Halogens Chlorine Research Articles

Nontuberculous Mycobacteria in Aerosol Droplets and Bulk Water Samples from Therapy Pools and Hot Tubs

Hot tub exposure has been causally associated with a steroid-responsive, granulomatous lung disease featuring nontuberculous mycobacterial (NTM) growth in both clinical and environmental samples. Little is known regarding prevalence of and risk factors for NTM-contamination and associated illness in these settings. In this study, the frequency of NTM growth and aerosolization in 18 public hot tubs and warm water therapy pools and the factors associated with mycobacterial growth were analyzed. Each site was characterized by water chemistry analysis; a questionnaire on maintenance, disinfection, and water quality; and air and water sampling for quantitative NTM culture. NTM were detected in air or water from 13/18 (72%) sites; a strong correlation was found between the maximum air and water NTM concentrations (rho 0.49, p = 0.04). Use of halogen (chlorine or bromine) disinfection was associated with significantly lower air and water concentrations of NTM compared with disinfection using ultraviolet light and hydrogen peroxide (p = 0.01–0.04). Higher water turnover rates were also associated with lower air and water NTM concentrations (p = 0.02–0.03). These findings suggest that NTM are frequently detectable in the air and water of spas and therapy pools and that particular maintenance and disinfection approaches affect NTM bioaerosol concentrations in these settings.

Insect mandibles—comparative mechanical properties and links with metal incorporation

A number of arthropod taxa contain metals in their mandibles (jaws), such as zinc, manganese, iron, and calcium. The occurrence of zinc and its co-located halogen chlorine have been studied in relation to the mechanical properties and shown to be linked in a direct fashion with increasing concentration. Hardness along with elastic modulus (stiffness) has also been linked to zinc and halogen concentration in some marine polychaete worms. The metal appears to be incorporated within the biological matrix, possibly bonding with proteins. However, the comparative advantage of metal inclusion has not been tested. It is possible that without metals, alternative mechanisms are used to achieve hardness of equal value in similar 'tools' such as mandibles. This question has direct bearing on the significance of metal hardening. In the present article, we compare across mandibles from six termite species, including samples with major zinc concentration, minor manganese, and no metals. Nanoindentation, electron microscopy, and electron microanalysis are used to assess metal concentration, form, and mechanical properties. The data demonstrate that termite mandibles lacking metals when fully developed have lower values for hardness and elastic modulus. Zinc is linked to a relative 20% increase in hardness when compared with mandibles devoid of metals. The similar transition metal, manganese, found in minor concentrations, is not linked to any significant increase in these mechanical properties. This raises the question of the function of manganese, which is as commonly found in insect mandibles as zinc and often located in the same mandibles.

Electrochemical functionalization of multi-walled carbon nanotubes for solvation and purification

Abstract The chemical modification of multi-walled carbon nanotubes using electrolysis is described. It is found that the evolution of the halogens chlorine or bromine on an anode made from a foil of carbon nanotubes couples halogen atoms to the nanotube lattice. Furthermore, oxygen bearing functional groups, such as hydroxyl and carboxyl groups, are formed at the same time aiding solvation of the nanotubes in water or alcohol without any surfactant. Impurities and low grade modified nanotubes remain insoluble. The halogenated carbon nanotubes can be converted with sodium amide or triphenylmethyllithium to add the corresponding functional groups.

Up with Bromine

ATMOSPHERIC SCIENCE Major volcanic eruptions eject particles and gases into the stratosphere, including the halogens chlorine (Cl) and bromine (Br), both of which contribute to the catalytic destruction of ozone, but the magnitude of the volcanic contribution of these gases is uncertain. Although enlarged polar ozone holes were observed after the Pinatubo eruption in 1991, these were attributed primarily to the effects of sulfate aerosols and other particles from the eruption on the formation of polar stratospheric clouds. Most of the volcanic Cl (which forms HCl) is likely scavenged before it reaches the stratosphere, but the potential effects of Br, which is much more potent at destroying ozone than Cl, are not well studied. Bureau et al . now present a series of experiments which suggest that the Pinatubo eruption and other comparable eruptions could inject as much Br into the atmosphere as the annual budget from all other natural and anthropogenic sources. Their results show that in magmas, Cl, Br, and I partition strongly into a hydrous fluid phase, which is responsible for driving violent eruptions. Bromine seems less likely to be washed out in the eruption column than Cl, although further study of this is needed. — BH Earth Planet. Sci. Lett . 183 , 51 (2000).

Preparative procedure of dihalosulfenylation: Thiobisamines addition to unsaturated compounds in the presence of phosphorus oxyhalides and halides

A new synthetic method was developed for \,\′-dihaloalkyl sulfides (halogen chlorine or bromine) by reaction of thiobisamines with olefins and alkynes in the presence of the appropriate phosphorus halides. The reaction proceeds along electrophilic mechanism affordingtrans-addition products. The highest yields of the target products were obtained at POBr3 or POC13 application.

Structures and vapor-sorption characteristics of sputtered polychlorotrifluoroethylene films treated by hydrogen-plasma

Hydrogen-plasma treatment of the polychlorotrifluoroethylene (PCTFE) film produced by radio-frequency sputtering induces considerable elimination of halogen (fluorine and chlorine) atoms. This dehalogenation produces some noteworthy structural features: surface densification (crosslinks), trapped radicals, and incorporation of oxygen in the carbon networks. These structural changes modify the vapor-sorption properties of the sputtered PCTFE film, producing a molecular-sieving effect and enhancing the polar character of solubility properties of organic vapors.

Stress birefringence and microinclusions in sublimation-grown bulk CdTe

High quality CdTe bulk crystals are difficult to obtain due to various types of defects such as twins, dislocations, inclusions, and sub-grain boundaries. In this paper, the influence of different dopants and growth conditions on formation, frequency, and stereometry of those defects are discussed. The crystals have been grown by means of a sublimation travelling heater method (STHM) using Bridgman seeds. As dopants, the halogens chlorine, bromine, and iodine as well as vanadium and titanium have been used. By means of quantitative near-IR polarizing microscopy, the mapping of long-range stress fields can be related to irregularities in crystal growth. Additionally, local stress birefringence induced by dislocations and inclusions has been observed. The occurrence of crystal perturbations in STHM and Bridgman material is compared.

Electronic structure and models of receptor of monooxygenase inductors from a number of polychlorinated polycyclic compounds. 3. Mndo calculations of chlorine and fluorine derivatives of dibenzo-p-dioxins

MNDO calculations for dibenzo-para-dioxin (DD) and its chlorine- and fluorine-substituted derivatives have shown that the geometric structure of the molecules and the Π-donor properties are very little dependent on the type of halogen (chlorine or fluorine) or on the position of the halogen in the molecule. The chlorine and fluorine derivatives of the DD do exhibit substantial differences in the charges on the C atoms directly connected to the halogens. The higher atomic charges on the C atoms connected to F atoms suggests that the fluorine-containing DDs will be capable of metabolism to mercapturic acids.

Control of the freshwater fouling bivalveCorbicula fluminea by halogenation

Mortality levels for adult and juvenile Asiatic clam,Corbicula fluminea, were determined after exposure to halogens (chlorine, bromine) in 28 to 32-day laboratory and field (industrial water supply) tests. Low levels of mortality ( 53%) when test specimens were exposed to comparable TRC levels (0.2 to 1.0 mg/L) at temperatures in excess of 18‡C. Mortalities generated among adults by an initial 14-day low dose (0.25 mg/L TRC) followed by an 18-day high dose (0.50 to 1.00 mg/L TRC; >80% mortality) were comparable to those from a constant high dose (0.50 to 1.00 mg/L; 60 to 95% mortality). Adults and juveniles were comparably sensitive to halogen concentrations adequate for control. There is no substantial difference in the effectiveness of either chlorine or bromine in controlling adult and juvenile stages ofC. fluminea. Field studies conducted in the spring and fall produced markedly dissimilar results. Mortality levels during the spring field study exceeded 90% after 28 days of exposure to 0.25 mg/L TRC, while ambient temperatures rose from 20 to 25‡C. Mortality levels not exceeding 23% were observed among test organisms after 28 days of exposure to elevated TRC levels (<0.50 mg/L), while ambient temperatures were declining from 20 to 12‡C during October and November 1985.

Electron and ion emission from zirconium, yttrium and scandium during chlorine and bromine adsorption

Abstract Previous work on exoelectron and ion emission during chemisorption under UHV conditions has been extended to include halogen (chlorine, bromine) adsorption on group IIIA (Y, Sc) and group IA (Zr) surfaces, both clean and with Na predosing. Ionic species observed include Na + Cl − and NaCl − 2 . By means of double dosing experiments, it is shown conclusively that the latter dichloride ion is formed by direct titration of Na by Cl − 2 , and that halogen dissociation is not a precursor step.

Anion ordering in europium(ii) mixed halide systems: Preparation of mixed cation fluoride halides

The results of phase studies of EuX 2-EuX' 2 systems, where X and X' represent the halogens chlorine, bromine and iodine, are presented and compared with previous studies of related divalent systems. All systems exhibit the PbCl 2-type structure over a limited intermediate composition range. In every reported study but one the anions in the PbCl 2-type structure region are found to be ordered, with the smaller anion occupying the tetrahedral hole. The complexity of the systems is found to correlate well with the effective size difference between the anions and the cation. Lattice parameter data for three mixed cation PbFCl-type fluoride halides are presented.

Reactions of metal-metal multiple bonds. 7. Addition of the halogens chlorine, bromine and iodine and diisopropyl peroxide to hexaisopropoxydimolybdenum (M.tplbond.M). Dinuclear oxidative-addition reactions accompanied by metal-metal bond-order changes from 3 to 2 to 1

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTReactions of metal-metal multiple bonds. 7. Addition of the halogens chlorine, bromine and iodine and diisopropyl peroxide to hexaisopropoxydimolybdenum (M.tplbond.M). Dinuclear oxidative-addition reactions accompanied by metal-metal bond-order changes from 3 to 2 to 1Malcolm H. Chisholm, Charles C. Kirkpatrick, and John C. HuffmanCite this: Inorg. Chem. 1981, 20, 3, 871–876Publication Date (Print):March 1, 1981Publication History Published online1 May 2002Published inissue 1 March 1981https://doi.org/10.1021/ic50217a046RIGHTS & PERMISSIONSArticle Views195Altmetric-Citations34LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (788 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Chlorine, bromine and iodine in monsoon rains in India

The mean concentrations of the halogens chlorine, bromine and iodine in a large number of rainwater samples collected in India during the south-west moonsoon at the west coast and at two sites on the hill range near the west coast are presented and discussed. The concentration and ratios of these halogens in the rain-water samples compare very well with those previously observed in marine precipitations. There is no change in the Cl/Na ratios with collection altitude. Br shows a slight enrichment relative to N a at most of the sampling locations and a nominal depletion at one of the sites on the hills. Iodine enrichment is high at all sampling sites and the samples from the higher altitude station on the hills show the maximum enrichment. The study confirms that large deposition of sea-salt occurs along the west coast of India due to the monsoonal flow. DOI: 10.1111/j.2153-3490.1979.tb00907.x

Tropospheric Halogen Gases: Inorganic and Organic Components

Inorganic and organic components of the gaseous tropospheric halogens chlorine, bromine, and iodine have been simultaneously measured. At four diverse remote locations the organic component contained the bulk of the halogen mass, varied less than the inorganic component, and was comparable in concentration to the independently measured halocarbon component.

HALOGENATION IN THE RHODOPHYTA1,2 A REVIEW

SUMMARYThe halogens—chlorine, bromine and iodine—play an important, role in the biochemical processes of marine red algae. Recent studies show that various species from at least 5 orders of the Rhodophyta possess the unique ability to synthesize organic halogen‐containing compounds which are derived from seawater components. A variety of substances have been reported, with various structures from simple aliphatic halo‐ketones and brominated phenols to more sophisticated mono‐, sesqui‐ and diterpenes. While the biological functions of these compounds are not clearly understood, they appear to provide environmental advantage, probably involving predator avoidance responses and microflora antibiosis.

Recent Advances in Halogenation of Organic Compounds

This article deals with some generalizations that may be reached concerning the preparative halogenation of organic compounds via free-radical chain mechanisms. The halogenating agents discussed are: 1. elemental halogen (chlorine and bromine), 2. certain organic and inorganic halogen compounds which exhibit a special selectivity or which are particularly useful as synthetic tools because of their ease of handling.

SOME OBSERVATIONS ON THE RADIATIVE COMBINATION OF ATOMIC HYDROGEN WITH ATOMIC HALOGENS IN BURNER FLAMES

When small quantities of gaseous molecular halogens chlorine, bromine, and iodine are introduced into the supply to premixed hydrogen–oxygen–nitrogen flames one of the most important spectroscopic features appearing is an apparently continuous emission in the visible, sometimes extending into the near ultraviolet. The intensity of this continuous emission has been studied as a function of amount of halogen, and of temperature, composition, and position with respect to the reaction zone in a wide variety of flames. In oxygen-rich flames it has been attributed to an over-all process,[Formula: see text]where X denotes an atom of halogen; one of the atoms may be in an excited state. Most of the work concerns hydrogen-rich flames, where a very strong correlation between the intensity and the product [H][X] is obtained. The over-all process may be written as[Formula: see text]The efficiency of this over-all process is measured as 1 quantum emitted for about 1010 ordinary kinetic collisions of the atoms. The mechanism is discussed from the aspects of direct radiative recombination and of stabilization by collision of an intermediate excited HX* before radiation.

Germicidal Effectiveness of Chlorine, Bromine and Iodine

In this project, the facts desired concern the comparative effectiveness of the three halogens chlorine, bromine and iodine as germicides in water. Included in the series also has been a mixture of bromine, 90 parts, plus chlorine, 10 parts. The chlorine used in these experiments was derived from sodium hypochlorite manufactured by the Great Western Electro-Chemical Company of Pittsburg, California, while the bromine and the bromine plus chlorine mixture were the products of the California Chemical Corporation of Newark, in the same state. The iodine utilized was Baker's Analyzed in quality. The bacterial flora of water are derived in very large part from soil and therefore soil suspensions made by shaking garden soil in tap water were passed through cotton in a funnel to remove gross particles. The soil suspension was prepared by adding ten grams of soil to one litre of the water. For the test suspensions used in these experiments, 200 cc. of this turbid water were added to 800 cc. of tap water. All suspensions were prepared fresh at time of use. The first portion of the problem has dealt with reduction of the numbers of bacteria derived from soil when suspended in water. Under conditions of general usage of the halogens, chlorine or iodine, the end desired in practice is control of contamination in water. No discussion of the effectiveness of chlorine will be added here for many volumes of work dealing with it have been contributed in the aggregate. Its value is too well recognized to require comment. In these trials chlorine serves rather as a well recognized standard for purposes of comparison. Iodine has its use in military and camp sanitation, but regarding bromine little knowledge has been accumulated.