富含氧空位的由多金属氧簇辅助的银基异质结用于高效电催化固氮

目前工业产氨主要依赖传统的Haber-Bosch工艺,然而该工艺条件苛刻,需要高温(350-550℃)和高压(150-250bar),每年消耗全球能源供应的2%,同时排放4.5亿吨二氧化碳(占全球总排放量的1.6%).近年来,科研工作者致力于开发高效率、高选择性的固氮电催化剂,但是由于析氢反应的强烈竞争,目前已报道的氮还原催化剂仍然受到低法拉第效率和低氨产率的限制.因此,开发活性位点丰富、氮气吸附能力强、催化性能优异的氮还原电催化剂成为当务之急.贵金属催化剂由于其纳米结构中富含活性位点,并且金属表界面处具有较好的导电性,因此表现出较高的法拉第效率.而分子催化剂因可调的电子结构和明确的构效关系引起了广泛关注.多金属氧簇是一种典型的金属聚阴离子团簇,由氧原子连接的含氧多面体组成,且具备优异的氧化还原性能.因此,本课题组尝试将多金属氧簇分子引入到氮还原催化剂中,并探究其催化机理.本文选取了一个多金属氧簇为前驱体,在溶剂、还原剂和诱导剂共存时,通过一锅法合成了富含氧空位的AgPW_(11)/Ag纳米方块电催化剂.实验结果表明,富含氧空位的AgPW_(11)/Ag异质结催化剂在-0.2 V(vs.RHE)电位时表现出高达46.02±1.03μg h^(-1)mg^(-1)_(cat).的氨产率和34.07±0.16%的法拉第效率,催化反应能够稳定运行32h且性能未见衰减,显著优于银催化剂.随后系统地研究了AgPW_(11)/Ag催化剂的氮还原活性位点,发现异质结中的银单质为催化反应提供了高导电性的支持,而催化剂中的银氧簇具有较好的电子得失能力,有利于促进氮还原反应中的六电子转移过程.丰富的氧空位利于吸附氮气,也能协同提升AgPW_(11)/Ag对电化学氮还原的催化活性.密度泛函理论计算结果表明,在还原后的银氧簇中,银原子d轨道与氮气π*轨道之间的强相互作用激活了吸附的氮气,促进了第一个质子化过程:*N_(2)向*N-NH的转化(电化学决速步).综上,本工作建立了异质结催化剂的催化性能与其分子结构之间的构效关系,为开发多金属氧簇及其衍生物作为电催化剂提供了依据和思路.

Engineering Strategies for Suppressing the Shuttle Effect in Lithium–Sulfur Batteries

Lithium–sulfur(Li–S)batteries are supposed to be one of the most potential next-generation batteries owing to their high theoretical capacity and low cost.Nevertheless,the shuttle effect of firm multi-step two-electron reaction between sulfur and lithium in liquid electrolyte makes the capacity much smaller than the theoretical value.Many methods were proposed for inhibiting the shuttle effect of polysulfide,improving corresponding redox kinetics and enhancing the integral performance of Li–S batteries.Here,we will comprehensively and systematically summarize the strategies for inhibiting the shuttle effect from all components of Li–S batteries.First,the electrochemical principles/mechanism and origin of the shuttle effect are described in detail.Moreover,the efficient strategies,including boosting the sulfur conversion rate of sulfur,confining sulfur or lithium polysulfides(LPS)within cathode host,confining LPS in the shield layer,and preventing LPS from contacting the anode,will be discussed to suppress the shuttle effect.Then,recent advances in inhibition of shuttle effect in cathode,electrolyte,separator,and anode with the aforementioned strategies have been summarized to direct the further design of efficient materials for Li–S batteries.Finally,we present prospects for inhibition of the LPS shuttle and potential development directions in Li–S batteries.

Intermittent disturbance mechanical behavior and fractional deterioration mechanical model of rock under complex true triaxial stress paths

Mechanical excavation,blasting,adjacent rockburst and fracture slip that occur during mining excavation impose dynamic loads on the rock mass,leading to further fracture of damaged surrounding rock in three-dimensional high-stress and even causing disasters.Therefore,a novel complex true triaxial static-dynamic combined loading method reflecting underground excavation damage and then frequent intermittent disturbance failure is proposed.True triaxial static compression and intermittent disturbance tests are carried out on monzogabbro.The effects of intermediate principal stress and amplitude on the strength characteristics,deformation characteristics,failure characteristics,and precursors of monzogabbro are analyzed,intermediate principal stress and amplitude increase monzogabbro strength and tensile fracture mechanism.Rapid increases in microseismic parameters during rock loading can be precursors for intermittent rock disturbance.Based on the experimental result,the new damage fractional elements and method with considering crack initiation stress and crack unstable stress as initiation and acceleration condition of intermittent disturbance irreversible deformation are proposed.A novel three-dimensional disturbance fractional deterioration model considering the intermediate principal stress effect and intermittent disturbance damage effect is established,and the model predicted results align well with the experimental results.The sensitivity of stress states and model parameters is further explored,and the intermittent disturbance behaviors at different f are predicted.This study provides valuable theoretical bases for the stability analysis of deep mining engineering under dynamic loads.

Effects of the kinetic pattern of dietary glucose release on nitrogen utilization, the portal amino acid profile, and nutrient transporter expression in intestinal enterocytes in piglets

Background Promoting the synchronization of glucose and amino acid release in the digestive tract of pigs could effectively improve dietary nitrogen utilization.The rational allocation of dietary starch sources and the exploration of appropriate dietary glucose release kinetics may promote the dynamic balance of dietary glucose and amino acid supplies.However,research on the effects of diets with different glucose release kinetic profiles on amino acid absorption and portal amino acid appearance in piglets is limited.This study aimed to investigate the effects of the kinetic pattern of dietary glucose release on nitrogen utilization,the portal amino acid profile,and nutrient transporter expression in intestinal enterocytes in piglets.Methods Sixty-four barrows(15.00±1.12 kg)were randomly allotted to 4 groups and fed diets formulated with starch from corn,corn/barley,corn/sorghum,or corn/cassava combinations(diets were coded A,B,C,or D respectively).Protein retention,the concentrations of portal amino acid and glucose,and the relative expression of amino acid and glucose transporter m RNAs were investigated.In vitro digestion was used to compare the dietary glucose release profiles.Results Four piglet diets with different glucose release kinetics were constructed by adjusting starch sources.The in vivo appearance dynamics of portal glucose were consistent with those of in vitro dietary glucose release kinetics.Total nitrogen excretion was reduced in the piglets in group B,while apparent nitrogen digestibility and nitrogen retention increased(P<0.05).Regardless of the time(2 h or 4 h after morning feeding),the portal total free amino acids content and contents of some individual amino acids(Thr,Glu,Gly,Ala,and Ile)of the piglets in group B were significantly higher than those in groups A,C,and D(P<0.05).Cluster analysis showed that different glucose release kinetic patterns resulted in different portal amino acid patterns in piglets,which decreased gradually with the extension of feeding time.The portal His/Phe,Pro/Glu,Leu/Val,Lys/Met,Tyr/Ile and Ala/Gly appeared higher similarity among the diet treatments.In the anterior jejunum,the glucose transporter SGLT1 was significantly positively correlated with the amino acid transporters B0AT1,EAAC1,and CAT1.Conclusions Rational allocation of starch resources could regulate dietary glucose release kinetics.In the present study,group B(corn/barley)diet exhibited a better glucose release kinetic pattern than the other groups,which could affect the portal amino acid contents and patterns by regulating the expression of amino acid transporters in the small intestine,thereby promoting nitrogen deposition in the body,and improving the utilization efficiency of dietary nitrogen.

Potential industrial applications of photo/electrocatalysis: Recent progress and future challenges

Nowadays,the rapid development of the social economy inevitably leads to global energy and environmental crisis.For this reason,more and more scholars focus on the development of photocatalysis and/or electrocatalysis technology for the advantage in the sustainable production of high-value-added products,and the high efficiency in pollutants remediation.Although there is plenty of outstanding research has been put forward continuously,most of them focuses on catalysis performance and reaction mechanisms in laboratory conditions.Realizing industrial application of photo/electrocatalytic processes is still a challenge that needs to be overcome by social demand.In this regard,this review comprehensively summarized several explorations in thefield of photo/electrocatalytic reduction towards potential industrial applications in recent years.Special attention is paid to the successful attempts and the current status of photo/electrocatalytic water splitting,carbon dioxide conversion,resource utilization from waste,etc.,by using advanced reactors.The key problems and challenges of photo/electrocatalysis in future industrial practice are also discussed,and the possible development directions are also pointed out from the industry view.

碳酸盐炼制共热耦合甲烷干重整制高附加值化学品发展展望

传统过程工业,诸如我国水泥、钢铁、耐材和电石等行业,都涉及碳酸盐高温热分解过程,其导致的CO_(2)排放量超过了全国工业碳排放总量的50%,大量CO_(2)排放对全球气候产生了不可逆转的影响。因此,如何减少过程工业排放的CO_(2)并且充分利用碳酸盐热分解的余热面临着巨大挑战。为进一步降低该类过程工业的CO_(2)排放量同时降低其热分解的能耗,通过利用地球上储量丰富的温室气体CH_(4),对碳酸盐进行共热耦合重整制备合成气等高附加值产品,有望成为一种环保经济的技术路线。本文总结了(光/热)碳酸盐炼制耦合甲烷干重整反应、醇类重整反应以及CO_(2)捕获反应的最新进展,并且对碳酸盐炼制耦合甲烷干重整反应在理论计算方面的研究进展进行了介绍,进一步结合本课题组近期关于碳酸盐共热耦合甲烷重整的最新结果,我们提出了该类耦合反应的发展展望,为实现CO_(2)的高效转化和减排增效提供了思路。

High valence metals engineering strategies of Fe/Co/Ni-based catalysts for boosted OER electrocatalysis

Electrocatalysis for the oxygen evolution reactions(OER)has attracted much attention due to its important role in water splitting and rechargeable metal-air batteries.Therefore,designing highly efficient and low-cost catalysts for OER process is essential as the conventional catalysts still rely on precious metals.Transition metal-based compounds have been widely investigated as active OER catalysts,and renewed interest in the high valence metals engineered compounds has been achieved for superior catalytic activity and stability.However,an in-depth understanding of the construction strategies and induced effects for the high valence metals engineered catalysts is still lacking and desired.In this review,we have summarized the construction strategies of high valence metals as dopants or formed heterostructures with the iron/cobalt/nickel(Fe/Co/Ni)-based catalysts.Then the induced effects on Fe/Co/Ni-based catalysts by incorporating high valence metals,e.g.,accelerating the surface reconstruction,forming amorphous structure,generating vacancies/defects,and acting as stabilizers,are highlighted.The impacts of high valence metals on OER performance are elucidated based on different elements,including molybdenum(Mo),tungsten(W),cerium(Ce),vanadium(V),chromium(Cr),manganese(Mn),niobium(Nb),zirconium(Zr).The correlations of construction strategies,induced effects,catalytic activity and OER reaction pathways are elaborated.Finally,the remaining challenges for further enhancements of OER performance induced by high valence metals are presented.

Electrochemical Carbon Dioxide Reduction to Ethylene:From Mechanistic Understanding to Catalyst Surface Engineering

Electrochemical carbon dioxide reduction reaction(CO_(2)RR)provides a promising way to convert CO_(2)to chemicals.The multicarbon(C_(2+))products,especially ethylene,are of great interest due to their versatile industrial applications.However,selectively reducing CO_(2)to ethylene is still challenging as the additional energy required for the C–C coupling step results in large overpotential and many competing products.Nonetheless,mechanistic understanding of the key steps and preferred reaction pathways/conditions,as well as rational design of novel catalysts for ethylene production have been regarded as promising approaches to achieving the highly efficient and selective CO_(2)RR.In this review,we first illustrate the key steps for CO_(2)RR to ethylene(e.g.,CO_(2)adsorption/activation,formation of~*CO intermediate,C–C coupling step),offering mechanistic understanding of CO_(2)RR conversion to ethylene.Then the alternative reaction pathways and conditions for the formation of ethylene and competitive products(C_1 and other C_(2+)products)are investigated,guiding the further design and development of preferred conditions for ethylene generation.Engineering strategies of Cu-based catalysts for CO_(2)RR-ethylene are further summarized,and the correlations of reaction mechanism/pathways,engineering strategies and selectivity are elaborated.Finally,major challenges and perspectives in the research area of CO_(2)RR are proposed for future development and practical applications.

单层类水滑石纳米片的可控合成及规模生产展望

水滑石(LDHs)是一种阴离子黏土材料,由于其主体层板厚度的可调性,使其在光/电催化、电池、超级电容器、传感器以及生物医药等领域都具有广泛应用。降低层厚至单层可使材料的物理化学性质发生根本改变,从而优化催化性能。近期研究表明,利用自上而下,自下而上的方法,可以实现单层LDHs类材料的合成,但是受限于产量(g级)以及成本设备等问题,目前规模化制备高质量单层LDHs类材料还没有工业案例。成核晶化隔离法是目前唯一规模化合成纳米LDHs的工业化方法,具有成本低,产量可吨级放大等优点。本综述从合成方法、表征手段、应用三个角度讨论了单层及超薄LDHs的精准调控,详细论述了近期关于单层及超薄LDHs合成突破以及LDHs的规模化生产进展,并对其性能进行了总结,为后续设计高性能单层LDHs提供思路。

SLC7A11基因在恶性肿瘤中的研究进展

SLC7A11为溶质载体家族成员之一,该基因编码胱氨酸/谷氨酸反转运体xc-系统的轻链亚基SLC7A11(又称xCT)。 SLC7A11通过介导胱氨酸摄取和谷氨酸释放促进谷胱甘肽(glutathione,r-glutamyl cysteingl+glycine,GSH)的 合成,保护细胞免受 氧化应激,维持细胞的氧化还原平衡,阻止脂质过氧化诱导的细胞死亡。SLC7A11在多种恶性肿瘤中过表达,与胶质瘤、乳腺癌、 卵巢癌、肝癌和肺癌等恶性肿瘤的生长、预后、转移和治疗密切相关,为恶性肿瘤新的潜在治疗靶点之一。本文就SLC7A11基因 在恶性肿瘤中的研究进展进行综述。

Ultrafine monolayer Co-containing layered double hydroxide nanosheets for water oxidation

For many two-dimensional(2D)materials,low coordination edges and corner sites offer greatly enhanced catalytic performance compared to basal sites,motivating the search for new synthetic approaches towards ultrathin and ultrafine 2D nanomaterials with high specific surface areas.To date,the synthesis of catalysts that are both ultrathin(monolayer)and ultrafine(lateral size<10nm)has proven extremely challenging.Herein,using a facile ultrasonic exfoliation procedure,we describe the successful synthesis of ultrafine ZnCo-LDH nanosheets(denoted as ZnCo-UF)with a size^3.5 nm and thickness^0.5 nm.The single layer ZnCo-UF nanosheets possess an abundance of oxygen vacancies(Vo)and unsaturated coordination s让es,thereby affording outstanding electrocatalytic water oxidation performance.DFT calculations confirmed that Vo on the surface of ZnCo-UF enhanced H20 adsorption via increasing the electropositivity of the nanosheets.

Tunable Syngas Synthesis from Photocatalytic CO2 Reduction Under Visible-Light Irradiation by Interfacial Engineering

Visible-light-driven CO2 photoreduction to achieve renewable materials,such as syngas,hydrocarbons,and alcohols,is a key process that could relieve environmental problems and the energy crisis simultaneously.Reduction of syngas products with diff erent H2:CO proportions is highly expected to produce high value-added chemicals in the industry.However,the development of technologies employing long-wavelength irradiation to achieve CO2 photoreduction and simultaneous tuning of the resultant H2:CO proportion remains a challenging endeavor.In this work,we carried out interfacial engineering by designing a series of heterostructured layered double-hydroxide/MoS2 nanocomposites via electrostatic self-assembly.The syngas proportion(H 2:CO)obtained from CO2 photoreduction could be modulated from 1:1 to 9:1 by visible-light irradiation(λ>400 nm)under the control of the interface-rich heterostructures.This work provides a cost-eff ective strategy for solar-tofuel conversion in an artificial photosynthetic system and describes a novel route to produce syngas with targeted proportions.

Tuning the selectivity of photoreduction of CO2 to syngas over Pd/layered double hydroxide nanosheets under visible light up to 600 nm

Photocatalytic reduction of CO2 with H2 O to syngas is an effective way for producing high value-added chemical feedstocks such as methanol and light olefins in industry.Nevertheless,the precise control of CO/H2 ratio from photocatalytic CO2 reduction reaction still poses a great challenge for the further application.Herein,we prepared a series of highly efficient heterostructure based on highly dispersed palladium supported on ultrathin Co Al-layered double hydroxide(LDH).In conjunction with a Ru-complex sensitizer,the molar ratios of CO/H2 can be tuned from 1:0.74 to 1:3 under visible-light irradiation(λ>400 nm).More interestingly,the syngas can be obtained under light irradiation atλ>600 nm.Structure characterization and density functional theory calculations revealed that the remarkable catalytic activity can be due to the supported palladium,which improved the charge transfer efficiency.Meanwhile,more H atoms were used to generate H2 on the supported palladium for further tunable CO/H2 ratio.This work demonstrates a new strategy for harnessing abundant solar-energy to produce syngas from a CO2 feedstock.

Scaled-up synthesis of defect-rich layered double hydroxide monolayers without organic species for efficient oxygen evolution reaction

The scaled-up synthesis of organic-free monolayer nanomaterials is highly desirable,especially in obtaining green energy by electrocatalysis.In this study,a method for the scaled-up synthesis of the series of monolayer layered double hydroxides(LDHs)without the addition of organic solvents is reported via the separate nucleation and aging steps process.The resulting monolayer LDHs with the thicknesses of less than 1 nm showed a narrow thickness distribution.X-ray absorption fine-structure revealed that monolayer NiFe-LDH nanosheets have a number of oxygen and metal vacancies defects.As a practical application,monolayer NiFe-LDH nanosheets containing defects showed an enhanced electrocatalytic water oxidation activity compared with that of bulk NiFe-LDH.Density functional theory calculations uncovered that excellent catalytic activity is attributed to vacancies defects.The proposed method is an economical and universally applicable strategy for the scaled-up production of monolayer LDHs.

Rock borehole shear tests in dam foundation of Xiangjiaba hydropower station

Xiangjiaba hydropowcr station is one of the complicated geological conditions of its dam foundation, parameters of rock masses are very important issues. To cascade power stations on the Jinsha River, China. Due to the evaluating the rock mass quality and determining the mechanical address these issues, several groups of rock borehole shear tests （RBSTs） were conducted on the black mudstone in the dam foundation of Xiangjiaba hydropower station in the second construction phase. Forty three groups of shear strengths of black mudstone samples were obtained from RBSTs, and the shear strength parameters （c and f） were calculated using the least squares method. In addition, the limitations and merits of RBST employed in the Xiangjiaba hydropower station were discussed. Test results indicate that the shear strength parameters obtained from RBST have a good correlation with the results from sotmd wave test in borehole. It is believed that RBST has a good adaptability and applicability in geotechnical engineering.

Determination of mechanical parameters for jointed rock masses

Combining with empirical method, laboratory test and numerical simulation, a comprehensive system was presented to determine the mechanical parameters of jointed rock masses. The system has the following four functions: (1) Based on the field investigation of joints, the system can consider rock mass structures, by using network simulation technology. (2) Rock samples are conducted by numerical simulation with the input engineering mechanical parameters of rocks and joints obtained from laboratory tests. (3) The whole stress-strain curve of jointed rock masses under certain normal stress can be plotted from numerical simulation, and then the shear strength parameters of jointed rock masses can be obtained from the whole stress-strain curves under different normal stresses. (4) The statistical values of mechanical parameters of jointed rock masses can be determined according to numerical simulation. Based on the statistical values, combining with engineering experiences and geological investigations, the comprehensive mechanical parameters of jointed rock masses can be achieved finally. Several cases are presented to prove the engineering feasibility and suitability of this system.

基于肾周CT特征结合血清肌酐水平探讨脓毒症伴急性肾损伤的早期识别

目的:探讨脓毒症伴急性肾损伤(AKI)患者入ICU 24 h内的肾周CT影像特征,建立并验证临床-影像诊断模型。方法:回顾性分析东南大学附属中大医院2016年12月至2020年10月收治的336例ICU脓毒症患者,根据患者入ICU的时间,将2016年12月至2019年12月收治的251例脓毒症患者纳入训练组,2020年1月至2020年10月收治的85例脓毒症患者纳入验证组。根据患者是否合并AKI,将训练组患者分为脓毒症不伴AKI组(139例)和脓毒症伴AKI组(112例)。收集与AKI发生相关的临床指标,并分析患者入ICU 24 h内的肾周CT影像指标。对每个变量进行单因素分析,并将P<0.05的变量纳入多因素logistic回归分析,得到与AKI发生独立相关的临床和影像指标,建立并验证临床-影像诊断模型。结果:脓毒症伴AKI组和脓毒症不伴AKI组脓毒症感染部位、实验室指标(血清肌酐升高、血清尿素氮升高、血清碳酸氢盐、估算肾小球滤过率)及急性病生理学和长期健康评价Ⅱ评分比较,差异均有统计学意义(P均<0.05)。影像指标中,脓毒症伴AKI组的左肾周筋膜增厚发生率及左肾周脂肪密度相对百分比均更高、左肾后脂肪厚度更厚(P均<0.05)。多因素logistic回归分析显示血清肌酐升高[比值比(OR)=40.495,95%置信区间(CI)(18.805,87.200),P<0.001]、左侧肾周筋膜增厚[OR=3.437,95%CI(1.597,7.398),P=0.002]均是脓毒症患者伴发AKI的独立危险因素。训练组临床-影像诊断模型的受试者工作特征曲线下面积(AUC)为0.894[95%CI(0.850,0.929),P<0.001],验证组的AUC为0.877[95%CI(0.788,0.938),P<0.001]。结论:脓毒症患者入ICU 24 h内腹部CT平扫特征——左肾周筋膜增厚是脓毒症伴AKI独立危险因素,联合基线血清肌酐水平增高提示脓毒症伴AKI的发生。

Design and modification of metal sulfide-based catalysts for lithiumsulfur batteries

Metal sulfide(MS)have good conductivity,strong adsorption ability,and excellent catalytic activity for the conversion of sulfur species,and thus,show great promise as the catalysts in LieS batteries.However,the relationship between their properties and electrochemical performance is still unclear.Thus,further in-depth discussions are required to improve their design in Li-S batteries.This review systematically summarizes the basic structural and electrochemical properties of MSs and highlights the advantages that guarantee them as high-performance catalysts in Li-S batteries.Then,various modification strategies for MSs to enhance the catalytic activity,efficiency,and stability are also reviewed.At last,future opportunities for MS catalysts in Li-S batteries are proposed.

Biomarkers in aortic dissection:Diagnostic and prognostic value from clinical research

Aortic dissection is a life-threatening condition for which diagnosis mainly relies on imaging examinations,while reliable biomarkers to detect or monitor are still under investigation.Recent advances in technologies provide an unprecedented opportunity to yield the identification of clinically valuable biomarkers,including proteins,ribonucleic acids(RNAs),and deoxyribonucleic acids(DNAs),for early detection of pathological changes in susceptible patients,rapid diagnosis at the bedside after onset,and a superior therapeutic regimen primarily within the concept of personalized and tailored endovascular therapy for aortic dissection.

Wavelength-tunable multi-point pump semiconductor disk laser based on an intra-cavity transmission grating

We report a wavelength-tunable multi-point pump scheme of the semiconductor disk lasers(SDLs).By designing an external cavity of SDL with an intra-cavity transmission grating,multiple pump gain regions share the same resonator.The effect of the intra-cavity grating on the output laser power,wavelength,and beam quality was investigated.The emission wavelength could be tuned over a bandwidth of~18 nm.With multi-point pumping,we achieve the laser output power with almost no loss,and further improvement is limited by the thermal effect.The changes in the beam are due to the mode selectivity by the intra-cavity grating.