The radial vibration of a radial composite tubular transducer with a large radiation range and power capacity is studied. The transducer is composed of a longitudinally polarized piezoelectric ceramic tube and a coaxial outer metal tube. Assuming that the longitudinal length is much larger than the radius, the electromechanical equivalent circuits of the radial vibration of a piezoelectric ceramic long tube and a metal long tube are derived and obtained for the first time following the plane strain theory. As per the condition of the continuous forces and displacements of two contact surfaces, the electromechanical equivalent circuit of the tubular transducer is obtained. The radial resonance/anti-resonance frequency equation and the expression of the effective electromechanical coupling coefficient are obtained. Then, the effects of the radial geometry dimension of the transducer on the vibration characteristics are analyzed. The theoretical resonance frequencies, anti-resonance frequencies, and the effective electromechanical coupling coefficients at the fundamental mode and the second mode are in good agreement with the finite element analysis (FEA) results. The study shows that when the overall size of the transducer is unchanged, as the proportion of piezoelectric ceramic increases, the radial resonance/anti-resonance frequency and the effective electromechanical coupling coefficient of the transducer at the fundamental mode and the second mode have certain characteristics. The radial composite tubular transducer is expected to be used in high-power ultrasonic wastewater treatment, ultrasonic degradation, and underwater acoustics, as well as other high-power ultrasonic fields. Longitudinal sandwich piezoelectric ceramic ultrasonic transducers, which are also called Langevin piezoelectric composite ultrasonic transducers, are widely used in high-power ultrasound ,2,3,4. TUntil now, the research on radial composite ultrasonic transducers has been relatively comprehensive. According to the ratio of the longitudinal length of the radius, the research can be divided into the following three categories: When the ratio is small, the model of the piezoelectric element is mainly a thin solid disk or a hollow ring. Iula et al. analyzed the radial symmetry mode of the thin piezoelectric ring ,10. GaniGenerally speaking, there are many methods to analyze the vibrations of piezoelectric ceramic vibrators, and the most widely used is the equivalent circuit method ,23,24,25Along with the development of ultrasonic technology, the optimization of high-power ultrasonic transducers is mainly focused on two aspects. On the one hand, the power capacity of the piezoelectric vibrator is expected to improve in order to increase the power of the whole transducer. On the other hand, the tool heads of the different models are designed to increase the displacement amplitude of the radiated end face of the transducer. In order to enlarge the radiation area, improve the power capacity, and improve the equivalent circuit theory of the piezoelectric vibrator, the radial vibration of a high-power longitudinally polarized radial composite tubular transducer is studied. In the analysis, the plane strain theory is considered, and the vibration of the transducer can be regarded as an axisymmetric radial vibration. Based on the theoretical analysis, the electromechanical equivalent circuit of the radial vibration of the transducer is derived. In order to verify the correctness of the analytical theory, finite element analysis (FEA) is employed to simulate the vibrational modes of the transducer.r and z as the radial and axial directions, respectively. The transducer is composed of a longitudinally polarized piezoelectric ceramic tube and a coaxial outer metal tube in the radial direction. The radius of the transducer is a, b, and c from inside to outside; the height of the transducer is h, and h is much larger than c. The direction of the applied electric field of the piezoelectric ceramic tube is parallel to its polarization direction.i = r, θ, rθ, rz) are the stress components of the piezoelectric ceramic tube, i = r, θ) are the radial and circumferential strain components. Because the vibration of the transducer is an axisymmetric radial vibration, In the cylindrical coordinate system, the motion equation of the radial vibration of the piezoelectric ceramic tube  is(1)ρrh, of the tube is much larger than the radius, c, the plane strain theory about mechanics can be applied to analyze the vibration of the transducer, so In the cylindrical coordinate system, the linear piezoelectric constitutive equations of a longitudinally polarized piezoelectric ceramic tube  are as fA1, A2, and A3 are constants, which are defined as Substituting Equations (10) and (11) into Equations (6) and (7), the expressions of the radial strain component, From Equations (12) and (13), the radial stress component and the relationships between the radial and circumferential stress components can be obtained asB1 and B2 are the constants that are determined by the boundary conditions. Substituting Equations (2) and (5) into Equations (14) and (15), and then substituting the obtained results into Equation (4), the wave equation of the piezoelectric ceramic tube on the radial vibration can be obtained. The simple harmonic motion is considered as B1 and B2 can be obtained asSubstituting boundary conditions pZ11, pZ12, and pZ13 are the impedances and N31 is the electromechanical conversion coefficient of the piezoelectric ceramic tube, whose expressions areSubstituting Equation (18) into Equations (2) and (5), and then substituting the result into Equation (14) and combining it with Equations (20) and (21), the radial stress component can be further written asD3 can be written asThe current flowing into the slender tube is D3 can be further written asSubstituting Equation (16) into Equation (11), the expression of I31, can be obtained asFrom Equation (32), the current, In the cylindrical coordinate system, according to the generalized Hooke’s law, the relationships between the stresses and strains of a metal tube  are(34)Substituting Equation (40) into Equations (34) and (35), C1 and C2 are the constants determined by the boundary conditions. Substituting Equations (38) and (39) into Equations (41) and (42), and then substituting the results into Equation (37), the wave equation of the radial vibration of the metal tube can be further written asC1 and C2 can be obtained asSubstituting boundary conditions bF and cF can be obtained asSubstituting Equation (44) into Equations (38) and (39), and then substituting the results into Equation (41) and combining this with Equations (46) and (47), According to Equations (51) and (52), the electromechanical equivalent circuit of the radial vibration of the outer metal tube can be obtained as shown in Zm11, Zm12, and Zm13 are the impedances, whose expressions are the following forms:In According to the above theoretical analysis, considering the load mechanical resistance and by combining Zl1 and Zl2 are the load mechanical resistances of the radial composite tubular transducer at the inner and outer surfaces, respectively. The mechanical impedances of the outer metal long tube and the transducer are defined as moZ and mZ, respectively. The input electrical impedance of the transducer is defined as eZ. The expressions of moZ, m,Z and eZ can be written asWhere rf, a,f and effK are the resonance frequency, anti-resonance frequency, and the effective electromechanical coupling coefficient, respectively. According to Equations (59)–(61), when the geometric dimensions and the basic material parameters of the transducer are given, the resonance frequency, anti-resonance frequency, and the effective electromechanical coupling coefficient can be obtained.Under the no-load state, the resonance frequency equation, anti-resonance frequency equation, and the expression of the effective electromechanical coupling coefficient areE1 = Because Equations (59)–(61) are transcendental equations, Wolfram Mathematica 11.3 was used to calculate the radial resonance frequencies and anti-resonance frequencies of the transducer at the fundamental mode and the second mode. In order to verify the correctness of the theoretical results, the theoretical results were compared with the FEA results, which were obtained by COMSOL Multiphysics 5.3a. PZT-4 was selected as the material of the piezoelectric ceramic tube, which had the following standard material parameters: b was gradually increasing and other geometric dimensions were fixed . When the transducer vibrated at the fundamental mode and the second mode, the relationships between the radial resonance (rf)/the anti-resonance frequency (af), the effective electromechanical coupling coefficient (effK), and the radial geometric dimension Under the no-load state, rf1) and the anti-resonance (af1) frequency of the transducer at the fundamental mode decreased. The reason is that when the overall size of the transducer is unchanged, rf2) and the anti-resonance frequency (af2) at the second mode of the transducer are relatively complex. There are two inflection points in It can be clearly seen from effK1) at the fundamental mode increases significantly. However, as effK2) at the second mode decreases first and then increases. When effK2 is basically unchanged. When effK2 is almost zero. In the actual engineering design of the transducer, the situation where effK is zero should be avoided. The effective electromechanical coupling coefficient should be as large as possible to ensure a higher electromechanical conversion.It can be seen from As can be seen from In this section, COMSOL Multiphysics 5.3a was applied to simulate the vibrational modes of the transducer. The radial relative displacement distribution curves and the modulus of the input electrical impedance can then be obtained. The radial geometric dimensions of the two different radial composite tubular transducers are shown in z-axis on the outer surface of the transducers are not completely uniform. Compared with the transducer with The vibrational modes and radial relative displacement distribution curves of No. 1 transducer, with The frequency curves of the input electrical impedance of the No. 2 transducer are shown in t−rf1 and t−af1 are the theoretical resonance frequency and anti-resonance frequency, respectively; n−rf1 and n−af1 are the radial resonance frequency and anti-resonance frequency calculated by COMSOL, respectively; and The comparisons between the theoretical and simulation results of the No. 1 and No. 2 transducers at the fundamental mode at As can be seen from e length .(1)Under the no-load state, when the overall size of the transducer is unchanged, as the proportion of piezoelectric ceramics increases, there are two inflection points on the variation curves of the radial resonance frequency and anti-resonance frequency at the second mode.(2)The resonance/anti-resonance frequencies of the No. 1 and No. 2 transducers under different ratios of length to radius are obtained using COMSOL. After comparison, the analytical theoretical results and COMSOL results are in good agreement.(3)In the present work, the vibration characteristics of the transducer at the fundamental mode and the second mode are analyzed. In future work, the higher vibrational order and the effects of the dielectric and load losses on the vibration characteristics will be studied.(4)The derivation of the electromechanical equivalent circuit of the radial vibration of a longitudinally polarized piezoelectric ceramic tube completes the equivalent circuit theory. The tubular transducer with a large radiation range and power capacity has certain application prospects in the fields of high-power ultrasonic wastewater treatment, ultrasonic degradation, and underwater acoustics.In this paper, based on the plane strain theory, the equivalent circuits of a longitudinally polarized piezoelectric ceramic long tube and a metal hollow long tube are derived and obtained for the first time. In addition, the electromechanical equivalent circuit of a longitudinally polarized radial composite tubular transducer is obtained. Then, the effects of the radial geometry dimension of the transducer on the vibration characteristics are analyzed. Through the analysis of the research results, the following conclusions can be drawn:


Bonferroni’s correlation between both angles was 0.50 (p = 0.028). More failures were seen with a varus drill positioning, aiming at the central area of the femoral head, outside the weight-bearing area (WBA) (p = 0.049). In the transverse plane, the anterior positioning of the drill did not result in better outcomes (p = 0.477). Conclusion: The forage drilling to deliver cells should be positioned within the WBA in the coronal plane, avoiding varus positioning, and central to anterior in the transverse plane. The efficacy of delivered MSCs to regenerate bone in ONFH could be influenced by the drilling direction. Standardization of this surgical technique is desirable.Bone forage to treat early osteonecrosis of the femoral head (ONFH) has evolved as the channel to percutaneously deliver cell therapy into the femoral head. However, its efficacy is variable and the drivers towards higher efficacy are currently unknown. The aim of this study was to evaluate the forage technique and correlate it with the efficacy to heal ONFH in a multicentric, multinational clinical trial to implant autologous mesenchymal stromal cells expanded from bone marrow (BM-hMSCs). Methods: In the context of EudraCT 2012-002010-39, patients with small and medium-sized  ONFH stage II  C1 and C2 (Japanese Investigation Committee (JIC)) were treated with percutaneous forage and implantation of 140 million BM-hMSCs in a standardized manner. Postoperative hip radiographs , and MRI sections  were retrospectively evaluated in 22 patients to assess the femoral head drilling orientation in both planes, and its relation to the necrotic area. Results: Treatment efficacy was similar in C1 and C2  and in anterior to posterior (transverse plane) osteonecrotic lesions. The drill crossed the sclerotic rim in all cases. The forage was placed slightly valgus, at 139.3 ± 8.4 grades  with higher dispersion ( Treatments for osteonecrosis of the femoral head (ONFH) are still a matter of considerable debate. Non-operative treatments have been associated with high radiographic failure rates (at a mean of 72%) consistently throughout the years . Due to The forage or CD technique has substantially evolved given the limited, variable efficacy. Different technical proposals include multiple small drilling ,10,11,12Considerable interest has been generated by the advances in cell therapy to regenerate bone, and Hernigou early on confirmed the benefits of bone marrow (BM) grafting injected through the forage . The useEfficacy may not only depend on patient- and disease-specific aspects , but also on technical specificities that are poorly understood. While surgeons usually aim to perform the forage drilling towards the lesion, the cell distribution and subsequent efficacy may also be modulated by this drilling. Among the uncertain issues, some are technical, such as drill diameter, single versus multiple drilling or the location and direction of the drilling related to the lesion, towards the central area of the femoral head or the weight-bearing area (WBA). In preclinical models, the biodistribution of MSCs was proven to remain within the injected femoral head , confirmAt this point, the study aim is to evaluate the variability of the forage positioning and to identify how this variability may affect the efficacy of cell therapy, framed in a clinical trial injecting expanded autologous BM-derived MSCs in the femoral head with osteonecrosis Ficat–Arlet or ARCO stage II. To meet the aim of the study, we evaluated the efficacy of the technique related to the location of the osteonecrosis and the location of the forage tunnel.6 cells/mL). All included patients agreed to their participation and signed an appropriate informed consent form . Patients were 19 males and 3 females with a mean ± sd (range) age of 43 ± 10 (21-62) years and a mean ± sd (range) time since initial diagnosis of 2.3±2.2 (0.1–7.6) months. The ONFH was idiopathic (40%) or due to corticosteroid treatment (25%) or other non-traumatic causes (35%). All cases were classified as stage II by Arlet and Ficat [Anonymized imaging from 22 patients treated for osteonecrosis of the femoral head under the Ortho 2 clinical trial (EudraCT 2012-002010-39) in the REBORNE EU-funded project  is the material under study . Brieflynd Ficat , Steinbend Ficat  or ARCO nd Ficat , as all nd Ficat . The volnd Ficat , as a peDuring surgery, antimicrobial prophylaxis and analgesia were performed as per local protocol. After anesthesia , patients were positioned supine on a fracture table. A radiological C-arm was placed and both anteroposterior (AP) and axial views of the femoral neck and head were checked under fluoroscopy. Following a minimally invasive approach, with a 1 cm incision laterally to the proximal femur, a guide wire was drilled from the lateral cortex of the subtrochanteric femur into the femoral head lesion, under fluoroscopic AP and axial control. Then, a 4 mm cannulated drill was introduced along the guide wire into the femoral head , guided To determine the coronal location of the necrotic lesion, we used the 2001 classification system, proposed by the Japanese Investigation Committee , on preoTo estimate the transverse lesion location from anterior to posterior, we defined a so-called anterior/central/posterior (ACP) method on preoperative T1-transverse MR sections and lateral or axial radiographs of the hip. The method consists in identifying the extension of the lesion in three regions of the femoral head , taking as a reference the osseous acetabular rim (from the anterior to the posterior edge). The value of anterior 2 (A2) or posterior 2 (P2) means that the lesion surpasses the anterior acetabular edge (A2) or the posterior acetabular edge (P2). To evaluate the transverse plane in MR sections, we set the height in the section where the anterior trochanter appears, using the comparative function of OsirixMD software v9.1  to help us adjust the coronal view. We use a radial angle circle tool to divide the region into three zones. Finally, postoperative (1.5 or 3 months since surgery) anteroposterior radiographs were examined to measure the anatomical angle and the forage angle, taking as a reference the intersection point of the cervicodiaphyseal angle , and to locate the forage tunnel in the WBA thirds , as seen in All images were processed, measured, and classified with OsirixMD software . Mean anp = 0.001). There was no difference in efficacy related to the JIC extension of the lesion in the coronal plane, whether the extension was evaluated in radiographs  or in MRI . Therefore, the coronal extension of the lesion was not associated with an increase in the treatment failure after the delivery of autologous, expanded BM-MSCs .Characteristics of the osteonecrosis lesion and the forage technique are listed in p = 0.042). Then, the transverse evaluation was performed on MRI for the final analysis. There was no difference in the efficacy  by the type of ACP lesion in MRI . Therefore, the transverse extension of the lesion was not associated in this series with an increase in the treatment failure after the delivery of autologous, expanded BM-MSCs .The location of the osteonecrosis by the ACP method in MR studies was defined as A2CP in 11/22 cases (50%), ACP in 6/22 cases (27%) and A2C in 5/22 cases (23%). Using lateral or axial radiographs, the location was defined as ACP in 13/22 cases (59%) and A2CP in 9/22 cases (41%). The inconsistency between both types of images was 50% (11/22 cases). The percentage of classification agreement between MRI and radiographs in our cases was considered slight, 18% , with a Bonferroni correlation of 0.5 (p = 0.028).The mean anatomical angle of the proximal femur in grades was 133.7 ± 5.2 , the mean intermediate angle forming the WBA-I as per  was 142.2 = 3.85; p = 0.049). There was no significant difference in the failure rate (ON progression and/or THR conversion) when the forage was performed within the 1st or the 2nd portion of the femoral head weight-bearing area .The drilling crossed the sclerotic rim in all cases. Seven forages were placed inside WBA-I (32%), eight inside WBA-II (36%) and seven (32%) outside the WBA. The failure rate for cases with forage outside of the WBA  was 42.8% (3/7) versus 13.3% (2/15) in forages placed within the WBA. In this sense, the efficacy of the injected cells to heal the lesion (in terms of avoiding osteonecrosis progression and/or THR conversion) was significantly higher when the forage was performed in the weight-bearing area . The failure rate of cases with anterior forage was 14% (1/7) and 27% (4/15) with central forage . No differences in bone healing were found between the anterior or central location of forage and the anterior extension of the lesion .The transverse location of the forage (ACP) in the postoperative MR sections was central in 68% of cases (15/22) and anterior in the remaining 32% (7/19) of cases . The ACPl forage , with nop = 0.514) and no differences were seen related to the coronal ONFH location, as per the JIC 2001 classification (Mann–Whitney test p = 0.185), or the transverse ONFH location, as per the defined ACP method . When comparing cases with small ONFH lesions (volume under 15%) to those with medium-sized lesions (over 15%), the failure rate was not statistically different . Adjusting the category of the small or medium preoperative volume of ONFH by the ACP location, no differences were observed in the failure rate , not even when adjusting with the JIC 2001  type of lesion .The mean preoperative volume of osteonecrosis was 13.4 ± 5.9 % (range: 5.4–32.2), as a percentage of the spherical model of the femoral head and did not influence the healing in this homogenous series. No differences were seen in the preoperative volume between the healed and the non-healed cases  and the Japanese Investigation Committee (JIC) offered different approaches to expand the ONFH classification and integrate the prognostic value of extended locations of the lesion. Even if a recent Delphi approach to the ARCO classification contradicts this view [The technique’s efficacy may be related to the lesion. The influence of the lesion location in the treatment of ONFH has long been debated. After the original and extended Ficat and Arlet staging, Steinberg  , the Asshis view  and doeshis view . In our his view .Besides this debate, the imaging evaluation to classify the lesion may also be a problem, as the assessment of the Ficat–Arlet and ARCO staging concluded that these classifications offer poor interobserver reliability and fair intraobserver variability . We coulWe also defined anterior, central and posterior areas of the femoral head as a way to understand the transverse extension of the lesion, in the philosophy of the JIC classification for the coronal plane . The neeThe forage technique was then considered when related to treatment efficacy. The forage or CD technique has varied substantially in decreasing the potential risks, such as fracture  secondarThe positioning of the forage has not been previously investigated. Furthermore, when multiple drilling (3 mm) is planned instead of a single, larger drilling , its posThis study is based on postoperative imaging after an early clinical trial, and the number of cases is limited. This is a major limitation of the study, as occurs with many reports on osteonecrosis treatment. However, the fact that it is based on a precise protocol for including cases , performing the technique, delivering a standardized advanced treatment (such as 140 million autologous expanded MSCs) and following patients is also a study strength that has helped us to homogenize the results. Other limitations include the potential influence of different diagnoses, the variable regenerative potential of autologous cells from each patient, the unknown spatial proliferation of delivered cells and the evolution of these cells within the necrotic tissue. All these limitations due to the biology of the treatment may influence the surgical efficacy of the procedure. This bone regeneration is still poorly understood within the osteonecrotic lesion and will require further studies. Still, we believe that the role of adequately positioning the cells within the femoral head during the surgical procedure needs to be appraised and standardized, to avoid an important source of potential variability in the current treatment of early stages of osteonecrosis by means of cell therapy.The drilling orientation of the percutaneous forage in the coronal plane within the weight-bearing area of the femoral head, slightly valgus compared with the anatomical CCD angle, increased the efficacy of bone regeneration when delivering cell therapy to the osteonecrotic femoral head in this study. In the transverse plane, central or anterior drilling were similarly efficacious. The drilling orientation should be standardized in a clinical protocol to percutaneously treat femoral head osteonecrosis with cell therapy, considering the injury location and spread, because the efficacy of the cells delivered in the treatment may be influenced by the surgical procedure.


Significantly divergent polioviruses (VDPV) derived from the oral poliovirus vaccine (OPV) from Sabin strains, like wild polioviruses, are capable of prolonged transmission and neuropathology. This is mainly shown for VDPV type 2. Here we describe a molecular-epidemiological investigation of a case of VDPV type 3 circulation leading to paralytic poliomyelitis in a child in an orphanage, where OPV has not been used. Samples of feces and blood serum from the patient and 52 contacts from the same orphanage were collected twice and investigated. The complete genome sequencing was performed for five polioviruses isolated from the patient and three contact children. The level of divergence of the genomes of the isolates corresponded to approximately 9–10 months of evolution. The presence of 61 common substitutions in all isolates indicated a common intermediate progenitor. The possibility of VDPV3 transmission from the excretor to susceptible recipients  with subsequent circulation in a closed children’s group was demonstrated. The study of the blood sera of orphanage residents at least twice vaccinated with IPV revealed the absence of neutralizing antibodies against at least two poliovirus serotypes in almost 20% of children. Therefore, a complete rejection of OPV vaccination can lead to a critical decrease in collective immunity level. The development of new poliovirus vaccines that create mucosal immunity for the adequate replacement of OPV from Sabin strains is necessary. The trivalent oral poliovirus vaccine (tOPV) from Sabin strains, which promotes the formation of both humoral and mucosal immunity in vaccine recipients, was considered the most effective tool for fulfilling the objectives of the Global Polio Eradication Initiative (GPEI) . Due to The threat of VDPV formation is most closely associated with the Sabin strain type 2 ,12. ThusVDPVs originating from the Sabin strain type 3 are much less common. In the period 2000–2015, type 3 cVDPV outbreaks accounted for only 1.5% of known cVDPV cases . As regaAlthough less than 1% of people with PID excrete iVDPV, the potential for iVDPV to enter the human population is considered a serious threat of OPV withdrawal after the global certification for polio eradication . CurrentThe AFP case (later defined as VAPP) was registered on 10 July 2014 in Syzran city hospital . The patient, a 13-months-old boy , was born in a socially disadvantaged family. Since 7 May 2014 he lived in the Syzran orphanage that specializes in providing medical, pedagogical and social assistance to children aged up to 4 years with organic lesions of the central nervous system, mental disorders, and other congenital, hereditary and acquired diseases. The sanitary and hygienic conditions in the orphanage met the regulatory requirements of the Russian Federation. Children were separated into 4 isolated groups. Of the 54 children living in the orphanage, 26 (48%) were not vaccinated against poliomyelitis at the time of polio case occurrence. IPV was used in the orphanage for vaccination against poliomyelitis. However, 9 children (17%) had received from 1 to 3 doses of OPV  before eThe AFP case was detected and laboratory investigated according to the AFP assay algorithm adopted in Russia  and the The isolation and identification of viruses from fecal samples were performed by the standard procedures . The virPoliovirus-neutralizing antibodies were determined in sera via neutralization assay with Sabin strains types 1, 2 and 3 in Hep-2c cells .The total RNA was isolated from the cultural medium of infected cells using the RNeasy minikit , reverse–transcribed by the SuperScript reverse transcriptase  with random hexanucleotide primers , amplified by PCR to produce 8 overlapping DNA fragments (primers are available upon request), and purified with QiaQuick DNA purification kit . For sequencing, an ABI 3130 Genetic Analyzer was used.The full viral genomes were assembled using the Lasergene software . The sequence alignments and estimation of genomes divergence were performed with MEGA 6 .Nucleotide sequences were deposited in GenBank (accession numbers MT645947–MT645951).Flaccid lower paraparesis with lesions of the distal and proximal parts of the legs was detected in a child P (patient) living in the Syzran orphanage, 10 July 2014. Paresis arose sharply against the background of a fever within 7 days. Upon examination, the child showed a low tone of the lower extremities, a decrease in the knee reflexes and the absence of the Achilles reflexes. Sensitivity disorders and dysfunctions of the pelvic organs were not observed. Paresis of the extremities persisted on the 60th and 90th days after AFP onset. Before the disease, the boy was not vaccinated against polio. VDPVs type 3 was isolated from the fecal samples collected on 11 and 12 July. The AFP case was classified as “contact VAPP” (cVAPP) by the National Expert Classification committee as recommended by the WHO  and natiVDPVs type 3 were also found in fecal samples collected on 13 July from three out of seven investigated healthy contact infants from the same group in the orphanage. Two of these virus excretors  had previously been IPV-vaccinated, whereas the third one  was not.Two serological examinations of P carried out soon after the disease onset did not detect neutralizing antibodies against polioviruses of serotypes 1 and 2 (titers < 1:8), while the third test revealed a low titer of serotype 2 (1:16), and a significant accumulation of antibodies against the serotype 3 was recorded subsequently, from 1:32 (14 July) to 1:256 (24 July 7 August). Similarly, the serum of C-1, investigated on 7 August, contained antibodies only against serotype 3 (1:64) , even thThe full genome sequences of the two isolates (separated by one day) from the VAPP patient and the isolates from three healthy contacts revealed that these viruses contained numerous mutations distinguishing them from the Sabin 3 strain . All isoThe minimal and maximal divergences of the genomes from those of the vaccine were 70 and 84 nt, in isolates from C-1 and C-2, respectively . AlthougThe relevant values markedly varied for the five isolates in the range of 8.8–10.6 months . A large472C) and in the VP1-coding region , both being commonly observed in the Sabin-3 derivates [2034C, resulting in Phe91Ser substitution in VP3), which affects the temperature sensitivity of the poliovirus [Some of the mutations were obviously biologically relevant, and at least a portion of them were of adaptive character. All isolates harbored deattenuating mutations in the 5′-UTR , and we often observed in VDPVs the substitution of Ala165Thr in the adjoining antigenic site 2 position [288Asp and Asp290Asn of VP1 and Ser79Leu in the antigenic site 4 of the VP3 of the isolate C-2. Moreover, all strains shared the Met105Thr substitution, often detected in VDPVs, [Besides the above-mentioned adaptive mutations in the capsid proteins of all the isolates, there were substitutions in the antigenic sites. In the antigenic site 2 in VP2, there were Valposition . In the n VDPVs,  in the rn VDPVs, .162A, G395A, U472C, U480C, U5832C and U6938C) are expected to stabilize the secondary RNA structure of domains II, IV and V of the 5′UTR [cis-acting element [15Ser. It is believed that this substitution is the reason for the recombination of the derivatives of a vaccine strain of the type 3 [In addition, several nucleotide mutations  and the observation of their health, the laboratory investigation of specimens from the contacts (serum and feces samples), and the revision of the vaccination withdrawals.In the summer–autumn of 2014, after the detection of the disease, 10, 23 and 7 children were given one, two or three doses of IPV, respectively. The first 11 children were vaccinated soon after the AFP case detection (14.07). At the end of July and in August, 8 children received IPV; in September, 21 did, in October 13 did and in November 24 did.Fecal samples from 52 children were collected in October and additionally from 49 of them in November, and they were found to be poliovirus-negative.The sera of all children were investigated for neutralizing antibody presence on 7–8 October and 24 November . SeveralIn October, there were four children testing negative for antibodies against serotypes 1 and 2, but exhibiting relatively high titers against serotype 3 , providing additional evidence that the transmission of VDPV-3 affected not only the poliovirus excretors detected. This notion is also in line with the fact that several sera  contained at least four-fold higher antibodies titers against serotype 3, compared to the other two.At the final stage of the Global Polio Eradication Initiative, when the victory over wild polioviruses of types 2  was annoPresented in this study, the case of a VDPV type 3 circulation in a specialized orphanage, which resulted in one child with VAPP, allows us to dwell on several points.cis element-inhibiting RNaseL activity located in the 3C region and in the first conservative structural element of 3D-7000. Many of these mutations were also observed in other variants of Sabin 3 , all is Sabin 3 .15Ser mutation in protein 3A. Most (about 80%) of the tested type 3 natural isolates of vaccine origin are intertype recombinants [Another interesting feature of the studied isolates (non-recombinants) is an Argmbinants ,49. Earlmbinants . The genWe believe that the origin of the VDPV circulation observed in the orphanage could be Sabin-3, which evolved over a long period in the organism, most likely, of one host. In favor of the assumption that the “common ancestor” of the isolates is iVDPV is the fact that all isolates are not recombinants, and, moreover, we have not found any other related viruses. The fact that the virus was actively circulating in the orphanage (cVDPV) is confirmed by both the isolation of related but significantly different viruses from four children , and by Unfortunately, we were not able to identify the source of the infection, as only IPV was used for vaccination in the orphanage. It is feasible that one of the newly enrolled children acquired the virus through contact in a previous place of residence, or in a medical facility. Long-term poliovirus excretion, exceeding the quarantine time upon admission (one month), is not a rare event. This is especially true for weakened children with various severe diagnoses, for whom this specialized orphanage is intended. It should be noted that at the time of the disease detection, nine children previously routinely vaccinated with OPV lived in the orphanage. Genetic analysis of the isolates showed that the time of their divergence from the vaccine strain ranges from 9 to 11 months . In fourThe case presented here in accordance with current WHO recommendations  can be cA frightening discovery in the investigation of this epidemiological situation was the lack of immunity to at least two poliovirus serotypes in a significant number of children at least twice vaccinated with IPV when the assessment of antibody levels was carried out more than a month after the first vaccination . MoreovAccording to the WHO’s current plans, after the global OPV cessation, polio immunization will only be carried out with IPV , and at It has been convincingly shown that the introduction of polioviruses into the non-immune group leads to its rapid spread and prolonged circulation . At the The main type of surveillance of poliovirus circulation for implementing the Global Polio Eradication Initiative is the surveillance of acute flaccid paralysis (AFP). However, over time, with the further implementation of the Program, additional types of surveillance, aimed at identifying the long-term asymptomatic circulation of polioviruses, has become increasingly important. This includes environmental surveillance (wastewater research) and the study of PID patients as potential poliovirus excretors . Russia


Mandibular fracture healing is a complex process involving nerves and growth factors. Nerve growth factor (NGF) not only facilitates the maintenance of sympathetic neurite growth but also stimulates other growth factors that can promote the essential osteogenesis and angiogenesis for fracture healing. Therefore, it is necessary to analyze the combined effects of NGF, bone morphogenic protein-9 (BMP-9), and vascular endothelial growth factor (VEGF) to accelerate the healing of mandible fractures.The models of mandible fracture with local nerve injury established in 48 rabbits were randomly divided into nerve growth factor group (NGF group), gelatin sponge group (GS group), blank group, and intact group. The recovery of nerve reflex was assessed by observing the number of rabbits with lower lip responses to acupuncture. The fracture healing was observed with visual and CBCT, and then callus tissues from the mandibular fracture area were collected for hematoxylin and eosin (HE) staining observation, and the expression of BMP-9 and VEGF in callus at different stages was detected by quantitative real-time PCR (qRT-PCR).Needling reaction in the lower lip showed the number of animals with nerve reflex recovery was significantly higher in the NGF group than that in the GS and blank groups at the 2nd and 4th weeks after the operation. The combined results of macroscopic observation, CBCT examination, and histological analysis showed that a large number of osteoblasts and some vascular endothelial cells were found around the trabecular bone in the NGF group and the amount of callus formation and reconstruction was better than that in the GS group at the 2nd week after the operation. The qRT-PCR results indicated that the expression levels of BMP-9 and VEGF in the four groups reached the highest values at the 2nd week, while the expression levels of both in the NGF group were significantly higher than that in the GS group.The exogenous NGF could accelerate the healing of mandible fractures. This work will provide a new foundation and theoretical basis for clarifying the mechanism of fracture healing, thereby promoting fracture healing and reducing the disability rate of patients.The online version contains supplementary material available at 10.1186/s13018-021-02220-z. With nearly 29% of all maxillofacial fractures with a range of 11–36%, mandibular fracture remains one of the most common facial fractures , and vehMany studies have investigated the effect of regulating factors including cell proliferation and differentiation, matrix synthesis, and calcification in the process of fracture healing –10. ThesBelonging to the transforming growth factor-β (TGF-β) superfamily, more than 14 bone morphogenic proteins (BMPs) have been identified to induce ectopic bone growth and cartilage formation , 26. BonTo analyze the combination of NGF, BMP-9, and VEGF to accelerate the healing rate of mandible fracture, the rabbit models of mandible fracture with local nerve injury were constructed in this study. This study aims to investigate the regulating effects of exogenous nerve growth factor on the expression of BMP-9 and VEGF, and to further elucidate the possible mechanism of promoting fracture healing through exogenous NGF.Forty-eight skeletally-mature, male or female New Zealand white rabbits, weighing 2.5–3.0 kg (mean 2.7 ± 0.2), were included in the study. The animals were transferred to the experimental animal center of Zunyi Medical University at least 1 week before the surgery and kept in separate cages to help them adapt to the new environment as well as to ensure their health. This study was performed by the regulations of the Animal Management Regulations and Administrative Measures on Experimental Animal and approved by the medical ethics committee of Zunyi Medical University .Forty-eight healthy rabbits were used to establish fracture models by the following surgery under aseptic conditions. All rabbits were randomly selected and placed in the supine position, and their submandibular region was prepared individually. They were anesthetized with an ear vein injection of 3% pelltobarbitalum natricum (1 ml/kg body weight), and 2% lidocaine (2 ml) was then injected for intensive local anesthesia. After submandibular incision and dissection of the periosteum, both sides of the mandible anterior to the masseter muscle were exposed by blunt and sharp dissection, and the neurovascular bundle of the mandible of 36 rabbits was transected. Then, incomplete fractures (about 5 mm × 2 mm) were made in front of the mental foramen of the mandible through the buccal and lingual using diamond burs, and the zone was fully rinsed and cooled by physiological saline at the same time. All fracture models need no reduction and fixation.Forty-eight New Zealand white rabbits were randomly assigned to the nerve growth factor group (NGF group), gelatin sponge group (GS group), blank group, and intact group with 12 rabbits in each group. In the NGF group, the mental neurovascular bundle was cut off and implanted l ml nerve growth factor (10 μg/ml) with gelatin sponge as the carrier. The mental neurovascular bundle was cut off and implanted with normal saline equivalent to NGF with gelatin sponge as the carrier in the GS group. The mental neurovascular bundle was cut off without implanting material serving as the blank group. The intact group retained the neurovascular bundle intact and no material was implanted.After the rabbits were fully awakened from the operation, they were returned to separate cages, and the lower lip response to acupuncture was performed on the same day. Penicillin (0.4 million units) was administered intramuscularly to each rabbit twice a day for 3 days. Before the stitches were removed on the 7th day, the wound was cleaned and the healing status was observed every day.The mental nerve innervated the skin of the lower lip area in front of one side of the chin foramen. If the lower lip did not respond to acupuncture on the first day after the operation, the nerve fracture models were successfully established. Besides, the recovery of nerve reflex was assessed by observing the number of rabbits with lower lip responses to acupuncture at the 2nd, 4th, 6th, and 8th weeks after the operation.At the 2nd, 4th, 6th, and 8th weeks after the operation, three animals in each group were sacrificed and fracture healing was determined by observing and comparing the size of the bone gaps and the clarity of the osteotomy line using cone-beam computed tomography (CBCT) systems. The operated mandible of each executed rabbit was dissected subperiosteally to visually observe the formation of healing tissue at the fracture site as well as the amount of healing tissue formation and degree of fusion. The healing tissues were immediately collected for subsequent hematoxylin and eosin (HE) staining observation and qRT-PCR analysis.Callus tissues from the mandibular fracture area were collected using rongeur, rinsed in physiological saline, and then immediately put into 10% neutral buffered formalin fixative for 48 h. Subsequently, the samples were rinsed in running tap water for 10 min and incubated with 10% ethylenediaminetetraacetic acid (EDTA) (pH = 7.2). The decalcifying solution was changed every 3 days until the decalcification was completed. The decalcification process was finished when the specimen was easily penetrated by a needle without any force. Next, samples were washed in 0.01 M phosphate-buffered saline (PBS) for 10 min and then followed by routine dehydration and paraffin embedding. The paraffin wrapped tissues were cut into 4 μm sections using a Leica microtome . The tissue sections were soaked by xylene solution two times with 20 min to dewax the sections, and then soaked in 100%, 95%, 80%, and 75% alcohol for 5 min, and finally rinsed in running tap water.After deparaffinization and rehydration, the sections were stained with hematoxylin dye for five minutes and then rinsed in running tap water. Soak the sections with 100%, 95%, 80%, and 75% alcohol to dehydrate the sections. The sections were soaked in xylene until the sections were clear, and then the tablet was sealed. Finally, the pathological changes of callus tissue between all groups were observed and photographed using an Olympus BX53 fluorescence microscope  by the following criteria: (1) the distribution of bone matrix collagen; (2) the distribution and number of osteoblasts; (3) the distribution and number of vascular endothelial cells; (4) the arrangement of trabecular.To determine whether exogenous NGF could improve the expression of BMP-9 and VEGF during mandibular fracture by detecting the expression levels of BMP-9 mRNA and VEGF mRNA in four groups of healing tissues at the 2nd, 4th, 6th, and 8th weeks after the operation. For RNA extraction, callus tissue in the mandibular fracture area was collected using rongeur and immediately frozen in liquid nitrogen. The frozen tissue was ground to a fine powder in liquid nitrogen using a freezer mill . Total RNA was extracted using the RNeasy Mini Kit , according to the manufacturer’s instruction. The quantity, degradation, and contamination of total RNA were assessed using a NanoDrop 2000 spectrophotometer  and 1% agarose gel electrophoresis, respectively.−ΔΔCt gave the relative quantitation value of gene expression.RNAs were reverse-transcribed by oligo (dT) primer using the ThermoScriptTM RT–PCR system . QRT-PCR analysis was carried out using an ABI PRISM7300 Fast Real-Time PCR System . The published sequences of BMP-9, VEGF, and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were obtained from GeneBank, and these oligonucleotide primers for the rabbit-specific genes were designed using the Primer Express Software (Applied Biosystems), as shown in Table p value of < 0.05 was considered statistically significant.The descriptive values for BMP-9 and VEGF in different periods in the NGF group, GS group, blank group, and intact group were presented in mean and standard deviations. The statistical analysis was analyzed with SPSS 20.0, . Statistical differences among groups were detected by one-way ANOVA followed by Bonferroni’s multiple comparison test. A A total of 48 New Zealand white rabbits were included in this study. CBCT examination showed that incomplete fractures of the mandible were prepared successfully in all models Fig. . The incAcupuncture was performed on the lower lip on the first day after the operation. The results showed that there was a contraction reaction of the lower lip in the intact group, but no reaction in the NGF, GS, and blank group, which proved that the nerve dissection operation was successful Table . At the The results of CBCT examination showed that the fracture situation of each group was roughly the same, with clear bone incision lines and obvious bone gap Fig. .Fig. 2CMacroscopic observation and CBCT examination demonstrated that callus was formed in the fracture area of each group, and the osteotomy line was clear Fig. a–d. The Macroscopic observation and CBCT examination indicated that the hyperplasia of the callus was obvious in all the four groups, and the bone gap was smaller than that at the 2nd week Fig. a–d. CompMacroscopic observation and CBCT examination determined that the callus at both ends of the osteotomy line in the NGF group and the intact group had fused and calcified, and the fracture line disappeared Fig. a, b. FusThe combined results of macroscopic observation, CBCT examination, and histological analysis showed that the fractures in the NGF group, intact group, GS group, and blank group had completely healed, the osteotomy line had disappeared, and the degree of callus reconstruction was similar and tended to normal bone tissue structure Fig. a–d. TherP < 0.05). The expression level of BMP-9 mRNA in the NGF group was significantly higher than that in the GS group except for the 8th week (P < 0.05) , but there was no statistically significant difference at the other three time points  Fig. . At the Fracture healing, especially in the mandible, is influenced by a combination of neuromodulation and humoral regulation due to the specific physiological and facial parts . ChisaliNGF promotes fracture healing as follows: inducing nerve growth in bone callus, interaction with neuropeptide substance, regulating bone growth factors, promoting angiogenesis factors in callus, and inhibiting osteoclast function . In thisP < 0.05)  Fig. . Hayami P < 0.05), but there was no significant difference at the 4th, 6th, and 8th weeks. The above results concluded that the exogenous NGF facilitated the healing rate at early stage of mandible fracture.This study clarified the effects of exogenous nerve growth factor on the expression of BMP-9 and VEGF in the early stage of mandible fracture healing in rabbits. In detail, the acupuncture reaction indicated that the number of animals with nerve reflex recovery was higher in the NGF group at the 2nd and 4th weeks after the operation, and then remained consistent in the four groups. Similar manifestations were observed in the radiographic and histological appearance, in which the osteotomy line in the fracture area became blurred in the NGF group, the amount of callus formation and the degree of fusion were better, the process of callus reconstruction remained obvious, and a large number of osteoblasts were still visible around the trabecular bone at the 2nd and 4th weeks. And then, there was no significant difference in acupuncture reaction, CBCT, and histological results among the groups at the 8th week. QRT-PCR showed that the expression of VEGF and BMP-9 mRNA in the NGF group was markedly higher than that in the GS group at the 2nd week (It has been reported that NGF could promote the proliferation and differentiation of bone cells and inhibit the formation of osteoclasts through endocrine factors, such as other neuropeptides and hormones, thereby promoting fracture healing . HoweverThe results of this study demonstrated that the exogenous NGF would promote nerve repair and angiogenesis at the fracture site in the early phase of mandibular fracture and improve the expression of BMP-9 and VEGF in the early phase of mandibular fracture to accelerate the healing of the mandibular fracture.Additional file 1: Table S1. The expression level of BMP-9 mRNA in the callus tissues at four stages.Additional file 2: Table S2. The expression level of VEGF mRNA in the callus tissues at four stages.


After publication of this article , concernThe complete underlying data for the Figs 1, 3, and 4 and the data underlying the Supporting Information tables has been provided within the Supporting Information file .In addition, in the discussion of the article cited as reference 15 in the text, the autPLOS ONE re-assessed this article in light of issues about the reported results raised post-publication and confirmed that the article meets PLOS ONE’s publication criteria, that the article as reported is valid and no further actions are required.The authors apologize for the errors within the published article.S1 File(ZIP)Click here for additional data file.


One of the key components of the designing procedure of a structure of hard anti-wear coatings deposited via Physical Vapour Deposition (PVD) is the analysis of the stress and strain distributions in the substrate/coating systems, initiated during the deposition process and by external mechanical loads. Knowledge of residual stress development is crucial due to their significant influence on the mechanical and tribological properties of such layer systems. The main goal of the work is to find the optimal functionally graded material (FGM) coating’s structure, composed of three functional layers: (1) adhesive layer, providing high adhesion of the coating to the substrate, (2) gradient load support and crack deflection layer, improving hardness and enhancing fracture toughness, (3) wear-resistant top layer, reducing wear. In the optimisation procedure of the coating’s structure, seven decision criteria basing on the state of residual stresses and strains in the substrate/coating system were proposed. Using finite element simulations and postulated criteria, the thickness and composition gradients of the transition layer in FGM coating were determined. In order to verify the proposed optimisation procedure, Zr-C coatings with different spatial distribution of carbon concentration were produced by the Reactive Magnetron Sputtering PVD (RMS PVD) method and their anti-wear properties were assessed by scratch test and ball-on-disc tribological test. Moreove2O3/TiN . One of the possibilities of solving the above-mentioned problems occurring in multilayer coatings is the use of the concept of functionally graded materials (FGM) , charact1, low abrasive wear W2 and high fracture toughness W3. Hence, one of the important problems connected with the design of the coating’s structure in the case of multilayer coatings is the selection of the chemical composition, mechanical properties and thickness of individual layers and, in the case of FGM coatings, the selection of spatial distribution of its chemical composition, in order to achieve the maximum values of W1–W3 [Overall, the durability and reliability of a hard anti-wear coating require high adhesion to the substrate Wof W1–W3 ,15,16,17of W1–W3 ,23,24,25of W1–W3 ,27,28,29of W1–W3 ,31,32. In the area of the above-mentioned issues, the work in  deservesIn summary, despite the significant progress made in the design of gradient anti-wear coatings, no generally acceptable and unambiguous set of optimisation guidelines and criteria has been formulated to date. Hence, this work is part of the search for representative criteria correlated with their anti-wear properties in order to develop an optimisation procedure. The present work is a continuation of the research presented by the authors in  on the oThe main goal of the work is to find an optimal FGM coating’s structure, composed of three functional layers: (1) adhesive layer, providing high adhesion of the coating to the substrate, (2) gradient load support and crack deflection layer, improving hardness and enhancing fracture toughness, (3) wear-resistant top layer, reducing wear. The procedure adopts seven decision criteria, which are functions of stresses and strains in the FGM coating induced by external tangential and normal mechanical loads. Among the newly proposed criteria, there are also three previously developed and tested criteria  adapted The optimisation object is a gradient coating composed of three functional layers: adhesive layer, gradient load support and crack deflection layer, and wear-resistant top layer, with a structure as in td), (2) exponent of the power transition function describing the continuous change in carbon concentration in the gradient layer (p). The domain of decision variables is defined as followsTwo decision variables were postulated in the optimisation task: (1) thickness of gradient load support and crack deflection layer (ZrCCbase)( and ZrCCtop) makes it possible to identify the change in the exponent p with the change in the carbon concentration in the coating. p), for fixed thickness of gradient layer (td). The explicit formula of the adopted power transition functions, describing the spatial distribution of carbon concentration in the gradient layer, is given byThe steel substrate is treated as a homogeneous continuous medium;Substrate and layer materials are elastic-plastic bodies represented by a so-called bi-linear model with work hardening;Before deposition process in substrate initial stresses were 0 GPa;At the boundary between the substrate and the coating mesh nodes are connected—no separation allowed;Spatial distribution of carbon concentration in gradient layer is represented by a continuous power transition function;A homogeneous temperature distribution was assumed in the samples during the deposition of the coatings—the deposition temperature value was 400 °C.In the optimisation procedure, the coating’s thickness was assumed constant, equal to 2.6 µm. Based on the authors’ previous experimental and theoretical investigations ,38,39, aThe COMSOL Multiphysics 5.2a program   was usedThe aim of the research undertaken was to find the carbon concentration profile in FGM layer (load support and crack deflection layer) and its thickness, which would provide high coating fracture toughness, adhesion and wear resistance. A scheme of the proposed optimisation procedure is presented in P0—maximum contact pressure, µ—coefficient of friction, a—radius of contact. The maximum value of the contact pressure and the contact radius determined for the elastic deformation range differ significantly when taking into account the substrate’s plastic deformation. Namely, in the case of taking into account the plastic deformations of the substrate and the coating, the contact area increases and the maximum value of the contact pressure decreases compared to those obtained for pure elastic contact [Basing on classical Hertzian elastic contact theory , in slid contact ,43,44. E be used b.Optimisation of carbon concentration profile in FGM layer (load support and crack deflection layer) and its thickness was done for given continuous 3D external mechanical loads—quasi-static equivalent of the scratch test with diamond indenter with a radius of 200 µm. In the optimisation procedure, seven decision criteria based on the state of stresses and strains in the coating, resulting from internal stresses (after deposition process) and imposed external mechanical loads, was proposed. The first prototype of the set of decision criteria proposed in this paper was presented by the authors in . One of K1 criterion was the weighted sum of the fraction of positive first-principal stresses Iσ and their average value in a given volume of the coating. The explicit formula of this criterion isi is the element number and volume N denotes total number of elements in mesh grid .The K2 criterion was adopted the maximum value of I principal stress in the zone of interface of adhesive layer/gradient layer (As nt layer .(6)K2dtK1 and K2 criteria were already tested as potential measures of coating’s resistance to cracking (through thickness perpendicular cracks) and the mechanical integrity of the adhesive layer/gradient layer interface [The nterface ,45,46.K3 was the maximum value of equivalent plastic deformations in the adhesive layerCriterion As shown in ,28,29,35K4 was the maximum value of the module of shear stresses xyσ in the adhesive layer/gradient layer interface (Criterion nterface (8)K4dt,K5 criterion as the maximum value of III principal stress in the coating.The choice of this criterion is dictated by the relationship between the shear stresses at the layer boundaries and the resistance to the initiation of lateral cracks, which may lead to coating delamination ,46,47. RK5 could be a significant indicator connected with the probability of coating buckling.Therefore, according to the interpretation shown in , the valK6 criterioni is the element number and N is the total number of elements in the analysed coating’s volume in FEM model. The inspiration for introducing this criterion was the work of [The mean value of von Mises stresses in the coating was adopted as the  work of , in whiczyσ stresses on the adhesive layer/gradient layer interface was adopted as the criterion K7.The maximum value of the K7 criterion was introduced due to the relationship of shear stresses in the plane perpendicular to the direction of the indenter motion, and the probability of chipping and delamination due to recovery spallation after the disappearance of the external load at the indenter-coating contact boundary [The boundary ,45,46,48iminK and imaxK denote, respectively, the minimal and maximal value of criteria in the defined domain (1). In the further presentation of the results, only normalized criteria will be analysed without upper index (n), i.e., iKn). Grinding was carried out with a semi-automatic grinder with water-cooled SiC grain sandpaper. The papers were changed gradually from granulation 100 to 2000. The surfaces were then polished with pastes with a monocrystalline diamond suspension with an average grain size of 3 µm, then 1 µm, on a polishing cloth of acetate fibers. Before the deposition process, the samples were washed with acetone at 58.08 g/mol and rinsed in an ultrasonic cleaner with EcoShine Ultrasonic K3 solution containing <5% of each individual of the three nonionic surfactants sodium 5–15 edetate (EDTA), <5% corrosion inhibitor then they were rinsed in deionized water and dried. In the working chamber, substrates were subjected to ion cleaning at a pulse voltage of a glow discharge with an amplitude of 1.5 kV at an Ar pressure of 7 Pa. Sputtering was performed from a metallic Zr target, with a diameter of 114 mm supplied by PLANSEE Composite Materials, Lechbruck, Austria. The target was made by powder metallurgy. Composition: Zr + Hf min. 99.2 wt.%, Hf max. 4.5 wt.%, Fe + Cr max. 2000 µg/g, H max. 50 µg/g, N max 250 µg/g, C max. 500 µg/g, O max. 1600 µg/g, at fixed discharge power of 500 W in a mixed Ar and C2H2 atmosphere by controlling the flow rate of both gases. Different profiles of carbon concentrations in the coatings were obtained by changing the flow rate of C2H2 in the range of 1.5–6.5 sccm. The magnetron source was powered with pulse voltage with a frequency of 1 kHz with a signal modulated by 100 kHz. Substrates were polarised with negative 10 V bias voltage, and their temperature during all the deposition processes was stabilised in the range of 400 ± 20 °C.Zr–C gradient coatings were deposited via reactive magnetron sputtering (RMS) on substrates made of HS5-6-2 steel, in the form of discs that are 32 mm in diameter and 3 mm thick as well as rectangular silicon substrates with dimensions 10 × 20 × 0.5 mm. The steel samples were quenched  and double tempering at 540 °C. The samples in the quenched and tempered condition with a hardness of approx. 63 HRC were provided by FABA S.A. Prior to deposition, the substrates were ground and polished, which resulted in obtaining a mirror state with roughness parameters on average RAfter depositing the Zr-C coatings on silicon substrates, the value of the residual stresses was estimated by measuring the surface profiles of the samples (determining the radius of curvature) with a Hommelwerke T2000 profilometer  using the Stoney formula.® 4.3 software. To determine the value of Young’s modulus and hardness using the Olivier–Pharr model [Indentation measurements were made using a Fisherscope HM2000  micro hardness tester equipped with a Berkovich diamond indenter and WIN-HCUrr model , indentac1) was determined, as well as the load value at which the coating was completely removed from scratch path (Lc3).The fracture toughness and adhesion of the coatings were assessed by scratch test using a CSM Revetest scratch tester . The tester was equipped with a diamond conical indenter with a spherical tip of 200 µm radius. The indenter was moved across the surface of the coating at a speed of 10 mm/min; the force loading the indenter increased linearly from the preload of 90 mN at a speed of 100 N/min to 50 N over a distance of 5 mm. During the test, the normal and tangential force were recorded as a function of the indenter displacement, the acoustic emission signal was recorded and the resulting scratch path was simultaneously observed using optical microscope. On this basis, the value of the load at which the first coating damage occurred , measuring the force and friction coefficient as a function of the sliding distance. The tests were carried out with a normal load of 5 N and with a linear sliding speed of 0.2 m/s. A ceramic alumina ball with a diameter of 10 mm was used as a counter-specimen. Based on the cross-section profiles of the wear tracks obtained with the Hommelwerke T2000 profilometer , the values of the volumetric wear ratio of the sample were calculated.0, is necessary to calculate the values of the adopted decision criteria, using the created FEM models, for each coating prototype in the domain of decision variables. For this purpose, single-layer Zr-C coatings with a carbon concentration of 21 at.%, 51 at.%, 66 at.%, 74 at.% and 84 at.% on HS-6-5-2 steel and Si substrates were produced. Details on the methodology of sample preparation and coating deposition conditions are included in the authors’ previous works [The determination of the values of basic material constants of Zr-C coatings, depending on the carbon concentration, i.e., Young’s modulus E, yield strength Y, tangent modulus TM, as well as the initial residual stress σus works ,38,39. Tx,y) plane and the carbon concentration was also determined , E(C) functions a,b whichtermined .Residual stresses were assessed after the coating’s deposition process basing on measurements of the radius of curvature of the Si/Zr–C substrate/coating systems and calculated using Stoney’s formula .K1–K7 on values of parameter p, of transition function, and thickness of gradient layer (td), were determined  dependences of termined a–g.iK = iK, i = 1, 5, 6 indicate the presence of relatively large changes in the value of the criteria in the neighborhood of the decision variable p = 1 for each thickness td. It follows that the prototype with p = 1 is a kind of a limit prototype in the neighborhood of which significant differences in mechanical properties of prototypes can be expected. It should be noted that in the case of the iK = iK, i = 1, 7 , the increment in gradient layer thicknesses (td) results in a strong differentiation of the prototypes due to their potential anti-wear properties.According to the adopted definition and normalization of each of the criteria, the value 0 corresponds to the minimum (desirable), and the value 1 (unfavorable) to the global maximum. The obtained explicit dependencies K =  in the 7-dimensional space of decision criteria, the distance d = d was determined for each of them from the so-called utopian solution represented by the origin of the coordinate system.In order to perform the selection of all analyzed prototypes, represented by the points N = N, which values are below the level of 0.3, was determined, i.e.,Moreover, for each acceptable solution, the number of criteria d = d and N = N the quality index was defined in the formUsing the dependencies N was 0, the index J was not calculated. The introduced J quality index was the basic criterion for selecting the best solutions—coating prototypes. It contains information about the distance of the tested solution from the so-called utopian solution  in the criteria space and, at the same time, supports the selection of solutions for which individual criteria are below the value of 0.3. In further considerations, it was assumed that the level of 0.3 is a limit value below which the criterion, scaled to the fuzzy variable, is at the Low (L) level. The J index has been defined in such a way that its minimum value corresponds to the best coating prototype. For the analysed domain of decision variables (1), the chart of J is presented in In the case where the value of td = 1 μm, the differences in the values of the criteria between the individual prototypes are low; therefore, these prototypes should have similar anti-wear properties. If the gradient layer reaches about 50% of the total thickness of the coating, an increase in the differences in the values of the criteria between individual prototypes is observed, which leads to their diversification in terms of potential anti-wear properties. Maximum differences in the values of the criteria are achieved in the case of a gradient layer with a thickness of td = 2 μm, which is about 80% of the total thickness of the coating. Thus, in order to obtain the highest diversification of the prototypes in terms of their mechanical properties, prototypes with the highest gradient layer thickness were selected for further experimental research. In particular, prototypes were selected for which the index J has a minimal or maximal value  compared to prototypes with p > 1 for the same thickness of the dt gradient layer. Moreover, among the prototypes with p < 1, there is a prototype ensuring the global minimization of J, while among the prototypes with p > 1, there is a prototype with the maximum value of this quality index. Hence, in further considerations, in order to draw general conclusions about the design of optimal carbon concentration profiles, the solutions will be divided into three groups together with their representatives →min), p = 1 and p > 1; →max). Spatial distributions of the Young’s modulus and yield strength for selected prototypes are shown in By analysing ntatives , i.e., pThen, selected coatings prototypes  were proThe fracture toughness and adhesion of the coatings, which are strongly connected with their anti-wear properties, were assessed by scratch test. c1 and Lc3 critical loads are presented in Microscopic photos of scratch path, illustrating damages of coatings for the Lp > 1  are typical damages of hard brittle coatings (belonging to the group of brittle failure modes in scratch testing) deposited on high-hardness substrates, in this case, an HS -6-5-2 steel substrate with a hardness of H = 8 GPa. The first cracks in the coating (Lc1 = 13 N), the so-called Chevron (angular) cracks, belong to the group of brittle tensile cracks. These cracks arise behind the indenter as a result of tensile stresses, whose values exceed coating tensile strength [c3 = 37 N.Damages occurring in the scratch path for the coating with the value of strength ,57,58. Wp = 1, damages in the scratch path belong to the group of ductile failure modes. The first cracks occurring in the coating (Lc1 = 11 N), with few chippings and areas of delamination along the path, are so-called conformal cracks and are typical for relatively ductile coatings. They result from the action of compressive stresses in front of the indenter, which then slides over the fracture surface and pushes them into the path. With a further increase in the indenter load, buckling spallations become larger and spread to the sides of the scratch path. Consequently, this leads to the complete coatings detachment as the formed cracks extend over the entire thickness of the coating [For the prototype with  coating ,57,58.p < 1 possesses the highest value of the critical force (Lc1 = 23 N) among the tested prototypes. Coating damages in the scratch path, as in the case of the prototype with p = 1, belong to the ductile failure modes group. However, in the case of the prototype with p < 1, no buckling spallations or wedging are observed, which is characteristic of highly ductile coatings possessing relatively low hardness. For this prototype, only conformal cracks are observed, with a small amount of chipping along the scratch path until the coating is fully delaminated from the substrate. The critical force Lc3, for this prototype is 60 N and is about two times higher than in other prototypes.A prototype with p > 1, p = 1 and p < 1, tribological tests  were performed, with simultaneous measurements of the frictional force vs. sliding distance. In the ball-on-disc wear tests, each coating prototype was made on six samples, then, on each of them, two measurements were performed (two measurements were made on each sample to avoid interactions between the obtained tracks and to achieve the same number of cycles at a given sliding distance). For the purposes of wear assessment, for produced prototypes p < 1 prototype, the friction coefficient is lower (COF = 0.045) than for the other prototypes , and (2) exponent of the power transition function, describing the continuous change in carbon concentration in the gradient layer. Seven decision criteria were adopted, being the functions of the stress and deformation states, which simultaneous minimisation allows for obtaining the optimal distribution of stress in terms of preventing the occurrence of cracks under a given load. In order to verify the proposed optimisation procedure, Zr-C coatings, with different spatial distributions of carbon concentration described by power functions, were produced. The aim of the conducted study was to optimise the gradient coating structure in terms the of anti-wear properties. The optimisation procedure developed as part of the research was based on the state of strains and stresses initiated by tangential and normal external mechanical loads, taking into account initial residual stresses in coatings. Two decision variables were adopted in the optimisation procedure: (1) thickness of gradient load support and crack deflection layer  index takes the maximum value from the tested range. This means that in the case of this prototype, extreme and unfavorable effects deteriorating the anti-wear properties should be expected. Although, for the prototype with p > 1, the values of Lc1 and Lc2 are slightly higher compared to the prototype with p = 1, extensive buckling spallations are observed in the scratch test in this prototype. The obtained results clearly indicate that the prototypes with p > 1 are characterised by lower resistance to brittle cracking and delamination compared to the prototypes with p = 1 and p > 1. At the same time, prototypes with p > 1 are characterised by a much higher value of the J index than prototypes with p = 1 and p < 1, for which this index has the lowest values. It follows that the adopted index J can be regarded as a kind of measure of the coating resistance to the occurrence of so-called catastrophic failure modes. The obtained results also prove that using only the critical load Lc1 as a measure of the quality of the coating adhesion to the substrate and its fracture toughness is ambiguous, because coatings with similar Lc1 values may have different types of cracks with the same normal force value in the scratch test. In the case of the prototype with The main aim of the conducted study was to select the optimal structure of the gradient coating in terms of its anti-wear properties, using an optimisation procedure proposed. Using the optimisation procedure with postulated criteria, an optimal FGM coating’s structure was proposed. The chosen prototypes (being the representatives of three main groups of solutions) were produced, and their properties were experimentally evaluated. J quality index was developed, which facilitated the diversification of prototypes in terms of all criteria at the same time, creating subsets of solutions corresponding to the coatings with the best and worst possible anti-wear properties. Using the defined index, it was determined that optimal coatings should be characterised by:p < 1  → min) and the thickness of the gradient layer td at 80% of the total thickness of the coating;Exponent of the power transition function td from the adhesive layer interface;The asymmetric Lorentzian distribution of Young’s modulus and hardness , the maxA strong decrease in hardness and Young’s modulus starting from the maximum, up to the top layer interface.For the needs of the optimal solution selection, the K1–K7 criteria—the values of VL and L in the fuzzy-logic variable space.Based on the experimental tests , it was found that the anti-wear properties of gradient coatings are related to the values of the adopted decision criteria. Namely, it has been shown that the prototypes with lower wear rates and higher critical loads are characterised by the lowest values of the Validation tests of the developed criteria can be extended to other Me–(C) coatings and will constitute an important level in the development of a universal and generally acceptable set of criteria and guidelines for the design of gradient coatings with enhanced anti-wear properties. As part of further research, it is planned to test the developed set of criteria in terms of stability and assessment of the impact of criteria weights on the individual anti-wear properties of other transition metal carbide coatings, e.g., TiC, VC, WC.


This phenomenon might be due to a fear of contracting the virus at hospitals, companies having their employees work remotely and postponing events, people following the Japanese Ministry of Health, Labour and Welfare’s instructional guidelines for going to the hospital, prevention awareness becoming widespread, and a decreased number of tourists. The number of patients visiting Emergency Departments in Tokyo was decreased and the number of COVID-19 infections has remained within the health system’s capacity during the early phase of COVID-19 first wave.The first coronavirus 2019 (COVID-19) patients were reported in China on December 12, 2019, and the first COVID-19 patients were reported in Japan on January 16, 2020. Here, we investigated the number of patients in Emergency Departments (EDs) in three major hospitals in Tokyo, and also briefly discussed about the relationship between the number of patients in EDs and health system’s capacity. We compared the number of patients in 2020 to the average number of patients from 2016 to 2019. Numbers were compared in three periods: before the first COVID-19 patient was reported in Japan (January 1 to January 16), after the government encouraged social distancing (February 26 to March 10), and the interval between them (January 17 to February 25). The average number of daily patients in 2020 ( The first coronavirus 2019 (COVID-19) patients were reported in China on December 12, 2019, and the first COVID-19 patients were reported in Japan on January 16, 2020. The total number of cases in Japan had increased to 552 patients (including 12 deaths) by March 10 , and reqInitially, staff in Emergency Departments (EDs) anticipated the number of patients to increase. In actuality, the number of patients seemed to decrease.Here, we investigated the number of patients in EDs in three major hospitals in Tokyo, and also briefly discussed about the relationship between the number of patients in EDs and health system’s capacity.Hospital characteristics  and the average number of patients visiting EDs per day in three hospitals  were collected. We compared the number of patients in 2020 to the average number of patients from 2016 to 2019 in three major hospitals in Tokyo. Numbers were compared in three periods: before the first COVID-19 patient was reported in Japan (January 1 to January 16), after the government encouraged social distancing (February 26 to March 10), and the interval between them (January 17 to February 25). The Mann-Whitney test was used to perform the comparison of the number of daily patients in 2020 and the 2016–2019 average in 3 Tokyo EDs.n = 122) decreased by 17% compared to the average number of patients from 2016 to 2019 (n = 144)  proposed by MHLW, this contributed the decrease in number of patients visiting EDs and maintain the health system’s capacity in the early stage of the COVID-19 first wave.The number of patients visiting Emergency Departments in Tokyo was decreased and the number of COVID-19 infections has remained within the health system’s capacity during the early phase of COVID-19 first wave.


Thereafter, a survey carried out in the U.S. by the Harvard School of Public Health suggested a strong association between increases in particulate matter concentration and mortality rates due to COVID-19. The presence of SARS-COV-2 RNA on the particulate matter of Bergamo, which is not far from Milan and represents the epicenter of the Italian epidemic, seems to confirm  that the virus can create clusters with the particles and be carried and detected on PM10. Although no assumptions can be made concerning the link between this first experimental finding and COVID-19 outbreak progression or severity, the presence of SARS-COV-2 RNA on PM10 of outdoor air samples in any city of the world could represent a potential early indicator of COVID-19 diffusion. Searching for the viral genome on particulate matter could therefore be explored among the possible strategies for adopting all the necessary preventive measures before future epidemics start. A number of nations were forced to declare a total shutdown due to COVID-19 infection, as extreme measure to cope with dramatic impact of the pandemic, with remarkable consequences both in terms of negative health outcomes and economic loses. However, in many countries a “Phase-2” is approaching and many activities will re-open soon, although with some differences depending on the severity of the outbreak experienced and SARS-COV-2 estimated diffusion in the general population. At the present, possible relapses of the epidemic cannot be excluded until effective vaccines or immunoprophylaxis with human recombinant antibodies will be properly set up and commercialized. COVD-19-related quarantines have triggered serious social challenges, so that decision makers are concerned about the risk of wasting all the sacrifices imposed to the people in these months of quarantine. The availability of possible early predictive indicators of future epidemic relapses would be very useful for public health purposes, and could potentially prevent the suspension of entire national economic systems. On 16 March, a Position Paper launched by the Italian Society of Environmental Medicine (SIMA) hypothesized for the first time a possible link between the dramatic impact of COVID-19 outbreak in Northern Italy and the high concentrations of particulate matter (PM A number of nations were forced to declare a total shutdown due to COVID-19 infection as an extreme measure to cope with the dramatic impact of the pandemic, with remarkable consequences in terms of negative health outcomes, social life and economic loses. This incredible choice of closing regions, States, and entire countries was seen as the only way to cope with the unexpected threat to human health represented by SARS-COV-2 virus due to the high number of infected people requiring intensive care in hospital setting in relation to the limited beds available. At the date of 23 April, there were about 2,700,000 confirmed cases of COVID-19  and almost 190,000 deaths recorded worldwide. The majority of diagnoses were made both in Europe  and in North America . In Asia, Iran  and Turkey  had more infections than China , the country where the pandemic started and was subsequently well contained in the province of Wuhan. Surprisingly, the Indian sub-continent recorded only 23,000 cases, and a minor number of cases were diagnoses in South America , Africa  and Oceania  [10 and PM2.5), already recognized as one of the most polluted zones in Europe [The Italian population is less than 20% of that of the United States, but the number of deaths recorded in Italy  are up to 50% of those reported in the U.S. . These epidemiological figures are mainly due to the rapid spreading of COVID-19 in Lombardy and Northern Italian regions of the Po Valley (Padana Plain), an area characterized by constant high concentrations of particulate matter  and the spreading of the COVID-19 infection before the shutdown decided by the Government [10 exceedances was much more frequent in Lombardy and in cities located in the Po valley than those observed in Rome and Southern Italy, where the diffusion and lethality of the virus was significantly lower when compared to those of Northern regions [The Italian Society of Environmental Medicine (SIMA) has been the first to hypothesize—by releasing a specific Position Paper on 16 March—a possible link between the high mortality rates observed in Northern Italy due to COVID-19 and the PM concentrations ,4. A sigvernment . The numMeanwhile, a survey carried out in the U.S. by the Harvard School of Public Health has suggested a strong association between increases in particulate matter concentration and mortality rates due to COVID-19, with The Lancet scientific community highlighting the need for adopting a planetary health perspective on COVID-19 outbreak ,7. FurthIn many countries, a “Phase-2” is approaching and many activities will re-open soon, although with some differences, depending on the severity of the outbreak experienced and SARS-COV-2 estimated diffusion in the general population. At the present, possible relapses of the epidemic cannot be excluded until effective vaccines or immunoprophylaxis with human recombinant antibodies will be properly set up and commercialized. COVD-19-related quarantines have triggered serious social challenges, so that decision makers are concerned about the risk of wasting all the sacrifices imposed to the people in these months of quarantine. The availability of possible early predictive indicators of future epidemic relapses would be very useful for public health purposes, and could potentially prevent the suspension of entire national economic systems. The presence of SARS-COV-2 RNA on the particulate matter of Bergamo, which is not far from Milan and represents the epicenter of the Italian epidemic, seems to confirm  that the virus can create clusters with the particles and be carried and detected on PM10 . The preThe availability of early direct or indirect indicators of SARS-COV-2 diffusion could save many lives and reduce the economic impact of future possible outbreaks by giving Governments enough time to cope with these new kind of challenges .In Italy, lethality rates showed a remarkable increase in the oldest age groups, reaching 40% in men aged >80 years old (20% in women), and 30% in males between 70 and 79 years old . People aged 60–69 still present a lethality rate as high as 12% in men and 5.6% in women, accounting for 15% of infections and 11% of deaths. Elderly people >80 years old represent 22% of positive cases and 50% of the deaths, while patients aged 70–79 account for additional 16% of infections and 30% of deaths [On the other hand, COVID-19 has clearly shown its potential to become a hospital infection, at least in Europe and U.S. , with 10% of infected people being healthcare workers, and a huge proportion of cases and deaths possibly related to infections acquired in hospital setting or nursing homes ,24. Inde