Sandwich-type composited solid polymer electrolytes to strengthen the interfacial ionic transportation and bulk conductivity for all-solid-state lithium batteries from room temperature to 120℃

The insurmountable charge transfer impedance at the Li metal/solid polymer electrolytes(SPEs)interface at room temperature as well as the ascending risk of short circuits at the operating temperature higher than the melting point,dominantly limits their applications in solid-state batteries(SSBs).Although the inorganic filler such as CeO_(2)nanoparticle content of composite solid polymer electrolytes(CSPEs)can significantly reduce the enormous charge transfer impedance at the Li metal/SPEs interface,we found that the required content of CeO_(2)nanoparticles in SPEs varies for achieving a decent interfacial charge transfer impedance and the bulk ionic conductivity in CSPEs.In this regard,a sandwich-type composited solid polymer electrolyte with a 10%CeO_(2)CSPEs interlayer sandwiched between two 50%CeO_(2)CSPEs thin layers(sandwiched CSPEs)is constructed to simultaneously achieve low charge transfer impedance and superior ionic conductivity at 30℃.The sandwiched CSPEs allow for stable cycling of Li plating and stripping for 1000 h with 129 mV polarized voltage at 0.1 mA cm^(-2)and 30℃.In addition,the LiFePO_(4)/Sandwiched CSPEs/Li cell also exhibits exceptional cycle performance at 30℃and even elevated120℃without short circuits.Constructing multi-layered CSPEs with optimized contents of the inorganic fillers can be an efficient method for developing all solid-state PEO-based batteries with high performance at a wide range of temperatures.

On-chip quantum NOON state sensing for temperature and humidity

A maximal photon number entangled state,namely NOON state,can be adopted for sensing with a quantum enhancedprecision.In this work,we designed silicon quantum photonic chips containing two types of Mach-Zehnder interferometerswherein the two-photon NOON state,sensing element for temperature or humidity,is generated.Compared with classicallight or single photon case,two-photon NOON state sensing shows a solid enhancement in the sensing resolution andprecision.As the first demonstration of on-chip quantum photonic sensing,it reveals the advantages of photonic chips forhigh integration density,small-size,stability for multiple-parameter sensing serviceability.A higher sensing precision isexpected to beat the standard quantum limit with a higher photon number NOON state.

Several Cotton Rotation and Intercropping Systems in Cotton Planting Area of Eastern Henan Province

In recent years,the area dedicated to cotton cultivation in eastern Henan Province has experienced a continuous decline.Developing efficient multi-cropping systems for cotton and increasing the multiple cropping index represent effective strategies to stabilize the cotton planting area and enhance the income of cotton farmers.This paper presents an overview of intercropping systems and the benefits associated with cotton rotation and intercropping practices.Specifically,it discusses the"early maturing cotton-wheat"rotation system,the"cotton-watermelon"intercropping system,the"cotton-Dutch bean"intercropping system,and the"early maturing cotton-peanut-garlic"intercropping system.

The mini-GWAC optical follow-up of gravitational wave alerts – results from the O2 campaign and prospects for the upcoming O3 run

The second(O2)observational campaign of gravitational waves(GWs)organized by the LIGO/Virgo Collaborations has led to several breakthroughs such as the detection of GW signals from merger systems involving black holes or neutrons stars.During O2,14 GW alerts were sent to the astronomical community with sky regions mostly covering over hundreds of square degrees.Among them,six were finally confirmed as real astrophysical events.Since 2013,a new set of ground-based robotic telescopes called Ground-based Wide Angle Camera system(GWAC)project and its pathfinder mini-GWAC has been developed to contribute to the various challenges of multi-messenger and time domain astronomy.The GWAC system is built up in the framework of the ground-segment system of the SVOM mission that will be devoted to the study of the multi-wavelength transient sky in the next decade.During O2,only the mini-GWAC telescope network was fully operational.Due to the wide field of view and fast automatic follow-up capabilities of the mini-GWAC telescopes,they were adept to efficiently cover the sky localization areas of GW event candidates.In this paper,we present the mini-GWAC pipeline we have set up to respond to GW alerts and we report our optical follow-up observations of eight GW alerts detected during the O2 run.Our observations provided the largest coverage of the GW localization areas with a short latency made by any optical facility.We found tens of optical transient candidates in our images,but none of those could be securely associated with any confirmed black hole-black hole merger event.Based on this first experience and the near future technical improvements of our network system,we will be more competitive in detecting the optical counterparts from some GW events that will be identified during the upcoming O3 run,especially those emerging from binary neutron star mergers.

A Heterogeneous Information Fusion Method for Maritime Radar and AIS Based on D-S Evidence Theory

Maritime radar and automatic identification systems (AIS), which are essential auxiliary equipment for navigation safety in the shipping industry, have played significant roles in maritime safety supervision. However, in practical applications, the information obtained by a single device is limited, and it is necessary to integrate the information of maritime radar and AIS messages to achieve better recognition effects. In this study, the D-S evidence theory is used to fusion the two kinds of heterogeneous information: maritime radar images and AIS messages. Firstly, the radar image and AIS message are processed to get the targets of interest in the same coordinate system. Then, the coordinate position and heading of targets are chosen as the indicators for judging target similarity. Finally, a piece of D-S evidence theory based on the information fusion method is proposed to match the radar target and the AIS target of the same ship. Particularly, the effectiveness of the proposed method has been validated and evaluated through several experiments, which proves that such a method is practical in maritime safety supervision.

Timing of carbonatite-hosted U-polymetallic mineralization in the supergiant Huayangchuan deposit,Qinling Orogen:Constraints from titanite U-Pb and molybdenite Re-Os dating

The newly-discovered supergiant Huayangchuan uranium(U)-polymetallic(Sr,Se,REEs,Ba,Nb and Pb)deposit is located in the Qinling Orogen,central China.The deposit underwent multistage mineralization,with the main carbonatite ore stage being the most important for the U,Nb,REE,Sr and Ba endowments.According to the mineral assemblages,the main carbonatite ore stage can be divided into three substages,i.e.,sulfate(Ba-Sr),alkali-rich U and REE-U mineralization.Main-stage titanite from the Huayangchuan igneous carbonatite are rich in high field strength elements(HFSEs,e.g.,Zr,Nb and REEs),and show clear elemental substitutions(e.g.,Ti vs.Nb+Fe+Al and Ca+Ti vs.Fe+Al+REE).High-precision LA-ICP-MS titanite dating yielded a U-Pb age of 209.0±2.9 Ma,which represents the mainstage mineralization age at Huayangchuan,and is coeval with the local carbonatite dyke intrusion.This mineralization age is further constrained by the Re-Os dating of molybdenite from the Huayangchuan carbonatite,which yielded a weighted mean age of 196.8±2.4 Ma.Molybdenite Re contents(337.55-392.75 ppm)and C-OSr-Nd-Pb isotopic evidence of the Huayangchuan carbonatite both suggest a mantle origin for the carbonatite.Our study supports that the Late Triassic carbonatite magmatism was responsible for the world-class U-Mo-REE mineralization in the Qinling Orogen,and that the regional magmatism and ore formation was likely caused by the closure of the Mianlue ocean and the subsequent North China-South China continent-continent collision.

光催化产氢双助催化剂:类别、合成和设计策略

在低碳经济背景下,开发以氢能为代表的清洁可再生能源至关重要.利用太阳能驱动半导体进行光催化分解水,是未来可持续制取氢气的有效方法之一.然而,光催化制氢技术产业化受限于半导体表面光生载流子复合效率高和量子效率低.解决上述问题的办法是在半导体中引入双元助催化剂,这不仅可以促使三相界面的形成,促进界面电荷的有效转移,而且不同种类的双助催化剂可以为半导体提供各自的积极作用,协同提高光催化产氢效率和稳定性.因此,需要密切关注双助催化剂的开发,以建立一个集优异的光活性和光稳定性于一体的光催化产氢体系.本文系统地介绍了光催化产氢双助催化剂的类别、优势、合成方法和设计策略.首先,双助催化剂被分为双还原型(Red-Red)和还原-氧化型(Red-Ox)两类,详细概述了在光催化产氢领域中还原型和氧化型助催化剂相互匹配后形成的双助催化剂的实例及其协同效应.总结了在制氢体系中双助催化剂相对于单一助催化剂的五大优势:促进载流子快速迁移、实现电子-空穴空间分离、提高产氢吸附/脱附动力学、提高催化剂光稳定性和阻断可逆反应.随后,概括了双助催化剂-半导体光催化剂的合成策略,基于通常报道的水/溶剂热处理、煅烧、光沉积、自组装和化学沉积等助催化剂的合成方法,可以采用一步法和两步法将两种助催化剂加载到半导体上,获得三元复合材料.探讨了双助催化剂-半导体光催化体系的设计策略,详细总结了如何设计具有优化电子传递路径的Red-Red助催化剂体系和具有空间分离电荷的Red-Ox助催化剂体系.其中,为了优化电子传递路径,两种还原型助催化剂的位置关系可分为三类:核壳包裹结构、分散分布结构和相邻结构;为了实现氧化/还原位点空间分离,氧化-还原型双助催化剂在半导体表面可设计为三种结构:内外结构、晶面相关结构和端侧结构.最后,提出了双助催化剂在光催化制氢领域中的现状、挑战及未来发展方向.在未来,可以继续开发新型无贵金属助催化剂来降低催化剂体系总成本,真正达到经济实用目标;需要继续发展利于规模化生产的双助催化剂三元复合材料的合成策略;需要通过实验表征,结合同位素标记法、分子模拟和密度泛函理论计算,深入研究助催化剂的性质和作用机理.希望本文能够为构建高效实用的双助催化剂三元析氢光催化体系提供借鉴.

Enclosed stigma contributes to higher spikelet fertility for rice(Oryza sativa L.) subjected to heat stress

With global warming, rice plants may be subjected to heat stress more regularly during the heatsensitive flowering stage, causing spikelet sterility and grain yield loss.Stigma exsertion is considered to increase pollen reception and promote female reproductive success.The aim of this study was to investigate the role of stigma exsertion on spikelet fertility at high temperatures.Five rice cultivars(Liangyoupeijiu, Shanyou 63, Huanghuazhan, Nagina 22, and IR64) with differing degrees of stigma exsertion were cultivated and exposed to high temperature at anthesis.Heat-tolerant cultivars did not always show a high percentage of spikelets with exserted stigmas, and vice versa.Irrespective of the presence of more pollen grains on exserted stigmas, spikelets with exserted stigmas did not show greater spikelet fertility than spikelets with fewer exserted stigmas or hidden stigmas under heat stress.GA3 application augmented the percentage of spikelets with exserted stigmas;however, it did not increase spikelet fertility under heat stress.Spikelet fertility of whole panicles was negatively correlated with the percentage of spikelets with exserted stigmas, but positively with that with hidden stigmas.Viability of the hidden stigmas was less reduced than that of exserted stigmas under heat stress, suggesting that hidden stigmas have an advantage in maintaining viability.Heat stress delayed anther dehiscence and reduced the viabilities of both exserted stigmas and pollens, thereby causing low spikelet fertility.Together, these results suggest that high spikelet fertility does not depend on stigma exsertion and that enclosed stigma generally contributes to higher spikelet fertility and heat tolerance under high-temperature conditions during flowering in rice.

Urinary metabolomics analysis identifies key biomarkers of different stages of nonalcoholic fatty liver disease

AIM To identify a panel of biomarkers that can distinguish between non-alcoholic fatty liver disease(NAFLD) and non-alcoholic steatohepatitis(NASH), and explore molecular mechanism involved in the process of developing NASH from NAFLD.METHODS Biomarkers may differ during stages of NAFLD. Urine and blood were obtained from non-diabetic subjects with NAFLD and steatosis, with normal liver function(n = 33), from patients with NASH, with abnormal liver function(n = 45), and from healthy age and sex-matched controls(n = 30). Samples were subjected to metabolomic analysis to identify potential non-invasive biomarkers. Differences in urinary metabolic profiles were analyzed using liquid chromatography tandem mass spectrometry with principal component analysis and partial least squares-discriminate analysis.RESULTS Compared with NAFLD patients, patients with NASH had abnormal liver function and high serum lipid concentrations. Urinary metabonomics found differences in 31 metabolites between these two groups, including differences in nucleic acids and amino acids. Pathway analysis based on overlapping metabolites showed that pathways of energy and amino acid metabolism, as well as the pentose phosphate pathway, were closely associated with pathological processes in NAFLD and NASH.CONCLUSION These findings suggested that a panel of biomarkers could distinguish between NAFLD and NASH, and could help to determine the molecular mechanism involved in the process of developing NASH from NAFLD. Urinary biomarkers may be diagnostic in these patients and could be used to assess responses to therapeutic interventions.

The transcription factor OpWRKY2 positively regulates the biosynthesis of the anticancer drug camptothecin in Ophiorrhiza pumila

The limited bioavailability of plant-derived natural products with anticancer activity poses major challenges to the pharmaceutical industry.An example of this is camptothecin,a monoterpene indole alkaloid with potent anticancer activity that is extracted at very low concentrations from woody plants.Recently,camptothecin biosynthesis has been shown to become biotechnologically amenable in hairy-root systems of the natural producer Ophiorrhiza pumila.Here,time-course expression and metabolite analyses were performed to identify novel transcriptional regulators of camptothecin biosynthesis in O.pumila.It is shown here that camptothecin production increased over cultivation time and that the expression pattern of the WRKY transcription factor encoding gene OpWRKY2 is closely correlated with camptothecin accumulation.Overexpression of OpWRKY2 led to a more than three-fold increase in camptothecin levels.Accordingly,silencing of OpWRKY2 correlated with decreased camptothecin levels in the plant.Further detailed molecular characterization by electrophoretic mobility shift,yeast one-hybrid and dual-luciferase assays showed that OpWRKY2 directly binds and activates the central camptothecin pathway gene OpTDC.Taken together,the results of this study demonstrate that OpWRKY2 acts as a direct positive regulator of camptothecin biosynthesis.As such,a feasible strategy for the over-accumulation of camptothecin in a biotechnologically amenable system is presented.

Association of serum gamma-glutamyl transferase with treatment outcome in chronic hepatitis B patients

AIM:To investigate the association of serum gammaglutamyl transferase(GGT) levels with chronic hepatitis B infection and hepatitis B e antigen(HBe Ag) seroconversion.METHODS:A retrospective study was performed on clinical data collected from patients who had been positive for hepatitis B surface antigen for > 6 mo and who were antiviral-treatment na?ve(n = 215) attending the Hepatitis Clinic at Nanjing Drum Tower Hospital between August 2010 and December 2013. Healthy individuals without liver disease(n = 83) were included as controls. Patients were categorized into four groups based on disease status as recommended by the European Association for the Study of the Liver:immune tolerance(IT; n = 47),HBe Ag-positive hepatitis(EPH; n = 93),HBe Ag-negative hepatitis(ENH;n = 20),and inactive carrier(IC; n = 55). Prediction of complete response(CR) based on serum GGT was also examined in EPH patients(n = 33) treated for 48 wk with nucleos(t)ide analogue(NA) therapy,including lamivudine plus adefovir combination therapy(n = 20) or entecavir monotherapy(n = 13). CR was defined as a serum hepatitis B virus DNA level < 500 copies/m L and HBe Ag seroconversion by 48 wk of treatment. RESULTS:Serum GGT levels were significantly increased in EPH and ENH patients relative to the IT,IC,and healthy control groups(P < 0.01 for all). However,no significant difference in serum GGT levels was found between the EPH and ENH groups. Baseline serum GGT levels were significantly higher in patients who achieved CR(7/33; 21.2%) compared to patients in the non-CR group(26/33; 78.8%; P = 0.011). In addition,the decline in serum GGT was greater in CR patients compared to non-CR patients after 24 wk and 48 wk of treatment(P = 0.012 and P = 0.008,respectively). The receiver operating characteristic curve yielded a sensitivity of 85.71% and a specificity of 61.54% at a threshold value of 0.89 times the upper limit of normal for baseline serum GGT in the prediction of CR following NA therapy. CONCLUSION:Serum GGT is significantly elevated in EPH and ENH patients and is a potential biomarker for the prediction of HBe Ag seroconversion following NA therapy.

Response of spikelet water status to high temperature and its relationship with heat tolerance in rice

In rice, high-temperature stress(HT) during flowering results in decreased grain yield via a reduction in spikelet fertility;however, the effect of plant water status on spikelet fertility under HT remains unknown. To investigate the relationship between spikelet water status and spikelet fertility under HT, two experiments were performed under temperature-controlled conditions using four genotypes with varying tolerance to HT. Rice plants were exposed to HT for seven consecutive days during the flowering stage under three soil water treatments(soil water potential 0, -20, and -40 kPa), as well as under hydroponic conditions in a separate experiment. HT significantly decreased spikelet fertility, pollen fertility, and anther dehiscence under each of the three water treatments. HT significantly increased the spikelet transpiration rate, and this change was accompanied by a significant decrease in the internal temperature of the spikelets. HT decreased pollen grain diameter in heat-sensitive genotypes. HT had varying effects on the water potential of panicles and anthers but increased anther soluble-sugar concentration. Different aquaporin genes showed different expression profiles under HT, and the expression levels of PIPs for plasma membrane intrinsic proteins and TIPs for tonoplast intrinsic proteins increased in anthers but decreased in glumes.Correlation analyses showed that anther dehiscence and pollen(spikelet) fertility were tightly associated with anther water status, and the expression levels of almost all anther aquaporin genes were significantly correlated with anther dehiscence under HT. In summary, an increased spikelet transpiration rate and decreased internal spikelet temperature were associated with alleviation of the effects of HT in rice genotypes with varying degrees of heat tolerance, and the response of spikelet water status to HT, involving increased total expression of aquaporins and soluble sugar content, thereby improved pollen fertility,anther dehiscence, and spikelet fertility, especially in heat-resistant genotypes. The heat-resistant genotypes N22 and SY63 may adopt different approaches to reduce heat damage.

Optimization of the End Effect of Hilbert-Huang transform(HHT)

In fault diagnosis of rotating machinery, Hil- bert-Huang transform （HHT） is often used to extract the fault characteristic signal and analyze decomposition results in time-frequency domain. However, end effect occurs in HHT, which leads to a series of problems such as modal aliasing and false IMF （Intrinsic Mode Func- tion）. To counter such problems in HHT, a new method is put forward to process signal by combining the general- ized regression neural network （GRNN） with the bound- ary local characteristic-scale continuation （BLCC）. Firstly, the improved EMD （Empirical Mode Decompo- sition） method is used to inhibit the end effect problem that appeared in conventional EMD. Secondly, the gen- erated IMF components are used in HHT. Simulation and measurement experiment for the cases of time domain, frequency domain and related parameters of Hilbert- Huang spectrum show that the method described here can restrain the end effect compared with the results obtained through mirror continuation, as the absolute percentage of the maximum mean of the beginning end point offset and the terminal point offset are reduced from 30.113% and 27.603% to 0.510% and 6.039% respectively, thus reducing the modal aliasing, and eliminating the false IMF components of HHT. The proposed method caneffectively inhibit end effect, reduce modal aliasing and false IMF components, and show the real structure of signal components accuratelX.

Tracking charge transfer pathways in SrTiO_(3)/CoP/Mo_(2)C nanofibers for enhanced photocatalytic solar fuel production

Photocatalytic solar fuel generation is currently a hot topic because of its potential for solving the energy crisis owing to its low cost and zero-carbon emissions.However,the rapid bulk recombination of photoexcited carrier pairs is a fundamental disadvantage.To resolve this problem,we synthesized a dual cocatalysts system of cobalt phosphide(Co P)and molybdenum carbide(Mo_(2)C)embedded on strontium titanate(Sr TiO_(3))nanofibers.Compared with those of pristine SrTiO_(3) and binary samples,the dual cocatalysts system(denoted SCM)showed a significant improvement in the hydrogen evolution and CO_(2) reduction performance.Further,the structure of SCM effectively promoted spatial charge separation and enhanced the photocatalytic performance.In addition,the Schottky junction formed between the SrTiO_(3) and cocatalysts enabled the rapid transfer of photoexcited electrons from SrTiO_(3) to the cocatalysts,resulting in effective separation and prolonged photoexcited electron lifetimes.The electron migration route between SrTiO_(3) and the cocatalysts was determined by in situ irradiation X-ray spectroscopy,and band structures of Sr TiO_(3) and the cocatalysts are proposed based on results obtained from UV-vis diffraction reflection spectroscopy and ultraviolet photoelectron spectroscopy measurements.On the basis of our results,the dual cocatalysts unambiguously boosts charge separation and enhances photocatalytic performance.In summary,we have investigated the flux of photoexcited electrons in a dual cocatalysts system and provided a theoretical basis and ideas for subsequent research.

Single-atomic tungsten-doped Co_(3)O_(4) nanosheets for enhanced electrochemical kinetics in lithium–sulfur batteries

The practical application of lithium–sulfur batteries(LSBs)is severely hindered by the undesirable shuttling of lithium polysulfides(LiPSs)and sluggish redox kinetics of sulfur species.Herein,a series of ultrathin singleatomic tungsten-doped Co_(3)O_(4)(Wx-Co_(3)O_(4))nanosheets as catalytic additives in the sulfur cathode for LSBs are rationally designed and synthesized.Benefiting from the enhanced catalytic activity and optimized electronic structure by W doping,the Wx-Co_(3)O_(4) not only reduces the shuttling of LiPSs but also decreases the energy barrier of sulfur redox reactions of sulfur species,leading to accelerated electrode kinetic.As a result,LSB cathodes with the use of 5.0 wt%W0.02-Co_(3)O_(4) as the electrocatalyst show the high reversible capacities of 1217.0 and 558.6 mAh g^(-1) at 0.2 and 5.0 C,respectively,and maintain a high reversible capacity of 644.6 mAh g^(-1) at 1.0 C(1.0 C=1675 mA g^(-1))after 500 cycles.With a high sulfur loading of 5.5 mg cm^(-2) and electrolyte–electrode ratio of 8μL_(electrolyte) mg_(sulfur)^(-1),the 5.0 wt%W_(0.02)-Co_(3)O_(4)-based sulfur cathode also retains a high reversible areal capacity of 3.86 mAh cm^(-2) at 0.1 C after 50 cycles with an initial capacity retention of 84.7%.

面向数据权利、数据定价和隐私计算的数据驱动学习

近年来,数据已成为数字经济中最重要的生产要素之一。与传统生产要素不同,数据的数字化性质使其难以合同和交易。因此,建立一个高效和标准的数据交易市场体系将有利于降低成本,提高行业各方的生产力。尽管许多研究致力于数据法规和其他数据交易问题,如隐私和定价,但很少有工作对机器学习和数据科学领域的这些研究进行全面回顾。为了提供对这个主题的完整和最新的理解,本文涵盖了数据交易过程中的三个关键问题:数据权利、数据定价和隐私计算。通过厘清这些主题之间的关系,本文提供了一个数据生态系统的全貌,其中数据由个人、研究机构和政府等数据主体生成,而数据处理者出于创新或运营目的获取数据,并通过适当的定价机制根据数据主体各自的所有权分配收益。为了使人工智能(AI)能够长期有益于人类社会的发展,人工智能算法需要通过数据保护法规(即隐私保护法规)进行评估,以帮助构建日常生活中值得信赖的人工智能系统。

GPU-accelerated scanning path optimization in particle cancer therapy

When using the beam scanning method for particle beam therapy, the target volume is divided into many iso-energy slices and is irradiated slice by slice. Each slice may comprise thousands of discrete scanning beam positions. An optimized scanning path can decrease the transit dose and may bypass important organs. The minimization of the scanning path length can be considered as a variation of the traveling salesman problem; the simulated annealing algorithm is adopted to solve this problem. The initial scanning path is assumed as a simple zigzag path;subsequently, random searches for accepted new paths are performed through cost evaluation and criteria-based judging. To reduce the optimization time of a given slice,random searches are parallelized by employing thousands of threads. The simultaneous optimization of multiple slices is realized by using many thread blocks of generalpurpose computing on graphics processing units hardware.Running on a computer with an Intel i7-4790 CPU and NVIDIA K2200 GPU, our new method required only 1.3 s to obtain optimized scanning paths with a total of 40 slices in typically studied cases. The procedure and optimization results of this new method are presented in this work.

Microstructure evolution and its effect on mechanical properties of cast Ti48Al6NbxSi alloys

In order to improve mechanical properties of TiAlNb alloys,different contents of silicon were added into Ti48Al6Nb alloy.The Ti48Al6NbxSi (x=0,0.1,0.2,0.3,0.4 and 0.5,at.%) alloys were prepared by vacuum arc melting.The phase constitution,microstructure evolution and mechanical properties of the alloys were studied.Results show that the Ti48Al6NbxSi alloys consist of γ-TiAl phase,α2-Ti3Al phase and B2 phase,and Ti5Si3 silicide phase is formed when the addition of silicon is higher than 0.3at.%.The addition of silicon leads to the decrease in γ phase and increase in α2 phase.The formation of silicide decreases the amount of Nb dissolved in the TiAl matrix,and therefore decreases B2 phase.Compressive tests show that the ultimate strength of the alloys increases from 2,063 MPa to 2,281 MPa with an increase in silicon from 0 to 0.5at.%,while the fracture strain decreases from 34.7% to 30.8%.The increase of compressive strength and decrease of fracture strain can be attributed to the decrease of B2 phase and the formation of Ti5Si3 phase by the addition of silicon.The strengthening mechanism is changed from solid solution strengthening when the addition of silicon is less than 0.3at.% to combination of solid solution strengthening and secondary phase strengthening when the addition of silicon is higher than 0.3at.%.

通过预测学习者理解度比较英语不同变体的清晰度--一种语音实验方法

本实验研究着重于使用自动语音系统测量英语发音的清晰度,并在该可行性实验研究中进行系统的测试。实验挑选18名来自不同国家的受试者,代表6种类型的英语(中国、越南、埃及、印度、南非和菲律宾),这些受试者均能代表一系列语音的清晰程度。实验中使用了两种不同的方式——转录和无意义——测试和衡量英语发音的清晰度。其中基于超分段测量的口语能力评分的计算机自动模式被用来预测清晰度得分。人类评估得分和计算机预测得分之间的皮尔森相关性为0.743,无意义得分为0.819。转录得分的可靠内部评分Cronbach’s alpha为0.943,无意义可解性得分为0.945。根据可理解性测度的类型,计算机利用不同的超分段测量来预测得分并且使用了11个无意义理解度的指标和8个衡量转录分数的指标,两种结构方式显示出只有两类特性是共性的。这些计算机实验模式的分析和结果可为二语研究者在今后衡量发音可理解性的研究中提供不同的视角。

New supernova candidates from the SDSS-DR7 spectral survey

This letter presents 25 supernova candidates discovered from SDSS-DR7 by using our dedicated method, called Sample Decrease. Ten of them have been confirmed by other research groups, while the remaining 15, including 14 Type la and one Type Ⅱ, are first discovered based on Supernova Identification analysis. The results demonstrate that our method is reliable. The description of the method and some detailed spectral analysis procedures are also presented.