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At least 1,621 records · Page 90Linked to original sources
PubMed2000

[Application of spectral analysis on atmosphere corrosion research].

This paper applied two methods of spectrum analysis to measure the rusty layer of samples atmosphere corrosion from Qingdao and Chengdu. The main component elements and rust phase of rusty layer are obtained. It showed that the relative content of the elements and rust phase varies with the change of corroded environment and time. The result, relative content of each rust phase of A3(1) rusty layer sample have following relation: gamma-Fe00H > alpha-Fe00H > delta-Fe00H, and, relative content of other rusty layer samples have relation: gamma-Fe00H > delta-Fe00H > alpha-Fe00H, in the rusty layer of low-alloy steel, there are the alloy elements of rest body.

English Abstract↗
PubMed2003

[FTIR spectral analysis of saturated solution during dissolution and transformation of chloropinnoite in magnesium chloride solution].

FTIR differential spectroscopy was used to identify the polyborate ions in saturated aqueous solutions during dissolution and transformation of 2MgO.2B2O3.MgCl2.14H2O in 0.5%, 12%, and 18% MgCl2 solutions at 30 degrees C, respectively. The recorded IR-spectroscopic frequencies of the borate aqueous solution subtracted that of water as a blank value and their assignments were given. The bands at about 515, 630 and 550 cm-1 are characteristics of B(OH)4-/B2O(OH)6(2-), B3O3(OH)4-/B3O3(OH)5(2-), and B4O5(OH)4(2-), respectively. The existing forms of polyborate anions in saturated aqueous solutions and their interaction have been discussed. The relations between the existing forms of polyborate anions and the crystallizing solid phases have been obtained.

Borates↗
PubMed1992

Spectral analysis of electroencephalography data in athletes with low erythrocyte magnesium.

In a population of high level athletes (kayakists) we compared quantitative electroencephalography data in those with low erythrocyte (magnesium magnesium deficit) and those with normal magnesium (controls). Logistic regression showed that the relative power of the alpha frequency band in the occipital lead is the most discriminant (P < 0.05). There was a significant positive correlation between low erythrocyte magnesium and alpha relative power (P < 0.05). An alteration of magnesium homeostasis could explain the occurrence of magnesium deficiency in athletes.

Adult↗
PubMed1992

Spectral analysis of the protein-derived tyrosyl radicals from prostaglandin H synthase.

We have analyzed the low temperature EPR spectra of the protein-derived tyrosyl radicals detected upon addition of arachidonic acid or 5-phenyl-4-pentenyl-1-hydroperoxide (PPHP) to prostaglandin H synthase. With either arachidonic acid or PPHP the initial radical detected is a doublet (peak-to-trough = 35 Gauss) that disappears rapidly and is replaced by a broad singlet (peak-to-trough = 30 Gauss) followed by a narrow singlet (peak-to-trough = 26.5 Gauss). The relative amounts of these signals vary with time and concentration of arachidonic acid. The three tyrosyl radical signals were subjected to computer simulation and power saturation analysis. The data establish that there are only two distinct tyrosyl radical species, the doublet and the narrow singlet. The broad singlet seen at intermediate times and at low arachidonic acid concentrations is a composite of the doublet and the narrow singlet. The composition of the broad singlet in incubations of prostaglandin H synthase with 0.5 mM arachidonic acid is approximately 40% doublet and 60% singlet. The broad singlet signal does not represent a distinct tyrosyl radical species.

Alkenes↗
PubMed1992

Cytochrome aa3 of Rhodobacter sphaeroides as a model for mitochondrial cytochrome c oxidase. Purification, kinetics, proton pumping, and spectral analysis.

Aerobically grown Rhodobacter sphaeroides synthesizes a respiratory chain similar to that of eukaryotes. We describe the purification of the aa3-type cytochrome c oxidase of Rb. sphaeroides as a highly active (Vmax > or = 1800 s-1), three-subunit enzyme from isolated, washed cytoplasmic membranes by hydroxylapatite chromatography and anion exchange fast protein liquid chromatography. The purified oxidase exhibits biphasic kinetics of oxidation of mammalian cytochrome c, similar to mitochondrial oxidases, and pumps protons efficiently (H+/e- = 0.7) following reconstitution into phospholipid vesicles. A membrane-bound cytochrome c is associated with the aa3-type oxidase in situ, but is removed during purification. The EPR spectra of the Rb. sphaeroides enzyme suggest the presence of a strong hydrogen bond to one or both of the histidine ligands of heme a. In other respects, optical, EPR, and resonance Raman analyses of the metal centers and their protein environments demonstrate a close correspondence between the bacterial enzyme and the structurally more complex bovine cytochrome c oxidase. The results establish this bacterial oxidase as an excellent model system for the mammalian enzyme and provide the basis for site-directed mutational analysis of its energy transducing function.

Animals↗
PubMed1992

[Spectral analysis of the effects of nomifensine on bioelectric activity of the rat brain].

The influence of nomifensine on bioelectrical activity of sensorimotor cortex, dorsal hippocamp and lateral hypothalamus in conscious rats in free behavior was studied. The pharmacological and EEG analysis of nomifensine action on EEG power spectra by Fourier technique was measured. It was established that nomifensine evoked an increase and stabilization of the dominant peak in EEG spectra in the left and right cortex and in the left hippocamp, while in the other ranges of frequency a decrease was observed. The effects on hypothalamus was opposite--EEG power spectra decreased in all the ranges. The authors conclude that nomifensine evokes higher level of wakefulness, vigilance of the animals. This is likely to underlie neurophysiological mechanisms of optimal behavior due to stimulants of CNS, including nomifensine.

Animals↗
PubMedDate not supplied

[A spectral analysis of the effect of adapromine on brain bioelectrical activity].

A study was made of the influence of adapromine on bioelectrical activity of the brain, sensorimotor cortex, dorsal hippocamp and lateral hypothalamus in freely moving wakeful rats. Adapromine was established to evoke a decrease of the amplitude of the dominant peak and dominant theta-activity in power spectra of the EEG in the cortex and hippocamp, with an increase of rapid wave activity in the beta 2 range in the right cortex and hippocamp. These changes attained maximum after 1 to 1.5 hour and lasted up to 4-5 hours after adapromine administration. These changes can be viewed as activation of the cortex and hippocamp, which may attest to the presence of antidepressive and psychostimulant effects in the action spectrum of adapromine. The specific influence of adapromine on catecholaminergic processes of the brain may lie at the basis of the above effects.

Animals↗
PubMed1992

[A spectral analysis of the effect of sidnocarb on the bioelectrical activity of the rat brain].

A quantitative pharmaco-EEG analysis of the action of psychostimulant drug sydnocarb and its solvent polyethylenglycol-400 on bioelectrical activity of sensomotor cortex, dorsal hippocamp and lateral hypothalamus of wakeful rats in free behavior was carried out. Polyethylenglycol-400 proved to affect CNS, as it decreases slow-wave activity and causes displacement of the dominant peak to the region of more slow-wave frequencies, shows anticonvulsant action. Sydnocarb reduces absolute power of all frequency ranges and increases relative power of fast activity. It is concluded that sydnocarb increases in optimal limits the level of CNS vigilance which may underlie a psychostimulant action of the drug eventuating into optimization of behavioral functions, increasing physical and mental capacity for work.

Animals↗