Sequential Growth of Cs_(3)Bi_(2)I_(9)/BiVO_(4)Direct Z-Scheme Heterojunction for Visible-Light-Driven Photocatalytic CO_(2)Reduction

The high exciton binding energy and lack of a positive oxidation band potential restrict the photocatalytic CO_(2)reduction efficiency of lead-free Bi-based halide perovskites Cs_(3)Bi_(2)X_(9)(X=Br,I).In this study,a sequential growth method is presented to prepare a visible-light-driven(λ>420 nm)Z-scheme heterojunction photocatalyst composed of BiVO_(4)nanocrystals decorated on a Cs_(3)Bi_(2)I_(9)nanosheet for photocatalytic CO_(2)reduction coupled with water oxidation.The Cs_(3)Bi_(2)I_(9)/BiVO_(4)Z-scheme heterojunction photocatalyst is stable in the gas-solid photocatalytic CO_(2)reduction system,demonstrating a high visible-light-driven photocatalytic CO_(2)-to-CO production rate of 17.5μmol/(g·h),which is approximately three times that of pristine Cs_(3)Bi_(2)I_(9).The high efficiency of the Cs_(3)Bi_(2)I_(9)/BiVO_(4)heterojunction was attributed to the improved charge separation in Cs_(3)Bi_(2)I_(9).Moreover,the Z-scheme charge-transfer pathway preserves the negative reduction potential of Cs_(3)Bi_(2)I_(9)and the positive oxidation potential of BiVO_()4.This study off ers solid evidence of constructing Z-scheme heterojunctions to improve the photocatalytic performance of lead-free halide perovskites and would inspire more ideas for developing leadfree halide perovskite photocatalysts.

Exploratory Application of X-ray Photography in the Diagnosis of Poultry Fatty Liver

[Objectives]This study was conducted to explore the application value of X ray in the diagnosis of poultry fatty liver.[Methods]Serum biochemical tests were performed on laying hens with suspected fatty liver.The X-ray liver images of the left lateral position were observed.And the liver traits were observed by anatomy.[Results]The increase in liver space occupying lesion observed by X-ray photography was consistent with the increase in liver volume observed by anatomy.The biochemical test showed slight liver function abnormalities.[Conclusions]X-ray examination can be used for the auxiliary diagnosis of poultry fatty liver.

Effects of Probiotics and Enzyme Preparation on Cholesterol, Triglyceride and Serum ALT and POD in Egg Yolks

[Objectives]This study was conducted to investigate the effects of probiotics and enzyme preparation on cholesterol,triglyceride and serum alanine aminotransferase (ALT) and peroxidase (POD) in egg yolks.[Methods]Forty eight 450-day-old Hyline brown hens were randomly divided into 4 groups with 3 replicates in each group and 4 individuals in each replicate.Group 1 as the control check (CK) group was fed the basal diet;group 2 was fed the basal diet with the addition of 150 g/t of probiotics;group 3 was the basal diet +200 g/t lipase group;and group 4 was fed the basal diet with the addition of 150 g/t of probiotics and 200 g/t of lipase.The preliminary trial period was 10 d,and the trial period was 30 d.[Results]The contents of cholesterol and triglyceride in the egg yolks of the test groups supplemented with the probiotics and enzyme preparation were higher than those of the CK.On the 14^th day of treatment,the cholesterol contents in the egg yolks of group 2 and group 4 were significantly higher than that of group 1 ( P <0.05).On the 28^th day of treatment,the contents of cholesterol and triglyceride in the egg yolks of the three test groups were significantly higher than those in group 1 ( P <0.05).There were no significant differences in serum ALT and POD between various groups ( P >0.05).[Conclusions]The addition of probiotics and enzyme preparations to the feed of laying hens can increase the contents of cholesterol and triglyceride in egg yolks,without significantly affecting serum ALT and POD.

Correlation Between Cholesterol Content in Egg Yolks and Laying Rate

[Objectives]This study was conducted to investigate the relationship between cholesterol content in egg yolks and laying rate of laying hens.[Methods]Forty eight 450-day-old Hyline brown hens with uniform weight were randomly divided into 4 groups with 3 replicates in each group and 4 individuals in each replicate.Group 1 as the control check group(CK)was fed the basal diet;group 2 was fed the basal diet with the addition of 150 g/t of probiotics;group 3 was the basal diet+200 g/t lipase group;and group 4 was fed the basal diet with the addition of 150 g/t of probiotics and 200 g/t of lipase.The preliminary trial period was 10 d,and the experimental period was 30 d.[Results]The cholesterol content in the egg yolks of each test group was higher than that of the control group at 14 and 28 d after the drug administration.The laying rate of each test group began to increase at 14 d after the drug administration;and the laying rate of each test group increased significantly 28 d after the drug administration.It indicated that with the increase of cholesterol in egg yolks,the laying rate of laying hens increased significantly.[Conclusions]This study provides a certain experimental basis for culture production of laying hens.

Highly effective self-assembled porphyrin MOCs nanomaterials for enhanced photodynamic therapy in tumor

Porphyrins and their derivatives are excellent photosensitizers in photodynamic therapy(PDT).The modification of porphyrin molecules into metal-organic cages(MOCs)is a viable strategy to improve their bioavailability.In this work,MOC C66 based on porphyrin was synthesised by a one-pot self-assembly method.The three-dimensional structure of the metal-organic cage ameliorated the aggregation and selfquenching of porphyrins and increased the molar absorption coefficient in the visible light region,which enhanced the reactive oxygen species(ROS)yield of porphyrins and effectively improved the efficiency of photodynamic therapy.ROS generation ability tests in solution confirmed the improved reactive oxygen capacity of the cage,which showed greater phototoxicity to HeLa and MCF-7 cells in vitro,suggesting a new strategy for future modifications of the simple synthesis of porphyrins as photosensitizers.

Recent progression and future perspectives in cotton genomic breeding

Upland cotton is an important global cash crop for its long seed fibers and high edible oil and protein content.Progress in cotton genomics promotes the advancement of cotton genetics,evolutionary studies,functional genetics,and breeding,and has ushered cotton research and breeding into a new era.Here,we summarize high-impact genomics studies for cotton from the last 10 years.The diploid Gossypium arboreum and allotetraploid Gossypium hirsutum are the main focus of most genetic and genomic studies.We next review recent progress in cotton molecular biology and genetics,which builds on cotton genome sequencing efforts,population studies,and functional genomics,to provide insights into the mechanisms shaping abiotic and biotic stress tolerance,plant architecture,seed oil content,and fiber development.We also suggest the application of novel technologies and strategies to facilitate genome-based crop breeding.Explosive growth in the amount of novel genomic data,identified genes,gene modules,and pathways is now enabling researchers to utilize multidisciplinary genomics-enabled breeding strategies to cultivate"super cotton",synergistically improving multiple traits.These strategies must rise to meet urgent demands for a sustainable cotton industry.

Photoredox-neutral ring-opening pyridylation of cyclic oximes via phosphoranyl radical-mediated N-O/C-C bond cleavages and sequential radical-radical coupling

A novel photoredox-neutral ring-opening pyridylation of non-prefunctionalized cyclic oximes has been accomplished through phosphoranyl radical-mediated N-O/C-C bond cleavages followed by radicalradical coupling.This mild acid-,base-,and oxidant-free protocol provides highly site-selective and efficient access to distally pyridylated alkylnitriles,which could be scale-up synthesized and readily converted into skeletally diverse compounds.Notably,the oxidized ground-state photocatalyst generated via the SET oxidation of the highly reducing excited-state photocatalyst by cyanopyridines might initiate the following phosphoranyl radical-mediated deoxygenative process.

国际基因工程机器大赛对本科生科研教育的启示

近年来,国际基因工程机器大赛(International genetically engineered machine,iGEM,简称iGEM大赛)在全球迅猛发展。仅2017年iGEM大赛全球注册队伍就达到了史无前例的313支,中国地区有98支iGEM团队报名参赛并取得了优异成绩。与国内已有的诸多大学生创新项目、科研培养项目不同,iGEM的组织模式是以学生为主体的研究型学习。该模式取得了丰富的教育效果,体现了新的教育理念,对于我国高校组织本科生课外科研训练有较大的借鉴意义。文中以北京大学参加iGEM大赛为线索,介绍国际基因工程机器大赛(iGEM)的背景和基本情况并以一个参赛周期为序再现北京大学iGEM团队组织和参赛的主要过程。通过与其他本科生科研训练的组织模式进行比较,探讨iGEM对本科生科研训练意义,并总结iGEM的组织经验和对本科生科研能力培养以及组织本科生科研学术竞赛的启示,希望能为国内高校的iGEM活动组织以及本科教育改革提供借鉴。

Temporal variations and source apportionment of volatile organic compounds at an urban site in Shijiazhuang, China

Shijiazhuang,the city with the worst air quality in China,is suffering from severe ozone pollution in summer.As the key precursors of ozone generation,it is necessary to control the Volatile Organic Compounds(VOCs)pollution.To have a better understanding of the pollution status and source contribution,the concentrations of 117 ambient VOCs were analyzed from April to August 2018 in an urban site in Shijiazhuang.Results showed that the monthly average concentration of total VOCs was 66.27 ppbv,in which,the oxygenated VOCs(37.89%),alkanes(33.89%),and halogenated hydrocarbons(13.31%)were the main composite on.Eight major sources were identified using Positive Matrix Factorization modeling with an accurate VOCs emission inventory as inter-complementary methods revealed that the petrochemical industry(26.24%),other industrial sources(15.19%),and traffic source(12.24%)were the major sources for ambient VOCs in Shijiazhuang.The spatial distributions of major industrial activities emissions were identified by using geographic information statistics system,which illustrated the VOCs was mainly from the north and southeast of Shijiazhuang.The inverse trajectory analysis using Hybrid Single-Particle Lagrangian Integrated Trajectory(HYSPLIT)and Potential Source Contribution Function(PSCF)clearly demonstrated the features of pollutant transport to Shijiazhuang.These findings can provide references for local governments regarding control strategies to reduce VOCs emissions.

基于重组酶和终止子的状态调控开关设计

合成生物学研究常用基因开关来调控细胞的状态以实现相应功能。已有的基因开关往往需要持续的输入信号来维持特定的开关状态,开关功能的维持需要持续消耗能量,并且对扰动较为敏感。文中利用了位点特异性重组酶的倒位效应反转终止子,构建了一种转录层次的状态调控开关,使得脉冲信号即可触发开关状态改变,并在下一次信号来临前稳定维持当前状态。应用自下而上的工程化思想,文中先后对重组酶和终止子进行了单独表征和组合表征,探究了二者之间的相互影响,筛选出了相互兼容的组合,成功实现了细胞的单次、二次状态切换。最后,此开关成功地被用于构建生物七段译码器,显示出了其较好的应用潜力。

The calcium-dependent protein kinase ZmCDPK7 functions in heat-stress tolerance in maize

Global warming poses a serious threat to crops.Calcium-dependent protein kinases(CDPKs)/CPKs play vital roles in plant stress responses,but their exact roles in plant thermotolerance remains elusive.Here,we explored the roles of heat-induced ZmCDPK7 in thermotolerance in maize.ZmCDPK7-overexpressing maize plants displayed higher thermotolerance,photosynthetic rates,and antioxidant enzyme activity but lower H2 O2 and malondialdehyde(MDA)contents than wild-type plants under heat stress.ZmCDPK7-knockdown plants displayed the opposite patterns.ZmCDPK7 is attached to the plasma membrane but can translocate to the cytosol under heat stress.ZmCDPK7 interacts with the small heat shock protein sHSP17.4,phosphorylates sHSP17.4 at Ser-44 and the respiratory burst oxidase homolog RBOHB at Ser-99,and up regulates their expression.Site-directed mutagenesis of sHSP17.4 to generate a Ser-44-Ala substitution reduced ZmCDPK7’s enhancement of catalase activity but enhanced ZmCDPK7’s suppression of MDA accumulation in heat-stressed maize protoplasts.sHSP17.4,ZmCDPK7,and RBOHB were less strongly upregulated in response to heat stress in the abscisic acid-deficient mutant vp5 versus the wild type.Pretreatment with an RBOH inhibitor suppressed sHSP17.4 and ZmCDPK7 expression.Therefore,abscisic acid-induced ZmCDPK7 functions both upstream and downstream of RBOH and participates in thermotolerance in maize by mediating the phosphorylation of sHSP17.4,which might be essential for its chaperone function.

Tribological properties of onion like fullerenes and NiFe2O4 nanocomposites in reciprocating motion

A novel way for a compressor to improve its coefficient of performance and enhance its reliability by employing nano-refrigeration lubricant oil was proposed. Onion like fullerenes (OLFs) and NiFe2O4 nano-composites, modified by Span 80, were dispersed in refrigeration oil KFR22 by solid grinding (SG). Morphologies of NiFe2O4 nano-composites were characterized by using transmission electron microscope (TEM). The tribological properties as a refrigeration lubricants additive were investigated using SRV (II), a multi-functional reciprocating friction and wear tester. The results showed that the friction coefficient was decreased from 0.15 to 0.04.

Performance of rolling piston type rotary compressor using fullerenes(C70)and NiFe204 nanocomposites as lubricants additives

A novel way for a compressor to improve its coefficient of performance was proposed in this paper.Fullerenes(C70)and NiFe2O4 nanocomposites were modified by span 80 and dispersed in refrigeration oil by solid grinding(SG).Besides,the tribological properties of the nanocomposites were investigated using a four ball friction tester.The results show that when the mass concentration of fullerenes nanocomposite is higher than 60 ppm and the concentration of nano-oil is 2 g/L,the friction coefficient decreases from 0.13 to 0.06 which means the wear is reduced.The coefficient of performance of the compressor under the air conditioning test condition can be raised by 1.23%.