检索结果-南通市图书馆

In situ rapid versatile method for the preparation of zirconium metal-organic framework filters

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2022年第12期65卷 2462-2467页

作者： Hang Wang Xingmao Zhang Ruxin Yao Shuang Zhao Pengfei Zhao Ruile Yang Lin Wang Yichao Huang Tong Wei Xiang Li Zhuangjun Fan Bo Wang School of Materials Science and Engineering China University of PetroleumQingdao266580China Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials Key Laboratory of Cluster ScienceMinistry of EducationSchool of Chemistry and Chemical EngineeringBeijing Institute of TechnologyBeijing100081China Key Laboratory of Magnetic Molecules&Magnetic Information Materials(Ministry of Education) Institute of Chemistry and CultureSchool of Chemistry&Material ScienceShanxi Normal UniversityTaiyuan030006China

The development of the rapid preparation of highly stable metal-organic framework(MOF)-based devices provides the possibility of meeting the increasing demands of MOF in industrial applications.However,MOFs experience poor processability and stable high-valence-metal(Ⅳ)-based MOFs favor forming either thermodynamically stable metal hydroxides or oxides during their growth and nucleation,which hinders their practical applications.Herein,we present a versatile deep eutectic solvent(des)-assisted hot pressing method to in situ rapidly prepare six distinct zirconium-based MOF nanocrystals on fibers(denoted as Zr-MOFilters)within 20 min.A small amount of des promotes MOF precursor contact and accelerates Zr-MOF growth.Temperature and pressure facilitate the formation of Zr-MOFs onto desired substrates.In situ1H nuclear magnetic resonance spectra and time-dependent Fourier-transform infrared spectra were conducted to elucidate the growth of Zr-MOF nanocrystals.As a proof-of-concept,the abilities of Zr-MOFilters for Cr_(2)O_(7)^(2−) and micro(nano)plastics removal have been demonstrated.This strategy paves the way for the rapid fabrication of highly stable MOF-based devices and brings MOFs a step closer to practical application.

关键词： in situ UiO-66 des hot pressing filter pollutant control

A Novel Approach for Security Enhancement of Data Encryption Standard

在线全文

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2023年第6期75卷 5073-5086页

作者： Dawood Shah Tariq Shah Sajjad Shaukat Jamal Mohammad Mazyad Hazzazi Amer Aljaedi Adel R.Alharbi Department of Mathematics Quaid-i-Azam UniversityIslamabadPakistan Department of Mathematics College of ScienceKing Khalid UniversityAbhaSaudi Arabia College of Computing and Information Technology University of TabukTabuk71491Saudi Arabia

Data Encryption Standard(des)is a symmetric key cryptosystem that is applied in different cryptosystems of recent times.However,researchers found defects in the main assembling of the des and declared it insecure against linear and differential cryptanalysis.In this paper,we have studied the faults and made improvements in their internal structure and get the new algorithm for Improved des.The improvement is being made in the substitution step,which is the only nonlinear component of the algorithm.This alteration provided us with great outcomes and increase the strength of des.Accordingly,a novel 6×6 good quality S-box construction scheme has been hired in the substitution phase of the des.The construction involves the Galois field method and generates robust S-boxes that are used to secure the scheme against linear and differential attacks.Then again,the key space of the improved des has been enhanced against the brute force attack.The out-comes of different performance analyses depict the strength of our proposed substitution boxes which also guarantees the strength of the overall des.

关键词： des S-box linear cryptanalysis differential cryptanalysis

Comparison of detached eddy simulation and standard k-ε RANS model for rack-level airflow analysis inside a data center

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Building Simulation 2022年第9期15卷 1595-1610页

作者： Anashusen Saiyad Yogesh Fulpagare Atul Bhargav Mechanical Engineering Energy Systems Research LaboratoryIndian Institute of Technology GandhinagarPalajGandhinagarGJ382355India

High computing demands and data privacy regulations from many countries in the world have resulted in the expansion of data centers.With this,energy consumption by data centers has increased to an alarming level.Data centers are highly dynamic due to time-dependent server heat generation and cold-hot aisle arrangements,making it difficult to have real-time control for efficient thermal management.Traditional cooling strategies based on conservative set points affect energy consumption.Instead of expensive field measurements,CFD analysis of the flow field inside the data center can provide insightful data to assist the heat release from the racks.The detailed rack-level flow field inside the data center is missing in the literature as most of the studies are based on approximate results using the RANS-based k-ε model.However,des-based models have shown the ability to resolve complex flow fields.With this finding,rack-level CFD analysis of the data center is performed using des and standard k-ε techniques.At first,average rack inlet and outlet air temperatures in steady-state were validated with experiments within the accuracy of 1.4℃.The distributions of turbulent kinetic energy and mean velocity inside the cold aisle were examined.The recirculation region in the cold aisle was well-captured by the des and qualitatively validated with the experiments compared to the k-e model.The k-ε model failed to predict SHI,RTI,and/3 metrics,whereas the des model successfully captured recirculation and self-heating of the upper servers.An acceptable trade-off between computational cost and accuracy for the simulations would be a pivotal parameter for the selection of either des or the k-ε model for the data center CFD analysis.The porous media assumption of the servers can bring uncertainties for turbulent quantities and hence further des model for a data center can provide additional insights in this study.

关键词： data center CFD des RANS thermal management

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

低共熔溶剂体系提取中药渣中肉桂醛

化学工程 2023年第4期51卷 22-27页

作者：张荣清刘云云陈海峰陈小燕张宇邱雨心陕西科技大学机电工程学院陕西西安710021 中国科学院广州能源研究所中国科学院可再生能源重点实验室广东广州510640

筛选适合的低共熔溶剂(des)对中药渣疏水性功效成分进行高效提取对提高中药固废物的资源化利用效率有着重要的意义。采用微波辅助低共熔溶剂法对肉桂枝中药渣原料中的肉桂醛进行提取,考察低共熔溶剂类别、固液比、提取时间、摩尔比、提... 详细信息

筛选适合的低共熔溶剂(des)对中药渣疏水性功效成分进行高效提取对提高中药固废物的资源化利用效率有着重要的意义。采用微波辅助低共熔溶剂法对肉桂枝中药渣原料中的肉桂醛进行提取,考察低共熔溶剂类别、固液比、提取时间、摩尔比、提取温度等因素对肉桂醛提取率的影响。结果表明:氯化胆碱与乙二醇组成的des体系中,在氯化胆碱与乙二醇摩尔比为1∶6、固液质量体积比1∶60、提取温度100℃、反应时间90 min的较优条件下肉桂醛的提取率可达到12.64 mg/g,相比传统甲醇提取法提取率增加了45.45%。中性des相比酸性des对功效成分的稳定性和提取效率都具有较佳的效果。氯化胆碱和乙二醇中性des有益于中药渣功效成分的提取和纯化,具有较大的发展潜力。

关键词：中药渣 des 肉桂醛

Non-profiled Deep-Learning-Based Power Analysis of the SM4 and des Algorithms

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Electronics 2021年第3期30卷 500-507页

作者： MA Xiangliang LI Bing WANG Hong WU Di ZHANG Lizhen HUANG Kezhen DUAN Xiaoyi School of Integrated Circuits Tsinghua University National Research Center for Information Technology Security China Cybersecurity Review Technology and Certification Center Trusted Computing and Information Assurance Laboratory Institute of Software Chinese Academy of Sciences University of Chinese Academy of Sciences Department of Electronics and Information Engineering Beijing Electronic Science and Technology Institute

Power analysis methods are commonly used for evaluating the security of cryptographic devices.They are characteristically low-cost and display a high success rate and the ability to obtain important device information, e.g., keys. Given the current wide application of deep-learning technology, there is a growing tendency to incorporate power-analysis technology in development.This study investigates non-profiled deep-learning-based power analysis. The labels used in this attack are uncertain,and the attack conditions required are greatly reduced. We choose the Recurrent neural network(RNN), multilayer perceptron, and convolutional neural network algorithms,which use the same network structure, to recover the keys for the SM4 software and des hardware implementations.We propose combining the RNN algorithm with power analysis, and validate the benefits experimentally. The experimental results show that they all successfully recover the correct key for the SM4 software implementation,although the RNN algorithm by itself achieves a better effect. This conclusion also applies to attacks on the des hardware implementation but is limited to labels based on the bit model.

关键词： Cryptography Data security Neural nets Non-profiled deep learning Power analysis SM4 des Key recovery

Reverse Genetics for Peste des Petits Ruminants Virus: Current Status and Lessons to Learn from Other Non-segmented Negative-Sense RNA Viruses

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Virologica Sinica 2018年第6期33卷 472-483页

作者： Alfred Niyokwishimira Yongxi Dou Bang Qian Prajapati Meera Zhidong Zhang State Key Laboratory of Veterinary Etiological Biology Lanzhou Veterinary Research Institute Chinese Academy of Agricultural Sciences CAAS-ILRI Joint Laboratory for Ruminant Disease Control Lanzhou Veterinary Research Institute Chinese Academy of Agricultural Sciences

Peste des petits ruminants(PPR) is a highly contagious transboundary animal disease with a severe socio-economic impact on the livestock industry, particularly in poor countries where it is endemic. Full understanding of PPR virus(PPRV)pathobiology and molecular biology is critical for effective control and eradication of the disease. To achieve these goals,establishment of stable reverse genetics systems for PPRV would play a key role. Unfortunately, this powerful technology remains less accessible and poorly documented for PPRV. In this review, we discussed the current status of PPRV reverse genetics as well as the recent innovations and advances in the reverse genetics of other non-segmented negative-sense RNA viruses that could be applicable to PPRV. These strategies may contribute to the improvement of existing techniques and/or the development of new reverse genetics systems for PPRV.

关键词： Peste des petits ruminants(PPR) PPRV Reverse genetics Non-segmented negative-sense RNA virus

在斜向非定常流动中由层流向湍流转变对模型尺度螺旋桨性能和压力脉动的影响

在线全文

学校读者我要写书评

暂无评论

哈尔滨工程大学学报（英文版） 2023年第2期22卷 199-218页

作者： Stefano Gaggero University of Genoa Department of ElectricElectronicTelecommunications Engineering and Naval ArchitectureVia Montallegro 1Genoa 16145Italy

In this paper,after the successful applications to open water propeller performance estimations,the influence of transition sensitive and modified mass transfer models tuned to account for the laminar flow in the prediction of the cavitation inception of marine propulsors is investigated from the point of view of the unsteady functioning and induced pressure pulses.The VP1304(also known as PPTC)test case,for which dedicated data were collected during several workshops,is considered first.After preliminary analyses using RANS,also Detached Eddy Simulations(des)are included to better account for the vortex dynamics and its influence on pressure pulses.Similarly to what observed in uniform inflow,results show a better agreement with the available measurements of propeller performances and confirm the reliability of the proposed approaches for unsteady,non-cavitating,model scale propeller predictions.The overall cavitation pattern is improved too by the application of the transition sensitive correction to the mass transfer model,but the complex dynamics of bubble cavitation observed in experiments prevents quantitatively better predictions in terms of thrust/torque breakdown and induced pressure pulses levels regardless the use of RANS or des methods.

关键词： Transition sensitive turbulence models Cavitation Cavitation with laminar flow Mass transfer models Model scale propeller Oblique flow Induced pressure pulses RANS des

des磁性分子印迹材料的制备及其吸附性能研究

在线全文

学校读者我要写书评

暂无评论

DES磁性分子印迹材料的制备及其吸附性能研究

作者：刘帅江苏大学

学位级别：硕士

表面分子印迹技术(SMIT),是以某些有特定作用的基质作为载体,并在其表面进行聚合的技术。聚合得到的表面分子印迹聚合物材料,其识别结合位点基本位于聚合物表面和浅表层,吸附与解吸附比较容易,可同时提高分子印迹材料对目标分子吸附效... 详细信息

表面分子印迹技术(SMIT),是以某些有特定作用的基质作为载体,并在其表面进行聚合的技术。聚合得到的表面分子印迹聚合物材料,其识别结合位点基本位于聚合物表面和浅表层,吸附与解吸附比较容易,可同时提高分子印迹材料对目标分子吸附效果。表面化学接枝法是一种目前较为常用表面印迹技术,即在改性后的载体表面进行表面接枝聚合。己烯雌酚(des)是一种人工合成的雌激素,难降解、易积累,长期摄入对人体健康危害很大。所以对其进入市场的可能含有des的食品,进行含量的检测是非常重要的。本文以des为印迹分子,采用表面分子印迹的方法,对制备条件进行选择和优化,制备磁性和非磁性分子印迹材料,对制备的材料进行表征和分析,并考察其对des的选择性吸附分离性能,主要研究内容如下:1.以六水合三氯化铁为主要原料,采用溶剂热法制备FeO纳米粒子,将反应时间控制为8 h,可制备直径为300 nm左右的纳米粒子;将FeO纳米粒子置于正硅酸乙酯(TEOS)水解液中,当FeO(mg):TEOS(m L)为300:5时,二氧化硅包覆效果较好;通过比较三种单体与印迹分子的结合能力,单体甲基丙烯酸(MAA)可与模板分子des之间形成分子间作用力较强的氢键;单体在引发剂下反应时,反应温度设为65°C时,可以较好地控制聚合反应速度,使聚合物在载体表面更好地包覆;对合成SMIP的单体、模板分子和交联剂进行选择和优化,确定模板分子、功能单体与交联剂之间的摩尔配比为1:4:20。2.利用TEOS水解制备纳米二氧化硅,使用甲基丙烯酰氧基丙基三甲氧基硅烷(MPS)对二氧化硅进行表面官能团的改性,将改性二氧化硅分散在乙腈中,加入摩尔比1:4:20的模板分子、功能单体与交联剂,在热引发剂偶氮二异丁腈(AIBN)作用下,磁力搅拌聚合24 h得到SMIP。合成的SMIP表面有约120 nm厚的分子印迹层,比表面积为357.52 m/g;将SMIP用于des的静态吸附,其最大吸附量为10.4 mg/g;SMIP和SNIP的吸附特性符合Langmuir吸附模型,表明对于目标分子的吸附主要是单分子层吸附;动态吸附结果表明:SMIP对des的吸附主要集中在前60 min,在60 min时达到最大吸附量的90%以上;SMIP的选择性吸附实验表明des、双酚A(BPA)、雌二醇(E2)的印迹因子分别为3.95、1.62、1.4,SMIP对des具有较大的选择性吸附能力;将SMIP重复使用六次以后,吸附量为最大吸附量的92.5%,可重复多次使用。3.将制备的FeO纳米粒子分散在TEOS水解液中,在表面包覆一层二氧化硅;使用MPS对Si O-FeO表面改性,得到MPS-Si O-FeO;将MAA与des以摩尔比4:1加入到乙腈溶剂中进行12小时自组装,然后加入MPS-Si O-FeO、EGDMA和AIBN超声分散30 min,在65℃下机械搅拌反应24 h得到MMIP。制备的MMIP分子印迹聚合物层的厚度约为30 nm;MMIP的饱和磁强度为67.6emu/g,无磁滞现象,矫顽力为零,表现出超顺磁性,在磁铁作用下17秒就可与溶液分离;吸附完成后的分离操作,只需使用磁铁分离即可,简单快捷;室温下,MMIP对des的静态最大吸附量为7.1 mg/g,等温吸附特性符合Langmuir模型。动态吸附结果表明:MMIP吸附量随着时间的增加而增大,在60 min时可以达到最大吸附量的90%以上;选择性吸附实验表明:MMIP对des印迹因子为3.71,表现出对des较大的识别能力;MMIP可以重复使用六次以上,具有良好的可再生性能。

关键词：分子印迹 des 磁性吸附选择性

管萼山豆根总黄酮的提取工艺优化及其抗氧化活性研究

同方学位论文库评论

在线全文

同方学位论文库

学校读者我要写书评

暂无评论

林产化学与工业 2024年第3期44卷 87-96页

作者：雷嘉昕李政莫嘉玮董爱文吉首大学化学化工学院湖南吉首416000 吉首大学林产化工工程湖南省重点实验室湖南张家界427000 吉首大学生物资源与环境科学学院湖南吉首416000 广东省植物资源生物炼制重点实验室广东广州510006

以管萼山豆根的叶为原料,采用微波-超声波辅助低共熔溶剂(des)提取总黄酮,筛选出较优的des体系,在单因素试验的基础上,运用Plackett-Burman和响应面试验优化其提取工艺;并考察了最佳提取工艺下总黄酮对DPPH·、·ABTS^(+)和·OH的清除... 详细信息

以管萼山豆根的叶为原料,采用微波-超声波辅助低共熔溶剂(des)提取总黄酮,筛选出较优的des体系,在单因素试验的基础上,运用Plackett-Burman和响应面试验优化其提取工艺;并考察了最佳提取工艺下总黄酮对DPPH·、·ABTS^(+)和·OH的清除作用。研究结果表明:较优的des溶剂体系为n(氯化胆碱)∶n(三乙二醇)=1∶3,总黄酮的最佳提取工艺条件为提取时间45 min、提取温度74℃、料液比1∶45(g∶mL)、微波功率300 W、des含水量25%、超声波功率300 W,在该条件下叶中总黄酮得率为3.460%;分别采用乙酸乙酯、热乙酸乙酯(_(50)±1)℃、大孔吸附树脂AB-8、NKA-9和D101分离总黄酮,其回收率分别为23.40%、28.09%、88.66%、71.55%和41.86%;AB-8大孔树脂分离所得总黄酮对DPPH·、·ABTS^(+)与·OH的半数抑制质量浓度(IC_(50))值分别为0.01705、0.01835和0.12330 g/L;总黄酮对DPPH·、·ABTS^(+)的清除率显著高于维生素C(V_(c)),而对·OH的清除率略低于V_(c)。进一步分析发现:优化条件下叶总黄酮得率(3.460%)高于茎(2.059%)和根(1.875%),高于单一微波提取(3.377%)和超声波提取(3.390%),低于加热回流提取(3.635%),但所需时间仅为加热回流提取的1/4。

关键词：管萼山豆根总黄酮微波-超声波辅助提取抗氧化活性 des