This study aims to contribute to the existing literature that explores the impact of market concentration on bank efficiency in emerging economies. Using a sample of 225 banks in 18 countries in the Middle East and North Africa (MENA) region over the period 2006–2020, we empirically investigate the significance of this relationship. Since the evidence of concentration effect on efficiency during the COVID-19 outbreak is ambiguous, we test the hypothesis that the efficiency is positively affected by the level of banking market concentration in the MENA region. We adopt fixed effect model specifications and test the robustness of our results with the two-step Generalized Method of Moments (GMM) estimation technique. Our analysis finds a strong positive association between market concentration and bank efficiency. The analysis of different types of banking systems that co-existing in the MENA region  indicates the market concentration effect is more pronounced when the banking institution is Islamic and during the COVID-19 outbreak. Moreover, the better economic performance of Islamic banks during the initial stage of pandemic further increases their efficiency. Our analysis indicated that the impact of market competitive conditions on bank efficiency varies significantly across banks with different ownership structures and is more pronounced for government-owned banks. The results are robust using different model specifications and alternative estimation techniques. In this paper, we investigate the effect of market concentration on bank efficiency using a sample of 225 banks in the countries in the Middle East and North Africa (MENA) region. According to Kozak and Wierzbowska , the impEmpirical literature investigating the effect of banking market structure on efficiency provides conflicting evidence. While some studies report a positive impact on bank efficiency reflected in more favorable prices and higher income , 3 and/oRecently, a considerable number of studies have focused on assessing the impact of COVID-19 on the banking systems of different countries and/or regions –9. The eAnother strand of empirical literature has focused specifically on the performance and efficiency of Islamic banks during the COVID-19 pandemic. For example, Le et al.  investigOur study is important for advancing existing research on the MENA region in a few aspects. First, previous empirical studies provide inconclusive evidence on how banking market concentration affects the efficiency of different types of banking systems operating in the MENA region. To fill this gap, we focus our analysis on Islamic (IBs) and conventional banks (CBs), as well as banks with different ownership structures. While the role of different banking systems to the overall banking sector stability has been widely investigated, the differences in bank ownership structure have received much less attention. Therefore, our study is the first one to investigate the relationship between market concentration and efficiency across banks with different structure . Second, we extend previous studies by incorporating the COVID-19 pandemic effect in our analysis. The analysis of different types of banking systems that co-existing in the MENA region  indicates the market concentration effect is more pronounced when the banking institution is Islamic and during the COVID-19 outbreak.We perform our analysis using a panel dataset that covers data from 225 banks  in 18 MENA countries over 15 years (2006–2020). Following Sufian ).In this paper, we analyze the impact of market concentration on bank efficiency in the MENA region, incorporating the effect of the COVID-19 outbreak. We report a number of interesting results that have strong policy implications.First, our analysis reveals a positive association between market concentration and bank efficiency. The concentration thus creates favorable conditions for banks to increase their profit efficiency. However, the increased competition between concentrated banks can increase risk taking and decrease efficiency, which will harm the banking system’s financial stability. Our results remain robust to different alternative measures of concentration (the HH-index and CR3). Our findings align with the studies on bank efficiency in other developing countries  that co-exist in MENA and other developing regions. The empirical literature provides mixed evidence depending on the context: studies on individual countries report that IBs are more efficient than CBs and vice versa, whereas papers reporting cross-country evidence find no difference between the two types of banks. Our analysis reveals a strong differential effect for IBs. Specifically, market concentration effect on bank efficiency is more pronounced when the banking institution is Islamic. To test this notion, we split the sample into two groups (CBs and IBs) and repeat the baseline analysis separately for each group of banks. We find a similar (positive) impact of market concentration on the efficiency of either type of bank. However, the concentration effect is more pronounced during the COVID-19 outbreak only in the group of IBs. The positive sign of interaction term of the concentration measure (CR3 in this case) and the crisis dummy variable indicates that any increase in the concentration level during the COVID-19 outbreak intensifies IBs efficiency. As IBs show higher efficiency levels and stability than their conventional counterparts during the pandemic crisis see , IslamicFinally, there is limited empirical evidence of whether the relationship between market concentration and efficiency depends on the banks’ ownership structure. We contribute to this area by addressing the question of whether the concentration effect is similar for banks that are government-owned or have foreign ownership. Our analysis indicates that market concentration effect is strongly significant and positive for the government-owned bank but insignificant in the group of foreign-owned banks. One possible reason for this difference might be that foreign banks in the MENA countries suffer more from bad institutional framework in the host country than government-owned (domestic) ones. Moreover, the concentration effect is more pronounced for domestic Islamic banking institutions. This result somewhat supports the finding of  for MalaOur findings provide strong implications for bank managers, policymakers, and regulators in the MENA region. Specifically, the results related to IBs efficiency can guide bank managers on how to shape their strategies during the COVID-19 pandemic. Though our findings relate to the COVID-19 outbreak only, they provide guidance to the managers to enhance bank profitability because it is positively associated with bank efficiency level. Moreover, though bank managers are often driven by short-term results, the adoption of appropriate risk management strategy during the crisis times (such as COVID-19) that increase bank stability will allow, in the long term, to mitigate the institutional risk imposed by the various regulatory reform initiatives. An example of such initiatives are policies oriented to increase the level of concentration to improve the financial stability of the banking sector. However, policy makers and regulators should be cautious in implementing policies that increase market concentration without considering the potential negative effects on competition, consumers, and systemic risk. Therefore, regulatory authorities and policy makers concerned with improving financial stability in the MENA region should proceed differently depending on the level of concentration and the type of banking system. For example, they may adopt policies that prevent the further increase in banking size (in the case of CBs) through additional consolidation in the banking industry owing to the COVID-19 pandemic. Referring to IBs, as they show better efficiency and stability than their conventional counterparts during the recent crisis, increased concentration will most likely positively affect the efficiency of Islamic banks’ operations; therefore, these institutions can be entrusted with a more decisive and important role in the post-COVID-19 revival.However, the main limitation of our analysis is related to the fact that the effect of the global pandemic crisis on bank efficiency is analyzed using a limited period of one year (the last year of the sample period that coincides with the COVID-19 outbreak). Therefore, further investigation of the COVID-19 effect on bank efficiency and profitability is required using an extended period of global crisis impact. This will be the area of our future research.S1 Table(DOCX)Click here for additional data file.S2 Table(DOCX)Click here for additional data file.S3 Table(DOCX)Click here for additional data file.S4 Table(DOCX)Click here for additional data file.S5 Table(DOCX)Click here for additional data file.S1 Fig(DOCX)Click here for additional data file.S1 Data(XLSX)Click here for additional data file.S1 File(XLSX)Click here for additional data file.S2 File(XLSX)Click here for additional data file.S3 File(XLSX)Click here for additional data file.S4 File(XLSX)Click here for additional data file.S5 File(XLSX)Click here for additional data file.


Phyllodes tumor (PT) is an infrequent type of breast neoplasm, constituting a mere 0.5%–1.5% of the entirety of breast tumors. The malignant phyllodes tumor (MPT) comprises only 15% of all phyllodes tumors, and its transformation into rhabdomyosarcoma (RMS) is exceedingly rare in clinical practice. Given its insensitivity to chemotherapy and radiotherapy, treatment options for MPT patients are limited, leaving complete surgical resection as the only option. Therefore, it is imperative to investigate the effective utilization of the heterogeneous differentiation characteristics of MPT to expand treatment alternatives for these patients. In this case report, we represent a 13-year-old adolescent diagnosed with giant breast MPT with RMS differentiation and pulmonary metastasis. The initial step in the treatment process involved radical surgical resection, followed by the administration of four cycles of VDC/IC chemotherapy, which is widely recognized as the standard chemotherapy for RMS. Regrettably, the delay in initiating chemotherapy resulted in minimal observable changes in the size of the pulmonary metastatic nodule. Additionally, a comprehensive literature review on the characterization of MPT with heterogeneous differentiation was conducted to enhance comprehension of the diagnosis and treatment of this uncommon disease in clinical practice. Meanwhile, this case also reminds the doctors that when we diagnose a patient as MPT, it is crucial to consider its heterogenous nature and promptly initiate adjuvant treatment. By targeting the differentiation element of MPT, it becomes feasible to overcome the previously perceived limitation of surgical intervention as the sole treatment option. Phyllodes tumor (PT), classified as the fibroepithelial tumor of breast composing of epithelial and stromal elements, is a rare kind of pathological subtype in the clinical practice . The WorA 13-year-old female patient was initially referred to our hospital due to the presence of a large mass in her left breast, accompanied by nipple inversion  and positron emission tomography/computed tomography (PET/CT)  guidelines recommend the complete surgical resection with at least 1-cm margins without sentinel lymph node biopsy for the treatment of MPT. Surgeons may more likely perform breast-conservation operation instead of mastectomy for pediatric MPT patients considering their quality of life in the future , 36. HowDifferent from the dilemma of MPT, which mainly relied on the surgery, it has long been demonstrated that the treatment for RMS is multimodality. Surgery still takes the dominant role in the whole therapeutic strategy. Apart from surgery, RMS is sensitive to cyto-toxic chemotherapy and radiotherapy . VincrisFor metastatic RMS patients, radiotherapy is still disputed, as the authoritative classification of patient subgroups that can benefit more from the radiotherapy than others are absent and myelosuppression caused by radiotherapy may restrict the effect of chemotherapy . HoweverThe chemotherapy strategy for our patient was the four cycles of vincristine–doxorubicin–cyclophosphamide/ifosfamide–etoposide (VDC/IE) chemotherapy, which is the main chemotherapy strategy for the treatment of Ewing sarcoma family of tumors . FurtherIn this study, we present a case of an adolescent patient who was diagnosed with MPT with RMS differentiation, contributing novel perspectives on treatment approaches for these uncommon diseases. Pathology remains crucial in the diagnosis of MPT, and the integration of imaging examinations can aid in assessing the severity and monitoring the occurrence of relapse and distant metastases. The heterogeneous nature of MPT is of utmost importance in clinical practice, as it can significantly influence disease progression and guide therapeutic decision-making. As in the patient that we report in this case, both the biological feature of MPT and RMS should be taken into consideration for the clinical decision-making. Surgery with negative margin is critical to reduce the recurrence or metastasis and improve the overall survival for both the MPT and RMS patient. Adjuvant chemotherapy and radiotherapy are controversial for pure PT patients, but robust evidence has revealed that RMS patients will benefit a lot from such treatments. It is regrettable that the patient did not promptly receive adjuvant chemotherapy upon initial diagnosis of MPT with RMS differentiation. This serves as a reminder to medical professionals that MPT patients with RMS differentiation can also benefit from the multimodal treatment typically administered to primary RMS patients.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.Ethical approval was not required for the study involving human samples in accordance with the local legislation and institutional requirements. Written informed consent for participation in this study was provided by the participants’ legal guardians/next of kin. Written informed consent was obtained from the participant's legal guardian for the publication of this case report and any identifiable material contained.YZ designed the idea of the article. JL, YZ, and RY collected the patient’s clinical and pathological data. JL is the major contributor in writing the first draft of the manuscript. YZ and LG revised the manuscript. All authors contributed to the article and approved the submitted version.


Introduction: Lumbar disc arthroplasty is a surgical procedure designed to treat degenerative disc disease by replacing the affected disc with a mobile prosthesis. Several types of implants fall under the term total disc replacement, such as ball-and-socket, mobile core or elastic prostheses. Some studies have shown that facet arthritis can develop after arthroplasty, without much precision on the mechanical impact of the different implant technologies on the facet joints. This study aims to create validated patient-specific finite element models of the intact and post-arthroplasty lumbar spine in order to compare the mechanical response of ball-and-socket and elastic prostheses.Methods: Intact models were developed from CT-scans of human lumbar spine specimens (L4-S1), and arthroplasty models were obtained by replacing the L4-L5 disc with total disc replacement implants. Pure moments were applied to reproduce physiological loadings of flexion/extension, lateral bending and axial rotation.Results: Models with ball-and-socket prosthesis showed increased values in both range of motion and pressure at the index level and lower values at the adjacent level. The mechanical behaviour of the elastic prosthesis and intact models were comparable. The dissipated friction energy in the facet joints followed a similar trend.Conclusion: Although both implants responded to the total disc replacement designation, the mechanical effects in terms of range of motion and facet joint loads varied significantly not only between prostheses but also between specimens. This confirms the interest that patient-specific surgical planning using finite element analysis could have in helping surgeons to choose the appropriate implant for each patient. The management of degenerative phenomena of the lumbar spine and the resulting pathologies, such as radiculalgia and low back pain, represents a public health problem . Low bacTwo main surgical procedures exist to treat Degenerative Disc Disease (DDD), which are arthrodesis and arthroplasty. Only the latter can retain some of the natural mobilities of the spine. This is achieved by removing the degenerated disc and replacing it with a mobile prosthesis. Multiple studies have shown that arthroplasty represents a pertinent alternative to arthrodesis to treat DDD, and could provide an improvement of the quality of life to the patient over the longer term . VariousDespite the benefits of lumbar Total Disc Replacement (TDR) surgery, researches have demonstrated that 34% of patients may develop facet arthritis at the index level within 2 years of the surgery . Facet aThe objective of this work was to quantify the mechanical effects involved by a TDR on the facet joints according to the arthroplasty solution and the inter-subject differences. For this, patient specific FE models of the lumbar spine were developed to assess mechanical effects in pressure, sliding, and dissipated energy in the facet joints at the index and inferior adjacent level.The protocol used to carry out the study is detailed in the flow chart shown in 3 in size. A FE model was developed from the geometrical characteristics of each specimen including vertebrae and intervertebral discs, which were extracted by the means of 3D Slicer software  extracted from 2 male donors (age: 77 and 86 years old) were used , were modelled by uniaxial springs (COMBIN39 elements) assuming a non-linear behaviour , as showTo model the articular cartilages of the facet joints, cartilaginous endplates were placed in contact between the inferior and superior articular processes , 3D models of each prosthesis (Prodisc-L and LP-ESP) were created. Three families of lumbar arthroplasty prostheses exist , which cThe reference FE models (group 1) were modified to simulate the arthroplasty models . The pos- Group 1: reference models based on the native geometries of the lumbar spines- Group 2: lumbar spines implanted with a ball-and-socket prosthesis with 3 DoF - Group 3: lumbar spines implanted with an elastic prosthesis with 6 DoF 3 groups of 2 specimens leading to specific FE models were considered .- Group 40 simulations were conducted (20 for each specimen). For the reference models, pure moments of 7.5 Nm were applied to the upper vertebra while the lower extremity of the sacrum was fixed , whereas an increase was noted for group 3 (+107%).The dissipated energy in the facet joints for each model was analysed to evaluate the mechanical behaviour of the implants. Group 2 showed higher dissipated energy in the facet joints at the index level compared to groups 1 and 3, especially during flexion (+706%) and lateral bending (+16%). In contrast, a reduction was observed at the adjacent level, particularly during flexion (−68%), lateral bending (−35%), and axial rotation (−63%). Group 3 presented an increase of dissipated energy during extension and axial rotation (respectively +270% and +54%), whereas a reduction was observed during flexion (−61%) and lateral bending (−71%). At the adjacent level, the behaviour was similar to that of group 1 for each movement.This study used FE analysis to show that for the same TDR implant designation, the mechanical effects in terms of ROM and facet joint loads can vary greatly not only between different TDR designs, but also among different patients. These findings highlight the potential benefits of using patient-specific FE analysis to assist surgeons in selecting the most appropriate surgical solution for each patient.Most FE studies of the lumbar spine focus on ROM , on intrThe stiffness of the models was found to be higher than that reported in most studies, in particular for flexion-extension movements . This stin vivo studies could be envisaged to understand the acceptable level of increased loads for facet joint cartilages. It would be interesting to define a threshold of stress that increases the risk of facet joint arthritis, which could have important implications for the development of prostheses and surgical planning.Although all TDR implants were intended to treat the same indication, the mechanical behaviour of different implant types varied significantly. The ball-and-socket prosthesis (Prodisc-L) appeared to increase the ROM and the loads at the index level, while preserving the adjacent level, which is consistent with the results of previously published studies . TherefoThis study presents some limitations, the first of which consists in the fact that the validation of the FE models presented in this work were only performed by comparison of the computed ROM to previous kinematic data presented in the literature. To improve this, experiments could be done on the specimens to assess their real behaviour, allowing for a specimen specific validation by a coupled approach of experimental and numerical testing. Also, it would be interesting to validate the computed pressure results by inserting pressure sensors in the facet joints of the real specimens. However, this method would be very invasive and could be difficult to perform.Specific models were developed from CT scans. However, it was not possible to accurately construct facet joint cartilage. For future studies, it would be interesting to have access to an MRI facility with sufficient resolution to construct accurate cartilage surfaces and combine MRI and CT data to generate a complete patient-specific model.Furthermore, elastic behaviour was assumed to model the intervertebral discs, whereas most current tend to model the discs with hyperelastic behaviours . Xie et Another limitation of this work is that the results are valid only under the assumption of perfect stability after bone remodelling around the prosthesis, which may not always be the case in clinical practice due to different efficacy of the anchoring systems and physiological differences between patients.In addition, this work focused only on the effect of arthroplasty on the index level and the inferior adjacent level. The same methodology could be applied to perform the same analyses on the superior adjacent levels.Also, these models could be modified to consider more types of spinal implants. Indeed, it would be interesting to determine the effects on the facet joints of mobile core prosthesis, which correspond to the third family of arthroplasty implants, or of implants destined to other types of surgeries, such as arthrodesis cages or posterior stabilisation devices based on pedicular screws.Finally, this study did not investigate the effects of antero-posterior misalignment of the different implants according to specimen geometry. It has been shown that this can significantly influence the results  but it wIn this work, we developed patient specific FE models to analyse mechanical effects linked to arthroplasty in lumbar levels. Elastic prostheses seem to be a promising option for arthroplasty due to their mechanical behaviour similar to a disc in particular, in case of degenerated discs and relatively stiff spinal units. On the other hand, for patients without arthrosis disease, ball-and-socket prostheses reduce loads at the lower adjacent level and increases ROM at the index level. These findings confirm the contribution of a surgical planning built from a patient-specific FE analysis. FE models integrating patient characteristics  could provide quantitative data to surgeons to optimise the choice of the implant. Further research coupled with clinical observations would be needed to determine the long-term effects of these implants on adjacent and surgical spinal segments, as well as to explore other potential solutions that balance the benefits of increased mobility and reduced loads.


MDSCs consist of two main subsets: polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) and monocytic myeloid-derived suppressor cells (M-MDSCs) . In miceLy6Chigh . In humaIn addition to phenotype, immunosuppression is the major characteristic of MDSCs, which makes them different from mature monocytes and neutrophils. MDSCs can directly suppress T-cell response by releasing high levels of suppressive molecules. MDSCs can also indirectly inhibit the immune response by inducing regulatory T cells (Tregs), promoting the differentiation of T helper 17 (Th17) cells, and inhibiting the activation of natural killer (NK) cells , 5. MoreAccumulation of MDSCs takes place alongside the same differentiation pathways as for granulocytes and monocytes. Multiple molecules contribute to the accumulation of MDSCs, and these molecules can be further divided into two groups, which are responsible for MDSC expansion and activation, respectively . In the The goal of this Research Topic is to provide a forum to advance research on the accurate mechanisms that epigenetic modifications induce the changes in MDSC biology, as well as explore the clinical application prospect of epigenetic therapy targeting MDSCs in individuals with cancer or autoimmune disease. We focus on: (a) Mechanisms of epigenetic modifications that induce the changes in MDSC differentiation and function; (b) Clinical applications of epigenetic therapy targeting MDSCs; (c) Inducers of the epigenetic modification in MDSCs; (d) Cell biology changes of different MDSC subsets; (e) The influence of epigenetic modification in MDSCs on the intercellular interaction.Xu et al. provide a detailed summary of the current research on the regulatory roles of DNA methylation, histone modifications, and non-coding RNAs in the development and immunosuppressive activity of MDSCs, and further summarize the distinct role of MDSCs in the pathogenesis of autoimmune diseases, to provide help for the diagnosis and treatment of diseases from the perspective of epigenetic regulation of MDSCs.In this collection of articles, Xu et al. summarize the crosstalk between the epigenetic alterations and MDSC functions and briefly introduce how the accumulation and function of MDSCs caused by epigenetic modification impact the disease development, which represents a promising therapeutic strategy for the related disorders.Zulqarnain et al. assess the effectiveness of endoscopic retrograde appendicitis therapy (ERAT) as a new technique and method for chronic fecalith appendicitis complicated by active ulcerative colitis. They find that ERAT can be seen as a different approach and be favored as a safer and more effective option in treating UC patients with appendicitis, especially those who are later in the course of the disease. Because of the ERAT procedure, such cases can avoid surgery and surgery-related complications.Zhao et al. demonstrate the existing studies of MDSCs in IBD reporting either its pro-inflammatory roles or anti-inflammatory roles, along with the application of MDSCs targeted therapies in IBD. The rich diversity of topics discussed in this Research Topic is an indication of the many emerging roles of epigenetic modifications in MDSCs.The authors contributed equally and in mutual agreement to the reviews of the submitted manuscripts and the writing of the editorial. All authors contributed to the article and approved the submitted version.


Understanding the developmental changes that affect neurons is a key step in exploring the assembly and maturation of neural circuits in the brain. For decades, researchers have used a number of labeling techniques to visualize neuronal morphology at different stages of development. However, the efficiency and accuracy of neuronal labeling technologies are limited by the complexity and fragility of neonatal brains. In this review, we illustrate the various labeling techniques utilized for examining the neurogenesis and morphological changes occurring during the early stages of development. We compare the advantages and limitations of each technique from different aspects. Then, we highlight the gaps remaining in our understanding of the structure of neurons in the neonatal mouse brain. RealistLabeling methods can be broadly divided into two categories: traditional markers, such as fluorescent dyes, proteins, and bacterial toxins , and genin utero electroporation (IUE) may lead to embryonic death  is one of the earliest markers used in the morphological study of neuronal axons and is still being used in labeling neonatal axons  are commonly used markers  that can2.3.Single-cell injection of traditional chemical tracers can achieve the goal of targeting specific individual neurons in neonatal mouse brains . AnterogChemical tracers are diverse, highly sensitive, and can be transported retrograde or anterograde by being attached to different vectors at different rates . However3.3.1.Neurotropic viruses are widely used vectors for labeling neurons in young mice. As the first viral tracers used to label the soma of the neonatal mouse, retroviruses can permanently integrate the genome they carry into host neurons after mitosis, achieving a long-term and stable fluorescent signal . DespiteAdeno-associated viruses (AAV) have the advantages of versatility and multiple serotypes, rendering them a popular tool in the field of neuroanatomy . A viralViral tracers are a popular tool in the field of neurodevelopment. Nevertheless, there are still several limitations associated with the application of viral tracers in neonatal mouse brains. Only a few studies have revealed details of the morphological development of neurons during the early postnatal period using viral tracers , as it g3.2.Transgenic mice provide an option for non-invasive labeling. A wide variety of transgenic mice can be generated by prokaryotic injection, bacterial artificial chromosomes (BACs), or knock-in techniques. In the study of neuron lineage tracing, transgenic mice have been generated to target specific types of neurons that develop after embryonic development .in vivo and has been used in the tracing of neuron lineages -mediated interchromosomal recombination. Transgenic mice used for lineage tracing with the MADM  is a popular labeling method that has been in development since 2001 (nce 2001 . Gene vence 2001  or hipponce 2001 . As the nce 2001 . In thisnce 2001 . Howevernce 2001 .in utero electroporation (PASME) system  system  utilizes) system .It is vital that we discover what links the different types of morphological changes that occur in the basic unit of signal transmission in the brain, the neuron, with the connections and functions of complex neural circuits. The development of genetic engineering technology provides abundant options for scientists to track changes to the morphology of neurons during the developmental period . Genetic4.The development of neurons is a critical step in the establishment of precise neural circuits. Over the past several decades, a variety of labeling techniques have been invented that allow us to visualize the morphology of neurons as they develop. Thus, researchers have found that different neurons form distinct structures and exhibit different dynamics. However, current labeling techniques do not yet satisfy the need to track all types of neurons from their formation in the embryonic stage to maturation in adulthood.Adjustments to surgical protocols and the optimization of equipment continue to improve the utility of labeling technology. For IUE, triple-electrode probes have been developed to greatly extend the range of suitable transfection areas . Dual IUOne major main technical barrier to overcome in this field is our ability to balance the long-term stable expression of markers with the sparse labeling of specific neurons during different development stages. Usually, the insertion and expression of foreign genes takes a certain amount of time, which may result in us missing the short time window for the optimal observation of developing neurons. For example, AAV does not express strong enough signals until a few weeks after injection. To accelerate the expression of labeling signals, especially during the early postnatal period, transgenic systems can be updated by increasing the number of gene copies encoding fluorescent proteins or developing more efficient sparse labeling constructs. The Brainbow system can be employed to label individual neurons with distinguishable colors through the stochastic expression of several fluorescent reporter transgenes, and neurons expressing a particular color thus share a common lineage . With fuin vitro until dyes with higher biocompatibility and in vivo imaging techniques were invented. Nowadays, technologies such as intracranial multiphoton microscopy and head-mounted microscopes offer us the ability to observe the development of living animals in real-time. Secondly, the retention of precise fluorescence signals in neurons within intact brains provides more possibilities for scientists to conduct the anatomical dissection of neural systems and even study the fine morphology of individual neurons  declare financial support was received for the research, authorship, and/or publication of this article. This work was financially supported by STI2030-Major Projects (no. 2022ZD0205201), National Nature Science Foundation of China (no. T2122015), CAMS Innovation Fund for Medical Sciences (no. 2019-I2M-5-014), and the Hainan Provincial Natural Science Foundation of China for High-level Talents (no. 821RC531).The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Severe ankylosing spondylitis (AS) frequently involves hip joints and, occasionally, presents with concurrent spinal deformities, such as kyphoscoliosis, creating complex challenges for surgical management.We present a 26-year-old Persian male with a history of AS and severe kyphoscoliosis, leading to bilateral hip fusion and immobility. Following spinal deformity correction, a one-stage bilateral conversion to total hip arthroplasty (THA) was conducted through the direct anterior approach.Primary correction of spinal deformities allows for extended surgical procedures under general anesthesia. Single stage bilateral hip conversion arthroplasty via the direct anterior approach enhances postoperative mobilization, reduce the risk of re-ankylosis, and improve the overall quality of life for AS patients with this unique presentation. Ankylosing spondylitis (AS) is an inflammatory rheumatic disease belonging to the group of spondylarthritis, mainly involving axial skeleton and inflammation of the joints presenting initially with inflammatory low back pain in most of the cases . AS clasHip involvement in AS reported to happen in about one-third to half of the cases, and in most of them this involvement is diagnosed in bilateral hip ankylosis . ConversHowever, simultaneous presence of AS and spine deformities like kyphoscoliosis is a relatively rare phenomenon reported in studies, with almost none of them targeted to repair the hip fusion –15. In tA 26-year-old Persian male patient was referred to our tertiary orthopedic surgery center with chief complaint of bilateral pelvic pain since a couple of months ago. The patient had a history of diagnosed AS and thoracolumbar kyphoscoliosis. The drug history of patient included only sulfasalazine 2 g/day PO divided BID for the treatment of AS. No other specific past medical history was present. Patient had no history of smoking or drug abuse. Family history was unremarkable specifically regarding the rheumatologic conditions..On the physical examination, the patient was thin and an apparent kyphoscoliosis was observed. Also, the range of motion (ROM) of the hip joints bilaterally was severely limited that made walking almost impossible for patient. Also, the kyphoscoliosis made placing the patient in the supine position not possible in any way Fig. .Fig. 1Pa. Further evaluation with computed tomography (CT) scan and 3D reconstruction confirmed ankylosed hips in their respective anatomical locations .Pelvic X ray revealed bilateral fused hips and bamboo spine Fig. . FurtherIn according to the potential surgical and anesthetic risks associated with performing total hip arthroplasty (THA) in patients diagnosed with AS, a comprehensive consultation with the patient led to the decision to choose a one-stage conversion of bilateral hip fusion to THA. To optimize the surgical procedure, the direct anterior approach (DAA) was chosen as the preferred method. In preparation for this conversion, the patient was initially referred to a spine specialist to address the underlying spine deformity, thereby enabling the patient to assume a supine position during the THA procedure. After nine months following the spinal surgery, the patient underwent readmission for a one-stage bilateral hip conversion arthroplasty via the DAA. This approach allowed for the simultaneous performance of both hip surgeries, promoting enhanced postoperative recovery and facilitating quicker mobilization for more efficient restoration of hip joint function..To perform the conversion arthroplasty, the hips were approached using the DAA in a single-stage surgery. The surgical approach involved utilizing the intermuscular plane between the Sartorius muscle and the tensor fascia lata. after reaching the joint two cuts were made utilizing an oscillating saw, one in the basicervical region , and the other in the subcapital region (the confluence of the neck and ileum) Fig. .Fig. 4A .After the removal of the bone block, we proceeded with the surgical placement of the acetabular cup and femoral stem with precision. During acetabular reaming, particular attention was paid to ensure the correct version, inclination, and medialization of the components. Given the significant muscle atrophy observed in this case, we assessed the feasibility of using a larger cup size to accommodate a larger femoral head. Post-operative radiographic assessments confirmed the proper anatomical positioning and version of the prosthesis components Fig. .Fig. 5PoThe patient was suggested to walk using a pair of crutches for a duration of two months, while maintaining full weight bearing. Also, the patient was warned about hip deep flexion with internal rotation, and hyperextension with external rotation of the hip for six months after surgery to reduce the possibility of dislocation.Patient was followed up for 12 months. He started to walk independently and acceptably at the end of the follow-up period and experienced an uneventful period after surgery.This study shows the surgical management of a challenging case involving ankylosed hips on both sides in a patient with AS and kyphoscoliosis. The patient underwent a successful single-stage surgery to convert both hip fusions using the DAA approach. The results have been promising during the follow-up period and are encouraging for the long-term prognosis.Anesthesia administration in AS cases poses significant challenges, primarily attributed to limitations in patient positioning caused by severe axial skeleton stiffness and spinal rigidity. These factors not only hinder patient mobility but also restrict respiratory capacity , 17. ThiIn our search of literature, only a few studies have reported performing surgeries on such cases and none of them were on surgical repair of fused hips due to AS. Here we review the presentations and findings of those cases and studies to provide a bigger picture of the patient management in these cases.In a study by Kuwaijo and colleagues on a 58-year-old man with AS and severe kyphoscoliosis who was diagnosed with prostate carcinoma, the surgeons placed the patient under general anesthesia in the supine-Trendelenburg-Lithotomy position and performed the robot-assisted radical prostatectomy and this way they could overcome the complex state of the patient and the surgery was successful . The secIn a published series of four cases with AS complicated by congenital spinal deformity, with one case having lumbar kyphosis, one case having thoracic kyphosis, one case having decreased L5 vertebral body height, and one case having thoracolumbar kyphoscoliosis, only one patient underwent poly-segmental osteotomy and fixation of spine and the others were managed by only medications, and none of the cases has evidence of hip involvement at the stage of their presentation with lower back pain and stiffness . AnotherSpeaking of complications, evidence in the filed show that AS patients with and without spinal deformities are at higher risk of post-operative adverse effects and complications which need appropriate consideration and management. A systematic review of available literature on the bilateral THA conversion surgery in AS patients found that this treatment is safe and effective in repair of hip fusion in these cases; however, the technical obstacles exist in their surgery and the risk of post-operative complications are significant including intra-operative fracture, nerve injuries leading to paresis and palsy, hip dislocation, the need for revision surgery mainly due to aseptic loosening, and the serious issue of development of heterotopic ossification after surgery and the risk of re-ankylosis if the primary disease of AS is not well under control . Other iPerforming the single-stage bilateral conversion THA surgery via DAA in the case presented in this study was a strength of our approach which enabled earlier patient mobilization and rehabilitation. Studies show bilateral THA for severe hip ankylosis in AS cases is an efficient method to regain the hip joint function, relieve the pain, and improve the patient quality of life . AnotherAS complicated by spinal deformities like kyphoscoliosis is a challenging situation for any surgery, specifically in case of hip involvement in the form of ankylosis and hip fusion, as spinal deformity poses a major obstacle against anesthesia and essential maneuvers during surgery. A primary correction of the spinal deformity provides the chance for performing longer surgeries under general anesthesia and a single-stage bilateral hip fusion conversion to THA facilitates patient mobilization and recovery. Also, performing the conversion arthroplasty via the direct anterior approach brings up the chance of hip conversion in both sides in a single surgery so the patient mobilization could be quicker. Choosing a proper treatment plan for patients with simultaneous AS and kyphoscoliosis needs a by-case decision making process and approach to reach the maximum benefits for the improvement of patient’s quality of life.


The eastern African Oldowan has been documented in multiple raw material contexts and physical environments and displays considerable differences in terms of technological complexity. The relative influence of percussion techniques and raw material quality are central to debates concerning hominin skill levels as a potential driver of change during the period between 2.6 and 2 million-years (Ma). The early Oldowan assemblages from the Shugura Formation play a key role in these debates due to a number of distinctive features, including the small size of the artefacts and poorly controlled flaking. Here we mobilize quantified and replicable experimental data in order to (a) assess the significance of the bipolar technique in the Omo archaeological assemblages and (b) discriminate the respective impact of raw materials, technical choices and knapper skill levels on the unique character of these assemblages. By combining descriptive statistics with regression tree models, our analysis demonstrates knapper skill level to be of minimal importance in this context for the production of sharp-edged flakes. The absence of a link between skill and knapping success reflects the combined effect of raw material constraints, the frequent use of the bipolar technique, and relatively simple technical objectives. Our analysis confirms the key role played by local environmental conditions in the unique appearance of the Shungura assemblages, a relationship which has been frequently suggested but never demonstrated. Beyond the operational and sensorimotor skills considered in most studies, we suggest that the diversity of early Oldowan assemblages should be better sought in the cognitive abilities developed by early toolmakers as a response to landscape learning and use, two elements of early human evolution that remain largely unexplored. The Oldowan (ca. 2.6 to 1.7 Ma) lithic assemblages of eastern Africa share a simple yet effective core-flake technology for the production of what are generally unmodified sharp-edged flakes . These aRaw material constraints are the main factor held to explain the singularity of the Shungura assemblages –20. All The use of bipolar percussion in the Shungura assemblages was first noted by Chavaillon for a core fragment from Omo 123k , and equInferences regarding the degree of technical skill and dexterity of the Shungura toolmakers are even more controversial. The exploitation of minuscule cores and flakes has been interpreted as reflecting an advanced degree of grip precision and manual dexterity , 37. TheIn sum, each of the factors advanced to explain the unique character of the Shungura assemblages has been the subject of diverging interpretations. These contrasting views are deeply rooted in research paradigms and fostered by a drastic lack of solid analytical data. The diminutive size of the Shungura assemblages is clearly related to the small size of the available pebbles in the Lower Omo Valley, which, combined with the variable quality of the pebbles, required adaptive solutions from the toolmakers. One of the most common solutions is the use of bipolar percussion, extensively documented in quartz assemblages around the world and from all periods of prehistory . HoweverThe question of knapper skill level is addressed here based on experimental reduction sequences produced by modern knappers with highly contrasting experience. “Skill” is a generic term that encompasses a large variety of distinct notions. For the present analysis, we make a distinction between (a) cognitive skills, i.e. knowledge, (b) operational skills, i.e. know-how, and (c) sensorimotor skills, including precision grip, striking accuracy, and control of percussive force –45. We fThe majority of raw materials exploited by the Shungura toolmakers are vein quartz pebbles , i.e. clTwo technical choices are considered in our analysis: free-hand and bipolar knapping, two percussion techniques implying radically distinct motions and implements . The freThe Shungura lithic assemblages are the result of the reduction until exhaustion of small unprepared quartz pebbles for the production of sharp-edged flakes that did not require modification prior to use. This functional requirement, which is common to all early Oldowan assemblages, underlies the choice of variables included in the analysis. These variables relate exclusively on the absence / presence and extension of cutting edges, which we consider as the most relevant proxies for assessing the success of the knapping sequence. Our analysis takes into account three independent variables: proportion of angular fragments, proportion of sharp-edged flakes and extension of the cutting edges on the sharp-edged flakes. Angular fragments are by-products devoid of sharp (i.e. cutting) edges, lack a platform, and bear no identifiable ventral or dorsal surface indicative of a controlled detachment. Sharp-edged products include all flakes and broken flakes with effective cutting edges for penetrating soft tissue, defined here as an edge angle ≤ 70°, and maximum length > 2 cm. The proportions of angular fragments and sharp-edged products are calculated in relation to the total number of products extracted from each pebble, and are therefore unaffected by variations in pebble size. The extension of the cutting edges is calculated as the ratio cutting edge length (mm) to the overall circumference of the piece (mm). This ratio is preferred to other values, such as the length of cutting edge alone  or flakein situ position. The first two assemblages derive from excavations carried out in the 1970s by the IORE team [The presence and significance of the bipolar technique is estimated in five archaeological assemblages from Member F, dated to between 2.324 ± 0.020 and 2.271 +/- 0.041 Ma , 14. TheORE team , 19, 20,ORE team .The replication of stone-tool assemblages for addressing issues related to quartz and/or bipolar knapping , 47–51 phttps://doi.org/10.34847/nkl.3e292r29).The experimental assemblage was produced during two working sessions, in the field in 2010 and in France (Pôle Mixte de Recherche de Campagne) in 2011. They involved four novice knappers (i.e. experimenters who had never practiced stone knapping before), and one experienced knapper (MB), who routinely reproduce stone tool technologies for over twenty years and has mastered all Early Stone Age technologies. The novices were given basic training before they started, including the mechanical constraints and principles for the detachment of flakes using both bipolar and free-hand techniques. Each pebble was reduced using a single technique, either bipolar or free-hand, and for the sole purpose of obtaining as many sharp-edged products as possible, until the core was exhausted. The raw materials were quartz pebbles from the Lower Omo Valley , selecteU tests were performed to assess the impact of each factor on these variables for the 37 knapping sets presented in The isolated influence of each of the three factors  was considered in the experimental dataset for each of the three quantitative variables described above. Since the first two variables  apply to pebbles, Wilcoxon-Mann-Whitney In a second step, regression trees , a speciThe only pattern which is exclusive to the bipolar technique is the production of flakes and broken flakes with double impact points produced simultaneously during flake detachment from the struck platform, and by a counterblow from the opposite edge of the core in contact with the anvil . AlthougThese strong contrasts in the use of the bipolar technique undermine the idea that the Shungura toolmakers did not have any other technical choice to reduce the rounded quartz pebbles in the Lower Omo Valley, as suggested by Ludwig . FurtherIn order to assess the relative impact of raw material quality, knapping technique and skill levels on the selected variables, each factor was successively explored via descriptive statistics, complemented by the information provided by regression trees.U tests provide some evidence against the null hypotheses of no impact of raw material quality and knapping technique on the proportion of angular fragments (p ≈ 0.051 and p ≈ 0.021 respectively). Conversely, knapping skill appears to have no influence on the proportion of angular fragments (p ≈ 0.771). Accordingly, percussion technique appears to be the most discriminating factor for the proportion of angular fragments in the regression tree . The predominant influence of raw material quality on the proportion of sharp-edged flakes is also illustrated by the regression tree (p ≈ 0.31). All statistical data point to a weak impact of all three factors on the proportion of flakes with cutting edges. This likely results from either insufficient sample size, in particular for the free-hand reduction sequences on low-quality pebbles, or the unpredictability inherent in quartz pebbles from the Lower Omo Valley for detaching sharp-edged flakes, independent of technique and knapper skill.As regards the proportion of sharp-edged flakes, the boxplots  show quiion tree , where kp ≈ 0.023, p ≈ 0.031 and p ≈ 0.011 respectively; see The free-hand technique produces sharp-edged flakes and broken flakes with more extensive cutting edges, a trend which is even more evident among flakes produced from high-quality pebbles or by expert knappers . AlthougWhen all variables are taken into account, knapper skill level impacts successful reduction sequences only in combination with one or both of the other factors, and always to a lesser degree. The combination free-hand technique / good quality pebbles / high skill level is most efficient in minimizing the proportion of angular fragments, while free-hand technique / high skill level is the best combination for more extensive cutting edges. The unexpectedly higher ratio of sharp-edged flakes produced by the novice knappers tends to confirm the non-decisive character of knapper experience when considered alone. By contrast, knapping technique appears to be the most determinant factor for successful reduction sequences, with a marked advantage for the free-hand over bipolar technique. This raises questions concerning the potential advantages of the bipolar technique for the Shungura toolmakers.Unlike previous descriptions of the Shungura Member F assemblages as technologically uniform , 18, 19,Given that the bipolar technique is often found in association with the free-hand technique in the Shungura assemblages, and sometimes even in lower proportions, the bipolar technique may have been an alternative or complement to the free-hand technique. The most parsimonious explanation is that bipolar percussion was used for quartz cores that were too small to be struck in the hand, either from the beginning of the knapping sequence or at an advanced stage of core reduction, as evidenced in other contexts . TechniqRaw material knapping quality is an aspect largely neglected in studies dedicated to the characterization of Oldowan raw materials, which mainly focus on raw material sourcing and selection –68, withThe influence of raw material and/or technique overshadows the relative impact of knapper skill level. This low visibility is due to the limited technical skills required for producing sharp-edged products following a simple core-flake technology without any structured method. Minimal oral instruction coupled with a very basic demonstration were sufficient for the novice knappers involved in our experiments to fulfill the defined objectives almost as well as the experienced knapper. It has also been stressed that not all raw materials have the same potential for identifying knapper skill levels . This paThe low potential of the Shungura assemblages for assessing knapper technical skills should thus be seen as the combined effect of raw material constraints, a frequent use of the bipolar technique and basic technical objectives. Therefore, direct comparisons derived from technological data between the Shungura assemblages and pene-contemporaneous Oldowan assemblages are unlikely to reveal distinct skill levels. This does not mean that such differences did not exist, but rather that they are impossible to identify. This contrast is particularly evident with Lokalalei 2c, which is only about 100 km to the south in the Nachukui Formation and characterized by the controlled detachment of flakes by means of a unifacial free-hand flaking method , 67, 70.The mechanisms underlying the diversity of the early Oldowan assemblages therefore appear to be more linked to the cognitive skills of the toolmakers, cognitive skills which we dissociate from the technical skills considered in this study. These include a set of techno-economic behaviors based on environmental knowledge, including patterns of land-use, group mobility, raw material procurement and processing, problem-solving abilities and tool-using activities. Such aspects have remain under-explored in the Shungura Formation , 71 and Several conclusions can be drawn from our analyses of the Shungura early Oldowan archaeological and experimental assemblages.The combination of descriptive statistics and regression trees provides a powerful tool for disentangling the relative impact of the main factors influencing the nature and composition of prehistoric lithic technologies. Applied here to the question of the factors involved in the diversity of the early Oldowan, this approach might be highly relevant in all studies involving multi-causal relationships;The sensorimotor and operative skills reflected in the early Oldowan assemblages from the Shungura Formation cannot be directly assessed based on standard quantitative proxies, which are highly raw material and technique dependent. This, of course, directly questions most implicit or explicit assumptions suggested in previous works regarding the skill level of the Shungura toolmakers;The specific environmental constraints  of the Lower Omo Valley heavily influence the technical elaboration of the Shungura assemblages. The considerable impact of these environmental settings suggests that patterns of diversity in hominin behavioral skills are better sought in landscape knowledge and use.S1 File(PDF)Click here for additional data file.


An important step towards improving performance while reducing weight and maintenance needs is the integration of composite materials into mechanical and aerospace engineering. This subject explores the many aspects of composite application, from basic material characterization to state-of-the-art advances in manufacturing and design processes. The major goal is to present the most recent developments in composite science and technology while highlighting their critical significance in the industrial sector—most notably in the wind energy, automotive, aerospace, and marine domains. The foundation of this investigation is material characterization, which offers insights into the mechanical, chemical, and physical characteristics that determine composite performance. The papers in this collection discuss the difficulties of gaining an in-depth understanding of composites, which is necessary to maximize their overall performance and design. The collection of articles within this topic addresses the challenges of achieving a profound understanding of composites, which is essential for optimizing design and overall functionality. This includes the application of complicated material modeling together with cutting-edge simulation tools that integrate multiscale methods and multiphysics, the creation of novel characterization techniques, and the integration of nanotechnology and additive manufacturing. This topic offers a detailed overview of the current state and future directions of composite research, covering experimental studies, theoretical evaluations, and numerical simulations. This subject provides a platform for interdisciplinary cooperation and creativity in everything from the processing and testing of innovative composite structures to the inspection and repair procedures. In order to support the development of more effective, durable, and sustainable materials for the mechanical and aerospace engineering industries, we seek to promote a greater understanding of composites. With its ability to provide a strategic advantage in the design and development of high-performance structures, composite materials have become a fundamental component in the advancement of mechanical and aerospace engineering. These materials are complicated due to their heterogeneous compositions, which necessitates a deep comprehension of their inherent properties ,2,3,4,5.Beyond the lab, material optimization is being investigated to satisfy the demanding requirements of aerospace applications, where every gram matters. When maintaining or minimizing the overall weight, engineers work to improve mechanical properties including toughness, fatigue resistance, and thermal stability. Modern manufacturing techniques, such as additive manufacturing, which enables the creation of components with intricate geometries and optimal material distribution, are used to achieve this equilibrium ,14,15,16There are challenges in integrating composites into the current industrial frameworks. When switching to composites from traditional materials, assembly methods, testing procedures, and maintenance protocols must all be reevaluated. To ensure that composite materials perform reliably in engineering applications, new joining, inspection, and repair methods are being developed to accommodate their unique characteristics ,20,21,22The environmental impact of composite materials is an issue that spans the entire lifecycle, from raw material extraction to end-of-life disposal or recycling. The development of sustainable composites, which includes the use of bio-based resins and recyclable fibers, is a growing field of research. These materials aim to reduce the environmental footprint of composites while maintaining their high-performance characteristics ,28,29,30Multiscale modeling has become an indispensable tool in the study of composites, bridging the gap between molecular-level interactions and macroscopic properties. This approach allows for the simulation of composite behavior across different scales, providing insights into how changes at the nano- or microscale can influence the overall performance of the material. Multiscale models are particularly useful in predicting the mechanical responses of composites under complex loading conditions, informing the design process, and enabling the optimization of material properties ,32,33,34In the broader context, the development of composites is not just a technical endeavor, but also a strategic one. The ability to tailor materials to specific applications opens up new possibilities in design and functionality. As the field of composites continues to mature, it promises to redefine the boundaries of what is achievable in aerospace and mechanical engineering, driving innovation and performance to new heights. The articles on this topic delve into the synergistic effects of these technologies on composite performance, offering insights into how they can be harnessed to meet the specific demands of aerospace and mechanical engineering.Aerospace. This research addresses the critical issue of damage tolerance in aeronautical composite structures, particularly focusing on the behavior of stiffened carbon fiber reinforced polymer (CFRP) panels under compression after impact. The study aims to understand the residual strength of these panels when they have sustained damage, which is essential for compliance with damage tolerance requirements in the aerospace industry. The paper details the development of a stiffened specimen for the VERTEX multiaxial test rig, which is a step towards evaluating the damage tolerance of stiffened structures under combined loadings. The specimen design was informed by virtual testing to ensure it would exhibit the desired damage phenomena, specifically the debonding of the stiffener from the center as the first mode of failure. The research involved manufacturing three samples and subjecting them to low-velocity impacts at various locations and energies, followed by compression testing to the point of stiffener debonding under a post-buckling regime of the skin. The results of the tests, including force fluxes and global strains, were obtained from in situ stereo-correlation, showing that different impacts resulted in different types of damage but similar residual strength. This work contributes to the broader understanding of the damage tolerance behavior of stiffened composite structures and their post-buckling capabilities, potentially allowing for more efficient sizing and mass reduction in composite panels.Contribution 1 is encapsulated in the article from the journal Applied Sciences. This work investigates the aerodynamic and structural design of fairings for vehicles, employing the Rankine half-body theory for aerodynamic design—a theory commonly used for aircraft gas turbine engine inlets and turboprop nose cones. The structural design leverages glass fabric composite materials, analyzed under aerodynamic design loads to ensure structural safety. The research culminates in the manufacturing of the fairing using the resin transfer molding method, with the final design being reviewed for its compatibility with existing vehicles and confirmed for safety. The study contributes significantly to the field by applying aircraft drag reduction techniques to commercial vehicles, aiming to improve fuel efficiency and reduce environmental impact. It also addresses the gap in research regarding the overall structural safety and lightening of fairings compared to existing structures.Contribution 2 is encapsulated in an article from the journal Materials. This research delves into the dynamic behavior of sandwich beams that incorporate PMI foam cores when they are subjected to low-velocity impact loading. The study is particularly focused on understanding how these beams sustain and transfer loads upon impact, which is crucial for applications in aerospace, marine, and other engineering fields where such materials are often used due to their advantageous mechanical and physical properties. The paper outlines the experimental procedures used to assess the performance of the sandwich beams under both quasi-static and dynamic loading conditions. Different types of PMI foam cores were tested to analyze the influence of core density and face sheet thickness on the load-sustaining and transfer mechanisms. The experiments involved clamping the beams and subjecting them to impacts at varying velocities to measure the impact force using an accelerometer. The results demonstrated that the impact force and duration increased with the thickness of the face sheet and the density of the core. Moreover, the study observed a transition in failure modes from shear to tensile, attributed to the strength ratio between the bottom face sheet and the core. The findings of this research contribute to a better understanding of the dynamic deformation mechanisms of sandwich beams with PMI foam cores, which is essential for designing more resilient structures in various engineering applications.Contribution 3 is encapsulated in the article from the journal Contribution 4 is detailed in the article from the journal J. Compos. Sci. This study explores the blast mitigation performance of sandwich panels by examining various design parameters and core geometries. The research compares three core designs—honeycomb, mushroom, and tubular—to assess their effectiveness in resisting blast loads. The study also considers the impact of plate thickness and the spacing between core structures on the panels’ performance. Using finite element analysis, twenty-seven numerical experiments were conducted. The results were then evaluated through regression analysis. The findings indicate that the tubular sandwich panel exhibited the least deformation and damage while contributing to the highest kinetic energy dissipation. Conversely, honeycomb core structures recorded the highest internal energy dissipation, but also the most deformation and damage. Despite these differences, the study found that core shape and spacing were less influential in resisting blast loads compared to plate thickness, which emerged as the most significant factor.Materials. The study focuses on the optimization of heat treatment conditions for accurately measuring the resin content in CFRP and glass-fiber-reinforced plastic (GFRP) used in construction. The method of thermal gravimetric analysis (TGA) was utilized to determine the optimal temperature and time for heat treatment that would remove the resin without causing loss to the fibers. The research involved incrementally increasing the temperature by 100 °C up to 800 °C and maintaining a heat treatment time of 4 h to observe the degree of thermal decomposition of the resin. It was found that most resin decomposition in CFRP occurred at 300 °C, and at a pyrolysis temperature of 400 °C, the resin was effectively removed with no significant change in weight, indicating no fiber damage. However, at temperatures of 500 °C or higher, partial thermal decomposition of the fibers was observed. This study is significant as it provides a method for determining the resin content in FRP construction materials without compromising the integrity of the reinforcing fibers. The optimized heat treatment conditions can be crucial for ensuring the quality and performance of FRP materials in the construction industry.Contribution 5 is presented in the article published in the journal Materials. This study investigates the thermal buckling behavior of moderately thick laminated conical shells that are reinforced with layers originating from carbon nanotubes (CNTs). This research is significant for applications where these materials are exposed to uniform rises in temperature, such as in aerospace and other high-performance engineering fields. The paper utilizes the Donnell-type shell theory to derive the governing equations for the thermal buckling problem. The Galerkin method is then employed to determine the buckling temperature while considering shear deformation theories (STs). The analysis incorporates different transverse shear stress functions, including parabolic, cosine-hyperbolic, and uniform shear stress functions, to evaluate the buckling behavior. After validating the formulation against the existing literature, the study describes several parametric experiments to explore the effects of CNT patterns, the number of layers, and their arrangement on the uniform buckling temperature (UBT).Contribution 6 is presented in the article published in the journal Materials. This study examines the impact of interface shear strength (IFSS) on the mechanical performance of carbon fiber-reinforced composites with a polyether ether ketone (PEEK) thermoplastic matrix. The research compares two types of laminates: one made with as-received fiber fabrics and the other with fibers that had undergone thermal treatment to remove the original sizing agent. The IFSS was measured using the push-in test, which showed that fibers treated to remove the sizing agent exhibited a 25% higher critical shear stress. Microscopic inspections revealed that untreated specimens were more prone to debonding, leading to a higher crack density. This was detected by the C-Scan technique and was evident in the response of the laminates under tensile tests at ±45° fiber orientation. The desized specimens demonstrated a 37% increase in maximum stress and a 190% increase in strain at break values, confirming that the original fiber sizing weakened the fiber–matrix interface. The study contributes to the understanding of how the fiber–matrix interface affects the mechanical properties of composite materials, which is crucial for their application in the aerospace and automotive industries.Contribution 7 is presented in the article published in the journal Applied Sciences. The study focuses on the dynamic buckling behavior of composite laminated structures that are reinforced with a honeycomb pattern and filled with viscoelastic material. This research is particularly relevant for engineering applications where such structures are subjected to varying dynamic loads, such as in aerospace, automotive, and civil engineering. The paper presents a mathematical model of the honeycomb-reinforced composite laminated plate, considering the coupling of in-plane forces. The critical buckling load is determined using large deflection theory, and the effective dynamic stiffness modulus of the composite sandwich is obtained through homogenous asymptotic theory. The study also explores the influence of geometric and external load factors on the dynamic buckling load of these composite structures. The numerical analysis conducted in the study provides insights into the parameters that significantly affect the critical buckling loads, such as the axis load parameter, the geometry parameter, the thickness ratio of the core layer, the honeycomb reinforcement’s width, and the dynamic impulse load’s frequency. The findings contribute to the design and optimization of composite structures for enhanced stability under dynamic loading conditions.Contribution 8 is encapsulated in the research article published in the journal Materials. The study addresses the complex mechanical behavior of solid propellants, which are composite materials known for their nonlinear viscoelastic characteristics. This behavior is largely attributed to the cumulative damage process caused by the formation and growth of microflaws within the material. The research presents a series of standard relaxation and uniaxial tension tests on hydroxyl-terminated polybutadiene (HTPB) propellant at different velocities, utilizing digital image correlation (DIC) techniques to capture the deformation. The findings confirmed that the mechanical behavior of the propellant is rate-dependent, with both yield stress and failure stress significantly influenced by tensile velocity. To accurately describe this behavior, the study developed a nonlinear viscoelastic constitutive model that incorporated rate-dependent cumulative damage. This model employed a Prony series representation of viscoelastic material functions and introduced a rate-dependent damage variable to account for the characteristics of the damage accumulation process. Furthermore, a new normalized failure criterion was derived from the proposed damage model, which remained independent of strain rate after normalization. The model’s accuracy and the failure criterion were validated through finite element analysis, showing high agreement with the experimental data under various strain rates. This research contributes to the field by providing a more precise description of the mechanical characteristics of solid propellants, which is crucial for the design and analysis of solid rocket motors.Contribution 9 is encapsulated in the research article published in the journal Aerospace. This study delves into the thermal and mechanical properties of carbon/carbon (C/C) composite materials, which are extensively utilized in aerospace structures that operate in high-temperature environments due to their superior performance characteristics. The paper focuses on the yarn architecture of C/C composites, where fiber bundles cross in various directions, and these are categorized into different types such as 3-D orthogonal, 4-D in-plane, and 4-D diagonal, based on the arrangement of the fiber bundles. The thermo-mechanical properties of these materials can be tailored by manipulating the yarn architecture, the constituent materials (fiber and matrix), and manufacturing parameters like yarn size, yarn spacing, and fiber volume fraction. In this research, geometric models for repeating unit cells (RUCs) are defined according to the yarn architecture of the C/C composite material. The study employs the iso-strain assumption and stress averaging technique to predict the effective stiffness of these materials. Furthermore, it compares and evaluates the thermo-mechanical characteristics of the RUCs based on yarn architecture and fiber volume fraction. The study’s approach allows for the prediction of thermo-mechanical properties of C/C composite materials, which can significantly reduce testing costs and optimize structural weight while ensuring performance. This is particularly beneficial in the preliminary design stages of aerospace structures, where material selection and parameter optimization are crucial.Contribution 10 is presented in the research article published in the journal Materials. This study proposes a micromechanical simulation approach within a multi-scale modeling (MSM) framework that incorporates manufacturing defects, specifically focusing on the effects of void shape on the macromechanical properties of materials. The research includes a case study on a cross-ply laminate, emphasizing the significance of accurate micromechanical geometry and void characteristics for predicting material behavior. A representative volume element (RVE) model was developed using actual micromechanical geometry obtained from micrographs. Voids were introduced into the RVE model based on statistical experimental data, and their impact on fiber distribution and effective macromechanical properties was assessed. The findings suggest that the local void fraction, void size, and void shape significantly influence the effective micromechanical properties. The study underscores the importance of considering these factors in relation to the overall void fraction of an RVE and the actual laminate. The proposed MSM framework demonstrates a robust prediction capability for macromechanical properties and shows promise for industrial application, particularly in identifying weak spots and critical areas in laminate structures on a macro-level.Contribution 11 is detailed in the article published in the journal Applied Sciences. The research focuses on developing a methodology to assess the residual strength of C/SiC ceramic matrix composite panels when exposed to simultaneous thermal and acoustic stresses. This is particularly relevant for aerospace applications where such materials are used in structures that encounter extreme temperature and noise conditions, such as the thermal protection systems (TPS) of hypersonic vehicles. The study uses a 2D plain-woven C/SiC ceramic matrix composite panel as the test subject, applying spatially uniform thermal loading and band-limited Gaussian white noise to evaluate its geometric nonlinear response through numerical simulation. The material properties, including static strength, residual strength, and fatigue life, are characterized under tensile and compression loads at elevated temperatures. A computer code is developed to simulate the fatigue behavior of the composite panels, and the methodology’s accuracy is validated against experimental results from residual strength tests on the panels under the combined loadings. The findings show a good correlation between the predicted residual strength and the experimental data, indicating the reliability of the proposed methodology in assessing the durability of C/SiC composites under harsh operating conditions.Contribution 12 is outlined in the article published in the journal Materials. The research investigates the bond–slip behavior at the interface between CFRP and steel, which is a critical factor in the performance of CFRP-strengthened steel structures. The study conducted a series of double-strap experiments on CFRP-strengthened steel plates and employs finite element analysis to simulate the bond characteristics. The experiments revealed that the maximum shear stress at the bonding interface was higher for the Q345B steel specimen compared to the X100 specimen. It was also found that both the initial slip and maximum slip at the interface increased with the thickness of the bonding layer. The finite element model incorporated a maximum stress criterion to simulate the onset of material damage when the nominal stress reached the maximum nominal stress threshold. The model’s effectiveness was validated through a verification test, which confirmed that the modified equations derived from the study aligned well with both the numerical and experimental results. This research contributes to the understanding of the bond performance at the CFRP–steel interface and provides modified equations that can predict the bond–slip properties effectively, which is crucial for the design and assessment of CFRP-strengthened steel structures.Contribution 13 is presented in the article published in the journal Materials. The study explores the challenges of machining CFRPs, which are widely used in various industries due to their superior mechanical properties, but present difficulties due to their anisotropy and inhomogeneity. The research focuses on the slot milling of plain-woven CFRP using polycrystalline diamond (PCD) tools, examining the influence of cutting parameters and tool rake angle on the cutting force and surface roughness. The findings indicate that a PCD tool with a 4° rake angle resulted in a smaller cutting force compared to a 0° rake angle tool, although the rake angle did not significantly affect the surface roughness. The concept of an equivalent cutting area was introduced to analyze the variation in cutting force and surface roughness, revealing that both increase with a larger equivalent cutting area and decrease with a smaller one. The study also discusses the different material removal mechanisms under varying equivalent cutting areas and explains the causes of delamination observed on the top layer after milling.Contribution 14 is encapsulated in the article published in the journal Materials. The study delves into the integration of shape memory alloys (SMA) with polymer matrix composites (PMC) for use in active aerodynamic systems in the automotive sector. A significant challenge in this integration is the limited strength at the metal–polymer interface, which is crucial for the functionality of SMA-actuated systems. The research focuses on selecting materials with appropriate thermo-mechanical properties to prevent premature activation of the SMA during the polymer setting and to avoid damage to the polymer during the SMA’s thermal activation. Nonstandard samples consisting of SMA wires embedded in cylindrical resin blocks were created for both static and fatigue pullout tests under thermo-mechanical loading. The study also included fully coupled thermo-mechanical simulations with a special constitutive model for SMAs to analyze stress and temperature distribution. The results demonstrate the substantial impact of SMA thermal activation on adhesion strength due to significant recovery forces and temperature increases at the interface. Under static mechanical load, the samples showed a nominal pullout stress of around 940 MPa, which was reduced to 280 MPa under simultaneous thermal and mechanical loads. Additionally, a fatigue run-out of 5000 cycles was achieved at a nominal stress of around 200 MPa when combining thermal activation and mechanical loads. These findings highlight the design constraints of SMA/PMC systems, particularly regarding the maximum allowable stresses during static and cyclic actuation.Contribution 15 is encapsulated in the article featured in the journal Applied Sciences. The study investigates the integration of plasma combustion technology into micro gas turbine engines (GTEs) using biodiesel fuel derived from animal fat, with a focus on enhancing performance, reducing fuel consumption, and minimizing greenhouse gas (GHG) emissions. The research was conducted at Kuwait’s Public Authority for Applied Education and Training, where laboratory design, fabrication, assembly, testing, and evaluation of the results took place. The study found that the use of biodiesel blended fuels resulted in the lowest emissions of sulfur, nitrogen oxides (NOx), and carbon monoxide (CO). The introduction of hydrogen plasma into the biodiesel improved the thermal efficiency, leading to an increase in the compressor inlet and outlet firing temperatures by 13.3 °C and 6.1 °C, respectively. This enhancement in combustion efficiency due to plasma technology also resulted in a thrust increment of 0.2 kgf for the highest loading condition, positively affecting horsepower and overall GTE engine efficiency while also reducing fuel consumption costs.Contribution 16 is detailed in the article published in the journal Materials. This study addresses the challenge of fabricating carbon-fiber-reinforced silicon carbide (Cf/C-SiC) composites, which are highly sought after for high-temperature load-bearing applications due to their low density, high strength, and excellent thermal–physical properties. Traditional methods for preparing Cf/C-SiC composites often require high sintering temperatures and pressures, which can limit their practical applications. The research introduced a novel binary binder composed of coal pitch and polysilylacetylene, which served as a carbon source, SiC precursor, and semi-ceramic SiC filler. This innovative approach allowed for the successful incorporation of the SiC phase into C/C composites through a slurry impregnation–hot pressing sintering method. The resulting Cf/C-SiC composites exhibited impressive mechanical properties, with a density of 1.53 g/cm³ and a bending strength of 339 ± 21 MPa. Furthermore, the study investigated the impact of the binary binder on the microstructure, density, and mechanical properties of the composites, providing a promising and efficient method for producing Cf/C-SiC composites with enhanced performance characteristics.Contribution 17 is presented in the article published in the journal Materials. This paper presents the innovative development of hybrid composites with significantly improved interfacial properties, achieved by integrating aligned zinc oxide (ZnO) nanowires with continuous carbon fibers. The atomic layer deposition method was utilized to synthesize nanoscale ZnO seeds uniformly on carbon fibers, followed by the growth of vertically aligned ZnO nanowires using a low-temperature hydrothermal method. The morphology and chemical compositions of the ZnO nanowires were meticulously characterized to assess the quality within the hybrid fiber-reinforced composites. Remarkably, single-fiber fragmentation tests revealed an impressive 286% improvement in the IFSS of the epoxy composites. To further understand the interfacial behavior, a multiscale modeling framework was developed, incorporating a cohesive zone model (CZM) to simulate the interface between the fiber and matrix and an ABAQUS user subroutine for the damage behavior of the fiber. The combined experimental and analytical results underscore the efficacy of the aligned ZnO nanowires in enhancing the key mechanical properties of hybrid fiber-reinforced composites, marking a significant advancement in the field of composite materials.Contribution 18 is encapsulated in the article published in the journal Materials. The study delves into the thermal decomposition mechanisms of DFTNAN, a novel fluorinated low-melting-point explosive, by comparing it with TNAN under various heating conditions. The research utilized DSC-TG-FTIR-MS and T-jump-PyGC-MS coupling analyses to monitor the thermal decomposition processes and initial reactions. The findings indicate that the presence of fluorine reduces the thermal stability of the molecular structure, shifting the trigger bond from the ortho-nitro group of the ether to the para-nitro group. Upon initial bond breakage, DFTNAN tends to undergo rupture of the dissociative nitro group, leading to significant heat release and subsequent ring opening of the benzene structure. The study also observed major side reactions, including the formation of polycyclic compounds and the migration of fluorine atoms. The research highlights that fluorine not only affects thermal stability, but also alters the reaction pathway, with fluorinated products appearing as fluorocarbons due to the robustness of the C-F bond.Contribution 19 is encapsulated in the research article published in the journal Materials. This research investigates the magneto-thermoelastic interactions within an unbounded medium that encompasses a spherical cavity. The study employed an advanced multi-time-derivative dual-phase-lag thermoelasticity model to analyze these interactions. The spherical cavity’s surface was assumed to be traction-free and was subjected to both constant heating and an external magnetic field. The authors developed a generalized magneto-thermoelastic coupled solution using Laplace’s transform. The graphical representation of the field variables was used to elucidate the effects of the magnetic field, phase-lags, and other parameters on the field quantities. The study validated the present theory by comparing it with the existing literature, demonstrating its relevance and accuracy.Contribution 20 is detailed in the article published in the journal Aerospace. This study focused on the impact of lightning strikes on the structural integrity of honeycomb sandwich composite structures, which are extensively used in aircraft due to their unique performance characteristics. The research aimed to assess the residual mechanical properties of these structures following a lightning strike. The methodology included simulated lightning strike tests on honeycomb sandwich panels, both with and without a carbon nanotube film (CNTF), to evaluate different damage scenarios and the protective effect of CNTF. Subsequently, the residual compressive strength of the damaged panels was predicted using a progressive damage analysis method. The predictions were then validated against experimental results, demonstrating a correlation between the numerical predictions and the actual outcomes. The study found that the size and extent of lightning damage significantly influence the compression damage mode of honeycomb sandwich panels with closed edges.Contribution 21 is encapsulated in the research article published in the journal Applied Sciences. The study introduced a novel approach to fabricating load-bearing structures with high mass-specific mechanical performance, suitable for various applications in engineering, architecture, automotive, or aerospace industries. The research focused on additive manufacturing processes, specifically coreless filament winding with fiber composites and laser powder bed fusion with metals, to produce lightweight structures. These processes exhibit unique characteristics that must be considered to successfully integrate multiple materials and methods. The hybrid design approach aims to combine the benefits of different materials to achieve mass savings in load-bearing structures with high mass-specific stiffness, strict geometrical tolerance, and machinability. A digital tool for coreless filament winding was developed to capture the process-specific characteristics and support all project phases. The study demonstrated this by stiffening an aluminum base plate with a coreless wound fiber-composite structure, which was attached using additively manufactured metallic winding pins. The research also introduced the concept of multi-stage winding to minimize fiber–fiber interaction, which can be challenging to predict and control. The results showed a significant increase in component stiffness by a factor of 2.5 with only one-fifth of the mass compared to a state-of-the-art reference. This indicates that the hybrid design approach has substantial potential to enhance performance when process-specific features, interfaces, material interaction, and process interdependencies are considered during the digital design phase.Contribution 22 is presented in the article published in the journal Materials journal. This study delved into the hot corrosion characteristics of cobalt-based DZ40M and nickel-based K452 superalloys when exposed to NaCl molten salt at 900 °C, a scenario that simulated the harsh conditions faced by aero-engine turbine blades in marine environments. The research outlines the experimental setup where the superalloys were coated with NaCl salt and subjected to high-temperature conditions to observe the corrosion behavior. The findings reveal that the K452 superalloy, with its higher content of aluminum and titanium, forms a relatively continuous Al2O3 and TiO2 layer that exhibits lower solubility and less damage in Na2O, resulting in a lower hot corrosion rate compared to DZ40M. The latter contains higher amounts of carbon, chromium, and tungsten, which influence its corrosion behavior differently. The paper proposes a corrosion mechanism induced by NaCl by comparing the oxidation and hot corrosion behavior of the two alloys, providing insights into their failure processes. This research is significant for the aerospace industry as it offers a theoretical reference for the selection of materials for guide vanes in turbine blades, which are critical for the performance and longevity of aero-engines.Contribution 23 is encapsulated in the research article published in the Materials journal. This study addresses the challenges of machining CFRP, which are widely used in advanced manufacturing fields such as aviation and aerospace due to their favorable properties. The research introduces a novel gradual-removal reverse edge milling cutter designed to improve the hole-making quality in CFRP. The study established finite element method models to simulate the reverse helical milling process with both the new cutter and a conventional flat-bottomed reverse edge milling cutter under ultrasonic vibration. Comparative cutting experiments were conducted to assess the performance of both cutters. The findings indicate that the new milling cutter can effectively transfer part of the cutting task from the peripheral edge to the end edge, reducing wear on the peripheral edges and improving the quality of the hole at the outlet. This is attributed to the cutter’s design, which allows the peripheral edge to be dominated by shear failure, leading to a significant enhancement in the outlet quality.Contribution 24 is detailed in the article published in the Aerospace journal. This study investigates the nonlinear behaviors and interactions among the constituents of composite material structures under tensile load, focusing on fiber-reinforced composite laminates with central holes. The research employer a multiscale damage model using the generalized method of cells (GMC) and a lamina-level progressive damage model, both based on the thermodynamic Schapery Theory (ST) at either the micro-level or the lamina level. The study’s approach involved predicting the load versus displacement curves and failure modes of the open-hole laminates by using two progressive failure models. These models were compared with the Hashin–Rotem progressive failure model and experimental results. The findings demonstrate that the ST-based method can capture the nonlinear progressive damage evolution states and failure states of the composite at both the lamina level and the multiscale level. The paper also presents damage contours and failure paths, contributing to our understanding of the mechanical response and failure mechanisms of composite structures.Contribution 25 is encapsulated in the research article published in the Materials journal. This research addresses the challenge of enhancing the strength and ductility of magnesium (Mg) matrix composites by incorporating CNTs as a reinforcing agent. The study explores the use of electrophoretic deposition (EPD) to achieve a uniform dispersion of CNTs within a metal matrix, followed by spark plasma sintering (SPS) to synthesize the layered CNTs/Mg composites. The article details the methodology, including the preparation of CNTs, the EPD process for layering, and the subsequent SPS. The results demonstrate that the composite samples sintered at 590 °C exhibited improved strength and ductility compared to pure Mg and those sintered at 600 °C. Additionally, the composites rolled by 40% showed significantly higher strength without a substantial decrease in ductility. The study also examined the damping properties of the composites, revealing that the damping-test-temperature curve increases with temperature and that the composites maintain excellent damping properties at room temperature. The research concludes that the layered structure of the CNTs/Mg composites, prepared via EPD, can effectively disperse CNTs and enhance the material’s mechanical properties while preserving ductility, offering potential applications in aerospace and other advanced manufacturing fields.Contribution 26 is presented in the article published in the Materials journal. The study delves into the damping characteristics of CFRP raft frames, which are pivotal in vibration isolation in mechanical systems. Utilizing composite laminated plate theory and a strain energy model, the research examined how different layups affect the damping capacity of the raft frame and its components, such as the top/bottom plate and I-support. The study employed finite element analysis (FEA) and a damping ratio prediction model to compare the theoretical results with the experimental data. It was found that the layup of CFRP laminates significantly influenced the damping ratio of the raft frame, with the maximum error in the first-order natural frequency and damping ratio for the top/bottom plate being 5.6% and 15.1%, respectively. The I-support showed a 7.5% maximum error in the first-order natural frequency between FEA and test results, indicating a larger error in the damping ratio due to stress concentration. The research concluded that the damping performance of the raft frame is affected by the arrangement of the I-support, and the simulation analysis aligned well with the experimental outcomes. This study provides valuable insights for enhancing the damping performance of CFRP raft frames, which could have significant implications for their application in various manufacturing sectors, including aerospace.Contribution 27 is highlighted in the article published in the The series of studies presented under this topic offer a comprehensive examination of the advancements in composite materials and their applications in aerospace and mechanical engineering. The research contributions collectively address the critical aspects of material characterization, damage assessment, and structural integrity, providing insights into the multifaceted nature of composite materials.The collective findings from these studies underscore the importance of innovative design, precise material characterization, and advanced manufacturing techniques in the development of composite materials for aerospace applications. The integration of experimental, numerical, and theoretical approaches across these contributions provides a holistic view of the current state and future directions of composite material research in the aerospace sector.