Recent progress in thermodynamic and kinetics modification of magnesium hydride hydrogen storage materials

Hydrogen energy has emerged as a pivotal solution to address the global energy crisis and pave the way for a cleaner,low-carbon,secure,and efficient modern energy system.A key imperative in the utilization of hydrogen energy lies in the development of high-performance hydrogen storage materials.Magnesium-based hydrogen storage materials exhibit remarkable advantages,including high hydrogen storage density,cost-effectiveness,and abundant magnesium resources,making them highly promising for the hydrogen energy sector.Nonetheless,practical applications of magnesium hydride for hydrogen storage face significant challenges,primarily due to their slow kinetics and stable thermodynamic properties.Herein,we briefly summarize the thermodynamic and kinetic properties of MgH2,encompassing strategies such as alloying,nanoscaling,catalyst doping,and composite system construction to enhance its hydrogen storage performance.Notably,nanoscaling and catalyst doping have emerged as more effective modification strategies.The discussion focuses on the thermodynamic changes induced by nanoscaling and the kinetic enhancements resulting from catalyst doping.Particular emphasis lies in the synergistic improvement strategy of incorporating nanocatalysts with confinement materials,and we revisit typical works on the multi-strategy optimization of MgH2.In conclusion,we conduct an analysis of outstanding challenges and issues,followed by presenting future research and development prospects for MgH2 as hydrogen storage materials.

差热-拉曼光谱联用系统的搭建及其在熔盐相图测定实验中的运用

通过元件和设备的拼装方式创建新的研究方法,这是科技创新的重要途径之一。本项目以差热-拉曼光谱联用测量系统的搭建为例,利用实验室现有的设备单元组建差热分析部件,将其设计成可适用于拉曼光谱测量的差热分析(DTA)平台,并将所制的差热-拉曼联用系统用于研究混合熔盐的相变过程。通过仪器组建和实验测量过程,学生可以深入了解差热分析的原理,认识到多种实验技术联合使用产生的增强效应。更为重要的是,他们能够学习如何利用手边的元件单元创立新研究方法。因此,这个实验项目能够有效提高学生的创新能力和科研能力。此外,该系统涉及的差热分析平台、数据采集系统和相图测量等方面都能够开展进一步的改进和升级,这就保证了这个开放实验教学项目具有可持续的创新教学功能。

传统物理化学实验内容设计的再讨论

以案例分析的方式,对传统物理化学实验项目“燃烧热的测定”“界面移动法测定离子迁移数”和“临界胶束浓度测定”的实验内容和数据分析过程进行了必要的补充和发展,以满足“高阶性、创新性和挑战度”的要求。实践证明,对实验理论和模型的丰富和加强,能够有效提升实验教学的学术层次,并提高学生的数据分析能力和训练水平,以满足新时代“金课”的标准要求。

普通化学实验新技术和新思路

对普通化学实验课程的现状及不足之处进行了分析研究,提出了根据“反应过程可视化、实验成果实物化及化学理论虚拟现实化”的原则,采用数码成像实验技术改变学生观察实验的角度和视野,在实验中完成可实用的产品,并通过软件、手工、3D打印等方法呈现物质的微观结构。这些实验教学改革的新技术和新思路,能够使普通化学实验的面貌得到极大改观,拓展学生视野,培养创新思维,使化学教育教学工作获得更多学生的认可和喜爱。

人工智能时代成人情境学习的新向度

人工智能技术的发展促进了成人学习者的基本素养提升、技能方向变更、思维能力拓展。在人工智能时代,情境学习强调在智能空间的情境下创设成人学习的新场域,以深度学习跨越成人思维盲点门槛,以社会互动联结成人精神情感纽带。要在人工智能时代实现成人情境学习,需要创设开放情境,突破固化思维;转换教师角色,引导良性对话;开发集体修炼,实现成人的共同觉醒。

Analysis on Antibacterial, Detumescent and Antioxidant Activity of Huoshan Large-leaf Yellow Tea

[Objectives] To provide experimental basis for the effective development and utilization of Huoshan large-leaf yellow tea resources and the screening of safe and effective active ingredients of large-leaf yellow tea. [Methods] The active substances of Huoshan large-leaf yellow tea were extracted by hot-water extraction, and the freeze-dried powder of Huoshan large-leaf yellow tea was obtained by freeze drying. The antibacterial activity of the extract was preliminarily confirmed using the Oxford cup method, and its antimicrobial spectrum was analyzed using 14 strains. A xylene-induced mouse auricle swelling test was carried out to detect the swelling inhibition rate of the extract and analyze its in-vitro detumescent activity. Then, the antioxidant activity of the extract was identified through a DPPH free radical scavenging capacity test and a ferric reducing antioxidant power assay. [Results] The extract had significant inhibitory effects on various bacteria. The extract could effectively inhibit the growth of Escherichia coli, Staphylococcus aureus, Enterococcus hirae, Acinetobacter baumannii, Klebsiella pneumonia, Pseudomonas aeruginosa, Bacillus subtilis , and other strains. The diameter of the inhibition zone increased with the increase of sample concentration. The extract had a significant inhibitory effect on auricle swelling induced by xylene in mice. When the concentration of the drug reached 1.0 mg/mL, its inhibition rate on mouse auricle swelling reached 55.2% ( P <0.01), slightly lower than the swelling inhibition rate of the aspirin group (66.52%, P <0.01). The results of the antioxidant test showed that large-leaf yellow tea extract also had strong activity. Within the concentration range of 0.1-1.0 mg/mL, its DPPH radical scavenging rate increased with the increase of sample concentration. Within the concentration range of 0.1-1.0 mg/mL, its DPPH radical scavenging rate increased with the increase of sample concentration. When the concentration reached 1.0 mg/mL, the scavenging rate reached 69.75%. The Fe 3+ -reduction capacity of the extract also increased with the increase of sample concentration within the concentration range of 0.1-2.5 mg/mL. When the concentration was 2.5 mg/mL, the reducing power of the extract reached 1.43±0.04. However, its DPPH free radical scavenging rate and reducing power were slightly lower than the capacity of V C at the same concentration. [Conclusions] The extract of Huoshan large-leaf yellow tea obtained by hot-water extraction had strong activity in many aspects, including inhibiting the growth of various microbes, subsiding swelling in vitro and resisting oxidation. These experimental results provide certain guiding significance for the basic research of Huoshan large-leaf yellow tea extract, as well as experimental data support for the subsequent development of functional foods and drugs of Huoshan large-leaf yellow tea.

The nature of irreversible phase transformation propagation in nickel-rich layered cathode for lithium-ion batteries

Ni-rich layered cathode is regarded as one of the most promising candidates to achieve lithium-ion batteries (LIBs) with high energy density. However, due to the irreversible phase transformation (IPT) and its eventual propagation from surface to the bulk of the material, Ni-rich layered cathode typically suffers from severe capacity fading, structure failure, and thermal instability, which greatly hinders its mass adoption. Hence, achieving an in-depth understanding of the IPT propagation mechanism in Ni-rich layered cathode is crucial in addressing these issues. Herein, the triggering factor of IPT propagation in Ni-rich cathode is verified to be the initial surface disordered cation mixing domain covered by a thin rock-salt phase, instead of the rock-salt phase itself. According to the density functional theory (DFT) results, it is further illustrated that the metastable cation mixing domain possesses a lower Ni migration energy barrier, which facilitates the migration of Ni ions towards the Li slab, and thus driving the propagation of IPT from surface to the bulk of the material. This finding clarifies a prevailing debate regarding the surface impurity phases of Ni-rich cathode material and reveals the origin of IPT propagation, which implies the principle and its effectiveness of tuning the surface microstructure to address the structural and thermal instability issue of Ni-rich layered cathode materials.

Quantifying impacts of climate and human activities on the grassland in the Three-River Headwater Region after two phases of Ecological Project

The Three-River Headwater Region(TRHR)of China is a typical representative of the alpine environment in the Central Asian plateau and the alpine grassland in the world.Grassland degradation is one of its serious eco-logical problems.The purpose of this study is to quantify the joint impacts of climate and human activities on grassland changes in TRHR after two phases of Ecological Conservation and Construction Project(Ecological Project).Grassland vegetation coverage is selected as an indicator for analyzing grassland changes.We adopt Sen+Mann-Kendall trend analysis,residual trend analysis and correlation analysis methods to analyze the trends in spatial-temporal changes and driving factors of grassland in TRHR from 2000 to 2019.The results show that:(1)The grassland has been mainly restored,and the degraded grassland area only accounts for 1.66%of TRHR.After the implementation of the first phase of the Ecological Project,the percentage of restored grassland area has significantly increased from 8.82%to 24.57%,and slightly decreased during the second phase.(2)The establish-ment of national nature reserves and the implementation of the Ecological Project have changed the situation that“the grassland inside the reserve is worse than that outside the reserve”.(3)Grassland restoration is mainly af-fected by the joint effects of climate and human activities.Nevertheless,grassland degradation is mainly affected by human activities such as overgrazing and grassland reclamation.All of these findings can enrich our under-standing of grassland restoration in TRHR.Artificial measures have certain limitations in promoting grassland restoration.Natural restoration should be considered when human beings strengthen ecological conservation and transform their production and life styles.

Characteristics and source apportionment of PM_(2.5) under the dual influence of the Spring Festival and the COVID-19 pandemic in Yuncheng city

Based on the online and membrane sampling data of Yuncheng from January 1st to February 12th,2020,the formation mechanism of haze under the dual influence of Spring Festival and COVID-19 (Corona Virus Disease) was analyzed.Atmospheric capacity,chemical composition,secondary transformation,source apportionment,backward trajectory,pollution space and enterprise distribution were studied.Low wind speed,high humidity and small atmospheric capacity inhibited the diffusion of air pollutants.Four severe pollution processes occurred during the period,and the pollution degree was the highest around the Spring Festival.In light,medium and heavy pollution periods,the proportion of SNA (SO_(4)^(2-),NO_(3)-and NH_(4)^(+)) was 59.6%,56.0%and 54.9%,respectively,which was the largest components of PM_(2.5);the[NO_(3)-]/[SO_(4)^(2-)]ratio was 2.1,1.5 and 1.7,respectively,indicating that coal source had a great influence;the changes of NOR (nitrogen oxidation ratio,0.44,0.45,0.61)and SOR (sulphur oxidation ratio,0.40,0.49,0.65) indicated the accumulation of secondary aerosols with increasing pollution.The coal combustion,motor vehicle,secondary inorganic sources and industrial sources contributed 36.8%,26.59%,11.84%and 8.02%to PM_(2.5)masses,respectively.Backward trajectory showed that the influence from the east was greater during the Spring Festival,and the pollutants from the eastern air mass were higher,which would aggravate the pollution.Meteorological and Spring Festival had a great impact on heavy pollution weather.Although some work could not operate due to the impact of the COVID-19 epidemic,the emission of pollutants did not reduce much.

Field assessment of straw pellet combustion in improved heating stoves in rural Northeast China

Straw pellets are widely promoted and expected to be a cleaner alternative fuel to unprocessed crop residues and rawcoal in rural China.However,the effectiveness of these dissemination programs is not well evaluated.In this field study,emission characteristics of burning strawpellets,rawcoal,and unprocessed corn cobs in heating stoveswere investigated in a pilot village in Northeast China.Emission measurements covering the whole combustion cycle(ignition,flaming,and smoldering phases)shows the promotion of improved heating stoves and straw pellets could reduce pollutant emissions(e.g.,SO_(2) and CO),but increase NO_(X) and PM_(2.5) emissions compared to the initial stove-fuel use pattern in the studied area.There is a significant variance in emission characteristics between different combustion phases.The normalized emission concentrations of the different stove-fuel combinations were higher than the limits in the Chinese national standard for heating stoves,indicating that the standard is not met for real-world emissions.Coal consumption was lower than official data.Household surveys were conducted to identify the barriers to fuel and stove access associated with existing promotion strategies,management,and policies.The pilot program was of the typical“subsidy-and-policy-dependence”pattern and was unlikely to be implemented on a large scale.Technological innovation,operational optimization,and proper policies considering the local socioeconomic factors are needed to sustain the promotion of biomass straw pellets and stoves.

Enhanced secondary organic aerosol formation during dust episodes by photochemical reactions in the winter in Wuhan

To investigate the effect of frequently occurring mineral dust on the formation of secondary organic aerosol(SOA),106 volatile organic compounds(VOCs),trace gas pollutants and chemical components of PM_(2.5) were measured continuously in January 2021 in Wuhan,Central China.The observation period was divided into two stages that included a haze period and a following dust period,based on the ratio of PM_(2.5) and PM_(10) concentrations.The average ratio of secondary organic carbon(SOC)to elemental carbon(EC)was 1.98 during the dust period,which was higher than that during the haze period(0.69).The contribution of SOA to PM_(2.5) also increased from 2.75% to 8.64%.The analysis of the relationships between the SOA and relative humidity(RH)and the odd oxygen(e.g.,O_(X)=O_(3)+NO_(2))levels suggested that photochemical reactions played a more important role in the enhancement of SOA production during the dust period than the aqueous-phase reactions.The heterogeneous photochemical production of OH radicals in the presence of metal oxides during the dust period was believed to be enhanced.Meanwhile,the ratios of trans-2-butene to cis-2-butene and m-/p-xylene to ethylbenzene(X/E)dropped significantly,confirming that stronger photochemical reactions occurred and SOA precursors formed efficiently.These results verified the laboratory findings that metal oxides in mineral dust could catalyse the oxidation of VOCs and induce higher SOA production.

Time-Varying Functional Connectivity of Rat Brain during Bipedal Walking on Unexpected Terrain

The cerebral cortex plays an important role in human and other animal adaptation to unpredictable terrain changes,but little was known about the functional network among the cortical areas during this process.To address the question,we trained 6 rats with blocked vision to walk bipedally on a treadmill with a random uneven area.Whole-brain electroencephalography signals were recorded by 32-channel implanted electrodes.Afterward,we scan the signals from all rats using time windows and quantify the functional connectivity within each window using the phase-lag index.Finally,machine learning algorithms were used to verify the possibility of dynamic network analysis in detecting the locomotion state of rats.We found that the functional connectivity level was higher in the preparation phase compared to the walking phase.In addition,the cortex pays more attention to the control of hind limbs with higher requirements for muscle activity.The level of functional connectivity was lower where the terrain ahead can be predicted.Functional connectivity bursts after the rat accidentally made contact with uneven terrain,while in subsequent movement,it was significantly lower than normal walking.In addition,the classification results show that using the phase-lag index of multiple gait phases as a feature can effectively detect the locomotion states of rat during walking.These results highlight the role of the cortex in the adaptation of animals to unexpected terrain and may help advance motor control studies and the design of neuroprostheses.

2-取代苯并噻唑化合物的合成进展

2-取代苯并噻唑在生物医药、材料科学等领域的应用和研究使其合成方法受到了广泛的关注.在传统合成方法的研究基础之上,单质硫介导的氧化还原反应和饱和化合物的脱氢芳构化反应等新方法的发展,为苯并噻唑衍生物的合成提供更多可能.此外,近年来新型金属-有机骨架催化剂、组合离子液体/凝胶、超声以及微波辅助等的应用,极大地丰富了苯并噻唑衍生物的合成方式.综述了近年来2-取代苯并噻唑的合成方法.

南阿尔金地区含铀-富铀锆钛石的发现及其新成因机制

锆钛石(ZrTi2O6)为高级变质岩、交代地幔岩和岩浆岩中的一种罕见副矿物,是研究高场强元素迁移与富集机理的理想对象.中国南阿尔金高压-超高压变质带的高压基性麻粒岩中发现了含铀-富铀锆钛石,其主要化学组成为TiO2,ZrO2和UO2,但不同颗粒或同一颗粒不同区域成分变化较大,UO2含量最高可达20.83 wt%,且U与Zr具类质同象替代关系,晶体化学式可简写为(Zr,U)Ti2O6.低-中等UO2含量的含铀锆钛石与不含铀锆钛石相比晶体结构未发生显著变化,高UO2含量的富铀锆钛石由于放射性损伤已发生蜕晶化.矿物显微结构及成分分析表明南阿尔金含铀-富铀锆钛石及其伴生矿物组合为:金红石-钛铁矿-含铀-富铀锆钛石-白钨矿或钛铁矿-含铀-富铀锆钛石-白钨矿,其中钛铁矿为金红石退变形成,而含铀-富铀锆钛石和白钨矿是金红石退变分解过程中释放的Zr,Ti,W等元素与变质流体中的U,Ca结合直接结晶形成.该研究对矿物尺度高场强元素迁移富集机理具有重要的指示意义.

CRISPR/Cas9技术编辑OsRhoGDI2基因导致水稻半矮化

OsRhoGDI2是通过酵母双杂交从水稻幼穗中分离的一个与Rho蛋白家族成员OsRacD相互作用蛋白的编码基因,但功能尚不明确。本研究利用CRISPR/Cas9技术创制水稻OsRhoGDI2基因敲除突变体。检测结果表明,转基因水稻T0代获得2种纯合突变体,T1代获得8种纯合突变体。序列分析显示,在敲除水稻中,该基因的编辑靶点附近发生了碱基的替换或缺失,预期生成丧失RhoGDI保守结构域的截短蛋白。表型比对分析发现,敲除水稻与对照相比,株高显著降低,统计学分析结果显示,敲除水稻株高降低源于第Ⅱ和第Ⅲ茎节的缩短,提示OsRhoGDI2基因可能与水稻株高控制相关。

Washed microbiota transplantation vs.manual fecal microbiota transplantation:clinical findings,animal studies and in vitro screening

Fecal microbiota transplantation(FMT)by manual preparation has been applied to treat diseases for thousands of years.However,this method still endures safety risks and challenges the psychological endurance and acceptance of doctors,patients and donors.Population evidence showed the washed microbiota preparation with microfiltration based on an automatic purification system followed by repeated centrifugation plus suspension for three times significantly reduced FMT-related adverse events.This washing preparation makes delivering a precise dose of the enriched microbiota feasible,instead of using the weight of stool.Intraperitoneal injection in mice with the fecal microbiota supernatant obtained after repeated centrifugation plus suspension for three times induced less toxic reaction than that by the first centrifugation following the microfiltration.The toxic reactions that include death,the change in the level of peripheral white blood cells,and the proliferation of germinal center in secondary lymphoid follicles in spleen were noted.The metagenomic next-generation sequencing(NGS)indicated the increasing types and amount of viruses could be washed out during the washing process.Metabolomics analysis indicated metabolites with pro-inflammatory effects in the fecal microbiota supernatant such as leukotriene B4,corticosterone,and prostaglandin G2 could be removed by repeated washing.Near-infrared absorption spectroscopy could be served as a rapid detection method to control the quality of the washingprocess.In conclusion,this study for the first time provides evidence linking clinical findings and animal experiments to support that washed microbiota transplantation(WMT)is safer,more precise and more quality-controllable than the crude FMT by manual.

Rational Design and Development of Low-Price, Scalable, Shelf-Stable and Broadly Applicable Electrophilic Sulfonium Ylide-Based Trifluoromethylating Reagents

The development of two highly reactive electrophilic trifluoromethylating reagents(trifluoromethyl)(4-nitrophenyl)bis(carbometh-oxy)methylide(1g)and(trifluoromethyl)(3-chlorophenyl)bis(carbomethoxy)methylide(1j)through structure-activity study was described.Under mild conditions,reagent 1g reacted with β-ketoesters and silyl enol ethers to give α-trifluoromethylated-β-ketoesters or α-trifluoromethylated ketones in high yields.In addition,reagent 1g could serve as a trifluoromethyl radical for a variety of trifluo-romethylative transformations under visible light irradiation,including radical trifluoromethylation of electron-rich indoles and pyrroles and sodium aryl sulfinates as well as trifluoromethylative difunctionalization with styrene derivatives.On the other hand,as a complimentary,under reductive coupling conditions,reagent 1j reacted with a variety of(hetero)aryl iodides for the formation of tri-fluoromethylated(hetero)arenes.

芦岭煤田微生物群落结构和生物成因气的产甲烷类型研究

【目的】揭示芦岭煤田微生物群落组成,并分析其潜在的产甲烷类型及产甲烷途径。【方法】采集芦岭煤田的煤层气样品和产出水样品,分别分析样品的地球化学性质特征;利用Illumina HiSeq高通量测序技术分析产出水中的微生物群落结构;采用添加不同底物的厌氧培养实验进一步证实芦岭煤田生物成因气的产甲烷类型。【结果】该地区煤层气为生物成因和热成因的混合成因气;古菌16S rRNA基因分析表明在产出水中含有乙酸营养型、氢营养型和甲基营养型的产甲烷菌。丰度较高的细菌具有降解煤中芳香族和纤维素衍生化合物的潜力。厌氧富集培养结果表明,添加乙酸盐、甲酸盐、H2+CO2为底物的矿井水样均有明显的甲烷产生。【结论】芦岭煤田具有丰富的生物多样性,该地区同时存在三种产甲烷类型。本研究为利用微生物技术提高煤层气的采收率,实现煤层气的可持续开采提供科学依据。

From interpenetrating polymer networks to hierarchical porous carbons for advanced supercapacitor electrodes

Hierarchical porous carbons (HPCs) are obtained via in-situ activation of interpenetrating polymer networks (IPNs) obtained from simultaneous polymerization of resorcinol/formaldehyde (R/F) and polyacrylamide (PAM). The hierarchically micro-, meso-and macroporous structure of as-prepared HPCs is attributed to the synergistic pore-forming effect of PAM and KOH, including PAM decomposition, KOH chemical activation, and a foaming process of potassium polyacrylate formed by partial hydrolysis of PAM in KOH aqueous solution. The typical HPC electrode with the highest surface area (2544 m2/g) shows a high specific capacitance of 261 F/g at 1.0 A/g and a superior rate capability of 216 F/g at 20 A/g in alkaline electrolyte. Moreover, the electrode maintains the capacitance retention of 90.8% after 10000 chargingdischarging cycles at 1.0 A/g, exhibiting long cycling life. This study highlights a new avenue towards IPNs-derived carbons with unique pore structure for promising electrochemical applications.

Monofluoromethyl-Substituted Sulfonium Ylides:Preparation,Structure-Reactivity Study and Substrate Scope

of main observation and conclusion Structure-reactivity study of a family of electrophilic monofluoromethylating reagents based on sulfonium ylide skeleton with different steric hindrance and electron-withdrawing properties was described.These studies led us to discover two highly reactive reagents 3 with a cyclic malonate backbone and 6 with an electron-poor 1,1,1,5,5,5-hexafluoropentane-2,4-dione backbone.The high reactivity of reagent 6 allowed to highly selectively access either C-monofluoromethylated or O-monofluoromethylated p-ketoesters in high yields by the use of different bases.In addition,reactions of reagent 3 with a variety of nucleophiles including phenols,carboxylic acids,thiophenols or heteroaryl nucleophiles occurred in full conversion within 10 min at room temperature and the scopes for these reactions were reported in detail.