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951.
Heloise?Carrer Juliana?Cortez Laercio?Mantovani?Frare Michelle?Budke?Costa Paulo?Rodrigo?Stival?BittencourtEmail author 《Journal of Thermal Analysis and Calorimetry》2016,125(2):927-934
Polymorphism is the ability of a substance to crystallize into different crystalline states. Different polymorphs vary according to their physical and chemical properties, and therefore, the presence of different crystalline forms of a drug may change some physicochemical properties of certain medicines. The goal of this work was to detect polymorphic forms of a compound used as a drug, bromopride. For the purpose of this study, recrystallizations were carried out from different solvents and at distinct temperatures, with the aim of obtaining different crystalline forms, which were characterized by dynamic thermal analysis (DTA) and X-ray powder diffraction. The samples obtained through recrystallization in different temperature conditions and solvents showed peculiar DTA curves and diffractograms profiles, indicating the presence of crystalline forms distinct from each other. 相似文献
952.
Naira F. Z. Schneider Fabiana C. Geller Lara Persich Lucas L. Marostica Rodrigo M. Pádua Wolfgang Kreis 《Natural product research》2016,30(11):1327-1331
Cardiac glycosides consist of a large family of naturally derived compounds that are clinically used to treat congestive heart failure, and also present anticancer properties. In this study, the cytotoxic effects of two cardenolides, digitoxigenin monodigitoxoside (DGX) and convallatoxin (CON) were screened in four human tumour cell lines. Both compounds showed anti-proliferative effects in all tumour cells, at nanomolar concentrations. Since the human lung cancer cell line A549 was the most sensitive, we investigated the anti-proliferative, anti-migratory and anti-invasive effects of these cardenolides. DGX and CON reduced A549 cell migration, being able to reduce more than 90% of cell invasion. Their effects on the expression of key regulators of metastatic mechanism showed decreased levels of MMP-2, MMP-9 and p-FAK. Both compounds also presented low toxicity for healthy cells. Finally, this work provides the first insights into the effects of these cardenolides on key steps of lung cancer metastasis. 相似文献
953.
This work reports a fast and efficient method for metal extraction in inorganic fertilizers by combining heating and sonication using an ultrasonic bath. Microwave-induced plasma optical emission spectrometry (MIP OES) was applied for the determination of Cd, Cu, Cr, Mn, Pb, and Zn in the extracts. Higher efficiency of metal extraction (∼100% for all metals except to Cd) was obtained for the treatment of 150 mg of fertilizer with 4 mL of 50% (v/v) HCl sonicated for 10 min and heating at 85 °C. Extractions applying only heating did not provide satisfactory results. The proposed procedure is simple and contributes to reduced production of waste in comparison to the official method. 相似文献
954.
Chemical Modification in the Design of Immobilized Enzyme Biocatalysts: Drawbacks and Opportunities
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Nazzoly Rueda Jose C. S. dos Santos Claudia Ortiz Rodrigo Torres Oveimar Barbosa Rafael C. Rodrigues Ángel Berenguer‐Murcia Roberto Fernandez‐Lafuente 《Chemical record (New York, N.Y.)》2016,16(3):1436-1455
Chemical modification of enzymes and immobilization used to be considered as separate ways to improve enzyme properties. This review shows how the coupled use of both tools may greatly improve the final biocatalyst performance. Chemical modification of a previously immobilized enzyme is far simpler and easier to control than the modification of the free enzyme. Moreover, if protein modification is performed to improve its immobilization (enriching the enzyme in reactive groups), the final features of the immobilized enzyme may be greatly improved. Chemical modification may be directed to improve enzyme stability, but also to improve selectivity, specificity, activity, and even cell penetrability. Coupling of immobilization and chemical modification with site‐directed mutagenesis is a powerful instrument to obtain fully controlled modification. Some new ideas such as photoreceptive enzyme modifiers that change their physical properties under UV exposition are discussed. 相似文献
955.
Araújo AS da Rocha LL Tomazela DM Sawaya AC Almeida RR Catharino RR Eberlin MN 《The Analyst》2005,130(6):884-889
After just simple degassing, dilution, pH adjustment and direct flow injection, characteristic fingerprint spectra of beer samples have been obtained by fast (few seconds) electrospray ionization mass spectrometry (ESI-MS) analysis in both the negative and positive ion modes. A total of 29 samples belonging to the two main beer types (lagers and ales) and several beer subtypes from USA, Europe and Brazil could be clearly divided into three groups both by simple visual inspection of their ESI(+)-MS and ESI(-)-MS fingerprints as well as by chemometric treatment of the MS data. Diagnostic ions with contrasting relative abundances in both the positive and negative ion modes allow classification of beers into three major types: P = pale (light) colored (pilsener, pale ale), D = dark colored (bock, stout, porter, mild ale) and M = malt beer. For M beers, samples of a dark and artificially sweetened caramel beer produced in Brazil and known as Malzbiers were used. ESI-MS/MS on these diagnostic beer cations and anions, most of which are characterized as arising from ionization of simple sugars, oligosaccharides, and iso-alpha-acids, yield characteristic tandem mass spectra adding a second and optional MS dimension for improved selectivity for beer characterization by fingerprinting. Direct ESI-MS or ESI-MS/MS analysis can therefore provide fast and reliable fingerprinting characterization of beers, distinguishing between types with different chemical compositions. Other unusual polar components, impurities or additives, as well as fermentation defects or degradation products, could eventually be detected, making the technique promising for beer quality control. 相似文献
956.
Palladium-catalyzed cross-coupling of vinylic tellurides and potassium vinyltrifluoroborate salt: synthesis of 1,3-dienes 总被引:1,自引:0,他引:1
Here we report an ultrasound-assisted synthesis of stereodefined 1,3-dienes by Suzuki-Miyaura cross-coupling reactions of vinylic tellurides and potassium β-styryl trifluoroborate salt. 相似文献
957.
The dimethylacetal of benzaldehyde and some 3, 3,4 and 3,4,5 oxygenated derivatives thereof are regiospecifically deprotonated at the 2-position by alkyl lithiums. The resulting aryl lithiums provide various 2-substituted benzaldehydes in moderate to excellent yields. 相似文献
958.
Reinaldo Calixto de Campos Rodrigo Araújo Gonalves Gisele Birman Tonietto Jos Marcus Godoy Geisamanda Pedrini Brando 《Microchemical Journal》2006,84(1-2):26-30
A new procedure for the speciation analysis of hydride forming elements using GFAAS as detector is proposed. The separation of the species is performed by HPLC and the eluent flow is merged with HCl and NaBH4 solutions moved by peristaltic pumps controlled by a flow injection apparatus. As the species emerges from the column, its respective hydride is formed and carried through the autosampler capillary to an Ir treated graphite tube pre-heated at 300 °C, where it is trapped. After the hydride collection, the autosampler arm is moved from the tube and atomization takes place. The sequence is repeated for the next emerging species. The feasibility of the system was evaluated for the speciation of As (III) and As (V) in waste water samples. The retention times were previously determined using a more concentrated mixed analytical solution and a quartz tube as atomizer. The analytical curves obtained by the proposed procedure showed similar slopes for both species as well as coefficient of regression better than 0.99. Limits of detection were 0.2 ng/mL for both species, 50 times better then the same assembly using a quartz tube atomizer. In the analysis of certified reference materials the sum of the As (III) and As (V) species concentrations were in close agreement with the arsenic concentration certified for total arsenic. 相似文献
959.
Rodrigo A. A. Munoz Cíntia S. Silva Paulo R. M. Correia Pedro V. Oliveira Lúcio Angnes 《Mikrochimica acta》2005,149(3-4):199-204
The determination of metals in lubricating oil has been used as an important means of preventing components failures, to provide environmental information, and to solve criminal issues. In this study derivative potentiometric stripping analysis (DPSA) was used for the simultaneous determination of copper and lead in lubricating oils of vehicular engines. The samples were completely digested in a focused microwave-assisted oven using a powerful oxidant mixture (HNO3, H2SO4, H2O2). The optimized heating program to digest about 1mL of lubricating oil takes 45minutes. The residual carbon content after digestion was below 0.3%m/m for all samples. Copper and lead were also determined by graphite furnace atomic absorption spectrometry (GFAAS), and the results obtained were in good agreement with those obtained by electrochemical measurements. Recoveries of 94–109 and 93–103%, for copper and lead, respectively, were obtained for new and used lubricating oil samples. 相似文献
960.
Juliana da Silva Lima Fonseca Rodrigo Veiga T. de Albuquerque Marluce O. da Guarda Souza 《Reaction Kinetics and Catalysis Letters》2007,91(1):127-130
Textural and catalytic properties of iron oxides impregnated with copper acetate were investigated. In order to get satisfactory
performance in the high temperature shift reaction, 4 impregnation hours are necessary. 相似文献