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The electron tunneling rates between a two-dimensional electron gas (2DEG) and self-assembled InAs quantum dots are studied by applying a magnetic field perpendicular to the tunneling direction. For both the ground and the first excited states, the tunneling rate can be modified by a magnetic field. The field dependence of both the s and p state tunneling rates can be explained with a model, based on momentum matching between the Fermi surface of the 2DEG and the wave function of the quantum dots in momentum space. The results, together with the comparison between charging and discharging rates, provide insight into the filling sequence of the p-state electrons. [ABSTRACT FROM AUTHOR]

Microscopy characterization techniques can provide intuitive images of 2D materials with certain spatial resolutions. At the same time, machine-learning algorithms, which have experienced tremendous advancement in image processing over passed decades, are able to extract comprehensive information directly from a large scale of the images. Combining microscopy characterization techniques with machine-learning algorithms can offer insight into the structures and properties of 2D materials with the advantages of high automation, high accuracy, and high throughput. Herein, we will give a review of this interdisciplinary area, from foundations and progress to challenges and potential opportunities. The developments in this field are first overviewed according to its characterization techniques. Then, this review focuses on the theoretical and practical foundations of machine-learning-assisted microscopies for 2D material property characterizations, followed by two case studies to illustrate the implementation details. Finally, challenges and opportunities are addressed for future research and industrialized applications. We hope this review article can provide a clear guideline for both the academic society and general readers and inspire researchers for further explorations of this promising area. [ABSTRACT FROM AUTHOR]

Echoviruses, for which there are currently no approved vaccines or drugs, are responsible for a range of human diseases, for example echovirus 11 (E11) is a major cause of serious neonatal morbidity and mortality. Decay-accelerating factor (DAF, also known as CD55) is an attachment receptor for E11. Here, we report the structure of the complex of E11 and the full-length ectodomain of DAF (short consensus repeats, SCRs, 1–4) at 3.1 Å determined by cryo-electron microscopy (cryo-EM). SCRs 3 and 4 of DAF interact with E11 at the southern rim of the canyon via the VP2 EF and VP3 BC loops. We also observe an unexpected interaction between the N-linked glycan (residue 95 of DAF) and the VP2 BC loop of E11. DAF is a receptor for at least 20 enteroviruses and we classify its binding patterns from reported DAF/virus complexes into two distinct positions and orientations, named as E6 and E11 poses. Whilst 60 DAF molecules can attach to the virion in the E6 pose, no more than 30 can attach to E11 due to steric restrictions. Analysis of the distinct modes of interaction and structure and sequence-based phylogenies suggests that the two modes evolved independently, with the E6 mode likely found earlier. [ABSTRACT FROM AUTHOR]

This paper proposes a novel error correction grey prediction model for degradation prediction of renewable energy storages. The proposed approach uses an error correction factor ψ to eliminate the inherent error of the original grey model (GM), and at the same time retain the original simplicity and fast prototyping. In addition, due to the uncertainty and complexity of failure mechanisms, a trigonometric residual modification is considered in order to well-describe the influence of operating conditions or cyclic fluctuation on the renewable energy storages. Two experimental case studies, including lithium-ion battery and fuel cell aging tests, are performed to validate the performance of the proposed method. In particular, the accuracy of the proposed method is investigated for different prediction horizon lengths, in order to further demonstrate its effectiveness and robustness. It is worth mentioning that the proposed method can ensure the accuracy of the remaining useful life estimation in the case of long-term forecasting, and thus, the maintenance management and corrective action of renewable energy storages can be scheduled earlier, leading to more effective cost minimization and risk mitigation. [ABSTRACT FROM AUTHOR]

Solid-state nanopores are considered an attractive basis for single-molecule DNA sequencing. At present, one obstacle to be overcome is the improvement of their temporal resolution, with the DNA molecules remaining in the sensing volume of the nanopore for a long period of time. Here, we used a composite system of a concentration gradient of LiCl in solution and a nanofiber mesh to slow the DNA perforation speed. Compared to different alkali metal solutions with the same concentration, LiCl can extend the dwell time to 20 ms, five times longer than NaCl and KCl. Moreover, as the concentration gradient increases, the dwell time can be tuned from dozens of milliseconds to more than 100 ms. When we introduce a nanofiber mesh layer on top of the pore in the asymmetric solution, the DNA molecules get retarded by 162–185 μ s/nt, which is three orders of magnitude slower than the bare nanopore. At the same time, because the molecule absorption region becomes larger at the pore vicinity, the higher molecule capture rate improves the detection efficiency. [ABSTRACT FROM AUTHOR]

Abstract This paper proposes a novel robust prognostic approach that contains three phases for degradation prediction of proton exchange membrane fuel cell (PEMFC) performance and its remaining useful lifetime (RUL) estimation. In the first detrending phase, a physical aging model (PAM) is used to remove the non-stationary trend in the original fuel cell degradation data. In the second filtering phase, the order of autoregressive and moving average (ARMA) model is determined by autocorrelation function (ACF), partial ACF and Akaike information criterion. The linear component in the stationary time series is then filtered by the identified ARMA model. In the third prediction phase, the remaining nonlinear pattern is used to train the time delay neural network (TDNN), in order to provide the final prediction result. Since the proposed prognostic approach uses appropriate methods to analyze and preprocess the original degradation data (i.e., the PAM maintains stationary trend, and then the identified ARMA filters linear component), the remaining nonlinear pattern of stationary time series can thus guarantee a good convergence performance of TDNN. In order to experimentally demonstrate the robustness and prediction accuracy of the proposed approach, degradation tests are performed using two types of PEMFC stack. Highlights • Applicability of different prognostic approaches is considered in terms of data types. • PAM removes the non-stationary trend to obtain static time series. • The identified ARMA model filters the linear component of the stationary time series. • The remaining nonlinear component of time series is used to train TDNN. • The proposed method guarantees robustness due to proper data preprocessing. [ABSTRACT FROM AUTHOR]

This paper presents a computationally efficient two-dimensional (2-D) steady-state model for fuel cell real-time control implementation. Both the fluid and electrochemical physical domains are considered in the proposed real-time model. The fuel cell under-rib convection is fully described by considering the geometry of serpentine channel. In addition, in order to solve the implicit activation voltage loss and further explore the computational performance, three numerical root-searching algorithms: bisection, secant, and Newton–Raphson methods are applied to the proposed implicit iterative solver and compared. The preferred secant method has been proven to effectively improve both the efficiency and robustness performance of the proposed real-time fuel cell model. Moreover, a computational fluid dynamic based COMSOL fuel cell model is used to validate the calculation accuracy. Furthermore, the practical feasibility of the presented real-time model has been verified using an RT-LAB simulator platform from Opal-RT. [ABSTRACT FROM AUTHOR]

This paper presents a novel two-dimensional real-time modeling approach for a proton exchange membrane fuel cell (PEMFC) based on a tridiagonal matrix algorithm (Thomas algorithm). The Thomas algorithm consists of a forward elimination and a backward substitution, its arithmetic complexity of computations being much lower than the Gaussian elimination. In order to use this advanced numerical solver, the differential equations of reactant gas convection and diffusion phenomena in serpentine channels are transformed into a tridiagonal equations system. In addition, a three-level bisection algorithm has been developed to solve spatial physical quantities distribution for electrochemical domain. The real-time computing methods developed in this paper are then implemented in C language for a fast execution time in a real-time processor. The proposed real-time model is experimentally validated using a 1.2 kW Ballard NEXA fuel cell system, and its practical feasibilities in advanced real-time control for PEMFC systems have been experimentally demonstrated in an RT-LAB real-time simulator. [ABSTRACT FROM PUBLISHER]

In this paper, an online energy management control strategy is proposed based on a novel fractional-order extremum seeking (ES) method. The proposed method is an online adaptive optimization algorithm, which can be effectively used in the applications of fuel cell hybrid electric vehicles. Compared with the traditional integer-order ES method, the presented method uses Oustaloup approximation based fractional-order calculus in order to achieve faster convergence speed and higher robustness. A detailed mathematical analysis of the proposed method is presented to give a stability proof and shows how the fractional-order calculus improves the integer-order ES method. In order to support the stability analysis results and demonstrate the effectiveness and robustness of the proposed method, a hardware-in-the-loop test bench is developed to provide two experimental case studies. Experimental results show that, by using the presented fractional-order ES approach, the operation points of a proton exchange membrane fuel cell stack system can be effectively controlled in its maximum efficiency area. In addition, the fuel cell system durability can be improved. [ABSTRACT FROM PUBLISHER]

Many fish swim using various kinematic patterns of head and tail combinations to change their body posture, which reduces drag while swimming. This study proposes a new method to improve the energy-harvesting performance of a flapping foil by actively controlling the combined movements of the leading- and trailing-edge flaps. These movements allow the foil to deform to a shape with preferable hydrodynamic performance during the flapping motion inspired by fish swimming modes. The study employs two-dimensional (2D) computational fluid dynamics (CFD) simulations to investigate the effect of the forced oscillation of a leading-edge flap on the energy-harvesting performance of a flapping foil. Consequently, the optimal combination of operating parameters of the leading-edge flap leading to greater efficiency and an apparent increase in power production from the flapping foil can be determined. Therefore, the energy-harvesting performance of a flapping foil with dynamic leading- and trailing-edge flaps was investigated numerically. The results suggest that synchronized movement between the leading- and trailing-edge flaps, which mimic the movement of live fish, can increase the camber of the foil and effectively manage the boundary layer by adjusting the frequency and amplitude of the oscillations, thereby generating elevated hydrodynamic forces acting on the foil. Therefore, the proposed flapping foil with swinging leading- and trailing-edge flaps can exhibit superior energy-harvesting performance than its conventional alternative across the full spectrum of operations. • A novel concept of a flapping foil flow energy harvester is proposed in this work. • Actively controlled leading- and trailing-edge flaps were adopted to mimic the head and tail oscillations of a fish. • CFD analysis were performed to investigate the performance of the proposed flapping foil configuration. • The proposed flapping foil energy harvester has better energy harvesting performance than its conventional counterpart. [ABSTRACT FROM AUTHOR]

Due to limitations in operational scope and efficiency, a single Autonomous Underwater Vehicle (AUV) falls short of meeting the demands of the contemporary marine working environment. Consequently, there is a growing interest in the coordination of multiple AUVs. To address the requirements of coordinated missions, this paper proposes a comprehensive solution for the coordinated development of multi-AUV formations, encompassing long-range ferrying, coordinated detection, and surrounding attack. In the initial phase, detection devices are deactivated, employing a path planning method based on the Rapidly Exploring Random Tree (RRT) algorithm to ensure collision-free AUV movement. During the coordinated detection phase, an artificial potential field method is applied to maintain AUV formation integrity and avoid obstacles, dynamically updating environmental probability based on formation movement. In the coordinated surroundings attack stage, predictive capabilities are enhanced using Long Short-Term Memory (LSTM) networks and reinforcement learning. Specifically, LSTM forecasts the target's position, while the Deep Deterministic Policy Gradient (DDPG) method controls AUV formation. The effectiveness of this coordinated solution is validated through an integrated simulation trajectory. [ABSTRACT FROM AUTHOR]

This paper presents a 2-D real-time modeling approach for a proton-exchange-membrane fuel cell (PEMFC). The proposed model covers multi-physical domains for both fluidic and electrochemical features, which considers in particular the flow field geometric form of fuel cell. The characteristics of reactant gas convection in the serpentine gas pipeline and diffusion phenomenon through the gas diffusion layer (GDL) are thoroughly considered in fluidic domain model. In addition, a three levels iterative solver is developed in order to accurately calculate the implicit spatial physical quantities distribution in electrochemical domain. Moreover, the proposed 2-D real-time modeling approach uses a numerical method to achieve a fast execution time, and can thus be further easily applied to any real-time control implementation or online diagnostic system. After experimental validation under different fuel cell operating conditions, an iterative Least Angle Regression (LAR) method is used to efficiently and accurately perform the global parameters sensitivity analysis based on Sobol definition. The online analysis results give an insight into the influences of modeling parameters on fuel cell performance. The effect of interactions between parameters’ sensitivities is especially investigated, which can provide useful information for degradation understanding, parameters tuning, re-calibration of the parameters and online prognostic. [ABSTRACT FROM AUTHOR]

As an online adaptive optimization algorithm, the extremum seeking method (ESM) can be effectively employed to find an optimal operating point of a static nonlinear system in real-time. This paper presents a comparative study of different ESM schemes for online energy management strategy of fuel cell hybrid electric vehicles (FCHEVs). By applying the extremum seeking controller, the fuel cell system operating points can be maintained in a high efficiency region and thus saving the hydrogen consumption. In addition, battery state of charge (SOC) is considered as the input of penalty function for extremum seeking controller, in order to prevent over-discharging/over-charging of the lithium-ion battery during the FCHEVs operation. Different schemes of ESM presented in this comparative study consist of first-order ESM, high-pass filter based ESM, and band-pass filter based ESC. The main evaluation criteria in this comparative study include the utilization of lithium-ion battery, the fluctuation of fuel cell system output power, the fuel cell system efficiency and the hydrogen consumption. A Hardware-In-the-Loop (HIL) platform is used to experimentally validate the presented comparative study. Experimental comparison results show that, the performance of all the presented ES controllers is close to that of offline benchmark dynamic programming. The band-pass filter based ES controller is preferred to improve both the performance and durability of energy storage system (ESS) in FCHEVs, since this controller is found to have a good ability to limit the fuel cell power dynamics. [ABSTRACT FROM AUTHOR]

In this paper, an innovative robust prediction algorithm for performance degradation of proton exchange membrane fuel cell (PEMFC) is proposed based on a combination of model-based and data-driven prognostic method. A novel approach using the moving window method is applied, in order to 1) train the developed models; 2) update the weight factors of each method and 3) further fuse the predicted results iteratively. In the proposed approach, both model-based and data-driven methods are simultaneously used to achieve a better accuracy. During the prediction process, each dataset in the proposed moving window are divided into three sections respectively: training, evaluation and prediction. The training data are used first to identify the models parameters. The evaluation data are then used to measure the weight of each method, which represents the degree of confidence of each method in the actual state. Based on these dynamically adjusting weight factors, the prediction results from different methods are then fused using weighted average methodology to calculate the final prediction results. In order to verify the proposed method, three experimental validations with different aging testing profiles have been performed. The results demonstrate that the proposed hybrid prognostic approach can achieve a higher accuracy than conventional prediction methods. In addition, in order to find the satisfactory trade-off between the prediction accuracy and forecast time for optimizing on-line prognostic, the performance variation of proposed approach with different moving window length is further showed and discussed. [ABSTRACT FROM AUTHOR]

Energy management strategy plays a key role for Fuel Cell Hybrid Electric Vehicles (FCHEVs), it directly affects the efficiency and performance of energy storages in FCHEVs. For example, by using a suitable energy distribution controller, the fuel cell system can be maintained in a high efficiency region and thus saving hydrogen consumption. In this paper, an energy management strategy for online driving cycles is proposed based on a combination of the parameters from three offline optimized fuzzy logic controllers using data fusion approach. The fuzzy logic controllers are respectively optimized for three typical driving scenarios: highway, suburban and city in offline. To classify patterns of online driving cycles, a Probabilistic Support Vector Machine (PSVM) is used to provide probabilistic classification results. Based on the classification results of the online driving cycle, the parameters of each offline optimized fuzzy logic controllers are then fused using Dempster-Shafer (DS) evidence theory, in order to calculate the final parameters for the online fuzzy logic controller. Three experimental validations using Hardware-In-the-Loop (HIL) platform with different-sized FCHEVs have been performed. Experimental comparison results show that, the proposed PSVM-DS based online controller can achieve a relatively stable operation and a higher efficiency of fuel cell system in real driving cycles. [ABSTRACT FROM AUTHOR]

In this paper, a novel degradation prediction model for proton-exchange-membrane fuel cell (PEMFC) performance is proposed based on a multiphysical aging model with particle filter (PF) and extrapolation approach. The proposed multiphysical aging model considers major internal physical aging phenomena of fuel cells, including fuel cell ohmic losses, reaction activity losses, and reactants mass transfer losses. Furthermore, in order to obtain accurate values of electrochemical activation losses under a variable load profile, a bisection solver is presented to solve the implicit Butler–Volmer equation. The proposed aging model is initialized at first by fitting the PEMFC polarization curve at the beginning of lifetime. During the prediction process, the aging dataset is then divided into two parts, learning and prediction phases. The PF framework is used to study the degradation characteristics and update the aging parameters during the learning phase. The suitable fitting curve functions are then selected to satisfy the degradation trends of trained aging parameters, and used to further extrapolate the future values of aging parameters in the prediction phase. By using these extrapolated aging parameters, the prediction results are thus obtained from the proposed aging model. Three experimental validations with different aging testing profiles have been performed. The results demonstrate the robustness and advantages of the proposed prediction method. [ABSTRACT FROM AUTHOR]

Dynamic variable coupling analysis is an important method to properly design a control structure for complex multivariable and multi-physical dynamic systems, such as fuel cells. The fuel cell is an electrochemical energy conversion device which includes different inter-coupled dynamic phenomena in electrical, fluidic, and thermal domains. In order to achieve optimized fuel cell performance, different operation variables, such as fuel cell temperature, inlet air flow rate, hydrogen pressure, and membrane water content, need to be properly controlled. In this paper, variable coupling analyses of fuel cell dynamic behaviors are presented and discussed based on a proton exchange membrane fuel cell (PEMFC) dynamic model, which considers in particular the transient phenomena in both fluidic and thermal domain. The analyses of dynamic phenomena step responses are conducted using the relative gain array for various control input variables. Quantitative analyses of coupling effects in different physical domains are shown and discussed. The analysis results can be used to optimize the controller design for fuel cell system. [ABSTRACT FROM PUBLISHER]

In this paper, a robust model-based battery state-of-charge (SOC) estimating algorithm is proposed with a novel approach based on combination of multimodels data-fusion technique and particle filter (PF). The proposed method is particularly adapted for SOC estimation under real-time conditions and the presence of measurement noise. In this innovative approach, multiple battery models have been used in order to accurately estimate a battery SOC. During the estimation process, the measured battery terminal voltage is compared with the multiple battery models output to generate individual residual, which is then used to calculate the weight of estimated value from each battery model. This weight, which represents the accuracy of observation equation of each battery model, is inversely proportional to the residual. The estimated SOC values from different models are then fused and the weights of estimated values from each battery model are adjusted dynamically using PF and weighted average methodology, in order to calculate the final SOC estimation of the battery. For each proposed battery model, the corresponding parameter-tuning strategies are also presented. In addition, the proposed method has been validated by experimental results. The results demonstrate that the proposed multimodels-based algorithm can be implemented effectively for real-time application, and achieve better accuracy than single model-based methods. [ABSTRACT FROM AUTHOR]

Highly transmissible Omicron variants of SARS-CoV-2 currently dominate globally. Here, we compare neutralization of Omicron BA.1, BA.1.1, and BA.2. BA.2 RBD has slightly higher ACE2 affinity than BA.1 and slightly reduced neutralization by vaccine serum, possibly associated with its increased transmissibility. Neutralization differences between sub-lineages for mAbs (including therapeutics) mostly arise from variation in residues bordering the ACE2 binding site; however, more distant mutations S371F (BA.2) and R346K (BA.1.1) markedly reduce neutralization by therapeutic antibody Vir-S309. In-depth structure-and-function analyses of 27 potent RBD-binding mAbs isolated from vaccinated volunteers following breakthrough Omicron-BA.1 infection reveals that they are focused in two main clusters within the RBD, with potent right-shoulder antibodies showing increased prevalence. Selection and somatic maturation have optimized antibody potency in less-mutated epitopes and recovered potency in highly mutated epitopes. All 27 mAbs potently neutralize early pandemic strains, and many show broad reactivity with variants of concern. [Display omitted] • Potent RBD antibodies from Omicron breakthrough vaccinees broadly neutralize VoC • These, possible recall antibodies, are focused in two main clusters • Somatic maturation adapts public antibodies to recover potency • BA.2 > BA.1 ACE2 affinity. BA.2 < BA.1 neutralization by vaccine serum and Vir-S309 Analysis of antibodies from SARS-CoV-2 Omicron breakthrough infections reveals their structural and functional properties as well as ability to neutralize different pandemic strains. [ABSTRACT FROM AUTHOR]

Abstract: A kind of transformation functions is proposed to realize the nonmagnetic invisibility cloak with minimized scattering on the basis of generalized transformation. By matching the impedance at the outer surface of the cloak, the transformations with two parameters are determined. The good performance of the cloak is indicated by the full wave simulation based on the finite element method. Furthermore, based on the calculation of total scattering cross section, it is shown that the scattering cross section is very sensitive to the different parameters even though the impedance at the exterior boundary matches perfectly with the free space. In addition, from the effective media theory, an alternating layered system composed of two isotropic materials is proposed to realize experimentally the cloak. [Copyright &y& Elsevier]

This case study of entrepreneurial migrants at, and associated with, the Dongguan Humen Zhisheng School explores the upward social mobility experienced by entrepreneurial migrants as they move from their hometowns to Dongguan and become business owners. The strategies they adopt during the transition are vital to achieving upward social mobility. To transform themselves from hired laborers to business owners, they seek funding from their original social networks based on family and location and set up new social networks in their places of residence to share information and other external resources. While moving upward, these migrants use their networks to create a new, distinct social space. Although entrepreneurial migrants readily adapt to urban life, the household registration system and discriminatory regulations based on it require them to return to their places of origin at crucial moments in their lives. In terms of political status and social reputation, entrepreneurial migrants still find themselves on the "fringe" of urban society. As a result, they have not truly completed the migration from countryside to city or moved to a higher social stratum. [ABSTRACT FROM AUTHOR]

The turnover of labor-intensive personnel in businesses is extremely frequent and is primarily manifested in "flowing back" and in "switching jobs." Field surveys and research have demonstrated that frequent and extensive job switching, as well as the rapid turnover of personnel, has had a significant impact on businesses. There are many reasons for migrant workers from the countryside to switch jobs, but young migrant workers from the countryside are more likely to switch jobs frequently. Irrational factors affect job switching, and these factors affect the careers of migrant workers from the countryside. Switching jobs has become a way for migrant workers in the new era to pursue self-realization as well as a way for them to express themselves and has ultimately become an action strategy for migrant workers from the countryside. [ABSTRACT FROM AUTHOR]

Based on research in a labor-intensive enterprise, this study discusses the differences between new and old migrant workers. One consists of the choice of, and attitude toward "flow-backs" (hui liu) and "switching jobs" (zhuan gong) on the part of new and old migrant workers. The authors maintain that "flow-backs" and "switching jobs" are the different means by which the new and old generation of migrant workers face future developments and handle opportunities that enable them to make subjective choices. Implied behind these opportunities are the migrant workers' different self-realization requirements, displacement strategies, and different perspectives on urban and rural life. Another concerns the self-categorization process of the new and old generation of migrant worker groups-in other words, how these groups have undergone subjective divisions due to differences in concepts and choices. By analyzing the mutual evaluations, delimitations, interactions, and even conflicts among them, a clearer understanding is obtained of the process of the new replacing the old within migrant worker groups. [ABSTRACT FROM AUTHOR]

It may be said that among all the casual worker groups, haulage workers are the most diverse and interesting category, and the category with the most "freedom." The haulage workers' "freedom" is relative; it is a vivid sign of their unwillingness to accept their status quo and the fact that that they cannot do otherwise. Another salient characteristic of haulage workers is that they are "scattered in form but not in spirit" (xing san shen bu san). Their work is relatively free, and their way of making a living unstable, but they maintain close connections with their fellow-townspeople and friends, possess spheres of influence, adhere to certain work principles, and have a sense of organization. [ABSTRACT FROM AUTHOR]

Of all migrant casual workers, construction workers as a group do the hardest work, the most dangerous jobs, and have the fewest guarantees. The vocation has a low threshold, is labor intensive, and engages a vast number of people, thus becoming the starting point for many migrant workers in their quest to make a living away from home or as a means of accumulating "seed capital." Once the time is ripe, they will move to other jobs, for which reason construction workers exhibit a high degree of mobility. [ABSTRACT FROM AUTHOR]

Nannies are an important group of the casual workers studied. In this article, six characteristics of the group are analyzed: the nature of their work and the personality characteristics of nannies; their age structure; reasons for working; marriage and family dynamics; their relationships with their employers; and their social networks. Analysis is by means of oral interviews with nannies in Guangzhou and Shenzhen. The gender aggregation effect salient among nannies means that they are a purely female vocational group which increases the group's vulnerabilities and weaknesses. [ABSTRACT FROM AUTHOR]

The article focuses on the main agricultural products including xianggu (shiitake mushrooms) and luohanguo (momordica grosvenori) that are involved in technological change among Guoshan Yao in Guangxi province, China. According to the author, Xianggu is the main traditional economic crop for the Guoshan Yao at Dongmian village, and the main food and economic resource on which the Guoshan Yao relied for their livelihood and development. Meanwhile, the cultivation of luohanguo replaced that of xianggu, becoming the main source of income for the Guoshan Yao. Moreover, the development of these two main crop is inseparable from the progress of scientific technique in which the villagers enhanced their incomes.

The article discusses various reports published within the issue, including one by Hu Mingwen on the investigation about the She people living in Jiangxi province and another by Sam Wong on the institutions perception towards local leaders and organizations.

On the basis of related literature and the author's field research in Jiangxi province, the present article discusses the process of ethnic group reconstruction and identification of the She people with the family names of Lan, Lei, and Zhong in the Gannan region of Jiangxi province, who were restored as members of the She ethnic group from their original Han ethnic group after ethnic policies were carried out in 1985. The author puts forward his personal opinions on the factors of ethnic identity and the two schools of theory on ethnic identification, namely primordialism and circumstantialism. [ABSTRACT FROM AUTHOR]

The article focuses on the composition and relation between the ethnic groups at Hehuang region in China. Hehuang region is considered as the cultural center and the most significant historical area for ancient ethnic groups and ethnic minority regimes which currently occupied by the Mongolians, Tibetans and Hui minority groups. It is seen that cultural identification is the factor in the interactive relations between ethnic groups which resulted to the mutual acting force on them and the development of the cognition level of related ethnic cultures.

Analyzes the kinship system in the Fenghuang village in China. Changing process of lineage organization in the village; Structure of the lineage systems; Revitalization of lineage organizations and local religions; Resurgence of lineage and religious ideologies; Five indicators to determine whether a lineage exists.

Introduces the issues concerning the development of Chinese anthropology in the 1990s. Establishment of the China Urban Anthropology Association; Workshop spreading the influence of anthropology in academic and wider societal circles; Reemphasis on the centrality of the feildwork.

Terminating the SARS-CoV-2 pandemic relies upon pan-global vaccination. Current vaccines elicit neutralizing antibody responses to the virus spike derived from early isolates. However, new strains have emerged with multiple mutations, including P.1 from Brazil, B.1.351 from South Africa, and B.1.1.7 from the UK (12, 10, and 9 changes in the spike, respectively). All have mutations in the ACE2 binding site, with P.1 and B.1.351 having a virtually identical triplet (E484K, K417N/T, and N501Y), which we show confer similar increased affinity for ACE2. We show that, surprisingly, P.1 is significantly less resistant to naturally acquired or vaccine-induced antibody responses than B.1.351, suggesting that changes outside the receptor-binding domain (RBD) impact neutralization. Monoclonal antibody (mAb) 222 neutralizes all three variants despite interacting with two of the ACE2-binding site mutations. We explain this through structural analysis and use the 222 light chain to largely restore neutralization potency to a major class of public antibodies. [Display omitted] • Despite similar RBD mutations, P.1 is easier to neutralize than B.1.351 • P.1, B.1.351, and B.1.1.7 partially or fully escape most VH3-53 antibodies • mAb 222 (VH3-53) retains neutralization against all three variants • Neutralization is restored in VH3-53 chimeric antibodies with mAb 222 LC Structural and functional analysis of the P.1 variant of SARS-CoV-2 from Brazil reveals less resistance to antibodies generated from natural infection or vaccination compared to another similar variant, B.1.351. A monoclonal antibody, mAb 222, is able to neutralize all three variants (P.1, B.1.351, and B.1.1.7), with its light chain able to restore neutralization potency to a broad group of antibodies. [ABSTRACT FROM AUTHOR]

The bottom platform is an important underwater sensor that can be used in communications, early warning, monitoring, and other fields. It may be affected by earthquakes, winds, waves, and other loads in the working environment, causing changes in posture and affecting its sensing function. Therefore, it is of practical engineering significance to analyze the force conditions and posture changes in the bottom platform. In order to solve the problem of postural stability of the underwater bottom platform, this paper establishes a fluid and structural simulation model of the underwater bottom platform. First, computational fluid dynamics (CFD) technology is used to solve the velocity distribution and forces in the watershed around the bottom platform under a 3 kn ocean current, where the finite element method (FEM) numerical calculation method is used to solve the initial equilibrium state of the bottom platform after it is buried. On this basis, this paper calculates the forces on the bottom platform and the posture of the bottom platform at different burial depths under the action of ocean currents. Additionally, the effects of different burial depths on the maximum displacement, deflection angle, and postural stability of the bottom platform are studied. The calculation results show that when the burial depth is greater than 0.6 m, and the deflection angle of the bottom platform under the action of the 3 kn sea current is less than 5°, the bottom platform can maintain a stable posture. This paper could be used to characterize the postural stability of underwater bottom platforms at different burial depths for the application of underwater sensors in ocean engineering. [ABSTRACT FROM AUTHOR]

The race to produce vaccines against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) began when the first sequence was published, and this forms the basis for vaccines currently deployed globally. Independent lineages of SARS-CoV-2 have recently been reported: UK, B.1.1.7; South Africa, B.1.351; and Brazil, P.1. These variants have multiple changes in the immunodominant spike protein that facilitates viral cell entry via the angiotensin-converting enzyme-2 (ACE2) receptor. Mutations in the receptor recognition site on the spike are of great concern for their potential for immune escape. Here, we describe a structure-function analysis of B.1.351 using a large cohort of convalescent and vaccinee serum samples. The receptor-binding domain mutations provide tighter ACE2 binding and widespread escape from monoclonal antibody neutralization largely driven by E484K, although K417N and N501Y act together against some important antibody classes. In a number of cases, it would appear that convalescent and some vaccine serum offers limited protection against this variant. [Display omitted] • Reduced B.1.351 neutralization by mAbs and sera induced by early SARS-CoV-2 isolates • B.1.351 neutralization titer reduced 8- to 9-fold for Pfizer and AstraZeneca vaccinees • E484K, K417N, and N501Y cause widespread escape from mAbs • NTD deletion in B.1.351 abrogates neutralization by a potent neutralizing human mAb Structure-function analysis of the SARS-CoV-2 variant B.1.351 using serum samples from convalescent and vaccinated individuals reveals how mutations in the viral spike protein result in tighter binding to the receptor ACE2 and allow escape from monoclonal antibody neutralization. [ABSTRACT FROM AUTHOR]

Antibodies are crucial to immune protection against SARS-CoV-2, with some in emergency use as therapeutics. Here, we identify 377 human monoclonal antibodies (mAbs) recognizing the virus spike and focus mainly on 80 that bind the receptor binding domain (RBD). We devise a competition data-driven method to map RBD binding sites. We find that although antibody binding sites are widely dispersed, neutralizing antibody binding is focused, with nearly all highly inhibitory mAbs (IC 50 < 0.1 μg/mL) blocking receptor interaction, except for one that binds a unique epitope in the N-terminal domain. Many of these neutralizing mAbs use public V-genes and are close to germline. We dissect the structural basis of recognition for this large panel of antibodies through X-ray crystallography and cryoelectron microscopy of 19 Fab-antigen structures. We find novel binding modes for some potently inhibitory antibodies and demonstrate that strongly neutralizing mAbs protect, prophylactically or therapeutically, in animal models. [Display omitted] • Map 377 mAbs: 19 of 80 recognizing the RBD are potent neutralizers; 1 potent NTD binder • 19 Fab-antigen complex structures; 80 mAbs mapped on RBD and clustered into 5 epitopes • Most potent mAbs are ACE2 blockers, neutralize with few ACE2s, some Fabs glycosylated • mAbs reveal unique examples of NTD binding, RBD binding mode, and LC optimization Dejnirattisai et al. present an in-depth study of the human antibody response to SARS-CoV-2 infection. By characterizing 377 human mAbs from recovered COVID-19 patients, and determining 19 protein structures, they construct a map of antibody footprints on the RBD that describes in great detail its antigenic anatomy. [ABSTRACT FROM AUTHOR]

SARS-CoV-2 has caused over 2 million deaths in little over a year. Vaccines are being deployed at scale, aiming to generate responses against the virus spike. The scale of the pandemic and error-prone virus replication is leading to the appearance of mutant viruses and potentially escape from antibody responses. Variant B.1.1.7, now dominant in the UK, with increased transmission, harbors 9 amino acid changes in the spike, including N501Y in the ACE2 interacting surface. We examine the ability of B.1.1.7 to evade antibody responses elicited by natural SARS-CoV-2 infection or vaccination. We map the impact of N501Y by structure/function analysis of a large panel of well-characterized monoclonal antibodies. B.1.1.7 is harder to neutralize than parental virus, compromising neutralization by some members of a major class of public antibodies through light-chain contacts with residue 501. However, widespread escape from monoclonal antibodies or antibody responses generated by natural infection or vaccination was not observed. [Display omitted] • Original strain convalescent and vaccine sera show reduced B.1.1.7 neutralization • N501Y enhances RBD: ACE2 binding affinity • N501Y compromises neutralization by many antibodies with public V-region IGHV3-53 • No widespread escape by B.1.1.7 was observed The SARS-CoV-2 B.1.1.7 variant is not neutralized as easily as the original form of the virus. Some public antibodies cannot neutralize B.1.1.7, due to altered light-chain contacts with residue 501. However, B.1.1.7 does not show widespread escape from monoclonal antibodies, natural antibody responses, or vaccines. [ABSTRACT FROM AUTHOR]

Unlike traditional rotary turbines, the flapping hydrofoil energy harvesters can capture kinetic energy from flowing fluids by undergoing combined heaving and pitching motions. In this paper, a new type of flapping hydrofoil energy harvester whose trailing-edge can deflect upwards during downstroke flapping cycle and downwards during the upstroke has been proposed. The energy-extraction performance of the proposed flapping hydrofoil then was investigated by numerical simulations based on the two-dimensional incompressible Navier-Stokes equations at a Reynolds number of 4.7 × 10 5. Influences of various characteristic parameters including deflection angle amplitude, flap length, gap width on the energy-extraction efficiency of the proposed flapping hydrofoil were analyzed. The present results show that the heaving force is the most dominant contributor to total power output of the flapping hydrofoil and it can be greatly increased due to the deflection of TEF. It is also found that there exist optimal deflection angle amplitude and TEF length which can significantly improve the energy-extraction efficiency at moderate to high values of reduced frequency. Moreover, the smaller the gap width, the higher the efficiency can be achieved. As a result, the maximum energy-extraction efficiency of the flapping hydrofoil with optimized TEF can be increased by approximately 23.5% compared to the conventional flapping hydrofoil-based current energy harvester. • A novel flapping hydrofoil energy harvester with trailing-edge flap (TEF) is proposed. • Energy extraction performance of the proposed flapping hydrofoil is numerically studied. • Effects of various parameters of TEF on the power extraction efficiency are analyzed. • An increment in power extraction efficiency is achieved by using the optimized TEF. [ABSTRACT FROM AUTHOR]

• Monolayer WS 2 crystal with edge lengths ranged from 10 to 460 μm can be readily synthesized on SiO 2 /Si substrate. • The WS 2 crystals exhibit homogeneous distributions of the crystallinity, electron doping and residual strain. • The amount of WO 3 used in this study is three orders lower than the commonly reported one and the semi-sealed quartz tube can be reused more than 50 times after mildly cleaning. Synthesis of monolayer WS 2 crystals on SiO 2 /Si substrate has attracted interests due to the advantage of fabrication of field effect transistor without WS 2 transfer process. Although substantial efforts have been achieved in recent years, controllable synthesis of uniform and large-area monolayer WS 2 crystals on SiO 2 /Si substrate is still challenging. Herein, we report an elegant method to synthesize monolayer WS 2 crystals on SiO 2 /Si substrate by using NaCl as a growth promoter in one semi-sealed quartz tube. It is found that triangular monolayer WS 2 with edge lengths ranged from 10 to 460 μm can be readily synthesized within 5 min of growth by adjusting the growth temperature and weight ratio of NaCl and WO 3. The Raman mapping results indicate that the as-synthesized WS 2 crystals exhibit homogeneous distributions of the crystallinity, electron doping and residual strain across the entire triangular domains regardless of their dimensions. However, the smaller WS 2 crystals exhibit a higher electron doping and less residual strain compared to the larger one obtained under the same growth conditions. Importantly, the amount of WO 3 used in this study is three orders lower than the commonly reported one and the semi-sealed quartz tube can be reused more than 50 times after mildly cleaning. [ABSTRACT FROM AUTHOR]

• Photodegradation occurs for TDBP-TAZTO and DBDPE under laboratory and near-natural conditions. • Photodegradation was affected by UV wavelength, intensity, solvent type and structural characteristics. • Photodegradation results in an array of degradation products with less bromine substitution. • The findings indicate photodegradation affects the fate and ecological risks of these flame retardants. Photodegradation has been demonstrated as one of the important environmental factors affecting the fate of contaminants such as brominated flame retardants (BFRs). However, a number of emerging BFRs, particularly those with high bromine substitution, have rarely been investigated for their photodegradation kinetics. Our study evaluated photodegradation of two highly brominated FRs, 1,3,5-tris-(2,3-dibromopropyl)-1,3,5-triazine-2,4,6-trione (TDBP-TAZTO) and decabromodiphenyl ethane (DBDPE), under various conditions. The results indicated that the degradation kinetics was affected by UV irradiation wavelength, intensity, solvent type, as well as the structural characteristics. TDBP-TAZTO exhibited degradation half-lives (t 1/2) of 23.5–6931 min under various UV irradiation conditions and 91.2 days under natural sunlight. Its degradation was much slower than that of DBDPE which exhibited t 1/2 of 0.8–101.9 min under UV and 41.3 min under natural sunlight. A variety of degradation products were detected as a result of different breakdown pathways. This indicated that photodegradation could substantially influence the fate of these highly brominated FRs, resulting in a cocktail of degradation products as environmentally occurring contaminants. This could also complicate the evaluation of the ecological risks of these target flame retardants, given that degradation products generally possess physicochemical properties and biological effects different from their parent chemicals. [ABSTRACT FROM AUTHOR]

We investigate the tunneling rates from a 2-dimensional electron gas (2DEG) into the ground state of self-assembled InGaAs quantum dots. These rates are strongly affected by a magnetic field perpendicular to the tunneling direction. Surprisingly, we find an increase in the rates for fields up to 4 T before they decrease again. This can be explained by a mismatch between the characteristic momentum of the quantum dot ground state and the Fermi momentum kF of the 2DEG. Calculations of the tunneling probability can account for the experimental data and allow us to determine the dot geometry as well as kF. [ABSTRACT FROM AUTHOR]

Urban migration for work creates problems both for migrant workers themselves and for the governments that must integrate new populations. The four articles in the present issue of Chinese Sociology and Anthropology analyze regional policy, schooling, upward mobility, job switching, urban-rural differences, and housing for their effect on migrant workers and the communities associated with them, both past and present. [ABSTRACT FROM AUTHOR]

Urban migration for work creates problems both for migrant workers themselves and for the governments that must integrate new populations. The four articles in the present issue of Chinese Sociology and Anthropology are based on research on urban migrants that was funded by the Chinese Ministry of Education and conducted under the sponsorship of Zhou Daming at Sun Yat-sen University. [ABSTRACT FROM AUTHOR]

Monolayer WS2 (Tungsten Disulfide) with a direct-energy gap and excellent photoluminescence quantum yield at room temperature shows potential applications in optoelectronics. However, controllable synthesis of large-area monolayer WS2 is still challenging because of the difficulty in controlling the interrelated growth parameters. Herein, we report a facile and controllable method for synthesis of large-area monolayer WS2 flakes by direct sulfurization of powdered WO3 (Tungsten Trioxide) drop-casted on SiO2/Si substrates in a one-end sealed quartz tube. The samples were thoroughly characterized by an optical microscope, atomic force microscope, transmission electron microscope, fluorescence microscope, photoluminescence spectrometer, and Raman spectrometer. The obtained results indicate that large triangular monolayer WS2 flakes with an edge length up to 250 to 370 μm and homogeneous crystallinity were readily synthesized within 5 min of growth. We demonstrate that the as-grown monolayer WS2 flakes show distinctly size-dependent fluorescence emission, which is mainly attributed to the heterogeneous release of intrinsic tensile strain after growth. [ABSTRACT FROM AUTHOR]

Gas diffusion layers (GDLs) in high-temperature, high-humidity, and high-electric-potential environments can be affected by the carbon corrosion and degradation of Polytetrafluoroethylene (PTFE) network structures, resulting in reduced reliability and hydrophobicity. By using cyclic voltammetry and offline characterization, a high-potential scanning of 1–1.5 V is applied to the GDL in the three-electrode system, considering the role of gradient graphitization degree and pore size structure in corrosion. Accelerating the electrochemical corrosion process of carbon and PTFE allows the identification of corrosion location, extent, and determinants. The results indicate that after 800 cycles of high-potential triangulation scanning, the graphitization of gas diffusion base has the most significant impact on the GDL's durability. On the other hand, the durability of the GDL's microporous layer is influenced by its small pore size structure rather than its graphitization degree. Furthermore, the corrosion process of GDLs with a small pore size structure tends to be relatively slow, providing a basis for GDL selection and durability prediction. [ABSTRACT FROM AUTHOR]

Due to the non-renewable nature and pollution associated with fossil fuels, there is widespread research into alternative energy sources. As a novel energy device, a proton exchange membrane fuel cell (PEMFC) is considered a promising candidate for transportation due to its advantages, including zero carbon emissions, low noise, and high energy density. However, the commercialization of fuel cells faces a significant challenge related to aging and performance degradation during operation. In order to comprehensively address the issue of fuel cell aging and performance decline, this paper provides a detailed review of aging mechanisms and influencing factors from the perspectives of both the PEMFC system and the stack. On this basis, this paper offers targeted solutions to degradation issues stemming from various aging factors and presents research on aging prediction methods to proactively mitigate aging-related problems. Furthermore, to enhance prediction accuracy, this paper categorizes and analyzes the degradation index and accuracy evaluation criteria commonly employed in the existing fuel cell aging research. The results indicate that specific factors leading to aging-related failures are often addressed via targeted solving methods, corresponding to specific degradation indexes. The significance of this study lies in the following aspects: (1) investigating the aging factors in fuel cells and elucidating the multiple aging mechanisms occurring within fuel cells; (2) proposing preventive measures, solutions, and aging prediction methods tailored to address fuel cell aging issues comprehensively, thereby mitigating potential harm; and (3) summarizing the degradation index and accuracy evaluation standards for aging prediction, offering new perspectives for resolving fuel cell aging problems. [ABSTRACT FROM AUTHOR]

Due to its advantages of high acceleration, reusability, environmental protection, safety, energy conservation, and efficiency, electromagnetic energy has been considered as an inevitable choice for future space launch technology. This paper proposes a novel three-level orbital launch approach based on a combination of a traditional two-level orbital launch method and an electromagnetic boost (EMB), in which the traditional two-level orbital launch consists of a turbine-based combined cycle (TBCC) and a reusable rocket (RR). Firstly, a mathematical model of a multi-stage coil electromagnetic boost system is established to develop the proposed three-level EMB-TBCC-RR orbital launch approach, achieving a horizontal take-off–horizontal landing (HTHL) reusable launch. In order to optimize the fuel quality of the energy system, an artificial intelligence algorithm parameters-sensitivity-based adaptive quantum-inspired glowworm swarm optimization (AQGSO)is proposed to improve the performance of the electromagnetic boosting system. Simulation results show that the proposed AQGSO improves the global optimization precision and convergence speed. By using the proposed EMB-TBCC-RR orbital launch system and the optimization approach, the required fuel weight was reduced by about 13 tons for the same launch mission, and the energy efficiency and reusability of the spacecraft was greatly improved. The spacecraft can be launched with more cargo capacity and increased payload. The proposed novel three-level orbital launch approach can help engineers to design and optimize the orbital launch system in the field of electromagnetic energy conversion and management. [ABSTRACT FROM AUTHOR]

The fuel cell with a ten-channel serpentine flow field has a low operating pressure drop, which is conducive to extended test operations and stable use. According to numerical results of the ten-channel serpentine flow field fuel cell, the multi-channel flow field usually has poor mass transmission under the ribs, and the lower pressure drop is not favorable for drainage from the outlet. In this paper, an optimized flow field is developed to address these two disadvantages of the ten-channel fuel cell. As per numerical simulation, the optimized flow field improves the gas distribution in the reaction area, increases the gas flow between the adjacent ribs, improves the performance of PEMFC, and enhances the drainage effect. The optimized flow field can enhance water pipe performance, increase fuel cell durability, and decelerate aging rates. According to further experimental tests, the performance of the optimized flow field fuel cell was better than that of the ten-channel serpentine flow field at high current density, and the reflux design requires sufficient gas flow to ensure the full play of the superior performance. [ABSTRACT FROM AUTHOR]

The article discusses various reports published within the issue, including one by Liu Linping and Li Chaohai on the involuntary nature and objective occupation nature of female prostitutes, another by Zhou Jianxin and Zhou Daming on studies regarding nannies, haulage workers and construction workers among the migrant casual workers in the Pearl River Delta and another by Liu Zhijun on the children that migrant workers leave behind in their native places.