检索结果-南通市图书馆

一种基于Flory-Huggins理论的等温吸附模型——用于分析小麦粉的水分吸附

在线全文

学校读者我要写书评

暂无评论

食品工业科技 2025年第1期46卷 114-120页

作者：李望铭马荣琨贾庆超徐娜孔欣欣魏笑笑郑州科技学院食品科学与工程学院河南郑州450064 郑州轻工业大学食品与生物工程学院河南郑州450002

本文基于Flory-Huggins方程提出一种水分等温吸附模型,该模型采用Langmuir模型表示结合水的吸附,其余水分在干物质-结合水体系中的吸附遵循Flory-Huggins方程,并采用橡胶弹性理论的幻影模型计算弹性作用对水分化学势的贡献。采用动态水... 详细信息

本文基于Flory-Huggins方程提出一种水分等温吸附模型,该模型采用Langmuir模型表示结合水的吸附,其余水分在干物质-结合水体系中的吸附遵循Flory-Huggins方程,并采用橡胶弹性理论的幻影模型计算弹性作用对水分化学势的贡献。采用动态水分吸附分析仪测定了小麦粉在20、30、40℃时的吸湿及解吸平衡水分,对所提出的模型进行分析验证。结果表明,采用本文提出的等温吸附模型能够很好描述小麦粉的水分等温吸附特性,预测的Flory-Huggins相互作用参数χ在0.86~1.52之间,大分子交联浓度在3000~6400 mol/m3之间,说明所提出的模型是合理的。基于该模型的分析显示,温度对平衡水分含量的影响主要归结为对Langmuir水含量的影响,在中低水分活度时混合效应是决定化学势的主要因素,而在高水分活度时弹性效应的贡献不容忽略。

关键词：水分吸附 Flory-Huggins 理论 Langmuir 吸附橡胶弹性化学势小麦粉

维普期刊数据库博看期刊

Fast growth of graphene on SiO2/Si substrates by atmospheric pressure chemical vapor deposition with floating metal catalysts

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2016年第6期59卷 707-712页

作者： na Liu jia Zhang Yunfeng Qiu Jie Yang PingAn Hu School of Chemical Engineering and Technology Harbin Institute of TechnologyHarbin 150001China Key Laboratory of Micro-systems and Micro-structures Manufacturing Ministry of EducationHarbin Institute of TechnologyHarbin 150080China

graphene on dielectric substrates is essential for its electronic applications. graphene is typically synthesized on the surface of metal and then transferred to an appropriate substrate for fabricating device applications. This post growth transfer process is detrimental to the quality and performance of the as-grown graphene. Therefore, direct growth of graphene films on dielectric substrates without any transfer process is highly desirable. However, fast growth of graphene on dielectric substrates remains challenging. Here, we demonstrate a transfer-free chemical vapor deposition (CVD) method to directly grow graphene films on dielectric substrates at fast growth rate using Cu as floating catalyst. A large area (centimeter level) graphene can be grown within 15 min using this CVD method, which is increased by 500 times compared to other direct CVD growth on dielectric substrate in the literatures. This research presents a significant progress in transfer-free growth of graphene and graphene device applications.

关键词： graphene fast growth dielectric substrates

Microstructure and room temperature fracture toughness of Nb-Si-based alloys with Sr addition

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2024年第8期43卷 3904-3912页

作者： Yong-Lin Huang Li-na jia Bin Kong Yue-Ling guo na Wang School of Materials Science and Engineering Beihang UniversityBeijing 100191China

Nb-Si-based alloys show great potential to surpass the widely used Ni-based *** element Sr is widely applied in aluminum and magnesium alloys,but reports about the effects of Sr on Nb-Si-based alloys are quite ***,Nb-Si-based alloys with nominal compositions of Nb-15Si-24Ti-4Cr-2Al-2Hf-0/0.05/0.15Sr(at%)were prepared by directional solidification and heat *** microstructural characterization and room temperature fracture toughness of Nb-Si-based alloy were systematically *** show that all these alloys consist of Nb_5Si_3 phase embedded within Nb solid solution(Nb_(ss)) *** Nb_(5)Si_(3) phase becomes refined and more discontinuous after adding minor *** for the fracture toughness,0.05 at% and 0.15 at% Sr additions do not cause significant *** discontinuous and refining mechanism of Sr element was studied,and the analysis of toughness decreasing with Sr addition reveals that the size of Nb_(ss) phase plays a crucial role in determining the fracture toughness.

关键词： Nb-Si alloy Refinement Discontinuous Fracture toughness Nb_(ss)

Characteristics of sewage sludge and distribution of heavy metal in plants with amendment of sewage sludge

在线全文

学校读者我要写书评

暂无评论

Journal of Environmental Sciences 2006年第6期18卷 1094-1100页

作者： DAI jia-yin CHEN Ling ZHAO jian-fu MA na Institute of Zoology Chinese Academy of Sciences Beijing 100080 China State Key Laboratory of Pollution Control and Resource Reuse College of Environmental Science and Engineering Tongji University Shanghai 200092 China

In order to better understand land application of sewage sludge, the characterization of heavy metals and organic pollutants were investigated in three different sewage sludges in Shanghai City, China. It was found that the total concentrations of Cd in all of sewage sludge and total concentrations of Zn in Jinshan sewage sludge, as well as those ofZn, Cu, and Ni in Taopu sludge are higher than Chinese regulation limit of pollutants for sludge to be used in agriculture. Leachability of rig in all of studied samples and that of Cd in Taopu sewage sludge exceed the limit values of waste solid extraction standard in China legislation. Based on the characteristics for three kinds of sewage sludge, a pot experiment was conducted to investigate the effect of soil amended with Quyang sewage sludge on the accumulation of heavy *** Begonia semperfloreas-hybr; Ophiopogon japonicas （L.F.） Ker-gaw; Loropetalum chindense-var, rubrum; Dendranthema morifolium; Viola tricolor; A ntirrhinum majas; Buxas radicans Sieb; Viburnum macrocephalum; Osmanthas fragrans Lour; Cinnamomum camphora siebold and Ligustrum lucidum ait. Results showed that 8 species of plant survived in the amended soil, and moreover they flourished as well as those cultivated in the control soil. The heavy metal concentration in plants varied with species, As, Pb, Cd and Cr concentration being the highest in the four herbaceous species studied, particularly in the roots of D. morifolium. These plants, however, did not show accumulator of As, Pb, Cd and Cr. The highest concentration of Ni and Hg was found in the roots ofD. morifolium, followed by the leaves ofB. semperflorens-hybr. Levels of Zn and Cu were much higher in D. morifolium than in the other plant species. D. morifolium accumulated Ni, Hg, Cu and Zn, which may contribute to the decrease of heavy metal contents in the amended soil. Treatment with sewage sludge did not significantly affect the uptake of heavy metals by the L. chindense-var, rubrum, ho

关键词： sewage sludge characteristic lixiviation test pot experiments land application

Correlation between indoor and outdoor corrosion tests for coal train body steel in a coal medium environment

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2022年第9期29卷 1495-1504页

作者： jia-liang Song Jun-hang Chen Pan Yi na-na Chen Zhao-liang Li Kui Xiao Institute of Advanced Materials and Technology University of Science and Technology BeijingBeijing 100083China Corrosion and Protection Center University of Science and Technology BeijingBeijing 100083China China Electric Power Research Institute Beijing 100192China

Q345B carbon steel as well as Q450NQR1 and S500AW weathering steels were subjected to outdoor exposure corrosion tests in coal environments and indoor periodic immersion accelerated corrosion tests with a simulated coal leaching *** corrosion kinetics were studied by the weight loss method,and the corrosion morphology and corrosion product composition were observed and analyzed by scanning electron microscopy,energy-dispersive spectroscopy and X-ray ***,correlation analysis of the indoor and outdoor tests was carried out by the gray correlation analysis *** results show that the relationship between the corrosion weight loss and corrosion time of the three steels conforms to follow the exponent power *** particular,Q450NQR1 steel has the best corrosion *** types of corrosion products and the distribution of elements in the rust layer of the three steels are similar in the indoor and outdoor *** gray correlation degrees of the three steels in the indoor and outdoor tests are all greater than 0.6;thus,the two corrosion tests have a good *** on this,the accelerated simulation test method of the coal leaching solution is determined,and life prediction models of three steels in coal leaching solution are established to simulate the corrosion of the bottom board and side board.

关键词： Coal train body steel Coal environment-Corrosion Outdoor exposure test Indoor acceleration test Correlation

Single track and single layer formation in selective laser melting of niobium solid solution alloy

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

Chinese Journal of Aeronautics 2018年第4期31卷 860-866页

作者： Yueling gUO Lina jia Bin KONg na WANg Hu ZHANg School of Materials Science and Engineering Beihang University

Selective laser melting（SLM） was employed to fabricate Nb-37 Ti-13 Cr-2 Al-1 Si（at%）alloy, using pre-alloyed powders prepared by plasma rotating electrode processing（PREP）. A series of single tracks and single layers under different processing parameters was manufactured to evaluate the processing feasibility by SLM, including laser power, scanning speed, and hatch *** showed that continuous single tracks could be fabricated using proper laser powers and scanning velocities. Both the width of a single track and its penetration depth into a substrate increased with an increase of the linear laser beam energy density（LED）, i.e., an increase of the laser power and a decrease of the scanning speed. Nb, Ti, Si, Cr, and Al elements distributed heterogeneously over the melt pool in the form of swirl-like patterns. An excess of the hatch distance was not able to interconnect neighboring tracks. Under improper processing parameters, a balling phenomenon occurred, but could be eliminated with an increased LED. This work testified the SLMprocessing feasibility of Nb-based alloy and promoted the application of SLM to the manufacture of niobium-based alloys.

关键词： Additive manufacturing Melt pool Niobium alloy Powder metallurgy Selective laser melting

Preparation of Anion Exchange Membrane Based on Imidazolium Functionalized Poly（arylene ether ketone）

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2013年第4期29卷 811-815页

作者： ZHOU Hao ZHANg na MA Wen-jia ZHAO Cheng-ji na Hui Alan g. MacDiarmid Institute College of Chemistry Jilin University Changchun 130012 P. R. China

The authors presented a novel synthetic route for the imidazolium functionalized poly（arylene ether ke- tone）s, derived from an engineering plastics polymer, a poly（arylene ether ketone） with 3,3＇,5,5＇- tetramethyl-4,4＇-dihydroxybiphenyl moiety（PAEK-TM）. The preparation of anion exchange membranes comprised converting benzylic methyl groups to bromomethyl groups by a radical reaction, followed by the functionalization of bromomethylated PAEK with alkyl imidazoles, i.e., methyl, butyl or vinyl imidazole. The structure of imidazolium functionalized PAEK was proved by 1H NMR spectra. A class of flexible and tough membranes was then achieved by subsequent film-forming and anion exchange processes. The water uptake and hydroxide conductivities of mem- branes are comparable or superior to those of quaternary ammonium（QA） anion exchange membranes. This work demonstrated a new route for non-QA anion exchange membrane design, avoiding the chloromethylation reagent and oreciselv controlling the degree and location of imidazolium grouos.

关键词： Anion exchange membrane Poly(arylene ether ketone) Hydroxide conductivity Imidazolium

Synthesis and characterization of biodegradable materials:PDLLA-(MAh-Diol)_n-PDLLA copolymer

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

Chinese Chemical Letters 2007年第5期18卷 613-616页

作者： jia Chen Yuan Liang Wang Mei na Huang Research Center of Bioinspired Material Science and Engineering （BIMSEC） College of Bioengineering Chongqing University Chongqing 400044 PR China

The novel biodegradable copolymer PDLLA-（MAH-Diol）n-PDLLA with unsaturated bond was synthesized by copolymefizing lactide and prepolymer, which was prepared by the polycondensation of maleic anhydride and poly（ethylene glycol）, using ptoluene sulphonic acid as catalyst. The new copolymer has improved hydrophilicity and flexibility. The structure and properties of the novel polymers were studied by FTIR, NMR, gPC-MALLS and DSC.

关键词： Poly(ethylene glycol) Maleic anhydride PDLLA-(MAH-Diol)n-PDLLA Unsaturated bond

Effect of Intermetallic Phases on Corrosion Initiation of AZ91 Alloy With Rare Earth Y Addition

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2015年第5期31卷 504-511页

作者： Li-na Zhang Ruiling jia Dan Li Wei Zhang Feng guo School of Materials Science and Engineering Inner Mongolia University of Technology State Key Laboratory for Corrosion and Protection Institute of Metal ResearchChinese Academy of Sciences

The effect of the rare earth（RE） element Y on the microstructure of AZ91 Mg alloy is investigated.A detailed description of the procedure of identifying the intermetallic phases containing Y in the AZ91 Mg alloy with 0.9 wt%Y addition is *** results shows that there are two different kinds of RE phases in scanning electron microscopy（SEM） *** dispersive spectrum（EDS） analysis shows that one is rich in Y element and the other is rich in Mn *** to the element mapping of electron probe microanalysis（EPMA）.the element Al can be found not only in the β-Mg17Al12phase but also in these two RE phases.X-ray diffraction（XRD） and transmission electron microscopy（TEM） results further confirm one of the two RE phases is AI2Y;the phase of Al10Mn2Y has just been determined by transmission electron microscopy（TEM） instead of XRD probably because it is *** shapes of these two RE intermetallic phases are pretty *** 3D digital microscopy is employed to observe in-situ the effect of the(5 phase and the above two RE intermetallic phases on the corrosion initiation of the *** results show that the corrosion attack of AZ91 Mg alloy without Y addition starts around the eutectic phase β-*** the addition of 0.9 wt%Y,the two kinds of Y-rich intermetallic phases act as cathodic effect and a phase in the adjacent of them was activated and cathodic effect of the β-Mg17Al12phase was inhibited.

关键词： Mg alloy Yttrium Intermetallic phase Corrosion ini