Mercury Light Research Articles

Influence of Mercury(II) and UV Light on the Reaction of Pentacyanoferrate (II) Ions with Oximes

Abstract Mercury(II) ions catalyze the reaction of sodium aquopentacyanoferrate(II) with bidentate oximes and inhibit it with monodentate oximes. UV light increases the reaction rate of complex formation with all the examined oximes except pyridine-4-aldoxime.

Photoconducting TiO 2 prepared by spray pyrolysis using TiCl 4

TiO 2 was prepared by the oxidation of TiCl 4 at relatively low deposition temperatures using spray pyrolysis. For a fixed carrier gas (N 2) flow rate, the substrate temperature is the critical parameter determining the film properties. Films made near 595 K contain only the anatase phase, adhere well to the glass substrate, and have a relative optical transmission of about 75% (between 450 and 850 nm), the value one calculates for the non-absorbing anatase phase in this region. These films have an absorption edge characteristic of a direct gap semiconductor with allowed transitions and optical gaps of 3.5–3.7 eV, depending on the porosity. At higher substrate temperatures (above 635 K), the resulting films have a cloudy appearance and they contain both the rutile and the anatase modifications, confirmed by X-ray diffraction. Lower temperature substrates reduce the deposition rate and yield more porous films. For the pure anatase films, the dark conductivities are about one order of magnitude larger, and the photoconductivity is about one order of magnitude smaller when measured with the sample in air, than those observed when the sample is in a vacuum. When the samples are in a vacuum, the conductivities of the clear films increase by about two orders of magnitude (from about 10 −10 to about 10 −8 S cm −1) when illuminated with light from an electrically programmable read-only memory eraser (mercury light), which gives an intensity of about 30 μW cm −2 at the sample. The photoresponse has two parts; the fast portion rises in less than 1 s to 99% of its final value, followed by a small slow rise portion. The slow response, which is more pronounced in the decay process, is interpreted as being due to the presence of surface trapping states.

14,15-Epoxyeicosatrienoic acid inhibits platelet aggregation in mouse cerebral arterioles.

Epoxygenase metabolites of arachidonic acid are produced by several tissues and have been shown to inhibit in vitro platelet aggregation. The purpose of the present investigation was to determine whether 14,15- or 8,9-epoxyeicosatrienoic acid, epoxygenase derivatives of arachidonic acid, affect the speed of platelet aggregation in in vivo mouse cerebral arterioles. We performed a craniectomy in 116 anesthetized male mice and observed the pial arterioles by microscopy. We induced in situ platelet aggregation using a mercury light and intravascularly injected fluorescein dye. Indomethacin (0.5 mg/kg i.p.), a known cyclooxygenase inhibitor, and 14,15-epoxyeicosatrienoic acid (0.3 mg/kg i.v.) increased the time necessary for the light plus dye to induce the first arterial platelet aggregate by 35% and 26%, respectively, whereas 8,9-epoxyeicosatrienoic acid (0.3 mg/kg i.v.) had no effect. Analysis of mouse serum by radioimmunoassay showed that the degree of inhibition of platelet aggregation by indomethacin and epoxyeicosatrienoic acids correlated with the degree of inhibition of thromboxane production. We conclude that 14,15-epoxyeicosatrienoic acid is a potent inhibitor of in vivo platelet aggregation but cannot conclusively confirm that its effect on aggregation occurs via its reduction of platelet thromboxane A2. Because epoxyeicosatrienoic acids are produced by several tissues, including brain and vascular tissue, they may be important in vivo modulators of platelet aggregation and hemostasis.

Dévalaison des smolts et efficacité d'un exutoire de dévalaison à l'usine hydroélectrique d'Halsou sur la Nive

SUMMARY Downstream migration of Atlantic salmon (Salmo salar) smolts in river Nive South­ west France was studied in 1987 and 1988 to access the effectiveness of a fish bypass structure at the hydroelectric plant of Halsou. Passage of fish was determined by trapping and video recording. Daily, diurnal and hourly passages at bypass were determined. Tests with marked fish showed between 42 % and 95 % of the smolts used the surface bypass. Significantly more smolts were bypassed when the discharge was increased. Exploratory tests with halogen and mercury lights were performed. Visual observation indicated that fish was attracted to the lights but avoided the point source : results showed an increased rate of passage when the lamps lighting up the bypass were turned off.

Photothermal ignition of dichlormethane and chlorine gas mixtures

We examine the temperature regime in the ignition of mixtures of dichlormethane and chlorine subjected to the effects of a beam of mercury light. In mixtures with a dichlormethane concentration below the lowest concentration limit of ignition the reaction occurs in a nonisothermal regime, with considerable heating of the mixture. With a higher dichlormethane concentration the reaction is explosive in nature, and the mixture is ignited. We have investigated the inhibiting of the photoignition process with oxygen. We have demonstrated that for purposes of describing the photoignition process during the initial period it is possible to use the equation for the rate of the reaction, derived under the assumption of quasisteadiness in the active particles.

Angiotensin II induces endothelium-dependent vasodilation of rat cerebral arterioles

We evaluated the response of cerebral arterioles to angiotensin II (ANG II) in anesthetized rats equipped with a closed cranial window. Topical application of 10(-10)-10(-5) M ANG II induced dose-dependent arteriolar vasodilation. Maximum vasodilation of 24 +/- 2.2% (+/- SE) was attained at a concentration of 10(-6) M ANG II. The dilation in response to ANG II was blocked by 3 micrograms/ml indomethacin, a cyclooxygenase inhibitor, and was reversed to minimal vasoconstriction by 10(-5) M methylene blue, a substance that has been reported to eliminate endothelium-dependent vasodilation. Coapplication of indomethacin with methylene blue reduced the arteriolar response to ANG II to a similar extent as the application of indomethacin alone. Indomethacin or methylene blue did not inhibit the vasodilation induced by 10(-5) M adenosine, which is not endothelium and cyclooxygenase dependent. Mercury light illumination of the pial vessels after intravenous injection of fluorescein dye, a technique that has been used by others to functionally damage endothelial cells, reversed ANG II (10(-6) M)-induced vasodilation into a -14.2 +/- 2.3% constriction while not affecting the response to adenosine. Our data suggest that ANG II produces vasodilator responses of rat cerebral arterioles by the release of a factor that is derived from the endothelium and may be generated through a cyclooxygenase-dependent mechanism.

Enhanced ultraviolet detection in high-performance liquid chromatographic analysis of drugs by “on-line” photochemical reaction

The effect of on-line photochemical reaction on UV detection in high-performance liquid chromatography (HPLC) has been studied. For on-line irradiation a photoreactor utilizing a low pressure mercury light source and a crocheted reaction capillary has been used by which the chromatographic performance of the HPLC separation is only slightly influenced. On-line irradiation of the drugs methadone, methoin, nirvanol and several barbiturate analogues results in a significant increase in their UV absorptivity, either due to the appearance of new spectral bands or due to absorption enhancement at longer UV wavelengths. By these photochemical effects, the detectability of drugs at longer UV wavelengths will be increased, in some cases more than 80-fold. Thus routine analysis of these drugs in biological samples may be simplified considerably, allowing more specific detection and less complex sample preparation.

In vivo studies of pial vascular permeability to sodium fluorescein: absence of alterations by bradykinin, histamine, serotonin, or arachidonic acid.

We studied pial vessels in vivo in mice, examining under mercury light the permeability of these vessels to sodium fluorescein. Topical application of hypertonic solutions of NaCl caused leakage of fluorescein. However, putative chemical mediators of leakage, such as histamine, serotonin, arachidonic acid, and bradykinin, all failed to increase permeability to the dye. Apparent increases in permeability only accompanied endothelial damage caused by the dye + light combination, as indicated by production of local platelet aggregates. The technique is useful, provided inadvertent endothelial injury is recognized and avoided. The data in mice suggest that pial vessels may not participate in the permeability changes reportedly produced in parenchymal brain vessels by several of the mediators we tested. Therefore, studies of pial vascular permeability are not expected to provide reliable data concerning the actions of agents that might mediate cerebral edema.

Ultrastructural studies of pial vascular endothelium following damage resulting in loss of endothelium-dependent relaxation.

The changes in pial arterioles of 7 cats were examined by electron microscopy after injury that eliminates endothelium-dependent relaxation to acetylcholine or bradykinin. The injury was produced by exposing the vessels to mercury light in situ in the presence of intravascular sodium fluorescein dye. Previous studies showed that, at the time of initial injury and loss of endothelium-dependent responses, the endothelial cells displayed minimal ultrastructural evidence of injury. Because these changes might indicate the beginning of a sequence of irreversible alterations representing or leading to cell death, the present study was carried out 31/2-4 hours later, when ultrastructural evidence of progressive cell degeneration should readily be recognized. No such changes were observed. Instead, most vessels showed only the minimal alterations observed initially (endothelial vacuolation, blebs, and lucencies). Four of 19 vessels were completely normal. The findings fail to support the hypothesis that irreversible cell damage or death caused by the light + dye injury has caused the associated loss of endothelium-dependent relaxation. Rather, the findings support the concept that much lesser degrees of trauma are sufficient to impair the dilating responses of cerebral microvessels. This greatly expands the potential spectrum of pathologic states that might result in loss of endothelium-dependent relaxation.

Photoreaktionen von Biscyclopentadienyltitandichlorid in einer monomerhaltigen polymethylmethacrylat‐matrix

AbstractIt could be demonstrated that methyl methacrylate (MMA) in a poly(methyl methacrylate) (PMMA)‐matrix can be polymerized by photoinduction with titaniumbiscyclopentadienyl dichloride (titanocene chloride). The photoinduced polymerized portion of MMA consists practically only of isotactic PMMA. The differences in polymerization by irradiation with laser light and with monochromatic light of a mercury light source with the same wavelength are discussed.

Temperature-dependence of electric and photovoltaic properties of HgTe thin film

The I–V characteristics of an illuminated thin film of HgTe and of a dark sample were recorded. The high values of the photoelectric current of the illuminated sample as the distance decreased may be due to the impurity conductivity, that can be higher than the band conduction predominating at higher incident energy. In the dark, the impurity conductivity is always low compared to the band conductivity occurring at the higher incident energy of mercury light. The low mobility and the increase of the activation energy with increasing temperature suggest that more than one conduction mechanism is involved. The high density of acceptor centres in the thin layer of HgTe may affect the conduction current in certain temperature ranges.The dielectric constant of the HgTe thin film was measured at different temperatures. The increase of the dielectric constant might be due to point defects which are Hg-vacancy or Te-interstitial acceptors. HgTe has an excess of Te and the net hole concentration (p-n) can be altered by increasing the ionized acceptor defects which migrate through the cubic crystallites to accumulate at the electrodes, giving rise to the dielectric constant.

Photo-polymerization of vacuum evaporated amorphous (As 2S 3) 1− x(As 2Se 3) xsystems

Photo-induced changes of the infrared absorption spectra in vacuum evaporated amorphous As 2S 3As 2Se 3 systems are studied in the wave number region 100–500 cm −1 at room and liquid nitrogen temperatures, and conversion of the species of the molecular units and local structures of these systems are studied. After mercury light irradiation the spectrum becomes similar to that of a thermally annealed sample, accordingly, similar to that of a bulk material. Just after evaporation, such molecular units as As 4, As 4S 3, As 4S 4, S 8, As 4Se 4, etc. may be bonded by Van der Waals forces, and the observed photo-induced changes in the infrared absorption spectra are interpreted by rearrangement (polymerization) of bonding configurations.

Über die quantenausbeute der kettenspaltung von polystyrol in lösung bei bestrahlung mit wellenlängen λ ≧ 270 nm

AbstractValues of the mean number of chain scissions per macromolecule and the quantum efficiency of chain scission processes are presented for systems studied in our previous works, in which the photodegradation of polystyrene in solutions irradiated with mercury light (λ ≧ 270 nm) was investigated and changes of the weight‐average molecular weight M̄w were considered to be a measure for chain scission. The presented values of the number of scissions were obtained as follows: the molar mass distributions were determined for the investigated polystyrene samples by dynamic (quasielastic) light scattering experiments, before and after irradiation, the number‐average molecular weight values M̄n were calculated from these distributions and the mean number of scissions was obtained from the changes of the M̄n values.

ChemInform Abstract: ELECTROCHEMICAL INITIATION OF CRYSTALLIZATION OF AMORPHOUS SELENIUM

AbstractI.l V gegen SCE setz die Umwandlung in das trigonale Allotrope in Verbindung mit der kathodischen Auflösung des Se ein.

Electrochemical initiation of crystallization of amorphous selenium

Vapour deposited films of amorphous selenium on conducting tin oxide glass are stable at open circuit or positive potentials when in contact with acetonitrile containing 0.1 M tetraethylammonium perchlorate. At −1.1 V vs sce transformation to the trigonal allotrope is initiated together with the cathodic dissolution of Se. Crystallization begins at more positive potentials under irradiation by a low pressure mercury light. In contact with aqueous electrolyte, cathodic dissolution occurs without crystallization, while in contact with dimethylformamide, crystallization precedes dissolution but can be inhibited by positive potentials. A simple model is proposed to rationalize these observations.

Attraction of Fish to Mercury Vapour Light and Its Application in a Generating Station Forebay

AbstractLaboratory and field tests were conducted to determine the effectiveness of filtered mercury vapour lights in attracting fish with possible utilization in a fish conserving scheme at an electrical generating station. In laboratory tests, alewife demonstrated an attraction to the mercury vapour light which was associated with an increase in swimming activity. This response was maintained over a 48‐hour period. When the filtered mercury vapour lights were utilized in association with a fish pump in the Nanticoke Generating Station forebay, juvenile gizzard shad and smelt were attracted to the pump area. Although there was variation with time of day, tubidity and lighting array; the results suggested that the number of fish passing through the pump increased when the mercury vapour lights alone or when the mercury lights in association with a white strobe light were employed.

Standardization of Formaldehyde-Induced Fluoresecence and its Measurement to Quantify Serotonim Emission in Pulmonary Neuroendocrine Cells

We describe a modified and standardized quantitative FIF procedure for producing fluorophores and measuring emission intensity of serotonin-containing neuroepithelial bodies (NEB's) in the rabbit lung. This technique, using epifluorescence, was reproduced without significant differences between control groups. Important considerations for reproducibility were: using the same humidity (80% RH) and reaction time (2 h) during the vapor treatment, sectioning at constant relative humidity, avoiding unnecessary heating (sections should not be stretched over a hot plate) and avoiding exposure of sections to light. Optimal emission readings were obtained with sectioning and mounting at 40--50% RH. Readings were reduced by 25% when the mercury light source was switched from 200 W to 100 W. It was also important to let the instruments warm up long enough to avoid drift during quantitation. Each NEB should be subjected to the same duration of light exposure for alignment (30 s) before measuring fluorescence to avoid differences from photodecomposition.

Standardization of formaldehyde-induced fluorescence and its measurement to quantify serotonin emission in pulmonary neuroendocrine cells

We describe a modified and standardized quantitative FIF procedure for producing fluorophores and measuring emission intensity of serotonin-containing neuroepithelial bodies (NEB's) in the rabbit lung. This technique, using epifluorescence, was reproduced without significant differences between control groups. Important considerations for reproducibility were: using the same humidity (80% RH) and reaction time (2 h) during the vapor treatment, sectioning at constant relative humidity, avoiding unnecessary heating (sections should not be stretched over a hot plate) and avoiding exposure of sections to light. Optimal emission readings were obtained with sectioning and mounting at 40--50% RH. Readings were reduced by 25% when the mercury light source was switched from 200 W to 100 W. It was also important to let the instruments warm up long enough to avoid drift during quantitation. Each NEB should be subjected to the same duration of light exposure for alignment (30 s) before measuring fluorescence to avoid differences from photodecomposition.

Photolysis of MAg 4I 5 superionic films

Photolysis studies on MAg 4I 5 films are reported. The electrical conductivities of MAg 4I 5 films have been found to change when exposed to mercury light. This is explained on the basis of a model similar to Mott-Gurney theory of photolysis for silver halides. The formation of silver specks has been confirmed by photomicrographic studies.

Direct measurement of the dispersion of the refractive index of compressed argon with yellow mercury light

An interference technique is presented which determines directly the dispersion of the refractive index of compressed gases with yellow mercury doublet.