Mercurous Chloride Research Articles

Effects of mercury electrodeposition on the surface degradation of microlithographically fabricated iridium ultramicroelectrodes

The surface degradation of a microlithographically fabricated array of 10 mm diameter iridium ultramicroelectrodes (UME) was investigated using atomic force microscopy (AFM), Auger scanning electron microscopy (SEM), and stripping voltammetry. Micrometer-size accumulations could be observed on the iridium surface after mercury was electrochemically deposited and stripped approximately five times in a perchloric acid media with a Ag AgCl 3M NaCl reference electrode. AFM images of the accumulations revealed that they were pyramidal in shape and had a tendency to form in clusters. Elemental analysis of the clusters with Auger SEM identified them as mercury and a small amount of chloride. The accumulations were determined to be mercurous chloride (Hg2Cl2) with the chloride contamination resulting both from leakage of the reference electrode and the decay of the perchloric acid. During subsequent depositions of mercury, chloride ions were eliminated by using a nitric acid media and a polyurethane solid state reference electrode. With chloride eliminated, mercury could be electrodeposited and stripped at least ten times on the iridium UME array without any visible surface degradation. © 1998 Elsevier Science S.A. All rights reserved.

Poisoning of dairy heifers by mercurous chloride

Mercury poisoning was diagnosed in four dairy heifers, three of which died. The clinical signs were variable and included salivation, excessive thirst, extreme depression and severe diarrhoea.

Poisoning of dairy heifers by mercurous chloride

Mercury poisoning was diagnosed in four dairy heifers, three of which died. The clinical signs were variable and included salivation, excessive thirst, extreme depression and severe diarrhoea. Postmortem examinations revealed...

Thermal convection in physical vapour transport of mercurous chloride for rectangular enclosures

The convective flow structures in the physical vapour transport process for mercurous chloride are investigated for two-dimensional rectangular enclosures at various aspect ratios (width-to-transport length) and two different wall boundary conditions: conducting and insulating. For a low aspect ratio of 0.124, the core of the flow is dominated by a unicellular convective structure at a Rayleigh number for conducting walls. For increasing Rayleigh number, the flow field bifurcates to asymmetric multicells. In contrast to conducting wall boundary conditions, the insulating wall boundary conditions tend to suppress the formation of secondary cells. As the aspect ratio decreases, the Rayleigh number at which transient convective flow arises decreases.

Physical vapor transport of mercurous chloride crystals: design of a microgravity experiment

Flow field characteristics predicted from a computational model show that the dynamical state of the flow, for practical crystal growth conditions of mercurous chloride, can range from steady to unsteady. Evidence that the flow field can be strongly dominated by convection for ground-based conditions is provided by the prediction of asymmetric velocity profiles by the model which show reasonable agreement with laser Doppler velocimetry experiments in both magnitude and planform. Unsteady flow is shown to be correlated with a degradation of crystal quality as quantified by light scattering pattern measurements. A microgravity experiment is designed to show that an experiment performed with parameters which yield an unsteady flow becomes steady (diffusive-advective) in a microgravity environment of 10 −3 g 0 as predicted by the model, and hence yields crystals with optimal quality.

Mercury Poisoning Associated With Beauty Cream—Texas, New Mexico, and California, 1995-1996

The Texas Department of Health (TDH), New Mexico Department of Health (NMDH), and San Diego County Health Department (SDCHD) recently investigated three cases of mercury poisoning among persons who had used a beauty cream produced in Mexico. The investigations implicated the beauty cream as the source of the mercury. The cream, marketed as "Crema de Belleza--Manning," lists "calomel" (mercurous chloride) as an ingredient and was found to contain 6%-8% mercury by weight. This report summarizes the ongoing investigation of these and other possible cases.

On the origin of the photoluminescence of mercurous chloride

The well known orange emission ( γ max = 645 nm of Hg 2Cl 2 at room temperature is apparently caused by the cluster cation Hg 3 2+ which is formed by the disproportionation of trace amounts of (Hg 2Cl 2 → Hg + HgCl 2) and the subsequent addition of a mercury atom to Hg 2Cl 2. The green emission of Hg 2Cl 2 at 77 K is composed of two components which are attributed to Hg 3 2+ ( γ max = 505 nm) and Hg 3 4+ ( γ max = 735 nm). The latter cluster cation is assumed to be formed by the addition of HgCl 2 to Hg 2Cl 2.

Thermal convective effects on physical vapor transport growth of mercurous chloride (Hg2Cl2) crystals for axisymmetric 2D cylindrical enclosure

The effects of thermal convection are investigated for the physical vapor transport (PVT) crystal growth process of Hg2Cl2. These effects may lead to increased defect densities and reduced optical homogeneity of the resultant crystals. A two-dimensional axisymmetrical model has been developed and applied to simulate the fluid flow, temperature, and mass concentration distribution in closed ampoules during PVT crystal growth. The numerical parametric studies show that the growth rate increases with the one-quarter power of the Raleigh number, Ra0.25, for 0<or= Delta T<or=30 K (0<or=Ra<or=2.62*103), and with Ra1.5 in the temperature range of 30<or= Delta T<or=50 K (2.62*103<or=Ra<or=4.73*103). The effect of thermal convection is shown to be negligible for gravitational accelerations less than the order of 10-1g0, for low-aspect-ratio enclosures. The growth rate of Hg2Cl2 decreases exponentially with an increase in the partial pressure of an impurity B, as well as with a decrease in the ampoule aspect ratio AR (radius to transport length) for 0.05<or=AR<or=0.20.

Arylsulfatase from Streptomyces griseorubiginosus S980-14.

A new arylsulfatase designated Es-1, which desulfated etoposide 4'-sulfate and p-nitrophenyl sulfate, was isolated from Streptomyces griseorubiginosus S980-14 and purified to protein homogeneity by ammonium sulfate fractionation, ion exchange column chromatography, and chromatofocusing. The enzyme was active in monomeric form with an approximate molecular weight of 45,000, had a pI value of 4.95, and required calcium for full activity. At an optimum reaction pH of 8.5, iodoacetate, mercurous chloride, and EDTA severely inhibited the activity of Es-1 arylsulfatase.

Was Young's syndrome caused by exposure to mercury in childhood?

To determine whether the incidence of chronic sinusitis, bronchitis, or bronchiectasis in men with obstructive azoospermia (Young's syndrome) has fallen in men born after 1955 when calomel (mercurous chloride) was removed from teething powders and worm medication in the United Kingdom. A prospective study of aetiological factors in subfertile men with epididymal obstruction operated on between 1975 and 1993. Central London. 274 men with obstructive azoospermia undergoing epididymovasostomy; date of birth was recorded and illness in childhood, persistent nasal or respiratory symptoms, and previous urinary or genital infection were asked about. Site of epididymal block and association with possible aetiological factors, related to date of birth. 146 men had hold up in the head of the epididymis (capital blocks): 119 (82%) had Young's syndrome, and 11 gave a definite history of pink disease (mercury intoxication) in childhood. 128 had obstruction lower down towards the tail of the epididymis (caudal blocks): 64 (50%) had a history of genital or urinary infection, and only three had Young's syndrome; none had had pink disease. The incidence of Young's syndrome fell significantly from 114 (50%) of 227 men born up to 1955 to eight (17%) of 47 men born since then. The decline in incidence of Young's syndrome in those born after 1955 is similar to that observed with pink disease, suggesting that both conditions may have had a similar aetiology--mercury intoxication.

Performance of mercurous chloride acousto-optic devices

Abstract The suitability of mercurous chloride for commercial applications was examined by fabricating Bragg cells and acousto-optic tunable filters (AOTF). The acoustic attenuation measurements showed that for operation at a center frequency of 30 MHz, it should be possible to build a Bragg cell with over 8000 resolution elements. For a frequency of 50 MHz, 6000 resolution elements can be achieved with an aperture smaller than 10 cm which is a significant advancement in the state of the art, and is superior to that tellurium dioxide. The AOTF was tested by measuring the transmission at 3.39 μm. The peak response was observed at 18.9 MHz and the fwhm was about 0.58 MHz, corresponding to a 3% of center wavelength resolution, which were excellent agreement with the theory.

Flight experiment on physical vapor transport growth of mercurous halide crystals

Large single crystals of mercurous chloride were grown by the physical vapor transport (PVT) technique. The present study reports the effect of convection on the optical quality of crystals. Optical homogeneity was observed to be dependent on convection levels present during crystal growth. Ground based experiments showed that better quality crystals grow at a low Rayleigh number. A flight experiment on PVT growth of mercurous halide is recommended to produce superior crystals, since numerical studies have shown that for a gravity level of 10 −3 g or less the Stefan wind drives the flow and no recirculating flow cells are expected.

Effect of surfactants and fungicides on clubroot (Plasmodiophora brassicae) of brassicas

SummaryTwo formulations of the surfactant sodium dioctyl sulphosuccinate (Aerosol OT, Monawet MO70), one of alkyl phenyl ethylene oxide (Agral) and three fungicides (PP192, dichlorophen and a thiabendazole/iodophor complex ‐Byatran) were tested in field trials for control of clubroot (Plasmodiophora brassicae) on cabbage in 1988 and 1989. A standard mercurous chloride treatment (pre‐sowing compost incorporation) was included in all experiments. Plants were raised in 64 cm3 blocks (1988) or 15 cm3 free‐fill cells (1989). Mercurous chloride reduced disease severity and increased yield in both years. Byatran was ineffective. The surfactants and dichlorophen, applied as pre‐planting soaks to the plant‐raising compost, restricted disease development and increased yield in 1988 but not in 1989. A similar treatment with PP192 restricted disease severity and enhanced yield in both years. Pouring the surfactants and dichlorophen into the planting hole was more effective than using them to soak the compost. In 1989 pour treatments with Agral and a combined soak/pour treatment with dichlorophen reduced disease severity and increased yields by 250% and 97% respectively; compost treatment with PP192 gave a 150% increase.

The optical quality of mercurous halide crystals

The improvement in the optical quality of mercurous halide crystals is described. Optical quality was evaluated by studying optical distortion, birefringence interferograms, and laser scattering characteristics; the parameters which are crucial for practical devices. Mercurous chloride and mercurous bromide crystals showed acoustic attenuation constants of 8 and 11.8 dB μ s −1 GHz −2 for cm size crystals. The acoustic attenuation of mercurous iodide was very large and varied significantly because of inhomo-geneities in the matrices of cm size crystals.

On the growth of Hg2Cl(1–x)2Brx2 single crystals

Single crystals of mixed mercurous halides Hg2X2 (where X = Cl and Br) were grown by the physical vapor transport process. Structural parameters and optical properties were determined to examine the suitability of mixed crystals for acousto-optic devices. Mixed crystals grown in the low concentration region did not show striations or banding. Crystals grown in the high concentration region showed considerable inhomogeneity in the refractive index. Since we had used identical thermal conditions, inhomogeneity was attributed to the solutal convection caused by the difference in densities of mercurous chloride and bromide vapors. A low concentration of dopant did not change the acoustic velocity of the parent components.

Thermodynamic reactivity, growth and characterization of mercurous halide crystals

Thermodynamic calculations were carried out for the Hg-X-O system (X = Cl, Br, I) to identify the potential sources of contamination and relative stability of oxides and oxy-halide phases. The effect of excess mercury vapor pressure on the optical quality of mercurous halide crystal was studied by growing several mercurous chloride crystals from mercury-rich composition. The optical quality of crystals was examined by birefringence interferometry and laser scattering studies. Crystals grown in slightly mercury-rich composition showed improved optical quality relative to stoichiometric crystals.

Fractal-like kinetics in solid—gas reactions

On re-examination, the kinetics of the solid—solid reaction between mercurous chloride and iodine is found to be of the fractal type. Microscopic studies of the reaction interface indicates that it may be random fractal of the percolation cluster type.

A study on the mechanical and optical properties of mercurous chloride single crystals

The Vickers hardness on (110) plane of mercurous chloride has been measured. Mercurous chloride crystals have been fabricated in the form of prisms and the refractive indices of ordinary and extraordinary rays were calculated over a wavelength range of 430 to 720 nm. The optical transmittance of 3.3 mm thick polished mercurous chloride samples was recorded using UV-visible and IR spectrophotometers. The absorption bands in the far IR region were explained in comparison with the literature.

Anisotropic thermal conductivity in mercurous chloride crystals.

Thermal-conductivity measurements were made on 10 samples of mercurous chloride prepared with their long (heat-flow) axes in each of three principal crystallographic orientations. The measurements revealed both differences in conductivity between different sample orientations, and differences due to thermal-cycling history. With use of three adjustable parameters, the data were fitted to a phenomenological model based on the standard Callaway and Holland models, with modifications suggested by Slack and by McCurdy et al., to explicitly take account of sound velocity anisotropies. The model is generally successful and shows the role of both anisotropic phonon velocities and anisotropic phonon scattering, in anisotropic thermal conductivity.

Growth and characterization of mercurous chloride single crystals

Mercurous chloride was purified by repeated sublimation using multichamber distillation column. Single crystals were grown by Physical Vapour Transport technique. During the process of purification of the material, very interesting habit modifications like dendrites and needles were observed. Vickers hardness tests were carried out on the (110) plane of the crystal for different orientations of the indentor. The shape of the impressions for different orientations of the indentor reveals the non-cubic structure of the plane. No structural phase transition in mercurous chloride was observed in calorimetry and optical studies.