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1.
L. C. Machado A. A. L. Marins E. J. B. Muri J. A. S. Lacerda V. O. Balthar P. F. Fulvio J. C. C. Freitas 《Journal of Thermal Analysis and Calorimetry》2004,75(2):615-621
This paper presents the reactions of synthesis between the ligand sodium diphenylamine-4-sulfonate and the lanthanum(III)
chloride hydrated. The compounds (LaCl3)2·(C12H10NSO3Na)3·2(CH3CH2OH) (A) and (LaCl3)·(C12H10NSO3Na)·(CH3CH2OH)·12H2O (B) were obtained using the solvents ethanol and methanol (synthesis A) and ethanol and water (synthesis B). The produced
compounds and the ligand were characterized by thermogravimetric and differential thermogravimetric analysis, IR spectroscopy
and elemental analysis of sodium, carbon, hydrogen, nitrogen, sulfur, chlorine and lanthanum, whereas the residues from thermal
decomposition were investigated by X-ray diffractometry.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
2.
Rangel Elidiane C. Cruz Nilson C. da Kayama Milton E. Rangel Rita C. C. Marins Nazir Durrant Steven F. 《Plasmas and Polymers》2004,9(1):1-22
Diamond-like carbon (DLC) films were grown from radiofrequency plasmas of acetylene-argon mixtures, at different excitation powers, P. The effects of this parameter on the plasma potential, electron density, electron temperature, and plasma activity were investigated using a Langmuir probe. The mean electron temperature increased from about 0.5 to about 7.0 eV while the mean electron density decreased from about 1.2 × 109 to about 0.2 × 109 cm–3 as P was increased from 25 to 150 W. Both the plasma potential and the plasma activity were found to increase with increasing P. Through actinometric optical emission spectrometry, the relative concentrations of CH, [CH], and H, [H], in the discharge were mapped as a function of the applied power. A rise in [H] and a fall in [CH] with increasing P were observed and are discussed in relation to the plasma characteristics and the subimplantation model. The optical properties of the films were calculated from ultraviolet-visible spectroscopic data; the surface resistivity was measured by the two-point probe method. The optical gap, E
G, and the surface resistivity, s, fall with increasing P. E
G and s are in the ranges of about 2.0–1.3 eV and 1014–1016 /, respectively. The plasma power also influences the film self-bias, V
b, via a linear dependence, and the effect of V
b on ion bombardment during growth is addressed together with variation in the relative densities of sp2 and sp3 bonds in the films as determined by Raman spectroscopy. 相似文献
3.
Mariana Santos Pinheiro Rita de Cássia Elias Estrela Marins Lúcio Mendes Cabral 《液相色谱法及相关技术杂志》2018,41(5):223-231
Roflumilast is a phosphodiesterase type 4 inhibitor that is administered orally as a long-term, in the clinical treatment of chronic obstructive pulmonary disease and asthma. Launched in 2010 for the European market, it currently does not have an official monograph. Here, a reproducible gradient RP-HPLC method was developed and validated for the separation and determination of Roflumilast in the presence of its six major degradation products. Separation was performed on a C18 analytical column (250?×?4.6?mm, 5?µm) with a mobile phase-A of ACN and a phase-B of ammonium acetate buffer (5?mM, pH 4.2) containing triethylamine (0.5% v/v). The most effective RP-HPLC gradient program was determined to be 0/80, 35/10, 36/80, 40/80 (time in minutes/% mobile phase-B). The flow rate was 1.0?ml/min and the column temperature was 25°C. The success of separation of the degradation products with different chemical characteristics was obtained by extending the time of the gradient, changing the proportion of the mobile phases and increasing the velocity of the flow. Two detectors were evaluated for the identification of degradation products and Roflumilast: a diode-arrary detector and a charged aerosol detector. The inability of the charged aerosol detector to dectect one of the six degradation products indicated that the method developed with RP-HPLC and the diode-array detector was more suitable for Roflumilast analysis. The method was validated according to specificity, linearity, LOD, LOQ, accuracy, precision and robustness. 相似文献
4.
Brito Ciro José Miarka Bianca García-Pastor Teresa Pérez Diego Ignácio Valenzuela Marins Joao Carlos Bouzas Sillero-Quintana Manuel 《Journal of Thermal Analysis and Calorimetry》2021,145(5):2467-2475
Journal of Thermal Analysis and Calorimetry - This study investigated the thermal skin (Tsk) response of lower limbs in older adults with or without osteoarthritis before and after a concurrent... 相似文献
5.
Rivelino M. Cavalcante Márcia V.F. de Andrade Rozane V. Marins Lincoln D.M. Oliveira 《Microchemical Journal》2010,96(2):337-343
An analytical protocol combining a headspace technique with gas chromatography and detection by photoionization detector and flame ionization detector (HS-GC-PID-FID) was developed. This procedure was used to measure volatile organic compounds (VOCs) in environmental aqueous matrices and was applied in determination of VOCs on the coast of Fortaleza, Brazil. At optimum operating conditions, analytical figures of merit such as linearity (R ranged from 0.9983 to 0.9993), repeatability (5.62 to 9.63% and 0.02 to 0.19% for the quantitative and qualitative analyses, respectively), detection limits (0.22 to 7.48 μg L−1) and sensibility were estimated. This protocol favors a fast sampling/sample preparation (in situ), minimizes the use of laboratory material, eliminates the matrix effect from environmental samples, and can be applied to river, estuarine and oceanic waters. The advantage of detectors in series is that a low sensitivity in detection in one is compensated by the other. Toluene was the most abundant VOC in the studied area, with an average concentration of 1.63 μg L−1. It was followed by o-xylene (1.15 μg L−1), trichloroethene (1.08 μg L−1), benzene (0.86 μg L−1), ethylbenzene (0.74 μg L−1), carbon tetrachloride (0.55 μg L−1), m/p-xylene (0.48 μg L−1) and tetrachloroethene (0.46 μg L−1), compounds which are very commonly detected in urban runoff from most cities. The results of the VOC distribution showed that port activity was not the main source of VOCs along the Fortaleza Coast, but that the contribution from urban runoff seemed more significant. 相似文献
6.
The objective of this study was to evaluate the time-course effects of UV-B exposure on expression of genes involved in the DNA repair system of zebrafish ( Danio rerio ) hepatocytes, a highly competent species in terms of damage repair induced by UV radiation. For gene expression analysis (RT-PCR), cells were exposed to 23.3 mJ cm−2 UV-B, which was the dose that affected viable cell number (reduction of 30% when compared with the control group) and produced no visual alteration on cell morphology. The early response observed (6 h) showed induction in the expression of the CDKI gene (cyclin-dependent kinase inhibitor) and genes related to DNA damage repair (mainly XPC and DDB2 ), while the late response observed (24 h) was more related to up-regulation of p53 and genes involved in cell cycle arrest ( gadd45a , cyclinG1 ). In all times analyzed, the anti-apoptotic gene Bcl-2 was down-regulated. Another interesting result observed was the up-regulation of the Apex- 1 gene after UV-B exposure, which could indicate the induction of oxidative lesions in the DNA molecule. In conclusion, these results demonstrate an activation of the DNA repair system in hepatocytes of zebrafish exposed to UV-B radiation, mainly involving the participation of p53. 相似文献
7.
Mixing chloranil with tetrabase in ether solution gives no reaction. The redox reaction, with formation of a blue diphenylmethane dye, occurs only after evaporation of the ether. On this. effect can be based a selective identification of chloranil. It can be carried out as a spot test showing an identification limit of 0.25 γ of chloranil. The authors describe a preliminary test for aromatic compounds, which consists in heating the test material with potassium chlorate and conc. hydrochloric acid and identifying the hereby formed chloranil by means of tetrabase. The investigation of 71 compounds has shown that not all aromatic compounds can be converted to chloranil. but that there exist characteristic exceptions. 相似文献
8.
Richard Marins da Silva Valeria Monteze Guimarães Lizzy Ayra Alcântara Veríssimo Márcia Cristina Teixeira Ribeiro Vidigal Valéria Paula Rodrigues Minim Luis Antonio Minim 《Journal of separation science》2022,45(2):401-410
This study focused on the extraction, purification, and physicochemical characterization of γ-conglutin, a protein present in lupin seeds with properties of reducing blood glucose levels. Total protein was extracted with an alkaline-saline solvent, followed by isoelectric precipitation. Chromatographic purification of the precipitated fraction was performed using a cation exchange supermacroporous cryogel column. Electrophoresis of the eluted fraction from chromatography presented a single band of ∼48 kDa under non-reducing conditions (two bands of ∼30 and ∼17 kDa, under reducing conditions) confirming the success of the purification protocol. Liquid chromatography-tandem mass spectrometry analysis confirmed the identity of the protein as γ-conglutin. The purified γ-conglutin had an isoelectric point of 7.51, β-sheets prevailing as a secondary structure, and denaturation temperature close to 68°C. The outcome of this work showed that γ-conglutin was obtained with a high degree of purity. The proposed purification protocol is simple and can be easily scaled up. 相似文献
9.
R F B Serpa E F O de Jesus M J Anjos L F de Oliveira L A Marins M G T do Carmo J D Corrêa Junior M S Rocha R T Lopes A M B Martinez 《Analytical sciences》2008,24(7):839-842
Knowledge about the spatial distribution and the local concentration of trace elements in tissues is of great importance, since trace elements are involved in many biological functions of living organisms. However, there are few methods available to measure the spatial (two (three)-dimensional) elemental distribution in animal brain. X-ray microfluorescence with synchrotron radiation is a multielemental mapping technique, which was used in this work to determine the topographic of iron, zinc and copper in coronal sections of female Wistar rats of different ages. Young (14 days old) and middle-aged (20 months old) rats (n = 8) were analyzed. The measurements were carried out at the XRF beam line at the Synchrotron Light National Laboratory (Campinas, Brazil). Two-dimensional scanning was performed in order to study the tendency of elemental concentration variation. The acquisition time for each pixel was 10 s/step and the step size was 300 microm/step in both directions. It was observed that the iron distribution was more conspicuous in the cortical area, thalamus and bellow the thalamus. On the other hand, the zinc distribution was more pronounced in the hippocampus. The iron, copper and zinc levels increased with advancing age. Therefore, this study reinforces the idea that these elements are involved in the chemical mechanisms of the brain that induce some neurological diseases, since they are also present in high levels in specific areas of the brain, such as the hippocampus and the substantia nigra of patients with these disorders. 相似文献
10.