Superior oxygen electrocatalyst derived from metal organic coordination polymers by instantaneous nucleation and epitaxial growth for rechargeable Li-O_(2) battery

Rechargeable aprotic Li-O_(2)batteries have attractea increasing attention due to their extremely high capacity,and it is very important to design appropriate strategies to synthesize efficient catalysts used as oxygen cathode.In present work,we present an expedient "instantaneous nucleation and epitaxial growth"(INEG) synthesis strategy for convenient and large-scale synthesis of ultrafine MOCPs nanoparticles(size 50-100 nm) with obvious advantages such as fast synthesis,high yields,low costs and reduced synthetic steps.The bimetallic Ru/Co-MOCPs are further pyrolyzed to obtain bimetallic Coand low content of Ru-based nanoparticles embedded within nitrogen-doped carbon(Ru/Co@N-C) as an efficient catalyst used in Li-O_(2)battery.The Ru/Co@N-C provides porous carbon framework for the ion transportation and O_(2)diffusion,and has large amounts of metal/nonmetal sites as active site to promote the oxygen reduction reaction(ORR)/oxygen evolution reaction(OER) in Li-O_(2)batteries.As a consequence,a high discharge specific capacity of 15246 mA h g^(-1)at 250 mA g^(-1), excellent rate capability at different current densities,and stable overpotential during cycling,are achieved.This work opened up a new understanding for the industrialized synthesis of ultrafine catalysts for Li-O_(2)batteries with excellent structural characteristics and electrochemical performance.

材料、能源、机械工程中高效的电流变技术——从机理到应用

电流变(ER)技术是一种基于电流变效应的先进技术。电流变技术中最常见的材料是电流变液(ERF)。电流变液是一种软物质智能材料,其黏度可以通过施加电场来可逆地调节。电流变液的衍生物、一种新型的电响应软物质材料——电流变弹性体(ERE),由于其不沉降、易封装的优点也得到了越来越多的关注。电流变材料由于其可逆可调、快速响应、低能耗等特性在机械工程中有着广泛的应用。除了基础的电流变材料的合成和应用以外,电流变技术还应用在了能源材料制备、石油运输、储能等诸多领域。电流变技术在能源领域的应用为其在其他领域的潜在应用提供了一个很好的范例。本文结合最新的研究成果,从机理到应用,系统地综述了电流变技术在材料、能源和机械工程等领域的研究现状和未来发展前景。

Synthesis and Performance of Li Fe_xMn_(1-x)PO_4/C as Cathode Material for Lithium Ion Batteries

LiFe Mn1-xPO4/C composites were synthesized by a solid-state reaction route using phenolic resin as both reducing agent and carbon source. The effect of Fe doping on the crystallinity and electrochemical performance of LiFexMnt xPOJC was investigated. The experimental results show that the Fe2＋ substitution for Mn2＋ will lead to crystal lattice shrinkage of LiFe Mn1-xPO4/C particles due to the smaller ionic radii of Fe2＋ In the investigated Fe doping range （x = 0 to 0.7）, LiFe Mn1-xPO4/C （x = 0.4） composites exhibited a maximum discharge capacity of 148.8 mAh/g at 0.1 C while LiF%MnI_xPO4/C （x = 0.7） composite showed the best cycle capability with a capacity retention ratio of 99.0% after 30 cycles at 0.2 C. On the contrary, the LiFe Mnl-xPO4/ C （x = 0.5） composite performed better trade-off on discharge capacity and capacity retention ratio, 127.2 mAh/ g and 94.7% after the first 30 cycles at 0.2 C, respectively, which is more preferred for practical applications.

Labor Force Participation Rates in China:Present and Future

This paper describes the changes in China’s total population,labor force age structure and labor force participation rate(LFPR).Based on census data,this paper assesses the age pattern and changes in the LFPR,examines factors affectingthe LFPR through modeling and predicts the trends of labor force development to 2050.We find that the labor force hasbeen growing rapidly at an average annual rate of 6 percent from 1980 to 2005 due to improvements in competency andstructure.On the other hand,the overall LFPR declined mainly due to prolonged education that slashed the LFPR amongadolescents.The age pattern of labor force participation is in the shape of an inverted-U curve.Results from a Logit regression model of labor participation indicate that labor force participation intensity is higher inthe South than in the North and higher among the male population than among the female population.Presuming that thetotal fertility rate climbs to 2.0,life expectancy increases by ten years,and delayed retirement age lengthen the duration oflabor participation.We have made the following forecasts:(1) China’s future working age population will decrease;(2) labor force willexperience zero growth within 15 years and then negative growth;(3) the middle-aged and elderly populations willaccount for a significant share of the labor force.It is important to explore ways to increase,train and use human resourcesand increase the LFPR and productivity.In today’s China,regional or structural labor force shortage has already emerged.With an ageing population,China should take proactive measures by relaxing its birth policy,increasing education andtraining,promoting labor flow,and increasing the LFPR among the middle-aged,particularly women,so as to preventsevere shocks from a diminishing labor force.

Highly active and durable core-shell electrocatalysts for proton exchange membrane fuel cells

This work presents simple post-treatment methods to selectively and partially remove the Pd core of Pd-Pt core–shell(Pt@Pd/C)catalysts.The proton exchange membrane fuel cell with the post-treated Pt@Pd/C cathode(Pt loading:0.10 mg·cm^(-2))delivers an impressive peak power density of 1.2 W·cm^(-2).The partial removal of Pd core endows an ultrahigh oxygen reduction reaction(ORR)mass activity of 0.32 A·g_(PGM)-1 when normalized to the platinum group metal(PGM)mass,or equivalently 0.55 A·mg_(Pt)^(-1) at 0.9 V measured in a fuel cell.The post-treatment thickens the Pt shells and mitigates the Pd dissolution during potential cycling.As a result,the post-treated core-shell catalyst demonstrates superior durability in ORR mass activity and polarization power density retention than untreated core-shell catalyst and benchmark Pt/C.In-situ inductively coupled plasmamass spectrometry(ICP-MS)results highlight that the amount of dissolved Pd in post-treated core–shell catalyst is 17-times lower than that of the untreated one.Our findings highlight the importance of structural tuning of catalysts in enhancing their mass activity and durability.

Co‑packaged optics(CPO):status,challenges,and solutions

Due to the rise of 5G,IoT,AI,and high-performance computing applications,datacenter trafc has grown at a compound annual growth rate of nearly 30%.Furthermore,nearly three-fourths of the datacenter trafc resides within datacenters.The conventional pluggable optics increases at a much slower rate than that of datacenter trafc.The gap between application requirements and the capability of conventional pluggable optics keeps increasing,a trend that is unsustainable.Copackaged optics(CPO)is a disruptive approach to increasing the interconnecting bandwidth density and energy efciency by dramatically shortening the electrical link length through advanced packaging and co-optimization of electronics and photonics.CPO is widely regarded as a promising solution for future datacenter interconnections,and silicon platform is the most promising platform for large-scale integration.Leading international companies(e.g.,Intel,Broadcom and IBM)have heavily investigated in CPO technology,an inter-disciplinary research feld that involves photonic devices,integrated circuits design,packaging,photonic device modeling,electronic-photonic co-simulation,applications,and standardization.This review aims to provide the readers a comprehensive overview of the state-of-the-art progress of CPO in silicon platform,identify the key challenges,and point out the potential solutions,hoping to encourage collaboration between diferent research felds to accelerate the development of CPO technology.

聚氨酯海绵中碳纳米管与各向异性形状Ni的协同效应增强电磁干扰屏蔽性能

巧妙的微观结构设计和合适的多组分策略仍然是高效吸收型电磁干扰屏蔽材料在轻质、低填充水平和薄样品厚度方面的挑战.本文基于独特的屏蔽胶囊结构,采用浸渍法制备了柔性水性聚氨酯/介电碳纳米管/磁各向异性镍(链或花)电磁屏蔽复合海绵.结果表明,增加镍(花状或链状)填料的含量可显著提高复合材料的导电性和电磁干扰屏蔽性能.水性聚氨酯/碳纳米管/8 wt%镍花-三聚氰胺海绵和水性聚氨酯/碳纳米管/8 wt%镍链-三聚氰胺海绵的电磁屏蔽性能分别为42.8和46.7 dB,优于仅含碳纳米管的复合海绵.碳纳米管与镍(花状或链状)之间的协同作用意味着复合海绵的屏蔽电磁干扰的主要机制来自于吸收过程.重要的是,在水性聚氨酯层的保护下,复合材料在强烈的物理和化学损伤下仍然表现出良好的电磁屏蔽性能.这项工作为设计新颖、轻量化和高效的电磁屏蔽复合材料提供了一种简单的协同策略,在便携式和可穿戴电子设备中显示出巨大的应用前景.

Enzyme-free photothermally amplified fluorescent immunosorbent assay(PAFISA)for sensitive cytokine quantification

Cytokine monitoring has attracted great attention due to its significance in the diagnosis and treatment of many diseases,such as tumors,microbial infections,and immunological diseases.Enzyme-linked immunosorbent assay(ELISA)is one of the most popular methods in cytokine detection,ascribing to the lavish signal amplification methods in the ELISA platform.In addition to classical enzymes,other signal amplifiers such as fluorescent probes,artificial nano-enzymes,and photothermal reagents have been applied to reduce the detection limit and produce more sensitive ELISA kits.Due to the accumulative effect of heat,photothermal reagents are promising materials in the signal amplification of ELISA.However,the lack of efficient photothermal generation material at an aggregate scale may delay the further development of this area.In this contribution,based on an efficient organic photothermal aggregate material,an enzyme-free photothermally amplified fluorescent immunosorbent assay system consisting of an assay microfluidic chip and detecting platform was developed.The photothermal nanoparticles with highly efficient photothermal conversion by harvesting energy via excited-state intramolecular motions and enlarging molar absorptivity were successfully prepared.The detection concentration at 50 pg/mL of interleukin-2 was achieved,realizing a signal improvement of detection limits by 20-fold compared to that of previously reported photothermal ELISA.The microscopic imaging integrated with plane sweeping technology provided high spatial resolution and precision,indicating the potential of achieving high throughput profiling at the microscale.Moreover,as an alternative excitation source,light-emitting diode not only provided a more affordable and miniaturized detection system but also revealed the great feasibility of intramolecular motion-induced photothermy nanoparticles for biological analyses.

Full-color monolithic hybrid quantum dot nanoring micro light-emitting diodes with improved efficiency using atomic layer deposition and nonradiative resonant energy transfer

Full-color displays based on micro light-emitting diodes(μLEDs) can be fabricated on monolithic epitaxial wafers. Nanoring(NR) structures were fabricated on a green LED epitaxial wafer; the color of NR-μLEDs was tuned from green to blue through strain relaxation. An Al_2O_3 layer was deposited on the sidewall of NR-μLEDs,which improved the photoluminescence intensity by 143.7%. Coupling with the exposed multiple quantum wells through nonradiative resonant energy transfer, red quantum dots were printed to NR-μLEDs for a full-color display. To further improve the color purity of the red light, a distributed Bragg reflector is developed to reuse the excitation light.

MR-DBSCAN： a scalable MapReduce-based DBSCAN algorithm for heavily skewed data

DBSCAN （density-based spatial clustering of ap- plications with noise） is an important spatial clustering tech- nique that is widely adopted in numerous applications. As the size of datasets is extremely large nowadays, parallel process- ing of complex data analysis such as DBSCAN becomes in- dispensable. However, there are three major drawbacks in the existing parallel DBSCAN algorithms. First, they fail to prop- erly balance the load among parallel tasks, especially when data are heavily skewed. Second, the scalability of these al- gorithms is limited because not all the critical sub-procedures are parallelized. Third, most of them are not primarily de- signed for shared-nothing environments, which makes them less portable to emerging parallel processing paradigms. In this paper, we present MR-DBSCAN, a scalable DBSCAN algorithm using MapReduce. In our algorithm, all the crit- ical sub-procedures are fully parallelized. As such, there is no performance bottleneck caused by sequential process- ing. Most importantly, we propose a novel data partitioning method based on computation cost estimation. The objective is to achieve desirable load balancing even in the context of heavily skewed data. Besides, We conduct our evaluation us- ing real large datasets with up to 1.2 billion points. The ex- periment results well confirm the efficiency and scalability of MR-DBSCAN.

Synthesis of Sub-micrometer Lithium Iron Phosphate Particles Using Supercritical Hydrothermal Method for Lithium Ion Batteries

In this study,sub-micrometer LiFePO_4 particles with high purity and crystallinity were synthesized using supercritical hydrothermal method as the cathode material for lithium ion batteries.Experimental results show that templates and calcination time have significant impacts on the purity,particle size and morphology of LiFePO_4 particles.The as-prepared LiFePO_4 particles using polyvinyl pyrrolidone(PVP) template with additional one hour calcination at 700℃exhibit characteristics of good crystallinity,uniform size distribution,high capacity and cycling performance.The specific discharge capacities of 141.2 and 114.0mA·h/g were obtained at the charge/discharge rates of 0.1 and 1.0 C,respectively.It retained 96.0%of an initial capacity after 100 cycles at 1.0 C rate.The good electrochemical performance of the as-synthesized material is attributed to the synergistic factors of its reasonable particle size and surface areas and high crystallinity.

Boosting the activity of Fe–N_x moieties in Fe–N–C electrocatalysts via phosphorus doping for oxygen reduction reaction

The Fe–N–C material is a promising non-noblemetal electrocatalyst for oxygen reduction reaction(ORR).Further improvement on the ORR activity is highly desired in order to replace Pt/C in acidic media.Herein,we developed a new-type of single-atom Fe–N–C electrocatalyst,in which Fe–Nxactive sites were modified by P atoms.The half-wave potential of the optimized material reached 0.858 V,which is 23 mV higher than that of the pristine one in a 0.1 mol L-1 HClO4 solution.Density functional theory(DFT)calculations revealed that P-doping can reduce the thermodynamic overpotential of the rate determining step and consequently improve the ORR activity.

Holey aligned electrodes through in-situ ZIF-8-assisted-etching for high-performance aqueous redox flow batteries

Fabricating electrodes with large specific surface area(SSA)and high permeability has been the longstanding target in redox flow batteries(RFBs).In this work,we propose a novel ZIF-8-assisted etching approach to form holey fibers in the electrospinning process of aligned electrode structures.The etching approach allows the formation of holey fibers with small pores of~50 nm,offering large active surface areas for redox reactions,while the aligned macrostructure with the holey fibers of 3–5 lm in diameter ensures a high permeability along the fiber direction.The application of the prepared electrodes to a vanadium redox flow battery(VRFB)enables an energy efficiency(EE)of 87.2%at the current density of 200 m A cm^(-2),which is 13.3%higher than that with conventional electrospun carbon electrodes.Even at high current densities of 300 and 400 m A cm^(-2),the battery still maintains energy efficiencies of 83.3%and 79.3%.More excitingly,the prepared electrode yields a high limiting current density of4500 m A cm^(-2) and a peak power density of 1.6 W cm^(-2).It is anticipated that the present electrospinning method combining the ZIF-8-assisted etching approach with a way to form ordered fiber structures will allow even more high-performance electrodes for RFBs in the future.

Enhancement of MoTe2 near-infrared absorption with gold hollow nanorods for photodetection

Infrared(IR)light photodetection based on two dimensional(2D)materials of proper bandgap has attracted increasing attention.However,the weak IR absorption in 2D materials,due to their ultrathin attribute and indirect bandgap in multilayer structures,degrades their performance when used as IR photodetectors.In this work,we utilize the fact that few-layer MoTe2 flake has a near-IR(NIR)bandgap and demonstrate a^60-fold enhancement of NIR response by introducing a gold hollow nanorods on the surface.Such gold hollow nanorods have distinct absorption peak located also at the NIR regime,therefore induces strong resonance,benefitting NIR absorption in MoTe2,resulting in strong near-field enhancement.With the evidence from steady and transient state optical spectra,we confirm that the enhancement of NIR response originates only photon absorption,rather than electron transport at interfaces as observed in other heterostructures,therefore,precluding the requirement of high-quality interfaces for commercial applications.

Copy number variation profile-based genomic typing of premenstrual dysphoric disorder in Chinese

Premenstrual dysphoric disorder(PMDD) affects nearly 5% of women of reproductive age. Symptomatic heterogeneity, together with largely unknown genetics, has greatly hindered its effective treatment. In the present study, analysis of genomic sequencing-based copy number variations(CNVs) called from 100 kb white blood cell DNA sequence windows by means of semisupervized clustering led to the segregation of patient genomes into the D and V groups, which correlated with the depression and invasion clinical types,respectively, with 89.0% consistency. Application of diagnostic CNV features selected using the correlation-based machine learning method enabled the classification of the CNVs obtained into the D group, V group, total patient group, and control group with an average accuracy of 83.0%. The power of the diagnostic CNV features was 0.98 on average, suggesting that these CNV features could be used for the molecular diagnosis of the major clinical types of PMDD. This demonstrated concordance between the CNV profiles and clinical types of PMDD supported the validity of symptom-based diagnosis of PMDD for differentiating between its two major clinical types, as well as the predominantly genetic nature of PMDD with a host of overlaps between multiple susceptibility genes/pathways and the diagnostic CNV features as indicators of involvement in PMDD etiology.

Identification of molecular biomarkers for the diagnosis of gastric cancer and lymph-node metastasis

Background and objective:Biomarkers are important tools for prompt diagnosis of cancer.This study aimed to identify reliable biomarkers for clinical applications in the diagnosis of gastric cancer and lymph-node(LN)metastasis.Methods:Between 1 December 2014 and 31 December 2015,we prospectively collected samples of gastric-cancer tissues,corresponding matched-pair normal gastric mucosa,and their peri-gastric metastatic and non-metastatic LNs to identify quantitatively reliable genes using quantitative real-time polymerase chain reaction.Relative quantity(RQ)was used to calculate the mRNA expression levels of our target genes.Statistics were calculated using one-way analysis of variance(ANOVA)and Tukey’s multiple comparison test.Analytical graphs were plotted using GraphPad Prism.Results:Of nine assessed genes,the mRNA levels of inhibin beta A(INHBA)and secreted phosphoprotein 1(SPP1)were most consistently highly expressed in tumor tissues by 15.4-and 15.6-fold,respectively,as compared with normal tissues(P<0.001),with 91.3%sensitivity and 95.7%specificity(receiver operating characteristic[ROC]curve area=0.974)for the former and 82.6%sensitivity and 87.0%specificity(ROC curve area=0.924)for the latter.Further analysis revealed no differentiating significance of SPP1 mRNA expression between metastatic and non-metastatic LNs(P=0.470).In contrast,the INHBA mRNA level was up-regulated 4.1-fold in metastatic LNs(P<0.001),with 80.0%sensitivity and 81.5%specificity(ROC curve area=0.857),and was also able to successfully differentiate between more severe disease conditions,T3 and T4(P=0.003),M0 and M1(P=0.043)and different histological variants(intestinal type vs diffuse type,P=0.019).Conclusions:Our results showed that INHBA was the most optimally reliable biomarker for diagnosing gastric cancer and LN metastasis.

A dual plasmonic core-shell Pt/[TiN@TiO_(2)]catalyst for enhanced photothermal synergistic catalytic activity of VOCs abatement

Volatile organic compounds(VOCs)are ubiquitous organic pollutants affecting atmospheric environment and human health.The development of new efficient and environmentally friendly materials utilizing photothermal synergistic catalysis for purification of VOCs is still challenging.Herein,we design and prepare a core–shell TiN@TiO_(2)nanostructure integrating with nanoscaled Pt(Pt/[TiN@TiO_(2)])by an attractive quenching method.The strong light-harvesting capability of Pt and TiN components improve light-to-heat utilization efficiency by their intrinsic surface plasmon resonance effect.The TiO_(2)component upon the surface and the coexisting coupling effect of Pt0 and Pt2+enhance the photocatalytic effect of the system.As a result,the catalytic performance is significantly improved with toluene(120 ppm)conversion of 100%under the gas hourly space velocity of 72,000 mL·g^(−1)·h^(−1)and light illumination of 500 mW·cm^(−2).The desired catalyst thus achieves highly efficient coupling effect of photocatalysis and light-to-heat conversion for promoting VOCs abatement.

Expanding our understanding of marine viral diversity through metagenomic analyses of biofilms

Recent metagenomics surveys have provided insights into the marine virosphere.However,these surveys have focused solely on viruses in seawater,neglecting those associated with biofilms.By analyzing 1.75 terabases of biofilm metagenomic data,3974 viral sequences were identified from eight locations around the world.Over 90%of these viral sequences were not found in previously reported datasets.Comparisons between biofilm and seawater metagenomes identified viruses that are endemic to the biofilm niche.Analysis of viral sequences integrated within biofilm-derived microbial genomes revealed potential functional genes for trimeric autotransporter adhesin and polysaccharide metabolism,which may contribute to biofilm formation by the bacterial hosts.However,more than 70%of the genes could not be annotated.These findings show marine biofilms to be a reservoir of novel viruses and have enhanced our understanding of natural virus-bacteria ecosystems.