The ergogenicity of caffeine on several exercise and sport situations is well-established. However, the extent of the ergogenic response to acute caffeine ingestion might greatly vary among individuals despite using the same dosage and timing. The existence of one or several individuals that obtained minimal ergogenic effects or even slightly ergolytic effects after caffeine intake  has been reported in several previous investigations. Nevertheless, the concept non-responding to caffeine, in terms of physical performance, relies on investigations based on the measurement of one performance variable obtained once. Recently it has been suggested that correct identification of the individual ergogenic effect induced by caffeine intake requires the repeated measurement of physical performance in identical caffeine–placebo comparisons. In this communication, we present data from an investigation where the ergogenic effect of acute caffeine intake (3 mg/kg) was measured eight times over a placebo in the same individuals and under the same conditions by an incremental cycling test to volitional fatigue and an adapted version of the Wingate cycling test. The ergogenic response to caffeine varied from 9% to 1% among individuals, but all participants increased both cycling power in the incremental test and Wingate mean power at least three to eight times out of eight the caffeine–placebo comparisons. These data expand the suggestion of a minimal occurrence of caffeine non-responders because it shows that all individuals responded to caffeine when caffeine is compared to a placebo on multiple and repeated testing sessions. Nutrients in 2018, because they offered new insights towards unveiling the causes of the variability on physiological responses to caffeine. With this communication, we want to expand the understanding about why some individuals obtain less ergogenic benefits after the ingestion of a moderate dose of caffeine than others, and perhaps it will help to dispel the myth/concept of non-responders to caffeine, at least when referring to exercise performance. 2018 has been a prolific year for the publication of manuscripts aimed at explaining the causes of the interindividual variations for the ergogenic response of caffeine ingestion on exercise performance. Particularly, we read with interest the reviews by Southward et al. , publishThe utility of caffeine to increase physical performance in several exercise and sport situations is well-established and has been recently confirmed by systematic reviews and meta-analyses ,5,6,7. IRecently, Pickering and Kiely  and GrgiWe have recently published an investigation where the ergogenic effect of caffeine (3 mg/kg) was measured eight times over a placebo in the same individuals by using two physical performance tests: an incremental cycling test to volitional fatigue (25 W/minutes) and an adapted version of the Wingate cycling test . The perBecause the tolerance to the ergogenic effect of caffeine was not completed after 20 days of consecutive ingestion, we have performed a sub-analysis for this communication to present the individual responses to acute caffeine intake in each of the eight identical caffeine–placebo comparisons. In conclusion, the data provided in this communication do not dispute the existence of a great interindividual variability to the ergogenic effects of caffeine ingestion, nor the genetic, environmental, or epigenetic causes associated to this variability. However, this analysis suggests that all individuals, to some extent, positively respond to the acute ingestion of 3 mg/kg of caffeine, while the magnitude of the ergogenic effect might be the result of the totality of consequences induced by caffeine ingestion on the human body. In this respect, this communication suggests that the individuals with a high response to the cardiovascular effects of caffeine would be less prone to obtaining ergogenic benefits from this stimulant. Caffeine ergogenicity might be subject to genetic influence, but future investigations on this topic should assess the individual ergogenic response to caffeine by using different forms of exercise testing and/or by using well-standardized caffeine–placebo comparisons on multiple, repeated testing sessions. In the point of view of the authors, this repeated measurement of the ergogenic effect of caffeine would help to reduce the equivocal findings of previous investigations on genetic variations . From a


A technique to reduce burr height in titanium micro-drilling is presented: a poly (methyl methacrylate) coating was applied before machining on the upper and lower surfaces of a titanium specimen (0.5-mm thick). After drilling, a cleaning process (acetone bath) was executed to eliminate the coating, and holes with less burr were obtained. The coating process was executed with a spin-coating machine. To test the efficacy of the technique, two different coating thicknesses (7.9 and 5.4 μm) and two drill bits (0.25- and 0.5-mm diameter) were evaluated. Qualitative and quantitative analyses of the holes obtained were performed with scanning electron microscopy and three-dimensional microscopy, respectively. The results highlight the efficacy of the technique to reduce the burr height by 70% in coated titanium relative to that in an uncoated titanium sheet. Manufacturing technologies for material removal have been constantly evolving to fulfill consumer requirements. Currently, downscaling of processes such as machining, injection molding, and electric discharge machining (EDM) is needed to produce microscale workpieces that are used in fields ranging from aeronautical to biomedical applications ,2. DespiAs can be observed, the path of the absolute burr height shows an increase of the burr height in the range from 0.1 mm ≤ d ≤ 7 mm. Afterwards, the burr process mechanism becomes unstable for a change of burr geometry (from crown to ring). On the opposite, in the case of the micro drill bit with a diameter less than 2 mm, Figure 16 in Ref.  shows hoIn micromachining, this trend leads to a high amount of burr that surrounds the hole and affects its function. The exit burr degrades the quality of parts and is problematic for assembly, so a deburring process is necessary. Problems arise during manual deburring, which is often performed at a conventional size level and is difficult to apply. A chemical deburring process is often unsuitable because it can distort the shape of the hole. Moreover, burr generation is critical not only to industry but also to scientific applications. In micro-drilling, the dimensions of important output parameters are affected, such as hole diameter and roundness. These parameters are fundamental in tool wear analysis, but the burr makes it difficult to use a machine tool interferometer. In a previous study, the author tested a method to avoid this problem by choosing brass as a reference material to reduce burr interference in hole diameter measurement . HoweverIn the literature, several solutions have been studied to minimize burr. Referring to the process parameter, a linear correlation between the burr height and feed per tooth was found , in partAnother approach that could be followed to reduce burr height is to apply an auxiliary material on the top and the bottom of the workpiece. Based on chip mechanism formation, burrs are formed at the entrance and exit surfaces of the workpiece and are due to tearing and bending actions followed by shearing or lateral extrusion; so the possibility to apply on these surfaces a material that could be removed after playing a significative role in protecting the surface form the press foot, driving the drill bit and improving the accuracy and in particular to reduce the burr height . This teTo experimentally evaluate the proposed method, two thicknesses of coating and two different drills diameter were tested. The efficacy of the method in terms of burr homogeneity and height was analyzed with scanning electron microscope (SEM) and 3D digital microscopy, respectively. The results highlight some benefits and critical aspects of the proposed approach.Of interest is the suitability of the method for application in biomedical device production. Titanium is strong, biocompatible, and completely resistant to bodily fluids, making it the material of choice for the manufacture of a myriad of medical and dental devices, such as artificial valves in the heart ; stents ensure a low and controlled film deposition that contributes a negligible amount to the workpiece thickness;guarantee good adhesion between the substrate and the film to avoid detachment during the micro-drilling process;use a material that can be easily removed, avoiding any modification to the machined surface.The top and bottom of the part to be machined are first covered with a film (step A), as shown in h is given by Equation (1).K is a constant characteristic of the solvent-polymer system used, and C and f denote the concentration of the solution and the rotational speed (rpm) of the machine, respectively [Based on these assumptions, spin-coating was selected as the deposition technique. Spin coating is widely used in science and engineering to deposit uniform coatings of organic materials and to uniformly distribute particulate matter on a flat surface ,24. In tectively . The coaDrilled holes were realized with a Kern Pyramid Nano, a five-axis ultra-precision CNC machine , as shown in Two different diameters (0.5 and 0.27 mm) of HSS DIN 1899 drill bits  were used in the experimental campaign. The choice of the two drill diameters considered that, when moving from macro- to microscale processing, the drill’s core in proportion to the diameter is larger for smaller diameter tools in order to give them strength, which causes the chisel edge’s length to increase and influences the micro-drilling process reactions ,27. In oAfter drilling, the PMMA was removed by ultrasonic cleaning in an acetone bath for 10 min. The acetone chemically reacts with the PMMA and avoids any metal microstructure modification. Because it is possible for the ultrasound process alone to reduce the burr, uncoated sheets were also cleaned. As an example, images of a titanium sheet drilled with a 0.5-mm drill bit diameter are shown in To analyze burr homogeneity, images of the drilled holes before and after an ultrasonic cleaning in an acetone bath were acquired by SEM with a tungsten filament. The SEM analysis made it possible to establish the presence or absence of PMMA on the sheet after the cleaning operation due to a difference in electron beam absorption of PMMA that causes localized darker areas to appear . Moreover, according to previous research [After SEM analysis, the burr height for each test was measured by 3D digital microscopy (Hirox). A 3D model of each hole was captured for each test, and eight height measurements were acquired. A statistical approach was executed to analyze the results: a two-way ANOVA to verify the significance of coating and replicas and a Tukey’s range test to demonstrate whether the burr heights were significantly different from each other. The results of these statistical analyses are shown in p-value of coating <0.05) and the robustness of the experimental design (differences among replicas are not significant). The results of the Tukey’s range test show that an improvement in burr reduction is achieved when a coating is applied, but the thicknesses of coatings tested yielded comparable burr heights. To better highlight the efficacy of the method, the mean height reduction and histograms with standard deviation are reported in The ANOVA results confirm the efficacy of the technique  after a machining process without affecting their biocompatibility. In particular, nowadays different medical devices are produced using additive manufacturing processes that lead to the possibility of customizing the part design; however, additive process need post process machining operations to improve surface roughness or to realize micro features so that a technique able to reduce burr formation is needed. Future studies will be designed to understand the correlation between hole quality and coating thickness better.


Sensing the voltage developed over a superconducting object is very important in order to make superconducting installation safe. An increase in the resistive part of this voltage (quench) can lead to significant deterioration or even to the destruction of the superconducting device. Therefore, detection of anomalies in time series of this voltage is mandatory for reliable operation of superconducting machines. The largest superconducting installation in the world is the main subsystem of the Large Hadron Collider (LHC) accelerator. Therefore a protection system was built around superconducting magnets. Currently, the solutions used in protection equipment at the LHC are based on a set of hand-crafted custom rules. They were proved to work effectively in a range of applications such as quench detection. However, these approaches lack scalability and require laborious manual adjustment of working parameters. The presented work explores the possibility of using the embedded Recurrent Neural Network as a part of a protection device. Such an approach can scale with the number of devices and signals in the system, and potentially can be automatically configured to given superconducting magnet working conditions and available data. In the course of the experiments, it was shown that the model using Gated Recurrent Units (GRU) comprising of two layers with 64 and 32 cells achieves 0.93 accuracy for anomaly/non-anomaly classification, when employing custom data compression scheme. Furthermore, the compression of proposed module was tested, and showed that the memory footprint can be reduced four times with almost no performance loss, making it suitable for hardware implementation. The benefit of using superconductivity in industrial applications is well understood. However actual application of superconducting devices is still limited by difficulties in the maintenance of cryogenic stability of superconducting cables and coils. In many cases, it is hard to design safe superconducting circuit. A small mechanical rearrangement releases enough energy to initiate local avalanche process (quench) leading to loss of superconducting state and next to overheating of the machine and then even to melting. Therefore superconducting machines require a special protection system.In general, such a system consists of data producers and processing servers. The producers are electronic devices located close to individual superconducting machines which require protection. This device (producer) is capable of collecting and processing data and generating the activation signal for local actuators. The servers are capable of storing and analyzing data delivered by producers through the network.The overarching research goal is to improve data processing within the producers and to move a part of the analysis task into them in order to reduce network load. The preliminary results of this research were presented in Ref. , which fdevelopment of a neural algorithm dedicated to detecting anomaly occurring in the voltage time series acquired on the terminals of superconducting machines in electrical circuits,design and verification of the complete processing flow,introduction of the RNN-based solution for edge computing which paves the way for low-latency and low-throughput hardware implementation of the presented solution,development of a system level model suited for future experiments with the adaptive grid-based approach; the software is available online see .The presented research main contributions are as follows:One of the biggest superconducting systems is installed at the Large Hadron Collider (LHC) accelerator at the European Organization for Nuclear Research (CERN). Despite its scientific purpose, the LHC should be considered as a huge industrial system. The final product of this factory is the total number of particle collisions. During the steady operation, every second, 40,000,000 collisions are performed in three different interaction points. The LHC consists of a chain of superconducting magnets. The chain is located in an underground circular tunnel, 100  in Ref. .When the LHC collides particles, even a tiny fraction of energy stored in each proton beam can cause a magnet to leave the superconducting state. Such an occurrence is named a quench, and it can severely damage the magnets in case of machine protection procedures failure. These procedures mainly relay on triggering the power down of the whole accelerator when resistive part of voltage on one superconducting element exceeds a predefined threshold. This study concerns only a protection system of superconducting elements inside the LHC.A protection system known as Quench Protection System (QPS) has been installed at the LHC since the beginning and it successfully works since ten years of the LHC operation. The detailed description of the existing system can be found in Refs. ,4. The pThe data is continuously buffered in a circular buffer. Some of the samples  are directly transmitted to the CERN Accelerator Logging Service (CALS) database in the cloud. The CALS serves permanent monitoring of almost every device in the CERN’s accelerator’s complex. The sampling rate for this service is very low, in the best case it is 10 The presented protection system underwent many upgrades introduced during breaks of the LHC operation. However, the emergence of new superconducting materials opens a question concerning detection algorithms for application in the future protection system again. Such experiments are conducted in SM18 CERN’s facility see , currentAnomaly and novelty detection methods have been researched over many years ,6,7 whicTraining dataset is different for novelty and outlier detection. In novelty detection, it is not contaminated by anomalies—all outliers need to be removed beforehand. On the contrary, the training procedure of the outlier detection model involves incorporating anomalous data into the training dataset. Both flows employ an unsupervised approach as a training procedure, although some of the procedures may be boosted using some external hyper-parameters such as contamination factor, thresholds or max features that are taken into account in the training process.In this work three different algorithms were used as a baseline for the RNN-based approach proposed by the authors: Elliptic Envelope, Isolation Forest (IF), and One-Class Support Vector Machine (OC-SVM) ,16,17,18Another useful method, invented in 2008, is the Isolation Forest [OC-SVM is usually considered to be a novelty-detection method, and the training data should not contain outliers. It performs well in high-dimensional space where there is no assumption regarding the distribution of the underlying data. However, if the data is well distributed  the Isolation Forest or Elliptic Envelope may perform better.The presented methods assume the spatial structure of the data with no temporal relationships. There is a set of methods such as ESD, ARIMA, Holt-Winters ,22 whichWhen detecting anomalies in time series, RNNs are both scalable and adaptable which is critical when it comes to design and implementation of complex anomaly detection systems ,24,25. Rstatic [adaptive data quantization [In the authors’ previous works concerning superconducting magnets monitoring Root-Mean-Square Error (RMSE)  and bothstatic  and adaptization ,25 approstatic quantization was used, mapping the input data into a set of m equal-width bins. This method, however, resulted in sub-par results, stemming from the uneven distribution of the samples in the bins, up to the point where nearly all samples occupied only one or two bins  in such a way, that all categories have  the same samples cardinality , Elliptic Envelope, Isolation Forest, OC-SVM, Long Short-Term Memory (LSTM) and Gated Recurrent Unit (GRU).Depending on the system configuration , some moIn the classification mode, used in the experiments presented in this paper, the model is trained using data containing anomalies (except for models belonging to the novelty detection category). Instead of trying to predict the next (quantized) value, it directly classifies the sample as either anomaly or not.The models can be roughly divided into the ones working with either spatial  or temporal data . Relevant data preprocessing and structuring, as well as model training and testing, is coordinated by one of the possible detectors. The model/detector combination used in particular setup is defined in configuration file. This option ensures the system extensibility since the detector does not need to know about all possible models in advance.Currently, the experiments are carried out using the software implementation of the system. The target system, however, will need to be implemented in hardware to ensure it complies with latency requirements. To fit the Neural Network (NN) model onto the Field-Programmable Gate Array (FPGA) or Application-Specific Integrated Circuit (ASIC) board, it needs to be compressed while retaining the high accuracy . The reaDeep Learning models have a range of features which render them superior to other similar Machine Learning models. However, they usually have high memory footprint as well as require substantial processing power . Computix from a quasi-continuous space of IEEE-754 notation is mapped to fixed-point value q, represented using During a quantization, a floating-point number linear quantization used during experiments can be described by the following equation:The minmax quantization used during experiments can be described by the following equation:The log_minmax quantization, where:Also tested was tanh quantization used during experiments can be described by the following equation:The The main idea behind coefficients quantization is using a dynamic range of the available number representation to its fullest, and meet the requirements of the hardware platform to be used for deploying the system at the same time. In our implementation, the so-called dynamic fixed-point notation was used. It allows emulating fixed-point number representation using floating-point container. It is worth noting that most of edge computing platforms require linear quantization due to the fixed, a priori defined size of internal registers and arithmetic processing elements. FPGA and custom-designed ASIC which this work is targeting have no such limitation.A series of experiments were conducted to practically examine performance of the proposed methods. Different configurations of the module setup were used in order to expose impact of different parameters of the proposed algorithm on the overall performance of the anomaly detection system. Furthermore, the performance of the proposed solution was compared with a range of state-of-the-art algorithms.The dataset used in the experiments contained 2500 series retrieved from PM database, with 64-16-20 training-validation-testing split. 2415 of those series had a length of 1248 samples, while the remaining 85 series had a length of 1368 samples. For each of the series, the four input channels were available:Anomalies were marked based on the value of Before the start of experiments, the data was normalized. The example data series (and results) visualizations can be seen in During the experiments two main quality measures were used: F-measure and accuracy. While F-measure is better suited to evaluate the results of anomaly detection, in case of PM data the relative lack of imbalance between anomalous and normal samples  makes the accuracy also a viable metric.Additionally, the NN models quantization results are usually measured in terms of accuracy, so its usage allows to relate our results with others found in literature. For example, the drop in accuracy resulting from quantization should be no higher than one percentage point .An accuracy can be defined as:An F-measure is calculated using two helper metrics, a recall , also caThe During the experiments two The Receiver Operating Characteristic (ROC) curve is a graph used to analyze the operation of the binary classifiers as the one presented in this work. It shows the performance of the model taking into account all classification thresholds. True Positive Rate (To derive quantitative conclusions from ROC curve Area Under Curve (AUC) may be employed. It measures the whole two-dimensional area under the ROC curve. It may be considered as an integral operation performed from points  to  on a ROC graph. AUC values fall into a range between 0 and 1. A model whose predictions are 100% wrong has an AUC of 0.0, the one which works perfectly hasAUC of 1.0.The initial experiments attempted to determine the impact of history length . Since it ignores the input data entirely, its results do not depend on the For the other models’ tests, based on the previous experiments, the values of It is worth noting that the presented methods such as OC-SVM, Isolation Forest, or Elliptic Envelope are more sensitive to the data distribution and perform well for specific kind of underlying data . In the case of the presented CERN data, the distribution is not always stable (varies across setups and magnets). It is also worth noting that the distribution as such does not tell much about temporal aspects of the analyzed data. It may happen that the signals of the same distribution have different temporal shape. This is even more pronounced for more temporarily complex signals see .The protection system for superconducting machinery existing at the LHC is a vast distributed system installed around the whole circular tunnel. It consists of many individual units connected with a dedicated network. The approach used to design protection units is hard to scale and requires laborious manual adjustment of working parameters. The presented work explores the possibility of using the RNN to build a protection device of a new generation. The idea is to perform on-line analysis inside local protection unit using data acquired with a much higher sampling rate without sending such a massive amount of data to the cloud.One of the main advantages of the proposed methodology is the simplicity of the parameters setting and adjustment through a complete workflow. Only the model architecture and data quantization levels need to be selected, and even those can be automatically optimized. Additionally, since the solution is based on NNs, it can be extended  to use more sensors (or data streams) or even incorporate text tags , while keeping the overall architectural design the same, even for various types of magnets. It is also possible to fine-tune or retrain RNN-based modules when data has changed  when in the traditional approach it would require reconsideration and restructuring of the existing solution. This architectural uniformity makes it a good candidate for implementation in a distributed edge-computing cluster of sensors, trained in an end-to-end fashion. Such a holistic approach can significantly reduce overall resources consumption, latency, and throughput.The conducted experiments showed that using large The coefficients quantization level should also be considered a meta-parameter of the model optimization. Experiments showed that the selection of any value equal to or above 8 bits does not lead to noticeable performance degradation. Careful choice of the quantization level may allow reducing memory footprint even more; however, it must be noted that below 8 bits the accuracy of the model oscillates.Overall, due to the relatively small size of the neural models and the possibility of significantly reducing their memory footprint (


One of the most promising techniques of recent research is adsorption. This technique attracts great attention in environmental technology, especially in the decontamination of water and wastewaters. A “hidden” point of the above is the cost of adsorbents. As can be easily observed in the literature, there is not any mention about the synthesis cost of adsorbents. What are the basic criteria with which an industry can select an adsorbent? What is the synthesis (recipe) cost? What is the energy demand to synthesize an efficient material? All of these are questions which have not been answered, until now. The reason for this is that the estimation of adsorbents’ cost is relatively difficult, because too many cost factors are involved . In this work, the first estimation cost of adsorbents is presented, taking into consideration all of the major factors which influence the final value. To be more comparable, the adsorbents used are from a list of polymeric materials which are already synthesized and tested in our laboratory. All of them are polymeric materials with chitosan as a substrate, which is efficiently used for the removal of heavy metal ions. One of the most promising techniques of recent research is adsorption. This technique attracts great attention in environmental technology, especially in the decontamination of water and wastewaters. It is considered that adsorption is one of the most efficient techniques for limiting or even completely cleaning water and “heavy” industrial effluents. The materials used in these techniques  can be easily applied in the tertiary stage of the biological treatment or water-cycle, having an ultimate target of capturing and binding the last remaining pollutants existing in the liquid phase  of this (last) stage. The potential of this technique is so strong that more-and-more adsorbents are tested in order to find the most suitable one for further examination. The common question now is why adsorption is so promising, but the answer is easy if we look at the classic “bibliographic” advantages of this. Adsorption is an easy method, which can be applied without any special instrumentation, only some large-scale industrial adsorption beds  are required. Moreover, this technique is simple and fast, while the materials used can be easily reused after appropriate and simple pre-treatment ).Nowadays, a wide range of these types of adsorbents are extensively used, initially in lab-scale experiments for optimization and then in real industrial processes. Activated carbon, inorganic oxides, agricultural wastes, clays, and carbons are some of adsorbents used. However, special attention has recently been given to the use of polymeric materials because they can easily be modified based on the need of the pollutant. For example, if the pollutant is an anionic dye, the polymer can be grafted with positively charged groups (amino groups) to improve the attraction and consequently the adsorption ability. Grafting co-polymerization is a polymerization technique that allows for adding functional groups to chitosan. It can occur by utilizing a variety of options, such as free radicals, radiation, and enzymes ,2. The mA “hidden” point of all the above is the cost of adsorbents. As can be easily observed in the literature, there is not any mention about the synthesis cost of adsorbents. What are the basic criteria with which an industry can select an adsorbent? What is the synthesis (recipe) cost? What is the energy demand to synthesize an efficient material? All of these are questions which have not been answered, until now. The reason for this is that the estimation of adsorbents cost is relatively difficult, because too many factors are involved .N-deacetylation of (its origin compound) chitin. The major advantage of chitosan is the existence of modifiable positions in its chemical structure. This gives chitosan the opportunity to be employed in different applications [The novelty of the present work is clear, we present the first estimation cost of adsorbents, taking into consideration the cost factors which influence the final value. To be more comparable the adsorbents used are a list of polymeric materials which are already synthesized and tested in our laboratory. All of them are polymeric materials with chitosan as a substrate, which is efficiently used for the removal of heavy metal ions. Chitosan-based materials were selected because this polymer (poly-β-1→4)-2-amino-2-deoxy-D-glucose) is a nitrogenous (amino-based) polysaccharide, which is produced in large quantities by -2-amino-ications ,10,11,12Large-scale data was gathered during the initial stage of the research process. The top-down approach was utilized to assess and verify the chitosan market share. Multiple studies and information published in various sources  were taken into account while performing the secondary research. The process involved the use of multiple other avenues of information such as directories and databases to identify and obtain information for the purposes of more technical and market-oriented research on the chitosan market. This work explores the current market trends, analyzes past data from 2010 to 2018, and discusses the forecasts for the following years, ranging from 2020 to 2025.The data was obtained from various sources, for the most part via in-person interviews with the corresponding managers of two Greek Chemistry Laboratories. They were selected due to their experience with the subject matter. The main point of the interviews was the establishment and assessment of a list of attributes of “popular” adsorbents.Conducting interviews in person offers the advantage of observing the interviewee’s reactions, as well as listening to their replies unobtrusively. Our approach was based on unstructured interviews because of their flexibility for all people involved, as suggested by Gubrium and Holstein . In addiIn an effort to explore the adsorption phase in more depth and to uncover the factors that characterize the adsorbents, we conducted a literature search to identify and further analyze their recipes. The most cited ones were selected, so that the corresponding cost factors could be evaluated. Raw material cost prices for the study of chitosan were obtained from publicly released catalogues. It should be noted that chitin and chitosan products can have very wide price ranges, depending on the quality of the final product. For example, chitosan prices might range between United States Dollar (USD) 10 to USD 1000 per kilogram. The costs calculated in this work are all translated to euros (€). The analysis took into account multiple market prices, as provided by vendors all over the world. The raw material cost for each case included the adsorbent cost as well as the metal recovery cost.The energy cost corresponds to the energy spent for the various stages of the adsorption process. Electricity costs per KWh used are based on the average energy price in Greece for 2019 (0.194 Euro/KWh). This price was retrieved by the Hellenic Public Power Corporation S.A. [This type of cost consists of the compensation of researchers participating in the project, with the addition of taxes and benefits. For the purposes of this study, the personnel required for the synthesis process comprises of 1 researcher working for 1 work-day . The average wages of the personnel were assessed based on information from Glassdoor , which mChitosan has multiple applications across various industrial sectors which renders it quite attractive for investors. The high cost of production, however, is a significant limiting factor. Researchers are focusing on making it more cost effective, which can also be achieved if we can reach economy of scale. On this basis, two major modifications can be found in the literature: (i) grafting reactions to enhance the adsorption capacity, and (ii) cross-linking reactions to make the final product more rigid to extreme conditions  and increase the reusability.Grafting cationic groups into chitosan has been utilized for a variety of applications. It has been successful in removing anionic pollutants. Li et al.  producedRaw chitosan  is limitThe main contributors of growth for the chitosan market are the high availability of raw materials and the emerging applications and applicability in multiple sectors. Thorough research and development activity on pre-existing technology is yet another reason for a market-size growth, despite the expensive production process of high-quality chitosan. It should be noted that occasional product inconsistency due to seasonal, regional, or chemical modifications might hinder the market growth to a certain degree .It should be noted that the adsorption ability of the materials mentioned in this work also rely on other experiment conditions including pH levels, starting concentration level, contact duration, dosage, and competitive ion presence. Wan Ngah and Fatinathan were successful in cross-linking chitosan beads with GLA as a means of removing Cu(II) ions in aqueous solutions . The croAccording to Transparency Market Research , globallGlobal Market insights published and estimate of 1.5 billion for 2017 . Market For comparison purposes, the outcomes of this work, along with information about the adsorption capacities of a range of chitosan-based adsorbents from the literature, are presented in c is the energy cost (€), PD is the power consumed by the device (kW), a is a load factor , and Cc is the energy cost (€/KWh).To calculate the recipe cost, According to Recipe costs depend on a variety of factors, ranging from current research needs, expertise, and appropriate recipe selection. For example, the same material could be evaluated differently, because an experienced researcher will know how to find and select a lower cost recipe, without undermining the final product quality.The cost analysis for any technology is the most common form of cost evaluation as it basically takes into account all of the costs (direct or not) of a product throughout its lifecycle. The labor and energy costs take up a very significant percentage of the final cost of the chitosan synthesis process. Almost 70% of the total recipe cost is labor cost. Raw materials comprise 23% of the total recipe cost. It is noted that the energy cost does not surpass 45% of the final cost. It therefore becomes obvious that the labor cost is the most significant cost factor of the recipe process for chitosan. This recipe cost is far higher than the material’s market price, which currently spans between. Operational costs were the main factors affecting the recipe cost evaluation. These include raw materials, personnel wages, and energy consumed. 2·4H2O, FeCl3·6H2O, Graphite, the most significant cost is Labor, reaching almost 60%, while for the case of Chitosan/-/Succinic anhydride the most important cost driver is Energy, reaching about 46%. The labor cost is the highest percentage overall in both recipes, but it is evident that depending on the material produced, the balance of costs might change, favoring different factors. For both cases of this study, the recipe cost was actually lower than the market price of high-purity non-animal-derived Chitosan, which is about 254 € per gram.Raw materials comprise about 16% and 25% of the total recipe cost, respectively. It is of note that for each recipe the major cost driver is different. In the case of Chitosan/GLA/FeClThe ever-increasing demand for green materials has led to the growth of the polymer industry. Polymers have a wide variety of applications, but their high cost has been a hindrance, hence a lot of research has been devoted to cost reduction and selection of "the greenest". Chitosan is one of the polymers found in nature in abundance. Its cost is relatively low but depends on the specific physicochemical properties required for the target application. In this case, the raw material cost does not really affect the final total recipe cost.In order to limit the current and future recipe costs without sacrificing the quality, new strategies must be forged. Our results suggest that the main cost factors are labor and energy. Identifying fixed and variable costs will assist in optimizing them. Labor cost is a variable cost. In order to minimize it as much as possible, researchers could be trained to perform both the synthesis and characterization efficiently. Furthermore, depending on materials used, an additional step would be to select equipment that would minimize energy consumption by performing multiple processes concurrently.Chitosan has a great potential as a sorbent with the ability to remove a variety of contaminants, however its limitations require adjustments to be made to enhance its abilities. Raw chitosan has a crystalline structure, which lowers its adsorption ability due to the adsorption taking place on the crystal part. Cross-linking groups tend to react with the amine parts of chitosan, which are known as common bonding sites for metal ions. It is thus important to proceed in the grafting of functional groups on chitosan, in an effort to enhance selectivity and efficiency. Grafting seems like a suitable approach for refining the intrinsic attributes of natural polymers or for enriching them with new ones. Cross-linking and grafting are great alternative options for establishing an adsorption system. The effect of cross-linked content on the process or the actual properties of chitosan should be further explored in future research on discovering more efficient adsorbents.


The results showed that conscientiousness was significantly and positively correlated with the gray matter volume (GMV) in the right inferior frontal gyrus (IFG), which is the key region for inhibitory control. Further mediation analysis revealed that the IFG volume partially mediated the relation between conscientiousness and expressive suppression (ES), rather than cognitive reappraisal (CR), which showed that the IFG is associated with direct inhibitory control and plays a specific role in the relationship between conscientiousness and the two strategies of emotion regulation. Taken together, these findings contributed to sharpening the understanding of the correlation between conscientiousness and emotion regulation from the perspective of the brain structural basis.Conscientiousness is frequently characterized by tendencies to be self-disciplined, to demonstrate organization and dependability, to act dutifully, to aim for achievement and to have good impulse control; this trait plays an important role in some special contexts, such as legal consciousness. Although a great number of studies have confirmed the impact of conscientiousness on emotion experience, little is known about the relationship between conscientiousness and emotion regulation, or of the brain structural basis that is involved. The current study investigated the neuroanatomical basis of the relationship between conscientiousness and emotion regulation from the perspective of individual differences. The voxel-based morphometry (VBM) method at the whole-brain level was used to identify the brain structural basis related to conscientiousness in a large, young sample ( In the Big Five taxonomy of personality, conscientiousness has often been defined as a personality trait that reflects the tendencies of self-control, hard work, achievement-striving and acting dutifully  studies revealed a positive correlation between conscientiousness and gray matter volume (GMV) in the lateral prefrontal cortex  method to identify the association between conscientiousness and regional GMV at the whole-brain level. Second, we further examined which regions would be able to mediate the relationship between conscientiousness and emotion regulation (CR and ES). Given that some studies reported that conscientiousness reflects the abilities of inhibitory control and self-regulation  individuals participated in this study as part of our ongoing project, which was designed to examine the associations between brain imaging, creativity, and mental health. All participants were right-handed and without a history of mental illnesses or neurological disorders. All participants provided written informed consent prior to the study. The Brain Imaging Center Institutional Review Board of Southwest China University approved this study and the experimental procedure.The NEO-PI-R was used to measure the conscientiousness of each individual .All the MRI data were acquired on a 3.0-T Siemens Trio MRI scanner . During data acquisition, the subjects were instructed to keep their heads still. Earplugs and foam padding were used to reduce the scanner noise and head motion, respectively. The high-resolution T1-weighted anatomical images were obtained with a magnetization-prepared rapid gradient echo (MPRAGE) sequence  = 256 × 256 mmThe MRI scans were processed using SPM8  were initially identified. In the analyses of our studies, the p-maps were thresholded to yield an expected p-value of <0.05, with the FWE correction for multiple comparisons.Statistical analyses of the GMV data were performed using SPM8. We applied multiple linear regression to identify the brain region whose GMV was associated with individual differences in conscientiousness. We created a custom binary mask by including voxels with a gray matter value greater than 0.2 to avoid the partial volume effect. All subsequent statistical analyses were conducted in this mask. Gender, age and total GMV were included as nuisance covariates to remove any potential confounds. Within the custom mask, clusters with continuous suprathreshold voxels  is a variable that is part of the causal pathway by which an independent variable (X) affects a dependent variable (Y). In this study, X was the conscientiousness scores, Y was the suppression scores and M was the GMV of the regions associated with conscientiousness that were extracted from our own corrected results. This macro uses bootstrapped sampling to estimate the indirect mediation effect. In this analysis, 2000 bootstrapped samples were drawn and the bias-corrected, 95% bootstrap confidence intervals (CIs) were reported. CIs that did not include zero indicated a significant indirect effect of the independent variable on the dependent variable through the mediators , which was consistent with the findings of previous studies.The demographic data and behavioral results are shown in Table t = 4.85; cluster size = 615; p < 0.005), corrected by FWE at the cluster-level of p < 0.05 . Suppression was negatively associated with the GMV of the IFG . Conscientiousness was positively associated with suppression . To test the significance of the indirect effects between conscientiousness and suppression, bootstrap resampling was used. The results showed a significant indirect effect  between conscientiousness and suppression, through the volume of the IFG (see Figure Indirect mediation effects can be interpreted as the strength of the relationship between conscientiousness and suppression ability when accounting for mediating pathways. Conscientiousness was negatively associated with the GMV of the IFG (The present study investigated the associations among conscientiousness, emotion regulation and brain structure in a large, young sample. Conscientiousness was positively correlated with two types of emotion regulation strategies. The VBM results revealed that the GMV in the IFG was significantly and positively associated with conscientiousness, and the IFG acted as a mediator in the relationship between conscientiousness and ES.Our results confirmed the close association between conscientiousness and emotion regulation, which was in line with previous research (Ivcevic and Brackett, The whole-brain VBM results revealed that conscientiousness was significantly and positively associated with GMV in a cluster that was mainly located in the right IFG, which was similar to the findings of a longitudinal study of brain structure development associated with personality traits (Ferschmann et al., More interestingly, the mediation analysis showed that the GMV in the right IFG partially mediated the correlation between conscientiousness and ES, rather than CR. CR is considered a cognitive-linguistic strategy that changes emotional responses by subjectively assigning a new meaning to the situation, and ES is a response-focused strategy that directly suppresses behaviors associated with emotional responses (Goldin et al., Our results are preliminary, and some limitations should be acknowledged. Despite the relatively large sample size, all participants of this study were young undergraduates, which may restrain the generalizability of these findings; thus, different sample groups need to be included to further validate these findings. In addition, the current results were correlational, and the mediation results also remained speculative, which suggests that the implementation of longitudinal studies may be required to further confirm the causal relationship between conscientiousness and emotion regulation and to consider other potential influencing factors. Of equal importance, task-based functional MRI research may be urgently needed to reveal the impact of individual differences in conscientiousness on the emotion regulation process. The study of conscientiousness and emotion regulation in some special fields can also be considered in the future, such as workplace impacts, legal consciousness and child development.In summary, the present study demonstrated that conscientiousness is correlated with emotion regulation, and the IFG volume mediates the relation between conscientiousness and ES rather than CR. These findings contributed by deepening the understanding of the relationship between conscientiousness and emotion regulation from the perspective of brain structural basis and highlighted the critical role of inhibitory control in these relationships.CC and QJ designed the study. YM, JL and LH collected the data. CC and YM analyzed and interpreted the data; wrote the manuscript.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.


Exciton-polaritons in semiconductor microcavities constitute the archetypal realization of a quantum fluid of light. Under coherent optical drive, remarkable effects such as superfluidity, dark solitons or the nucleation of vortices have been observed, and can be all understood as specific manifestations of the condensate collective excitations. In this work, we perform a Brillouin scattering experiment to measure their dispersion relation  Owing to its driven-dissipative nature, and its solid-state environment, a resonantly driven polariton condensate can be accompanied by an incoherent reservoir of excitons. Stepanov et al. demonstrate that this situation strongly modifies the spectrum of collective excitations, which determines many quantum hydrodynamic features in a polariton fluid. The system is then governed by the laws of quantum hydrodynamics, in which the condensate phase 4, in which this regime has been pioneered, and ultracold atom gases5 that are nowadays among the most accurate systems to investigate every subtleties of quantum fluids.Upon quieting down the thermal fluctuations in a liquid or a gaseous many-body system by deeply cooling it, and if it does not turn solid, a radical transformation occurs as the system behavior starts to be dominated by quantum mechanics. In the case of integer spin particles, a so-called Bose–Einstein condensate appears below a critical temperature, in which a significant fraction of the fluid occupies a single-quantum state6. The corresponding experimental measurements of the elementary excitations came decades later in an ultracold atom gas9 and confirmed their key role in the observed phenomena.The root cause of these fascinating phenomena can be traced back to the nature and dispersion relation (DR) of the elementary excitations in the quantum fluid. As a general feature, these excitations consist of coupled phase and density fluctuations, and due to two-body interaction they are collective in nature. In the mean-field regime, where the temperature is low, interactions are weak, and the condensate fraction is dominant, Bogoliubov derived in 1947 an analytical description of this regime, and could thus reveal the link between the DR of the excitations and the superfluid state11. A paradigmatic member of this class is the fluid of exciton–polaritons (polaritons), that can be pumped within the spacer of an optical microcavity in the strong coupling regime12. Polaritons can be understood as photons dressed by semiconductor electrons–hole pairs (excitons) that display significant binary interactions mediated by Coulomb interaction. Their nonequilibrium character comes from the fact that they need to be continuously replenished by an external pump to compensate for ultrafast radiative losses. They thus require a different theoretical framework than their equilibrium counterpart, which is based on the generalized Gross–Pitaevskii equation (GGPE)13.Recently, quantum fluids of light have emerged as a new class of quantum fluids, characterized by their nonequilibrium character19; experimentally, a superfluid-like frictionless flow has been demonstrated in 2009 in a steady-state polariton fluid20. From there on, a number of quantum hydrodynamics phenomena have been studied in this system, including the nucleation of topological excitations, such as solitons22 and quantized vortices25, phenomena associated with their spin degree of freedom27, vortex dynamics29, and turbulence effects30.In this nonequilibrium setting, the notion of superfluidity raises intriguing questions about its definition and characteristic observables31 for instance, a transient polariton population was created with a resonant pulsed laser, and the time-integrated DR of the excitations was measured in a four-wave mixing arrangement, hinting at sound-like collective excitations. A measurement under resonant continuous wave (CW) drive has been carried out in ref. 32, where two bands of positive and negative frequencies excitations have been measured, and found in agreement with the normal and ghost branches of Bogoliubov’s theory. However, the optical pump was kept too low to observe collective features beyond the perturbative regime of the single-particle picture. The DR of collective excitations has also been measured in the regime of pulsed nonresonant optical drive in several works35, but in this incoherent excitation configuration, the nature and DR of the excitations are different from those realized under resonant drive condition like ours36. Moreover, the pulsed excitation introduces time-dependent densities, which results in inhomogeneous broadening of the excitation spectrum, and makes comparison with theory harder. Finally, a measurement of the Bogoliubov DR has been reported recently in an equilibrium-like fluid of light in the conceptually different case of a propagating geometry in an atomic vapor cell37.As mentioned above, the DR of the collective excitations play a crucial role in these phenomena. To the best of our knowledge, while it has been investigated in some particular cases, its measurement under resonant optical drive is still missing. In ref. 43, we developed a theoretical framework in which polaritons can be converted into reservoir excitons  is excited resonantly with a tunable single longitudinal mode CW laser (cf. Methods). A sizable population of excitations is spontaneously created on top of the resonantly driven polariton condensate by the interaction of polaritons with the thermal bath of acoustic phonons naturally present within the solid-state microcavity (see Supplementary Note 3). The polaritons involved in these excitations can then relax radiatively, so that their energy and momentum with respect to the condensate constitute a direct measurement of the DR of the excitations. This emission, that we will refer to as excitations photoluminescence (EPL), is collected by the detection scheme illustrated in Fig. 44, to detect the EPL in the cross-polarized direction with respect to the laser. For the second stage, we designed an narrow band notch filter  readsLike in the previous case, the interaction energy We then performed the same analysis for the other working point WPB, in which we used a nonzero laser incidence angle Like in WPA, the comparison with the two theoretical limiting cases are shown in Fig. 49. A detailed discussion can be found in Supplementary Note 1.These experimental observations pinpoint the necessity of building a theoretical description of the elementary excitations that includes a contribution from the reservoir. We first check the existence of the reservoir alongside polaritons by exploiting their very different respective lifetimes: we performed a time-resolved polariton photoluminescence decay measurement under pulsed resonant excitation and found that the polariton population exhibits a fast decay component fixed by the polariton lifetime, and a slow decay time component of 36. In addition, due to the cross-polarized measurement technique, this theory needs to account for the polariton polarization degree of freedom. This vectorial theory is presented in details in Supplementary Note 8. For the sake of simplicity, we present thereafter a scalar version in which the coupled equations read50. Experimentally, we find that the relative intensity of the excitations is very small as compared with the coherent field, so that a linearized treatment around the steady state is an accurate description.We thus developed a theoretical model with the GGPE for the condensate wavefunction 13 do apply. In particular, the suppression of polariton scattering due to interaction with an obstacle is expected to happen below a critical velocity 21. On the other hand, in the regime where excitations have a frequency This model describes a condensate on top of which excitations of frequencies In order to simulate the experimental measurements, we used the vectorial version of the model, and determined the energy-momentum power spectrum of the condensate wavefunction by convolving the Bogoliubov matrix response function with a stochastic Gaussian noise simulating the coupling with the phonon bath. We then extracted the DR by fitting these data using the same method as for the experimental data. We obtained a quantitative agreement with the experimental DR both in WPA 55, such that the emission from the ghost branch could be detected, albeit in a regime dominated by the free-particle properties.Remarkably, our model also recovers the fact that in our measurements, the ghost branch emission is strongly suppressed (cf e.g., Fig. 21, involve the total blueshift due to polaritons and reservoir. On the other hand, finite-frequency collective excitations as investigated here, are governed only by interactions between condensate polaritons.In summary, we obtained a direct measurement of the dispersion relation of the collective excitations on top of a coherently driven polariton condensate. This measurement can be directly used as the key experimental ingredient required to test the system against most superfluidity criteria. Our analysis also provides a deep insight into the unique two-components nature of this quantum fluid and its elementary excitations: partly polariton condensate and partly incoherent reservoir. In particular, we have checked that the speed of sound, which is a key characteristic of collective excitations in quantum fluids, is strongly reduced by the presence of the reservoir. More generally, we have established theoretically and experimentally that the reservoir involvement results in two different regimes of collective excitations. On one hand, the spatial density patterns resulting from static collective excitations like in historical frictionless flow experiments58 is a time-dependent phenomenon, for which one can naturally expect strong modifications due to the coupling of the coherent polariton fluid to the much slower degrees of freedom of the reservoir that strongly affects its Galilean relativity properties. From a quantum-optical perspective, the additional blueshift of the polariton state due to the incoherent reservoir may be playing a role in the experimental recent two-body correlation experiments59. Along the same lines, the presence of an incoherent excitonic reservoir reservoir is a convincing argument60 to explain the overestimated polariton–polariton interaction constant in ref. 61. In this context, our spectroscopic measurement of the collective excitations provides an accurate way to extract the polariton–polariton interactions contribution to the total interaction energy, and isolate it from the reservoir contribution.We are currently investigating the extent and magnitude of these consequences from both the theoretical and the experimental point of view. For instance, the hydrodynamic nucleation of vortices studied in refs. 62. It features a quality factor The GaAs/AlAs microcavity used in this experiment is identical to that used in ref. The polariton fluid is driven resonantly with a single longitudinal mode CW Ti-Sapphire laser of 5 MHz linewidth, and linearly polarized with a high purity. The laser beam is shaped with pinholes into a spatially Fourier-limited Gaussian mode of Owing to its polarization degree of freedom, the condensate field is a vectorial field, characterized by its two components The experimental dispersion relations are extracted from the measurements of Supplementary InformationPeer Review File


With the development in the exploitation of maritime resources, the structural health monitoring (SHM) of offshore structures becomes necessary. This study focuses on addressing the practical issues of application of fiber Bragg grating (FBG) sensors for the SHM of offshore structures, in particular an FPSO  vessel. Due to the harsh marine environment and tough working conditions, the FBG sensors must have sufficient protection and good repeatability for long-term monitoring. Thorough research has been conducted to identify the most suitable, commercially available protection packaging for FBG sensors for offshore applications. Further, the performance of the selected FBG sensor packaging is tested under conditions of strong sunlight, heavy rain, and salty water in order to emulate the marine environment. Moreover, the installation method of the packaged FBG sensors is equally important, as it ensures the repeatability and durability of the sensors for their long-term performance. It is shown that the packaged FBG sensors can be installed using resin-based epoxy to maintain the repeatability of the sensor over the long-term. Further, the packaged FBG sensors are installed and tested on a simple FPSO model. The experimental results under full load and ballast draft conditions show that the proposed FBG sensors are competent for the SHM of offshore structures. Structural health monitoring (SHM) refers to detecting and analyzing the changes in structures, and indicating damage and property degradation . The SHMIn general, a typical SHM system consists of three parts: sensors, a data transmission system, and a health evaluation system. The structural responses are first measured by the sensors; then, they are transmitted through the data transmission system, and finally analyzed by the health evaluation system . The accMieloszyk and Ostachowicz presented an application of FBG sensors for the SHM of an offshore wind turbine support structure model; the experimental investigation verified the usefulness of FBG sensors as a part of the system permanently installed on the underwater elements of an offshore structure . Based oSince a bare FBG sensor is quite fragile and easily damaged, it requires sufficient protection to be used for field applications . In factGenerally, practical issues related to the offshore application of FBG sensors include the selection of sensor protection, installation method, measurement process, and responses of the sensor to harsh environments. Most of the current research studies have just focused on one aspect of offshore applications. In this study, a comprehensive investigation of these topics is conducted. Characteristics such as the robustness, sensitivity, stability, and repeatability of three commercially available packaged FBG sensors are studied in this work. Based on all of the characterization results, the composite embedded FBG sensors are recommended for offshore applications. The installation of packaged FBG sensors is another important issue, as it ensures the repeatability and durability of the sensors. Also, the installation method must be non-invasive for offshore applications. Usually, the packaged FBG sensors are installed by gluing, bolting, or welding. Although the methods of bolting and welding can fix the sensors firmly, the structural integrity of the monitored structures may be hampered. The composite embedded FBG sensors can be easily installed by gluing them on the structures using resin-based epoxy, which is a non-invasive method. Although the fatigue performance of the gluing method cannot be as good as that of the bolting or welding method, the results from the dynamic test show that resin-based epoxy works well with the composite embedded FBG sensors as far as the repeatability of the sensor is concerned. Further, the experimental results show that the repeatability of the composite embedded FBG sensors while being subjected to harsh environmental conditions such as strong sunlight, heavy rain, and salty water is maintained, which confirms the durability of the sensors. Further, an FBG monitoring system for offshore structures is introduced based on the selected FBG sensor. Finally, the FBG monitoring system is tested on an FPSO model, and the results show that the proposed system is competent for the SHM of offshore structures in terms of its practicability and accuracy.Bλ). The Bragg wavelength changes as the grating period (the distance between the consecutive grooves) changes [effn is the effective refractive index of the core of the fiber, and Λ is the grating period of the FBG. When the FBG is subjected to external perturbations, the grating period increases or decreases, and hence, the Bragg wavelength increases or decreases, respectively. The wavelengths’ drift  is inscribed into the core of the fiber, as shown in  changes . The Braectively .In this section, experiments are conducted to find out the most suitable protection/packaging for FBG sensors that can be part of the SHM system for the offshore structures. In this research, three representative and competitive FBG protections  and strain gauge are used for comparison, and the simulation data obtained by finite element analysis (FEA) software is illustrated as the theoretical values.In static tests, all five sensors are used to measure the strain value of an aluminum plate of size 1030 mm × 530 mm × 3 mm under simply supported loading conditions, as shown in The strain values measured by the five sensors under various loads are plotted in Clearly, similar to the strain gauge, the measurement data obtained by bare FBG sensor are very close to the simulated data, establishing the credibility of the bare FBG sensor. However, the bare FBG sensor cannot be used directly. Different protection materials have different influences on the sensitivity of the FBG sensor. As shown in The repeatability of sensors is equally important. The repeatability of the bare FBG sensor is certainly very high. For the packaged sensor, the protection layers may play a role affecting the repeatability. To ascertain such an effect, the loading tests are repeated six times with all the same sensors and the same plate, and the variance and standard deviation (Std) are calculated for each load. In In summary, from results of the static tests, the FBG sensor embedded into composite is the best one among the three FBG sensors with protection material.Dynamic loads are very common in offshore applications, and dynamic tests for the protected FBG sensors must be conducted. Considering the static test results of the three FBG sensors, the most suitable one is utilized to carry out the dynamic tests. Thus, the FBG sensor embedded into composite that has the best performance in static tests is bonded to an aluminum plate with a size of 450 mm × 94 mm × 2 mm by using resin-based epoxy, as shown in 6 cycles (in 12 days), indicating the reliability and repeatability of the composite-embedded FBG sensors. The simulation results  obtained from FEA based on the parameters shown in In order to test the stability and repeatability of the sensor, the shaker runs continuously for about 12 days (12 × 24 = 288 h). The strain data samples (for two cycle periods) are collected at 0 h (beginning), 48 h, 96 h, 144 h, 240 h, and 288 h. The wavelength data is converted into the strain data and plotted in Therefore, we can conclude that the FBG sensor embedded into composite is suitable for offshore applications in consideration of its credibility, sensitivity, stability, and repeatability.Due to the harsh environment, the offshore applications raise many extra requirements for the FBG sensors. The FBG sensors and their installation methods must be durable enough to work under some extreme conditions such as strong sunlight, heavy rain, high humidity, etc. Especially, they must work well in saline water. Since the seawater is oxygen-containing and conductive, the coating layer of the FBG sensor and the adhesive may fail after a long period of work . In ordeMoreover, to verify the durability of the FBG sensor in sea water, the specimen was put into salty water that had a similar salinity (35‰) to sea water overnight (from 19:00 to 08:00) for 15 days. The loading test was conducted on the specimen every day at 8:45 after taking the specimen out of the saline water, after which the specimen was put in the outside weather conditions. This cycle of events continued for 15 days. In the loading test, 5-N, 10-N, 15-N, and 20-N weights were put at the center of the aluminum plate, as shown in Before conducting the loading tests, the specimen was placed in the laboratory for about half an hour for temperature stabilization. However, the temperature in the laboratory while conducting the loading test might be different on different days. This issue can be overcome by recording a reference value of the FBG sensor (Bragg wavelength) every day before conducting the loading test and temperature variations during the test can be conveniently considered negligible. As shown in °C increment. The whole system for the experiments is shown in In an offshore environment, temperature variations might take place quite often. Therefore, the composite embedded FGB sensor must be characterized for temperature variations. In the experiment, three FBG sensors embedded into the composite are used. Two FBG sensors are attached to two separate plates of the same material that have different thicknesses. In detail, the first one (Sensor 1) is bonded to an aluminum plate with a size of 450 mm × 94 mm × 2 mm  which is isolated from mechanical force, was kept in the same environment. This method can be straightforwardly illustrated in After selecting the suitable FBG sensor for offshore applications, an FBG monitoring system based on the composite embedded sensor is introduced. The FBG monitoring system  and vertical wave-induced bending moment (VWBM). In the laboratory tests, we only simulated the SWBM, which depends basically on the longitudinal distribution of the self-weight, the cargo, or the deadweight. Two working conditions, the full load condition and the ballast draft condition, were considered based on the FPSO model. The proposed FBG monitoring system was used to detect the strain values of the FPSO model for the two working conditions.In order to locate the measurement points (hot spots) when monitoring the FPSO model, finite element analysis (FEA) was conducted. According to the simulation results Experiment 1: The FPSO model is put in the water tank for 15 minutes to let it reach the steady state. The water is injected into the first middle cabin in two-liter steps until it is full. The wavelengths of the four FBG sensors are recorded at every step. Further, the water is injected into the second middle cabin in two-liter steps until it is full. Again, the wavelengths of the four FBG sensors are recorded at every step.(2)Experiment 2: The FPSO model is put in the water tank for 15 minutes to let it reach the steady state. The water is injected into both the stem part and stern part in two-liter steps until the total amount of the injected water reaches 30 liters, and the wavelengths of the four FBG sensors are recorded at every step.According to the measurement data obtained by the four FBG sensors, the strain values that were induced due to water injection are plotted in As shown in In this study, we address some practical issues regarding the application of customized FBG sensors for the SHM of offshore structures. A comprehensive study of various available FBG sensors is conducted, and the experimental results suggest that the FBG sensor embedded into composite is the best suited for offshore applications in consideration of its robustness, sensitivity, stability, and repeatability. To test the performance of the composite embedded FBG sensor in the harsh offshore environment, a series of dynamic tests and durability tests are conducted, including experiments on FBG sensors subjected to environments similar to offshore conditions such as strong sunlight, heavy rain, and salty water. An FBG monitoring system based on the composite embedded FBG sensor is then introduced and employed to measure the strain values of an FPSO model under full load and ballast draft conditions. The experimental results show that the composite embedded FBG sensors competently monitor the offshore structures with high practicality and accuracy.


Job tenure has been significantly shortened with the prevalence of the gig economy around the world. Workers are faced with a new age of frequent employment change. This emerging situation is out of expectation of social health insurance policymakers. As the multi-level social health insurance system in China is closely associated with employment status; urban workers cannot enjoy the urban employee basic medical insurance (UEBMI) during the unemployment period. At this time, unemployed rural-to-urban migrant workers can only rely on the new cooperative medical scheme (NCMS) and unemployed urban residents can only rely on the urban resident basic medical insurance (URBMI). This study provides a preliminary analysis on healthcare utilization change triggered by the unemployment-induced social health insurance transition that has never been investigated. Using the data of a nationwide survey, empirical results show that the unemployment-induced social health insurance transition can significantly deteriorate the healthcare utilization of insurance beneficiaries experiencing the transitions from the UEBMI to the NCMS (or from the UEBMI to the URBMI). Specifically, the outpatient service quality and the conventional physical examination become worse, and the out-of-pocket expenditure increases. Therefore, the multi-level social health insurance system currently in effect can expose workers to a high risk of insufficient health security in the age of frequent employment change. A growing number of enterprises and institutions in China are adapting to the trend of gig economy and tending to hire an increasing number of temporary staff instead of permanent staff. Reports published by LinkedIn, a famous business-oriented social networking service, show that the average job tenure has reduced to 22 months in China , and theIn contrast with the United States, China’s health insurance system is based on social health insurance provided by the state . The comUrban workers cannot enjoy the urban employee basic medical insurance (UEBMI) as before once they lose their jobs ,6. DurinFurther, for workers experiencing the unemployment-induced insurance transition from the UEBMI to the NCMS during the employment change period, the damage to their healthcare utilization appears more serious. Due to the great rural-urban disparity in healthcare access ,8,9, theThis study provides a preliminary investigation on the healthcare utilization change triggered by the unemployment-induced insurance transition that has never been explored. This issue arises from the prevailing gig economy around the world. Now, it is becoming increasingly difficult to acquire long job tenure. A growing number of people have to bear the frequent employment change and the resulting frequent gap between jobs. The temporary unemployment status is thus becoming an increasingly common experience in one’s life. However, the current health insurance systems are not ready for the change of employment environment. The link-up of health insurance systems is not well established enough to respond to the unemployment-induced health insurance transition. As such, the frequent unemployment status can inevitably cause the damage to the healthcare utilization. To better understand this issue, it is essential to empirically examine the effect of the unemployment-induced health insurance transition on healthcare utilization in the context of frequent employment change.Moreover, this issue is of great significance in China. Compared with developed countries, the commercial health insurance market in China is not yet mature. It has difficulty, at the present time, becoming a reliable and widely-accepted solution for unemployed people for maintaining a level of healthcare utilization. More importantly, due to being closely associated with employment status, Chinese multi-level social health insurance system can trigger passive health insurance transition in the context of frequent employment change, making people in temporary unemployment status not entitled to benefits of health insurance with wider coverage, but have to turn to others with narrower coverage. Thus, it is particularly necessary to investigate how this issue presents in China.This paper is structured as follows. In the following sections, this paper first describes the foundation laid by previous research, and the motivation for initiating this study. Then, this paper discusses the status quo of China’s social health insurance system, and based on this, analyzes the potential effect of unemployment-induced insurance transition on health utilization in the context of frequent employment change. In the following methods section, this paper uses the data of a nationwide survey  to empirically examine the effect of health insurance transition from the UEBMI to URBMI or NCMS on health utilization. Meanwhile, this paper makes a detailed description of measures of variables and offers the technical details to clarify the reasonability of the heterogeneously robust linear regression approach applied in this study. Finally, in the discussion and conclusion sections, this study concludes that the current social health insurance system in China has not coped well with the emerging problem of frequent insurance transition triggered by the frequent employment change. The rural-to-urban migrant workers who experience the transition from UEBMI to NCMS are found suffering a far more severe deterioration of healthcare utilization than regular urban residents who experience the transition from UEBMI to URBMI. The current social health insurance schemes thus need to be integrated to meet the new requirements. Future research directions and implications of the present research have also been discussed.Previous research has laid a solid foundation for this study. Some of them focus on one kind of social health insurance to explore its effect on health outcomes e.g., ,21) or t or t21])To briefly summarize the differences between UEBMI, URBMI and NCMS it can help to better understand the problem of unemployment-induced social health insurance transition.(1) First, the target population is different.The UEBMI mainly benefits the urban employed , while t(2) Second, the payment requirements and funding source are different.The UEBMI is mandatory for the urban employed and jointly paid by employers and employees , while t(3) Third, the coverage level of treatment is different.Since the level of funding for URBMI and NCMS are relatively lower, the general level of their medical treatment is shown lower than that of UEBMI’s ,38. The (4) Finally, the reimbursement level is different.The reimbursement rate and reimbursement cap enjoyed by URBMI and NCMS beneficiaries are lower than that for UEBMI ,43,44,45As mentioned above, the UEBMI is superior in many aspects to the URBMI and the NCMS. For the UEBMI, its stable and reliable funding source can ensure its higher funding level, which in turn can support its high level of treatment coverage for the beneficiaries ,50. In tThe data of China health and retirement longitudinal study (CHARLS-2015) is used in this study. CHARLS is a widely-used nationwide survey using stratified random sampling, and it collects a high-quality and nationally representative sample of Chinese residents over the age of 45. This survey is jointly initiated by the Center for Social Science Survey in China and the Youth League Committee of Peking University, and is implemented by the National Development Institute of Peking University. CHARLS-2015 is made public since 2017. This survey covers 150 counties, including 450 communities and villages across 28 provinces and municipalities in China, among which about 52.6% are rural areas and 47.4% are urban areas. The sample has covered about 12,400 households in total. This population surveyed is representative of people who are more vulnerable to diseases and more sensitive to the social health insurance transition.2013→No2013–2015). According to the insurance status of NCMS in 2013 and during 2013–2015 for unemployed rural-to-urban migrant workers, four conditions are tested as independent variables . The similar four combinations of insurance status of URBMI in 2013 and during 2013–2015 for unemployed urban residents are also tested as independent variables . More details about dependent and independent variables have been shown in In this study, three critical dependent variables reflecting healthcare utilization  are examined. Respondents in this study are those who are the insured of UEBMI in 2013, but turn out to be uninsured during 2013–2015 because of unemployment ”. The unmatched observations are dropped. The statistical software Stata 13.1 is used in the data analysis. The heterogeneously robust linear regression is applied in this study. Standard errors have been clustered on community level and household level, respectively. The advantage of this method lies in that the estimates can still remain consistent and efficient when individuals could not comply with the independent and identically distributed (I.I.D.) condition. Considering respondents from the same community (or household) are more likely to be homogeneous, the heterogeneously robust linear regression would compute the robust standard errors clustered on community (or household) level instead of the common one to judge the statistical significance. In this way, the estimates are reliable.p < 0.05 for people in the condition of UEBMI: Yes→No and NCMS: Yes→Yes and UEBMI: Yes→No and NCMS: No→Yes respectively).Results of Similar empirical results have been found for the transition between UEBMI and URBMI see , althougIt is generally known that job tenure has been significantly shortened with the prevalence of the gig economy in China, and a long-termed job has become less available. This new situation leaves the social health insurance system in force lagging behind the status quo of China’s economy. The mismatch between the continuing healthcare demand and the health insurance transition during the short unemployed gap period starts to emerge. The current social health insurance system does not cope well with this problem.In the past, the multi-level social health insurance system is considered to have well covered different types of population. The employed people are covered by UEBMI, and the unemployed people can also enjoy health insurance of URBMI and NCMS. The employment change is not so frequent as before, and the social health insurance system in force does not take the employment change as a matter that frequently happens. Neither the URBMI nor the NCMS is particularly designed for people that experience short unemployed gap periods. Thus, the frequent social health insurance transition resulting from the employment change brings not only the great managing difficulty for beneficiaries, but also huge administrative costs for administrative agencies.Moreover, the conflict between the continuing demand for healthcare utilization and the passive social health insurance transition can lead to severe consequences. For example, continuing healthcare is particularly in need for chronic disease patients. However, during the short unemployed gap period, the healthcare utilization can be suppressed, and some necessary treatments have to be broken off for saving out-of-pocket expenditure. As such, the patients have to adjust their treatment demand to make it covered by the transitional social health insurance rather than in accordance with their illness status. Even though people can restore their beneficiary status of UEBMI after getting the next job, the interruption or suppression of healthcare utilization within the short unemployed gap period can still have serious impact on chronic disease patients.Further, the rural-to-urban migrant workers are more vulnerable to the social health insurance transition. Although the healthcare utilization is also damaged for regular urban residents that experience the transition from UEBMI to URBMI, the deterioration of healthcare utilization is much more severe for rural-to-urban migrant workers who experience the transition from UEBMI to NCMS. The difference in benefit package between the two schemes (URBMI and NCMS) can partially lead to this situation. And also, the over-concentration of healthcare resources and the resulting great rural-urban disparity in healthcare access can be the culprit of this asymmetry.This study is the first attempt to assess the impact of health insurance transition induced by employment change on healthcare utilization. It adds important new knowledge to the existing empirical evaluation of health insurance system. Results further provide empirical support to the idea that the emerging gig economy and the resulting frequent employment change can produce a new challenge to the social health insurance system in China. For policy makers of social health insurance, it is necessary to establish a proper transferring mechanism to integrate UEBMI, URBMI and NCMS. This mechanism needs to link with the original health insurance system, whereby the barrier to receiving NCMS reimbursement for most of rural-to-urban migrant workers could be well dealt with. To successfully build this mechanism, the cohesion between different social health insurance schemes needs to be strengthened through solving some problems like payment age conversion, medical funding compensation for local areas. Moreover, it is helpful to construct an integrated health insurance information platform that implements the centralized management of health information and compensation schemes of various diseases for all kinds of the insured. For those without sufficient conditions for integration of different social health insurance schemes, this practice can serve as the first move towards this integration. Further, the urban-rural dual structure of current social health insurance in China is designed for ease of administration. However, the separate healthcare administration for different social health insurance schemes has now hindered the resolution of emerging issues. Thus, it is essential to unify the administration to facilitate the integration of health insurance, and also to alleviate the financial pressure of operation. Finally, for now, the mitigation measure is to set the buffer period, for example, by 12 months since unemployment, during which the entitlement to UEBMI benefits can be retained. This effort may minimize the damage to health utilization during the period of health insurance transition.This study is not free of limitations. The nationwide survey used in this study simply documents the information of health insurance transition during the year of 2013–2015, which cannot be used to reveal the dynamics of its effect on health outcomes in a long term. With the subsequent data gradually made public, the effect of a health insurance transition on health outcomes can get the dynamic monitoring. Thus, as more relevant data become available, future research can use new data to provide a comprehensive exploration of this issue.