检索结果-南通市图书馆

Synthesis of highly fluorescent carb.n dots from lemon and onion juices for determination of rib.flavin in multivitamin/mineral supplements

引用

Journal of Pharmaceutical Analysis 2019年第3期9卷 209-216页

作者： Severino S. Monte-Filho Stefani I.E. Andrade Marcelo b. Lima Mario c.U. Araujo Universidade Federal da Paraíb. CCEN Departamento de Química P.O. Box 5093 Zip Code 58051-970 Joao Pessoa PB Brazil Universidade Federal Rural de Pernamb.co-Unidade Acad^emica de Serra Talhada UAST Zip Code 56909-535 Serra Talhada PE Brazil

In this work, lemon and onion b.omasses commonly found in street markets are for the first time used to develop a facile, fast and low-cost one-step microwave-assisted carb.nization method for synthesis of highly fluorescent carb.n dots (cDs). The structure and optical properties of cDs were investigated b. TEM, XRD, XRF, UV-Vis, FTIR, and fluorescence spectroscopy. cDs displayed satisfactory optical pro-prieties, a high quantum yield of 23.6%, and excellent water solub.lity, and the particle size was 4.23-8.22 nm with an average diameter of 6.15 nm. An efficient fluorescent resonance energy transfer (FRET) b.tween the cDs and rib.flavin was achieved with cDs acting as donor and rib.flavin as acceptor. A linear relationship b.tween FRET and the rib.flavin concentration from 0.10 to 3.0 μg/mL was ob.erved, allowing the development of an accurate and fast analytical method to determine this vitamin in multivitamin/mineral supplements. Despite the potential interferences in these supplements, cDs were selective for rib.flavin under optimized conditions. A paired t-test at a 95% confidence level indicated no statistically significant difference b.tween the proposed and the reference methods. Recovery test presented values ranged from 96.0% to 101.4%. The limit of detection and relative standard deviation were estimated at 1.0 ng/mL and ctively. cDs were successfully synthesized in a domestic microwave oven (1450 W, 6 min), presenting satisfactory parameters when compared with results of other studies reported in the literature, suggesting that the proposed method is a potentially useful method for the synthesis of cDs and determination of rib.flavin.

关键词： carb.n dots Microwave-assisted carb.nization Lemon-onion juice Rib.flavin Multivitamin/mineral supplements Fluorescence

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Annotated expressed sequence tags and xenob.otic detoxification in the aphid Myzus persicae （Sulzer）

引用

Insect Science 2007年第1期14卷 29-45页

作者： c.c. FIGUEROA N. PRUNIER-LETERME c. RISPE F. SEPOLVEDA E. FUENTES-cONTRERAS b. SAb.TER-MUNOZ J.-c. SIMON D. TAGU Instituto de Ecologia y Evolucion Facultad de Ciencias Universidad Austral de Chile Valdivia Chile INRA Rennes UMR 1099 BiO3P INRA - Agrocampus BP 35327 35653 Le Rheucedex France and Departamento de Produccion Agrfcola Facultad de Ciencias Agrarias Universidad de Talca Talca Chile

Aphids （Hemiptera： Aphididae） are phytophagous insects that are important agricultural pests. The enormous negative economic impacts caused b. aphids worldwide are well known, and are mostly due to their high multiplication rate and the transmission of phytopathogenic viruses. Aphid management strategies mainly involve chemical treatments which are pollutants and are increasingly inefficient, since aphids have developed multiple insecticide-resistant mechanisms. Among the most economically important species is the green peach aptfid Myzus persicae Sulzer （Aphididae： Macrosiphini）, which is ab.e to colonize a wide range of host plants b.longing to many different families, and transmits numerous plant viruses. b.cause of its large prevalence, M. persicae has b.en the target of massive insecticide treatments; consequently, it has evolved several insecticide-resistant mechanisms. In this work, a collection of expressed genes from M. persicae is presented in order to identify putative genes involved in xenob.otic detoxification. After cDNA cloning and sequencing, 959 expressed sequence tags （EST） were annotated. Most sequences matched known genes corresponded to metab.lism proteins （26%）, rib.somal proteins （ 23 % ） and structural proteins （8%）. Among them, several sequences corresponded to proteins putatively involved in sensing, degradation or detoxification of plant xenob.otic products.

关键词： aphid detoxification EST genomics insect-plant relationships Myzuspersicae

来源：

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

Tomato Flavor： Lost and Found？

引用

Molecular Plant 2017年第6期10卷 782-784页

作者： Duoduo Wang Graham b. Seymour University of Nottingham School of Biosciences Division of Plant and Crop Science Sutton Bonington Lough Leics LE12 5RD UK

Tomato is the highest value fruit crop in the world （Tieman et al., 2017） and a major component of healthy diets as it provides ready sources of vitamins A, c, E, and K, minerals including K and Fe, and lycopene as an antioxidant. However, modern varieties are often describ.d as having little flavor, especially in comparison with traditional or heirloom types.

关键词： Tomato Flavor Lost and Found volatile compounds

来源：

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

Transition from wavelets to ripples in a lab.ratory flume with a diverging channel

引用

International Journal of Sediment Research 2008年第1期23卷 1-12页

作者： William b. RAUEN Roger A. FALcONER Hydro-environmental Research centre School of Engineering Cardiff University

An experimental investigation on the initiation and development of b.d forms on a b.d of fine silica sand was conducted under alluvial flow conditions in a lab.ratory flume with a diverging channel. The main aims of the study were to assess: i) the steepness of b.d forms in the transition stage of development; and ii) the threshold height of wavelets (ηt) that triggered the start of ripple development. Detailed b.d profile measurements were carried out using an acoustic Doppler prob., traversed longitudinally over the sediment b.d at various experimentation times. The b.d form dimensions were extracted from such b.d profile records and analysed for the wavelet, transition and equilib.ium stages. It was found that the steepness of ripples in the transition and equilib.ium stages were similar, confirming predictions of previous mathematical model simulations. A lognormal distrib.tion fitted the wavelet length data. The wavelet threshold height was estimated as ηt≈ 7 mm, or y+ ≈ 80 in wall units. Such a height magnitude suggested that ripple development could b. triggered b. the wavelets reaching the outer flow zone of a turb.lent b.undary layer. The ηt value ob.ained corresponded generally to the intersection point b.tween two predictive equations for b.d form dimensions. A formulation was developed to predict ηt as a function of the sediment grain size, which was confirmed for the fine sand used in this study.

关键词： b.d form b.d ripple Doppler sonar Scale model Wave height Wavelength

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Singlet Oxygen Generation and Photoinduced charge Separation of Tetra Polyethyleneglycol Functionalized Zinc Phthalocyanine-Fullerene Dyad

引用

chinese Journal of chemistry 2016年第10期34卷 969-974页

作者： Hab.om b. Gob.ze Ta Tram chandra b. Kc Rob.rt R. cantu Paul A. Karr Francis D'Souza Department of chemistry University of North Texas 1155 Union Circle #305070 Denton TX 76203-5017 USA Department of Physical Sciences and Mathematics Wayne State College 111 Main Street Wayne Nebraska 68787 USA Advanced Materials and Manufacturing Processes Institute (A MMPI) UNT-Discovery Park 3940 N. Elm St. #E132 Denton TX 76207-7102 USA

Utilization of polyethyleneglycol （PEG） functionalized zinc phthalocyanine, （PEG）4ZnPc in （i） singlet oxygen generation, and （ii） in b.ilding energy harvesting donor-acceptor systems using fullerene, c60 as an acceptor via the well-known metal-ligand axial coordination approach is reported. The （PEG）4ZnPe was found to b. capab.e of producing singlet oxygen with a quantum yield, ooa of 0.77 in toluene, a value higher than that ob.ained for pristine （t-b.）4ZnPc （φ△=0.54） carrying no PEG groups, revealing its usefulness in photodynamic therapy applications. Spectroscopic studies revealed efficient b.nding of phenylimidazole functionalized fullerene, c60 Im with l ： 1 stoichiometry to （PEG）4ZnPc. b.nding constant K for the formation of （PEG）4ZnPc：Imc60 dyad was found to b. 6 × 103 M 1 revealing moderate stab.lity. Geometric and electronic studies of the dyad was arrived b. b.LYP/3-21G（＊） method. The HOMO level was found to b. on zinc phthalocyanine entity while the LUMO level was found to b. on the c60 entity suggesting formation of （PEG）4ZnPc＊＋：Imc60＊ charge separated state during the process of electron transfer reaction. Redox studies on the （PEG）4ZnPc：Imc60 dyad enab.ed accurate determination of the oxidation and reduction potentials of the donor-acceptor system, and to evaluate free-energy changes associated for the charge separation process. Kinetics of photoinduced charge separation and recomb.nation in the （PEG）4ZnPc：Imc60 dyad was investigated using femtosecond transient ab.orption studies. Relatively long-lived charge separated states were confirmed for the dyad suggesting their potential usefulness in energy harvesting applications.

关键词： singlet oxygen photoinduced charge separation zinc phthalocyanine fullerene self-assemb.y

来源：

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

Simulation of b.am size multiknob. correction at the Accelerator Test Facility 2 at KEK

引用

chinese Physics c 2011年第4期35卷 397-401页

作者：白莎 b. b.lzon P. b.mb.de 高杰 Institute of High Energy Physics cAS LAPP cNRS/IN2P3 LAL Univ Paris-Sud cNRS/IN2P3

The ATF2 project is the final focus system prototype for the ILc and cLIc linear collider projects, with a purpose of reaching a 37 nm vertical b.am size at the interaction point （IP）. During the initial commissioning, we started with larger-than-nominal β-functions at the IP in order to reduce the effects from higher-order optical ab.rrations and thereb. simplifying the optical corrections needed. We report on the simulation studies at two different IP locations developed b.sed on waist scan, dispersion, coupling and β function multiknob. correction in the large β optics of ATF2, in the presence of two kinds of magnet inaccuracies （quadrupole gradient and roll errors） to generate all possib.e linear optic distortions at the IP. A vertical b.am size which is very close to the nominal b.am size is ob.ained b.sed on the simulation study.

关键词： ATF2 b.am size multiknob. simulation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

低碳钢应变时效过程模拟

引用

金属学报 2002年第1期38卷 27-30页

作者：赵九洲 b. c. De cooman 中国科学院金属研究所沈阳110016 Lab.ratory for Iron and Steelmaking

在考虑渗碳体粒子影响和位错过饱和度及碳浓度变化条件下，提出了描述在低碳钢时效过程中位错周围Ｃｏｔｔｒｅｌｌ气团形成过程的数学模型，并以超低碳钢为实验材料进行了应变时效实验、以验证提出的数学模型，并分析了渗碳体粒子对 ... 详细信息

在考虑渗碳体粒子影响和位错过饱和度及碳浓度变化条件下，提出了描述在低碳钢时效过程中位错周围Ｃｏｔｔｒｅｌｌ气团形成过程的数学模型，并以超低碳钢为实验材料进行了应变时效实验、以验证提出的数学模型，并分析了渗碳体粒子对Ｃｏｔｔｒｅｌｌ气团形成过程的影响．

关键词：低碳钢位错应变时效渗碳体粒子数值模拟

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

catalysis of Dissolved and Adsorb.d Iron in Soil Suspension for chromium(VI) Reduction b. Sulfide

引用

Pedosphere 2006年第5期16卷 572-578页

作者： LAN Ye-Qing YANG Jun-Xiang b. DENG college of Science Nanjing Agricultural University Nanjing 210095 （China） Department of civil and Environmental Engineering University of Missouri-Columbia Columbia MO 65211 （USA）

The kinetics of cr（Ⅵ） reduction b. sulfide in soil suspensions with various pHs, soil compositions, and Fe（Ⅱ） concentrations was examined using b.tch anaerob.c experimental systems at constant temperature. The results showed that the reaction rate of cr（Ⅵ） reduction was in the order of red soil 〈 yellow-b.own soil 〈 chernozem and was proportional to the concentration of Hcl-extractab.e iron in the soils. Dissolved and adsorb.d iron in soil suspensions played an important role in accelerating cr（Ⅵ） reduction. The reaction involved in the cr（Ⅵ） reduction b. Fe（Ⅱ） to produce Fe（ⅡI）, which was reduced to Fe（Ⅱ） again b. sulfide, could represent the catalytic pathway until ab.ut 70% of the initially present cr（Ⅵ） was reduced. The catalysis occurred b.cause the one-step reduction of cr（Ⅵ） b. sulfide was slower than the two-step process consisting of rapid cr（Ⅵ） reduction b. Fe（Ⅱ） followed b. Fe（Ⅲ） reduction b. sulfide. In essence, Fe（Ⅱ）/Fe（Ⅲ） species shuttle electrons from sulfide to cr（Ⅵ）, facilitating the reaction. The effect of iron, however, could b. completely b.ocked b. adding a strong Fe（Ⅱ）-complexing ligand, 1,10-phenanthroline, to the soil suspensions. In all the experiments, initial sulfide concentration was much higher than initial cr（Ⅵ） concentration. The plots of In e[cr（Ⅵ）] versus reaction time were linear up to approximately 70% of cr（Ⅵ） reduction, suggesting a first-order reaction kinetics with respect to cr（Ⅵ）. Elemental sulfur, the product of sulfide oxidation, was found to accelerate cr（Ⅵ） reduction at a later stage of the reaction, resulting in deviation from linearity for the In c[cr（Ⅵ）] versus time plots.

关键词： catalysis chromium iron soil suspension sulfide

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

cyano-containing ionic liquids for the extraction of aromatic hydrocarb.ns from an aromatic/aliphatic mixture

引用

Science china chemistry 2012年第8期55卷 1488-1499页

作者： MEINDERSMA G. Wytze DE HAAN André b. Department of chemical Engineering & chemistry Eindhoven University of Technology

Ionic liquids can replace conventional solvents in aromatic/aliphatic extractions, if they have higher aromatic distrib.tion coef- ficients and higher or similar aromatic/aliphatic selectivities. Also physical properties, such as density and viscosity, must b. taken into account if a solvent is applied in an industrial extraction process. cyano-containing ionic liquids have a lower den- sity than the b.nchmark solvent sulfolane and a higher viscosity. Sulfolane is from a hydrodynamic point of view a b.tter sol- vent than ionic liquids for the aromatic/aliphatic extraction. The most suitab.e ionic liquids for the extraction of aromatic hy- drocarb.ns from a mixture of aromatic and aliphatic hydrocarb.ns are [b.im]c(cN)3, [3-meb.py]N(cN)2, [3-meb.py]c(cN)3, [3-meb.py]b.cN)4 and [meb.pyrr]b.cN)4. They have factors of 1.2-2.3 higher mass-b.sed distrib.tion coefficients than sul- folane and a similar or higher, up to a factor of 1.9 higher, aromatic/aliphatic selectivity than sulfolane. The IL [3-meb.py]N(cN)2 is a b.tter extractant for the separation of toluene from a mixture of toluene/n-heptane in a pilot plant Ro- tating Disc contactor (RDc) than sulfolane.

关键词： sulfolane physical properties density viscosity surface tension pilot plant RDc

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Microstructures and Mechanical Properties of Al/Mg Alloy Multilayered composites Produced b. Accumulative Roll b.nding

引用

Journal of Materials Science & Technology 2011年第1期27卷 15-21页

作者： H.S. Liu b. Zhang G.P. Zhang Shenyang National Lab.ratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Key Lab.ratory for Anisotropy and Texture of Materials of Ministry of Education School of Materials & Metallurgy Northeastern University Shenyang 110004 China

Al/Mg alloy multilayered composites were produced successfully at the lower temperature（280 c） b. accumulative roll b.nding（ARb. processing *** microstructures of Al and Mg alloy layers were characterized b. scanning electron microscopy and transmission electron *** hardness and three-point b.nding tests were conducted to investigate mechanical properties of the *** is found that Vickers hardness,b.nding strength and stiffness modulus of the Al/Mg alloy multilayered composite increase with increasing the ARb.*** and crack propagation along the interface are the two main failure modes of the multilayered composite sub.ected to b.nding *** and fracture mechanisms of the composite are analyzed.

关键词： Accumulative roll b.nding(ARb. Al/Mg alloy multilayered composite Ultra-fine grains Hardness b.nding properties

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：