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At least 1,639 records · Page 91Linked to original sources
PubMed2003

[Spectral analysis of electromyography of low back muscle fatigue induced by simulated driving].

OBJECTIVE: To evaluate the effects of different vibration frequency on the back muscle fatigue during simulated driving. METHODS: Thirty-six subjects performed three simulated driving experiments under three vertical vibration frequencies which were 1.8, 4.0, 6.0 Hz respectively and the driving time was 90 minutes. At the same time the electromyography of low back was recorded. RESULTS: The median frequencies calculated from the power spectrum were decreased exponentially under three vertical vibration frequencies, especially under 4.0 Hz vibration frequency. CONCLUSION: The 4.0 Hz vibration frequency has the most important effect on the back muscle fatigue under simulated driving condition.

Adult↗
PubMedDate not supplied

[Spectral analysis of EEG coherence in Alzheimer's disease].

INTRODUCTION: In analysis of the electrical activity of the brain, coherence is a measure of the degree of synchrony between two or more regions of the brain with regard to their frequency values over a unit of time. AIMS: To explore the functional alterations caused by Alzheimer's disease (AD), by evaluating the behaviour of coherence over the whole spectrum of EEG frequencies. PATIENTS AND METHODS: We studied a group of 42 patients with AD, according to criteria of the NINCDS ADRDA group. Partial coherence (e.g. between two derivations each time) was calculated within and between hemispheres, during a state of mental rest; the Z statistic was also determined by comparing the coherence values with the standard data for age, sex and functional state of the brain. RESULTS: Significantly low coherence values were obtained for the frontal central regions of the left hemisphere (LH) and for the occipital parietal regions of the right hemisphere (RH) in the delta band. The same localisations were carried out for the theta band, in addition to the centrotemporal and temporal regions of the LH. The highest incoherence values were observed for the alpha and beta bands, more specifically in frontal central and occipital parietal derivations of the RH, and temporal derivations of the LH. CONCLUSIONS: Non activated partial coherence acts as an indicator of the degree of functional disconnection between brain regions in AD. Studying activated coherence in these patients could contribute new elements to our knowledge about the functional disorders observed in this disease.

Alzheimer Disease↗
PubMed1992

Spectral analysis of electromyograms for extraocular muscles in normal and ophthalmoplegia cases.

Quantitative analysis of electromyograms (EMGs) of the extraocular muscles (EOMs), which contain fast fibers, like all skeletal muscles, but also slow fibers, was carried out in healthy subjects and a patient with external ophthalmoplegia. Interference EMGs of normal extraocular muscles demonstrated a relatively higher power spectrum in the higher frequency domain than those of the biceps brachii (BB). In the case of ophthalmoplegia, the lateral rectus (LR) and medial rectus (MR) muscles demonstrated a power spectrum with a wide ranging distribution up to 2,000 Hz in the early stage of recovery. Conservative treatment led to an improvement in the patient's ocular motility accompanied by a gradual shift of the spectrum towards lower frequencies within 265 days, during which time EMG examinations were performed four times. The results imply that the electrical activity of the slow fibers proper in the extraocular muscles affects the high frequency domain of the power spectrum and that the those fibers synchronously improve with fast fibers.

Action Potentials↗
PubMed2004

[Combined spectral analysis method to trace the chemical elemental composition of food].

We have applied the combined approach to the routine elemental analysis of food using the complex ICP AES + ICP-MS for both major and trace element groups. Matrix elements (up to 15-20), such as Na, Mg, Al, Si, P, K, Ca, Fe, Zn in biological samples can be determined by ICP-AES while the rest elements except of H, C, O, F, Cl measured by more powerful ICP-MS method, which is able to quantify up to 50-60 elements, depending on element/isotope abundances. The application of two methods provides more flexibility when working with unknown matrices and provides cross-checking to improve data reliability and also enhances sample throughput.

Elements↗
PubMed2004

[Unequal interval jump grey modeling and its application to the spectral analysis of lubricating oil].

Unequal interval jump grey model was built for raw data series with unequal interval and jump trend in this paper. Levenberg-Marquardt arithmetic that belongs to non-linear least-square. estimation was used to recognize the parameters. The model built was used to fit spectrometric analysis values of diesel engine and the fitting precision is good. It is helpful to improve the accuracy and reliability of spectrometric analysis by revising test data after oil change with model parameter.

English Abstract↗
PubMed1999

[Study on the interaction of copper-zinc superoxide dismutase with cobalt (II)-histidine by spectral analysis--II. Effect of amount of external added Co(His)n, phosphate].

The effect of changing the amount of external added Co(His)n and phosphate on the interaction of Cu2Zn2SOD with organic metal compound (Cobalt (II)-Histidine) have been studied by means of ICP, VIS and measurement of enzyme activity. It has found that in aqueous solution, there exists a direct interaction of the metal ions of the active center in the metalloenzyme (Cu2Zn2SOD) with external added Co(His)n. As a result, part of the metal ions in metalloenzyme were replaced and the corresponding metalloenzyme derivatives (Co (II)-substituted derivatives of SOD) were produced and the catalytic activity of enzyme were affected. It has also studied the intensity of interactions in different molar ratios (Cobalt (II)-Histidine) and of the presence of phosphate and got some results under the effect of corresponding factors.

Cobalt↗
PubMed1999

[Study on the interaction of copper-zinc superoxide dismutase with cobalt (II)-histidine by spectral analysis. II. Effects of pH, interaction time].

The direct interaction of Cu2Zn2SOD with organic metal compound (Cobalt (II)-Histidine) was studied by ICP, VIS and the measurement of enzyme activity, and also investigated the effect of pH values and different interaction times for this interaction. The results showed that with the increased in pH values and the more longer interaction times, the intensity of interaction were increased and the corresponding catalytic activity of enzyme were affected.

Cobalt↗
PubMed2005

[Spectral analysis of dissolved organic matter derived from rice straw after chemical treatment].

Fourier transform infrared spectroscopy (FTIR), ultraviolet spectroscopy (UV), and nuclear magnetic resonance spectroscopy (NMR) were used to study the chemical composition of Dissolved Organic Matter (DOM) derived from rice straw in the hydrolysis process with a dilute complex acid solution. The results obtained are as follows. FTIR spectra could indicate the changes of DOM during the hydrolysis process of rice straw. With the progress of rice straw hydrolysis, methyl, methylene, aromatic compounds and carbohydrates decreased, most of aliphatic compounds were oxidized to CO2 and H2O, and others were turned into carbonates. Most of the organic silicon was hydrolyzed into inorganic silicon. The proteins, amino acids and other nitrogen were hydrolyzed to NH4+. All the recalcitrant fractions of rice straw, such as hemi-cellulose, cellulose and silicon sharply decreased during the process of chemical treatment. The results obtained in this paper proposed that the changes of DOM of rice straw in the hydrolysis could be an indication in the changes of chemical composition of rice straw during the hydrolyzation, and FTIR, UV and NMR were good methods to study the changes in the structure of organic compounds.

Acids↗
PubMed2005

[Study on D-glucosamine-zn (II) complexes by IR spectral analysis].

In this paper, a series of glucosamine-Zn(II) complexes were synthesized by the reaction of D-glucosamine hydrochloride with ZnSO4 at different pH values. The physical properties and the IR spectra of glucosamine-ZnSO4 complexes were investigated. The absorption at 3346 and 3292 cm(-1) shifted to 3300 cm(-1) due to O--H and N--H stretching, one at 1617 cm(-1) shifted to 1530 cm(-1) due to N-H stretching, and one at 1094 cm(-1) disappeared due to secondary alcohol --OH stretching. But 1033 cm(-1) with primary alcohol --OH did not shift, suggesting that both the amino and secondary hydroxyl groups of glucosamine are coordinated to Zn(II). The results showed that the coordination ability of Zn(II) to glucosamine was enhanced with the pH value increasing, however, the coordination ability weakened when pH value was more than 6.5. So pH 6.5 is an optimal coordination condition for glucosamine-ZnSO4 complexes. The complexes of D-glucosamine with different zinc salts (zinc sulfate, zinc nitrate, zinc acetate, and zinc chloride) were also synthesized at the same pH value, and zinc chloride had weaker coordination ability than other zinc salts. Their IR spectra indicated that glucosamine-Zn(II) complexes with different zinc salts had different coordination model, and only glucosamine-ZnSO4 complex had fixed ratio of coordination under the condition of pH 6.5. The structure of the complex seems to correspond to [Zn(glucosamine)]SO4 7H2O at pH 6.5.

Chlorides↗
PubMed2005

[Luminescence properties and spectral analysis of long phosphorescent phosphors: Ba(1 - x) Ca (x) Al2O4 : Eu2+, RE3+].

New long phosphorescent phosphors Ba(1 -x),Ca(x)Al2O4 : Eu2+, RE3+ (RE3+ = Dy3+, Nd3+) with tunable color emission have been prepared by solid state reaction. The luminescence properties of the samples are discussed and analyzed. The emission spectra show that the tuning range of the color emission of the phosphors is between 498 and 440 nm, which is determined by x, under the excitation of UV. The wavelength of afterglow increases with increasing x until x equals 0.6, and when x equals 0.6, the luminescence property of Ba(1-x) Ca(x)Al2O4: Eu2+, RE3+ (RE3+ = Dy3+, Nd3+) is similar to that of CaAl2O4 : Eu2+, RE3+. The XRD measurements were performed to investigate the single phase states of the samples, and it was found that the single phase limit in the phosphors is below an x value of 0.4. The thermoluminescence curves imply that the traps in the hosts are different with different x value, which well explains the varying delay time of the samples.

Aluminum Oxide↗
PubMed2005

[Synthesis and spectral analysis of metal-N-glycoside complexes and studies of catalyzed ester hydrolytic kinetics].

Four new complexes of Ni(II), Cu(II), Zn(II) and Co(III) with HL (HL= N,N'-di-beta-D-glucosylethylenediamine) have been synthesized in methanol solutions. The compositions of the complexes determined by elementary analysis are [Ni(HL)(H2O)2]2+ Cl2.CH3OH.2H2O, [Cu(HL)]2+ Cl2.CH3CH2OH.3H2O, [Zn(HL)]2+ Cl2.H2O and [Co(HL)(H2O)(OH)]2+ Cl2.CH3OH.2H2O respectively. They were also characterized by IR, UV and NMR spectra which show that complexes of Ni(II) and Co(III) have octahedral configuration, while complexes of Cu(II) and Zn(II) have tetralhedral configuration. The hydrolytic kinetics of p-Nitrophenyl picolinate(PNPP) catalyzed by these complexes in buffer solution was also studied spectrophotometrically.

Catalysis↗
PubMed1992

[Power spectral analysis of electromyograms in fast and slow fibers of cats extraocular muscles].

Electromyogram (EMG) was recorded from the muscle fibers in the orbital layers through the global layers of superior rectus muscle of the cat. Power spectrum analysis was applied to investigate the quantitative differences between EMG patterns in both layers. The median of the power spectrum in frequency from the global layers was 400-700 Hz, which was considered to be an EMG pattern of the fast fibers. On the other hand, EMG from the orbital layers showed a small amplitude of 35-70 microV and two different types of power spectrum; one had the median frequency of more than 1,000 Hz and the other, about 500 Hz. It was suggested that the high frequency component was due to multi-innervated slow fibers and the low frequency component was due to singly innervated and intermediate fibers. The study of the power spectrum of interference electromyograms provides an advantage to differentiate the electrical activities of the slow fibers from the fast ones.

Animals↗