Two new significant discoveries are reported: i) the dragline silk of N. clavipes spider has an exceptionally high thermal conductivity: up to 416 W/m·K that beats most materials; ii) contrary to ...normal materials, its thermal conductivity increases with strain (19% increase under ∼20% strain). These new findings will revolutionize the design of polymer fibers to increase their thermal conductivity by orders of magnitude.
Background
: Covid-19 has started to spread within China since the end of December 2019. Despite government’s immediate actions and strict control, more and more people were infected every day. As ...such a contagious virus can spread easily and rapidly between people, the whole country was put into lockdown and people were forced into isolation. In order to understand the impact of Covid-19 on mental health well-being, Chinese researchers have conducted several studies. However, no consistent results were obtained. Therefore, a meta-analysis was conducted.
Methods:
We searched Embase, PubMed, and Web of Science databases to find literature from December 2019 to April 2020 related to Covid-19 and mental health, among which results such as comments, letters, reviews and case reports were excluded. The incidence of anxiety and depression in the population was synthesized and discussed.
Results:
A total of 27,475 subjects were included in 12 studies. Random effect model is used to account for the data. The results showed that the incidence of anxiety was 25% (95% CI: 0.19–0.32), and the incidence of depression was 28% (95% CI: 0.17–0.38). Significant heterogeneity was detected across studies regarding these incidence estimates. Subgroup analysis included the study population and assessment tools, and sensitivity analysis was done to explore the sources of heterogeneity.
Conclusions:
Owing to the significant heterogeneity detected in studies regarding this pooled prevalence of anxiety and depression, we must interpret the results with caution. As the epidemic is ongoing, it is vital to set up a comprehensive crisis prevention system, which integrating epidemiological monitoring, screening and psychological crisis prevention and interventions.
Bladder cancer (BLCA) is a common malignant tumor of the urinary tract, which is the sixth most common cancer among men. Numerous studies suggested that pyroptosis and long noncoding RNAs (lncRNAs) ...played an essential role in the development of cancers. However, the role of pyroptosis-related lncRNAs in BLCA and their prognostic value are still unclear.
In this study, we constructed a signature model through least absolute shrinkage and selection operator (LASSO) Cox regression analysis and Cox univariate analysis based on The Cancer Genome Atlas (TCGA) database. The expression of 12 pyroptosis-related lncRNAs was also confirmed by qRT-PCR in BLCA cell lines. TIMER, XCELL, QUANTISEQ, MCPCOUNTER, EPIC, and CIBERSORT R script were applied to quantify the relative proportions of infiltrating immune cells. Correlation coefficients were computed by Spearman analyses. The Kaplan-Meier method, Cox regression model, and log-rank tests were used to evaluate the prognostic value. The R package of pRRophetic was used to predict IC50 of common chemotherapeutic agents.
A total of 12 pyroptosis-related lncRNAs with great prognosis value were identified. The expression was investigated by qRT-PCR in four BLCA cell lines. Then, 126 cases were identified as high-risk group, and 277 cases were identified as low-risk group based on the cutoff point. Patients in the low-risk group showed a significant survival advantage. Furthermore, we found that clinical features were significantly related to the risk score. As well, based on the C-index values, a nomogram was constructed. The gene set enrichment analysis (GSEA) results showed that mitogen-activated protein kinase (MAPK) signaling, transforming growth factor (TGF)-β signaling, and WNT signaling were with important significance in the high-risk group. Moreover, we found that riskscore was positively correlated with M0 macrophages and M2 macrophages.
In conclusion, our study indicated that pyroptosis is closely connected to BLCA. The riskscore generated from the expression of 12 pyroptosis-related lncRNAs was evaluated by various clinical features including survival status, tumor microenvironment, clinicopathological characteristic, and chemotherapy. It may offer a significant basis for future studies.
Using ab initio calculations combined with experiments, we clarified how the kinetics of Li-ion diffusion can be tuned in LiNi x Mn y Co z O2 (NMC, x + y + z = 1) materials. It is found that Li-ions ...tend to choose oxygen dumbbell hopping (ODH) at the early stage of charging (delithiation), and tetrahedral site hopping (TSH) begins to dominate when more than 1/3 Li-ions are extracted. In both ODH and TSH, the Li-ions surrounded by nickel (especially with low valence state) are more likely to diffuse with low activation energy and form an advantageous path. The Li slab space, which also contributes to the effective diffusion barriers, is found to be closely associated with the delithiation process (Ni oxidation) and the contents of Ni, Co, and Mn.
Many researchers have used a material response function termed “electroplasticity” to account for the mechanical behavior of metals subjected to electric current during plastic deformation. However, ...other researchers claimed that the electrically-assisted (EA) deformation behavior of metals could be successfully characterized using thermal-mechanical constitutive models without the need for electroplasticity theories. In order to examine the controversial mechanisms and determine which dominates the flow stress behavior under EA forming, this work established a flow stress model including the effects of strain hardening, rate hardening, thermal softening, solute–dislocation interaction and electron wind, where the latter three effects were assumed to contribute to the stress drop due to electric current. Additionally, an analytic thermal model was also established to capture the temperature variations during EA tension based on the energy balance between the heat generation due to Joule heating, and the heat losses due to conduction and convection. Also, the evolutions of strain rate and strain at specimen center were incorporated into both models to capture the effects of diffuse necking on thermal and mechanical behaviors during EA tension. Uniaxial micro-tension tests were conducted on AZ31 magnesium alloy specimens subjected to continuous electricity with various current densities to verify the proposed models. Results show that the thermal and mechanical models can effectively predict the thermal and mechanical behaviors of the AZ31 magnesium alloy at various current densities in EA micro-tension, respectively. The modeling results also demonstrate that Joule heating is the major factor to affect the deformation behavior under micro-tension subjected to continuous electricity.
•An analytic model is established to effectively predict current-induced temperatures.•Electrically-assisted tension behavior can be captured by proposed flow stress model.•Thermal softening due to Joule heating dominates stress drops in uniaxial tension.•Electroplastic effect makes insignificant contribution in continuous current case.
A 1.0wt.% graphene reinforced aluminum 6061 (Al6061) composite was synthesized to investigate the effects of graphene dispersion by ball milling technique. The Al6061 powder and graphene were ball ...milled at different milling times. The composites were then synthesized by hot compaction in the semi-solid regime of the Al6061. A three point bending test was performed to characterize the mechanical properties of the composite. The ball milled powder and the fracture surfaces of the composites were analyzed using the scanning electron microscopy. A maximum enhancement of 47% in flexural strength was observed when compared with the reference Al6061 processed at the same condition.
Transition-metal dichalcogenides (TMDs) have emerged in recent years as a special group of two-dimensional materials and have attracted tremendous attention. Among these TMD materials, molybdenum ...disulfide (MoS2) has shown promising applications in electronics, photonics, energy, and electrochemistry. In particular, the defects in MoS2 play an essential role in altering the electronic, magnetic, optical, and catalytic properties of MoS2, presenting a useful way to engineer the performance of MoS2. The mechanisms by which lattice defects affect the MoS2 properties are unsettled. In this work, we reveal systematically how lattice defects and substrate interface affect MoS2 electronic structure. We fabricated single-layer MoS2 by chemical vapor deposition and then transferred onto Au, single-layer graphene, hexagonal boron nitride, and CeO2 as substrates and created defects in MoS2 by ion irradiation. We assessed how these defects and substrates affect the electronic structure of MoS2 by performing X-ray photoelectron spectroscopy, Raman and photoluminescence spectroscopies, and scanning tunneling microscopy/spectroscopy measurements. Molecular dynamics and first-principles based simulations allowed us to conclude the predominant lattice defects upon ion irradiation and associate those with the experimentally obtained electronic structure. We found that the substrates can tune the electronic energy levels in MoS2 due to charge transfer at the interface. Furthermore, the reduction state of CeO2 as an oxide substrate affects the interface charge transfer with MoS2. The irradiated MoS2 had a faster hydrogen evolution kinetics compared to the as-prepared MoS2, demonstrating the concept of defect controlled reactivity in this phase. Our findings provide effective probes for energy band and defects in MoS2 and show the importance of defect engineering in tuning the functionalities of MoS2 and other TMDs in electronics, optoelectronics, and electrochemistry.
Peach (Prunus persica L.) is a highly valuable crop species and is recognized by molecular researchers as a model fruit for the Rosaceae family. Using whole-genome sequencing data generated from 129 ...peach accessions, here we perform a comprehensive genome-wide association study for 12 key agronomic traits. We show that among the 10 qualitative traits investigated, nine exhibit consistent and more precise association signals than previously identified by linkage analysis. For two of the qualitative traits, we describe candidate genes, one potentially involved in cell death and another predicted to encode an auxin-efflux carrier, that are highly associated with fruit shape and non-acidity, respectively. Furthermore, we find that several genomic regions harbouring association signals for fruit weight and soluble solid content overlapped with predicted selective sweeps that occurred during peach domestication and improvement. Our findings contribute to the large-scale characterization of genes controlling agronomic traits in peach.
Electrochemical experiments were conducted on {100}, {110}, and {111} silicon wafers to characterize the kinetics of the initial lithiation of crystalline Si electrodes. Under constant current ...conditions, we observed constant cell potentials for all orientations, indicating the existence of a phase boundary that separates crystalline silicon from the amorphous lithiated phase. For a given potential, the velocity of this boundary was found to be faster for {110} silicon than for the other two orientations. We show that our measurements of varying phase boundary velocities can accurately account for anisotropic morphologies and fracture developed in crystalline silicon nanopillars. We also present a kinetic model by considering the redox reaction at the electrolyte/lithiated silicon interface, diffusion of lithium through the lithiated phase, and the chemical reaction at the lithiated silicon/crystalline silicon interface. From this model, we quantify the rates of the reactions at the interfaces and estimate a lower bound on the diffusivity through the lithiated silicon phase.
Computational meta-optics brings a twist on the accelerating hardware with the benefits of ultrafast speed, ultra-low power consumption, and parallel information processing in versatile applications. ...Recent advent of metasurfaces have enabled the full manipulation of electromagnetic waves within subwavelength scales, promising the multifunctional, high-throughput, compact and flat optical processors. In this trend, metasurfaces with nonlocality or multi-layer structures are proposed to perform analog optical computations based on Green's function or Fourier transform, intrinsically constrained by limited operations or large footprints/volume. Here, we showcase a Fourier-based metaprocessor to impart customized highly flexible transfer functions for analog computing upon our single-layer Huygens' metasurface. Basic mathematical operations, including differentiation and cross-correlation, are performed by directly modulating complex wavefronts in spatial Fourier domain, facilitating edge detection and pattern recognition of various image processing. Our work substantiates an ultracompact and powerful kernel processor, which could find important applications for optical analog computing and image processing.
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