Investigation of phase modulation and propagation-route effect from unmatched large-scale structures for Doppler reflectometry measurement through 2D full-wave modeling

To interpret the common symmetric peaks caused by the large-scale structure in the complex S(f)spectrum from the heterodyne Doppler reflectometry(DR)measurement in EAST,a 2D circular-shaped O-mode full-wave model based on the finite-difference time-domain method is built.The scattering characteristics and the influences on the DR signal from various scales are investigated.When the structure is located around the cutoff layer,a moving radial or poloidal large-scale structure k_(θ)k_(θ),match(k_(θ),match is the theoretic wavenumber of Bragg scattering)could both generate an oscillation phase term called‘phase modulation’,and symmetrical peaks in the complex S(f)spectrum.It was found that the image-rejection ratio A_(−1)/A_(+1)(A_(±1)represents the amplitudes of±1 order modulation peaks)could be a feasible indicator for experiment comparison.In the case when the structure is near the cutoff layer with the same arrangement as the experiment for the edge DR channel,the curve of A_(−1)/A_(+1)versus kθcan be divided into three regions,weak asymmetrical range with k_(θ)/k_(0)0.15(k_(0)is the vacuum wavenumber),harmonics range with 0.15k_(θ)/k_(0)0.4,and Bragg scattering range of 0.4k_(θ)/k_(0)0.7.In the case when the structure is located away from the cutoff layer,the final complex S(f)spectrum is the simple superimposing of modulation and Bragg scattering,and the modulation peaks have an amplitude response nearly proportional to the local density fluctuation,called the‘propagationroute effect’.Under the H-mode experiment arrangement for the core DR,a critical fluctuation amplitude Amp(n_(e,Mod.@route))/Amp(n_(e,Tur.@MSA)∼1.3–4.1(Amp(n_(e,Mod.@route))refers to the pedestal large-scale structure amplitude and Amp(ne,Tur.@MSA)refers to turbulence amplitude at the main scattering area)is needed for the structure in the pedestal to be observed by the core DR measurement.The simulations are well consistent with the experimental results.These effects need to be carefully considered during the DR signal analyses as the injecting beam passes through the plasma region with large-scale structures.

Radio-frequency measurements of energetic-electron-driven emissions using high-frequency magnetic probe on XuanLong-50 spherical torus

A high-frequency magnetic probe is designed and developed on the XuanL ong-50(EXL-50)spherical torus to measure high-frequency magnetic field fluctuation.The magnetic loop,radio filters,radio-frequency limiter,and data acquisition system of the probe are comprehensively examined.The fluctuation data from the EXL-50 plasma are analyzed in the time–frequency domain using fast Fourier transforms.Moreover,distinct high-frequency instabilities are detected using this diagnostic system.In particular,significant frequency chirping is observed,which is consistent with the bumpon-tail drive instability predicted using the Berk–Breizman model.

PD-L1 is increased in the spinal cord and infiltrating lymphocytes in experimental allergic encephalomyelitis

Experimental allergic encephalomyelitis is a mouse model of human multiple sclerosis with similar pathology and pathogenesis. Thl cells play an important role in the pathogenesis of experimental allergic encephalomyelitis. This study determined the potential effect of programmed cell death 1 ligand 1 in the pathogenesis of experimental allergic encephalomyelitis induced by injecting myelin oligodendrocyte glycoprotein, complete Freund＇s adjuvant and Bordetella pertussis toxin into C57BL/6J mice. Experimental allergic encephalomyelitis mice developed disease and showed in- flammatory changes in the central nervous system by hematoxylin-eosin staining of spinal cord pathological sections, demyelination by Luxol fast-blue staining and clinical manifestations. The expression of programmed cell death 1 ligand 1 in mice was detected by immunohistochemistry, flow cytometry and western blot anatysis. The expression of programmed cell death 1 ligand 1 in the spinal cord and splenocytes of mice was significantly increased compared with normal mice. Our findings suggest the involvement of programmed cell death 1 ligand 1 in the pathogenesis of ex- perimental allergic encephalomyelitis and suggest this should be studied in multiple sclerosis.

Construction of Air Quality Evaluation System Based on FCM Algorithm and BP Neural Network

In order to solve the limitations of existing air quality evaluation system, a new air quality evaluation system was established based on FCM, the BP neural network, with the aim to provide scientific bases for the targeted and efficient control of air pollution, formulation of prevention and control strategy, and improvement of living environment. Based on the existing data of 6 air quality indices, the air quality data were reclassified by using FCM algorithm, obtaining the clustering center, which minimized the cost function of non-similar index. Then, the reclassified 6 classes of data were proceeded with BP neural network training and simulation, so as to achieve the purpose of identification, thereby forming a new air quality evaluation system.

染色体外癌基因扩增特点与肿瘤发生发展

染色体外DNA(extrachromosomal DNA,ecDNA)是位于染色体外的小片段环状DNA,具有自我复制功能。已有研究证明癌基因在ecDNA上被扩增是肿瘤细胞中的常见现象,并且具有一些值得研究的特征,如与患者的不良预后相关。多种染色体事件参与ecDNA形成,且它的扩增能直接使染色体外癌基因DNA拷贝数增加,加速肿瘤产生和发展。并且,亲代ecDNA细胞不均等传递到子代的分离方式,不仅增加肿瘤异质性,同时增强肿瘤对环境的适应和对治疗的反应能力。本文对ecDNA在肿瘤细胞中的研究现状及其潜在意义作一综述。

Influences of uncertainties to the generation feasible region for medium- and long-term electricity transaction

For the implementation of power market in China,medium-and Iong-term security checks are essential for bilateral transactions,of which the electricity quantity that constitutes the generation feasible region(GFR)is the target.However,uncertainties from load forecasting errors and transmission contingencies are threats to medium-and Iong-term electricity tradi ng in terms of their in flue nces on the GFR.In this paper,we prese nt a graphic distortio n pattern in a typical threegenerator system using the Monte Carlo method and projection theory based on security constrained economic dispatch.The underlying potential risk to GFR from uncertainties is clearly visualized,and their impact characteristics are discussed.A case study on detailed GFR distortion was included to dem on strate the effectiveness of this visualization model.The result implies that a small uncertainty could distort the GFR to a remarkable extent and that different line-contingency precipitates disparate the GFR distortion patterns,thereby eliciting great emphasis on load forecasting and line reliability in electricity transacti ons.

A CRISPR activation screen identifies genes that enhance SARS-CoV-2 infection

Dear Editor,Identifying the host factors that are utilized for virus infection and mapping their cell-type expression profile can help to understand the viral tissue/organ tropism and pathogenesis.Much effort has been devoted to the identification of SARS-CoV-2 infection-dependent host factors.CRISPR-based activation(Konermann et al.,2015).

香蕉假茎生物炭对根际土壤细菌丰度和群落结构的影响

【目的】将香蕉假茎生物炭施加到土壤,探讨香蕉假茎生物炭对香蕉根际土壤微生物的影响。【方法】以香蕉假茎生物炭(BPB) 0、1%、2%、3%的质量比与土壤均匀混合。盆栽培养3个月后分离香蕉根际土壤。采用16S rRNA高通量测序技术对根际土壤细菌群落结构和丰度进行表征。【结果】提高BPB施用量可增加土壤有机质、有效钾、有效磷含量,提高土壤pH值,但降低有效氮浓度。在1%BPB样品中获得2278个OTUs,其显示细菌群落中的最大多样性。施加3%的BPB处理土壤,拟杆菌门、疣微菌门和厚壁菌门的相对丰度显著增加;放线菌门、酸杆菌门、芽单胞菌门明显减少。主成分分析发现,1%BPB和2% BPB处理的样本之间土壤细菌群落相似。【结论】施加不同比例BPB改变了根际土壤中细菌丰度和群落结构,且高比例添加改变更加明显。

外源酚酸诱导枳菌根共生相关基因筛选

【目的】基于丛枝菌根(AM)真菌改变柑橘酚类现象,筛选外源酚酸诱导菌根共生差异基因,分析酚相关基因功能。【方法】以枳(Poncirus trifoliate L.)接种AM真菌,并施加外源酚酸,采用随机引物扩增,获得差异表达片段;继而克隆酚相关基因并进行生物信息学分析。【结果】试验采用20条随机引物和3条锚定引物扩增cDNA,共获得了154条差异显示的表达片段;对其中16条Northern杂交显示阳性的片段测序与比对,发现9条有相关功能注释,参与环境因子及内源信号的识别,调节共生体的形成;DD-11基因只有在外源酚酸添加和接种AM真菌的根系中表达,该片段cDNA全长序列长度为1382 bp,编码454个氨基酸,分子式为C2210H3427N603O657S31,其理论等电点和相对分子量分别为7.81和49950.03;磷酸化分析发现,该蛋白有22个丝氨酸残基、14个苏氨酸残基及7个酪氨酸残基可能成为蛋白激酶磷酸化位点。通过PredictProtein服务器对DD-11蛋白质的二级结构进行分析,该蛋白含有α螺旋22%、无规则卷曲58%、延伸链20%,不含有β折叠结构。【结论】本试验获得菌根共生过程酚相关基因,其功能与植物内源信号识别密切相关,为探讨酚类在菌根共生过程中的分子机制提供了新的视角。

航天搭载对武夷名丛相关生理及生长特性的影响

以神舟八号飞船搭载的6种武夷名丛种子SP1代株系为材料,探讨航天搭载对武夷名丛SP1代株系叶片形态、光合色素含量、叶绿素荧光参数、可溶性糖和蛋白质含量以及茶叶品质成分含量的影响,分析航天搭载后武夷名丛生长和生理特性的变化,从中筛选优良突变株。结果表明,航天搭载后6个武夷名丛SP1代植株的叶长、叶宽、节间长度和叶面积均发生变化,其中,雀舌、肉桂和奇丹的叶面积显著增加;航天搭载显著提高雀舌、奇丹、肉桂和金毛猴的叶绿素及类胡萝卜素含量,瞬时叶绿素荧光(Ft)和光量子效率(Qy)也有所增加,这有利于提高光合效率;武夷名丛航天搭载后表现出可溶性糖含量增加而蛋白质含量减少,氨基酸和茶多酚含量下降,儿茶素和咖啡碱含量上升。综合各项指标,航天搭载后6个武夷名丛中雀舌可以作为有益变异株系加以选育。

Efficient photocatalytic hydrogen evolution coupled with benzaldehyde production over 0D Cd_(0.5)Zn_(0.5)S/2D Ti_(3)C2 Schottky heterojunction

Converting water into hydrogen fuel and oxidizing benzyl alcohol to benzaldehyde simultaneously under visible light illumination is of great significance,but the fast recombination of photogenerated carriers in photocatalysts seriously decreases the conversion efficiency.Herein,a novel dual-functional 0D Cd_(0.5)Zn_(0.5)S/2D Ti_(3)C2 hybrid was fabricated by a solvothermally in-situ generated assembling method.The Cd_(0.5)Zn_(0.5)S nano-spheres with a fluffy surface completely and uniformly covered the ultrathin Ti_(3)C2 nanosheets,leading to the increased Schottky barrier(SB)sites due to a large contact area,which could accelerate the electron–hole separation and improve the light utilization.The optimized Cd_(0.5)Zn_(0.5)S/Ti_(3)C2 hybrid simultaneously presents a hydrogen evolution rate of 5.3 mmol/(g·h)and a benzaldehyde production rate of 29.3 mmol/(g·h),which are~3.2 and 2 times higher than those of pristine Cd_(0.5)Zn_(0.5)S,respectively.Both the multiple experimental measurements and the density functional theory(DFT)calculations further demonstrate the tight connection between Cd_(0.5)Zn_(0.5)S and Ti_(3)C2,formation of Schottky junction,and efficient photogenerated electron–hole separation.This paper suggests a dual-functional composite catalyst for photocatalytic hydrogen evolution and benzaldehyde production,and provides a new strategy for preventing the photogenerated electrons and holes from recombining by constructing a 0D/2D heterojunction with increased SB sites.

Active ammonia-oxidizing bacteria and archaea in wastewater treatment systems

Ammonia-oxidizing bacteria(AOB)and archaea(AOA)are two microbial groups mediating nitrification,yet little is presently known about their abundances and community structures at the transcriptional level in wastewater treatment systems(WWTSs).This is a significant issue,as the numerical abundance of AOA or AOB at the gene level may not necessarily represent their functional role in ammonia oxidation.Using amo A genes as molecular markers,this study investigated the transcriptional abundance and community structure of active AOA and AOB in 14 WWTSs.Quantitative PCR results indicated that the transcriptional abundances of AOB amo A(averaged:1.6×10^(8)copies g^(-1)dry sludge)were higher than those of AOA(averaged:3.4×10^(7)copies g^(-1)dry sludge)in all WWTSs despite several higher abundances of AOA amo A at the gene level.Moreover,phylogenetic analysis demonstrated that Nitrosomonas europaea and unknown clusters accounted for 37.66%and 49.96%of the total AOB amo A transcripts,respectively,suggesting their dominant role in driving ammonia oxidation.Meanwhile,AOA amo A transcripts were only successfully retrieved from 3 samples,and the Nitrosospaera sister cluster dominated,accounting for 83.46%.Finally,the substrate utilization kinetics of different AOA and AOB species might play a fundamental role in shaping their niche differentiation,community composition,and functional activity.This study provides a basis for evaluating the relative contributions of ammonia-oxidizing microorganisms(AOMs)to nitrogen conversions in WWTSs.

Electrospun Cu-doped In_(2)O_(3) hollow nanofibers with enhanced H2S gas sensing performance

One-dimensional nanofibers can be transformed into hollow structures with larger specific surface area, which contributes to the enhancement of gas adsorption. We firstly fabricated Cu-doped In_(2)O_(3) (Cu-In_(2)O_(3)) hollow nanofibers by electrospinning and calcination for detecting H2S. The experimental results show that the Cu doping concentration besides the operating temperature, gas concentration, and relative humidity can greatly affect the H2S sensing performance of the In_(2)O_(3)-based sensors. In particular, the responses of 6%Cu-In_(2)O_(3) hollow nanofibers are 350.7 and 4201.5 to 50 and 100 ppm H2S at 250 ℃, which are over 20 and 140 times higher than those of pristine In_(2)O_(3) hollow nanofibers, respectively. Moreover, the corresponding sensor exhibits excellent selectivity and good reproducibility towards H2S, and the response of 6%Cu-In_(2)O_(3) is still 1.5 to 1 ppm H2S. Finally, the gas sensing mechanism of Cu-In_(2)O_(3) hollow nanofibers is thoroughly discussed, along with the assistance of first-principles calculations. Both the formation of hollow structure and Cu doping contribute to provide more active sites, and meanwhile a little CuO can form p–n heterojunctions with In_(2)O_(3) and react with H2S, resulting in significant improvement of gas sensing performance. The Cu-In_(2)O_(3) hollow nanofibers can be tailored for practical application to selectively detect H2S at lower concentrations.