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At least 1,063 records · Page 59Linked to original sources
PubMedDate not supplied

Chromate reduction by chromium-resistant bacteria isolated from soils contaminated with dichromate.

Extensive use of hexavalent chromium [Cr(VI)] in various industrial applications has caused substantial environmental contamination. Chromium-resistant bacteria isolated from soils can be used to remove toxic Cr(VI) from contaminated environments. This study was conducted to isolate chromium-resistant bacteria from soils contaminated with dichromate and describes the effects of some environmental factors such as pH, temperature, and time on Cr(VI) reduction and resistance. We found that chromium-resistant bacteria can tolerate 2500 mg L(-1) Cr(VI), but most of the isolates tolerated and reduced Cr(VI) at concentrations lower than 1500 mg L(-1). Chromate reduction activity of whole cells was detected in five isolates. Most of these isolates belong to the genus Bacillus as identified by the 16S rRNA gene sequencing. Maximal Cr(VI) reduction was observed at the optimum pH (7.0-9.0) and temperature (30 degrees C) of growth. One bacterial isolate (Bacillus sp. ES 29) was able to aerobically reduce 90% of Cr(VI) in six hours. The Cr(VI) reduction activity of the whole cells of five isolates had a K(M) of 0.271 (2.61 mM) to 1.51 mg L(-1) (14.50 mM) and a V(max) of 88.4 (14.17 nmol min(-1)) to 489 mg L9-1) h(-1) (78.36 nmol min(-1)). Our consortia and monocultures of these isolates can be useful for Cr(VI) detoxification at low and high concentrations in Cr(VI)-contaminated environments and under a wide range of environmental conditions.

Bacillus↗
PubMedDate not supplied

Occurrence of metals in soil and ground water near chromated copper arsenate-treated utility poles.

To thoroughly investigate the metal contamination around chromated copper arsenate (CCA)/polyethylene glycol (PEG)-treated utility poles, a total of 189 soil samples obtained from different depths and distances near six treated poles in the Montreal area (Canada) were analyzed for Cu, Cr, and As content. Various soil physicochemical properties were also determined. Ground water samples collected below the poles were analyzed for metals and bioassays with Daphnia magna were conducted. Generally, sandy soils had lower contaminant levels than clayey and organic soils. Copper concentrations in soil were highest followed by As and Cr. The highest Cu (1460 +/- 677 mg kg(-1)), As (410 +/- 150 mg kg(-1)), and Cr (287 +/- 32 mg kg(-1)) concentrations were found at the ground line and immediately adjacent to the pole. Contaminant levels then decreased with distance, approaching background levels within 0.1 m from the pole for Cr and 0.5 m for Cu and As. Chromium and Cu levels generally approached background levels at a depth of 0.5 m. Average As content near the pole on all study sites was three to eight times higher than Quebec's Level C criterion (50 mg kg(-1)), although it dropped to 31 mg kg(-1) at 0.1 m. Results also showed that As persisted up to 1 m in soil depth (17-54 mg kg(-1)). Copper and Cr concentrations in ground water samples were always <1.000 mg L(-1) and <0.05 mg L(-1), respectively and Cr(VI) was <0.02 mg L(-1). One sample contained an As concentration >0.025 mg L(-1) but bioassays showed that, overall, ground water had a low ecotoxic potential.

Aluminum Silicates↗
PubMed1989

[Chromatic studies of porcelain veneered crown. Application of ceramco opaque porcelain].

Chromatic characteristics were compared between the porcelain fused metal substructures using a gold alloy and a nickel-chromium alloy with or without superficially sprayed with gold alloy. From the stand point of the hiding efficiency for the metallic color of the substructure by opaque porcelain fusing, the gold alloy and the sprayed nickel-chromium alloy were superior to the nickel-chromium one as a metal for the porcelain-fused-to-metal crown. The likeness in color of the gold alloy and the sprayed one was also shown. As the conclusion, the application of wire explosion spraying technique which combines the advantages of the gold alloy and the nickel-chromium one appears to be quite useful for providing an excellent substructure for porcelain-fused crowns.

Chromium Alloys↗
PubMed2006

An unusual local reaction after microsclerotherapy with chromated glycerin.

A case of papular itching lesions after microsclerotherapy with chromated glycerin (CG) at a 72% concentration for telangiectases of the thighs is reported. Patch-test results were strongly positive for nickel sulfate (+++/+++) and thimerosal (++/++) whereas results were negative for the sclerosing agent CG 72% and glycerol (control). Intradermal injection of CG 72% in the thigh and intravascular injection of CG 72% into telangiectases of the knee produced erythematous papular itching lesions in about 5 to 6 hours. As a negative control, glycerol and sodium chloride 0.9% injected intradermically on the thigh did not cause any reaction. CG can elicit allergic reactions in patients who are sensitive to chromium and can cause new sensitizations to chromium. In our case, no positivity to potassium dichromate was observed.

Alum Compounds↗
PubMed1994

Cross-reactivity to metal compounds studied in guinea pigs induced with chromate or cobalt.

Multiple sensitivity to metals is often seen in humans. This may be due to cross-reactivity or to multiple sensitization. The pattern of cross-reactivity to some metal compounds was studied, using the guinea pig maximization test method. Animals were induced with K2Cr2O7 and CoCl2, respectively, and then challenged with K2Cr2O7, CoCl2, NiSO4, PdCl2 and RhCl3. No simultaneous reactivity was recorded. This supports the view that simultaneous reactivity in patients to nickel-cobalt and to chromate-cobalt is due to multiple exposure and sensitization, and not to cross-reactivity. The purity of the test compounds was analysed.

Animals↗
PubMed1980

The solution of achromatic and chromatic Embedded Figures revisited.

Two samples of 20 males and 20 females each were drawn from two Eastern universities. Each of these two samples was presented with the 12-item Form B of Witkin's Embedded Figures Test, with half of each sex receiving the achromatic and half the chromatic format. As in the previous experiment (Bush & Coward, 1974), neither replication yielded a significant difference in mean solution time attributable to the effects of color. However, unlike the previous investigation, no sex differences were observed.

Adult↗
PubMed1981

Effect of auditory stimulation of subjects' chromatic visual fields.

The chromatic visual field of 14 subjects was measured while they heard a sound of 1000 Hz at 95 db during 3 min. Stimuli were produced by a monochromator. Visual threshold was lower under the influence of sound for red (lambda = 550 nm) and green (lambda = 610 nm) stimuli at 40 degrees, 45 degrees, and 50 degrees of temporal eccentricity.

Acoustic Stimulation↗
PubMed1981

Binocular pattern stabilization by afterimage technique: reliability of children's time-dependent judgments of chromatic features.

To investigate visual afterimage technique as a means of producing retinally stabilized pattern, children's judgments of time-dependent shifts in chromatic appearance of random-dot configurations were twice examined within a 3-wk. interval. 13 subjects, aged 7 to 12 yr., were very consistent (r = .93) in their test-retest response times. This supports the belief that after image procedures can be developed as a reliable means of studying developmental aspects of stabilized pattern perception.

Child↗
PubMed1988

Psychophysiology of analysis of connotative decodification: the role of thermic and somesthetic systems in decodification of chromatic stimuli.

We hypothesized that in the decodification of connotative aspects of visual chromatic stimuli the periphery of the body plays an important role. In particular we hypothesized that the decodification process of so called "warm" and "cold" colours is related to a real modification of the temperature of the body which is the basis of the "subjective feeling" and of the attribution of the "emotional meaning" to the stimulus. So we have measured the temperature of the body of 36 female psychology students while they were looking at a luminous screen through spectacles in which filters (coloured lenses) of different colours were placed. Analysis indicated that during the perception of so called "warm" colours a statistically significant increase in the temperature of the body appeared. We observed an enhancement of temperature on the left side of the body during the perception with red and yellow filters and a small increase in temperature on the right side of the body with orange and yellow filters. In the discussion of the results we considered also the role of the cerebral dominance in decodification process of the connotative components of stimuli.

Adult↗
PubMedDate not supplied

Optical fibre-based goniometer for sensing patient position and movement within a magnetic resonance scanner using chromatic modulation.

An optical fibre-based goniometer is described. This instrument was designed to measure the angular position of patients' limbs within the core of a magnetic resonance body scanner, via a 40 m remote fibre-optic link. The sensor exploits the advantages of optical fibre-based sensing, which include immunity to electromagnetic interference, intrinsic safety and chemical immunity. The detection electronics and signal processing are based on the principles of chromatic modulation, an inexpensive, intensity-independent technique in which a change in the spectral power distribution is measured over a broad bandwidth, by photodetectors with differing spectral responses. The optical fibre goniometer has an angular range of 90 degrees, with an average resolution of 2'. The long-term accuracy is within +/- 1 degree, the specified accuracy for the physiological application.

Artifacts↗
PubMed1999

[The effect of overloading from intensive maneuvering on the function of the peripheral chromatic field of vision].

Data on the peripheral chromatic field of vision (PCFV) in pilots after centrifugation and missions with intensive maneuvering associated with accelerations (+Gz) higher than 6 g are presented. Depression of the PCFV area due to hypergravity was most expressed in the shortwave section of the visible spectrum and closely linked with the state of cranial hemodynamics. Changes in PCFV persisted for quite long period, i.e. initial values did not regain following 40 min since exposure to accelerations. Correlation between the degree of PCFV changes and pilot's tolerance to accelerations was established. According to the factual data analysis, the PCFV technique can be used to evaluate the dynamics of G-tolerance during intensive maneuvering aircraft.

Acceleration↗
PubMed1998

[Detection of sister chromatic exchange in workers exposed to coal tar pitch and to coke oven volatiles].

In order to know the changes of genetic toxicological effects on workers occupationally exposed to polycyclic aromatic hydrocarbons (PAHs), sister chromatic exchange(SCE) was detected by the methods of peripheral lymphocyte culture in 23 workers exposed to coal tar pitch (CTP) and in 19 workers exposed to coke oven volatiles (COV) and 12 normal controls. The results suggested that the SCE in occupational workers was significantly higher than that in controls (11.31 vs 6.37, P < 0.001). The SCE in workers exposed to CTP and to COV was higher than that of control (10.27 and 12.58 vs 6.37) respectively. In workers exposed to CTP and COV, there were no differences of SCE for smokers and nonsmokers (P > 0.05). It is indicated that CTP and COV caused strong genetic toxicity and injury to chromosome.

Adult↗
PubMed2000

Quantitative chromatics analysis for computer imaging of cytologic subtypes of lung cancer stained by Papanicolaou stain.

OBJECTIVE: To determine the role of quantitative chromatics analysis in the classification of subtypes of lung cancer stained by Papanicolaou stain. STUDY DESIGN: By means of computer image analysis, 60 keratinized squamous carcinoma cells (KSCC), 88 nonkeratinized squamous carcinoma cells (NKSCC) and 150 adenocarcinoma cells (ACC) from lung cancer in sputum smears stained by Papanicolaou stain were analyzed and distinguished based on quantitative colorimetry. The features measured were the content of three primary colors, red (R), green (G) and blue (B) and the coefficients of R, G and B (r, g and b, respectively). Hue, saturation, brightness and gray level were also measured. A stepwise discriminant analysis was carried out. RESULTS: The values of R, G and B and r, g and b, hue and saturation in NKSCC and ACC were significantly different from those of KSCC, and the changes in the three primary colors were more sensitive than those in the gray level. Computer assessment based on three primary color coefficients, hue and saturation yielded accuracy of distinguishing KSCC from NKSCC and KSCC from ACC of 95.2% and 95%, respectively. CONCLUSION: Quantitative analyses of R, G and B and r, g, b and hue and saturation are valuable in distinguishing KSCC from NKSCC and ACC.

Adenocarcinoma↗
PubMedDate not supplied

[Chromatic fluorescence transitions in bean chloroplasts].

Chromatic fluorescence transients of isolated bean chloroplasts were investigated. In the presence of methylviologen we observed a decrease in the chloroplasts fluorescence under the influence of light which mainly excited the photosystem I. The effects of preliminary illumination with the white light and Mg2+ ions concentration on the fluorescence of chloroplasts were also studied.

Chloroplasts↗
PubMed2004

Effect of sodium valproate on neuromagnetic responses to chromatic flicker: implication for photosensitivity.

The effect of oral administration of sodium valproate in normal subjects was evaluated using whole-scalp magnetoencephalography, with results compared to the effect of sodium valproate in photosensitive children. Neuromagnetic responses to 10 Hz equiluminant red-green and red-blue flicker were measured before and after 5 days of sodium valproate administration. For the red-green flicker, relative power spectra at the stimulus frequency (10 Hz) were attenuated with medication in most brain regions. However, for the red-blue flicker, the 10-Hz power in the occipital region was enhanced with medication, while it was reduced in other regions. These results qualitatively resembled those in photosensitive children. The present findings suggest that (1) combinational chromatic sensitivity can be a critical factor for cortical excitability, that (2) the effect of sodium valproate is qualitatively similar in normal and photosensitive subjects, and that (3) the effect of sodium valproate on cortical excitability is not simply to suppress the stimulus-synchronized occipital activity, but rather to inhibit the spread of cortical activity from the occipital region to other regions.

Adolescent↗
PubMed2006

[Effect of three kinds of rare earth oxides on chromaticity and mechanical properties of zirconia ceramic].

OBJECTIVE: To evaluate the colouration of zirconia ceramic by adding three kinds of rare earth oxides. The influence of the pigments concentration on the mechanical properties and the microstructure was also analyzed. METHODS: Added different concentrations of CeO(2), Er(2)O(3) and Pr(6)O(11) in tetragonal zirconia poly crystals stabilized with 3 mol% yttria (3Y-T2P) powder, compacted at 200 MPa using cold isostatic pressure, and sintered to 1 400 degrees C. The heating rate was 150 degrees C/h and the dwelling time was 2 hours. The chromaticity of sintered bodies was measured with chroma meter. The relative density, hardness, flexure strength and fracture toughness were investigated as well. The phase stability of the colorized and pure zirconia was evaluated by X-ray diffraction (XRD) using an automated diffractometer. The microstructures of the specimens were evaluated by scanning electron microscope (SEM). RESULTS: Several kinds of color achieved by the different pigments praseodym oxide, cerium oxide and erbium oxide were presented in the CIELab system. The a* value increased with the added amount of Er(2)O(3), while b* value rose with the increasing amount of CeO(2) and Pr(6)O(11). However, three pigments failed to decrease L* value and the sintered body appeared too bright. Adding three pigments influenced flexure strength of zirconia ceramic significantly, but had little influence on the hardness and fracture toughness. Microscopy revealed the relationship between the porosity and shapes of grains was correlated to strength of the diphase ceramics. No additional phase could be detected by XRD, except t-ZrO(2) in all colorized samples after sintering at 1 400 degrees C for 120 min. CONCLUSIONS: Zirconia ceramic can be colorized by CeO(2), Er(2)O(3), and Pr(6)O(11). Pigments even in a small amount influence the mechanical properties of the colorized zirconia material, which necessitates further investigation.

Coloring Agents↗
PubMed2006

[Research for De-noising in the detection of chromatic visual evoked potential based on wavelet].

The signal analysis technology based on wavelet was used to detect the chromatic visual evoked potential (VEP). The method was based on wavelet transform modulus maxima reconstruction. The test signal was decomposed using the dyadic discrete time wavelet transform "Mallat" algorithm, and the modulus maxima distribution of each scale was obtained. Signal was de-noised as the Lipschitz coefficient. The POCS method was used to reconstruction the original signal. The news method proved not only good for de-noising but also for decreasing the times of test by the simulation result.

Color↗
PubMed1991

[A comparative evaluation of the results of studies of multi-moment chromatic intubation and cholecystography].

These methods were employed in examinations of 55 patients with various gastrointestinal diseases. The findings of both methods coincided in assessment of gallbladder kinetic function in 36 (66%) patients. In 19 (34%) patients the results did not coincide, in 9 of them multi-moment chromatic duodenal intubation with xylite stimulation has yielded overstated results, and in the remaining 10 patients gallbladder hyperfunction was detected by x-ray examination after egg yolk stimulation. Individual reactions of the body may be responsible for this discrepancy; other explanations are unstable pathologic dysfunction of the gallbladder and the psychoemotional status of patients during the examination.

Adult↗