摘要：In present study,four new dammarane-type triterpenoids,namely caffruones A–D(1–4),were isolated from the cherries of Coffea *** structures were elucidated by extensive spectroscopic analysis including 1D,2D NMR(HSQC,HMBC,^(1)H–^(1)H COSY,and ROESY),HRMS and IR *** is the first time that tetracyclic triterpenes have been reported in genus Coffea.

摘要：本文报道了一台结合电喷雾离子源和双反射飞行时间质谱的速度成像光电子能谱仪的研制过程,其可用于开展溶液中负离子的光电子能谱研究.在该装置中,电喷雾离子源产生的负离子由四极杆组成的离子引导系统传输至冷离子阱,并对负离子进行富集和冷却,用于后端的质量选择和光电子能谱探测.该装置的关键技术之一是将双反射质量分析器与Wiley-McLaren离子加速聚焦设计进行了串联:这样可以有效地提高质谱分辨,从而准确地选择目标离子,其质量分辨率(M/△M)可达2000以上.该装置的高分辨光电子速度成像系统采用多极电子透镜设计,对于动能为0.59eV的光电子,其能谱峰的半高宽约为5.8meV,相对分辨率为~0.98%本文对该装置的工作原理,结构设计和性能测试情况进行了详细阐述。

摘要：认识剪切型岩爆的触发机理对地下工程科学设计与安全施工具有重要意义。为揭示隧道围岩(DTR)的剪切触发型岩爆机理,进行了砂岩的双矩形隧道和双圆形隧道物理模型剪切试验。在剪切试验过程中,利用高速摄像机和声发射监测仪对DTR的岩爆过程进行监测和记录,揭示了压剪下DTR的宏观和细观断裂特征;进而建立了5种隧道间距数值模型,分析了压剪下含隧洞试样连续-非连续剪切过程及其触发的岩爆机理;提出了一种新的能量冲击指数(S)来评价剪切型岩爆倾向性。试验结果表明,在剪切试验中,DTR的实时剪切特征、内外破裂特征和微裂纹数演化特征可划分为4个典型阶段:整体剪切压缩阶段(Ⅰ阶段)、以裂纹萌生为主的弹性阶段(Ⅱ阶段)、以裂纹扩展-贯通和剪切岩爆为主的剪切破裂阶段(Ⅲ阶段)和剪切摩擦阶段(Ⅳ阶段)。此外,试验结果还表明DTR在剪切型岩爆发生后可形成对称猫耳形缺口;微裂纹演化过程中DTR经历了裂纹预备阶段(Ⅰ阶段)、裂纹初始增长阶段(Ⅱ阶段)、裂纹快速增长阶段(Ⅲ阶段)和裂纹稳定阶段(Ⅳ阶段)。更重要的是,综合分析发现,双矩形隧道和双圆形隧道触发剪切型岩爆机制存在差别的本质是截面形状导致的结构效应,即双矩形隧道和双圆形隧道应力场分布差异导致断裂行为不同。研究结果有利于加深对剪切型岩爆机理的认识,为岩土工程防治提供理论依据。

摘要：AIM： TO inhibit the expression of vascular endothelial growth factor （VEGF） in colon cancer cell line by RNA interference （RNAi）.METHODS： Followed the service of E-RNAi, we designed and constructed two kinds of shRNA expression vectors aiming at the VEGF gene, then transfected them into colon cancer HT29 cells by lipofectamineTM 2000. The level of VEGF mRNA was investigated by RT-PCR and Northern blotting. The protein expression of VEGF was observed by immunofluoresence staining and Western blotting.RESULTS： We got two kinds of VEGF specific shRNA expression vectors which could efficiently inhibit the expression of VEGF in HT29 cells. RT-PCR, Northern blotting, immunofluoresence staining and Western blotting showed that inhibition rate for VEGF expression was up to 42%, 89%, 73% and 82%, respectively.CONCLUSION： The expression of VEGF can be inhibited by RNA interference in HT29 cells.

摘要：Both of planar and mesoporous architectures prevail for perovskite solar cells(PSCs).However,it is still an open question how the architecture affects the performance of *** inconsistent results in the references often create *** particular,the specific roles of mesoporous frameworks are yet to be well elaborated and require further *** this study,we carefully compared the properties of perovskite films and the device performances for both architectures to unravel the roles of mesoporous TiO2 framworks in CH3NH3PbI3 *** detailed characterizations of structural,microscopic,optical and electrical properties revealed that the presence of mesoporous TiO2 framework contributed to enlarged perovskite crystal sizes,enhanced light harvesting,efficient electron extration and suppressed charge *** a result,compared with the planar device,the mesoporous device yielded an improved power conversion efficiency of 18.18%,coupled with a reduced *** study reveals the benefits of mesoporous TiO2 framework in PSCs and provides the guidance for the design and optimization of architectures for high-performance devices.

摘要：Aims Bee-pollinated flowers are rarely red,presumably because bees(which lack red receptors)have difficulty detecting red *** the response of bees to red colour has been investigated in lab experiments,most stimuli have been pure red,while the subtle diversity of red as perceived by humans(human-red)has received very limited *** we test the hypothesis that ultraviolet(UV)reflected from human-red flowers enhances their attractiveness to bees,through increased chromatic *** Using Onosma confertum(Boraginaceae),a plant with UV-reflecting red flowers that are pollinated by bumblebees,we investigated the effects of UV reflection on pollinator responses by conducting phenotypic manipulation experiments in the *** preferences of flower-naïve bumblebees were also *** perception by bumblebees was estimated in terms of chromatic and achromatic contrast,based on two different colour perception *** Findings We found that both natural and flower-naïve bumblebees strongly preferred visiting UV-reflecting targets compared with UV-absorbing *** models show that the UV-reflecting flowers exhibit higher spectral purity and higher chromatic contrast against the foliage background,whereas they have similar achromatic contrast in terms of green receptor *** results indicate that the component of UV reflection increases chromatic contrast in ***,enhancing the visual attractiveness of these red flowers to *** further infer that the secondary reflectance might be a necessary component in human-red flowers that are primarily pollinated by animals without red receptors,such as bees.

摘要：The sharp rise of CO2 in the atmosphere has become a potential threat to global climate, which results from the massive utilization of fossil fuel since the industry revolution. CO2 electroreduction provides us a new possibility of utilizing CO2 as a carbon feedstock for fuel and commercial chemicals generation. In this article, a new method is developed for synthesizing CuInS2 hollow nanostructures through the Kirkendall effect. The CuInS2 hollow nanostructures exhibit excellent catalytic activity for electrochemical reduction of CO2 with particular high selectivity, achieving high faradaic efficiency for HCOOH of 72.8% at -0.7 V. To elucidate the mechanisms, operando electrochemical Raman spectroscopy is employed to examine the CO2 reduction process. This work provides new insights into the design of hollow nanostructures toward electrocatalytic CO2 conversion and offers us an effective and reliable way for real-time investigation of electrochemical CO2 reduction reaction processes.

摘要：In this paper, we propose a new lightweight block cipher named RECTANGLE. The main idea of the design of RECTANGLE is to allow lightweight and fast implementations using bit-slice techniques. RECTANGLE uses an SP-network. The substitution layer consists of 16 4 × 4 S-boxes in parallel. The permutation layer is composed of 3 rotations. As shown in this paper, RECTANGLE offers great performance in both hardware and software environment, which provides enough flexibility for different application scenario. The following are3 main advantages of RECTANGLE. First, RECTANGLE is extremely hardware-friendly. For the 80-bit key version, a one-cycle-per-round parallel implementation only needs 1600 gates for a throughput of 246 Kbits/s at100 k Hz clock and an energy efficiency of 3.0 p J/bit. Second, RECTANGLE achieves a very competitive software speed among the existing lightweight block ciphers due to its bit-slice style. Using 128-bit SSE instructions,a bit-slice implementation of RECTANGLE reaches an average encryption speed of about 3.9 cycles/byte for messages around 3000 bytes. Last but not least, we propose new design criteria for the RECTANGLE *** to our careful selection of the S-box and the asymmetric design of the permutation layer, RECTANGLE achieves a very good security-performance tradeoff. Our extensive and deep security analysis shows that the highest number of rounds that we can attack, is 18(out of 25).

摘要：The performance of a joint data assimilation system（Tan-Tracker）,which is based on the PODEn4 Dvar assimilation method,in assimilating Greenhouse gases Observing SATellite（GOSAT） carbon dioxide（CO2） data,was *** 3D CO2 concentrations and CO2 surface fluxes（CFs） from2010 were simulated using a global chemistry transport model（GEOS-Chem）.TheTan-Tracker system used the simulated CO2 concentrations and fluxes as a background field and assimilated the GOSAT column average dry-air mole fraction of CO2（X（CO2）） data to optimize CO2 concentrations and CFs in the same assimilation *** simulated X（CO2）（X（CO2）Sim）） and assimilated X（CO2）（X（CO2）,TT） data retrieved at different satellite scan positions were compared with GOSAT-observed X（CO2）（X（CO2）,obs）*** average RMSE between the monthly X（CO2）,TT and X（CO2）,Obs data was significantly（30%） lower than the average RMSE between X（CO2）,Sim and X（CO2）,Obs）.Specifically,reductions in error were found for the positions of northern Africa（the Sahara）,the Indian peninsula,southern Africa,southern North America,and western *** difference between the correlation coefficients of the X（CO2）,Sim）and X（CO2）,Obs and those of the X（CO2）Π）,TT and X（CO2）,Obs was only *** general,the Tan-Tracker system performed very well after assimilating the GOSAT data.

摘要：High-temperature proton exchange membrane(HT-PEM)fuel cells offer more advantages than low-temperature PEM fuel *** ideal characteristics of HT-PEMs are high conductivities,low-humidity operation conditions,adequate mechanical properties,and competitive *** molecular moieties,such as benzimidazole,benzothiazole,imide,and ether ether ketone,have been introduced to polymer chain backbones to satisfy the application requirements for *** most common sulfonated polymers based on the main chain backbones have been employed to improve the *** group/chain engineering,including the introduction of SO_(3)^(-) on the side chain,grafting,branching,and crosslinking,has been widely applied to HTPEMs to further improve their proton conductivity,thermal stability,and mechanical ***,phosphoric acid-doped polybenzimidazole is the most successful polymer material for application in *** compositing/blending modification methods of polymers are effective in obtaining high PA-doping levels and superior mechanical *** this review,the current progress of various membrane materials used for HT-PEMs is *** synthesis and performance characteristics of polymers containing specific moieties in the chain backbones applied to HT-PEMs are discussed *** modification approaches and their deficiencies associated with HT-PEMs are analyzed and *** and future challenges are also presented.