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81.
Campos-Suñol MJ Domínguez-Vidal A Ayora-Cañada MJ De la Torre-López MJ 《Analytical and bioanalytical chemistry》2008,391(3):1039-1048
Different analytical techniques were used for microstructural and compositional analysis of the ochre-coloured patinas that appear on the calcarenite substrate of monuments in the historical settings of Úbeda and Baeza (Spain). Optical microscopy, scanning electron microscopy–energy dispersive x-ray spectrometry (SEM-EDX), x-ray diffraction, Raman spectroscopy and attenuated total reflection–Fourier transform infrared spectroscopy (ATR-FTIR) were employed and a critical comparison of their experimental requirements, strengths and weaknesses is presented. The study focussed on two churches in Úbeda where patinas were widespread in ornamental elements. These films contained calcite as the principal component, and traces of dolomite and feldspars. Clear identification of calcium oxalate, mainly in the form of whewellite, was achieved by infrared and Raman spectroscopic studies. Results from texture, distribution and composition of the patinas in ornamental elements suggest that ancient treatments were applied for protection of Renaissance façades and consolidation of weathered older façades. The patinas were seldom found on supporting elements. Their different composition, apatite was found together with oxalates, and location may suggest a biogenic origin here. Gypsum crusts were sometimes found over the patinas. 相似文献
82.
83.
84.
E. Iller H. Polkowska-Motrenko W. Łada D. Wawszczak M. Sypuła K. Doner M. Konior J. Milczarek J. Żołądek J. Ráliš 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(1):83-86
Studies of zirconium tungstate gels for production of 188W/188Re generators using tungsten of natural isotopic abundance irradiated in a moderate flux nuclear reactor have been carried
out. Composites of WO3–ZrO2 have been synthesized by Complex Sol–Gel Process developed in INCT and other techniques. Different proportions of metal oxides
and temperature were applied. Elution profiles of columns filled with gel samples irradiated in nuclear reactor have been
studied using as an eluent 0.9% NaCl solution. Purity of 188Re fraction and efficiency of elution were determined. Ageing effect on elution efficiency was also examined. It was found
that the best elution performance showed zirconium tungstate gel prepared in 110 °C or 500 °C in which molar ratio of metal
oxides was 1:2. 相似文献
85.
Analysis of antibiotics in fish samples 总被引:1,自引:0,他引:1
F. Cañada-Cañada A. Muñoz de la Peña A. Espinosa-Mansilla 《Analytical and bioanalytical chemistry》2009,395(4):987-1008
The use of antibiotics in food-producing animals has generated considerable interest because the widespread administration
of these drugs may lead to the development of resistant human pathogens. A large increase in the demand for seafood products
has occurred in the last century. This has led to a concomitant increase in high-intensity aquaculture methods, characterized
by high stock density and volume, and the heavy use of formulated feeds containing antibiotics, among other substances. Therefore,
accurate and sensitive determination of antibiotic residues is now a necessity. In order to protect human health, the European
Union and other regulatory authorities worldwide have established maximum residue limits (MRL) for antibiotic residues in
animal products entering the human food chain. This paper reviews the most recent methods for analysis of antibiotic residues
in fish. 相似文献
86.
María Antonia Serrano Javier Cañada Juan Carlos Moreno Members of the Research Group of Solar Radiation of Valencia 《Photochemistry and photobiology》2010,86(3):716-721
UV exposure is considered to be one of the most important risk factors in skin cancers, mainly in outdoor occupational or recreational activities. Outdoor athletes such as cyclists receive regular and significant solar UV erythemal radiation (UVER). The aim of this work was to quantify UVER exposure of amateur cyclists over the course of several days in their training schedules. To quantify UVER exposure of this group, dosimeters (Viospor) were attached at the top of the helmet in the course of their training. The study took place in Valencia, Spain, in June to July 2008 and February to March 2009, and involved a group of five cyclists over a period of 4 days for each period. The mean 2-day personal UV exposure was 32.24 ± 4.14 SED (standard erythema dose) in summer and 11.30 ± 5.36 SED in the winter period. One SED is defined as an effective radiant exposure of 100 J m−2 when weighted with the International Commission on Illumination (CIE) erythemal response function. The mean exposure ratio (ER) of cyclists was 0.37 ± 0.04 in summer and 0.40 ± 0.11 in winter. The cyclists received the highest UVER exposure in the summer period, but in both training periods UVER exposure was in excess of occupational and recreational guidelines, indicating that protective measures are very necessary. 相似文献
87.
We study the existence of solution for nonlinear problems at resonance under Dirichlet boundary conditions. We deal with PDE's
as well as systems of ODE's. The nonlinear terms considered are periodic functions: in particular, the problem is strongly
resonant at infinity. By means of variational methods, we prove nondegeneracy under some hypotheses on the nonlinearities.
Received: 31 October 2003, Accepted: 12 July 2004, Published online: 8 February 2005
Mathematics Subject Classification (2000):
34B15, 35B34, 35J20
The authors have been supported by the Ministry of Science and Technology of Spain (BFM2002-02649), and by J. Andalucía (FQM
116) 相似文献
88.
Przemysław Zalewski Judyta Cielecka-Piontek Piotr Garbacki Anna Jelińska Marta Karaźniewicz-Łada 《Chromatographia》2013,76(7-8):387-391
The stability-indicating LC assay method was developed and validated for quantitative determination of cefcapene pivoxil in the presence of degradation products formed during forced degradation studies. An isocratic RP-HPLC method was developed with a Lichrospher RP-18 (250 mm × 4.6 mm, 5 μm) column and the mobile phase composed of 45 volumes of acetonitrile and 55 volumes of mixture composed of citric acid 10 mmol L?1 and potassium chloride 18 mmol L?1. The flow rate of the mobile phase was 1 mL min?1. Detection wavelength was 270 nm and temperature was 30 °C. Cefcapene pivoxil, similar to other cephalosporins, was subjected to stress conditions of degradation in aqueous solutions including hydrolysis, oxidation, and thermal degradation. The method was validated with regard to linearity, accuracy, precision, selectivity, and robustness. The method was applied successfully for the determination of cefcapene pivoxil during kinetic studies in aqueous solutions (pH and thermal degradation) and in solid state (oxidative, thermal, and radiolytic degradation). 相似文献
89.
Luis Calle Dr. Virginia Roldós Prof. Dr. F. Javier Cañada María Laura Uhrig Alejandro J. Cagnoni Verónica E. Manzano Oscar Varela Prof. Dr. Jesus Jiménez‐Barbero 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(13):4262-4270
Herein, we describe the use of thioglycosides as glycosidase inhibitors by employing novel modifications at the reducing end of these glycomimetics. The inhibitors display a basic galactopyranosyl unit (1→4)‐bonded to a 3‐deoxy‐4‐thiopentopyranose moiety. The molecular basis of the observed inhibition has been studied by using a combination of NMR spectroscopy and molecular modeling techniques. It is demonstrated that these molecules are not recognized by Escherichia coli β‐galactosidase in their ground‐state conformation, with a conformational selection process taking place. In fact, the observed conformational distortion depends on the chemical nature of the compounds and results from the rotation around the glycosidic linkage (variation of Φ or Ψ) or from the deformation of the six‐membered ring of the pentopyranose. The bound conformations of the ligand are adapted in the enzymatic pocket with a variety of hydrogen‐bond, van der Waals, and stacking interactions. 相似文献
90.
A. Deptuła T. Olczak W. Łada B. Sartowska F. Croce L. Giorgi A. Di Bartolomeo A. Brignocchi 《Journal of Sol-Gel Science and Technology》2003,26(1-3):201-206
The spinel LiMn2O4 and layered oxides LiNi
x
Co1 – x
O2 (x = 1; 0.75; 0) have been prepared by Complex Sol-gel Process (CSGP). The appropriate sol compositions were obtained from acetate aqueous solution of metals containing ascorbic acid by alkalizing it with aqueous ammonia. Gels were produced from the systems by evaporation of water and other volatilies at elevated temperatures. A very intense foaming was observed during the heating at the temperatures higher than 140°C. To avoid foaming in the course of the final thermal treatment, a very long (lasting several days) soaking step was found necessary. However pretreated materials exhibit self-ignition at temperature range 320–500°C dependent on socking conditions. The dependence of self-ignition temperature on carbon content in bed as well as on specific surface has not been proved. Final thermal transformation of gel to solid was studied by TG, DTA, XRD, and IR methods. It was observed that final compounds are formed faster from precursors which did not contain Ni (e.g. LiMn2O4 and LiCoO2), while Li carbonate is not formed in these systems. In contrast, in Li-Ni(Co)-O the formation of Li(or Ni)CO3 was always proved. In addition, during the thermal treatment Ni species are partially reduced even to metallic phase. This effect evidently restrains the formation of pure layered oxides phase. Electrochemical properties of carbonate free compounds are definitely better than of those containing CO3. 相似文献