（乙醇、异丙醇）+N-甲基哌嗪二元体系在101.3 kPa下的汽液平衡

采用改进的Rose釜测定乙醇 N-甲基哌嗪和异丙醇 N-甲基哌嗪两个二元体系在101.3kPa压力下的汽液平衡数据,用折光指数确定汽、液相组成,采用UNIQUAC活度系数模型关联实验数据,计算结果良好。     

Standard molar enthalpies of formation of some vinylfuran derivatives

The standard (p^° = 0.1 MPa) molar enthalpies of combustion, ${\mathrm{\Delta }}_{\text{c}}{H}_{\text{m}}^{°}$, for crystalline 2-furanacrylic acid, 3-furanacrylic acid, and 3-(2-furyl)-2-propenal and for the liquid 2-furanacrylonitrile were determined, at the temperature 298.15 K, using a static bomb combustion calorimeter. For these compounds, the standard molar enthalpies of phase transition, ${\mathrm{\Delta }}_{\text{cr,l}}^{\text{g}}{H}_{\text{m}}^{°}$, at T = 298.15 K, were determined by Calvet microcalorimetry. For the two crystalline furanacrylic acids the vapour pressures as function of temperature were measured by the Knudsen effusion technique and the standard molar enthalpies of sublimation, ${\mathrm{\Delta }}_{\text{cr}}^{\text{g}}{H}_{\text{m}}^{°}$, at T = 298.15 K were derived by the Clausius–Clapeyron equation. The results are as follows:     

913.

In vitro inhibition of protein glycation and advanced glycation end products formation by hydroethanolic extract and two fractions of Simaba trichilioides roots     

Bruno Pereira Motta  Anderson Kiyoshi Kaga  Juliana Oriel Oliveira  Maiara Destro Inacio  Cledson Ferreira da Silva  Paulo Teixeira de Sousa Junior 《Natural product research》2020,34(16):2389-2393

Abstract

Long-term hyperglycemia maintenance is responsible for increased protein glycation and formation of advanced glycation end products (AGEs), both are associated with the onset of diabetes mellitus complications. Efforts have been made to discover new agents having antiglycation potential. The aim of this study was to investigate the effects of the hydroethanolic extract and the ethyl acetate and methanolic fractions of Simaba trichilioides roots on the formation of AGEs. In an in vitro model system of protein glycation, incubations with hydroethanolic extract, ethyl acetate or methanolic fractions of S. trichilioides decreased the fluorescent AGEs, and markers of tyrosine and tryptophan oxidation. Protein crosslinking was reduced in the presence of the ethyl acetate fraction of S. trichilioides. Simaba trichilioides roots seem to be a promising source of compounds having ability to prevent glycoxidation changes, with potential applications in complementary therapies for management of diabetic complications.     

914.

Wheland intermediates: an ab initio valence bond study     

Hadzic M  Braïda B  Volatron F 《Organic letters》2011,13(8):1960-1963

The traditional resonance model for electrophilic attacks on substituted aromatic rings is revisited using high level valence bond (VB) calculations. A large π-donation is found in the X = NH(2) case and a weaker one for the X = Cl case, not only for ortho and para isomers but also for the meta case, which can be explained by considering five (not three) fundamental VB structures. No substantial π-effect is found in the X = NO(2) case, generally viewed as π-attractive.     

915.

Efficient kinetic resolution of (±)-1,2-O-isopropylidene-3,6-di-O-benzyl-myo-inositol with the lipase B of Candida antarctica     

Aline G. Cunha  Angelo A.T. da Silva  Antnio J.R. da Silva  Luzineide W. Tinoco  Rodrigo V. Almeida  Ricardo B. de Alencastro  Alessandro B.C. Simas  Denise M.G. Freire 《Tetrahedron: Asymmetry》2010,21(24):671-2903

(±)-1,2-O-Isopropylidene-3,6-di-O-benzyl-myo-inositol is a relevant starting material in the synthesis of inositol phosphates and their analogs. In this study, we disclose our efforts toward an efficient methodology for the kinetic resolution of this compound by lipase B of Candida antarctica (Novozym 435). This reaction selectively affords L-(?)-1,2-O-isopropylidene-5-O-acetyl-3,6-di-O-benzyl-myo-inositol. From a conversion of 34% with EtOAc as an acylating agent, the use of vinyl acetate increased the yield to over 49%, while maintaining a very high ee (>99%). The combination of the latter reagent with TBME as a solvent accelerates the reaction.     

916.

Determination of α‐Lipoic acid on a Pyrolytic Graphite Electrode Modified with Cobalt Phthalocyanine          下载免费PDF全文

Ana Paula M. Ferreira  Laise N. dos Santos Pereira  Iranaldo Santos da Silva  Sônia M. C. N. Tanaka  Auro A. Tanaka  Lúcio Angnes 《Electroanalysis》2014,26(10):2138-2144

In this work voltammetric techniques were explored for quantification of α‐Lipoic acid (ALA) using a pyrolytic graphite electrode modified with cobalt phthalocyanine. Cyclic voltammograms recorded in phosphate buffer solution containing 1×10^?3 mol L^?1 of ALA presented an oxidation peak located at +0.8 V vs. SCE. The modification of the electrode produced a 100 mV shift of the onset oxidation potential to less positive value and a substantial increase in the ALA oxidation current. Among the voltammetric techniques explored, differential pulse voltammetry showed the best performance for quantifications of the analyte in low concentrations. Limits of detection and quantification of ALA obtained corresponds to 3.4×10^?9 mol L^?1 and 1.2×10^?8 mol L^?1, respectively.     

917.

染料在纳米TiO2薄膜表面吸附性能的研究   总被引：11，自引：0，他引：11  

胡智学  戴松元  王孔嘉  徐轶达 《化学研究与应用》2002,14(3):277-279

采用溶胶－凝胶法制备纳米TiO2薄膜，并通过吸附染料形成染料／TiO2复合薄膜。分析了染料与TiO2薄膜的相互关系，利用紫外可见、比表面等技术研究染料在纳米TiO2薄膜表面的吸附性能，并计算出TiO2薄膜对染料的最大吸附率。研究表明，染料溶液浓度、温度以及TiO2薄膜浸泡时间对染料吸附量有着显著的影响，染料的吸附性能直接影响着太阳能电池的光电转换效率。     

918.

Development and validation of an HPLC method for mefloquine hydrochloride determination in tablet dosage form     

Nogueira FH  Goulart Lde P  César Ida C  de Campos LM  Pianetti GA 《Journal of AOAC International》2011,94(4):1089-1093

A simple HPLC method for determination of mefloquine hydrochloride in tablets was developed and validated. The separation was carried out on an Xterra RP18 (250 x 4.6 mm id, 5 pm particle size) analytical column. The mobile phase was 0.05 M monobasic potassium phosphate buffer (pH 3.5)-methanol (40 + 60, v/v). The flow rate and wavelength were set to 1 mL/min and 283 nm, respectively. The method was specific for mefloquine hydrochloride in the presence of hydrolytic, oxidative, and photolytic degradation products. It was also linear, precise, accurate, and robust, being suitable for routine QC analyses and stability studies. The developed HPLC method was compared to a previously described spectrophotometric method.     

919.

Polypropylene/carbon nanotube magnetic composites obtained using carbon nanotubes from sawdust     

Muhammad Nisar  Maria da Graa Sebag Bernd  Luiz Carlos Pinto da Silva Filho  Julian Geshev  Griselda Barrera Galland 《先进技术聚合物》2019,30(2):457-464

Magnetic polypropylene (PP) nanocomposites with different loadings (from 0.5 to 20 wt %) of carbon nanotubes with iron (CNT‐Fe) were fabricated using the melt‐mixing method. The carbon nanotubes were synthesized by pyrolysis of sawdust from the furniture industry. The morphological characterization shows homogenous dispersion of the filler in the polymer matrix. The addition of only 0.5 wt % CNT‐Fe already results in ferromagnetic behavior in the diamagnetic polymer matrix. The thermal properties were investigated using thermogravimetric analysis and differential scanning calorimetry. The results show an increase in the maximum degradation, crystallization, and melting temperatures of the nanocomposites compared with neat PP. The nanocomposites showed improvement in terms of mechanical and oxygen permeability properties. A very significant result of the work is the high remnant magnetization and coercivity values of the nanocomposites at room temperature whereas most of the works on similar systems show magnetic properties only at very low temperatures.     

920.

Salt‐Driven Deposition of Thermoresponsive Polymer‐Coated Metal Nanoparticles on Solid Substrates          下载免费PDF全文

Zhiyue Zhang  Dr. Samarendra Maji  Dr. André B. da Fonseca Antunes  Riet De Rycke  Prof. Richard Hoogenboom  Prof. Bruno G. De Geest 《Angewandte Chemie (International ed. in English)》2016,55(25):7086-7090

Here we report on a simple, generally applicable method for depositing metal nanoparticles on a wide variety of solid surfaces under all aqueous conditions. Noble‐metal nanoparticles obtained by citrate reduction followed by coating with thermoresponsive polymers spontaneously form a monolayer‐like structure on a wide variety of substrates in presence of sodium chloride whereas this phenomenon does not occur in salt‐free medium. Interestingly, this phenomenon occurs below the cloud point temperature of the polymers and we hypothesize that salt ion‐induced screening of electrostatic charges on the nanoparticle surface entropically favors hydrophobic association between the polymer‐coated nanoparticles and a hydrophobic substrate.     

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In vitro inhibition of protein glycation and advanced glycation end products formation by hydroethanolic extract and two fractions of Simaba trichilioides roots

Abstract

Long-term hyperglycemia maintenance is responsible for increased protein glycation and formation of advanced glycation end products (AGEs), both are associated with the onset of diabetes mellitus complications. Efforts have been made to discover new agents having antiglycation potential. The aim of this study was to investigate the effects of the hydroethanolic extract and the ethyl acetate and methanolic fractions of Simaba trichilioides roots on the formation of AGEs. In an in vitro model system of protein glycation, incubations with hydroethanolic extract, ethyl acetate or methanolic fractions of S. trichilioides decreased the fluorescent AGEs, and markers of tyrosine and tryptophan oxidation. Protein crosslinking was reduced in the presence of the ethyl acetate fraction of S. trichilioides. Simaba trichilioides roots seem to be a promising source of compounds having ability to prevent glycoxidation changes, with potential applications in complementary therapies for management of diabetic complications.     

Wheland intermediates: an ab initio valence bond study

The traditional resonance model for electrophilic attacks on substituted aromatic rings is revisited using high level valence bond (VB) calculations. A large π-donation is found in the X = NH(2) case and a weaker one for the X = Cl case, not only for ortho and para isomers but also for the meta case, which can be explained by considering five (not three) fundamental VB structures. No substantial π-effect is found in the X = NO(2) case, generally viewed as π-attractive.     

Efficient kinetic resolution of (±)-1,2-O-isopropylidene-3,6-di-O-benzyl-myo-inositol with the lipase B of Candida antarctica

(±)-1,2-O-Isopropylidene-3,6-di-O-benzyl-myo-inositol is a relevant starting material in the synthesis of inositol phosphates and their analogs. In this study, we disclose our efforts toward an efficient methodology for the kinetic resolution of this compound by lipase B of Candida antarctica (Novozym 435). This reaction selectively affords L-(?)-1,2-O-isopropylidene-5-O-acetyl-3,6-di-O-benzyl-myo-inositol. From a conversion of 34% with EtOAc as an acylating agent, the use of vinyl acetate increased the yield to over 49%, while maintaining a very high ee (>99%). The combination of the latter reagent with TBME as a solvent accelerates the reaction.     

Determination of α‐Lipoic acid on a Pyrolytic Graphite Electrode Modified with Cobalt Phthalocyanine

In this work voltammetric techniques were explored for quantification of α‐Lipoic acid (ALA) using a pyrolytic graphite electrode modified with cobalt phthalocyanine. Cyclic voltammograms recorded in phosphate buffer solution containing 1×10^?3 mol L^?1 of ALA presented an oxidation peak located at +0.8 V vs. SCE. The modification of the electrode produced a 100 mV shift of the onset oxidation potential to less positive value and a substantial increase in the ALA oxidation current. Among the voltammetric techniques explored, differential pulse voltammetry showed the best performance for quantifications of the analyte in low concentrations. Limits of detection and quantification of ALA obtained corresponds to 3.4×10^?9 mol L^?1 and 1.2×10^?8 mol L^?1, respectively.     

染料在纳米TiO2薄膜表面吸附性能的研究

采用溶胶－凝胶法制备纳米TiO2薄膜，并通过吸附染料形成染料／TiO2复合薄膜。分析了染料与TiO2薄膜的相互关系，利用紫外可见、比表面等技术研究染料在纳米TiO2薄膜表面的吸附性能，并计算出TiO2薄膜对染料的最大吸附率。研究表明，染料溶液浓度、温度以及TiO2薄膜浸泡时间对染料吸附量有着显著的影响，染料的吸附性能直接影响着太阳能电池的光电转换效率。     

Development and validation of an HPLC method for mefloquine hydrochloride determination in tablet dosage form

A simple HPLC method for determination of mefloquine hydrochloride in tablets was developed and validated. The separation was carried out on an Xterra RP18 (250 x 4.6 mm id, 5 pm particle size) analytical column. The mobile phase was 0.05 M monobasic potassium phosphate buffer (pH 3.5)-methanol (40 + 60, v/v). The flow rate and wavelength were set to 1 mL/min and 283 nm, respectively. The method was specific for mefloquine hydrochloride in the presence of hydrolytic, oxidative, and photolytic degradation products. It was also linear, precise, accurate, and robust, being suitable for routine QC analyses and stability studies. The developed HPLC method was compared to a previously described spectrophotometric method.     

Polypropylene/carbon nanotube magnetic composites obtained using carbon nanotubes from sawdust

Magnetic polypropylene (PP) nanocomposites with different loadings (from 0.5 to 20 wt %) of carbon nanotubes with iron (CNT‐Fe) were fabricated using the melt‐mixing method. The carbon nanotubes were synthesized by pyrolysis of sawdust from the furniture industry. The morphological characterization shows homogenous dispersion of the filler in the polymer matrix. The addition of only 0.5 wt % CNT‐Fe already results in ferromagnetic behavior in the diamagnetic polymer matrix. The thermal properties were investigated using thermogravimetric analysis and differential scanning calorimetry. The results show an increase in the maximum degradation, crystallization, and melting temperatures of the nanocomposites compared with neat PP. The nanocomposites showed improvement in terms of mechanical and oxygen permeability properties. A very significant result of the work is the high remnant magnetization and coercivity values of the nanocomposites at room temperature whereas most of the works on similar systems show magnetic properties only at very low temperatures.     

Salt‐Driven Deposition of Thermoresponsive Polymer‐Coated Metal Nanoparticles on Solid Substrates

Here we report on a simple, generally applicable method for depositing metal nanoparticles on a wide variety of solid surfaces under all aqueous conditions. Noble‐metal nanoparticles obtained by citrate reduction followed by coating with thermoresponsive polymers spontaneously form a monolayer‐like structure on a wide variety of substrates in presence of sodium chloride whereas this phenomenon does not occur in salt‐free medium. Interestingly, this phenomenon occurs below the cloud point temperature of the polymers and we hypothesize that salt ion‐induced screening of electrostatic charges on the nanoparticle surface entropically favors hydrophobic association between the polymer‐coated nanoparticles and a hydrophobic substrate.