Plasma-assisted quartz-to-quartz direct bonding for the fabrication of a multilayered quartz template for nanoimprint lithography

International Nuclear Information System (INIS)

Lee, Jihye; Ali, Altun; Kim, Ki-don; Choi, Dae-guen; Choi, Jun-Hyuk; Jeong, Jun-ho; Kim, Jae-Hyun

2010-01-01

In this paper, a low-temperature plasma-assisted process is developed to realize a uniform, ultraviolet (UV) transparent and chemically inert quartz-to-quartz direct bonding. Two sets of pretests are performed in order to understand how the bond surface energy changes with the plasma exposure time and the wet etching of quartz, respectively. The developed technique is used to fabricate a multilayered quartz template for UV nanoimprint lithography (UV-NIL). The multilayered quartz template is fabricated by bonding a square piece of a standard quartz wafer, which is about 625 µm in thickness, to a wet-etched 6.35 mm thick quartz photomask plate. A fabricated multilayered template is loaded to the commercial UV-NIL tool Imprio(TM) 100, and NIL was performed successfully. The developed direct bonding technique makes it possible for standard quartz wafers, which are compatible with high-resolution semiconductor fabrication processes, to be utilized as the templates in commercial UV-NIL machines with enhanced mechanical stability.

Halogenation processes of secondary organic aerosol and implications on halogen release mechanisms

Directory of Open Access Journals (Sweden)

J. Ofner

2012-07-01

Full Text Available Reactive halogen species (RHS, such as X·, X₂ and HOX containing X = chlorine and/or bromine, are released by various sources like photo-activated sea-salt aerosol or from salt pans, and salt lakes. Despite many studies of RHS reactions, the potential of RHS reacting with secondary organic aerosol (SOA and organic aerosol derived from biomass-burning (BBOA has been neglected. Such reactions can constitute sources of gaseous organohalogen compounds or halogenated organic matter in the tropospheric boundary layer and can influence physicochemical properties of atmospheric aerosols.

Model SOA from α-pinene, catechol, and guaiacol was used to study heterogeneous interactions with RHS. Particles were exposed to molecular chlorine and bromine in an aerosol smog-chamber in the presence of UV/VIS irradiation and to RHS, released from simulated natural halogen sources like salt pans. Subsequently, the aerosol was characterized in detail using a variety of physicochemical and spectroscopic methods. Fundamental features were correlated with heterogeneous halogenation, which results in new functional groups (FTIR spectroscopy, changes UV/VIS absorption, chemical composition (ultrahigh resolution mass spectroscopy (ICR-FT/MS, or aerosol size distribution. However, the halogen release mechanisms were also found to be affected by the presence of organic aerosol. Those interaction processes, changing chemical and physical properties of the aerosol are likely to influence e.g. the ability of the aerosol to act as cloud condensation nuclei, its potential to adsorb other gases with low-volatility, or its contribution to radiative forcing and ultimately the Earth's radiation balance.

Organic halogens in landfill leachates

DEFF Research Database (Denmark)

Grøn, C.; Christensen, J. B.; Jensen, Dorthe Lærke

2000-01-01

Using a group parameter, total organic halogens (TOX), high TOX concentrations were found in leachates and leachate contaminated groundwaters at two Danish mixed sanitary and hazardous waste sites. With commonly used screening procedures for organic contaminants, the individual halogenated organi...

Biogeochemistry of Halogenated Hydrocarbons

Science.gov (United States)

Adriaens, P.; Gruden, C.; McCormick, M. L.

2003-12-01

Halogenated hydrocarbons originate from both natural and industrial sources. Whereas direct anthropogenic emissions to the atmosphere and biosphere are often easy to assess, particularly when they are tied to major industrial activities, the attribution of emissions to other human activities (e.g., biomass burning), diffuse sources (e.g., atmospheric discharge, run off), and natural production (e.g., soils, fungi, algae, microorganisms) are difficult to quantify. The widespread occurrence of both alkyl and aryl halides in groundwater, surface water, soils, and various trophic food chains, even those not affected by known point sources, suggests a substantial biogeochemical cycling of these compounds (Wania and Mackay, 1996; Adriaens et al., 1999; Gruden et al., 2003). The transport and reactive fate mechanisms controlling their reactivity are compounded by the differences in sources of alkyl-, aryl-, and complex organic halides, and the largely unknown impact of biogenic processes, such as enzymatically mediated halogenation of organic matter, fungal production of halogenated hydrocarbons, and microbial or abiotic transformation reactions (e.g., Asplund and Grimvall, 1991; Gribble, 1996; Watling and Harper, 1998; Oberg, 2002). The largest source may be the natural halogenation processes in the terrestrial environment, as the quantities detected often exceed the amount that can be explained by human activities in the surrounding areas ( Oberg, 1998). Since biogeochemical processes result in the distribution of a wide range of halogenated hydrocarbon profiles, altered chemical structures, and isomer distributions in natural systems, source apportionment (or environmental forensics) can often only be resolved using multivariate statistical methods (e.g., Goovaerts, 1998; Barabas et al., 2003; Murphy and Morrison, 2002).This chapter will describe the widespread occurrence of halogenated hydrocarbons, interpret their distribution and biogeochemical cycling in light of

Studies on halogen quenching through the Stern-Volmer plot

International Nuclear Information System (INIS)

Takiue, Makoto; Ishikawa, Hiroaki.

1978-01-01

The quenching effect for halogenated benzenes, methanes and ethanes have been investigated. The halogen quenching was accurately measured using the internal conversion electrons emitted from 113 Sn-sup(113m)In. From the quenching constants determined by the Stern-Volmer plots with respect to various halogen quenchers, the following results have been obtained. (1) The quenching constants increase with the number of halogen substituents, so as linearly in halogenated benzenes and exponentially in halogenated methanes and ethanes. Even the isomers of halogenides have different quenching constants. (2) There is a linearity between logarithm of the quenching constant and a polarographic half-wave reduction potential. (3) Electron excitation provides larger quenching constants than UV excitation for halogenated methanes. Based on these results, the mechanism of halogen quenching have been discussed in connection with the exciplex formation. (auth.)

Independent Evolution of Six Families of Halogenating Enzymes.

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Xu, Gangming; Wang, Bin-Gui

2016-01-01

Halogenated natural products are widespread in the environment, and the halogen atoms are typically vital to their bioactivities. Thus far, six families of halogenating enzymes have been identified: cofactor-free haloperoxidases (HPO), vanadium-dependent haloperoxidases (V-HPO), heme iron-dependent haloperoxidases (HI-HPO), non-heme iron-dependent halogenases (NI-HG), flavin-dependent halogenases (F-HG), and S-adenosyl-L-methionine (SAM)-dependent halogenases (S-HG). However, these halogenating enzymes with similar biological functions but distinct structures might have evolved independently. Phylogenetic and structural analyses suggest that the HPO, V-HPO, HI-HPO, NI-HG, F-HG, and S-HG enzyme families may have evolutionary relationships to the α/β hydrolases, acid phosphatases, peroxidases, chemotaxis phosphatases, oxidoreductases, and SAM hydroxide adenosyltransferases, respectively. These halogenating enzymes have established sequence homology, structural conservation, and mechanistic features within each family. Understanding the distinct evolutionary history of these halogenating enzymes will provide further insights into the study of their catalytic mechanisms and halogenation specificity.

Role of Substrate on Quartz Cementation in Quartz Aggregates

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Farver, J. R.; Winslow, D.; Onasch, C.

2010-12-01

Quartz cementation in quartz aggregates has been experimentally investigated. The starting material was disaggregated detrital quartz grains from the well-sorted, mature St. Peter Sandstone. The ‘as-is’ grains have patches of iron oxide coatings and some have euhedral overgrowths that contain iron oxide dust rims. In addition a set of experiments was run using grains that were cleaned by soaking in sodium hydrosulfite and sodium bisulfate solutions to remove exposed iron oxide coatings. Experimental charges consisted of amorphous silica powder (≈30 mg) to provide a source of silica for the quartz cement, AlCl3 powder (≈3 mg) to provide a tracer for Cathodoluminescence (CL) identification of cement formed during the experiment, 25 wt% NaCl brine solution (≈25 mg) to increase the silica solubility and to better mimic oil field brines, and the natural quartz grains (100-130 mg). The charges were weld-sealed in Au capsules and run in cold-seal pressure vessels at 250°C to 450°C at 150 MPa confining pressure for up to 8 weeks. After the experiments, the samples were vacuum impregnated with a low viscosity epoxy containing a blue dye. After curing, the sample charge was sawn in half along its long axis and one half was polished (to 1 micron diamond paste) for analysis. The nature and amount of quartz cement in the samples were determined by a combination of CL, light microscopy, and scanning electron microscopy. Photomosaics of the samples were created and the amount of cement, porosity, and average grain sizes were determined by point-counting. The cement formed during the experiment was easily recognized from the quartz grains (and previous overgrowths) by the difference in luminescence. The results indicate the amorphous silica powder provides a ready source for silica for quartz cementation due to its greater solubility than the quartz. The cementation rates are rapid (>14% cement formed in 2 weeks at 450°C and >7% in 8 weeks at 250°C). Compared to

METHOD FOR PRODUCING ISOTOPIC METHANES AND PARTIALLY HALOGENATED DERIVATIVES THEROF

Science.gov (United States)

Frazer, J.W.

1959-08-18

A method is given for producing isotopic methanes and/ or partially halogenated derivatives. Lithium hydride, deuteride, or tritide is reacted with a halogenated methane or with a halogenated methane in combination with free halogen. The process is conveniently carried out by passing a halogenated methane preferably at low pressures or in an admixture with an inert gas through a fixed bed of finely divided lithium hydride heated initially to temperatures of 100 to 200 deg C depending upon the halogenated methane used.

Organic halogens in spruce forest throughfall

DEFF Research Database (Denmark)

Öberg, G.; Johansen, C.; Grøn, C.

1998-01-01

. No relationship between the position of the collectors and the forest edge or dominating wind-direction was found, suggesting that dry deposition was not a major source. The concentration of organic halogens was related to that of organic carbon and decreased from the tree-trunk and outwards. In addition......, the concentrations were higher during the growing season than during the dormant season. This indicates that the major part of the organic carbon and organic halogens in spruce forest throughfall originates from canopy leachates or other internal sources. (C) 1998 Elsevier Science Ltd.......Deposition of dissolved organic halogens by throughfall was determined in a small spruce forest site in Denmark (56 degrees 28'N, 8 degrees 24'E). The mean annual deposition of dissolved organic halogens was 377 g ha(-1)yr(-1), and larger than the general deposition by precipitation...

New Type of Halogen Bond: Multivalent Halogen Interacting with π- and σ-Electrons

Directory of Open Access Journals (Sweden)

Sławomir J. Grabowski

2017-12-01

Full Text Available MP2/aug-cc-pVTZ calculations were performed for complexes of BrF3 and BrF5 acting as Lewis acids through the bromine centre, with species playing a role of Lewis base: dihydrogen, acetylene, ethylene, and benzene. The molecular hydrogen donates electrons by its σ-bond, while in remaining moieties—in complexes of hydrocarbons; such an electron transfer follows from π-electrons. The complexes are linked by a kind of the halogen bond that is analyzed for the first time in this study, i.e., it is the link between the multivalent halogen and π or σ-electrons. The nature of such a halogen bond is discussed, as well as various dependencies and correlations are presented. Different approaches are applied here, the Quantum Theory of Atoms in Molecules, Natural Bond Orbital method, the decomposition of the energy of interaction, the analysis of electrostatic potentials, etc.

Experimental and computational evidence of halogen bonds involving astatine

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Guo, Ning; Maurice, Rémi; Teze, David; Graton, Jérôme; Champion, Julie; Montavon, Gilles; Galland, Nicolas

2018-03-01

The importance of halogen bonds—highly directional interactions between an electron-deficient σ-hole moiety in a halogenated compound and an acceptor such as a Lewis base—is being increasingly recognized in a wide variety of fields from biomedicinal chemistry to materials science. The heaviest halogens are known to form stronger halogen bonds, implying that if this trend continues down the periodic table, astatine should exhibit the highest halogen-bond donating ability. This may be mitigated, however, by the relativistic effects undergone by heavy elements, as illustrated by the metallic character of astatine. Here, the occurrence of halogen-bonding interactions involving astatine is experimentally evidenced. The complexation constants of astatine monoiodide with a series of organic ligands in cyclohexane solution were derived from distribution coefficient measurements and supported by relativistic quantum mechanical calculations. Taken together, the results show that astatine indeed behaves as a halogen-bond donor—a stronger one than iodine—owing to its much more electrophilic σ-hole.

Transition from metal-ligand bonding to halogen bonding involving a metal as halogen acceptor a study of Cu, Ag, Au, Pt, and Hg complexes

Science.gov (United States)

Oliveira, Vytor; Cremer, Dieter

2017-08-01

Utilizing all-electron Dirac-exact relativistic calculations with the Normalized Elimination of the Small Component (NESC) method and the local vibrational mode approach, the transition from metal-halide to metal halogen bonding is determined for Au-complexes interacting with halogen-donors. The local stretching force constants of the metal-halogen interactions reveal a smooth transition from weak non-covalent halogen bonding to non-classical 3-center-4-electron bonding and finally covalent metal-halide bonding. The strongest halogen bonds are found for dialkylaurates interacting with Cl2 or FCl. Differing trends in the intrinsic halogen-metal bond strength, the binding energy, and the electrostatic potential are explained.

Cellular effects of halogen blue light from dental curing unit

International Nuclear Information System (INIS)

Trosic, I.; Pavicic, I.; Jukic, S.

2008-01-01

Full text: Halogen curing lights are the most frequently used polymerization source in dental offices. Light-cured bonding systems have become increasingly popular among clinicians because they offer a number of advantages over self-cured adhesives. The effort to increase polymerization quality releases the commercially available high power light density dental curing units. Emitted visible blue light belongs to the range of nonionizing radiation. Common concern in both, patients and dentist grows with regard to the unfavorable effects on the pulp tissue. The aim of study was to evaluate the time and dose dependence effect of halogen light curing unit (Elipar TriLight, ESPE Dental AG, Germany) at the disposed condition modes in vitro. A quartz-tungsten-halogen light source emits radiation of the wavelengths between 400 and 515 nm. This halogen blue light source operates in the three illumination modes, medium (M), exponential (E) and standard (S), and five illumination times. The total irradiance or the light intensity was measured by the light intensity control area on the control panel of device and mean light intensity given by manufacturer was 800 m W/cm 2 . Continuous culture of V79 cells was illuminated in triplicate. The influence of medium mode (M), exponential (E) and standard (S) illumination during 20, 40 and 80 sec on the cell viability, colony forming ability and proliferation of V79 cell culture was investigated. Trypan blue exclusion test was used to determine cell viability, both, in the treated and control cell samples. Colony forming ability was assessed for each exposure time and mode by colony count on post-exposure day 7. Cell proliferation was determined by cell counts for each time and mode of exposure during five post-exposure days. Statistical difference were determined at p<0.05 (Statistica 7.0, StatSoft Inc., USA). Viability of cells was not affected by blue light in view of exposure time and modes. Regardless to exposure or illumination

Removal of Intermediate Aromatic Halogenated DBPs by Activated Carbon Adsorption: A New Approach to Controlling Halogenated DBPs in Chlorinated Drinking Water.

Science.gov (United States)

Jiang, Jingyi; Zhang, Xiangru; Zhu, Xiaohu; Li, Yu

2017-03-21

During chlorine disinfection of drinking water, chlorine may react with natural organic matter (NOM) and bromide ion in raw water to generate halogenated disinfection byproducts (DBPs). To mitigate adverse effects from DBP exposure, granular activated carbon (GAC) adsorption has been considered as one of the best available technologies for removing NOM (DBP precursor) in drinking water treatment. Recently, we have found that many aromatic halogenated DBPs form in chlorination, and they act as intermediate DBPs to decompose and form commonly known DBPs including trihalomethanes and haloacetic acids. In this work, we proposed a new approach to controlling drinking water halogenated DBPs by GAC adsorption of intermediate aromatic halogenated DBPs during chlorination, rather than by GAC adsorption of NOM prior to chlorination (i.e., traditional approach). Rapid small-scale column tests were used to simulate GAC adsorption in the new and traditional approaches. Significant reductions of aromatic halogenated DBPs were observed in the effluents with the new approach; the removals of total organic halogen, trihalomethanes, and haloacetic acids by the new approach always exceeded those by the traditional approach; and the effluents with the new approach were considerably less developmentally toxic than those with the traditional approach. Our findings indicate that the new approach is substantially more effective in controlling halogenated DBPs than the traditional approach.

The halogen bond: Nature and applications

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Costa, Paulo J.

2017-10-01

The halogen bond, corresponding to an attractive interaction between an electrophilic region in a halogen (X) and a nucleophile (B) yielding a R-X⋯B contact, found applications in many fields such as supramolecular chemistry, crystal engineering, medicinal chemistry, and chemical biology. Their large range of applications also led to an increased interest in their study using computational methods aiming not only at understanding the phenomena at a fundamental level, but also to help in the interpretation of results and guide the experimental work. Herein, a succinct overview of the recent theoretical and experimental developments is given starting by discussing the nature of the halogen bond and the latest theoretical insights on this topic. Then, the effects of the surrounding environment on halogen bonds are presented followed by a presentation of the available method benchmarks. Finally, recent experimental applications where the contribution of computational chemistry was fundamental are discussed, thus highlighting the synergy between the lab and modeling techniques.

Enzymatic Halogenation and Dehalogenation Reactions: Pervasive and Mechanistically Diverse.

Science.gov (United States)

Agarwal, Vinayak; Miles, Zachary D; Winter, Jaclyn M; Eustáquio, Alessandra S; El Gamal, Abrahim A; Moore, Bradley S

2017-04-26

Naturally produced halogenated compounds are ubiquitous across all domains of life where they perform a multitude of biological functions and adopt a diversity of chemical structures. Accordingly, a diverse collection of enzyme catalysts to install and remove halogens from organic scaffolds has evolved in nature. Accounting for the different chemical properties of the four halogen atoms (fluorine, chlorine, bromine, and iodine) and the diversity and chemical reactivity of their organic substrates, enzymes performing biosynthetic and degradative halogenation chemistry utilize numerous mechanistic strategies involving oxidation, reduction, and substitution. Biosynthetic halogenation reactions range from simple aromatic substitutions to stereoselective C-H functionalizations on remote carbon centers and can initiate the formation of simple to complex ring structures. Dehalogenating enzymes, on the other hand, are best known for removing halogen atoms from man-made organohalogens, yet also function naturally, albeit rarely, in metabolic pathways. This review details the scope and mechanism of nature's halogenation and dehalogenation enzymatic strategies, highlights gaps in our understanding, and posits where new advances in the field might arise in the near future.

Molecular activation analysis for organo-halogen contaminants in yogurt

International Nuclear Information System (INIS)

Zhang Hong; Chai Zhifang

2004-01-01

The concentrations of total halogen (TX), extractable organo-halogen (EOX), extractable persistent organo-halogen (EPOX), organo-chlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in 18 different yogurt specimens of 14 brands from Beijing, Tianjin, Shanghai, Guangzhou and Shijiazhuang were determined by epithermal neutron activation analysis (ENAA), molecular activation analysis (MAA) and GC-Mass Spectrometry (GC-MS), respectively. The results indicated that the halogen in yogurt mainly existed as inorganic species and non-extractable organo-halogen compounds. About 1/3 to 1/4 of EOX was EPOX. Further, EOCl and EPOCl were the main organo-halogen species in yogurt. The average concentration of the unknown organo-chlorine was 96% of the EPOCl. HCHs and DDTs were still the main contaminants of OCPs in the yogurt of interest. Also, PCB202, PCB103 and PCB208 were the main contaminants of PCBs. (authors)

FIELD SCREENING FOR HALOGENATED VOLATILE ORGANIC COMPOUNDS

Energy Technology Data Exchange (ETDEWEB)

John F. Schabron; Joseph F. Rovani Jr.; Theresa M. Bomstad

2002-06-01

Western Research Institute (WRI) initiated exploratory work towards the development of new field screening methodology and a test kit to measure halogenated volatile organic compounds (VOCs) in the field. Heated diode and corona discharge sensors are commonly used to detect leaks of refrigerants from air conditioners, freezers, and refrigerators. They are both selective to the presence of carbon-halogen bonds. Commercially available heated diode and corona discharge leak detectors were procured and evaluated for halogenated VOC response. The units were modified to provide a digital readout of signal related to VOC concentration. Sensor response was evaluated with carbon tetrachloride and tetrachloroethylene (perchloroethylene, PCE), which represent halogenated VOCs with and without double bonds. The response characteristics were determined for the VOCs directly in headspace in Tedlar bag containers. Quantitation limits in air were estimated. Potential interferences from volatile hydrocarbons, such as toluene and heptane, were evaluated. The effect of humidity was studied also. The performance of the new devices was evaluated in the laboratory by spiking soil samples and monitoring headspace for halogenated VOCs. A draft concept of the steps for a new analytical method was outlined. The results of the first year effort show that both devices show potential utility for future analytical method development work towards the goal of developing a portable test kit for screening halogenated VOCs in the field.

Halogens in chondritic meteorites and terrestrial accretion

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Clay, Patricia L.; Burgess, Ray; Busemann, Henner; Ruzié-Hamilton, Lorraine; Joachim, Bastian; Day, James M. D.; Ballentine, Christopher J.

2017-11-01

Volatile element delivery and retention played a fundamental part in Earth’s formation and subsequent chemical differentiation. The heavy halogens—chlorine (Cl), bromine (Br) and iodine (I)—are key tracers of accretionary processes owing to their high volatility and incompatibility, but have low abundances in most geological and planetary materials. However, noble gas proxy isotopes produced during neutron irradiation provide a high-sensitivity tool for the determination of heavy halogen abundances. Using such isotopes, here we show that Cl, Br and I abundances in carbonaceous, enstatite, Rumuruti and primitive ordinary chondrites are about 6 times, 9 times and 15-37 times lower, respectively, than previously reported and usually accepted estimates. This is independent of the oxidation state or petrological type of the chondrites. The ratios Br/Cl and I/Cl in all studied chondrites show a limited range, indistinguishable from bulk silicate Earth estimates. Our results demonstrate that the halogen depletion of bulk silicate Earth relative to primitive meteorites is consistent with the depletion of lithophile elements of similar volatility. These results for carbonaceous chondrites reveal that late accretion, constrained to a maximum of 0.5 ± 0.2 per cent of Earth’s silicate mass, cannot solely account for present-day terrestrial halogen inventories. It is estimated that 80-90 per cent of heavy halogens are concentrated in Earth’s surface reservoirs and have not undergone the extreme early loss observed in atmosphere-forming elements. Therefore, in addition to late-stage terrestrial accretion of halogens and mantle degassing, which has removed less than half of Earth’s dissolved mantle gases, the efficient extraction of halogen-rich fluids from the solid Earth during the earliest stages of terrestrial differentiation is also required to explain the presence of these heavy halogens at the surface. The hydropilic nature of halogens, whereby they track

Organic halogen compounds in the environment

International Nuclear Information System (INIS)

1979-07-01

There are 20 research reports on selected problems concerning the analysis, the occurence, and the behaviour of a wide spectrum of organic halogen compounds. The work was carried out in the framework of the project 'Organic Halogen Compounds in the Environment', financed by the BMFT, between 1975 and 1978. (orig.) [de

Process for removal of hydrogen halides or halogens from incinerator gas

Science.gov (United States)

Huang, H.S.; Sather, N.F.

1987-08-21

A process for reducing the amount of halogens and halogen acids in high temperature combustion gas and through their removal, the formation of halogenated organics at lower temperatures, with the reduction being carried out electrochemically by contacting the combustion gas with the negative electrode of an electrochemical cell and with the halogen and/or halogen acid being recovered at the positive electrode.

Computational Tools To Model Halogen Bonds in Medicinal Chemistry.

Science.gov (United States)

Ford, Melissa Coates; Ho, P Shing

2016-03-10

The use of halogens in therapeutics dates back to the earliest days of medicine when seaweed was used as a source of iodine to treat goiters. The incorporation of halogens to improve the potency of drugs is now fairly standard in medicinal chemistry. In the past decade, halogens have been recognized as direct participants in defining the affinity of inhibitors through a noncovalent interaction called the halogen bond or X-bond. Incorporating X-bonding into structure-based drug design requires computational models for the anisotropic distribution of charge and the nonspherical shape of halogens, which lead to their highly directional geometries and stabilizing energies. We review here current successes and challenges in developing computational methods to introduce X-bonding into lead compound discovery and optimization during drug development. This fast-growing field will push further development of more accurate and efficient computational tools to accelerate the exploitation of halogens in medicinal chemistry.

Ozone Depletion in Tropospheric Volcanic Plumes: From Halogen-Poor to Halogen-Rich Emissions

Directory of Open Access Journals (Sweden)

Tjarda J. Roberts

2018-02-01

Full Text Available Volcanic halogen emissions to the troposphere undergo a rapid plume chemistry that destroys ozone. Quantifying the impact of volcanic halogens on tropospheric ozone is challenging, only a few observations exist. This study presents measurements of ozone in volcanic plumes from Kīlauea (HI, USA, a low halogen emitter. The results are combined with published data from high halogen emitters (Mt Etna, Italy; Mt Redoubt, AK, USA to identify controls on plume processes. Ozone was measured during periods of relatively sustained Kīlauea plume exposure, using an Aeroqual instrument deployed alongside Multi-Gas SO2 and H2S sensors. Interferences were accounted for in data post-processing. The volcanic H2S/SO2 molar ratio was quantified as 0.03. At Halema‘uma‘u crater-rim, ozone was close to ambient in the emission plume (at 10 ppmv SO2. Measurements in grounding plume (at 5 ppmv SO2 about 10 km downwind of Pu‘u ‘Ō‘ō showed just slight ozone depletion. These Kīlauea observations contrast with substantial ozone depletion reported at Mt Etna and Mt Redoubt. Analysis of the combined data from these three volcanoes identifies the emitted Br/S as a strong but non-linear control on the rate of ozone depletion. Model simulations of the volcanic plume chemistry highlight that the proportion of HBr converted into reactive bromine is a key control on the efficiency of ozone depletion. This underlines the importance of chemistry in the very near-source plume on the fate and atmospheric impacts of volcanic emissions to the troposphere.

Retention of Halogens in Waste Glass

Energy Technology Data Exchange (ETDEWEB)

Hrma, Pavel R.

2010-05-01

In spite of their potential roles as melting rate accelerators and foam breakers, halogens are generally viewed as troublesome components for glass processing. Of five halogens, F, Cl, Br, I, and At, all but At may occur in nuclear waste. A nuclear waste feed may contain up to 10 g of F, 4 g of Cl, and ≤100 mg of Br and I per kg of glass. The main concern is halogen volatility, producing hazardous fumes and particulates, and the radioactive iodine 129 isotope of 1.7x10^7-year half life. Because F and Cl are soluble in oxide glasses and tend to precipitate on cooling, they can be retained in the waste glass in the form of dissolved constituents or as dispersed crystalline inclusions. This report compiles known halogen-retention data in both high-level waste (HLW) and low-activity waste (LAW) glasses. Because of its radioactivity, the main focus is on I. Available data on F and Cl were compiled for comparison. Though Br is present in nuclear wastes, it is usually ignored; no data on Br retention were found.

Halogen-Mediated Conversion of Hydrocarbons to Commodities.

Science.gov (United States)

Lin, Ronghe; Amrute, Amol P; Pérez-Ramírez, Javier

2017-03-08

Halogen chemistry plays a central role in the industrial manufacture of various important chemicals, pharmaceuticals, and polymers. It involves the reaction of halogens or halides with hydrocarbons, leading to intermediate compounds which are readily converted to valuable commodities. These transformations, predominantly mediated by heterogeneous catalysts, have long been successfully applied in the production of polymers. Recent discoveries of abundant conventional and unconventional natural gas reserves have revitalized strong interest in these processes as the most cost-effective gas-to-liquid technologies. This review provides an in-depth analysis of the fundamental understanding and applied relevance of halogen chemistry in polymer industries (polyvinyl chloride, polyurethanes, and polycarbonates) and in the activation of light hydrocarbons. The reactions of particular interest include halogenation and oxyhalogenation of alkanes and alkenes, dehydrogenation of alkanes, conversion of alkyl halides, and oxidation of hydrogen halides, with emphasis on the catalyst, reactor, and process design. Perspectives on the challenges and directions for future development in this exciting field are provided.

E. S. R. studies of halogenated pyrimidines in. gamma. -irradiated alkaline glasses. [Halogenated uracil bases; bromouridine; bromodeoxyuridine

Energy Technology Data Exchange (ETDEWEB)

Simpson, L D; Zimbrick, J D [Kansas Univ., Lawrence (USA)

1975-11-01

The reactions of mobile electrons (e/sup -//sub m/) and oxygen radical anions (O./sup -/) with halogenated bases and nucleosides have been studied in ..gamma..-irradiated alkaline glasses by e.s.r. and specific halogen-ion electrode techniques. It was shown that electrons react with halogenated uracil bases (XUr where X = Cl, Br, I but not F) by dissociative electron attachment to form uracil-5-yl radicals (U.) and halogen anions. The relative rates of reaction of e/sup -//sub m/ with XUr decreased in the sequence BrUr > ClUr > FUr > IUr. Thermal annealing studies carried out on U. in H/sub 2/O and D/sub 2/O matrices supported the hypothesis that U. in H/sub 2/O hydrates across the 5-6 double bond in the temperature region 135/sup 0/ to 155/sup 0/ K, and deuterates to a much smaller extent in D/sub 2/O at temperatures above 155/sup 0/ K. Studies on bromouridine and bromodeoxyuridine suggested that e/sup -/sub(m) reacts with the base moieties to form U. type radicals which abstract H. from the sugar moieties of adjacent nucleosides.

Colorado quartz: occurrence and discovery

Science.gov (United States)

Kile, D.E.; Modreski, P.J.; Kile, D.L.

1991-01-01

The many varieties and associations of quartz found throughout the state rank it as one of the premier worldwide localities for that species. This paper briefly outlines the historical importance of the mineral, the mining history and the geological setting before discussing the varieties of quartz present, its crystallography and the geological enviroments in which it is found. The latter include volcanic rocks and near surface igneous rocks; pegmatites; metamorphic and plutonic rocks; hydrothermal veins; skarns and sedimentary deposits. Details of the localities and mode of occurrence of smoky quartz, amethyst, milky quartz, rock crystal, rose quartz, citrine, agate and jasper are then given. -S.J.Stone

The role of metasomatism in the balance of halogens in ore-forming process at porphyry Cu-Mo deposits

Science.gov (United States)

Berzina, A. N.

2009-04-01

Volatile components play an important role in the evolution of ore-magmatic systems and their ore potential. Of special interest are fluorine and chlorine compounds that principally control the transportation of ore elements by the fluid in a magmatic process and under high-temperature hydrothermal conditions. Study of the evolution of fluorine-chlorine activity in the ore-forming process and their source is usually based on analysis of their magmatic history, whereas the additional source of fluorine and chlorine released during metasomatic alteration of rocks hosting mineralization is poorly discussed in the existing literature. Based on microprobe data on Cl and F abundances in halogen-containing minerals (biotite, amphibole, apatite, titanite) in intrusive rocks and their hydrothermally altered varieties, the role of metasomatic processes in the balance of volatiles in the ore-forming system is discussed by the example of porphyry Cu-Mo deposits of Siberia (Russia) and Mongolia. Two groups of the deposits are considered: copper-molybdenum (Erdenetiin Ovoo, Mongolia and Aksug, Russia) with prevailing propylitic and phyllic alteration and molybdenum-copper (Sora, Russia), with predominant potassic alteration. All types of hydrothermal alterations have led to drastic decrease in Cl contents in metasomatic minerals as compared with halogen-containing magmatic minerals. All studied deposits (particularly those where propylitic and phyllic alteration were developed) show a nearly complete chlorine removal from altered halogen-containing rock-forming minerals (biotite and amphibole). The Cl content in amphibole decreases several times at the stage of replacement with actinolite in the process of propylitization. In the later chlorites (ripidolite and brunsvigite) that replace amphibole, actinolite, and biotite, chlorine is not detected by microprobe (detection limit 0.01-0.02% Cl). Chlorine was also not detected in white micas (muscovite-phengite series) in quartz

Scientific conferences: A big hello to halogen bonding

Science.gov (United States)

Erdelyi, Mate

2014-09-01

Halogen bonding connects a wide range of subjects -- from materials science to structural biology, from computation to crystal engineering, and from synthesis to spectroscopy. The 1st International Symposium on Halogen Bonding explored the state of the art in this fast-growing field of research.

Selective C-H Halogenation with a Highly Fluorinated Manganese Porphyrin.

Science.gov (United States)

Li, Gang; Dilger, Andrew K; Cheng, Peter T; Ewing, William R; Groves, John T

2018-01-26

The selective C-H functionalization of aliphatic molecules remains a challenge in organic synthesis. While radical chain halogenation reactions provide efficient access to many halogenated molecules, the use of typical protocols for the selective halogenation of electron-deficient and strained aliphatic molecules is rare. Herein, we report selective C-H chlorination and fluorination reactions promoted by an electron-deficient manganese pentafluorophenyl porphyrin catalyst, Mn(TPFPP)Cl. This catalyst displays superior properties for the aliphatic halogenation of recalcitrant, electron-deficient, and strained substrates with unique regio- and stereoselectivity. UV/Vis analysis during the course of the reaction indicated that an oxo-Mn V species is responsible for hydrogen-atom abstraction. The observed stereoselectivity results from steric interactions between the bulky porphyrin ligand and the intermediate substrate radical in the halogen rebound step. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hydrogen speciation in synthetic quartz

Science.gov (United States)

Aines, R.D.; Kirby, S.H.; Rossman, G.R.

1984-01-01

The dominant hydrogen impurity in synthetic quartz is molecular H2O. H-OH groups also occur, but there is no direct evidence for the hydrolysis of Si-O-Si bonds to yield Si-OH HO-Si groups. Molecular H2O concentrations in the synthetic quartz crystals studied range from less than 10 to 3,300 ppm (H/Si), and decrease smoothly by up to an order of magnitude with distance away from the seed. OH- concentrations range from 96 to 715 ppm, and rise smoothly with distance away from the seed by up to a factor of three. The observed OH- is probably all associated with cationic impurities, as in natural quartz. Molecular H2O is the dominant initial hydrogen impurity in weak quartz. The hydrolytic weakening of quartz may be caused by the transformation H2O + Si-O-Si ??? 2SiOH, but this may be a transitory change with the SiOH groups recombining to form H2O, and the average SiOH concentration remaining very low. Synthetic quartz is strengthened when the H2O is accumulated into fluid inclusions and cannot react with the quartz framework. ?? 1984 Springer-Verlag.

Influence of Halogen Substituents on the Catalytic Oxidation of 2,4,6-Halogenated Phenols by Fe(III-Tetrakis(p-hydroxyphenyl porphyrins and Potassium Monopersulfate

Directory of Open Access Journals (Sweden)

Seiya Nagao

2011-12-01

Full Text Available The influence of halogen substituents on the catalytic oxidation of 2,4,6-trihalogenated phenols (TrXPs by iron(III-porphyrin/KHSO5 catalytic systems was investigated. Iron(III-5,10,15,20-tetrakis(p-hydroxyphenylporphyrin (FeTHP and its supported variants were employed, where the supported catalysts were synthesized by introducing FeTHP into hydroquinone-derived humic acids via formaldehyde poly-condensation. F (TrFP, Cl (TrCP, Br (TrBP and I (TrIP were examined as halogen substituents for TrXPs. Although the supported catalysts significantly enhanced the degradation and dehalogenation of TrFP and TrCP, the oxidation of TrBP and TrIP was not enhanced, compared to the FeTHP catalytic system. These results indicate that the degree of oxidation of TrXPs is strongly dependent on the types of halogen substituent. The order of dehalogenation levels for halogen substituents in TrXPs was F > Cl > Br > I, consistent with their order of electronegativity. The electronegativity of a halogen substituent affects the nucleophilicity of the carbon to which it is attached. The levels of oxidation products in the reaction mixtures were analyzed by GC/MS after extraction with n-hexane. The most abundant dimer product from TrFP via 2,6-difluoroquinone is consistent with a scenario where TrXP, with a more electronegative halogen substituent, is readily oxidized, while less electronegative halogen substituents are oxidized less readily by iron(III-porphyrin/KHSO5 catalytic systems.

Quartz fiber calorimeter

International Nuclear Information System (INIS)

Akchurin, N.; Doulas, S.; Ganel, O.; Gershtein, Y.; Gavrilov, V.; Kolosov, V.; Kuleshov, S.; Litvinsev, D.; Merlo, J.-P.; Onel, Y.; Osborne, D.; Rosowsky, A.; Stolin, V.; Sulak, L.; Sullivan, J.; Ulyanov, A.; Wigmans, R.; Winn, D.

1996-01-01

A calorimeter with optical quartz fibers embedded into an absorber matrix was proposed for the small angle region of the CMS detector at LHC (CERN). This type of calorimeter is expected to be radiation hard and to produce extremely fast signal. Some results from beam tests of the quartz fiber calorimeter prototype are presented. (orig.)

Effect of high intensity vs. soft-start halogen irradiation on light-cured resin-based composites. Part I. Temperature rise and polymerization shrinkage.

Science.gov (United States)

Hofmann, Norbert; Markert, Tanja; Hugo, Burkard; Klaiber, Bernd

2003-12-01

To determine polymerization shrinkage kinetics and temperature rise of light-cured resin-based composites after high intensity vs. soft-start quartz tungsten halogen irradiation. Shrinkage kinetics was evaluated using the "deflecting disk technique", modified for simultaneous measurement of temperature within the resin-based composite using a thermocouple. Additional irradiations after 60 and 65 minutes allowed the determination of temperature rises caused by radiation or by reaction heat. Four hybrids (Filtek Z250, Herculite, Solitaire 2, Tetric Ceram), an inhomogeneously filled hybrid (InTen-S) and a microfill (Filtek A110, formerly Silux Plus) were cured using the quartz tungsten halogen units Astralis 10 and Optilux 501 in the high intensity (A10 HiPo: 10 seconds at 1300 mW/cm2; OL Boost: 10 seconds at 1140 mW/cm2) or soft-start modes (A10 Pulse: increase to 700 mW/cm2 within 10 seconds, three periods of 2 seconds at 1300 mW/cm2 alternating with two periods of 2 seconds at 700 mW/cm2; OL Ramp: exponential increase within 10 seconds, followed by 10 seconds at 1140 mW/cm2). The soft-start protocols produced less contraction, and polymerization shrinkage started later and progressed slower (or: more slowly), compared to high intensity irradiation [correction]. The lowest shrinkage was observed for InTen-S, followed by Filtek Z250 and A110, whereas Solitaire 2, Herculite and Tetric Ceram scored highest for this parameter. Temperature rise was caused more or less equally by radiation and by reaction heat and reached values of up to 28.9 degrees C relative to a baseline of 37 degrees C. For some combinations of curing modes and resin-based composites, less heat was generated by the soft-start protocols and by Optilux 501.

40 CFR 721.5452 - Alkali metal salt of halogenated organoborate (generic).

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Alkali metal salt of halogenated... Specific Chemical Substances § 721.5452 Alkali metal salt of halogenated organoborate (generic). (a... generically as alkali metal salt of halogenated organoborate (PMN P-00-0638) is subject to reporting under...

LED and Halogen Light Transmission through a CAD/CAM Lithium Disilicate Glass-Ceramic.

Science.gov (United States)

Pereira, Carolina Nemesio de Barros; De Magalhães, Cláudia Silami; Daleprane, Bruno; Peixoto, Rogéli Tibúrcio Ribeiro da Cunha; Ferreira, Raquel da Conceição; Cury, Luiz Alberto; Moreira, Allyson Nogueira

2015-01-01

The effect of thickness, shade and translucency of CAD/CAM lithium disilicate glass-ceramic on light transmission of light-emitting diode (LED) and quartz-tungsten-halogen units (QTH) were evaluated. Ceramic IPS e.max CAD shades A1, A2, A3, A3.5, high (HT) and low (LT) translucency were cut (1, 2, 3, 4 and 5 mm). Light sources emission spectra were determined. Light intensity incident and transmitted through each ceramic sample was measured to determine light transmission percentage (TP). Statistical analysis used a linear regression model. There was significant interaction between light source and ceramic translucency (p=0.008) and strong negative correlation (R=-0.845, pceramic thickness and TP. Increasing one unit in thickness led to 3.17 reduction in TP. There was no significant difference in TP (p=0.124) between shades A1 (ß1=0) and A2 (ß1=-0.45) but significant reduction occurred for A3 (ß1=-0.83) and A3.5 (ß1=-2.18). The interaction QTH/HT provided higher TP (ß1=0) than LED/HT (ß1=-2.92), QTH/LT (ß1=-3.75) and LED/LT (ß1=-5.58). Light transmission was more effective using halogen source and high-translucency ceramics, decreased as the ceramic thickness increased and was higher for the lighter shades, A1 and A2. From the regression model (R2=0.85), an equation was obtained to estimate TP value using each variable ß1 found. A maximum TP of 25% for QTH and 20% for LED was found, suggesting that ceramic light attenuation could compromise light cured and dual cure resin cements polymerization.

Construction of Tungsten Halogen, Pulsed LED, and Combined Tungsten Halogen-LED Solar Simulators for Solar Cell I-V Characterization and Electrical Parameters Determination

Directory of Open Access Journals (Sweden)

Anon Namin

2012-01-01

Full Text Available I-V characterization of solar cells is generally done under natural sunlight or solar simulators operating in either a continuous mode or a pulse mode. Simulators are classified on three features of irradiance, namely, spectral match with respect to air mass 1.5, spatial uniformity, and temporal stability. Commercial solar simulators use Xenon lamps and halogen lamps, whereas LED-based solar simulators are being developed. In this work, we build and test seven simulators for solar cell characterization, namely, one tungsten halogen simulator, four monochromatic (red, green, blue, and white LED simulators, one multicolor LED simulator, and one tungsten halogen-blue LED simulator. The seven simulators provide testing at nonstandard test condition. High irradiance from simulators is obtained by employing elevated supply voltage to tungsten halogen lamps and high pulsing voltages to LEDs. This new approach leads to higher irradiance not previously obtained from tungsten halogen lamps and LEDs. From I-V curves, electrical parameters of solar cell are made and corrected based on methods recommended in the IEC 60891 Standards. Corrected values obtained from non-STC measurements are in good agreement with those obtained from Class AAA solar simulator.

SYNTHESIS AND CHARACTERIZATION OF NEW HALOGENATED CURCUMINOIDS

Directory of Open Access Journals (Sweden)

Eugenio Torres

2013-12-01

Full Text Available In this work a novel procedure of synthesis of compounds analogues to curcumin with halogens atoms in its structure is described, which can increase its solubility and biological activity. Four halogenated curcuminoids were obtained with great pharmacological interest, none of them reported in literature before. Synthesis was carried out by means of the aldol condensation assisted by microwaves of halogenated aromatic aldehydes and acetylacetona, using morpholine as basic catalyst, in absence of solvent, and the reaction just needed 1 min. The products were purified by treatment of the reaction mixture with methanol under ultrasound irradiation, followed by chromatographic column. All obtained compounds were characterized by infrared spectroscopy, nuclear magnetic resonance, quantitative elementary analysis and high resolution mass spectrometry. The RMN-1H data demonstrate in all structures of synthesized curcuminoids the enol form is the most favored.

40 CFR 721.8900 - Substituted halogenated pyridinol, alkali salt.

Science.gov (United States)

2010-07-01

..., alkali salt. 721.8900 Section 721.8900 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.8900 Substituted halogenated pyridinol, alkali salt. (a) Chemical... as substituted halogenated pyridinols, alkali salts (PMNs P-88-1271 and P-88-1272) are subject to...

The problem of dating quartz 2: Synchrotron generated X-ray excited optical luminescence (XEOL) from quartz

International Nuclear Information System (INIS)

King, G.E.; Finch, A.A.; Robinson, R.A.J.; Taylor, R.P.; Mosselmans, J.F.W.

2011-01-01

The luminescence emission of quartz is used in optically stimulated luminescence dating (OSL), however the precise origins of the emission are unclear. A suite of quartz samples were analysed using X-ray excited optical luminescence (XEOL). Radiation dose effects were observed whereby the UV emissions (3.8 and 3.4 eV) were depleted to the benefit of the red emission (1.9-2.0 eV). Samples were excited at ∼7 keV. Understanding why some quartz emit light more brightly than others will increase the efficiency and precision of OSL analyses. - Highlights: → The X-ray excited optical luminescence (XEOL) emission of quartz is explored. → The XEOL of quartz of different provenances varies. → Radiation dosing causes UV emissions to deplete to the benefit of red emissions. → The 3.8 and 3.4 eV emissions deplete at the same rate. → The quartz luminescence emission exhibits anisotropic effects.

Quartz analysis in gravimetric sampling

International Nuclear Information System (INIS)

Rex, D.A.

1990-01-01

An overview of the methods employed in the assessment of quartz exposure is provided. The principles and some of the problems associated with each method is discussed. The methods reviewed include wet chemical methods, X-ray diffraction and infrared absorption of which the latter two methods are deemed appropriate for analysing quartz on personal gravimetric collected samples. The implications of combining area samples collected over a six month period, and performing only a single quartz analysis rather than separate analyses, are considered. Finally, various options open to mines with regard to their involvement with quartz analysis are also briefly discussed. 35 refs., 6 figs., 1 tab

The unique role of halogen substituents in the design of modern agrochemicals.

Science.gov (United States)

Jeschke, Peter

2010-01-01

The past 30 years have witnessed a period of significant expansion in the use of halogenated compounds in the field of agrochemical research and development. The introduction of halogens into active ingredients has become an important concept in the quest for a modern agrochemical with optimal efficacy, environmental safety, user friendliness and economic viability. Outstanding progress has been made, especially in synthetic methods for particular halogen-substituted key intermediates that were previously prohibitively expensive. Interestingly, there has been a rise in the number of commercial products containing 'mixed' halogens, e.g. one or more fluorine, chlorine, bromine or iodine atoms in addition to one or more further halogen atoms. Extrapolation of the current trend indicates that a definite growth is to be expected in fluorine-substituted agrochemicals throughout the twenty-first century. A number of these recently developed agrochemical candidates containing halogen substituents represent novel classes of chemical compounds with new modes of action. However, the complex structure-activity relationships associated with biologically active molecules mean that the introduction of halogens can lead to either an increase or a decrease in the efficacy of a compound, depending on its changed mode of action, physicochemical properties, target interaction or metabolic susceptibility and transformation. In spite of modern design concepts, it is still difficult to predict the sites in a molecule at which halogen substitution will result in optimal desired effects. This review describes comprehensively the successful utilisation of halogens and their unique role in the design of modern agrochemicals, exemplified by various commercial products from Bayer CropScience coming from different agrochemical areas.

Special features of self-compensation of halogen donor action in lead telluride

International Nuclear Information System (INIS)

Kajdanov, V.I.; Nemov, S.A.; Ravich, Yu.I.; Dereza, A.Yu.

1985-01-01

Specific features of self-compensation of halogen donor action in lead telluride are investigasted. Lead telluride samples with chlorine additions (with tellurium excess) and, besides, with bromine- and iodine additions were studied in order to reveal general regularities in alloyind with all halogen donor impurities. Experimental dependences of the difference between the electron and hole concentrations (n-p) in PbTe as a function of an amount of introduced halogen impurities (Ni) are presented for samples with a maximum compensation at 295 K. General features of the n-p=f(Ni) dependence are presented for all halogens. The hypothesis on the kinetic mechanism of increasing the efficiency of self-compensation of halogen donor action in lead telluride is suggested

Spectrographic determination of traces of halogens; Dosage de traces d'halogenes par la methode spectrographique

Energy Technology Data Exchange (ETDEWEB)

Melamed, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1961-07-01

Hollow cathode source is employed for determining traces of halogens (fluorine - chlorine) in the uranium oxide U{sub 3}O{sub 8} qualitatively, detection of at least 40 ppm of fluorine, as alkali fluoride and 125 ppm of chlorine, is possible. (author) [French] Un tube a decharge a cathode creuse a ete utilise pour la determination spectrographique des halogenes (fluor - chlore) presentes a l'etat de traces dans un oxyde d'uranium U{sub 3}O{sub 8}. On a pu deceler qualitativement des teneurs de 40 ppm de fluor sous forme de fluorures alcalins. En ce qui concerne le chlore, la plus faible teneur decelee a ete de 125 ppm. (auteur)

Blue Light Emitting Diodes for Optical Stimulation of Quartz in Retrospective Dosimetry and Dating (invited paper)

International Nuclear Information System (INIS)

Botter-Jensen, L.; Duller, G.A.T.; Murray, A.S.; Banerjee, D.

1999-01-01

Recently developed blue light emitting diodes (LEDs) for the optical stimulation of quartz for use in routine optically stimulated luminescence (OSL) dating and retrospective dosimetry have been tested. For similar power densities, it was found that the higher energy light provided by the blue LEDs (470 nm) gives order of magnitude greater rate of stimulation in quartz than that from conventional blue-green light filtered from a halogen lamp. A practical blue LED OSL configuration is described. From comparisons of OSL decay curves produced by green and blue light sources, and by examination of the dependence of the blue LED OSL on preheat temperature, it is deduced that there is no evidence that the blue LEDs stimulate deep traps in a different manner from broadband filtered light. It is concluded that blue LEDs offer a practical alternative to existing stimulation sources. They have the significant advantages that the life-time is indefinite, and the output can be controlled electronically; this allows the power to be readily controlled by software. Unlike a filtered light source, there are no electromechanical parts, and the switch on/off times are about 10 times faster than a shutter. Finally, preliminary results from ramping the blue light power output with time are demonstrated. It is shown that this technique enables the separation of OSL components with differing stimulation rates. (author)

Radiation-Hard Quartz Cerenkov Calorimeters

International Nuclear Information System (INIS)

Akgun, U.; Onel, Y.

2006-01-01

New generation hadron colliders are going to reach unprecedented energies and radiation levels. Quartz has been identified as a radiation-hard material that can be used for Cerenkov calorimeters of the future experiments. We report from the radiation hardness tests performed on quartz fibers, as well as the characteristics of the quartz fiber and plate Cerenkov calorimeters that have been built, designed, and proposed for the CMS experiment

Halogenated organic compounds in archived whale oil: A pre-industrial record

International Nuclear Information System (INIS)

Teuten, Emma L.; Reddy, Christopher M.

2007-01-01

To provide additional evidence that several halogenated organic compounds (HOCs) found in environmental samples are natural and not industrially produced, we analyzed an archived whale oil sample collected in 1921 from the last voyage of the whaling ship Charles W. Morgan. This sample, which pre-dates large-scale industrial manufacture of HOCs, contained two methoxylated polybrominated diphenyl ethers (MeO-PBDEs), five halogenated methyl bipyrroles (MBPs), one halogenated dimethyl bipyrrole (DMBP), and tentatively one dimethoxylated polybrominated biphenyl (diMeO-PBB). This result indicates, at least in part, a natural source of the latter compounds. - Nine halogenated organic compounds have been detected in archived whale oil from the early 1920s

Halogenated organic compounds in archived whale oil: A pre-industrial record

Energy Technology Data Exchange (ETDEWEB)

Teuten, Emma L. [Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, MA 02543 (United States)]. E-mail: emma.teuten@plymouth.ac.uk; Reddy, Christopher M. [Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, 360 Woods Hole Road, Woods Hole, MA 02543 (United States)]. E-mail: creddy@whoi.edu

2007-02-15

To provide additional evidence that several halogenated organic compounds (HOCs) found in environmental samples are natural and not industrially produced, we analyzed an archived whale oil sample collected in 1921 from the last voyage of the whaling ship Charles W. Morgan. This sample, which pre-dates large-scale industrial manufacture of HOCs, contained two methoxylated polybrominated diphenyl ethers (MeO-PBDEs), five halogenated methyl bipyrroles (MBPs), one halogenated dimethyl bipyrrole (DMBP), and tentatively one dimethoxylated polybrominated biphenyl (diMeO-PBB). This result indicates, at least in part, a natural source of the latter compounds. - Nine halogenated organic compounds have been detected in archived whale oil from the early 1920s.

Halogens are key cofactors in building of collagen IV scaffolds outside the cell.

Science.gov (United States)

Brown, Kyle L; Hudson, Billy G; Voziyan, Paul A

2018-05-01

The purpose of this review is to highlight recent advances in understanding the molecular assembly of basement membranes, as exemplified by the glomerular basement membrane (GBM) of the kidney filtration apparatus. In particular, an essential role of halogens in the basement membrane formation has been discovered. Extracellular chloride triggers a molecular switch within non collagenous domains of collagen IV that induces protomer oligomerization and scaffold assembly outside the cell. Moreover, bromide is an essential cofactor in enzymatic cross-linking that reinforces the stability of scaffolds. Halogenation and halogen-induced oxidation of the collagen IV scaffold in disease states damage scaffold function. Halogens play an essential role in the formation of collagen IV scaffolds of basement membranes. Pathogenic damage of these scaffolds by halogenation and halogen-induced oxidation is a potential target for therapeutic interventions.

Halonium Ions as Halogen Bond Donors in the Solid State [XL2]Y Complexes.

Science.gov (United States)

Rissanen, Kari; Haukka, Matti

2015-01-01

The utilization of halogen bonding interactions is one of the most rapidly developing areas of supramolecular chemistry. While the other weak non-covalent interactions and their influence on the structure and chemistry of various molecules, complexes, and materials have been investigated extensively, the understanding, utilizations, and true nature of halogen bonding are still relatively unexplored. Thus its final impact in chemistry in general and in materials science has not yet been fully established. Because of the polarized nature of a Z-X bond (Z=electron-withdrawing atom or moiety and X=halogen atom), such a moiety can act as halogen bond donor when the halogen is polarized enough by the atom/moiety Z. The most studied and utilized halogen bond donor molecules are the perfluorohalocarbons, where Z is a perfluorinated aryl or alkyl moiety and X is either iodine or bromine. Complementing the contemporary halogen bonding research, this chapter reviews the solid state structural chemistry of the most extremely polarized halogen atoms, viz. halonium ions, X+, and discussed them as halogen bond donors in the solid state [XL2]Y complexes (X=halonium ion, Y=any anion).

Metal-Mediated Halogen Exchange in Aryl and Vinyl Halides: a Review

Science.gov (United States)

Evano, Gwilherm; Nitelet, Antoine; Thilmany, Pierre; Dewez, Damien F.

2018-04-01

Halogenated arenes and alkenes are of prime importance in many areas of science, especially in the pharmaceutical, agrochemical and chemical industries. While the simplest ones are commercially available, some of them are still hardly accessible depending on their substitution patterns and the nature of the halogen atom. Reactions enabling the selective and efficient replacement of the halogen atom of an aryl or alkenyl halide by another one, lighter or heavier, are therefore of major importance since they can be used for example to turn a less reactive aryl/alkenyl chloride into the more reactive iodinated derivatives or, in a reversed sense, to block an undesired reactivity, for late-stage modifications or for the introduction of a radionuclide. If some halogen exchange reactions are possible with activated substrates, they usually require catalysis with metal complexes. Remarkably efficient processes have been developed for metal-mediated halogen exchange in aryl and vinyl halides: they are overviewed, in a comprehensive manner, in this review article.

Halogenated furanones inhibit quorum sensing through accelerated LuxR turnover

DEFF Research Database (Denmark)

Manefield, M.; Rasmussen, Thomas Bovbjerg; Henzter, M.

2002-01-01

fischeri overproduced in Escherichia coli. Whilst a stable interaction between the algal metabolite and the bacterial protein was not found, it was noted by Western analysis that the half-life of the protein is reduced up to 100-fold in the presence of halogenated furanones. This suggests that halogenated...... that the reduction in LuxR concentration is the mechanism by which furanones control expression of AHL-dependent phenotypes. The mode of action by which halogenated furanones reduce cellular concentrations of the LuxR protein remains to be characterized....

Thermal behavior of halogenated imidebismaleimide resins

International Nuclear Information System (INIS)

Mohammad, A.; Al-Halim, N.Z.

1995-01-01

Several new poly-halogenated malecimides, bismaleimides and therir copoly resins were synthessised thermally from their corresponding amic acids. The synthesis was accomplished by two way method (amic acid-polimide) instead of the well-known three way method (amic acid-imide-polyimide). Thermal characterization of monomers and their cured resins was achieved using differential thermal analysis (DTA), dynamic thermogravimetric analysis (TGA) and isothermal gravimetric analysis (IGA). The effect of halogen substituent, especially in the ortho postion, is clear in the imidization proces, while polymerization proceeds almost equally in all systems. Thermal properties of homo and copolymers were correlated with their chemical structures. (author). 15 refs., 4

Quartz glass behavior at ultraviolet spectrum region

International Nuclear Information System (INIS)

Braga, A.F.B.; Barbosa, L.C.; Evora, C.A.P.D.

1990-01-01

Melted quartz ingots were produced from raw materials of different sources. Behavior studies of these three different quartz glass were made at the eletromagnetic spectrum ultraviolet region. The atomic absorption spectroscopy was used as an analysis technique of the alkaline, transition and aluminum metal traces. It was found that the alkaline, transition and aluminum metals impurities present a great influence on the melted quartz spectral behavior at the ultraviolet region. It was stated that measurments at this spectrum region constitute an important characterization technique to natural quartz as well as melted quartz. (author) [pt

Development of non-halogen cables for nuclear power stations

Energy Technology Data Exchange (ETDEWEB)

Yagyu, Hideki; Yamamoto, Yasuaki; Onishi, Takao (Hitachi Cable, Ltd., Tokyo (Japan))

1983-12-01

The non-halogen fire-resistant cables for nuclear power stations which never generate halogen gas, have been developed. The cables comprise the insulator of EP rubber and the sheath of polyolefine containing non-halogen inorganic fire-retardant. The results of the environmental test and fire-resistance test are described. In the environmental test, the cables were subjected to the heating, gamma-irradiation and steam exposure successively, according to IEEE specification 323,383, and subsequently the change in the appearance, tensile strength and electrical performance of the cables was measured. In the fire-resistance test, the vertical tray fire test according to the IEEE specification 383 was adopted, and other tests including the vertical fire test on insulator cores, oxygen index, the generation of corrosive gas, copper mirror corrosion test, gas toxicity test and optical smoke density test were carried out. It became clear that the cables did not generate halogen gas on burning, and brought about reduced toxicity, corrosion and smoke, and that the safety against fire is greatly improved by using the cables.

Development of non-halogen cables for nuclear power stations

International Nuclear Information System (INIS)

Yagyu, Hideki; Yamamoto, Yasuaki; Onishi, Takao

1983-01-01

The non-halogen fire-resistant cables for nuclear power stations which never generate halogen gas, have been developed. The cables comprise the insulator of EP rubber and the sheath of polyolefine containing non-halogen inorganic fire-retardant. The results of the environmental test and fire-resistance test are described. In the environmental test, the cables were subjected to the heating, gamma-irradiation and steam exposure successively, according to IEEE specification 323,383, and subsequently the change in the appearance, tensile strength and electrical performance of the cables was measured. In the fire-resistance test, the vertical tray fire test according to the IEEE specification 383 was adopted, and other tests including the vertical fire test on insulator cores, oxygen index, the generation of corrosive gas, copper mirror corrosion test, gas toxicity test and optical smoke density test were carried out. It became clear that the cables did not generate halogen gas on burning, and brought about reduced toxicity, corrosion and smoke, and that the safety against fire is greatly improved by using the cables. (Yoshitake, I.)

Process for reducing halogen impurities in oil products

Energy Technology Data Exchange (ETDEWEB)

Basler, F.

1990-08-14

Oil products, in particular waste oils, may be efficiently reprocessed according to an economic and technically simple method for removing impurities, notably halogens. In this method, the oil product is treated at temperatures up to about 150{degree}C with an effective amount of an aqueous solution of at least one compound selected from the group consisting of a strong acid, a salt of a weak base and a strong acid and precursors thereof. The oil product obtained in this step is treated at increased temperatures with at least one halogen binding agent. The water and/or solids from the product so treated are separated out. The process of the invention can be carried out in a conventional stripping apparatus. The strong acid used in the first step is preferably selected from sulfurous acid, phosphoric acid, phosphorous acid, and phosphonic acid. The salt of the weak base and strong acid is preferably ammonium sulfate, ammonium bisulfate, ammonium sulfite, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphite, and ammonium phosphonic acid. The second step of the method is preferably a coagulation step in which organic halogen compounds break down into hydrogen halides which are neutralized by the added halogen binding agents. The preferred halogen binding agents are ammonia and/or an organic base. The coagulation is preferably carried out in heat exchangers so that the oil is heated in 3 stages and the oil from each stage is passed through a cascade tower. In the third step, additives may be used to enhance separation of the oil. Experiments are described to illustrate the method of the invention. 1 tab.

Participation of the Halogens in Photochemical Reactions in Natural and Treated Waters

Directory of Open Access Journals (Sweden)

Yi Yang

2017-10-01

Full Text Available Halide ions are ubiquitous in natural waters and wastewaters. Halogens play an important and complex role in environmental photochemical processes and in reactions taking place during photochemical water treatment. While inert to solar wavelengths, halides can be converted into radical and non-radical reactive halogen species (RHS by sensitized photolysis and by reactions with secondary reactive oxygen species (ROS produced through sunlight-initiated reactions in water and atmospheric aerosols, such as hydroxyl radical, ozone, and nitrate radical. In photochemical advanced oxidation processes for water treatment, RHS can be generated by UV photolysis and by reactions of halides with hydroxyl radicals, sulfate radicals, ozone, and other ROS. RHS are reactive toward organic compounds, and some reactions lead to incorporation of halogen into byproducts. Recent studies indicate that halides, or the RHS derived from them, affect the concentrations of photogenerated reactive oxygen species (ROS and other reactive species; influence the photobleaching of dissolved natural organic matter (DOM; alter the rates and products of pollutant transformations; lead to covalent incorporation of halogen into small natural molecules, DOM, and pollutants; and give rise to certain halogen oxides of concern as water contaminants. The complex and colorful chemistry of halogen in waters will be summarized in detail and the implications of this chemistry for global biogeochemical cycling of halogen, contaminant fate in natural waters, and water purification technologies will be discussed.

Experimental diagenesis of quartz with petroleum; Diagenese experimentale du quartz en presence d'hydrocarbures

Energy Technology Data Exchange (ETDEWEB)

Teinturier, St.

2002-11-01

Quartz cementation has a great impact on petroleum reservoir quality by controlling the porosity and thus the gas or oil storage. However, the possible cementation of quartz during petroleum emplacement is still debated. In most cases, the reconstitution and the understanding of diagenetic processes is based on fluid inclusions studies. However, many questions concerning the representativeness and the reading of the fluid inclusions still remains misunderstood. The experiments were carried out in a silica{+-}water{+-}salts{+-}oil{+-}gas system with the objective to simulate the siliceous diagenesis of natural petroleum reservoirs and to better understand the mechanisms of fluid inclusions formation and quartz cementation in a water and/or petroleum system. Calibration curves have been established using Raman micro-spectroscopy and synthetic reference inclusions to calculate the methane content of aqueous inclusions in the H{sub 2}O-CH{sub 4}-NaCl system. A quantitative procedure for FT-IR micro-spectrometry has been developed to obtain, from individual petroleum fluid inclusions, mole % concentrations of methane, alkanes and carbon dioxide as constraints to thermodynamic modelling. Synthetic aqueous inclusions were created within quartz micro-fractures, with methane (from 150 deg C-200 bar), with petroleum (from 184 deg C-163 bar) and inside quartz overgrowth with the presence of hydrocarbons (from 277 deg C-300 bar). Synthetic petroleum inclusions were created with different water/oil ratios (W/O) within quartz micro-fractures (0quartz overgrowth (10

First-principles studies on the effects of halogen adsorption on monolayer antimony.

Science.gov (United States)

Yeoh, Keat Hoe; Yoon, Tiem Leong; Ong, Duu Sheng; Lim, Thong Leng; Zuntu Abdullahi, Yusuf

2017-09-27

Using first-principles calculations, we carry out systematic studies on the electronic, magnetic and structural properties of halogenated β-phase antimonene. We consider two different levels of halogen adatom coverage i.e. Θ = 1/8 and Θ = 1/18. It is found that F, Cl and Br adatoms act as acceptors whereas the I adatom acts as a donor. For a high coverage of Θ = 1/8, halogenated β-phase antimonene exhibits metallic characteristics. With a lower coverage of Θ = 1/18, through the adsorption of F, Cl and Br the semiconducting unstrained antimonene becomes metallic. In contrast, I-adsorbed antimonene remains semiconducting but exhibits magnetic behavior. We further investigate the effects of bi-axial strain on the halogenated β-phase antimonene. It is found that bi-axial strain can only induce ferromagnetism on the halogenated antimonene at Θ = 1/18. However, the ferromagnetism is suppressed when the applied strain is high. We uncover that the emergence of strain-dependent magnetism is attributed to the presence of localized states in the bandgap resulting from collective effects of bi-axial strain and the adsorption of halogen atoms.

Study of seed for synthetical quartz

International Nuclear Information System (INIS)

Suzuki, C.K.; Torikai, D.

1988-01-01

Natural quartz blocks for seed (synthetic quartz technology) were studied by using various characterization techniques, such as X-ray topography, optical micrography, inspectoscopy, polariscopy and conoscopy, and etching. One of the most commonly found defect is the electrical or Dauphine twin. In The present research, we have developed a methodology to obtain a highly perfect seed for the synthetic quartz industries. (author) [pt

Halogenation dictates the architecture of amyloid peptide nanostructures.

Science.gov (United States)

Pizzi, Andrea; Pigliacelli, Claudia; Gori, Alessandro; Nonappa; Ikkala, Olli; Demitri, Nicola; Terraneo, Giancarlo; Castelletto, Valeria; Hamley, Ian W; Baldelli Bombelli, Francesca; Metrangolo, Pierangelo

2017-07-20

Amyloid peptides yield a plethora of interesting nanostructures though difficult to control. Here we report that depending on the number, position, and nature of the halogen atoms introduced into either one or both phenylalanine benzene rings of the amyloid β peptide-derived core-sequence KLVFF, four different architectures were obtained in a controlled manner. Our findings demonstrate that halogenation may develop as a general strategy to engineer amyloidal peptide self-assembly and obtain new amyloidal nanostructures.

Quartz gauge response in ion radiation

International Nuclear Information System (INIS)

Taylor, P.E.; Gilbert, P.H.; Kernthaler, C.; Anderson, M.U.

1995-01-01

This paper describes recent work to make high quality quartz gauge (temporal and spatial) shock wave measurements in a pulsed ion beam environment. Intense ion beam radiation, nominally 1 MeV protons, was deposited into material samples instrumented with shunted quartz gauges adjacent to the ion deposition zone. Fluence levels were chosen to excite three fundamentally different material response modes (1) strong vapor, (2) combined vapor and melt phase and (3) thermoelastic material response. A unique quartz gauge design was utilized that employed printed circuit board (PCB) technology to facilitate electrical shielding, ruggedness, and fabrication at sign e meeting the essential one dimensional requirements of the characterized Sandia shunted quartz gauge. Shock loading and unloading experiments were conducted to evaluate the piezoelectric response of the coupled quartz gauge/PCB transducer. High fidelity shock wave profiles were recorded at the three ion fluence levels providing dynamic material response data for vapor, melt and solid material phases

Induction of bacterial antibiotic resistance by mutagenic halogenated nitrogenous disinfection byproducts

International Nuclear Information System (INIS)

Lv, Lu; Yu, Xin; Xu, Qian; Ye, Chengsong

2015-01-01

Halogenated nitrogenous disinfection byproducts (N-DBPs) raise concerns regarding their mutagenicity and carcinogenicity threatening public health. However, environmental consequence of their mutagenicity has received less attention. In this study, the effect of halogenated N-DBPs on bacterial antibiotic resistance (BAR) was investigated. After exposure to bromoacetamide (BAcAm), trichloroacetonitrile (TCAN) or tribromonitromethane (TBNM), the resistance of Pseudomonas aeruginosa PAO1 to both individual and multiple antibiotics (ciprofloxacin, gentamicin, polymyxin B, rifampin, tetracycline, ciprofloxacin + gentamicin and ciprofloxacin + tetracycline) was increased, which was predominantly ascribed to the overexpression of efflux pumps. The mechanism of this effect was demonstrated to be mutagenesis through sequencing and analyzing antibiotic resistance genes. The same induction phenomena also appeared in Escherichia coli, suggesting this effect may be universal to waterborne pathogens. Therefore, more attention should be given to halogenated N-DBPs, as they could increase not only genotoxicological risks but also epidemiological risks of drinking water. - Highlights: • The halogenated N-DBPs could induce bacterial antibiotic resistance. • Both individual and multiple resistances could be induced. • Efflux mechanism played an important role in the induced antibiotic resistance. • The halogenated N-DBPs induced bacterial antibiotic resistance via mutagenesis. • Effects of N-DBPs on antibiotic resistance may be universal to waterborne pathogens. - Halogenated N-DBPs could increase antibiotic resistance, even multidrug resistance via mutagenesis, contributing to the enrichment of antibiotic resistant bacteria in drinking water

Concentration-dependent multiple chirality transition in halogen-bond-driven 2D self-assembly process

Science.gov (United States)

Miao, Xinrui; Li, Jinxing; Zha, Bao; Miao, Kai; Dong, Meiqiu; Wu, Juntian; Deng, Wenli

2018-03-01

The concentration-dependent self-assembly of iodine substituted thienophenanthrene derivative (5,10-DITD) is investigated at the 1-octanic acid/graphite interface using scanning tunneling microscopy. Three kinds of chiral arrangement and transition of 2D molecular assembly mainly driven by halogen bonding is clearly revealed. At high concentration the molecules self-assembled into a honeycomb-like chiral network. Except for the interchain van der Waals forces, this pattern is stabilized by intermolecular continuous Cdbnd O⋯I⋯S halogen bonds in each zigzag line. At moderate concentration, a chiral kite-like nanoarchitecture are observed, in which the Cdbnd O⋯I⋯S and I⋯Odbnd C halogen bonds, along with the molecule-solvent Cdbnd O⋯I⋯H halogen bonds are the dominated forces to determine the structural formation. At low concentration, the molecules form a chiral cyclic network resulting from the solvent coadsorption mainly by molecule-molecule Cdbnd O⋯I⋯S halogen bonds and molecule-solvent Cdbnd O⋯I⋯H halogen bonds. The density of molecular packing becomes lower with the decreasing of the solution concentration. The solution-concentration dependent self-assembly of thienophenanthrene derivative with iodine and ester chain moieties reveals that the type of intermolecular halogen bond and the number of the co-adsorbing 1-octanic acids by molecule-solvent Cdbnd O⋯I⋯H halogen bonds determine the formation and transformation of chirality. This research emphasizes the role of different types of halogen (I) bonds in the controllable supramolecular structures and provides an approach for the fabrication of chirality.

Synthesis of Isotactic-block-Syndiotactic Poly(methyl Methacrylate via Stereospecific Living Anionic Polymerizations in Combination with Metal-Halogen Exchange, Halogenation, and Click Reactions

Directory of Open Access Journals (Sweden)

Naoya Usuki

2017-12-01

Full Text Available Isotactic (it- and syndiotactic (st- poly(methyl methacrylates (PMMAs form unique crystalline stereocomplexes, which are attractive from both fundamental and application viewpoints. This study is directed at the efficient synthesis of it- and st-stereoblock (it-b-st- PMMAs via stereospecific living anionic polymerizations in combination with metal-halogen exchange, halogenation, and click reactions. The azide-capped it-PMMA was prepared by living anionic polymerization of MMA, which was initiated with t-BuMgBr in toluene at –78 °C, and was followed by termination using CCl4 as the halogenating agent in the presence of a strong Lewis base and subsequent azidation with NaN3. The alkyne-capped st-PMMA was obtained by living anionic polymerization of MMA, which was initiated via an in situ metal-halogen exchange reaction between 1,1-diphenylhexyl lithium and an α-bromoester bearing a pendent silyl-protected alkyne group. Finally, copper-catalyzed alkyne-azide cycloaddition (CuAAC between these complimentary pairs of polymers resulted in a high yield of it-b-st-PMMAs, with controlled molecular weights and narrow molecular weight distributions. The stereocomplexation was evaluated in CH3CN and was affected by the block lengths and ratios.

Halogen bonding: A new retention mechanism for the solid phase extraction of perfluorinated iodoalkanes

International Nuclear Information System (INIS)

Yan Xiaoqing; Shen Qianjin; Zhao Xiaoran; Gao Haiyue; Pang Xue; Jin Weijun

2012-01-01

Highlights: ► Halogen bonding (XB) is firstly utilised in solid phase extraction. ► The perfluorinated iodine alkanes can be extracted by C-I⋯Cl − halogen bonding. ► The C-I⋯Cl − halogen bond is well characterised by spectroscopy methods. ► The analytes with strong halogen-bonding abilities can be selectively extracted. - Abstract: For the first time, halogen-bonding interaction is utilised in the solid phase extraction of perfluorinated iodoalkane (PFI). Nine PFIs, as model analytes, were tested, and analyses by UV, 19 F NMR and Raman spectroscopies demonstrate that the PFIs are extracted by a strong anion exchange (SAX) sorbent from n-hexane due to the C-I⋯Cl − halogen-bonding interactions. The results also show that the adsorptivities of SAX for the diiodoperfluoro-alkanes (diiodo-PFIs) were much stronger than those for the perfluoroalkyl iodides (monoiodo-PFIs). Specifically, the recoveries for 1,6-diiodoperfluorohexane and 1,8-diiodoperfluorooctane were higher than 80% when 100 mL of sample spiked with a 5 ng mL −1 analyte mixture was extracted. Interestingly, SAX had no adsorption for hexafluorobenzene at all, which is known to be unable to form a halogen bond with Cl − . The analytical performance of the halogen bond-based SPE-GC–MS method for the diiodo-PFIs was also examined in soil samples. The sorbent SAX enabled the selective extraction of four diiodo-PFIs successfully from soil samples. The recoveries of the diiodo-PFIs extracted from 5 g soil sample at the 100 ng g −1 spike level were in the range of 73.2–93.8% except 26.8% for 1,2-diiodoperfluoroethane. The limit of detection varied from 0.02 to 0.04 ng g −1 in soil samples. Overall, this work reveals the great application potential of halogen bonding in the field of solid phase extraction to selectively extract compounds with strong halogen-bonding abilities.

Positron states and nanoobjects in proton-irradiated quartz single crystals: Positronium atom in quartz

International Nuclear Information System (INIS)

Grafutin, V. I.; Zaluzhnyi, A. G.; Timoshenkov, S. P.; Britkov, O. M.; Ilyukhina, O. V.; Myasishcheva, G. G.; Prokop'ev, E. P.; Funtikov, Yu. V.

2008-01-01

The influence of proton bombardment and metal atom impurities on the structure of quartz single crystals has been studied. The related defects have been studied using positron annihilation spectroscopy (angular correlation of positron-annihilation photons), acoustic absorption, and optical absorption measurements. It is shown that the presence of a narrow component f in the angular distribution of annihilation photons (ADAP), which is related to the formation of parapositronium, determines a high sensitivity of this method with respect to features of the crystal structure of quartz. It is established that the defectness of the structure of irradiated quartz crystals can be characterized by the ratio f/f 0 of the relative intensities of narrow components in the ADAP curves measured before (f 0 ) and after (f) irradiation. Any process leading to a decrease in the probability of positronium formation (e.g., positron loss as a result of the trapping on defects and the interaction with impurity atoms and lattice distortions) decreases the intensity of the narrow component. Based on the ADAP data, estimates of the radii and concentrations of nanodefects in quartz have been obtained and their variation upon annealing at temperatures up to T = 873 K has been studied

Quartz crystal reinforced quartz glass by spark plasma sintering

International Nuclear Information System (INIS)

Torikai, D.; Barazani, B.; Ono, E.; Santos, M.F.M.; Suzuki, C.K.

2011-01-01

The Spark Plasma Sintering presents fast processing time when compared to conventional sintering techniques. This allows to control the grain growth during sintering as well as the diffusion rate of a multi-material compounds, and make possible obtainment of functionally graded materials and nanostructured compounds. Powders of high purity silica glass and crystalline silica were sintered in a SPS equipment at temperatures around 1350° C, i.e., above the softening temperature of silica glass and below the melting temperature of quartz crystal. As a result, glass ceramics with pure silica glass matrix reinforced with crystalline alpha-quartz grains were fabricated at almost any desired range of composition, as well as controlled size of the crystalline reinforcement. X-ray diffraction and density measurements showed the possibility to manufacture a well controlled density and crystallinity glass-ceramic materials. (author)

Additive manufacturing of transparent fused quartz

Science.gov (United States)

Luo, Junjie; Hostetler, John M.; Gilbert, Luke; Goldstein, Jonathan T.; Urbas, Augustine M.; Bristow, Douglas A.; Landers, Robert G.; Kinzel, Edward C.

2018-04-01

This paper investigates a filament-fed process for additive manufacturing (AM) of fused quartz. Glasses such as fused quartz have significant scientific and engineering applications, which include optics, communications, electronics, and hermetic seals. AM has several attractive benefits such as increased design freedom, faster prototyping, and lower processing costs for small production volumes. However, current research into glass AM has focused primarily on nonoptical applications. Fused quartz is studied here because of its desirability for use in high-quality optics due to its high transmissivity and thermal stability. Fused quartz filaments are fed into a CO2 laser-generated molten region, smoothly depositing material onto the workpiece. Spectroscopy and pyrometry are used to measure the thermal radiation incandescently emitted from the molten region. The effects of the laser power and scan speed are determined by measuring the morphology of single tracks. Thin walls are printed to study the effects of layer-to-layer height. This information is used to deposit solid pieces including a cylindrical-convex shape capable of focusing visible light. The transmittance and index homogeneity of the printed fused quartz are measured. These results show that the filament-fed process has the potential to print transmissive optics.

Determination of halogens by flame emission of metal halogenides

International Nuclear Information System (INIS)

Henrion, G.; Marquardt, D.; Stoecker, B.

1979-01-01

The A-B systems InF, InCl, InBr, and InI have been excited by laminar H 2 -N 2 flames in order to dermine individual halogens or their mixtures qualitatively or quantitatively. In optimizing the fuel gas composition two different behavior patterns have been found for band intensities, which are correlated with binding energies of InX (X = halogen). The low temperature of the flame leads to complicated matrix effects which first of all result from effects on excitation and from competitive reactions. In general, cations cause a decreased intensity. Therefore, salts have to be converted into hydrohalide acids by ion exchange. Qualitative determinations of individual halogens are possible at a 500 to 50,000fold excess of the others, whereas quantitative determinations can be performed at a 100 to 5,000fold excess in 10 -4 molar solutions with errors of 2 to 10 per cent. (author)

High-temperature peaks of thermostimulated luminescence in the ammonium halogens

International Nuclear Information System (INIS)

Kim, L.M.; Musenova, Eh.K.; Mukhamedrakhimov, K.U.

2003-01-01

The ammonium halogen crystals (AHC) are the close analogs of the alkali halogen crystals by the type of chemical bonds and crystal lattice structure. The ammonium halogen after irradiation by X-rays within 80-300 K range have two peaks of thermo-stimulation luminescence. Its maximums in dependence of anions type are in the 110-120 K and 170-180 K ranges. The first range is related with activation of auto-localized holes migration, and the second one - with the NH 3 + defects decay. Experimentally is established, that the pure ammonium halogens have memory about the previous irradiation at heating up to 300 K. After repeat irradiation the recombination luminescence high-temperature peak's shoulder is appearing. The second luminescence peak's shoulder revealing does not depend on the impurity center nature. It is known, that in the AHC there is the next thermo-stimulation luminescence peak within 340-360 K. The thermal annealing of this peak leads to the memory effect disappearance. So, the observing phenomenon is related with own defect of the matrix in the cation sublattice. Experimentally is established, that at a room temperature the AHC memorizing about previous irradiation during 20 h

Retention efficiencies of halogenated and non-halogenated hydrocarbons in selected wetland ecosystem in Lake Victoria Basin

Directory of Open Access Journals (Sweden)

Shadrack Mule

2015-06-01

Full Text Available The determination of retention efficiencies of halogenated and non-halogenated hydrocarbon in selected wetland ecosystems in Lake Victoria basin was carried out. Qualitative and quantitative determination of the presence of residual hydrocarbons in Kigwal/Kimondi, Nyando and Nzoia wetland ecosystems using Gas Chromatography - Mass Spectrometer (GC-MS instrument indicated the presence of residual organochlorines, organophosphorus, carbamates and synthetic pyrethroid hydrocarbons in water, sediment and plant materials. In order to compare the retention efficiencies of the wetlands, the wetland ecosystems were divided into three different sections, namely: inlet, mid and outlet. Calculations of mass balances of residual halogenated and non-halogenated hydrocarbons at the respective sections was done taking into account the partition of the studied compounds in samples of water, sediments and papyrus reed plant materials and analyzed using validated Gas Chromatography - Mass Spectrometer (GC-MS method. From the analysis, several residual hydrocarbons namely: bendiocarb, benzene hexachloride (BHC, carbaryl, cypermethrin, decis, deltamethrin, diazinon, dieldrin, DDT, DDD, DDE, malathion, propoxur, sumithion, 5-phenylrhodanine, 1,3,5-trichlorobenzene, 1-(2-phenoxybenzylhydrazine were detected and quantified. The levels of the selected residual hydrocarbons in water samples were used to calculate the retention efficiencies of a specific hydrocarbon and the values recorded. Generally, River Nyando wetland recorded mean percentage retention efficiencies of 76 and 94% for dry and rainy seasons respectively; Kigwal/Kimondi wetland had seasonal mean percentage retention efficiencies of 63 to 78%. River Nzoia also had calculated seasonal mean percentage retention efficiencies of between 56 to 88%. Dry season had lower mean percentages retention efficiencies as compared to rainy season in the three wetlands of interest during the period of study. The study

Halogens determination in vegetable NBS standard reference materials

International Nuclear Information System (INIS)

Stella, R.; Genova, N.; Di Casa, M.

1977-01-01

Levels of all four halogens in Orchard Leaves, Pine Needles and Tomato Leaves NBS reference standards were determined. For fluorine a spiking isotope dilution method was used followed by HF absorption on glass beads. Instrumental nuclear activation analysis was adopted for chlorine and bromine determination. Radiochemical separation by a distillation procedure was necessary for iodine nuclear activation analysis after irradiation. Activation parameters of Cl, Br and I are reported. Results of five determinations for each halogen in Orchard Leaves, Pine Needles and Tomato Leaves NBS Standard Materials and Standard deviations of the mean are reported. (T.I.)

Quartz-Enhanced Photoacoustic Spectroscopy: A Review

Science.gov (United States)

Patimisco, Pietro; Scamarcio, Gaetano; Tittel, Frank K.; Spagnolo, Vincenzo

2014-01-01

A detailed review on the development of quartz-enhanced photoacoustic sensors (QEPAS) for the sensitive and selective quantification of molecular trace gas species with resolved spectroscopic features is reported. The basis of the QEPAS technique, the technology available to support this field in terms of key components, such as light sources and quartz-tuning forks and the recent developments in detection methods and performance limitations will be discussed. Furthermore, different experimental QEPAS methods such as: on-beam and off-beam QEPAS, quartz-enhanced evanescent wave photoacoustic detection, modulation-cancellation approach and mid-IR single mode fiber-coupled sensor systems will be reviewed and analysed. A QEPAS sensor operating in the THz range, employing a custom-made quartz-tuning fork and a THz quantum cascade laser will be also described. Finally, we evaluated data reported during the past decade and draw relevant and useful conclusions from this analysis. PMID:24686729

Quartz-Enhanced Photoacoustic Spectroscopy: A Review

Directory of Open Access Journals (Sweden)

Pietro Patimisco

2014-03-01

Full Text Available A detailed review on the development of quartz-enhanced photoacoustic sensors (QEPAS for the sensitive and selective quantification of molecular trace gas species with resolved spectroscopic features is reported. The basis of the QEPAS technique, the technology available to support this field in terms of key components, such as light sources and quartz-tuning forks and the recent developments in detection methods and performance limitations will be discussed. Furthermore, different experimental QEPAS methods such as: on-beam and off-beam QEPAS, quartz-enhanced evanescent wave photoacoustic detection, modulation-cancellation approach and mid-IR single mode fiber-coupled sensor systems will be reviewed and analysed. A QEPAS sensor operating in the THz range, employing a custom-made quartz-tuning fork and a THz quantum cascade laser will be also described. Finally, we evaluated data reported during the past decade and draw relevant and useful conclusions from this analysis.

Aberrant thermoluminescence dates obtained from primary volcanic quartz

International Nuclear Information System (INIS)

Guerin, Gilles; Samper, Agnes

2007-01-01

This study deals with the dating by thermoluminescence (TL) of quartz from six volcanic formations of the Saint Lucia Island (Lesser Antilles Arc). Quartz microcrystals up to one millimetre in size were extracted from dacites and pumice flows and prepared in a way similar to the well-known inclusion technique. The TL properties of these quartz were used to estimate apparent palaeodoses using the multi-aliquot protocol. The quartz TL was studied in three different spectral domains: red, green and ultraviolet/blue. The calculated annual dose-rates yielded a set of 18 age-estimates. For some samples complementary dates were obtained using high temperature TL (HTTL) of plagioclase feldspars. These latter dates combined with previously determined radiocarbon and unspiked K-Ar dates were used to explore the validity of ages computed from the TL of quartz. Individual values for quartz appear to be scattered and do not match ages deduced from 14 C, unspiked K-Ar or HTTL on plagioclase dates. These results indicate that when conventional TL methodologies derived from the inclusion method are applied to volcanic quartz major dating problems are to be expected

Aberrant thermoluminescence dates obtained from primary volcanic quartz

Energy Technology Data Exchange (ETDEWEB)

Guerin, Gilles [Laboratoire des Sciences du Climat et de l' Environnement, CEA-CNRS, avenue de la Terrasse, 91191 Gif-sur-Yvette (France)], E-mail: gilles.guerin@u-psud.fr; Samper, Agnes [Laboratoire de geochronologie multitechnique (UPS-IPGP), Universite de Paris-Sud Orsay, 91405 Orsay Cedex (France)

2007-10-15

This study deals with the dating by thermoluminescence (TL) of quartz from six volcanic formations of the Saint Lucia Island (Lesser Antilles Arc). Quartz microcrystals up to one millimetre in size were extracted from dacites and pumice flows and prepared in a way similar to the well-known inclusion technique. The TL properties of these quartz were used to estimate apparent palaeodoses using the multi-aliquot protocol. The quartz TL was studied in three different spectral domains: red, green and ultraviolet/blue. The calculated annual dose-rates yielded a set of 18 age-estimates. For some samples complementary dates were obtained using high temperature TL (HTTL) of plagioclase feldspars. These latter dates combined with previously determined radiocarbon and unspiked K-Ar dates were used to explore the validity of ages computed from the TL of quartz. Individual values for quartz appear to be scattered and do not match ages deduced from {sup 14}C, unspiked K-Ar or HTTL on plagioclase dates. These results indicate that when conventional TL methodologies derived from the inclusion method are applied to volcanic quartz major dating problems are to be expected.

Halogen Bonding Involving CO and CS with Carbon as the Electron Donor

Directory of Open Access Journals (Sweden)

Janet E. Del Bene

2017-11-01

Full Text Available MP2/aug’-cc-pVTZ calculations have been carried out to investigate the halogen-bonded complexes formed when CO and CS act as electron-pair donors through C to ClF, ClNC, ClCl, ClOH, ClCN, ClCCH, and ClNH2. CO forms only complexes stabilized by traditional halogen bonds, and all ClY molecules form traditional halogen-bonded complexes with SC, except ClF which forms only an ion-pair complex. Ion-pair complexes are also found on the SC:ClNC and SC:ClCl surfaces. SC:ClY complexes stabilized by traditional halogen bonds have greater binding energies than the corresponding OC:ClY complexes. The largest binding energies are found for the ion-pair SC–Cl+:−Y complexes. The transition structures which connect the complex and the ion pair on SC:ClNC and SC:ClCl potential surfaces provide the barriers for inter-converting these structures. Charge-transfer from the lone pair on C to the σ-hole on Cl is the primary charge-transfer interaction stabilizing OC:ClY and SC:ClY complexes with traditional halogen bonds. A secondary charge-transfer occurs from the lone pairs on Cl to the in-plane and out-of-plane π antibonding orbitals of ClY. This secondary interaction assumes increased importance in the SC:ClNH2 complex, and is a factor leading to its unusual structure. C–O and C–S stretching frequencies and 13C chemical shieldings increase upon complex formation with ClY molecules. These two spectroscopic properties clearly differentiate between SC:ClY complexes and SC–Cl+:−Y ion pairs. Spin–spin coupling constants 1xJ(C–Cl for OC:ClY complexes increase with decreasing distance. As a function of the C–Cl distance, 1xJ(C–Cl and 1J(C–Cl provide a fingerprint of the evolution of the halogen bond from a traditional halogen bond in the complexes, to a chlorine-shared halogen bond in the transition structures, to a covalent bond in the ion pairs.

A Survey of Electron Impact Cross-Sections for Halogens and Halogen Compounds of Interest to Plasma Processing

Science.gov (United States)

Sharma, S. P.; Rao, M. V. V. S.; Arnold, James O. (Technical Monitor)

1998-01-01

Published electron impact cross section data on halogens Cl2, F2, and halogen containing compounds such as Cx Fy, HCl, Cx Cly Fz are reviewed and critically evaluated based on the information provided by various researchers. The present work reports data on electron impact excitation, ionization, dissociation, electron attachment, electron detachment, and photo detachment. Elastic scattering cross sections and data on bulk properties such as diffusion coefficients in various background gases are also evaluated. Since some of the cross sectional data is derived from indirect measurements such as drift velocity, care has been taken to reconcile the differences among the reported data with due attention to the measurement technique. In conclusion, the processes with no or very limited amount of data and questionable set of data are identified and recommendation for further research direction is made.

Estrogenicity of halogenated bisphenol A: in vitro and in silico investigations.

Science.gov (United States)

Zhang, Jie; Li, Tiezhu; Wang, Tuoyi; Yuan, Cuiping; Zhong, Shuning; Guan, Tianzhu; Li, Zhuolin; Wang, Yongzhi; Yu, Hansong; Luo, Quan; Wang, Yongjun; Zhang, Tiehua

2018-03-01

The binding interactions of bisphenol A (BPA) and its halogenated derivatives (halogenated BPAs) to human estrogen receptor α ligand binding domain (hERα-LBD) was investigated using a combined in vitro and in silico approach. First, the recombinant hERα-LBD was prepared as a soluble protein in Escherichia coli BL21(DE3)pLysS. A native fluorescent phytoestrogen, coumestrol, was employed as tracer for the fluorescence polarization assay. The results of the in vitro binding assay showed that bisphenol compounds could bind to hERα-LBD as the affinity ligands. All the tested halogenated BPAs exhibited weaker receptor binding than BPA, which might be explained by the steric effect of substituents. Molecular docking studies elucidated that the halogenated BPAs adopted different conformations in the flexible hydrophobic ligand binding pocket (LBP), which is mainly dependent on their distinct halogenation patterns. The compounds with halogen substituents on the phenolic rings and on the bridging alkyl moiety acted as agonists and antagonists for hERα, respectively. Interestingly, all the compounds in the agonist conformation of hERα formed a hydrogen bond with His524, while the compounds in the antagonist conformation formed a hydrogen bond with Thr347. These docking results suggested a pivotal role of His524/Thr347 in maintaining the hERα structure in the biologically active agonist/antagonist conformation. Comparison of the calculated binding energies vs. experimental binding affinities yielded a good correlation, which might be applicable for the structure-based design of novel bisphenol compounds with reduced toxicities and for environmental risk assessment. In addition, based on hERα-LBD as a recognition element, the proposed fluorescence polarization assay may offer an alternative to chromatographic techniques for the multi-residue determination of bisphenol compounds.

Halogen degassing during ascent and eruption of water-poor basaltic magma

Science.gov (United States)

Edmonds, M.; Gerlach, T.M.; Herd, Richard A.

2009-01-01

A study of volcanic gas composition and matrix glass volatile concentrations has allowed a model for halogen degassing to be formulated for K??lauea Volcano, Hawai'i. Volcanic gases emitted during 2004-2005 were characterised by a molar SO2/HCl of 10-64, with a mean of 33; and a molar HF/HCl of 0-5, with a mean of 1.0 (from approximately 2500 measurements). The HF/HCl ratio was more variable than the SO2/HCl ratio, and the two correlate weakly. Variations in ratio took place over rapid timescales (seconds). Matrix glasses of Pele's tears erupted in 2006 have a mean S, Cl and F content of 67, 85 and 173??ppm respectively, but are associated with a large range in S/F. A model is developed that describes the open system degassing of halogens from parental magmas, using the glass data from this study, previously published results and parameterisation of sulphur degassing from previous work. The results illustrate that halogen degassing takes place at pressures of < 1??MPa, equivalent to < ~ 35??m in the conduit. Fluid-melt partition coefficients for Cl and F are low (< 1.5); F only degasses appreciably at < 0.1??MPa above atmospheric pressure, virtually at the top of the magma column. This model reproduces the volcanic gas data and other observations of volcanic activity well and is consistent with other studies of halogen degassing from basaltic magmas. The model suggests that variation in volcanic gas halogen ratios is caused by exsolution and gas-melt separation at low pressures in the conduit. There is no evidence that either diffusive fractionation or near-vent chemical reactions involving halogens is important in the system, although these processes cannot be ruled out. The fluxes of HCl and HF from K??lauea during 2004-5 were ~ 25 and 12??t/d respectively. ?? 2008 Elsevier B.V.

Production of quartz plates for CMS-CASTOR Experiment

CERN Document Server

Adiguzel, Aytul; Ayhan, Aydin; Bakirci, Mustafa Numan; Basegmez, Suzan; Beaumont, Willem; Borras, Kerstin; Campbell, Alan; De Paula Carvalho, W; Çerçi, Salim; De Jesus Damiao, Dilson; Dogangün, O; Dumanoglu, Isa; d'Enterria, David; Erchov, Y; Eskut, Eda; Figueiredo, D; Girgis, Semiray; Göttlicher, P; Gouskos, Loukas; Gurpinar, Emine; Hos, Ilknur; Katkov, Igor; Katsas, Panagiotis; Khein, Lev; Knutsson, Albert; Kuznetsov, Andrey; Lebeau, Michel; Van Mechelen, Pierre; Muhl, Carsten; Musienko, Yuri; Ochesanu, Silvia; Onengüt, G; Onengut, G Jr; Ozdemir, Kadri; Panagiotou, Apostolos; Polatoz, A; Ripert, Marion; Shileev, K; Sogut, Kenan; Tiflov, B TaliV; Kayis-Topaksu, A; Uzun, Dilber

2008-01-01

Light transmission rate performance of $102$ irradiated quartz samples was measured to select the best quartz plates for CMS-CASTOR calorimeter. All the produced quartz plates were originally used in a previous CERN experiment, DELPHI. Three different doses of $^{60}$Co source were used with the collaboration of PSI (Paul Scherrer Institute, Villigen PSI, Switzerland.) to study the transmission rate performance of the quartz samples after irradiation for different incident light, ranging from $250$ to $700$ nm in $5$ nm increasing steps. All samples show different decrease in the rate with wavelength for different doses. Three different steps were followed before irradiation to find out the best way of cleaning the original DELPHI Cu/Cr tracks on the samples. Results of these measurements presented here correspond to the quartz plates that will be used in one hadronic sector of CASTOR calorimeter until end of 2008. For the full calorimeter new quartz plates will be installed. We also present the light transmi...

Mechanical and optical nanodevices in single-crystal quartz

Science.gov (United States)

Sohn, Young-Ik; Miller, Rachel; Venkataraman, Vivek; Lončar, Marko

2017-12-01

Single-crystal α-quartz, one of the most widely used piezoelectric materials, has enabled a wide range of timing applications. Owing to the fact that an integrated thin-film based quartz platform is not available, most of these applications rely on macroscopic, bulk crystal-based devices. Here, we show that the Faraday cage angled-etching technique can be used to realize nanoscale electromechanical and photonic devices in quartz. Using this approach, we demonstrate quartz nanomechanical cantilevers and ring resonators featuring Qs of 4900 and 8900, respectively.

A High Sensitivity Preamplifier for Quartz Tuning Forks in QEPAS (Quartz Enhanced PhotoAcoustic Spectroscopy Applications

Directory of Open Access Journals (Sweden)

Tomasz Starecki

2017-11-01

Full Text Available All the preamplifiers dedicated for Quartz Enhanced PhotoAcoustic Spectroscopy (QEPAS applications that have so far been reported in the literature have been based on operational amplifiers working in transimpedance configurations. Taking into consideration that QEPAS sensors are based on quartz tuning forks, and that quartz has a relatively high voltage constant and relatively low charge constant, it seems that a transimpedance amplifier is not an optimal solution. This paper describes the design of a quartz QEPAS sensor preamplifier, implemented with voltage amplifier configuration. Discussion of an electrical model of the circuit and preliminary measurements are presented. Both theoretical analysis and experiments show that use of the voltage configuration allows for a substantial increase of the output signal in comparison to the transimpedance circuit with the same tuning fork working in identical conditions. Assuming that the sensitivity of the QEPAS technique depends directly on the properties of the preamplifier, use of the voltage amplifier configuration should result in an increase of QEPAS sensitivity by one to two orders of magnitude.

A High Sensitivity Preamplifier for Quartz Tuning Forks in QEPAS (Quartz Enhanced PhotoAcoustic Spectroscopy) Applications.

Science.gov (United States)

Starecki, Tomasz; Wieczorek, Piotr Z

2017-11-03

All the preamplifiers dedicated for Quartz Enhanced PhotoAcoustic Spectroscopy (QEPAS) applications that have so far been reported in the literature have been based on operational amplifiers working in transimpedance configurations. Taking into consideration that QEPAS sensors are based on quartz tuning forks, and that quartz has a relatively high voltage constant and relatively low charge constant, it seems that a transimpedance amplifier is not an optimal solution. This paper describes the design of a quartz QEPAS sensor preamplifier, implemented with voltage amplifier configuration. Discussion of an electrical model of the circuit and preliminary measurements are presented. Both theoretical analysis and experiments show that use of the voltage configuration allows for a substantial increase of the output signal in comparison to the transimpedance circuit with the same tuning fork working in identical conditions. Assuming that the sensitivity of the QEPAS technique depends directly on the properties of the preamplifier, use of the voltage amplifier configuration should result in an increase of QEPAS sensitivity by one to two orders of magnitude.

Process for removing halogenated aliphatic and aromatic compounds from petroleum products

Science.gov (United States)

Googin, J.M.; Napier, J.M.; Travaglini, M.A.

1983-09-20

A process is described for removing halogenated aliphatic and aromatic compounds, e.g., polychlorinated biphenyls, from petroleum products by solvent extraction. The halogenated aliphatic and aromatic compounds are extracted from a petroleum product into a polar solvent by contacting the petroleum product with the polar solvent. The polar solvent is characterized by a high solubility for the extracted halogenated aliphatic and aromatic compounds, a low solubility for the petroleum product and considerable solvent power for polyhydroxy compound. The preferred polar solvent is dimethylformamide. A miscible compound, such as, water or a polyhydroxy compound, is added to the polar extraction solvent to increase the polarity of the polar extraction solvent. The halogenated aliphatic and aromatic compounds are extracted from the highly-polarized mixture of water or polyhydroxy compound and polar extraction solvent into a low polar or nonpolar solvent by contacting the water or polyhydroxy compound-polar solvent mixture with the low polar or nonpolar solvent. The halogenated aliphatic and aromatic compounds and the low polar or nonpolar solvent are separated by physical means, e.g., vacuum evaporation. The polar and nonpolar solvents are recovered from recycling. The process can easily be designed for continuous operation. Advantages of the process include that the polar solvent and a major portion of the nonpolar solvent can be recycled, the petroleum products are reclaimable and the cost for disposing of waste containing polychlorinated biphenyls is significantly reduced. 1 fig.

Quartz exposure and increased respiratory symptoms among coal ...

African Journals Online (AJOL)

Quartz has been an inevitable composition of different type of coal mined. The quartz exposures among coalmine workers has been attributed to activities such as cutting the adjacent rock, the roof, the floor and the intrusions. Objective: The aim of the study is to determine the associations between quartz exposures and ...

Risk assessment for halogenated solvents

International Nuclear Information System (INIS)

Travis, C.C.

1988-01-01

A recent development in the cancer risk area is the advent of biologically based pharmacokinetic and pharmacodynamic models. These models allow for the incorporation of biological and mechanistic data into the risk assessment process. These advances will not only improve the risk assessment process for halogenated solvents but will stimulate and guide basic research in the biological area

Development of halogen-free cables for nuclear power plants

International Nuclear Information System (INIS)

Yamamoto, Mitsuo; Ito, Kazumi; Yaji, Takeo; Yoshida, Shin; Sakurai, Takako; Matsushita, Shigetoshi.

1990-01-01

On the occasion where serious fire accidents were experienced in the past, the need for making flame-retardant wire and cable incombustible took place and has since been generalizing. Various sorts of flame-retardant cables have already been developed and been actually used. From the viewpoint of avoiding the interference with the evacuation and fire-fighting activity in case of fire or the secondary accidents such as corrosion of the distributing panel, etc., the demand for non-halogen flame-retardant cable has rapidly been increasing in recent years in some fields of general industries, because this specific cable would generate the least amount of toxic smoke or corrosive gas even when it should burn. Similar demand has been increasing also for the cable used for nuclear power plants. In this field, earnest desire has been made for the development of non-halogen flame-retardant cable having specific environmental resistance specially required at nuclear power plants in addition to the properties and capacities required in general industries. The authors have continued examinations on the anti-environmental properties of the materials for cable such as long heat resistance, radiation resistance, steam resistance and succeeded in completing various sorts of non-halogen flame-retardant cable for nuclear power plants. In this report, we will introduce various features of the cable we have developed this time as well as the long-term reliability of non-halogen flame-retardant materials. (author)

Microwave GaAs Integrated Circuits On Quartz Substrates

Science.gov (United States)

Siegel, Peter H.; Mehdi, Imran; Wilson, Barbara

1994-01-01

Integrated circuits for use in detecting electromagnetic radiation at millimeter and submillimeter wavelengths constructed by bonding GaAs-based integrated circuits onto quartz-substrate-based stripline circuits. Approach offers combined advantages of high-speed semiconductor active devices made only on epitaxially deposited GaAs substrates with low-dielectric-loss, mechanically rugged quartz substrates. Other potential applications include integration of antenna elements with active devices, using carrier substrates other than quartz to meet particular requirements using lifted-off GaAs layer in membrane configuration with quartz substrate supporting edges only, and using lift-off technique to fabricate ultrathin discrete devices diced separately and inserted into predefined larger circuits. In different device concept, quartz substrate utilized as transparent support for GaAs devices excited from back side by optical radiation.

Experimental study of quartz inclusions in garnet at pressures up to 3.0 GPa: evaluating validity of the quartz-in-garnet inclusion elastic thermobarometer

Science.gov (United States)

Thomas, Jay B.; Spear, Frank S.

2018-05-01

Garnet crystals with quartz inclusions were hydrothermally crystallized from oxide starting materials in piston-cylinder apparatuses at pressures from 0.5 to 3 GPa and temperatures ranging from 700 to 800 °C to study how entrapment conditions affect remnant pressures of quartz inclusions used for quartz-in-garnet (QuiG) elastic thermobarometry. Systematic changes of the 128, 206 and 464 cm-1 Raman band frequencies of quartz were used to determine pressures of quartz inclusions in garnet using Raman spectroscopy calibrations that describe the P-T dependencies of Raman band shifts for quartz under hydrostatic pressure. Within analytical uncertainties, inclusion pressures calculated for each of the three Raman band frequencies are equivalent, which suggests that non-hydrostatic stress effects caused by elastic anisotropy in quartz are smaller than measurement errors. The experimental quartz inclusions have pressures ranging from - 0.351 to 1.247 GPa that span the range of values observed for quartz inclusions in garnets from natural rocks. Quartz inclusion pressures were used to model P-T conditions at which the inclusions could have been trapped. The accuracy of QuiG thermobarometry was evaluated by considering the differences between pressures measured during experiments and pressures calculated using published equation of state parameters for quartz and garnet. Our experimental results demonstrate that Raman measurements performed at room temperature can be used without corrections to estimate garnet crystallization pressures. Calculated entrapment pressures for quartz inclusions in garnet are less than 10% different from pressures measured during the experiments. Because the method is simple to apply with reasonable accuracy, we expect widespread usage of QuiG thermobarometry to estimate crystallization conditions for garnet-bearing silicic rocks.

Characterization of color centers in quartz induced by gamma irradiation

International Nuclear Information System (INIS)

Guttler, Rainer A.S.

2009-01-01

The availability of gamma ray irradiators in Brazil increased the possibilities of treatments of gemstones for color enhancements. One of the minerals with a very high potential of these treatments is quartz, a very widespread mineral with much colored commercial varieties. Quartz occurs in Brazil mainly in two geological environments, called pegmatitic and hydrothermal. The detailed mechanism of color center formation of these two types of quartz will be investigated by spectroscopic and chemical analysis. Until yet, it can be shown that due to chemical differences of the nature of mineral forming fluids, the two types behave differently. All quartzes contain mainly traces of Iron, Aluminum, Lithium and some amounts of Water. The quartz of hydrothermal origin incorporated much structurally bound water, and despite some similarities with the chemical composition of pegmatitic quartz, this high water content is the reason for the formation of Silanol radicals, giving the green color to the quartz. The main difference in chemical composition of pegmatitic quartz is the presence of higher amounts of Al and Li , responsible for the brownish and yellowish colors formed by irradiation. Since each pegmatite is different, the quartz will behave differently. This explains the formation of the famous 'Green Gold' of quartz from Sao Jose da Safira , and the more yellowish, Citrine type, color of quartz from the Coluna deposit, near Itamarandiba, Minas Gerais. (author)

Characterization of color centers in quartz induced by gamma irradiation

Energy Technology Data Exchange (ETDEWEB)

Guttler, Rainer A.S., E-mail: rainersg@usp.b [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Geociencias; Enokihara, Cyro T.; Rela, Paulo R., E-mail: prela@ipen.b, E-mail: cteiti@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2009-07-01

The availability of gamma ray irradiators in Brazil increased the possibilities of treatments of gemstones for color enhancements. One of the minerals with a very high potential of these treatments is quartz, a very widespread mineral with much colored commercial varieties. Quartz occurs in Brazil mainly in two geological environments, called pegmatitic and hydrothermal. The detailed mechanism of color center formation of these two types of quartz will be investigated by spectroscopic and chemical analysis. Until yet, it can be shown that due to chemical differences of the nature of mineral forming fluids, the two types behave differently. All quartzes contain mainly traces of Iron, Aluminum, Lithium and some amounts of Water. The quartz of hydrothermal origin incorporated much structurally bound water, and despite some similarities with the chemical composition of pegmatitic quartz, this high water content is the reason for the formation of Silanol radicals, giving the green color to the quartz. The main difference in chemical composition of pegmatitic quartz is the presence of higher amounts of Al and Li , responsible for the brownish and yellowish colors formed by irradiation. Since each pegmatite is different, the quartz will behave differently. This explains the formation of the famous 'Green Gold' of quartz from Sao Jose da Safira , and the more yellowish, Citrine type, color of quartz from the Coluna deposit, near Itamarandiba, Minas Gerais. (author)

Surface complexation modelling: Experiments on sorption of nickel on quartz, goethite and kaolinite and preliminary tests on sorption of thorium on quartz

Energy Technology Data Exchange (ETDEWEB)

Puukko, E.; Hakanen, M. [Univ. of Helsinki (Finland). Dept. of Chemistry. Lab. of Radiochemistry

1997-09-01

The aim of the work was to study the sorption behaviour of Ni on quartz, goethite and kaolinite at different pH levels and in different electrolyte solutions of different strength. In addition preliminary experiments were made to study the sorption of thorium on quartz. The MUS quartz and Nilsiae quartz were analysed for MnO{sub 2} by neutron activation analysis (NAA) and the experimental results were modelled with the HYDRAQL computer model. 9 refs.

Geology and geochemistry of giant quartz veins from the ...

Indian Academy of Sciences (India)

Numerous younger thin quartz veins with somewhat similar orientation cut across the giant quartz .... Angular fragments of quartz are set in ... places along grain boundaries. ... Oxide values are in wt%, and trace element concentrations are.

FIELD SCREENING FOR HALOGENATED VOLATILE ORGANIC COMPOUNDS

Energy Technology Data Exchange (ETDEWEB)

John F. Schabron; Joseph F. Rovani, Jr.; Theresa M. Bomstad

2003-07-01

Western Research Institute (WRI) is continuing work toward the development of new screening methodology and a test kit to measure halogenated volatile organic compounds (VOCs) in the field. Heated diode and corona discharge sensors are commonly used to detect leaks of refrigerants from air conditioners, freezers, and refrigerators. They are both selective to the presence of halogens. In prior work, the devices were tested for response to carbon tetrachloride, heptane, toluene, and water vapors. In the current work, sensor response was evaluated with sixteen halogenated VOCs relative to carbon tetrachloride. The results show that the response of the various chlorinated VOCs is within an order of magnitude of the response to carbon tetrachloride for each of the sensors. Thus, for field screening a single response factor can be used. Both types of leak detectors are being further modified to provide an on-board LCD signal readout, which is related to VOC concentration. The units will be fully portable and will operate with 115-V line or battery power. Signal background, noise level, and response data on the Bacharach heated diode detector and the TIF corona discharge detector show that when the response curves are plotted against the log of concentration, the plot is linear to the upper limit for the particular unit, with some curvature at lower levels. When response is plotted directly against concentration, the response is linear at the low end and is curved at the high end. The dynamic ranges for carbon tetrachloride of the two devices from the lower detection limit (S/N=2) to signal saturation are 4-850 vapor parts per million (vppm) for the corona discharge unit and 0.01-70 vppm for the heated diode unit. Additional circuit modifications are being made to lower the detection limit and increase the dynamic response range of the corona discharge unit. The results indicate that both devices show potential utility for future analytical method development work toward

Identifying well-bleached quartz using the different bleaching rates of quartz and feldspar luminescence signals

DEFF Research Database (Denmark)

Murray, A.S.; Thomsen, Kristina Jørkov; Masuda, N.

2012-01-01

When dating older sedimentary deposits using quartz, there are no unambiguous methods for identifying the presence of incomplete bleaching. Current statistical analysis of dose distributions depends entirely on the assumption that incomplete bleaching and mixing are the main causes of any excess...... dispersion in the distribution; the only existing way to test this assumption is using independent age control. Here we suggest a new approach to this question, based on the differential bleaching rates of quartz and feldspar luminescence signals. We first present data that confirm the differences...... in relative bleaching rates of quartz optically stimulated luminescence (OSL) and feldspar luminescence stimulated at 50 °C by infrared light (IR50) and feldspar luminescence stimulated at 290 °C by infrared light after a stimulation at 50 °C (pIRIR290), and use recently deposited samples to determine...

Halogenation of Hydraulic Fracturing Additives in the Shale Well Parameter Space

Science.gov (United States)

Sumner, A. J.; Plata, D.

2017-12-01

Horizontal Drilling and Hydraulic fracturing (HDHF) involves the deep-well injection of a `fracking fluid' composed of diverse and numerous chemical additives designed to facilitate the release and collection of natural gas from shale plays. The potential impacts of HDHF operations on water resources and ecosystems are numerous, and analyses of flowback samples revealed organic compounds from both geogenic and anthropogenic sources. Furthermore, halogenated chemicals were also detected, and these compounds are rarely disclosed, suggesting the in situ halogenation of reactive additives. To test this transformation hypothesis, we designed and operated a novel high pressure and temperature reactor system to simulate the shale well parameter space and investigate the chemical reactivity of twelve commonly disclosed and functionally diverse HDHF additives. Early results revealed an unanticipated halogenation pathway of α-β unsaturated aldehyde, Cinnamaldehyde, in the presence of oxidant and concentrated brine. Ongoing experiments over a range of parameters informed a proposed mechanism, demonstrating the role of various shale-well specific parameters in enabling the demonstrated halogenation pathway. Ultimately, these results will inform a host of potentially unintended interactions of HDHF additives during the extreme conditions down-bore of a shale well during HDHF activities.

Errors in short circuit measurements due to spectral mismatch between sunlight and solar simulators

Science.gov (United States)

Curtis, H. B.

1976-01-01

Errors in short circuit current measurement were calculated for a variety of spectral mismatch conditions. The differences in spectral irradiance between terrestrial sunlight and three types of solar simulator were studied, as well as the differences in spectral response between three types of reference solar cells and various test cells. The simulators considered were a short arc xenon lamp AMO sunlight simulator, an ordinary quartz halogen lamp, and an ELH-type quartz halogen lamp. Three types of solar cells studied were a silicon cell, a cadmium sulfide cell and a gallium arsenide cell.

Evaluation of remaining behavior of halogen on the fabrication of MOX pellet containing Am

International Nuclear Information System (INIS)

Ozaki, Yoko; Osaka, Masahiko; Obayashi, Hiroshi; Tanaka, Kenya

2004-11-01

It is important to limit the content of halogen elements, namely fluorine and chlorine that are sources of making cladding material corrode, in nuclear fuel from the viewpoint of quality assurance. The halogen content should be more carefully limited in the MOX fuel containing Americium (Am-MOX), which is fabricated in the Alpha-Gamma Facility (AGF) for irradiation testing to be conducted in the experimental fast reactor JOYO, because fluorine may remain in the sintered pellets owing to a formation of AmF 3 known to have a low vapor pressure and may exceeds the limit of 25 ppm. In this study, a series of experimental determination of halogen element in Am-MOX were performed by a combination method of pyrolysis and ion-chromatography for the purpose of an evaluation of behavior of remaining halogen through the sintering process. Oxygen potential, temperature and time were changed as experimental parameters and their effects on the remaining behavior of halogen were examined. It was confirmed that good pellets, which contained small amount of halogen, could be obtained by the sintering for 3 hour at 1700degC in the oxygen potential range from -520 to -390 kJ/mol. In order to analysis of fluorine chemical form in green pellet, thermal analysis was performed. AmF 3 and PuF 3 have been confirmed to remain in the green pellet. (author)

Development of Halogen-free flame-retardant cable for nuclear power plant

International Nuclear Information System (INIS)

Ishii, Nobuhisa; Morii, Akira; Fujimura, Shunichi

1992-01-01

Conventional flame-retardant cables release a large volume of corrosive and toxic gases as well as smoke while combusted. Cables covered with halogen-free flame-retardant material, containing no halogen in it, have been developed to reduce generation of such gases and smoke, and have already been used in telecommunication service, subway and shipboard applications. However, for cables for nuclear power plant, covering materials should also have radiation resistance and other properties, including long-term physical stability. We have developed halogen-free flame-retardant cables for BWR nuclear power plant with sufficient flame retardancy radiation resistance and environmental resistance including steam-exposure resistance all of which are in accordance with Japanese specifications for BWR nuclear cables and have such characteristics as low corrosiveness, low toxicity and low smoke emission. (author)

Development of halogen-free flame-retardant cable for nuclear power plant

International Nuclear Information System (INIS)

Ishii, Nobuhisa; Morii, Akira; Fujimura, Shunichi

1991-01-01

Conventional flame-retardant cables release a large amount of corrosive and toxic gases and also smoke during combustion on fire. Cables covered with halogen-free flame-retardant material, containing no halogen in it, have been developed to reduce generation of such gases and smoke, and already used in telecommunication plant, subway and shipboard applications. In the case of nuclear power plant application, cable covering materials should also have radiation resistance and other properties including long-term physical stability. We have developed halogen-free flame-retardant cables for nuclear power plant with sufficient flame retardancy, radiation resistance, and environmental resistance including steam-exposure resistance, all of which are in accordance with Japanese specifications for nuclear cables, and with characteristics as low corrosiveness, low toxicity, and low smoke evolution. (author)

Halogen Bonding from Dispersion-Corrected Density-Functional Theory: The Role of Delocalization Error.

Science.gov (United States)

Otero-de-la-Roza, A; Johnson, Erin R; DiLabio, Gino A

2014-12-09

Halogen bonds are formed when a Lewis base interacts with a halogen atom in a different molecule, which acts as an electron acceptor. Due to its charge transfer component, halogen bonding is difficult to model using many common density-functional approximations because they spuriously overstabilize halogen-bonded dimers. It has been suggested that dispersion-corrected density functionals are inadequate to describe halogen bonding. In this work, we show that the exchange-hole dipole moment (XDM) dispersion correction coupled with functionals that minimize delocalization error (for instance, BH&HLYP, but also other half-and-half functionals) accurately model halogen-bonded interactions, with average errors similar to other noncovalent dimers with less charge-transfer effects. The performance of XDM is evaluated for three previously proposed benchmarks (XB18 and XB51 by Kozuch and Martin, and the set proposed by Bauzá et al.) spanning a range of binding energies up to ∼50 kcal/mol. The good performance of BH&HLYP-XDM is comparable to M06-2X, and extends to the "extreme" cases in the Bauzá set. This set contains anionic electron donors where charge transfer occurs even at infinite separation, as well as other charge transfer dimers belonging to the pnictogen and chalcogen bonding classes. We also show that functional delocalization error results in an overly delocalized electron density and exact-exchange hole. We propose intermolecular Bader delocalization indices as an indicator of both the donor-acceptor character of an intermolecular interaction and the delocalization error coming from the underlying functional.

Symmetric and asymmetric halogen-containing metallocarboranylporphyrins and uses thereof

Science.gov (United States)

Miura, Michiko; Wu, Haitao

2013-05-21

The present invention is directed to low toxicity boronated compounds and methods for their use in the treatment, visualization, and diagnosis of tumors. More specifically, the present invention is directed to low toxicity halogenated, carborane-containing 5,10,15,20-tetraphenylporphyrin compounds and methods for their use particularly in boron neutron capture therapy (BNCT) and photodynamic therapy (PDT) for the treatment of tumors of the brain, head and neck, and surrounding tissue. The invention is also directed to using these halogenated, carborane-containing tetraphenylporphyrin compounds in methods of tumor imaging and/or diagnosis such as MRI, SPECT, or PET.

Structure-Energy Relationships of Halogen Bonds in Proteins.

Science.gov (United States)

Scholfield, Matthew R; Ford, Melissa Coates; Carlsson, Anna-Carin C; Butta, Hawera; Mehl, Ryan A; Ho, P Shing

2017-06-06

The structures and stabilities of proteins are defined by a series of weak noncovalent electrostatic, van der Waals, and hydrogen bond (HB) interactions. In this study, we have designed and engineered halogen bonds (XBs) site-specifically to study their structure-energy relationship in a model protein, T4 lysozyme. The evidence for XBs is the displacement of the aromatic side chain toward an oxygen acceptor, at distances that are equal to or less than the sums of their respective van der Waals radii, when the hydroxyl substituent of the wild-type tyrosine is replaced by a halogen. In addition, thermal melting studies show that the iodine XB rescues the stabilization energy from an otherwise destabilizing substitution (at an equivalent noninteracting site), indicating that the interaction is also present in solution. Quantum chemical calculations show that the XB complements an HB at this site and that solvent structure must also be considered in trying to design molecular interactions such as XBs into biological systems. A bromine substitution also shows displacement of the side chain, but the distances and geometries do not indicate formation of an XB. Thus, we have dissected the contributions from various noncovalent interactions of halogens introduced into proteins, to drive the application of XBs, particularly in biomolecular design.

Rational design of organic semiconductors for texture control and self-patterning on halogenated surfaces

KAUST Repository

Ward, Jeremy W.; Li, Ruipeng; Obaid, Abdulmalik; Payne, Marcia M.; Smilgies, Detlef Matthias; Anthony, John Edward; Amassian, Aram; Jurchescu, Oana D.

2014-01-01

new materials. Here, the influence of the interactions at the interface between a halogenated organic semiconductor (OSC) thin film and a halogenated self-assembled monolayer on the formation of the crystalline texture directly affecting

Red and blue colouration of thermoluminescence from natural quartz sands

Energy Technology Data Exchange (ETDEWEB)

Hashimoto, T; Hayashi, Y; Koyanagi, A; Yokosaka, K; Kimura, K

1986-01-01

Quartz extracts, from a pegmatite rock, volcanic ashes and beach sands, were exposed to X-rays or gamma-rays upto 8.8kGy. The irradiated sands were observed through a thermoluminescence colour image technique (abbreviated to TLCI by the authors) using highly sensitive colour photographic system. The quartz sands from volcanic ash layers, containing ..beta..-quartz (mineralized at high temperature), always indicate a red TLCI, whereas the quartz rocks from pegmatite origin and granite strata, containing ..cap alpha..-quartz (mineralized at low temperature), gave a typical blue TLCI, being consistent with the well known quartz TL colour. Quartz fractions from the beach sands showed a mixture of both red and blue TLCI, probably reflecting the respective mixtures of ..beta..-(in their origin) and ..cap alpha..-quartz fractions along the riverside area. The search using X-ray diffractometry and instrumental neutron activation analysis proved that the cause of distinctly different colourations was attributable to the impurity atoms: light rare earth elements (Eu and/or Sm) bringing on red TLCI, while structural defects yielding the blue TLCI).

Gamma irradiation of quartz from Pannier basin, South America

Energy Technology Data Exchange (ETDEWEB)

Enokihara, Cyro T.; Rela, Paulo R. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], E-mail: cteiti@ipen.br, E-mail: prela@ipen.br; Guttler, Rainer A.S. [Universidade de Sao Paulo (USP), SP (Brazil). Inst. de Geociencias

2007-07-01

The use of gamma radiation to induce or enhance color centers in gemstones is a widespread technique and applied worldwide on a industrial scale since at least 1970. The presence of defects and defect structures in quartz from a border region of southern Brazil and Uruguay are the reason for the creation of a new color variety of quartz called 'Prasiolite' in the gem trade. This quartz has a pleasant green color produced by gamma irradiation. The procedures of irradiation at IPEN show that the activation of these color producing defects can be monitored by detailed chemical and spectroscopic analysis. For the first time UV-VIS-NIR spectra of this new color variety of quartz are shown. They revealed special features of these quartz crystals coming from basaltic terranes of the Parana Basin. Contrary to most specimen of quartz from other parts of Brazil, they have such a high water and OH content that they resemble more chalcedony or opal, but not highly crystalline quartz specimens. The cause of the color are broken bonds of Si-OH defining the so-called dangling bonds. (author)

TL response to quartz and aluminum oxide grain for α-irradiation

International Nuclear Information System (INIS)

Pan Baolin; Wei Mingjian; Li Dongxu; Liu Zhaowen; Liu Chao; Zhao Shiyuan

2009-01-01

Thermoluminescence (TL) response for an α-ray irradiation system ( 241 Am) was examined with quartz grains of 11-40 μm. Quartz grains of different sizes, i.e. 137 Cs), before they were irradiated to different doses by the α-ray irradiation system. TL response to the quartz grain samples was measured. TL response of the quartz grains smaller than 4 μm and 11-40 μm to α-ray irradiation is the best, as the α-rays cannot penetrate quartz larger than 40 μm. The TL response characteristic is related with quartz grain surface area. TL responses to α-irradiation of 11-40 μm quartz and aluminum oxide grains were compared. The α-irradiation TL response of aluminum oxide (330 degree C) is better than the quartz (375 degree C). (authors)

Selective Nitrate Recognition by a Halogen-Bonding Four-Station [3]Rotaxane Molecular Shuttle.

Science.gov (United States)

Barendt, Timothy A; Docker, Andrew; Marques, Igor; Félix, Vítor; Beer, Paul D

2016-09-05

The synthesis of the first halogen bonding [3]rotaxane host system containing a bis-iodo triazolium-bis-naphthalene diimide four station axle component is reported. Proton NMR anion binding titration experiments revealed the halogen bonding rotaxane is selective for nitrate over the more basic acetate, hydrogen carbonate and dihydrogen phosphate oxoanions and chloride, and exhibits enhanced recognition of anions relative to a hydrogen bonding analogue. This elaborate interlocked anion receptor functions via a novel dynamic pincer mechanism where upon nitrate anion binding, both macrocycles shuttle from the naphthalene diimide stations at the periphery of the axle to the central halogen bonding iodo-triazolium station anion recognition sites to form a unique 1:1 stoichiometric nitrate anion-rotaxane sandwich complex. Molecular dynamics simulations carried out on the nitrate and chloride halogen bonding [3]rotaxane complexes corroborate the (1) H NMR anion binding results. © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Radiation resistivity of quartz core fiber, 3

International Nuclear Information System (INIS)

Gozen, Toshikazu; Suzuki, Toshiya; Hayashi, Tokuji; Tanaka, Hiroyuki; Okamoto, Shinichi.

1985-01-01

Radiation resistance characteristics were evaluated for a multi-mode quartz core fiber in low temperature region together with photobleaching effect depending on the incident light power and dependency on the wavelength of measuring rays. This report describes the results of the abovementioned items and the next step study of trial manufacturing of a pure-quartz single-mode fiber for the employment of longer wavelength rays and greater capacity in light transmission communication system. Quartz core fiber specimens were irradiated by 60 Co γ-ray source at -55 deg C to 80 deg C in a constant temperature bath and light transmission loss was determined under irradiation conditions. Low temperature characteristics were superior in an MRT (modified rod-in tube) pure quartz fiber prepared by the plasma method as compared to VAD quartz and Ge-GI fibers. The MRT fiber showed better quality than the Ge-GI fiber also in the photobleaching effect examination. As for the wavelength dependency, light transmission loss of the MRT fiber was less than that of the Ge-GI fiber. The MRT fiber also showed a superior quality in the wide range of irradiation temperatures. Based on the above-mentioned understandings, a pure-quartz single-mode fiber of both BF 3 -doped and F-doped cladding types were developed for longer wavelengths uses. The fibers could attain low light transmission loss of less than 1.0 dB/km at 1.30 μm of wavelength. At the standpoint of radiation resistivity, the BF 3 -doped fiber was found superior. (Takagi, S.)

Singlet oxygen production by combining erythrosine and halogen light for photodynamic inactivation of Streptococcus mutans.

Science.gov (United States)

Fracalossi, Camila; Nagata, Juliana Yuri; Pellosi, Diogo Silva; Terada, Raquel Sano Suga; Hioka, Noboru; Baesso, Mauro Luciano; Sato, Francielle; Rosalen, Pedro Luiz; Caetano, Wilker; Fujimaki, Mitsue

2016-09-01

Photodynamic inactivation of microorganisms is based on a photosensitizing substance which, in the presence of light and molecular oxygen, produces singlet oxygen, a toxic agent to microorganisms and tumor cells. This study aimed to evaluate singlet oxygen quantum yield of erythrosine solutions illuminated with a halogen light source in comparison to a LED array (control), and the photodynamic effect of erythrosine dye in association with the halogen light source on Streptococcus mutans. Singlet oxygen quantum yield of erythrosine solutions was quantified using uric acid as a chemical-probe in an aqueous solution. The in vitro effect of the photodynamic antimicrobial activity of erythrosine in association with the halogen photopolimerizing light on Streptococcus mutans (UA 159) was assessed during one minute. Bacterial cultures treated with erythrosine alone served as negative control. Singlet oxygen with 24% and 2.8% degradation of uric acid in one minute and a quantum yield of 0.59 and 0.63 was obtained for the erythrosine samples illuminated with the halogen light and the LED array, respectively. The bacterial cultures with erythrosine illuminated with the halogen light presented a decreased number of CFU mL(-1) in comparison with the negative control, with minimal inhibitory concentrations between 0.312 and 0.156mgmL(-1). The photodynamic response of erythrosine induced by the halogen light was capable of killing S. mutans. Clinical trials should be conducted to better ascertain the use of erythrosine in association with halogen light source for the treatment of dental caries. Copyright © 2016 Elsevier B.V. All rights reserved.

On the ultrafast charge migration and subsequent charge directed reactivity in Cl⋯N halogen-bonded clusters following vertical ionization

International Nuclear Information System (INIS)

Chandra, Sankhabrata; Bhattacharya, Atanu; Periyasamy, Ganga

2015-01-01

In this article, we have presented ultrafast charge transfer dynamics through halogen bonds following vertical ionization of representative halogen bonded clusters. Subsequent hole directed reactivity of the radical cations of halogen bonded clusters is also discussed. Furthermore, we have examined effect of the halogen bond strength on the electron-electron correlation- and relaxation-driven charge migration in halogen bonded complexes. For this study, we have selected A-Cl (A represents F, OH, CN, NH 2 , CF 3 , and COOH substituents) molecules paired with NH 3 (referred as ACl:NH 3 complex): these complexes exhibit halogen bonds. To the best of our knowledge, this is the first report on purely electron correlation- and relaxation-driven ultrafast (attosecond) charge migration dynamics through halogen bonds. Both density functional theory and complete active space self-consistent field theory with 6-31 + G(d, p) basis set are employed for this work. Upon vertical ionization of NCCl⋯NH 3 complex, the hole is predicted to migrate from the NH 3 -end to the ClCN-end of the NCCl⋯NH 3 complex in approximately 0.5 fs on the D 0 cationic surface. This hole migration leads to structural rearrangement of the halogen bonded complex, yielding hydrogen bonding interaction stronger than the halogen bonding interaction on the same cationic surface. Other halogen bonded complexes, such as H 2 NCl:NH 3 , F 3 CCl:NH 3 , and HOOCCl:NH 3 , exhibit similar charge migration following vertical ionization. On the contrary, FCl:NH 3 and HOCl:NH 3 complexes do not exhibit any charge migration following vertical ionization to the D 0 cation state, pointing to interesting halogen bond strength-dependent charge migration

First principles study of halogens adsorption on intermetallic surfaces

International Nuclear Information System (INIS)

Zhu, Quanxi; Wang, Shao-qing

2016-01-01

Graphical abstract: - Highlights: • The linear relation between adsorbates induced work function change and dipole moment change also exists for intermetallic surfaces. • It is just a common linear relationship rather than a directly proportion. • A new weight parameter β is proposed to describe different factors effect on work function shift. - Abstract: Halides are often present at electrochemical environment, they can directly influence the electrode potential or zero charge potential through the induced work-function change. In this work, we focused in particular on the halogen-induced work function change as a function of the coverage of fluorine, chlorine, bromine and iodine on Al_2Au and Al_2Pt (110) surfaces. Results show that the real relation between work function change and dipole moment change for halogens adsorption on intermetallic surfaces is just a common linear relationship rather than a directly proportion. Besides, the different slopes between fitted lines and the theoretical slope employed in pure metal surfaces demonstrating that the halogens adsorption on intermetallic surfaces are more complicated. We also present a weight parameter β to describe different factors effect on work function shift and finally qualify which factor dominates the shift direction.

Fabrication of a novel quartz micromachined gyroscope

Science.gov (United States)

Xie, Liqiang; Xing, Jianchun; Wang, Haoxu; Wu, Xuezhong

2015-04-01

A novel quartz micromachined gyroscope is proposed in this paper. The novel gyroscope is realized by quartz anisotropic wet etching and 3-dimensional electrodes deposition. In the quartz wet etching process, the quality of Cr/Au mask films affecting the process are studied by experiment. An excellent mask film with 100 Å Cr and 2000 Å Au is achieved by optimization of experimental parameters. Crystal facets after etching seriously affect the following sidewall electrodes deposition process and the structure's mechanical behaviours. Removal of crystal facets is successfully implemented by increasing etching time based on etching rate ratios between facets and crystal planes. In the electrodes deposition process, an aperture mask evaporation method is employed to prepare electrodes on 3-dimensional surfaces of the gyroscope structure. The alignments among the aperture masks are realized by the ABM™ Mask Aligner System. Based on the processes described above, a z-axis quartz gyroscope is fabricated successfully.

Asymmetric adsorption of alanine by quartz powder from ethanol solution

Energy Technology Data Exchange (ETDEWEB)

Furuyama, Shozo; Sawada, Michio; Hachiya, Kinji; Morimoto, Tetsuo (Okayama Univ. (Japan). Faculty of Science)

1982-11-01

The asymmetric adsorption of the racemic alanine by the optically active quartz from ethanol solution at 8/sup 0/C was studied by the /sup 14/C-tracer method and the newly developed /sup 14/C-tracer ninhydrin-colorimetry combination method. The preferential adsorption of L-alanine by levorotatory quartz (l-quartz) and D-alanine by dextrorotatory quartz (d-quartz) was confirmed. The asymmetric adsorptivity (Asub(s)) falls in the range of 1.1 - 1.3, which is comparable with the value determined at - 80/sup 0/C in the previous paper. The effects of water content in the ethanol solution and of the adsorption temperature upon the adsorption affinity of alanine to quartz were also measured. The cause for the asymmetric adsorption is discussed from the crystallographic point of view.

Isostructurality and non-isostructurality in the series of halogenated organic crystal substances. The structure of Hal-aggregates

International Nuclear Information System (INIS)

Grineva, O.V.; Zorkij, P.M.

2001-01-01

Local characteristics and the type of intermolecular Hal-aggregates (ensembles of contacting halogen atoms of adjacent molecules) present in chemically similar halogenated crystal substances, differing only in the nature of Hal atoms, are compared. 23 series of halogenated hydrocarbons, including 57 crystal structures were considered. A clearly pronounced specificity of Hal-aggregates for compounds with a low and intermediate content of halogen was revealed. It was found that, as a rule, coordination number of Hal atom by Hal adjacent atoms increases in the series F-Cl-Br-I [ru

Halogens in pore water of peat bogs – the role of peat decomposition and dissolved organic matter

Directory of Open Access Journals (Sweden)

H. Biester

2006-01-01

Full Text Available Halogens are strongly enriched in peat and peatlands and such they are one of their largest active terrestrial reservoir. The enrichment of halogens in peat is mainly attributed to the formation of organohalogens and climatically controlled humification processes. However, little is known about release of halogens from the peat substrate and the distribution of halogens in the peat pore water. In this study we have investigated the distribution of chlorine, bromine and iodine in pore water of three pristine peat bogs located in the Magellanic Moorlands, southern Chile. Peat pore waters were collected using a sipping technique, which allows in situ sampling down to a depth greater than 6m. Halogens and halogen species in pore water were determined by ion-chromatography (IC (chlorine and IC-ICP-MS (bromine and iodine. Results show that halogen concentrations in pore water are 15–30 times higher than in rainwater. Mean concentrations of chlorine, bromine and iodine in pore water were 7–15 mg l−1, 56–123 μg l−1, and 10–20 μg l−1, which correspond to mean proportions of 10–15%, 1–2.3% and 0.5–2.2% of total concentrations in peat, respectively. Organobromine and organoiodine were the predominant species in pore waters, whereas chlorine in pore water was mostly chloride. Advection and diffusion of halogens were found to be generally low and halogen concentrations appear to reflect release from the peat substrate. Release of bromine and iodine from peat depend on the degree of peat degradation, whereas this relationship is weak for chlorine. Relatively higher release of bromine and iodine was observed in less degraded peat sections, where the release of dissolved organic carbon (DOC was also the most intensive. It has been concluded that the release of halogenated dissolved organic matter (DOM is the predominant mechanism of iodine and bromine release from peat.

Halogen poisoning effect of Pt-TiO{sub 2} for formaldehyde catalytic oxidation performance at room temperature

Energy Technology Data Exchange (ETDEWEB)

Zhu, Xiaofeng; Cheng, Bei [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Luoshi Road 122#, Wuhan 430070 (China); Yu, Jiaguo, E-mail: jiaguoyu@yahoo.com [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Luoshi Road 122#, Wuhan 430070 (China); Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Ho, Wingkei, E-mail: keithho@ied.edu.hk [Department of Science and Environmental Studies and Centre for Education in Environmental Sustainability, The Hong Kong Institute of Education, Tai Po, N.T. Hong Kong (China)

2016-02-28

Graphical abstract: - Highlights: • The Pt-TiO{sub 2} catalyst is deactivated by adsorption of halogen ions. • The halogen poison is mainly attributed to the active site blocking of the Pt surface. • Halogen ions and Pt form Pt−X coordination bonds. • Large halogen diameter exhibits severe poisoning effect. - Abstract: Catalytic decomposition of formaldehyde (HCHO) at room temperature is an important method for HCHO removal. Pt-based catalysts are the optimal catalyst for HCHO decomposition at room temperature. However, the stability of this catalyst remains unexplored. In this study, Pt-TiO{sub 2} (Pt-P25) catalysts with and without adsorbed halogen ions (including F{sup −}, Cl{sup −}, Br{sup −}, and I{sup −}) were prepared through impregnation and ion modification. Pt-TiO{sub 2} samples with adsorbed halogen ions exhibited reduced catalytic activity for formaldehyde decomposition at room temperature compared with the Pt-TiO{sub 2} sample; the catalytic activity followed the order of F-Pt-P25, Cl-Pt-P25, Br-Pt-P25, and I-Pt-P25. Characterization results (including XRD, TEM, HRTEM, BET, XPS, and metal dispersion) showed that the adsorbed halogen ions can poison Pt nanoparticles (NPs), thereby reducing the HCHO oxidation activity of Pt-TiO{sub 2}. The poison mechanism is due to the strong adsorption of halogen ions on the surface of Pt NPs. The adsorbed ions form coordination bonds with surface Pt atoms by transferring surplus electrons into the unoccupied 5d orbit of the Pt atom, thereby inhibiting oxygen adsorption and activation of the Pt NP surface. Moreover, deactivation rate increases with increasing diameter of halogen ions. This study provides new insights into the fabrication of high-performance Pt-based catalysts for indoor air purification.

On the ultrafast charge migration and subsequent charge directed reactivity in Cl⋯N halogen-bonded clusters following vertical ionization

Energy Technology Data Exchange (ETDEWEB)

Chandra, Sankhabrata; Bhattacharya, Atanu, E-mail: atanub@ipc.iisc.ernet.in [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore (India); Periyasamy, Ganga [Department of Chemistry, Central College Campus, Bangalore University, Bangalore (India)

2015-06-28

In this article, we have presented ultrafast charge transfer dynamics through halogen bonds following vertical ionization of representative halogen bonded clusters. Subsequent hole directed reactivity of the radical cations of halogen bonded clusters is also discussed. Furthermore, we have examined effect of the halogen bond strength on the electron-electron correlation- and relaxation-driven charge migration in halogen bonded complexes. For this study, we have selected A-Cl (A represents F, OH, CN, NH{sub 2}, CF{sub 3}, and COOH substituents) molecules paired with NH{sub 3} (referred as ACl:NH{sub 3} complex): these complexes exhibit halogen bonds. To the best of our knowledge, this is the first report on purely electron correlation- and relaxation-driven ultrafast (attosecond) charge migration dynamics through halogen bonds. Both density functional theory and complete active space self-consistent field theory with 6-31 + G(d, p) basis set are employed for this work. Upon vertical ionization of NCCl⋯NH{sub 3} complex, the hole is predicted to migrate from the NH{sub 3}-end to the ClCN-end of the NCCl⋯NH{sub 3} complex in approximately 0.5 fs on the D{sub 0} cationic surface. This hole migration leads to structural rearrangement of the halogen bonded complex, yielding hydrogen bonding interaction stronger than the halogen bonding interaction on the same cationic surface. Other halogen bonded complexes, such as H{sub 2}NCl:NH{sub 3}, F{sub 3}CCl:NH{sub 3}, and HOOCCl:NH{sub 3}, exhibit similar charge migration following vertical ionization. On the contrary, FCl:NH{sub 3} and HOCl:NH{sub 3} complexes do not exhibit any charge migration following vertical ionization to the D{sub 0} cation state, pointing to interesting halogen bond strength-dependent charge migration.

Reconciliation of Halogen-Induced Ozone Loss with the Total-Column Ozone Record

Science.gov (United States)

Shepherd, T. G.; Plummer, D. A.; Scinocca, J. F.; Hegglin, M. I.; Fioletov, V. E.; Reader, M. C.; Remsberg, E.; von Clarmann, T.; Wang, H. J.

2014-01-01

The observed depletion of the ozone layer from the 1980s onwards is attributed to halogen source gases emitted by human activities. However, the precision of this attribution is complicated by year-to-year variations in meteorology, that is, dynamical variability, and by changes in tropospheric ozone concentrations. As such, key aspects of the total-column ozone record, which combines changes in both tropospheric and stratospheric ozone, remain unexplained, such as the apparent absence of a decline in total-column ozone levels before 1980, and of any long-term decline in total-column ozone levels in the tropics. Here we use a chemistry-climate model to estimate changes in halogen-induced ozone loss between 1960 and 2010; the model is constrained by observed meteorology to remove the eects of dynamical variability, and driven by emissions of tropospheric ozone precursors to separate out changes in tropospheric ozone. We show that halogen-induced ozone loss closely followed stratospheric halogen loading over the studied period. Pronounced enhancements in ozone loss were apparent in both hemispheres following the volcanic eruptions of El Chichon and, in particular, Mount Pinatubo, which significantly enhanced stratospheric aerosol loads. We further show that approximately 40% of the long-term non-volcanic ozone loss occurred before 1980, and that long-term ozone loss also occurred in the tropical stratosphere. Finally, we show that halogeninduced ozone loss has declined by over 10% since stratospheric halogen loading peaked in the late 1990s, indicating that the recovery of the ozone layer is well underway.

Luminescence sensitivity changes in quartz

CERN Document Server

Wintle, A G

1999-01-01

In the luminescence dating of sedimentary or heated quartz, some heat treatment is usually applied to the sample immediately prior to the measurement of the optically stimulated luminescence. In this paper we report experiments on a 30,000-year-old sedimentary quartz, in which we use the luminescence response to a test dose to monitor the changes in sensitivity that are caused by holding the quartz at temperatures from 160 to 280 deg. C for times from 10 s to 22 h. For an optically bleached sample, the monitoring is by both optically stimulated luminescence and the 110 deg. C TL peak; both luminescence signals are shown to have the same sensitisation (i.e. activation energy) characteristics. For natural or laboratory irradiated samples only the 110 deg. C TL peak can be used; sensitivity increases of up to a factor of 1.3 and 3 are observed for the natural and laboratory irradiated aliquots, respectively. Up to four exponential components are used to deconvolve the sensitivity change data; the dominant compon...

Iron Mineral Catalyzed C-H Activation As a Potential Pathway for Halogenation Processes

Science.gov (United States)

Tubbesing, C.; Schoeler, H. F.; Benzing, K.; Krause, T.; Lippe, S.; Rudloff, M.

2014-12-01

Due to increasing drinking water demand of mankind and an expected climate change the impact of salt lakes and salt deserts will increase within the next decades. Furthermore, a rising sea level influences coastal areas like salt marshes and abets processes which will lead to elevated organohalogen formation. An additional increase of the global warming potential, of particle formation and stratospheric ozone depletion is expected. Understanding these multifaceted processes is essential for mankind to be prepared for these alterations of the atmosphere. For example, Keppler et al. (2000) described the production of volatile halogenated organic compounds via oxidation of organic matter driven by ferric iron. However, the formation of long-chained alkyl halides in salt lakes is yet undisclosed. Despite the relative "inertness" of alkanes a direct halogenation of these compounds might be envisaged. In 2005 Vaillancourt et al. discovered a nonheme iron enzyme which is able to halogenate organic compounds via generating the high valent ferryl cation as reaction center. Based on various publications about C-H activation (Bergman, 2007) we postulate a halogenation process in which an iron containing minerals catalyse the C-H bond cleavage of organic compounds in soils. The generated organic radicals are highly reactive towards halides connected to the iron complex. We suggest that next to diagenetically altered iron containing enzymes, minerals such as oxides, hydroxides and sulfides are involved in abiotic halogenation processes. We applied the amino acid methionine as organic model compound and soluble iron species as reactants. All samples were incubated in aqueous phases containing various NaCl concentrations. As a result various halogenated ethanes and ethenes were identified as reaction products. References Bergman, R. G. (2007) Nature, 446(7134) 391-393 Keppler, F., et al. (2000) Nature, 403(6767) 298-301 Vaillancourt, F. H., et al. (2005) Nature, 436(7054) 1191-1194

Development of halogen-free, heat-resistant, low-voltage wire for automotive use

International Nuclear Information System (INIS)

Ueno, Keiji; Suzuki, Sizuo; Takahagi, Masatoshi; Uda, Ikujiro

1995-01-01

The environmental load of our motorized society is of major concern, and includes considerations of recycling of automotive parts as the industrial wastes. The total average length of AV, AVX (electrical wire insulated with PVC, cross-linked PVC), and AEX (electrical wire insulated with cross-linked polyolefin) wires required for the harnesses in modern automobiles is approximately 2,000-3,000 meters per unit. However these electrical wires contain a large amount of halogen, which can generate the smoke and corrosive gas. In response to this problem the authors have developed the electron beam irradiated halogen-free, heat-resistant, low-voltage electrical wire which does not contain any halogen based polymer or flame retardants. The developed wire features the reliability equivalent to AEX wire with minimum environmental load. (Author)

Microbially induced separation of quartz from hematite using sulfate reducing bacteria.

Science.gov (United States)

Prakasan, M R Sabari; Natarajan, K A

2010-07-01

Cells and metabolic products of Desulfovibrio desulfuricans were successfully used to separate quartz from hematite through environmentally benign microbially induced flotation. Bacterial metabolic products such as extracellular proteins and polysaccharides were isolated from both unadapted and mineral-adapted bacterial metabolite and their basic characteristics were studied in order to get insight into the changes brought about on bioreagents during adaptation. Interaction between bacterial cells and metabolites with minerals like hematite and quartz brought about significant surface-chemical changes on both the minerals. Quartz was rendered more hydrophobic, while hematite became more hydrophilic after biotreatment. The predominance of bacterial polysaccharides on interacted hematite and of proteins on quartz was responsible for the above surface-chemical changes, as attested through adsorption studies. Surface-chemical changes were also observed on bacterial cells after adaptation to the above minerals. Selective separation of quartz from hematite was achieved through interaction with quartz-adapted bacterial cells and metabolite. Mineral-specific proteins secreted by quartz-adapted cells were responsible for conferment of hydrophobicity on quartz resulting in enhanced separation from hematite through flotation. 2010 Elsevier B.V. All rights reserved.

Thermal quenching of thermoluminescence in quartz samples of various origin

International Nuclear Information System (INIS)

Subedi, B.; Oniya, E.; Polymeris, G.S.; Afouxenidis, D.; Tsirliganis, N.C.; Kitis, G.

2011-01-01

The effect of thermal quenching stands among the most important properties in the thermoluminescence (TL) of quartz on which many applications of TL are based. Since the quartz samples used in various applications are all of different origin it is useful to investigate whether the values of the thermal quenching parameters, i.e. the activation energy for thermal quenching W and a parameter C which describes the ratio of non-radiative to radiative luminescence transitions, evaluated mainly in specific quartz samples can be extrapolated to quartz samples of unknown origin as well as to quartz samples which are annealed at high temperatures. In the present work the TL glow curve of a series of un-annealed and annealed natural and synthetic quartz samples were studied as a function of the heating rate between 0.25 K/s and 16 K/s. Using an indirect fitting method it was found that the thermal quenching parameters W and C in most of the quartz samples are very similar to the values accepted in the literature. Furthermore, in some cases the thermal quenching parameters W and C are not the same for all TL glow-peaks in the same glow-curve. Finally, the strong external treatment of annealing the quartz samples at very high temperature can also influence at least one of the thermal quenching parameters.

Recoil halogen reactions in liquid and frozen aqueous solutions of biomolecules

International Nuclear Information System (INIS)

Arsenault, L.J.; Blotcky, A.J.; Firouzbakht, M.L.; Rack, E.P.; Nebraska Univ., Omaha

1982-01-01

Reactions of recoil 38 Cl, 80 Br and 128 I have been studied in crystalline systems of 5-halouracil, 5-halo-2'-deoxyuridine and 5-halouridine as well as liquid and frozen aqueous solutions of these halogenated biomolecules. In all systems expect crystalline 5-iuodouracil the major product was the radio-labelled halide ion. There was no evidence for other halogen inorganic species. The major labelled organic product was the parent molecule. A recoil atom tracer technique was developed to acquire site information of the biomolecule solutes in the liquid and frozen aqueous systems. For all liquid and frozen aqueous systems, the halogenated biomolecules tended to aggregate. For liquid systems, the tendency for aggregation diminished as the solute concentration approached zero, where the probable state of the solute approached a monomolecular dispersion. Unlike the liquid state, the frozen ice lattice demonstated a ''caging effect'' for the solute aggregates which resulted in constant product yields over the whole concentration range. (orig.)

Environmental levels and toxicological potencies of a novel mixed halogenated carbazole

Directory of Open Access Journals (Sweden)

Miren Pena-Abaurrea

2016-09-01

Full Text Available The present work involves an extensive analytical and toxicological description of a recently identified mixed halogenated carbazole found in sediment samples, 1,8-dibromo-3,6-dichloro-9H-carbazole (BCCZ. Concentrations and the relative effect potency (REP were calculated for the target BCCZ in a set of stream sediments collected in 2008 in Ontario, Canada. The levels calculated for BCCZ as compared to those previously assessed for legacy persistent organic pollutants (POPs in the same samples revealed a significant contribution of BCCZ to the total organic chemical contamination (<1%–95%; average 37%. The corresponding dioxin toxic equivalencies (TEQs of BCCZ in the sediment extracts were estimated from experimental REP data. The experimental data presented supports the classification of this emerging halogenated chemical as a contaminant of emerging environmental concern. Although potential emission sources could not be identified, this study highlights the importance of on-going research for complete characterization of halogenated carbazoles and related compounds.

Quartz exsolution topotaxy in clinopyroxene from the UHP eclogite of Weihai, China

Science.gov (United States)

Xu, Haijun; Zhang, Junfeng; Zong, Keqing; Liu, Liang

2015-06-01

Abundant oriented silica precipitates of α-quartz (4.0 ± 1.0 vol.%), in part coexisting with calcic amphiboles (topotactic relationships with their host clinopyroxenes. Three types of crystallographic topotactic relationship have been identified between quartz and host clinopyroxene: (1) 52% quartz precipitates share the same orientation for the c-axes with [0001]qz//[001]cpx; (2) 34% quartz precipitates share the same orientation for the a-axes with [11 2 bar0]qz//[001]cpx; and (3) 11% quartz precipitates share the same orientation for the s-planes with (11 2 bar1)qz//(100)cpx. Other quartz axes and planes disperse in large or small girdles around the shared axes or planes. Many quartz rods/needles are elongated parallel to the [001]cpx with the long axes of quartz being either [0001]qz or [11 2 bar0]qz. Amphibole precipitates have also a strong crystallographic relationship with host clinopyroxene, i.e., (100)amp//(100)cpx, [010]amp//[010]cpx, and [001]amp//[001]cpx. These results provide quantitative microstructural evidence supporting an exsolution origin for oriented quartz needles/rods in clinopyroxene and demonstrate that the exsolution of quartz from clinopyroxene occurred within the stability field of α-quartz rather than coesite. The oriented precipitates of α-quartz, in part coexisting with calcic amphiboles, in host clinopyroxene are probably promoted by supercritical fluid or partial melting during the early exhumation of eclogites. Our results suggest that oriented quartz precipitates in clinopyroxene cannot be used as an indisputable UHP-indicator.

Development of no halogen incombustible cables for atomic energy

International Nuclear Information System (INIS)

Ishii, Nobumasa; Kimura, Hitoshi; Fujimura, Shun-ichi

1990-01-01

In upgrading light water reactor technology, it is important to improve the reliability of machinery and equipment, to make regular inspection efficient, to extend the period of continuous operation, to optimize operation cycle and to improve the maintainability of plant facilities. For the cables for nuclear power stations, high incombustibility is required, and at present halogen system incombustible materials are used. Recently the development of no halogen incombustible cables has been advanced, with which the generation of corrosive gas and smoke at the time of fires is slight. In this study, the application of such no halogen incombustible cables to nuclear power stations and the improvement of reliability of the cables were investigated. The cables to be developed are those for electric power, control and instrumentation in BWR plants and insulated electric wires. The required characteristics are incombustibility, no generation of smoke and corrosive gas at the time of fires, radiation resistance and steam resistance in LOCA. The selection of base polymers, metal hydrates and radiation protectors, the evaluation of radiation resistance and steam resistance, the examination of the corrosive and poisonous properties of generated gas and smoke generation and so on are reported. The development was successful. (K.I.)

Dating quartz: Ar/Ar analyses of coexisting muscovite and fluid inclusion - rich quartz from paleocene amorphic aureole

International Nuclear Information System (INIS)

Matthews, S.J.; Perez de Arce, C.; Cornejo, P.; Cuitino, L; Klein, J

2001-01-01

We present Ar/Ar total fusion and step-heating data for coexisting muscovite and white quartz from the metamorphic aureole of the Lower Paleocene La Copiapina Pluton, 6 km south of Inca de Oro, III Region, Chile. The pluton intrudes the upper clastic sedimentary member of the Punta del Cobre Group (Upper Jurassic - Lower Cretaceous) and the calcareous sedimentary rocks of the Chanarcillo Group (Neocomian), and comprises fine to coarse grained pyroxene-hornblende-biotite quartz diorites and monzodiorites. Its emplacement was controlled on its north-western side by a subvertical NE-trending fault, along which were developed vertically banded skarns (skarn mylonite), suggesting syntectonic intrusion. Biotite K-Ar ages for the pluton fall in the range 61-63 Ma, relating it to a latest Cretaceous to Lowest Paleocene syn-compressional intrusive belt which is present in the area (Matthews and Cornejo, 2000). A metamorphic / metasomatic aureole is developed within the sandstones of the Punta del Cobre Group, on the extreme northern limit of the pluton. In this area, the sedimentary rocks have been replaced by quartz-sericite and quartz-muscovite assemblages, with minor hematite and tourmaline, and late supergene kaolinite and pyrophyllite. A coarse muscovite-quartz-tourmaline-hematite assemblage is developed in and around older (early Upper Cretaceous) andesitic dykes, in the form of replacement / fracture fill veins and replacement zones. Further from the contact with the pluton, fine-grained quartz-sericite rock with coarser muscovite-rich replacement veins represents the dominant lithology. Quartz in the coarse replacement rock is very rich in fluid inclusions. Primary inclusions are mainly of two coexisting types; bi-phase (liquid and gas bubble) and tri-phase (liquid, gas bubble and halite crystal), indicating that the quartz formed in the presence of a boiling fluid. Some inclusions also contain sylvite and occasional hematite daughter crystals. Secondary inclusions

Chlorine dioxide as phenol and H2S scavenger - formation of halogenated phenols and subsequent environmental risk

Energy Technology Data Exchange (ETDEWEB)

Melbye, Alf G.; Faksness, Liv-Guri; Knudsen, Boerre Leif

2006-03-15

Formation of halogenated phenols as side products from treatment of produced water with aqueous chlorine dioxide has been investigated. The literature describes formation of halogenated hydrocarbons in effluent treatment using chlorine, hypochlorite and chlorine dioxide. A new chlorine dioxide product, originally intended as a H2S scavenger in the oil and gas industry, has been tested both as a phenol scavenger and H2S-scavenger for produced water applications. The concern about the possible formation of halogenated by-products initiated laboratory testing of chlorine dioxide as phenol and H2S scavenger for produced water applications. The tests also included synthetic matrixes containing phenols, and the tests show that halogenated phenols, mainly brominated species, are found in produced water after treatment with chlorine dioxide. Due to potential environmental risk from halogenated organic contaminants, the use of chlorine dioxide as phenol and H2S scavenger is not recommended. (Author)

Determination of N-containing halogenated natural products using gas chromatography in combination of a nitrogen-phosphorus-detector

Energy Technology Data Exchange (ETDEWEB)

Melcher, J.; Vetter, W. [Hohenheim Univ., Stuttgart (Germany). Inst. fuer Lebensmittelchemie

2004-09-15

In the last few years several nonpolar halogenated natural products (HNPs) such as Q1, MHC-1, BC-2, BC-3, BC-10 were detected at elevated concentrations in marine biota samples. In addition, there are still some abundant peaks of halogenated compounds frequently found in the gas chromatograms of many marine samples which have not yet been identified. Some of the known halogenated natural products (Q1, HDBPs including BC-10, bromoindoles) contain N-heterocyclic backbones. Since nitrogen is scarcely found in anthropogenic halogenated compounds, the detection of N-containing halogenated substances may be used as a first indicator for the presence of HNPs in a sample extract. In the presented method we studied the suitability of a nitrogen phosphorous detector (NPD) for quantification of Q1 and the detection of Ncontaining compounds in marine biota. Analyses were accompanied with GC/ECD analyses.

A 19F NMR study of C-I....pi- halogen bonding

DEFF Research Database (Denmark)

Hauchecorne, Dieter; vand er Veken, Benjamin J.; Herrebout, Wouter A.

2011-01-01

The formation of halogen bonded complexes between toluene-d8 and the perfluoroiodopropanes 1-C3F7I and 2-C3F7I has been investigated using 19F NMR spectroscopy. For both Lewis acids, evidence was found for the formation of a C–I⋯π halogen bonded complex. The complex formed is a 1:1 type. Using sp...... results are supported by ab initio calculations at the B3LYP-PCM/6-311++G(d,p) + LanL2DZ∗ level....

Are superhalogens without halogen ligand capable of transcending traditional halogen-based superhalogens? Ab initio case study of binuclear anions based on pseudohalogen ligand

Science.gov (United States)

Li, Jin-Feng; Sun, Yin-Yin; Bai, Hongcun; Li, Miao-Miao; Li, Jian-Li; Yin, Bing

2015-06-01

The superhalogen properties of polynuclear structures without halogen ligand are theoretically explored here for several [M2(CN)5]-1 (M = Ca, Be) clusters. At CCSD(T) level, these clusters have been confirmed to be superhalogens due to their high vertical electron detachment energies (VDE). The largest one is 9.70 eV for [Ca2(CN)5]-1 which is even higher than those of corresponding traditional structures based on fluorine or chlorine ligands. Therefore the superhalogens stronger than the traditional halogen-based structures could be realized by ligands other than halogen atoms. Compared with CCSD(T), outer valence Green's function (OVGF) method either overestimates or underestimates the VDEs for different structures while MP2 results are generally consistent in the aspect of relative values. The extra electrons of the highest VDE anions here aggregate on the bridging CN units with non-negligible distribution occurring on other CN units too. These two features lower both the potential and kinetic energies of the extra electron respectively and thus lead to high VDE. Besides superhalogen properties, the structures, relative stabilities and thermodynamic stabilities with respect to the detachment of cyanide ligand were also investigated. The sum of these results identifies the potential of polynuclear structures with pseudohalogen ligand as suitable candidates with enhanced superhalogens properties.

Halogen bond tunability II: the varying roles of electrostatic and dispersion contributions to attraction in halogen bonds

Czech Academy of Sciences Publication Activity Database

Riley, Kevin Eugene; Murray, J. S.; Fanfrlík, Jindřich; Řezáč, Jan; Solá, R. J.; Concha, M. C.; Ramos, F. M.; Politzer, P.

2013-01-01

Roč. 19, č. 11 (2013), s. 4651-4659 ISSN 1610-2940 R&D Projects: GA ČR GBP208/12/G016 Grant - others:Operational Program Research and Development for Innovations(XE) CZ.1.05/2.1.00/03.0058 Institutional support: RVO:61388963 Keywords : dispersion * electrostatics * halogen bonding * noncovalent interactions Subject RIV: CE - Biochemistry Impact factor: 1.867, year: 2013

Engaging the Terminal: Promoting Halogen Bonding Interactions with Uranyl Oxo Atoms.

Science.gov (United States)

Carter, Korey P; Kalaj, Mark; Surbella, Robert G; Ducati, Lucas C; Autschbach, Jochen; Cahill, Christopher L

2017-11-02

Engaging the nominally terminal oxo atoms of the linear uranyl (UO 2 2+ ) cation in non-covalent interactions represents both a significant challenge and opportunity within the field of actinide hybrid materials. An approach has been developed for promoting oxo atom participation in a range of non-covalent interactions, through judicious choice of electron donating equatorial ligands and appropriately polarizable halogen-donor atoms. As such, a family of uranyl hybrid materials was generated based on a combination of 2,5-dihalobenzoic acid and aromatic, chelating N-donor ligands. Delineation of criteria for oxo participation in halogen bonding interactions has been achieved by preparing materials containing 2,5-dichloro- (25diClBA) and 2,5-dibromobenzoic acid (25diBrBA) coupled with 2,2'-bipyridine (bipy) (1 and 2), 1,10-phenanthroline (phen) (3-5), 2,2':6',2''-terpyridine (terpy) (6-8), or 4'-chloro-2,2':6',2''-terpyridine (Cl-terpy) (9-10), which have been characterized through single crystal X-ray diffraction, Raman, Infrared (IR), and luminescence spectroscopy, as well as through density functional calculations of electrostatic potentials. Looking comprehensively, these results are compared with recently published analogues featuring 2,5-diiodobenzoic acid which indicate that although inclusion of a capping ligand in the uranyl first coordination sphere is important, it is the polarizability of the selected halogen atom that ultimately drives halogen bonding interactions with the uranyl oxo atoms. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quartz-molybdenite veins in the Priestly Lake granodiorite, north-central Maine

Science.gov (United States)

Ayuso, Robert A.; Shank, Stephen G.

1983-01-01

Quartz-molybdenite veins up to 15 cm in width occur in fine to medium-grained porphyritic biotite-hornblende granodiorite at Priestly Lake north-central Maine. An area of about 150 m x 150 m contains quartz-molybdenite veins; a larger area is characterized by barren quartz veins. Quartz-molybdenite veins are concentrated within the most felsic variants of the intrusion as suggested by lower mafic mineral contents. The pluton has a narrow range in SiO2 (67-70 wt.%), major oxides, and in trace-element compositions. Molybdenite occurs as coarse grained clusters in pockets within the quartz veins, and fills fractures in the quartz veins and host rocks. Disseminated molybdenite in the granodiorite is relatively rare and occurs only in the area characterized by a high density of quartz veins (up to 50 veins per square meter). Alteration envelopes along the quartz veins are very thin or absent, although in some areas the granodiorite appears to be selectively and pervasively altered. Sericite, chlorite, epidote, calcite, pyrite, and quartz are concentrated near the quartz-molybdenite veins. Many of the field and geochemical characteristics of the Priestly Lake pluton are unlike those of major molybdenum-producing areas (Climax, Henderson, Urad). For example, the area of alteration seems to be of limited extent, the host rock is not intensely altered hydrothermally at the surface, the density of fractures is rather low in the mineralized area, and the amount of disseminated molybdenite appears to be small. However, the Priestly Lake pluton may be a small fraction of a concealed batholith as suggested by geophysical data. It is conceivable that the type of mineralization at the surface might be the expression of more extensive molybdenite mineralization at depth. The quartz-molybdenite veins in the Priestly Lake pluton are significant because they indicate that potential molybdenum sources for producing mineralized granites were available at depth. Future studies should be

Tuning the viscosity of halogen free bulk heterojunction inks for inkjet printed organic solar cells

NARCIS (Netherlands)

Lamont, C.A.; Eggenhuisen, T.M.; Coenen, M.J.J.; Slaats, T.W.L.; Andriessen, R.; Groen, P.

2015-01-01

For the solution processing of organic photovoltaics on an industrial scale, the exclusion of halogenated solvents is a necessity. However, the limited solubility of most semiconducting polymer/fullerene blends in non-halogenated solvents results in ink formulations with low viscosities which poses

Impact of enhanced ozone deposition and halogen chemistry on tropospheric ozone over the Northern Hemisphere

Science.gov (United States)

Fate of ozone in marine environments has been receiving increased attention due to the tightening of ambient air quality standards. The role of deposition and halogen chemistry is examined through incorporation of an enhanced ozone deposition algorithm and inclusion of halogen ch...

Model study of multiphase DMS oxidation with a focus on halogens

Directory of Open Access Journals (Sweden)

R. von Glasow

2004-01-01

Full Text Available We studied the oxidation of dimethylsulfide (DMS in the marine boundary layer (MBL with a one-dimensional numerical model and focused on the influence of halogens. Our model runs show that there is still significant uncertainty about the end products of the DMS addition pathway, which is especially caused by uncertainty in the product yield of the reaction of the intermediate product methyl sulfinic acid (MSIA with OH. BrO strongly increases the importance of the addition branch in the oxidation of DMS even when present at mixing ratios smaller than 0.5pmol mol-1. The inclusion of halogen chemistry leads to higher DMS oxidation rates and smaller DMS to SO2 conversion efficiencies. The DMS to SO2 conversion efficiency is also drastically reduced under cloudy conditions. In cloud-free model runs between 5 and 15% of the oxidized DMS reacts further to particulate sulfur, in cloudy runs this fraction is almost 100%. Sulfate production by HOClaq and HOBraq is important in cloud droplets even for small Br- deficits and related small gas phase halogen concentrations. In general, more particulate sulfur is formed when halogen chemistry is included. A possible enrichment of HCO3- in fresh sea salt aerosol would increase pH values enough to make the reaction of S(IV* (=SO2,aq+HSO3-+SO32- with O3 dominant for sulfate production. It leads to a shift from methyl sulfonic acid (MSA to non-sea salt sulfate (nss-SO42- production but increases the total nss-SO42- only somewhat because almost all available sulfur is already oxidized to particulate sulfur in the base scenario. We discuss how realistic this is for the MBL. We found the reaction MSAaq+OH to contribute about 10% to the production of nss-SO42- in clouds. It is unimportant for cloud-free model runs. Overall we find that the presence of halogens leads to processes that decrease the albedo of stratiform clouds in the MBL.

Chalcogen- and halogen-bonds involving SX2 (X = F, Cl, and Br) with formaldehyde.

Science.gov (United States)

Mo, Lixin; Zeng, Yanli; Li, Xiaoyan; Zhang, Xueying; Meng, Lingpeng

2016-07-01

The capacity of SX2 (X = F, Cl, and Br) to engage in different kinds of noncovalent bonds was investigated by ab initio calculations. SCl2 (SBr2) has two σ-holes upon extension of Cl (Br)-S bonds, and two σ-holes upon extension of S-Cl (Br) bonds. SF2 contains only two σ-holes upon extension of the F-S bond. Consequently, SCl2 and SBr2 form chalcogen and halogen bonds with the electron donor H2CO while SF2 forms only a chalcogen bond, i.e., no F···O halogen bond was found in the SF2:H2CO complex. The S···O chalcogen bond between SF2 and H2CO is the strongest, while the strongest halogen bond is Br···O between SBr2 and H2CO. The nature of these two types of noncovalent interaction was probed by a variety of methods, including molecular electrostatic potentials, QTAIM, energy decomposition, and electron density shift maps. Termolecular complexes X2S···H2CO···SX'2 (X = F, Cl, Br, and X' = Cl, Br) were constructed to study the interplay between chalcogen bonds and halogen bonds. All these complexes contained S···O and Cl (Br)···O bonds, with longer intermolecular distances, smaller values of electron density, and more positive three-body interaction energies, indicating negative cooperativity between the chalcogen bond and the halogen bond. In addition, for all complexes studied, interactions involving chalcogen bonds were more favorable than those involving halogen bonds. Graphical Abstract Molecular electrostatic potential and contour map of the Laplacian of the electron density in Cl2S···H2CO···SCl2 complex.

Rational design of organic semiconductors for texture control and self-patterning on halogenated surfaces

KAUST Repository

Ward, Jeremy W.

2014-05-15

Understanding the interactions at interfaces between the materials constituting consecutive layers within organic thin-film transistors (OTFTs) is vital for optimizing charge injection and transport, tuning thin-film microstructure, and designing new materials. Here, the influence of the interactions at the interface between a halogenated organic semiconductor (OSC) thin film and a halogenated self-assembled monolayer on the formation of the crystalline texture directly affecting the performance of OTFTs is explored. By correlating the results from microbeam grazing incidence wide angle X-ray scattering (μGIWAXS) measurements of structure and texture with OTFT characteristics, two or more interaction paths between the terminating atoms of the semiconductor and the halogenated surface are found to be vital to templating a highly ordered morphology in the first layer. These interactions are effective when the separating distance is lower than 2.5 dw, where dw represents the van der Waals distance. The ability to modulate charge carrier transport by several orders of magnitude by promoting "edge-on" versus "face-on" molecular orientation and crystallographic textures in OSCs is demonstrated. It is found that the "edge-on" self-assembly of molecules forms uniform, (001) lamellar-textured crystallites which promote high charge carrier mobility, and that charge transport suffers as the fraction of the "face-on" oriented crystallites increases. The role of interfacial halogenation in mediating texture formation and the self-patterning of organic semiconductor films, as well as the resulting effects on charge transport in organic thin-film transistors, are explored. The presence of two or more anchoring sites between a halogenated semiconductor and a halogenated self-assembled monolayer, closer than about twice the corresponding van der Waals distance, alter the microstructure and improve electrical properties. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Flame retardant synergism between molybdenum and halogen-containing compounds in unsaturated polyesters. [Smoke suppression

Energy Technology Data Exchange (ETDEWEB)

Skinner, G.A.; Parker, L.E.; Marshall, P.J.

1978-01-01

Oxygen index results for a series of unsaturated polyesters, containing molybdenum oxide and various halogenated compounds, have provided definite evidence for some form of flame retardant synergistic effect between molybdenum and halogen. With the halogenated compounds used, the magnitude of the effect was greater in the presence of bromine but was dependent on the type of compound. When dibromoneopentyl glycol was used as the bromine source, the synergistic effect exhibited by molybdenum oxide was comparable to that shown by antimony oxide. Since molybdenum oxide also acts as a smoke suppressant, it could offer a useful alternative to antimony oxide particularly in the light of probable changes in standards and regulatory control regarding smoke emission. 4 figures, 2 tables.

Study of the halogenation of EuBa[sub 2]Cu[sub 3]O[sub 6]. Etude de l'halogenation de EuBa[sub 2]Cu[sub 3]O[sub 6

Energy Technology Data Exchange (ETDEWEB)

Kabeya, D.T. (Rennes-1 Univ., 35 (France). Lab. de Chimie du Solide et Inorganique Moleculaire); Mokhtari, M. (Rennes-1 Univ., 35 (France). Lab. de Chimie du Solide et Inorganique Moleculaire); Perrin, C. (Rennes-1 Univ., 35 (France). Lab. de Chimie du Solide et Inorganique Moleculaire); Sergent, M. (Rennes-1 Univ., 35 (France). Lab. de Chimie du Solide et Inorganique Moleculaire); Grushko, Yu. (Russian Academy of Sciences, Gatchina (Russian Federation). Nuclear Physics Inst.); Kokovina, L. (Russian Academy of Sciences, Gatchina (Russian Federation). Nuclear Physics Inst.); Rozhniakova, N. (Russian Academy of Sciences, Gatchina (Russian Federation). Nuclear Physics Inst.)

1994-11-01

Sintered samples of EuBa[sub 2]Cu[sub 3]O[sub 6] have been halogenated at low temperature (t<300 C) by treatments under NF[sub 3] or CCl[sub 4] flow diluted in nitrogen, or by reaction with iodine in sealed tubes. Such mild conditions of synthesis allowed to avoid the decomposition of the material during the reactions. The incorporation of the halogen in the sample has been evidenced by the weight gain, by the evolution of the unit-cell parameters and by SEM and EDS analyses. After fluorination and chlorination, the samples become superconducting, but no superconducting behaviour is observed after iodination. These results are compared to the ones previously obtained during the halogenation of YBa[sub 2]Cu[sub 3]O[sub 6]. (orig.).

Quartz enhanced photoacoustic spectroscopy based trace gas sensors using different quartz tuning forks.

Science.gov (United States)

Ma, Yufei; Yu, Guang; Zhang, Jingbo; Yu, Xin; Sun, Rui; Tittel, Frank K

2015-03-27

A sensitive trace gas sensor platform based on quartz-enhanced photoacoustic spectroscopy (QEPAS) is reported. A 1.395 μm continuous wave (CW), distributed feedback pigtailed diode laser was used as the excitation source and H2O was selected as the target analyte. Two kinds of quartz tuning forks (QTFs) with a resonant frequency (f0) of 30.72 kHz and 38 kHz were employed for the first time as an acoustic wave transducer, respectively for QEPAS instead of a standard QTF with a f0 of 32.768 kHz. The QEPAS sensor performance using the three different QTFs was experimentally investigated and theoretically analyzed. A minimum detection limit of 5.9 ppmv and 4.3 ppmv was achieved for f0 of 32.768 kHz and 30.72 kHz, respectively.

Quartz Enhanced Photoacoustic Spectroscopy Based Trace Gas Sensors Using Different Quartz Tuning Forks

Directory of Open Access Journals (Sweden)

Yufei Ma

2015-03-01

Full Text Available A sensitive trace gas sensor platform based on quartz-enhanced photoacoustic spectroscopy (QEPAS is reported. A 1.395 μm continuous wave (CW, distributed feedback pigtailed diode laser was used as the excitation source and H2O was selected as the target analyte. Two kinds of quartz tuning forks (QTFs with a resonant frequency (f0 of 30.72 kHz and 38 kHz were employed for the first time as an acoustic wave transducer, respectively for QEPAS instead of a standard QTF with a f0 of 32.768 kHz. The QEPAS sensor performance using the three different QTFs was experimentally investigated and theoretically analyzed. A minimum detection limit of 5.9 ppmv and 4.3 ppmv was achieved for f0 of 32.768 kHz and 30.72 kHz, respectively.

UARS Halogen Occultation Experiment (HALOE) Level 2 V001

Data.gov (United States)

National Aeronautics and Space Administration — The HALOE home page on the WWW is http://haloe.gats-inc.com/home/index.php The Halogen Occultation Experiment (HALOE) on NASA's Upper Atmosphere Research Satellite...

Biogas from MSW landfill: Composition and determination of chlorine content with the AOX (adsorbable organically bound halogens) technique

International Nuclear Information System (INIS)

Rey, M.D.; Font, R.; Aracil, I.

2013-01-01

An exhaustive characterization of the biogas from some waste disposal facilities has been carried out. The analysis includes the main components (methane, carbon dioxide, nitrogen and oxygen) as well as trace components such as hydrogen sulphide, ammonia and VOCs (volatile organic compounds) including siloxanes and halogenated compounds. VOCs were measured by GC/MS (Gas Chromatography/Mass Spectrometry) using two different procedures: thermal desorption of the Tenax TA and Carbotrap 349 tubes and SPME (Solid Phase Micro-Extraction). A method has been established to measure the total halogen content of the biogas with the AOX (adsorbable organically bound halogens) technique. The equipment used to analyze the samples was a Total Organic Halogen Analyzer (TOX-100). Similar results were obtained when comparing the TOX (Total Organic Halogen) values with those obtained by GC/MS. The halogen content in all the samples was under 22 mg Cl/Nm 3 which is below the limit of 150 mg/Nm 3 proposed in the Spanish Regulations for any use of the biogas. The low chlorine content in the biogas studied, as well as the low content of other trace compounds, makes it suitable for use as a fuel for electricity generating engines

Estimating Quartz Reserves Using Compositional Kriging

Directory of Open Access Journals (Sweden)

J. Taboada

2013-01-01

Full Text Available The aim of this study was to determine spatial distribution and volume of four commercial quartz grades, namely, silicon metal, ferrosilicon, aggregate, and kaolin (depending on content in impurities in a quartz seam. The chemical and mineralogical composition of the reserves in the seam were determined from samples collected from outcrops, blasting operations, and exploratory drilling, and compositional kriging was used to calculate the volume and distribution of the reserves. A more accurate knowledge of the deposit ensures better mine planning, leading to higher profitability and an improved relationship with the environment.

Refractometry characteristics of α-quartz after neutron irradiation

International Nuclear Information System (INIS)

Abdkadyrova, I.Kh.

1997-01-01

Lattice structure distortions in irradiated crystalline quartz were studied by refractometry methods. The refractometry constants of α-quartz for the flux of fast neutrons 10 18 - 10 21 neutron/cm 2 were calculated. The critical kinetics of this constants at the phase transformation is observed.(author). 5 refs., 1 fig

Are superhalogens without halogen ligand capable of transcending traditional halogen-based superhalogens? Ab initio case study of binuclear anions based on pseudohalogen ligand

International Nuclear Information System (INIS)

Li, Jin-Feng; Sun, Yin-Yin; Li, Miao-Miao; Li, Jian-Li; Yin, Bing; Bai, Hongcun

2015-01-01

The superhalogen properties of polynuclear structures without halogen ligand are theoretically explored here for several [M 2 (CN) 5 ] −1 (M =  Ca, Be) clusters. At CCSD(T) level, these clusters have been confirmed to be superhalogens due to their high vertical electron detachment energies (VDE). The largest one is 9.70 eV for [Ca 2 (CN) 5 ] −1 which is even higher than those of corresponding traditional structures based on fluorine or chlorine ligands. Therefore the superhalogens stronger than the traditional halogen-based structures could be realized by ligands other than halogen atoms. Compared with CCSD(T), outer valence Green’s function (OVGF) method either overestimates or underestimates the VDEs for different structures while MP2 results are generally consistent in the aspect of relative values. The extra electrons of the highest VDE anions here aggregate on the bridging CN units with non-negligible distribution occurring on other CN units too. These two features lower both the potential and kinetic energies of the extra electron respectively and thus lead to high VDE. Besides superhalogen properties, the structures, relative stabilities and thermodynamic stabilities with respect to the detachment of cyanide ligand were also investigated. The sum of these results identifies the potential of polynuclear structures with pseudohalogen ligand as suitable candidates with enhanced superhalogens properties

Are superhalogens without halogen ligand capable of transcending traditional halogen-based superhalogens? Ab initio case study of binuclear anions based on pseudohalogen ligand

Energy Technology Data Exchange (ETDEWEB)

Li, Jin-Feng; Sun, Yin-Yin; Li, Miao-Miao; Li, Jian-Li; Yin, Bing, E-mail: rayinyin@nwu.edu.cn [MOE Key Laboratory of Synthetic and Natural Functional Molecule Chemistry, Shaanxi Key Laboratory of Physico-Inorganic Chemistry, College of Chemistry and Materials Science, Northwest University, Xi’an 710069 (China); Bai, Hongcun [Key Laboratory of Energy Source and Chemical Engineering, Ningxia University, Yinchuan, Ningxia 750021 (China)

2015-06-15

The superhalogen properties of polynuclear structures without halogen ligand are theoretically explored here for several [M{sub 2}(CN){sub 5}]{sup −1} (M =  Ca, Be) clusters. At CCSD(T) level, these clusters have been confirmed to be superhalogens due to their high vertical electron detachment energies (VDE). The largest one is 9.70 eV for [Ca{sub 2}(CN){sub 5}]{sup −1} which is even higher than those of corresponding traditional structures based on fluorine or chlorine ligands. Therefore the superhalogens stronger than the traditional halogen-based structures could be realized by ligands other than halogen atoms. Compared with CCSD(T), outer valence Green’s function (OVGF) method either overestimates or underestimates the VDEs for different structures while MP2 results are generally consistent in the aspect of relative values. The extra electrons of the highest VDE anions here aggregate on the bridging CN units with non-negligible distribution occurring on other CN units too. These two features lower both the potential and kinetic energies of the extra electron respectively and thus lead to high VDE. Besides superhalogen properties, the structures, relative stabilities and thermodynamic stabilities with respect to the detachment of cyanide ligand were also investigated. The sum of these results identifies the potential of polynuclear structures with pseudohalogen ligand as suitable candidates with enhanced superhalogens properties.

Self-assembly of iodine in superfluid helium droplets. Halogen bonds and nanocrystals

Energy Technology Data Exchange (ETDEWEB)

He, Yunteng; Zhang, Jie; Lei, Lei; Kong, Wei [Department of Chemistry, Oregon State University, Corvallis, OR (United States)

2017-03-20

We present evidence of halogen bond in iodine clusters formed in superfluid helium droplets based on results from electron diffraction. Iodine crystals are known to form layered structures with intralayer halogen bonds, with interatomic distances shorter than the sum of the van der Waals radii of the two neighboring atoms. The diffraction profile of dimer dominated clusters embedded in helium droplets reveals an interatomic distance of 3.65 Aa, much closer to the value of 3.5 Aa in iodine crystals than to the van der Waals distance of 4.3 Aa. The profile from larger iodine clusters deviates from a single layer structure; instead, a bi-layer structure qualitatively fits the experimental data. This work highlights the possibility of small halogen bonded iodine clusters, albeit in a perhaps limited environment of superfluid helium droplets. The role of superfluid helium in guiding the trapped molecules into local potential minima awaits further investigation. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Dependence of red thermoluminescence on Eu-anomaly in natural quartzes

Energy Technology Data Exchange (ETDEWEB)

Hashimoto, T; Yokosaka, K; Notoya, S; Ojima, T; Sakaue, S [Niigata Univ. (Japan). Faculty of Science

1993-04-01

The causes of red colour thermoluminescence (RTL) from natural quartz have been sought in the presence of impurity elements. Some impurities in 31 varieties of natural quartz extracts, determined by a neutron activation analysis, have been examined with respect to a meaningful correlation of the RTL to the total detectable TL strength. Generally, the higher impurity contents were found in quartz of volcanic origin, which always emits purely RTL colour, whereas the lower impurities were usually detected in hydrothermal quartz, which emits purely blue TL (BTL) in all absorbed doses. Among the impurities, the middle REE (rare earth elements), involving Eu and Sm, particularly offered considerable correlation with RTL emission with the exception of pegmatite quartz. It was found from the chondrite-normalized REE patterns that a positive Eu anomaly or flattened Eu distribution gave rise to relatively high RTL proportions, while a negative Eu anomaly always showed extremely weak RTL intensity. Thus, it was concluded that the Eu[sup 3+], formed from the oxidizable surrounding or high oxygen fugacity relative to a Cl chondrite formation, is strongly related to the RTL intensity in natural quartz. (author).

Competition of hydrogen bonds and halogen bonds in complexes of hypohalous acids with nitrogenated bases.

Science.gov (United States)

Alkorta, Ibon; Blanco, Fernando; Solimannejad, Mohammad; Elguero, Jose

2008-10-30

A theoretical study of the complexes formed by hypohalous acids (HOX, X = F, Cl, Br, I, and At) with three nitrogenated bases (NH 3, N 2, and NCH) has been carried out by means of ab initio methods, up to MP2/aug-cc-pVTZ computational method. In general, two minima complexes are found, one with an OH...N hydrogen bond and the other one with a X...N halogen bond. While the first one is more stable for the smallest halogen derivatives, the two complexes present similar stabilities for the iodine case and the halogen-bonded structure is the most stable one for the hypoastatous acid complexes.

Formation of cogenetic quartz and nepheline syenites

Science.gov (United States)

Foland, K. A.; Landoll, J. D.; Henderson, C. M. B.; Chen, Jiangfeng

1993-02-01

Understanding the processes involved in the formation of cogenetic silica-undersaturated and silica-saturated felsic rocks in alkaline igneous complexes has been a long-standing enigma because of constraints imposed by phase equilibria relationships. This problem is discussed in general drawing upon relationships at two magmatic centers: Marangudzi in Zimbabwe and Mt. Brome in Quebec, Canada. At each locality, cogenetic quartz and nepheline syenites appear to be derived from common critically undersaturated magmas. Strontium and neodymium isotope results indicate that quartz syenites bear the signatures of substantial amounts of crustal assimilation whereas nepheline syenites lack or display lesser effects. In the model outlined, quartz syenite melts develop from felsic silica undersaturated magmas by assimilation of granitic crust coupled with fractional crystallization whereas nepheline syenites form without large amounts of contamination. This model is compatible with the constraints imposed by phase equilibria.

Ab Initio Calculations on Halogen Bond Between N-Br and Electron-donating Groups

Institute of Scientific and Technical Information of China (English)

WANG Yan-hua; CHEN Xue-song; ZOU Jian-wei; YU Qing-sen

2007-01-01

Ab initio calculations of complexes formed between N-bromosuccinimide and a series of electron-donating groups were performed at the level of MP2/Lanl2DZ* to gain a deeper insight into the nature of the N-Br halogen stronger halogen-bonding complex than the C-Br. A comparison of neutral hydrogen bond complex series reveals that the electron-donating capacities of the atoms decrease in the order, N＞O＞S; O(sp3)＞O(sp2), which is adequate for the C-Br halogen bonding. Interaction energies, in conjunction with the geometrical parameters show that the affinitive capacity of trihalide anions X-3 with N-bromosuccinimide are markedly lower than that of the corresponding X- with N-bromosuccinimide, even lower than those of neutral molecules with N-bromosuccinimide. AIM analyses further confirmed the above results.

Selenium-Mediated Dehalogenation of Halogenated Nucleosides and its Relevance to the DNA Repair Pathway.

Science.gov (United States)

Mondal, Santanu; Manna, Debasish; Mugesh, Govindasamy

2015-08-03

Halogenated nucleosides can be incorporated into the newly synthesized DNA of replicating cells and therefore are commonly used in the detection of proliferating cells in living tissues. Dehalogenation of these modified nucleosides is one of the key pathways involved in DNA repair mediated by the uracil-DNA glycosylase. Herein, we report the first example of a selenium-mediated dehalogenation of halogenated nucleosides. We also show that the mechanism for the debromination is remarkably different from that of deiodination and that the presence of a ribose or deoxyribose moiety in the nucleosides facilitates the deiodination. The results described herein should help in understanding the metabolism of halogenated nucleosides in DNA and RNA. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Identification of color development potential of quartz by Raman spectroscopy

International Nuclear Information System (INIS)

Alkmim, Danielle G.; Lameiras, Fernando S.; Almeida, Frederico O.T.

2013-01-01

Colorless quartz is usually exposed to ionizing radiation (gamma rays or high energy electron beams) to acquire different colors for jewelry. Color development is due to the presence of traces of some elements such as aluminum, iron, hydrogen, lithium, or sodium. Most quartz crystals are extracted colorless from nature and it is necessary to separate those that can develop colors from those that cannot. Irradiation tests can be used to accomplish this separation, but they take a long time. Infrared signature of colorless quartz can also be used. However, infrared spectroscopy is quite expensive, especially when using portable devices. Raman spectroscopy is now available as an inexpensive and portable technique that could provide identification of the samples of colorless quartz still in the field, facilitating the prediction for their economic exploitation. In addition, Raman spectroscopy usually requires a minimum or no sample preparation. This paper presents an investigation of the feasibility of using Raman spectroscopy as a substitute for infrared spectroscopy to predict the potential for color development of quartz. A band at 3595 cm -1 in the Raman shift spectrum was observed only along the c axis of a prasiolite excited by a high power 514 nm laser. This band was not observed in quartz samples that do not develop color after irradiation. Further studies are required to identify the potential for color development by Raman spectroscopy of other types of colorless quartz. (author)

Radioluminescence of synthetic quartz related to alkali ions

Energy Technology Data Exchange (ETDEWEB)

Martini, M., E-mail: m.martini@unimib.it [Dipartimento di Scienza dei Materiali, Universita degli Studi di Milano Bicocca, Via Cozzi 53, I-20125 Milano (Italy); INFN-Sezione di Milano Bicocca, Via Cozzi 53, I-20125 Milano (Italy); Fasoli, M. [Dipartimento di Scienza dei Materiali, Universita degli Studi di Milano Bicocca, Via Cozzi 53, I-20125 Milano (Italy); Galli, A. [Dipartimento di Scienza dei Materiali, Universita degli Studi di Milano Bicocca, Via Cozzi 53, I-20125 Milano (Italy); Istituto di Fotonica e Nanostrutture, IFN-CNR (Italy); Villa, I. [Dipartimento di Scienza dei Materiali, Universita degli Studi di Milano Bicocca, Via Cozzi 53, I-20125 Milano (Italy); Guibert, P. [IRAMAT-CRP2A (Institut de recherche sur les Archeomateriaux), UMR no. 5060, CNRS-Universite Bordeaux III, F-33607 Pessac (France)

2012-04-15

The radioluminescence (RL) of synthetic quartzes (GEMMA Quartz and Crystal Company) has been measured at room temperature. Some samples were treated by electrodiffusion ('sweeping') in order to change the concentrations of alkali ions, mainly Li{sup +} and Na{sup +}, which in quartz are known to be linked to Al ions, substitutional for Si ions. The RL emission spectra show evidence of a role of alkali ions in affecting some specific emissions. All the spectra could be analysed as composed of four bands in the blue and UV region. Specifically, the well known blue emission at around 470 nm was seen to be composed by two bands at 430 nm (2.86 eV) and at 485 nm (2.53 eV). Effects of irradiation, during the RL measurements, were clearly seen only in the 'Li swept in' sample, namely an increase in the 485 nm band intensity and a decrease in the 430 nm band one. The previously reported UV emission was detected at 355 nm (3.44 eV) in all the samples, being the most intense band in the 'swept out' sample. A further UV emission was detected at 315 nm (3.94 eV), more intense in untreated samples. Possible assignments of the detected emission bands are discussed in relation to the defects of quartz, specifically focusing on the Al centres that are most affected by sweeping procedures. - Highlights: Black-Right-Pointing-Pointer Contribution to the understanding of relationships between defects in quartz and luminescence emissions. Black-Right-Pointing-Pointer Role of charge compensators at substitutional Al sites in the optical properties of quartz. Black-Right-Pointing-Pointer Evidence of the double nature of the 'blue emission' (around 470 nm).

Benchmark Calculations of Noncovalent Interactions of Halogenated Molecules

Czech Academy of Sciences Publication Activity Database

Řezáč, Jan; Riley, Kevin Eugene; Hobza, Pavel

2012-01-01

Roč. 8, č. 11 (2012), s. 4285-4292 ISSN 1549-9618 R&D Projects: GA ČR GBP208/12/G016 Institutional support: RVO:61388963 Keywords : halogenated molecules * noncovalent interactions * benchmark calculations Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.389, year: 2012

Polar Flattening and the Strength of Halogen Bonding

Czech Academy of Sciences Publication Activity Database

Sedlák, Robert; Kolář, Michal H.; Hobza, Pavel

2015-01-01

Roč. 11, č. 10 (2015), s. 4727-4732 ISSN 1549-9618 R&D Projects: GA ČR GBP208/12/G016 Institutional support: RVO:61388963 Keywords : density functional theory * interaction energies * halogen bonding Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 5.301, year: 2015

Food irradiation dosimetry using thermoluminescence of quartz sand

International Nuclear Information System (INIS)

Khan, H.M.; Ehlermann, D.A.E.

1993-01-01

Thermoluminescence of quartz sand, which is inert and concomitant to several food materials, has been investigated for applications in food irradiation dosimetry and detection of irradiated foods. The glow curves consist of at least three overlapping peaks from 100 to 420 C. The peak at lower temperature is not stable and decays quickly at room temperature. However, the peaks at higher temperature are stable and more useful for dosimetry work. The intensity of the peak at 360 C, measured using different optical filters, shows a linear response in the range of 0.05 to 23 kGy. Stability of these signals at different annealing temperatures has been investigated. Thermoluminescence from adhering minerals and contaminating dust in different food materials has been found useful for the detection of irradiation treatment. Since quartz is frequently one of these minerals, further computerized deconvolution of individual glow peaks from the complex glow curves of quartz sand was carried out which improves the dosimetric results. Possible applications of thermoluminescence of quartz sand in food irradiation dosimetry and detection of irradiated foods have been discussed. (orig.)

The Effect of Intermolecular Halogen Bond on 19F DNP Enhancement in 1, 4-Diiodotetrafluorobenzene/4-OH-TEMPO Supramolecular Assembly

Directory of Open Access Journals (Sweden)

GAO Shan

2017-12-01

Full Text Available Halogen bond, as hydrogen bond, is a non-covalent bond. Dynamic nuclear polarization (DNP technique has been used previously to study hydrogen bonds-mediated intermolecular interactions. However, no study has been carried out so far to study the halogen bond-mediated intermolecular interactions with DNP. In this work, 19F DNP polarization efficiency of the halogen bonds existing in supramolecular assembling by 4-OH-TEMPO and 1,4-diiodotetrafluorobenzene (DITFB was studied on a home-made DNP system. The formation of intermolecular halogen bonds appeared to increase 19F DNP polarization efficiency, suggesting that the spin-spin interactions among electrons were weakened by the halogen bonds, resulting in an increased T2e and a larger saturation factor.

Alpha efficiency determination for OSL of quartz extracted from Chinese loess

International Nuclear Information System (INIS)

Lai Zhongping; Zoeller, Ludwig; Fuchs, Markus; Brueckner, Helmut

2008-01-01

We report here the estimates of alpha efficiency for fine grain quartz extracted from Chinese loess using the SAR protocol. For the seven samples, the α-values range from 0.028 to 0.038 with an average of 0.035±0.001. The annealed quartz (450 deg. C, 45 min) has an α-value of 0.030±0.001 which is similar to the α-value of 0.029±0.001 for the non-annealed quartz extracts, suggesting that the α-value is independent of the quartz's thermal history for this sample. We suggest that an α-value of 0.035±0.003 can be adopted for quartz extracted from Chinese loess when calculating the environmental dose rate

Isomorphism of 2-methylnaphthalene and 2-halonaphthalenes as a revealer of a special interaction between methyl and halogen

Science.gov (United States)

Calvet, T.; Cuevas-Diarte, M. A.; Haget, Y.; Mondieig, D.; Kok, I. C.; Verdonk, M. L.; Van Miltenburg, J. C.; Oonk, H. A. J.

1999-03-01

The systems 2-methylnaphthalene+2-chloronaphthalene and 2-methylnaphthalene+2-bromonaphthalene belong to the exceptional group of binary systems where the formation of mixed crystals goes together with a solid-liquid phase diagram with a maximum. For these systems a thermodynamic analysis is presented which is based on new phase diagram and thermochemical data. The excess Gibbs energies, excess enthalpies, and excess entropies of the mixed crystalline state all are negative. These properties correspond to a net attraction between methyl and substituted halogen. Additional evidence of such an attraction is given by the outcome of a statistical search on intermolecular contacts, in the crystalline state of pure substances, among methyl+halogen, halogen+halogen, and methyl+methyl.

Activation analysis of high pure quartz used as packing materials

International Nuclear Information System (INIS)

Luknitskij, V.A.; Morozov, B.A.

1979-01-01

A γ-spectrometric technique of neutron activation determination of microelements in quartz tubes used as a packing material for irradiation in reactors is reported. The analysis of 29 micro-admixtures in quartz tubes of USSR brands ''spectrtosil'' and ''KV'' was carried out. The γ-spectra of ''KV'' quartz irradiated by thermal and epithermal neutrons are presented. The activation by epithermal neutrons provides an activity gain for the nuclei whose resonance integral is high enough as compared to the activation cross-section with regard to thermal neutrons. The activation by epithermal neutrons permits additional determination of W, Cd, V, Th, Mn and Ni and provides for a substantial decrease in the activity of 24 Na, 42 K, 140 La, 46 Sc, 141 Ce, 51 Cr, and 59 Fe, which hinder the determination of the above-mentioned elements. The microelement composition of Soviet-made quartz varieties is compared to that of foreign-made quartz brands

A systematic structural study of halogen bonding versus hydrogen bonding within competitive supramolecular systems

Directory of Open Access Journals (Sweden)

Christer B. Aakeröy

2015-09-01

Full Text Available As halogen bonds gain prevalence in supramolecular synthesis and materials chemistry, it has become necessary to examine more closely how such interactions compete with or complement hydrogen bonds whenever both are present within the same system. As hydrogen and halogen bonds have several fundamental features in common, it is often difficult to predict which will be the primary interaction in a supramolecular system, especially as they have comparable strength and geometric requirements. To address this challenge, a series of molecules containing both hydrogen- and halogen-bond donors were co-crystallized with various monotopic, ditopic symmetric and ditopic asymmetric acceptor molecules. The outcome of each reaction was examined using IR spectroscopy and, whenever possible, single-crystal X-ray diffraction. 24 crystal structures were obtained and subsequently analyzed, and the synthon preferences of the competing hydrogen- and halogen-bond donors were rationalized against a background of calculated molecular electrostatic potential values. It has been shown that readily accessible electrostatic potentials can offer useful practical guidelines for predicting the most likely primary synthons in these co-crystals as long as the potential differences are weighted appropriately.

High energy halogen atom reactions activated by nuclear transformations. Progress report, February 15-December 31, 1984

International Nuclear Information System (INIS)

1985-01-01

Energetic halogen atoms or ions, activated by various nuclear transformations are studied in gas, high pressure and condensed phase saturated and unsaturated hydrocarbons, halomethanes, and liquid and solid aqueous solutions of biomolecular and organic solutes in order to understand better the mechanisms and dynamics of high energy monovalent species. The experimental program and its goals remain the same, consisting of four interrelated areas: (1) The stereochemistry of energetic 18 F, /sup 34m/Cl, and 38 Cl substitution reactions with chiral molecules in the gas and condensed phase is studied. (2) The gas to condensed state transition in halogen high energy chemistry, involving energetic chlorine, bromine, and iodine reactions in halomethanes, saturated and unsaturated hydrocarbons and aqueous solutions of biomolecules and alkyl halides is being investigated in more detail. Current attention is given to defining the nature of the enhancement yields in the condensed phase. Specifically, energetic halogen reactions in liquid and frozen aqueous solutions or organic and biomolecular solutes are studied. (3) Reactions of bromine and iodine activated by isomeric transition with halogenated biomolecular and organic solutes in liquid and frozen aqueous solutions are being studied in an attempt to learn more about the activation events in the condensed phase. (4) The applications of hot chemistry techniques and theory to neutron activation analysis of biological systems are being continued. Current attention is given to developing procedures for trace molecular determinations in biological systems. The applications of hot halogen atoms as site indicators in liquid and frozen aqueous solutions of halogenated bases and nucleosides are currently being developed. 14 references

Construction of simple quartz crystal microbalance

Energy Technology Data Exchange (ETDEWEB)

Ristov, Milcho [Center of Energy, Informatics and Materials of the Macedonian Academy fo Science and Arts, Skopje (Macedonia, The Former Yugoslav Republic of); Mitrevski, Mitre [Institute of Physics, Faculty of natural Science and Mathematics, Ss Cyril and Methodius University, Skopje (Macedonia, The Former Yugoslav Republic of)

2003-07-01

A very simple Quartz Crystal Microbalance (QCM) was constructed for the measurement of thickness of chemically deposited thin films. QCM consisted of two active elements: one dual-gate MOSFET and one bipolar transistor, and as usually two AT-cut quartz crystal. The beat frequency oscillation generated as a result of loading of the sensor crystal by the deposited thin film, was measured by HP-multimeter, set as a low frequency meter. The sensitivity was found to be high and satisfactory for the study of growth rate of thin films, mainly deposited by methods of chemical deposition.

Construction of simple quartz crystal microbalance

International Nuclear Information System (INIS)

Ristov, Milcho; Mitrevski, Mitre

2002-01-01

A very simple Quartz Crystal Microbalance (QCM) was constructed for the measurement of thickness of chemically deposited thin films. QCM consisted of two active elements: one dual-gate MOSFET and one bipolar transistor, and as usually two AT-cut quartz crystal. The beat frequency oscillation generated as a result of loading of the sensor crystal by the deposited thin film, was measured by HP-multimeter, set as a low frequency meter. The sensitivity was found to be high and satisfactory for the study of growth rate of thin films, mainly deposited by methods of chemical deposition.

EPR investigation into the structure of boron-containing quartz glasses

International Nuclear Information System (INIS)

Amosov, A.V.; Bushmarin, D.B.; Prokhorova, T.I.; Yudin, D.M.

1975-01-01

Certain properties of boron-containing quartz glasses and the nature of occurrence of boron in the glass lattice are studied as functions of the method of alloying. The formation of three types of borate structural nodes (BO 4 , BO 3 and BO 4 -BO 3 ) in the lattice of quartz glasses is established. Alloying by boron oxide up to 3% (weight) increases the crystallization stability of quartz glasses, lowers down tsub(g) from 1220 to 950 deg C and does not affect the coefficient of thermal expansion. Low symmetry of borate structural nodes, following from the analysis of EPR spectra, confirms the literature data concerning the low symmetry of glass-forming polyhedrons in a quartz glass

Global impacts of tropospheric halogens (Cl, Br, I on oxidants and composition in GEOS-Chem

Directory of Open Access Journals (Sweden)

T. Sherwen

2016-09-01

Full Text Available We present a simulation of the global present-day composition of the troposphere which includes the chemistry of halogens (Cl, Br, I. Building on previous work within the GEOS-Chem model we include emissions of inorganic iodine from the oceans, anthropogenic and biogenic sources of halogenated gases, gas phase chemistry, and a parameterised approach to heterogeneous halogen chemistry. Consistent with Schmidt et al. (2016 we do not include sea-salt debromination. Observations of halogen radicals (BrO, IO are sparse but the model has some skill in reproducing these. Modelled IO shows both high and low biases when compared to different datasets, but BrO concentrations appear to be modelled low. Comparisons to the very sparse observations dataset of reactive Cl species suggest the model represents a lower limit of the impacts of these species, likely due to underestimates in emissions and therefore burdens. Inclusion of Cl, Br, and I results in a general improvement in simulation of ozone (O3 concentrations, except in polar regions where the model now underestimates O3 concentrations. Halogen chemistry reduces the global tropospheric O3 burden by 18.6 %, with the O3 lifetime reducing from 26 to 22 days. Global mean OH concentrations of 1.28  ×  106 molecules cm−3 are 8.2 % lower than in a simulation without halogens, leading to an increase in the CH4 lifetime (10.8 % due to OH oxidation from 7.47 to 8.28 years. Oxidation of CH4 by Cl is small (∼  2 % but Cl oxidation of other VOCs (ethane, acetone, and propane can be significant (∼  15–27 %. Oxidation of VOCs by Br is smaller, representing 3.9 % of the loss of acetaldehyde and 0.9 % of the loss of formaldehyde.

Thermodynamics parameters for binding of halogenated benzotriazole inhibitors of human protein kinase CK2α.

Science.gov (United States)

Winiewska, Maria; Kucińska, Katarzyna; Makowska, Małgorzata; Poznański, Jarosław; Shugar, David

2015-10-01

The interaction of human CK2α (hCK2α) with nine halogenated benzotriazoles, TBBt and its analogues representing all possible patterns of halogenation on the benzene ring of benzotriazole, was studied by biophysical methods. Thermal stability of protein-ligand complexes, monitored by calorimetric (DSC) and optical (DSF) methods, showed that the increase in the mid-point temperature for unfolding of protein-ligand complexes (i.e. potency of ligand binding to hCK2α) follow the inhibitory activities determined by biochemical assays. The dissociation constant for the ATP-hCK2α complex was estimated with the aid of microscale thermophoresis (MST) as 4.3±1.8 μM, and MST-derived dissociation constants determined for halogenated benzotriazoles, when converted according to known ATP concentrations, perfectly reconstruct IC50 values determined by the biochemical assays. Ligand-dependent quenching of tyrosine fluorescence, together with molecular modeling and DSC-derived heats of unfolding, support the hypothesis that halogenated benzotriazoles bind in at least two alternative orientations, and those that are efficient hCK2α inhibitors bind in the orientation which TBBt adopts in its complex with maize CK2α. DSC-derived apparent heat for ligand binding (ΔΔHbind) is driven by intermolecular electrostatic interactions between Lys68 and the triazole ring of the ligand, as indicated by a good correlation between ΔΔHbind and ligand pKa. Overall results, additionally supported by molecular modeling, confirm that a balance of hydrophobic and electrostatic interactions contribute predominantly (~40 kJ/mol), relative to possible intermolecular halogen/hydrogen bonding (less than 10 kJ/mol), in binding of halogenated benzotriazoles to the ATP-binding site of hCK2α. This article is part of a Special Issue entitled: Inhibitors of Protein Kinases. Copyright © 2015 Elsevier B.V. All rights reserved.

Radiolysis of aqueous solutions of nucleosides halogenated at the sugar moiety

Energy Technology Data Exchange (ETDEWEB)

Hissung, A; Isildar, M; von Sonntag, C [Max-Planck-Institut fuer Kohlenforschung, Muelheim an der Ruhr (Germany, F.R.). Inst. fuer Strahlenforschung; Witzel, H [Biochemisches Institut der Westfaelischen Wilhelms-Universitaet, Muenster, West Germany

1981-02-01

The pulse radiolysis of aqueous solutions of nucleosides halogenated at the sugar moiety (2'-bromo-2'-deoxyuridine 4, 3'-deoxy-3'-iodothymidine 5, 5'-deoxy-5'-iodouridine 6) has been studied. G(Hal) were determined by conductometry varying the experimental conditions (pH, saturation with Ar, N/sub 2/O or air, addition of t-butanol). The results indicate that solvated electrons both add to the nucleobases and eliminate halogen ions from the halogenated sugar moiety. In the case of 4(and possibly of 5) the radical anion of the base transfers (k approximately 10/sup 5/s/sup -1/) an electron to the sugar-bound halogen atom thus cleaving the C-Hal bond. In competition with this reaction there is a protonation of the radical anion of the base by protons and by water. For the latter reaction constant of k = 5 x 10/sup 3/ M/sup -1/s/sup -1/ was estimated. Compound 4 has also been investigated by product analysis after 60-Co-..gamma..-irradiation. In aerated solutions erythrose is formed with a G-value of 0.12. Its precursor radical is the 2'-radical generated from 4 by dissociative electron capture which reacts with O/sub 2/ to the corresponding peroxyl radical. Erythrose is formed after a sequence of reactions, one of which involves the scission of the C-1'-C-2'bond. Under this condition G(HBr) as measured by pulse radiolysis is 0.8. Thus erythrose is formed in 15 per cent yield with respect to its precursor radical. This result is of importance in assessing the precursor radical of a similar product observed in irradiated DNA.

Radiolysis of aqueous solutions of nucleosides halogenated at the sugar moiety

International Nuclear Information System (INIS)

Hissung, A.; Isildar, M.; Sonntag, C. von; Witzel, H.

1981-01-01

The pulse radiolysis of aqueous solutions of nucleosides halogenated at the sugar moiety (2'-bromo-2'-deoxyuridine 4, 3'-deoxy-3'-iodothymidine 5, 5'-deoxy-5'-iodouridine 6) has been studied. G(Hal) were determined by conductometry varying the experimental conditions (pH, saturation with Ar, N 2 O or air, addition of t-butanol). The results indicate that solvated electrons both add to the nucleobases and eliminate halogen ions from the halogenated sugar moiety. In the case of 4(and possibly of 5) the radical anion of the base transfers (k approximately 10 5 s -1 ) an electron to the sugar-bound halogen atom thus cleaving the C-Hal bond. In competition with this reaction there is a protonation of the radical anion of the base by protons and by water. For the latter reaction constant of k = 5 x 10 3 M -1 s -1 was estimated. Compound 4 has also been investigated by product analysis after 60-Co-γ-irradiation. In aerated solutions erythrose is formed with a G-value of 0.12. Its precursor radical is the 2'-radical generated from 4 by dissociative electron capture which reacts with O 2 to the corresponding peroxyl radical. Erythrose is formed after a sequence of reactions, one of which involves the scission of the C-1'-C-2'bond. Under this condition G(HBr) as measured by pulse radiolysis is 0.8. Thus erythrose is formed in 15 per cent yield with respect to its precursor radical. This result is of importance in assessing the precursor radical of a similar product observed in irradiated DNA. (author)

Halogen bond preferences of thiocyanate ligand coordinated to Ru(II) via sulphur atom

Science.gov (United States)

Ding, Xin; Tuikka, Matti; Hirva, Pipsa; Haukka, Matti

2017-09-01

Halogen bonding between [Ru(bpy)(CO)2(S-SCN)2] (bpy = 2,2'-bipyridine), I2 was studied by co-crystallising the metal compound and diiodine from dichloromethane. The only observed crystalline product was found to be [Ru(bpy)(CO)2(S-SCN)2]ṡI2 with only one NCSṡṡṡI2 halogen bond between I2 and the metal coordinated S atom of one of the thiocyanate ligand. The dangling nitrogen atoms were not involved in halogen bonding. However, computational analysis suggests that there are no major energetic differences between the NCSṡṡṡI2 and SCNṡṡṡI2 bonding modes. The reason for the observed NCSṡṡṡI2 mode lies most probably in the more favourable packing effects rather than energetic preferences between NCSṡṡṡI2 and SCNṡṡṡI2 contacts.

Soil chemistry in lithologically diverse datasets: the quartz dilution effect

Science.gov (United States)

Bern, Carleton R.

2009-01-01

National- and continental-scale soil geochemical datasets are likely to move our understanding of broad soil geochemistry patterns forward significantly. Patterns of chemistry and mineralogy delineated from these datasets are strongly influenced by the composition of the soil parent material, which itself is largely a function of lithology and particle size sorting. Such controls present a challenge by obscuring subtler patterns arising from subsequent pedogenic processes. Here the effect of quartz concentration is examined in moist-climate soils from a pilot dataset of the North American Soil Geochemical Landscapes Project. Due to variable and high quartz contents (6.2–81.7 wt.%), and its residual and inert nature in soil, quartz is demonstrated to influence broad patterns in soil chemistry. A dilution effect is observed whereby concentrations of various elements are significantly and strongly negatively correlated with quartz. Quartz content drives artificial positive correlations between concentrations of some elements and obscures negative correlations between others. Unadjusted soil data show the highly mobile base cations Ca, Mg, and Na to be often strongly positively correlated with intermediately mobile Al or Fe, and generally uncorrelated with the relatively immobile high-field-strength elements (HFS) Ti and Nb. Both patterns are contrary to broad expectations for soils being weathered and leached. After transforming bulk soil chemistry to a quartz-free basis, the base cations are generally uncorrelated with Al and Fe, and negative correlations generally emerge with the HFS elements. Quartz-free element data may be a useful tool for elucidating patterns of weathering or parent-material chemistry in large soil datasets.

Organohalide respiration in pristine environments: implications for the natural halogen cycle.

Science.gov (United States)

Atashgahi, Siavash; Häggblom, Max M; Smidt, Hauke

2018-03-01

Halogenated organic compounds, also termed organohalogens, were initially considered to be of almost exclusively anthropogenic origin. However, over 5000 naturally synthesized organohalogens are known today. This has also fuelled the hypothesis that the natural and ancient origin of organohalogens could have primed development of metabolic machineries for their degradation, especially in microorganisms. Among these, a special group of anaerobic microorganisms was discovered that could conserve energy by reducing organohalogens as terminal electron acceptor in a process termed organohalide respiration. Originally discovered in a quest for biodegradation of anthropogenic organohalogens, these organohalide-respiring bacteria (OHRB) were soon found to reside in pristine environments, such as the deep subseafloor and Arctic tundra soil with limited/no connections to anthropogenic activities. As such, accumulating evidence suggests an important role of OHRB in local natural halogen cycles, presumably taking advantage of natural organohalogens. In this minireview, we integrate current knowledge regarding the natural origin and occurrence of industrially important organohalogens and the evolution and spread of OHRB, and describe potential implications for natural halogen and carbon cycles. © 2017 Society for Applied Microbiology and John Wiley & Sons Ltd.

Photofragmentation spectra of halogenated methanes in the VUV photon energy range

Energy Technology Data Exchange (ETDEWEB)

Cartoni, Antonella, E-mail: antonella.cartoni@uniroma1.it [Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, P.le Aldo Moro 5, Roma 00185 (Italy); Bolognesi, Paola; Fainelli, Ettore; Avaldi, Lorenzo [CNR-IMIP, Area della Ricerca di Roma 1, Monterotondo Scalo (Rm) 00015 (Italy)

2014-05-14

In this paper an investigation of the photofragmentation of dihalomethanes CH{sub 2}X{sub 2} (X = F, Cl, Br, I) and chlorinated methanes (CH{sub n}Cl{sub 4−n} with n = 0–3) with VUV helium, neon, and argon discharge lamps is reported and the role played by the different halogen atoms is discussed. Halogenated methanes are a class of molecules used in several fields of chemistry and the study of their physical and chemical proprieties is of fundamental interest. In particular their photodissociation and photoionization are of great importance since the decomposition of these compounds in the atmosphere strongly affects the environment. The results of the present work show that the halogen-loss is the predominant fragmentation channel for these molecules in the VUV photon energy range and confirm their role as reservoir of chlorine, bromine, and iodine atoms in the atmosphere. Moreover, the results highlight the peculiar feature of CH{sub 2}F{sub 2} as a source of both fluorine and hydrogen atoms and the characteristic formation of I{sub 2}{sup +} and CH{sub 2}{sup +} ions from the photofragmentation of the CH{sub 2}I{sub 2} molecule.

Mutagenic activity of halogenated propanes and propenes: effect of bromine and chlorine positioning.

Science.gov (United States)

Låg, M; Omichinski, J G; Dybing, E; Nelson, S D; Søderlund, E J

1994-10-01

A series of halogenated propanes and propenes were studied for mutagenic effects in Salmonella typhimurium TA100 in the absence or presence of NADPH plus liver microsomes from phenobarbital-induced rats as an exogenous metabolism system. The cytotoxic and mutagenic effects of the halogenated propane 1,2-dibromo-3-chloropropane (DBCP) has previously been studied in our laboratories. These studies showed that metabolic activation of DBCP was required to exert its detrimental effects. All of the trihalogenated propane analogues were mutagenic when the microsomal activation system was included. The highest mutagenic activity was obtained with 1,2,3-tribromopropane, with approximately 50-fold higher activity than the least mutagenic trihalogenated propane, 1,2,3-trichloropropane. The order of mutagenicity was as follows: 1,2,3-tribromopropane > or = 1,2-dibromo- 3-chloropropane > 1,3-dibromo-2-chloropropane > or = 1,3-dichloro-2-bromopropane > 1-bromo-2,3-dichloropropane > 1,2,3-trichloropropane. Compared to DBCP, the dihalogenated propanes were substantially less mutagenic. Only 1,2-dibromopropane was mutagenic and its mutagenic potential was approximately 1/30 of that of DBCP. In contrast to DBCP, 1,2-dibromopropane showed similar mutagenic activity with and without the addition of an activation system. The halogenated propenes 2,3-dibromopropene and 2-bromo-3-chloropropene were mutagenic to the bacteria both in the absence and presence of the activation system, whereas 2,3-dichloropropene did not show any mutagenic effect. The large differences in mutagenic potential between the various halogenated propanes and propenes are proposed to be due to the formation of different possible proximate and ultimate mutagenic metabolites resulting from the microsomal metabolism of the various halogenated propanes and propenes, and to differences in the rate of formation of the metabolites. Pathways are proposed for the formation of genotoxic metabolites of di- and trihalogenated

Extending Halogen-based Medicinal Chemistry to Proteins: IODO-INSULIN AS A CASE STUDY.

Science.gov (United States)

El Hage, Krystel; Pandyarajan, Vijay; Phillips, Nelson B; Smith, Brian J; Menting, John G; Whittaker, Jonathan; Lawrence, Michael C; Meuwly, Markus; Weiss, Michael A

2016-12-30

Insulin, a protein critical for metabolic homeostasis, provides a classical model for protein design with application to human health. Recent efforts to improve its pharmaceutical formulation demonstrated that iodination of a conserved tyrosine (Tyr B26 ) enhances key properties of a rapid-acting clinical analog. Moreover, the broad utility of halogens in medicinal chemistry has motivated the use of hybrid quantum- and molecular-mechanical methods to study proteins. Here, we (i) undertook quantitative atomistic simulations of 3-[iodo-Tyr B26 ]insulin to predict its structural features, and (ii) tested these predictions by X-ray crystallography. Using an electrostatic model of the modified aromatic ring based on quantum chemistry, the calculations suggested that the analog, as a dimer and hexamer, exhibits subtle differences in aromatic-aromatic interactions at the dimer interface. Aromatic rings (Tyr B16 , Phe B24 , Phe B25 , 3-I-Tyr B26 , and their symmetry-related mates) at this interface adjust to enable packing of the hydrophobic iodine atoms within the core of each monomer. Strikingly, these features were observed in the crystal structure of a 3-[iodo-Tyr B26 ]insulin analog (determined as an R 6 zinc hexamer). Given that residues B24-B30 detach from the core on receptor binding, the environment of 3-I-Tyr B26 in a receptor complex must differ from that in the free hormone. Based on the recent structure of a "micro-receptor" complex, we predict that 3-I-Tyr B26 engages the receptor via directional halogen bonding and halogen-directed hydrogen bonding as follows: favorable electrostatic interactions exploiting, respectively, the halogen's electron-deficient σ-hole and electronegative equatorial band. Inspired by quantum chemistry and molecular dynamics, such "halogen engineering" promises to extend principles of medicinal chemistry to proteins. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Chiral halogenated Schiff base compounds: green synthesis, anticancer activity and DNA-binding study

Science.gov (United States)

Ariyaeifar, Mahnaz; Amiri Rudbari, Hadi; Sahihi, Mehdi; Kazemi, Zahra; Kajani, Abolghasem Abbasi; Zali-Boeini, Hassan; Kordestani, Nazanin; Bruno, Giuseppe; Gharaghani, Sajjad

2018-06-01

Eight enantiomerically pure halogenated Schiff base compounds were synthesized by reaction of halogenated salicylaldehydes with 3-Amino-1,2-propanediol (R or S) in water as green solvent at ambient temperature. All compounds were characterized by elemental analyses, NMR (1H and 13C), circular dichroism (CD) and FT-IR spectroscopy. FS-DNA binding studies of these compounds carried out by fluorescence quenching and UV-vis spectroscopy. The obtained results revealed that the ligands bind to DNA as: (Rsbnd ClBr) > (Rsbnd Cl2) > (Rsbnd Br2) > (Rsbnd I2) and (Ssbnd ClBr) > (Ssbnd Cl2) > (Ssbnd Br2) > (Ssbnd I2), indicating the effect of halogen on binding constant. In addition, DNA-binding constant of the Ssbnd and R-enantiomers are different from each other. The ligands can form halogen bonds with DNA that were confirmed by molecular docking. This method was also measured the bond distances and bond angles. The study of obtained data can have concluded that binding affinity of the ligands to DNA depends on strength of halogen bonds. The potential anticancer activity of ligands were also evaluated on MCF-7 and HeLa cancer cell lines by using MTT assay. The results showed that the anticancer activity and FS-DNA interaction is significantly dependent on the stereoisomers of Schiff base compounds as R-enantiomers displayed significantly higher activity than S-enantiomers. The molecular docking was also used to illustrate the specific DNA-binding of synthesized compounds and groove binding mode of DNA interaction was proposed for them. In addition, molecular docking results indicated that there are three types of bonds (Hsbnd and X-bond and hX-bond) between synthesized compounds and base pairs of DNA.

Detection of halogenated flame retardants in polyurethane foam by particle induced X-ray emission

International Nuclear Information System (INIS)

Maley, Adam M.; Falk, Kyle A.; Hoover, Luke; Earlywine, Elly B.; Seymour, Michael D.; DeYoung, Paul A.; Blum, Arlene; Stapleton, Heather M.; Peaslee, Graham F.

2015-01-01

A novel application of particle-induced X-ray emission (PIXE) has been developed to detect the presence of chlorinated and brominated flame retardant chemicals in polyurethane foams. Traditional Gas Chromatography–Mass Spectrometry (GC–MS) methods for the detection and identification of halogenated flame retardants in foams require extensive sample preparation and data acquisition time. The elemental analysis of the halogens in polyurethane foam performed by PIXE offers the opportunity to identify the presence of halogenated flame retardants in a fraction of the time and sample preparation cost. Through comparative GC–MS and PIXE analysis of 215 foam samples, excellent agreement between the two methods was obtained. These results suggest that PIXE could be an ideal rapid screening method for the presence of chlorinated and brominated flame retardants in polyurethane foams

Detection of halogenated flame retardants in polyurethane foam by particle induced X-ray emission

Energy Technology Data Exchange (ETDEWEB)

Maley, Adam M.; Falk, Kyle A.; Hoover, Luke; Earlywine, Elly B.; Seymour, Michael D. [Department of Chemistry, Hope College, 35 E. 12th Street, Holland, MI 49423 (United States); DeYoung, Paul A. [Department of Physics, Hope College, 27 Graves Place, Holland, MI 49423 (United States); Blum, Arlene [Green Science Policy Institute, Box 5455, Berkeley, CA 94705 (United States); Stapleton, Heather M. [Nicholas School of the Environment, Duke University, LSRC Box 90328, Durham, NC 27708 (United States); Peaslee, Graham F., E-mail: peaslee@hope.edu [Department of Chemistry, Hope College, 35 E. 12th Street, Holland, MI 49423 (United States)

2015-09-01

A novel application of particle-induced X-ray emission (PIXE) has been developed to detect the presence of chlorinated and brominated flame retardant chemicals in polyurethane foams. Traditional Gas Chromatography–Mass Spectrometry (GC–MS) methods for the detection and identification of halogenated flame retardants in foams require extensive sample preparation and data acquisition time. The elemental analysis of the halogens in polyurethane foam performed by PIXE offers the opportunity to identify the presence of halogenated flame retardants in a fraction of the time and sample preparation cost. Through comparative GC–MS and PIXE analysis of 215 foam samples, excellent agreement between the two methods was obtained. These results suggest that PIXE could be an ideal rapid screening method for the presence of chlorinated and brominated flame retardants in polyurethane foams.

Importance of surface characteristics of QUARTZ DQ 12 for acute inflammation

Energy Technology Data Exchange (ETDEWEB)

Albrecht, C.; Becher, A.; Scins, R.P.F.; Hoehr, D.; Unfried, K.; Knaapen, A.M.; Borm, P.J.A. [Institut fuer medizinische Forschung (IUF), Duesseldorf (Germany)

2004-07-01

Although quartz is known to induce inflammation in rat lungs, mechanisms are not yet fully understood. The importance of particle surface characteristics was investigated in vivo after intratracheal instillation of different preparations of quartz in rat lungs. Three days after instillation of 2 mg DQ12 quartz, or DQ12 coated with polyvinylpyridine-N-oxide (PVNO) or Aluminium lactate (AL), lungs of female Wistar rats were lavaged in situ to determine markers of inflammation. Control rats received saline or the coating substances alone. DQ12 induced a marked inflammatory response, as indicated by a significant increase in the number of neutrophils and macrophages, as well as in the levels of b-glucuronidase and myeloperoxidase. None of these inflammatory markers was increased for both coated quartz preparations, with the exception of neutrophil influx which was also increased after treatment with AL quartz. Our results indicate that surface characteristics are important in the onset of quartz-induced lung inflammation which could imply a different development of persistent inflammation. This will be investigated in later follow-up time points of the same animal study. (orig.)

Quartz-Enhanced Photoacoustic Spectroscopy Sensor with a Small-Gap Quartz Tuning Fork

Directory of Open Access Journals (Sweden)

Yu-Fei Ma

2018-06-01

Full Text Available A highly sensitive quartz-enhanced photoacoustic spectroscopy (QEPAS sensor based on a custom quartz tuning fork (QTF with a small-gap of 200 μm was demonstrated. With the help of the finite element modeling (FEM simulation software COMSOL, the change tendency of the QEPAS signal under the influence of the laser beam vertical position and the length of the micro-resonator (mR were calculated theoretically. Water vapor (H2O was selected as the target analyte. The experimental results agreed well with those of the simulation, which verified the correctness of the theoretical model. An 11-fold signal enhancement was achieved with the addition of an mR with an optimal length of 5 mm in comparison to the bare QTF. Finally, the H2O-QEPAS sensor, which was based on a small-gap QTF, achieved a minimum detection limit (MDL of 1.3 ppm, indicating an improvement of the sensor performance when compared to the standard QTF that has a gap of 300 μm.

Properties and behavior of quartz for the silicon process

Energy Technology Data Exchange (ETDEWEB)

Aasly, Kurt

2008-07-01

This PhD-thesis is a result of the study on important properties of quartz as a raw material for the metallurgical production of ferrosilicon and silicon metal. This includes defining mechanical properties important for the size reduction experienced during transport and storage and thermo-mechanical properties of quartz that is important for how the quartz reacts to the high temperatures experienced as it is charged on the furnace. Additionally, softening properties of quartz have been briefly discussed in some of the papers. Another important goal has been to test analytical and experimental methods for investigating the various properties. The investigations of important factors for the mechanical properties of ores and industrial minerals have been carried out as a literature study. The mining operation and transport from mine to smelter has been discussed and several factors that are significant for achieving best possible mechanical properties of the quartz have been identified. The most important factors are related to production in the mine and processing plant, which should be carefully planned to minimize the amount of blast-induced damage in the rock and thus achieve the best possible mechanical strength of the raw material. The amount of fines can be minimized by controlling the handling of the raw materials during the transport and storage. It is especially important to avoid high drops, both high single drops and accumulated height of all the drops in total. Investigations of the thermo-mechanical properties of quartz have been carried out by using different experimental and characterization methods. The petrographic investigations of the raw materials by polarized light microscopy have been important. Thermo-mechanical investigations have been high-temperature microthermometry and shock heating of quartz samples in an induction furnace with subsequent investigations of the heated material. The subsequent investigation included polarized- and

Can Halogen Enrichment in Reduced Enstatite Chondrites Provide Clues to Volatile Accretion in the Early Earth?

Science.gov (United States)

Clay, P. L.; Burgess, R.; Busemann, H.; Ruzié, L.; Joachim, B.; Ballentine, C.

2013-12-01

Understanding how the Earth obtained and ultimately retained its volatiles is important for our overall understanding of large scale planetary evolution. Numerous models exist for the heterogeneous accretion of volatiles to early Earth, but accounting for all elements through accretion of typical planetary building blocks (e.g., CI chondrites) is difficult. Proto-planetary collisions resulting in the accretion of volatile-poor material under reducing conditions followed by accretion of volatile-rich material under oxidizing conditions has been suggested in such models [e.g., 1]. The heavy halogens (Cl, Br and I), a group of moderately volatile elements, are excellent tracers of planetary processing due to their low abundance and incompatible nature. Therefore characterizing halogen abundance and distribution in materials that accreted to form the planets, e.g., primitive meteorites, is crucial. One group of primitive meteorites, the enstatite chondrites (EC's), are amongst the most reduced materials in the solar system as evidenced by their unique mineral assemblage. Yet despite forming under ultra-reducing conditions, they are enriched in the moderately volatile elements, such as the halogens. The ECs are of particular interest owing to their oxygen isotopic composition which plots along the terrestrial fractionation line, linking them isotopically to the Earth-Moon system. These samples can thus potentially provide clues on the accretion of moderately volatile element rich material under reducing conditions, such as it may have existed during the early stages of Earth's accretion. Chlorine, Br and I concentrations in ECs were determined through step-heating small neutron-irradiated samples (0.3 to 3.3 mg) and measured by mass spectrometry using the noble gas proxy isotopes 38ArCl/Cl, 80KrBr/Br and 128XeI/I. The EH chondrites are consistently enriched in the heavy halogens (up to 330 ppm Cl, 2290 ppb Br and 180 ppb I), compared to other ordinary and carbonaceous

Structure optimization and simulation analysis of the quartz micromachined gyroscope

Directory of Open Access Journals (Sweden)

Xuezhong Wu

2014-02-01

Full Text Available Structure optimization and simulation analysis of the quartz micromachined gyroscope are reported in this paper. The relationships between the structure parameters and the frequencies of work mode were analysed by finite element analysis. The structure parameters of the quartz micromachined gyroscope were optimized to reduce the difference between the frequencies of the drive mode and the sense mode. The simulation results were proved by testing the prototype gyroscope, which was fabricated by micro-electromechanical systems (MEMS technology. Therefore, the frequencies of the drive mode and the sense mode can match each other by the structure optimization and simulation analysis of the quartz micromachined gyroscope, which is helpful in the design of the high sensitivity quartz micromachined gyroscope.

Evaluation of 10 aliphatic halogenated hydrocarbons in the mouse bone marrow micronucleus test.

Science.gov (United States)

Crebelli, R; Carere, A; Leopardi, P; Conti, L; Fassio, F; Raiteri, F; Barone, D; Ciliutti, P; Cinelli, S; Vericat, J A

1999-03-01

Ten halogenated aliphatic hydrocarbons (carbon tetrachloride, 1-chlorohexane, 2,3-dichlorobutane, 1,2-dichloroethane, 1,2-dichloroethylene, 1,3-dichloropropane, hexachloroethane, 1,1,2-trichloroethane, 1,2,3-trichloropropane and 1,1,3-trichloropropene), previously assayed in genetic assays in fungi, were evaluated in the mouse bone marrow micronucleus test in order to assess their genotoxicity in vivo. All chemicals were administered once i.p. at 40 and 70-80% of their respective LD50 to male and female CD-1 mice, 24 and 48 h before killing. All treatments produced evident clinical symptoms, but no marked depression of bone marrow proliferation. No statistically significant increases in the incidence of micronucleated polychromatic erythrocytes over the control values were observed at any sampling time with any of the 10 halogenated hydrocarbons assayed. The comparison of the results obtained in this study with the findings provided by in vitro micronucleus assays on the same chemicals, reported by other authors, indicate that mouse bone marrow is weakly sensitive to the genotoxic effects induced by halogenated hydrocarbons in other test systems. This suggests that the role of such an assay in carcinogen screening may be questionable for this chemical class. An examination of mouse bone marrow micronucleus test results with the halogenated aliphatic hydrocarbons classified as carcinogens by IARC supports this conclusion.

Copper-catalyzed recycling of halogen activating groups via 1,3-halogen migration.

Science.gov (United States)

Grigg, R David; Van Hoveln, Ryan; Schomaker, Jennifer M

2012-10-03

A Cu(I)-catalyzed 1,3-halogen migration reaction effectively recycles an activating group by transferring bromine or iodine from a sp(2) to a benzylic carbon with concomitant borylation of the Ar-X bond. The resulting benzyl halide can be reacted in the same vessel under a variety of conditions to form an additional carbon-heteroatom bond. Cross-over experiments using an isotopically enriched bromide source support intramolecular transfer of Br. The reaction is postulated to proceed via a Markovnikov hydrocupration of the o-halostyrene, oxidative addition of the resulting Cu(I) complex into the Ar-X bond, reductive elimination of the new sp(3) C-X bond, and final borylation of an Ar-Cu(I) species to turn over the catalytic cycle.

[Near infrared light irradiator using halogen lamp].

Science.gov (United States)

Ide, Yasuo

2012-07-01

The practical electric light bulb was invented by Thomas Alva Edison in 1879. Halogen lamp is the toughest and brightest electric light bulb. With light filter, it is used as a source of near infrared light. Super Lizer and Alphabeam are made as near infrared light irradiator using halogen lamp. The light emmited by Super Lizer is linear polarized near infrared light. The wave length is from 600 to 1,600 nm and strongest at about 1,000 nm. Concerning Super Lizer, there is evidence of analgesic effects and normalization of the sympathetic nervous system. Super Lizer has four types of probes. SG type is used for stellate ganglion irradiation. B type is used for narrow area irradiation. C and D types are for broad area irradiation. The output of Alphabeam is not polarized. The wave length is from 700 to 1,600 nm and the strongest length is about 1,000nm. Standard attachment is used for spot irradiation. Small attachment is used for stellate ganglion irradiation. Wide attachment is used for broad area irradiation. The effects of Alphabeam are thought to be similar to that of Super Lizer.

Toroidal helical quartz forming machine

International Nuclear Information System (INIS)

Hanks, K.W.; Cole, T.R.

1977-01-01

The Scyllac fusion experimental machine used 10 cm diameter smooth bore discharge tubes formed into a simple toroidal shape prior to 1974. At about that time, it was discovered that a discharge tube was required to follow the convoluted shape of the load coil. A machine was designed and built to form a fused quartz tube with a toroidal shape. The machine will accommodate quartz tubes from 5 cm to 20 cm diameter forming it into a 4 m toroidal radius with a 1 to 5 cm helical displacement. The machine will also generate a helical shape on a linear tube. Two sets of tubes with different helical radii and wavelengths have been successfully fabricated. The problems encountered with the design and fabrication of this machine are discussed

A new equation of state for α-quartz

Science.gov (United States)

Magyar, Rudolph; Carpenter, John

2015-06-01

Quartz (SiO2) is often used as an optically transparent window for visar signals in shock experiments and is itself an active component of the experiments. Therefore, the shock response of quartz is an important input that must be known to high fidelity for precise measurement of other materials. We describe on-going work to develop a wide-range equation of state table that includes multiple phases and incorporates the latest high quality experimental and density functional theory (DFT) calculations. The emphasis in this work is the proper description of α-quartz along its principal Hugoniot through Stishovite and liquid phases. While molecular dissociation occurs at high pressures and temperatures, we find that an additional dissociation model is unnecessary. Although SiO2 possesses a number of solid phases, we restrict our focus to α-quartz and Stishovite as these two provide the density change along the Hugoniot path. We compare the model to recently measured data on Sandia's Z-machine. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE.

Tuning the electronic structure of graphene through alkali metal and halogen atom intercalation

Science.gov (United States)

Ahmad, Sohail; Miró, Pere; Audiffred, Martha; Heine, Thomas

2018-04-01

The deposition, intercalation and co-intercalation of heavy alkali metals and light halogens atoms in graphene mono- and bilayers have been studied using first principles density-functional calculations. Both the deposition and the intercalation of alkali metals gives rise to n-type doping due to the formation of M+-C- pairs. The co-intercalation of a 1:1 ratio of alkali metals and halogens derives into the formation of ionic pairs among the intercalated species, unaltering the electronic structure of the layered material.

Application of hydrometallurgy techniques in quartz processing and purification: a review

Science.gov (United States)

Lin, Min; Lei, Shaomin; Pei, Zhenyu; Liu, Yuanyuan; Xia, Zhangjie; Xie, Feixiang

2018-04-01

Although there have been numerous studies on separation and purification of metallic minerals by hydrometallurgy techniques, applications of the chemical techniques in separation and purification of non-metallic minerals are rarely reported. This paper reviews disparate areas of study into processing and purification of quartz (typical non-metallic ore) in an attempt to summarize current work, as well as to suggest potential for future consolidation in the field. The review encompasses chemical techniques of the quartz processing including situations, progresses, leaching mechanism, scopes of application, advantages and drawbacks of micro-bioleaching, high temperature leaching, high temperature pressure leaching and catalyzed high temperature pressure leaching. Traditional leaching techniques including micro-bioleaching and high temperature leaching are unequal to demand of modern glass industry for quality of quartz concentrate because the quartz products has to be further processed. High temperature pressure leaching and catalyzed high temperature pressure leaching provide new ways to produce high-grade quartz sand with only one process and lower acid consumption. Furthermore, the catalyzed high temperature pressure leaching realizes effective purification of quartz with extremely low acid consumption (no using HF or any fluoride). It is proposed that, by integrating the different chemical processes of quartz processing and expounding leaching mechanisms and scopes of application, the research field as a monopolized industry would benefit.

Identification of Color Development Potential of Quartz by Raman Spectroscopy

International Nuclear Information System (INIS)

Gomides Alkmim, D.; Soares Lameiras, F.

2013-01-01

Colorless quartz is usually exposed to ionizing radiation (gamma rays or high energy electron beams) in order to acquire different colors for jewelry. This is due to the presence of traces of some elements such as aluminum, iron, hydrogen, lithium, or sodium, which are responsible for the extrinsic colors developed after irradiation. Most quartz crystals are extracted colorless from nature and it is necessary to separate those that can develop colors from those that cannot. This can be done through irradiation tests, which take a long time. Other option is to collect the infrared signature of colorless quartz. However, infrared spectroscopic analysis is quite expensive, especially when using portable devices. Raman spectroscopy is now available as an inexpensive and portable technique that could provide identification of the samples of colorless quartz still in the field, facilitating the prediction for their economic exploitation. In addition, Raman spectroscopy usually requires a minimum or no sample preparation. This paper presents an investigation of the feasibility of using Raman spectroscopy as a substitute for infrared spectroscopy to predict the potential for color development of quartz. A band at 3595 cm -1 was observed, only along the c axis of a prasiolite excited by a high power 514 nm laser. This band was nor observed in quartz samples that do not develop color after irradiation, hence requiring further studies. (Author)

The anomalous halogen bonding interactions between chlorine and bromine with water in clathrate hydrates.

Science.gov (United States)

Dureckova, Hana; Woo, Tom K; Udachin, Konstantin A; Ripmeester, John A; Alavi, Saman

2017-10-13

Clathrate hydrate phases of Cl 2 and Br 2 guest molecules have been known for about 200 years. The crystal structure of these phases was recently re-determined with high accuracy by single crystal X-ray diffraction. In these structures, the water oxygen-halogen atom distances are determined to be shorter than the sum of the van der Waals radii, which indicates the action of some type of non-covalent interaction between the dihalogens and water molecules. Given that in the hydrate phases both lone pairs of each water oxygen atom are engaged in hydrogen bonding with other water molecules of the lattice, the nature of the oxygen-halogen interactions may not be the standard halogen bonds characterized recently in the solid state materials and enzyme-substrate compounds. The nature of the halogen-water interactions for the Cl 2 and Br 2 molecules in two isolated clathrate hydrate cages has recently been studied with ab initio calculations and Natural Bond Order analysis (Ochoa-Resendiz et al. J. Chem. Phys. 2016, 145, 161104). Here we present the results of ab initio calculations and natural localized molecular orbital analysis for Cl 2 and Br 2 guests in all cage types observed in the cubic structure I and tetragonal structure I clathrate hydrates to characterize the orbital interactions between the dihalogen guests and water. Calculations with isolated cages and cages with one shell of coordinating molecules are considered. The computational analysis is used to understand the nature of the halogen bonding in these materials and to interpret the guest positions in the hydrate cages obtained from the X-ray crystal structures.

Molecular Engineering of Non-Halogenated Solution-Processable Bithiazole based Electron Transport Polymeric Semiconductors

KAUST Repository

Fu, Boyi

2015-04-01

The electron deficiency and trans planar conformation of bithiazole is potentially beneficial for the electron transport performance of organic semiconductors. However, the incorporation of bithiazole into polymers through a facile synthetic strategy remains a challenge. Herein, 2,2’-bithiazole was synthesized in one step and copolymerized with dithienyldiketopyrrolopyrrole to afford poly(dithienyldiketopyrrolopyrrole-bithiazole), PDBTz. PDBTz exhibited electron mobility reaching 0.3 cm2V-1s-1 in organic field-effect transistor (OFET) configuration; this contrasts with a recently discussed isoelectronic conjugated polymer comprising an electron rich bithiophene and dithienyldiketopyrrolopyrrole, which displays merely hole transport characteristics. This inversion of charge carrier transport characteristics confirms the significant potential for bithiazole in the development of electron transport semiconducting materials. Branched 5-decylheptacyl side chains were incorporated into PDBTz to enhance polymer solubility, particularly in non-halogenated, more environmentally compatible solvents. PDBTz cast from a range of non-halogenated solvents exhibited film morphologies and field-effect electron mobility similar to those cast from halogenated solvents.

Molecular Engineering of Non-Halogenated Solution-Processable Bithiazole based Electron Transport Polymeric Semiconductors

KAUST Repository

Fu, Boyi; Wang, Cheng-Yin; Rose, Bradley Daniel; Jiang, Yundi; Chang, Mincheol; Chu, Ping-Hsun; Yuan, Zhibo; Fuentes-Hernandez, Canek; Bernard, Kippelen; Bredas, Jean-Luc; Collard, David M.; Reichmanis, Elsa

2015-01-01

The electron deficiency and trans planar conformation of bithiazole is potentially beneficial for the electron transport performance of organic semiconductors. However, the incorporation of bithiazole into polymers through a facile synthetic strategy remains a challenge. Herein, 2,2’-bithiazole was synthesized in one step and copolymerized with dithienyldiketopyrrolopyrrole to afford poly(dithienyldiketopyrrolopyrrole-bithiazole), PDBTz. PDBTz exhibited electron mobility reaching 0.3 cm2V-1s-1 in organic field-effect transistor (OFET) configuration; this contrasts with a recently discussed isoelectronic conjugated polymer comprising an electron rich bithiophene and dithienyldiketopyrrolopyrrole, which displays merely hole transport characteristics. This inversion of charge carrier transport characteristics confirms the significant potential for bithiazole in the development of electron transport semiconducting materials. Branched 5-decylheptacyl side chains were incorporated into PDBTz to enhance polymer solubility, particularly in non-halogenated, more environmentally compatible solvents. PDBTz cast from a range of non-halogenated solvents exhibited film morphologies and field-effect electron mobility similar to those cast from halogenated solvents.

The Suitability Of Local Quartz Sand In The Production Of Bath Crucibles.

Directory of Open Access Journals (Sweden)

C. O. Okpanachi

2017-03-01

Full Text Available The suitability of local quartz sand in the production of bath crucibles is a study that was carried out in order to impart overall strength on bath crucibles hence reduce breakages during fettling. Therefore this research constitutes a study to enhance the efficiency of production of bath crucibles by addition of quartz sand in slip preparation. The steps taken in the beneficiation of quartz sand for the production of bath crucibles are comminution which entails crushing and milling classification washing liquid dispersion sizing and reduction of iron content by magnetic separation. The slip contains materials like plastic clay feldspar kaolin talc sodium silicate water quartz sand etc. These were all milled in the ball mill for slip production casting and fettling glazing and sintering to get final bath crucibles as the end products. Quartz sand is used in a variety of products essentially as raw material for the foundry casting and glass industries and also in chemicals water filtration and ceramics the heat resistance nature of quartz sand makes it an excellent refractory substance for these industrial processes. Slip can be prepared for production of bath crucibles without the inclusion of quartz sand however the addition of quartz sand is needed to improve the mechanical performance of the slip in the production of bath crucibles.

Mercury and halogens in coal: Chapter 2

Science.gov (United States)

Kolker, Allan; Quick, Jeffrey C.; Granite, Evan J.; Pennline, Henry W.; Senior, Constance L.

2014-01-01

Apart from mercury itself, coal rank and halogen content are among the most important factors inherent in coal that determine the proportion of mercury captured by conventional controls during coal combustion. This chapter reviews how mercury in coal occurs, gives available concentration data for mercury in U.S. and international commercial coals, and provides an overview of the natural variation in halogens that influence mercury capture. Three databases, the U.S. Geological Survey coal quality (USGS COALQUAL) database for in-ground coals, and the 1999 and 2010 U.S. Environmental Protection Agency (EPA) Information Collection Request (ICR) databases for coals delivered to power stations, provide extensive results for mercury and other parameters that are compared in this chapter. In addition to the United States, detailed characterization of mercury is available on a nationwide basis for China, whose mean values in recent compilations are very similar to the United States in-ground mean of 0.17 ppm mercury. Available data for the next five largest producers (India, Australia, South Africa, the Russian Federation, and Indonesia) are more limited and with the possible exceptions of Australia and the Russian Federation, do not allow nationwide means for mercury in coal to be calculated. Chlorine in coal varies as a function of rank and correspondingly, depth of burial. As discussed elsewhere in this volume, on a proportional basis, bromine is more effective than chlorine in promoting mercury oxidation in flue gas and capture by conventional controls. The ratio of bromine to chlorine in coal is indicative of the proportion of halogens present in formation waters within a coal basin. This ratio is relatively constant except in coals that have interacted with deep-basin brines that have reached halite saturation, enriching residual fluids in bromine. Results presented here help optimize mercury capture by conventional controls and provide a starting point for

Halogenated hydrocarbons - an environmental problem

Energy Technology Data Exchange (ETDEWEB)

Schoeler, H F; Thofern, E

1984-01-01

The paper provides a survey of the incidence of highly volatile halogenated hydrocarbons in ground, surface and drinking water as well as in the snows of Western Germany. Almost the entire production of chlorinated solvents is released into the environment. The absorption media are mostly soil, water and atmosphere. Whereas in the atmosphere elimination reactions take place, solvents that have passed the soil get into the ground water owing to their persistence and can cause considerable pollutions of drinking water. Moreover haloforms may occur in drinking water, which are produced during chlorine disinfection of pre-treated water.

Pulsed ESR measurements of oxygen deficient type centers in various quartz

International Nuclear Information System (INIS)

Yamanaka, C.; Kohno, H.; Ikeya, M.

1996-01-01

Phase-memory times T M for E'-centers in various quartz samples were measured by pulse-ESR. Manually ground quartz followed by γ-irradiation, α-irradiated quartz and that from a natural uranium deposit showed T M M of 15-18μs. Natural SiO 2 with dense spins, (∼ 3.96 Ga) and sandstone from an impact crater were also examined. (author)

Characterization of halogenated DBPs and identification of new DBPs trihalomethanols in chlorine dioxide treated drinking water with multiple extractions.

Science.gov (United States)

Han, Jiarui; Zhang, Xiangru; Liu, Jiaqi; Zhu, Xiaohu; Gong, Tingting

2017-08-01

Chlorine dioxide (ClO 2 ) is a widely used alternative disinfectant due to its high biocidal efficiency and low-level formation of trihalomethanes and haloacetic acids. A major portion of total organic halogen (TOX), a collective parameter for all halogenated DBPs, formed in ClO 2 -treated drinking water is still unknown. A commonly used pretreatment method for analyzing halogenated DBPs in drinking water is one-time liquid-liquid extraction (LLE), which may lead to a substantial loss of DBPs prior to analysis. In this study, characterization and identification of polar halogenated DBPs in a ClO 2 -treated drinking water sample were conducted by pretreating the sample with multiple extractions. Compared to one-time LLE, the combined four-time LLEs improved the recovery of TOX by 2.3 times. The developmental toxicity of the drinking water sample pretreated with the combined four-time LLEs was 1.67 times higher than that pretreated with one-time LLE. With the aid of ultra-performance liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry, a new group of polar halogenated DBPs, trihalomethanols, were detected in the drinking water sample pretreated with multiple extractions; two of them, trichloromethanol and bromodichloromethanol, were identified with synthesized standard compounds. Moreover, these trihalomethanols were found to be the transformation products of trihalomethanes formed during ClO 2 disinfection. The results indicate that multiple LLEs can significantly improve extraction efficiencies of polar halogenated DBPs and is a better pretreatment method for characterizing and identifying new polar halogenated DBPs in drinking water. Copyright © 2017. Published by Elsevier B.V.

40 CFR 63.2465 - What requirements must I meet for process vents that emit hydrogen halide and halogen HAP or HAP...

Science.gov (United States)

2010-07-01

... process vents that emit hydrogen halide and halogen HAP or HAP metals? 63.2465 Section 63.2465 Protection... and halogen HAP or HAP metals? (a) You must meet each emission limit in Table 3 to this subpart that... section. (b) If any process vents within a process emit hydrogen halide and halogen HAP, you must...

Luminescence sensitivity changes in quartz as a result of annealing

DEFF Research Database (Denmark)

Bøtter-Jensen, L.; Agersnap Larsen, N.; Mejdahl, V.

1995-01-01

archaeological samples show very different OSL sensitivities. In this paper we report on studies of the effect of high temperature annealing on the OSL and phototransferred TL (PTTL) signals from sedimentary and synthetic quartz. A dramatic enhancement of both OSL and PTTL sensitivity was found especially...... in the temperature range 500-800 degrees C. Computer simulations of the possible effects are shown to produce data that agree in all essential details with the experimental observations. It is further demonstrated that the enhanced OSL sensitivity as a function of annealing temperature is not a pre-dose effect....... of magnitude less per unit radiation than that for heated material. The reason these temperature-induced sensitivity changes occur in quartz is presently not well understood. This phenomenon is also seen in the related area of luminescence dating in which sedimentary quartz and quartz from heated...

Fracture flow due to hydrothermally induced quartz growth

Science.gov (United States)

Kling, Tobias; Schwarz, Jens-Oliver; Wendler, Frank; Enzmann, Frieder; Blum, Philipp

2017-09-01

Mineral precipitations are a common feature and limitation of initially open, permeable rock fractures by forming sealing structures or secondary roughness in open voids. Hence, the objective of this numerical study is the evaluation of hydraulic properties of fractures sealed by hydrothermally induced needle and compact quartz growth. Phase-field models of progressive syntaxial and idiomorphic quartz growth are implemented into a fluid flow simulation solving the Navier-Stokes equation. Flow simulations for both quartz types indicate an obvious correlation between changes in permeability, fracture properties (e.g. aperture, relative roughness and porosity) and crystal growth behavior, which also forms distinct flow paths. Thus, at lower sealing stages initial fracture permeability significantly drops down for the 'needle fracture' forming highly tortuous flow paths, while the 'compact fracture' records a considerably smaller loss. Fluid flow in both sealing fractures most widely is governed by a ;parallel plate;-like cubic law behavior. However, the 'needle fracture' also reveals flow characteristics of a porous media. A semi-theoretical equation is introduced that links geometrical (am) with hydraulically effective apertures (ah) and the relative fracture roughness. For this purpose, a geometry factor α is introduced being α = 2.5 for needle quartz and α = 1.0 for compact quartz growth. In contrast to most common ah-am-relationships this novel formulation not only reveals more precise predictions for the needle (RMSE = 1.5) and the compact fractures (RMSE = 3.2), but also exhibit a larger range of validity concerning the roughness of the 'needle' (σ/am = 0-2.4) and the 'compact fractures' (σ/am = 0-1.8).

Quartz dissolution and silica deposition in hot-dry-rock geothermal systems

Energy Technology Data Exchange (ETDEWEB)

Robinson, B.A.

1982-07-01

The kinetics of quartz dissolution control the produced fluid dissolved silica concentration in geothermal systems in which the downhole residence time is finite. The produced fluid of the Phase I, Run Segment 5 experimental Hot Dry Rock (HDR) geothermal system at Fenton Hill, NM, was undersaturated with respect to quartz in one pass through the reservoir, suggesting that the rate of granite dissolution governed the outlet dissolved silica concentration in this system. The literature data for the rate of quartz dissolution in water from 65 to 625/sup 0/C is correlated using an empirical rate law which is first order in quartz surface area and degree of undersaturation of the fluid. The Arrhenius plot (ln k vs T/sup -1/) is linear over eight orders of magnitude of the rate constant, verifying the validity of the proposed rate expression. Carefully performed quartz dissolution experiments in the present study duplicated the literature data and completed the data base in the temperature range from 150 to 250/sup 0/C. Identical experiments using crushed granite indicate that the rate of quartz dissolution in the presence of granite could be as much as 1 to 2 orders of magnitude faster than the rates observed in the pure quartz experiments. A temperature dependent HDR reservoir model incorporates the quartz dissolution rate law to simulate the dissolved silica behavior during the Fenton Hill Run Segment 5 experiment. For this low-permeability, fracture-dominated reservoir, the assumptions of one-dimensional plug flow through a vertically-inclined rectangular fracture and one-dimensional rock heat conduction perpendicular to the direction of flow are employed. These simplifications lead to an analytical solution for the temperature field in the reservoir.

Ionic diffusion in quartz studied by transport measurements, SIMS and atomistic simulations

International Nuclear Information System (INIS)

Sartbaeva, Asel; Wells, Stephen A; Redfern, Simon A T; Hinton, Richard W; Reed, Stephen J B

2005-01-01

Ionic diffusion in the quartz-β-eucryptite system is studied by DC transport measurements, SIMS and atomistic simulations. Transport data show a large transient increase in ionic current at the α-β phase transition of quartz (the Hedvall effect). The SIMS data indicate two diffusion processes, one involving rapid Li + motion and the other involving penetration of Al and Li atoms into quartz at the phase transition. Atomistic simulations explain why the fine microstructure of twin domain walls in quartz near the transition does not hinder Li + diffusion

Mineralogy, morphology, and textural relationships in coatings on quartz grains in sediments in a quartz-sand aquifer

Science.gov (United States)

Zhang, Shouliang; Kent, Douglas B.; Elbert, David C.; Shi, Zhi; Davis, James A.; Veblen, David R.

2011-01-01

Mineralogical studies of coatings on quartz grains and bulk sediments from an aquifer on Western Cape Cod, Massachusetts, USA were carried out using a variety of transmission electron microscopy (TEM) techniques. Previous studies demonstrated that coatings on quartz grains control the adsorption properties of these sediments. Samples for TEM characterization were made by a gentle mechanical grinding method and focused ion beam (FIB) milling. The former method can make abundant electron-transparent coating assemblages for comprehensive and quantitative X-ray analysis and the latter technique protects the coating texture from being destroyed. Characterization of the samples from both a pristine area and an area heavily impacted by wastewater discharge shows similar coating textures and chemical compositions. Major constituents of the coating include Al-substituted goethite and illite/chlorite clays. Goethite is aggregated into well-crystallized domains through oriented attachment resulting in increased porosity. Illite/chlorite clays with various chemical compositions were observed to be mixed with goethite aggregates and aligned sub-parallel to the associated quartz surface. The uniform spatial distribution of wastewater-derived phosphorus throughout the coating from the wastewater-contaminated site suggests that all of the coating constituents, including those adjacent to the quartz surface, are accessible to groundwater solutes. Both TEM characterization and chemical extraction results indicate there is a significantly greater amount of amorphous iron oxide in samples from wastewater discharge area compared to those from the pristine region, which might reflect the impact of redox cycling of iron under the wastewater-discharge area. Coating compositions are consistent with the moderate metal and oxy-metalloid adsorption capacities, low but significant cation exchange capacities, and control of iron(III) solubility by goethite observed in reactive transport

Three-dimensional thermoluminescence spectra of different origin quartz from Altay Orogenic belt, Xinjiang, China

International Nuclear Information System (INIS)

Tan Kaixuan; Liu Zehua; Zeng Sheng; Liu Yan; Xie Yanshi; Rieser, Uwe

2009-01-01

Three-dimensional thermoluminescence spectra are measured for different types of geological origin quartz from the Altay orogenic belt, northern Xinjiang, China. The results show striking differences which appear to be characteristic of their geological origin. Granitic quartz is dominated by emission bands at 420-430 nm, 550-560 nm, at a temperature of 170 deg. C. Pegmatite quartz is characterized by an intense 480 nm emission band at 170 deg. C. Volcanic quartz has exclusive UV (340-360 nm) and violet (410-430 nm) emission bands. Hydrothermal quartz exhibits very different TL spectral characteristics because of different hydrothermal activity and mineralization. Only one TL peaks at 485 nm/170 deg. C was observed in sedimentary quartz. An intense 730 nm emission band observed at 170 deg. C considered generally to be characteristics of feldspar was observed in quartz from granite and hydrothermal Au-bearing quartz. This TL peak is probably related to the centre of [FeO 4 ] 0 on an Si site. All samples show an intense 990-1000 nm emission band at 330 deg. C. Identical types of quartz formed in different regions or different geological and tectonic settings can also exhibit striking differences in TL spectra.

Compound deterioration properties of non-halogen flame-resisting cables

International Nuclear Information System (INIS)

Yamamoto, Yasuaki; Yagyu, Hideki; Onishi, Takao; Kamiharako, Shinji

1984-01-01

Conventional flame-resisting cables release harmful gas such as hydrogen chloride and smoke on burning. To improve this disadvantage, the cables for nuclear power plants using new non-halogen flame-resisting insulating material have been developed. In this experiment, the non-halogen flame-resisting cables were subjected to the environmental test with varying test conditions. The test conditions included the order of exposure (heat treatment, γ-ray irradiation and steam exposure) and dose rate. After the environmental test, the mechanical and electrical properties of the samples were measured. In all test conditions, the samples did not crack in bending, and withstood the bending and withstand-voltage in-water test. The tensile strength and a.c. breakdown voltage did not change, and were stable. The elongation decreased greatly, but maintained the value of about 100 %, and the volumetric resistivity decreased by only one figure. It was confirmed that these cables were able to withstand various environmental tests. (Yoshitake, I.)

Content of some microelements in Bulgarian quartz

International Nuclear Information System (INIS)

Kostadinov, K.; Kuleff, I.; Djingova, R.; Todorovski, D.

1982-01-01

Data on the content of As, Au, Ba, Br, Ca, Cd, Ce, Co, Cr, Cs, Eu, Fe, Hf, Hg, Ir, K, La, Lu, Mn, Nd, Na, Rb, Sb, Sm, Ta, Tb, Sc, Th, U, W, Yb, Zn obtained by instrumental neutron activation analysis are reported. The method is published elsewhere (Kuleff, I. et J. Radional. Chem. 62 (1981) 187). The results of other authors for the amount of Al, Li, Ti, obtained by atomic absorption spectrometry and Cu, P measured by destructive neutron activation analysis are also reported for 3 batches of electrothermal quartz glass, manufactured by ''Svetlina'' plant in Sliven, Bulgaria. The results for Bulgarian quartz glass are compared with literature and authors' data for similar quality glasses produced in England, France, FRG, GDR, USA and USSR. The results show that the amount of As, Au, Cd, Ce, Co, Cs, Eu, Hg, La, Ta, Yb in Bulgarian made quartz glass is lower than in a number of other similar glasses and the amount of the other impurities is close to the mean values. (authors)

Determination of halogen content in glass for assessment of melter decontamination factors

International Nuclear Information System (INIS)

Goles, R.W.

1996-03-01

Melter decontamination factor (DF) values for the halogens (fluorine, chlorine, and iodine) are important to the Hanford Waste Vitrification Plant (HWVP) process because of the potential influence of DF on secondary-waste recycle strategies (fluorine and chlorine) as well as its impact on off-gas emissions (iodine). This study directly establishes the concentrations of halides-in HWVP simulated reference glasses rather than relying on indirect off-gas data. For fluorine and chlorine, pyrohydrolysis coupled with halide (ion chromatographic) detection has proven to be a useful analytical approach suitable for glass matrices, sensitive enough for the range of halogens encountered, and compatible with remote process support applications. Results obtained from pyrohydrolytic analysis of pilot-scale ceramic melter (PSCM) -22 and -23 glasses indicate that the processing behavior of fluorine and chlorine is quite variable even under similar processing conditions. Specifically, PSCM-23 glass exhibited a ∼90% halogen (F and Cl) retention efficiency, while only 20% was incorporated in PSCM-22 glass. These two sets of very dissimilar test results clearly do not form a sufficient basis for establishing design DF values for fluorine and chlorine. Because the present data do not provide any new halogen volatility information, but instead reconfirm the validity of previously obtained offgas derived values, melter DF values of 4, 2, and 1 for fluorine, chlorine, and iodine, respectively, are recommended for adoption; these values were conservatively established by a team of responsible engineers at Westinghouse Hanford Company (WHC) and Pacific Northwest Laboratory (PNL) on the basis of average behavior for many comparable melter tests. In the absence of further HWVP process data, these average melter DFs are the best values currently available

Composes inter-halogenes sous pression: etude des transformations structurales dans le monobromure d'iode sous forme dense

Science.gov (United States)

Bouchard, Alexandre

La famille des composes halogenes et inter-halogenes representent des solides moleculaires adoptant des phases denses communes avec des solides moleculaires diatomiques comme l'azote et l'hydrogene. Parmi les transformations structurales et electroniques induites sous haute pression et observees dans ces solides, on note, entre autres, la dissociation moleculaire et la metallisation. De plus, l'etude des phases denses de l'iode a permis recemment l'observation d'une structure cristalline possedant une modulation dite incommensurable, c'est-a-dire une modulation possedant une periodicite differente de celle de la structure cristalline, jetant ainsi une lumiere nouvelle sur le processus de dissociation moleculaire dans les solides halogenes. Dans ce memoire, on propose d'etudier les changements structuraux dans monobromure d'iode (IBr), un compose inter-halogene possedant des proprietes structurales semblables a celles de deux composes halogenes, soit l'iode (I 2) et le brome (Br2) sous leur forme solide. Des experiences de diffraction des rayons X de poudres en utilisant un rayonnement synchrotron ont ete realisees a temperature ambiante sur l'IBr en variant la pression jusqu'aux environs de 60 GPa. La nature chimique particuliere du compose IBr a necessite la mise au point de techniques de chargement d'echantillon destinees a preserver l'integrite chimique de la substance utilisee. On rapporte egalement l'observation d'une phase de l'IBr presentant une modulation incommensurable. Les phases observees dans l'IBr permettent d'etablir des paralleles avec les phases denses rapportees dans I2 et Br2 par le biais d'un modele phenomenologique decrivant la sequence structurale des solides halogenes sous forme condensee.

Development of halogen-free flame-retardant cable for nuclear power plant. 2

International Nuclear Information System (INIS)

Matsumoto, Tetsuo; Kimura, Hitoshi; Ishii, Nobuhisa

1997-01-01

Halogen-free flame-retardant cables were developed for PWR nuclear power stations. It was confirmed that the developed cables possess flame retardant property, corrosion resistance, low toxicity and low smoke generation, and withstand the normal operation in the environment in PWR containment vessels for 60 years and loss of coolant accident. In the advancement of LWR technology, it is important to improve the reliability of machinery and equipment, to extend the period of continuous operation, to optimize the operation cycle and to improve the maintenance of plants. By improving halogen-free flame-retardant material and applying it to the cables for nuclear power stations, it can contribute to the above purposes. The required characteristics of these cables are explained, and the targets of development are power cables, control cables, instrumentation cables and insulated wires which do not contain halogen. The basic material is polyolefin, in which flame retardant magnesium hydroxide and the agent for improving radiation resistance are mixed. The corrosive property and toxicity of gases, smoke generation and the prevention of spread of flame when the cables burn and the durability in environment were evaluated. (K.I.)

Development of an enzymatic fiber-optic biosensor for detection of halogenated hydrocarbons

Energy Technology Data Exchange (ETDEWEB)

Bidmanova, Sarka; Chaloupkova, Radka; Damborsky, Jiri; Prokop, Zbynek [Masaryk University, Loschmidt Laboratories, Department of Experimental Biology and Research Centre for Toxic Compounds in the Environment, Faculty of Science, Brno (Czech Republic)

2010-11-15

An enzyme-based biosensor was developed by co-immobilization of purified enzyme haloalkane dehalogenase (EC 3.8.1.5) and a fluorescence pH indicator on the tip of an optical fiber. Haloalkane dehalogenase catalyzes hydrolytic dehalogenation of halogenated aliphatic hydrocarbons, which is accompanied by a pH change influencing the fluorescence of the indicator. The pH sensitivity of several fluorescent dyes was evaluated. The selected indicator 5(6)-carboxyfluorescein was conjugated with bovine serum albumin and its reaction was tested under different immobilization conditions. The biosensor was prepared by cross-linking of the conjugate in tandem with haloalkane dehalogenase using glutaraldehyde vapor. The biosensor, stored for 24 h in 50 mM phosphate buffer (pH 7.5) prior to measurement, was used after 15 min of equilibration, the halogenated compound was added, and the response was monitored for 30 min. Calibration of the biosensor with 1,2-dibromoethane and 3-chloro-2-(chloromethyl)-1-propene showed an excellent linear dependence, with detection limits of 0.133 and 0.014 mM, respectively. This biosensor provides a new tool for continuous in situ monitoring of halogenated environmental pollutants. (orig.)

Development of quartz particulate reinforced AA6063 aluminum matrix composites via friction stir processing

Directory of Open Access Journals (Sweden)

S. Joyson Abraham

2016-12-01

Full Text Available Friction stir processing (FSP has been accepted as a potential method to produce aluminum matrix composites (AMCs without the drawbacks of liquid metallurgy methods. The present work focuses on the development of AMCs reinforced with quartz (SiO2 particles using FSP. Grooves with various dimensions were machined on AA6063 plates and compacted with quartz particles. A single pass FSP was carried out using a combination of optimized process parameters. The volume fraction of quartz particles in the AMCs was varied from 0 to 18 vol.% in steps of 6 vol.%. The developed AA6063/Quartz AMCs were characterized using optical, scanning and transmission electron microscopy. The quartz particles were distributed uniformly in the aluminum matrix irrespective of the location within the stir zone. The grains of the AA6063 were extensively refined by the combination of thermomechanical effect of FSP and the pinning effect of quartz particles. The dispersion of the quartz particles improved the microhardness and wear resistance of the AMCs. The role of quartz particles on the worn surface and wear debris is reported.

Historical review of quartz crystal growth

Science.gov (United States)

Iwasaki, Fumiko; Iwasaki, Hideo

2002-04-01

The history of quartz crystal growth is reviewed from the origin to the industrialization. The developing process of growth techniques is divided into the following three stages: (1) The fundamental work based on the mineralogical genetic view point, which was performed in Italy during the end of the 19th to the beginning of the 20th centuries. (2) The works to attempt the industrial application made in Germany and in England during World War II. (3) The industrialization of quartz growth after World War II. These were initiated in England, in USA and independently in Russia. The highest mass production process was developed in Japan. The historical flow is traced by the interview of several persons based on the original references.

Quantum Chemical Examination of the Sequential Halogen Incorporation Scheme for the Modeling of Speciation of I/Br/Cl-Containing Trihalomethanes.

Science.gov (United States)

Zhang, Chenyang; Li, Maodong; Han, Xuze; Yan, Mingquan

2018-02-20

The recently developed three-step ternary halogenation model interprets the incorporation of chlorine, bromine, and iodine ions into natural organic matter (NOM) and formation of iodine-, bromine-, and chlorine-containing trihalomethanes (THMs) based on the competition of iodine, bromine, and chlorine species at each node of the halogenation sequence. This competition is accounted for using the dimensionless ratios (denoted as γ) of kinetic rates of reactions of the initial attack sites or halogenated intermediates with chlorine, bromine, and iodine ions. However, correlations between the model predictions made and mechanistic aspects of the incorporation of halogen species need to be ascertained in more detail. In this study, quantum chemistry calculations were first used to probe the formation mechanism of 10 species of Cl-/Br-/I- THMs. The HOMO energy (E HOMO ) of each mono-, bi-, or trihalomethanes were calculated by B3LYP method in Gaussian 09 software. Linear correlations were found to exist between the logarithms of experimentally determined kinetic preference coefficients γ reported in prior research and, on the other hand, differences of E HOMO values between brominated/iodinated and chlorinated halomethanes. One notable exception from this trend was that observed for the incorporation of iodine into mono- and di-iodinated intermediates. These observations confirm the three-step halogen incorporation sequence and the factor γ in the statistical model. The combined use of quantum chemistry calculations and the ternary sequential halogenation model provides a new insight into the microscopic nature of NOM-halogen interactions and the trends seen in the behavior of γ factors incorporated in the THM speciation models.

Performance analysis of photoresistor and phototransistor for automotive’s halogen and xenon bulbs light output

Science.gov (United States)

Rammohan, A.; Kumar, C. Ramesh

2017-11-01

Illumination of any light is measured using a different kind of calibrated equipment’s available in the market such as a goniometer, spectral radiometer, photometer, Lux meter and camera based systems which directly display the illumination of automotive headlights light distribution in the unit of lux, foot-candles, lumens/sq. ft. and Lambert etc., In this research, we dealt with evaluating the photo resistor or Light Dependent Resistor (LDR) and phototransistor whether it is useful for sensing light patterns of Automotive Halogen and Xenon bulbs. The experiments are conducted during night hours under complete dark space. We have used the headlamp setup available in TATA SUMO VICTA vehicle in the Indian market and conducted the experiments separately for Halogen and Xenon bulbs under low and high beam operations at various degrees and test points within ten meters of distance. Also, we have compared the light intensity of halogen and xenon bulbs to prove the highest light intensity between halogen and Xenon bulbs. After doing a rigorous test with these two sensors it is understood both are good to sensing beam pattern of automotive bulbs and even it is good if we use an array of sensors or a mixed combination of sensors for measuring illumination purposes under perfect calibrations.

Surface coatings on quartz grains in bentonites and their relevance to human health

International Nuclear Information System (INIS)

Wendlandt, Richard F.; Harrison, Wendy J.; Vaughan, David J.

2007-01-01

The cytotoxicity of quartz in the human lung is recognized to be dependent on both the inherent properties of the silica dust and external factors related to the history of the dust and including the presence of surface contamination. In this study, the physical and chemical surface properties of quartz grains in commercial bentonite deposits from the western (South Dakota) and southern (Alabama) USA were investigated. Measured quartz contents of bentonites range from 1.9 to 8.5 wt% with the <10 μm size fraction comprising 6-45% of this total. Trace element contents (Fe-Ti-Al) of quartz grains from any given bentonite are similar, indicating a single origin for the quartz with little if any contamination from other sources. Surface coatings are pervasive on all quartz grains and resist removal by repeated vigorous washings and reaction with HCl. Textural attributes and XPS and EDS analyses of these coatings are consistent with most being montmorillonite and, less frequently, mixtures of montmorillonite and opaline silica. Opaline silica (opal-A and opal-CT) occurs in two texturally distinct generations: an early massive grain-coating event and as later lepispheres. Montmorillonite coating thicknesses range from <1 μm to more than 10 μm thick. Surfaces of plagioclase, K-feldspar, and biotite grains are conspicuously devoid of montmorillonite coatings, but may show sparse distributions of opal-CT lepispheres. HRTEM has not confirmed a topotactic relationship or atomic structural concordance between montmorillonite coatings and underlying quartz grains. Alternatively, a precursor volcanic glass phase that coats the quartz surfaces during volcanic eruption and/or preferential early precipitation of opaline silica on quartz may provide substrates for development of montmorillonite coatings. Estimations of montmorillonite biodurability under pulmonary pH conditions suggest possible prolonged sequestration of respired bentonite quartz grains from contact with lung

40 CFR Table 3 to Subpart Ffff of... - Emission Limits for Hydrogen Halide and Halogen HAP Emissions or HAP Metals Emissions From...

Science.gov (United States)

2010-07-01

... Halogen HAP Emissions or HAP Metals Emissions From Process Vents 3 Table 3 to Subpart FFFF of Part 63... to Subpart FFFF of Part 63—Emission Limits for Hydrogen Halide and Halogen HAP Emissions or HAP... following table that applies to your process vents that contain hydrogen halide and halogen HAP emissions or...

Evaluation of trapping parameters of annealed natural quartz

International Nuclear Information System (INIS)

Zhou, Rui; Wei, Ming-Jian; Song, Bo; Zhang, Yan; Zhao, Qiu-Yue; Pan, Bao-Lin; Li, Teng-Fei

2016-01-01

The thermoluminescence (TL) trapping parameters of annealed quartz have been investigated. The apparent TL peaks observed at temperatures of 133 °C, 211 °C, 266 °C and 405 °C, respectively, were named Peak I, Peak II, Peak III and Peak IV. The T_m − T_s_t_o_p method is applied to investigate the number of peaks and their positions, and to obtain the trap distributions in the quartz. Peak shape (PS), Hoogenstraaten method (Various Heating Rates Method, VHR), and Computerized Glow Curve Deconvolution (CGCD) are used to evaluate the trapping parameters of the annealed quartz. The glow curve can be considered as a superposition of at least nine overlapping peaks. These peaks show up at 133 °C, 211 °C, 266 °C, 308 °C, 333 °C, 384 °C, 441 °C, 466 °C and 484 °C. The PS method can be only used in evaluating the parameters for Peaks I. The VHR method can be used in evaluating the trapping parameters for the first three peaks. CGCD method is complementary to obtaining parameters for the sub-peaks, and the thermal quenching correction with the Urbach’s method is necessary. The Urbach’s coefficient for the quartz is 30.03 kT_m.

Evaluation of trapping parameters of annealed natural quartz

Energy Technology Data Exchange (ETDEWEB)

Zhou, Rui [College of Resources, Environment & Tourism, Capital Normal University, 100048 Beijing (China); Shisanling Seismic Station, Institute of Earthquake Science, CEA, 102200 Beijing (China); Wei, Ming-Jian, E-mail: weimj@cnu.edu.cn [College of Resources, Environment & Tourism, Capital Normal University, 100048 Beijing (China); Song, Bo [College of Resources, Environment & Tourism, Capital Normal University, 100048 Beijing (China); Beijing Jing Yuan School, 100040 Beijing (China); Zhang, Yan [College of Resources, Environment & Tourism, Capital Normal University, 100048 Beijing (China); School of TaiPingqiao, Nan Lu of West Railway Station, 100073 Beijing (China); Zhao, Qiu-Yue [Key Laboratory of Tourism and Resources Environment in Universities of Shandong, Taishan University, 271000 Tai’an (China); Pan, Bao-Lin; Li, Teng-Fei [College of Resources, Environment & Tourism, Capital Normal University, 100048 Beijing (China)

2016-05-15

The thermoluminescence (TL) trapping parameters of annealed quartz have been investigated. The apparent TL peaks observed at temperatures of 133 °C, 211 °C, 266 °C and 405 °C, respectively, were named Peak I, Peak II, Peak III and Peak IV. The T{sub m} − T{sub stop} method is applied to investigate the number of peaks and their positions, and to obtain the trap distributions in the quartz. Peak shape (PS), Hoogenstraaten method (Various Heating Rates Method, VHR), and Computerized Glow Curve Deconvolution (CGCD) are used to evaluate the trapping parameters of the annealed quartz. The glow curve can be considered as a superposition of at least nine overlapping peaks. These peaks show up at 133 °C, 211 °C, 266 °C, 308 °C, 333 °C, 384 °C, 441 °C, 466 °C and 484 °C. The PS method can be only used in evaluating the parameters for Peaks I. The VHR method can be used in evaluating the trapping parameters for the first three peaks. CGCD method is complementary to obtaining parameters for the sub-peaks, and the thermal quenching correction with the Urbach’s method is necessary. The Urbach’s coefficient for the quartz is 30.03 kT{sub m}.

75 FR 30282 - Airworthiness Directives; Quartz Mountain Aerospace, Inc. Model 11E Airplanes

Science.gov (United States)

2010-06-01

... Airworthiness Directives; Quartz Mountain Aerospace, Inc. Model 11E Airplanes AGENCY: Federal Aviation... airworthiness directive (AD) for all Quartz Mountain Aerospace, Inc. Model 11E airplanes. This AD requires you... reference of certain publications listed in this AD. ADDRESSES: Quartz Mountain Aerospace, Inc. is in...

Protection of halogenated DNA from strand breakage and sister-chromatid exchange induced by the topoisomerase I inhibitor camptothecin

International Nuclear Information System (INIS)

Orta, Manuel Luis; Mateos, Santiago; Cantero, Gloria; Wolff, Lisa J.; Cortes, Felipe

2008-01-01

The fundamental nuclear enzyme DNA topoisomerase I (topo I), cleaves the double-stranded DNA molecule at preferred sequences within its recognition/binding sites. We have recently reported that when cells incorporate halogenated nucleosides analogues of thymidine into DNA, it interferes with normal chromosome segregation, as shown by an extraordinarily high yield of endoreduplication, and results in a protection against DNA breakage induced by the topo II poison m-AMSA [F. Cortes, N. Pastor, S. Mateos, I. Dominguez, The nature of DNA plays a role in chromosome segregation: endoreduplication in halogen-substituted chromosomes, DNA Repair 2 (2003) 719-726; G. Cantero, S. Mateos, N. Pastor; F. Cortes, Halogen substitution of DNA protects from poisoning of topoisomerase II that results in DNA double-strand breaks (DSBs), DNA Repair 5 (2006) 667-674]. In the present investigation, we have assessed whether the presence of halogenated nucleosides in DNA diminishes the frequency of interaction of topo I with DNA and thus the frequency with which the stabilisation of cleavage complexes by the topo I poison camptothecin (CPT) takes place, in such a way that it protects from chromosome breakage and sister-chromatid exchange. This protective effect is shown to parallel a loss in halogen-substituted cells of the otherwise CPT-increased catalytic activity bound to DNA

Pharmacological evaluation of halogenated and non-halogenated arylpiperazin-1-yl-ethyl-benzimidazoles as D(2) and 5-HT(2A) receptor ligands.

Science.gov (United States)

Tomić, Mirko; Vasković, Djurdjica; Tovilović, Gordana; Andrić, Deana; Penjišević, Jelena; Kostić-Rajačić, Sladjana

2011-05-01

Five groups of previously synthesized and initially screened non-substituted and 4-halogenated arylpiperazin-1-yl-ethyl-benzimidazoles were estimated for their in-vitro binding affinities at the rat D(2) , 5-HT(2A) , and α(1) -adrenergic receptors. Among all these compounds, 2-methoxyphenyl and 2-chlorophenyl piperazines demonstrate the highest affinities for the tested receptors. The effects of 4-halogenation of benzimidazoles reveal that substitution with bromine may greatly increase the affinity of the compounds for the studied receptors, while the effect of substitution with chlorine is less remarkable. Most of the tested components show 5-HT(2A)/D(2) pK(i) binding ratios slightly above or less than 1, while only 4-chloro-6-(2-{4-[3-(trifluoromethyl)phenyl]piperazin-1-yl}ethyl)-1H-benzimidazole expresses an appropriate higher binding ratio (1.14), which was indicated for atypical neuroleptics. This compound exhibits a non-cataleptic action in rats and prevents d-amphetamine-induced hyperlocomotion in mice, which suggest its atypical antipsychotic potency. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dose response on the 110 °C thermoluminescence peak of un-heated, synthetic Merck quartz

Energy Technology Data Exchange (ETDEWEB)

Kaya Keleş, Şule, E-mail: sule.kaya@ankara.edu.tr; Meriç, Niyazi; Polymeris, George S.

2016-07-15

Studies on 110 °C TL peak have been carried out using natural quartz from different origins and synthetic quartz produced by different suppliers. The interest in quartz is due to its usage in dating and retrospective dosimetry as a main material; both synthetic and natural types of quartz yield the 110 °C TL peak in their glow curve. In most studies to understand the physical mechanism behind the TL system, synthetic quartz samples are used and there are many investigations about dose response, in both low and high radiation dose region. In these studies generally synthetic quartz samples produced by Sawyer Research Products are used and the studies showed that both heated and un-heated synthetic quartz samples have intense supra-linear responses. Supra-linearity was enhanced by applying a pre-irradiation while several models have been developed towards an explanation to these supra-linearity effects. In this study commercially available synthetic Merck quartz was used. Different combinations of optical filters were used to obtain dose response curves upto 266 Gy and the effect of pre-dose to these dose response curves was studied. Un-pre-dosed Merck quartz samples dose supra-linearity index is below 1 independently on the optical filters; so Merck quartz showed linear or sub-linear dose response.

The Effect of Quartz on the Flotation of Fine Wolframite with Octyl Hydroxamic Acid

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Qingyou Meng

2017-09-01

Full Text Available The influence of quartz on the flotation of fine wolframite using octyl hydroxamic acid (OHA as the collector was investigated by micro-flotation tests, inductively coupled plasma (ICP measurements, adsorption experiments, zeta potential, and Fourier transform infrared spectroscopy (FT-IR analysis. Micro-flotation tests showed that a large difference in floatability existed between fine wolframite and quartz in the pH range of 7.0 to 10.0. However, in a synthetic mixture, the flotation separation of fine wolframite from quartz became more difficult as the particle size of the latter decreased. When a dissolved solution of wolframite was used as the flotation medium, quartz floatability improved significantly. Zeta potentials of quartz particles shifted positively in the dissolved solution of wolframite compared to distilled water, especially at a pH level of 7.0–10.0, which was attributed to the metal ions dissolved from the wolframite being adsorbed onto the quartz surface. The surface activation of quartz led to an increase in the OHA adsorption and made the surface hydrophobic. FT-IR analysis further demonstrated that OHA could adsorb onto the activated quartz surface through a dominantly chemical process.

Chromatographic resolution of closely related species in pharmaceutical chemistry: dehalogenation impurities and mixtures of halogen isomers.

Science.gov (United States)

Regalado, Erik L; Zhuang, Ping; Chen, Yadan; Makarov, Alexey A; Schafer, Wes A; McGachy, Neil; Welch, Christopher J

2014-01-07

In recent years, the use of halogen-containing molecules has proliferated in the pharmaceutical industry, where the incorporation of halogens, especially fluorine, has become vitally important for blocking metabolism and enhancing the biological activity of pharmaceuticals. The chromatographic separation of halogen-containing pharmaceuticals from associated isomers or dehalogenation impurities can sometimes be quite difficult. In an attempt to identify the best current tools available for addressing this important problem, a survey of the suitability of four chromatographic method development platforms (ultra high-performance liquid chromatography (UHPLC), core shell HPLC, achiral supercritical fluid chromatography (SFC) and chiral SFC) for separating closely related mixtures of halogen-containing pharmaceuticals and their dehalogenated isosteres is described. Of the 132 column and mobile phase combinations examined for each mixture, a small subset of conditions were found to afford the best overall performance, with a single UHPLC method (2.1 × 50 mm, 1.9 μm Hypersil Gold PFP, acetonitrile/methanol based aqueous eluents containing either phosphoric or perchloric acid with 150 mM sodium perchlorate) affording excellent separation for all samples. Similarly, a survey of several families of closely related halogen-containing small molecules representing the diversity of impurities that can sometimes be found in purchased starting materials for synthesis revealed chiral SFC (Chiralcel OJ-3 and Chiralpak IB, isopropanol or ethanol with 25 mM isobutylamine/carbon dioxide) as well as the UHPLC (2.1 × 50 mm, 1.8 μm ZORBAX RRHD Eclipse Plus C18 and the Gold PFP, acetonitrile/methanol based aqueous eluents containing phosphoric acid) as preferred methods.

Apatite-brannerite-pitchblende association in hydrothermal quartz veins

International Nuclear Information System (INIS)

Brodin, B.V.; Mel'nikova, A.M.; Osipov, B.S.; Pavlov, E.G.

1976-01-01

A study into the vein quartz mineralization confined to the tectonic zones of crush and silicification in sedimentary-igneous rocks of the lower Paleozoic has been made. The physicochemical characteristics of minerals were studied by way of optical and electron microscopy, chemical, laser-microspectral and X-ray structural analyses, microprobing and alpha-microradiography. 3 mineral associations have been discriminated, representative of the sequence of hydrothermal mineralization. An unusual parogenesis of pitchblende and brannerite with apatite, xenotime and more recent goethite has been revealed. The results are indicative of a medium-low-temperature hydrothermal process occurring at the final stages of formation of uraniferrous quartz veins. By composition and mineralization sequence, the latters are close to low- and medium-temperature uranium-quartz-chlorite-hydromica formations with apatite, coffinite, brannerite and pitchblende. The weak initial metamictization of goethite in veins 80 to 100 million years old is due to the radioactive effect of the submicroscopic radioactive mineral impurity on the crystalline lattice

A box model study on photochemical interactions between VOCs and reactive halogen species in the marine boundary layer

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K. Toyota

2004-01-01

Full Text Available A new chemical scheme is developed for the multiphase photochemical box model SEAMAC (size-SEgregated Aerosol model for Marine Air Chemistry to investigate photochemical interactions between volatile organic compounds (VOCs and reactive halogen species in the marine boundary layer (MBL. Based primarily on critically evaluated kinetic and photochemical rate parameters as well as a protocol for chemical mechanism development, the new scheme has achieved a near-explicit description of oxidative degradation of up to C3-hydrocarbons (CH4, C2H6, C3H8, C2H4, C3H6, and C2H2 initiated by reactions with OH radicals, Cl- and Br-atoms, and O3. Rate constants and product yields for reactions involving halogen species are taken from the literature where available, but the majority of them need to be estimated. In particular, addition reactions of halogen atoms with alkenes will result in forming halogenated organic intermediates, whose photochemical loss rates are carefully evaluated in the present work. Model calculations with the new chemical scheme reveal that the oceanic emissions of acetaldehyde (CH3CHO and alkenes (especially C3H6 are important factors for regulating reactive halogen chemistry in the MBL by promoting the conversion of Br atoms into HBr or more stable brominated intermediates in the organic form. The latter include brominated hydroperoxides, bromoacetaldehyde, and bromoacetone, which sequester bromine from a reactive inorganic pool. The total mixing ratio of brominated organic species thus produced is likely to reach 10-20% or more of that of inorganic gaseous bromine species over wide regions over the ocean. The reaction between Br atoms and C2H2 is shown to be unimportant for determining the degree of bromine activation in the remote MBL. These results imply that reactive halogen chemistry can mediate a link between the oceanic emissions of VOCs and the behaviors of compounds that are sensitive to halogen chemistry such as dimethyl

Four groups of new aromatic halogenated disinfection byproducts: effect of bromide concentration on their formation and speciation in chlorinated drinking water.

Science.gov (United States)

Pan, Yang; Zhang, Xiangru

2013-02-05

Bromide is naturally present in source waters worldwide. Chlorination of drinking water can generate a variety of chlorinated and brominated disinfection byproducts (DBPs). Although substantial efforts have been made to examine the effect of bromide concentration on the formation and speciation of halogenated DBPs, almost all previous studies have focused on trihalomethanes and haloacetic acids. Given that about 50% of total organic halogen formed in chlorination remains unknown, it is still unclear how bromide concentration affects the formation and speciation of the new/unknown halogenated DBPs. In this study, chlorinated drinking water samples with different bromide concentrations were prepared, and a novel approach-precursor ion scan using ultra performance liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry-was adopted for the detection and identification of polar halogenated DBPs in these water samples. With this approach, 11 new putative aromatic halogenated DBPs were identified, and they were classified into four groups: dihalo-4-hydroxybenzaldehydes, dihalo-4-hydroxybenzoic acids, dihalo-salicylic acids, and trihalo-phenols. A mechanism for the formation of the four groups of new aromatic halogenated DBPs was proposed. It was found that increasing the bromide concentration shifted the entire polar halogenated DBPs as well as the four groups of new DBPs from being less brominated to being more brominated; these new aromatic halogenated DBPs might be important intermediate DBPs formed in drinking water chlorination. Moreover, the speciation of the four groups of new DBPs was modeled: the speciation patterns of the four groups of new DBPs well matched those determined from the model equations, and the reactivity differences between HOBr and HOCl in reactions forming the four groups of new DBPs were larger than those in reactions forming trihalomethanes and haloacetic acids.

A Protein Data Bank survey reveals shortening of intermolecular hydrogen bonds in ligand-protein complexes when a halogenated ligand is an H-bond donor.

Science.gov (United States)

Poznański, Jarosław; Poznańska, Anna; Shugar, David

2014-01-01

Halogen bonding in ligand-protein complexes is currently widely exploited, e.g. in drug design or supramolecular chemistry. But little attention has been directed to other effects that may result from replacement of a hydrogen by a strongly electronegative halogen. Analysis of almost 30000 hydrogen bonds between protein and ligand demonstrates that the length of a hydrogen bond depends on the type of donor-acceptor pair. Interestingly, lengths of hydrogen bonds between a protein and a halogenated ligand are visibly shorter than those estimated for the same family of proteins in complexes with non-halogenated ligands. Taking into account the effect of halogenation on hydrogen bonding is thus important when evaluating structural and/or energetic parameters of ligand-protein complexes. All these observations are consistent with the concept that halogenation increases the acidity of the proximal amino/imino/hydroxyl groups and thus makes them better, i.e. stronger, H-bond donors.

UV-visible and resonance Raman spectroscopy of halogen molecules in clathrate hydrates

Energy Technology Data Exchange (ETDEWEB)

Janda, K.C.; Kerenskaya, G.; Goldsheleger, I.U.; Apkarian, V.A.; Fleischer, E.B. [California Univ., Irvine, CA (United States). Dept. of Chemistry

2008-07-01

Resonance Raman spectroscopy was used to study halogen clathrate hydrate solids. In particular, this paper presented an ultraviolet-visible spectra for a polycrystalline sample of chlorine clathrate hydrate and two single crystal samples of bromine clathrate hydrate. UV-visible spectroscopy was used to study the interactions between the halogen guest molecule and the host water lattice. The spectrum for chlorine hydrate had a strong temperature dependence, while the spectra for bromine clathrate hydrate single crystals had a stable cubic type 2 structure as well as a tetragonal structure. A metastable cubic type 1 structure was also observed. Resonance Raman spectroscopy showed how the molecules fit into the host cages. 25 refs., 2 tabs., 7 figs.

Attosecond Time Delay in Photoionization of Noble-Gas and Halogen Atoms

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Liang-Wen Pi

2018-02-01

Full Text Available Ultrafast processes are now accessible on the attosecond time scale due to the availability of ultrashort XUV laser pulses. Noble-gas and halogen atoms remain important targets due to their giant dipole resonance and Cooper minimum. Here, we calculate photoionization cross section, asymmetry parameter and Wigner time delay using the time-dependent local-density approximation (TDLDA, which includes the electron correlation effects. Our results are consistent with experimental data and other theoretical calculations. The asymmetry parameter provides an extra layer of access to the phase information of the photoionization processes. We find that halogen atoms bear a strong resemblance on cross section, asymmetry parameter and time delay to their noble-gas neighbors. Our predicted time delay should provide a guidance for future experiments on those atoms and related molecules.

SYNTHESIS AND STUDY OF HALOGENATED BENZYLAMIDES OF SOME ISOCYCLIC AND HETEROCYCLIC ACIDS AS POTENTIAL ANTICONVULSANTS.

Science.gov (United States)

Strupińska, Marzanna; Rostafińska-Suchar, Grażyna; Pirianowicz-Chaber, Elżbieta; Grabczuk, Mateusz; Józwenko, Magdalena; Kowalczyk, Hubert; Szuba, Joanna; Wójcicka, Monika; Chen, Tracy; Mazurek, Aleksander P

2015-01-01

A series of potential anticonvulsants have been synthesized. There are eight fluorobenzylamides and three chlorobenzylamides of isocyclic or heterocyclic acids. Two not halogenated benzylamides were also synthesized to compare the effect of halogenation. The aim of the research performed was to evaluate whether halogenation of the mother structure is able to improve its anticonvulsant activity. The compounds were tested in Anticonvulsant Screening Project (ASP) of Antiepileptic Drug Development Program (ADDP) of NIH. Compound 1 showed MES ED50 = 80.32 mg/kg, PI = 3.16. Compound 7 showed CKM ED50 = 56.72 mg/kg. Compound 8 showed MES ED50 = 34.23 mg/kg and scPTZ ED50 > 300 mg/kg, PI = 8.53.Compound 13 showed 6Hz ED50 = 78.96, PI = 3.37. The results indicate that fluorination does not improve activity, whereas chlorination in our experiment even reduces it.

Computational insights into the photocyclization of diclofenac in solution: effects of halogen and hydrogen bonding.

Science.gov (United States)

Bani-Yaseen, Abdulilah Dawoud

2016-08-21

The effects of noncovalent interactions, namely halogen and hydrogen bonding, on the photochemical conversion of the photosensitizing drug diclofenac (DCF) in solution were investigated computationally. Both explicit and implicit solvent effects were qualitatively and quantitatively assessed employing the DFT/6-31+G(d) and SQM(PM7) levels of theory. Full geometry optimizations were performed in solution for the reactant DCF, hypothesized radical-based intermediates, and the main product at both levels of theories. Notably, in good agreement with previous experimental results concerning the intermolecular halogen bonding of DCF, the SQM(PM7) method revealed different values for d(ClO, Å) and ∠(C-ClO, °) for the two chlorine-substituents of DCF, with values of 2.63 Å/162° and 3.13 Å/142° for the trans and cis orientations, respectively. Employing the DFT/6-31+G(d) method with implicit solvent effects was not conclusive; however, explicit solvent effects confirmed the key contribution of hydrogen and halogen bonding in stabilizing/destabilizing the reactant and hypothesized intermediates. Interestingly, the obtained results revealed that a protic solvent such as water can increase the rate of photocyclization of DCF not only through hydrogen bonding effects, but also through halogen bonding. Furthermore, the atomic charges of atoms majorly involved in the photocyclization of DCF were calculated using different methods, namely Mulliken, Hirshfeld, and natural bond orbital (NBO). The obtained results revealed that in all cases there is a notable nonequivalency in the noncovalent intermolecular interactions of the two chlorine substituents of DCF and the radical intermediates with the solvent, which in turn may account for the discrepancy of their reactivity in different media. These computational results provide insight into the importance of halogen and hydrogen bonding throughout the progression of the photochemical conversion of DCF in solution.

Oxygen isotopic ratios in quartz as an indicator of provenance of dust

International Nuclear Information System (INIS)

Jackson, M.L.

1977-01-01

Quartz was isolated in the long range aerosol size range (fine silt, 1-10 μm in diameter) from atmospheric aerosols, wind-erosive soils, soil silts, shales, and Pacific pelagic sediments of the Northern and Southern Hemispheres, to trace their provenance or origin, as part of a study of dust mineral sequestering of 137 Cs and other products of nuclear fission. The oxygen isotopic ratio ( 18 O/ 16 O) was determined by mass spectrometry. The provenance has been established for this fine silt fraction which reflects the relative proportion of two classes of quartz source: (a) weathering of igneous and metamorphic rocks (high temperature origin and low 18 O/ 16 O ratio) and (b) of quartz crystallized in cherts and overgrowths (low temperature origin and high 18 O/ 16 O ratio). This quartz mixing ratio is a basic model or paradigm. Analyses of present day atmospheric aerosols and eolian-derived soils, Pacific pelagic sediments, and now-raised Phanerozoic marine sediments show that the Northern and Southern Hemispheres have separate large-scale reservoirs of the fine grain sizes that contribute to aerosol dusts. These can be identified by distinctive values of 18 O/ 16 O ratios of the quartz therein. The difference in quartz delta 18 O value in parts per thousand per ml ( 0 / 00 of about 12 +- 2 0 / 00 in Southern Hemisphere mixed detrital sediments and about 19 +- 2 0 / 00 in those of the Northern Hemisphere (for constant size, the 1-10 μm size fraction) results from the presence of a considerably larger proportion of quartz having low-temperature origin and higher delta 18 O values (chert, silica overgrowths, etc.) in the Northern Hemisphere reservoirs. The early paleoclimatic and paleogeochemical differences remain the control of the North-South Hemisphere difference in delta 18 O values in long-range aerosol sized quartz

OSL and IRSL characteristics of quartz and feldspar from southern California, USA

International Nuclear Information System (INIS)

Lawson, Michael J.; Roder, Belinda J.; Stang, Dallon M.; Rhodes, Edward J.

2012-01-01

Southern California comprises of a wide range of diverse landscapes and environments, from high mountains with glacial and periglacial sediments to deserts with large sand dunes, extensive alluvial fans and ephemeral playas. Highly active tectonic processes has exposed ancient (c. 2 Ga) plutonic and metamorphic basement from deep within the crust, while similar Palaeozoic, Mesozoic and Cenozoic rocks are also common. A rich array of volcanic lithologies extending into the late Quaternary complement many thick sedimentary sequences that formed in equally diverse ancient environments typical of an accreting active continental margin. In some locations, notably in the Coachella Valley close to Palm Springs and the Salton Sea, low OSL sensitivity and poor characteristics restrict the application of the quartz SAR protocol to date late Pleistocene and Holocene fluvial sediments. In other locations such as the Malibu coastline, high sensitivity of the quartz OSL signal is observed, despite local source rocks being dominated by volcanic lithologies. Problems of poor quartz characteristics, along with uncertainty in predicting quartz OSL behavior for future dating campaigns poses a significant problem for projects, in particular for neotectonic contexts. While K-feldspar has been used extensively to date eolian and fluvial sediments in southern California, little information regarding signal stability is available. We explore the characteristics of both quartz and feldspar sub-samples from eolian, fluvial, lacustrine environments, in order to help develop mineral selection criteria for optical dating applications and clarify these issues. The importance of radiation quenching in quartz grains recently eroded from bedrock and the role of fires in enhancing OSL sensitivity are considered. The relative bleachability of quartz and feldspar fractions, along with thermal stability considerations is discussed. A simple test for quartz OSL signal contamination based on thermal

Analysis of Halogen-Mercury Reactions in Flue Gas

Energy Technology Data Exchange (ETDEWEB)

Paula Buitrago; Geoffrey Silcox; Constance Senior; Brydger Van Otten

2010-01-01

Oxidized mercury species may be formed in combustion systems through gas-phase reactions between elemental mercury and halogens, such as chorine or bromine. This study examines how bromine species affect mercury oxidation in the gas phase and examines the effects of mixtures of bromine and chlorine on extents of oxidation. Experiments were conducted in a bench-scale, laminar flow, methane-fired (300 W), quartz-lined reactor in which gas composition (HCl, HBr, NO{sub x}, SO{sub 2}) and temperature profile were varied. In the experiments, the post-combustion gases were quenched from flame temperatures to about 350 C, and then speciated mercury was measured using a wet conditioning system and continuous emissions monitor (CEM). Supporting kinetic calculations were performed and compared with measured levels of oxidation. A significant portion of this report is devoted to sample conditioning as part of the mercury analysis system. In combustion systems with significant amounts of Br{sub 2} in the flue gas, the impinger solutions used to speciate mercury may be biased and care must be taken in interpreting mercury oxidation results. The stannous chloride solution used in the CEM conditioning system to convert all mercury to total mercury did not provide complete conversion of oxidized mercury to elemental, when bromine was added to the combustion system, resulting in a low bias for the total mercury measurement. The use of a hydroxylamine hydrochloride and sodium hydroxide solution instead of stannous chloride showed a significant improvement in the measurement of total mercury. Bromine was shown to be much more effective in the post-flame, homogeneous oxidation of mercury than chlorine, on an equivalent molar basis. Addition of NO to the flame (up to 400 ppmv) had no impact on mercury oxidation by chlorine or bromine. Addition of SO{sub 2} had no effect on mercury oxidation by chlorine at SO{sub 2} concentrations below about 400 ppmv; some increase in mercury oxidation

Microscopy and Cathodoluminescence Spectroscopy Characterization of Quartz Exhibiting Different Alkali-Silica Reaction Potential.

Science.gov (United States)

Kuchařová, Aneta; Götze, Jens; Šachlová, Šárka; Pertold, Zdeněk; Přikryl, Richard

2016-02-01

Different quartz types from several localities in the Czech Republic and Sweden were examined by polarizing microscopy combined with cathodoluminescence (CL) microscopy, spectroscopy, and petrographic image analysis, and tested by use of an accelerated mortar bar test (following ASTM C1260). The highest alkali-silica reaction potential was indicated by very fine-grained chert, containing significant amounts of fine-grained to cryptocrystalline matrix. The chert exhibited a dark red CL emission band at ~640 nm with a low intensity. Fine-grained orthoquartzites, as well as fine-grained metamorphic vein quartz, separated from phyllite exhibited medium expansion values. The orthoquartzites showed various CL of quartz grains, from blue through violet, red, and brown. Two CL spectral bands at ~450 and ~630 nm, with various intensities, were detected. The quartz from phyllite displayed an inhomogeneous dark red CL with two CL spectral bands of low intensities at ~460 and ~640 nm. The massive coarse-grained pegmatite quartz from pegmatite was assessed to be nonreactive and displayed a typical short-lived blue CL (~480 nm). The higher reactivity of the fine-grained hydrothermal quartz may be connected with high concentrations of defect centers, and probably with amorphized micro-regions in the quartz, respectively; indicated by a yellow CL emission (~570 nm).

Is there theoretical evidence for mutual influence between halogen

Indian Academy of Sciences (India)

Based on many-body analysis, two and three-body terms of interaction energies have a positive contribution to the total interaction energy. It was found that the amount of charge transfer in the triads is higher than that in the corresponding dyads. AIM analyses showed that the halogen and pnicogen-hydride bonds in the ...

A Protein Data Bank survey reveals shortening of intermolecular hydrogen bonds in ligand-protein complexes when a halogenated ligand is an H-bond donor.

Directory of Open Access Journals (Sweden)

Jarosław Poznański

Full Text Available Halogen bonding in ligand-protein complexes is currently widely exploited, e.g. in drug design or supramolecular chemistry. But little attention has been directed to other effects that may result from replacement of a hydrogen by a strongly electronegative halogen. Analysis of almost 30000 hydrogen bonds between protein and ligand demonstrates that the length of a hydrogen bond depends on the type of donor-acceptor pair. Interestingly, lengths of hydrogen bonds between a protein and a halogenated ligand are visibly shorter than those estimated for the same family of proteins in complexes with non-halogenated ligands. Taking into account the effect of halogenation on hydrogen bonding is thus important when evaluating structural and/or energetic parameters of ligand-protein complexes. All these observations are consistent with the concept that halogenation increases the acidity of the proximal amino/imino/hydroxyl groups and thus makes them better, i.e. stronger, H-bond donors.

Absorption and luminescence of crystalline quartz under electron nanosecond irradiation

Energy Technology Data Exchange (ETDEWEB)

Gritsenko, B P; Lisitsyn, V M; Stepanchuk, V N [Tomskij Politekhnicheskij Inst. (USSR)

1981-02-01

The purpose of the study is continuation of investigations of principal regularities of production and destruction of short-lived defects in quartz and accompanying luminescence under electron pulse irradiation. For investigation purposes samples of crystalline synthetic quartz have been used. The irradiation has been performed at 80-400 K temperatures by means of an electron pulse accelerator with parameters: electron flow pulse duration 10 ns, pulse current density up to 1000 A/cm/sup 2/, electron mean energy 200 keV. Temperature-time characteristics of absorption and luminescence spectrum are studied. It has been found that quartz irradiation by electron pulses of nanosecond duration leads to appearance of short-lived bands of optical absorption at 4.1 and 5.15 eV to which by kinetic parameters correspond luminescence bands at 2.6 and 3.1 eV, respectively. The enumerated absorption bands are induced by quartz irradiation independently of the prehistory and phase state of the sample and are caused obviously by intrinsic radiation defects. Possible models of such defects are suggested.

Study of green quartz of hydrothermal origin treated by gamma radiation

International Nuclear Information System (INIS)

Enokihara, Cyro Teiti

2013-01-01

A specific variety of quartz showing a green color in nature or induced artificially by radiation is quite rare. This can be explained by the fact that the mechanism of formation of this color is very different from the ones widely discussed in the literature and responsible for the formation of the fumee, citrine and amethyst types of quartz, including the prasiolite (leak green quartz) formed by heating amethyst from Montezuma, Brazil. Only two occurrences are known today, where this type of quartz can be found: Canada, at the Thunder Bay Amethyst Mine, Ontario, a small district, and Brazil, at widely scattered geode occurrences along a 600 km stretch from Quarai at Brazils southernmost tip to Uberlandia in Minas Gerais. These two occurrences have been formed by strong hydrothermal activities, at Thunder Bay due to tectonics and in Brazil by meteoric and hydrothermal waters of the Guarani aquifer. That way much quartz crystals showed a very fast growth history facilitating the formation of growth defects (twinning, small angle tilting, mosaic growth, striations) and the uptake of water in form of micro inclusions, molecular water, silanol (Si-OH) and OH. This type of quartz can be considered 'wet quartz', similar to synthetic quartz. The water content with up to 3200 ppm by weight exceeds the amount of charge balancing cations (Fe, Al, Li). There is no correlation between water content and cations as in other color varieties. Instead, silanol complexes are formed, which by radiation due to gamma rays form the color center NBOHC (non-bonding oxygen hole defect), showing absorption between 590 to 620 nm and leaving a transmission window at about 550nm, responsible for the green color. To characterize samples which will be colored green by gamma rays analyses by ICP, NAA, Electron microscopy, water loss techniques and UV-VIS and NIR-FTIR spectroscopic have been made. The spectroscopic water determination showed less water (up to 2300 ppm by weight) compared with

Correct interpretation of diffraction properties of quartz crystals for X-ray optics applications

Energy Technology Data Exchange (ETDEWEB)

Huang, Xian-Rong; Gog, Thomas; Kim, Jungho; Kasman, Elina; Said, Ayman H.; Casa, Diego M.; Wieczorek, Michael; Hönnicke, Marcelo G.; Assoufid, Lahsen

2018-02-01

Quartz has hundreds of strong Bragg reflections that may offer a great number of choices for making fixed-angle X-ray analyzers and polarizers at virtually any hard X-ray energies with selectable resolution. However, quartz crystals, unlike silicon and germanium, are chiral and may thus appear in two different forms of handedness that are mirror images. Furthermore, because of the threefold rotational symmetry along thecaxis, the {h₁h₂h₃L} and {h₂h₁h₃L} Bragg reflections may have quite different Darwin bandwidth, reflectivity and angular acceptance, although they have the same Bragg angle. The design of X-ray optics from quartz crystals therefore requires unambiguous determination of the orientation, handedness and polarity of the crystals. The Laue method and single-axis diffraction technique can provide such information, but the variety of conventions used in the literature to describe quartz structures has caused widespread confusion. The current studies give detailed guidelines for design and fabrication of quartz X-ray optics, with special emphasis on the correct interpretation of Laue patterns in terms of the crystallography and diffraction properties of quartz. Meanwhile, the quartz crystals examined were confirmed by X-ray topography to have acceptably low densities of dislocations and other defects, which is the foundation for developing high-resolution quartz-based X-ray optics.

Laboratory Investigations of Stratospheric Halogen Chemistry

Science.gov (United States)

Wine, Paul H.; Nicovich, J. Michael; Stickel, Robert E.; Hynes, Anthony J.

1997-01-01

A final report for the NASA-supported project on laboratory investigations of stratospheric halogen chemistry is presented. In recent years, this project has focused on three areas of research: (1) kinetic, mechanistic, and thermochemical studies of reactions which produce weakly bound chemical species of atmospheric interest; (2) development of flash photolysis schemes for studying radical-radical reactions of stratospheric interest; and (3) photochemistry studies of interest for understanding stratospheric chemistry. The first section of this paper contains a discussion of work which has not yet been published. All subsequent chapters contain reprints of published papers that acknowledge support from this grant.

The Halogenated Metabolism of Brown Algae (Phaeophyta, Its Biological Importance and Its Environmental Significance

Directory of Open Access Journals (Sweden)

Stéphane La Barre

2010-03-01

Full Text Available Brown algae represent a major component of littoral and sublittoral zones in temperate and subtropical ecosystems. An essential adaptive feature of this independent eukaryotic lineage is the ability to couple oxidative reactions resulting from exposure to sunlight and air with the halogenations of various substrates, thereby addressing various biotic and abiotic stresses i.e., defense against predators, tissue repair, holdfast adhesion, and protection against reactive species generated by oxidative processes. Whereas marine organisms mainly make use of bromine to increase the biological activity of secondary metabolites, some orders of brown algae such as Laminariales have also developed a striking capability to accumulate and to use iodine in physiological adaptations to stress. We review selected aspects of the halogenated metabolism of macrophytic brown algae in the light of the most recent results, which point toward novel functions for iodide accumulation in kelps and the importance of bromination in cell wall modifications and adhesion properties of brown algal propagules. The importance of halogen speciation processes ranges from microbiology to biogeochemistry, through enzymology, cellular biology and ecotoxicology.

Geospatializing The Klang Gate Quartz Ridge in Malaysia: A Technological Perspective

Science.gov (United States)

Azahari Razak, Khamarrul; Mohamad, Zakaria; Zaki Ibrahim, Mohd; Azad Rosle, Qalam; Hattanajmie Abd Wahab, Mohd; Abu Bakar, Rabieahtul; Mohd Akib, Wan Abdul Aziz Wan

2015-04-01

Establishment of inventories on geological heritage, or geoheritage resources is a step forward for a comprehensive geoheritage management leading to a better conservation at national and global levels. Compiling and updating inventory of geoheritage is a tedious process and even so in a tropical environment. Malaysia has a tremendous list of geodiversity and generating its national database is a multi-institutional effort and worthwhile investment. However, producing accurate and reliable characteristics of such landform and spectacular geological features remained elusive. The advanced and modern mapping techniques have revolutionized the mapping, monitoring and modelling of the earth surface processes and landforms. Yet the methods for quantification of geodiversity physical features are not fully utilized in Malaysia for a better understanding its processes and activity. This study provides a better insight into the use of advanced active remote sensing technology for characterizing the forested Quartz Ridge in Malaysia. We have developed the novel method and tested in the Klang Gates Quartz Ridge, Selangor. The granitic country rock made up by quartz mineral is known as the longest quartz ridge in Malaysia and characterized by rugged topography, steep slopes, densely vegetated terrain and also rich-biodiversity area. This study presents an integrated field methodological framework and processing scheme by taking into account the climatic, topographic, geologic, and anthropogenic challenges in an equatorial region. Advanced terrestrial laser scanning system was used to accurately capture, map and model the ridge carried out within a relatively stringent time period. The high frequency Global Navigation Satellite System and modern Total Station coupled with the optical satellite and radar imageries and also advanced spatial analysis were fully utilized in the field campaign and data assessment performed during the recent monsoon season. As a result, the mapping

Complex impedance spectroscopy of alkali impurities in as-grown, irradiated and annealed quartz

International Nuclear Information System (INIS)

Devautour-Vinot, S.; Cambon, O.; Prud'homme, N.; Giuntini, J. C.; Boy, J.-J.; Cibiel, G.

2007-01-01

This work compares the dielectric relaxation properties of different crystalline quartz materials, according to their source (natural or synthetics). It is shown that these relaxation properties are due to a hopping process of alkaline (Li + , Na + , and K + ) impurities located near [Al-O 4 ] 5- tetrahedra. A detailed analysis, in terms of the distribution function of the dielectric loss peak, allowed us to perfectly distinguish the different types of as-grown quartz. We show that (i) the natural quartz has less stable M + charge carriers than the synthetic materials and that (ii) the homogeneity of the M + trapping sites, created by the [Al-O 4 ] 5- tetrahedra, strongly depends on the crystal growth conditions. These features were then studied using quartz samples with different treatment conditions: as-grown, irradiated, or annealed at high temperature. We propose that the irradiation greatly facilitates the M + relaxation, by creating additional low energy M + hosting sites, whose number depends on the source of the quartz crystals. We also show that for 100 krad irradiation, the saturation state of the defects is already reached for all the materials under consideration. Finally, we propose that the irradiation followed by annealing at 450 deg. C improves the M + stability and homogeneity in quartz materials, compared with the as-grown materials, this trend being much more relevant for the natural than for the synthetic quartz

Stable isotope compositions of quartz pebbles and their fluid inclusions as tracers of sediment provenance: Implications for gold- and uranium-bearing quartz pebble conglomerates

Energy Technology Data Exchange (ETDEWEB)

Vennemann, T.W.; Kesler, S.E.; O' Neil, J.R. (Univ. of Michigan, Ann Arbor (United States))

1992-09-01

Oxygen isotope compositions of pebbles from late Archean to paleo-Proterozoic gold- and/or uranium-bearing oligomictic quartz pebble conglomerates of the Witwatersrand district, South Africa, and Huronian Supergroup, Canada, were determined in an attempt to define the nature of the source terrain. The [delta][sup 18]O values of quartz pebbles within any one sample typically vary by [approximately] 4[per thousand] or more, but occasionally by as much as 8[per thousand], even for adjacent pebbles within the same hand specimen. In addition, adjacent quartz pebbles of widely contrasting [delta][sup 18]O values also preserve distinct isotopic signatures of their fluid inclusions. This overall heterogeneity suggests that the pebbles did not undergo significant oxygen isotope exchange after incorporation in the conglomerates. Therefore, oxygen isotope analyses of such quartz pebbles, in combination with a detailed investigation of their mineral and fluid inclusions, can provide a useful method for characterizing pebble populations and hence dominant sediment source modes. Comparison of values found in this study with [delta][sup 18]O values of quartz from Archean granites, pegmatites, and mesothermal greenstone gold veins, i.e., [delta][sup 18]O values of sources commonly proposed for the conglomerate ores, suggests that uranium is derived from a granitic source, whereas gold has a mesothermal greenstone gold source. Low [delta][sup 18]O values of chert pebbles (9[per thousand] to 11.5[per thousand]) relative to those expected for Archean and Proterozoic marine cherts (commonly [ge] 17[per thousand]) effectively exclude marine cherts, and therefore, auriferous iron formations and exhalatives, as likely sources of gold.

Stable isotope compositions of quartz pebbles and their fluid inclusions as tracers of sediment provenance: Implications for gold- and uranium-bearing quartz pebble conglomerates

International Nuclear Information System (INIS)

Vennemann, T.W.; Kesler, S.E.; O'Neil, J.R.

1992-01-01

Oxygen isotope compositions of pebbles from late Archean to paleo-Proterozoic gold- and/or uranium-bearing oligomictic quartz pebble conglomerates of the Witwatersrand district, South Africa, and Huronian Supergroup, Canada, were determined in an attempt to define the nature of the source terrain. The δ 18 O values of quartz pebbles within any one sample typically vary by ∼ 4 per-thousand or more, but occasionally by as much as 8 per-thousand, even for adjacent pebbles within the same hand specimen. In addition, adjacent quartz pebbles of widely contrasting δ 18 O values also preserve distinct isotopic signatures of their fluid inclusions. This overall heterogeneity suggests that the pebbles did not undergo significant oxygen isotope exchange after incorporation in the conglomerates. Therefore, oxygen isotope analyses of such quartz pebbles, in combination with a detailed investigation of their mineral and fluid inclusions, can provide a useful method for characterizing pebble populations and hence dominant sediment source modes. Comparison of values found in this study with δ 18 O values of quartz from Archean granites, pegmatites, and mesothermal greenstone gold veins, i.e., δ 18 O values of sources commonly proposed for the conglomerate ores, suggests that uranium is derived from a granitic source, whereas gold has a mesothermal greenstone gold source. Low δ 18 O values of chert pebbles (9 per-thousand to 11.5 per-thousand) relative to those expected for Archean and Proterozoic marine cherts (commonly ≥ 17 per-thousand) effectively exclude marine cherts, and therefore, auriferous iron formations and exhalatives, as likely sources of gold

Dew point fast measurement in organic vapor mixtures using quartz resonant sensor

Science.gov (United States)

Nie, Jing; Liu, Jia; Meng, Xiaofeng

2017-01-01

A fast dew point sensor has been developed for organic vapor mixtures by using the quartz crystal with sensitive circuits. The sensor consists of the quartz crystal and a cooler device. Proactive approach is taken to produce condensation on the surface of the quartz crystal, and it will lead to a change in electrical features of the quartz crystal. The cessation of oscillation was measured because this phenomenon is caused by dew condensation. Such a phenomenon can be used to detect the dew point. This method exploits the high sensitivity of the quartz crystal but without frequency measurement and also retains the stability of the resonant circuit. It is strongly anti-interfered. Its performance was evaluated with acetone-methanol mixtures under different pressures. The results were compared with the dew points predicted from the universal quasi-chemical equation to evaluate the performance of the proposed sensor. Though the maximum deviations of the sensor are less than 1.1 °C, it still has a fast response time with a recovery time of less than 10 s, providing an excellent dehumidifying performance.

High energy halogen atom reactions activated by nuclear transformations. Progress report, February 15, 1980-February 14, 1981

International Nuclear Information System (INIS)

1981-02-01

The stereochemistry of high energy 18 F, /sup 34m/Cl, and 76 Br substitution reactions involving enantiomeric molecules in the gas and condensed phase is studied. The gas to condensed state transition in halogen high energy chemistry, involving chlorine, bromine, and iodine activated by the (n,γ) and (I.T.) processes in halomethanes, saturated and unsaturated hydrocarbons is being investigated in more detail. Special attention is given to defining the nature of the enhancement yields in the condensed phase. High energy halogen reactions in liquid and frozen aqueous solutions of organic and biomolecular solutes are studied in an attempt to learn more about these reactions. The applications of high energy chemistry techniques and theory to neutron activation analysis of biological systems are being continued. Special attention is given to developing procedures for trace molecular determinations in biological systems. The applications of hot halogen atoms as indicators of solute-solute interactions in liquid and frozen aqueous solutions of halogenated bases and nucleosides are being developed. Experiments are designed to explain the mechanisms of the radioprotection offered biomolecular solutes trapped within the frozen ice lattice. Reactions of bromine and iodine activated by isomeric transition with halogenated biomolecular solutes in liquid and frozen aqueous solutions are studied. The high energy reactions of iodine with the isomers of pentene have been studied in low pressure gaseous systems employing additives and rare gas moderators and liquid systems. Reactivity of excited complex formation and structural effects of electrophilic iodine attack on the pi-bond systems are studied

High energy halogen atom reactions activated by nuclear transformations. Progress report, February 15, 1980-February 14, 1981

Energy Technology Data Exchange (ETDEWEB)

1981-02-01

The stereochemistry of high energy /sup 18/F, /sup 34m/Cl, and /sup 76/Br substitution reactions involving enantiomeric molecules in the gas and condensed phase is studied. The gas to condensed state transition in halogen high energy chemistry, involving chlorine, bromine, and iodine activated by the (n,..gamma..) and (I.T.) processes in halomethanes, saturated and unsaturated hydrocarbons is being investigated in more detail. Special attention is given to defining the nature of the enhancement yields in the condensed phase. High energy halogen reactions in liquid and frozen aqueous solutions of organic and biomolecular solutes are studied in an attempt to learn more about these reactions. The applications of high energy chemistry techniques and theory to neutron activation analysis of biological systems are being continued. Special attention is given to developing procedures for trace molecular determinations in biological systems. The applications of hot halogen atoms as indicators of solute-solute interactions in liquid and frozen aqueous solutions of halogenated bases and nucleosides are being developed. Experiments are designed to explain the mechanisms of the radioprotection offered biomolecular solutes trapped within the frozen ice lattice. Reactions of bromine and iodine activated by isomeric transition with halogenated biomolecular solutes in liquid and frozen aqueous solutions are studied. The high energy reactions of iodine with the isomers of pentene have been studied in low pressure gaseous systems employing additives and rare gas moderators and liquid systems. Reactivity of excited complex formation and structural effects of electrophilic iodine attack on the pi-bond systems are studied.

Influence of hydrogen on optical destruction of the irradiated quartz glass

International Nuclear Information System (INIS)

Bedilov, M.R.; Beysembayeva, Kh.B.; Sabitov, M.S.

2002-01-01

The influence of concentration impurity of hydrogen on optical destruction of a quartz glass was investigated. As objects of researches the fragments of capsules of industrial lamps OQG, intended for job in low and hard load operation, modes i.e. lamp IFF-500 and IFF-8000 respectively were taken. The results of the elemental analysis of capsules lamps IFF-500 and IFF-8000 showed their complete identity. The exception was made only for an impurity of H, contents of which in a material of an environment of a lamp capsule IFF-500 was almost of the order higher than in quartz glass of lamp capsule IFF-8000 (10 -2 %). Absence in structure of investigated by us of Cl ions, as well as the available concentration of H, allowed to make the conclusion, that the quartz glasses used for manufacturing of environments of lamps capsules, investigated by us, are the full pump lamps and represent glasses of gas melt up; and the quartz glass of a lamp IFF-500 was melt- up or is processed in hydrogen. As of spectra of absorption results of research showed, quartz glass of an of a lamp capsule IFF-500, containing highest quantity impurity of hydrogen, at flux, not exceeding 10 18 neutron/cm 2 , is less painted in comparison with an capsule IFF-8000. Smaller density of coloring of capsules containing higher concentration H, is connected to the hydrogen, existing in glass, blocks the potential centers of capture holes as defective aluminum oxygen tetrahedron of non-bridge of oxygen. The authors found out, that at high γ-radiation and influence flux of neutrons leads to degradation of regular ≡Si-O-Si≡ connections in quartz glasses producing defects as non-bridge oxygen and three-coordinate of silicon, and also production of vacancies of oxygen. By results of the researches, carried out by us, at increase of concentration of hydrogen ions in quartz glass process of structural defective formation intensifies. Research of beam durability of quartz glasses of environments of not

BENTONITE-QUARTZ SAND AS THE BACKFILL MATERIALS ON THE RADIOACTIVE WASTE REPOSITORY

Directory of Open Access Journals (Sweden)

Raharjo Raharjo

2010-06-01

Full Text Available An investigation of the contribution of quartz sand in the bentonite mixture as the backfill materials on the shallow land burial of radioactive waste has been done. The experiment objective is to determine the effect of quartz sand in a bentonite mixture with bentonite particle sizes of -20+40, -40+60, and -60+80 mesh on the retardation factor and the uranium dispersion in the simulation of uranium migration in the backfill materials. The experiment was carried out by the fixed bed method in the column filled by the bentonite mixture with a bentonite-to-quartz sand weight percent ratio of 0/100, 25/75, 50/50, 75/25, and 100/0 on the water saturated condition flown by uranyl nitrate solution at concentration (Co of 500 ppm. The concentration of uranium in the effluents in interval 15 minutes represented as Ct was analyzed by spectrophotometer, then using Co and Ct, retardation factor (R and dispersivity ( were determined. The experiment data showed that the bentonite of -60+80 mesh and the quartz sand of -20+40 mesh on bentonite-to-quartz sand with weight percent ratio of 50/50 gave the highest retardation factor and dispersivity of 18.37 and 0.0363 cm, respectively.   Keywords: bentonite, quartz sand, backfill materials, radioactive waste

Neutron activation analysis for study of distribution patterns of organo-halogen pollutants in apple

International Nuclear Information System (INIS)

Zhang Hong; Luo Jialing; Sun Huibin; Chai Zhifang; Chinese Academy of Sciences, Beijing

2007-01-01

The distribution characteristics of organo-halogens in apple and their sources were studied by neutron activation analysis combined with statistical analysis. The results indicated that concentrations of organo-halogens in apple were in the order of organo-chlorine >> organo-bromine > organo-iodine, and concentrations of the organo-chlorine in four parts of apple were in the order of seed >> peel >> endocarp ≥ pulp. Also, the organo-chlorine, -bromine and-iodine in apple were found to have different sources. The latter two were mainly from naturally synthetic products by plant itself, while the former was mainly from anthropogenic pollutants. (authors)

Halogen effect for improving high temperature oxidation resistance of Ti-50Al by anodization

Science.gov (United States)

Mo, Min-Hua; Wu, Lian-Kui; Cao, Hua-Zhen; Lin, Jun-Pin; Zheng, Guo-Qu

2017-06-01

The high temperature oxidation resistance of Ti-50Al was significantly improved via halogen effect which was achieved by anodizing in an ethylene glycol solution containing with fluorine ion. The anodized Ti-50Al with holes and micro-cracks could be self-repaired during oxidation at 1000 °C. The thickness of the oxide scale increases with the prolonging of oxidation time. On the basis of halogen effect for improving the high temperature oxidation resistance of Ti-50Al by anodization, only fluorine addition into the electrolyte can effectively improve the high temperature oxidation resistance of Ti-50Al.

Boiling Heat Transfer to Halogenated Hydrocarbon Refrigerants

Science.gov (United States)

Yoshida, Suguru; Fujita, Yasunobu

The current state of knowledge on heat transfer to boiling refrigerants (halogenated hydrocarbons) in a pool and flowing inside a horizontal tube is reviewed with an emphasis on information relevant to the design of refrigerant evaporators, and some recommendations are made for future research. The review covers two-phase flow pattern, heat transfer characteristics, correlation of heat transfer coefficient, influence of oil, heat transfer augmentation, boiling from tube-bundle, influence of return bend, burnout heat flux, film boiling, dryout and post-dryout heat transfer.

Recent progress in the performances of ultrastable quartz resonators and oscillators

Directory of Open Access Journals (Sweden)

Salzenstein Patrice

2016-01-01

Full Text Available Stressed compensated (SC cut led recently to the best frequency stability ever obtained with a quartz oscillator, 2.5 × 10−14 for the flicker frequency modulation (FFM floor. This result is confirmed in this paper with a 3.2 × 10−14 ± 1.1 × 10−14. The quartz resonator is integrated in a 5 MHz enhanced aging box double oven controlled oscillator. After reminding a bit of history, this paper describes how the first significant development in terms of ultra-stable quartz state-of-the-art oscillators was performed in the last 20 years, how the resonators were chosen, and main information about the development of adequate electronics and how to mechanically and thermally stabilized such an ultra-stable oscillator. We also present how to characterize the expected performances, and hot topics in quartz based oscillators.

Gas-liquid partitioning of halogenated volatile organic compounds in aqueous cyclodextrin solutions

Energy Technology Data Exchange (ETDEWEB)

Ondo, Daniel; Barankova, Eva [Department of Physical Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6 (Czech Republic); Dohnal, Vladimir, E-mail: dohnalv@vscht.cz [Department of Physical Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6 (Czech Republic)

2011-08-15

Highlights: > Binding of halogenated VOCs with cyclodextrins examined through g-l partitioning. > Complex stabilities reflect host-guest size matching and hydrophobic interaction. > Presence of halogens in the guest molecule stabilizes the binding. > Thermodynamic origin of the binding varies greatly among the systems studied. > Results obey the guest-CD global enthalpy-entropy compensation relationship. - Abstract: Gas-liquid partitioning coefficients (K{sub GL}) were measured for halogenated volatile organic compounds (VOCs), namely 1-chlorobutane, methoxyflurane, pentafluoropropan-1-ol, heptafluorobutan-1-ol, {alpha},{alpha},{alpha}-trifluorotoluene, and toluene in aqueous solutions of natural {alpha}-, {beta}-, and {gamma}-cyclodextrins (CDs) at temperatures from (273.35 to 326.35) K employing the techniques of headspace gas chromatography and inert gas stripping. The binding constants of the 1:1 inclusion complex formation between the VOCs and CDs were evaluated from the depression of the VOCs volatility as a function of CD concentration. The host-guest size matching and the hydrophobic interaction concept were used to rationalize the observed widely different affinity of the VOC-CD pairs to form the inclusion complex. The enthalpic and entropic component of the standard Gibbs free energy of complex formation as derived from the temperature dependence of the binding constant indicate the thermodynamic origin of the binding to vary greatly among the systems studied, but follow the global enthalpy-entropy compensation relationships reported previously in the literature.

Hydration of the Atlantis Massif: Halogen, Noble Gas and In-Situ δ18O Constraints

Science.gov (United States)

Williams, M. J.; Kendrick, M. A.; Rubatto, D.

2017-12-01

A combination of halogen (Cl, Br, I), noble gases (He, Ne, Ar, Kr and Xe) and in situ oxygen isotope analysis have been utilized to investigate the fluid-mobile element record of hydration and alteration processes at the Atlantis Massif (30°N on the Mid-Atlantic Ridge). The sample suite investigated includes serpentinite, talc-amphibole ± chlorite schist and hydrated gabbro recovered by seafloor drilling undertaken at sites on a transect across the Atlantis Massif during IODP Expedition 357. Serpentine mesh and veins analysed in-situ by SHRIMP SI exhibit δ18O from 6‰ down to ≈0‰, suggesting serpentinization temperatures of 150 to >280°C and water/rock ratios >5. Differences of 1.5-2.5‰ are observed between adjacent generations of serpentine, but the δ18O range is similar at each investigated drilling site. Halogen and noble gas abundances in serpentinites, talc-amphibole schist and hydrated gabbro have been measured by noble gas mass spectrometry of both irradiated and non-irradiated samples. Serpentinites contain low abundances of halogens and noble gases (e.g. 70-430 ppm Cl, 4.7-12.2 x 10-14 mol/g 36Ar) relative to other seafloor serpentinites. The samples have systematically different Br/Cl and I/Cl ratios related to their mineralogy. Serpentinites retain mantle-like Br/Cl with a wide variation in I/Cl that stretches toward seawater values. Talc-amphibole schists exhibit depletion of Br and I relative to Cl with increasing Cl abundances, suggesting tremolite exerts strong control on halogen abundance ratios. Serpentinites show no evidence of interaction with halogen-rich sedimentary pore fluids. Iodine abundances are variable across serpentinites, and are decoupled from Br and Cl; iodine enrichment (up to 530 ppb) is observed within relatively oxidised and clay-bearing samples. Serpentinized harzburgites exhibit distinct depletion of Kr and Xe relative to atmospheric 36Ar in seawater. Oxygen isotope compositions and low abundances of both halogens

Mid-latitude Ozone Depletion Events Caused by Halogens from the Great Salt Lake in Utah

Science.gov (United States)

Fibiger, D. L.; Goldberger, L.; Womack, C.; McDuffie, E. E.; Dube, W. P.; Franchin, A.; Middlebrook, A. M.; Thornton, J. A.; Brown, S. S.

2017-12-01

Halogens are highly reactive chemicals and play an important role in atmospheric chemistry. They can be involved in many cycles which influence the oxidizing capacity of the atmosphere, including through destruction of ozone (O3). While the influence of halogens on O3 is well documented in the arctic, there are very few observations of O3 depletion driven by halogens in the mid-latitudes. To date, the most comprehensive study observed co-occurring plumes of BrO and depleted O3 near the Dead Sea in 1997. During the Utah Wintertime Fine Particulate Study (UWFPS) in winter 2017, simultaneous measurements of a comprehensive suite of halogen measurements by I- chemical ionization mass spectrometry and O3 from cavity ring-down spectroscopy, both at 1-second time resolution, were taken on a NOAA Twin Otter Aircraft over the Great Salt Lake and in the surrounding valleys. Many O3 depletion events were observed over the lake with O3 values sometimes below the instrument detection limit of 0.5 ppbv. Corresponding increases in BrO and/or ClO were observed. Many of these events were caused by extremely high levels of halogens (up to 1 ppmv Cl2) emitted from the U.S. Magnesium plant on the edge of the lake. The O3 depletion caused by U.S. Magnesium was usually isolated to a distinct vertical layer, but in other cases O3 depletion was vertically mixed and the origin of halogen activation was not immediately clear. The most complete O3 depletion was observed over the lake, but there were smaller events of a few ppbv observed in the adjacent valleys, including the highly populated Salt Lake Valley, with corresponding plumes of BrO and ClO, due to transport from the lake. Additionally, meteorology played a role in the observed O3 depletion. The strongest O3 depletion was observed during inversion events, when there is a low boundary layer and little mixing out of the air above the lake. During non-inversion conditions, only small depletions were observed, covering a much smaller

Origin of the X-Hal (Hal = Cl, Br) bond-length change in the halogen-bonded complexes.

Science.gov (United States)

Wang, Weizhou; Hobza, Pavel

2008-05-01

The origin of the X-Hal bond-length change in the halogen bond of the X-Hal...Y type has been investigated at the MP2(full)/6-311++G(d,p) level of theory using a natural bond orbital analysis, atoms in molecules procedure, and electrostatic potential fitting methods. Our results have clearly shown that various theories explaining the nature of the hydrogen bond cannot be applied to explain the origin of the X-Hal bond-length change in the halogen bond. We provide a new explanation for this change. The elongation of the X-Hal bond length is caused by the electron-density transfer to the X-Hal sigma* antibonding orbital. For the blue-shifting halogen bond, the electron-density transfer to the X-Hal sigma* antibonding orbital is only of minor importance; it is the electrostatic attractive interaction that causes the X-Hal bond contraction.

A facile approach towards increasing the nitrogen-content in nitrogen-doped carbon nanotubes via halogenated catalysts

International Nuclear Information System (INIS)

Ombaka, L.M.; Ndungu, P.G.; Omondi, B.; McGettrick, J.D.; Davies, M.L.; Nyamori, V.O.

2016-01-01

Nitrogen-doped carbon nanotubes (N-CNTs) have been synthesized at 850 °C via a CVD deposition technique by use of three ferrocenyl derivative catalysts, i.e. para-CN, -CF_3 and -Cl substituted-phenyl rings. The synthesized catalysts have been characterized by NMR, IR, HR-MS and XRD. The XRD analysis of the para-CF_3 catalyst indicates that steric factors influence the X-ray structure of 1,1′-ferrocenylphenyldiacrylonitriles. Acetonitrile or pyridine was used as carbon and nitrogen sources to yield mixtures of N-CNTs and carbon spheres (CS). The N-CNTs obtained from the para-CF_3 catalysts, in pyridine, have the highest nitrogen-doping level, show a helical morphology and are less thermally stable compared with those synthesized by use of the para-CN and -Cl as catalyst. This suggests that fluorine heteroatoms enhance nitrogen-doping in N-CNTs and formation of helical-N-CNTs (H-N-CNTs). The para-CF_3 and para-Cl catalysts in acetonitrile yielded iron-filled N-CNTs, indicating that halogens promote encapsulation of iron into the cavity of N-CNT. The use of acetonitrile, as carbon and nitrogen source, with the para-CN and -Cl as catalysts also yielded a mixture of N-CNTs and carbon nanofibres (CNFs), with less abundance of CNFs in the products obtained using para-Cl catalysts. However, para-CF_3 catalyst in acetonitrile gave N-CNTs as the only shaped carbon nanomaterials. - Graphical abstract: Graphical abstract showing the synthesis of N-CNTs using halogenated-ferrocenyl derivatives as catalyst with pyridine or acetonitrile as nitrogen and carbon sources via the chemical vapour deposition technique. - Highlights: • N-CNTs were synthesized from halogenated ferrocenyl catalysts. • Halogenated catalysts promote nitrogen-doping and pyridinic nitrogen in N-CNTs. • Halogenated catalysts facilitate iron filling of N-CNTs.

Development of a red TL detection system for a single grain of quartz

International Nuclear Information System (INIS)

Yawata, T.; Hashimoto, T.

2007-01-01

Red thermoluminescence (RTL) of natural quartz grains offers many desirable properties for quaternary chronology and archaeological dating, although RTL measurements suffer from high thermal background due to black-body radiation on heating. To reduce the thermal background to as low a level as possible, a silver sample disc covered with a biotite plate with a sample hole was used in combination with a light guide, cluster heater, optical filters, and photomultiplier tube cooling to -20 deg. C in the present system. As a result, the thermal background decreased from 2x10 4 to 1000 cps in the temperature range 350-380 deg. C, resulting in a detection limit of approximately 100 cps, corresponding to the RTL signal from a single quartz grain (250-500μm) irradiated with 4.0 Gy. In addition, application of lower heating rates retarded the thermal quenching effect, resulting in high RTL signals, which are preferable for young or insensitive quartz samples. Using RTL measurements with the single quartz grain method under optimal RTL conditions, comparison of equivalent doses from artificially irradiated single quartz grains to the known dose was within the 20% measurement error. Based on equivalent dose determinations for single quartz grains, large irregularities on non-etched quartz surfaces might be very detrimental to the TL detection process. This result confirms that surface etching treatment is required to achieve reliable dating with high counting efficiency

Long-term Studies of Marine Halogen Release

Science.gov (United States)

Tschritter, J.; Holla, R.; Frieß, U.; Platt, U.

2009-04-01

Institute of Enviromental Physics, Heidelberg, Germany. Long term measurements of atmospheric trace gases using multi-axis DOAS instruments are pursued at the new SOLAS observatory on the island of Sao Vicente, (Cape Verde). This research is part of the SOPRAN (Surface Ocean Processes in the ANthropocene) project (Fördernummer:03F0462F). Reactive halogen species (RHS) such as bromine- and iodine- containing species play major roles in the chemistry of ozone in both the troposphere and lower stratosphere and thus possibly influence the ozone budget on a global scale. In addition iodine-species emitted from the ocean surface have been shown to be responsible for the production of new atmospheric particles in the marine boundary layer. This may have an effect on cloud formation and radiation transfer on local and global scales. Long term measurements of RHS abundances will help to identify their key regions and processes for formation. A new long term Multi-MAX-DOAS instrument has been installed at the SOLAS observatory on the island of Sao Vicente, (Cape Verde). The main focus of these unique measurements is the investigation of reactive halogen chemistry in the subtropical marine boundary layer based on measurements of BrO, IO, and possibly OIO. Because of its wide spectral range also the use for O4-retrievals to gain aerosol profiles is possible. IO has been detected with mixing ratios up to 1.3 ppt. For BrO an upper limit of 2 ppt could be determined.

Process for removing halogenated aliphatic and aromatic compounds from petroleum products. [Polychlorinated biphenyls; methylene chloride; perchloroethylene; trichlorofluoroethane; trichloroethylene; chlorobenzene

Science.gov (United States)

Googin, J.M.; Napier, J.M.; Travaglini, M.A.

1982-03-31

A process for removing halogenated aliphatic and aromatic compounds, e.g., polychlorinated biphenyls, from petroleum products by solvent extraction. The halogenated aliphatic and aromatic compounds are extracted from a petroleum product into a polar solvent by contracting the petroleum product with the polar solvent. The polar solvent is characterized by a high solubility for the extracted halogenated aliphatic and aromatic compounds, a low solubility for the petroleum product and considerable solvent power for polyhydroxy compound. The preferred polar solvent is dimethylformamide. A miscible polyhydroxy compound, such as, water, is added to the polar extraction solvent to increase the polarity of the polar extraction solvent. The halogenated aliphatic and aromatic compounds are extracted from the highly-polarized mixture of polyhydroxy compound and polar extraction solvent into a low polar or nonpolar solvent by contacting the polyhydroxy compound-polar solvent mixture with the low polar or nonpolar solvent. The halogenated aliphatic and aromatic compounds in the low polar or nonpolar solvent by physical means, e.g., vacuum evaporation. The polar and nonpolar solvents are recovered for recycling. The process can easily be designed for continuous operation. Advantages of the process include that the polar solvent and a major portion of the nonpolar solvent can be recycled, the petroleum products are reclaimable and the cost for disposing of waste containing polychlorinated biphenyls is significantly reduced. 2 tables.

Impact of enhanced ozone deposition and halogen chemistry on model performance

Science.gov (United States)

In this study, an enhanced ozone deposition scheme due to the interaction of iodide in sea-water and atmospheric ozone and the detailed chemical reactions of organic and inorganic halogen species are incorporated into the hemispheric Community Multiscale Air Quality model. Prelim...

Tumour radiosensitization with the halogenated pyrimidines 5'-bromo-and 5'-iododeoxyuridine

International Nuclear Information System (INIS)

Epstein, A.H.; Cook, J.A.; Goffman, T.; Glatstein, E.

1993-01-01

The authors review studies of the use of iododeoxyuridine (IdUrd) and bromodeoxyuridine as radiosensitizers and attempt to correlate the clinical outcome for patients treated with radiation and IdUrd with the extent of halogenated pyrimidine cellular uptake and incorporation. (U.K.)

Radiation-Induced Changes in Quartz, A Mineral Analog of Nuclear Power Plant Concrete Aggregates.

Science.gov (United States)

Silva, Chinthaka M; Rosseel, Thomas M; Kirkegaard, Marie C

2018-03-19

Quartz single-crystal samples consisting of α-quartz crystal structure were neutron irradiated to fluences of 5 × 10 18 , 4 × 10 19 , and 2 × 10 20 n/cm 2 (E > 0.1 MeV) at two temperatures (52 and 95 °C). The changes in the α-quartz phase as a function of these two conditions (temperature and fluence) were studied using X-ray powder diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM), and the results acquired using these complementary techniques are presented in a single place for the first time. XRD studies showed that the lattice parameters of α-quartz increased with increasing neutron flux. The lattice growth was larger for the samples that were neutron irradiated at 52 °C than at 95 °C. Moreover, an amorphous content was determined in the quartz samples neutron irradiated at 4 × 10 19 n/cm 2 , with the greater amount being in the 52 °C irradiated sample. Complete amorphization of quartz was observed at a fluence of 2 × 10 20 n/cm 2 (E > 0.1 MeV) using XRD and confirmed by TEM characterization and Raman spectroscopic studies. The cause for α-quartz lattice expansion and sample amorphization was also explored using XRD and Raman spectroscopic studies.

Genomic instability in quartz dust exposed rat lungs: Is inflammation responsible?

Energy Technology Data Exchange (ETDEWEB)

Albrecht, C; Schins, R P F [Institut fuer Umweltmedizinische Forschung (IUF) at the Heinrich Heine University Duesseldorf (Germany); Demircigil, G Cakmak; Coskun, Erdem [Gazi University, Faculty of Pharmacy, Department of Toxicology, Ankara (Turkey); Schooten, F J van [Nutrition and Toxicology Research Institute Maastricht (NUTRIM), Department of Health Risk Analysis and Toxicology, University of Maastricht (Netherlands); Borm, P J A [Centre of Expertise in Life Sciences (Cel), Hogeschool Zuyd, Heerlen (Netherlands); Knaapen, A M, E-mail: catrin.albrecht@uni-duesseldorf.d

2009-02-01

Exposure to quartz dusts has been associated with lung cancer and fibrosis. Although the responsible mechanisms are not completely understood, progressive inflammation with associated induction of persistent oxidative stress has been discussed as a key event for these diseases. Previously we have evaluated the kinetics of pulmonary inflammation in the rat model following a single intratracheal instillation of 2mg DQ12 quartz, either in its native form or upon its surface modification with polyvinylpyridine-N-oxide or aluminium lactate. This model has been applied now to evaluate the role of inflammation in the kinetics of induction of DNA damage and response at 3, 7, 28, and 90 days after treatment. Bronchoalveolar lavage (BAL) cell counts and differentials as well as BAL fluid myeloperoxidase activity were used as markers of inflammation. Whole lung homogenate was investigated to determine the induction of the oxidative and pre-mutagenic DNA lesion 8-hydroxy-2-deoxy-guanosine (8-OHdG) by HPLC/ECD, while mRNA and protein expression of oxidative stress and DNA damage response genes including hemeoxygenase-1 (HO-1) and apurinic/apyrimidinic endonuclease (APE/Ref-1) were evaluated using Western blotting and real time PCR. Isolated lung epithelial cells from the treated rats were used for DNA strand breakage analysis using the alkaline comet assay as well as for micronucleus scoring in May-Gruenwald-Giemsa stained cytospin preparations. In the rats that were treated with quartz, no increased 8-OHdG levels were observed, despite the presence of a marked and persistent inflammation. However, DNA strand breakage in the lung epithelial cells of the quartz treated rats was significantly enhanced at 3 days, but not at 28 days. Moreover, significantly enhanced micronucleus frequencies were observed for all four time points investigated. In the animals that were treated with the PVNO modified quartz, micronuclei scores did not differ from controls, while in those treated with

Noncovalent Halogen Bonding as a Mechanism for Gas-Phase Clustering

DEFF Research Database (Denmark)

Wegeberg, Christina; Donald, William A.; McKenzie, Christine

2017-01-01

in the crystalline phases of PhIO2 and its derivatives serve as models for the structures of larger gas-phase clusters, and calculations on simple model gas-phase dimer and trimer clusters result in similar motifs. This is the first account of halogen bonding playing an extensive role in gas-phase associations....

OSL, TL and IRSL emission spectra of sedimentary quartz and feldspar samples

International Nuclear Information System (INIS)

Lomax, Johanna; Mittelstraß, Dirk; Kreutzer, Sebastian; Fuchs, Markus

2015-01-01

This contribution presents a variety of different luminescence emission spectra from sedimentary feldspar and quartz samples under various stimulation modes. These are green stimulated quartz (OSL-) spectra, quartz TL spectra, feldspar IRSL and post-IR IRSL spectra. A focus was set at recording OSL and IRSL spectra at elevated stimulation temperatures such as routinely applied in luminescence dating. This was to test whether optical stimulation at elevated temperatures results in a shift of emission peaks. For OSL emissions of quartz, this has so far not been tested. In case of feldspar emissions, post-IR IRSL conditions, hence IRSL emissions at a low temperature, directly followed by high temperature post-IRSL emissions, are explicitly investigated. All spectra were recorded using a new system incorporated into a Lexsyg luminescence reader. Thus, this study, besides presenting new spectral data, also serves as a feasibility study for this new device. It is shown that (a) the new device is capable of automatically measuring different sorts of spectra, also at elevated temperatures, (b) known thermally and optically stimulated peak emissions of quartz and feldspar are confirmed, (c) obtained IRSL and OSL spectra indicate that there is no significant relation between peak emission and stimulation temperature. - Highlights: • We have measured OSL, IRSL and TL emission spectra of sedimentary quartz and feldspar samples. • Spectral analyses were performed at elevated stimulation temperatures. • Emission spectra show very little variation with stimulation temperatures.

Optically stimulated luminescence characteristics of natural and doped quartz and alkali feldspars

Energy Technology Data Exchange (ETDEWEB)

Huett, G.; Jaek, I.; Brodski, L. [Institute of Geology at Tallinn Technical University, Tallinn (Estonia); Vasilchenko, V. [Institute of Experimental Physics and Technology of Tartu University, Tartu (Estonia)

1999-05-01

Natural alkali feldspars and quartz were doped by Tl and Cu by thermodiffusion and electrodiffusion technology. As a result of doping, intensive UV emission bands were created. The OSL stimulation spectra of irradiated natural and doped quartz and alkali feldspars were measured in the span of 400-1300 nm using UV emission of Tl at 280 nm and of Cu at 380 nm. One-trap centre conception was confirmed for high-temperature palaeodosimetrical TL peaks and OSL stimulation spectrum bands: for alkali feldspars at 880 and 420 nm and visible region of the spectrum for quartz. A thermooptical mechanism of the optical depopulation of the corresponding trap is confirmed in alkali feldspars, but there is no evidence for processes of this kind in quartz. An analogy between the physical background of OSL properties of both minerals is discussed.

Optically stimulated luminescence characteristics of natural and doped quartz and alkali feldspars

International Nuclear Information System (INIS)

Huett, G.; Jaek, I.; Brodski, L.; Vasilchenko, V.

1999-01-01

Natural alkali feldspars and quartz were doped by Tl and Cu by thermodiffusion and electrodiffusion technology. As a result of doping, intensive UV emission bands were created. The OSL stimulation spectra of irradiated natural and doped quartz and alkali feldspars were measured in the span of 400-1300 nm using UV emission of Tl at 280 nm and of Cu at 380 nm. One-trap centre conception was confirmed for high-temperature palaeodosimetrical TL peaks and OSL stimulation spectrum bands: for alkali feldspars at 880 and 420 nm and visible region of the spectrum for quartz. A thermooptical mechanism of the optical depopulation of the corresponding trap is confirmed in alkali feldspars, but there is no evidence for processes of this kind in quartz. An analogy between the physical background of OSL properties of both minerals is discussed

Radiation-induced DNA damage in halogenated pyrimidine incorporated cells and its correlation with radiosensitivity

International Nuclear Information System (INIS)

Watanabe, R.; Nikjoo, H.

2003-01-01

Cells with DNA containing 5-halogenated pyrimidines in place of thymidine show significant reductions of slope (Do) and shoulder (Dq) of their radiation survival curves. Similar radiosensitization has also been observed in the yield of DNA strand breaks. The purpose of this study is to obtain an insight into the mechanism of cell lethality by examining the relationship between the spectrum of DNA damage and the cell survival. In this study we estimated the enhancement of strand breaks due to incorporation of halogenated pyrimidine, the complexity of DNA damage and the probability of the initial DNA damage leading to cell inactivation. Monte Carlo track structure methods were used to model and simulate the induction of strand breakage by X-rays. The increase of DNA strand break was estimated by assuming the excess strand break was caused by the highly reactive uracil radicals at the halouracil substituted sites. The assumption of the enhancement mechanism of strand breaks was examined and verified by comparison with experimental data for induction of SSB and DSB. The calculated DNA damage spectrum shows the increase in complexity of strand breaks is due to incorporation of halogenated pyrimidines. The increase in the yield of DSB and cell lethality show similar trend at various degrees of halogenated pyrimidine substitution. We asked the question whether this agreement supports the hypothesis that DSB is responsible for cell lethality? The estimated number of lethal damage from the cell survival using a linear-quadratic model is much less than the initial yield of DSB. This work examines the correlation of cell lethality as a function of frequencies of complex form of double strand breaks

Thermal activation of OSL as a geothermometer for quartz grain heating during fault movements

CERN Document Server

Rink, W J; Rees-Jones, J; Schwarcz, H P

1999-01-01

In discussions of ESR dating of fault movements, there has been much debate whether zeroing of ESR signals is a mechanical shearing effect or caused by frictional heating. The OSL (optically stimulated luminescence) sensitivity of quartz is known to increase after heating. This thermal activation of dose response of the OSL in quartz should be useful as a geothermometer to test whether quartz particles in fault gouge had been heated. We tested the OSL sensitivities of quartz from fault gouge, and from a control (quartz grains from sandstone) and were able to show heat-induced enhancement of OSL sensitivity to a test dose. We observed that relative enhancement of OSL dose response (ratio of heated to unheated single aliquots) is significantly less for the finest grains (45-75 and 100-150 mu m) compared with coarser grains (150-250 mu m). These data are consistent with a model of zeroing of the quartz grains during faulting, by frictional heating localized to the grain boundaries, which would be expected to aff...

The response of quartz crystals coated with thin fatty acid film to organic gases

CERN Document Server

Jin, C N; Kim, K H; Kwon, Y S

1999-01-01

We tried to apply a quartz crystal as a sensor by using the resonant frequency and the resistance properties of quartz crystals. Four kinds of fatty acids that have the same head groups were coated on the surfaces of the quartz crystals, and the shift of the resonant frequency and the resistance were observed based on the lengths of the tail groups. Myristic acid (C sub 1 sub 4), palmitic acid (C sub 1 sub 6), stearic acid (C sub 1 sub 8), and arachidic acid (C sub 2 sub 0) were deposited on the surfaces of quartz crystals by using the Langmuir-Blodgett (LB) method. As a result, the resonant frequency change was more sensitive to high molecular-weight fatty acids than to low molecular-weight ones. We also observed the effect of temperature on stearic acid LB films, and the response properties of quartz crystals coated with stearic-acid LB films to organic gases were investigated. As a result, the sensitivity of quartz crystals to organic gases was higher for higher molecular-weight gas, and we found that quar...

Investigations on low temperature thermoluminescence centres in quartz

International Nuclear Information System (INIS)

Bernhardt, H.

1984-01-01

The present paper will help to understand the often investigated process of thermoluminescence of quartz which is of high complexity. A lot of traps exist in quartz crystals which compete with each other with respect to the trapping of charge carriers during the X-ray treatment. That is why a variety of processes takes place after X-irradiation at liquid nitrogen temperature (LNT) of quartz which complicate the phenomenology of low temperature thermoluminescence. This competition in the trapping process leads to the so-called 'sensibilization' or 'desensibilization' effects of thermoluminescence, respectively, which are described in this paper for the first time. This effect means the dependence of the LNT thermoluminescence intensity on a pre-irradiation dose applied at room temperature (RT). The influence of this pre-irradiation is understood assuming the saturation of competitive traps. This favours an enhanced trapping of charge carriers at LNT-(shallow) traps instead of the preferential trapping on the deep traps in the case of X-ray treatment of the as-grown crystal at LNT. To get the afore mentioned model we take into account not only thermoluminescence but also coloration, ir- and vuv-absorption measurements. (author)

Reconstruction of thermally quenched glow curves in quartz

International Nuclear Information System (INIS)

Subedi, Bhagawan; Polymeris, George S.; Tsirliganis, Nestor C.; Pagonis, Vasilis; Kitis, George

2012-01-01

The experimentally measured thermoluminescence (TL) glow curves of quartz samples are influenced by the presence of the thermal quenching effect, which involves a variation of the luminescence efficiency as a function of temperature. The real shape of the thermally unquenched TL glow curves is completely unknown. In the present work an attempt is made to reconstruct these unquenched glow curves from the quenched experimental data, and for two different types of quartz samples. The reconstruction is based on the values of the thermal quenching parameter W (activation energy) and C (a dimensionless constant), which are known from recent experimental work on these two samples. A computerized glow-curve deconvolution (CGCD) analysis was performed twice for both the reconstructed and the experimental TL glow curves. Special attention was paid to check for consistency between the results of these two independent CGCD analyses. The investigation showed that the reconstruction attempt was successful, and it is concluded that the analysis of reconstructed TL glow curves can provide improved values of the kinetic parameters E, s for the glow peaks of quartz. This also leads to a better evaluation of the half-lives of electron trapping levels used for dosimetry and luminescence dating.

Oxygen isotope exchange with quartz during pyrolysis of silver sulfate and silver nitrate.

Science.gov (United States)

Schauer, Andrew J; Kunasek, Shelley A; Sofen, Eric D; Erbland, Joseph; Savarino, Joel; Johnson, Ben W; Amos, Helen M; Shaheen, Robina; Abaunza, Mariana; Jackson, Terri L; Thiemens, Mark H; Alexander, Becky

2012-09-30

Triple oxygen isotopes of sulfate and nitrate are useful metrics for the chemistry of their formation. Existing measurement methods, however, do not account for oxygen atom exchange with quartz during the thermal decomposition of sulfate. We present evidence for oxygen atom exchange, a simple modification to prevent exchange, and a correction for previous measurements. Silver sulfates and silver nitrates with excess (17)O were thermally decomposed in quartz and gold (for sulfate) and quartz and silver (for nitrate) sample containers to O(2) and byproducts in a modified Temperature Conversion/Elemental Analyzer (TC/EA). Helium carries O(2) through purification for isotope-ratio analysis of the three isotopes of oxygen in a Finnigan MAT253 isotope ratio mass spectrometer. The Δ(17)O results show clear oxygen atom exchange from non-zero (17)O-excess reference materials to zero (17)O-excess quartz cup sample containers. Quartz sample containers lower the Δ(17)O values of designer sulfate reference materials and USGS35 nitrate by 15% relative to gold or silver sample containers for quantities of 2-10 µmol O(2). Previous Δ(17)O measurements of sulfate that rely on pyrolysis in a quartz cup have been affected by oxygen exchange. These previous results can be corrected using a simple linear equation (Δ(17)O(gold) = Δ(17)O(quartz) * 1.14 + 0.06). Future pyrolysis of silver sulfate should be conducted in gold capsules or corrected to data obtained from gold capsules to avoid obtaining oxygen isotope exchange-affected data. Copyright © 2012 John Wiley & Sons, Ltd.

Cathodoluminescence (CL Characteristics of Quartz from Different Metamorphic Rocks within the Kaoko Belt (Namibia

Directory of Open Access Journals (Sweden)

Jonathan Sittner

2018-05-01

Full Text Available Quartz of metamorphic rocks from the Kaoko belt (Namibia representing metamorphic zones from greenshist to granulite facies were investigated by cathodoluminescence (CL microscopy and spectroscopy to characterize their CL properties. The samples cover P-T conditions from the garnet zone (500 ± 30 °C, 9 ± 1 kbar up to the garnet-cordierite-sillimanite-K-feldspar zone (750 ± 30 °C, 4.0–5.5 kbar. Quartz from 10 different localities and metamorphic environments exclusively exhibits blue CL. The observed CL colors and spectra seem to be more or less independent of the metamorphic grade of the host rocks, but are determined by the regional geological conditions. Quartz from different localities of the garnet-cordierite-sillimanite-K-feldspar zone shows a dominant 450 nm emission band similar to quartz from igneous rocks, which might be related to recrystallization processes. In contrast, quartz from different metamorphic zones in the western part of the central Kaoko zone (garnet, staurolite, kyanite, and kyanite-sillimanite-muscovite zone is characterized by a heterogeneous blue-green CL and a dominant 500 nm emission band that strongly decreases in intensity under electron irradiation. Such CL characteristics are typical for quartz of pegmatitic and/or hydrothermal origin and indicate the participation of fluids during neoformation of quartz during metamorphism.

Establishment of gold-quartz standard GQS-1

Science.gov (United States)

Millard, Hugh T.; Marinenko, John; McLane, John E.

1969-01-01

A homogeneous gold-quartz standard, GQS-1, was prepared from a heterogeneous gold-bearing quartz by chemical treatment. The concentration of gold in GQS-1 was determined by both instrumental neutron activation analysis and radioisotope dilution analysis to be 2.61?0.10 parts per million. Analysis of 10 samples of the standard by both instrumental neutron activation analysis and radioisotope dilution analysis failed to reveal heterogeneity within the standard. The precision of the analytical methods, expressed as standard error, was approximately 0.1 part per million. The analytical data were also used to estimate the average size of gold particles. The chemical treatment apparently reduced the average diameter of the gold particles by at least an order of magnitude and increased the concentration of gold grains by a factor of at least 4,000.

Cooperativity of halogen, chalcogen, and pnictogen bonds in infinite molecular chains by electronic structure theory.

Science.gov (United States)

George, Janine; Deringer, Volker L; Dronskowski, Richard

2014-05-01

Halogen bonds (XBs) are intriguing noncovalent interactions that are frequently being exploited for crystal engineering. Recently, similar bonding mechanisms have been proposed for adjacent main-group elements, and noncovalent "chalcogen bonds" and "pnictogen bonds" have been identified in crystal structures. A fundamental question, largely unresolved thus far, is how XBs and related contacts interact with each other in crystals; similar to hydrogen bonding, one might expect "cooperativity" (bonds amplifying each other), but evidence has been sparse. Here, we explore the crucial step from gas-phase oligomers to truly infinite chains by means of quantum chemical computations. A periodic density functional theory (DFT) framework allows us to address polymeric chains of molecules avoiding the dreaded "cluster effects" as well as the arbitrariness of defining a "large enough" cluster. We focus on three types of molecular chains that we cut from crystal structures; furthermore, we explore reasonable substitutional variants in silico. We find evidence of cooperativity in chains of halogen cyanides and also in similar chalcogen- and pnictogen-bonded systems; the bonds, in the most extreme cases, are amplified through cooperative effects by 79% (I···N), 90% (Te···N), and 103% (Sb···N). Two experimentally known organic crystals, albeit with similar atomic connectivity and XB characteristics, show signs of cooperativity in one case but not in another. Finally, no cooperativity is observed in alternating halogen/acetone and halogen/1,4-dioxane chains; in fact, these XBs weaken each other by up to 26% compared to the respective gas-phase dimers.

The interpretation of quartz optically stimulated luminescence equivalent dose versus time plots

International Nuclear Information System (INIS)

Bailey, R.M.

2000-01-01

Numerical modelling has shown that the form of the quartz OSL shine plateau (hereafter 'D e (t)-plot') is influenced by the effects of phototransferred TL in the ∼110 deg. C region. It is suggested also that the presence of multiple OSL components (as described by Partial bleaching and the decay form characteristics of quartz OSL. Radiat. Meas., 27, 123-136. The form of the optically stimulated luminescence signal of quartz: implications of dating. Unpublished PhD thesis, University of London) affects the form of the D e (t)-plot. Laboratory measurements of a fully reset and artificially dosed sample yielded non-flat D e (t)-plots, the deviation being greater for the larger of the two simulated palaeodoses, in accordance with theoretical predictions. It is suggested that the so-called 'shine plateau' test is of limited use in assessing the bleaching history of quartz sediments

Carbothermal Reduction of Quartz and Carbon Pellets at Elevated Temperatures

Science.gov (United States)

Li, Fei; Tangstad, Merete; Ringdalen, Eli

2018-02-01

In this study, the carbothermal reduction of pellets composed of quartz and carbon at temperatures between 1898 K and 1948 K (1625 °C and 1675 °C) are investigated. The main product from this reaction is silicon carbide (SiC). The reduction of quartz with carbon black, charcoal, coke, coal, and pre-heated coal in the pellet were compared to investigate the different carbon resources used in silicon production. Charcoal and coke have high SiO reactivity, while carbon black and coal (pre-heated coal) have low SiO reactivity. Charcoal and carbon black show better matching between quartz/carbon reactivity and SiO reactivity, and will lose less SiO gas than coke and pre-heated coal. Coal has a high volatile content and is thus not recommended as a raw material for the pellets.

Carbothermal Reduction of Quartz and Carbon Pellets at Elevated Temperatures

Science.gov (United States)

Li, Fei; Tangstad, Merete; Ringdalen, Eli

2018-06-01

In this study, the carbothermal reduction of pellets composed of quartz and carbon at temperatures between 1898 K and 1948 K (1625 °C and 1675 °C) are investigated. The main product from this reaction is silicon carbide (SiC). The reduction of quartz with carbon black, charcoal, coke, coal, and pre-heated coal in the pellet were compared to investigate the different carbon resources used in silicon production. Charcoal and coke have high SiO reactivity, while carbon black and coal (pre-heated coal) have low SiO reactivity. Charcoal and carbon black show better matching between quartz/carbon reactivity and SiO reactivity, and will lose less SiO gas than coke and pre-heated coal. Coal has a high volatile content and is thus not recommended as a raw material for the pellets.

Natural alpha recoil particle radiation and ionizing radiation sensitivities in quartz detected with EPR: implications for geochronometry

International Nuclear Information System (INIS)

Rink, W.J.; Odom, A.L.

1991-01-01

The electron paramagnetic resonance EPR signals in granitic quartz samples of known age are studied. Time-integrated alpha recoil activity and EPR signal intensity are more significantly correlated than sample age and EPR signal intensity. Neutron activation analysis for internal uranium and thorium in quartz are reported. Natural germanium EPR signals are observed in pegmatitic quartz samples and one granitic quartz. Pegmatitic quartz exhibits germanium EPR center growth competing strongly with E' center growth, apparently leading to depleted natural concentrations of E' centers. Calculations of lattice vacancy accumulation associated with alpha recoil damage are presented and compared with concentrations of paramagnetic oxygen vacancies in the quartz. Based on the results reported, the potential and problems associated with dating quartz are discussed, relating both to accumulated lattice damage and the additive dose methods. (author)

High-energy-density hydrogen-halogen fuel cells for advanced military applications

International Nuclear Information System (INIS)

Balko, E.N.; McElroy, J.F.

1981-01-01

It is pointed out that hydrogen-halogen fuel cell systems are particularly suited for an employment as ground power sources for military applications. The large cell potential and reversible characteristics of the H 2 Cl 2 and H 2 Br 2 couples permit high energy storage density and efficient energy conversion. When used as flow batteries, the fluid nature of the reactants in the hydrogen-halogen systems has several advantages over power sources which involve solid phases. Very deep discharge is possible without degradation of subsequent performance, and energy storage capacity is limited only by the external reactant storage volume. Very rapid chemical recharging is possible through replenishment of the reactant supply. A number of H 2 Cl 2 and H 2 Br 2 fuel cell systems have been studied. These systems use the same solid polymer electrolyte (SPE) cell technology originally developed for H2/O2 fuel cells. The results of the investigation are illustrated with the aid of a number of graphs

Emission properties of thermoluminescence from natural quartz - blue and red TL response to absorbed dose

International Nuclear Information System (INIS)

Hashimoto, T.; Yokosaka, K.; Habuki, H.

1987-01-01

The TL spectrometry of natural quartz exposed to a gamma radiation dose of 8.8 kGy proved that the red TL, mainly from volcanically originated quartz, has a broad emission band with a peak around 620 nm, while the blue TL from plutonically originated quartz also has a broad emission band giving a peak around 470 nm. These typical red or blue intrinsic colours were also confirmed on the thermoluminescence colour images (TLCI). Exceptionally, a pegmatite quartz changed its TLCI colour from red to blue when the absorbed dose was increased. By using colour filter assemblies, all these quartz samples were shown to emit mainly blue and red TLs, which have distinctly different TL responses to the absorbed dose; the blue invariably showed a supralinearity relation between 1 and 10 kGy dose. For the purpose of dating, the use of red TL, is preferable. The red TL component is related to the impurity Eu content in quartz minerals. (author)

Changes in the artificial thermoluminescence glow curves of quartz associated with uranium deposits

Energy Technology Data Exchange (ETDEWEB)

Hochman, M.B.M.; Ypma, P.J.M.

1988-01-01

Previous laboratory-based studies have shown that quartz thermoluminescence (TL) glow curves change in intensity and shape in response to large radiation doses. Initially, low temperature peaks are sensitized though at gamma doses of greater than 10/sup 5/ - 10/sup 6/ kGy desensitization occurs. This study has examined the change in artificial TL in quartz at various distances from a uranium deposit. Such quartz has been subjected to varying palaeoradiation doses in a natural uranium rich environment. Quartz from an uranium rich environment shows that the 130/sup 0/C glow peak is the dominant glow peak in background radiation environments, though this peak decreases with increasing palaeoradiation dose. At doses greater than 10/sup 5/-10/sup 6/ kGy the 350/sup 0/C glow peak is the dominant glow peak in these quartz samples. An increase in E'/sub 1/ centre concentration also occurs from the least radiation affected sample to the most radiation affected sample. These results suggest that artificial TL is useful in uranium exploration.

Organic halogen compounds and surface water pollution; Composti organoalogenati alifatici e contaminazione delle acque superficiali

Energy Technology Data Exchange (ETDEWEB)

Cocchioni, M.; Pellegrini, M. G.; Grappasonni, I.; Nacciarriti, L.; Bernacchia, G. [Camerino, Univ. (Italy). Dipt. di Scienze Igienistiche e Sanitarie-Ambientali

1997-03-01

A brief review of the effects of halogenated organic compounds on the fluvial ecosystem is followed by results from a detailed monitoring of these substances in all the Marches Region rivers. The results show generally modest concentrations, except for sporadic peaks for chloroform. Sites revealing significant concentrations of halogenated organic compounds also manifested a worsening of the biological quality of the waters with lessening of E.B.I. Attention is drawn to the negative effects of indiscriminate chlorination of purification plant outputs, as this practice often fails to resolve infective problems and in itself adds toxicity to the watercourse.

Thermal activation of OSL as a geothermometer for quartz grain heating during fault movements

International Nuclear Information System (INIS)

Rink, W.J.; Toyoda, S.; Rees-Jones, J.; Schwarcz, H.P.

1999-01-01

In discussions of ESR dating of fault movements, there has been much debate whether zeroing of ESR signals is a mechanical shearing effect or caused by frictional heating. The OSL (optically stimulated luminescence) sensitivity of quartz is known to increase after heating. This thermal activation of dose response of the OSL in quartz should be useful as a geothermometer to test whether quartz particles in fault gouge had been heated. We tested the OSL sensitivities of quartz from fault gouge, and from a control (quartz grains from sandstone) and were able to show heat-induced enhancement of OSL sensitivity to a test dose. We observed that relative enhancement of OSL dose response (ratio of heated to unheated single aliquots) is significantly less for the finest grains (45-75 and 100-150 μm) compared with coarser grains (150-250 μm). These data are consistent with a model of zeroing of the quartz grains during faulting, by frictional heating localized to the grain boundaries, which would be expected to affect smaller grains more than large ones. This argues against a zeroing model in which the entire fault gouge is heated by friction. Higher laboratory preheating of sandstone quartz reduces between-aliquot variability of OSL dose response in the unheated grains to nearly zero. Unheated coarsest fault gouge grains displayed virtually no among-aliquot variability, whereas fine grains showed much larger between-aliquot variability; as with the quartz sand, variability dropped to near zero after laboratory heating, suggesting that fine grains in fault gouge have experienced a wide range of natural thermal histories during faulting. This may present a problem for ESR dating of fault gouge using the plateau method

Creep of quartz by dislocation and grain boundary processes

Science.gov (United States)

Fukuda, J. I.; Holyoke, C. W., III; Kronenberg, A. K.

2015-12-01

Wet polycrystalline quartz aggregates deformed at temperatures T of 600°-900°C and strain rates of 10-4-10-6 s-1 at a confining pressure Pc of 1.5 GPa exhibit plasticity at low T, governed by dislocation glide and limited recovery, and grain size-sensitive creep at high T, governed by diffusion and sliding at grain boundaries. Quartz aggregates were HIP-synthesized, subjecting natural milky quartz powder to T=900°C and Pc=1.5 GPa, and grain sizes (2 to 25 mm) were varied by annealing at these conditions for up to 10 days. Infrared absorption spectra exhibit a broad OH band at 3400 cm-1 due to molecular water inclusions with a calculated OH content (~4000 ppm, H/106Si) that is unchanged by deformation. Rate-stepping experiments reveal different stress-strain rate functions at different temperatures and grain sizes, which correspond to differing stress-temperature sensitivities. At 600-700°C and grain sizes of 5-10 mm, flow law parameters compare favorably with those for basal plasticity and dislocation creep of wet quartzites (effective stress exponents n of 3 to 6 and activation enthalpy H* ~150 kJ/mol). Deformed samples show undulatory extinction, limited recrystallization, and c-axis maxima parallel to the shortening direction. Similarly fine-grained samples deformed at 800°-900°C exhibit flow parameters n=1.3-2.0 and H*=135-200 kJ/mol corresponding to grain size-sensitive Newtonian creep. Deformed samples show some undulatory extinction and grain sizes change by recrystallization; however, grain boundary deformation processes are indicated by the low value of n. Our experimental results for grain size-sensitive creep can be compared with models of grain boundary diffusion and grain boundary sliding using measured rates of silicon grain boundary diffusion. While many quartz mylonites show microstructural and textural evidence for dislocation creep, results for grain size-sensitive creep may apply to very fine-grained (<10 mm) quartz mylonites.

Studies of the spectral and spatial characteristics of shock-induced luminescence from x-cut quartz

International Nuclear Information System (INIS)

Brannon, P.J.; Konrad, C.; Morris, R.W.; Jones, E.D.; Asay, J.R.

1983-01-01

Spatial and spectral studies of shock-induced luminescence from x-cut crystalline quartz as a function of stress level revealed the following information: Crystalline x-cut quartz has a threshold for emission near the dynamic yield point (about 6 GPa); the spatial distribution of the luminescence from x-cut quartz changes from an intersecting linear emission pattern to a uniform emission pattern as the stress level increases from 6 to 8 GPa; spectra from x-cut quartz are band-like rather than blackbody; crystalline x-cut quartz has emission peaks near 400 and 600 nm; a change in the 400-nm emission with time can be correlated to wave interaction times. A discussion of the luminous emission in terms of yielding and other physical mechanisms is given

Impact of bromide on halogen incorporation into organic moieties in chlorinated drinking water treatment and distribution systems.

Science.gov (United States)

Tan, J; Allard, S; Gruchlik, Y; McDonald, S; Joll, C A; Heitz, A

2016-01-15

The impact of elevated bromide concentrations (399 to 750 μg/L) on the formation of halogenated disinfection by-products (DBPs), namely trihalomethanes, haloacetic acids, haloacetonitriles, and adsorbable organic halogen (AOX), in two drinking water systems was investigated. Bromine was the main halogen incorporated into all of the DBP classes and into organic carbon, even though chlorine was present in large excess to maintain a disinfectant residual. Due to the higher reactivity of bromine compared to chlorine, brominated DBPs were rapidly formed, followed by a slower increase in chlorinated DBPs. Higher bromine substitution and incorporation factors for individual DBP classes were observed for the chlorinated water from the groundwater source (lower concentration of dissolved organic carbon (DOC)), which contained a higher concentration of bromide, than for the surface water source (higher DOC). The molar distribution of adsorbable organic bromine to chlorine (AOBr/AOCl) for AOX in the groundwater distribution system was 1.5:1 and almost 1:1 for the surface water system. The measured (regulated) DBPs only accounted for 16 to 33% of the total organic halogen, demonstrating that AOX measurements are essential to provide a full understanding of the formation of halogenated DBPs in drinking waters. In addition, the study demonstrated that a significant proportion (up to 94%) of the bromide in source waters can be converted AOBr. An evaluation of AOBr and AOCl through a second groundwater treatment plant that uses conventional treatment processes for DOC removal produced 70% of AOX as AOBr, with 69% of the initial source water bromide converted to AOBr. Exposure to organobromine compounds is suspected to result in greater adverse health consequences than their chlorinated analogues. Therefore, this study highlights the need for improved methods to selectively reduce the bromide content in source waters. Copyright © 2015 Elsevier B.V. All rights reserved.

High energy halogen atom reactions activated by nuclear transformations. Progress report, February 15, 1979-February 14, 1980

Energy Technology Data Exchange (ETDEWEB)

Rack, E.P.

1980-02-01

The program consists of six interrelated areas: (1) Reactions of iodine with alkenes and alkynes activated by radiative neutron capture and isomeric transition in low pressure gaseous systems employing additives and rare gas moderators, high pressure, and liquid systems. Special attention was given to the reactivity of excited complex formation and structural effects of electrophilic iodine attack on various pi-bond systems. (2) The gas-to-condensed phase transition in halogen high energy chemistry. Current interest involves the study of caging effects of an ice lattice on recombination reactions involving neutron-irradiated frozen aqueous solutions of halogenated organic and biochemical solutes in order to learn more about kinetic energy effects, halogen size, solute molecule size, steric effects and hydrogen bonding within an ice lattice cage. (3) Systematics of halogen hot atom reactions. The reactions of /sup 80m/Br, /sup 80/Br, /sup 82m/Br + /sup 82/Br, /sup 82/Br, /sup 82/Br, /sup 128/I, /sup 130/I, and /sup 130m/I + /sup 130/I activated by radiative neutron capture or isomeric transition in hydrocarbons and halo-substituted alkanes in low pressure and high pressure gaseous systems employing additives and rare gas moderators are currently being studied. (4) Mathematical and computer simulation studies of caging events within an ice lattice are being investigated. (5) At Brookhaven National Laboratory, cyclotron-produced chlorine and fluorine hot atoms substitution reactions with molecules possessing a single chiral center are under investigation to determine the role of hot atom kinetic energy, halogen atom, enantioner structure, steric effects and phase on the extent of substitution by retention of configuration or by Walden inversion. (6) The applications of high energy techniques and concepts to neutron activation analysis for trace element determinations in biological systems was continued.

Effects of halogenated aromatics/aliphatics and nitrogen(N)-heterocyclic aromatics on estimating the persistence of future pharmaceutical compounds using a modified QSAR model.

Science.gov (United States)

Lim, Seung Joo; Fox, Peter

2014-02-01

The effects of halogenated aromatics/aliphatics and nitrogen(N)-heterocyclic aromatics on estimating the persistence of future pharmaceutical compounds were investigated using a modified half life equation. The potential future pharmaceutical compounds investigated were approximately 2000 pharmaceutical drugs currently undergoing the United States Food and Drug Administration (US FDA) testing. EPI Suite (BIOWIN) model estimates the fates of compounds based on the biodegradability under aerobic conditions. While BIOWIN considered the biodegradability of a compound only, the half life equation used in this study was modified by biodegradability, sorption and cometabolic oxidation. It was possible that the potential future pharmaceutical compounds were more accurately estimated using the modified half life equation. The modified half life equation considered sorption and cometabolic oxidation of halogenated aromatic/aliphatics and nitrogen(N)-heterocyclic aromatics in the sub-surface, while EPI Suite (BIOWIN) did not. Halogenated aliphatics in chemicals were more persistent than halogenated aromatics in the sub-surface. In addition, in the sub-surface environment, the fates of organic chemicals were much more affected by halogenation in chemicals than by nitrogen(N)-heterocyclic aromatics. © 2013.

Measurement of the dose in quartz in the presence of feldspar contamination

DEFF Research Database (Denmark)

Wallinga, J.; Murray, A.S.; Bøtter-Jensen, L.

2002-01-01

To allow the determination of the dose in quartz in the presence of feldspar contamination. the quartz-to-feldspar optically stimulated luminescence (OSL) ratio needs to be maximised. Experiments were carried Out to find the optimum procedure to bleach the feldspar by exposure to infrared light...

Structural study of some halogen oxyfluorides

International Nuclear Information System (INIS)

Tantot, Georges.

1976-12-01

Some halogen oxyfluorides are studied from a structural point of view by vibrational spectroscopy and nuclear magnetic resonance. Force constant and molecular orbital calculations are added to the experimental data. The pyramidal shape of ClO 2 F under its three physical states is confirmed. In the gas and liquid phases an intermolecular association is observed. A similar interaction takes place in ClOF 3 . ClO 3 F has only a solid state transition above 10K. The structures of ClO 2 F and KBrO 2 F 2 are partly determined. The theoretical calculations are well correlated with the experimental data. They suggest a major influence of the ligands [fr

Study of the α and β phases of quartz by neutron multiple diffraction

International Nuclear Information System (INIS)

Mazzocchi, V.L.

1984-01-01

Crystal structures of α and β phases of quartz are studied, employing neutron multiple diffraction as a method of analysis. Theoretical multiple diffraction patterns in a many-beam case were determined by a computer program which calculates intensities of beams as sums of Taylor's series expansions, retaining terms up to a order n. Experimental 'umweg' and transmitted beam patterns were obtained for the 00.1 primary reflection of α and β phases of quartz. To calculate α - quartz multiple diffraction intensities it was necessary to determine the Dauphine twinning fraction for the crystal after having passed by the β-phase. For the two models of β-quartz a better agreement between experimental and calculated integrated intensities was found for the disordered structure model based on split-half-oxigen positions. (Author) [pt

Imperfections study of the smoky quartz from Bahia by X-ray diffraction

International Nuclear Information System (INIS)

D'Aguiar Neto, M.M.F.

1974-01-01

X-ray diffraction techniques were used to study the type of point defects in Smoky quartz from Itambe and Vitoria da Conquista in Bahia. The power method, using the Seemann Bohlin camara (back refletion), was utilized in the analysis of the policrystals, while the monocrystals were studied by means of the precession camara. The positions occupied by the defects in the crystal net were calculated. The results show that while the defects of substitutional impurities predominate in the quartz from Itambe, in the quartz from Vitoria da Conquista the substitutional defects exist in comparable proportions that the interstital ones. Isochronous annealing curves, for both type of smoky quartz indicate an increase in the net parameter to temperature values above the annealing temperatures. Was formulated the hypothesis that providing a thermal energy greater than that of annealing is used, new interstitial defects would be created as a result of a thermic diffusion mechanism. (C.D.G.) [pt

Experiment study of a quartz tube falling particle receiver

Institute of Scientific and Technical Information of China (English)

Tianjian WANG; Fengwu BAI; Shunzhou CHU; Xiliang ZHANG; Zhifeng WANG

2017-01-01

This paper presents an experimental evaluation of a specially designed falling particle receiver.A quartz tube was used in the design,with which the particles would not be blown away by wind.Concentrated solar radiation was absorbed and converted into thermal energy by the solid particles flowed inside the quartz tube.Several experiments were conducted to test the dynamic thermal performance of the receiver on solar furnace system.During the experiments,the maximum particle temperature rise is 212℃,with an efficiency of 61.2％,which shows a good thermal performance with a falling distance of 0.2 m in a small scale particle receiver.The average outlet particle temperature is affected by direct normal irradiance (DNI) and other factors such as wind speed.The solid particles obtain a larger viscosity with a higher temperature while smaller solid particles are easier to get stuck in the helix quartz tube.The heat capacity of the silicon carbide gets larger with the rise of particle temperature,because as the temperature of solid particles increases,the temperature rise of the silicon carbide decreases.

Petrogenesis of low-δ18O quartz porphyry dykes, Koegel Fontein complex, South Africa

Science.gov (United States)

Harris, Chris; Mulder, Kwenidyn; Sarkar, Saheli; Whitehead, Benjamin; Roopnarain, Sherissa

2018-04-01

This paper investigates the origin of low-δ18O quartz porphyry dykes associated with the 144-133 Ma Koegel Fontein Igneous Complex, which was intruded during the initial phase of breakup of Africa and South America. The 25-km diameter Rietpoort Granite is the largest and youngest phase of activity, and is roofed by a 10-km diameter pendant of gneiss. Quartz porphyry (QP) dykes, up to 15 m in width, strike NW-SE across the complex. The QP dykes that intruded outside the granite have similar quartz phenocryst δ18O values (average 8.0‰, ± 0.7, n = 33) to the granite (average 8.3 ± 1.0, n = 7). The QP dykes that intruded the roof pendant have quartz phenocrysts with more variable δ18O values (average 1.6‰, ± 2.1, n = 55). In some cases quartz phenocrysts have δ18O values as low as - 2.5‰. The variation in δ18O value within the quartz crystal population of individual dykes is small relative to the overall range, and core and rim material from individual quartz phenocrysts in three samples are identical within error. There is no evidence that quartz phenocryst δ18O values have been affected by fluid-rock interaction. Based on a Δquartz-magma value of 0.6‰, magma δ18O values must have been as low as - 3.1‰. Samples collected along the length of the two main QP dykes that traverse the roof pendant have quartz phenocryst δ18O values that range from + 1.1 to + 4.6‰, and - 2.3 to + 5.6‰, respectively. These δ18O values correlate negatively ( r = - 0.96) with initial 87Sr/86Sr, which can be explained by the event that lowered δ18O values of the source being older than the dykes. We suggest that the QP dykes were fed by magma produced by partial melting of gneiss, which had been variably altered at high temperature by 18O-depleted meteoric water during global glaciation at 550 Ma. The early melts had variable δ18O value but as melt pockets interconnected during melting, the δ18O values approached that of average gneiss. Variable quartz phenocryst �

Thermal annealing studies in muscovite and in quartz

International Nuclear Information System (INIS)

Roberts, J.H.; Gold, R.; Ruddy, F.H.

1979-06-01

In order to use Solid State Track Recorders (SSTR) in environments at elevated temperatures, it is necessary to know the thermal annealing characteristics of various types of SSTR. For applications in the nuclear energy program, the principal interest is focused upon the annealing of fission tracks in muscovite mica and in quartz. Data showing correlations between changes in track diameters and track densities as a function of annealing time and temperature will be presented for Amersil quartz glass. Similar data showing changes in track lengths and in track densities will be presented for mica. Time-temperature regions will be defined where muscovite mica can be accurately applied with negligible correction for thermal annealing

The effects of pre-dose and annealing temperature on some dosimetric properties of thermoluminescence of quartz

International Nuclear Information System (INIS)

Lin Zhikai

1996-02-01

The following aspects of dosimetric properties of quartz sample were studied. (1) The changes in dosimetric sensitivity of quartz with different pre-doses under different annealing temperature; (2) the option of optimal annealing temperature which can make the dosimetric sensitivity of quartz to restore its original level; (3) The changes in dosimetric sensitivity of quartz with different annealing time at 500 degree C for 8 h; (4) Repeated experiments were carried out in order to prove whether the sensitivity of quartz can restore its original level at annealing temperature 700 degree C for 3 h. It has been found that at 700 degree C for 3 h gave the least sensitivity change and the sensitivity of quartz almost restored its original level. Repeated experiments with four kinds of quartz sample confirmed this conclusion. The dramatic change of TL glow curve occurred only at the condition of annealing temperature 900 degree C for 1 h. This result was different from that obtained by D. J. Huntley et al. (1988). (3 refs., 4 figs., 1 tab.)

Microbially induced separation of quartz from calcite using Saccharomyces cerevisiae.

Science.gov (United States)

Padukone, S Usha; Natarajan, K A

2011-11-01

Cells of Saccharomyces cerevisiae and their metabolites were successfully utilized to achieve selective separation of quartz and calcite through microbially induced flotation and flocculation. S. cerevisiae was adapted to calcite and quartz minerals. Adsorption studies and electrokinetic investigations were carried out to understand the changes in the surface chemistry of yeast cells and the minerals after mutual interaction. Possible mechanisms in microbially induced flotation and flocculation are outlined. Copyright © 2011 Elsevier B.V. All rights reserved.

Emission polarization study on quartz and calcite.

Science.gov (United States)

Vincent, R. K.

1972-01-01

Calculation of the spectral emission polarization of quartz and calcite polished plates for observation angles of 20 and 70 deg by the substitution of complex index of refraction values for each mineral into Fresnel's equations. The emission polarization is shown to be quite wavelength-dependent, demonstrating that selected narrow or medium-width spectral bands exhibit a significantly higher percentage of polarization than a broad spectral band for these two minerals. Field measurements with a broadband infrared radiometer yield polarizations on the order of 2% for a coarse-grained granite rock and beach sand (both quartz-rich). This implies that a more sensitive detector with a selected medium-width filter may be capable of measuring emission polarization accurately enough to make this parameter useful as a remote sensing tool for discrimination among rocks on the basis of texture.

The red thermoluminescence of quartz: 3-D spectral measurements

International Nuclear Information System (INIS)

Scholefield, R.B.; Prescott, J.R.

1999-01-01

As part of a general study of the thermoluminescence (TL) of quartz, we have examined the 3-D spectra of samples of quartz extracted from a variety of sediments. Blue emission at about 2.6 eV/475 nm, which is the photon energy region commonly used in luminescence dating, seems ubiquitous. Significant emission in the red, ∼1.9 eV/650 nm, has been found at most glow temperatures in all of our samples of Australian quartz sediments, and it is to this that particular attention is paid in the present work. A limited selection of samples from other countries has also been included. The ratio of the intensities of the red and blue emissions varies widely among samples. We have not found any evidence of a correlation between this ratio, nor the intensity of the red emission, with trace element concentration, including that of Al for which a correlation has been previously observed. In the context of luminescence dating, all samples have been examined to see whether they have a rapidly bleaching red component in a similar sense to the well-known 305 deg. C/2.95 eV/420 nm peak in quartz: some samples have such a component--some do not. A suggestive parallelism is found between the blue and red spectra, in that there are 'slowly bleaching' and 'rapidly bleaching' components at similar temperatures in the both red and the blue. However, there is no red component associated with the 110 deg. C peak used in pre-dose dating

Assessing rare earth elements in quartz rich geological samples

International Nuclear Information System (INIS)

Santoro, A.; Thoss, V.; Ribeiro Guevara, S.; Urgast, D.; Raab, A.; Mastrolitti, S.; Feldmann, J.

2016-01-01

Sodium peroxide (Na_2O_2) fusion coupled to Inductively Coupled Plasma Tandem Mass Spectrometry (ICP-MS/MS) measurements was used to rapidly screen quartz-rich geological samples for rare earth element (REE) content. The method accuracy was checked with a geological reference material and Instrumental Neutron Activation Analysis (INAA) measurements. The used mass-mode combinations presented accurate results (only exception being "1"5"7Gd in He gas mode) with recovery of the geological reference material QLO-1 between 80% and 98% (lower values for Lu, Nd and Sm) and in general comparable to INAA measurements. Low limits of detection for all elements were achieved, generally below 10 pg g"−"1, as well as measurement repeatability below 15%. Overall, the Na_2O_2/ICP-MS/MS method proved to be a suitable lab-based method to quickly and accurately screen rock samples originating from quartz-rich geological areas for rare earth element content; particularly useful if checking commercial viability. - Highlights: • Na_2O_2 fusion coupled to ICP-MS/MS was used to determine REE in quartz-rich samples. • The method accuracy was checked with a geological reference material and INAA. • Results were within 80–98% recovery of QLO-1 reference material, comparable to INAA. • Detection limits were generally below 10 pg g"−"1, and repeatability was below 15%. • Na_2O_2/ICP-MS/MS proved to be a suitable method for REE in quartz-rich samples.

Effect of pre-dose irradiation in the quartz and its use for archaelogical dating

International Nuclear Information System (INIS)

Yukimitu, K.

1985-01-01

The technique of pre-dose for dating ceramics, using the thermoluminescent properties of quartz is presented. The behavior of thermoluminescent (TL) sensitivity of the 110 0 C peak of Brazilian quartz, in its geologic state, submitted to thermal treatments from 600 to 900 0 C, is studied. The samples were tritured for separating the quartz crystals from clay. The quartz grains were submitted to leaching with chloric acid solution followed by leaching with running water. The samples were irradiated in laboratory, with gamma radiation using Co-60 and Cs-137 sources, for calibration. A sensitivity enhancement rate of 2% per rad was observed for samples annealed at 900 0 C, was observed. (M.C.K.) [pt

High power light emitting diode (LED) arrays versus halogen light polymerization of oral biomaterials: Barcol hardness, compressive strength and radiometric properties.

Science.gov (United States)

Mills, Robin W; Uhl, Alexander; Blackwell, Gordon B; Jandt, Klaus D

2002-07-01

The clinical performance of light polymerized dental composites is greatly influenced by the quality of the light curing unit (LCU) used. Commonly used halogen LCUs have some specific drawbacks such as decreasing light output with time. This may result in a low degree of monomer conversion of the composites with negative clinical implications. Previous studies have shown that blue light emitting diode (LED) LCUs have the potential to polymerize dental composites without having the drawbacks of halogen LCUs. Since these studies were carried out LED technology has advanced significantly and commercial LED LCUs are now becoming available. This study investigates the Barcol hardness as a function of depth, and the compressive strength of dental composites that had been polymerized for 40 or 20s with two high power LED LCU prototypes, a commercial LED LCU, and a commercial halogen LCU. In addition the radiometric properties of the LCUs were characterized. The two high power prototype LED LCUs and the halogen LCU showed a satisfactory and similar hardness-depth performance whereas the hardness of the materials polymerized with the commercial LED LCU rapidly decreased with sample depth and reduced polymerization time (20 s). There were statistically significant differences in the overall compressive strengths of composites polymerized with different LCUs at the 95% significance level (p = 0.0016) with the two high power LED LCU prototypes and the halogen LCU forming a statistically homogenous group. In conclusion, LED LCU polymerization technology can reach the performance level of halogen LCUs. One of the first commercial LED LCUs however lacked the power reserves of the high power LED LCU prototypes.

Quadrupole coupling constants and isomeric Moessbauer shifts for halogen-containing gold, platinum, niobium, tantalum and antimony compounds

International Nuclear Information System (INIS)

Poleshchuk, O. K.; Branchadell, V.; Ritter, R. A.; Fateev, A. V.

2008-01-01

We have analyzed by means of Density functional theory calculations the nuclear quadrupole coupling constants of a range of gold, antimony, platinum, niobium and tantalum compounds. The geometrical parameters and halogen nuclear quadrupole coupling constants obtained by these calculations substantially corresponded to the data of microwave and nuclear quadrupole resonance spectroscopy. An analysis of the quality of the calculations that employ pseudo-potentials and all-electron basis sets for the halogen compounds was carried out. The zero order regular approximation (ZORA) method is shown to be a viable alternative for the calculation of halogen coupling constants in molecules. In addition, the ZORA model, in contrast to the pseudo-potential model, leads to realistic values of all metal nuclear quadrupole coupling constants. From Klopman's approach, it follows that the relationship between the electrostatic bonding and covalent depends on the nature of the central atom. The results on Moessbauer chemical shifts are also in a good agreement with the coordination number of the central atom.

Quadrupole coupling constants and isomeric Moessbauer shifts for halogen-containing gold, platinum, niobium, tantalum and antimony compounds

Energy Technology Data Exchange (ETDEWEB)

Poleshchuk, O. K., E-mail: poleshch@tspu.edu.ru [Tomsk State Pedagogical University (Russian Federation); Branchadell, V. [Universitat Autonoma de Barcelona, Departament de Quimica (Spain); Ritter, R. A.; Fateev, A. V. [Tomsk State Pedagogical University (Russian Federation)

2008-01-15

We have analyzed by means of Density functional theory calculations the nuclear quadrupole coupling constants of a range of gold, antimony, platinum, niobium and tantalum compounds. The geometrical parameters and halogen nuclear quadrupole coupling constants obtained by these calculations substantially corresponded to the data of microwave and nuclear quadrupole resonance spectroscopy. An analysis of the quality of the calculations that employ pseudo-potentials and all-electron basis sets for the halogen compounds was carried out. The zero order regular approximation (ZORA) method is shown to be a viable alternative for the calculation of halogen coupling constants in molecules. In addition, the ZORA model, in contrast to the pseudo-potential model, leads to realistic values of all metal nuclear quadrupole coupling constants. From Klopman's approach, it follows that the relationship between the electrostatic bonding and covalent depends on the nature of the central atom. The results on Moessbauer chemical shifts are also in a good agreement with the coordination number of the central atom.

Data Acquisition System for Quartz Crystal Microbalances

Directory of Open Access Journals (Sweden)

Kleber Romero Felizardo

2006-02-01

Full Text Available This work presents a data acquisition system used in a mass sensor: quartz crystal microbalance. This system reads the frequency of this sensor along the time and sends the collected data to the computer through a serial interface.

Slaw extracted proton beam formation and monitoring for the ''QUARTZ'' setup

International Nuclear Information System (INIS)

Bushnin, Yu.B.; Gres', V.N.; Davydenko, Yu.P.

1982-01-01

The version of optical mode of the beam channel providing with simultaneous operating the experimental setups FODS and ''QUARTZ'' at consecutive usage of the slow extracted proton beam is reported. The ''QUARTZ'' setup beam diagnostics system comprises two subsystems: for measuring beam profile beam timing structure and beam intensity and operates in the beam extraction duration from 20 ns to few seconds at beam intensity from 10 10 to 5x10 12 protons/pulse. The ''QUARTZ'' setup represents a focusing crystal-diffraction spectrometer with 5-meter focal distance and Ge(Li) special construction detector. High efficiency target is applied in the setup. The ''QUARTZ'' setup is designed for studying exotic atoms produced by negative charged heavy particles (π, K, μ, P tilde) and atomic nuclei. Precise energy measurement of X ray transitions in such atoms is performed. For measuring beam geometric parameters 32-channel secondary emission chambers are used. As detector of beam intensity and timing structure of slow extracted beam the secondary emission chamber is employed. The principle circuit of current integrator is given. As data transmission line a 50-pair telephone cable is used. Information conversion into digital form and its subsequent processing is performed in the CAMAC system and the SM-3 computer. The proton beam full intensity measuring system provides with accuracy not worse than +-4.5% in the 10 10 -10 12 proton/sec range. The implemented optical mode of the beam channel and proton beam monitoring system permitted to begin fulfillment of the experimental program on the ''QUARTZ'' setup

Allergic contact dermatitis due to highly reactive halogenated compounds

Energy Technology Data Exchange (ETDEWEB)

Pickering, F C; Ive, F A

1983-11-01

Ten cases of dermatitis in a fine organic chemicals plant are reported. These cases were all due to exposure to chemical compounds with reactive bromine or chlorine atoms. This type of chemical is always extremely irritant, but evidence is put forward to suggest that these cases were the result of allergic sensitization. Chemicals with reactive halogen atoms should always be handled with extreme care and patch testing should be approached with caution.

Ferrobielastic twinning in irradiated quartz

International Nuclear Information System (INIS)

Shiau, S.M.

1986-01-01

Cultured quartz is usually free from electrical twinning; however, it may occur if the seed crystal is twinned or if undue applied forces are exerted on the crystal. Ferrobielastic twinning was studied optically (photoelastic effect) and electrically (piezoelectric effect). At room temperature, twins were perceptible at stresses of about 2.l5 x 10 8 N/m 2 , and crystals switched from their original states to the alternative twin states at stresses about 5.0 x 10 8 N/m 2 (called coercive stress). The decrease in coercive stress with increasing temperature was observed, and these coercive stresses become very low as temperatures reach to 300 0 C. The effects of irradiation on the twinning in quartz were also studied. The presence of defects produced by irradiation was utilized to pin the domain wall motion. Both neutrons and gamma rays were employed. The stress required to nucleate an appreciable volume of twins is about twice as high for irradiated crystals than for those unirradiated. This result demonstrated that the irradiated crystals can tolerate higher stresses. However, the coercive stress for complete switch-over was not much different for irradiated and unirradiated crystals. It appears that the defects caused by irradiation eliminate the initial twinning events but do not affect switch-over

Significance of Dauphiné twins in crystallographic fabrics of quartz tectonites

Science.gov (United States)

Eske Sørensen, Bjørn

2014-05-01

Dauphine twins are commonly found in quartz tectonites, however their role in deformation processes are not completely understood. This study represents a new attempt to understand the interaction between slip systems and Dauphine twins in deforming quartz-rich rocks at different temperatures. There is no doubt that Dauphine twins are mobilized under stress as this has been shown by experiments for single crystals and in polycrystalline aggregates where distinct crystallographic fabrics develop in previously randomly oriented aggregates related to minimization of elastic energy (Tullis 1972). However in quartz tectonites the Dauphine twin process is a part of interplay between plastic deformation and recovery processes which depends on PT, strain-rate and fluid composition and availability. In quartz tectonites with Y-girdle C-axis (GBM-regime) fabrics Dauphiné twins are abundant, relating different parts of r- and z rhomb "comet" distributions. This is interpreted as completion between prism slip and Dauphiné twinning. Slip rotates grains such that CRSS is low on the prism planes, but then Dauphiné twin boundaries sweeps through the grain back to the orientation giving lower stored elastic energy. The faster recovery at higher temperatures gives subgrain walls slowing down twin movement across the mm-sized grain of the GBM regime. At lower temperatures in the SGR-regime grain-size is reduced and different rotations of the grains are happening due to the domination of rhomb and basal slip. Because recrystallization is effective relative to grain-size the grains are commonly free of internal strain and subgrain walls, allowing the favorably oriented Dauphiné twin member to sweep across the whole grain overwhelming the unfavorably oriented Dauphiné twin member. As a consequence high strain reduces the number of Dauphiné twins and quartz rhomb fabrics appear trigonal, missing the "comet" shape of the GBM regime rhomb fabrics. Since Dauphiné twinning is also

Mathematical modeling of quartz particle melting process in plasma-chemical reactor

Energy Technology Data Exchange (ETDEWEB)

Volokitin, Oleg, E-mail: volokitin-oleg@mail.ru; Volokitin, Gennady, E-mail: vgg-tomsk@mail.ru; Skripnikova, Nelli, E-mail: nks2003@mai.ru; Shekhovtsov, Valentin, E-mail: shehovcov2010@yandex.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); Vlasov, Viktor, E-mail: rector@tsuab.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); National Research Tomsk Polytechnic University, 30, Lenin Ave., 634050, Tomsk (Russian Federation)

2016-01-15

Among silica-based materials vitreous silica has a special place. The paper presents the melting process of a quartz particle under conditions of low-temperature plasma. A mathematical model is designed for stages of melting in the experimental plasma-chemical reactor. As calculation data show, quartz particles having the radius of 0.21≤ r{sub p} ≤0.64 mm completely melt at W = 0.65 l/s particle feed rate depending on the Nusselt number, while 0.14≤ r{sub p} ≤0.44 mm particles melt at W = 1.4 l/s. Calculation data showed that 2 mm and 0.4 mm quartz particles completely melted during and 0.1 s respectively. Thus, phase transformations occurred in silicon dioxide play the important part in its heating up to the melting temperature.

Measurements of the Shock Release Of Quartz and Paralyene-N

Science.gov (United States)

Hawreliak, James; Karasik, Max; Oh, Jaechul; Aglitskiy, Yefim

2017-06-01

The shock and release properties of Quartz and hydrocarbons are important to high energy density (HED) research and inertial confinement fusion (ICF) science. The bulk of HED material research studies single shock or multiple shock conditions. The challenge with measuring release properties is unlike shocks which have a single interface from which to measure the properties, the release establishes gradients in the sample. The streaked x-ray imaging capability of the NIKE laser allow the interface between quartz and CH to be measured during the release, giving measurements of the interface velocity and CH density. Here, we present experimental results from the NIKE laser where quartz and parylene-N are shock compressed to high pressure and temperature and the release state is measured through x-ray imaging. The shock state is characterized by shock front velocity measurements using VISAR and the release state is characterized by using side-on streaked x-ray radiography Work supported by DOE/NNSA.

Usability of VTL from natural quartz grains for retrospective dosimetry

International Nuclear Information System (INIS)

Fujita, H.; Hashimoto, T.

2007-01-01

To develop retrospective dosimetry of unexpected radiation accident, basic studies on violet thermoluminescence (VTL) phenomena were conducted using natural quartz grains. All VTL glow curves of as-received samples did not exhibit peaks <250 deg. C, although for artificially irradiated quartz samples there were VTL peaks in the temperature region <250 deg. C. Therefore, accident doses could be estimated without the interference of naturally accumulated doses by VTL measurements from natural quartz. The mean lives of VTL were evaluated by the various heating rates method and the range of values was found to be between some days and ten thousands of years depending on each peak. Especially, the mean life of VTL peak at 200 deg. C was years order. Furthermore, the lower detection limit was calculated to be tens of mGy from the response curve. This value was lower than that of other methods such as ESR dosimetry. From these results, we conclude that VTL dosimetry can be preferred for accidental evaluation. (authors)

Luminescence quartz dating of lime mortars. A first research approach

International Nuclear Information System (INIS)

Zacharias, N.; Mauz, B.; Michael, C.T.

2002-01-01

Lime mortars mixed with sand are well suited for connecting structural materials, like stones and bricks, due to the mechanical properties this material exhibits. Their extensive use in architectural and decorative works during the last 4000 years motivated the introduction of the 'Luminescence clock' for age determination of mortars. The same principles as for quartz optically stimulated luminescence (OSL) dating of sediments were applied for age estimation of a mortar fragment removed from a Byzantine church monument dated by archaeological means to 1050-1100 years ago (the first half of the 10th century). The OSL from the quartz was monitored under blue light stimulation and UV detection, using a single-aliquot-regenerative-dose protocol. The quartz-OSL dating of the mortar resulted in 870±230 a. TL polymineral fine grain dating was also performed on a brick fragment which was connected to the mortar, resulting in a TL age of 1095±190 a. (author)

Experimental and modelling study of pulsed optically stimulated luminescence in quartz, marble and beta irradiated salt

International Nuclear Information System (INIS)

Pagonis, V; Mian, S M; Barnold, C; Chithambo, M L; Christensen, E

2009-01-01

Optical stimulation luminescence (OSL) signals can be obtained using continuous-wave optical stimulation (CW-OSL), the linear modulation optical stimulation method (LM-OSL) and the time-resolved optical stimulation (TR-OSL) method. During TR-OSL measurements, the stimulation and emission of luminescence are experimentally separated in time by using short light pulses. This paper presents new TR-OSL data for annealed high purity synthetic quartz, for marble and for commercially available iodized salt. A new type of behaviour for TR-OSL signals for quartz and iodized salt is presented, in which the OSL signal exhibits a nonmonotonic behaviour during optical stimulation; this type of behaviour has not been reported previously in the literature for quartz. Furthermore, a luminescence component with very long luminescence lifetime is reported for some quartz aliquots, which may be due to the presence of a delayed-OSL (DOSL) mechanism in quartz. A new kinetic model for TR-OSL in quartz is presented, which is based on a main electron trap and on several luminescence centres. The model is used to quantitatively fit several sets of experimental data of pulsed optically stimulated luminescence from quartz.

Spectrographic analysis of metallic silicium and natural quartz

International Nuclear Information System (INIS)

Grigoletto, T.; Lordello, A.R.

1985-01-01

A method has been developed for the spectrographic determination of B, Mg, Al, Ca, Ti, Mn, Fe, Ni, Cu and Ag in silicon metal and other for Al, Ca, Mg, Ti, Cr, Mn, and Fe in natural quartz. A mixture of the matrix with a proper buffer is excited directly in a dc-arc. High-current (25A) and argon atmosphere are used for both the methods. Silicon metal is blended with 8% NaF and after 1:1 (w/w) with graphite. For natural quartz 20% NaF and 30% graphite by weight is the buffer mixture employed. The lower values in the determinations varies from 0.5 to 40 μg/g and the precision of the analysis from 7% to 45%. (Author) [pt

Quartz luminescence response to a mixed alpha-beta field: Investigations on Romanian loess

International Nuclear Information System (INIS)

Constantin, Daniela; Jain, Mayank; Murray, Andrew S.; Buylaert, Jan-Pieter; Timar-Gabor, Alida

2015-01-01

Previous SAR-OSL dating studies using quartz extracted from Romanian and Serbian loess samples report SAR-OSL dose–response curves on fine grained (4–11 μm) quartz that grow to much higher doses compared to those of coarse-grained (63–90, 90–125, 125–180 μm) quartz. Furthermore, quartz SAR-OSL laboratory dose response curves do not reflect the growth of the OSL signal in nature. A main difference in coarse- and fine-grained quartz dating lies in the alpha irradiation history, but the effect of mixed alpha-beta fields has so far received little attention. In the present study we investigate whether the alpha dose experienced by fine grains over geological cycles of irradiation and bleaching may have an effect on the saturation characteristics of the laboratory dose response. By applying time resolved optically stimulated luminescence we confirm that the OSL signals induced in quartz by alpha and beta radiation follow the same recombination path. We also show that a mixed alpha-beta dose response reproduces the beta dose response only up to about 800 Gy. Assuming an a-value of 0.04 we have shown that laboratory alpha and beta dose response curves overlap up to effective alpha doses of ∼50 Gy. Based on these results, we conclude that exposure of fine grains to alpha radiation during burial and transport cycles prior to deposition, as well exposure to the mixed radiation field experienced during burial are not responsible for the age discrepancies previously reported on fine and coarse grained quartz extracted from Romanian and Serbian loess. - Highlights: • Prior alpha irradiation history does not influence the laboratory beta growth curves. • Alpha and beta induced photon emissions in quartz follow the same recombination path. • Laboratory alpha and beta growth curves overlap up to total alpha doses of ∼1250 Gy. • Mixed alpha-beta growth curves reproduce the beta dose response curves up to ∼800 Gy. • Mixed radiation field is not

Radiation-induced frequency transients in AT, BT, and SC cut quartz resonators

International Nuclear Information System (INIS)

Koehler, D.R.

1979-01-01

Earlier studies of transient frequency changes in high-purity swept AT quartz resonators led to the conclusion that impurity-induced effects were small, while the observed changes were qualitatively and quantitatively well characterized in terms of the time changing temperature of the vibrating quartz and its effect on frequency. 5 MHz, AT cut fifth overtone, and BT and SC cut third overtone resonators were prepared from a single stone of Sawyer swept Premium-Q quartz. The resonators were operated in precision ovenized oscillators at or near their turnover temperatures. Pulsed irradiation, at dose levels of the order of 10 4 rads (Si) per pulse, was accomplished at Sandia. The experimental data display negative frequency transients for the AT cut resonators, positive frequency transients for the BT cut resonators, and very small transient effects for the SC cut resonators. From these experimental results, it is concluded that no measurable impurity-induced frequency changes are observed in this high-purity swept-quartz and that the frequency transients are accurately modelled in terms of transient temperature effects stemming from the thermal characteristics of the resonator structure

A study of positron properties in quartz crystals and synthetic silica glass

International Nuclear Information System (INIS)

Anwand, W.; Brauer, G.; Hesegawa, M.; Dersch, O.; Rauch, F.

2001-01-01

The monoenergetic positron beamline 'SPONSOR' at Rossendorf has been used to investigate the positron behaviour in a naturally grown Brasilian quartz, two synthetic quartz crystals of different origin, and synthetic silica glass. The measurements allow us to obtain the positron diffusion length of free positrons and Bloch para-positronium, if formed, in these materials. In addition, hydrothermal treatment of a synthetic quartz has been used to introduce hydrogen into the crystal up to a certain depth. The presence of hydrogen is found to influence the formation of para-positronium. The depth distribution of hydrogen has been measured independently by the nuclear reaction analysis, and will be discussed in comparison with the results deduced from the positron studies. (author)

Constraints on Alpine Fault (New Zealand) Mylonitization Temperatures and Geothermal Gradient from Ti-in-quartz Thermobarometry

OpenAIRE

Kidder, Steven; Toy, Virginia; Prior, Dave; Little, Tim; MacRae, Colin

2018-01-01

We constrain the thermal state of the central Alpine Fault using approximately 750 Ti-in-quartz SIMS analyses from a suite of variably deformed mylonites. Ti-in-quartz concentrations span more than an order of magnitude from 0.24 to ~5 ppm, suggesting recrystallization of quartz over a 300° range in temperature. Most Ti-in-quartz concentrations in mylonites, protomylonites, and the Alpine Schist protolith are between 2 and 4 ppm and do not vary as a function of grain size or bul...

Competition between Halogen, Hydrogen and Dihydrogen Bonding in Brominated Carboranes

Czech Academy of Sciences Publication Activity Database

Fanfrlík, Jindřich; Holub, Josef; Růžičková, Z.; Řezáč, Jan; Lane, P. D.; Wann, D. A.; Hnyk, Drahomír; Růžička, A.; Hobza, Pavel

2016-01-01

Roč. 17, č. 21 (2016), s. 3373-3376 ISSN 1439-4235 R&D Projects: GA ČR(CZ) GBP208/12/G016; GA ČR(CZ) GA15-05677S Institutional support: RVO:61388963 ; RVO:61388980 Keywords : bromine * carboranes * halogen bonds * sigma holes * X-ray crystal structure Subject RIV: CF - Physical ; Theoretical Chemistry; CA - Inorganic Chemistry (UACH-T) Impact factor: 3.075, year: 2016

Strength and Character of Halogen Bonds in Protein-Ligand Complexes

Czech Academy of Sciences Publication Activity Database

Riley, Kevin Eugene; Hobza, Pavel

2011-01-01

Roč. 11, č. 10 (2011), s. 4272-4278 ISSN 1528-7483 R&D Projects: GA MŠk LC512 Grant - others:Research and Development for Innovations of European Social Fund(XE) CZ.1.05/2.1.00/03.0058 Institutional research plan: CEZ:AV0Z40550506 Keywords : halogen bond * protein-ligand complexes * calculations Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.720, year: 2011

Adhesion of Escherichia coli onto quartz, hematite and corundum: extended DLVO theory and flotation behavior.

Science.gov (United States)

Farahat, Mohsen; Hirajima, Tsuyoshi; Sasaki, Keiko; Doi, Katsumi

2009-11-01

The adhesion of Escherichia coli onto quartz, hematite and corundum was experimentally investigated. A strain of E. coli was used that had the genes for expressing protein for silica precipitation. The maximum cell adhesion was observed at pH mineral adhesion was assessed by the extended DLVO theory approach. The essential parameters for calculation of microbe-mineral interaction energy (Hamaker constants and acid-base components) were experimentally determined. The extended DLVO approach could be used to explain the results of the adhesion experiments. The effect of E. coli on the floatability of three oxide minerals was determined and the results showed that E. coli can act as a selective collector for quartz at acidic pH values, with 90% of the quartz floated at 1.5 x 10(9)cells/ml. However, only 9% hematite and 30% corundum could be floated under similar conditions. By using E. coli and no reagents, it was possible to separate quartz from a hematite-quartz mixture with Newton's efficiency of 0.70. Removal of quartz from the corundum mixture was achieved by E. coli with Newton's efficiency of 0.62.

Acoustic loss and frequency stability studies of gamma- and proton-irradiated alpha-quartz crystal resonators

International Nuclear Information System (INIS)

Suter, J.J.

1988-01-01

This work examines the radiation-induced effects in alpha-quartz crystal resonators and distinguishes the various acoustic losses responsible for the frequency susceptibility over these dose ranges. Simulation of low-earth-orbit proton radiation was accomplished with protons from the Harvard University Cyclotron using a novel proton-beam modulator, which was designed to emulate a 10-120 MeV proton spectrum for the radiation susceptibility and acoustic-loss studies on AT quartz resonators. Quartz resonators having aluminum defect center concentrations between 0.01 and 19 ppm experienced proton-induced frequency shifts not correlated to their aluminum impurity content. It was also found that AT quartz resonators of the electrode-less BVA design experienced the smallest frequency shifts. Experiments conducted with 1.25-MeV gamma rays from a cobalt 60 source demonstrated identical frequency shifts in quartz, indicating that the energy losses of gamma rays and protons in quartz over the examined dose and energy ranges were similar. Acoustic-loss measurements conducted over the 0.3-70 K range revealed that the phonon-phonon and two-level energy excitation peaks near 20 and 5 K, respectively, were not affected by proton or cobalt 60 radiation

Post mortem analysis of a JET quartz microbalance system

Energy Technology Data Exchange (ETDEWEB)

Esser, H.G. [Association EURATOM-Forschungszentrum Juelich, IPP, D-52425, Juelich (Germany)]. E-mail: h.g.esser@fz-juelich.de; Philipps, V. [Association EURATOM-Forschungszentrum Juelich, IPP, D-52425, Juelich (Germany); Wienhold, P. [Association EURATOM-Forschungszentrum Juelich, IPP, D-52425, Juelich (Germany); Sugiyama, K. [Department of Nuclear Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Kreter, A. [Association EURATOM-Forschungszentrum Juelich, IPP, D-52425, Juelich (Germany); Coad, J.P. [UKAEA/EURATOM Fusion Association, Culham Science Centre, Abingdon (United Kingdom); Tanabe, T. [Department of Nuclear Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

2007-06-15

In the year 2001, a quartz microbalance system (QMB) was installed in the remote area of the inner JET divertor to investigate in situ material erosion and redeposition processes. When removed in 2004, the system was found to be coated all over with carbon deposits. The deposit on the quartz oscillator and the outer and inner housing was analysed by various methods, as SIMS (secondary ion mass spectroscopy), stylus depth profilometry, EPMA (electron probe microanalysis), TIPT (Tritium imaging plate technique) and colorimetry and compared to the frequency change of the quartz. The layer thickness was determined to 1.85 {+-} 0.1 {mu}m in average on an area of 0.95 cm{sup 2} which has to be related to the equivalent of 1.77 x 10{sup -4} g measured from the frequency change of 23 640 Hz. This corresponds to a carbon areal density of 9.3 x 10{sup 18} C atoms/cm{sup 2}. Significant deposition was found also on the surfaces inside the QMB housing which can only be understood if reflection and low sticking is assumed for a high fraction of particles.

A halogen-free synthesis of gold nanoparticles using gold(III) oxide

International Nuclear Information System (INIS)

Sashuk, Volodymyr; Rogaczewski, Konrad

2016-01-01

Gold nanoparticles are one of the most used nanomaterials. They are usually synthesized by the reduction of gold(III) chloride. However, the presence of halide ions in the reaction mixture is not always welcome. In some cases, these ions have detrimental influence on the morphology and structure of resulting nanoparticles. Here, we present a simple and halogen-free procedure to prepare gold nanoparticles by reduction of gold(III) oxide in neat oleylamine. The method provides the particles with an average size below 10 nm and dispersity of tens of percent. The process of nanoparticle formation was monitored using UV–Vis spectroscopy. The structure and chemical composition of the nanoparticles was determined by SEM, XPS and EDX. We also proposed the mechanism of reduction of gold(III) oxide based on MS, IR and NMR data. Importantly, the synthetic protocol is general and applicable for the preparation of other coinage metal nanoparticles from the corresponding metal oxides. For instance, we demonstrated that the absence of halogen enables efficient alloying of metals when preparing gold–silver bimetallic nanoparticles.

Relationship of Technological Properties with Dynamic Recrystallization of Quartz on the Example of Objects of the Karelian-Kola Region

Science.gov (United States)

Skamnitskaya, Lubov; Rakov, Leonid; Bubnova, Tatyana; Shchiptsov, Vladimir

2017-12-01

Despite the significant reserves of quartz raw materials, there is a deficit of high purity quartz. It is due to the strict technical requirements imposed by standards for this type of raw materials and technological properties of quartz, which are determined by the features of the crystal structure. The crystalline structure is of particular importance for the technological properties of quartz, since such important characteristics as the limit of raw material enrichment, dissolution rate in acid, melting point of quartz, etc., are determined. The formation of the crystal structure of quartz under natural conditions is associated with the successive dynamic recrystallization of the mineral. The degree of dynamic recrystallization of quartz reflects the distribution of dispersed impurities. If it is weakly manifested, the dispersed impurities are not displaced from one zone to another, and all quartz microblocks contain approximately the same concentration. In this case, more or less uniform dissolution of various regions of quartz is observed, and the pattern of distribution of submicroscopic inhomogeneities is monotonic. If intensive dynamic recrystallization of quartz takes place, then it causes a significant redistribution of the scattered impurities. Then the treatment in HF leads to the appearance of a contrast pattern of the distribution of submicroscopic inhomogeneities. The details of the crystal structure of quartz in this work were investigated by the electron paramagnetic resonance (EPR) method using the ER-420 “Bruker” spectrometer. In the selected samples of quartz, the concentrations of isomorphic impurities Al and Ti were measured, and the degree of crystallinity D of the mineral was estimated from the EPR spectra of each of them. Thus, the technological properties of quartz are determined by various geological processes. The results of the studies show that when evaluating the prospects of quartz raw materials, it is necessary to take into

Halogen doping of II-VI semiconductors during molecular beam epitaxy

Energy Technology Data Exchange (ETDEWEB)

Waag, A.; Litz, Th.; Fischer, F.; Heinke, H.; Scholl, S.; Hommel, D.; Landwehr, G. (Physikalisches Inst. der Univ. Wuerzburg (Germany)); Bilger, G. (Zentrum fuer Sonnenenergie und Wasserstoff-Forschung, Stuttgart (Germany))

1994-04-14

Results on the halogen doping of CdTe, (CdMn)Te as well as (CdMg)Te thin films and quantum well structures are reported. The structures were grown by molecular beam epitaxy. The samples have been investigated by Van der Pauw, photoconductivity, X-ray diffraction, XPS and SIMS measurements. ZnCl[sub 2] and ZnBr[sub 2] have been used as dopant sources. Free carrier concentrations at room temperature above 10[sup 18] cm[sup -3] can easily be achieved for CdTe for a wide range of Cd/Te flux ratios and substrate temperatures. In the ternary alloys, the free carrier concentration decreases drastically with increasing x-values, despite a constant incorporation of the dopant species. In addition, persistent photoconductivity has been observed in n-type doped ternary thin films at low temperatures. The decrease of the free carrier concentration with x-value is common to other wide-gap ternary alloys, and the reason for it is discussed in the frame of DX-like deep donor impurities in ternary II-VI compounds. In first experiments on planar halogen doping of CdTe, a doping level of 5x10[sup 18] cm[sup -3] could be reached in the doped regions, the highest value ever reported for CdTe. A clear influence of dopant incorporation on the structural quality of CdTe thin films has been seen even for dopant concentrations of as low as 10[sup 18] cm[sup -3]. The FWHM of the rocking curves decreased by a factor of 2 with increasing dopant incorporation. SIMS as well as XPS measurements demonstrate that the Cl/Zn and Br/Zn ratio in the doped films is 2/1, but no chemical shift corresponding to Zn-Cl or Zn-Br bonds could be detected. A model for the incorporation of the halogens is proposed on the basis of these results

Magma reservoir dynamics at Toba caldera, Indonesia, recorded by oxygen isotope zoning in quartz.

Science.gov (United States)

Budd, David A; Troll, Valentin R; Deegan, Frances M; Jolis, Ester M; Smith, Victoria C; Whitehouse, Martin J; Harris, Chris; Freda, Carmela; Hilton, David R; Halldórsson, Sæmundur A; Bindeman, Ilya N

2017-01-25

Quartz is a common phase in high-silica igneous rocks and is resistant to post-eruptive alteration, thus offering a reliable record of magmatic processes in silicic magma systems. Here we employ the 75 ka Toba super-eruption as a case study to show that quartz can resolve late-stage temporal changes in magmatic δ 18 O values. Overall, Toba quartz crystals exhibit comparatively high δ 18 O values, up to 10.2‰, due to magma residence within, and assimilation of, local granite basement. However, some 40% of the analysed quartz crystals display a decrease in δ 18 O values in outermost growth zones compared to their cores, with values as low as 6.7‰ (maximum ∆ core-rim  = 1.8‰). These lower values are consistent with the limited zircon record available for Toba, and the crystallisation history of Toba quartz traces an influx of a low-δ 18 O component into the magma reservoir just prior to eruption. Here we argue that this late-stage low-δ 18 O component is derived from hydrothermally-altered roof material. Our study demonstrates that quartz isotope stratigraphy can resolve magmatic events that may remain undetected by whole-rock or zircon isotope studies, and that assimilation of altered roof material may represent a viable eruption trigger in large Toba-style magmatic systems.

Flue gas corrosion through halogen compounds in fuel gas

Energy Technology Data Exchange (ETDEWEB)

Eisenmann, R

1987-04-01

The halogens of chlorine and fluorine greatly influence the corrosion speed of metal materials. If small quantities of chlorinated and/or fluorinated hydrocarbons are present in fuel gas like in landfill gas, they must not result in enhanced corrosion of gas appliances. Data from literature and the initial results of tests run by the author indicate that quantities at about 10 mg/cbm (in terms of chlorine) can be assumed not to cause any noticeable acceleration of corrosion speed.

Environmental and economic implications of a shift to halogen-free printed wiring boards

Energy Technology Data Exchange (ETDEWEB)

Bergendahl, C.G.; Johansson, G.; Zackrisson, M. [IVF Industrial Research and Development Corp., Moelndal (Sweden); Lichtenvort, K. [Technical Univ. of Berlin (Germany); Nyyssoenen, J. [Aspocomp Oy, Salo (Finland)

2004-07-01

The 'Restriction of Hazardous Substances Directive' (RoHS) and the 'Waste from Electrical and Electronic Equipment Directive' (WEEE) enforced by the European Commission require new materials and processes to be implemented in the production of electrical and electronic equipment (EEE). In response to this, the project grEEEn (Cost Management System for greening Electrical and Electronic Equipment) was defined and carried out within the 5th framework programme of the EU. This paper presents the grEEEn method and the outcome of applying the method on a case study. The study addressed the material shift in printed wiring boards (PWBs), from the traditional FR4 material containing halogenated flame retardants to halogen-free FR4 materials. The paper presents the product, process and scenario modelling and the results from analysing costs, environmental profile and legal compliance. (orig.)

75 FR 12468 - Airworthiness Directives; Quartz Mountain Aerospace, Inc. Model 11E Airplanes

Science.gov (United States)

2010-03-16

... Aerospace, Inc. Model 11E Airplanes AGENCY: Federal Aviation Administration (FAA), Department of... airworthiness directive (AD) for all Quartz Mountain Aerospace, Inc. Model 11E airplanes. This proposed AD would... 5 p.m., Monday through Friday, except Federal holidays. Quartz Mountain Aerospace, Inc. is in...

Nitrate-cancrinite precipitation on quartz sand in simulated Hanford tank solutions.

Science.gov (United States)

Bickmore, B R; Nagy, K L; Young, J S; Drexler, J W

2001-11-15

Caustic NaNO3 solutions containing dissolved Al were reacted with quartz sand at 89 degrees C to simulate possible reactions between leaked nuclear waste and primary subsurface minerals at the U.S. Department of Energy's Hanford site in Washington. Nitrate-cancrinite began to precipitate onto the quartz after 2-10 days, cementing the grains together. Estimates of the equilibrium constant for the precipitation reaction differ for solutions with 0.1 or 1.0 m OH- (log Keq = 30.4 +/- 0.8 and 36.2 +/- 0.6, respectively). The difference in solubility may be attributable to more perfect crystallinity (i.e., fewer stacking faults) in the higher-pH cancrinite structure. This is supported by electron micrographs of crystal morphology and measured rates of Na volatilization under an electron beam. Precipitate crystallinity may affect radionuclide mobility, because stacking faults in the cancrinite structure can diminish its zeolitic cation exchange properties. The precipitation rate near the onset of nucleation depends on the total Al and Si concentrations in solution. The evolution of experimental Si concentrations was modeled by considering the dependence of quartz dissolution rate on AI(OH)4- activity, cancrinite precipitation, and the reduction of reactive surface area of quartz due to coverage by cancrinite.

Gas loading of graphene-quartz surface acoustic wave devices

Science.gov (United States)

Whitehead, E. F.; Chick, E. M.; Bandhu, L.; Lawton, L. M.; Nash, G. R.

2013-08-01

Graphene was transferred to the propagation path of quartz surface acoustic wave devices and the attenuation due to gas loading of air and argon measured at 70 MHz and 210 MHz and compared to devices with no graphene. Under argon loading, there was no significant difference between the graphene and non-graphene device and the values of measured attenuation agree well with those calculated theoretically. Under air loading, at 210 MHz, there was a significant difference between the non-graphene and graphene devices, with the average value of attenuation obtained with the graphene devices being approximately twice that obtained from the bare quartz devices.

Quartz microbalance device for transfer into ultrahigh vacuum systems

International Nuclear Information System (INIS)

Stavale, F.; Achete, C. A.; Niehus, H.

2008-01-01

An uncomplicated quartz microbalance device has been developed which is transferable into ultrahigh vacuum (UHV) systems. The device is extremely useful for flux calibration of different kinds of material evaporators. Mounted on a commercial specimen holder, the device allows fast quartz microbalance transfer into the UHV and subsequent positioning exactly to the sample location where subsequent thin film deposition experiments shall be carried out. After backtransfer into an UHV sample stage, the manipulator may be loaded in situ with the specimen suited for the experiment. The microbalance device capability is demonstrated for monolayer and submonolayer vanadium depositions with an achieved calibration sensitivity of less the 0.001 ML coverage.

Characterization of silica quartz as raw material in photovoltaic applications

Energy Technology Data Exchange (ETDEWEB)

Boussaa, S. Anas, E-mail: sabiha.anas@gmail.com; Kheloufi, A.; Kefaifi, A.; Kerkar, F. [Division croissance cristalline et procédés métallurgiques CCPM Centre de recherche en technologie des semi-conducteurs pour l’énergétique (C.R.T.S.E) 02 Bd Frantz Fanon BP. 140 Alger 7 merveilles, Alger 16200 (Algeria); Zaourar, N. Boutarek [Laboratoire des technologies des matériaux, USTHB, B.P. 32 El Alia, Bab Ezzouar, Alger, Algérie 16111 (Algeria)

2016-07-25

Raw materials are essential for the functioning of modern societies, and access to these raw materials is vital to the world economy. Sustainable development, both globally level, raises important new challenges associated with access and efficient use of raw materials. High purity quartz, is consider as a critical raw material and it is a rare commodity that only forms under geological conditions where a narrow set of chemical and physical parameters is fulfilled. When identified and following special beneficiation techniques, high purity quartz obtains very attractive prices and is applied in high technology sectors that currently are under rapid expansion such as photovoltaic solar cells, silicon metal - oxide wafers in the semiconductor industry and long distance optical fibers that are used in communication networks. Crystalline silicon remains the principal material for photovoltaic technology. Metallurgical silicon is produced industrially by the reduction of silica with carbon in an electric arc furnace at temperatures higher than 2000 °C in the hottest parts, by a reaction that can be written ideally as: SiO{sub 2} + 2C = Si + 2CO. The aim of this study has been to test experimental methods for investigating the various physical and chemical proprieties of Hoggar quartz with different techniques: X Ray Fluorescence, infra-red spectroscopy, Scanning Electron Microscopy, Optic Microscopy, Carbon Analyzer and Vickers Hardness. The results show finally that the quartz has got good result in purity but need enrichment for the photovoltaic application.

Theoretical modelling of experimental diagnostic procedures employed during pre-dose dosimetry of quartz

International Nuclear Information System (INIS)

Pagonis, V.; Chen, R.; Kitis, G.

2006-01-01

The pre-dose technique in thermoluminescence (TL) is used for dating archaeological ceramics and for accident dosimetry. During routine applications of this technique, the sensitisation of the quartz samples is measured as a function of the annealing temperature, yielding the so-called thermal activation characteristic (TAC). The measurement of multiple TACs and the study of the effect of UV-radiation on the TL sensitivity of quartz are important analytical and diagnostic tools. In this paper, it is shown that a modified Zimmerman model for quartz can successfully model the experimental steps undertaken during a measurement of multiple TACs. (authors)

Optical modulation in nematic phase of halogen substituted hydrogen bonded liquid crystals

Science.gov (United States)

Vijayakumar, V. N.; Madhu Mohan, M. L. N.

2012-01-01

A series of halogen-substituted hydrogen-bonded liquid crystalline complexes have been designed and synthesised. A successful attempt has been made to form complementary hydrogen bonding between the dodecyloxy benzoic acid (12BAO) and halogen-substituted benzoic acids and the physical properties exhibited by the individual complexes are studied. The complexes obtained are analysed by polarising optical microscope (POM), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR) and dielectric studies. The formation of complementary hydrogen bond is confirmed through FTIR spectra. An interesting feature of this series is the observation of a field-induced transition (FiT) in nematic phase. Another interesting phenomenon is the observation of a new smectic X phase (worm-like texture) in all the synthesised complexes. Dielectric relaxation studies in the smectic C phase of these hydrogen bonded complexes along with the Arrhenius and the Cole-Cole plots are discussed. Optical tilt angle in smectic C phase and the corresponding fitted data analysis concur with the Mean field theory prediction.

Hydrogenated and halogenated blue phosphorene as Dirac materials: A first principles study

International Nuclear Information System (INIS)

Sun, Minglei; Wang, Sake; Yu, Jin; Tang, Wencheng

2017-01-01

Highlights: • The fully hydrogenated and halogenated blue phosphorenes are 2D Dirac materials. • The Dirac cone in fluorinated and iodinated blue phosphorenes lies exactly at the Fermi level. • The mass density of hydrogenated and fluorinated blue phosphorenes is rather small. - Abstract: Using first-principles calculations, we systematically investigate the structures and electronic properties of fully hydrogenated and halogenated blue phosphorene (P_2X_2). All these systems possess Dirac cone at high-symmetry K point, which are mainly contributed by P s p_x p_y orbitals. The Dirac cone in P_2F_2 and P_2I_2 systems lies exactly at the Fermi level. Formation energy analysis denotes that all the systems are energetically stable except P_2I_2. The mass density for P_2H_2 and P_2F_2 systems is rather small. Our calculations proposed that these systems, especially P_2F_2 system, have great potential applications in future nanoelectronics.

Negative atomic halogens incident on argon and molecular nitrogen: electron detachment studies

International Nuclear Information System (INIS)

Jalbert, G; Medina, A; Magalhaes, S D; Wolff, W; Barros, A L F de; Carrilho, P; Rocha, A B; Faria, N V de Castro

2007-01-01

During the last years we have measured total detachment cross sections of atomic and cluster anions colliding with gases in the velocity range of 0.2 to 1.8 a.u. In particular, we measured negative atomic halogens incident on argon and molecular nitrogen. These last data are for the first time analyzed using the simple semi-classical model that we have developed. For that purpose, the values of elastic plus inelastic cross sections for impact of free electrons on Ar and N 2 , the latter showing a shape resonance, convoluted with the anion's outermost electron momentum distribution yielded the overall shape of the anion cross sections. Inclusion of a velocity independent additive term, interpreted as an effective area of the collision region, led to accurate absolute cross section values. The high affinity of the halogens and the existence of a not well described resonance in the e-N 2 collision, are characteristics that may be used to delimit the scope and validity of the model

A simple and automated sample preparation system for subsequent halogens determination: Combustion followed by pyrohydrolysis.

Science.gov (United States)

Pereira, L S F; Pedrotti, M F; Vecchia, P Dalla; Pereira, J S F; Flores, E M M

2018-06-20

A simple and automated system based on combustion followed by a pyrohydrolysis reaction was proposed for further halogens determination. This system was applied for digestion of soils containing high (90%) and also low (10%) organic matter content for further halogens determination. The following parameters were evaluated: sample mass, use of microcrystalline cellulose and heating time. For analytes absorption, a diluted alkaline solution (6 mL of 25 mmol L -1  NH 4 OH) was used in all experiments. Up to 400 mg of soil with high organic matter content and 100 mg of soil with low organic matter content (mixed with 400 mg of cellulose) could be completely digested using the proposed system. Quantitative results for all halogens were obtained using less than 12 min of sample preparation step (about 1.8 min for sample combustion and 10 min for pyrohydrolysis). The accuracy was evaluated using a certified reference material of coal and spiked samples. No statistical difference was observed between the certified values and results obtained by the proposed method. Additionally, the recoveries obtained using spiked samples were in the range of 98-103% with relative standard deviation values lower than 5%. The limits of quantification obtained for F, Cl, Br and I for soil with high (400 mg of soil) and low (100 mg of soil) organic matter were in the range of 0.01-2 μg g -1 and 0.07-59 μg g -1 , respectively. The proposed system was considered as a simple and suitable alternative for soils digestion for further halogens determination by ion chromatography and inductively coupled plasma mass spectrometry techniques. Copyright © 2018 Elsevier B.V. All rights reserved.

Luminescence lifetimes in quartz: dependence on annealing temperature prior to beta irradiation

International Nuclear Information System (INIS)

Galloway, R.B.

2002-01-01

It is well known that the thermal history of a quartz sample influences the optically stimulated luminescence sensitivity of the quartz. It is found that the optically stimulated luminescence lifetime, determined from time resolved spectra obtained with pulsed stimulation, also depends on past thermal treatment. For samples at 20 deg. C during stimulation, the lifetime depends on beta dose and on duration of preheating at 220 deg. C prior to stimulation for quartz annealed at 600 deg. C and above, but is independent of these factors for quartz annealed at 500 deg. C and below. For stimulation at higher temperatures, the lifetime becomes shorter if the sample is held at temperatures above 125 deg. C during stimulation, in a manner consistent with thermal quenching. A single exponential decay is all that is required to fit the time resolved spectra for un-annealed quartz regardless of the temperature during stimulation (20-175 deg. C), or to fit the time resolved spectra from all samples held at 20 deg. C during stimulation, regardless of annealing temperature (20-1000 deg. C). An additional shorter lifetime is found for some combinations of annealing temperature and temperature during stimulation. The results are discussed in terms of a model previously used to explain thermal sensitisation. The luminescence lifetime data are best explained by the presence of two principal luminescence centres, their relative importance depending on the annealing temperature, with a third centre involved for limited combinations of annealing temperature and temperature during stimulation

High-Precision Hysteresis Sensing of the Quartz Crystal Inductance-to-Frequency Converter.

Science.gov (United States)

Matko, Vojko; Milanović, Miro

2016-06-28

A new method for the automated measurement of the hysteresis of the temperature-compensated inductance-to-frequency converter with a single quartz crystal is proposed. The new idea behind this method is a converter with two programmable analog switches enabling the automated measurement of the converter hysteresis, as well as the temperature compensation of the quartz crystal and any other circuit element. Also used is the programmable timing control device that allows the selection of different oscillating frequencies. In the proposed programmable method two different inductances connected in series to the quartz crystal are switched in a short time sequence, compensating the crystal's natural temperature characteristics (in the temperature range between 0 and 50 °C). The procedure allows for the measurement of the converter hysteresis at various values of capacitance connected in parallel with the quartz crystal for the converter sensitivity setting at selected inductance. It, furthermore, enables the measurement of hysteresis at various values of inductance at selected parallel capacitance (sensitivity) connected to the quartz crystal. The article shows that the proposed hysteresis measurement of the converter, which converts the inductance in the range between 95 and 100 μH to a frequency in the range between 1 and 200 kHz, has only 7 × 10(-13) frequency instability (during the temperature change between 0 and 50 °C) with a maximum 1 × 10(-11) hysteresis frequency difference.

High-Precision Hysteresis Sensing of the Quartz Crystal Inductance-to-Frequency Converter

Directory of Open Access Journals (Sweden)

Vojko Matko

2016-06-01

Full Text Available A new method for the automated measurement of the hysteresis of the temperature-compensated inductance-to-frequency converter with a single quartz crystal is proposed. The new idea behind this method is a converter with two programmable analog switches enabling the automated measurement of the converter hysteresis, as well as the temperature compensation of the quartz crystal and any other circuit element. Also used is the programmable timing control device that allows the selection of different oscillating frequencies. In the proposed programmable method two different inductances connected in series to the quartz crystal are switched in a short time sequence, compensating the crystal’s natural temperature characteristics (in the temperature range between 0 and 50 °C. The procedure allows for the measurement of the converter hysteresis at various values of capacitance connected in parallel with the quartz crystal for the converter sensitivity setting at selected inductance. It, furthermore, enables the measurement of hysteresis at various values of inductance at selected parallel capacitance (sensitivity connected to the quartz crystal. The article shows that the proposed hysteresis measurement of the converter, which converts the inductance in the range between 95 and 100 μH to a frequency in the range between 1 and 200 kHz, has only 7 × 10−13 frequency instability (during the temperature change between 0 and 50 °C with a maximum 1 × 10−11 hysteresis frequency difference.

Diagenèse expérimentale du quartz en présence d'hydrocarbures

OpenAIRE

Teinturier , Stéphane

2002-01-01

Quartz cementation has a great impact on petroleum reservoir quality by controlling the porosity and thus the gas or oil storage. Experiments were carried out in a silica+-water+-salts+-oil+-gas system with the objective to simulate the siliceous diagenesis of natural petroleum reservoirs and to better understand the mechanisms of fluid inclusions formation and quartz cementation in a water and/or petroleum system.; La cimentation du quartz est un processus diagénétique important puisqu'elle ...

Experimental deformation in sandstone, carbonates and quartz aggregate

Energy Technology Data Exchange (ETDEWEB)

Cheung, Cecilia See Nga [Stony Brook Univ., NY (United States)

2015-05-01

The first part of my thesis is mainly focused on the effect of grain size distribution on compaction localization in porous sandstone. To identify the microstructural parameters that influence compaction band formation, I conducted a systematic study of mechanical deformation, failure mode and microstructural evolution in Bleurswiller and Boise sandstones, of similar porosity (~25%) and mineralogy but different sorting. Discrete compaction bands were observed to develop over a wide range of pressure in the Bleurswiller sandstone that has a relatively uniform grain size distribution. In contrast, compaction localization was not observed in the poorly sorted Boise sandstone. My results demonstrate that grain size distribution exerts important influence on compaction band development, in agreement with recently published data from Valley of Fire and Buckskin Gulch, as well as numerical studies. The second part aimed to improve current knowledge on inelastic behavior, failure mode and brittle-ductile transition in another sedimentary rock, porous carbonates. A micritic Tavel (porosity of ~13%) and an allochemical Indiana (~18%) limestones were deformed under compaction in wet and dry conditions. At lower confining pressures, shear localization occurred in brittle faulting regime. Through transitional regime, the deformation switched to cataclastic flow regime at higher confining pressure. Specifically in the cataclastic regime, the (dry and wet) Tavel and dry Indiana failed by distributed cataclastic flow, while in contrast, wet Indiana failed as compaction localization. My results demonstrate that different failure modes and mechanical behaviors under different deformation regimes and water saturation are fundamental prior to any geophysical application in porous carbonates. The third part aimed to focus on investigating compaction on quartz aggregate starting at low (MPa) using X-ray diffraction. We report the diffraction peak evolution of quartz with increasing

Thermal dependence of luminescence lifetimes and radioluminescence in quartz

Energy Technology Data Exchange (ETDEWEB)

Pagonis, V., E-mail: vpagonis@mcdaniel.edu [McDaniel College, Physics Department, Westminster, MD 21157 (United States); Chithambo, M.L. [Department of Physics and Electronics, Rhodes University, PO BOX 94, Grahamstown 6140 (South Africa); Chen, R. [Raymond and Beverly Sackler School of Physics and Astronomy, Tel-Aviv University, Tel-Aviv 69978 (Israel); Chruścińska, A. [Institute of Physics, Nicholas Copernicus University, 87-100 Toruń (Poland); Fasoli, M. [Department of Materials Science, University of Milano-Bicocca, Via Cozzi 53, 20125 Milano (Italy); Li, S.H. [Department of Earth Sciences, The University of Hong Kong (Hong Kong); Martini, M. [Department of Materials Science, University of Milano-Bicocca, Via Cozzi 53, 20125 Milano (Italy); Ramseyer, K. [Institut für Geologie, Baltzerstrasse 1-3, 3012 Bern (Switzerland)

2014-01-15

During time-resolved optical stimulation experiments (TR-OSL), one uses short light pulses to separate the stimulation and emission of luminescence in time. Experimental TR-OSL results show that the luminescence lifetime in quartz of sedimentary origin is independent of annealing temperature below 500 °C, but decreases monotonically thereafter. These results have been interpreted previously empirically on the basis of the existence of two separate luminescence centers L{sub H} and L{sub L} in quartz, each with its own distinct luminescence lifetime. Additional experimental evidence also supports the presence of a non-luminescent hole reservoir R, which plays a critical role in the predose effect in this material. This paper extends a recently published analytical model for thermal quenching in quartz, to include the two luminescence centers L{sub H} and L{sub L}, as well as the hole reservoir R. The new extended model involves localized electronic transitions between energy states within the two luminescence centers, and is described by a system of differential equations based on the Mott–Seitz mechanism of thermal quenching. It is shown that by using simplifying physical assumptions, one can obtain analytical solutions for the intensity of the light during a TR-OSL experiment carried out with previously annealed samples. These analytical expressions are found to be in good agreement with the numerical solutions of the equations. The results from the model are shown to be in quantitative agreement with published experimental data for commercially available quartz samples. Specifically the model describes the variation of the luminescence lifetimes with (a) annealing temperatures between room temperature and 900 °C, and (b) with stimulation temperatures between 20 and 200 °C. This paper also reports new radioluminescence (RL) measurements carried out using the same commercially available quartz samples. Gaussian deconvolution of the RL emission spectra was

Hydrogen sensing method with a quartz sensor

International Nuclear Information System (INIS)

Suzuki, A.; Kurokawa, A.; Nonaka, H.

2006-01-01

The stability for hydrogen leakage detection was improved by impedance measurement with a quartz sensor (Q-sensor) instead of pressure measurement with a quartz friction pressure gauge (Q-gauge) previously used. Degree of the experimental fluctuation of the impedance from the Q-sensor and of the pressure from the Q-gauge was 0.06 and 0.2 % of each output, thus showing that the Q-sensor measurement was more stable than that by the Q-gauge. Estimated minimum detection limit for hydrogen by the Q-sensor impedance measurement is also improved compared to the Q-gauge pressure measurement. Low hydrogen concentration experiment presented that the Q-sensor impedance measurement detects the 0.05 vol.% hydrogen in air at atmospheric pressure more sensitively than the Q-gauge pressure measurement. It was proved that the Q-sensor impedance measurement was more sensitive and stable as a hydrogen leakage detection method than the Q-gauge pressure measurement. (authors)

Phosphorylated lignin as a halogen-free flame retardant additive for epoxy composites

Science.gov (United States)

Gamini P. Mendis; Sydney G. Weiss; Matthew Korey; Charles R. Boardman; Mark Dietenberger; Jeffrey P. Youngblood; John A. Howarter

2016-01-01

Sustainable, non-halogenated flame retardants are desired for a variety of industry applications. Lignin, as an industrially processed wood derivative, has been examined as a potential sustainable flame retardant additive to polymer systems. Here, the lignin is phosphorylated using a pyridine-catalysed esterification reaction with diphenyl phosphoryl chloride to...

Aspects of pre-dose and other luminescence phenomena in quartz absorbed dose estimation

International Nuclear Information System (INIS)

Adamiec, G.

2000-01-01

The understanding of all luminescence processes occurring in quartz is of paramount importance in the further development of robust absorbed dose estimation techniques (for the purpose of dating and retrospective dosimetry). The findings presented in this thesis, aid future improvements of absorbed dose estimation techniques using quartz by presenting investigations in the following areas: 1) interpretation of measurement results, 2) numerical modelling of luminescence in quartz, 3) phenomena needing inclusion in future physical models of luminescence. In the first part, the variability of properties of single quartz grains is examined. Through empirical and theoretical considerations, investigations are made of various problems of measurements of luminescence using multi-grain aliquots, and specifically areas where the heterogeneity of the sample at the inter-grain level may be misinterpreted at the multi-grain-aliquot level. The results obtained suggest that the heterogeneity of samples is often overlooked, and that such differences can have a profound influence on the interpretation of measurement results. Discussed are the shape of TL glow curves, OSL decay curves, dose response curves (including consequences for using certain signals as proxies for others), normalisation procedures and D E estimation techniques. Further, a numerical model of luminescence is proposed, which includes multiple R-centres and is used to describe the pre-dose sensitisation in quartz. The numerical model exhibits a broad-scale behaviour observed experimentally in a sample of annealed quartz. The shapes of TAC for lower (20 Gy) and higher doses (1 kGy) and the evolution with temperature of the isothermal sensitisation curves are qualitatively matched for the empirical and numerical systems. In the third area, a preliminary investigation of the properties of the '110 deg. C peak' in the 550 nm emission band, in annealed quartz is presented. These properties are in sharp contrast with

Design and fabrication of an AT-cut quartz phononic Lamb wave resonator

International Nuclear Information System (INIS)

Hung, Chia-Hao; Liu, Ting-Wei; Wu, Tsung-Tsong; Wang, Wei-Shan; Esashi, Masayoshi; Lin, Yu-Ching; Sun, Jia-Hong; Chen, Yung-Yu

2013-01-01

This paper presents results on the design and fabrication of an AT-cut quartz Lamb wave resonator with phononic crystal (PC) reflective gratings. The deep reactive ion etching process with a laboratory-made etcher was utilized to fabricate PC structures of the AT-cut quartz Lamb wave resonator. The finite element method was adopted to calculate the PC band structure, effective reflective distance from the PC boundary and further the resonant modes and admittance of the phononic Lamb wave resonant cavity. Through the comparison studies between the experimental and simulated results, a design process for the AT-cut quartz phononic Lamb wave resonator was proposed. It is noted that by using the phononic reflectors, the size of the Lamb wave resonator can be reduced significantly. (paper)

Quantitative Classification of Quartz by Laser Induced Breakdown Spectroscopy in Conjunction with Discriminant Function Analysis

Directory of Open Access Journals (Sweden)

A. Ali

2016-01-01

Full Text Available A responsive laser induced breakdown spectroscopic system was developed and improved for utilizing it as a sensor for the classification of quartz samples on the basis of trace elements present in the acquired samples. Laser induced breakdown spectroscopy (LIBS in conjunction with discriminant function analysis (DFA was applied for the classification of five different types of quartz samples. The quartz plasmas were produced at ambient pressure using Nd:YAG laser at fundamental harmonic mode (1064 nm. We optimized the detection system by finding the suitable delay time of the laser excitation. This is the first study, where the developed technique (LIBS+DFA was successfully employed to probe and confirm the elemental composition of quartz samples.

Quartz substrate infrared photonic crystal

Science.gov (United States)

Ghadiri, Khosrow; Rejeb, Jalel; Vitchev, Vladimir N.

2003-01-01

This paper presents the fabrication of a planar photonic crystal (p2c) made of a square array of dielectric rods embedded in air, operating in the infrared spectrum. A quartz substrate is employed instead of the commonly used silicon or column III-V substrate. Our square structure has a normalized cylinder radius-to-pitch ratio of r/a = 0.248 and dielectric material contrast ɛr of 4.5. We choose a Z-cut synthetic quartz for its cut (geometry), and etching properties. Then a particular Z-axis etching process is employed in order to ensure the sharp-edged verticality of the rods and fast etching speed. We also present the computer simulations that allowed the establishment of the photonic band gaps (PBG) of our photonic crystal, as well as the actual measurements. An experimental measurement have been carried out and compared with different simulations. It was found that experimental results are in good agreement with different simulation results. Finally, a frequency selective device for optical communication based on the introduction of impurity sites in the photonic crystal is presented. With our proposed structure Optical System on a Chip (OsoC) with micro-cavity based active devices such as lasers, diodes, modulators, couplers, frequency selective emitters, add-drop filters, detectors, mux/demuxes and polarizers connected by passive waveguide links can be realized.

Diversity of band gap and photoluminescence properties of lead halide perovskite: A halogen-dependent spectroscopic study

Science.gov (United States)

Yu, Wenlei; Jiang, Yunfeng; Zhu, Xiuwei; Luo, Chunhua; Jiang, Kai; Chen, Liangliang; Zhang, Juan

2018-05-01

The effects of halogen substitution on microstructure, optical absorption, and phonon modes for perovskite CH3NH3PbX3 (MAPbX3, X = I/Br/Cl) films grown on FTO substrates have been investigated. The X-ray diffraction analysis exhibited good crystallization, and the strong diffraction peak assigned to (1 0 0) c for X = Br/Cl shifted toward a higher angle compared to (1 1 0) t of MAPbI3. Band-gap tuning from 1.63 to 2.37 to 3.11 eV in the I-Br-Cl series can be found due to the halogen effects. These energy values closely match the positions of peak determined from photoluminescence experiments. The remarkable absorption dip and emission peak appear for the MAPbBr3, suggesting higher crystallinity under the same preparation conditions. The wavenumbers of main IR-vibrations slightly decrease with ionic radius of the halogen increasing (in the order of Cl-Br-I), which related to the increasing polarizability. These results provide important progress towards the understanding of the halide role in the realization of high performance MAPbX3-based solar cells.

SORPTION AND DISPERSION OF STRONTIUM RADIONUCLIDE IN THE BENTONITE-QUARTZ-CLAY AS BACKFILL MATERIAL CANDIDATE ON RADIOACTIVE WASTE REPOSITORY

Directory of Open Access Journals (Sweden)

Herry Poernomo

2010-12-01

Full Text Available The experiment of sorption and dispersion characteristics of strontium in the mixture of bentonite-quartz, clay-quartz, bentonite-clay-quartz as candidate of raw material for backfill material in the radioactive waste repository has been performed. The objective of this research is to know the grain size effect of bentonite, clay, and quartz on the weight percent ratio of bentonite to quartz, clay to quartz, bentonite to clay to-quartz can be gives physical characteristics of best such as bulk density (rb, effective porosity (e, permeability (K, best sorption characteristic such as distribution coefficient (Kd, and best dispersion characteristics such as dispersivity (a and effective dispersion coefficient (De of strontium in the backfill material candidate. The experiment was carried out in the column filled by the mixture of bentonite-quartz, clay-quartz, bentonite-clay-quartz with the weight percent ratio of bentonite to quartz, clay to quartz, bentonite to clay to quartz of 100/0, 80/20, 60/40, 40/60, 20/80, 0/100 respectively at saturated condition of water, then flowed 0.1 N Sr(NO32 as buffer solution with tracer of 0.05 Ci/cm3 90Sr as strontium radionuclide simulation was leached from immobilized radioactive waste in the radioactive waste repository. The concentration of 90Sr in the effluents represented as Ct were analyzed by Ortec b counter every 30 min, then by using profile concentration of Co and Ct, values of Kd, a and De of 90Sr in the backfill material was determined. The experiment data showed that the best results were -80+120 mesh grain size of bentonite, clay, quartz respectively on the weight percent ratio of bentonite to clay to quartz of 70/10/20 with physical characteristics of rb = 0.658 g/cm3, e = 0.666 cm3/cm3, and K = 1.680x10-2 cm/sec, sorption characteristic of Kd = 46.108 cm3/g, dispersion characteristics of a = 5.443 cm, and De = 1.808x10-03 cm2/sec can be proposed as candidate of raw material of backfill material

Natural elimination of volatile halogenated hydrocarbons from the environment

Energy Technology Data Exchange (ETDEWEB)

Harress, H.M.; Grathwohl, P.; Torunski, H.

1987-01-01

Recently carried out field investigations of groundwater contaminations with volatile halogenated hydrocarbons have shown evidence of natural elimination of these hazardous substances. This elimination effects is rare and observed in connection with special geological conditions. With regard to some contaminated sites, the following mechanisms for this behaviour are discussed: 1. Stripping by naturally ascending gases. 2. Sorption on soil organic matter. 3. Biodegradation. The so far compiled knowledge allowed to develop further research programmes, which are pursued in various projects.

Variation of airborne quartz in air of Beijing during the Asia-Pacific Economic Cooperation Economic Leaders' Meeting.

Science.gov (United States)

Li, Gang; Li, Yingming; Zhang, Hongxing; Li, Honghua; Gao, Guanjun; Zhou, Qian; Gao, Yuan; Li, Wenjuan; Sun, Huizhong; Wang, Xiaoke; Zhang, Qinghua

2016-01-01

Quartz particles are a toxic component of airborne particulate matter (PM). Quartz concentrations were analyzed by X-ray diffraction in eighty-seven airborne PM samples collected from three locations in Beijing before, during, and after the Asia-Pacific Economic Cooperation (APEC) Leaders' Meeting in 2014. The results showed that the mean concentrations of quartz in PM samples from the two urban sites were considerably higher than those from the rural site. The quartz concentrations in samples collected after the APEC meeting, when the pollution restriction lever was lifted, were higher than those in the samples collected before or during the APEC meeting. The quartz concentrations ranged from 0.97 to 13.2 μg/m(3), which were among the highest values amid those reported from other countries. The highest quartz concentration exceeded the Californian Office of Environmental Health Hazard Assessment reference exposure level and was close to the occupational threshold limit values for occupational settings. Moreover, a correlation analysis showed that quartz concentrations were positively correlated with concentrations of pollution parameters PM10, PM2.5, SO2 and NOx, but were negatively correlated with O3 concentration. The results suggest that the airborne quartz particles may potentially pose health risks to the general population of Beijing. Copyright © 2015. Published by Elsevier B.V.

Natural quartz TL property and similarity in Piper nigrum L

International Nuclear Information System (INIS)

Guzman A, S.; Cruz Z, E.; Furetta, C.; Brown, F.; Barboza F, M.

2009-10-01

Quartz is a mineral abundant in nature and can provide information thermoluminescent (TL), and also is located in the mineral fraction of some herbs and spices consumed. It is present the analysis of the TL properties of a sample of natural quartz rock and compared with those obtained from the fraction of Piper nigrum L. poly mineral when they were exposed to 60 Co gamma radiation. The poly minerals of Piper nigrum L. were analyzed by X-ray diffraction, where the quartz was found as a major component. They separated in different particle sizes (10, 53, 74 and 149 μm). The samples were irradiated at relatively low doses (1-500 Gy) and high (0.1-40 kGy) in order to determine the linearity of the TL emission as a function of the dose and the analysis of glow curves. Also there was the fading of the TL signal, the effect of ultra violet light. The reproducibility of the TL signal in the samples indicates that a smaller particle size gives better TL signal. (author)

Analysis of optical bleaching of OSL signal in sediment quartz

International Nuclear Information System (INIS)

Przegiętka, K.R.; Chruścińska, A.

2013-01-01

The aim of this work was to study the effect of the quality of optical bleaching on the results of OSL (Optically Stimulated Luminescence) dating method. The large aliquots of coarse quartz grains extracted from fluvial deposit were used in the study. The poor, medium and good bleaching were simulated in laboratory with help of Blue LED light source in series of experiments. Then the samples were irradiated with a common laboratory dose. The equivalent doses (DE) were measured by the help of standard Single Aliquot Regeneration (SAR) technique, but obtained DE distributions are analyzed in a new way. The method for recognizing and compensating for partial bleaching is proposed. The conclusions for dating sediment quartz samples are presented and discussed. -- Highlights: ► Bleaching experiments on sediment quartz are performed. ► Blue LED light source incorporated in luminescence reader is used. ► New analysis of data measured by standard SAR OSL technique is proposed. ► The results are promising for recognizing and compensating for partial bleaching

Understanding optically stimulated charge movement in quartz and feldspar using time-resolved measurements

International Nuclear Information System (INIS)

Ankjaergaard, C.

2010-02-01

Thermoluminescence (TL) and optically stimulated luminescence (OSL) from quartz and feldspar are widely used in accident dosimetry and luminescence dating. In order to improve already existing methods or to develop new methods towards extending the current limits of the technique, it is important to understand the charge movement within these materials. Earlier studies have primarily focussed on examination of the trap behaviour; however, this only tells half of the story as OSL is a combination of charge stimulation and recombination. By using time-resolved OSL (TR-OSL), one can directly examine the recombination route(s), and thus obtain insight into the other half of the process involved in luminescence emission. This thesis studies the TR-OSL and optically stimulated phosphorescence signals from quartz and feldspars spanning several orders of magnitude in time (few ns to the seconds time scale) in order to identify various charge transport mechanisms in the different time regimes. The techniques employed are time-resolved OSL, continuous-wave OSL, TL, optically stimulated exo-electron (OSE) emission and time-resolved OSE. These different techniques are used in combination with variable thermal or optical stimulation energy. The thesis first delves into three main methodological developments, namely (i) research and development of the equipment for TR-OSL measurements, (ii) finding the best method for multiple-exponential analysis of a TR-OSL curve, and (iii) optimisation of the pulsing configuration for the best separation of quartz OSL from a mixed quarts-feldspar sample. It then proceeds to study the different charge transport mechanisms subsequent to an optical stimulation pulse in quartz and feldspars. The results obtained for quartz conclude that the main lifetime component in quartz represents an excited state lifetime of the recombination centre, and the more slowly decaying components on the millisecond to seconds time scale arise from charge recycling

Understanding optically stimulated charge movement in quartz and feldspar using time-resolved measurements

Energy Technology Data Exchange (ETDEWEB)

Ankjaergaard, C.

2010-02-15

Thermoluminescence (TL) and optically stimulated luminescence (OSL) from quartz and feldspar are widely used in accident dosimetry and luminescence dating. In order to improve already existing methods or to develop new methods towards extending the current limits of the technique, it is important to understand the charge movement within these materials. Earlier studies have primarily focussed on examination of the trap behaviour; however, this only tells half of the story as OSL is a combination of charge stimulation and recombination. By using time-resolved OSL (TR-OSL), one can directly examine the recombination route(s), and thus obtain insight into the other half of the process involved in luminescence emission. This thesis studies the TR-OSL and optically stimulated phosphorescence signals from quartz and feldspars spanning several orders of magnitude in time (few ns to the seconds time scale) in order to identify various charge transport mechanisms in the different time regimes. The techniques employed are time-resolved OSL, continuous-wave OSL, TL, optically stimulated exo-electron (OSE) emission and time-resolved OSE. These different techniques are used in combination with variable thermal or optical stimulation energy. The thesis first delves into three main methodological developments, namely (i) research and development of the equipment for TR-OSL measurements, (ii) finding the best method for multiple-exponential analysis of a TR-OSL curve, and (iii) optimisation of the pulsing configuration for the best separation of quartz OSL from a mixed quarts-feldspar sample. It then proceeds to study the different charge transport mechanisms subsequent to an optical stimulation pulse in quartz and feldspars. The results obtained for quartz conclude that the main lifetime component in quartz represents an excited state lifetime of the recombination centre, and the more slowly decaying components on the millisecond to seconds time scale arise from charge recycling

Linking precious metal enrichment and halogen cycling in mafic magmatic systems: insights from the Rum layered intrusion, NW Scotland

Science.gov (United States)

Kelly, A. P.; O'Driscoll, B.; Clay, P. L.; Burgess, R.

2017-12-01

Layered intrusions host the world's largest known concentrations of the platinum-group elements (PGE). Emphasis has been attached to the role of halogen-bearing fluids in concentrating the precious metals, but whether this occurs at the magmatic stage, or via subsequent metasomatism, is actively debated. One obstacle to progress has been the analytical difficulty of measuring low abundances of the halogens in the cumulate products of layered intrusions. To elucidate the importance of the halogens in facilitating PGE-mineralisation, as well as fingerprint halogen provenance and assess the importance of halogen cycling in mafic magma systems more generally, a suite of samples encompassing different stages of activity of the Palaeogene Rum layered intrusion was investigated. Halogen abundances were measured by neutron irradiation noble gas mass spectrometric analysis, permitting the detection of relatively low (ppm-ppb) abundances of Cl, Br and I in mg-sized samples. The samples include PGE-enriched chromite seams, various cumulates (e.g., peridotites), picrites (approximating the Rum parental magma), and pegmatites representing volatile-rich melts that circulated the intrusion at a late-stage in its solidification history. The new data reveal that PGE-bearing chromite seams contain relatively low Cl concentrations (2-3 ppm), with high molar ratios of Br/Cl and I/Cl (0.005 and 0.009, respectively). The picrites and cumulates have Br/Cl and I/Cl ratios close to sub-continental lithospheric mantle values of approximately 0.0013 and 0.00002, respectively, and thus likely reflect the Rum magma source region. A positive correlation between Cl and Br signifies comparable partitioning behaviour in all samples. However, I is more variable, displaying a positive correlation with Cl for more primitive samples (e.g. picrite and peridotite), and seemingly decoupling from Br and Cl in chromite seams and pegmatites. The relative enrichment of I over Cl in the chromite seams points

Tumour radiosensitization with the halogenated pyrimidines 5'-bromo-and 5'-iododeoxyuridine

Energy Technology Data Exchange (ETDEWEB)

Epstein, A.H.; Cook, J.A.; Goffman, T. (National Cancer Inst., Bethesda, MD (United States)); Glatstein, E. (Texas Univ., Dallas, TX (United States). Southwestern Medical Center)

1993-02-01

The authors review studies of the use of iododeoxyuridine (IdUrd) and bromodeoxyuridine as radiosensitizers and attempt to correlate the clinical outcome for patients treated with radiation and IdUrd with the extent of halogenated pyrimidine cellular uptake and incorporation. (U.K.).

On luminescence lifetimes in quartz

International Nuclear Information System (INIS)

Chithambo, M.L.; Galloway, R.B.

2000-01-01

In this paper we present results of investigations concerning the time dependence of luminescence emission relative to the time of stimulation in quartz. Measurements of time-resolved spectra were performed on a new versatile pulsed light emitting diode system using 525 nm stimulation, an 11 μs duration pulse, a repetition rate of 11 kHz and a 64 μs dynamic range. Effects on luminescence lifetime resulting from sample treatments such as optical stimulation, irradiation, and preheating, are reported

Molecular recognition of halogen-tagged aromatic VOCs at the air-silicon interface.

Science.gov (United States)

Condorelli, Guglielmo G; Motta, Alessandro; Favazza, Maria; Gurrieri, Ettore; Betti, Paolo; Dalcanale, Enrico

2010-01-14

Selective and reversible complexation of halogen-tagged aromatic VOCs by a quinoxaline cavitand-decorated Si surface is demonstrated. The specific host-guest interactions of the Si-bonded receptors are proved to be responsible of the surface recognition properties, while extracavity non specific adsorptions are totally suppressed compared to the bulk material.

High energy halogen atom reactions activated by nuclear transformations. Progress report, February 15, 1979-February 14, 1980

International Nuclear Information System (INIS)

Rack, E.P.

1980-02-01

The program consists of six interrelated areas: (1) Reactions of iodine with alkenes and alkynes activated by radiative neutron capture and isomeric transition in low pressure gaseous systems employing additives and rare gas moderators, high pressure, and liquid systems. Special attention was given to the reactivity of excited complex formation and structural effects of electrophilic iodine attack on various pi-bond systems. (2) The gas-to-condensed phase transition in halogen high energy chemistry. Current interest involves the study of caging effects of an ice lattice on recombination reactions involving neutron-irradiated frozen aqueous solutions of halogenated organic and biochemical solutes in order to learn more about kinetic energy effects, halogen size, solute molecule size, steric effects and hydrogen bonding within an ice lattice cage. (3) Systematics of halogen hot atom reactions. The reactions of /sup 80m/Br, 80 Br, /sup 82m/Br + 82 Br, 82 Br, 82 Br, 128 I, 130 I, and /sup 130m/I + 130 I activated by radiative neutron capture or isomeric transition in hydrocarbons and halo-substituted alkanes in low pressure and high pressure gaseous systems employing additives and rare gas moderators are currently being studied. (4) Mathematical and computer simulation studies of caging events within an ice lattice are being investigated. (5) At Brookhaven National Laboratory, cyclotron-produced chlorine and fluorine hot atoms substitution reactions with molecules possessing a single chiral center are under investigation. (6) The applications of high energy techniques and concepts to neutron activation analysis for trace elements and trace molecule determinations in biological systems was continued

Measurement of fast risetime megampere currents by quartz gauge

International Nuclear Information System (INIS)

Williams, R.R.; McDaniel, D.H.; Stinnett, R.W.

1980-01-01

Quartz gauges have been used on the Sandia National Laboratories Proto II accelerator to measure current in the magnetically insulated transmission line at the 11 TW power level. The accelerator delivers 3.5 MA at 2 x 10 14 A/s in a 40 ns pulse to a 0.0127 m diameter aluminum liner to produce a high density plasma. At this radius and dI/dt levels, the B-dot monitors no longer function for the measurement of load current because the monitor suffers electrical breakdown. Quartz pressure gauges mounted at a radius of 0.0086 m have successfully measured the magnetic pressure due to the load current with nanosecond temporal resolution

Natural sunlight bleaching of the aluminum center in quartz

International Nuclear Information System (INIS)

Lin Min; Yin Gongming; Han Kongyan; Bao Jifei; Liu Jingwei; Jia Li

2007-01-01

The effect of sunlight bleaching on ESR signals from the aluminum center in quartz is reported for two samples of sand-sized quartz, one from a granite and one from a beach sand. The grains were exposed to direct sunlight for periods of time up to 500 h, with bleaching carried out in four different cities in China that are from 50 to 3600 m above sea level. Each sample bleached to the same residual level, ∼55% for the granite and 80% for the beach sand of the initial value after a 200 Gy dose had been given. After 200 h, the bleaching level reached was independent of the height above sea level

Timescales of quartz crystallization and the longevity of the Bishop giant magma body.

Science.gov (United States)

Gualda, Guilherme A R; Pamukcu, Ayla S; Ghiorso, Mark S; Anderson, Alfred T; Sutton, Stephen R; Rivers, Mark L

2012-01-01

Supereruptions violently transfer huge amounts (100 s-1000 s km(3)) of magma to the surface in a matter of days and testify to the existence of giant pools of magma at depth. The longevity of these giant magma bodies is of significant scientific and societal interest. Radiometric data on whole rocks, glasses, feldspar and zircon crystals have been used to suggest that the Bishop Tuff giant magma body, which erupted ~760,000 years ago and created the Long Valley caldera (California), was long-lived (>100,000 years) and evolved rather slowly. In this work, we present four lines of evidence to constrain the timescales of crystallization of the Bishop magma body: (1) quartz residence times based on diffusional relaxation of Ti profiles, (2) quartz residence times based on the kinetics of faceting of melt inclusions, (3) quartz and feldspar crystallization times derived using quartz+feldspar crystal size distributions, and (4) timescales of cooling and crystallization based on thermodynamic and heat flow modeling. All of our estimates suggest quartz crystallization on timescales of magma bodies are ephemeral features that, once established, evolve on millennial timescales. We also suggest that zircon crystals, rather than recording the timescales of crystallization of a large pool of crystal-poor magma, record the extended periods of time necessary for maturation of the crust and establishment of these giant magma bodies.

Radiation-induced conductivity and high-temperature Q changes in quartz resonators

International Nuclear Information System (INIS)

Koehler, D.R.

1981-01-01

While high temperature electrolysis has proven beneficial as a technique to remove interstitial impurities from quartz, reliable indices to measure the efficacy of such a processing step are still under development. The present work is directed toward providing such an index. Two techniques have been investigated - one involves measurement of the radiation induced conductivity in quartz along the optic axis, and the second involves measurement of high temperature Q changes. Both effects originate when impurity charge compensators are released from their traps, in the first case resulting in ionic conduction and in the second case resulting in increased acoustic losses. Radiation induced conductivity measurements have been carried out with a 200 kV, 14 mA x-ray machine producing 5 rads/s. With electric fields of the order of 10 4 V/cm, the noise level in the current measuring system is equivalent to an ionic current generated by quartz impurities in the 1 ppB range. The accuracy of the high temperature ( 300 to 800 0 K) Q -1 measurement technique will be determined. A number of resonators constructed of quartz material of different impurity contents have been tested and both the radiation induced conductivity and the high temperature Q -1 results compared with earlier radiation induced frequency and resonator resistance changes. 10 figures

Defect studies in quartz: Composite nature of the blue and UV emissions

Energy Technology Data Exchange (ETDEWEB)

Martini, Marco, E-mail: m.martini@unimib.it [Dipartimento di Scienza dei Materiali, Università degli Studi di Milano Bicocca, via R. Cozzi 55, I-20125 Milano (Italy); INFN, Sezione di Milano Bicocca, Piazza della Scienza 1, I-20126 Milano (Italy); Fasoli, Mauro; Villa, Irene [Dipartimento di Scienza dei Materiali, Università degli Studi di Milano Bicocca, via R. Cozzi 55, I-20125 Milano (Italy)

2014-05-01

Quartz is an extremely diffused natural luminescence dosimeter. Thanks to the presence of traps and luminescence centres, its TSL and OSL (Thermally and Optically Stimulated Luminescence) properties have been extensively exploited. Quartz is then used for archaeological and geological dating and is one of the most useful materials for accident dosimetry. Many luminescence emissions are known to be present in the OSL and TSL of quartz. Three main emission bands are always reported, as the red, blue and UV bands, centred at around 650, 470, and 360–380 nm, respectively. Although the assignment of the luminescence emissions to specific defect centres in quartz is still undefined, a thorough analysis of the radioluminescence emissions and their response to irradiation and thermal treatments turned out to be very useful in understanding many features. Specifically, the presence of the same emission bands in natural and synthetic quartz and their dependence on the presence of extrinsic impurities is a common characteristic. The main impurities involve Al ions substituting Si ones and charge compensated by nearby either alkali ions, H{sup +}, or a hole. The emission spectra dynamics evidenced in our experiment confirm the role of Al-related centres in the luminescence properties of quartz. From the measurements presented in this paper the composite nature of the “blue” emission is confirmed. Two bands labelled as A at 2.5 eV and B at 2.8 eV contribute to the emission in this region, their behaviour being different as a function of irradiation. More complex is the picture in the UV region, where, besides the already detected C and D bands at 3.4 eV and 3.9 eV, respectively, two further emissions have been detected at 3.1 eV and 3.7 eV. Despite both the 3.4 eV and the 3.7 eV bands are shown to be affected by thermal treatments, the annealing temperature dependence of their intensity is markedly different. In fact, whereas the C band intensity, at 3.4 eV, increases

Defect studies in quartz: Composite nature of the blue and UV emissions

International Nuclear Information System (INIS)

Martini, Marco; Fasoli, Mauro; Villa, Irene

2014-01-01

Quartz is an extremely diffused natural luminescence dosimeter. Thanks to the presence of traps and luminescence centres, its TSL and OSL (Thermally and Optically Stimulated Luminescence) properties have been extensively exploited. Quartz is then used for archaeological and geological dating and is one of the most useful materials for accident dosimetry. Many luminescence emissions are known to be present in the OSL and TSL of quartz. Three main emission bands are always reported, as the red, blue and UV bands, centred at around 650, 470, and 360–380 nm, respectively. Although the assignment of the luminescence emissions to specific defect centres in quartz is still undefined, a thorough analysis of the radioluminescence emissions and their response to irradiation and thermal treatments turned out to be very useful in understanding many features. Specifically, the presence of the same emission bands in natural and synthetic quartz and their dependence on the presence of extrinsic impurities is a common characteristic. The main impurities involve Al ions substituting Si ones and charge compensated by nearby either alkali ions, H + , or a hole. The emission spectra dynamics evidenced in our experiment confirm the role of Al-related centres in the luminescence properties of quartz. From the measurements presented in this paper the composite nature of the “blue” emission is confirmed. Two bands labelled as A at 2.5 eV and B at 2.8 eV contribute to the emission in this region, their behaviour being different as a function of irradiation. More complex is the picture in the UV region, where, besides the already detected C and D bands at 3.4 eV and 3.9 eV, respectively, two further emissions have been detected at 3.1 eV and 3.7 eV. Despite both the 3.4 eV and the 3.7 eV bands are shown to be affected by thermal treatments, the annealing temperature dependence of their intensity is markedly different. In fact, whereas the C band intensity, at 3.4 eV, increases after

Optically stimulated exoelectron emission processes in quartz: comparison of experiment and theory

DEFF Research Database (Denmark)

Pagonis, V.; Ankjærgaard, Christina; Murray, A.S.

2009-01-01

Recent experiments have demonstrated that it is possible to measure optically stimulated exoelectron emission (OSE) signals simultaneously with optically stimulated luminescence (OSL) from quartz samples. These experiments provide valuable information on the charge movement in quartz grains. Two...... data yield a value of χ1.2 eV for the work function of quartz. The experimental temperature dependence of the OSE signals is interpreted on the basis of a photo-thermostimulated (PTSEE) process involving the main OSL trap at 320 °C; this process takes place with a thermal assistance energy estimated...... at W(0.29±0.02) eV. Good quantitative agreement is obtained between theory and experiment by assuming a thermal broadening of the thermal depletion factor for the OSL traps, described by a Gaussian distribution of energies....

Solution and solid-phase halogen and C-H hydrogen bonding to perrhenate.

Science.gov (United States)

Massena, Casey J; Riel, Asia Marie S; Neuhaus, George F; Decato, Daniel A; Berryman, Orion B

2015-01-28

(1)H NMR spectroscopic and X-ray crystallographic investigations of a 1,3-bis(4-ethynyl-3-iodopyridinium)benzene scaffold with perrhenate reveal strong halogen bonding in solution, and bidentate association in the solid state. A nearly isostructural host molecule demonstrates significant C-H hydrogen bonding to perrhenate in the same phases.

Degradation of halogenated aliphatic compounds by the ammonia- oxidizing bacterium Nitrosomonas europaea.

OpenAIRE

Vannelli, T; Logan, M; Arciero, D M; Hooper, A B

1990-01-01

Suspensions of Nitrosomonas europaea catalyzed the ammonia-stimulated aerobic transformation of the halogenated aliphatic compounds dichloromethane, dibromomethane, trichloromethane (chloroform), bromoethane, 1,2-dibromoethane (ethylene dibromide), 1,1,2-trichloroethane, 1,1,1-trichloroethane, monochloroethylene (vinyl chloride), gem-dichloroethylene, cis- and trans-dichloroethylene, cis-dibromoethylene, trichloroethylene, and 1,2,3-trichloropropane, Tetrachloromethane (carbon tetrachloride),...

Perspectives on halogen bonding and other sigma-hole interactions: Lex parsimoniae (Occam's Razor)

Czech Academy of Sciences Publication Activity Database

Politzer, P.; Riley, Kevin Eugene; Bulat, F. A.; Murray, J. S.

2012-01-01

Roč. 998, SI (2012), s. 2-8 ISSN 2210-271X Institutional research plan: CEZ:AV0Z40550506 Keywords : halogen bonding * alpha-Hole bonding * hydrogen bonding * electrostatics /polarization * dispersion * electrostatic potentials Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.139, year: 2012

PATTERN RECOGNITION STUDIES OF HALOGENATED ORGANIC COMPOUNDS USING CONDUCTING POLYMER SENSOR ARRAYS. (R825323)

Science.gov (United States)

Direct measurement of volatile and semivolatile halogenated organic compounds of environmental interest was carried out using arrays of conducting polymer sensors. Mathematical expressions of the sensor arrays using microscopic polymer network model is described. A classical, non...

Trace element characterisation and purification of quartz powder of Indian origin

International Nuclear Information System (INIS)

Dash, K.; Thangavel, S.; Dhavile, S.M.; Sahayam, A.C.; Chaurasia, S.C.

2002-11-01

Analytical methodologies for the trace element characterisation and purification of quartz powder of Indian origin have been described. Metallic impurities (11 elements) in ∼700 quartz samples have been analysed using different instrumental techniques. The values are cross-validated by American and British analytical laboratories. A special multi channel vapour phase digestion (MCVPD) chamber has been designed to reduce the process blank levels for the determination of ultra trace impurities in high purity silicon matrix. In this vessel 21 samples can be digested at a time in a period of 8 hrs. at normal pressure and low temperature (∼ 80 degC). Analytical methodologies for the determination of non-metals (phosphorus, boron and chloride) at very low levels <1 ppm) have also been described. A highly cost effective, single step, room temperature purification procedure is developed based on chemical leaching. Around 300 raw quartz powders (3-4N) from various mines have been purified to 5N pure ( optical grade ). (author)

Recommendations concerning an interim annual individual exposure limit for respirable quartz

International Nuclear Information System (INIS)

Stocker, H.; Horvath, F.J.; Napier, W.

1983-07-01

This paper presents AECB staff recommendations on the desirability of an annual individual occupational exposure limit for respirable quartz and on the magnitude of this limit, for uranium miners. Justifications are presented for the magnitude of this suggested limit for respirable quartz, drawing on experience gained in Ontario uranium and non-uranium mines and on that in other countries. The suggestion is made that an exposure limit be set for an interim period in order that additional information on the adequacy of the magnitude of the limit may be acquired. To complement the suggested exposure limit, it is proposed that a co-existing control program of action levels, to be triggered at various respirable quartz concentrations, be set up. It is the contention of this paper that the degree of protection afforded to individuals by the suggested exposure limit would be equivalent to the time-weighted average threshold limit value derived from recommendations, based on group average exposures, of the American Conference of Governmental Industrial Hygienists

Difference in luminescence sensitivity of coarse-grained quartz from deserts of northern China

International Nuclear Information System (INIS)

Zheng, C.X.; Zhou, L.P.; Qin, J.T.

2009-01-01

The luminescence sensitivity of coarse quartz extracted from desert sands in northern China was investigated. In general, the western deserts' samples are shown to be less sensitive than samples from the eastern deserts with respect to both OSL and the 110 deg. C TL peak. However, internal scatter among different aliquots of the same sample is observed for these two signals, which have already been normalized by weight. Laboratory dosing/bleach experiments indicate that earth surface processes, such as repeated burial and transportation can cause the sensitivity change and suggest that they may be responsible for the internal scatter. An intrinsic property of quartz was explored via the luminescence response to thermal activation to a maximum temperature of 700 deg. C. The thermal activation curves obtained with quartz from western and central deserts are similar, except one sample from Gurbantungut, which follows the pattern of eastern samples. The differences in quartz luminescence sensitivity exhibited by OSL/110 deg. C TL sensitivity and response to thermal activation are in accordance with the published results of geochemical studies.

Quartz: structural and thermodynamic analyses across the α ↔ β transition with origin of negative thermal expansion (NTE) in β quartz and calcite

Energy Technology Data Exchange (ETDEWEB)

Antao, Sytle M.

2016-04-01

The temperature variation,T, of the crystal structure of quartz, SiO₂, from 298 to 1235 K was obtained with synchrotron powder X-ray diffraction data and Rietveld structure refinements. The polymorphic transformation fromP3₂21 (low-T, α quartz) toP6₂22 (high-T, β quartz) occurs at a transition temperature,T_tr= 847 K. TheTvariations of spontaneous strains and several structural parameters are fitted to an order parameter,Q, using Landau theory. The change in Si atom coordinate, Si_x, givesT_tr-T_c= 0.49 K, which indicates an α ↔ β transition that is weakly first order and nearly tricritical in character (Q⁴∝T). Strains give higherT_tr-T_cvalues (≃ 7 K). Other fitted parameters are the oxygen O_zcoordinate, Si—Si distance, Si—O—Si and φ angles, and intensity of the (111) reflection,I₁₁₁. In α quartz, the Si—Si distance increases withTbecause of cation repulsion, so the Si—O—Si angle increases (and φ decreases) and causes the thermal expansion of the framework structure that consists of corner-sharing distorted rigid SiO₄tetrahedra. The Si—Si distances contract withTand cause negative thermal expansion (NTE) in β quartz because of increasing thermal librations of the O atom in the Si—O—Si linkage that occur nearly perpendicular to the Si—Si contraction. In calcite, CaCO₃, the short Ca—Ca distance expands withT, but the next-nearest Ca—Ca distance, which is of equal length to theaaxis, contracts withTand causes NTE along

Study on the dynamics of halogen elements in the agro-environment and these element`s deficiency, toxicity and environmental hazards by the application of the neutron activation analysis method

Energy Technology Data Exchange (ETDEWEB)

Yuita, Kouichi [National Inst. of Agro-Environmental Sciences, Tsukuba, Ibaraki (Japan)

1998-03-01

A neutron activation analysis method is an accurate and highly sensitive method for analyzing halogen elements (iodine, bromine and chlorine) except fluorine. It is unsubstitutable and valuable method especially for iodine (including radioactive {sup 129}I) and bromine which are present at lower levels. Halogen elements have high chemical and physiological activities and move widely in the environment. As a result, deficiency and an excess of halogen elements in plants and animals have occurred and artificial halogen compounds have caused environmental pollution in wide areas. We efficiently utilized the neutron activation analysis method and an activable tracer method to obtain valuable findings which contribute to the clarification of and measures against these actual problems and which are also concerned with the occurrence, distribution and migration of halogen elements in the environment, especially agricultural and forestry ecosystems in space and in time. (author)

Direct Growth of III-Nitride Nanowire-Based Yellow Light-Emitting Diode on Amorphous Quartz Using Thin Ti Interlayer

KAUST Repository

Prabaswara, Aditya; Min, Jung-Wook; Zhao, Chao; Janjua, Bilal; Zhang, Daliang; Albadri, Abdulrahman M.; Alyamani, Ahmed Y.; Ng, Tien Khee; Ooi, Boon S.

2018-01-01

.6 V, on an amorphous quartz substrate. We achieved ~ 40% transparency across the visible wavelength while maintaining electrical conductivity by employing a TiN/Ti interlayer on quartz as a translucent conducting layer. The nanowire-on-quartz LED emits

Low molecular weight halogenated hydrocarbons (LMHHs) in Mediterranean sea water: Preliminary observations

International Nuclear Information System (INIS)

Elder, D.L.; Villeneuve, J.P.; Harvey, G.R.

1976-01-01

Halogenated organic compounds containing 1-3 carbon atoms are among the most extensively produced synthetic chemicals. Within this group of compounds are solvents such as chloroform, carbon tetrachloride, trichloroethane and the chlorofluoro carbons or freons which are used as refrigerants and aerosol sprays. Once produced many of these compounds are eventually released to the environment

Rearrangements in the halogenation of tetraalkylethylenes with N-halosuccinimides and tert-butyl hypochlorite

NARCIS (Netherlands)

Meijer, E.W.; Kellogg, R.M.; Wynberg, H.

1982-01-01

The reaction of N-halosuccinimides and Me3COCl with tetraalkylethylenes involves halo-cation addn. to the double bond in a fast reaction, followed by abstraction of an allylic proton, resulting in a double bond shift. Homoallylic halogenation occurs in tetraalkylethylenes which can not undergo a

Hydrogenated and halogenated blue phosphorene as Dirac materials: A first principles study

Energy Technology Data Exchange (ETDEWEB)

Sun, Minglei [School of Mechanical Engineering, Southeast University, Nanjing, Jiangsu 211189 (China); Wang, Sake [Department of Physics, Southeast University, Nanjing, Jiangsu 210096 (China); Yu, Jin [School of Materials Science and Engineering, Southeast University, Nanjing, Jiangsu 211189 (China); Tang, Wencheng, E-mail: 101000185@seu.edu.cn [School of Mechanical Engineering, Southeast University, Nanjing, Jiangsu 211189 (China)

2017-01-15

Highlights: • The fully hydrogenated and halogenated blue phosphorenes are 2D Dirac materials. • The Dirac cone in fluorinated and iodinated blue phosphorenes lies exactly at the Fermi level. • The mass density of hydrogenated and fluorinated blue phosphorenes is rather small. - Abstract: Using first-principles calculations, we systematically investigate the structures and electronic properties of fully hydrogenated and halogenated blue phosphorene (P{sub 2}X{sub 2}). All these systems possess Dirac cone at high-symmetry K point, which are mainly contributed by P s p{sub x} p{sub y} orbitals. The Dirac cone in P{sub 2}F{sub 2} and P{sub 2}I{sub 2} systems lies exactly at the Fermi level. Formation energy analysis denotes that all the systems are energetically stable except P{sub 2}I{sub 2}. The mass density for P{sub 2}H{sub 2} and P{sub 2}F{sub 2} systems is rather small. Our calculations proposed that these systems, especially P{sub 2}F{sub 2} system, have great potential applications in future nanoelectronics.

Kinetics of the coesite to quartz transformation

Science.gov (United States)

Mosenfelder, J.L.; Bohlen, S.R.

1997-01-01

The survival of coesite in ultrahigh-pressure (UHP) rocks has important implications for the exhumation of subducted crustal rocks. We have conducted experiments to study the mechanism and rate of the coesite ??? quartz transformation using polycrystalline coesite aggregates, fabricated by devitrifying silica glass cylinders containing 2850H/106 Si at 1000??C and 3.6 GPa for 24h. Conditions were adjusted following synthesis to transform the samples at 700-1000??C at pressures 190-410 MPa below the quartz-coesite equilibrium boundary. Reaction proceeds via grain-boundary nucleation and interface-controlled growth, with characteristic reaction textures remarkably similar to those seen in natural UHP rocks. We infer that the experimental reaction mechanism is identical to that in nature, a prerequisite for reliable extrapolation of the rate data. Growth rates obtained by direct measurement differ by up to two orders of magnitude from those estimated by fitting a rate equation to the transformation-time data. Fitting the rates to Turnbull's equation for growth therefore yields two distinct sets of parameters with similar activation energies (242 or 269 kJ/mol) but significantly different pre-exponential constants. Extrapolation based on either set of growth rates suggests that coesite should not be preserved on geologic time scales if it reaches the quartz stability field at temperatures above 375-400??C. The survival of coesite has previously been linked to its inclusion in strong phases, such as garnet, that can sustain a high internal pressure during decompression. Other factors that may play a crucial role in preservation are low fluid availability - possibly even less than that of our nominally "dry" experiments - and the development of transformation stress, which inhibits nucleation and growth. These issues are discussed in the context of our experiments as well as recent observations from natural rocks. ?? 1997 Elsevier Science B.V.

A parametric comparative study of electrocoagulation and coagulation using ultrafine quartz suspensions.

Science.gov (United States)

Kiliç, Mehtap Gülsün; Hoşten, Cetin; Demirci, Sahinde

2009-11-15

This paper attempts to compare electrocoagulation using aluminum anodes and stainless steel cathodes with conventional coagulation by aluminum sulfate dosing on aqueous suspensions of ultrafine quartz. Several key parameters affecting the efficiency of electrocoagulation and coagulation were investigated with laboratory scale experiments in search of optimal parameter values. Optimal values of the parameters were determined on the basis of the efficiency of turbidity removal from ultrafine quartz suspensions. The parameters investigated in the study were suspension pH, electrical potential, current density, electrocoagulation time, and aluminum dosage. A comparison between electrocoagulation and coagulation was made on the basis of total dissolved aluminum, revealing that electrocoagulation and coagulation were equally effective at the same aluminum dosage for the removal of quartz particles from suspensions. Coagulation, however, was more effective in a wider pH range (pH 6-9) than electrocoagulation which yielded optimum effectiveness in a relatively narrower pH range around 9, where, in both methods, these pH values corresponded to near-zero zeta potentials of quartz particles. Furthermore, experimental results confirmed that electrocoagulation could display some pH buffering capacity. The kinetics of electrocoagulation was very fast (<10 min) in approaching a residual turbidity, which could be modeled with a second-order rate equation.

Evaluation of wear rate of dental composites polymerized by halogen or LED light curing units

Directory of Open Access Journals (Sweden)

Alaghehmand H.

2006-08-01

Full Text Available Background and Aim: Sufficient polymerization is a critical factor to obtain optimum physical properties and clinical efficacy of resin restorations. The aim of this study was to evaluate wear rates of composite resins polymerized by two different systems Light Emitting Diodes (LED to and Halogen lamps. Materials and Methods: In this laboratory study, 20 specimens of A3 Tetric Ceram composite were placed in brass molds of 2*10*10 mm dimensions and cured for 40 seconds with 1 mm distance from surface. 10 specimens were cured with LED and the other 10 were cured with Halogen unit. A device with the ability to apply force was developed in order to test the wear of composites. After storage in distilled water for 10 days, the specimens were placed in the wear testing machine. A chrome cobalt stylus with 1.12 mm diameter was applied against the specimens surfaces with a load of 2 kg. The weight of each samples before and after 5000, 10000, 20000, 40000, 80000 and 120000 cycles was measured using an electronic balance with precision of 10-4 grams. Data were analyzed using t test and paired t test. P0.05. Conclusion: Based on the results of this study, LED and halogen light curing units resulted in a similar wear rate in composite resin restorations.

Timescales of Quartz Crystallization and the Longevity of the Bishop Giant Magma Body

Energy Technology Data Exchange (ETDEWEB)

Gualda, Guilherme A.R.; Pamukcu, Ayla S.; Ghiorso, Mark S.; Anderson, Jr. , Alfred T.; Sutton, Stephen R.; Rivers, Mark L. (OFM Res.); (Vanderbilt); (UC)

2013-04-08

Supereruptions violently transfer huge amounts (100 s-1000 s km{sup 3}) of magma to the surface in a matter of days and testify to the existence of giant pools of magma at depth. The longevity of these giant magma bodies is of significant scientific and societal interest. Radiometric data on whole rocks, glasses, feldspar and zircon crystals have been used to suggest that the Bishop Tuff giant magma body, which erupted {approx}760,000 years ago and created the Long Valley caldera (California), was long-lived (>100,000 years) and evolved rather slowly. In this work, we present four lines of evidence to constrain the timescales of crystallization of the Bishop magma body: (1) quartz residence times based on diffusional relaxation of Ti profiles, (2) quartz residence times based on the kinetics of faceting of melt inclusions, (3) quartz and feldspar crystallization times derived using quartz+feldspar crystal size distributions, and (4) timescales of cooling and crystallization based on thermodynamic and heat flow modeling. All of our estimates suggest quartz crystallization on timescales of <10,000 years, more typically within 500-3,000 years before eruption. We conclude that large-volume, crystal-poor magma bodies are ephemeral features that, once established, evolve on millennial timescales. We also suggest that zircon crystals, rather than recording the timescales of crystallization of a large pool of crystal-poor magma, record the extended periods of time necessary for maturation of the crust and establishment of these giant magma bodies.

Effect of Water Glass Modification on Its Viscosity and Wettability of Quartz Grains

Directory of Open Access Journals (Sweden)

A. Kmita

2012-09-01

Full Text Available The aim of the present study was to develop a modifier for water glass. The method of thermal generation of metal oxide nanoparticleswas adapted and used in the research. Nanoparticles of ZnO from the thermal decomposition of basic zinc carbonate were used. A methodfor the modifier introduction was developed, and the effect of modifier content and organic solvent type on the physico-chemicalproperties of binder (viscosity and quartz wettability was determined. Binder viscosity was examined from the flow curves plotted with the help of a RHEOTEST 2 rotational rheometer equipped with proper software. Quartz wettability was determined examining timerelated changes in the value of the contact angle in a quartz-binder system, until full stabilisation of the angle value has been achieved.Binder modification was carried out on sodium water glass designated as R"145". The water glass modifiers were suspensions of ZnOnanoparticles in propanol and methanol at a fixed concentration of c = 0.3 M and with the size of nanoparticles comprised in a range of. Water glass modification with the suspensions of ZnO nanoparticles in methanol and propanol showed the effect ofmodifier on the water glass viscosity and quartz wettability. This effect depends on the type of alcohol used. The ZnO suspension inpropanol (alcohol with a longer hydrocarbon chain affects more strongly the viscosity of binder and quartz wettability than the methanol suspension.

Effect of Water Glass Modification on Its Viscosity and Wettability of Quartz Grains

Directory of Open Access Journals (Sweden)

Kmita A.

2012-09-01

Full Text Available The aim of the present study was to develop a modifier for water glass. The method of thermal generation of metal oxide nanoparticles was adapted and used in the research. Nanoparticles of ZnO from the thermal decomposition of basic zinc carbonate were used. A method for the modifier introduction was developed, and the effect of modifier content and organic solvent type on the physico-chemical properties of binder (viscosity and quartz wettability was determined. Binder viscosity was examined from the flow curves plotted with the help of a RHEOTEST 2 rotational rheometer equipped with proper software. Quartz wettability was determined examining timerelated changes in the value of the contact angle in a quartz-binder system, until full stabilisation of the angle value has been achieved. Binder modification was carried out on sodium water glass designated as R"145". The water glass modifiers were suspensions of ZnO nanoparticles in propanol and methanol at a fixed concentration of c = 0.3 M and with the size of nanoparticles comprised in a range of . Water glass modification with the suspensions of ZnO nanoparticles in methanol and propanol showed the effect of modifier on the water glass viscosity and quartz wettability. This effect depends on the type of alcohol used. The ZnO suspension in propanol (alcohol with a longer hydrocarbon chain affects more strongly the viscosity of binder and quartz wettability than the methanol suspension

Amplifier Module for 260-GHz Band Using Quartz Waveguide Transitions

Science.gov (United States)

Padmanabhan, Sharmila; Fung, King Man; Kangaslahti, Pekka P.; Peralta, Alejandro; Soria, Mary M.; Pukala, David M.; Sin, Seth; Samoska, Lorene A.; Sarkozy, Stephen; Lai, Richard

2012-01-01

Packaging of MMIC LNA (monolithic microwave integrated circuit low-noise amplifier) chips at frequencies over 200 GHz has always been problematic due to the high loss in the transition between the MMIC chip and the waveguide medium in which the chip will typically be used. In addition, above 200 GHz, wire-bond inductance between the LNA and the waveguide can severely limit the RF matching and bandwidth of the final waveguide amplifier module. This work resulted in the development of a low-loss quartz waveguide transition that includes a capacitive transmission line between the MMIC and the waveguide probe element. This capacitive transmission line tunes out the wirebond inductance (where the wire-bond is required to bond between the MMIC and the probe element). This inductance can severely limit the RF matching and bandwidth of the final waveguide amplifier module. The amplifier module consists of a quartz E-plane waveguide probe transition, a short capacitive tuning element, a short wire-bond to the MMIC, and the MMIC LNA. The output structure is similar, with a short wire-bond at the output of the MMIC, a quartz E-plane waveguide probe transition, and the output waveguide. The quartz probe element is made of 3-mil quartz, which is the thinnest commercially available material. The waveguide band used is WR4, from 170 to 260 GHz. This new transition and block design is an improvement over prior art because it provides for better RF matching, and will likely yield lower loss and better noise figure. The development of high-performance, low-noise amplifiers in the 180-to- 700-GHz range has applications for future earth science and planetary instruments with low power and volume, and astrophysics array instruments for molecular spectroscopy. This frequency band, while suitable for homeland security and commercial applications (such as millimeter-wave imaging, hidden weapons detection, crowd scanning, airport security, and communications), also has applications to

FTIR measurements of OH in deformed quartz and feldspars of the South Tibetan Detachment, Greater Himalaya

Science.gov (United States)

Jezek, L.; Law, R. D.; Jessup, M. J.; Searle, M. P.; Kronenberg, A. K.

2017-12-01

OH absorption bands due to water in deformed quartz and feldspar grains of mylonites from the low-angle Lhotse Detachment (of the South Tibetan Detachment System, Rongbuk Valley north of Mount Everest) have been measured by Fourier Transform Infrared (FTIR) Spectroscopy. Previous microstructural studies have shown that these rocks deformed by dislocation creep at high temperature conditions in the middle crust (lower - middle amphibolite facies), and oxygen isotope studies suggest significant influx of meteoric water. OH absorption bands at 3400 cm-1 of quartz mylonites from the footwall of the Lhotse Detachment Fault are large, with the character of the molecular water band due to fluid inclusions in milky quartz. Mean water contents depend on structural position relative to the core of the Lhotse Detachment, from 1000 ppm (OH/106 Si) at 420 m below the fault to 11,350 (+/-1095) ppm near its center. The gradient in OH content shown by quartz grains implies influx of meteoric water along the Lhotse Detachment from the Tibetan Plateau ground surface to middle crustal depths, and significant fluid penetration into the extruding Himalayan slab by intergranular, permeable fluid flow processes. Feldspars of individual samples have comparable water contents to those of quartz and some are wetter. Large water contents of quartz and feldspar may have contributed to continued deformation and strain localization on the South Tibetan Detachment System. Dislocation creep in quartz is facilitated by water in laboratory experiments, and the water contents of the Lhotse fault rocks are similar to (and even larger than) water contents of quartz experimentally deformed during water weakening. Water contents of feldspars are comparable to those of plagioclase aggregates deformed experimentally by dislocation and diffusion creep under wet conditions.

A STUDY OF THE PRESSURE SOLUTION AND DEFORMATION OF QUARTZ CRYSTALS AT HIGH pH AND UNDER HIGH STRESS

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JUNG-HAE CHOI

2013-02-01

Full Text Available Bentonite is generally used as a buffer material in high-level radioactive waste disposal facilities and consists of 50% quartz by weight. Quartz strongly affects the behavior of bentonite over very long periods. For this reason, quartz dissolution experiment was performed under high-pressure and high-alkalinity conditions based on the conditions found in a high-level radioactive waste disposal facility located deep underground. In this study, two quartz dissolution experiments were conducted on 1 quartz beads under low-pressure and high-alkalinity conditions and 2 a single quartz crystal under high-pressure and high-alkalinity conditions. Following the experiments, a confocal laser scanning microscope (CLSM was used to observe the surfaces of experimental samples. Numerical analyses using the finite element method (FEM were also performed to quantify the deformation of contact area. Quartz dissolution was observed in both experiments. This deformation was due to a concentrated compressive stress field, as indicated by the quartz deformation of the contact area through the FEM analysis. According to the numerical results, a high compressive stress field acted upon the neighboring contact area, which showed a rapid dissolution rate compared to other areas of the sample.

Control of aliphatic halogenated DBP precursors with multiple drinking water treatment processes: Formation potential and integrated toxicity.

Science.gov (United States)

Zhang, Yimeng; Chu, Wenhai; Yao, Dechang; Yin, Daqiang

2017-08-01

The comprehensive control efficiency for the formation potentials (FPs) of a range of regulated and unregulated halogenated disinfection by-products (DBPs) (including carbonaceous DBPs (C-DBPs), nitrogenous DBPs (N-DBPs), and iodinated DBPs (I-DBPs)) with the multiple drinking water treatment processes, including pre-ozonation, conventional treatment (coagulation-sedimentation, pre-sand filtration), ozone-biological activated carbon (O 3 -BAC) advanced treatment, and post-sand filtration, was investigated. The potential toxic risks of DBPs by combing their FPs and toxicity values were also evaluated. The results showed that the multiple drinking water treatment processes had superior performance in removing organic/inorganic precursors and reducing the formation of a range of halogenated DBPs. Therein, ozonation significantly removed bromide and iodide, and thus reduced the formation of brominated and iodinated DBPs. The removal of organic carbon and nitrogen precursors by the conventional treatment processes was substantially improved by O 3 -BAC advanced treatment, and thus prevented the formation of chlorinated C-DBPs and N-DBPs. However, BAC filtration leads to the increased formation of brominated C-DBPs and N-DBPs due to the increase of bromide/DOC and bromide/DON. After the whole multiple treatment processes, the rank order for integrated toxic risk values caused by these halogenated DBPs was haloacetonitriles (HANs)≫haloacetamides (HAMs)>haloacetic acids (HAAs)>trihalomethanes (THMs)>halonitromethanes (HNMs)≫I-DBPs (I-HAMs and I-THMs). I-DBPs failed to cause high integrated toxic risk because of their very low FPs. The significant higher integrated toxic risk value caused by HANs than other halogenated DBPs cannot be ignored. Copyright © 2017. Published by Elsevier B.V.

Nature sunlight bleaching of Ti center ESR signal in quartz

International Nuclear Information System (INIS)

Yin Gongming; Liu Chunru; Li Jianping; Fang Jiahu; Gao Lu; Lin Min

2009-01-01

Quartz grains were extracted from granite. Bleaching was carried out in four different area chosen for their different altitudes (Beijing, Yinchuan, Germu, Lhasa), in order to observe their behavior under different intensities of the UV (Ultra violet) component of sunlight. The result of our experiments indicate that the Ti center signal is totally bleachable by the natural sunlight and show that the Ti center signal was reduced to zero after about 128 h in Beijing and after 56 h for Lhasa. We can speculate that different intensity of the UV component of sunlight lead to different minimal time necessary to obtain the total bleaching of the quartz sample. (authors)

Crystallochemical analysis of rare-earth halogen-containing π-complexes

International Nuclear Information System (INIS)

Blatova, O.A.; Blatov, V.A.; Serezhkin, V.N.

2001-01-01

Dependence of the size of Ln atom action in coordination polyhedrons LnC n X m (X = F, Cl, Br) on its nature, coordination number, oxidation state and number of Ln-X bonds, was studied using 96 halogen-containing π-complexes of rare earth and yttrium (Ln) by way of example. A method of estimating ligand sizes in coordination sphere using the Voronoi-Dirichlet molecular polyhedrons was suggested. Influence of the ligands sizes on stability of π-complexes and presence of specific interactions in their structure was analyzed [ru

Uraniferous quartz-pebble conglomerates in South Africa

International Nuclear Information System (INIS)

von Backstroem, J.W.

1981-01-01

The purpose of this paper is to give a short background statement summarizing data on the Dominion Reef Group, the Witwatersrand Supergroup, and the Ventersdorp Contact Reef, with particular reference to the close relationship of gold and uranium with sedimentary features as well as the mineralization, conditions of deposition, and the nature of the quartz-pebble conglomerates

The quartz crystal microbalance in soft matter research fundamentals and modeling

CERN Document Server

Johannsmann, Diethelm

2014-01-01

This book describes the physics of the second-generation quartz crystal microbalance (QCM), a fundamental method of analysis for soft matter at interfaces.From a device for measuring film thickness in vacuum, the quartz crystal microbalance (QCM) has in the past two decades evolved into a versatile instrument for analyzing soft matter at solid/liquid and solid/gas interfaces that found applications in diverse fields including the life sciences, material science, polymer research and electrochemistry. As a consequence of this success, the QCM is now being used by scientists with a wide variety

Impacts of halogen additions on mercury oxidation, in a slipstream selective catalyst reduction (SCR), reactor when burning sub-bituminous coal.

Science.gov (United States)

Cao, Yan; Gao, Zhengyang; Zhu, Jiashun; Wang, Quanhai; Huang, Yaji; Chiu, Chengchung; Parker, Bruce; Chu, Paul; Pant, Wei-Ping

2008-01-01

This paper presents a comparison of impacts of halogen species on the elemental mercury (Hg(0)) oxidation in a real coal-derived flue gas atmosphere. It is reported there is a higher percentage of Hg(0) in the flue gas when burning sub-bituminous coal (herein Powder River Basin (PRB) coal) and lignite, even with the use of selective catalytic reduction (SCR). The higher Hg(0)concentration in the flue gas makes it difficult to use the wet-FGD process for the mercury emission control in coal-fired utility boilers. Investigation of enhanced Hg(0) oxidation by addition of hydrogen halogens (HF, HCl, HBr, and HI) was conducted in a slipstream reactor with and without SCR catalysts when burning PRB coal. Two commercial SCR catalysts were evaluated. SCR catalyst no. 1 showed higher efficiencies of both NO reduction and Hg(0) oxidation than those of SCR catalyst no. 2. NH3 addition seemed to inhibit the Hg(0) oxidation, which indicated competitive processes between NH3 reduction and Hg(0) oxidation on the surface of SCR catalysts. The hydrogen halogens, in the order of impact on Hg(0) oxidation, were HBr, HI, and HCl or HF. Addition of HBr at approximately 3 ppm could achieve 80% Hg(0) oxidation. Addition of HI at approximately 5 ppm could achieve 40% Hg(0) oxidation. In comparison to the empty reactor, 40% Hg(0) oxidation could be achieved when HCl addition was up to 300 ppm. The enhanced Hg(0) oxidation by addition of HBr and HI seemed not to be correlated to the catalytic effects by both evaluated SCR catalysts. The effectiveness of conversion of hydrogen halogens to halogen molecules or interhalogens seemed to be attributed to their impacts on Hg(0) oxidation.

The Cherenkov correlated timing detector: beam test results from quartz and acrylic bars

International Nuclear Information System (INIS)

Kichimi, H.; Sugaya, Y.; Yamaguchi, H.; Yoshimura, Y.; Kanda, S.; Olsen, S.; Ueno, K.; Varner, G.; Bergfeld, T.; Bialek, J.; Lorenc, J.; Palmer, M.; Rudnick, G.; Selen, M.; Auran, T.; Boyer, V.; Honscheid, K.; Tamura, N.; Yoshimura, K.; Lu, C.; Marlow, D.; Mindas, C.; Prebys, E.; Asai, M.; Kimura, A.; Hayashi, S.

1996-01-01

Several prototypes of a Cherenkov correlated timing (CCT) detector have been tested at the KEK-PS test beam line. We describe the results for Cherenkov light yields and timing characteristics from quartz and acrylic bar prototypes. A Cherenkov angle resolution is found to be 15 mrad at a propagation distance of 100 cm with a 2 cm thick quartz bar prototype. (orig.)

Pressure solution of minerals in quartz-type buffer materials

International Nuclear Information System (INIS)

Erlstroem, M.

1986-12-01

Two samples, pure quartz sand and a sand-bentonite (10%) mixture, were tested under conditions of high pressure (200 bar) and temperature (115 0 C). The experiment was carried out over a period of 70 days. A series of thin slides were prepared on a resin embedded sample at the end of the test period. A microscopical study was performed as to obtain data concerning the effects of pressure and temperature. It showed that no pressure solution had taken place in the pure quartz sand. However, the individual grains had been severely fractured, thus causing significant internal sedimentation. The mixed sample showed that the clay component coated the quartz grains and significantly decreased the effect of stress in the grains by having a cushioning effect. Relative grain movement was facilitated by the clay, by which the grains rotated and slipped into stable positions with large contact areas and low contact stresses. This probably minimized pressure solution. However, a few contact regions indicated the presence of precipitated silica. The investigation shows no definite evidence of pressure solution after an experiment duration of 70 days. Since the effect of solution may be time dependent at the applied temperature, it is recommended that further experiments be conducted at higher effective and porewater pressures but still at 115 0 C. (orig.)

Analytical expressions for time-resolved optically stimulated luminescence experiments in quartz

International Nuclear Information System (INIS)

Pagonis, V.; Lawless, J.; Chen, R.; Chithambo, M.L.

2011-01-01

Optically stimulated luminescence (OSL) signals can be obtained using a time-resolved optical stimulation (TR-OSL) method, also known as pulsed OSL. During TR-OSL measurements, the stimulation and emission of luminescence are experimentally separated in time using short light pulses. This paper presents analytical expressions for the TR-OSL intensity observed during and after such a pulse in quartz experiments. The analytical expressions are derived using a recently published kinetic model which describes thermal quenching phenomena in quartz samples. In addition, analytical expressions are derived for the concentration of electrons in the conduction band during and after the TR-OSL pulse, and for the maximum signals attained during optical stimulation of the samples. The relevance of the model for dosimetric applications is examined, by studying the dependence of the maximum TR-OSL signals on the degree of initial trap filling, and also on the probability of electron retrapping into the dosimetric trap. Analytical expressions are derived for two characteristic times of the TR-OSL mechanism; these times are the relaxation time for electrons in the conduction band, and the corresponding relaxation time for the radiative transition within the luminescence center. The former relaxation time is found to depend on several experimental parameters, while the latter relaxation time depends only on internal parameters characteristic of the recombination center. These differences between the two relaxation times can be explained by the presence of localized and delocalized transitions in the quartz sample. The analytical expressions in this paper are shown to be equivalent to previous analytical expressions derived using a different mathematical approach. A description of thermal quenching processes in quartz based on AlO 4 - /AlO 4 defects is presented, which illustrates the connection between the different descriptions of the luminescence process found in the literature

Analytical investigations of thermoluminescence glow curve on quartz for luminescence dating

International Nuclear Information System (INIS)

Kim, K.B.; Hong, D.G.

2015-01-01

Investigations of bleaching and thermoluminescence (TL) response to radiation dose of quartz are importance in luminescence dating. Although such research has been extensively carried out for various types of quartz, most work was performed on the basis of TL intensity integrated for a particular temperature range on the glow curve, without any peak separation. In this study we investigated bleaching by a blue light stimulation and radiation dose behaviour for separated TL glow peaks of quartz, which are thermally stable, by using the computerized glow curve deconvolution (CGCD) method combined with the T_m–T_s_t_o_p method. The T_m–T_s_t_o_p method indicates that the glow curve of quartz is the superposition of at least seven components (P1–P7) in the temperature range between room temperature and 450 °C. A bleaching experiment for four thermally stable glow peaks (P4–P7) using a blue light stimulation revealed that the bleaching rate of peak P4 exhibits three different exponential decays, whereas the peaks P5, P6 and P7 are bleached with two different exponential decays. After bleaching of 12 h, the TL intensity of peaks P4, P5, P6 and P7 were reduced to approximately 6%, 16%, 26% and 68% of the initial value, respectively. Additionally, in a study of the radiation dose response of the four thermally stable glow peaks, all peaks have a similar pattern, which are well fitted by a single saturating exponential function. - Highlights: • We studied the physical characteristics of the separated TL glow peaks on quartz. • The kinetic parameters of each separated glow peak are evaluated by a CGCD method. • The separated peaks were bleached with two or three exponential decays. • The dose responses for the separated peaks showed a similar growth curve.

Retrospective dosimetry: dose evaluation using unheated and heated quartz from a radioactive waste storage building

International Nuclear Information System (INIS)

Jain, M.; Boetter-Jensen, L.; Murray, A.S.; Jungner, H.

2002-01-01

In the assessment of dose received from a nuclear accident, considerable attention has been paid to retrospective dosimetry using heated materials such as household ceramics and bricks. However, unheated materials such as mortar and concrete are more commonly found in industrial sites and particularly in nuclear installations. These materials contain natural dosemeters such as quartz, which usually is less sensitive than its heated counterpart. The potential of quartz extracted from mortar is a wall of a low-level radioactive-waste storage facility containing distributed sources of 60 Co and 13C s has been investigated. Dose-depth profiles based on small aliquots and single grains from the quartz extracted from the mortar samples are reported here. These are compared with results from heated quartz and polymineral fine grains extracted from an adjacent brick, and the integrated dose recorded by environmental TLDs. (author)

Retrospective dosimetry: Dose evaluation using unheated and heated quartz from a radioactive waste storage building

DEFF Research Database (Denmark)

Jain, M.; Bøtter-Jensen, L.; Murray, A.S.

2002-01-01

In the assessment of dose received from a nuclear accident, considerable attention has been paid to retrospective dosimetry using heated materials such as household ceramics and bricks. However, unheated materials such as mortar and concrete are more commonly found in industrial sites......-137 has been investigated. Dose-depth profiles based on small aliquots and single grains from the quartz extracted from the mortar samples are reported here. These are compared with results from heated quartz and polymineral fine grains extracted from an adjacent brick, and the integrated dose...... and particularly in nuclear installations. These materials contain natural dosemeters Such as quartz. which usually is less sensitive than its heated counterpart. The potential of quartz extracted from mortar in a wall of a low-level radioactive-waste storage facility containing distributed sources of Co-60 and Cs...

Halogen bonding from a hard and soft acids and bases perspective: investigation by using density functional theory reactivity indices.

Science.gov (United States)

Pinter, Balazs; Nagels, Nick; Herrebout, Wouter A; De Proft, Frank

2013-01-07

Halogen bonds between the trifluoromethyl halides CF(3)Cl, CF(3)Br and CF(3)I, and dimethyl ether, dimethyl sulfide, trimethylamine and trimethyl phosphine were investigated using Pearson's hard and soft acids and bases (HSAB) concept with conceptual DFT reactivity indices, the Ziegler-Rauk-type energy-decomposition analysis, the natural orbital for chemical valence (NOCV) framework and the non-covalent interaction (NCI) index. It is found that the relative importance of electrostatic and orbital (charge transfer) interactions varies as a function of both the donor and acceptor molecules. Hard and soft interactions were distinguished and characterised by atomic charges, electrophilicity and local softness indices. Dual-descriptor plots indicate an orbital σ hole on the halogen similar to the electrostatic σ hole manifested in the molecular electrostatic potential. The predicted high halogen-bond-acceptor affinity of N-heterocyclic carbenes was evidenced in the highest complexation energy for the hitherto unknown CF(3) I·NHC complex. The dominant NOCV orbital represents an electron-density deformation according to a n→σ*-type interaction. The characteristic signal found in the reduced density gradient versus electron-density diagram corresponds to the non-covalent interaction between contact atoms in the NCI plots, which is the manifestation of halogen bonding within the NCI theory. The unexpected C-X bond strengthening observed in several cases was rationalised within the molecular orbital framework. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterisation of blue-light stimulated luminescence components in different quartz samples: Implications for dose measurement

DEFF Research Database (Denmark)

Jain, M.; Murray, A.S.; Bøtter-Jensen, L.

2003-01-01

-aliquot dose-evaluation protocols seem to be relatively free of complications when applied to quartz dominated by the fast OSL component coming from 325degreesC TL region, but this may not be true for quartz in which other components are more significant. An adequate understanding of how different OSL...... results from measurement of (a) sensitisation, (b) thermal stability, (c) recuperation, and (d) infrared response as a function of stimulation temperature from 3 different samples of sedimentary quartz selected on the basis of relative OSL contribution from different blue light stimulated linearly...

Developing Effective Separation of Feldspar and Quartz While Recycling Tailwater by HF Pretreatment

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Weiqing Wang

2018-04-01

Full Text Available The effect of hydrofluoric acid (HF pretreatment on flotation of feldspar and quartz using dodecylamine (DDA as collector was investigated by micro-flotation, zeta potential, pyrene fluorescence spectroscopy, attenuated total reflection flourier transformed infrared spectroscopy (ATR-FTIR, scanning electron microscope (SEM, X-ray photoelectron spectroscopy (XPS and bench scale flotation. The micro-flotation tests revealed that there was little difference in the flotation of feldspar and quartz at pH 2, using H2SO4 as pH regulator. After HF pretreatment, the floatability of feldspar significantly increased while the floatability of quartz showed no change. HF pretreatment resulted in leaching of SiO2 and enrichment of Na, K and Al on the feldspar surface. Consequently, the negative surface charge of feldspar increased at pH 2, which allowed for the flotation separation of the feasible minerals. This took place via an increased electrostatic adsorption between DDA and Na, K, Al on the feldspar surface, which effectively increased its hydrophobicity and as a result, improved the floatability of feldspar. An alternative process which exhibited effective separation of quartz and feldspar while recycling the tailwater from the flotation was proposed.

Optically continuous silcrete quartz cements of the St. Peter Sandstone: High precision oxygen isotope analysis by ion microprobe

Science.gov (United States)

Kelly, Jacque L.; Fu, Bin; Kita, Noriko T.; Valley, John W.

2007-08-01

A detailed oxygen isotope study of detrital quartz and authigenic quartz overgrowths from shallowly buried (ratio by laser fluorination, resulting in an average δ 18O of 10.0 ± 0.2‰ (1SD, n = 109). Twelve thin sections were analyzed by CAMECA-1280 ion microprobe (6-10 μm spot size, analytical precision better than ±0.2‰, 1SD). Detrital quartz grains have an average δ 18O of 10.0 ± 1.4‰ (1SD, n = 91) identical to the data obtained by laser fluorination. The ion microprobe data reveal true variability that is otherwise lost by homogenization of powdered samples necessary for laser fluorination. Laser fluorination uses samples that are one million times larger than the ion microprobe. Whole rock (WR) samples from the 53 rocks were analyzed by laser fluorination, giving δ 18O between 9.8‰ and 16.7‰ ( n = 110). Quartz overgrowths in thin sections from 10 rocks were analyzed by ion microprobe and average δ 18O = 29.3 ± 1.0‰ (1SD, n = 161). Given the similarity, on average, of δ 18O for all detrital quartz grains and for all quartz overgrowths, samples with higher δ 18O(WR) values can be shown to have more cement. The quartz cement in the 53 rocks, calculated by mass balance, varies from outlier at 33 vol.% cement. Eolian samples have an average of 11% cement compared to marine samples, which average 4% cement. Two models for quartz cementation have been investigated: high temperature (50-110 °C) formation from ore-forming brines related to Mississippi Valley Type (MVT) mineralization and formation as silcretes at low temperature (10-30 °C). The homogeneity of δ 18O for quartz overgrowths determined by ion microprobe rules out a systematic regional variation of temperature as predicted for MVT brines and there are no other known heating events in these sediments that were never buried to depths >1 km. The data in this study suggest that quartz overgrowths formed as silcretes in the St. Peter Sandstone from meteoric water with δ 18O values of -10

Pyrimidine and halogenated pyrimidines near edge x-ray absorption fine structure spectra at C and N K-edges: experiment and theory

International Nuclear Information System (INIS)

Bolognesi, P.; O'Keeffe, P.; Ovcharenko, Y.; Coreno, M.; Avaldi, L.; Feyer, V.; Plekan, O.; Prince, K. C.; Zhang, W.; Carravetta, V.

2010-01-01

The inner shell excitation of pyrimidine and some halogenated pyrimidines near the C and N K-edges has been investigated experimentally by near edge x-ray absorption fine structure spectroscopy and theoretically by density functional theory calculations. The selected targets, 5-Br-pyrimidine, 2-Br-pyrimidine, 2-Cl-pyrimidine, and 5-Br-2-Cl-pyrimidine, allow the effects of the functionalization of the pyrimidine ring to be studied either as a function of different halogen atoms bound to the same molecular site or as a function of the same halogen atom bound to different molecular sites. The results show that the individual characteristics of the different spectra of the substituted pyrimidines can be rationalized in terms of variations in electronic and geometrical structures of the molecule depending on the localization and the electronegativity of the substituent.

Guiding effect of bent macroscopic quartz tube for high current electron beam

International Nuclear Information System (INIS)

Zhang Mingwu; Chen Jing; Wu Yehong; Yang Bian; Wang Wei; Xue Yingli; Yu Deyang; Cai Xiaohong

2012-01-01

By using an incident electron beam with the high current and high energy, the guiding effect of the bent macroscopic quartz tube for the electron beam has been investigated. The angular distributions of outgoing electrons depending on the current and energy of incident electrons were measured. The dependences of electron transmitted fraction on energy and current of incident electrons are also shown. As the incident electron energy increasing, the electron transmitted fraction increases, but it decreases while the incident electron current increasing. The results have been compared with the present data. This work presents, the process of guiding electrons is essentially different from that of guiding highly charged ions, the guiding electron beam was caused by both elastic and inelastic collisions between electrons and inner walls of quartz tube, rather than self-organized charging effect on the surface of inner wall of quartz tube. (authors)

DISPERSION AND SORPTION CHARACTERISTICS OF URANIUM IN THE ZEOLITE-QUARTZ MIXTURE AS BACKFILL MATERIAL IN THE RADIOACTIVE WASTE REPOSITORY

Directory of Open Access Journals (Sweden)

Herry Poernomo

2010-06-01

Full Text Available The experiment of sorption and dispersion characteristics of uranium in the zeolite-quartz mixture as candidate of raw material of backfill material in the radioactive waste repository has been performed. The objective is to know the effect of zeolite and quartz grain size on the zeolite-to-quartz weight ratio that gives porosity (ε, permeability (K, and dispersivity (α of uranium in the zeolite-quartz mixture as backfill material. The experiment was carried out by fixed bed method in the column filled by the zeolite-quartz mixture with zeolite-to-quartz weight percent ratio of 100/0, 80/20, 60/40, 40/60, 20/80, 0/100 wt. % in the water saturated condition flowed by uranyl nitrate solution of 500 ppm concentration (Co as uranium simulation which was leached from immobilized radioactive waste in the repository. The concentration of uranium in the effluents represented as Ct were analyzed by spectrophotometer Corning Colorimeter 253 every 15 minutes, then using Co and Ct uranium dispersivity (α in the backfill material was determined. The experiment data shown that 0.196 mm particle size of zeolite and 0.116 mm particle size of quartz on the zeolite-to-quartz weight ratio of 60/40 wt. % with ε = 0.678, K = 3.345x10-4 cm/second, and α = 0.759 cm can be proposed as candidate of raw material of backfill material in the radioactive waste repository.   Keywords: backfill material, quartz, radioactive waste, zeolite

Luminescence lifetimes in natural quartz annealed beyond its second phase inversion temperature

International Nuclear Information System (INIS)

Chithambo, M.L.

2015-01-01

The influence of annealing, irradiation dose, preheating and measurement temperature on luminescence lifetimes has been studied in quartz annealed at 1000 °C. The measurements were supplemented by studies on quartz annealed at 900 and 800 °C. Lifetimes increase with dose as well as with temperature and duration of annealing between 800 and 1000 °C. Preheating produces the same effect. The changes are accounted for in terms of hole-transfer from the non-radiative luminescence centre to and between radiative centres. The influence of measurement temperature on lifetimes depends on whether the stimulation is carried out from ambient to 200 °C or otherwise. This result is unlike that in quartz annealed at or below 500 °C where lifetimes are independent of the direction of heating. In particular, lifetimes decrease monotonically when measurements are made from 20 to 200 °C but not when recorded from 200 to 20 °C. The latter produces a pattern resembling that in quartz annealed up to 500 °C. The results are concluded as evidence of thermal effects on separate luminescence centres. In support of this, different values of the activation energy for thermal quenching were found for each supposed luminescence centre. The change of the corresponding luminescence intensity with temperature is also qualitatively consistent with this notion. - Highlights: • Luminescence lifetimes in natural quartz annealed beyond its second phase inversion temperature is reported. • Lifetimes increase with dose, annealing between 800 and 1000 °C, and preheating. • Lifetimes under stimulation temperature are affected by direction of heating. • Changes are accounted for in terms of hole-transfer luminescence centres.

U-Th-Mo mineralisation in quartz syenite from Maturigiri-Dhurakantagiri, West Garo Hills District, Meghalaya, India

International Nuclear Information System (INIS)

Basu, A.N.; Sharma, G.S.; Varma, H.M.; Dhana Raju, R.; Dougall, N.K.; Raju, B.N.V.

1987-01-01

At Maturigiri and Dhurkantagiri, mineralised coarse-grained quartz syenite bodies (up to 10x2m) occur as intrusives along the NNW-SSE trending joints in the gneissic country rock. Mineralogically, the quartz syenite is characterised by over 50 per cent K-feldspar, lesser plagioclase, quartz, mica, garnet and chlorite, together with accessory uraninite, monazite, molybdenite and pyrite. Uraninite occurs as euhedral to subhedral inclusions and mineralisation is syngenetic. Two types of monazite, Th-poor and Th-rich, are present. Molybdenite occurs as veins along fractures and appears to be of late hydrothermal origin. The mineralogical and textural features suggest that quartz syenite was formed from a residual melt of granitic magma of crustal origin. (author). 7 refs., 9 figs

OH-point defects in quartz in B- and Li-bearing systems and their application to pegmatites

Science.gov (United States)

Baron, M. A.; Stalder, R.; Konzett, J.; Hauzenberger, C. A.

2015-01-01

OH incorporation in quartz in Al-, B- and Li-bearing systems (granitic systems containing tourmaline or spodumene) was studied experimentally in order to investigate the effect of pressure, temperature and chemical impurities on the generation of OH-defects. High-pressure experiments were carried out at pressures between 5 and 25 kbar and temperatures between 800 and 900 °C, and OH-contents in quartz were calculated from IR absorption spectra measured on oriented quartz crystals. IR absorption features were assigned to impurity substitutions, such as AlOH (3,420, 3,379 and 3,315 cm-1) and BOH (3,595 cm-1), LiOH (3,483 cm-1), and hydrogarnet substitution (4H)Si defects (3,583 cm-1). Results indicate a negative correlation of incorporated Al-specific OH-defect content versus pressure (630 ± 130 wt ppm H2O at 5 kbar to 102 ± 6 wt ppm H2O at 25 kbar), but no clear correlation of B-specific OH-defects with pressure. In runs initially containing spodumene, virtually OH-free quartzes were observed at pressures ≥10 kbar, where impurity cations compensate each other forming an anhydrous eucryptite-defect component. In contrast, at 5 kbar, both Li- ad Al-specific OH-defects are observed (corresponding to 470 ± 75 wt ppm H2O). Results from this study may therefore be used to monitor formation conditions of quartz in terms of pressure and trace metal saturation of the crystallizing petrological system. IR spectra obtained from natural quartz grains from a tourmaline-bearing pegmatite exhibit B- and Al-related OH-bands. The B-related OH-band is also exhibited in quartz from a tourmaline + spodumene-bearing pegmatite. Li- and Al-related OH-bands, however, are subordinate or not observed at all in the spodumene-bearing system, which suggests that OH-vibrations do not reflect absolute Li-contents in quartz due to efficient coupled substitution involving Al. Data from experimental runs and natural specimens indicate that the B-related OH-band can be used as a rough proxy for

Manufacturing polycrystalline pellets of natural quartz for applications in thermoluminescence dosimetry

Energy Technology Data Exchange (ETDEWEB)

Carvalho Junior, Alvaro Barbosa de; Khoury, Helen Jamil [Federal University of Pernambuco (UFPE), Recife, PE (Brazil). Department of Nuclear Energy; Barros, Thiago Fernandes; Guzzo, Pedro Luiz [Federal University of Pernambuco (UFPE), Recife, PE (Brazil). Department of Mining Engineering

2012-07-15

This paper describes the manufacturing process of quartz-pellets and shows their potential use as thermoluminescence dosimeters (TLD) for those applications where low-levels of ionising radiation are present. Two batches of cold-pressed pellets were produced and their resistance were evaluated by vibration tests and weight-loss measurements. The batch manufactured with 75 Multiplication-Sign 150 Micro-Sign m particles showed enough resistance to be employed as TLD. The dosimetric properties of the 310 Degree-Sign C peak appearing in the glow curves of these pellets were characterized together with commercial TLD-100 units using {gamma}- and X-ray beams with different energies. The uncertainties related to reproducibility and stability of the TL signal were better than 10%. The sensitivity and the linearity of the TL response of quartz-pellets were better than that measured for TLD-100 for doses ranging from 0.5 to 200mGy. The energy dependence of the quartz-pellets was higher than that of TLD-100 but it cannot be considered a restriction to their use in clinical procedures and industrial applications. (author)

Saturation spectroscopy of calcium atomic vapor in hot quartz cells with cold windows

Science.gov (United States)

Vilshanskaya, E. V.; Saakyan, S. A.; Sautenkov, V. A.; Murashkin, D. A.; Zelener, B. B.; Zelener, B. V.

2018-01-01

Saturation spectroscopy of calcium atomic vapor was performed in hot quartz cells with cold windows. The Doppler-free absorption resonances with spectral width near 50 MHz were observed. For these experiments and future applications long-lived quartz cells with buffer gas were designed and made. A cooling laser for calcium magneto-optical trap will be frequency locked to the saturation resonances in the long-lived cells.

Testing the application of quartz and feldspar luminescence dating to MIS 5 Japanese marine deposits

DEFF Research Database (Denmark)

Thiel, Christine; Tsukamoto, Sumiko; Tokuyasu, Kayoko

2015-01-01

The applicability of both quartz and feldspar luminescence dating was tested on twenty-five samples from a marine succession now forming a coastal cliff at Oga Peninsula, Honshu Island, Japan. The quartz optically stimulated luminescence (OSL) signal shows thermal instability and linear modulated...

Degradation of halogenated aliphatic compounds by the ammonia- oxidizing bacterium Nitrosomonas europaea.

Science.gov (United States)

Vannelli, T; Logan, M; Arciero, D M; Hooper, A B

1990-01-01

Suspensions of Nitrosomonas europaea catalyzed the ammonia-stimulated aerobic transformation of the halogenated aliphatic compounds dichloromethane, dibromomethane, trichloromethane (chloroform), bromoethane, 1,2-dibromoethane (ethylene dibromide), 1,1,2-trichloroethane, 1,1,1-trichloroethane, monochloroethylene (vinyl chloride), gem-dichloroethylene, cis- and trans-dichloroethylene, cis-dibromoethylene, trichloroethylene, and 1,2,3-trichloropropane, Tetrachloromethane (carbon tetrachloride), tetrachloroethylene (perchloroethylene), and trans-dibromoethylene were not degraded. PMID:2339874

21 CFR 700.15 - Use of certain halogenated salicylanilides as ingredients in cosmetic products.

Science.gov (United States)

2010-04-01

... ingredients in cosmetic products. 700.15 Section 700.15 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) COSMETICS GENERAL Requirements for Specific Cosmetic Products § 700.15 Use of certain halogenated salicylanilides as ingredients in cosmetic products. (a...

A quartz crystal microbalance dew point sensor without frequency measurement

Science.gov (United States)

Wang, Guohua; Zhang, Weishuo; Wang, Shuo; Sun, Jinglin

2014-11-01

This work deals with the design of a dew point sensor based on Quartz Crystal Microbalance (QCM) without measuring the frequency. This idea is inspired by the fact that the Colpitts oscillation circuit will stop oscillating when the QCM works in the liquid media. The quartz crystal and the electrode are designed through the finite element simulation and the stop oscillating experiment is conducted to verify the sensibility. Moreover, the measurement result is calibrated to approach the true value. At last a series of dew points at the same temperature is measured with the designed sensor. Results show that the designed dew point sensor is able to detect the dew point with the proper accuracy.

Fission track dating of authigenic quartz in red weathering crusts of carbonate rocks in Guizhou province

International Nuclear Information System (INIS)

Liu Xiuming; Wang Shijie; Zhang Feng

2004-01-01

The Cenozoic evolution history of Guizhou Province, which is located on the southeastern flank of the Qinghai-Tibet Plateau, is unclear because of the lack of sedimentation records. The red weathering crusts widespread on the Yunnan-Guizhou Plateau may bear critical information about their evolution history. This work firstly determined the ages of four red weathering crusts in eastern, central and northern Guizhou. The material used in fission track dating is well-crystallized quartz occurring in many in-situ weathering crusts of carbonate rocks. The results showed that the fission track ages of quartz vary over a wide range from 1 Ma to 25 Ma in the four profiles, significantly younger than the ages of Triassic and Cambrian parent rocks. In combination with the regionally geological evolution history during the period from 25 Ma to 1 Ma, the ages of quartz can exclude the possibility that the origin of quartz has nothing to do with primary clastic minerals in parent rocks, authigenesis during diagenesis and hydrothermal precipitation or replacement by volcanic activities. It is deduced that the well-crystallized quartz was precipitated from Si-rich weathering fluids during weathering processes of carbonate rocks. The recorded ages of quartz from the four profiles are consistent with the episodes of planation surfaces on the Qinghai-Tibet Plateau, the stages of red soil in the tropics of South China, the tectonically stable periods in Guizhou, and the ages of weathering in other parts of the world during the Cenozoic era. That is to say, the ages of authigenic quartz dated by the fission track method are well feasible and credible. (authors)

INFLUENCE OF QUARTZ CERAMICS SINGLE-STAGE PROCESSING BY GEL-FORMING WATER SOLUTIONS ON ITS STRENGTH

Directory of Open Access Journals (Sweden)

S. K. Evstropiev

2014-09-01

Full Text Available The main research results of the influence of quartz ceramics processing by silicon- and aluminum-containing gel- forming water solutions on its durability and porosity are given. Aqueous-alcoholic solutions based on tetraethoxysilane (TEOS, Si(C2H5O4 with additives of aluminum nitrate are proposed for impregnation of porous quartz ceramics samples. Ceramic samples are being impregnated with solutions at the room temperature for 12 minutes. After impregnation they are being exposed to drying at the room temperature for 24 hours and heat treatment in the electric muffle furnace. The made experiments show that impregnation of quartz ceramics porous samples by gel-forming solutions leads to durability growth of not burned samples by 6-7 times even without additional heat treatment. High-temperature heat treatment of previously impregnated ceramic samples leads to decomposition of aluminum nitrate and removal of fossils, and also to hardening of the formed additional bonds between material particles. It considerably improves strength characteristics of quartz ceramics as well. Thus, the possibility of considerable hardening of porous quartz ceramics and stability growth of its strength properties by preliminary impregnation of silicon- and aluminum-bearing gel-forming solutions even without additional heat treatment is experimentally shown. It is revealed that impregnation of porous quartz ceramic samples by these solutions leads only to insignificant reduction of porosity of samples. Subsequent heat treatment of the impregnated porous ceramic samples at the temperatures, equal to 900-1200oC, results in additional significant increase in their mechanical durability.

Ab initio study of weakly bound halogen complexes: RX⋯PH3.

Science.gov (United States)

Georg, Herbert C; Fileti, Eudes E; Malaspina, Thaciana

2013-01-01

Ab initio calculations were employed to study the role of ipso carbon hybridization in halogenated compounds RX (R=methyl, phenyl, acetyl, H and X=F, Cl, Br and I) and its interaction with a phosphorus atom, as occurs in the halogen bonded complex type RX⋯PH3. The analysis was performed using ab initio MP2, MP4 and CCSD(T) methods. Systematic energy analysis found that the interaction energies are in the range -4.14 to -11.92 kJ mol(-1) (at MP2 level without ZPE correction). Effects of electronic correlation levels were evaluated at MP4 and CCSD(T) levels and a reduction of up to 27% in interaction energy obtained in MP2 was observed. Analysis of the electrostatic maps confirms that the PhCl⋯PH3 and all MeX⋯PH3 complexes are unstable. NBO analysis suggested that the charge transfer between the moieties is bigger when using iodine than bromine and chlorine. The electrical properties of these complexes (dipole and polarizability) were determined and the most important observed aspect was the systematic increase at the dipole polarizability, given by the interaction polarizability. This increase is in the range of 0.7-6.7 u.a. (about 3-7%).

Parent and halogenated polycyclic aromatic hydrocarbons in rice and implications for human health in China

International Nuclear Information System (INIS)

Ding Chao; Ni Honggang; Zeng Hui

2012-01-01

Rice is the staple food for approximate two thirds of the Chinese population. However, human exposure to parent and halogenated polycyclic aromatic hydrocarbons (PAHs) via rice consumption is still not clear for Chinese people so far. The goals of this work are to assess human exposure to PAHs and halogenated PAHs (HPAHs) via rice ingestion and the cancer risk for Chinese population. 16 PAHs and eight HPAHs were determined in rice samples collected from 18 provinces in China. In general terms, the general population in China was exposed to higher levels of PAHs via rice ingestion in comparison to that via cereals for other countries. The cancer risk values induced by exposure to PAHs and HPAHs for male and female on each age group were between the priority risk level (10 −4 ) and the acceptable risk level (10 −6 ). Children faced the highest cancer risk, followed by adolescents and adults. - Highlights: ► Dietary exposure to PAHs via rice ingestion for Chinese population was higher than that via cereals in other countries. ► The cancer risk induced by PAHs and HPAHs intakes via rice consumption were between 10 −6 and 10 −4 . ► Children faced the highest cancer risk, followed by adolescents and adults. ► Given all exposure routes were considered, the real cancer risk for Chinese people would be greater. - Human exposure to parent and halogenated PAHs via rice ingestion and the cancer risk for Chinese population were assessed.

Neutron peak velocity measurements at the National Ignition Facility (NIF) using novel quartz detectors

Science.gov (United States)

Grim, Gary; Eckart, Mark; Hartouni, Edward; Hatarik, Robert; Moore, Alastair; Root, Jaben; Sayre, Daniel; Schlossberg, David; Waltz, Cory

2017-10-01

In mid-2017 the NIF implemented quartz based neutron time-of-flight (nToF) detectors which have a faster and narrower impulse response function (IRF) relative to traditional scintillator detectors. In this presentation we report on comparisons between fusion neutron first moments as measured by quartz and scintillator based detectors using DT layered implosions at the NIF. We report on the change in precision presaged by the quartz converter and quantify the change in both in shot, line-of-site velocity variability. as well as, shot-to-shot variation. Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344. LLNL-ABS-734511-DRAFT.

Cathodoluminescence investigations on quartz cement in the sandstones of Khabour Formation from Iraqi Kurdistan Region, Northern Iraq

Science.gov (United States)

Omer, Muhamed F.; Friis, Henrik

2014-03-01

The Ordovician deltaic to shallow marine Khabour Formation in Northern Iraq consists mainly of sandstone with minor siltstone and interbedded shale. The sandstones are pervasively cemented by quartz that resulted in very little preserved primary porosity. Cathodoluminescence and petrographic studies showed that the silica cementation occurred in five successive phases which can be distinguished by their luminescence pattern. The precipitations of two phases have predated the major compaction process while the other phases are younger. The successive phases represent a sequence of changes in silica supply which were classified as very early and early, derived from dissolved biogenic silica that precipitated as opal/microquartz, possibly pre-compactional and of non-luminescent quartz overgrowth type. This was followed by phases whose silica supply derived from pressure solution of quartz, dissolution of feldspar, and hydrothermal fluids related to major thrust fault event. These successive quartz cement phases showed an increase in luminescence and the development of complicated zonation pattern in late-stage quartz cementation.

R and D on Radiation Hard Active Media Based on Quartz Plates

CERN Document Server

Onel, Yasar

2014-01-01

The need for radiation-hard active media in particle detectors is prominently dictated by the future colliders and the future operations of the Large Hadron Collider. The areas of implementation range from calorimetry to beamline instrumentation to specialized forward detectors e.g. luminosity monitors. In this context, we developed the idea of utilizing quartz plates with various surface coating properties as the active medium for such detectors. Plain quartz is a pure Cerenkov radiator which has quite limited photostatistics. In order to improve the efficiency of the photodetection, various methods were investigated including radiation hard wavelength shifters, p-terphenyl or 4pct gallium doped zinc oxide. The readout options include direct coupling of the photodetector to the quartz plate, or fibers. We have studied various geometries and readout options and constructed calorimeter prototypes. Here we report on the results of the previous tests, and the recent developments, which enable several factors of ...

Characterization of hydrothermal green quartz produced by gamma radiation

Energy Technology Data Exchange (ETDEWEB)

Enokihara, Cyro T.; Rela, Paulo R., E-mail: cteiti@ipen.br, E-mail: prela06@yahoo.com.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Schultz-Güttler, Rainer A., E-mail: rainersgut@gmail.com [Universidade de Sao Paulo (USP), Sao Paulo, SP (Brazil). Instituto de Geociencias

2015-07-01

A specific variety of quartz showing a green color in nature or induced artificially by radiation gamma ({sup 60}Co) is quite rare. Only two occurrences are known today, where this type of quartz can be found: Canada, at the Thunder Bay Amethyst Mine, Ontario and Brazil, at widely scattered geode occurrences along a 600 km stretch from Quarai at Brazils southern most tip to Uberlandia in Minas Gerais. These two occurrences have been formed by strong hydrothermal activities.That way much quartz crystals showed a very fast growth history facilitating the formation of growth defects (twinning, small angle tilting, mosaic growth, striations) and the uptake of water in form of micro inclusions, molecular water, silanol (Si-OH) and OH. In the present work the material analyzed is from hydrothermal regimes found in intrusions of basaltic rocks located in the Rio Grande do Sul state. To characterize these materials, colored green by gamma rays, analyses by ICP, electron microscopy, water loss techniques and UV-VIS or NIR-FTIR spectroscopic measurements have been made. Silanol complexes are formed, which by radiation due to gamma rays form the color center NBOHC (Non-bonding Oxygen Hole Center), showing absorption between 590 to 620 nm, responsible for the green color. The water content with up to 3200 ppm by weight exceeds the amount of charge balancing cations (Fe, Al, Li). There is no correlation between water content and cations as in other color varieties. (author)

Quartz exposure, retention, and early silicosis in sheep.

Science.gov (United States)

Bégin, R; Dufresne, A; Cantin, A; Possmayer, F; Sébastien, P; Fabi, D; Bilodeau, G; Martel, M; Bisson, D; Pietrowski, B

1989-05-01

The purposes of this study were (1) to investigate the chronology of events in cellular and biochemical changes thought to be important in the development of silicosis, (2) to relate these to changes in lung function and radiograph, and (3) to evaluate the relation of quartz exposure and retention to individual response leading to early silicosis. Thirty-six sheep were exposed by repeated intratracheal infusion at 10-day intervals to 100 mg Minusil-5 in 100 ml saline (Si group), and 10 sheep were exposed at the same intervals to 100 ml saline (control). All sheep were investigated at 3-month intervals by chest radiograph, lung function, and lung lavage. At month 9, chest radiograph score of parenchymal opacities was significantly increased at 2.8 +/- 0.6 versus 0.4 +/- 0.4 in the Si group (p less than .05), establishing early radiologic silicosis. Lung function was significantly altered with reduction in lung compliance, vital capacity, and diffusion capacity (p less than .05). Lung lavage cellularity revealed significant increase in total cells (X 2.5), macrophages (X3), and neutrophils (X3). Albumin in BAL remained at the control level. Fibronectin production was significantly increased, as was the fibroblast growth activity, without significant change in procollagen 3 at this early stage of disease. Total phospholipids were significantly elevated in the Si-exposed sheep, and the profile demonstrated an increase in all the phospholipid components. Spontaneous release of hydrogen peroxide by alveolar cells was not increased, but in the presence of phorbol myristate acetate (PMA) higher levels of peroxide were found in the quartz-exposed sheep (p less than .05). The cellular and biochemical alterations of lung lavage preceded other changes. At month 12, there were good correlations (r greater than .49, p less than .001) between parameters evaluating related phenomena but poor correlations between measurements evaluating different aspects of the disorder. To

Isomorphous Crystals from Diynes and Bromodiynes Involved in Hydrogen and Halogen Bonds

Directory of Open Access Journals (Sweden)

Pierre Baillargeon

2016-04-01

Full Text Available Isomorphous crystals of two diacetylene derivatives with carbamate functionality (BocNH-CH2-diyne-X, where X = H or Br have been obtained. The main feature of these structures is the original 2D arrangement (as supramolecular sheets or walls in which the H bond and halogen bond have a prominent effect on the whole architecture. The two diacetylene compounds harbor neighboring carbamate (Boc protected amine and conjugated alkyne functionalities. They differ only by the nature of the atom located at the penultimate position of the diyne moiety, either a hydrogen atom or a bromine atom. Both of them adopt very similar 2D wall organizations with antiparallel carbamates (as in antiparallel beta pleated sheets. Additional weak interactions inside the same walls between molecular bricks are H bond interactions (diyne-H···O=C or halogen bond interactions (diyne-Br···O=C, respectively. Based on crystallographic atom coordinates, DFT (B3LYP/6-31++G(d,p and DFT (M06-2X/6-31++G(d,p calculations were performed on these isostructural crystals to gain insight into the intermolecular interactions.

Distributions of alkali metals, alkaline earth metals and halogens in cabbage leaves

International Nuclear Information System (INIS)

Tsukada, Hirofumi; Takeda, Akira; Hasegawa, Hidenao

2007-01-01

The distributions of stable elements in plant components provide useful information for understanding the behavior of radionuclides in plants. An entire cabbage plant sample was collected from an experimental field, and the distributions of alkali metals (K, Rb and Cs), alkaline earth metals (Ca, Sr and Ba) and halogens (Cl and I) were determined for cabbage leaves at different positions. The concentration of Cs in outer (older) cabbage leaves was higher than that in inner (younger) leaves, but the distributions of K and Rb concentrations were relatively similar in cabbage leaves, independent of leaf positions. The concentration of Sr in older cabbage leaves was one order of magnitude higher than that in younger leaves. The distributions of Ca, Ba and Sr concentrations in the plant followed a similar pattern. The concentrations of halogens were also very rich in the outer leaves. The percentage distributions of Cs, Sr, Cl and I in the inedible (extreme outer) leaves were 77, 91, 93 and 96% of the total content in the leaf part, respectively. These results show that the inedible plant components are important for understanding the transfer of the radioactive Cs, Sr Cl and I in soil-plant systems. (author)

Tannins and Tannin-Related Derivatives Enhance the (Pseudo-)Halogenating Activity of Lactoperoxidase.

Science.gov (United States)

Gau, Jana; Prévost, Martine; Van Antwerpen, Pierre; Sarosi, Menyhárt-Botond; Rodewald, Steffen; Arnhold, Jürgen; Flemmig, Jörg

2017-05-26

Several hydrolyzable tannins, proanthocyanidins, tannin derivatives, and a tannin-rich plant extract of tormentil rhizome were tested for their potential to regenerate the (pseudo-)halogenating activity, i.e., the oxidation of SCN - to hypothiocyanite - OSCN, of lactoperoxidase (LPO) after hydrogen peroxide-mediated enzyme inactivation. Measurements were performed using 5-thio-2-nitrobenzoic acid in the presence of tannins and related substances in order to determine kinetic parameters and to trace the LPO-mediated - OSCN formation. The results were combined with docking studies and molecular orbital analysis. The - OSCN-regenerating effect of tannin derivatives relates well with their binding properties toward LPO as well as their occupied molecular orbitals. Especially simple compounds like ellagic acid or methyl gallate and the complex plant extract were found as potent enzyme-regenerating compounds. As the (pseudo-)halogenating activity of LPO contributes to the maintenance of oral bacterial homeostasis, the results provide new insights into the antibacterial mode of action of tannins and related compounds. Furthermore, chemical properties of the tested compounds that are important for efficient enzyme-substrate interaction and regeneration of the - OSCN formation by LPO were identified.

Halogenating reaction activity of aromatic organic compounds during disinfection of drinking water

International Nuclear Information System (INIS)

Guo Gaimei; Chen Xiaodong

2009-01-01

The halogenating reactions of five aromatic organic compounds (AOCs) with aqueous chlorine (HOCl/OCl - ) and aqueous bromine (HOBr/OBr - ) were studied with an aim to compare the formation properties of haloacetic acids (HAAs) for the corresponding chlorination or bromination reactions of AOCs, respectively. The experiment results indicated that the HAAs substitution efficiency for the bromination reactions of AOCs was greater than that for the chlorination reactions, and the formation of HAAs had a strong dependence on the chemical structure of AOCs. The chlorination or bromination reaction activities for the AOCs with electron donating functional groups were higher than that for them with electron withdrawing functional groups. The kinetic experiments indicated that the reactions of aqueous bromine with phenol were faster than those of aqueous chlorine with phenol and the halogen consumption exhibited rapid initial and slower consumption stages for the reactions of phenol with aqueous chlorine and bromine, respectively. In addition, the HAAs production for the chlorination reaction of phenol decreased with the increase of pH. These conclusions could provide the valuable information for the effective control of the disinfection by-products during drinking water treatment operation

Study of radiation-induced paramagnetic centers in quartz and its possible use in radiation dosimetry

International Nuclear Information System (INIS)

Mansour, A.M.E.

2008-01-01

A new EPR dosimetry system has been developed based on the radiation-formed stable paramagnetic centers in quartz. The first part of the thesis includes the preparation of quartz rods (diameter = 3 mm, length = 10 mm) where quartz powder was mixed with molten mixture of paraffin wax and ethylene vinyl acetate copolymer (EVA). The binding-mixture EVA / paraffin do not present interference or noise in the EPR signal before or after irradiation to high doses. The quartz rods were prepared by different concentrations (5, 10, 20, 30 and 50 %). The rods (30 %) show good mechanical properties for safe and multi-use handling. The second part is concerned with studying the dosimetric characteristics of gamma irradiation sensitive rods where the radiation-formed stable free radicals (E-center, peroxy radical and non-bridging oxygen hole center) which analyzed by using electron paramagnetic resonance (EPR) spectrometer. Unirradiated rods have no EPR signals. The useful dose range of these rods was found to range from 0.1 to 80 kGy depending on concentration of quartz powder, indicating their suitability for low and high dose gamma radiation applications. Also it was found that quartz rod exhibits a linear dose response in the dose regions 0.1-2.34 and 2.34-26 kGy at optimum EPR parameters. The dosimeter response was assessed using the peak-to-peak amplitude of the first-derivatives EPR spectrum. Its EPR signal was found unchanged in shape with different doses and different concentrations. A signal line spectrum attributed to the E-center was observed after irradiation, and this radical is insensitive to temperature, light independence as well as it have a very low decay (4.768 % per year). The overall uncertainty for quartz rod dosimeters at 2σ (σ is standard deviation) was found to be 3.8436 %. The dosimetric parameters, e. g. dose response, effect of temperature during irradiation on response as well as pre- and post-irradiation stability at different storage conditions

Primary investigation on contamination pattern of legacy and emerging halogenated organic pollutions in freshwater fish from Liaohe River, Northeast China

International Nuclear Information System (INIS)

Ren Guofa; Wang Zhao; Yu Zhiqiang; Wang Yang; Ma Shengtao; Wu Minghong; Sheng Guoying; Fu Jiamo

2013-01-01

Legacy halogenated compounds, including polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and emerging organo-halogen pollutants such as Dechlorane Plus (DP), were detected in fish from an old industrial region in Northeast China. PCBs and PBDEs were detected in all of the samples, with concentrations ranging from 38.15 to 170.51 ng/g lipid weight, and 9.40–39.69 ng/g lipid weight, respectively. DP was detected in more than 90% of the samples with concentrations ranging from not detected (ND) to 470 pg g/g lipid weight. Compared with similar data in other areas of the world, PCBs, PBDEs and DP in fish from Liaohe River were at medium or low level. An unusually high percentage of PCB-209 was first reported in the fish samples collected from China. Other halogenated pollutions, such as dichlorodiphenyltrichloroethane (DDT) and its metabolites, octachlorostyrene, chlorinated anisole, chlorinated thioanisole, triclosan-methyl, and other pesticides, have also been identified in the fish samples. - Highlights: ► DP was reported in fish samples from river close to an old industrial base in China. ► The first report on the unusually high fraction of PCB-209 in samples from China. ► GC × GC–TOFMS was used to identify non-targeted halogenated pollutants. - An unusually high percentage of PCB-209 was first reported in the fish samples collected from China, which might indicate that there were distinct sources of pure PCB-209 in the region of Liaohe River.

Understanding optically stimulated charge movement in quartz and feldspar using time-resolved measurements

DEFF Research Database (Denmark)

Ankjærgaard, Christina

. Although, results are only presented for some quartz and feldspar samples, they were found to be very similar within the each group during the course of this work.Thermoluminescence (TL) and optically stimulated luminescence (OSL) from quartz and feldspar are widely used in accident dosimetry...... stimulation energy. The thesis first delves into three main methodological developments, namely (i) research and development of the equipment for TR-OSL measurements, (ii) finding the best method for multiple-exponential analysis of a TR-OSL curve, and (iii) optimisation of the pulsing configuration...... of the equipment for TR-OSL measurements, (ii) finding the best method for multiple-exponential analysis of a TR-OSL curve, and (iii) optimisation of the pulsing configuration for the best separation of quartz OSL from a mixed quarts-feldspar sample. It then proceeds to study the different charge transport...

Use of pyrrole black in zinc-halogen batteries

Energy Technology Data Exchange (ETDEWEB)

Mengoli, G.; Musiani, M.M.; Tomat, R.; Valcher, S.; Pletcher, D.

1985-09-01

The storage of Br/sub 2//Br/sup -/ and I/sub 2//I/sup -/ couples in a conducting polymer matrix, polypyrrole coated on a reticulated vitreous carbon disc, is described and the application of these positive electrodes in zinc-halogen model batteries is discussed. The cell based on the polypyrrole bromine adduct shows the higher open circuit voltage which, however, depends on the state of charge. Such cells self discharge thus limiting their usefulness. In the case of the iodine cell the self discharge is due to loss of iodine from the polymer to the bulk solution, but with the bromine cell the cause is oxidative bromination and depolymerization of the polypyrrole. 22 references, 6 figures, 2 tables.

Adsorption of bis(2-hydroxy-3-chloropropyl) dodecylamine on quartz surface and its implication on flotation

Science.gov (United States)

Liu, Wengang; Liu, Wenbao; Dai, Shujuan; Wang, Benying

2018-06-01

In order to clarify the effect of polar group modification on flotation performance of amine collector, flotation properties of quartz and hematite using bis(2-hydroxy-3-chloropropyl) dodecylamine (N23) as a collector were investigated. And the adsorption mechanism of N23 on quartz surface was established by zeta potential measurements, SEM/EDS measurements, and molecular structure analysis. Single mineral flotation results indicated that N23 showed stronger collecting ability on quartz and hematite than DDA-CH3COOH. However, starch could depress the flotation of hematite. Flotation recovery of 98.10% for quartz could be achieved, when N23 concentration was 43.33 mg/L and starch concentration was 16.67 mg/L at natural slurry pH. Separation of artificially mixed minerals of hematite and quartz was achieved effectively using N23 as the collector. The optimized separation result with 66.29% iron grade and 90.06% iron recovery in concentrate was obtained when slurry pH was 7.34 with 43.33 mg/L N23 and 23.33 mg/L starch. The interaction energies of N23 with mineral surface also showed well consistency with flotation results. SEM/EDS analyses and zeta potential measurements revealed that N23 could absorb on quartz surface in the forms of strong electrostatic and hydrogen bonding interaction. Compared with DDA, N23 had a higher HLB value and better water-solubility, which resulted in better dispersion in water and stronger adsorption on mineral surface.

In vitro pulp chamber temperature rise from irradiation and exotherm of flowable composites.

Science.gov (United States)

Baroudi, Kusai; Silikas, Nick; Watts, David C

2009-01-01

The aim of this study was to investigate the pulpal temperature rise induced during the polymerization of flowable and non-flowable composites using light-emitting diode (LED) and halogen (quartz-tungsten-halogen) light-curing units (LCUs). Five flowable and three non-flowable composites were examined. Pulpal temperature changes were recorded over 10 min in a sample primary tooth by a thermocouple. A conventional quartz-tungsten-halogen source and two LEDs, one of which was programmable, were used for light curing the resin composites. Three repetitions per material were made for each LCU. There was a wide range of temperature rises among the materials (P < 0.05). Temperature rises ranged between 1.3 degrees C for Filtek Supreme irradiated by low-power LED and 4.5 degrees C for Grandio Flow irradiated by high-power LED. The highest temperature rises were observed with both the LED high-power and soft-start LCUs. The time to reach the exothermic peak varied significantly between the materials (P < 0.05). Pulpal temperature rise is related to both the radiant energy output from LCUs and the polymerization exotherm of resin composites. A greater potential risk for heat-induced pulp damage might be associated with high-power LED sources. Flowable composites exhibited higher temperature rises than non-flowable materials, because of higher resin contents.

ESR signals in quartz for the studies of earth surface processes

Science.gov (United States)

Toyoda, S.; Shimada, A., , Dr; Takada, M.

2017-12-01

Various ESR (electron spin resonance) signals are observed in quartz. As they are formed by natural radiation, the signals are useful in dating of geological events, such as volcanic eruption, faulting and sedimentation. It was also found that those paramagnetic defects can be fingerprints of sediments, to be used for studies in sediment provenance. The signal of the E1' center, unpaired electron at an oxygen vacancy, was first used for such studies. A method was proposed to estimate the number of the precursors (oxygen vacancies) from the E1' center intensity. The number of oxygen vacancies in quartz was found to have positive correlation with the crystallization age. Using this feature, studies were quite successful in aeolian dust. It was shown that the sources of aeolian dust deposited in northern part of Japanese Islands were different between in MIS1 and MIS 2. In combination with crystallinity index, the contributions of the dust components from three origins were quantitatively obtained. After these, the provenance studies on river sediments have started where the impurity centers in quartz were employed, which are the Al center, the Ti centers, and the Ge centers. Sediments of Kizu River, Mie to Nara prefectures in Central Japan are most extensively studied. Firstly, it was shown that each of possible sources of granitic quartz around the reaches has respective characteristics in the number of oxygen vacancies and the signal intensities of impurity centers. Secondary, by the artificial mixing experiments, the impurity signal intensities have the values consistent with the mixing ratio of the two samples of quartz with different intensities. At river junctions, the mixing ratios were calculated from the ESR signals. At some locations, the mixing ratio values obtained from one signal were consistent with the ones from another signal while at some locations they were not. The latter inconsistent results would indicate that the river sediments are

Optically stimulated luminescence from quartz measured using the linear modulation technique

International Nuclear Information System (INIS)

Bulur, E.; Boetter-Jensen, L.; Murray, A.S.

2000-01-01

The optically stimulated luminescence (OSL) from heated natural quartz has been investigated using the linear modulation technique (LMT), in which the excitation light intensity is increased linearly during stimulation. In contrast to conventional stimulation, which usually produces a monotonically decreasing signal, linearly increasing the stimulation power gives peaks in the signal as a function of time. In cases where the OSL signal contains more than one component, the linear increase in power of the stimulation light may result in a curve containing overlapping peaks, where the most easily stimulated component occurs at a shorter time. This allows the separation of the overlapping OSL components, which are assumed to originate from different traps. The LM-OSL curve from quartz shows an initial peak followed by a broad one. Deconvolution using curve fitting has shown that the composite OSL curve from quartz can be approximated well by using a linear combination of first-order peaks. In addition to the three known components, i.e. fast, medium and slow components from continuous-wave-OSL studies, an additional slow component is also identified for the first time. The dose responses and thermal stabilities of the various components are also studied

Surface complexation modelling: Experiments on the sorption of nickel on quartz

International Nuclear Information System (INIS)

Puukko, E.; Hakanen, M.

1995-10-01

Assessing the safety of a final repository for nuclear wastes requires knowledge concerning the way in which the radionuclides released are retarded in the geosphere. The aim of the work is to aquire knowledge of empirical methods repeating the experiments on the sorption of nickel on quartz described in the reports published by the British Geological Survey (BGS). The experimental results were modelled with computer models at the Technical Research Centre of Finland (VTT Chemical Technology). The results showed that the experimental knowledge of the sorption of Ni on quartz have been acheved by repeating the experiments of BGS. Experiments made with the two quartz types, Min-U-Sil 5 (MUS) and Nilsiae, showed the difference in sorption of Ni in the low ionic strength solution (0.001 M NaNO 3 ). The sorption of Ni on MUS was higher than predicted by the Surface Complexation Model (SCM). The phenomenon was also observed by the BGS, and may be due to the different amounts of inpurities in the MUS and in the NLS. In other respects, the results of the sorption experiments fitted quite well with those predicted by the SCM model. (8 refs., 8 figs., 11 tabs.)

Surface Textural Analysis of Quartz Grains from Modern Point Bar Deposits in Lower Reaches of the Yellow River

Science.gov (United States)

Cheng, Yong; Liu, Cong; Lu, Ping; Zhang, Yu; Nie, Qi; Wen, Yiming

2018-01-01

The surfaces of quartz grains contain characteristic textures formed during the process of transport, due to their stable physical and chemical properties. The surface textures include the information about source area, transporting force, sedimentary environment and evolution history of sediment. Surface textures of quartz grains from modern point bar deposits in the lower reaches of the Yellow River are observed and studied by scanning electron microscopy (SEM). Results indicate that there are 22 kinds of surface textures. The overall surface morphology of quartz grains shows short transporting time and distance and weak abrasive action of the river water. The combined surface textures caused by mechanical action indicate that quartz grains are transporting in a high-energy hydrodynamic condition and suffer a strong mechanical impact and abrasion. The common solution pits prove that the chemical property of transportation medium is very active and quartz grains receive an obvious chemical action. The combination of these surface textures can be an identification mark of fluvial environment, and that is: quartz grains are main subangular outline, whose roundness is higher with the farther motion distance; Surface fluctuation degree of quartz grains is relatively high, and gives priority to high and medium relief; V-shaped percussion marks are very abundant caused by mechanical action; The conchoidal of different sizes and steps are common-developed with paragenesis relationship; Solution pits are common-developed as well. The study makes up for the blank of surface textures analysis of quartz grains from modern fluvial deposits in China. It provides new ideas and evidence for studies of the sedimentary process and environmental significance, although the deep meanings of these micro textures remain to be further researched.

Ozone variability and halogen oxidation within the Arctic and sub-Arctic springtime boundary layer

Directory of Open Access Journals (Sweden)

J. B. Gilman

2010-11-01

Full Text Available The influence of halogen oxidation on the variabilities of ozone (O₃ and volatile organic compounds (VOCs within the Arctic and sub-Arctic atmospheric boundary layer was investigated using field measurements from multiple campaigns conducted in March and April 2008 as part of the POLARCAT project. For the ship-based measurements, a high degree of correlation (r = 0.98 for 544 data points collected north of 68° N was observed between the acetylene to benzene ratio, used as a marker for chlorine and bromine oxidation, and O₃ signifying the vast influence of halogen oxidation throughout the ice-free regions of the North Atlantic. Concurrent airborne and ground-based measurements in the Alaskan Arctic substantiated this correlation and were used to demonstrate that halogen oxidation influenced O₃ variability throughout the Arctic boundary layer during these springtime studies. Measurements aboard the R/V Knorr in the North Atlantic and Arctic Oceans provided a unique view of the transport of O₃-poor air masses from the Arctic Basin to latitudes as far south as 52° N. FLEXPART, a Lagrangian transport model, was used to quantitatively determine the exposure of air masses encountered by the ship to first-year ice (FYI, multi-year ice (MYI, and total ICE (FYI+MYI. O₃ anti-correlated with the modeled total ICE tracer (r = −0.86 indicating that up to 73% of the O₃ variability measured in the Arctic marine boundary layer could be related to sea ice exposure.

Detection of Molecular Oxygen at Low Concentrations Using Quartz Enhanced Photoacoustic Spectroscopy

Directory of Open Access Journals (Sweden)

Andreas Pohlkötter

2010-09-01