Search results for "Spectroscopy"

Direct Methane Oxidation on La1-xSrxCr1-yFeyO3-δ perovskite-type oxides as Potential Anode for Intermediate Temperature Solid Oxide Fuel Cells

2016

Abstract La1−xSrxCr1−yFeyO3−δ (x = 0, 0.1, 0.15, 0.2; y = 0, 0.3, 0.5) perovskite-type oxide powders were synthesized by solution combustion synthesis and characterized by X-ray diffraction, X-ray photoelectron spectroscopy and H2-temperature programmed reduction. Selected compositions were studied by CH4-temperature programmed reduction in the absence and in the presence of H2S. Temperature programmed oxidation and structural characterizations were performed in order to discriminate the nature of residual deposits on the catalyst surface. The study about reduction in different methane-based mixture revealed that total and partial methane oxidation occurred in the range ∼450–1000 °C indepen…

Direct injection of physiological fluids in micellar liquid chromatography

2000

Abstract Micellar liquid chromatography (MLC), which uses mobile phases of surfactants above the critical micellar concentration, provides a solution to the direct injection of physiological samples by solubilizing the protein components, and coating the analytical column with surfactant monomers to avoid clogging. A review showing the advantages and limitations of this technique over other chromatographic techniques used in drug analysis, working protocols, and examples of application is presented. The possibility of direct sample introduction simplifies and greatly expedites the treatments with reduced cost, improving the accuracy of the procedures. Surfactant monomers and micelles appear…

Electrochemical impedance spectroscopy of thin films with two mobile charge carriers: effects of the interfacial charging

1999

In the electrochemical systems containing an excess of the background electrolyte, the faradaic process and the interfacial (‘double-layer’) charging are coupled to the fluxes of different charge carriers, the former being related to the diffusional transport of electroactive entities while the latter being realized mostly by ions of the supporting electrolyte. As a result, the interfacial capacitance Cdl may simply be added in parallel to the faradaic impedance specific for each particular system (Randles & Ershler). This simple treatment is not justified in the absence of an indifferent electrolyte, if the same charged species take part in both the electrode reaction and the double layer …

Electrochemical reduction of graphene oxide and its in situ spectroelectrochemical characterization

2012

The electrochemical properties of self-assembled films of graphene oxide (GO) on mercaptoethylamine (MEA) modified rough Au-surfaces were studied. The film deposition process on MEA primed gold was followed by surface plasmon resonance measurements and the film morphology on 3-aminopropyltriethoxysilane primed Si(100)-surface was studied by atomic force microscopy. The deposited few layer thick GO films on gold were electrochemically reduced by cyclic voltammetry simultaneously as the structural changes in the film were recorded by in situ vibrational spectroscopies. In situ surface enhanced infrared spectroscopy results indicate that the effect of the applied potential on the GO structure …

PREDICTION OF MOESSBAUER PARAMETERS IN A DOUGLAS–KROLL–HESS FRAMEWORK

2008

On-line monitoring of food fermentation processes using electronic noses and electronic tongues: A review

2013

Fermentation processes are often sensitive to even slight changes of conditions that may result in unacceptable end-product quality. Thus, close follow-up of this type of processes is critical for detecting unfavorable deviations as early as possible in order to save downtime, materials and resources. Nevertheless the use of traditional analytical techniques is often hindered by the need for expensive instrumentation and experienced operators and complex sample preparation. In this sense, one of the most promising ways of developing rapid and relatively inexpensive methods for quality control in fermentation processes is the use of chemical multisensor systems. In this work we present an ov…

Harmonic behavior of trehalose-coated carbon-monoxy-myoglobin at high temperature.

1999

Abstract Embedding biostructures in saccharide glasses protects them against extreme dehydration and/or exposure to very high temperature. Among the saccharides, trehalose appears to be the most effective bioprotectant. In this paper we report on the low-frequency dynamics of carbon monoxy myoglobin in an extremely dry trehalose glass measured by neutron spectroscopy. Under these conditions, the mean square displacements and the density of state function are those of a harmonic solid, up to room temperature, in contrast to D 2 O-hydrated myoglobin, in which a dynamical transition to a nonharmonic regime has been observed at ∼180K (Doster et al., 1989. Nature. 337:754–756). The protective ef…

Can NF-κB Be Considered a Valid Drug Target in Neoplastic Diseases? Our Point of View

2020

Multidrug resistance (MDR), of the innate and acquired types, is one of major problems in treating tumor diseases with a good chance of success. In this review, we examine the key role of nuclear factor-kappa B (NF-κB) to induce MDR in three tumor models characterized precisely by innate or acquired MDR, in particular triple negative breast cancer (TNBC), hepatocellular carcinoma (HCC), and acute myeloid leukemia (AML). We also present different pharmacological approaches that our group have employed to reduce the expression/activation of this transcriptional factor and thus to restore chemo-sensitivity. Finally, we examine the latest scientific evidence found by other groups, the most sign…

Determination of isoniazid and pyridoxine in plasma sample of tuberculosis patients by micellar liquid chromatography

2021

It is no doubt Isoniazid is a powerful tuberculosis drug, but it might give rise to Vitamin B6 (Pyridoxine) deficiency. In this case, a usual treatment is the combined administration of Isoniazid and Pyridoxine. An easy-to-conduct procedure based on Micellar Liquid Chromatography has been developed to quantify Isoniazid and Pyridoxine in plasma from Tuberculosis patients. The sample was diluted in mobile phase, filtered and directly injected, thus avoiding extraction or purification steps. Both drugs were adequately resolved from the matrix and endogenous compounds using a mobile phase made up of 0.15 M sodium dodecyl sulfate – 8%(v/v) 1-butanol – 0.01 M phosphate buffer at pH 3, running at…

Determination of the enantiomeric composition of amphetamine, methamphetamine and 3,4-methylendioxy-N-methylamphetamine (MDMA) in seized street drug …

2021

Amphetamine (speed), methamphetamine (crystal meth), and 3,4-methylenedioxy-N-methylamphetamine (MDMA, ecstasy) represent the most frequently abused amphetamine-type stimulants (ATS). Differences in pharmacological potency and metabolism have been shown for the enantiomers of all three stimulants. Legal consequences in cases of drug possession may also differ according to the German law depending on the enantiomeric composition of the seized drug. Therefore, enantioselective monitoring of seized specimens is crucial for legal and forensic casework. Various kinds of samples of amphetamine (n = 143), MDMA (n = 94), and methamphetamine (n = 528) that were seized in southern Germany in 2019 and…