Stabilization of NCM811 cathode interface through macromolecular compound protective film formed by 2,5-bis(2,2,2-trifluoroethoxy)-benzoic acid additive in lithium metal batteries.

Lithium metal batteries (LMBs) offer substantial promise for next-generation energy storage owing to lithium metal's low reduction potential (-3.045 V vs. the standard hydrogen electrode) and its high specific capacity of 3860 mA h g-1. Among various cathode materials in LMBs, LiNi0.8Co0.1Mn0.1O2 (NCM811) is extensively employed because of its notably high specific capacity (over 200 mA h g-1) and comparatively lower cost. However, structural stress, nickel ions migration, and uneven Li+ deposition in NCM811 particles lead to cracking, irreversible decomposition of active substances, and the growth of mossy Li dendrites, causing severe capacity decline and low Coulomb efficiency in LMBs. In this study, we introduce an effective ethoxyl additive, 2,5-bis(2,2,2-trifluoroethoxy)-benzoic acid (2,5BTBA), directly into the carbonate electrolyte. This additive forms a dense and conductive macromolecular protective film on the NCM811 cathode and lithium metal anode during initial cycles, preventing electrode contact with the electrolyte. Consequently, it safeguards the cathode's structural integrity and enables dense lithium deposition. Adding 3 wt% 2,5BTBA, the Li/NCM811 battery retains a high capacity of 150.60 mA h g-1 and 89.41% retention after 700 cycles at 0.5C, maintaining an average Coulomb efficiency of 99.13%. This study presents an efficient and straightforward strategy to enhance the capacity retention of LMBs.

Mechanical properties of bilayer WS2and Graphene-WS2Hybrid composites by molecular dynamics simulations.

In the present work, by using molecular dynamics (MD) simulations, we investigate the mechanical properties of different nanostructures that may be core elements in next generation flexible/wearable photovoltaic devices, namely double layer WS2nanosheets (DLNS), graphene/WS2(layer) composites and graphene/WS2nanotube (NT) composites. Our results reveal that the mechanical properties of DLNS deteriorate when compared to those of monolayer WS2. Owing to graphene's reinforcement action, the mechanical properties of graphene/WS2(layer) composite with both layers deformed are superior than those of WS2, even though inferior than those of bare graphene. If stress is applied only to the graphene layer, the graphene/WS2composite retains the most of the strength and toughness of monolayer graphene, decreasing the fracture strength and Young's modulus by only 9.7% and 16.3%, respectively. Similarly, in the case of the graphene/WS2NT composite the mechanical strength and toughness experience a reduction compared to monolayer graphene, specifically by 15% and 53% for fracture strength and Young's modulus, respectively. Considering the market's keen interest in nanomaterials, particularly van der Waals (vdW) ones, for flexible and wearable photovoltaic devices, the findings presented here will significantly enhance the effective utilization of vdW composites.

Design and test a pneumatically actuated microgripper based on structural stiffness.

In response to the problem that the actual amplification ratio of the compliant motion amplification mechanism cannot be further improved, this paper introduces a two-stage amplification microgripper based on structural stiffness that is driven by pneumatics. The mechanism not only has the advantages of good symmetry, compact structure, and large output displacement but can also reduce the relative error of the theoretical and experimental amplification ratios. The first-stage mechanism selects high-stiffness mechanisms and high-stiffness flexure hinges, and the second-stage mechanism uses low-stiffness mechanisms and low-stiffness flexure hinges. The arrangement order of the mechanism is determined by the working mode analysis. The specific dimensions of the mechanism and flexure hinges are determined through structural size optimization so that the amplification performance of the mechanism will be optimal. The experimental results show that the displacement amplification ratio of both the opening and closing of the microgripper is 41.8.

Surveillance of Vaccination Coverage of Inactivated Influenza Vaccines and Allergic Rash Adverse Events Following Immunization for Children From 6 Manufacturers.

The composition of influenza vaccines is updated annually. To ensure vaccine safety, the coverage and adverse events following immunization (AEFI) of 6 manufacturers of trivalent inactivated influenza vaccine (TIV3) need to be evaluated. In January 2022, we analyzed data from more than 1.59 million children in the Childhood Vaccination Information Management System and the AEFI Surveillance Information Management System and evaluated influenza vaccines for children aged 6 to 35 months in Guangzhou from 2016/17 to 2019/20 Vaccination rates and AEFI reporting rates. From 2016/17 to 2019/20, the 1-dose influenza vaccination rate was 25.0% (range: 20.7%-30.2%), and the 2-dose (full course) influenza vaccination rate was 21.6% (range: 17.7%-26.4%). The full vaccination coverage rate has trended down since 2017/2018 (2017/18: 26.0%; 2018/19: 8.3; 2019/20: 17.7%). Fifty-two cases (13.1/100 000) and 24 cases (6.9/100 000) received AEFI reports for 1 dose and 2 doses, respectively, mainly due to fever ≥38.6°C (39 cases for 1 dose, 9.8/100 000; 15 cases for 2 dose, 4.3/100 000) and allergic rash (9 cases with 1 dose, 2.3/100 000; 5 cases with 2 doses, 1.4/100 000). Patients who received A and F manufacturers were more likely to report side effects. The safety of influenza vaccines from 6 manufacturers is good, and it is necessary to improve the recommended information on influenza vaccines to dispel people's concerns and increase the vaccination rate.

Macromolecular bridging-enhanced holey graphene oxide-based film and its humidity deformation response.

The interaction of water molecules with graphene oxide (GO) at the interface or surface will lead to the reversible deformation response of GO-based materials. However, the fabrication of structurally stable and highly sensitive GO-based humidity-responsive films remains a challenge. Since the stability and sensitivity of GO-based humidity-responsive devices are significantly limited by the deformation differences between different components. Herein, we demonstrate that polyamidoamine (PAMAM) bridge-enhanced carboxylated holey GO (hGC/PAMAM) films are sensitive to moisture and exhibit excellent stability in water. Experiments and molecular dynamics (MD) simulation show that the formation of N-C=O between PAMAM and GO sheets significantly increased the interlayer bonding force. Dynamic monitoring of the surface strain of the hGC/PAMAM films showed that the strains spread a gradient from the high-humidity to the low-humidity side, causing asymmetric expansion along the horizontal and vertical directions. This work will provide a better understanding of the mechanism of water molecule transport between layers.

Analysis of the coverage of inactivated enterovirus 71 (EV71) vaccine and adverse events following immunization with the EV71 vaccine among children from 2016 to 2019 in Guangzhou.

Background: Since 2016, China has approved the use of inactivated enterovirus 71 (EV71) vaccines produced by three manufacturers. The coverage and safety of different EV71 vaccines need to be evaluated.Research design and methods: The EV71 vaccination and AEFI data were collected from the Guangzhou Children's Vaccination Information Report Management System and the China AEFI Monitoring Information Management System, and the EV71 vaccine coverage rate and the AEFI incidence rate were analyzed.Results: From 2016 to 2019, the number of people who should have been vaccinated in Guangzhou was 2,781,618, and the coverage rates for doses 1 and 2 were 24.71% and 19.44%, respectively. The inoculation rates of vaccines from manufacturers A and B were between 3.03 and 10.46%. The reported incidence of AEFIs was 11.97 per 100,000 (147 cases), with fever (106 cases, 8.63 per 100,000) and allergic rash (59 cases, 4.80 per 100,000) being the most common reactions. There were no differences in the AEFI responses to the EV71 vaccines from the three manufacturers.Conclusion: The EV71 vaccines from the three manufacturers have good safety, but the EV71 vaccine coverage rate is low. It is recommended that vaccine publicity be strengthened and that the vaccine coverage rate in children be increased.

Impact-resistant carbon nanotube woven films: a molecular dynamics study.

Fiber-based fabrics have great potential in impacting protection. Here, we propose a novel nanostructure, wherein single-walled CNTs (SWCNTs) were employed to weave plain 2D films. The in-plane mechanical properties and impacting properties of SWCNT woven films (SWFs) were investigated via fully atomic molecular dynamics (MD) simulation. It was found that their fracture strength and Young's modulus present obvious anisotropy, depending on the loading direction. When the loading is along the CNT axis, the mechanical performances are the best. From the impacting test, we found that this SWF synchronously possesses high impacting strength and a percentage of absorbed energy. This is mainly a result of high intrinsic strength, excellent flexibility and radial deformation capability of CNTs. In addition, it was observed that the high-speed impact of projectile can lead to the intricate entanglements of CNTs, which also could dissipate some energy by friction between the CNTs. This study provides an in-depth understanding on the mechanical properties of SWFs and broadens the applications of CNT-based nanomaterials.

Interface Strength, Damage and Fracture between Ceramic Films and Metallic Substrates.

Interface strength, damage and fracture properties between ceramic films and metallic substrates affect the service reliability of related parts. The films' thickness, grain size and residual stress affect the interface properties and fracture behavior, thus related studies attract great attention. In this paper, the interface damage evolution and fracture behavior between ceramic films and metallic substrates were simulated by developing a three dimensional finite element model of alumina films on Ni substrates with cohesive elements in the interfaces. The interface fracture energy as a key parameter in the simulation was firstly determined based on its thermodynamic definition. The simulation results show the Mises stress distribution and damage evolution of the film/substrate structures during uniaxial tensile loading. Specially, when grain size of the films is in nanoscale, the interface strength increases obviously, agreeing with the previous experimental results. The effects of residual stress on interface properties was further simulated. The interface strength was found to decrease with increasing radial residual force and the axial residual pressure increases the interface strength. When the thickness of the films increases, the interface strength keeps a constant but the speed of interface damage becomes faster, that is, the thicker films show catastrophic fracture. The underlying mechanism of damage speed was analyzed. Understanding these size effects and the effects of residual stress is helpful to guide the design of related parts.

Safety of pentavalent DTaP-IPV/Hib combination vaccine in post-marketing surveillance in Guangzhou, China, from 2011 to 2017.

BACKGROUND: The DTaP-IPV/Hib combination vaccine can replace the acellular tetanus vaccine, polio vaccine, and the Haemophilus influenzae type B vaccine. Data on the safety of DTaP-IPV/Hib vaccines are required. We aimed to evaluate the safety of the vaccination program. METHODS: Using the National Adverse Events Following Immunization (AEFI) surveillance system (CNAEFIS) in Guangzhou, China, a retrospective study was performed from May 11, 2011, to December 31, 2017. There were 376 cases of adverse events after vaccination with the DTaP IPV/Hib vaccine. The primary analysis indicators were the number of vaccines used, the number of AEFI reports received, and the reporting rate (per 100,000). RESULTS: From May 1, 2011, to December 31, 2017, 516,000 doses of vaccine were inoculated, and 376 cases of adverse reactions were reported; the reporting rate was 72.8 per 100,000 vaccines. There were eight cases of serious AEFIs (1.5 per 100,000), with four cases of thrombocytopenic purpura (0.8 per 100,000); three cases of cyanosis of the lips, stiffness, and flexion of limbs, and convulsions (0.6 per 100,000); and one case of a high fever (0.2 per 100,000). The highest incidence of AEFIs occurred after the fourth dose (n = 207, 55.0%, 40.1 per 100,000), followed by the first dose (n = 81, 21.5%, 15.7 per 100,000), second dose (n = 48, 12.8%, 9.3 per 100,000) and third dose (n = 40, 10.6%, 7.7 per 100,000). The AEFI incidence was higher after injection of the vaccine into the deltoid muscle of the upper arm (n = 276, 73.4%, 53.5 per 100,000) than after injection of the vaccine into the thigh (n = 100, 26.6%, 19.4 per 100,000). There was a significant difference between AEFIs after injection into the deltoid of the upper arm deltoid and the thigh (x2 = 164.8, P < 0.05). CONCLUSIONS: Most of the reported AEFIs after DTaP-IPV/Hib vaccination are not serious. There were four cases of TP in this study; vaccination may be a rare cause of thrombocytopenic purpura.

Slip-spring simulations of different constraint release environments for linear polymer chains.

The constraint release (CR) mechanism has important effects on polymer relaxation and the chains will show different relaxation behaviour in conditions of monodisperse, bidisperse and other topological environments. By comparing relaxation data of linear polyisoprene (PI) chains dissolved in very long matrix and monodisperse melts, Matsumiya et al. showed that CR mechanism accelerates both dielectric and viscoelastic relaxation (Matsumiya et al. 2013 Macromolecules 46, 6067. (doi:10.1021/ma400606n)). In this work, the experimental data reported by Matsumiya et al. are reproduced using the single slip-spring (SSp) model and the CR accelerating effects on both dielectric and viscoelastic relaxation are validated by simulations. This effect on viscoelastic relaxation is more pronounced. The coincidence for end-to-end relaxation and the viscoelastic relaxation has also been checked using probe version SSp model. A variant of SSp with each entanglement assigning a characteristic lifetime is also proposed to simulate various CR environment flexibly. Using this lifetime version SSp model, the correct relaxation function can be obtained with equal numbers of entanglement destructions by CR and reptation/contour length fluctuation (CLF) for monodisperse melts. Good agreement with published experiment data is also obtained for bidisperse melts, which validates the ability to correctly describe the CR environment of the lifetime version model.

Current situation, causes, and countermeasures to NIP vaccine shortages in Guangzhou, China.

From 2017 to 2018, Guangzhou experienced a shortage in 3-6 types of National Immunization Program (NIP) vaccines. To evaluate the current situation and causes of the NIP vaccine shortage, we analysed the duration, intensity and causes of the shortage from data in the vaccine information system of the Guangzhou Center for Disease Control and Prevention; we also proposed countermeasures to resolve the shortage. In 2017, there were shortages of three types of NIP vaccines in Guangzhou. The most affected vaccines were inactivated poliovirus (IPV) vaccine and meningococcal group AC (MenAC) vaccine, accounting for 39.5% and 16.5% of the reported shortages, respectively. In 2018, the shortage extended to six vaccine types; the most affected were diphtheria, tetanus and pertussis (DTP) vaccine, MenAC vaccine, and Bacille Calmette Guerin (BCG) vaccine. The four main causes for the shortage were: 1) an insufficient production capacity; 2) a delay in batch issuance; 3) vaccine-related events; and 4) an extended bidding procurement cycle. Four solutions are proposed: 1) expand production output; 2) exempt creditworthy enterprises from batch inspections; 3) establish alternative enterprises and emergency use authorizations; and 4) establish public health funds and stockpile storage systems.

Study on the icosahedral fullerene structure with ultra-light and pressure resistance character.

An ultra-light icosahedral fullerene structure is described having 12 pentagonal faces at the vertices of the regular icosahedron and 20 triangular faces, which are expanded by hexagonal faces that consist of carbon atoms. When its size exceeds a critical value, the density of the icosahedron becomes lower than that of air. Since the hollow structure deforms under atmospheric pressure, we proposed the addition of helium atoms as a means to obtaining a floatable icosahedral fullerene with pressure-resistant character. According to these requirements, the radius of the midpoint ball of the edge is 493.33 µm; the total density of the helium-filled structure is 0.18 kg m-3; and the buoyancy per cubic meter in the air is 10.88 N. Theoretical calculation and simulation are combined to explore a new approach to ultra-light materials.

Cavitation in inhomogeneous soft solids.

A tiny spherical cavity expands in a homogenous neo-Hookean solid when subjected to an externally applied hydrostatic tension. If the applied tension reaches 2.5 times the shear modulus of the solid, the cavity expands unboundedly. Such a phenomenon is usually referred to as cavitation in soft solids. In previous studies, the soft solid is often assumed to have homogeneous mechanical properties. In this article, we study cavity expansion in inhomogeneous soft solids through analytical formulation and finite element simulations. We find that cavitation in an inhomogeneous soft solid can be greatly different from that in a homogenous one. In particular, we show that the relationship between the applied hydrostatic tension and the cavity size can be either monotonic or non-monotonic, depending on the geometry and material properties of the soft solid. We hope the results obtained in this article will be helpful in understanding the cavitation phenomenon in complex soft materials.

MiR-148b-3p inhibits renal carcinoma cell growth and pro-angiogenic phenotype of endothelial cell potentially by modulating FGF2.

MicroRNAs (miRNAs) have been implicated in a large number of biological processes such as tumor angiogenesis. MiR-148b-3p has been identified as a tumor suppressor in multiple cancer types and the function of miR-148b-3p in renal carcinoma remains unidentified. In this study, we found that the expression of miR-148b-3p was decreased in renal carcinoma based on GEO analysis and the gain-of-function experiments revealed that miR-148b-3p promoted renal carcinoma cell apoptosis and suppressed cell proliferation, migration in vitro and tumor growth in vivo. Functionally, the tube formation, invasion and migration capabilities of human umbilical vein endothelial cells (HUVECs) were suppressed by conditioned media derived from renal carcinoma 786-O cells that were transfected with miR-148b-3p mimics. Meanwhile, these conditioned media inhibited the proliferation and promoted apoptosis of HUVECs. The key angiogenesis inducer hypoxia inducible factor-1α (HIF-1α) and the pro-angiogenic mediators were decreased in 786-O cells that were transfected with miR-148b-3p mimics. Mechanistically, miR-148b-3p could target fibroblast growth factor-2 (FGF2) and further impaired the activation of fibroblast growth factor receptor 2 (FGFR2). Taken together, our findings demonstrate that miR-148b-3p attenuates renal carcinoma cell growth, the invasion and tube formation of endothelial cell potentially via regulating FGF2-FGFR2 signaling pathway.

Directly Modifying the Nonbonded Potential Based on the Standard Iterative Boltzmann Inversion Method for Coarse-Grained Force Fields.

Effective potentials are of great importance for coarse-grained (CG) simulations, which can be obtained by the structure-based iterative Boltzmann inversion (IBI) method. However, the standard IBI method is incapable of maintaining the mechanical and thermodynamic properties of the CG model in agreement with those of the all-atom model. Unlike the existing techniques, such as introducing friction force as the dissipative force to reduce the superatom motion while keeping the conservative force arising from the CG potential intact, we directly modified the standard IBI nonbonded potential by adding an empirical function. According to an analysis of the dissipative particle dynamics, the additional function did compensate for the friction reduction of the standard IBI CG model. In this work, the thermal fluctuation information from the nonbonded radial distribution function was incorporated into the additional empirical function. As an illustration of the new CG force fields, we presented simulations of the stress-strain relation and thermodynamic properties in terms of cis-polyisoprene and compared the statistical structure information of the superatoms with those of the IBI CG model and the all-atom model. It should be emphasized that the additional empirical function contributed to compensating for the friction reduction, irrespective of the functional form it took. In this sense, the proposed method was easily operable.

Nanoscale crosslinking in thermoset polymers: a molecular dynamics study.

In this paper, the nanoscale crosslinking process of thermoset polymer is studied using all-atom molecular dynamics. Based on the crosslinking simulations, the elastic properties of typical E51/593 thermoset polymer are predicted and verified by tensile experiments within a 10% error. The proposed method reveals a reliable understanding of the nanoscale crosslinking reactions occurring in thermoset polymers. Changes in system energy and overall density distribution, as well as the quantification of bond formation, yield a better insight into thermoset crosslinking that would be difficult to obtain through experimentation. The results give us confidence in realizing the virtual design of thermosets leading to tunable properties.

Measles epidemic from 1951 to 2012 and vaccine effectiveness in Guangzhou, southern China.

BACKGROUND: Since the National Expanded Program on Immunization was implemented in China, considerable progress has been made in reducing the incidence of measles. However, the incidence of measles increased again in 2004. Few post-marketing studies on measles vaccine effectiveness were reported in China. In this study, we aimed to describe the measles epidemic and to evaluate the effectiveness of the measles vaccine in Guangzhou, southern China. METHODS: Based on the surveillance data for measles, we investigated the epidemiology during different periods between 1951 and 2012. We analyzed the clinical characteristics of laboratory-confirmed cases of measles between 2009 and 2012 and conducted a case-control study using test-negative cases as controls. We determined the protective effect of measles vaccine. RESULTS: The highest annual incidence in Guangzhou was 2187.15/100,000 in 1964, and the lowest was 0.32/100,000 in 2011. The average incidence of measles from 1951 to 2012 was 306.27/100,000. There was a significant tendency of decline in recent years. From 2009 to 2012, there are 700 laboratory-confirmed cases were reported with an average onset age of 2.5 (median) years. The non-vaccinated target population (age<8 months and ≥ 15 years) accounted for 56.7% of the cases. The transient (non-resident) population accounted for 51.3% of the cases. Fewer cases were observed in the population targeted for measles vaccine (aged 8 months to 14 years). The effectiveness of a single dose of the measles vaccine was 89.1% (95% confidence interval (CI), 44.5-97.9), and the effectiveness of ≥ 2 doses of the measles vaccine was 97.8% (95% CI, 88.3-99.6) in children aged 8 months to 14 years old. CONCLUSIONS: There is a significant overall decline in the incidence of measles (including clinical and laboratory confirmed cases) in the measles vaccine targeted population in Guangzhou. Two doses of measles vaccine are more effective than one dose in preventing measles in China. In order to accelerate the elimination of measles, vaccination should also be given to the transient and the non-vaccine targeted population.

Graphene wrinkling: formation, evolution and collapse.

In this paper we focus on the studies of graphene wrinkling, from its formation to collapse, and its dependence on aspect ratio and temperature using molecule dynamics simulation. Based on our results, the first wrinkle is not formed on the edge but in the interior of graphene. The fluctuations of edge slack warps drive the wrinkling evolution in graphene which is distinguished from the bifurcation in continuum film. There are several obvious stages in wrinkling progress, including incubation, infancy, youth, maturity and gerontism periods which are identified by the atomic displacement difference due to the occurrences of new wrinkles. The wrinkling progress is over when the C-C bonds in highly stretched corners are broken which contributes to the wrinkling collapse. The critical wrinkling strain, the wrinkling pattern and extent depend on the aspect ratio of graphene, the wrinkling level and collapsed strains do not. Only the collapsed strain is sensitive to the temperature, the other wrinkling parameters are independent of the temperature. Our results would benefit the understanding of the physics of graphene wrinkling and the design of nanomechanical devices by tuning the wrinkles.

The physics of wrinkling in graphene membranes under local tension.

The wrinkling characteristics of a rectangular graphene membrane under local tension are studied in this paper based on the continuum theory. The characteristics of the primary bifurcation and secondary wrinkling are studied to discover the physics of graphene wrinkling. The wrinkling geometry is predicted by a continuum theory model. The results reveal that the first wrinkle is formed at the primary bifurcation point. The non-uniform stretch-induced compressed effects, that originate from both the loaded portion and the clamped edges, buckle the graphene to form the first wrinkle. Secondary wrinkling is generated on the boundary of the wrinkled regions and the slack regions near the loaded portion in the post-wrinkling stage is the intrinsic nature of the wrinkling rupture and evolution of graphene. In addition, the length of the loaded portion and the aspect ratio of graphene have great effects on the wrinkling characteristics. These results are tremendously useful in understanding the intrinsic nature of the structural instability of graphene.