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At least 127 records · Page 7Linked to original sources
PubMed1990

[Effects of the reduction of vibration intensity of chain saws on the prevalence rates of vibration syndrome among forestry workers].

Prevalence rates of vibration syndrome in two groups of forestry workers who were employed in private enterprises in Fukushima Prefecture and were operating chain saws not less than 25 days a year were evaluated in relation to the vibration acceleration levels of chain saws and the total working hours per year with the tools. The 1st group consisted of 261 workers (mean age and SD: 46.2 +/- 11.0 yr) who had begun to operate the tools between 1965 and 1976 and were examined at least once in 1976 or 1977 and the 2nd group of 225 workers (46.1 +/- 11.0 yr) who were at work between 1976 and 1987 and examined at least once during 1983 to 1988. The following results were obtained: 1. It was estimated that the maximum acceleration levels of the chain saws used between 1965 and 1975, and between 1976 and 1988 ranged approximately from 2.5 G to 8 G (mean: 5.1 G) and from 1 G to 2.5 G (mean: 1.7 G) by the one-third octave band filters, respectively. The average intensity of vibration was thus reduced by 89% after 1976. 2. The number of working days per year and hours per day with the tools were 157 +/- 70 d (mean +/- SD) and 3.7 +/- 1.3 h (mean +/- SD) in the first group and 120 +/- 55 d and 3.0 +/- 1.3 h in the second group, respectively. Therefore, the average total hours per year decreased by 38% after 1976.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1999

[The effect of the vibration and noise factor on the physical work capacity and autonomic nervous system function of workers in vibration-hazardous jobs].

An unexampled study was made of the peripheral vegetative incompetence syndrome developing in vibration disease. It is shown that chronic occupational exposure to vibration and noise results in damage to the segmentary apparatus of the vegetative nervous system. Vegetative inadequacies are manifested by impairement of cardiovascular functions. With exposure to vibration and noise, it is the sympathetic portion of the vegetative nervous system that is first affected. The service duration-related progression of the pathological process results in increase of the share of parasympathetic pathology. A change in vegetative regulation adversely affects physical performance in those workers who have come to be exposed to a vibronoise factor over long periods of time.

Autonomic Nervous System↗
PubMed1975

[17-ketosteroids in the 24-hour urine of miners with vibration disease from local vibration exposure].

The 17-ketosteroid level in the urine secreted in 24 hours s studied in miners with vibration disease. The case material is analyzed according to age, working service, clinical syndromes and stage. It is demonstrated that the continuous effect of local vibrations lead to inhibition of the adrenal function, manifested by a 17-ketosteroids fall. Such a lowering is assumed as one of the adaptational syndrome-manifestations. Regulation of corticosteroid secretion is discussed in the light of complex interrelations--neuroendocrine, biochemical and homeostatic. The role played by oxidation processes is also emphasized. 17-ketosteroids content in the urine has certain diagnostical value, irrespective of the fact that its lowering is by no means a specific manifestation of the vibration disease.

17-Ketosteroids↗
PubMed1991

[Assessment of probability of vibration disease caused by local vibration taking into consideration concomitant factors].

The article sets forth a theoretical basis for the evaluation of the probability of vibration disease caused by local vibration, with due account of the concomitant factors and with recommendations with regard to the assessment of the aggravating and normalizing factors. Basing on the original data and medical literature information, the contributors provided formulae and charts for the assessment of vibration disease, risks caused by noise, cold microclimate, physical overload, and cigarette smoking as an individual factor. A concept was proposed with regard to the risk-free dosage. The concept was viewed as a new hygienic and occupational category, which facilitated evaluating the real occupational risk levels for any profession and their consequent minimizing.

Cold Climate↗
PubMed1991

[Predicting the development of vibration disease in coal miners exposed to local vibration combined with noise and dust].

The contributors proposed a differentiated diagnostic technique which included 10 most informative physiologic, anthropometric and biochemical+ indices to provide the most reliable data (95% reliability) on the adaptation and compensatory mechanisms under local vibration and in combination with noise and dust, and with due account of the individual sensitivity to local vibration. Testing of the technique demonstrated its high accuracy in determining the levels of "exhaustion", and of "the normal state" of the adaptation-compensatory mechanisms, and its applicability for vibration disease prognosis in individual++ workers, thus establishing corresponding in preventive medical examinations, occupational selection, preventive measures' planning, and in expert solutions requiring precise diagnostic techniques.

Adaptation, Physiological↗
PubMed1984

[Acoustic reflex in workers using hand-held vibration tools. Combined effects of noise and local vibration].

Combined effects of noise and local vibration on the threshold of acoustic reflex (ART) were investigated. ARTs for three different stimuli (ARTWN, ART1k, ART4k) were determined in workers using hand-held vibration tools. The results obtained from these 72 workers (Group A) were compared with the ARTs in 100 control subjects (Group C) who had normal hearing acuity without any history of occupational noise exposure, as previously reported by the authors. The mean age in group A was 46.6 ranging from 26 to 62. The mean period of noise and vibration exposure was 11.4 years in subjects mainly using chain saws and 9.2 years in subjects mainly using bush cleaners (Table 2). ARTWN and ART1k in the exposed group showed significant differences compared to those in the non-exposed group (p less than 0.001), i.e., mean ARTWN was 89.6 dB SPL in Group A and 83.8 in Group C, mean ART1k was 96.1 dB SPL in the former and 92.2 in the latter group (Table 7). No significant difference was observed in mean ART4k between the two group (p greater than 0.1). The difference between ART1k and ARTWN, [ART1k-ARTWN], was significantly reduced in the exposed group (p less than 0.001), i.e., 2.7 dB in Group A and 12.4 in Group C (Table 8). To clarify the effects of aging on [ART1k-ARTWN], the exposed group was classified into three groups according to their HL(4k + 8k)/2. However, no significant correlation was observed between [ART1k-ARTWN] and age in any of these 3 groups (p greater than 0.1).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Vibration dose, disturbance stage, and examination results and subjective symptoms in vibration syndrome.

The 1973 national survey of 461 chainsaw operators in private forests was reexamined with respect to vibration exposure dose and the Stockholm Workshop Scale (CIRP and SN stages). Vibration dose (VD) was calculated by the formula "ahw(eq.4h) x D (days) x Y (years)". Vibration dose index (VDI) was calculated according to the level of VD. Subjects were divided into five VDI, for CIRP stage, and four SN stage groups. Examination results and prevalence of subjective symptoms were compared between VDI-1 and other VDI groups, CIRP-0 and other CIRP groups, and SN-0 and other SN groups. VD had higher values in CIRP-2 and 3, and SN-2 and 3 than CIRP-0 and SN-0, respectively. The most severe CIRP-3 and SN-3 appeared at higher rate in VDI-4 and 5 groups than in VDI-1 group. VDI had a correlation with mean value of prevalence of CIRP, vibrotactile perception, mean SN stage and fingertip pinch strength. A correlation was observed between skin temperature and CIRP stage, and between vibrotactile perception and SN stage. Decrease of muscle strength and difficulty in fine finger movement were associated with severe sensorineural disturbance.

Adult↗
PubMed2006

FT-IR vibrational spectrum and DFT:B3LYP/6-31G structure and vibrational analysis of guanidinoaceticserinenickel(II) complex: [Ni(GAA)(Ser)].

Vibrational assignment and structural determination for the guanidinoaceticserinenickel(II) complex have been made through DFT:B3LYP/6-31G calculations. A full discussion of the framework vibrational modes was done using as criteria the geometry study of distorted structures generated for the vibrational modes. Incidentally, the normal co-ordinate treatments have been made in order to clarify the assignments for the Ni(N)(2)(O)(2) structural fragment. The calculated DFT spectra in the high and low energy regions agree well with the observed ones.

Acetic Acid↗
PubMed2002

The complex-mode vibration of ultrasonic vibration systems.

The longitudinal-flexural and torsional-flexural vibrations are studied for the ultrasonic solid horn and the ultrasonic vibration system comprised of a sandwich transducer and a solid horn. The discussed solid horn is of arbitrary non-uniform cross-section. The analysis on flexural-mode vibration is based on Timoshenko theory. The theoretical results are verified by experiment.

Journal Article↗
PubMed2002

Infrared spectra of permanganate anions in potassium perchlorate matrices: vibrational anharmonicity, effective symmetry and vibrational mode mixing effects.

Fourier transform infrared spectra of MnO4- anions isomorphously isolated in potassium perchlorate matrices were recorded at room and low temperature (LT, approximately 100 K). On the basis of the detected second-order vibrational transitions involving the dopant species nu3 mode components, anharmonicity constants and harmonic eigenvalues for these modes were calculated. Despite the fact that, rigorously speaking, the appearance of the spectra of dopant permanganate anions may be explained in terms of a Cs site symmetry, the nu3 stretching region resembles an approximate A1+E splitting (characteristic for a local C3nu or even higher symmetry), which is not expected, even within the latent symmetry approach. We explain such spectral patterns on the basis of vibrational mode mixing (a 'Fermi-like' resonance) of the MnO4- nu1 mode with the nu3, site-group component. With the results of degenerate case stationary perturbation theory, we show that in the present case the Fermi-like resonance is predominantly responsible for the observed spectral features. The appearance of the region of second-order vibrational transitions in the spectra of dopant permanganate anions may be better explained in terms of the (rigorous) crystallographic Cs site group (corresponding to the crystallographic Pnma space group), instead of the 'latent' (effective) symmetry site group C2nu (corresponding to the latent symmetry space group Imma).

Manganese Compounds↗
PubMed2000

Vibrational anharmonicity and vibrational Stark effect of sulfate ions trapped in potassium, rubidium and cesium chromate.

Room and low temperature (approximately 100 K) FT-IR and Raman spectra of the sulfate doped K2CrO4, Rb2CrO4 and Cs2CrO4 were recorded. The positions of the nu1, nu3, and nu4 fundamental mode components of the dopant anions were measured. Nine (out of possible ten) second-order stretch-stretch vibrational transitions of the dopant anions were detected. On the basis of these data, the anharmonicity constants and the corresponding harmonic eigenvalues were calculated for several vibrational transitions using second-order perturbation theory expressions. The anharmonicity of the studied second-order transitions of the type nu1 + nu3i increases in the order (SO4/K2CrO4) < (SO4/Rb2CrO4) < (SO4/Cs2CrO4), while for those of the type nu3j + nu3i it basically follows the trend: (SO4/K2CrO4) > (SO4/Rb2CrO4) < (SO4/Cs2CrO4). The measured relative Stark splittings of the nu3 and nu4 mode components of the dopant SO4(2-) anions, as well as the average X13i/3i3j values decrease in the order (SO4/K2CrO4) > (SO4/Rb2CrO4) > (SO4/Cs2CrO4). In all cases, the splitting is larger for nu3 than for nu4 modes, indicating a smaller angular than the bond length distortion. The theory of vibrational Stark effect suggests that the observed frequency shifts of the nu1, nu3 and nu4 mode components may be attributed to the increase of the field strength at the doped anion site going from K2CrO4 to Cs2CrO4. The Stark splitting of these modes, on the other hand, implies that the internal crystalline field vector is almost parallel to the (hypothetical) C2 axis of the slightly distorted dopant tetrahedral anions.

Anions↗
PubMed1979

Low-frequency vibrations in resonance Raman spectra of horse heart myoglobin. Iron-ligand and iron-nitrogen vibrational modes.

The low-frequency regions (150--700 cm-1) of resonance Raman (RR) spectra of various complexes of oxidized and reduced horse heart myoglobin were examined by use of 441.6-nm excitation. In this frequency range, RR spectra show 10 bands common to all myoglobin derivatives (numbered here for convenience from I to X). Relative intensities of bands IV, V, and X constitute good indicators of the doming state of the heme and, consequently, of the spin state of the iron atom. An additional band is present for several complexes (fluorometmyoglobin, hydroxymetmyoglobin, azidometmyoglobin, and oxymyoglobin). Isotopic substitutions on the exogenous ligands and of the iron atom (56Fe leads to 54Fe) allow us to assign these additional lines to the stretching vibrations of the Fe-sixth ligand bond. Similarly, bands II are assigned to stretching vibrations of the Fe-N-(pyrrole) bonds. An assignment of bands VI to stretching vibrations of the Fe-Nepsilon(proximal histidine) bonds is also proposed. Mechanisms for the resonance enhancement of the main low-frequency bands are discussed on the basis of the excitation profiles and of the dispersion curves for depolarization ratios obtained for fluorometmyoglobin and hydroxymetmyoglobin.

Animals↗
PubMed2006

Solution phase isomerization of vibrationally excited singlet nitrenes to vibrationally excited 1,2-didehydroazepine.

Photolysis of phenyl and o-biphenylyl azide (at 270 nm) releases vibrationally excited singlet nitrene which isomerizes to the corresponding hot 1,2-didehydroazepine at a rate competitive with thermal relaxation. Using ultrafast vibrational spectroscopy we observe the formation of vibrationally excited 1,2-4,6-azacycloheptatetraene (1,2-didehydroazepine) in picoseconds following photolysis of phenyl azide in chloroform and o-biphenylyl azide in acetonitrile at ambient temperature.

Journal Article↗
PubMed2006

Intramolecular vibrational redistribution in the vibrational predissociation dynamics of He-I2.

The intramolecular vibrational redistribution (IVR) process is investigated in wave packet simulations of the vibrational predissociation dynamics of He-I(2)(B,upsilon') in the region of high upsilon' levels, upsilon' = 35-65. The simulations indicate that for upsilon' < or = 45 the dynamics is dominated by direct predissociation, whereas for higher upsilon' levels the onset of IVR appears and becomes increasingly important. The IVR process occurs via coupling of the initial state in the upsilon' manifold to intermediate long-lived resonances belonging to the lower upsilon < upsilon' vibrational manifolds. The IVR dynamics manifests itself in multiexponential behavior and oscillations in the time-dependent population curves associated with the He-I(2)(B,upsilon') initial state, the He-I(2)(B,upsilon < upsilon') intermediate complexes, and the final product states. The population curves corresponding to the upsilon'- 1 intermediate resonances located below the He + I(2)(B,upsilon'-1,j=0) dissociation limit are analyzed. It is found that initial population is transferred to all the intermediate resonance states considered, including those more separated in energy from the initial one. The results obtained for population transfer between the initial and the intermediate states can be explained by the intensity of the matrix elements coupling the initial and the intermediate resonances, in combination with the Rabi's formula for population exchange between two coupled states.

Journal Article↗
PubMed2004

Theoretical calculations of infrared absorption, vibrational circular dichroism, and two-dimensional vibrational spectra of acetylproline in liquids water and chloroform.

Infrared absorption, vibrational circular dichroism, and two-dimensional infrared pump-probe and photon echo spectra of acetylproline solutions are theoretically calculated and directly compared with experiments. In order to quantitatively determine interpeptide interaction-induced amide I mode frequency shifts, high-level quantum chemistry calculations were performed. The solvatochromic amide I mode frequency shift and fluctuation were taken into account by carrying out molecular dynamics simulations of acetylproline dissolved in liquids water and chloroform and by using the extrapolation method developed recently. We first studied correlation time scales of the two amide I vibrational frequency fluctuations, cross correlation between the two fluctuating local mode frequencies, ensemble averaged conformations of the acetylproline molecule in liquids water and chloroform. The corresponding conformations of the acetylproline in liquids water and chloroform are close to the ideal 3(10) helix and the C(7) structure, respectively. A few methods proposed to determine the angle between the two transition dipoles associated with the amide I vibrations were tested and their limitations are discussed.

Journal Article↗
PubMed2005

Calculation of Cl2 vibrational distributions after vibrational predissociation of He2-Cl2.

An approximate model is tested in order to obtain the vibrational distributions of the Cl2 fragment produced after He2-Cl2(B) predissociation, when the dynamics is simulated by a full-dimensional wave-packet method. The model is intended to overcome the limitations imposed to a rigorous calculation of the vibrational distributions by the use of a finite grid size and absorbing boundary conditions. The good agreement found between the present results and the available experimental data indicates that the model is able to provide realistic estimates for the product vibrational distributions.

Journal Article↗
PubMed1974

[Arteriography findings in vibration vascular disease of upper limbs ("vibration angiopahty") (author's transl)].

A bilateral angiographic study of the upper limbs was carried out under general anaesthesia in a group of 81 subjects--mostly (91.3%) miners--using vibrating tools. The patients' age ranged from 30 to 57 years; the time they worked as vibrating tool operators varied from 5 to 36 years; the duration of symptoms ranged from 3 months to 10 years. The mean values were 46.1, 20.9 and 3.7 years, respectively. Seventy-four subjects (91.3%) complained of Raynaud's-like phenomenon, which in 36 (44.4%) of them was elicited too, although partially, by provocative tests (cold exposure). Angiography was carried out under general anaesthesia maintained with halothane. Bilateral angiograms were available in 61 instances; in the remainder, only either right or left angiograms could be obtained. In all the subjects examined arteriographic lesions were found, mainly represented by organic stenoses and occlusions. The prevalance of such lesions was minimal at the level of the forearm arteries, and maximal at the level of the digital arteries. The 2nd finger, bilaterally, was the most frequently involved; the index finger on either side and the middle one on the right side were the most involved as to severity and extent of lesions. The 1st finger, however, was quite frequently involved too. No definite relationship between prevalance, severity and extent of arterial lesions, on one hand, and some history, clinical and functional parameters (such as age, vibrating tool usage time, smoking habit, hand arterial pattern, pulmonary silicosis, instrumental findings and Raynaud's-like phenomenon), on the other hand, could be established. As to Raynaud's-like phenomenon, it is hypothesized that such a finding could be, at least in part of cases, subsequent to the previous development of organic lesions in the digital arteries.

Adult↗