Realizing High Thermoelectric Performance in n-Type Se-Free Bi_(2)Te_(3)Materials by Spontaneous Incorporation of FeTe_(2)Nanoinclusions

Bi_(2)Te_(3)-based materials have drawn much attention from the thermoelectric community due to their excellent thermoelectric performance near room temperature.However,the stability of existing n-type Bi_(2)(Te,Se)_(3)materials is still low due to the evaporation energy of Se(37.70 kJ mol^(-1))being much lower than that of Te(52.55 kJ mol^(-1)).The evaporated Se from the material causes problems in interconnects of the module while degrading the efficiency.Here,we have developed a new approach for the high-performance and stable n-type Se-free Bi_(2)Te_(3)-based materials bymaximizing the electronic transport while suppressing the phonon transport,at the same time.Spontaneously generated FeTe_(2)nanoinclusions within the matrix during the melt-spinning and subsequent spark plasma sintering is the key to simultaneous engineering of the power factor and lattice thermal conductivity.The nanoinclusions change the fermi level of the matrix while intensifying the phonon scattering via nanoparticles.With a fine-tuning of the fermi level with Cu doping in the n-type Bi_(2)Te_(3)-0.02FeTe_(2),a high power factor of∼41×10^(-4)Wm^(-1)K^(-2)with an average zT of 1.01 at the temperature range 300-470 K are achieved,which are comparable to those obtained in n-type Bi_(2)(Te,Se)_(3)materials.The proposed approach enables the fabrication of high-performance n-type Bi_(2)Te_(3)-based materials without having to include volatile Se element,which guarantees the stability of the material.Consequently,widespread application of thermoelectric devices utilizing the n-type Bi_(2)Te_(3)-based materials will become possible.

An Improved Frag-Shells Algorithm for Data Cube Construction Based on Irrelevance of Data Dispersion

On-Line Analytical Processing (OLAP) is based on pre-computation of data cubes, which greatly reduces the response time and improves the performance of OLAP. Frag-Shells algorithm is a common method of precomputation.However, it relies too much on the data dispersion that it performs poorly, when confronts large amount of highly disperse data. As the amount of data grows fast nowadays, the efficiency of data cube construction is increasingly becoming a significant bottleneck. In addition, with the popularity of cloud computing and big data, MapReduce framework proposed by Google is playing an increasingly prominent role in parallel processing. It is an intuitive idea that MapReduce framework can be used to enhance the efficiency of parallel data cube construction. In this paper, by improving the Frag-Shells algorithm based on the irrelevance of data dispersion, and taking advantages of the high parallelism of MapReduce framework, we propose an improved Frag-Shells algorithm based on MapReduce framework. The simulation results prove that the proposed algorithm greatly enhances the efficiency of cube construction.

The histone methyltransferase EZH2 primes the early differentiation of follicular helper T cells during acute viral infection

Epigenetic modifications to histones dictate the differentiation of naïve CD4^(+) T cells into different subsets of effector T helper(TH)cells.The histone methyltransferase enhancer of zeste homolog 2(EZH2)has been implicated in the mechanism regulating the differentiation of TH1,TH2 and regulatory T(Treg)cells.However,whether and how EZH2 regulates follicular helper T(TFH)cell differentiation remain unknown.Using a mouse model of acute lymphocytic choriomeningitis virus(LCMV)infection,we observed abundant EZH2 expression and associated H3K27me3 modifications preferentially in the early committed virus-specific TFH cells compared to those in TH1 cells.Ablation of EZH2 in LCMV-specific CD4^(+) T cells leads to a selective impairment of early TFH cell fate commitment,but not late TFH differentiation or memory TFH maintenance.Mechanistically,EZH2 specifically stabilizes the chromatin accessibility of a cluster of genes that are important for TFH fate commitment,particularly B cell lymphoma 6(Bcl6),and thus directs TFH cell commitment.Therefore,we identified the chromatin-modifying enzyme EZH2 as a novel regulator of early TFH differentiation during acute viral infection.

Application requirements and design strategies of Bi_(2)Te_(3)-based thermoelectric devices for low-quality thermal energy

Bismuth telluride-based devices are capable of converting low-quality thermal energy into electrical power via the Seebeck effect.This transformative process not only extends the spectrum of energy utilization but also significantly amplifies energy efficiency.This review serves as a comprehensive guide,elucidating the intricate design considerations essential for optimizing bismuth telluride-based devices in both electrical and structural design.By exploring various application scenarios,it identifies critical parameters crucial for device effectiveness.Furthermore,the current landscape of thermoelectric(TE)devices is meticulously analyzed,synthesizing their developmental trajectory and contrasting it with stringent design requirements.Through this comprehensive analysis,it pinpoints key challenges that impede the maximal performance of existing TE devices.Envisioning the trajectory of bismuth telluride-based TE materials,this review makes projections regarding their future application trends.Traversing through contemporary mechanisms and technologies,it offers practical solutions and po-tential avenues aimed at enhancing the efficiency of TE devices.Ultimately,this discourse endeavors to provide invaluable insights,furnishing a roadmap for the advancement and refinement of TE devices in the years ahead.By proposing feasible solutions and charting plausible directions,it aspires to stimulate inno-vation and drive transformative progress in the domain of TE materials and science.

Thermoelectric properties of silicon and recycled silicon sawing waste

Large-scale-applicable thermoelectric materials should be both self-sustaining,in order to survive longterm duty cycles,and nonpolluting.Among all classes of known thermoelectric materials,these criteria reduce the available candidate pool,leaving silicon as one of the remaining options.Here we first review the thermoelectric properties of various silicon-related materials with respect to their morphologies and microstructures.We then report the thermoelectric properties of silicon sawing wastes recycled from silicon wafer manufacturing.We obtain a high power factor of~32 mWcm
1 K
2 at 1273 K with 6%phosphorus substitution in the Si crystal,a value comparable to that of phosphorus-doped silicongermanium alloys.Our work suggests the large-scale thermoelectric applicability of recycled silicon that would otherwise contribute to the millions of tons of industrial waste produced by the semiconductor industry.

Efficient control of chronic LCMV infection by a CD4 T cell epitope-based heterologous prime-boost vaccination in a murine model

CD4^(+)T cells are essential for sustaining CD8^(+)T cell responses during a chronic infection.The adoptive transfer of virus-specific CD4^(+)T cells has been shown to efficiently rescue exhausted CD8^(+)T cells.However,the question of whether endogenous virus-specific CD4^(+)T cell responses can be enhanced by certain vaccination strategies and subsequently reinvigorate exhausted CD8^(+)T cells remains unexplored.In this study,we developed a CD4^(+)T cell epitope-based heterologous prime-boost immunization strategy and examined the efficacy of this strategy using a mouse model of chronic lymphocytic choriomeningitis virus(LCMV)infection.We primed chronically LCMV-infected mice with a Listeria monocytogenes vector that expressed the LCMV glycoprotein-specific I-Ab-restricted CD4^(+)T cell epitope GP61–80(LM-GP61)and subsequently boosted the primed mice with an influenza virus A(PR8 strain)vector that expressed the same CD4^(+)T cell epitope(IAV-GP61).This heterologous prime-boost vaccination strategy elicited strong anti-viral CD4^(+)T cell responses,which further improved both the quantity and quality of the virusspecific CD8^(+)T cells and led to better control of the viral loads.The combination of this strategy and the blockade of the programmed cell death-1(PD-1)inhibitory pathway further enhanced the anti-viral CD8^(+)T cell responses and viral clearance.Thus,a heterologous prime-boost immunization that selectively induces virus-specific CD4^(+)T cell responses in conjunction with blockade of the inhibitory pathway may represent a promising therapeutic approach to treating patients with chronic viral infections.

Genome of the Giant Panda Roundworm Illuminates Its Host Shift and Parasitic Adaptation

Baylisascaris schroederi,a roundworm(ascaridoid)parasite specific to the bamboofeeding giant panda(Ailuropoda melanoleuca),represents a leading cause of mortality in wild giant panda populations.Here,we present a 293-megabase chromosome-level genome assembly of B.schroederi to infer its biology,including host adaptations.Comparative genomics revealed an evolutionary trajectory accompanied by host-shift events in ascaridoid parasite lineages after host separations,suggesting their potential for transmission and rapid adaptation to new hosts.Genomic and anatomical lines of evidence,including expansion and positive selection of genes related to the cuticle and basal metabolisms,indicate that B.schroederi undergoes specific adaptations to survive in the sharp-edged bamboo-enriched gut of giant pandas by structurally increasing its cuticle thickness and efficiently utilizing host nutrients through gut parasitism.Additionally,we characterized the secretome of B.schroederi and predicted potential drug and vaccine targets for new control strategies.Overall,this genome resource provides new insights into the host adaptation of B.schroederi to the giant panda as well as the host-shift events in ascaridoid parasite lineages.Our findings on the unique biology of B.schroederi will also aid in the development of prevention and treatment measures to protect giant panda populations from roundworm parasitism.

韧带重建联合胫骨高位截骨治疗晚期前交叉韧带损伤

[目的]比较前交叉韧带重建联合或不联合胫骨高位截骨术治疗晚期前交叉韧带损伤的临床效果。[方法]回顾性分析2016年1月~2018年12月期间来本院治疗的陈旧性前交叉韧带损伤患者46例。其中,20例行前交叉韧带重建联合胫骨高位截骨术,26例行常规单纯前交叉韧带重建。比较两组患者围手术期、随访与影像资料。[结果]两组患者均顺利手术,术中均未发生血管、神经损伤,筋膜室综合症等严重并发症。联合组在手术时间、术中失血量、切口长度方面均显著大于常规组(P<0.05)。所有患者随访12个月以上,与术前相比,末次随访时两组ROM、HSS评分和Lysholm评分均显著增加(P<0.05),而VAS评分均显著减少(P<0.05)。末次随访时,联合组ROM、HSS评分、Lysholm评分和VAS评分均显著优于常规组(P<0.05)。影像方面,末次随访时,联合组机械轴偏离距显著小于常规组(P<0.05)、内侧股骨近端角显著大于常规组(P<0.05)、关节线匹配角显著小于常规组(P<0.05)。[结论]胫骨高位截骨术可显著改善交叉韧带重建治疗晚期前交叉韧带损伤的临床效果。

Deep Audio-visual Learning:A Survey

Audio-visual learning,aimed at exploiting the relationship between audio and visual modalities,has drawn considerable attention since deep learning started to be used successfully.Researchers tend to leverage these two modalities to improve the performance of previously considered single-modality tasks or address new challenging problems.In this paper,we provide a comprehensive survey of recent audio-visual learning development.We divide the current audio-visual learning tasks into four different subfields:audiovisual separation and localization,audio-visual correspondence learning,audio-visual generation,and audio-visual representation learning.State-of-the-art methods,as well as the remaining challenges of each subfield,are further discussed.Finally,we summarize the commonly used datasets and challenges.

Experimental demonstration of suppressing residual geometric dephasing

The geometric phase is regarded as a promising strategy in fault tolerance quantum information processing(QIP) domain due to its phase only depending on the geometry of the path executed. However, decoherence caused by environmental noise will destroy the geometric phase. Traditional dynamic decoupling sequences can eliminate dynamic dephasing but can not reduce residual geometric dephasing, which is still vital for high-precision quantum manipulation. In this work, we experimentally demonstrate effective suppression of residual geometric dephasing with modified dynamic decoupling schemes,using a single trapped171 Ybtion. The experimental results show that the modified schemes can reduce dephasing rate up to more than one order of magnitude compared with traditional dynamic decoupling schemes, where residual geometric dephasing dominates. Besides, we also investigate the impact of intensity and correlation time of the low-frequency noise on coherence of the quantum system. And we confirm these methods can be used in many cases.

Experimental realization of nonadiabatic holonomic single‐qubit quantum gates with two dark paths in a trapped ion

For circuit-based quantum computation,experimental implementation of a universal set of quantum logic gates with high-fidelity and strong robustness is essential and central.Quantum gates induced by geometric phases,which depend only on global properties of the evolution paths,have built-in noise-resilience features.Here,we propose and experimentally demonstrate nonadiabatic holonomic single-qubit quantum gates on two dark paths in a trapped ^(171)γδ^(+)ion based on four-level systems with resonant drives.We confirm the implementation with measured gate fidelity through both quantum process tomography and randomized benchmarking methods.Meanwhile,we find that nontrivial holonomic two-qubit quantum gates can also be realized within current experimental technologies.Compared with previous implementations,our experiments share both the advantages of fast nonadiabatic evolution and robustness against systematic errors.Therefore,our experiments confirm a promising method for fast and robust holonomic quantum computation.

Zero sintering-induced shrinkage of porous oxide ceramics

Porous oxide ceramics are widely used in extreme working conditions owing to their excellent resistance to high temperatures and corrosion.However,sintering is an inevitable process applied to ceramics,from the green body to the final product.The highly complex structures exacerbate the shrinkage-induced ir-regular deformation and crack formation in the sintering process.A pioneering approach is developed in this study to achieve zero shrinkage for porous alumina ceramics during multistep sintering,using a combination of active fillers-ZrAl 3 and Al 75 Si 25.The response surface method is used to optimize the material compositions and sintering process,to achieve shrinkages of less than 0.05%for the entire pro-cess.The sintering expansion mechanism is investigated by analyzing the pyrolysis and microstructures of samples at different temperatures.The combination of ZrAl 3 and Al 75 Si 25 can attain the continuous expansion of the matrix in a wide temperature range of 600-1400°C.Furthermore,typical alumina com-ponents are fabricated and used to verify the effectiveness of the proposed approach.Owing to shrinkage suppression,the profile deviation of the samples is less than 0.1 mm,and the proportion of microcracks is reduced by 97.8%.The suggested approach shows potential applications in near-net,low-defect fabrica-tion of complex fine ceramic components.

DAPK1(death associated protein kinase 1)mediates mTORC1 activation and antiviral activities in CD8^(+)T cells

Mechanistic target of rapamycin complex 1(mTORCt)regulates CD8^(+)T-cell differentiation and function.Despite the links between PI3K-AKT and mTORCI activation in CD8^(+)T cells,the molecular mechanism underlying mTORCI activation remains undear.Here,we show that both the kinase activity and the death domain of DAPK1 are required for maximal mTOR activation and CD8^(+)T-cell function.We found that TCR-induced activation of calcineurin activates DAPK1,which subsequently interacts with TSC2 via its death domain and phosphorylates TSC2 to mediate mTORCI activation.Furthermore,both the kinase domain and death domain of DAPK1 are required for CD8^(+)T-cell antiviral responses in an LCMV infection model.Together,our data reveal a novel mechanism of mTORCI activation that mediates optimal CD8^(+)T-cell function and antiviral activity.

Erosion and deuterium retention behavior of tungsten exposed to impurity-seeded deuterium plasma

The effect of plasma impurity seeding on erosion and deuterium(D)retention behavior of tungsten(W)is investigated on linear experimental plasma system(LEPS).The incident D energy is 38 and 71 eV per D,and the D fluence varies from 3×10^(23)to 1×10^(26)D·m^(-2).The results of erosion reveal that argon(Ar)seeding strongly enhances erosion,helium(He)seed-ing slightly increases sputtering yield depending on the ratio of He in plasma,while nitrogen(N)seeding inhibits erosion and reduces the sputtering yield.Furthermore,O impurity dominates the erosion behavior during pure D plasma exposure when the D incident energy is lower than the sputtering threshold of W by D.For blistering and D retention behavior,compared with pure D exposure,Ar seeding reduces the amount and increases the size of blister,and leads to the increase of D inven-tory.He seeding has the opposite result,showing almost no blisters at sample surface and a dramatic drop in D retention.D retention decreases with increasing N content,and ruptured blisters are observed at a high D fluence of 1×10^(26)D·m^(-2).