Cu单原子与氧空位协同作用增强电催化CO_(2)还原中C_(2)液相产物活性

铜(Cu)因具有很好的CO结合能而被认为是目前可将CO_(2)电还原为乙酸、乙醇等多碳产物的重要催化材料.虽然Cu基催化剂表现出较好的还原活性,但产物的低选择性制约了其大规模商业化应用.因此,迫切需要开发高选择性、低成本的Cu基催化剂.研究表明,具有分散Cu-N活性位点的Cu基单原子催化剂是理想的CO_(2)电化学还原反应(CO_(2)RR)催化剂,但仍然存在着与反应关键中间体结合能较高的难题.当前研究多聚焦在诱导单原子的电子配位环境或催化剂的载体结构缺陷,关于二者之间的协同作用研究较少.本文通过简单的水热法与氢溢流策略制备了Cu单原子负载的高氧空位UIO66催化剂.X射线光电子能谱和高角度环形暗场扫描透射电子显微镜结果表明,Cu物种以高度分散的单原子形式存在.采用X射线吸收精细结构谱和X射线光电子能谱(XPS)的N 1s能级研究了Cu原子的电子和配位结构,证明了Cu-N键的存在.此外,相较于未经过H_(2)二次处理的Cu SAs/UIO材料和未负载Cu单原子的UIO-H_(2)材料,Cu SAs/UIO-H_(2)样品在电子顺磁光谱中观察到更加明显的氧空位信号,XPS谱的O 1s能级、傅里叶变换红外光谱(FTIR)表征结果均表明大量氧空位的存在,从而证明成功制备了Cu单原子负载的高氧空位UIO66催化剂(Cu SAs/UIO-H_(2)).反应测试结果表明,高氧空位掺杂UIO66耦合Cu-N位点后表现较好的CO_(2)RR性能,在-0.66 V(vs.RHE)的低电位下对于C_(2)液相产物实现了58.62%的法拉第效率,高于大多数已报道的Cu基催化剂结果.其中,乙醇的法拉第效率达46.28%,是UIO66-NH_(2),Cu SAs/UIO的9.61倍和2.78倍.经过12 h的稳定性测试后,乙醇仍然能够维持46%的法拉第效率,且反应后催化剂形貌和晶体结构几乎未发生改变,表明催化剂具有较高的稳定性和实际应用前景.为进一步分析反应机理,利用原位FTIR技术检测*CHO,*OCCHO和*CH_(3)CH_(2)O等重要反应中间体的形成,从而确定CO_(2)RR产乙醇的反应路径,并通过密度泛函理论分析了溶剂化效应的影响,验证了Cu单原子与大量氧空位协同作用下易于诱导关键中间体*HCCOH的生成,提出了大量氧空位的存在降低了CO_(2)RR产乙醇的反应能垒的理念,并分析计算CO_(2)RR产乙醇和产乙烯两条路径的能垒,讨论Cu SAs/UIO-H_(2)催化剂具有高乙醇选择性的原因.综上所述,Cu基单原子与氧空位协同是提高电催化剂CO_(2)RR活性的有效策略,具有良好的应用前景.本文为在原子尺度上设计高性能Cu单原子催化剂提供了一种新思路.

Liquid-liquid phase separation in DNA double-strand break repair

DNA repair factors function through spatiotemporal condensation and dissolution at DNA double-strand breaks(DSBs).Recent advances have indicated that some DSB repair factors undergo liquid-liquid phase separation(LLPS)and show droplet-like properties,as well as dynamic material exchange.Importantly,LLPS regulates various biological processes,and aberrant LLPS is involved in the pathologic progression of various diseases.

扶余油田西5-8区块井网开发方式的优化

扶余油田西5-8区块从1962年开发至今经历了溶解气驱、注水开发和3次较大调整，到2012年10月油井单向受效多，多向受效井少，平均单井日产油0．6t，含水率达到95．8％；注水开发的中后期，油层剩余油分布复杂，后期注水开发效果差、含水率高、采出程度低。单砂体精细刻画为理论依据，了解油层剩余油分布情况，从单、双注水井开发井网方式、不同井网的水井加密方式以及水井射孔方式进行优化选择，并且降低新、老井注水强度，实施低强度注水政策，可使得油井受效方向发生变化，单砂体控制状况得到改善从而提高注水开发效果。

Enhancement of spatial resolution of ghost imaging via localizing and thresholding

In ghost imaging, an illumination light is split into test and reference beams which pass through two different optical systems respectively and an image is constructed with the second-order correlation between the two light beams. Since both light beams are diffracted when passing through the optical systems, the spatial resolution of ghost imaging is in general lower than that of a corresponding conventional imaging system. When Gaussian-shaped light spots are used to illuminate an object, randomly scanning across the object plane, in the ghost imaging scheme, we show th√at by localizing central positions of the spots of the reference light beam, the resolution can be increased by a factor of 2^(1/2) same as that of the corresponding conventional imaging system. We also find that the resolution can be further enhanced by setting an appropriate threshold to the bucket measurement of ghost imaging.

Antagonistic Effects of Sphingomonas and Pseudomonas aeruginosa on 4 Kinds of Pathogenic Bacteria of Ginseng

[Objectives]To explore effective biocontrol methods for diseases in the process of ginseng cultivation,and develop an efficient and environmentally friendly biocontrol agent.[Methods]In this study,2 strains were isolated from biogas slurry,and Cylindrocarpon destructans(XF),Fusarium solani(GF),Botrytis cinerea Pers(HM)and Alternaria panax Whetz(HB)were used as test materials.The strains were isolated and identified by dilution plate method,16S rDNA sequence identification method,confrontation culture method,filter paper method and ultraviolet spectrophotometer method,and the bacteriostatic activity and bacteriostatic rate were tested.[Results]Strain 15(Sphingomonas)and strain 19(Pseudomonas aeruginosa)were screened out through identification and analysis,and they grew stably within 8-10 d.The bacteriostatic rates of strain 15 against A.panax and B.cinerea were 47.37%and 43.40%,respectively,and the bacteriostatic rates of strain 19 against A.panax and B.cinerea were 62.30%and 63.27%,respectively.The bacteriostatic activity of the extract of strain 19 increased with the increase of OD_(600) value,and the bacteriostatic effect was optimal when the OD_(600) value was in the range of 0.8-1.0,up to 70%,so it had a strong biocontrol potential.[Conclusions]This experiment provides convenience for more effective inoculation,establishes a fast,simple and accurate method for the determination of the best bacteriostatic rate of P.aeruginosa culture solution to HM,and lays a foundation for large-scale culture of P.aeruginosa culture solution.Besides,it is expected to provide a theoretical basis for the efficient control of ginseng B.cinerea in field production,use it for the prevention and control of ginseng shoot diseases,and provide a reference for the efficient and diverse development of biocontrol agents for ginseng shoot diseases.

Effect of Limited Enzymatic Hydrolysis on Structure Characterization of Glycinin

[ Objective] This study aimed to characterize the structure of soybean glycinin affected by limited enzymatic hydrolysis. [ Method ] The glycinin was limitedly hydrolyzed by alkaline protease; then the SDS-polyacrylamide gel electrophoresis （SDS-PAGE）, scanning electron microscopy （SEM）, Fourier transform infrared spectroscopy （fTIR） and other means were performed to characterize the glyeinin structure changing during the hydrolysis process. [ Result] SDS-PAGE analysis showed that the subunit contem of glycinin significantly decreased after hydrolysis, and acidic subunits were more susceptible to hydrolysis than alkaline subunits. The scanning electron microscopy revealed that the structure of glycinin powder changed greatly after hydrolysis. The I^TIR results showed that the propor- tions of all conformations of glycinin changed greatly during hydrolysis process. In addition, the protein hydrophobicity and sulfhydryl content were also significantly influenced by hydrolysis. [ Conclusion] The enzymatic hydrolysis greatly changed the conformations of glyeinin, and the change was dependent on the degree of hy- drolysis.

A Continuous Approach to Binary Quadratic Problems

This paper presents a continuous method for solving binary quadratic programming problems. First, the original problem is converted into an equivalent continuous optimization problem by using NCP (Nonlinear Complementarity Problem) function, which can be further carry on the smoothing processing by aggregate function. Therefore, the original combinatorial optimization problem could be transformed into a general differential nonlinear programming problem, which can be solved by mature optimization technique. Through some numerical experiments, the applicability, robustness, and solution quality of the approach are proved, which could be applied to large scale problems.

An Application of Sinc Sum Function in Hilbert Transformer

An application of the sinc sum function in Hilbert transformer (HT) is studied. The expression of the frequency re- sponse of HT is expressed with sinc sum functions. Some properties of sub-amplitude response of HT are proved by using the properties of the sinc sum function. A general HT formula is obtained theoretically and it contains a general window function. As an example three new window functions are obtained. Different from the existing window func- tions obtained from lowpass filters, these window functions are obtained directly from HT. Comparisons show that new windows are better than the Hanning, Hamming, Blackman and Kaiser windows in terms of HT performances.

Boosting Multi-modal Ocular Recognition via Spatial Feature Reconstruction and Unsupervised Image Quality Estimation

In the daily application of an iris-recognition-at-a-distance(IAAD)system,many ocular images of low quality are acquired.As the iris part of these images is often not qualified for the recognition requirements,the more accessible periocular regions are a good complement for recognition.To further boost the performance of IAAD systems,a novel end-to-end framework for multi-modal ocular recognition is proposed.The proposed framework mainly consists of iris/periocular feature extraction and matching,unsupervised iris quality assessment,and a score-level adaptive weighted fusion strategy.First,ocular feature reconstruction(OFR)is proposed to sparsely reconstruct each probe image by high-quality gallery images based on proper feature maps.Next,a brand new unsupervised iris quality assessment method based on random multiscale embedding robustness is proposed.Different from the existing iris quality assess-ment methods,the quality of an iris image is measured by its robustness in the embedding space.At last,the fusion strategy exploits the iris quality score as the fusion weight to coalesce the complementary information from the iris and periocular regions.Extensive experi-mental results on ocular datasets prove that the proposed method is obviously better than unimodal biometrics,and the fusion strategy can significantly improve therecognition performance.

Applying heteroatom co-doped carbon nanotube for manifesting high performance in the electrochemical reduction of aqueous nitrogen oxide by gold nanoparticles

Electrochemical NO-to-NH_(3) under ambient conditions could be a viable alternative having advantages in terms of energy consumption and exhaust gas recycling of NO,replacing a traditional ammonia synthesis method of the Haber–Bosch process.In synthesizing boron(B-)and nitrogen(N-)co-doped carbon nanotube(CNT)based gold(Au)catalysts,B-dopants elevate the conductivity of carbon nanotube by sp2 hybridization on graphene and implant B–N domains within the graphene layer,and result in facilitating the embedding amount of Au accompanied by high dispersibility with low particle size.Theoretical density functional theory(DFT)calculations elucidate that the electron cloud transmitted from B-dopant to the active site of Au induces the Lewis acidic site,and the O-distal pathway occurs following a spontaneous reaction.Increment of the electron-deficient B-doping area accompanied by N-defects and B–O edges retains the major valence state of Au as Au^(δ+),and suppresses hydrogen evolution reaction(HER)by repulsing the hindrance of H*.This record exhibits the highest faradaic efficiency(FE)of 94.7%,and NH_(3) yield rate of 1877.4μg·h^(-1)·mg_(cat)^(-1),which is the optimal yield over energy consumption in the field of the ambient reduction of aqueous NO.

CASIA-Iris-Africa:A Large-scale African Iris Image Database

Iris biometrics is a phenotypic biometric trait that has proven to be agnostic to human natural physiological changes.Research on iris biometrics has progressed tremendously,partly due to publicly available iris databases.Various databases have been available to researchers that address pressing iris biometric challenges such as constraint,mobile,multispectral,synthetics,long-distance,contact lenses,liveness detection,etc.However,these databases mostly contain subjects of Caucasian and Asian docents with very few Africans.Despite many investigative studies on racial bias in face biometrics,very few studies on iris biometrics have been published,mainly due to the lack of racially diverse large-scale databases containing sufficient iris samples of Africans in the public domain.Furthermore,most of these databases contain a relatively small number of subjects and labelled images.This paper proposes a large-scale African database named Chinese Academy of Sciences Institute of Automation(CASIA)-Iris-Africa that can be used as a complementary database for the iris recognition community to mediate the effect of racial biases on Africans.The database contains 28717 images of 1023 African subjects(2046 iris classes)with age,gender,and ethnicity attributes that can be useful in demographically sensitive studies of Africans.Sets of specific application protocols are incorporated with the database to ensure the database’s variability and scalability.Performance results of some open-source state-of-the-art(SOTA)algorithms on the database are presented,which will serve as baseline performances.The relatively poor performances of the baseline algorithms on the proposed database despite better performance on other databases prove that racial biases exist in these iris recognition algorithms.

Rice FLOURY ENDOSPERM22, encoding a pentatricopeptide repeat protein, is involved in both mitochondrial RNA splicing and editing and is crucial for endosperm development

Most of the reported P-type pentatricopeptide repeat(PPR) proteins play roles in organelle RNA stabilization and splicing. However, P-type PPRs involved in both RNA splicing and editing have rarely been reported, and their underlying mechanism remains largely unknown. Here, we report a rice floury endosperm22(flo22) mutant with delayed amyloplast development in endosperm cells. Map-based cloning and complementation tests demonstrated that FLO22 encodes a mitochondrion-localized P-type PPR protein.Mutation of FLO22 resulting in defective transsplicing of mitochondrial nad1 intron 1 and perhaps causing instability of mature transcripts affected assembly and activity of complex Ⅰ, and mitochondrial morphology and function. RNA-seq analysis showed that expression levels of many genes involved in starch and sucrose metabolism were significantly down-regulated in the flo22mutant compared with the wild type, whereas genes related to oxidative phosphorylation and the tricarboxylic acid cycle were significantly upregulated. In addition to involvement in splicing as a P-type PPR protein, we found that FLO22 interacted with DYW3, a DYW-type PPR protein, and they may function synergistically in mitochondrial RNA editing. The present work indicated that FLO22 plays an important role in endosperm development and plant growth by participating in nad1 maturation and multi-site editing of mitochondrial messager RNA.

Pressure-induced ferroelectric and anti-ferroelectric phase transitions in LaN

In this work,we focus on the structural and electronic properties of lanthanum mono-nitride s under high pressure.Based on firstprinciples calculations and crystal structure predictions,we identified an anti-ferroelectric orthogonal phase with space group Pbcm.It is predicted to be thermodynamically stable from 20 to 60 GPa,above which the tetragonal phase without the antiferroelectric distortion will substitute it.However,the anti-ferroelectric distortion can be enhancedby reducing the pressure,and a phase transition to a NiAs-type(B8,P63/mmc) structure occurs at about 20 GPa.The calculated double-well potential for La atoms along the c direction in the B8 phase reveals that it should exhibit ferroelectric properties at low temperatures.Enthalpy calculations well confirm their phase transition sequences under high pressure.Electtonic properties calculations suggest that all the newly identified phases are semiconductors and the corresponding structural distortions can increase their bandgaps.When increasing the pressure to 50 GPa,the tetragonal phase undergoes a semiconductor-to-semimetal transition.Taking the spin-orbit coupling into account,the semimetal phase becomes a topological insulator with a small bandgap.Finally,given the similarities between the ionic compounds LaN and BaO,we predict that the most stable phase for BaO at about 25 GPa should also be the anti-ferroelectric orthogonal phase instead of the tetragonal phase.

Tetrapyrrole biosynthesis pathway regulates plastid-to-nucleus signaling by controlling plastid gene expression in plants

Plastid-to-nucleus retrograde signaling coordinates nuclear gene expression with chloroplast developmental status and is essential for the photoautotrophic lifestyle of plants.Previous studies have established that tetrapyrrole biosynthesis(TPB)and plastid gene expression(PGE)play essential roles in plastid retrograde signaling during early chloroplast biogenesis;however,their functional relationship remains unknown.In this study,we generated a series of rice TPB-related gun(genome uncoupled)mutants and systematically analyzed their effects on nuclear and plastid gene expression under normal conditions or when subjected to treatments with norflurazon(NF;a noncompetitive inhibitor of carotenoid biosynthesis)and/or lincomycin(Lin;a specific inhibitor of plastid translation).We show that under NF treatment,expression of plastid-encoded polymerase(PEP)-transcribed genes is significantly reduced in the wild type but is derepressed in the TPB-related gun mutants.We further demonstrate that the derepressed expression of PEPtranscribed genes may be caused by increased expression of the PEP core subunit and nuclear-encoded sigma factors and by elevated copy numbers of plastid genome per haploid genome.In addition,we show that expression of photosynthesis-associated nuclear genes(PhANGs)and PEP-transcribed genes is correlated in the rice TPB-related gun mutants,with or without NF or Lin treatment.A similar correlation between PhANGs and PGE is also observed in the Arabidopsis gun4 and gun5 mutants.Moreover,we show that increased expression of PEP-transcribed plastid genes is necessary for the gun phenotype in NF-treated TPB-related gun mutants.Further,we provide evidence that these TPB-related GUN genes act upstream of GUN1 in the regulation of retrograde signaling.Taken together,our results suggest that the TPB-related GUN genes control retrograde plastid signaling by regulating the PGE-dependent retrograde signaling pathway.

CA19-9时间分辨荧光免疫层析检测方法的建立

本研究旨在建立一种定量检测血清中CA19-9含量的时间分辨荧光免疫层析检测方法。采用双抗体夹心法与荧光免疫层析技术,以羧基荧光微球和NC膜为载体将CA19-9配对抗体进行标记和包被,制备CA19-9检测试纸条。通过标记、包被抗体量对工艺进行优化,并通过线性范围、最低检出限、精密性等性能指标对CA19-9时间分辨荧光层析检测方法进行评价。最终确定20μL荧光微球的标记抗体量为80μg,检测线包被抗体浓度为1.5 mg/mL时,检测时间为15 min,线性范围为12.5–800 U/mL,最低检出限为6.32 U/mL,批内精密性与批间精密性均小于15%,平均回收率为101%,与罗氏电化学发光检测试剂盒平行检测50份临床样本,两者相关系数为0.980 6。初步建立了定量检测血清中CA19-9的荧光免疫层析检测方法,有较好的临床应用前景。

全国产氦液化器的性能调控优化研究及其工程化应用

超导磁体一般工作在液氦温区(–269℃),需要稳定可靠的冷源为其提供保障.为满足未来高能量粒子对撞机所需高场强超导二极磁体研究的测试需求,本文针对自主研制的国内首台全国产氦液化器开展了性能调控优化研究,分别实现了冷箱和液氦杜瓦降温过程的优化控制,节省压缩机功耗分别为12.3%和25.2%,显著提高了氦液化器的经济性.在此基础上,针对用户现场不同运行工况,实现了氦液化器适应变负荷的自动控制调节功能.分析了氦液化器在各负荷状态下的运行能耗;在不考虑液氮消耗的前提下,氦液化器最低能耗为2.4 kW h/L.通过调控优化及实验测试,成功实现了氦液化器与用户端磁体测试平台的联合运行,并通过了全国产氦液化器的长时间运行可靠性测试,满足了磁体测试系统对其低温制冷系统在稳定性和可靠性方面的要求.目前,该氦液化器已累计稳定运行超过两个月,生产液氦超过35000 L,推动首台国产化加速器高场强超导二极磁体取得了12.47 T磁场强度新指标的突破.这是全国产氦液化器首次应用于超导二极磁体测试平台,该工程应用未来可进行进一步推广.

SARS-Co V-2 N蛋白不同片段制备及其在荧光层析中的应用

表达纯化新型冠状病毒核衣壳(N)蛋白不同片段,建立新冠病毒总抗体荧光免疫层析方法并评价不同蛋白片段对该方法的影响。利用生物信息学技术对N蛋白序列进行分析、合成及原核表达、纯化,制备不同N蛋白片段;采用1-乙基-(3-二甲基氨基丙基)碳酰二亚胺(1-(3-Dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride,EDC)法荧光微球偶联抗原建立夹心荧光层析抗体检测方法,并分别进行性能评价。在制备的4个N蛋白片段中优选出全长N蛋白(N419)包被,N412加入0.5mol/L NaCl进行标记作为最优组合;删掉N抗原N端第91–120位氨基酸(N412)可减少87.5%的非特异性干扰;线性范围为0.312–80U/L,最低检出限为0.165U/L,准确度在95%以上。优选配对N蛋白片段建立的新冠病毒总抗体荧光免疫层析检测方法,与广州万孚试纸条对比总符合率为98%,有望用于新型冠状病毒的辅助检测,同时为新冠抗体检测试剂性能的提升提供实验依据和借鉴。

氧化铁纳米材料在肿瘤治疗中的研究进展

氧化铁纳米材料是目前美国食品药品监督管理局(FDA)批准的唯一可运用于临床的无机纳米材料,在磁共振医学影像中发挥着重要的作用.近年来,随着化学技术的蓬勃发展,以化学修饰改造为代表的优化策略在氧化铁纳米颗粒尺寸大小的调控、成分结构的改造以及表面功能化修饰中大量运用,使得生物相容性良好的氧化铁纳米颗粒在医学健康领域,特别是肿瘤治疗方面的运用得到极大的拓展.本文将探讨以氧化铁纳米颗粒为基元的纳米材料在肿瘤治疗领域的研究与发展,分别就当前氧化铁纳米颗粒的制备工艺、氧化铁纳米颗粒的生物学效应功能、氧化铁纳米颗粒在肿瘤治疗,以及肿瘤免疫微环境调节的运用等方面进行了总结.最后,讨论了氧化铁纳米颗粒作为肿瘤药物向临床转化面临的问题,并展望了其未来的发展方向.

Active/passive Q-switching operation of 2 μm Tm,Ho:YAP laser with an acousto-optical Q-switch/MoS_2 saturable absorber mirror

The active/passive Q-switching operation of a 2 μm a-cut Tm,Ho:YAP laser was experimentally demonstrated with an acousto-optical Q–switch∕MoS_2 saturable absorber mirror. The active Q-switch laser was operated for the first time, to the best of our knowledge, with an average output power of 12.3 W and a maximum pulse energy of 10.3 mJ. The passive Q-switch laser was also the first acquired with an average output power of 3.3 W and per pulse energy of 23.31 μJ, and the beam quality factors of M_x^2 = 1.06 and M_y^2 = 1.06 were measured at the average output power of 2 W.

BRITTLE PLANT1 is required for normal cell wall composition and mechanical strength in rice

A series of nucleotide sugar interconversion enzymes(NSEs) generate the activated sugar donors required for biosynthesis of cell wall matrix polysaccharides and glycoproteins. UDPglucose 4-epimerases(UGEs) are NSEs that function in the interconversion of UDP-glucose(UDP-Glc) and UDP-galactose(UDP-Gal). The roles of UDP-glucose 4-epimerases in monocots remain unclear due to redundancy in the pathways. Here, we report a brittle plant(bp1) rice mutant that exhibits brittle leaves and culms at all growth stages. The mutant culms had reduced levels of rhamnogalacturonan I, homogalacturonan, and arabinogalactan proteins.Moreover, the mutant had altered contents of uronic acids, neutral noncellulosic monosaccharides, and cellulose. Map-based cloning demonstrated that OsBP1 encodes a UDPglucose 4-epimerase(OsUGE2), a cytosolic protein. We also show that BP1 can form homoand hetero-protein complexes with other UGE family members and with UDP-galactose transporters 2(OsUGT2) and 3(OsUGT3), which may facilitate the channeling of Gal to polysaccharides and proteoglycans. Our results demonstrate that BP1 participates in regulating the sugar composition and structure of rice cell walls.