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At least 181 records · Page 10Linked to original sources
PubMed2005

The utilization of nonthermal blue (405-425 nm) and near infrared (850-890 nm) light in aesthetic dermatology and surgery-a multicenter study.

BACKGROUND: A major cause of skin aging is a chronic micro-inflammation triggered by UV radiation and external pollutants. It has been demonstrated that blue light diminishes inflammatory conditions and near infrared light enhances circulation. OBJECTIVES: To assess the effectiveness of a non thermal dual wavelength -- blue (405 - 420 nm) and near infrared (850 - 900 nm) -- light source in skin rejuvenation, in the reduction of the duration of post skin resurfacing erythema and in the acceleration of healing of post surgical conditions (face lift and breast augmentation). METHODS: We have utilized a non contact, hand free dual wavelength light source (iClearXL and Clear100XL, Curelight Ltd) to treat over 60 patients and perform three controlled studies in four centers. Follow up duration was three months. Control group for photo-rejuvenation consisted of patients treated with Glycolic peeling and daily appliance of vitamin C Control group for post skin resurfacing erythema duration consisted of patients untreated by the light source and control group for post surgical healing consisted of patients untreated by the light source or treated by the light source on one side only. RESULTS: Post skin resurfacing erythema duration is reduced by 90%. The healing of post surgical conditions is substantially accelerated and discomfort is reduced. The anti aging effect of the light source includes: reduction of pore size in 90% of patients with stable results at three months follow up, enhanced skin radiance in 90% of patients with stable results at three months follow up and smoothing of fine wrinkles in 45% of patients with stable results at three months follow up. The control group showed poor results which were stable for a duration of less than one month. CONCLUSIONS: A non thermal, non contact / hand free light source emitting at 405-420 nm and 850-900 nm considerably enhances aesthetic and surgical aesthetic procedures without consuming user time.

Chemexfoliation↗
PubMed2000

Visible-light detoxification and charge generation by transition metal chloride modified titania.

Amorphous microporous metal oxides of titanium (AMM-Ti) modified with chlorides of PtIV, IrIV, RhIII, AuIII, PdII, CoII, and NiII have been prepared by the sol-gel method and characterized by various surface analytical methods. These hybrid AMM-Ti powders are catalysts for the photodegradation of 4-chlorophenol (4-CP) in aqueous solution when illuminated with visible (lambda > or = 400 or 455 nm) or UV (lambda > or = 335 nm) light. The initial rate depends on the dopant level and is highest at 3.0% Pt in the case of PtIV/AMM-Ti. When employed in a photoelectrochemical cell, the activity spectrum of the photocurrent extends downward to about 600 nm, as does the photodegradation of 4-CP. It is suggested that the metal salt acts as a redox-active chromophore, transmitting the photogenerated charges to the amorphous matrix.

Catalysis↗
PubMed2004

Photomutagenicity of 16 polycyclic aromatic hydrocarbons from the US EPA priority pollutant list.

The photomutagenicity of 16 polycyclic aromatic hydrocarbons (PAHs), all on the United States Environmental Protection Agency (US EPA) priority pollutant list, was studied. Concomitant exposing the Salmonella typhimurium bacteria strain TA102 to one of the PAHs and light (1.1 J/cm2 UVA+2.1 J/cm2 visible) without the activation enzyme S9, strong photomutagenic response is observed for anthracene, benz[a]anthracene, benzo[ghi]perylene, benzo[a]pyrene, indeno[1,2,3-cd]pyrene, and pyrene. Under the same conditions, acenaphthene, acenaphthylene, benzo[k]fluoranthene, chrysene, and fluorene are weakly photomutagenic. Benzo[b]fluoranthene, fluoranthene, naphthalene, phenanthrene, and dibenz[a,h]anthracene are not photomutagenic. These results indicate that PAHs can be activated by light and become mutagenic in Salmonella TA102 bacteria. At the same time, the mutagenicity for all the 16 PAHs was examined with the standard mutagenicity test with 10% S9 as the activation system. Benzo[b]fluoranthene, benzo[k]fluoranthene, chrysene, acenaphthylene, and fluorene are weakly mutagenic, while the rest of the PAHs are not. In general, the photomutagenicity of PAHs in TA102 does not correlate with their S9-activated mutagenicity in either TA102 or TA98/TA100 since they involve different activation mechanisms.

Animals↗
PubMed2002

Distribution and transportation of polycyclic aromatic hydrocarbons in suspended particulate matter and surface sediment from the Pearl River Estuary.

Based on the quantitative and qualitative analysis of sixteen Polycyclic Aromatic Hydrocarbons (PAHs) with GC and GC-MSD, the concentrate distribution and transportation characteristics of PAHs in suspended particulate matter (SPM) and surface sediments (SS) from the Pearl River Estuary were studied. Whether in SPM or in SS, the concentration distribution of PAHs were characterized by acenaphthene (mean 55.5 microg/g in SPM, 226 ng/g in SS) with subordinate amounts of the tri- and tetra-cycle PAHs such as fluorene, fluoranthene, phenaphene and pyrene. However, PAHs had different composition and concentration in SPM and SS. Pentacyclic PAHs appeared in SS and seldom in SPM because of their low solubility and high molecular weight. The concentrations of the tri-, tetracyclic PAHs in SPM were 100-300 times higher than those in SS. The total PAHs varied from 12-281 microg/g (mean 77 microg/g) in SPM and 208-1849 ng/g (mean 537 ng/g) in SS respectively. There were similar correlations between the concentrations of PAHs in SPM and salinity, and between the distance of the stations from the river outlet moving seawards and the concentrations of PAHs. These indicated that PAHs were degraded or transported along with the salinity gradient in SPM and the distance from the river outlet in SS. It was also suggested that the sources of these PAHs are from sewage and shipping discharge-pollutants. Pearl River Estuary had been lightly contaminated by PAHs.

Environmental Monitoring↗
PubMed2006

Light-dependent transformation of aniline to indole esters by the purple bacterium Rhodobacter sphaeroides OU5.

In an attempt to understand the aromatic hydrocarbon metabolism by purple bacteria that do not grow at their expense, we earlier reported 2-aminobenzoate transformation by a purple non-sulfur bacterium, Rhodobacter sphaeroides OU5 (Sunayana et al., 2005, J Ind Microbiol Biotech 32:41-45), which is extended in the present study with aniline, a major environmental pollutant. Aniline did not support photo (light anaerobic) or chemo (dark aerobic) heterotrophic growth of Rhodobacter sphaeroides OU5 either as a sole source of carbon or nitrogen. However, light-dependent aniline transformation was observed in the culture supernatants and the products were identified as indole derivatives. The transformation was dependent on a tricarboxylate intermediate, fumarate. Five intermediates of the aniline biotransformation pathway were isolated and identified as indole esters having a mass of 443, 441, 279, 189, and 167 with unstoichiometric total indole yields of 0.16 mM: from 5 mM: of aniline consumed. The pathway proposed based on these intermediates suggest a novel xenobiotic detoxification process in bacteria.

Aniline Compounds↗
PubMed2005

Complete mineralization of propyzamide in aqueous solution containing TiO2 particles and H2O2 by the simultaneous irradiation of light and ultrasonic waves.

Environmental problems arise from the pollution of ground water and soil by propyzamide, 3,5-dichloro-N-(3-methyl-1-butyn-3-yl) benzamide, which is a popular herbicide. To decompose propyzamide, aqueous solutions containing propyzamide and TiO2 particles was irradiated by light. The photocatalytic decomposition was accelerated when the solution temperature and pH were high. The temperature dependence was due to the adsorption processes of propyzamide on the TiO2 particles. The decomposition was further promoted by addition of H2O2 because of its effective electron-trapping and generated *OH which was available to decompose propyzamide. Although no propyzamide was detected in the solution after the irradiation time of about 20 min, the decomposed intermediate compounds still remained. In order to mineralize completely propyzamide, simultaneous irradiation by light and ultrasonic waves was carried out. The hybrid effect of the irradiation by light and ultrasonic waves in conjunction with H2O2 was first confirmed to achieve the complete mineralization of propyzamide.

Journal Article↗
PubMed2003

N:P ratios, light limitation, and cyanobacterial dominance in a subtropical lake impacted by non-point source nutrient pollution.

A long-term (28-year) data set was used to investigate historical changes in concentrations of phosphorus (P), nitrogen (N), N:P ratios, and Secchi disk transparency in a shallow subtropical lake (Lake Okeechobee, Florida, USA). The aim was to evaluate changes in the risk of N2-fixing cyanobacterial blooms, which have infrequently occurred in the lake's pelagic zone. Predictions regarding bloom risk were based on previously published N:P ratio models. Temporal trends in the biomass of cyanobacteria were evaluated using phytoplankton data collected in 1974, 1989-1992, and 1997-2000. Concentrations of pelagic total P increased from near 50 microg l-1 in the mid-1970s to over 100 microg l-1 in the late 1990s. Coincidentally, the total N:P (mass) ratio decreased from 30:1 to below 15:1, and soluble N:P ratio decreased from 15:1 to near 6:1, in the lake water. Published empirical models predict that current conditions favor cyanobacteria. The observations confirm this prediction: cyanobacteria presently account for 50-80% of total phytoplankton biovolume. The historical decrease in TN:TP ratio in the lake can be attributed to a decreased TN:TP ratio in the inflow water and to a decline in the lake's assimilation of P, relative to N. Coincident with these declines in total and soluble N:P ratios, Secchi disk transparency declined from 0.6 m to near 0.3 m, possibly due to increased mineral turbidity in the lake water. Empirical models predict that under the turbid, low irradiance conditions that prevail in this lake, non-heterocystous cyanobacteria should dominate the phytoplankton. Our observations confirmed this prediction: non-N2-fixing taxa (primarily Oscillatoria and Lyngbya spp.) typically dominated the cyanobacteria community during the last decade. The only exception was a year with very low water levels, when heterocystous N2-fixing Anabaena became dominant. In the near-shore regions of this shallow lake, low N:P ratios potentially favor blooms of N2-fixing cyanobacteria, but their occurrence in the pelagic zone is restricted by low irradiance and lack of stable stratification.

Anabaena↗
PubMed1992

Pollution prevention as a market-enhancing strategy: a storehouse of economical and environmental opportunities.

EPA's (Environmental Protection Agency) Green Lights Program for energy-efficient lighting illustrates the economic benefits and the market-transforming value of a pollution prevention philosophy. Using technologies available today, and assuming current prices, this program is expected to reduce air pollution 5%, while saving the nation's businesses up to 20 billion in electric bills every year. However, these pollution prevention and savings estimates may be low. As Green Lights transforms the market for lighting services by creating a higher demand for better technologies at lower costs, the program will likely achieve even larger pollution reductions and electricity savings.

Journal Article↗
PubMed2006

Critique of "Precipitation in light extinction reconstruction" by P.A. Ryan.

The goal of the Regional Haze Rule (RHR) is to return visibility in class I areas (CIAs) to natural levels, excluding weather-related events, by 2064. Whereas visibility, the seeing of scenic vistas, is a near instantaneous and sight-path-dependent phenomenon, reasonable progress toward the RHR goal is assessed by tracking the incremental changes in 5-yr average visibility. Visibility is assessed using a haze metric estimated from 24-hr average aerosol measurements that are made at one location representative of the CIA. It is assumed that, over the 5-yr average, the aerosol loadings and relative humidity along all of the site paths are the same and can be estimated from the 24-hr measurements. It is further assumed that any time a site path may be obscured by weather (e.g., clouds and precipitation), there are other site paths within the CIA that are not. Therefore, when calculating the haze metric, sampling days are not filtered for weather conditions. This assumption was tested by examining precipitation data from multiple monitors for four CIAs. It is shown that, in general, precipitation did not concurrently occur at all monitors for a CIA, and precipitation typically occurred 3-8 hr or less in a day. In a recent paper in this journal, Ryan asserts that the haze metric should include contributions from precipitation and conducted a quantitative assessment incorrectly based on the assumption that the Optec NGN-2 nephelometer measurements include the effects of precipitation. However, these instruments are programmed to shut down during rain events, and any data logged are in error. He further assumes that precipitation occurs as often on the haziest days as the clearest days and that precipitation light scattering (bprecip) is independent of geographic location and applied an average bprecip derived for Great Smoky Mountains to diverse locations including the Grand Canyon. Both of these assumptions are shown to be in error.

Air Pollutants↗
PubMedDate not supplied

Dermatological risk of indoor ultraviolet exposure from contemporary lighting sources.

Discussions of risks and implications of cutaneous exposure to indoor lighting, including hypothetical contribution to causality of melanoma, have mainly concentrated on ultraviolet (UV) A and B (UVA, UVB) spectral emissions from fluorescent bulbs. Only studies of quartz halogen lamps have suggested that users might sustain UVC-induced injury. Examination of light sources in the home and school of a child with xeroderma pigmentosum revealed that several different types emitted surprising levels of UV. Our purpose was to assess the extent of UV emissions from a variety of commonly used light sources to identify potential dermatological risks. UV and visible spectral emissions of commercially obtained lamps of several types were measured using a calibrated spectral radiometer traceable to the National Institute of Standards and Technology. Indoor light sources including fluorescent, quartz halogen and even tungsten filament incandescent lamps provided UVA, UVB and sometimes UVC emissions. Intensities of some emissions were of similar magnitude to those in sunlight. Chronic exposure to indoor lighting may deliver unexpected cumulative UV exposure to the skin and eyes. Patients with UV-exacerbated dermatoses should be cautioned about potential adverse reactions from indoor lighting.

Air Pollution, Indoor↗
PubMed1992

The current position of poikilotherms.

The major research themes in poikilotherm leukaemias, and their progress over the past two years are reviewed. Despite the fact that poikilotherms represent 99% of the animal world including man, background knowledge on most poikilotherm species is sparse. Furthermore, haemic systems in many poikilotherms have functions different to those of homeotherms. Most progress is being made in relation to lethal blood mutant neoplasms in Drosophila, leukaemias of farmed salmonids among the fishes, and among shellfish, the hemic sarcomas of bivalves. The hypothesis that epizootic neoplasia in fish and shellfish populations could be indicative of environmental pollution is being refined in the light of recent studies; environmental xenobiotics are no longer considered to play a primary aetiological role in either lymphomas and leukaemias of fish or haemic sarcomas of bivalves, although xenobiotics may have a primary role in other poikilotherm neoplasms.

Animals↗
PubMed2001

The rate improvement and modeling of trichloroethene photodegradation by acetone sensitizer in surfactant solution.

The photodecay of trichloroethene (TCE) in surfactant solution by the help of photosensitizer (acetone, ACE) was investigated and modeled. Apart from the direct photodegradation, photosensitization is presumed to be one of the major mechanisms contributing to overall decay. Quantum yields of TCE photodecay in solution with surfactant Brij 35 and optimal ACE dosage are about 25 times higher than in Brij 35 alone. However, with an excess ACE dosage, ACE will act as a light barrier and attenuate the light intensity available for TCE photodegradation. TCE photodegradation follows a two-stage kinetics, in which a lag phase is followed by a fast decay. Mathematical models were developed for the prediction of the two-stage photodegradation, in which the remaining fraction of TCE (C/C0) in the system becomes predictable.

Acetone↗
PubMed2001

Study of Au/Au(3+)-TiO2 photocatalysts toward visible photooxidation for water and wastewater treatment.

With an attempt to extend light absorption of TiO2-based photocatalyst toward the visible light range and eliminate the rapid recombination of excited electrons/holes during photoreaction, a new type of photocatalysts (Au/Au(3+)-TiO2) powder was prepared by a photoreduction/sol-gel process. The crystal phase composition, surface structure, and light absorption of the new photocatalysts were comprehensively examined by X-ray differential detection (XRD), UV-visible absorption spectra, X-ray photoelectron emission spectroscopy (XPS), and photoluminescence (PL) spectra. The photooxidation efficiencies of the photocatalysts were also evaluated in the photodegradation of methylene blue (MB) in aqueous solutions under visible light irradiation from a high-pressure sodium lamp (lambda > 400 nm). The results of PL analyses in this study indicated that the gold/gold ion-doping on the surface of TiO2 could eliminate the electron/holes recombination and also increase the light absorption in the visible range. The analytical results of UV-visible diffuse reflection spectra (DRS) and optical absorption spectra indicated that a new energy level below 3.2 eV generated in the Au/Au(3+)-TiO2 promoted the optical absorption in the visible region and made it possible to be excited by visible light (E < 3.2 eV). The experiment demonstrated that the photooxidation efficiency of MB using the Au/Au(3+)-TiO2 powder were significantly higher than that using conventional TiO2 powder and an optimum molar content of gold doping/deposition in the TiO2 was 0.5%. The development of such photocatalysts may be considered a breakthrough in large-scale utilization of solar energy to address environmental needs.

Air Pollutants↗
PubMed2002

Morphological plasticity in metal-sequestering earthworm chloragocytes: morphometric electron microscopy provides a biomarker. of exposure in field populations.

Morphometric measurements of the volume fractions (Vv) of two prominent metal-sequestering compartments, chloragosome granules and debris vesicles, were made on transmission electron micrographs of chloragocytes in Dendrodrilus rubidus (Annelida: Oligochaeta: Lumbricidae) from one uncontaminated site and three qualitatively and quantitatively different metalliferous soils associated with disused Pb/Zn mines. We also examined the relative volume fractions of the alimentary wall and attached chloragogenous tissue by light microscopy. Several conclusions relevant to environmental diagnostics were reached: Metal identity and degree of soil pollution exert strong effects on chloragocyte ultrastructure; morphometry by light microscopy indicated that the metal-induced structural effects are characterized by intracellular alterations not accompanied by a significant expansion of the tissue volume; elevated metal burdens can reduce chloragosome Vv and, concomitantly, increase the Vv of their autophagic derivatives, the debris vesicles; the measured cellular alterations were more closely correlated with integrated tissue metal burdens than they were with integrated soil metal burdens; and estimates of tissue metal distribution, derived by combining morphometric data and published whole-worm and chloragosome metal concentrations, suggested that the alimentary wall of earthworms may sequester Pb, Zn, and Cd. Our study shows that cellular changes, directly or indirectly, may yield quantifiable expressions of metal loads bioaccumulated by earthworms. However, the practical use of cellular changes as biomarkers of soil quality probably will require automated light-microscopic morphometry in combination with organelle-specific molecular probes to be cost effective.

Animals↗
PubMed2005

Enhanced photodegradation of 2,4,6-trichlorophenol over palladium phthalocyaninesulfonate modified organobentonite.

This article explores a supported photocatalyst of palladium(II) phthalocyaninesulfonate (PdPcS) onto organoclay for removal of 2,4,6-trichlorophenol (TCP) from water under visible light (lambda > or = 450 nm) irradiation. The composite clay was not only a good sorbent for uptake of TCP from water, but it also exhibited notable activity for TCP oxidation via singlet molecular oxygen, generated in situ from PdPcS photosensitization. Complete dechlorination of TCP could be achieved after TCP was totally oxidized. The initial rate of TCP degradation was observed to increase with the initial amount of TCP sorption, the kinetics following well the Langmuir-Hinshelwood equation. The resulting rate constant of TCP oxidation was found to increase with the alkyl chain length of the intercalated surfactant from dodecyltrimethylammonium to cetyltrimethylammonium and to octadecyltrimethylammonium. Such the trend in photoactivity was in agreement with the catalyst capacity for TCP sorption from aqueous medium. The result showed that enrichment of toxic TCP on the catalyst was indeed an efficient way for enhancement of the photosensitized degradation of target pollutant. However, PdPcS loading led to a notable decrease in TCP sorption, because of partial blocking of the sorptive sites. The optimal loading of PdPcS was about 1.0 wt %. The catalyst was characterized by nitrogen adsorption, X-ray diffraction, visible diffuse reflectance spectroscopy, and TCP sorption, which revealed that the incorporated PdPcS, mainly in the form of photoactive monomer, coexisted with the intercalated surfactant in the bentonite interlayers. Seven repeated experiments demonstrated that the composite clay was relatively stable and could be repeatedly used for sorption and degradation of TCP pollutant via molecular oxygen and visible light.

Journal Article↗
PubMed2005

Photoenhanced uptake of gaseous NO2 on solid organic compounds: a photochemical source of HONO?

In several recent field campaigns the existence of a strong daytime source of nitrous acid was demonstrated. The mechanism of this source remains unclear. Accordingly, in the present laboratory study, the effect of light (in the range 300-500 nm) on the uptake kinetics of NO2 on various surfaces taken as proxies for organic surfaces encountered in the troposphere (as organic aerosol but also ground surfaces) was investigated. In this collaborative study, the uptake kinetics and product formation rate were measured by different flow tube reactors in combination with a sensitive HONO instrument. Uptake on light absorbing aromatic compounds was significantly enhanced when irradiated with light of 300-420 nm, and HONO was formed with high yield when the gas was humidified. Especially organic substrates containing a combination of electron donors, such as phenols, and of compounds yielding excited triplet states, such as aromatic ketones, showed a high reactivity towards NO2. Based on the results reported a mechanism is suggested, in which photosensitised electron transfer is occurring. The results show that HONO can be efficiently formed during the day in the atmosphere at much longer wavelengths compared to the recently proposed nitrate photolysis.

Aerosols↗