Calcium-chelating peptides from rabbit bone collagen:characterization,identification and mechanism elucidation

This study aimed to characterize and identify calcium-chelating peptides from rabbit bone collagen and explore the underlying chelating mechanism.Collagen peptides and calcium were extracted from rabbit bone by instant ejection steam explosion(ICSE)combined with enzymatic hydrolysis,followed by chelation reaction to prepare rabbit bone peptide-calcium chelate(RBCP-Ca).The chelating sites were further analyzed by liquid chromatography-tandem mass(LC-MS/MS)spectrometry while the chelating mechanism and binding modes were investigated.The structural characterization revealed that RBCP successfully chelated with calcium ions.Furthermore,LC-MS/MS analysis indicated that the binding sites included both acidic amino acids(Asp and Glu)and basic amino acids(Lys and Arg),Interestingly,three binding modes,namely Inter-Linking,Loop-Linking and Mono-Linking were for the first time found,while Inter-Linking mode accounted for the highest proportion(75.1%),suggesting that chelation of calcium ions frequently occurred between two peptides.Overall,this study provides a theoretical basis for the elucidation of chelation mechanism of calcium-chelating peptides.

The co-transport of Cd(Ⅱ) and nZnO in saturated soil packed column:effects of ionic strength and pH

The rapid development and widespread use of ZnO nanoparticles(nZnO) in various industries have raised concerns about their potential environmental impact.Therefore,understanding the fate and role of nZnO in the natural environment is crucial for mitigating their hazardous effects on the environment and human safety.The purpose of the present study was to provide scientific support for understanding and eliminating the joint risk of nanoparticle and heavy metal pollution in the soil environment by revealing the co-transport characteristics of Cd(Ⅱ) and ZnO nanoparticles(nZnO) in soil under different ionic strength(IS) and pH.The impacts of different IS and pH on the co-transport of Cd(Ⅱ) and nZnO in a20 cm long with an inner diameter of 2.5 cm acrylic column packed with 10 cm high soil samples were investigated in the present study.In the above system,a500 μg L^(-1) Cd(Ⅱ) loaded nZnO suspension pulse with varying IS or pH was introduced into the soil column for leaching over 5 PVs,followed up by 5 PVs background solutions without nZnO.The IS was 1,10,or 50 mM NaCl,with pH6,or the pH was 6,7 or 8 with 1 mM NaCl.Meanwhile,Sedimentation experiments for nZnO,adsorption of Cd(Ⅱ) on soil,and nZnO,DLVO theory calculation for the same background condition were conducted.The presence of nZnO significantly increased the mobility of Cd(Ⅱ) as a result of its strong adsorption capacity for nZnO-associated Cd(Ⅱ).However,with the increase of IS,the co-transport of nZnO and Cd(Ⅱ) was decreased and the retention of nZnO in the soil column due to more nZnO attended to aggregate and sediment during the transport and the decrease in the adsorption capacity of nZnO for Cd(Ⅱ) by competition of Na^(+).When pH was 6,7,and 8,the co-transport of nZnO and Cd(Ⅱ) increased with higher pH due to the lower electrostatic attraction between nZnO and soil under higher pH.Meanwhile,the DLVO theory was fitted to describe the above co-transport process of nZnO and Cd(Ⅱ).More attention should be paid to the presence of nZnO on the migration of Cd(Ⅱ) in the natural soil to control the potential risk of nanoparticles and heavy metals to the environment.The risk of co-transport of nZnO and Cd(Ⅱ) might be controlled by adjusting IS and pH in the soil solution.

鲁米诺的合成与振荡化学发光

鲁米诺的合成与化学发光是一个极具展示度的基础化学实验。近年来,国内部分高校陆续开设了这一实验,引起不错的反响。为进一步丰富和提升该实验的科学理论内涵,我们进行了如下改进:1)在合成部分引入机械搅拌、硫粉还原和微波合成,实现安全、快速、高效制备高纯度鲁米诺的目的;2)在单次化学发光的基础上,特别引入宛如星辰闪烁般的振荡化学发光反应(鲁米诺/H_(2)O_(2)/SCN^(-)/Cu^(2+)/OH^(-)振荡体系),该反应涉及非平衡态热力学和非线性化学等重要概念与基础理论知识,激发学生的求知欲;3)设计并搭建了可与荧光光谱仪配套使用的简易微型磁力搅拌加热装置,实现了对振荡化学发光的光强和振荡周期等数据的实时定量监测,使学生可以自行设计对比实验,探究影响振荡反应过程的因素,并总结振荡反应规律。该实验涵盖了多学科的重要知识点,兼具科学性与趣味性,对培养学生的探索精神和创新意识具有重要意义。

青霉素V钾的有机半合成及其抑菌效果表征——推荐一个化学生物学综合实验

青霉素的有机半合成及其抑菌效果表征是一个涵盖知识点众多的综合性实验,目前相关实验仅有美国麻省理工学院(MIT)等少数高校开设,国内尚未有关于该实验教学方面的报道。为了将研究型的环境引入教学实验,培养学生科学思维能力,我们进行了如下改进:1)设计并搭建了循环冷凝装置,引入低温控制,提高产物的稳定性,有效减少副产物的生成;2)添加无水乙醇后处理步骤,利用溶解度差异除去副产物;3)引入微量二倍稀释法测定青霉素最低抑菌浓度,利用牛津杯法测定青霉素抑菌圈,提高实验的展示度;4)将科研成果融入教学,使用小麦胚芽凝集素荧光标记结合荧光共聚焦显微镜表征青霉素对细菌细胞壁完整度的影响,展示青霉素的抑菌机制。该实验交叉融合有机合成与化学生物学的实验内容,引入科研表征手段,使得学生切实体验科学研究的过程,激发学生的探索精神和创新意识。

Recent progress in preventive effect of collagen peptides on photoaging skin and action mechanism

Ultraviolet(UV)-induced photoaging skin has become an urgent issue.The functional foods and cosmetics aiming to improve skin photoaging are developing rapidly,and the demand is gradually increasing year by year.Collagen peptides have been proven to display diverse physiological activities,such as excellent moisture retention activity,hygroscopicity,tyrosinase inhibitory activity and antioxidant activity,which indicates that they have great potential in amelioration of UV-induced photoaging.The main objective of this article is to recap the main mechanisms to improve photoaging skin by collagen peptides and their physiological activities in photo-protection.Furthermore,the extraction and structural characteristics of collagen peptides are overviewed.More importantly,some clinical trials on the beneficial effect on skin of collagen peptides are also discussed.In addition,prospects and challenges of collagen peptides are emphatically elucidated in this review.This article implies that collagen peptides have great potential as an effective ingredient in food and cosmetics industry with a wide application prospect.

A Knowledge-Enriched and Span-Based Network for Joint Entity and Relation Extraction

The joint extraction of entities and their relations from certain texts plays a significant role in most natural language processes.For entity and relation extraction in a specific domain,we propose a hybrid neural framework consisting of two parts:a span-based model and a graph-based model.The span-based model can tackle overlapping problems compared with BILOU methods,whereas the graph-based model treats relation prediction as graph classification.Our main contribution is to incorporate external lexical and syntactic knowledge of a specific domain,such as domain dictionaries and dependency structures from texts,into end-to-end neural models.We conducted extensive experiments on a Chinese military entity and relation extraction corpus.The results show that the proposed framework outperforms the baselines with better performance in terms of entity and relation prediction.The proposed method provides insight into problems with the joint extraction of entities and their relations.

Nanodiamonds decorated yolk-shell ZnFe_(2)O_(4) sphere as magnetically separable and recyclable composite for boosting antibiotic degradation performance

Photocatalysis is an environmentally friendly and energy-saving technology, which can effectively remove persistent dangerous pollutants in the water. Pitifully, optical absorption capacity and carrier separation have become major bottlenecks for marvelous photocatalytic performance of photocatalysts.Herein, to address these issue, Nanodiamonds/yolk-shell ZnFe_(2)O_(4) spheres(NDs/ZFO) nanocomposites were successfully constructed via a facile two-step of solvothermal and calcination methods. The synthesized optimal NDs/ZFO-10 nanocomposite exhibits superior photocatalytic degradation activity of antibiotic under visible light, approximately 85% of the total tetracycline(TC) is degraded, and this photocatalyst shows durable cycling stability. This stems from two aspects of refinement: improvement of light absorption capacity and photo-induced charges migration and separation. In addition, the NDs/ZFO composite photocatalyst features excellent magnetic recovery capability, facilitating the recovery of photocatalyst in industry. This study opens a new chapter in the combination of NDs with magnetic materials, and deepens the understanding of the application of NDs modified composite photocatalysts.

Preface to Special Issue on Towards High Performance Ga_(2)O_(3) Electronics: Epitaxial Growth and Power Devices(Ⅰ)

There is currently great optimism within the electronics community that gallium oxide(Ga_(2)O_(3)) ultra-wide bandgap semiconductors have unprecedented prospects for eventually revolutionizing a rich variety of power electronic applications. Specially, benefiting from its ultra-high bandgap of around 4.8 eV, it is expected that the emerging Ga_(2)O_(3) technology would offer an exciting platform to deliver massively enhanced device performance for power electronics and even completely new applications.

Preface to Special Issue on Towards High Performance Ga_(2)O_(3) Electronics:Power Devices and DUV Optoelectronic Devices(Ⅱ)

Gallium oxide(Ga_(2)O_(3))has garnered world-wide atten-tion as an ultrawide-bandgap semiconductor material from the area of power electronics and DUV optical devices benefit-ing from its outstanding electronic and optoelectronic proper-ties.For one thing,since Ga_(2)O_(3)features high critical break-down field of 8 MV/cm and Baliga’s figure of merit(BFOM)of 3444,it is a promising candidate for advanced high-power applications.For another thing,due to the bandgap directly corresponding to the deep-ultraviolet(DUV)region,Ga_(2)O_(3)is widely used in DUV optoelectronic devices.

Cold exposure promotes coronavirus infection by altering the gut microbiota and lipid metabolism to reduce host immunity

Objective:Cold exposure has been suggested to be advantageous for the spread and infection of the coronavirus,and the gut microbiota influences the severity of the infection by modulating host inflammatory and immune responses.However,it remains unclear whether the promotion of viral infection through cold exposure is linked to the gut microbiota.Methods:In this study,we performed an unbiased analysis of gut microbiota,serum,and lung tissue metabolome changes in cold-exposed and virus-infected mice,alongside the assessment of immune-inflammatory indicators in serum and lung tissue.Results:The results revealed that both cold exposure and viral infection significantly decreased the percentage of peripheral blood lymphocytes(CD4^(+)T cells,CD8^(+)T cells,and B cell)and increased the expression of inflammatory factors(IL-6,IL-1β,TNF-α,and IFN-γ).Meanwhile,cold exposure disrupted the homeostasis of gut microbiota,elevating the abundance of pathogenic bacteria(Staphylococcus)and diminishing the abundance of beneficial bacteria(Alistipes).Notably,in virus-infected mice exposed to a cold environment,the reduction in the abundance of beneficial bacteria Alistipes was more pronounced than in cases of single virus infection and cold exposure.Analysis of altered serum and lung tissue metabolites highlighted glycerophospholipids,fatty acids,and eicosanoids as the most affected metabolites by cold exposure.These metabolites,closely associated with virus infection,exhibited a significant correlation with immune-inflammatory indicators.Conclusion:These findings establish a mechanistic connection between cold exposure and virus infection,suggesting that cold exposure-induced dysregulation of gut microbiota and lipid metabolism diminishes host immunity,promoting virus infection.

Cardiac Piezo1 Exacerbates Lethal Ventricular Arrhythmogenesis by Linking Mechanical Stress with Ca^(2+) Handling After Myocardial Infarction

Ventricular arrhythmogenesis is a key cause of sudden cardiac death following myocardial infarction(MI).Accumulating data show that ischemia,sympathetic activation,and inflammation contribute to arrhythmogenesis.However,the role and mechanisms of abnormal mechanical stress in ventricular arrhythmia following MI remain undefined.We aimed to examine the impact of increased mechanical stress and identify the role of the key sensor Piezo1 in ventricular arrhythmogenesis in MI.Concomitant with increased ventricular pressure,Piezo1,as a newly recognized mechano-sensitive cation channel,was the most up-regulated mechanosensor in the myocardium of patients with advanced heart failure.Piezo1 was mainly located at the intercalated discs and T-tubules of cardiomyocytes,which are responsible for intracellular calcium homeostasis and intercellular communication.

清洁油品生产中溶剂萃取分离技术的研究进展

溶剂萃取分离技术广泛应用于石油化工领域,为石油石化产品的分离和提纯生产提供了有力的技术支撑.本文介绍了溶剂萃取分离技术在清洁油品生产过程中的研究进展,如芳烃抽提、溶剂萃取脱硫和关键组分定向分离技术等;分析讨论了溶剂萃取分离技术的优劣势,并就国VI汽油生产中烯烃的转化、汽油产品结构调整等社会急需解决的难题,对溶剂萃取分离技术的发展进行了展望.

溶剂结构对萃取分离直馏柴油中不同环数芳烃的影响

“双碳”目标为我国炼化行业带来巨大挑战,产品结构调整势在必行.直馏柴油作为重要的石油一次加工产品,包含约80 wt%烷烃,是优质的低碳烯烃裂解原料.然而20 wt%的芳烃易在裂解过程中结焦,导致生产周期短,乙烯收率仅20 wt%左右.因此,需对直馏柴油进行高效的芳烃脱除.为此,本研究通过量子化学计算耦合液液相平衡实验的方法,对直馏柴油溶剂萃取脱芳烃过程中溶剂结构与不同环数芳烃的萃取性能关系进行探究.结果发现,强极性、环状且空间位阻较小的溶剂利于直馏柴油芳烃的脱除,随着芳烃环数的增加,其与溶剂的相互作用位点增多,脱除率和选择性越强.这不仅为芳烃萃取溶剂的优化提供理论支撑,也为不同环数芳烃的更精细的分离提供了思路.

Blue light-emitting polyfluorenes containing dibenzothiophene-S,S-dioxide unit in alkyl side chain

Blue light-emitting polyfluorenes containing dibenzothiophene-S,S-dioxide(SO) unit in alkyl side chain(PF-FSOs and PF-CzSOs) were synthesized. All the polymers show high thermal stability with the decomposition temperatures over400 °C. The highest occupied molecular orbital(HOMO) and the lowest unoccupied molecular orbital(LUMO) energy levels of the copolymer slightly decrease with the increase of SO content in side chain. PL spectra of the polymers show slightly red shift and broadening with the increase of solvent polarities, indicating unremarkable intramolecular charge transfer(ICT) effect in the polymers containing SO unit in alkyl side chain. EL spectra of the polymers are almost unchanged in the current densities from 100 to 400 mA cm.2, indicating the superb EL stability of the resulted polymers. The EL spectra of the copolymers exhibit obvious blue-shift and narrowing with the CIE of(0.18, 0.11) for PF-FSO10 and(0.17, 0.11) for PF-CzSO10, respectively,compared with PF-SO10 containing SO unit in main chain with the CIE of(0.16, 0.17) and PFO with the CIE of(0.18, 0.18).The superior device performances were obtained with the luminous efficiency(LEmax) of 1.17 and 0.68 cd A.1 for PF-FSO15 and PF-CzSO20, respectively, compared with the LEmax of 0.37 cd A.1 for PFO. The results indicate that linking SO unit to alkyl side chain of the polyfluorene is a promising strategy for efficient blue light-emitting polymers.

Genetic and epigenetic mechanisms in the development of congenital heart diseases

Congenital heart disease(CHD)is the most common of congenital cardiovascular malformations associated with birth defects,and it results in significant morbidity and mortality worldwide.The classification of CHD is still elusive owing to the complex pathogenesis of CHD.Advances in molecular medicine have revealed the genetic basis of some heart anomalies.Genes associated with CHD might be modulated by various epigenetic factors.Thus,the genetic and epigenetic factors are gradually accepted as important triggers in the pathogenesis of CHD.However,few literatures have comprehensively elaborated the genetic and epigenetic mechanisms of CHD.This review focuses on the etiology of CHD from genetics and epigenetics to discuss the role of these factors in the development of CHD.The interactions between genetic and epigenetic in the pathogenesis of CHD are also elaborated.Chromosome abnormalities and gene mutations in genetics,and DNA methylations,histone modifications and on-coding RNAs in epigenetics are summarized in detail.We hope the summative knowledge of these etiologies may be useful for improved diagnosis and further elucidation of CHD so that morbidity and mortality of children with CHD can be reduced in the near future.

MR-seq:measuring a single cell's transcriptome repeatedly by RNA-seq

We described a novel single-cell RNA-seq technique called MR-seq （measure a single-cell transcriptome repeatedly）, which permits statistically assessing the technical variation and identifying the differentially expressed genes between just two single ceils by measuring each single cell twice. We demonstrated that MR-seq gave sensitivity and reproducibility similar to the standard single-cell RNA-seq and increased the positive predicate value, Application of MR-seq to early mouse embryos identified hundreds of candidate intra-embryonic heterogeneous genes among mouse 2-, 4- and 8-cell stage embryos. MR-seq should be useful for detecting differentially exnre^ed ~enes ~rnnn~ ~ ~m^ll nHmhpr nf c^ll~

Control of crystal growth to obtain needle-shaped violet phosphorus with excellent photocatalytic degradation performance

The control of crystal growth is important but challenging for multi-disciplinary research.Violet phosphorus,the most stable phosphorus allotrope,has recently been produced as a unique semiconducting layered structure.The crystal orientation and morphology bring extra performance due to its unique structure and anisotropy.Herein,the layered violet phosphorus has been controlled to grow along the c-axis to give tunable length up to centimeters with the assistance of tin,while the reported flat bulk ones with thickness are limited to micrometers.The as-produced needle-shaped violet phosphorus has also been demonstrated to significantly enhance the photocatalytic degradation of methyl orange pollutants due to its special crystallographic orientation.About 98.6%of methyl orange pollutants with a concentration of 50 ppm were degraded within 80 min under visible light conditions by needle-shaped violet phosphorus,which is much more effective than that of amorphous red phosphorus with only 14.1%degradation.

Constructing an artificial short route for cell-free biosynthesis of the phenethylisoquinoline scaffold

Plant-originated natural products are important drug sources.However,total biosynthesis of these compounds is often not achievable due to their uncharacterized,lengthy biosynthetic pathways.In nature,phenethylisoquinoline alkaloids(PIAs)such as colchicine are biosynthesized via a common precursor 6,7-dihydroxy-1-(4-hydroxyphenylethyl)-1,2,3,4-tetrahydroisoquinoline(i.e.,phenethylisoquinoline scaffold,PIAS).PIAS is naturally synthesized in plants by using two upstream substrates(L-phenylalanine and L-tyrosine)catalyzed by eight enzymes.To shorten this native pathway,here we designed an artificial route to synthesize PIAS with two enzymatic steps from two alternative substrates of 3-(4-hydroxyphenyl)propanol(4-HPP)and dopamine.In the two-step bioconversion,an alcohol dehydrogenase selected from yeast(i.e.,ADH7)was able to oxidize its non-native alcohol substrate 4-HPP to form the corresponding aldehyde product,which was then condensed with dopamine by the(S)-norcoclaurine synthase(NCS)to synthesize PIAS.After optimization,the final enzymatic reaction system was successfully scaled up by 200 times from 50μL to 10 mL,generating 5.4 mM of PIAS.We envision that this study will provide an easy and sustainable approach to produce PIAS and thus lay the foundation for large-scale production of PIAS-derived natural products.

Experimental study of primary and secondary side coupling natural convection heat transfer characteristics of the passive residual heat removal system in AP1000

Passive residual heat removal heat exchanger(PRHR HX),which is a newly designed equipment in the advanced reactors of AP1000 and CAP1400,plays an important role in critical accidental conditions.The primary and secondary side coupling heat transfer characteristics of the passive residual heat removal system(PRHRS)determine the capacity to remove core decay heat during the accidents.Therefore,it is necessary to investigate the heat transfer characteristics and develop applicable heat transfer formulas for optimized design.In the present paper,an overall scaled-down natural circulation loop of PRHRS in AP1000,which comprises a scaleddown in-containment refueling water storage tank(IRWST)and PRHR HX models and a simulator of the reactor core,is built to simulate the natural circulation process in residual heat removal accidents.A series of experiments are conducted to study thermal-hydraulic behaviors in both sides of the miniaturized PRHR HX which is simulated by 12 symmetric arranged C-shape tubes.For the local PRHR HX heat transfer performance,traditional natural convection correlations for both the horizontal and vertical bundles are compared with the experimental data to validate their applicability for the specific heat transfer condition.Moreover,the revised natural convection heat transfer correlations based on the present experimental data are developed for PRHR HX vertical and lower horizontal bundles.This paper provides essential references for the PRHRS operation and further optimized design.

Overcoming the limitations of gallium oxide through heterogeneous integration

Power electronics,processing over 50%of world's electric energy,enables very efficient electric energy conversion for a wide range of applications such as electric vehicles,data centers,autonomous driving,robotics and smart grids.The availability of low-cost,efficient,and reliable power semiconductor devices that can conduct high current,block high voltage,and switch at high frequencies are key to improving the performance of power electronics systems.