The Probability Density Function Related to Shallow Cumulus Entrainment Rate and Its Influencing Factors in a Large-Eddy Simulation

The process of entrainment-mixing between cumulus clouds and the ambient air is important for the development of cumulus clouds.Accurately obtaining the entrainment rate(λ)is particularly important for its parameterization within the overall cumulus parameterization scheme.In this study,an improved bulk-plume method is proposed by solving the equations of two conserved variables simultaneously to calculateλof cumulus clouds in a large-eddy simulation.The results demonstrate that the improved bulk-plume method is more reliable than the traditional bulk-plume method,becauseλ,as calculated from the improved method,falls within the range ofλvalues obtained from the traditional method using different conserved variables.The probability density functions ofλfor all data,different times,and different heights can be well-fitted by a log-normal distribution,which supports the assumed stochastic entrainment process in previous studies.Further analysis demonstrate that the relationship betweenλand the vertical velocity is better than other thermodynamic/dynamical properties;thus,the vertical velocity is recommended as the primary influencing factor for the parameterization ofλin the future.The results of this study enhance the theoretical understanding ofλand its influencing factors and shed new light on the development ofλparameterization.

Morphological disruption and visual tuning alterations in the primary visual cortex in glaucoma(DBA/2J)mice

Glaucoma is a leading cause of irreve rsible blindness wo rldwide,and previous studies have shown that,in addition to affecting the eyes,it also causes abnormalities in the brain.However,it is not yet clear how the primary visual cortex(V1)is altered in glaucoma.This study used DBA/2J mice as a model for spontaneous secondary glaucoma.The aim of the study was to compare the electrophysiological and histomorphological chara cteristics of neurons in the V1between 9-month-old DBA/2J mice and age-matched C57BL/6J mice.We conducted single-unit recordings in the V1 of light-anesthetized mice to measure the visually induced responses,including single-unit spiking and gamma band oscillations.The morphology of layerⅡ/Ⅲneurons was determined by neuronal nuclear antigen staining and Nissl staining of brain tissue sections.Eighty-seven neurons from eight DBA/2J mice and eighty-one neurons from eight C57BL/6J mice were examined.Compared with the C57BL/6J group,V1 neurons in the DBA/2J group exhibited weaker visual tuning and impaired spatial summation.Moreove r,fewer neuro ns were observed in the V1 of DBA/2J mice compared with C57BL/6J mice.These findings suggest that DBA/2J mice have fewer neurons in the VI compared with C57BL/6J mice,and that these neurons have impaired visual tuning.Our findings provide a better understanding of the pathological changes that occur in V1 neuron function and morphology in the DBA/2J mouse model.This study might offer some innovative perspectives regarding the treatment of glaucoma.

Physiological and molecular bases of the boron deficiency response in tomatoes

Boron is an essential microelement for plant growth.Tomato is one of the most cultivated fruits and vegetables in the world,and boron deficiency severely inhibits its yield and quality.However,the mechanism of tomato in response to boron deficiency remains largely unclear.Here,we investigated the physiological and molecular bases of the boron deficiency response in hydroponically grown tomato seedlings.Boron deficiency repressed the expression of genes associated with nitrogen metabolism,while it induced the expression of genes related to the pentose phosphate pathway,thereby altering carbon flow to provide energy for plants to cope with stress.Boron deficiency increased the accumulation of copper,manganese and iron,thereby maintaining chlorophyll content and photosynthetic efficiency at the early stage of stress.In addition,boron deficiency downregulated the expression of genes involved in cell wall organization and reduced the contents of pectin and cellulose in roots,ultimately retarding root growth.Furthermore,boron deficiency markedly altered phytohormone levels and signaling pathways in roots.The contents of jasmonic acid,jasmonoy1-L-isoleucine,trans-zeatin riboside,abscisic acid,salicylic acid,and SA glucoside were decreased;in contrast,the contents of isopentenyladenine riboside and ethylene precursor 1-aminocyclopropane-1-carboxylic acid were increased in the roots of boron-deficient tomato plants.These results collectively indicate that tomato roots reprogram carbon/nitrogen metabolism,alter cell wall components and modulate phytohormone pathways to survive boron deficiency.This study provides a theoretical basis for further elucidating the adaptive mechanism of tomato in response to boron deficiency.

导电金属有机框架材料在电催化中的成就,挑战和机遇

开发用于各种能量转化过程的新型催化剂对于满足绿色和可持续能源的需求至关重要。由于其具有可调节的晶体结构,显著的化学和物理性质以及稳定性,金属有机骨架(MOFs)已经广泛应用于电化学能量转换领域,比如CO_(2)还原反应、N_(2)还原反应、析氧反应、析氢反应和氧还原反应。更重要的是,MOFs具有可调节的化学环境、孔径和孔隙率,这些性质将促进反应物在多孔网络中的扩散,从而改善其电催化性能。但是,由于高的电荷转移能垒和受限的自由载流子,大多数MOFs展示了差的导电性,阻碍了其多样化应用。在先前的报道中,MOFs常被用作多孔基质来限制纳米颗粒生长或经退火处理作为共掺杂电催化剂。而导电MOFs不仅结合了传统MOFs的优点,还具有电子导电性和高电催化活性,使其无需退火处理就可以通过电子或离子途径实现导电,从而极大提高了电催化性能,这有助于拓宽其在电化学能源领域或其他方面的潜在应用。在一些催化反应中,导电MOFs的催化活性甚至超过了商业化的RuO_(2)催化剂或Pt基催化剂。本文主要总结了构建导电MOFs的机制,并概述了其合成方法,如水/溶剂热合成和界面辅助合成。此外,本文阐述了导电MOFs在电催化应用中的最新研究进展。值得一提的是,导电MOFs的形态和结构可改变底物与MOFs之间的界面接触,从而影响其催化性能,需要进一步深入研究。基于系统的合成策略,在未来可以根据各种电催化反应的需求设计合成更多的导电MOFs。高性能的导电MOF基催化剂将有望获得突破。

Recent Advances in Interface Engineering for Electrocatalytic CO_(2) Reduction Reaction

Electrocatalytic CO_(2) reduction reaction(CO_(2) RR) can store and transform the intermittent renewable energy in the form of chemical energy for industrial production of chemicals and fuels,which can dramatically reduce CO_(2) emission and contribute to carbon-neutral cycle. E cient electrocatalytic reduction of chemically inert CO_(2) is challenging from thermodynamic and kinetic points of view. Therefore,low-cost,highly e cient,and readily available electrocatalysts have been the focus for promoting the conversion of CO_(2). Very recently,interface engineering has been considered as a highly e ective strategy to modulate the electrocatalytic performance through electronic and/or structural modulation,regulations of electron/proton/mass/intermediates,and the control of local reactant concentration,thereby achieving desirable reaction pathway,inhibiting competing hydrogen generation,breaking binding-energy scaling relations of intermediates,and promoting CO_(2) mass transfer. In this review,we aim to provide a comprehensive overview of current developments in interface engineering for CO_(2) RR from both a theoretical and experimental stand-point,involving interfaces between metal and metal,metal and metal oxide,metal and nonmetal,metal oxide and metal oxide,organic molecules and inorganic materials,electrode and electrolyte,molecular catalysts and electrode,etc. Finally,the opportunities and challenges of interface engineering for CO_(2) RR are proposed.

铜基串联催化剂电催化CO_(2)还原的研究进展

化石燃料的燃烧和其他人类活动排放了大量的CO_(2)气体,引发了诸多环境问题。电催化CO_(2)还原反应(CO_(2)RR)可以储存间歇可再生能源,实现人为闭合碳循环,被认为是获得高附加值化学品和燃料的有效途径。电催化CO_(2)RR涉及多个电子-质子转移步骤,其中^(*)CO通常被认为是关键中间体。铜由于对^(*)CO具有合适的吸附能,已被广泛证明是唯一能够有效地将CO_(2)还原为碳氢化合物和含氧化合物的金属催化剂。然而,纯Cu稳定性差、产品选择性低、过电位高,阻碍了工业级多碳产品的生产。构筑Cu基串联催化剂是提高CO_(2)RR性能的一种有前途的策略。本文首先介绍电催化CO_(2)RR的反应路线和串联机理。然后,系统地总结铜基串联催化剂对电催化CO_(2)RR的最新研究进展。最后,提出合理设计和可控合成新型电催化CO_(2)RR串联催化剂面临的挑战和机遇。

Relationships between Cloud Droplet Spectral Relative Dispersion and Entrainment Rate and Their Impacting Factors

Cloud microphysical properties are significantly affected by entrainment and mixing processes.However,it is unclear how the entrainment rate affects the relative dispersion of cloud droplet size distribution.Previously,the relationship between relative dispersion and entrainment rate was found to be positive or negative.To reconcile the contrasting relationships,the Explicit Mixing Parcel Model is used to determine the underlying mechanisms.When evaporation is dominated by small droplets,and the entrained environmental air is further saturated during mixing,the relationship is negative.However,when the evaporation of big droplets is dominant,the relationship is positive.Whether or not the cloud condensation nuclei are considered in the entrained environmental air is a key factor as condensation on the entrained condensation nuclei is the main source of small droplets.However,if cloud condensation nuclei are not entrained,the relationship is positive.If cloud condensation nuclei are entrained,the relationship is dependent on many other factors.High values of vertical velocity,relative humidity of environmental air,and liquid water content,and low values of droplet number concentration,are more likely to cause the negative relationship since new saturation is easier to achieve by evaporation of small droplets.Further,the signs of the relationship are not strongly affected by the turbulence dissipation rate,but the higher dissipation rate causes the positive relationship to be more significant for a larger entrainment rate.A conceptual model is proposed to reconcile the contrasting relationships.This work enhances the understanding of relative dispersion and lays a foundation for the quantification of entrainment-mixing mechanisms.

Exclusive CO_(2)-to-formate conversion over single-atom alloyed Cu-based catalysts

Electrochemical CO_(2) reduction reaction(CO_(2) RR),powered by renewable energy sources,provides an appealing approach to convert emitted CO_(2) to value-added chemicals and fuels and achieve a carbon-neutral cycle.Among various carbon-based products,formic acid(HCOOH) has been considered as a promising liquid hydrogen storage material due to its high energy density and hydrogen content.However,so far,the reported HCOOH-selective catalysts(e.g.,Bi,Sn,In,Pb and Pd) have failed in either activity(<500 mA cm^(-2)) or stability(<20 h),which significantly inhibits the industrialized feasibility of CO_(2) RR.In contrast,Cu takes the advantages of excellent activity and low cost,making it more commercially viable.To date,one of the most challenging issues of Cu-based catalysts lies in unsatisfactory selectivity,that is,tending to produce mixed products rather than specific one,due to the complicated reaction paths involved.Very recently,Zheng et al.have developed a single-atom alloy(SAAs) strategy for the exclusive CO_(2)-to-formate conversion over Cu-based catalysts.The as-prepared Pb single-atom alloyed Cu catalyst(Pb_(1)Cu)(Fig.la) exhibited near unity selectivity towards HCOOH and impressive stability,providing the prospect of industrial production of HCOOH from CO_(2).

Insight into the Effect of Metal Cations in the Electrolyte on Performance for Electrocatalytic CO_(2)Reduction Reaction

This highlight indicates that the local electrostatic interactions between metal cations and key intermediates facilitate the electrocatalytic CO_(2) reduction reaction.Electrocatalytic CO_(2) reduction reaction(CO_(2)RR)has been considered as a promising strategy to achieve a carbon-neutral cycle and produce valuable fuels and feedstocks.

A New Classifier for Imbalanced Data Based on a Generalized Density Ratio Model

Achieving higher true positive rate when decreasing false positive rate is always a great challenge to the imbalance learning community.This work combines penalized empirical likelihood method,lower bound algorithm and Nyströmmethod and applies these techniques along with kernel method to density ratio model.The resulting classifier,density ratio classifier(DRC),is a combination of kernelization,regularization,efficient implementation and threshold moving,all of which are critical to enable DRC to be an effective and powerful method for solving difficult imbalance problems.Compared with other methods,DRC is competitive in that it is widely applicable and it is simple and easy to use without additional imbalance handling skills.In addition,the convergence rate of the estimate of log density ratio is discussed as well.And the results of numerical analysis also show that DRC outperforms other methods in AUC and G-mean score.

三参数冰相云微物理方案在CIESM模式中的应用

由于云的时空尺度非常宽广,云微物理参数化方案一直是气候模式中的薄弱环节.本文借鉴中尺度模式云微物理方案从双参数向三参数扩展的思路方法,发展了联合地球系统模式(Community Integrated Earth System Model,CIESM)三参数冰相云微物理方案,弥补了默认双参数方案不能预报冰晶粒径分布谱形参数(μ)的不足,进而分析了双、三参数方案对气候模拟的影响.模拟结果表明,相较于双参数方案(μ为0),三参数方案预报得出的μ更为合理,其在垂直分布上整体呈现出“高层小低层大”的特点,高层的低值主要是由于冰晶核化以及较大的冰晶粒子沉降后粒子之间相互混合导致的,而低层的高值主要是由于冰晶粒子在沉降过程中的粒子分选机制导致的.与双、三参数方案中μ的差异相呼应,模式模拟的气候平均态出现明显差异,其中三参数方案模拟的总云云量、低云云量、中云云量和总降水相较于双参数方案更接近观测结果,高云云量的误差增大.其中总降水的改进主要是由于高云云量的增加,大气稳定度增加,对流性降水减少.此外,还调整了相关参数,以改善模式对辐射的模拟能力.总之,本文在全球气候模式中评估了双、三参数方案对于模拟气候平均态的不同影响,为气候模式中云微物理方案的发展改进提供了一定的参考意义.

Enhancement of CH_(3)CO^(*) adsorption by editing d-orbital states of Pd to boost C–C bond cleavage of ethanol eletrooxidation

Improving the complete ethanol electrooxidation on Pd-based catalysts in alkaline media has drawn widely attention due to the high mass energy density.However,the weak adsorption energy of CH_(3)CO^(*) on Pd restricts the C–C bond cleavage.Inspired by the molecular orbital theory,we proposed the d-state-editing strategy to construct more unoccupied d-states of Pd for the enhanced interaction with CH_(3)CO^(*) to break C–C bonds.As expected,the reduced number of e_g electrons and more unoccupied d-states of Pd successfully formed on as-prepared porous Rh Au–Pd Cu nanosheets(PNSs).Theoretical calculations show that the optimized d-states of Rh Au–Pd Cu PNS can effectively improve the adsorption of CH_(3)CO^(*) and drastically reduce the energy barrier of C–C bond cleavage,thus boosting the complete oxidation of ethanol.The charge ratio of C_1 pathway on Rh Au–Pd Cu PNSs is 51.5%,more than 2 times higher than that of Pd NSs.Our finding provides an innovative perspective for the design of highly-efficient noble-based electrocatalysts.

Bimetallic phthalocyanine heterostructure used for highly selective electrocatalytic CO_(2) reduction

Heterogeneous molecular catalysts,such as metal phthalocyanines,are efficient electrocatalysts for CO_(2) reduction reaction(CO_(2)RR).However,the rational design and synthesis of a molecular catalyst-based heterostructure for CO_(2)RR remains challenging.Herein,we developed a crystalline bimetallic phthalocyanine heterostructure electrocatalyst(CoPc/FePc HS),which achieved an excellent CO_(2)-to-CO conversion efficiency(99%)and outstanding long-term stability after 10 h of electrocatalysis.Density functional theory calculations revealed that the enhancement of CO_(2)RR performance could be attributed to the distinct electron transfer pattern between FePc and CoPc.The heterostructural engineering in molecular catalysts would inspire a unique approach for improving CO_(2)RR performance.

Analysis of whole genome-wide microRNA transcriptome profiling in invasive pituitary adenomas and non-invasive pituitary adenomas

Background:Dysregulation of microRNAs(miRNAs)plays a critical role during the occurrence and progress of pituitary adenomas(PAs).However,the roles of miRNAs in the invasiveness of PA are poorly understood.This study aims to more comprehensively and specific define the relationship between altered miRNA and PA invasion.Methods:The differential expression of miRNAs(DEMs)between invasive PAs(IPAs)and non-invasive PAs(NPAs)was explored by RNA sequencing and which functions were analyzed by gene ontology(GO)as well as Kyoto Encyclopedia of Genes and Genomes(KEGG).The miRNA-mRNA network was predicted with bioinformatics.Results:We identified 31 upregulated miRNAs and 24 downregulated miRNAs in IPAs compared with NPAs.GO analysis and KEGG pathway analysis showed the DEMs were mainly associated with cell proliferation and cell cycle pathway.In addition,on the count of predicted miRNA-mRNA network,two hub miRNAs were identified.Conclusions:Our results demonstrate the miRNA-mRNA network in detail,which suggest that miRNA may be a promising target in diagnosis and therapy for IPAs.

三参数冰相云微物理方案的构建及在单柱大气模式中的应用

云微物理的参数化对天气及气候的准确模拟至关重要,其中云粒子谱分布特征通过改变云演化发展和云辐射效应,必然进一步影响气候模拟.目前广泛使用的双参数云微物理方案,无法预报云粒子谱分布的谱形参数,阻碍了气候模式对云物理过程的准确描述.鉴于此,本文在单柱大气模式SCAM5.3(Single Column Atmosphere Model,Version 5.3)中增加雷达反射率因子的预报方程,构建了三参数冰相云微物理方案,实现了冰晶粒子谱分布谱形参数的预报.利用该模式,模拟了大气辐射观测计划在1997年夏季实施的为期29 d的观测个例(ARM97),分析了双、三参数方案对云量和辐射的模拟差异.结果表明:首先,三参数方案预报的冰晶粒子谱的谱形参数主要集中在0~4,峰值在2左右,至少有85%的μ都大于默认的0.其次,与双参数方案相比,三参数方案对云量的模拟更接近观测;利用辐射通量密度的观测值进行评估,发现无论是短波还是长波辐射通量密度,三参数方案的误差都比双参数方案小.最后,揭示了三参数方案对云量和辐射模拟效果的改进机理:主要是因为三参数方案减弱了冰晶到雪的自动转化过程,增强了冰晶凝华增长过程,从而增大了冰晶浓度和冰云云量.本文构建的三参数冰相云微物理方案,将有利于增强模式对云-气候反馈等过程的模拟能力.

Two-dimensional covalent organic frameworks for electrocatalysis:Achievements,challenges,and opportunities

Covalent organic frameworks(COFs)represent an emerging class of crystalline porous polymers with high porosity,good stability,and adjustable structure,and their excellent characteristics lay a solid foundation for electrocatalysis.This review systematically introduces the design principles of the catalytic sites in two-dimensional(2D)COF-based electrocatalysts and analyzes the relationship between 2D COF structure and their electrocatalytic performances.In particular,the recent progress in the field of 2D COFs as electrocatalysts is comprehensively summarized.Finally,we discuss the current shortcomings and challenges on tailoring 2D COF for high-performance electrocatalysts in details,and look forward to promoting more researches on 2D COF-based electrocatalysts.

Developing Thick Cardiac Tissue with a Multilayer Fiber Sheet for Treating Myocardial Infarction

Human-induced pluripotent stem cell (hiPSC)-derived cardiac patches have been extensively used for treating myocardialinfarction and have shown potential for clinical application. However, the limited patch thickness can hamper its therapeuticeffect. We previously developed a fibrous scaffold that allowed the formation of well-organized cardiac tissue constructs. Inthe present study, based on the above technology, we developed a three-dimensional multilayer fibrous scaffold with dynamicperfusion, on which approximately 20 million hiPSC-derived cardiomyocytes (CMs) could be seeded in a single step andorganized into 1 mm thick and viable tissue. The multilayer cardiac tissue demonstrated enhanced contractile properties andupregulated cytokine secretion compared with the control group. Notably, when used on the myocardial infarction model,the multilayer group showed improved functional recovery and less fibrosis. These results indicated that the appropriatehiPSC-CM dose requires careful evaluation in developing clinical therapy. The multilayer cardiac tissue group demonstratedsignificant improvement than the control group, indicating that higher doses of transplanted cells may have improvedtherapeutic effects in treating myocardial infarction.

Perspective on machine learning in energy material discovery

To realize the sustainable development of society,advanced materials for energy storage and conversion are urgently needed.For a long time,the development of new materials relies heavily on tedious trial and error experiments,which have long cycles and high costs,far from modern requirements for advanced materials.With the rapid development of supercomputers and the wide application of density functional theory,high-precision first principle theoretical calculation has been widely used in the process of material design.

A comparative study of the anti-fatigue activity of extracts from different parts of Cistanche tubulosa(Schenk)Wight

Objective:To evaluate the anti-fatigue effects of different extracts from Cistanche tubulosa(Schenk)Wight(C.tubulosa,Rou Cong Rong),focusing on central and exercise-induced fatigue in mice.This study investigated the pharmacological effects of the total oligosaccharides,polysaccharides,and phenylethanoid glycosides(CPhGs)extracted from C.tubulosa.Methods: Models of sleep deprivation and forced swimming fatigue were established to simulate central and exercise-induced fatigue.The mice were treated with different extracts of C.tubulosa,and their effects were assessed using behavioral tests to measure exercise capacity,learning,and memory function.Biochemical analyses were performed to evaluate the changes in serum and brain neurotransmitter levels,liver and muscle glycogen storage,and various fatigue-related biomarkers.Results: This study found that treatment with C.tubulosa extract improved exercise capacity,learning,and memory in mice.Total oligosaccharides from C.tubulosa enhanced adrenocorticotropic hormone,cholinesterase,and thyroid-stimulating hormone levels,reduced cortisol levels in central fatigue models,and ameliorated biochemical markers of exercise-induced fatigue,including lowering lactic acid,blood urea nitrogen,and malondialdehyde levels.Among the tested extracts,the total oligosaccharides showed the most comprehensive anti-fatigue effects.Conclusion: The anti-fatigue effects of C.tubulosa,particularly those of its total oligosaccharides,are pronounced in both central and exercise-induced fatigue.These effects are mediated by the regulation of neurotransmitter levels,enhancement of glycogen storage,and improvement of antioxidant enzyme activity,suggesting potential therapeutic benefits in fatigue-related conditions.

滇金丝猴粪便微生物来源的β-半乳糖苷酶基因的表达及酶学性质

[目的]对滇金丝猴粪便微生物来源的β-半乳糖苷酶进行异源表达和纯化,并研究其酶学性质。[方法]从滇金丝猴粪便微生物的宏基因组中克隆出一个β-半乳糖苷酶基因galRBM20_1,对该基因进行异源表达和酶学性质分析。构建含有T7强启动子的pEASY-E2-galRBM20_1质粒,转化至大肠杆菌BL21(DE3),经IPTG诱导表达后进行酶学性质研究。[结果]滇金丝猴粪便来源的β-半乳糖苷酶(galRBM20_1)最适pH为5.0,在pH 4-7之间能保留70%及其以上的活性。最适温度为45℃,在37℃和45℃下耐受1 h,酶活不变。特别的是,该酶具有良好的NaCl稳定性,经1-5 mol/L的NaCl作用1 h后,相对酶活均能超过初始酶活:当NaCl的作用浓度为4 mol/L时,β-半乳糖苷酶相对酶活最高(146%);当NaCl的作用浓度为5 mol/L时,β-半乳糖苷酶的相对酶活仍达到135%。[结论]本研究从滇金丝猴粪便微生物的宏基因库中克隆得到β-半乳糖苷酶基因galRBM20_1,并成功在大肠杆菌BL21(DE3)表达,首次从动物胃肠道宏基因组中获得具有耐盐和转糖基产Galactooligosaccharides(GOS)性能的β-半乳糖苷酶。该酶具有良好的耐盐性,和较广的pH作用范围,使其在食品、生物技术领域和环保方面的发展具有良好的应用价值。