Effect of preparation method on the bimetallic NiCu/SAPO-11 catalysts for the hydroisomerization of n-octane

The bimetallic NiCu/SAPO-11 catalysts were prepared by co-impregnation, sequential impregnation, coprecipitation, and mechanical mixing methods. Powder X-ray diffraction, nitrogen adsorption-desorption,temperature-programmed desorption of ammonia, transmission electron microscopy, temperatureprogrammed reduction of hydrogen, and X-ray photoelectron spectroscopy were used to characterize the physicochemical properties of the catalysts. The catalytic performance of the catalysts was assessed by the hydroisomerization of n-octane. Results indicated that the conversion of n-octane and selectivity to n-octane isomers were related to the preparation methods of the catalysts. The catalysts with Ni-Cu alloy effectively restrained the hydrogenolysis reaction that decreases the selectivity of isomerization. The catalyst prepared by the mechanical mixing of NiO and CuO hardly formed Ni-Cu alloy, showing obvious hydrogenolysis and low selectivity to n-octane isomers. The unbalance between the metal and acid sites resulted in the low conversion of n-octane and selectivity to n-octane isomers. Among all the catalysts,the catalyst prepared by the co-impregnation method exhibited high catalytic activity and selectivity to n-octane isomers.

Clay nanosheet-mediated delivery of recombinant plasmids expressing artificial miRNAs via leaf spray to prevent infection by plant DNA viruses

Whitefly-transmitted begomoviruses are economically important plant pathogens that cause severe problems in many crop plants,such as tomato,papaya,cotton,and tobacco.Tomato yellow leaf curl virus(TYLCV)is a typical monopartite begomovirus that has been extensively studied,but methods that can efficiently control begomoviruses are still scarce.In this study,we combined artificial microRNA(amiRNA)-mediated silencing technology and clay nanosheetmediated delivery by spraying and developed a method for efficiently preventing TYLCV infection in tomato plants.We designed three amiRNAs that target different regions of TYLCV to silence virus-produced transcripts.Three plant expression vectors expressing pre-amiRNAs were constructed,and recombinant plasmid DNAs(pDNAs)were loaded onto nontoxic and degradable layered double hydroxide(LDH)clay nanosheets.LDH nanosheets containing multiple pDNAs were sprayed onto plant leaves.We found that the designed amiRNAs were significantly accumulated in leaves 7 days after spraying,while the pDNAs were sustainably detected for 35 days after the spray,suggesting that the LDH nanosheets released pDNAs in a sustained manner,protected pDNAs from degradation and efficiently delivered pDNAs into plant cells.Importantly,when the LDH nanosheets coated with pDNAs were sprayed onto plants infected by TYLCV,both the disease severity and TYLCV viral concentration in sprayed plants were significantly decreased during the 35 days,while the levels of H_(2)O_(2) were significantly increased in those plants.Taken together,these results indicate that LDH nanosheets loaded with pDNAs expressing amiRNAs can be a sustainable and promising tool for begomovirus control.

Exploring the salt-and drought-tolerant genes of alfalfa through expression library screening strategy

Salinity and drought stress are major abiotic stresses negatively affecting the growth and productivity of alfalfa(Medicago sativa L.).Exploration of genes exhibiting superior tolerance to salinity and drought stress in alfalfa will help aid target molecular breeding and developing tolerant forages.In this study,we adopted a high-efficient yeast FOX hunting system for the identification of salinity and drought tolerant genes in alfalfa.Based on the Gateway-compatible vector system,a high-quality expression library was constructed,containing 1.3×10^(7) clones with an average size of 1.44 kb.Through heterologous transformation of mixed library plasmid into salt or drought sensitive yeast mutants,monoclonal resistant strains were screened and tolerant genes were captured.Eighteen salinity-tolerance genes were obtained which were involved in several pathways,containing GRAS and zinc finger transcriptional factors,PP2A interaction module,ERVT vesicle transporter and LETM transmembrane protein.Twelve drought tolerance genes were separated,including ERF and SCL transcriptional factors,CIPK and BSK protein kinases,TGL-type ligase,cPGM and cPDL protease.The mRNA transcription levels of these tolerant genes were inducible or suppressible for response to salt or drought stress conditions following quantitative PCR detection,respectively.Furthermore,heterologous transformation of ERVT and CIPK11 can improve the salt and drought stress tolerance in Arabidopsis,which indicates the conservative function of the screening gene in yeast and Arabidopsis.Obtaining these candidate genes can provide new insights for future research with respect to plant salt and drought tolerance.

The Role of Gut Microbiota in the Mechanism of Cognitive Impairment in the Elderly

With the aging in whole world, it has become a great challenge to explore the relationship between the cognitive and behavioral performance of senile dementia and the underlying pathology of the brain. Alzheimer’s disease (AD) is a common age-related and progressive neurodegenerative disease characterized and one of the main causes of senile dementia. The pathogenesis and treatment mechanism of AD are not completely clear. In recent years, it has been found that the Gut microbiota (GM) disorder is related to nervous system diseases. The objective of this review is to summarize the etiology and pathogenyon the role of GM in the development of AD, metabolites of GM and the occurrence of AD, and GM, diabetes and occurrence of AD. Understanding the relationship between GM and AD will help provide possible interventions to improve the structure of GM and prevent AD through different treatments, and it may provide clinicians with a new and more effective way for early diagnosis, prevention and treatment of AD.

Highly sensitive and miniature microfiber-based ultrasound sensor for photoacoustic tomography

A microfiber with large evanescent field encapsulated in PDMS is proposed and demonstrated for ultrasound sensing.The compact size and large evanescent field of microfiber provide an excellent platform for the interaction between optical signal and ultrasound wave,exhibiting a high sensitivity of 3.5 mV/kPa,which is approximately 10 times higher than the single-mode fiber sensor.Meanwhile,a phase feedback stabilization module is introduced into the coherent demodulation system for long-term stable measurement.In addition,a photoacoustic tomography experiment with the microfiber ultrasound sensor is implemented to verify the excellent performance on imaging,with the depth of 12 mm,the highest lateral resolution of 65μm and axial resolution of 250μm,respectively.The highly sensitive microfiber ultrasound sensor provides a competitive alternative for various applications,such as industrial non-destructive testing,biomedical ultrasound and photoacoustic imaging.

Angular extent effect of micromotion target in SAR image by polar format algorithm

Target micromotion not only plays an important role in target recognition but also leads to esoteric characteristics in synthetic aperture radar （SAR） imaging. This paper finds out an interesting phenomenon, i.e. the angular extent effect, in micro-motion target images formulated by the polar format algorithm. A micromotion target takes on multiple pairs of paired echoes （PEs） around the true point, and each PE extends for an angle which is exactly equal to the angular extent of the synthetic aperture, regardless of the micromotion frequency. The effect is derived and interpreted by using the characteristics of Bessel functions. Then it is demonstrated by simulation experiments of a target with different micromotion frequencies. The revelation and interpretation of the effect is highly beneficial to micromotion-target SAR image understanding as wel as target recognition.

Ultra-small Co/CoO_(x) nanoparticles dispersed on N-doped carbon nanosheets for highly efficient electrocatalytic oxygen evolution reaction

In this paper,we report a facile strategy to synthesize Co-BDC-NH2 material,which is used as a precursor towards an excellent OER electrocatalyst by thermal annealing in nitrogen.Ultra-small Co/Co Oxnanoparticles were uniformly dispersed on the rhombus N-doped carbon(NC)nanoflakes.Transmission electron microscopic,X-ray diffraction spectrometric,and X-ray photoelectron spectroscopic analyses revealed the coexistence of metallic Co and Co oxides nanoparticles.It was found that Co/CoO_(x)@NC obtained at 500℃ annealing temperature exhibited the highest electrocatalytic OER activity,with 307 and375 m V overpotential to achieve 10 and 100 m A cm^(-2) current densities.Besides,thanks to the in-situ annealing process,Co/CoO_(x)@NC showed excellent catalytic stability with 97.4%current density retention after 24 h electrolysis at 1.66 V vs.RHE electrode potential.Further investigations revealed that the ultrasmall Co/Co Oxnanoparticles distributed on N-doped carbon template contribute significantly towards OER electrocatalysis through enlarging the activity surface areas and enhancing the intrinsic electrochemical activity due to the presence of metallic Co.

Construction of N-doped carbon frames anchored with Co single atoms and Co nanoparticles as robust electrocatalyst for hydrogen evolution in the entire pH range

The development of low-cost, efficient, and high atomic economy electrocatalysts for hydrogen evolution reaction(HER) in the entire p H range for sustainable hydrogen production is of great importance but still challenging. Herein, we synthesize a highly dispersed N-doped carbon frames(NCFs) anchored with Co single atoms(SAs) and Co nanoparticles(NPs) catalyst by a doping-adsorption-pyrolysis strategy for electrocatalytic hydrogen evolution. The Co SAs-Co NPs/NCFs catalyst exhibits an excellent HER activity with small overpotential, low Tafel slope, high turnover frequency as well as remarkable stability. It also exhibits a superior HER performance in the entire p H range. Combining with experimental and theoretical calculation, we find that Co SAs with Co-N_(3) coordination structure and Co NPs have a strong interaction for promoting synergistic HER electrocatalytic process. The H_(2)O molecule is easily activated and dissociated on Co NPs, while the generated H^(*) is easily adsorbed on Co SAs for HER, which makes the Co SAs-Co NPs/NCFs catalyst exhibit more suitable H adsorption strength and more conducive to the activation and dissociation of H_(2)O molecules. This work not only proposes a novel idea for constructing coupling catalyst with atomic-level precision, but also provides strong reference for the development of high-efficiency HER electrocatalysts for practical application.

Comparison on Chromosome Number among Ussuri Raccoon Dogs with Three Different Coat Colors

[ Objective] This study aimed to lay theoretical foundation for establishing the database of biological characteristics of raccoon dogs with different coat colors. [Method] Reddish-brown ussuri raccoon dogs, wild ussuri raccoon dogs and Jilln white raccoon dogs were used as experimental materials in this study. Chromosome specimens were prepared by peripheral blood lymphocyte culture, to analyze chromosome number of ussuri raccoon dogs with different coat colors. [ Result] Frequencies of cells with diploid chromosome number of 56 in reddish-brown ussuri raccoon dogs and wild ussuri raccoon dogs were 86% and 83% re- spectively, indicating that the chromosome number of reddish-brown ussuri raccoon dogs and wild ussuri raccoon dogs was 56. The frequency of cells with diploid chromosome number of 56 in Jilin white raccoom dogs was 70%, which was lower than that of other two varieties, while the frequency of cells with 2n = 57 was high- er than that of other two varieties. [Conclusion] The chromosome number was 56 for reddish-brown ussuri raccoon dogs and wild ussuri raccoon dogs, and it was 56 or 57 for Jllin white raccoon dogs, which represented pelymorphism.

De novo biosynthesis of liquiritin in Saccharomyces cerevisiae

Liquiritigenin(LG),isoliquiritigenin(Iso-LG),together with their respective glycoside derivatives liquiritin(LN)and isoliquiritin(Iso-LN),are the main active flavonoids of Glycyrrhiza uralensis,which is arguably the most widely used medicinal plant with enormous demand on the market,including Chinese medicine prescriptions,preparations,health care products and even food.Pharmacological studies have shown that these ingredients have broad medicinal value,including anti-cancer and antiinflammatory effects.Although the biosynthetic pathway of glycyrrhizin,a triterpenoid component from G.uralensis,has been fully analyzed,little attention has been paid to the biosynthesis of the flavonoids of this plant.To obtain the enzyme-coding genes responsible for the biosynthesis of LN,analysis and screening were carried out by combining genome and comparative transcriptome database searches of G.uralensis and homologous genes of known flavonoid biosynthesis pathways.The catalytic functions of candidate genes were determined by in vitro or in vivo characterization.This work characterized the complete biosynthetic pathway of LN and achieved the de novo biosynthesis of liquiritin in Saccharomyces cerevisiae using endogenous yeast metabolites as precursors and cofactors for the first time,which provides a possibility for the economical and sustainable production and application of G.uralensis flavonoids through synthetic biology.

Reaction environment self-modification on low-coordination Ni^(2+)octahedra atomic interface for superior electrocatalytic overall water splitting

Large scale synthesis of high-efficiency bifunctional electrocatalyst based on cost-effective and earth-abundant transition metal for overall water splitting in the alkaline environment is indispensable for renewable energy conversion.In this regard,meticulous design of active sites and probing their catalytic mechanism on both cathode and anode with different reaction environment at molecular-scale are vitally necessary.Herein,a coordination environment inheriting strategy is presented for designing low-coordination Ni^(2+)octahedra(L-Ni-8)atomic interface at a high concentration(4.6 at.%).Advanced spectroscopic techniques and theoretical calculations reveal that the self-matching electron delocalization and localization state at L-Ni-8 atomic interface enable an ideal reaction environment at both cathode and anode.To improve the efficiency of using the self-modification reaction environment at L-Ni-8,all of the structural features,including high atom economy,mass transfer,and electron transfer,are integrated together from atomic-scale to macro-scale.At high current density of 500 mA/cm2,the samples synthesized at gram-scale can deliver low hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)overpotentials of 262 and 348 mV,respectively.

Epitaxial growth of hyperbranched Cu/Cu2O/CuO coreshell nanowire heterostructures for lithium-ion batteries

nano 建筑学的小心的设计和期望的活跃材料的聪明的杂交能导致更先进的性质。这里，我们设计了新奇层次分叉 Cu/Cu 2 由联合一个灵巧的热水的方法和随后的控制氧化过程的 O/CuO heteronanostructure。在分支和脊梁之间的好结构和取向附生的关系被高分辨率的传播电子显微镜学调查。而且，分支生长的进化也在 Cu nanowire 表面的渐渐的氧化期间被观察了。试验性的结果建议经由二拍子的圆舞暴露进程要表现到改变湿度以便完成的表面氧化需要优化了核心壳的形成结构化的分叉的建筑学。最后，象在锂离子电池的阳极材料的如此的一个层次框架的功能的 proof-of-concept 被表明。分叉的核心壳 heterostructure 由几个工具改进电池性能：取向附生地成年的分支提供的(i) 为到卷变化的提高的电解质可接近性和高抵抗的一个高表面区域由 Li+ 置闰 / 抽取导致了；(ii ) 有它的明确的异质接面的核心壳结构增加在 lithiation 期间便于有效费用运输的接触区域；(iii ) 铜核心象提供结构的加强一样充当一个当前的收集者。

Dynamic thermal coupling modeling and analysis of wet electro-hydrostatic actuator

The electro-hydrostatic actuator(EHA)used in more electric aircraft(MEA)has been extensively studied due to its advantages of high reliability and high integration.However,this high integration results in a small heat dissipation area,leading to high-temperature problems.Generally,to reduce the temperature,a wet cooling method of using the pump leakage oil to cool the motor is adopted,which can also increase the difficulty of accurately predicting the system temperature in the early design stage.To solve this problem,a dynamic coupling thermal model of a wet EHA is proposed in this paper.In particular,the leakage oil of the pump is used as a coupling item between the electrical system and the hydraulic system.Then,an improved T-equivalent block model is proposed to address the uneven distribution of axial oil temperature inside the motor,and the control node method is applied to hydraulic system thermal modeling.Meanwhile,a dynamic coupling thermal model is developed that enables a dynamic evaluation of the wet EHA temperature.Then,experimental prototypes of wet motor and wet EHA are developed,while the temperature response of the wet motor at different rotation speeds and different loads and the temperature response of the wet EHA at no-load condition were verified experimentally at room temperature,respectively.The maximum temperature difference between the experimental and theoretical results of the wet motor as well as the experimental and theoretical results of the wet EHA is less than 8℃.These test results indicate that the dynamic coupling thermal model is valid and demonstrate that the thermal coupling modeling method proposed in this paper can provide a basis for the detailed thermal design of EHA.

Relationships between climate change, agricultural development and social stability in the Hexi Corridor over the last 2000 years

This case study of the Hexi Corridor, Northwestern China, utilizes statistical methods to estimate quantitatively the interaction at a regional level between climate change, ancient social developments, and political coping strategies over the past 2000 years. The data is sourced from high-resolution reconstructions of climate series(temperature and precipitation), and historical records of cultivated land, war, population, and changes in regional administrative systems. The results show that moisture conditions played a more significant role than temperature in driving land reclamation in the Hexi Corridor. Analysis also showed a negative correlation between war frequency and the area of cultivated land in the Corridor over 20-year time intervals. Population growth was found to have a significant positive correlation with the cultivated land area during the study period. The results indicate that a climate-induced decline in agricultural production and the subsequent fluctuations in population could act as a trigger for social unrest, which is especially true at the mutual decadal time-scales. However, the interaction with administrative reform also suggests that, in the face of social and economic turmoil, a reasonable administrative hierarchy could strengthen the social governance of regional government, and promote social stability and economic development at a regional level. The study substantiates this notion with empirical quantitative evidence.

Targeting folliculin to selectively inhibit mTORC1:a promising strategy for treating nonalcoholic fatty liver disease

In a recent study published in Science,Bridget S.Gosis et al.demonstrate that selective inhibition of the mammalian target of rapamycin complex 1(mTORC1)signaling through deletion of the RagC/D guanosine triphosphatase-activating protein folliculin(FLCN)in mice enhances activation of transcription factor E3(TFE3)in the liver and protects against nonalcoholic fatty liver disease(NAFLD).

Altered vaginal eukaryotic virome is associated with different cervical disease status

Viruses are important components of the human body.Growing evidence suggests that they are engaged in the physiology and disease status of the host.Even though the vaginal microbiome is involved in human papillomavirus(HPV)infection and cervical cancer(CC)progression,little is known about the role of the vaginal virome.In this pilot exploratory study,using unbiased viral metagenomics,we aim to investigate the vaginal eukaryotic virome in women with different levels of cervical lesions,and examine their associations with different cervical disease status.An altered eukaryotic virome was observed in women with different levels of lesions and Lactobacillus profiles.Anelloviruses and papillomaviruses are the most commonly detected eukaryotic viruses of the vaginal virome.Higher abundance and richness of anelloviruses and papillomaviruses were associated with lowgrade squamous intraepithelial lesion(LSIL)and CC.Besides,higher anellovirus abundance was also associated with lactobacillus-depleted microbiome profiles and bacterial community state(CST)type IV.Furthermore,increased correlations between Anelloviridae and Papillomaviridae occurred in the women with increased cervical disease severity level from LSIL to CC.These data suggest underlying interactions between different microbes as well as the host physiology.Higher abundance and diversity of both anelloviruses and papillomaviruses shared by LSIL and CC suggest that anellovirus may be used as a potential adjunct biomarker to predict the risk of HPV persistent infection and/or CC.Future studies need to focus on the clinical relevance of anellovirus abundance with cervical disease status,and the evaluation of their potential as a new adjunct biomarker for the prediction and prognoses of CC.

霾污染天气大气微生物气溶胶特性的研究进展

自从2013年以来,中国霾事件频发,霾污染已经成为全国人民广泛关注的环境问题之一.霾污染的本质是大气细颗粒物污染.大气颗粒物的生物成分(即生物气溶胶)与其化学成分一样,不仅对空气质量和人群健康具有潜在威胁,而且对全球气候变化以及大气物理化学过程也具有间接影响.然而,目前学术界对大气颗粒物的生物成分及其性质的研究相对滞后,尤其是对霾污染天气大气颗粒物中微生物的多样性、丰度及其时空变异特性等基本科学问题认识不足.因此,本文综述了目前霾污染天气大气微生物气溶胶的研究现状,结合我们的研究着重阐述了在不同霾污染程度下生物气溶胶的浓度、粒径分布与群落结构特性,以及空气污染和环境因子对生物气溶胶分布的影响机理等方面存在的问题.最后,给出了未来霾污染过程生物气溶胶研究应主要开展的5个方面的工作展望,以期为深入理解霾天生物气溶胶的来源、变化机理以及评估不同空气质量的健康影响提供参考.

无人机和地面相结合的自然保护地生物多样性监测技术与实践

无人机技术的运用为自然保护地生物多样性监测与研究带来了新的机遇和变革。然而,对自然保护地主要保护对象的关注不足,导致了无人机和地面相结合的监测技术尚未形成。为更好地发挥多种调查监测技术的各自优势,为自然保护地生物多样性管护和监测提供支撑,我们总结了国内外已开展的无人机和地面相结合的监测工作进展,梳理了我国不同类型自然保护地生物多样性保护管理和监测的需求。总的来看,不同类型自然保护地的主要保护对象围绕在生态系统、物种、遗址遗迹等或由上述要素构成的景观资源上;管理目标定位则集中在保护、恢复、科研、宣教、游憩和可持续发展等方面。基于上述需求,我们归纳提出了包括图像识别与分类解译、数据反演与格局分析、数字建模与地表测量、巡护巡检4个类别共计14个专题的无人机和地面相结合的监测技术方案,明确了监测时期与频次、监测指标、监测技术的结合途径以及数据后处理方法等。同时,我们在三江并流世界遗产地云岭片区内选择植物识别、植被长势、景观格局、地表测量以及执法检查等技术专题开展了应用试验。在技术方案取得良好验证结果的同时,实现了对自然保护地生物多样性保护和管理的技术支撑,为未来自然保护地精细化管理提供了技术储备。

鼎湖山南亚热带常绿阔叶林植物功能性状变异与不同垂直层次个体生长的关联

建立植物功能性状与群落动态之间的关联是功能生态学的核心问题之一。本文基于鼎湖山1.44 ha塔吊样地的两次调查数据,通过采集样地内所有4,142株个体的6种植物功能性状,对比分析了个体水平植物功能性状和物种水平功能性状均值对不同垂直层次(灌木层、亚冠层和林冠层)个体生长的影响差异。首先,分析了不同垂直层次下各植物功能性状的变化趋势;其次,计算了不同垂直层次下各植物功能性状的种内和种间变异水平;最后,运用结构方程模型探讨了植物功能性状、光竞争以及地下竞争对不同垂直层次树木生长的影响。结果表明:(1)不同垂直层次下的植物功能性状表现出明显的分异,由灌木层至林冠层,叶面积、比叶面积和能量供求关系指数显著降低,而叶片厚度和叶片干物质含量显著升高;(2)不同垂直层次下植物功能性状的种间变异均大于种内变异,且林冠层的种内功能性状变异均大于灌木层和亚冠层;(3)基于个体水平植物功能性状的结构方程模型较物种水平功能性状均值对生长具有更高的解释程度,且个体水平植物功能性状的引入更有利于提高对灌木层个体生长的预测能力;(4)光竞争和地下竞争主要通过影响功能性状间接影响植物生长。由灌木层至林冠层,同种间的相互作用逐渐减弱,异种间的相互作用逐渐增强。综上,将个体水平植物功能性状纳入分析有助于更好地理解群落的结构和动态。

鼎湖山南亚热带常绿阔叶林叶功能性状沿群落垂直层次的种内变异

探究功能性状沿着环境梯度如何变化一直以来是基于性状的群落生态学的核心问题之一。尽管功能性状存在种内和种间变异,但种内变异沿环境梯度如何变化仍有待探究。本文以鼎湖山南亚热带常绿阔叶林1.44 ha塔吊样地内16个树种的2,820个个体为研究对象,探究4种叶功能性状(比叶面积、叶干物质含量、叶厚度和叶面积)沿群落垂直层次的种内变异。首先,利用随机效应线性模型量化塔吊样地内的种内变异和种间变异;其次,利用Kmeans函数将森林的垂直层次划分为灌木层、亚冠层和林冠层,并通过构建回归模型探究叶功能性状在群落垂直层次中的种内变异格局。最后,应用混合线性模型和单因素方差分析的方法探究叶功能性状沿垂直层次的种内变异是否具有物种依赖性。结果表明:在局域群落中,并非所有叶功能性状的种内变异都低于种间变异;叶功能性状在不同垂直层次的种内变异格局存在显著差异,且种内变异与垂直范围呈正相关;叶功能性状的种内变异具有较强的物种依赖性,因此树种差异相对于小环境解释了更多的性状变异;此外,不同叶功能性状的种内变异沿垂直层次的变化趋势并不一致。本研究发现种内变异对于物种共存具有重要作用。