Search results for "alkali"

A clean analytical method for the spectrophotometric determination of formetanate incorporating an on-line microwave assisted hydrolysis step

1999

Abstract A fast and completely automated procedure is proposed for the spectrophotometric determination of formetanate in waters by means of its reaction with p-aminophenol (PAP). The method involves the on-line alkaline hydrolysis of formetanate to m-aminophenol (MAP) and its reaction, in the presence of KIO 4 as oxidant agent, with the quinoneimine form of PAP, to form a blue indophenol dye which absorbs at 576 nm. The on-line hydrolysis can be carried out in a 6 m reaction coil located inside the cavity of a domestic microwave oven operated at 650 W, or in a 4 m reaction coil located inside the cavity of a Microdigest 301 microwave system operated at 60 W and allows us, in both cases, a …

Classification of vegetable oils according to their botanical origin using n-alkane profiles established by GC-MS.

2013

n-Alkane profiles established by gas chromatography-mass spectrometry (GC-MS) were used to classify vegetable oils according to their botanical origin. The n-alkanes present in corn, grapeseed, hazelnut, olive, peanut and sunflower oils were isolated by means of alkaline hydrolysis followed by silica gel column chromatography of the unsaponifiable fractions. The n-alkane fraction was constituted mainly of n-alkanes in the range C8-C35, although only those most abundant (15 n-alkanes, from 21 to 35 carbon No.) were used as original variables to construct linear discriminant analysis (LDA) models. Ratios of the peak areas selected by pairs were used as predictors. All the oils were correctly …

Синтез и оптические свойства монокристаллических слоев окислов щелочноземельных металлов

1980

Isopropanolic Cimicifuga racemosa is favorable on bone markers but neutral on an osteoblastic cell line

2009

Postmenopausal women treated with an isopropanolic extract of Cimicifuga racemosa underwent a decrease in the urinary concentration of N-telopeptides, a marker of bone resorption, and an increase in alkaline phosphatase, a marker of bone formation, at the third month of therapy. Serum from treated women did not modify the activity of alkaline phosphatase or the expression of three genes, runt-related transcription factor-2 (Runx-2), alkaline phosphatase, and osteocalcin, when added to the MC3T3-E1 osteoblastic cell line.

Circular dichroism of magnetically induced transitions for D 2 lines of alkali atoms

2018

In this letter we study magnetic circular dichroism in alkali atoms exhibiting asymmetric behaviour of magnetically induced transitions. The magnetic field induces transitions between hyperfine levels of alkali atoms and in the range of magnetic field, the intensities of these transitions experience significant enhancement. We have inferred a general rule applicable for the D 2 lines of all alkali atoms, that is the transition intensity enhancement is around four times larger for the case of than for excitation for , whereas it is several hundreds of thousand times larger in the case of than that for polarization for . This asymmetric behaviour results in circular dichroism. For experimenta…

Self-trapped exciton formation through photo-induced recombination of F and H centers in alkali iodides

1997

The photo-induced conversion of the primary F, H center pairs into self-trapped excitons have been proposed and studied in alkali iodides.

Trapping of laser-vaporized alkali metal atoms in rare-gas matrices

1999

Abstract Alkali metal atoms prepared by laser ablation of solid Li and Na are trapped in Ar, Kr, and Xe matrices and studied by electron paramagnetic resonance spectroscopy (EPR) at 15 K. Evidence for tight trapping sites, not observed for atoms generated by conventional Knudsen oven techniques, is presented. The novel tight trapping sites are characterized by a large increase in the isotropic hyperfine coupling constant and a simultaneous decrease in the isotropic g -value. Based on the EPR data, it is suggested that the observed tight trapping corresponds to single substitution of lattice atoms in Ar, Kr, and Xe matrices.

Formation of self-trapped excitons through stimulated recombination of radiation-induced primary defects in alkali halides

1998

Abstract A self-trapped exciton formation through photostimulated recombination of an F and an H center — the exciton-created primary defect pair, is proposed and experimentally examined in alkali halides at low temperatures.

Functional consequences of prey acclimation to ocean acidification for the prey and its predator

2016

Ocean acidification is the suite of chemical changes to the carbonate system of seawater as a consequence of anthropogenic carbon dioxide (CO2) emissions. Despite a growing body of evidences demonstrating the negative effects of ocean acidification on marine species, the consequences at the ecosystem level are still unclear. One factor limiting our ability to upscale from species to ecosystem is the poor mechanistic understanding of the functional consequences of the observed effects on organisms. This is particularly true in the context of species interactions. The aim of this work was to investigate the functional consequence of the exposure of a prey (the mussel Brachidontes pharaonis) t…

Impact of Pulsed Electric Fields on Enzymes

2017

International audience; Pulsed electric field (PEF) processing has emerged as a promising technology in the development of tailor-made processes to effectively control the enzyme activity. It has been proven as an effective technique for the preservation of food products as it can result in substantial inactivation of most undesirable enzymes. When compared to microbial inactivation, however, large specific energy inputs are required to inactivate enzymes. The existing evidence suggests that PEF can also stimulate the activity of beneficial enzymes at low intense treatments. The PEF affects enzyme activity by changing mainly the secondary (α-helix, β-sheets, etc.), tertiary (spatial conform…