Sample records for vapor phase cigarette

  1. Leukocyte Recruitment of Airways by Cigarette Smoke and Particle Phase in Contrast to Cytotoxicity of Vapor

    Microsoft Academic Search

    Kaye H. Kilburn; Wayland McKenzie

    1975-01-01

    After hamsters had breathed fresh cigarette smoke in a miniature chamber, airways of the lung showed recruitment of polymorphonuclear leukocytes. Exposure to particles alone by removal of the vapor phase with charcoal did not change the leukocyte response. However, exposure to cigarette smoke vapor after removal of particles with Cambridge filters did not recruit leukocytes but produced nuclear and cytoplasmic

  2. Particulate and vapor phase constituents of cigarette mainstream smoke and risk of myocardial infarction

    Microsoft Academic Search

    Carr J. Smith; Thomas H. Fischer

    2001-01-01

    On pharmacological and compositional grounds, cigarette mainstream smoke (MS) aerosol can be broadly categorized as consisting of the following constituents: carbon monoxide, other vapor phase components, particulate matter (‘tar’) and nicotine. The relative risk of coronary artery disease for smoking 20 cigarettes per day has been estimated by meta-analysis of five large prospective epidemiology studies to be 1.78. These four

  3. Glass fibers and vapor phase components of cigarette smoke as cofactors in experimental respiratory tract carcinogenesis

    SciTech Connect

    Feron, V.J.; Kuper, C.F.; Spit, B.J.; Reuzel, P.G.; Woutersen, R.A.

    1985-01-01

    Syrian golden hamsters were given intratracheal instillations of glass fibers with or without BP suspended in saline, once a fortnight for 52 weeks; the experiment was terminated at week 85. No tumors of the respiratory tract were observed in hamsters treated with glass fibers alone. There was no indication that glass fibers enhanced the development of respiratory tract tumors induced by BP. In another study Syrian golden hamsters were exposed to fresh air or to a mixture of 4 major vapor phase components of cigarette smoke, viz. isoprene (800----700 ppm), methyl chloride (1000----900 ppm), methyl nitrite (200----190 ppm) and acetaldehyde (1400----1200 ppm) for a period of at most 23 months. Some of the animals were also given repeated intratracheal instillations of BP or norharman in saline. Laryngeal tumors were found in 7/31 male and 6/32 female hamsters exposed only to the vapor mixture, whereas no laryngeal tumors occurred in controls. The tumor response of the larynx most probably has to be ascribed entirely to the action of acetaldehyde. Simultaneous treatment with norharman or BP did not affect the tumor response of the larynx. Acetaldehyde may occur in the vapor phase of cigarette smoke at levels up to 2000 ppm. Chronic inhalation exposure of rats to acetaldehyde at levels of 0 (controls), 750, 1500 or 3000----1000 ppm resulted in a high incidence of nasal carcinomas, both squamous cell carcinomas of the respiratory epithelium and adenocarcinomas of the olfactory epithelium. It was discussed that acetaldehyde may significantly contribute to the induction of bronchogenic cancer by cigarette smoke in man.

  4. An ex vivo approach to the differential parenchymal responses induced by cigarette whole smoke and its vapor phase.

    PubMed

    Lin, James Chi-Jen; Roy, Jean-Philippe; Verreault, Jules; Talbot, Sébastien; Côté, France; Couture, Réjean; Morin, André

    2012-03-11

    Using a rat lung slice model, this study compared the stress responses induced by cigarette whole smoke (WS) to that induced by the vapor phase (VP) of the smoke. Following a 3-day exposure, lung slices exposed to 4, 10 and 20% WS retained 85, 42 and 16% relative survival respectively in comparison to the air-exposed ones. Consistently, histological observations revealed concentration-related alveolar damages in the lung slices. Expression of 5 stress-response genes was examined following a single 30 min exposure to 4% WS or VP. WS exposure resulted in 4, 11 and 50-fold induction of IL-1?, kinin type I receptor (B?R) and CYP1A1 genes, respectively, while CYP1B1 and TNF-? genes expression was found only two times higher in comparison to VP group. Since cigarette WS consists of particulate and vapor phases, these results highlight the preferential or synergistic role of the particulate phase in the induction of IL-1?, B?R and CYP1A1 genes and that VP did not have comparable effects on expression of these genes. However, both phases fairly contributed to the induction of CYP1B1 and TNF-? genes. VP was the fraction responsible for the toxic effect since WS did not produce further toxicity. The 4% whole smoke deposited about 7.1 ?g/cm² of total particulate matter (TPM) to the exposure chamber which may account for observed differential stress responses in the lung slices. PMID:22266391

  5. Murine lung tumor response after exposure to cigarette mainstream smoke or its particulate and gas/vapor phase fractions.

    PubMed

    Stinn, Walter; Arts, Josje H E; Buettner, Ansgar; Duistermaat, Evert; Janssens, Kris; Kuper, C Frieke; Haussmann, Hans-Juergen

    2010-09-10

    Knowledge on mechanisms of smoking-induced tumorigenesis and on active smoke constituents may improve the development and evaluation of chemopreventive and therapeutic interventions, early diagnostic markers, and new and potentially reduced-risk tobacco products. A suitable laboratory animal disease model of mainstream cigarette smoke inhalation is needed for this purpose. In order to develop such a model, A/J and Swiss SWR/J mouse strains, with a genetic susceptibility to developing lung adenocarcinoma, were whole-body exposed to diluted cigarette mainstream smoke at 0, 120, and 240 mg total particulate matter per m(3) for 6h per day, 5 days per week. Mainstream smoke is the smoke actively inhaled by the smoker. For etiological reasons, parallel exposures to whole smoke fractions (enriched for particulate or gas/vapor phase) were performed at the higher concentration level. After 5 months of smoke inhalation and an additional 4-month post-inhalation period, both mouse strains responded similarly: no increase in lung tumor multiplicity was seen at the end of the inhalation period; however, there was a concentration-dependent tumorigenic response at the end of the post-inhalation period (up to 2-fold beyond control) in mice exposed to the whole smoke or the particulate phase. Tumors were characterized mainly as pulmonary adenomas. At the end of the inhalation period, epithelial hyperplasia, atrophy, and metaplasia were found in the nasal passages and larynx, and cellular and molecular markers of inflammation were found in the bronchoalveolar lavage fluid. These inflammatory effects were mostly resolved by the end of the post-inhalation period. In summary, these mouse strains responded to mainstream smoke inhalation with enhanced pulmonary adenoma formation. The major tumorigenic potency resided in the particulate phase, which is contrary to the findings published for environmental tobacco smoke surrogate inhalation in these mouse models. PMID:20594951

  6. GC–MS Analysis of Hydrogen Sulfide, Carbonyl Sulfide, Methanethiol, Carbon Disulfide, Methyl Thiocyanate and Methyl Disulfide in Mainstream Vapor Phase Cigarette Smoke

    Microsoft Academic Search

    Ji-Zhou Dong; Samuel M. DeBusk

    2010-01-01

    A method is described for the simultaneous analysis of hydrogen sulfide, carbonyl sulfide, methanethiol, carbon disulfide,\\u000a methyl thiocyanate and methyl disulfide in mainstream vapor phase (MVP) cigarette smoke by gas chromatography–mass spectrometry.\\u000a The fresh MVP smoke was collected in a gas bag, followed by injection of a 50 ?L gas sample into the GC inlet via an automatic\\u000a six-port valve. The

  7. Levels of selected carcinogens and toxicants in vapor from electronic cigarettes

    PubMed Central

    Lukasz, Goniewicz Maciej; Jakub, Knysak; Michal, Gawron; Leon, Kosmider; Andrzej, Sobczak; Jolanta, Kurek; Adam, Prokopowicz; Magdalena, Jablonska-Czapla; Czeslawa, Rosik-Dulewska; Christopher, Havel; Peyton, Jacob; Neal, Benowitz

    2014-01-01

    Significance Electronic cigarettes, also known as e-cigarettes, are devices designed to imitate regular cigarettes and deliver nicotine via inhalation without combusting tobacco. They are purported to deliver nicotine without other toxicants and to be safer alternative to regular cigarettes. However, little toxicity testing has been performed to evaluate the chemical nature of vapor generated from e-cigarettes. The aim of this study was to screen e-cigarette vapors for content of four groups of potentially toxic and carcinogenic compounds: carbonyls, volatile organic compounds, nitrosamines, and heavy metals. Materials and methods Vapors were generated from 12 brands of e-cigarettes and the reference product, the medicinal nicotine inhaler, in controlled conditions using a modified smoking machine. The selected toxic compounds were extracted from vapors into a solid or liquid phase and analyzed with chromatographic and spectroscopy methods. Results We found that the e-cigarette vapors contained some toxic substances. The levels of the toxicants were 9 to 450 times lower than in cigarette smoke and were, in many cases, comparable to trace amounts found in the reference product. Conclusions Our findings are consistent with the idea that substituting tobacco cigarettes with electronic cigarettes may substantially reduce exposure to selected tobacco-specific toxicants. E-cigarettes as a harm reduction strategy among smokers unwilling to quit warrants further study. PMID:23467656

  8. Headspace stir bar sorptive extraction-gas chromatography/mass spectrometry characterization of the diluted vapor phase of cigarette smoke delivered to an in vitro cell exposure chamber.

    PubMed

    Kaur, Navneet; Cabral, Jean-Louis; Morin, André; Waldron, Karen C

    2011-01-14

    Advanced smoke generation systems, such as the Borgwaldt RM20S(®) smoking machine used in combination with the BAT exposure chamber, allow for the generation, dilution and delivery of fresh cigarette smoke to cell or tissue cultures for in vitro cell culture analyses. Recently, our group confirmed that the Borgwaldt RM20S(®) is a reliable tool to generate and deliver repeatable and reproducible exposure concentrations of whole smoke to in vitro cultures. However, the relationship between dose and diluted smoke components found within the exposure chamber has not been characterized. The current study focused on the development of a headspace stir bar sorptive extraction (HSSE) method to chemically characterize some of the vapor phase components of cigarette smoke generated by the Borgwaldt RM20S(®) and collected within a cell culture exposure chamber. The method was based on passive sampling within the chamber by HSSE using a Twister™ stir bar. Following exposure, sorbed analytes were recovered using a thermal desorption unit and a cooled injection system coupled to gas chromatograph/mass spectrometry for identification and quantification. Using the HSSE method, sixteen compounds were identified. The desorption parameters were assessed using ten reference compounds and the following conditions led to the maximal response: desorption temperature of 200°C for 2 min with cryofocussing temperature of -75°C. During transfer of the stir bars to the thermal desorption system, significant losses of analytes were observed as a function of time; therefore, the exposure-to-desorption time interval was kept at the minimum of 10±0.5 min. Repeatability of the HSSE method was assessed by monitoring five reference compounds present in the vapor phase (10.1-12.9% RSD) and n-butyl acetate, the internal standard (18.5% RSD). The smoke dilution precision was found to be 17.2, 6.2 and 11.7% RSD for exposure concentrations of 1, 2 and 5% (v/v) cigarette vapor phase in air, respectively. A linear response of analyte abundance was observed as a function of dilution. Extrapolation to 100% (v/v) cigarette vapor phase, i.e., undiluted smoke, gave yields for the five compounds ranging from 6 to 450 ng for 10 min exposure. PMID:21163485

  9. Murine lung tumor response after exposure to cigarette mainstream smoke or its particulate and gas\\/vapor phase fractions

    Microsoft Academic Search

    Walter Stinn; Josje H. E. Arts; Ansgar Buettner; Evert Duistermaat; Kris Janssens; C. Frieke Kuper; Hans-Juergen Haussmann

    2010-01-01

    Knowledge on mechanisms of smoking-induced tumorigenesis and on active smoke constituents may improve the development and evaluation of chemopreventive and therapeutic interventions, early diagnostic markers, and new and potentially reduced-risk tobacco products. A suitable laboratory animal disease model of mainstream cigarette smoke inhalation is needed for this purpose. In order to develop such a model, A\\/J and Swiss SWR\\/J mouse

  10. Evaluation of E-Cigarette Liquid Vapor and Mainstream Cigarette Smoke after Direct Exposure of Primary Human Bronchial Epithelial Cells

    PubMed Central

    Scheffler, Stefanie; Dieken, Hauke; Krischenowski, Olaf; Förster, Christine; Branscheid, Detlev; Aufderheide, Michaela

    2015-01-01

    E-cigarettes are emerging products, often described as “reduced-risk” nicotine products or alternatives to combustible cigarettes. Many smokers switch to e-cigarettes to quit or significantly reduce smoking. However, no regulations for e-cigarettes are currently into force, so that the quality and safety of e-liquids is not necessarily guaranteed. We exposed primary human bronchial epithelial cells of two different donors to vapor of e-cigarette liquid with or without nicotine, vapor of the carrier substances propylene glycol and glycerol as well as to mainstream smoke of K3R4F research cigarettes. The exposure was done in a CULTEX® RFS compact module, allowing the exposure of the cells at the air-liquid interface. 24 h post-exposure, cell viability and oxidative stress levels in the cells were analyzed. We found toxicological effects of e-cigarette vapor and the pure carrier substances, whereas the nicotine concentration did not have an effect on the cell viability. The viability of mainstream smoke cigarette exposed cells was 4.5–8 times lower and the oxidative stress levels 4.5–5 times higher than those of e-cigarette vapor exposed cells, depending on the donor. Our experimental setup delivered reproducible data and thus provides the opportunity for routine testing of e-cigarette liquids to ensure safety and quality for the user. PMID:25856554

  11. Evaluation of E-cigarette liquid vapor and mainstream cigarette smoke after direct exposure of primary human bronchial epithelial cells.

    PubMed

    Scheffler, Stefanie; Dieken, Hauke; Krischenowski, Olaf; Förster, Christine; Branscheid, Detlev; Aufderheide, Michaela

    2015-04-01

    E-cigarettes are emerging products, often described as "reduced-risk" nicotine products or alternatives to combustible cigarettes. Many smokers switch to e-cigarettes to quit or significantly reduce smoking. However, no regulations for e-cigarettes are currently into force, so that the quality and safety of e-liquids is not necessarily guaranteed. We exposed primary human bronchial epithelial cells of two different donors to vapor of e-cigarette liquid with or without nicotine, vapor of the carrier substances propylene glycol and glycerol as well as to mainstream smoke of K3R4F research cigarettes. The exposure was done in a CULTEX® RFS compact  module, allowing the exposure of the cells at the air-liquid interface. 24 h post-exposure, cell viability and oxidative stress levels in the cells were analyzed. We found toxicological effects of e-cigarette vapor and the pure carrier substances, whereas the nicotine concentration did not have an effect on the cell viability. The viability of mainstream smoke cigarette exposed cells was 4.5-8 times lower and the oxidative stress levels 4.5-5 times higher than those of e-cigarette vapor exposed cells, depending on the donor. Our experimental setup delivered reproducible data and thus provides the opportunity for routine testing of e-cigarette liquids to ensure safety and quality for the user. PMID:25856554

  12. The effect of the pore size and volume of activated carbon on adsorption efficiency of vapor phase compounds in cigarette smoke

    Microsoft Academic Search

    Takashi Sasaki; Akihiko Matsumoto; Yoichiro Yamashita

    2008-01-01

    Adsorption of volatile organic compounds (VOCs) in cigarette smoke by activated carbons was measured to investigate the correlation between the adsorption efficiencies of the VOCs and pore size and volume of the activated carbons. The adsorption efficiency E is defined by E=(Ci,in–Ci,out)\\/Ci,in where Ci,in and Ci,out are the concentration of the ith VOC component in cigarette smoke before and after

  13. Chemical hazards present in liquids and vapors of electronic cigarettes.

    PubMed

    Hutzler, Christoph; Paschke, Meike; Kruschinski, Svetlana; Henkler, Frank; Hahn, Jürgen; Luch, Andreas

    2014-07-01

    Electronic (e-)cigarettes have emerged in recent years as putative alternative to conventional tobacco cigarettes. These products do not contain typical carcinogens that are present in tobacco smoke, due to the lack of combustion. However, besides nicotine, hazards can also arise from other constituents of liquids, such as solvents, flavors, additives and contaminants. In this study, we have analyzed 28 liquids of seven manufacturers purchased in Germany. We confirm the presence of a wide range of flavors to enhance palatability. Although glycerol and propylene glycol were detected in all samples, these solvents had been replaced by ethylene glycol as dominant compound in five products. Ethylene glycol is associated with markedly enhanced toxicological hazards when compared to conventionally used glycerol and propylene glycol. Additional additives, such as coumarin and acetamide, that raise concerns for human health were detected in certain samples. Ten out of 28 products had been declared "free-of-nicotine" by the manufacturer. Among these ten, seven liquids were identified containing nicotine in the range of 0.1-15 µg/ml. This suggests that "carry over" of ingredients may occur during the production of cartridges. We have further analyzed the formation of carbonylic compounds in one widely distributed nicotine-free brand. Significant amounts of formaldehyde, acetaldehyde and propionaldehyde were only found at 150 °C by headspace GC-MS analysis. In addition, an enhanced formation of aldehydes was found in defined puff fractions, using an adopted machine smoking protocol. However, this effect was delayed and only observed during the last third of the smoking procedure. In the emissions of these fractions, which represent up to 40 % of total vapor volume, similar levels of formaldehyde were detected when compared to conventional tobacco cigarettes. By contrast, carbonylic compounds were hardly detectable in earlier collected fractions. Our data demonstrate the necessity of standardized machine smoking protocols to reliably address putative risks of e-cigarettes for consumers. PMID:24958024

  14. Headspace stir bar sorptive extraction–gas chromatography\\/mass spectrometry characterization of the diluted vapor phase of cigarette smoke delivered to an in vitro cell exposure chamber

    Microsoft Academic Search

    Navneet Kaur; Jean-Louis Cabral; André Morin; Karen C. Waldron

    2011-01-01

    Advanced smoke generation systems, such as the Borgwaldt RM20S® smoking machine used in combination with the BAT exposure chamber, allow for the generation, dilution and delivery of fresh cigarette smoke to cell or tissue cultures for in vitro cell culture analyses. Recently, our group confirmed that the Borgwaldt RM20S® is a reliable tool to generate and deliver repeatable and reproducible

  15. Evaluation of the Genotoxic and Cytotoxic Potential of Mainstream Whole Smoke and Smoke Condensate from a Cigarette Containing a Novel Carbon Filter

    Microsoft Academic Search

    D. W. Bombick; B. Reed Bombick; P. H. Ayres; K. Putnam; J. Avalos; M. F. Borgerding; D. J. Doolittle

    1997-01-01

    A novel carbon filter has been developed which primarily reduces the amount of certain vapor phase constituents of tobacco smoke with greater efficiency than the charcoal filters of cigarettes currently in the market.In vitroindicators of genotoxic and cytotoxic potential were used to compare the cigarette smoke condensate (particulate phase) or whole cigarette smoke (vapor phase and particulate phase) from cigarettes

  16. Infrared spectroscopy study of the influence of inhaled vapors/smoke produced by cigarettes of active smokers.

    PubMed

    Popa, Cristina

    2015-05-01

    While much is known about the effect of smoke and vapors on the composition of blood, little is known about their impact on the composition of breath. When tobacco from traditional cigarettes (T) is burned, it produces harmful smoke compared with the vapor produced when using electronic cigarettes (E). Using a noninvasive, safe, and rapid CO2 laser-photoacoustic method, this study aimed to examine the ethylene changes at different time intervals in the exhaled breath composition of E-cigarette smokers and T-cigarette smokers, before and after the consecutive exposures to cigarettes. Oxidative stress from exposure to tobacco smoke has a role in the pathogenic process, leading to chronic obstructive pulmonary disease. The evidence on the mechanisms by which T-smoking causes damage indicates that there is no risk-free level of exposure to tobacco smoke. The study revealed that the ethylene level (in the E-cigarette smoker's case) was found to be in smaller concentrations (compared with T-cigarette smoker's case) and that E-cigarettes may provide an alternative to T-cigarette smoking. PMID:25347574

  17. Organometallic vapor phase epitaxy (OMVPE)

    Microsoft Academic Search

    William G. Breiland; Michael E. Coltrin; J. Randall Creighton; Hong Q. Hou; Harry K. Moffat; Jeffrey Y. Tsao

    1999-01-01

    Organometallic vapor phase epitaxy (OMVPE) has emerged in this past decade as a flexible and powerful epitaxial materials synthesis technology for a wide range of compound–semiconductor materials and devices. Despite its capabilities and rapidly growing importance, OMVPE is far from being well understood: it is exceedingly complex, involving the chemically reacting flow of mixtures of organometallic, hydride and carrier-gas precursors.

  18. Vapor Phase Catalytic Ammonia Reduction

    NASA Technical Reports Server (NTRS)

    Flynn, Michael T.; Harper, Lynn D. (Technical Monitor)

    1994-01-01

    This paper discusses the development of a Vapor Phase Catalytic Ammonia Reduction (VPCAR) teststand and the results of an experimental program designed to evaluate the potential of the technology as a water purification process. In the experimental program the technology is evaluated based upon product water purity, water recovery rate, and power consumption. The experimental work demonstrates that the technology produces high purity product water and attains high water recovery rates at a relatively high specific power consumption. The experimental program was conducted in 3 phases. In phase I an Igepon(TM) soap and water mixture was used to evaluate the performance of an innovative Wiped-Film Rotating-Disk evaporator and associated demister. In phase II a phenol-water solution was used to evaluate the performance of the high temperature catalytic oxidation reactor. In phase III a urine analog was used to evaluate the performance of the combined distillation/oxidation functions of the processor.

  19. Endothelial disruptive proinflammatory effects of nicotine and e-cigarette vapor exposures.

    PubMed

    Schweitzer, Kelly S; Chen, Steven X; Law, Sarah; Van Demark, Mary; Poirier, Christophe; Justice, Matthew J; Hubbard, Walter C; Kim, Elena S; Lai, Xianyin; Wang, Mu; Kranz, William D; Carroll, Clinton J; Ray, Bruce D; Bittman, Robert; Goodpaster, John; Petrache, Irina

    2015-07-15

    The increased use of inhaled nicotine via e-cigarettes has unknown risks to lung health. Having previously shown that cigarette smoke (CS) extract disrupts the lung microvasculature barrier function by endothelial cell activation and cytoskeletal rearrangement, we investigated the contribution of nicotine in CS or e-cigarettes (e-Cig) to lung endothelial injury. Primary lung microvascular endothelial cells were exposed to nicotine, e-Cig solution, or condensed e-Cig vapor (1-20 mM nicotine) or to nicotine-free CS extract or e-Cig solutions. Compared with nicotine-containing extract, nicotine free-CS extract (10-20%) caused significantly less endothelial permeability as measured with electric cell-substrate impedance sensing. Nicotine exposures triggered dose-dependent loss of endothelial barrier in cultured cell monolayers and rapidly increased lung inflammation and oxidative stress in mice. The endothelial barrier disruptive effects were associated with increased intracellular ceramides, p38 MAPK activation, and myosin light chain (MLC) phosphorylation, and was critically mediated by Rho-activated kinase via inhibition of MLC-phosphatase unit MYPT1. Although nicotine at sufficient concentrations to cause endothelial barrier loss did not trigger cell necrosis, it markedly inhibited cell proliferation. Augmentation of sphingosine-1-phosphate (S1P) signaling via S1P1 improved both endothelial cell proliferation and barrier function during nicotine exposures. Nicotine-independent effects of e-Cig solutions were noted, which may be attributable to acrolein, detected along with propylene glycol, glycerol, and nicotine by NMR, mass spectrometry, and gas chromatography, in both e-Cig solutions and vapor. These results suggest that soluble components of e-Cig, including nicotine, cause dose-dependent loss of lung endothelial barrier function, which is associated with oxidative stress and brisk inflammation. PMID:25979079

  20. Vapor phase lubrication of high temperature alloys

    SciTech Connect

    Hanyaloglu, B.F.; Graham, E.E.; Oreskovic, T.; Hajj, C.G. [Cleveland State Univ., OH (United States)

    1995-06-01

    In a previous study, it was found that when a nickel-based superalloy IN750 was heated to high temperatures, a passive layer of aluminum oxide formed on the surface, preventing vapor phase lubrication. In this study, two nickel-chrome-iron alloys and a nickel-copper alloy were studied for high temperature lubrication to see if these alloys, which contained small amounts of aluminum, would exhibit similar behavior. It was found that under static conditions, all three alloys formed a lubricious nodular coating when exposed to a vapor of aryl phosphate. Under dynamic sliding conditions at 500{degrees}C, these alloys were successfully lubricated with a coefficient of friction of 0.1 and no detectable wear. In order to explain these results, a direct correlation between successful vapor phase lubrication and the composition of the alloys containing aluminum has been proposed. If the ratio of copper/aluminum or iron/aluminum is greater that 100 vapor phase, lubrication will be successful. If the ratio is less than 10, a passive aluminum oxide layer will prevent vapor phase lubrication. By selecting alloys with a high iron or copper content, vapor phase lubrication can provide excellent lubrication at high temperatures. 14 refs., 11 figs., 1 tab.

  1. A Simple and Rapid Method for Standard Preparation of Gas Phase Extract of Cigarette Smoke

    PubMed Central

    Higashi, Tsunehito; Mai, Yosuke; Noya, Yoichi; Horinouchi, Takahiro; Terada, Koji; Hoshi, Akimasa; Nepal, Prabha; Harada, Takuya; Horiguchi, Mika; Hatate, Chizuru; Kuge, Yuji; Miwa, Soichi

    2014-01-01

    Cigarette smoke consists of tar and gas phase: the latter is toxicologically important because it can pass through lung alveolar epithelium to enter the circulation. Here we attempt to establish a standard method for preparation of gas phase extract of cigarette smoke (CSE). CSE was prepared by continuously sucking cigarette smoke through a Cambridge filter to remove tar, followed by bubbling it into phosphate-buffered saline (PBS). An increase in dry weight of the filter was defined as tar weight. Characteristically, concentrations of CSEs were represented as virtual tar concentrations, assuming that tar on the filter was dissolved in PBS. CSEs prepared from smaller numbers of cigarettes (original tar concentrations ?15 mg/ml) showed similar concentration-response curves for cytotoxicity versus virtual tar concentrations, but with CSEs from larger numbers (tar ?20 mg/ml), the curves were shifted rightward. Accordingly, the cytotoxic activity was detected in PBS of the second reservoir downstream of the first one with larger numbers of cigarettes. CSEs prepared from various cigarette brands showed comparable concentration-response curves for cytotoxicity. Two types of CSEs prepared by continuous and puff smoking protocols were similar regarding concentration-response curves for cytotoxicity, pharmacology of their cytotoxicity, and concentrations of cytotoxic compounds. These data show that concentrations of CSEs expressed by virtual tar concentrations can be a reference value to normalize their cytotoxicity, irrespective of numbers of combusted cigarettes, cigarette brands and smoking protocols, if original tar concentrations are ?15 mg/ml. PMID:25229830

  2. Water vapor radiometry research and development phase

    NASA Technical Reports Server (NTRS)

    Resch, G. M.; Chavez, M. C.; Yamane, N. L.; Barbier, K. M.; Chandlee, R. C.

    1985-01-01

    This report describes the research and development phase for eight dual-channel water vapor radiometers constructed for the Crustal Dynamics Project at the Goddard Space Flight Center, Greenbelt, Maryland, and for the NASA Deep Space Network. These instruments were developed to demonstrate that the variable path delay imposed on microwave radio transmissions by atmospheric water vapor can be calibrated, particularly as this phenomenon affects very long baseline interferometry measurement systems. Water vapor radiometry technology can also be used in systems that involve moist air meteorology and propagation studies.

  3. An overview: Vapor phase corrosion inhibitors

    SciTech Connect

    Subramanian, A.; Natesan, M.; Muralidharan, V.S.; Balakrishnan, K.; Vasudevan, T.

    2000-02-01

    When present as vapors, certain organic compounds offer inhibition against the corrosion of ferrous and nonferrous materials. The inhibitors include aliphatic, aromatic, cyclohexylamines, aminonitrobenzoates, heteroalkylated lower amines, etc. The mechanism of inhibition offered by these compounds was discussed and an unified mechanism was presented. Various methods of evaluating inhibition efficiency were discussed with a special reference to surface film characterization techniques. Methods of application of the vapor phase inhibitors and their industrial uses also were presented.

  4. COMPARATIVE YIELDS OF MUTAGENS FROM CIGARETTE SMOKERS' URINE OBTAINED BY USING SOLID-PHASE EXTRACTION TECHNIQUES

    EPA Science Inventory

    Urine from cigarette smokers was prepared for mutagenicity testing by extracting mutagens with solid phase extraction columns. ommercially available prepacked bonded silicas (cotadecyl, cyclohexyl, cyanopropyl) were compared for their efficiency and specificity in concentration o...

  5. Vapor-liquid phase separator permeability results

    NASA Technical Reports Server (NTRS)

    Yuan, S. W. K.; Frederking, T. H. K.

    1981-01-01

    Continued studies are described in the area of vapor-liquid phase separator work with emphasis on permeabilities of porous sintered plugs (stainless steel, nominal pore size 2 micrometer). The temperature dependence of the permeability has been evaluated in classical fluid using He-4 gas at atmospheric pressure and in He-2 on the basis of a modified, thermosmotic permeability of the normal fluid.

  6. DIFFERENTIAL IN VIVO EFFECTS OF WHOLE CIGARETTE SMOKE EXPOSURE VERSUS CIGARETTE SMOKE EXTRACT ON MOUSE CILIATED TRACHEAL EPITHELIUM

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this study we compared the affect of vapor phase cigarette smoke (CS) versus cigarette smoke extract (CSE) on the lungs and upper airway of C57BL/6 mice. We found that CSE treatment significantly increased neutrophil influx (P<0.001), baseline ciliary beat frequency (CBF) (P<0.05), and protein ki...

  7. Vapor phase lubrication of high temperature alloys

    Microsoft Academic Search

    B. F. Hanyaloglu; E. E. Graham; T. Oreskovic; C. G. Hajj

    1995-01-01

    In a previous study, it was found that when a nickel-based superalloy IN750 was heated to high temperatures, a passive layer of aluminum oxide formed on the surface, preventing vapor phase lubrication. In this study, two nickel-chrome-iron alloys and a nickel-copper alloy were studied for high temperature lubrication to see if these alloys, which contained small amounts of aluminum, would

  8. The mouse lymphoma thymidine kinase assay for the assessment and comparison of the mutagenic activity of cigarette mainstream smoke particulate phase

    Microsoft Academic Search

    H. Schramke; T. J. Meisgen; F. J. Tewes; W. Gomm; E. Roemer

    2006-01-01

    The mouse lymphoma thymidine kinase assay (MLA) has been optimized to quantitatively determine the in vitro mutagenicity of cigarette mainstream smoke particulate phase. To test whether the MLA is able to discriminate between different cigarette types, specially constructed cigarettes each containing a single tobacco type – Bright, Burley, or Oriental – were investigated. The mutagenic activity of the Burley cigarette

  9. [Electronic cigarette].

    PubMed

    Králíková, Eva; Jezek, Martin

    2012-01-01

    Electronic cigarette (e-cigarettes) belongs to the "ENDS (Electronic Nicotine Delivery Systems), ie systems that deliver nicotine electronically. Extract of tobacco does not burn, just warm. Vapors may or may not contain nicotine. E-cigarettes are also available with different flavors. They don't produce a classic smoke. There is a large variability of these products. It seems that the initial negative position has to be reconsidered. Although there has been demonstrated trace amounts of several toxic substances in the vapor, the risk compared to traditional smoking is minimal. Moreover, lately it was shown that they can really contribute to smoking quitting. The legislative framework varies considerably, from the prohibition on sales to the recommended assistance in quitting. In the CR they are included according to the Act 379/2005 in 2009 among the tobacco products. PMID:22679688

  10. Adenylate Kinase 3 Sensitizes Cells to Cigarette Smoke Condensate Vapor Induced Cisplatin Resistance

    Microsoft Academic Search

    Xiaofei Chang; Rajani Ravi; Vui Pham; Atul Bedi; Aditi Chatterjee; David Sidransky

    2011-01-01

    BackgroundThe major established etiologic risk factor for bladder cancer is cigarette smoking and one of the major antineoplastic agents used for the treatment of advanced bladder cancer is cisplatin. A number of reports have suggested that cancer patients who smoke while receiving treatment have lower rates of response and decreased efficacy of cancer therapies.Methodology\\/Principal FindingsIn this study, we investigated the

  11. Cigarettes and cigarette smoking.

    PubMed

    Burns, D M

    1991-12-01

    Tobacco use was widespread in the New World by the time of the first voyage of Columbus; however, it is only in the last century that the use of tobacco as cigarettes has been prevalent. The milder tobacco and more acidic smoke of cigarettes lead to the deeper inhalation of tobacco into the lung with resultant deposition and absorption of the addicting, toxic, and carcinogenic components of the smoke. More than 4000 individual constituents have been identified in cigarette smoke, and the relative concentrations of these constituents vary widely between brands of cigarettes. Tar yield, a measure of the total particulate matter of the smoke, varies markedly with the characteristics of the cigarette manufacture and with the pattern of inhalation. As a result, tar is not a good measure of the dose of toxic or carcinogenic agents received by the individual smoker. The particle size of cigarette smoke is in the range that will lead to deposition in the airways and alveoli of the lung, and many of the gas-phase constituents are absorbed across the alveolar capillary membrane. The irritant agents in the smoke cause acute and chronic changes in lung structure and function that may result in greater retention of carcinogens within the lung and increased vulnerability of the lung to the effects of these carcinogens. Carcinogens and other constituents of cigarette smoke are also absorbed into the blood and metabolized to active forms through microsomal enzyme systems induced by cigarette smoke. The cellular influx of neutrophils and alveolar macrophages that is part of the inflammatory response may be the precursor of the alveolar wall destruction that results in emphysema. The prevalence of smoking is not uniformly distributed across the population. Men began smoking in large numbers very early in the century, but women began to smoke in large number only at the time of the Second World War. Men born after 1930 have been less likely to take up smoking than their older counterparts. The prevalence of smoking is currently declining in both men and women. PMID:1747982

  12. Enhancement of epitaxial lateral overgrowth by vapor-phase diffusion

    E-print Network

    Khenner, Mikhail

    heterostructure lasers, electroadsorption modulators, light-emitting diodes, etc. [1,2]. Micrometer nanostructures by MBE [10­12]. The advances in experimental field of SAG stimulate the interest in fundamental growth mechanism and ignore diffusion in vapor phase; the effect of vapor phase is reduced

  13. Freebase nicotine in tobacco products. Part I. Determination of free-base nicotine in the particulate phase of mainstream cigarette smoke and the relevance of these findings to product design parameters

    Microsoft Academic Search

    J. H. Lauterbach; M. Bao; P. J. Joza; W. S. Rickert

    2010-01-01

    The free-base nicotine (FBN) content of mainstream cigarette smoke (MSS) has been discussed in the peer-reviewed literature and popular press. It has been alleged that manufacturers adjust product design features to increase the percentage of total nicotine (TN) in the MSS gas–vapor phase that is unprotonated [Pg,nic(%)] and\\/or the fraction of nicotine in the MSS total particulate matter (TPM) that

  14. Free-base nicotine in tobacco products. Part I. Determination of free-base nicotine in the particulate phase of mainstream cigarette smoke and the relevance of these findings to product design parameters.

    PubMed

    Lauterbach, J H; Bao, M; Joza, P J; Rickert, W S

    2010-10-01

    The free-base nicotine (FBN) content of mainstream cigarette smoke (MSS) has been discussed in the peer-reviewed literature and popular press. It has been alleged that manufacturers adjust product design features to increase the percentage of total nicotine (TN) in the MSS gas-vapor phase that is unprotonated [P(g)(,nic)(%)] and/or the fraction of nicotine in the MSS total particulate matter (TPM) that is unprotonated (FBN/TN). Our research showed the Health Canada Intensive smoking conditions negated the effects of blend and cigarette design features reported to raise the pH of TPM collected under ISO or US FTC conditions. Our research also showed that when additive-free Canadian cigarettes were smoked under ISO conditions, the FBN/TN ratio increased as the tar/nicotine ratio decreased. Our findings are in line with other studies that have questioned allegations of a relationship between use of ammonia and its compounds as tobacco additives and amounts of unprotonated nicotine in MSS. In addition, the experimental work demonstrated how use of solid-phase microextraction to estimate FBN can yield erroneously high results due to improper conditioning and/or smoking of the cigarettes. Our research showed that there is no longer any scientific support for regulators to require smoke pH and FBN determinations on cigarette products. PMID:20621585

  15. Vapor phase growth of nanostructured yttrium oxysulfide films

    Microsoft Academic Search

    V. V. Bakovets; T. M. Levashova; I. Yu. Filatova; E. A. Maksimovskii; A. E. Kupcha

    2008-01-01

    Nanostructured yttrium oxysulfide films have been prepared via vapor phase growth. The first step was the deposition of 50-nm-thick\\u000a nanostructured yttria films from yttrium dipivaloylmethanate vapor at 525°C. Next, the films were sulfided in ammonium thiocyanate\\u000a vapor at temperatures from 800 to 1100°C. Hexagonal yttrium oxysulfide was obtained at 900°C and higher temperatures. The\\u000a films consisted of densely packed grains

  16. Size and Generation Rate of Sidestream Cigarette Smoke Particles

    Microsoft Academic Search

    Yasuo Ueno; Leonard K. Peters

    1986-01-01

    Sidestream cigarette smoke generated using an automatic smoking machine (SEM-II) and Kentucky 2R1 reference cigarettes was analyzed for particle generation rate and size distribution. Part of the sidestream smoke was sampled with an Andersen Cascade Impactor, following dilution with about 29 to 54 liters\\/min of laboratory air. The remaining sidestream smoke was further diluted 1,000-fold with vapor phase from filtered

  17. External fuel vaporization study, phase 1

    NASA Technical Reports Server (NTRS)

    Szetela, E. J.; Chiappetta, L.

    1980-01-01

    A conceptual design study was conducted to devise and evaluate techniques for the external vaporization of fuel for use in an aircraft gas turbine with characteristics similar to the Energy Efficient Engine (E(3)). Three vaporizer concepts were selected and they were analyzed from the standpoint of fuel thermal stability, integration of the vaporizer system into the aircraft engine, engine and vaporizer dynamic response, startup and altitude restart, engine performance, control requirements, safety, and maintenance. One of the concepts was found to improve the performance of the baseline E(3) engine without seriously compromising engine startup and power change response. Increased maintenance is required because of the need for frequent pyrolytic cleaning of the surfaces in contact with hot fuel.

  18. Development of Vapor-Phase Catalytic Ammonia Removal System

    NASA Technical Reports Server (NTRS)

    Flynn, Michael; Fisher, John; Kiss, Mark; Borchers, Bruce; Tleimat, Badawi; Tleimat, Maher; Quinn, Gregory; Fort, James; Nalette, Tim; Baker, Gale; Genovese, Joseph

    2007-01-01

    A report describes recent accomplishments of a continuing effort to develop the vapor-phase catalytic ammonia removal (VPCAR) process for recycling wastewater for consumption by humans aboard a spacecraft in transit to Mars.

  19. Preliminary assessment of halogenated alkanes as vapor-phase tracers

    SciTech Connect

    Adams, Michael C.; Moore, Joseph N.; Hirtz, Paul

    1991-01-01

    New tracers are needed to evaluate the efficiency of injection strategies in vapor-dominated environments. One group of compounds that seems to meet the requirements for vapor-phase tracing are the halogenated alkanes (HCFCs). HCFCs are generally nontoxic, and extrapolation of tabulated thermodynamic data indicate that they will be thermally stable and nonreactive in a geothermal environment. The solubilities and stabilities of these compounds, which form several homologous series, vary according to the substituent ratios of fluorine, chlorine, and hydrogen. Laboratory and field tests that will further define the suitability of HCFCs as vapor-phase tracers are under way.

  20. Superfluid helium 2 liquid-vapor phase separation: Technology assessment

    Microsoft Academic Search

    J. M. Lee

    1984-01-01

    A literature survey of helium 2 liquid vapor phase separation is presented. Currently, two types of He 2 phase separators are being investigated: porous, sintered metal plugs and the active phase separator. The permeability K(P) shows consistency in porous plug geometric characterization. Both the heat and mass fluxes increase with K(P). Downstream pressure regulation to adjust for varying heat loads

  1. Vapor phase crystallization in Apollo 14 breccia.

    NASA Technical Reports Server (NTRS)

    Mckay, D. S.; Clanton, U. S.; Morrison, D. A.; Ladle, G. H.

    1972-01-01

    The vugs contained in many of the highly recrystallized breccias from Apollo 14 are discussed, along with the well-developed crystals of plagioclase, pyroxene, ilmenite, apatite, whitlockite, iron, nickel-iron, and troilite that extend from the vug walls and bridge open spaces. These crystals are interpreted as having formed by deposition from a hot vapor containing oxides, halides, sulfides, alkali metals, iron and possibly other chemical species. The hot vapor was associated with the thermal metamorphism and subsequent cooling of the Fra Mauro formation after it had been deposited as an ejecta blanket by the Imbrian impact.

  2. Vapor Phase Deposition Using Plasma Spray-PVD™

    NASA Astrophysics Data System (ADS)

    von Niessen, K.; Gindrat, M.; Refke, A.

    2010-01-01

    Plasma spray—physical vapor deposition (PS-PVD) is a low pressure plasma spray technology to deposit coatings out of the vapor phase. PS-PVD is a part of the family of new hybrid processes recently developed by Sulzer Metco AG (Switzerland) on the basis of the well-established low pressure plasma spraying (LPPS) technology. Included in this new process family are plasma spray—chemical vapor deposition (PS-CVD) and plasma spray—thin film (PS-TF) processes. In comparison to conventional vacuum plasma spraying and LPPS, these new processes use a high energy plasma gun operated at a work pressure below 2 mbar. This leads to unconventional plasma jet characteristics which can be used to obtain specific and unique coatings. An important new feature of PS-PVD is the possibility to deposit a coating not only by melting the feed stock material which builds up a layer from liquid splats, but also by vaporizing the injected material. Therefore, the PS-PVD process fills the gap between the conventional PVD technologies and standard thermal spray processes. The possibility to vaporize feedstock material and to produce layers out of the vapor phase results in new and unique coating microstructures. The properties of such coatings are superior to those of thermal spray and EB-PVD coatings. This paper reports on the progress made at Sulzer Metco to develop functional coatings build up from vapor phase of oxide ceramics and metals.

  3. Electronic Cigarettes

    MedlinePLUS

    ... Previous Section Next Section What Is Known About E-Cigarettes? The claim that e-cigarettes emit only harmless ... Previous Section Next Section What Is Known About E-Cigarettes and Smoking Cessation? E-cigarettes have not been ...

  4. An Overview: Vapor Phase Corrosion Inhibitors

    Microsoft Academic Search

    A. Subramanian; T. Vasudevan; M. Natesan; V. S. Muralidharan; K. Balakrishnan

    2000-01-01

    When present as vapors, certain organic compounds offer inhibition against the corrosion of ferrous and nonferrous materials. The inhibitors include aliphatic, aromatic, cyclohexylamines, aminonitrobenzoates, heteroalkylated lower amines, etc. The mechanism of inhibition offered by these compounds was discussed and an unified mechanism was presented. Various methods of evaluating inhibition efficiency were discussed with a special reference to surface film characterization

  5. Modelling and Numerical Simulation of Liquid-Vapor Phase Transition

    E-print Network

    Paris-Sud XI, Université de

    of pressurized water reactors in the nuclear industry. Indeed, understanding the triggering of boiling crisis-Phase Model We assume that we are far from the critical point, thus the vapor (resp. liquid) phase can the triple Corresponding author is Gloria FACCANONI E-mail: gloria@cmap.polytechnique.fr, WWW: http

  6. Gas phase reaction of sulfur trioxide with water vapor

    SciTech Connect

    Kolb, C.E.; Molina, M.J.; Jayne, J.T.; Meads, R.F.; Worsnop, D.R.

    1994-12-31

    Sulfur trioxide (SO3) has long been known to react with water to produce sulfuric acid (H2S04). It has been commonly assumed that the gas phase reaction in the Earth`s atmosphere between SO3 and water vapor to produce sulfuric acid vapor is an important step in the production of sulfuric acid aerosol particles. The kinetics of the gas phase reaction of SO3 with water vapor have previously been studied by Castleman and co-workers, Wang et al and Reiner and Arnold. Each of these studies was carried out in a flow reactor, with the first two studies performed at low pressure (1-10 Torr) and the latter from approx. 30 to 260 Torr. Each of these studies measured SO3 decays over a range of H2O vapor levels, obtaining data consistent with interpreting the reaction of gaseous SO3 and H2O as a bimolecular process. It is not clear why previous experimental studies failed to observe a nonlinear dependence of SO3 consumption on water vapor concentration. It is probable that sufficient water dimer exists in much of the Earth`s atmosphere to allow dimer reactions to participate in sulfuric acid vapor formation.

  7. Phase transformations during the growth of paracetamol crystals from the vapor phase

    NASA Astrophysics Data System (ADS)

    Belyaev, A. P.; Rubets, V. P.; Antipov, V. V.; Bordei, N. S.

    2014-07-01

    Phase transformations during the growth of paracetamol crystals from the vapor phase are studied by differential scanning calorimetry. It is found that the vapor-crystal phase transition is actually a superposition of two phase transitions: a first-order phase transition with variable density and a second-order phase transition with variable ordering. The latter, being a diffuse phase transition, results in the formation of a new, "pretransition," phase irreversibly spent in the course of the transition, which ends in the appearance of orthorhombic crystals. X-ray diffraction data and micrograph are presented.

  8. Comparative Characterization of Organic Emissions from Diesel Particles, Coke Oven Mains, Roofing Tar Vapors and Cigarette Smoke Condensate

    Microsoft Academic Search

    R. Williams; C. Sparacino; B. Petersen; J. Bumgarner; R. H. Jungers; J. Lewtas

    1986-01-01

    This paper reports the characterization of the extractable organics from diesel particulate emissions compared to other complex organics which have been reported to increase the risk of human lung cancer. Class fractions of diesel, cigarette smoke condensate, roofing tar, and coke oven extracts were obtained using\\/liquid partitioning and silica gel chromatography. Capillary GC\\/MS was used to identify compounds in each

  9. The liquid and vapor phases in particle models with Kac potentials

    E-print Network

    Roma Tor Vergata, Università di

    The liquid and vapor phases in particle models with Kac potentials F. BaÆoni, I. Merola, and E curve #21; = #21;(#12;), #12; > #12; c > 0, where two phases (liquid and vapor) coexist, elsewhere #12; LIQUID AND VAPOR PHASES 2 P T liquid solid gas Figure 1. Phase diagram well understood. Indeed

  10. Assessment of radionuclide vapor-phase transport in unsaturated tuff

    SciTech Connect

    Smith, D.M.; Updegraff, C.D.; Bonano, E.J.; Randall, J.D.

    1986-11-01

    This report describes bounding calculations performed to investigate the possibility of radionuclide migration in a vapor phase associated with the emplacement of high-level waste canister in unsaturated tuff formations. Two potential radionuclide transport mechanisms in the vapor phase were examined: aerosol migration and convection/diffusion of volatile species. The former may have significant impact on the release of radionuclides to the accessible environment as the concentration in the aerosols will be equal to that in the ground water. A conservative analysis of air diffusion in a stagnant liquid film indicated that for all expected repository conditions, aerosol formation is not possible. The migration of volatile species was examined both in the vicinity of a waste canister and outside the thermally disturbed zone. Two-dimensional (radial) and three-dimensional (radial-vertical) coupled heat transfer-gas flow-liquid flow simulations were performed using the TOUGH computer code. The gas flow rate relative to the liquid flow rate predicted from the simulations allowed calculations of mobility ratios due to convection which led to the conclusion that, except for the immediate region near the canister, transport in the liquid phase will be dominant for radionuclides heavier than radon. Near the waste canister, iodine transport may also be important in the vapor phase. Bounding calculations for vertical mobility ratios were carried out as a function of saturation. These calculations are conservative and agree well with the two-dimensional simulations. Based on this analysis, it is clear that vapor-phase transport will not be important for radionuclides such as cesium and heavier species. Vapor transport for iodine may play a role in the overall release scenario depending on the particular repository conditions.

  11. Fog Machines, Vapors, and Phase Diagrams

    ERIC Educational Resources Information Center

    Vitz, Ed

    2008-01-01

    A series of demonstrations is described that elucidate the operation of commercial fog machines by using common laboratory equipment and supplies. The formation of fogs, or "mixing clouds", is discussed in terms of the phase diagram for water and other chemical principles. The demonstrations can be adapted for presentation suitable for elementary…

  12. Liquid-phase compositions from vapor-phase analyses: 3, Reanalysis of HF vapor-densities and of UFâ-HF liquid-vapor equilibria

    Microsoft Academic Search

    W. Jr. Davis; H. D. Cochran

    1986-01-01

    Currently, liquid-phase samples from uranium hexafluoride (UFâ) cylinders are used by all US Department of Energy enrichment facilities for determining the chemical content of cylinders - a requisite in the control and accountability of nuclear materials. Previously published reports note the economic incentive to use vapor-phase sampling for volatile impurities if the liquid-phase composition can be determined from analysis of

  13. Could charcoal filtration of cigarette smoke reduce smoking-induced disease? A review of the literature

    Microsoft Academic Search

    Christopher R. E. Coggins; Charles L. Gaworski

    2008-01-01

    A review of the published work with charcoal-filtered cigarettes indicates that there are reductions in the concentrations for many gas-vapor phase constituents found in mainstream smoke. However, charcoal filters provided no apparent capacity for reduction of smoke particulate phase components. The reductions in gas–vapor phase smoke chemistry analytes generally correspond with findings of reduced toxicological activity, principally related to a

  14. E-cigarettes: promise or peril?

    PubMed

    Riker, Carol A; Lee, Kiyoung; Darville, Audrey; Hahn, Ellen J

    2012-03-01

    Electronic cigarettes (e-cigarettes) use a heating element to vaporize nicotine and other ingredients, simulating the visual, sensory, and behavioral aspects of smoking without the combustion of tobacco. An ever-growing number of companies around the world manufacture a wide variety of e-cigarette brands, despite scant information on the safety of the ingredients for human inhalation. This article provides an overview of the history, production, and marketing of e-cigarettes, the contents of e-cigarettes and vapor, how they are used, public health concerns, and implications for nursing practice, research, and policy development. PMID:22289406

  15. Numerical Modelling of the Expansion Phase of Vapor Explosions

    NASA Astrophysics Data System (ADS)

    Hwang, Moonkyu

    When a cold liquid is brought into contact with a molten material with a temperature significantly higher than the liquid boiling point, an explosive interaction, involving sudden fragmentation of some of the molten material and rapid evaporation of the liquid, takes place. This phenomenon is referred to as a "vapor explosion" or "steam explosion". In the event of a core meltdown accident in a light water reactor, the molten fuel can interact with cooling water inside or outside the reactor vessel and cause a vapor explosion. The mechanical energy released during such an explosion can result in structural damage, and ultimately may lead to the release of radioactive material into the environment. Vapor explosions are extremely fast transients, involving a flow field consisting of at least three distinct phases, accompanied by thermal non-equilibrium and strong interfacial transfer processes. The objective of this research was to mechanistically model the expansion phase of a vapor explosion. A transient three-dimensional, three -fluid thermal hydraulic model was developed. Coolant liquid plus fragmented fuel particles, coolant vapor plus noncondensables and unfragmented fuel constitute the three fluids. Hydrodynamic and thermal interactions between the three phases were mechanistically treated, using flow regime-dependent models. The models were incorporated into a computer code, in which the conservation equations are cast in finite-difference form and are numerically solved using the point-relaxation method. The code was utilized in parametric and sensitivity calculations aimed at assessing the significance of interfacial transfer processes, and the effect of the premixture initial conditions on the phenomenology of the expansion phase of steam explosions. The initial conditions for the expansion phase were estimated by assuming that the propagation phase was a constant volume heat exchange process. Parametric results indicate that thermal and mechanical nonequilibrium are both significant. Various modelling assumptions relevant to the inter-phase transfer coefficients could change the predicted magnitude of the conversion ratio by up to a factor of two. The parametric results were extremely sensitive to the initial void fraction in the premixture prior to the propagation. The calculated conversion ratios varied by an order of magnitude as a result of varying the aforementioned initial void fraction.

  16. Supported complex catalysts for vapor-phase carbonylations

    SciTech Connect

    Bischoff, S.; Weigt, A.; Kant, M.; Schuelke, U. [Institute for Applied Chemistry Berlin-Adlershof (Germany)] [and others

    1996-10-01

    Supported mixed bidentate rhodium and iridium complexes derived from phosphonate-phosphanes have been studied in methanol carbonylation and in ethylene hydroformylation. The complexes showed higher activities than bis-phosphane complexes in homogeneous and vapor-phase methanol carbonylation. Hemilabile behavior of the mixed bidentate complexes may explain these findings. In contrast to strongly chelating ligands, phosphonate-phosphane ligands improved the selectivity of supported rhodium complexes in ethylene hydroformylation. Mixed zirconium phosphonate structures containing phosphane groups afforded excellent heterogeneous rhodium complex catalysts. The zirconium phosphonate-phosphane-rhodium catalysts were several times more active than rhodium on silica or rhodium on activated carbon, showed a superior stability, and produced butyraldehydes with up to 96% selectivity in the vapor-phase hydroformylation of propylene.

  17. Quantitative infrared spectra of vapor phase chemical agents

    Microsoft Academic Search

    Steven W. Sharpe; Timothy J. Johnson; Pamela M. Chu; James Kleimeyer; Brad Rowland; Patrick J. Gardner

    2003-01-01

    Quantitative, high resolution (0.1 cm-1) infrared spectra have been acquired for a number of pressure broadened (101.3 KPa N2), vapor phase chemicals including: Sarin (GB), Soman (GD), Tabun (GA), Cyclosarin (GF), VX, nitrogen mustard (HN3), sulfur mustard (HD) and Lewisite (L). The spectra are acquired using a heated, flow-through White cell of 5.6 m optical path length. Each reported spectrum

  18. Comparative characterization of organic emissions from diesel particles, coke oven mains, roofing tar vapors and cigarette smoke condensate.

    PubMed

    Williams, R; Sparacino, C; Petersen, B; Bumgarner, J; Jungers, R H; Lewtas, J

    1986-01-01

    This paper reports the characterization of the extractable organics from diesel particulate emissions compared to other complex organics which have been reported to increase the risk of human lung cancer. Class fractions of diesel, cigarette smoke condensate, roofing tar, and coke oven extracts were obtained using liquid/liquid partitioning and silica gel chromatography. Capillary GC/MS was used to identify compounds in each extract fraction. This manuscript reports the mass distribution after fractionation of each extract, all identified fraction components and quantification of selected mutagenic and carcinogenic compounds. PMID:3804556

  19. Comparative characterization of organic emissions from diesel particles, coke oven mains, roofing tar vapors, and cigarette smoke condensate

    SciTech Connect

    Williams, R.; Sparacino, C.; Petersen, B.; Bumgarner, J.; Jungers, R.H.

    1986-01-01

    The paper reports the characterization of the extractable organics from diesel particle emissions compared to other complex organics which have been reported to increase the risk of human lung cancer. Class fractions of diesel, cigarette smoke condensate, roofing tar, and coke oven extracts were obtained using liquid/liquid partitioning and silica gel chromatography. Capillary GC/MS was used to identify compounds in each extract fraction. The manuscript reports the mass distribution after fractionation of each extract, all identified fraction components and quantification of selected mutagenic and carcinogenic compounds.

  20. Superfluid helium 2 liquid-vapor phase separation: Technology assessment

    NASA Technical Reports Server (NTRS)

    Lee, J. M.

    1984-01-01

    A literature survey of helium 2 liquid vapor phase separation is presented. Currently, two types of He 2 phase separators are being investigated: porous, sintered metal plugs and the active phase separator. The permeability K(P) shows consistency in porous plug geometric characterization. Both the heat and mass fluxes increase with K(P). Downstream pressure regulation to adjust for varying heat loads and both temperatures is possible. For large dynamic heat loads, the active phase separator shows a maximum heat rejection rate of up to 2 W and bath temperature stability of 0.1 mK. Porous plug phase separation performance should be investigated for application to SIRTF and, in particular, that plugs of from 10 to the minus ninth square centimeters to 10 to the minus eighth square centimeters in conjunction with downstream pressure regulation be studied.

  1. Sensitive and selective determination of polycyclic aromatic hydrocarbons in mainstream cigarette smoke using a graphene-coated solid-phase microextraction fiber prior to GC/MS.

    PubMed

    Wang, Xiaoyu; Wang, Yuan; Qin, Yaqiong; Ding, Li; Chen, Yi; Xie, Fuwei

    2015-08-01

    A simple method has been developed for the simultaneous determination of 16 polycyclic aromatic hydrocarbons (PAHs) in mainstream cigarette smoke. The procedure is based on employing a homemade graphene-coated solid-phase microextraction (SPME) fiber for extraction prior to GC/MS. In comparison to commercial 100-?m poly(dimethyl siloxane) (PDMS) fiber, the graphene-coated SPME fiber exhibits advantageous cleanup and preconcentration efficiencies. By collecting the particulate phase 5 cigarettes, the LODs and LOQs of 16 target PAHs were 0.02-0.07 and 0.07-0.22ng/cigarette, respectively, and all of the linear correlation efficiencies were larger than 0.995. The validation results also indicate that the method has good repeatability (RSD between 4.2% and 9.5%) and accuracy (spiked recoveries between 80% and 110%). The developed method was applied to analyze two Kentucky reference cigarettes (1R5F and 3R4F) and six Chinese brands of cigarettes. In addition, the PAH concentrations in the particulate phase of the smoke from the 1R5F Kentucky cigarettes were in good agreement with recently reported results. Due to easy operation and good validation results, this SPME-GC/MS method may be an excellent alternative for trace analysis of PAHs in cigarette smoke. PMID:26048830

  2. Isotope dilution gas chromatography-mass spectrometry in the determination of benzene, toluene, styrene and acrylonitrile in mainstream cigarette smoke.

    PubMed

    Byrd, G D; Fowler, K W; Hicks, R D; Lovette, M E; Borgerding, M F

    1990-03-23

    A cryogenic trapping method with isotope dilution gas chromatography-mass spectrometry analysis has been developed for the determination of benzene, toluene, styrene and acrylonitrile in mainstream vapor phase cigarette smoke. The method is simple, direct, and quantitative. Vapor phase samples are collected cryogenically in a series of four traps following removal of the particulate phase with a Cambridge filter pad. For all four analytes, 75-85% of the total amounts recovered were found in the initial trap and less than 1% in the final trap. Assessment of instrumental precision by multiple injections of a sample gave relative standard deviations of less than 2%. Linear calibration for all analytes over the analysis range gave an r2 value greater than 0.99 with average relative standard deviations at the mean ranging from 1.4 to 8.2%. The cigarettes analyzed include a reference cigarette (Kentucky 1R4F), a commercial ultra-low "tar" mentholated cigarette, and two cigarettes that heat but do not burn tobacco. The values determined for the four analytes in the 1R4F samples are comparable to reported values of similar cigarettes. The cigarettes which heat rather than burn tobacco yield less of all four analytes compared to the other cigarettes in the study. PMID:2185256

  3. Evaluation of biomarkers of exposure to selected cigarette smoke constituents in adult smokers switched to carbon-filtered cigarettes in short-term and long-term clinical studies.

    PubMed

    Sarkar, Mohamadi; Kapur, Sunil; Frost-Pineda, Kimberly; Feng, Shixia; Wang, Jingzhu; Liang, Qiwei; Roethig, Hans

    2008-12-01

    Cigarette smoke is a complex aerosol that includes a gas vapor phase and a particulate phase. Inclusion of activated carbon in the cigarette filter can reduce some of the gas-phase smoke constituents implicated as toxicologically relevant. The present study evaluated exposure to selected gas-phase constituents when adult smokers switched to prototype cigarettes with a highly activated carbon filter. Smokers (N = 160) in two separate studies were randomized to continue to smoke conventional cigarettes (either a 6-mg or 11-mg FTC tar product), to smoke test cigarettes containing carbon filters (comparable tar levels), or to stop smoking. After completing 8 days in controlled smoking conditions (short-term studies), smokers had the option to continue in 24-week long-term ambulatory studies with unrestricted smoking. Urinary excretion of mercapturic acid metabolites of 1,3-butadiene, acrolein, and benzene; nicotine and five of its metabolites, total NNAL, and 1-hydroxypyrene were measured at baseline in the conventional cigarette group, in all groups in the short-term studies, and every 4 weeks in the long-term studies. In the short-term studies, statistically significant reductions (>70%, p<.001) in gas-phase biomarker levels were observed in the test cigarette group for both tar level products compared with the conventional cigarette group. These reductions were similar to those observed in the stop-smoking groups. The reductions continued consistently (p<.001) throughout the long-term studies. Switching to test cigarettes minimally affected the particulate-phase biomarkers. Statistically significant and consistent reductions in selected gas vapor phase biomarkers were observed when smokers switched to activated carbon filter cigarettes. PMID:19023827

  4. Vapor-induced phase separation—effect of the humid air exposure step on membrane morphology

    Microsoft Academic Search

    V. P. Khare; A. R. Greenberg; W. B. Krantz

    2005-01-01

    Vapor-induced phase separation (VIPS) involves a dry–wet casting process in which the dope solution is exposed to a nonsolvent vapor (often humid air) for a fixed time interval prior to immersion in a coagulation bath. Humid air exposure leads to a slow transfer of water from the vapor phase into the dope solution. By controlling the humid air exposure time,

  5. CONVERGENT FINITE ELEMENT DISCRETIZATION OF THE NAVIER-STOKES KORTEWEG SYSTEM FOR LIQUID-VAPOR PHASE

    E-print Network

    Tübingen, Universität

    CONVERGENT FINITE ELEMENT DISCRETIZATION OF THE NAVIER-STOKES KORTEWEG SYSTEM FOR LIQUID-VAPOR conditions. The isothermal Navier-Stokes-Korteweg model describes evolution of liquid- vapor diffuse, to properly cover both, the pressure in the `low density'/vapor phase, and the `high density'/liquid phase, i

  6. Molecular Orbital Studies of Zinc Oxide Chemical Vapor Deposition: Gas-Phase Radical Reactions

    E-print Network

    Schlegel, H. Bernhard

    Molecular Orbital Studies of Zinc Oxide Chemical Vapor Deposition: Gas-Phase Radical Reactions-phase reactions involved in the radical mechanism for zinc oxide chemical vapor deposition have been examined in the radical and closed shell mechanisms for zinc oxide chemical vapor deposition shows that the barrier

  7. nanocrystallites condensed in vapor-phase for photocatalyst applications

    NASA Astrophysics Data System (ADS)

    Yoshida, Takehito; Yagi, Nobuyasu; Nakagou, Riki; Sugimura, Akira; Umezu, Ikurou

    2014-10-01

    We have synthesized titanium dioxide (TiO2) nanocrystallites by pulsed laser ablation (PLA) in oxygen (O2) background gas for photocatalyst applications. Varying O2 background gas pressure or substrate target distance ( D TS), it was possible to change weight fraction of anatase phase in the anatase/rutile mixture from 0.2 to 1.0. Porosity of the deposited TiO2 films increased with increasing and D TS. Relation between the process parameters and the formed crystal phases was explained from the point of cooling process in vapor-phase. Furthermore, rapid thermal annealing (RTA) was performed as post-annealing, suppressing sintering of the nanocrystallites. Photocatalytic activities of the TiO2 nanocrystallites depended on the RTA temperature and following crystallinity restoring as well as the crystal phase: anatase or rutile.

  8. Modeling of Gallium Nitride Hydride Vapor Phase Epitaxy

    NASA Technical Reports Server (NTRS)

    Meyyappan, Meyya; Arnold, James O. (Technical Monitor)

    1997-01-01

    A reactor model for the hydride vapor phase epitaxy of GaN is presented. The governing flow, energy, and species conservation equations are solved in two dimensions to examine the growth characteristics as a function of process variables and reactor geometry. The growth rate varies with GaCl composition but independent of NH3 and H2 flow rates. A change in carrier gas for Ga source from H2 to N2 affects the growth rate and uniformity for a fixed reactor configuration. The model predictions are in general agreement with observed experimental behavior.

  9. Vapors-liquid phase separator. [infrared telescope heat sink

    NASA Technical Reports Server (NTRS)

    Frederking, T. H. K.; Brown, G. S.; Chuang, C.; Kamioka, Y.; Kim, Y. I.; Lee, J. M.; Yuan, S. W. K.

    1980-01-01

    The use of porous plugs, mostly with in the form of passive devices with constant area were considered as vapor-liquid phase separators for helium 2 storage vessels under reduced gravity. The incorporation of components with variable cross sectional area as a method of flow rate modification was also investigated. A particular device which uses a shutter-type system for area variation was designed and constructed. This system successfully permitted flor rate changes of up to plus or minus 60% from its mean value.

  10. Cigarettes Commencemet

    E-print Network

    Pilyugin, Sergei S.

    't throw your cigarette butts (or ANYTHING) on the ground! Folks, the university is getting very, very that people do not throw their cigarette butts on the ground any longer. This is considered litter. People for littering is $500. Don't risk it, please. Be sure to carefully put out your cigarettes and throw the butts

  11. Simultaneous determination of nicotine and 3-vinylpyridine in single cigarette tobacco smoke and in indoor air using direct extraction to solid phase

    PubMed Central

    Koszowski, Bartosz; Goniewicz, Maciej Lukasz; Czogala, Jan; Zymelka, Anna; Sobczak, Andrzej

    2009-01-01

    The aim of the present study was to develop a new analytical method of chromatographic determination of two important markers of ETS exposure: nicotine and 3-vinylpyridine (3-ethenylpyridine, 3-EP) in mainstream (MS) and sidestream (SS) smoke of one single cigarette and in indoor air using direct solid phase extraction combined with gas chromatography. The method can be utilised for both nicotine and 3-EP determination in SS and MS of one single cigarette as well as it allows for a precise determination of compound distribution in indoor air. The application of the same analytical method for both kinds of samples allows anticipating indoor air distribution of both analysed compounds in a very precise way. The precision of the method (calculated as a relative standard deviation) was 9.78% for nicotine and 2.67% for 3-EP; whereas the accuracy (evaluated by a recovery study conducted at three different levels) was 70.1 and 87.3%, respectively. The limit of detection was 0.06 µg per cigarette for both nicotine and 3-EP. The method was evaluated by determining the compounds of interest in two commercially available brands of cigarettes as well as in the reference cigarettes 3R4F and also in indoor air polluted with tobacco smoke. Determined levels of compounds of interest in MS varied from 586 to 772 (nicotine) µg per cigarette and from 3.5 to 10.7 (3-EP) µg per cigarette. In SS smoke the level varied from 14,370 to 22,590 (nicotine) µg per cigarette and from 185 to 550 (3-EP) µg per cigarette, whereas levels in indoor air polluted with tobacco smoke varied from 50.1 to 157.3 (nicotine) µg m?3 and from 7.7 to 20.8 (3-EP) µg m?3. PMID:19662106

  12. A load dampening system for vapor phase bioreactors

    SciTech Connect

    Al-Rayes, A.W.; Kinney, K.A.; Seibert, F.; Corsi, R.L.

    1999-07-01

    Vapor phase bioreactors have been used extensively to control odorous gases and are receiving increased attention as an efficient and cost-effective treatment method for volatile organic compound (VOC) emissions. However, an important issue related to bioreactors is their high sensitivity to shock loads and periods of process shutdown, which can significantly reduce treatment efficiency. The focus of this paper is the use of a novel closed absorption and humidification system to dampen dynamic loads of toluene, methyl tert butyl ether (MTBE), and acetone, and to reduce their detrimental effect on a downstream bioreactor. A model based on the mass transfer characteristics of target pollutants was developed and takes into account the closed water recirculation loop that minimizes fugitive emissions and simultaneously humidifies the influent gas stream. When water is used as the scrubbing liquid, model and experimental results indicate that the system effectively dampens hydrophilic compounds and segregates them from the hydrophobic compounds in the waste gas stream. The response of a vapor phase bioreactor to the pretreated stream has also been assessed and shows that the system works effectively with hydrophilic, but not hydrophobic, VOCs.

  13. Phase-Controlled Growth of Metastable Fe5Si3 Nanowires by a Vapor Transport Method

    E-print Network

    Kim, Bongsoo

    -limited solid-state reactions, only thermodynamically stable phases in the phase diagram nucleate. The vapor they demonstrated composition dependent crystalline KAIST. Korea University. (1) Massalski, T. B. Binary Alloy Phase Diagrams;

  14. Evaluation of the genotoxic and cytotoxic potential of mainstream whole smoke and smoke condensate from a cigarette containing a novel carbon filter.

    PubMed

    Bombick, D W; Bombick, B R; Ayres, P H; Putnam, K; Avalos, J; Borgerding, M F; Doolittle, D J

    1997-09-01

    A novel carbon filter has been developed which primarily reduces the amount of certain vapor phase constituents of tobacco smoke with greater efficiency than the charcoal filters of cigarettes currently in the market. In vitro indicators of genotoxic and cytotoxic potential were used to compare the cigarette smoke condensate (particulate phase) or whole cigarette smoke (vapor phase and particulate phase) from cigarettes containing the novel carbon filter with smoke condensate or whole smoke from commercial or prototype cigarettes not containing the novel carbon filter. Ames bacterial mutagenicity, sister chromatid exchange (SCE) in Chinese hamster ovary (CHO) cells, and neutral red cytotoxicity assays in CHO cells were utilized to assess the genotoxic and cytotoxic potential of the cigarette smoke condensates. SCE and neutral red cytotoxicity assays were utilized to assess the genotoxic and cytotoxic potential of the whole smoke. As expected, the novel carbon filter did not significantly affect the genotoxic or cytotoxic activity of the smoke condensate, although we did observe that the use of low-nitrogen tobacco reduced the mutagenicity of the condensate in Salmonella typhimurium strain TA98. However, the whole smoke from cigarettes containing the novel carbon filter demonstrated significant reductions in genotoxic and cytotoxic potential compared to cigarettes without the novel carbon filter. The toxicity of the smoke was correlated (r = 0.7662 for cytotoxicity and r = 0.7562 for SCE induction) to the aggregate mass of several vapor phase components (acetone, acetaldehyde, acrolein, acrylonitrile, 1,3-butadiene, ammonia, NOx, HCN, benzene, isoprene, and formaldehyde) in the smoke of the cigarettes utilized in this study. In conclusion, this novel carbon filter, which significantly reduced the amount of carbonyls and other volatiles in mainstream cigarette smoke, resulted in significant reductions in the genotoxic and cytotoxic activity of the smoke as measured by these assays. PMID:9325023

  15. Vapor-liquid coexistence of patchy models: Relevance to protein phase behavior

    E-print Network

    Sciortino, Francesco

    Vapor-liquid coexistence of patchy models: Relevance to protein phase behavior Hongjun Liu online 22 August 2007 The vapor-liquid coexistence boundaries of fluids composed of particles interacting, it is established that the reduced widths of the metastable vapor-liquid coexistence curve predicted by a model

  16. Continuous Determination of High-Vapor Phase Concentrations of Tetrachloroethylene Using On-Line Mass Spectrometry

    EPA Science Inventory

    A method was developed to determine the vapor concentration of tetrachloroethylene (PCE) at and below its equilibrium vapor phase concentration, 168,000 µg/L (25°C). Vapor samples were drawn by vacuum into a six-port sampling valve and injected through a jet separator into an io...

  17. Hygroscopic Growth and Deposition of Inhaled Secondary Cigarette Smoke in Human Nasal Pathways

    Microsoft Academic Search

    Jeffry D. Schroeter; Cynthia J. Musante; Dongming Hwang; Ray Burton; Ray Guilmette; Ted B. Martonen

    2001-01-01

    To ascertain the threat to human health posed by the inhalation of the particulate phase for secondary cigarette smoke (SCS), it is necessary to determine the doses delivered to airway cells. The risk assessment of SCS particles is complicated by their hygroscopic properties. Inhaled particles that are hygroscopic may absorb the water vapor that is present in a warm, humid

  18. Glass fibers and vapor phase components of cigarette smoke as cofactors in experimental respiratory tract carcinogenesis

    Microsoft Academic Search

    V. J. Feron; C. F. Kuper; B. J. Spit; P. G. Reuzel; R. A. Woutersen

    1985-01-01

    Syrian golden hamsters were given intratracheal instillations of glass fibers with or without BP suspended in saline, once a fortnight for 52 weeks; the experiment was terminated at week 85. No tumors of the respiratory tract were observed in hamsters treated with glass fibers alone. There was no indication that glass fibers enhanced the development of respiratory tract tumors induced

  19. Vapor phase mediated cellular uptake of sub 5 nm nanoparticles

    PubMed Central

    2012-01-01

    Nanoparticles became an important and wide-used tool for cell imaging because of their unique optical properties. Although the potential of nanoparticles (NPs) in biology is promising, a number of questions concerning the safety of nanomaterials and the risk/benefit ratio of their usage are open. Here, we have shown that nanoparticles produced from silicon carbide (NPs) dispersed in colloidal suspensions are able to penetrate into surrounding air environment during the natural evaporation of the colloids and label biological cells via vapor phase. Natural gradual size-tuning of NPs in dependence to the distance from the NP liquid source allows progressive shift of the fluorescence color of labeled cells in the blue region according to the increase of the distance from the NP suspension. This effect may be used for the soft vapor labeling of biological cells with the possibility of controlling the color of fluorescence. However, scientists dealing with the colloidal NPs have to seriously consider such a NP's natural transfer in order to protect their own health as well as to avoid any contamination of the control samples. PMID:22494848

  20. Vapor phase lubrication of a Ni-based superalloy

    SciTech Connect

    Hanyaloglu, B.; Fedor, D.C.; Graham, E.E. [Cleveland State Univ., OH (United States)

    1995-03-01

    In addition to ceramics, alloys such as tool steel and nickel- and iron-based superalloys are being considered for high temperature applications such as missile bearings and low heat rejection engines. Studies were made to lubricate a nickel-based superalloy at 500{degrees}C, by using a vaporized aryl phosphate ester, at a concentration of 0.1% in air. From deposition and wear studies it was found that it was impossible to form a good polymeric coating on the superalloy surface. Energy dispersive X-ray analyzer (EDXA) analysis showed that this was due to minute quantities of aluminum in the alloy segregating to the surface, upon being heated to 500{degrees}C, forming a passive oxide coating. It was necessary to activate the surface, in order to lubricate the material successfully. A method of activation by electrodepositing the surface with a layer of iron oxide was developed. Once activated, a good lubricous polymer was formed on the superalloy surface. Tests performed under dynamic conditions and 1 MPa pressure, using an activated specimen surface showed no wear and a coefficient of friction ({mu}) of 0.05. These results stress the importance of material selection for high temperature vapor phase lubrication. 15 refs., 13 figs., 2 tabs.

  1. Could charcoal filtration of cigarette smoke reduce smoking-induced disease? A review of the literature.

    PubMed

    Coggins, Christopher R E; Gaworski, Charles L

    2008-04-01

    A review of the published work with charcoal-filtered cigarettes indicates that there are reductions in the concentrations for many gas-vapor phase constituents found in mainstream smoke. However, charcoal filters provided no apparent capacity for reduction of smoke particulate phase components. The reductions in gas-vapor phase smoke chemistry analytes generally correspond with findings of reduced toxicological activity, principally related to a reduction in the cytotoxic action of the volatile smoke constituents. Results of a short-term clinical study show small reductions in the biomarkers of the gas-vapor phase smoke constituents in subjects smoking charcoal-filtered cigarettes, compared to subjects smoking non-charcoal filtered cigarettes. The very limited epidemiology data (a single study) fail to demonstrate a conclusive beneficial effect of charcoal-filtered cigarette products compared to non-charcoal filtered cigarette products. Review of the scientific literature is hindered due to the lack of documentation regarding the activity of the charcoal used in the filter, and the inconsistency in product designs used between the various different disciplines (chemistry, pre-clinical, clinical and epidemiology) that have conducted studies with charcoal filtered cigarettes. There do not appear to be any published studies using a combination of data from the different disciplines based on a consistently designed charcoal cigarette filter. Although the literature presently available would suggest that smoke filtration provided by current charcoal filter techniques alone may not be substantial enough to reduce smoking-related disease, the data are limited. Therefore, for the reduction of smoking-induced disease, it is difficult to come to a definitive conclusion regarding the potential health benefits of using charcoal as a smoke filtration technology. PMID:18289753

  2. Quantitative Infrared Spectra of Vapor Phase Chemical Agents

    SciTech Connect

    Sharpe, Steven W.; Johnson, Timothy J.; Chu, P. M.; Kleimeyer, J.; Rowland, Brad

    2003-08-01

    Quantitative, moderately high resolution (0.1 cm-1) infrared spectra have been acquired for a number of nitrogen broadened (1 atm N2) vapor phase chemicals including: Sarin (GB), Soman (GD), Tabun (GA), Cyclosarin (GF), VX, Nitrogen Mustard (HN3), Sulfur Mustard (HD), and Lewisite (L). The spectra are acquired using a heated, flow-through White Cell1 of 5.6 meter optical path length. Each reported spectrum represents a statistical fit to Beer’s law, which allows for a rigorous calculation of uncertainty in the absorption coefficients. As part of an ongoing collaboration with the National Institute of Standards and Technology (NIST), cross-laboratory validation is a critical aspect of this work. In order to identify possible errors in the Dugway flow-through system, quantitative spectra of isopropyl alcohol from both NIST and Pacific Northwest National Laboratory (PNNL) are compared to similar data taken at Dugway proving Grounds (DPG).

  3. Synthesis, characterization of WS2 nanostructures by vapor phase deposition

    NASA Astrophysics Data System (ADS)

    Fan, Yinping; Li, Jun; Hao, Guolin; Luo, Siwei; Tang, Chao; Zhong, Jianxin

    2015-02-01

    Ultrathin two-dimensional WS2 nanostructures with various morphologies have been prepared on SiO2/Si (300 nm) and sapphire substrates by vapor phase deposition method. Simultaneously, tungsten nanostructures have also been obtained during the growth process. The nanostructures and morphologies of as-prepared products were systematically characterized by employing atomic force microscopy, Raman spectroscopy as well as scanning electron spectroscopy. The electrostatic properties of WS2 nanostructures were investigated exhibiting uniform surface potential and charge distributions. We have also detected the photoluminescence properties of WS2 nanostructures, which are dependent on the thickness and nanostructures of synthesized WS2. These results suggest that the optoelectronic properties of WS2 nanostructures can be effectively tuned by quantum confinement effect and nanostructures.

  4. Liquid-vapor phase equilibrium in a tin-selenium system

    NASA Astrophysics Data System (ADS)

    Volodin, V. N.; Burabaeva, N. M.; Trebukhov, S. A.

    2014-12-01

    Based on the pressure of the saturated vapor and components over liquid alloys in a tin-selenium system, determined using the boiling points approach (isothermal variant), its boiling point and corresponding vapor phase composition are calculated in the region of liquid solutions. The phase diagram is supple-mented with the liquid-vapor phase transition under atmospheric pressure and in vacuums of 100 and 10 Pa with the boundaries of the region in which the regions of liquid and vapor coexist being determined.

  5. Cigarette Smoke Analysis Using an Inexpensive Gas-Phase IR Cell

    NASA Astrophysics Data System (ADS)

    Garizi, N.; Macias, A.; Furch, Toran; Fan, R.; Wagenknecht, Paul S.; Singmaster, K. A.

    2001-12-01

    An inexpensive, break-resistant IR gas cell has been constructed using a PVC compression tee. The cell allows for multiple experiments to be performed in freshman chemistry and advanced lab courses. The PVC cell can be assembled by the students and then dismantled and cleaned after their experiments are completed. This cell has been successfully used to analyze some of the components of cigarette smoke and car exhaust.

  6. Airborne and vapor phase hydrocarbons over the Mediterranean Sea

    SciTech Connect

    Marie-Alexandrine, S.; Jean-Claude, M.; Anne, L.; Alain, S.

    1990-11-01

    n-Alkane distributions and concentrations have been determined in the atmospheric particulate and gas phases for samples collected over the Mediterranean Sea. Distributions of airborne alkanes exhibited a strong odd to even predominance in the C{sub 22}-C{sub 38} range associated with the presence of unresolved compounds indicating a mixture of terrigenous and anthropogenic inputs. Variations in their concentration levels could be related to the origin of air masses. Solvent extractable gas phase n-alkanes dominated in the C{sub 15}-C{sub 22} range with a slight predominance of n-C{sub 17} except in one sample were C{sub 18} and C{sub 20} were dominant. A hump of unresolved compounds shifted toward low molecular weight was observed in all the samples. The origin of vapor phase hydrocarbons is discussed with respect to the composition of seawater samples collected during the same cruise. From lifetime and transport time considerations as well as distribution features, both marine and continental origins, as distribution features, both marine and continental origins, likely anthropogenic, are suggested. The strong terrigenous signal of the suspended particles in the microlayer and underlying waters is attributed to aerosol deposition. The dissolved alkane compositional feature suggested both marine and anthropogenic sources.

  7. Irritants in cigarette smoke plumes

    SciTech Connect

    Ayer, H.E.; Yeager, D.W.

    1982-11-01

    Concentrations of the irritants formaldehyde and acrolein in side stream cigarette smoke plumes are up to three orders of magnitude above occupational limits, readily accounting for eye and nasal irritation. ''Low-tar'' cigarettes appear at least as irritating as other cigarettes. More than half the irritant is associated with the particulate phase of the smoke, permitting deposition throughout the entire respiratory tract and raising the issue of whether formaldehyde in smoke is associated with bronchial cancer.

  8. Vapors Produced by Electronic Cigarettes and E-Juices with Flavorings Induce Toxicity, Oxidative Stress, and Inflammatory Response in Lung Epithelial Cells and in Mouse Lung

    PubMed Central

    Lerner, Chad A.; Sundar, Isaac K.; Yao, Hongwei; Gerloff, Janice; Ossip, Deborah J.; McIntosh, Scott; Robinson, Risa; Rahman, Irfan

    2015-01-01

    Oxidative stress and inflammatory response are the key events in the pathogenesis of chronic airway diseases. The consumption of electronic cigarettes (e-cigs) with a variety of e-liquids/e-juices is alarmingly increasing without the unrealized potential harmful health effects. We hypothesized that electronic nicotine delivery systems (ENDS)/e-cigs pose health concerns due to oxidative toxicity and inflammatory response in lung cells exposed to their aerosols. The aerosols produced by vaporizing ENDS e-liquids exhibit oxidant reactivity suggesting oxidants or reactive oxygen species (OX/ROS) may be inhaled directly into the lung during a “vaping” session. These OX/ROS are generated through activation of the heating element which is affected by heating element status (new versus used), and occurs during the process of e-liquid vaporization. Unvaporized e-liquids were oxidative in a manner dependent on flavor additives, while flavors containing sweet or fruit flavors were stronger oxidizers than tobacco flavors. In light of OX/ROS generated in ENDS e-liquids and aerosols, the effects of ENDS aerosols on tissues and cells of the lung were measured. Exposure of human airway epithelial cells (H292) in an air-liquid interface to ENDS aerosols from a popular device resulted in increased secretion of inflammatory cytokines, such as IL-6 and IL-8. Furthermore, human lung fibroblasts exhibited stress and morphological change in response to treatment with ENDS/e-liquids. These cells also secrete increased IL-8 in response to a cinnamon flavored e-liquid and are susceptible to loss of cell viability by ENDS e-liquids. Finally, exposure of wild type C57BL/6J mice to aerosols produced from a popular e-cig increase pro-inflammatory cytokines and diminished lung glutathione levels which are critical in maintaining cellular redox balance. Thus, exposure to e-cig aerosols/juices incurs measurable oxidative and inflammatory responses in lung cells and tissues that could lead to unrealized health consequences. PMID:25658421

  9. Vapor phase elemental sulfur amendment for sequestering mercury in contaminated soil

    DOEpatents

    Looney, Brian B.; Denham, Miles E.; Jackson, Dennis G.

    2014-07-08

    The process of treating elemental mercury within the soil is provided by introducing into the soil a heated vapor phase of elemental sulfur. As the vapor phase of elemental sulfur cools, sulfur is precipitated within the soil and then reacts with any elemental mercury thereby producing a reaction product that is less hazardous than elemental mercury.

  10. Chirality-Dependent Vapor-Phase Epitaxial Growth and Termination of Single-Wall Carbon Nanotubes

    E-print Network

    Zhou, Chongwu

    -wall carbon nano- tubes are highly desired for both fundamental study and many of their technologicalChirality-Dependent Vapor-Phase Epitaxial Growth and Termination of Single-Wall Carbon Nanotubes-controlled carbon nanotube synthesis. Nevertheless, the yield of vapor-phase epitaxial growth is rather limited

  11. VAPOR-PHASE 2,3,7,8-TCDD SORPTION TO PLANT FOILAGE - A SPECIES COMPARISON

    EPA Science Inventory

    Plant uptake rate constants (k1) were determined for vapor-phase 2,3,7,8-TCDD using grass, azalea, spruce, kale and pepper foliage, and the fruit from apple, tomato and pepper. lants were exposed to vapor-phase 3H-2,3,7,8-TCDD for 96 h, and the TCDD sorption rate constant for eac...

  12. Toxicological considerations on the use of propylene glycol as a humectant in cigarettes.

    PubMed

    Gaworski, Charles L; Oldham, Michael J; Coggins, Christopher R E

    2010-02-28

    Propylene glycol (PG) is a humectant commonly used in cigarettes. Previous toxicological examinations of the effects on the addition of PG to tobacco used mixtures with several other flavoring agents. In the present work, toxicological comparisons were made of experimental cigarettes containing no added PG against otherwise similar cigarettes with three different amounts of PG added to the tobacco. The main toxicological comparison was a sub-chronic inhalation study with mainstream smoke in Sprague-Dawley rats (exposures of 150 mg/m(3) of total particulate matter, 6h exposure per day, for 90 consecutive days). The target PG concentrations in the tobacco of the four cigarette types were 0, 4, 7 and 10%. Additional studies with mainstream smoke were bacterial mutagenicity (5 Salmonella strains, both with and without metabolic activation, particulate phase only), cytotoxicity of both particulate and gas/vapor phases (using the neutral red uptake assay), and analytical chemistry (41 analytes). The graded inclusion of PG into experimental cigarettes resulted in increases in the smoke concentrations of propylene oxide, at very low concentrations. Broadly similar responses were seen across the four cigarette types, and the responses were similar to those previously described in the scientific literature. The addition of PG to experimental cigarettes reduced concentrations of some smoke components (e.g. nicotine), but had minimal effects on the biological responses. Most of the changes produced in the 90-days of exposure were resolved in a 42-day post-inhalation period. PMID:20079797

  13. Use of electronic cigarettes (e-cigarettes) impairs indoor air quality and increases FeNO levels of e-cigarette consumers.

    PubMed

    Schober, Wolfgang; Szendrei, Katalin; Matzen, Wolfgang; Osiander-Fuchs, Helga; Heitmann, Dieter; Schettgen, Thomas; Jörres, Rudolf A; Fromme, Hermann

    2014-07-01

    Despite the recent popularity of e-cigarettes, to date only limited data is available on their safety for both users and secondhand smokers. The present study reports a comprehensive inner and outer exposure assessment of e-cigarette emissions in terms of particulate matter (PM), particle number concentrations (PNC), volatile organic compounds (VOC), polycyclic aromatic hydrocarbons (PAH), carbonyls, and metals. In six vaping sessions nine volunteers consumed e-cigarettes with and without nicotine in a thoroughly ventilated room for two hours. We analyzed the levels of e-cigarette pollutants in indoor air and monitored effects on FeNO release and urinary metabolite profile of the subjects. For comparison, the components of the e-cigarette solutions (liquids) were additionally analyzed. During the vaping sessions substantial amounts of 1,2-propanediol, glycerine and nicotine were found in the gas-phase, as well as high concentrations of PM2.5 (mean 197 ?g/m(3)). The concentration of putative carcinogenic PAH in indoor air increased by 20% to 147 ng/m(3), and aluminum showed a 2.4-fold increase. PNC ranged from 48,620 to 88,386 particles/cm(3) (median), with peaks at diameters 24-36 nm. FeNO increased in 7 of 9 individuals. The nicotine content of the liquids varied and was 1.2-fold higher than claimed by the manufacturer. Our data confirm that e-cigarettes are not emission-free and their pollutants could be of health concern for users and secondhand smokers. In particular, ultrafine particles formed from supersaturated 1,2-propanediol vapor can be deposited in the lung, and aerosolized nicotine seems capable of increasing the release of the inflammatory signaling molecule NO upon inhalation. In view of consumer safety, e-cigarettes and nicotine liquids should be officially regulated and labeled with appropriate warnings of potential health effects, particularly of toxicity risk in children. PMID:24373737

  14. Are E-cigarettes a safe and good alternative to cigarette smoking?

    PubMed

    Rom, Oren; Pecorelli, Alessandra; Valacchi, Giuseppe; Reznick, Abraham Z

    2015-03-01

    Electronic cigarettes (E-cigarettes) are devices that can vaporize a nicotine solution combined with liquid flavors instead of burning tobacco leaves. Since their emergence in 2004, E-cigarettes have become widely available, and their use has increased exponentially worldwide. E-cigarettes are aggressively advertised as a smoking cessation aid; as healthier, cheaper, and more socially acceptable than conventional cigarettes. In recent years, these claims have been evaluated in numerous studies. This review explores the development of the current E-cigarette and its market, prevalence of awareness, and use. The review also explores the beneficial and adverse effects of E-cigarettes in various aspects in accordance with recent research. The discussed aspects include smoking cessation or reduction and the health risks, social impact, and environmental consequences of E-cigarettes. PMID:25557889

  15. Menthol Cigarettes

    MedlinePLUS

    ... documents showed that, in the past, the tobacco industry has a history of marketing menthol cigarettes to women, youth, and minority racial/ ... and G.N. Connolly, The menthol smoker: tobacco industry research on consumer ... The marketing of menthol cigarettes in the United States: populations, ...

  16. VaporLiquidSolid and VaporSolid Growth of Phase-Change Sb2Te3 Nanowires and Sb2Te3/GeTe Nanowire

    E-print Network

    Yu, Dong

    these materials can be the basis of data storage media such as CD/DVD3 and phase- change random access memoryVapor­Liquid­Solid and Vapor­Solid Growth of Phase-Change Sb2Te3 Nanowires and Sb2Te3/GeTe Nanowire-switching behavior. Introduction Chalcogenides exhibit a reversible crystalline-amorphous phase change induced

  17. Underwater vapor phase burning of aluminum particles and on aluminum ignition during steam explosions

    SciTech Connect

    Epstein, M. [Fauske and Associates, Inc., Burr Ridge, IL (United States)

    1991-09-01

    Recently reported experimental studies on aluminum-water steam explosions indicate that there may be a critical metal temperature at which the process changes over from a physical explosion to one which is very violent and involves the rapid liberation of chemical energy. In this report we examine the hypothesis that vapor-phase burning of aluminum is a necessary condition for the occurrence of such ``ignition-type`` steam explosions. An available two-phase stagnation flow film-boiling model is used to calculate the steam flux to the vaporizing aluminum surface. Combining this calculation with the notion that there is an upper limit to the magnitude of the metal vaporization rate at which the reaction regime must change from vapor phase to surface burning, leads to prediction of the critical metal surface temperature below which vapor phase burning is impossible. The critical temperature is predicted for both the aluminum-water pre-mixture configuration in which coarse drops of aluminum are falling freely through water and for the finely-fragmented aluminum drops in the wake of the pressure shock that ``triggers`` the explosion. Vapor phase burning is predicted to be possible during the pre-mixture phase but not very likely during the trigger phase of a steam explosion. The implications of these findings in terms of the validity of the hypothesis that ignition may begin with the vapor phase burning of aluminum is discussed. Recently postulated, alternative mechanisms of underwater aluminum ignition are also discussed.

  18. Underwater vapor phase burning of aluminum particles and on aluminum ignition during steam explosions

    SciTech Connect

    Epstein, M. (Fauske and Associates, Inc., Burr Ridge, IL (United States))

    1991-09-01

    Recently reported experimental studies on aluminum-water steam explosions indicate that there may be a critical metal temperature at which the process changes over from a physical explosion to one which is very violent and involves the rapid liberation of chemical energy. In this report we examine the hypothesis that vapor-phase burning of aluminum is a necessary condition for the occurrence of such ignition-type'' steam explosions. An available two-phase stagnation flow film-boiling model is used to calculate the steam flux to the vaporizing aluminum surface. Combining this calculation with the notion that there is an upper limit to the magnitude of the metal vaporization rate at which the reaction regime must change from vapor phase to surface burning, leads to prediction of the critical metal surface temperature below which vapor phase burning is impossible. The critical temperature is predicted for both the aluminum-water pre-mixture configuration in which coarse drops of aluminum are falling freely through water and for the finely-fragmented aluminum drops in the wake of the pressure shock that triggers'' the explosion. Vapor phase burning is predicted to be possible during the pre-mixture phase but not very likely during the trigger phase of a steam explosion. The implications of these findings in terms of the validity of the hypothesis that ignition may begin with the vapor phase burning of aluminum is discussed. Recently postulated, alternative mechanisms of underwater aluminum ignition are also discussed.

  19. Electronic cigarettes. Potential harms and benefits.

    PubMed

    Drummond, M Bradley; Upson, Dona

    2014-02-01

    Use of electronic cigarettes, devices that deliver a nicotine-containing vapor, has increased rapidly across the country and globally. Perceived and marketed as a "healthier alternative" to conventional cigarettes, few data exist regarding the safety of these devices and their efficacy in harm reduction and treatment of tobacco dependence; even less is known about their overall impact on population health. This review highlights the recent data regarding electronic cigarette toxicity, impact on lung function, and efficacy in smoking reduction and cessation. Studies show that the vapor generated from electronic cigarettes has variable amounts of nicotine and potential harmful toxins, albeit at levels lower than in conventional cigarettes. The long-term carcinogenic and lung function effects of electronic cigarettes are not known. Although some data demonstrate that electronic cigarettes may be effective in reducing conventional cigarette consumption, there are no data demonstrating the efficacy of electronic cigarettes as a tool to achieve cessation. Until robust longitudinal evaluations demonstrate the safety of electronic cigarettes and efficacy in treatment of tobacco dependence, their role as a harm reduction tool is unclear. PMID:24575993

  20. A liquid vapor phase transition in quantum statistical F. Baffioni, T. Kuna, I. Merola, and E. Presutti

    E-print Network

    A liquid vapor phase transition in quantum statistical mechanics F. Baffioni, T. Kuna, I. Merola, and E. Presutti Abstract. We prove a liquid vapor phase transition for a quantum system of particles the van der Waals theory of liquid vapor phase transitions, and indeed the limit 0, after

  1. Continuous determination of high-vapor-phase concentrations of tetrachloroethylene using on-line mass spectrometry.

    PubMed

    Fine, Dennis; Brooks, Michael C; Bob, Mustafa; Mravik, Susan; Wood, Lynn

    2008-02-15

    A method was developed to determine the vapor concentration of tetrachloroethylene (PCE) at and below its equilibrium vapor-phase concentration, 168 000 microg/L (25 degrees C). Vapor samples were drawn by vacuum into a six-port sampling valve and injected through a jet separator into an ion trap mass spectrometer (MS). This on-line MS can continuously sample a vapor stream and provide vapor concentrations every 30 s. Calibration of the instrument was done by creating a saturated stream of PCE vapor, sampling the vapor with the on-line MS and with thermal desorption tubes, and correlating the peak area response from the MS with the vapor concentration determined by automated thermal desorption gas chromatography mass spectrometry. Dilution of the saturated stream provided lower concentrations of PCE vapor. The method was developed to monitor the vapor concentration of PCE that was sparged from a two-dimensional flow chamber and for determination of the total PCE mass removed during each sparge event. The method has potential application for analysis of gas-phase tracers. PMID:18205332

  2. Numerical Modeling of Liquid-Vapor Phase Change

    NASA Technical Reports Server (NTRS)

    Esmaeeli, Asghar; Arpaci, Vedat S.

    2001-01-01

    We implemented a two- and three-dimensional finite difference/front tracking technique to solve liquid-vapor phase change problems. The mathematical and the numerical features of the method were explained in great detail in our previous reports, Briefly, we used a single formula representation which incorporated jump conditions into the governing equations. The interfacial terms were distributed as singular terms using delta functions so that the governing equations would be the same as conventional conservation equations away from the interface and in the vicinity of the interface they would provide correct jump conditions. We used a fixed staggered grid to discretize these equations and an unstructured grid to explicitly track the front. While in two dimensions the front was simply a connection of small line segments, in three dimensions it was represented by a connection of small triangular elements. The equations were written in conservative forms and during the course of computations we used regriding to control the size of the elements of the unstructured grid. Moreover, we implemented a coalescence in two dimensions which allowed the merging of different fronts or two segments of the same front when they were sufficiently close. We used our code to study thermocapillary migration of bubbles, burst of bubbles at a free surface, buoyancy-driven interactions of bubbles, evaporation of drops, rapid evaporation of an interface, planar solidification of an undercooled melt, dendritic solidification, and a host of other problems cited in the reference.

  3. Comparison of environmental tobacco smoke (ETS) concentrations generated by an electrically heated cigarette smoking system and a conventional cigarette.

    PubMed

    Tricker, Anthony R; Schorp, Matthias K; Urban, Hans-Jörg; Leyden, Donald; Hagedorn, Heinz-Werner; Engl, Johannes; Urban, Michael; Riedel, Kirsten; Gilch, Gerhard; Janket, Dinamis; Scherer, Gerhard

    2009-01-01

    Smoking conventional lit-end cigarettes results in exposure of nonsmokers to potentially harmful cigarette smoke constituents present in environmental tobacco smoke (ETS) generated by sidestream smoke emissions and exhaled mainstream smoke. ETS constituent concentrations generated by a conventional lit-end cigarette and a newly developed electrically heated cigarette smoking system (EHCSS) that produces only mainstream smoke and no sidestream smoke emissions were investigated in simulated "office" and "hospitality" environments with different levels of baseline indoor air quality. Smoking the EHCSS (International Organisation for Standardization yields: 5 mg tar, 0.3 mg nicotine, and 0.6 mg carbon monoxide) in simulated indoor environments resulted in significant reductions in ETS constituent concentrations compared to when smoking a representative lit-end cigarette (Marlboro: 6 mg tar, 0.5 mg nicotine, and 7 mg carbon monoxide). In direct comparisons, 24 of 29 measured smoke constituents (83%) showed mean reductions of greater than 90%, and 5 smoke constituents (17%) showed mean reductions between 80% and 90%. Gas-vapor phase ETS markers (nicotine and 3-ethenylpyridine) were reduced by an average of 97% (range 94-99%). Total respirable suspended particles, determined by online particle measurements and as gravimetric respirable suspended particles, were reduced by 90% (range 82-100%). The mean and standard deviation of the reduction of all constituents was 94 +/- 4%, indicating that smoking the new EHCSS in simulated "office" and "hospitality" indoor environments resulted in substantial reductions of ETS constituents in indoor air. PMID:18951229

  4. In vitro micronucleus assay for cigarette smoke using a whole smoke exposure system: A comparison of smoking regimens

    Microsoft Academic Search

    Kosuke Okuwa; Masahiro Tanaka; Yasuo Fukano; Hidenori Nara; Yosuke Nishijima; Tomoki Nishino

    2010-01-01

    Previous studies on the biological assessment of cigarette smoke (CS) mainly focused on the total particulate matter (TPM) collected using a Cambridge filter or gas vapor phase (GVP) bubbled through phosphate-buffered saline (PBS). To study the effects of native CS in vitro, direct exposure methods have been developed. Meanwhile, in vitro micronucleus (MN) assays have been reported to evaluate the

  5. Using vapor phase tomography to measure the spatial distribution of vapor concentrations and flux for vadose-zone VOC sources

    NASA Astrophysics Data System (ADS)

    Mainhagu, J.; Morrison, C.; Brusseau, M. L.

    2015-06-01

    A test was conducted at a chlorinated-solvent contaminated site in Tucson, AZ, to evaluate the effectiveness of vapor-phase tomography (VPT) for characterizing the distribution of volatile organic contaminants (VOC) in the vadose zone. A soil vapor extraction (SVE) system has been in operation at the site since 2007. Vapor concentration and vacuum pressure were measured at four different depths in each of the four monitoring wells surrounding the extraction well. The test provided a 3D characterization of local vapor concentrations under induced-gradient conditions. Permeability data obtained from analysis of borehole logs were used along with pressure and the vapor-concentration data to determine VOC mass flux within the test domain. A region of higher mass flux was identified in the deepest interval of the S-SW section of the domain, indicating the possible location of a zone with greater contaminant mass. These results are consistent with the TCE-concentration distribution obtained from sediment coring conducted at the site. In contrast, the results of a standard soil gas survey did not indicate the presence of a zone with greater contaminant mass. These results indicate that the VPT test provided a robust characterization of VOC concentration and flux distribution at the site.

  6. Using vapor phase tomography to measure the spatial distribution of vapor concentrations and flux for vadose-zone VOC sources.

    PubMed

    Mainhagu, J; Morrison, C; Brusseau, M L

    2015-01-01

    A test was conducted at a chlorinated-solvent contaminated site in Tucson, AZ, to evaluate the effectiveness of vapor-phase tomography (VPT) for characterizing the distribution of volatile organic contaminants (VOC) in the vadose zone. A soil vapor extraction (SVE) system has been in operation at the site since 2007. Vapor concentration and vacuum pressure were measured at four different depths in each of the four monitoring wells surrounding the extraction well. The test provided a 3D characterization of local vapor concentrations under induced-gradient conditions. Permeability data obtained from analysis of borehole logs were used along with pressure and the vapor-concentration data to determine VOC mass flux within the test domain. A region of higher mass flux was identified in the deepest interval of the S-SW section of the domain, indicating the possible location of a zone with greater contaminant mass. These results are consistent with the TCE-concentration distribution obtained from sediment coring conducted at the site. In contrast, the results of a standard soil gas survey did not indicate the presence of a zone with greater contaminant mass. These results indicate that the VPT test provided a robust characterization of VOC concentration and flux distribution at the site. PMID:25835545

  7. The intractable cigarette ‘filter problem’

    PubMed Central

    2011-01-01

    Background When lung cancer fears emerged in the 1950s, cigarette companies initiated a shift in cigarette design from unfiltered to filtered cigarettes. Both the ineffectiveness of cigarette filters and the tobacco industry's misleading marketing of the benefits of filtered cigarettes have been well documented. However, during the 1950s and 1960s, American cigarette companies spent millions of dollars to solve what the industry identified as the ‘filter problem’. These extensive filter research and development efforts suggest a phase of genuine optimism among cigarette designers that cigarette filters could be engineered to mitigate the health hazards of smoking. Objective This paper explores the early history of cigarette filter research and development in order to elucidate why and when seemingly sincere filter engineering efforts devolved into manipulations in cigarette design to sustain cigarette marketing and mitigate consumers' concerns about the health consequences of smoking. Methods Relevant word and phrase searches were conducted in the Legacy Tobacco Documents Library online database, Google Patents, and media and medical databases including ProQuest, JSTOR, Medline and PubMed. Results 13 tobacco industry documents were identified that track prominent developments involved in what the industry referred to as the ‘filter problem’. These reveal a period of intense focus on the ‘filter problem’ that persisted from the mid-1950s to the mid-1960s, featuring collaborations between cigarette producers and large American chemical and textile companies to develop effective filters. In addition, the documents reveal how cigarette filter researchers' growing scientific knowledge of smoke chemistry led to increasing recognition that filters were unlikely to offer significant health protection. One of the primary concerns of cigarette producers was to design cigarette filters that could be economically incorporated into the massive scale of cigarette production. The synthetic plastic cellulose acetate became the fundamental cigarette filter material. By the mid-1960s, the meaning of the phrase ‘filter problem’ changed, such that the effort to develop effective filters became a campaign to market cigarette designs that would sustain the myth of cigarette filter efficacy. Conclusions This study indicates that cigarette designers at Philip Morris, British-American Tobacco, Lorillard and other companies believed for a time that they might be able to reduce some of the most dangerous substances in mainstream smoke through advanced engineering of filter tips. In their attempts to accomplish this, they developed the now ubiquitous cellulose acetate cigarette filter. By the mid-1960s cigarette designers realised that the intractability of the ‘filter problem’ derived from a simple fact: that which is harmful in mainstream smoke and that which provides the smoker with ‘satisfaction’ are essentially one and the same. Only in the wake of this realisation did the agenda of cigarette designers appear to transition away from mitigating the health hazards of smoking and towards the perpetuation of the notion that cigarette filters are effective in reducing these hazards. Filters became a marketing tool, designed to keep and recruit smokers as consumers of these hazardous products. PMID:21504917

  8. VAPOR-PHASE DECONTAMINATION OF APPLES CONTAINING ESCHERICHIA COLI

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Improved methods of decontaminating apples containing human pathogens are required. In this investigation, application of gaseous antimicrobial agents was investigated. An apparatus, which transfers vapor from hot antimicrobial solutions to a treatment vessel, was evaluated with Golden Delicious app...

  9. E-cigarettes: a rapidly growing Internet phenomenon.

    PubMed

    Yamin, Cyrus K; Bitton, Asaf; Bates, David W

    2010-11-01

    Electronic cigarettes (e-cigarettes) aerosolize nicotine and produce a vapor that emulates that of cigarettes but purportedly has fewer traditional toxins than secondhand smoke. Although e-cigarettes are widely sold online and by retailers, new research suggests that they may contain unexpected toxins and may provide unreliable nicotine delivery. Many countries have already banned or strictly regulated e-cigarettes. Currently in the United States, e-cigarettes are exempt from regulation as drug-delivery devices. Meanwhile, the presence of e-cigarettes on the Internet, including in Web searches, virtual user communities, and online stores where people sell e-cigarettes on commission, is increasing rapidly. Physicians should be aware of the popularity, questionable efficacy claims, and safety concerns of e-cigarettes so that they may counsel patients against use and advocate for research to inform an evidence-based regulatory approach. PMID:21041581

  10. Different pyrolytic pathways of levoglucosan in vapor- and liquid\\/solid-phases

    Microsoft Academic Search

    Takashi Hosoya; Haruo Kawamoto; Shiro Saka

    2008-01-01

    Influence of the amount of levoglucosan-loading on the pyrolysis behavior was studied in N2 at 400°C with a dual-space closed ampoule reactor. The results indicated that the pyrolytic pathways are different between vapor- and liquid\\/solid-phases. Relative contribution of these two pyrolysis conditions changed depending on the amount of levoglucosan-loading. In vapor-phase, levoglucosan was selectively converted to the non-condensable gas (mainly

  11. Smoke composition and predicting relationships for international commercial cigarettes smoked with three machine-smoking conditions.

    PubMed

    Counts, M E; Morton, M J; Laffoon, S W; Cox, R H; Lipowicz, P J

    2005-04-01

    The study objectives were to determine the effects of smoking machine puffing parameters on mainstream smoke composition and to express those effects as predicting relationships. Forty-eight commercial Philip Morris USA and Philip Morris International cigarettes from international markets and the 1R4F reference cigarette were machine-smoked using smoking conditions defined by the International Organization of Standardization (ISO), the Massachusetts Department of Public Health (MDPH), and Health Canada (HC). Cigarette tobacco fillers were analyzed for nitrate, nicotine, tobacco-specific nitrosamines (TSNA), and ammonia. Mainstream yields for tar and 44 individual smoke constituents and "smoke pH" were determined. Cigarette constituent yields typically increased in the order ISOcigarettes with higher initial filter ventilation and were also generally greater for vapor-phase constituents than for particulate-phase constituents. Predicting relationships were developed between ISO tar and ISO, MDPH, and HC constituent yields and between MDPH tar and HC tar and respective smoking condition yields. MDPH and HC constituent yields could be predicted with similar reliability using ISO tar or the corresponding smoking-condition tar. The reliability of the relationships varied from strong to weak, depending on particular constituents. Weak predicting relationships for nitrogen oxides and TSNA's, for example, were improved with inclusion of tobacco filler composition factors. "Smoke pH" was similar for all cigarettes at any one smoking condition, and overall marginally lower at HC conditions than at ISO or MDPH conditions. PMID:15748796

  12. An optical measurement of the phase transition rate of a vapor in a shock tube

    SciTech Connect

    Fujikawa, S.; Kotani, M.; Sato, H. [Toyama Prefectural Univ. (Japan). Dept. of Mechanical Systems Engineering

    1994-12-31

    A shock-tube is applied to measure the rate of phase transition of vapor and the sticking probability (condensation coefficient) of vapor molecules. In order to measure them, an optical method using light sources with different wavelengths is used. It is clarified that the shock-tube can provide an ideal condition for the investigation of the phase transition and the sticking probability. The sticking probability of methanol vapor molecules is found to be around 0.3. This value is in rather good agreement with a value obtained by computer simulation based on molecular dynamics.

  13. Simple Vapor-Phase Synthesis of Single-Crystalline Ag Nanowires and Single-Nanowire Surface-Enhanced Raman Scattering

    E-print Network

    Ihee, Hyotcherl

    Simple Vapor-Phase Synthesis of Single-Crystalline Ag Nanowires and Single-Nanowire Surface, KRICT, Daejeon 305-600, Korea Received May 1, 2007; E-mail: bongsoo@kaist.ac.kr We report vapor scattering (SERS) of a single NW. To the best of our knowledge, vapor-phase synthesis of single

  14. Proceedings of the Symposium on Fundamental Gas-Phase and Surface Chemistry of Vapor-Phase Materials Synthesis,

    E-print Network

    Taylor, James H.

    Proceedings of the Symposium on Fundamental Gas-Phase and Surface Chemistry of Vapor-Phase Materials Synthesis, PV98-28, p. 153,The Electrochemical Society, 1998. IN SITU STUDIES OF TEOS/OZONE CVD, gas chromatographic and other evidence (5-9) supports the participation of transient gas phase

  15. Effect of filtration by activated charcoal on the toxicological activity of cigarette mainstream smoke from experimental cigarettes.

    PubMed

    Gaworski, Charles L; Schramke, Heike; Diekmann, Joerg; Meisgen, Thomas J; Tewes, Franz J; Veltel, Detlef J; Vanscheeuwijck, Patrick M; Rajendran, Narayanan; Muzzio, Miguel; Haussmann, Hans-Juergen

    2009-07-01

    Activated charcoal (AC) filtration reportedly decreases the yields of smoke vapor phase constituents including some identified as human carcinogens and respiratory irritants. Non-clinical studies including chemical smoke analysis, in vitro cytotoxicity and mutagenicity (bacterial and mammalian cells), and in vivo subchronic rat inhalation studies were carried out using machine smoking at ISO conditions with lit-end research cigarettes containing AC filters. The objective was to assess whether AC filter technology would alter the established toxicity profile of mainstream smoke by increasing or decreasing any known toxicological properties, or elicit new ones. The reduced yield of vapor phase irritants from AC filter cigarettes correlated with markedly decreased in vitro cytotoxicity and in vivo morphology of the nose and lower respiratory tract. Increased yields of particulate phase constituents (e.g. polycyclic aromatic hydrocarbons) in AC filtered smoke were noted in comparison to controls in some studies. The in vitro bacterial mutagenicity of AC filtered smoke particulate preparations was occasionally increased over control levels. Laryngeal epithelial thickness was increased in some rats inhaling AC filtered smoke in comparison to controls, an effect perhaps related to higher inspiratory flow. When tested under more intense Massachusetts Department of Public Health smoking conditions, AC filter associated reductions in vapor phase constituent yields were smaller than those seen with ISO conditions, but the effect on in vitro cytotoxicity remained. PMID:19555222

  16. REDOX AND ELECTROPHILIC PROPERTIES OF VAPOR- AND PARTICLE-PHASE COMPONENTS OF AMBIENT AEROSOLS

    PubMed Central

    Eiguren-Fernandez, Arantzazu; Shinyashiki, Masaru; Schmitz, Debra A.; DiStefano, Emma; Hinds, William; Kumagai, Yoshito; Cho, Arthur K.; Froines, John R.

    2010-01-01

    Particulate matter (PM) has been the primary focus of studies aiming to understand the relationship between the chemical properties of ambient aerosols and adverse health effects. Size and chemical composition of PM have been linked to their oxidative capacity which has been postulated to promote or exacerbate pulmonary and cardiovascular diseases. But in the last few years, new studies have suggested that volatile and semivolatile components may also contribute to many adverse health effects. The objectives of this study were: i) assess for the first time the redox and electrophilic potential of vapor-phase components of ambient aerosols, and ii) evaluate the relative contributions of particle- and vapor-fractions to the hazard of a given aerosol. To achieve these objectives vapor- and particle-phase samples collected in Riverside (CA) were subjected to three chemical assays to determine their redox and electrophilic capacities. The results indicate that redox active components are mainly associated with the particle-phase, while electrophilic compounds are found primarily in the vapor-phase. Vapor-phase organic extracts were also capable of inducing the stress responding protein, heme-oxygenase-1 (HO-1), in RAW264.7 murine macrophages. These results demonstrate the importance of volatile components in the overall oxidative and electrophilic capacity of aerosols, and point out the need for inclusion of vapors in future health and risk assessment studies. PMID:20152964

  17. Vapor-Phase Thermal Conductivity, Vapor Pressure, and Liquid Density of R365mfc

    Microsoft Academic Search

    Isabel M. Marrucho; Nelson S. Oliveira; Ralf Dohrn

    2002-01-01

    The thermal conductivity of a new fluoroalkane, R365mfc (1,1,1,3,3-pentafluorobutane), important for the production of polyurethane rigid foams, was measured using a transient hot wire method, at temp- eratures between 336.85 K and 377.4 K. The extended corresponding states theory was used successfully to predict the results, with an average absolute deviation of 0.5%. The vapor pressure (302.90 K to 358.15

  18. E-Cigarette Users Often Believe Devices Will Help Them Quit Tobacco

    MedlinePLUS

    E-Cigarette Users Often Believe Devices Will Help Them Quit Tobacco They also think vapor is less harmful ... 4, 2015 THURSDAY, June 4, 2015 (HealthDay News) -- E-cigarette users are much more hopeful that the devices ...

  19. Vapor Phase Transport Synthesis of Zeolites from Sol-Gel Precursors

    SciTech Connect

    THOMA,STEVEN G.; NENOFF,TINA M.

    2000-07-14

    A study of zeolite crystallization from sol-gel precursors using the vapor phase transport synthesis method has been performed. Zeolites (ZSM-5, ZSM-48, Zeolite P, and Sodalite) were crystallized by contacting vapor phase organic or organic-water mixtures with dried sodium silicate and dried sodium alumino-silicate gels. For each precursor gel, a ternary phase system of vapor phase organic reactant molecules was explored. The vapor phase reactant mixtures ranged from pure ethylene diamene, triethylamine, or water, to an equimolar mixture of each. In addition, a series of gels with varied physical and chemical properties were crystallized using the same vapor phase solvent mixture for each gel. The precursor gels and the crystalline products were analyzed via Scanning Electron Microscopy, Electron Dispersive Spectroscopy, X-ray mapping, X-ray powder diffraction, nitrogen surface area, Fourier Transform Infrared Spectroscopy, and thermal analyses. The product phase and purity as a function of the solvent mixture, precursor gel structure, and precursor gel chemistry is discussed.

  20. Student Understanding of Liquid-Vapor Phase Equilibrium

    ERIC Educational Resources Information Center

    Boudreaux, Andrew; Campbell, Craig

    2012-01-01

    Student understanding of the equilibrium coexistence of a liquid and its vapor was the subject of an extended investigation. Written assessment questions were administered to undergraduates enrolled in introductory physics and chemistry courses. Responses have been analyzed to document conceptual and reasoning difficulties in sufficient detail to…

  1. DETERMINING HOW VAPOR PHASE MTBE REACHES GROUND WATER

    EPA Science Inventory

    EPA Region 2 and ORD have funded a RARE project for FY 2005/2006 to evaluate the prospects that MTBE (and other fuel components) in vapors that escape from an underground storage tank (UST) can find its way to ground water produced by monitoring wells at a gasoline filling statio...

  2. Genetic toxicology studies comparing the activity of sidestream smoke from cigarettes which burn or only heat tobacco.

    PubMed

    Doolittle, D J; Lee, C K; Ivett, J L; Mirsalis, J C; Riccio, E; Rudd, C J; Burger, G T; Hayes, A W

    1990-02-01

    The results of in vitro genetic toxicology studies of sidestream cigarette smoke (SSCS) from cigarettes which heat but do not burn tobacco were compared to those of sidestream smoke from cigarettes which burn tobacco. SSCSs from 5 cigarettes were compared. Three of the cigarettes, the Kentucky reference research cigarette (1R4F), a commercially available ultra-low-tar brand (ULT) and a commercially available ultra-low-tar menthol brand (ULT-menthol) burn tobacco while two of the cigarettes, a regular (TEST) and a menthol (TEST-menthol) heat tobacco. SSCSs from all cigarettes were prepared by identical techniques, which involved collecting sidestream smoke particulate matter on Cambridge filter pads and combining the particulate matter with the vapor-phase materials collected by bubbling the smoke exiting the Cambridge pad through DMSO. The SSCSs obtained (equivalent to 0.4 cigarettes/ml DMSO) were evaluated at identical concentrations in an in vitro genetic toxicology test battery. SSCS from 1R4F, ULT and ULT-menthol cigarettes produced positive results in Ames bacterial strains TA98, TA100, TA1537 and TA1538 in the presence of metabolic activation (S9 from Aroclor-induced rat liver) but negative results in strain TA1535. In the absence of metabolic activation, 1R4F, ULT and ULT-menthol SSCSs were not significantly mutagenic. TEST and TEST-menthol SSCSs produced negative results in all 5 bacterial strains, both with and without metabolic activation. SSCS from 1R4F, ULT and ULT-menthol cigarettes produced positive results in the CHO chromosomal aberration assay and in the CHO sister-chromatid exchange assay both with and without metabolic activation while TEST and TEST-menthol SSCSs produced negative results in both assays, either with or without metabolic activation. The SSCSs from 1R4F, ULT and ULT-menthol cigarettes were weakly positive in inducing DNA repair in cultured rat hepatocytes while TEST and TEST-menthol SSCSs were negative in this assay. All 5 SSCSs were nonmutagenic in the CHO-HGPRT assay both with and without metabolic activation. SSCSs from the 1R4F, ULT and ULT-menthol cigarettes were cytotoxic in the CHO-HGPRT assay, both with and without metabolic activation, while TEST and TEST-menthol SSCSs were not cytotoxic under either condition. These results demonstrate that sidestream smoke from cigarettes which heat but do not burn tobacco (TEST and TEST-menthol) was neither genotoxic nor cytotoxic under conditions where sidestream smoke from cigarettes which burn tobacco (1R4F, ULT and ULT-menthol) was genotoxic and/or cytotoxic in a concentration-dependent manner. PMID:2300076

  3. Phase liquid-vapor equilibria and thermodynamic properties of solutions of n-propanol-aliphatic ketones

    NASA Astrophysics Data System (ADS)

    Suntsov, Yu. K.; Vlasov, M. V.; Chuikov, A. M.

    2015-06-01

    The boiling points of solutions of five binary systems are measured using the ebulliometric method in the pressure range of 4.4-101.3 kPa. Compositions of the equilibrium vapor phases of systems are calculated, based on the constructed pressure isotherms of saturated vapor. The values of excess Gibbs energy and the enthalpy and entropy of solutions are calculated from the data on the liquid-vapor equilibrium. The patterns of change in the phase equilibria and thermodynamic properties of the solutions are established, based on the composition and temperature of the systems. The liquid-vapor equilibrium of systems is described using the equations of Wilson and the NRTL (Non-Random Two-Liquid model).

  4. Phase conjugation using the surface nonlinearity of a dense potassium vapor

    Microsoft Academic Search

    Jeffery J. Maki; William V. Davis; Robert W. Boyd; J. E. Sipe

    1992-01-01

    We observe optical phase conjugation using the surface nonlinearity of a dense atomic potassium vapor. For an atomic number density of 1.5×1017 cm-3, phase-conjugate reflectivities of 4×10-5 are measured for pump intensities approaching the saturation intensity of 10 W cm-2. We also demonstrate aberration correction using surface phase conjugation. The measured properties of the surface-phase-conjugate signal are in excellent agreement

  5. In Situ Spectroscopic Investigation of Gas Phase Chemistry During Silicon Chemical Vapor Deposition

    Microsoft Academic Search

    James E. Maslar; Wilbur S. Hurst

    2003-01-01

    During silicon thermal chemical vapor deposition, reactions occurring in the gas phase above the wafer surface can strongly influence the deposited film quality. Depending on the process conditions, e.g., temperature, silicon precursor, carrier gas, pressure, etc., gas phase reactions can include not only precursor decomposition but also nucleation of silicon nanoparticles above the wafer surface. Optical diagnostics were employed to

  6. Investigation of large dynamic range helium II liquid\\/vapor phase separator for SIRTF

    Microsoft Academic Search

    A. Nakano; D. Petrac; C. Paine; M. Murakami

    1999-01-01

    A large dynamic range superfluid helium, helium II, liquid–vapor phase separator is required for the thermal design of the Space Infrared Telescope Facility (SIRTF). A porous plug type phase separator is adopted for SIRTF mission. A candidate porous plug was tested using two different types of experimental apparatus to obtain the exact flow characteristics. Mass flow rate, pressure and temperature

  7. Cigarette Money

    Microsoft Academic Search

    Kenneth Burdett; Alberto Trejos; Randall Wright

    2001-01-01

    We study how commodities emerge as money, the way cigarettes did in POW camps. We characterize how specialization, trading frictions, intrinsic properties of goods, and the amount of fiat money determine whether a commodity serves as money and its value. In some equilibria, the exchange value of commodity money is pinned down by its consumption value; in others, it is

  8. Vapor-crystal phase transition in synthesis of paracetamol films by vacuum evaporation and condensation

    NASA Astrophysics Data System (ADS)

    Belyaev, A. P.; Rubets, V. P.; Antipov, V. V.; Bordei, N. S.; Zarembo, V. I.

    2014-03-01

    We report on the structural and technological investigations of the vapor-crystal phase transition during synthesis of paracetamol films of the monoclinic system by vacuum evaporation and condensation in the temperature range 220-320 K. The complex nature of the transformation accompanied by the formation of a gel-like phase is revealed. The results are interpreted using a model according to which the vapor-crystal phase transition is not a simple first-order phase transition, but is a nonlinear superposition of two phase transitions: a first-order transition with a change in density and a second-order phase transition with a change in ordering. Micrographs of the surface of the films are obtained at different phases of formation.

  9. Se vapor pressure dependence of the phase diagram of the CuGa 1? x In x Se 2 system

    Microsoft Academic Search

    Hiroaki Matsushita; Takeo Takizawa

    1998-01-01

    Phase transition points of the CuGa1?xInxSe2 system are investigated by the differential thermal analysis with varying Se vapor pressure up to 760Torr. The phase diagrams constructed under controlled Se vapor pressure show that the solidus and liquidus points decrease more than 100°C with increasing Se vapor pressure, and that the temperature zone of the (sphalerite+liquid) phase narrows in the region

  10. A Preliminary Study on the Vapor/Mist Phase Lubrication of a Spur Gearbox

    NASA Technical Reports Server (NTRS)

    Morales, Wilfredo; Handschuh, Robert F.

    1999-01-01

    Organophosphates have been the primary compounds used in vapor/mist phase lubrication studies involving ferrous bearing material. Experimental results have indicated that the initial formation of an iron phosphate film on a rubbing ferrous surface, followed by the growth (by cationic diffusion) of a lubricious pyrophosphate-type coating over the iron phosphate, is the reason organophosphates work well as vapor/mist phase lubricants. Recent work, however, has shown that this mechanism leads to the depletion of surface iron atoms and to eventual lubrication failure. A new organophosphate formulation was developed which circumvents surface iron depletion. This formulation was tested by generating an iron phosphate coating on an aluminum surface. The new formulation was then used to vapor/mist phase lubricate a spur gearbox in a preliminary study.

  11. MEMS Lubrication by In-Situ Tribochemical Reactions From the Vapor Phase.

    SciTech Connect

    Dugger, Michael T.; Asay, David B.; Kim, Seong H.

    2008-01-01

    Vapor Phase Lubrication (VPL) of silicon surfaces with pentanol has been demonstrated. Two potential show stoppers with respect to application of this approach to real MEMS devices have been investigated. Water vapor was found to reduce the effectiveness of VPL with alcohol for a given alcohol concentration, but the basic reaction mechanism observed in water-free environments is still active, and devices operated much longer in mixed alcohol and water vapor environments than with chemisorbed monolayer lubricants alone. Complex MEMS gear trains were successfully lubricated with alcohol vapors, resulting in a factor of 104 improvement in operating life without failure. Complex devices could be made to fail if operated at much higher frequencies than previously used, and there is some evidence that the observed failure is due to accumulation of reaction products at deeply buried interfaces. However, if hypothetical reaction mechanisms involving heated surfaces are valid, then the failures observed at high frequency may not be relevant to operation at normal frequencies. Therefore, this work demonstrates that VPL is a viable approach for complex MEMS devices in conventional packages. Further study of the VPL reaction mechanisms are recommended so that the vapor composition may be optimized for low friction and for different substrate materials with potential application to conventionally fabricated, metal alloy parts in weapons systems. Reaction kinetics should be studied to define effective lubrication regimes as a function of the partial pressure of the vapor phase constituent, interfacial shear rate, substrate composition, and temperature.

  12. Experimental studies on nucleation, nanoparticle's formation and polymerization from the vapor phase

    NASA Astrophysics Data System (ADS)

    Abdelsayed, Victor Maher

    This research is divided into three major parts. In part I, the critical supersaturations required for the homogeneous nucleation of 2,2,2-trifluorothanol (TFE) vapor have been measured over a temperature range (266-296 K) using an upward thermal diffusion cloud chamber (DCC). The measured supersaturations are in agreement with the predictions of both the classical and the scaled theory of nucleation. Moreover, the condensation of supersaturated TFE vapor on laser-vaporized magnesium nanoparticles has been studied under different experimental conditions, such as the supersaturation, the pressure and the electric field. In part II, the laser vaporization controlled condensation (LVCC) technique was used to prepare Au-Ag alloy nanoparticles in the vapor phase using designed targets of compressed Au and Ag micron-sized powder mixtures of selected composition. The results showed that the optical properties of these nanoparticles could be tuned depending on the alloy composition and the laser wavelength. Different intermetallic nanoparticles (FeAl and NiAl) from the vapor phase has also been prepared, using the same approach. In this work, the fraction of the charged particles generated during the laser vaporization process was used to prepare a new class of nanoparticle assemblies in the LVCC chamber under the influence of an electric field. The results showed that the electric field required to induce the formation of these nanoassemblies is material and field dependent. By coupling the LVCC chamber with the differential mobility analyzer, size-selected nanoparticles have been prepared in the vapor phase. The prepared nanoparticles were characterized by different techniques such as scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV-visible spectroscopy. In part III, new methods were developed to prepare nanoparticle-polymer composites from the vapor phase. In the first method, the LVCC method was used to prepare a carbonaceous cross-linked resin, with different nanoparticles (Ni, Pt and FeAl) embedded inside. In the second method, free radical-thermally initiated polymerization was used to polymerize a monomer vapor of styrene on the surfaces of activated Ni nanoparticles.

  13. Vapor phase synthesis of crystalline nanometer-scale GaAs clusters Winston A. Saunders, Peter C. Sercel, Harry A. Atwater,

    E-print Network

    Atwater, Harry

    Vapor phase synthesis of crystalline nanometer-scale GaAs clusters Winston A. Saunders, Peter C of a nonequilibrium vapor created by the explosive vaporization of a bulk GaAs sample in an inert atmosphere. High nucleation from a nonequilibrium vapor produced by the explosive vaporization of a bulk "wire" of Ga

  14. "Light" Cigarettes and Cancer Risk

    MedlinePLUS

    "Light" Cigarettes and Cancer Risk On This Page What is a so-called light cigarette? Are light cigarettes less hazardous than regular cigarettes? Do light cigarettes cause cancer? What were the tar yield ...

  15. ZnO quantum dots synthesized by a vapor phase transport process J. G. Lu, Z. Z. Ye,a

    E-print Network

    Wang, Zhong L.

    ZnO quantum dots synthesized by a vapor phase transport process J. G. Lu, Z. Z. Ye,a J. Y. Huang, L; published online 8 February 2006 A vapor phase transport growth process has been developed to synthesize ZnO quantum dots QDs on Si substrates. The characteristics were investigated for as-prepared ZnO QDs without

  16. Substrate effect on CdTe layers grown by metalorganic vapor phase N. V. Sochinskiia),b)

    E-print Network

    Viña, Luis

    Substrate effect on CdTe layers grown by metalorganic vapor phase epitaxy N. V. Sochinskiia for publication 30 December 1996 CdTe layers were grown by metalorganic vapor phase epitaxy MOVPE on different substrates like sapphire, GaAs, and CdTe wafers. The growth was carried out at the temperature 340 °C

  17. Simplified thermodynamic functions for vapor-liquid phase separation and fountain effect pumps

    NASA Technical Reports Server (NTRS)

    Yuan, S. W. K.; Hepler, W. A.; Frederking, T. H. K.

    1984-01-01

    He-4 fluid handling devices near 2 K require novel components for non-Newtonian fluid transport in He II. Related sizing of devices has to be based on appropriate thermophysical property functions. The present paper presents simplified equilibrium state functions for porous media components which serve as vapor-liquid phase separators and fountain effect pumps.

  18. Stimulated topological condensation of ``vapor phase'' photons and possible implications for space power technology

    Microsoft Academic Search

    M. Dudziak; M. Pitkaenen

    1999-01-01

    A quantum topological network model that might allow for the production of energy through the employment of vacuum electromagnetic currents form is based upon foundational principles of topological geometrodynamics (TGD) (Pitkänen, 1995a, 1995b). Such a production photon-factory would have the capability of drawing upon a seemingly inexhaustible supply of what in TGD formalism is a ``vapor phase'' of photons. Particularly

  19. A technique for eliminating white phosphorus deposits in vapor phase epitaxy systems

    NASA Technical Reports Server (NTRS)

    Wilt, D. M.; Hoffman, R. W.

    1993-01-01

    A technique of heating the exhaust lines is described whereby phosphorus in the exhaust portion of an organometallic vapor phase epitaxy reactor is encouraged to deposit in the red form rather than the pyrophoric white form. This technique is simple, effective, and does not hinder or limit the conditions under which the reactor may be operated.

  20. DEVELOPMENT OF AN AIR-TO-LEAF VAPOR PHASE TRANSFER FACTOR FOR DIOXINS AND FURANS

    EPA Science Inventory

    Results of an experiment in which grass was grown in a greenhouse and outdoors, and in soils of different concentration levels of dioxins and furans, were used in a modeling exercise to derive an air-to-leaf vapor phase transfer factor. The purpose of the experiment was to under...

  1. A power rate law study of silicon germanium selective vapor phase epitaxy kinetics

    Microsoft Academic Search

    P. Tomasini; V. Machkaoutsan; S. G. Thomas

    2009-01-01

    The selective vapor phase epitaxy (SVPE) kinetics of a Si1?xGex heterostructure is complex. To date, operational kinetics schemes are not available and reactant interactions are not very well understood. This study is a phenomenological investigation of epitaxial film growth rate (GR) and composition. An empirical model is developed specifically to address the kinetics of industrial SVPE processes performed at a

  2. Homogeneous nucleation of droplets from a supersaturated vapor phase Michael P. Moody and Phil Attard

    E-print Network

    Attard, Phil

    Attard Ian Wark Research Institute, University of South Australia, Mawson Lakes SA 5095 Australia are compared for the case where the vapor phase forms a reservoir constant supersaturation . In the case and will in all likelihood evaporate. As a result of this energy barrier, the system can exist in a metastable

  3. Retronasal Discrimination Between Vapor-Phase Long-Chain, Aliphatic Fatty Acids

    E-print Network

    2006; Warner et al. 1997). Linoleic acid is "the major constituent of many vegetables oils, including important (see Simopoulos 2008). Linoleic and oleic acids are the dominant fatty acids in vegetable oils vegetable oils (Gunstone 2002). During consumption of foods and beverages, vapor- phase components

  4. Supporting information Vapor Phase Synthesis of Single-Crystalline Ag Nanowires and Single-

    E-print Network

    Ihee, Hyotcherl

    1 Supporting information Vapor Phase Synthesis of Single-Crystalline Ag Nanowires and Single. Email: bongsoo@kaist.ac.kr #12;2 Experimental details Ag NWs Synthesis. In a typical synthesis, 0.2 g downstream by the flow of 500 sccm of argon gas at a pressure of 5 to 10 Torr to a lower temperature zone (T2

  5. ORGANIC CHARACTERIZATION OF AEROSOLS AND VAPOR PHASE COMPOUNDS IN URBAN ATMOSPHERES

    EPA Science Inventory

    Organic pollutants in urban atmospheres were characterized by analyzing particulate and/or vapor-phase samples collected by EPA in St. Louis, Missouri; Miami, Florida; Denver, Colorado; Houston, Texas; and at the General Motors Test Track in Milford, Michigan. The particulate sam...

  6. EFFECT OF DIRECTIONAL SWITCHING FREQUENCY ON TOLUENE DEGRADATION IN A VAPOR-PHASE BIOREACTOR. (R826168)

    EPA Science Inventory

    A potential method to improve biomass distribution and the stability of vapor-phase bioreactors is to operate them in a directionally switching mode such that the contaminant air stream direction is periodically reversed through the reactor. In this study, the effect of switching...

  7. EFFECT OF VAPOR-PHASE BIOREACTOR OPERATION ON BIOMASS ACCUMULATION, DISTRIBUTION, AND ACTIVITY. (R826168)

    EPA Science Inventory

    Excess biomass accumulation and activity loss in vapor-phase bioreactors (VPBs) can lead to unreliable long-term operation. In this study, temporal and spatial variations in biomass accumulation, distribution and activity in VPBs treating toluene-contaminated air were monitored o...

  8. Laser-diode frequency control by resonant phase-conjugate reflection from an atomic vapor

    Microsoft Academic Search

    N. Cyr; M. Breton; M. Tetu; S. Theriault

    1991-01-01

    First results are reported on the frequency control of an AlGaAs laser diode by resonant phase-conjugate reflection from an atomic rubidium vapor. When the electrical feedback technique is used, the Allan variance reaches a flicker floor. It is also demonstrated that laser frequency locking can be achieved by using the phase-conjugate reflection directly as a resonant optical feedback. This approach

  9. Space cryogenics components based on the thermomechanical effect - Vapor-liquid phase separation

    NASA Technical Reports Server (NTRS)

    Yuan, S. W. K.; Frederking, T. H. K.

    1989-01-01

    Applications of the thermomechanical effect has been qualified including incorporation in large-scale space systems in the area of vapor-liquid phase separation (VLPS). The theory of the porous-plug phase separator is developed for the limit of a high thermal impedance of the solid-state grains. Extensions of the theory of nonlinear turbulent flow are presented based on experimental results.

  10. Phase calibration and water vapor radiometry for millimeter-wave arrays

    Microsoft Academic Search

    O. P. Lay

    1997-01-01

    Correcting for the fluctuations in atmospheric path length caused by water vapor is a major challenge facing millimeter- and submillimeter-wave interferometers, and one that must be overcome to obtain routine sub-arcsecond resolution. Using the model for the power spectrum of phase fluctuations developed in \\\\cite[Lay~(1997)]{lay96}, the existing technique of phase referencing to a bright calibrator object is analysed. It is

  11. Plasma Spray-PVD: A New Thermal Spray Process to Deposit Out of the Vapor Phase

    NASA Astrophysics Data System (ADS)

    von Niessen, Konstantin; Gindrat, Malko

    2011-06-01

    Plasma spray-physical vapor deposition (PS-PVD) is a low pressure plasma spray technology recently developed by Sulzer Metco AG (Switzerland). Even though it is a thermal spray process, it can deposit coatings out of the vapor phase. The basis of PS-PVD is the low pressure plasma spraying (LPPS) technology that has been well established in industry for several years. In comparison to conventional vacuum plasma spraying (VPS) or low pressure plasma spraying (LPPS), the new proposed process uses a high energy plasma gun operated at a reduced work pressure of 0.1 kPa (1 mbar). Owing to the high energy plasma and further reduced work pressure, PS-PVD is able to deposit a coating not only by melting the feed stock material which builds up a layer from liquid splats but also by vaporizing the injected material. Therefore, the PS-PVD process fills the gap between the conventional physical vapor deposition (PVD) technologies and standard thermal spray processes. The possibility to vaporize feedstock material and to produce layers out of the vapor phase results in new and unique coating microstructures. The properties of such coatings are superior to those of thermal spray and electron beam-physical vapor deposition (EB-PVD) coatings. In contrast to EB-PVD, PS-PVD incorporates the vaporized coating material into a supersonic plasma plume. Owing to the forced gas stream of the plasma jet, complex shaped parts such as multi-airfoil turbine vanes can be coated with columnar thermal barrier coatings using PS-PVD. Even shadowed areas and areas which are not in the line of sight of the coating source can be coated homogeneously. This article reports on the progress made by Sulzer Metco in developing a thermal spray process to produce coatings out of the vapor phase. Columnar thermal barrier coatings made of Yttria-stabilized Zircona (YSZ) are optimized to serve in a turbine engine. This process includes not only preferable coating properties such as strain tolerance and erosion resistance but also the simultaneous coverage of multiple air foils.

  12. WHAT ARE E-CIGARETTES? Electronic cigarettes, also called electronic nicotine delivery systems (ENDS), are designed to mimic the size,

    E-print Network

    Su, Xiao

    in propylene glycol or glycerin. Many e-cigarettes are rechargeable and users purchase replacement cartridges · Exhaled vapor is a mixture of water, propylene glycol and low levels of nicotine, tobacco specific not approved e-cigarettes as effective cessation devices. There are other proven safe and effective methods

  13. Liquid-phase and vapor-phase dehydration of organic/water solutions

    DOEpatents

    Huang, Yu (Palo Alto, CA); Ly, Jennifer (San Jose, CA); Aldajani, Tiem (San Jose, CA); Baker, Richard W. (Palo Alto, CA)

    2011-08-23

    Processes for dehydrating an organic/water solution by pervaporation or vapor separation using fluorinated membranes. The processes are particularly useful for treating mixtures containing light organic components, such as ethanol, isopropanol or acetic acid.

  14. Comparison between Normal and HeII Two-phase Flows at High Vapor Velocities

    NASA Astrophysics Data System (ADS)

    Perraud, S.; Rousset, B.; Thibault, P.; van Weelderen, R.; Wolf, P. E.

    2006-04-01

    We present results on helium co-current two-phase flow experiments at high vapor velocity obtained with the use of the new CEA/SBT 400 W/1.8 K refrigerator. For vapor velocities larger than typically 4 m/s, a mist of droplets develops from the bulk liquid interface accompanied by an increase in heat transfer at the wall. Experiments were conducted in a 10 m long, 40 mm I.D. straight pipe, both in helium II and in helium I to compare these two situations. The respective roles of vapor density, vapor velocity and liquid level on atomization were systematically investigated. Light scattering experiments were performed to measure sizes, velocities and interfacial areas of droplets in a complete cross section. In-house-made heat transfer sensors located in the mist allowed us to deduce an upper value of the extra cooling power of the dispersed phase. The practical interest of atomized flow for cooling large cryogenic facilities is discussed by considering the balance between increase in heat transfer and pressure drops it induces.

  15. An Experimental Visualization and Image Analysis of Electrohydrodynamically Induced Vapor-Phase Silicon Oil Flow under DC Corona Discharge

    Microsoft Academic Search

    Ryu-Ichiro Ohyama; Masaru Fukumoto

    2004-01-01

    A DC corona discharge induced electrohydrodynamic (EHD) flow phenomenon for a multi-phase fluid containing a vapor-phase dielectric liquid in the fresh air was investigated. The experimental electrode system was a simple arrangement of needle-plate electrodes for the corona discharges and high-resistivity silicon oil was used as the vapor-phase liquid enclosure. The qualitative observation of EHD flow patterns was conducted by

  16. Electronic cigarettes: the road ahead.

    PubMed

    Besaratinia, Ahmad; Tommasi, Stella

    2014-09-01

    Electronic cigarettes (e-cig) are proliferating in the world's lucrative nicotine delivery market at an alarmingly fast pace. E-cig are aggressively marketed as an alternative to conventional tobacco cigarettes, although very little is known about the health consequences of e-cig use. Chemical analysis of e-cig vapor/liquid has shown that many toxicants and carcinogens present in cigarette smoke are also found, albeit generally in lower concentrations, in a wide range of e-cig products. Notwithstanding the presence of toxicants and carcinogens in e-cig products, the biological effects of exposure to these contaminants have not been determined in e-cig users. The ongoing research and future investigations on e-cig initiation, use, perceptions, dependence, and toxicity are expected to provide empirical evidence that can be used to inform the general public, scientific community, and regulatory authorities of the health risks/benefits associated with e-cig use. This information will help stimulate scientists in the field of tobacco research, as well as assist the regulatory agencies in making scientifically based decisions on the development and evaluation of regulations on tobacco products to protect the public's health. Finding the scientific underpinnings for the health risks/benefits of e-cig use can impact millions of people who are increasingly turning to e-cig as a replacement for or complement to conventional tobacco cigarettes. PMID:24952095

  17. Dramatic vapor-phase modulation of the characteristics of graphene field-effect transistors.

    PubMed

    Worley, Barrett C; Kim, Seohee; Park, Saungeun; Rossky, Peter J; Akinwande, Deji; Dodabalapur, Ananth

    2015-07-01

    Here we report on dramatic and favorable changes to the operating characteristics in monolayer graphene field-effect transistors (FETs) exposed to vapor-phase, polar organic molecules in ambient. These changes include significant reduction of the Dirac voltage, accompanied by both an increase in electron and hole mobility, ?, and a decrease in residual carrier density, N0, to < 3 × 10(11) cm(-2). In contrast to graphene FET modulation with various liquid- and solid-phase dielectric media present in the literature, we attribute these changes to screening by polar vapor-phase molecules of fields induced by charged impurities and defects, nimp, in or near the active layer. The magnitude of the changes produced in the graphene FET parameters scales remarkably well with the dipole moment of the delivered molecules. These effects are reversible, a unique advantage of working in the vapor phase. The changes observed upon polar molecule delivery are analogous to those produced by depositing and annealing fluoropolymer coatings on graphene that have been reported previously, and we attribute these changes to similar charge screening or neutralization phenomena. PMID:26107384

  18. Transient-pressure analysis in geothermal steam reservoirs with an immobile vaporizing liquid phase

    USGS Publications Warehouse

    Moench, A.F.; Atkinson, P.G.

    1978-01-01

    A finite-difference model for the radial horizontal flow of steam through a porous medium is used to evaluate transient-pressure behavior in the presence of an immobile vaporizing or condensing liquid phase. Graphs of pressure drawdown and buildup in terms of dimensionless pressure and time are obtained for a well discharging steam at a constant mass flow rate for a specified time. The assumptions are made that the steam is in local thermal equilibrium with the reservoir rocks, that temperature changes are due only to phase change, and that effects of vapor-pressure lowering are negligible. Computations show that when a vaporizing liquid phase is present the pressure drawdown exhibits behavior similar to that observed in noncondensable gas reservoirs, but delayed in time. A theoretical analysis allows for the computation of this delay and demonstrates that it is independent of flow geometry. The response that occurs upon pressure buildup is markedly different from that in a noncondensable gas system. This result may provide a diagnostic tool for establishing the existence of phase-change phenomena within a reservoir. ?? 1979.

  19. Novel Process for Removal and Recovery of Vapor Phase Mercury

    SciTech Connect

    Collin Greenwell; Daryl L. Roberts; Jason Albiston; Robin Stewart; Tom Broderick

    1998-03-09

    We demonstrated in the Phase I program all key attributes of a new technology for removing mercury from flue gases, namely, a) removal of greater than 95% of both elemental and oxidized forms of mercury, both in the laboratory and in the field b) regenerability of the sorbent c) ability to scale up, and d) favorable economics. The Phase I program consisted of four tasks other than project reporting: Task I-1 ? Screen Sorbent Configurations in the Laboratory Task I-2 ? Design and Fabricate Bench-Scale Equipment Task I-3 ? Test Bench-Scale Equipment on Pilot Combustor Task I-4 ? Evaluate Economics Based on Bench-Scale Results In Task I-1, we demonstrated that the sorbents are thermally durable and are regenerable through at least 55 cycles of mercury uptake and desorption. We also demonstrated two low-pressure- drop configurations of the sorbent, namely, a particulate form and a monolithic form. We showed that the particulate form of the sorbent would take up 100% of the mercury so long as the residence time in a bed of the sorbent exceeded 0.1 seconds. In principle, the particulate form of the sorbent could be imbedded in the back side of a higher temperature bag filter in a full-scale application. With typical bag face velocities of four feet per minute, the thickness of the particulate layer would need to be about 2000 microns to accomplish the uptake of the mercury. For heat transfer efficiency, however, we believed the monolithic form of the sorbent would be the more practical in a full scale application. Therefore, we purchased commercially-available metallic monoliths and applied the sorbent to the inside of the flow channels of the monoliths. At face velocities we tested (up to 1.5 ft/sec), these monoliths had less than 0.05 inches of water pressure drop. We tested the monolithic form of the sorbent through 21 cycles of mercury sorption and desorption in the laboratory and included a test of simultaneous uptake of both mercury and mercuric chloride. Overall, in Task I-1, we found that the particulate and monolith forms of the sorbent were thermally stable and durable and would repeatedly sorb and desorb 100% of the mercury, including mercuric chloride, with low pressure drop and short residence times at realistic flue gas conditions.

  20. Resonant Acoustic Measurement of Vapor Phase Transport Phenomenon

    NASA Astrophysics Data System (ADS)

    Schuhmann, R. J.; Garrett, S. L.; Matson, J. V.

    2002-12-01

    A major impediment to accurate non steady-state diffusion measurements is the ability to accurately measure and track a rapidly changing gas concentration without disturbing the system. Non-destructive methods that do not interfere with system dynamics have been developed in the past. These methods, however, have tended to be cumbersome or inaccurate at low concentrations. A new experimental approach has been developed to measure gaseous diffusion in free air and through porous materials. The method combines the traditional non steady-state laboratory methodology with resonant acoustic gas analysis. A phase-locked-loop (PLL) resonance frequency tracker is combined with a thermally insulated copper resonator. A piston sealed with a metal bellows excites the fundamental standing wave resonance of the resonator. The PLL maintains a constant phase difference (typically 90§) between the accelerometer mounted on the piston and a microphone near the piston to track the resonance frequency in real time. A capillary or glass bead filled core is fitted into an o-ring sealed opening at the end of the resonator opposite the bellows. The rate at which the tracer gas is replaced by air within the resonator is controlled by the diffusion coefficient of the gas in free air through the capillary (DA) or by the effective diffusion coefficient of the gas through the core (De). The mean molecular weight of the gas mixture in the resonator is directly determined six times each minute from the ratio of the absolute temperature to the square of the fundamental acoustic resonance frequency. Average system stability (temperature divided by frequency squared) is better than 350 ppm. DA values for a 0.3-inch diameter capillary were in excellent agreement with published values. De values for porous media samples (0.5 mm glass beads) of four different lengths (1 through 4 inches) using three different tracer gases (He, CH4, Kr) will be reported. Comments will be offered regarding tracer gas selection and device orientation and their effect on experimental results. [Work supported by the Office of Naval Research.

  1. Halide vapor phase epitaxy of twin-free ?-Ga2O3 on sapphire (0001) substrates

    NASA Astrophysics Data System (ADS)

    Oshima, Yuichi; Víllora, Encarnación G.; Shimamura, Kiyoshi

    2015-05-01

    The halide vapor phase epitaxy of ?-Ga2O3 is demonstrated for the first time. The films are twin-free and heteroepitaxially grown on sapphire (0001) substrates using gallium chloride and oxygen as precursors. X-ray ?–2? and pole figure measurements reveal that the film is single-crystalline (0001) ?-Ga2O3 with no detectable formation of ?-Ga2O3. The optical bandgap is determined to be 5.16 eV based on the transmittance spectrum. The growth rate monotonically increases with the partial pressures of the raw material gases, reaching approximately 150 µm/h, which is over two orders of magnitude larger than those of conventional vapor phase epitaxial growth techniques, such as mist CVD or MBE.

  2. Molecular Simulation of Henry's Constant at Vapor-Liquid and Liquid-Liquid Phase Richard J. Sadus

    E-print Network

    Molecular Simulation of Henry's Constant at Vapor-Liquid and Liquid-Liquid Phase Boundaries Richard to determine Henry's constant from the residual chemical potential at infinite dilution at the vapor-liquid coexistence. 1. Introduction Henry's constant is a well-known measure of a solute's solubility in a particular

  3. Effects of vapor-phase deposition processes on the optical, chemical, and magnetic properties OE the lunar regolith

    Microsoft Academic Search

    Bruce Hapke; William Cassidy; Edward Wells

    1975-01-01

    The processes of solar wind sputtering and meteoritic impact vaporization have created materials in the lunar regolith which were deposited from a vapor phase. Although the quantity of such exotic condensed substances should theoretically be comparable with that of materials which have been melted by impacts, their existence in the fines has not been generally recognized. We have investigated the

  4. Influence of Sapphire Nitridation on Properties of Indium Nitride Prepared by Metalorganic Vapor Phase Epitaxy

    Microsoft Academic Search

    Yung-Chung Pan; Wen-Hsiung Lee; Chen-Ke Shu; Heng-Ching Lin; Chung-I Chiang; Horng Chang; Deng-Sung Lin; Ming-Chih Lee; Wei-Kuo Chen

    1999-01-01

    Indium nitride films have been successfully grown on (0001) sapphiresubstrates by metalorganic vapor phase epitaxy (MOVPE) using TMIn and NH3as source precursors. Experimental results indicated that pregrowthtreatments, such as buffer layer growth, nitridation temperature andnitridation duration have dramatic effects on the growth of the InN films. For filmsnitridated at 1,000°C for 40 min without any buffer layer growth,we obtained an

  5. New vanadium dopant precursor for GaAs growth by metalorganic vapor-phase epitaxy

    Microsoft Academic Search

    A. Rebey; A Bchetnia; Ch Benjeddou; B El Jani; P Gibart

    1998-01-01

    Vanadium-doped GaAs was grown by metalorganic vapor-phase epitaxy (MOVPE) using vanadium (IV) chloride VCl4 as a novel dopant source. The optimum growth conditions were achieved using reflectometry with a 632.8nm laser beam. A reduction in the growth rate of V-doped GaAs was observed and attributed to the etching by Cl species associated to the use of high flow of VCl4.

  6. Growth and Characterization of Vanadium-Doped ZnSe by Metalorganic Vapor Phase Epitaxy

    Microsoft Academic Search

    Masahiro Tahashi; Zunyi Wu; Hideo Goto; Toshiyuki Ido

    2008-01-01

    Vanadium-doped ZnSe was epitaxially grown on a (100) GaAs substrate by metalorganic vapor phase epitaxy under atmospheric pressure. The effects of the molar supply ratio of dimethylzinc to dimethylselenide on crystallinity were investigated to determine the optimum vanadium doping conditions. In the present study, as dopant sources of vanadium, vanadocene and triethoxyvanadyl were used. When triethoxyvanadyl was used as a

  7. Isothermal vapor phase epitaxy as a versatile technology for infrared photodetectors

    Microsoft Academic Search

    Krzysztof Adamiec; Miroslaw Grudzien; Zenon Nowak; Jaroslaw Pawluczyk; Jozef Piotrowski; Jaroslaw Antoszewski; John M. dell; Charles A. Musca; Lorenzo Faraone

    1997-01-01

    We report here the use of isothermal vapor phase epitaxy to grow 3D Hg1-xCdxTe heterostructures for photoconductive, photovoltaic and photoelectromagnetic infrared detectors operated at near room temperatures. A reusable two-zone atmospheric pressure growth system has been developed.the system makes it possible not only to grow epilayers but also to perform in situ other processes such as high temperature annealing to

  8. Removal of Oxygen from Electronic Materials by Vapor-Phase Processes

    NASA Technical Reports Server (NTRS)

    Palosz, Witold

    1997-01-01

    Thermochemical analyses of equilibrium partial pressures over oxides with and without the presence of the respective element condensed phase, and hydrogen, chalcogens, hydrogen chalcogenides, and graphite are presented. Theoretical calculations are supplemented with experimental results on the rate of decomposition and/or sublimation/vaporization of the oxides under dynamic vacuum, and on the rate of reaction with hydrogen, graphite, and chalcogens. Procedures of removal of a number of oxides under different conditions are discussed.

  9. Vapor-Phase Helmholtz Equation for HFC227ea from Speed-of-Sound Measurements

    Microsoft Academic Search

    G. Benedetto; R. M. Gavioso; R. Spagnolo; M. Grigiante; G. Scalabrin

    2001-01-01

    This work presents measurements of the speed-of-sound in the vapor phase of 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea). The measurements were obtained in a stainless-steel spherical resonator with a volume of ~900 cm3 at temperatures between 260 and 380 K and at pressures up to 500 kPa. Ideal-gas heat capacities and acoustic virial coefficients are directly produced from the data. A Helmholtz equation of

  10. High-performance distributed feedback quantum cascade lasers grown by metalorganic vapor phase epitaxy

    Microsoft Academic Search

    R. P. Green; L. R. Wilson; E. A. Zibik; D. G. Revin; J. W. Cockburn; C. Pflügl; W. Schrenk; G. Strasser; A. B. Krysa; J. S. Roberts; C. M. Tey; A. G. Cullis

    2004-01-01

    We report the operation of distributed feedback quantum cascade lasers, grown by metalorganic vapor phase epitaxy. Single-mode laser emission at lambda~10.3 mum and lambda~7.8 mum is observed from two different samples, with 300 K threshold current densities of Jth~3 and ~2.4 kA cm-2, respectively. Structural investigation by x-ray diffraction and transmission electron microscopy, and the close correlation between the predicted

  11. High-performance distributed feedback quantum cascade lasers grown by metalorganic vapor phase epitaxy

    Microsoft Academic Search

    R. P. Green; L. R. Wilson; E. A. Zibik; D. G. Revin; J. W. Cockburn; W. Schrenk; G. Strasser; A. B. Krysa; J. S. Roberts; C. M. Tey; A. G. Cullis

    2004-01-01

    We report the operation of distributed feedback quantum cascade lasers, grown by metalorganic vapor phase epitaxy. Single-mode laser emission at ??10.3 ?m and ??7.8 ?m is observed from two different samples, with 300 K threshold current densities of Jth?3 and ?2.4 kA cm?2, respectively. Structural investigation by x-ray diffraction and transmission electron microscopy, and the close correlation between the predicted

  12. Low-temperature vapor-phase etching of silicon carbide by dioxygen difluoride

    Microsoft Academic Search

    M. Moalem; D. R. Olander; M. Balooch

    1995-01-01

    Efficient room-temperature vapor-phase etching of SiC by the compound dioxygen difluoride (FOOF) has been demonstrated. FOOF was generated using a design based on thermal-atomization technique which produced gram quantities of the compound per hour. On both poly- and epitype silicon carbide at room temperature, about 6% of the FOOF molecules striking the surface reacted to form SiF4 and CO. Examination

  13. Sintering behavior of ultrafine silicon carbide powders obtained by vapor phase reaction

    NASA Technical Reports Server (NTRS)

    Okabe, Y.; Miyachi, K.; Hojo, J.; Kato, A.

    1984-01-01

    The sintering behavior of ultrafine SiC powder with average particle size of about 0.01-0.06 microns produced by a vapor phase reaction of the Me4Si-H2 system was studied at the temperature range of 1400-2050 deg. It was found that the homogeneous dispersion of C on SiC particles is important to remove the surface oxide layer effectively. B and C and inhibitive effect on SiC grain growth.

  14. Removal of Vapor-Phase Elemental Mercury by Novel Chemically Promoted Noncarbon Sorbents

    Microsoft Academic Search

    Anchao Zhang; Jun Xiang; Lushi Sun; Song Hu; Juanli Jing; Peng Fu; Sheng Su; Peisheng Li; Wan Yu

    2009-01-01

    Adsorption experiments of vapor-phase elemental mercury were carried out using bromine and iodine modified Kaolin, Zeolite, Bentonite and Chitosan in a laboratory-scale fixed-bed reactor. VM3000 online mercury analyzer was applied to detect the inlet and outlet Hg0 concentrations. The characterizations of the sorbents were analyzed using Fourier transform infra-red spectroscopy. The results indicated the iodine was found in the inlayer

  15. Influence of aluminum on doping of ytterbium in optical fiber synthesized by vapor phase technique

    NASA Astrophysics Data System (ADS)

    Saha, Maitreyee; Pal, Atasi; Pal, Mrinmay; Sen, Ranjan

    2015-01-01

    The process conditions of vapor phase doping technique for fabricating rare earth (RE) doped optical fiber have been systematically investigated to achieve better control over RE incorporation. Experimental results showed that the amount of RE incorporation can be precisely controlled by adjusting Al ion concentration in the inlet gas mixture. The extent of RE incorporation can also be predicted for any composition of inlet gas mixture if all other process parameters remain constant. The investigation helps to obtain the optimum conditions necessary to produce fibers of given specification and thus achieve greater reproducibility. For the first time co-operative phenomenon has been established through gas phase technique.

  16. HeII co-current two phase flow at high vapor velocities

    NASA Astrophysics Data System (ADS)

    Rousset, B.; Jager, B.; di Muoio, E.; Puech, L.; Thibault, P.; Vallcorba, R.; van Weelderen, R.; Wolf, P. E.

    2002-05-01

    In the framework of LHC studies, we have performed several experiments on HeII co-current two-phase flow. It was found that for high vapor velocities, the heat exchange capacity between the HeII flow and the pipe wall is significantly better than what can be accounted for by the liquid to wall interface of a stratified two-phase flow pattern. This seems to indicate a transition from a pure stratified two-phase flow into either a partially annular two-phase flow or a stratified two-phase flow including liquid droplets in the vapor flow or a combination of the two. In the last two cases, it is assumed that liquid droplets which get dispersed on the tube wall increase the wetted surface. A new facility has been designed to analyze this flow behavior. High sensitivity capacitive liquid level sensors glued onto the inner wall of the pipe were used in order to detect a possible semiangular flow pattern whereas light diffraction and scattering were used to detect liquid droplets. Finally, in addition to a circumferential heat exchange box, local heat exchange boxes located at different azimuth positions are added. Description of this new facility, calibration of the local heat exchange boxes and first results are presented.

  17. Biodegradation of high concentrations of benzene vapors in a two phase partition stirred tank bioreactor

    PubMed Central

    2013-01-01

    The present study examined the biodegradation rate of benzene vapors in a two phase stirred tank bioreactor by a bacterial consortium obtained from wastewater of an oil industry refinery house. Initially, the ability of the microbial consortium for degrading benzene was evaluated before running the bioreactor. The gaseous samples from inlet and outlet of bioreactor were directly injected into a gas chromatograph to determine benzene concentrations. Carbone oxide concentration at the inlet and outlet of bioreactor were also measured with a CO2 meter to determine the mineralization rate of benzene. Influence of the second non-aqueous phase (silicon oil) has been emphasized, so at the first stage the removal efficiency (RE) and elimination capacity (EC) of benzene vapors were evaluated without any organic phase and in the second stage, 10% of silicon oil was added to bioreactor media as an organic phase. Addition of silicon oil increased the biodegradation performance up to an inlet loading of 5580?mg/m3, a condition at which, the elimination capacity and removal efficiency were 181?g/m3/h and 95% respectively. The elimination rate of benzene increased by 38% in the presence of 10% of silicone oil. The finding of this study demonstrated that two phase partition bioreactors (TPPBs) are potentially effective tools for the treatment of gas streams contaminated with high concentrations of poorly water soluble organic contaminant, such as benzene. PMID:23369269

  18. Evaluation of PCDD\\/F partitioning between vapor and solid phases in MWI flue gases with temperature variation

    Microsoft Academic Search

    Kai Hsien Chi; Moo Been Chang; Shu Hao Chang

    2006-01-01

    Partitioning of PCDD\\/Fs (polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofuran) between vapor and solid phases in flue gas is affected by several factors including temperature variation. In this study, PCDD\\/F removal efficiencies achieved with activated carbon injection (ACI) and partitioning of vapor\\/solid phase PCDD\\/Fs in flue gases with temperature variation in a municipal waste incinerator (MWI) are evaluated via intensive flue gas

  19. Enhanced Vapor-Phase Diffusion in Porous Media - LDRD Final Report

    SciTech Connect

    Ho, C.K.; Webb, S.W.

    1999-01-01

    As part of the Laboratory-Directed Research and Development (LDRD) Program at Sandia National Laboratories, an investigation into the existence of enhanced vapor-phase diffusion (EVD) in porous media has been conducted. A thorough literature review was initially performed across multiple disciplines (soil science and engineering), and based on this review, the existence of EVD was found to be questionable. As a result, modeling and experiments were initiated to investigate the existence of EVD. In this LDRD, the first mechanistic model of EVD was developed which demonstrated the mechanisms responsible for EVD. The first direct measurements of EVD have also been conducted at multiple scales. Measurements have been made at the pore scale, in a two- dimensional network as represented by a fracture aperture, and in a porous medium. Significant enhancement of vapor-phase transport relative to Fickian diffusion was measured in all cases. The modeling and experimental results provide additional mechanisms for EVD beyond those presented by the generally accepted model of Philip and deVries (1957), which required a thermal gradient for EVD to exist. Modeling and experimental results show significant enhancement under isothermal conditions. Application of EVD to vapor transport in the near-surface vadose zone show a significant variation between no enhancement, the model of Philip and deVries, and the present results. Based on this information, the model of Philip and deVries may need to be modified, and additional studies are recommended.

  20. Design and optimization of a total vaporization technique coupled to solid-phase microextraction.

    PubMed

    Rainey, Christina L; Bors, Dana E; Goodpaster, John V

    2014-11-18

    Solid-phase microextraction (SPME) is a popular sampling technique in which chemical compounds are collected with a sorbent-coated fiber and then desorbed into an analytical instrument such as a liquid or gas chromatograph. Typically, this technique is used to sample the headspace above a solid or liquid sample (headspace SPME), or to directly sample a liquid (immersion SPME). However, this work demonstrates an alternative approach where the sample is totally vaporized (total vaporization SPME or TV-SPME) so that analytes partition directly between the vapor phase and the SPME fiber. The implementation of this technique is demonstrated with polydimethylsiloxane-divinylbenzene (PDMS-DVB) and polyacrylate (PA) coated SPME fibers for the collection of nicotine and its metabolite cotinine in chloroform extracts. The most important method parameters were optimized using a central composite design, and this resulted in an optimal extraction temperature (96 °C), extraction time (60 min), and sample volume (120 ?L). In this application, large sample volumes up to 210 ?L were analyzed using a volatile solvent such as chloroform at elevated temperatures. The sensitivity of TV-SPME is nearly twice that of liquid injection for cotinine and nearly 6 times higher for nicotine. In addition, increased sampling selectivity of TV-SPME permits detection of both nicotine and cotinine in hair as biomarkers of tobacco use where in the past the detection of cotinine has not been achieved by conventional SPME. PMID:25313649

  1. Vapor-phase fabrication and properties of continuous-filament ceramic composites.

    PubMed

    Besmann, T M; Sheldon, B W; Lowden, R A; Stinton, D P

    1991-09-01

    The continuous-filament ceramic composite is becoming recognized as necessary for new, high-temperature structural applications. Yet because of the susceptibility of the filaments to damage from traditional methods for the preparation of ceramics, vapor-phase infiltration has become the fabrication method of choice. The chemical vapor infiltration methods for producing these composites are now being studied in earnest, with the complexity of filament weaves and deposition chemistry being merged with standard heat and mass-transport relationships. Two of the most influential effects on the mechanical properties of these materials are the adhesion and frictional force between the fibers and the matrix, which can be controlled by a tailored interface coating. A variety of materials are available for producing these composites including carbide, nitride, boride, and oxide filaments and matrices. Silicon carbide-based materials are by far the most advanced and are already being used in aerospace applications. PMID:17731807

  2. Elastin dehydration through the liquid and the vapor phase: a comparison of osmotic stress models.

    PubMed

    Lillie, M A; Chalmers, G W; Gosline, J M

    1996-11-01

    The swelling and viscoelastic behaviors of samples of purified arterial elastin were investigated to develop a model for studying the viscoelastic behavior of elastin. Two osmotic stress models were used: the vapor phase model (VPM), in which the stress on the elastin sample was applied through the vapor phase by equilibrating the sample over a saline solution, and the liquid phase model (LPM), in which the stress was applied through the liquid phase by equilibrating the sample in aqueous solutions of large molecular weight polymers. The elastin in the VPM showed a highly varied viscoelastic response, and was slightly stiffer and had a slightly higher damping coefficient than the elastin in the LPM at equivalent nominal relative humidities. We believe the difference in behavior of the elastin in the two models was due to geometric distortions of the elastin that occur during dehydration in the VPM. In the LPM, the spaces between the elastin fibrils are filled with water, and in the VPM these spaces collapse when the water is removed. Removal of only the interfibrillar water deswelled the tissue and increased its stiffness and damping coefficient. Viscoelastic spectra obtained at different levels of osmotic stress in the LPM were reducible to one master curve, indicating that the dominant effect of dehydration is a nonspecific reduction of molecular mobility. We conclude that the LPM is a better model than the VPM for studying the effects of dehydration on the mechanical behavior of elastin. PMID:8875818

  3. Vapor-phase infrared spectroscopy on solid organic compounds with a pulsed resonant photoacoustic detection scheme

    NASA Astrophysics Data System (ADS)

    Bartlome, Richard; Fischer, Cornelia; Sigrist, Markus W.

    2005-08-01

    There is a great need for a low cost and sensitive method to measure infrared spectra of solid organic compounds in the gas phase. To record such spectra, we propose an optical parametric generator-based photoacoustic spectrometer, which emits in the mid-infrared fingerprint region between 3 and 4 microns. In this system, the sample is heated in a vessel before entering a home built photoacoustic cell, where the gaseous molecules are excited by a tunable laser source with a frequency repetition rate that matches the first longitudinal resonance frequency of the photocaoustic cell. In a first phase, we have focused on low-melting point stimulants such as Nikethamide, Mephentermine sulfate, Methylephedrine, Ephedrine and Pseudoephedrine. The vapor-phase spectra of these doping substances were measured between 2800 and 3100 cm-1, where fundamental C-H stretching vibrations take place. Our spectra show notable differences with commercially available condensed phase spectra. Our scheme enables to measure very low vapor pressures of low-melting point (<160 °C) solid organic compounds. Furthermore, the optical resolution of 8 cm-1 is good enough to distinguish closely related chemical structures such as the Ephedra alkaloids Ephedrine and Methylephedrine, but doesn't allow to differentiate diastereoisomeric pairs such as Ephedrine and Pseudoephedrine, two important neurotransmitters which reveal different biological activities. Therefore, higher resolution and a system capable of measuring organic compounds with higher melting points are required.

  4. Vaporizing Vapor

    NSDL National Science Digital Library

    2012-08-03

    In this demonstration, relative humidity is modeled using a sponge and a pan of water, and the concept of saturation is depicted. Students answer questions examining the relationship between temperature and the capacity of air to hold water vapor. The resource is part of the teacher's guide accompanying the video, NASA Sci Files: The Case of the Phenomenal Weather. Lesson objectives supported by the video, additional resources, teaching tips and an answer sheet are included in the teacher's guide.

  5. Cigars, Cigarettes, and Adolescents

    ERIC Educational Resources Information Center

    Brooks, Ashley; Larkin, Elizabeth M. Gaier; Kishore, Sonal; Frank, Scott

    2008-01-01

    Objective: To examine public health implications of adolescent use of cigars only, cigarettes only, and both cigarettes and cigars. Methods: A cross-sectional health risk survey was administered to a random sample of 4486 high school students in a Midwestern county. Results: More adolescents reported using both cigarettes and cigars (10.6%) than…

  6. E-Cigarettes

    MedlinePLUS

    ... Sports: Keeping Kids Safe Concussions: What to Know E-Cigarettes KidsHealth > Parents > School & Family Life > Tough Topics > E- ... Kids From Using Them If You Smoke About E-Cigarettes E-cigarettes are being marketed as a safe ...

  7. E-Cigarettes

    MedlinePLUS

    What Are E-Cigarettes? E-cigarettes look high tech, so it's easy to believe the hype that they're a safe alternative to smoking. Unfortunately, they're not: E-cigarettes are just another way of putting nicotine — a ...

  8. Vapor-Phase Garnet at Yucca Mountain, Nevada: Geochemistry and Oxygen-Isotope Thermometry

    SciTech Connect

    R. J. Moscati; C.A. Johnson; J.F. Whelan

    2001-07-03

    About 20 vapor-phase garnets were studied in two samples of the Topopah Spring Tuff from Yucca Mountain, in southern Nevada. The Miocene-age Topopah Spring Tuff is a 350-m-thick, devitrified, moderately to densely welded ash flow that is compositionally zoned from high-silica rhyolite to quartz latite. During cooling of the tuff, escaping vapor produced lithophysae (former gas cavities) lined with an assemblage of tridymite, cristobalite, alkali feldspar, and locally, hematite and/or garnet. Vapor-phase topaz and economic deposits (such as porphyry molybdenum-tungsten) commonly associated with topaz-bearing rhyolites (characteristically enriched in fluorine) were not found in the Topopah Spring Tuff at Yucca Mountain. The garnets are not primary igneous phenocrysts, but rather crystals that grew from a fluorine-poor magma-derived vapor trapped during emplacement of the tuff. The garnets are euhedral, vitreous, reddish brown, trapezohedral, as large as 2 mm in diameter, and fractured. The garnets also contain inclusions of tridymite. Electron-microprobe analyses of the garnets reveal that they are almandine-spessartine (48.0 and 47.9 mol percent, respectively), have an average chemical formula of (Fe{sub 1.46}, Mn{sub 1.45}, Mg{sub 0.03}, Ca{sub 0.10}) (Al{sub 1.93}, TiO{sub 0.02}) Si{sub 3.01}O{sub 12}, and are homogeneous in Fe and Mn concentrations from core to rim. Composited garnets from each sample site have {delta}{sup 18}O values of 7.2 and 7.4{per_thousand}. The coexisting tridymite, however, has {delta}{sup 18}O values of 17.4 and 17.6{per_thousand} values indicative of reaction with later, low-temperature water. Unaltered tridymite from higher in the stratigraphic section has a {delta}{sup 18}O of 11.1{per_thousand} which, when coupled with the garnet {delta}{sup 18}O values in a quartz-garnet fractionation equation, indicates vapor-phase crystallization at temperatures of almost 600 C. This high-temperature mineralization, formed during cooling of the tuffs, is distinct from the later and commonly recognized low-temperature stage (generally 50-70 C) of calcite, quartz, and opal secondary mineralization, formed from percolating meteoric water, that locally coats fracture footwalls and lithophysal floors.

  9. Solid state phase transition and vapor pressure studies in ammonium nitrate-potassium nitrate binary system

    NASA Astrophysics Data System (ADS)

    Chien, Wen-Ming

    The solid-state phase transitions in ammonium nitrate (NH4NO 3) and potassium nitrate (KNO3) solid solutions and the equilibrium NH4NO3-KNO3 (AN-KN) phase diagram have been determined. The phase transitions and phase diagram were determined by using the differential scanning calorimetry (DSC) and high temperature X-ray diffractometry. Samples of several different compositions were made for these analyses in a special "Dry Room" with very low humidity. In the X-ray diffraction experiments, the samples were heated on Pt-Rh strip and LaB6 or Si was added for internal calibration. Equilibrium phase diagram was also calculated by using the "FactSage" computer program. A single (AN III) phase region without any phase transitions between 293 to 373 K was observed for compositions between 5 to 25wt% KNO3 in NH4NO3 that is critical for air bag gas generators. The higher temperature KNO3 (KN I) phase has a wide stability range, from 100%KNO3 to 20%KNO3 solution. There is one eutectic, two eutectoids, and two peritectoids in this phase diagram. Two newly discovered solid-state phases were found in the mid-composition range of AN-KN solid solutions. Details of phase equilibria and lattice expansions during heating have been determined. Phase diagram calculations show a reasonable match of the phase boundaries. The total vapor pressures as well as the average molecular weights of pure ammonium nitrate and 16% KNO3 solid solution were measured at various temperatures by the torsion-Knudsen effusion method. The partial pressures of NH4NO3 (PNH4NO 3), NH3 (PNH3), and HNO3 (PHNO 3) have also been determined.

  10. Comparative study of solution-phase and vapor-phase deposition of aminosilanes on silicon dioxide surfaces.

    PubMed

    Yadav, Amrita R; Sriram, Rashmi; Carter, Jared A; Miller, Benjamin L

    2014-02-01

    The uniformity of aminosilane layers typically used for the modification of hydroxyl bearing surfaces such as silicon dioxide is critical for a wide variety of applications, including biosensors. However, in spite of many studies that have been undertaken on surface silanization, there remains a paucity of easy-to-implement deposition methods reproducibly yielding smooth aminosilane monolayers. In this study, solution- and vapor-phase deposition methods for three aminoalkoxysilanes differing in the number of reactive groups (3-aminopropyl triethoxysilane (APTES), 3-aminopropyl methyl diethoxysilane (APMDES) and 3-aminopropyl dimethyl ethoxysilane (APDMES)) were assessed with the aim of identifying methods that yield highly uniform and reproducible silane layers that are resistant to minor procedural variations. Silane film quality was characterized based on measured thickness, hydrophilicity and surface roughness. Additionally, hydrolytic stability of the films was assessed via these thickness and contact angle values following desorption in water. We found that two simple solution-phase methods, an aqueous deposition of APTES and a toluene based deposition of APDMES, yielded high quality silane layers that exhibit comparable characteristics to those deposited via vapor-phase methods. PMID:24411379

  11. Pin-in-paste DFM constraints in vapor phase soldering technology for optoelectronic components

    NASA Astrophysics Data System (ADS)

    Plotog, I.; Varzaru, G.; Turcu, C.; Cucu, T. C.; Svasta, P.; Vasile, A.

    2009-01-01

    The topical trends in the field of electronic equipments developing are a large integration on pcb support for different types of components and devices, including optoelectronic type, from small to medium power, in condition of reducing physical dimensions, in order to create new electronic products in short time at lower manufacturing cost. The condition for economical success for a product is to assure the product, even from the conception stage, with a high level of quality by reducing the product cost; to conclude, designing according with production possibilities by using Design For Manufacturing (DFM) concept. This desideratum depends on the conception and design of the product. According to DFM concept, a successful project assures design requirements for the system and finally for printed circuit boards (PCB), accomplishes the assembling technology constraints defined by international standards in the field of electronic packaging, such as IPC or Restriction of Hazardous Substances Directive. Active from July 1, 2006, the RoHS Directive 2002/95/EC adopted in February 2003 by the European Union, and adopted in Romania by HG - 992/2005, completed by HG - 816/2006, call forth important consequences in assembling technologies. In order to minimize manufacturing cost, Pin-In-Paste offers solutions for complete assembling of high complexity PCBs in Vapor Phase Technology using only one reflow machine avoiding overheating of the assemblies relatively to infrared reflow oven. Starting from RoHS consequences analysis, especially thermal profile, the paper presents the applied research performed in the assembling lines on VPS machine in order to define the design requirements for Pin-In-Paste dedicated stencils and PCBs, experiments result and conclusions regarding DFM requirements for lead-free assembling technologies of optoelectronic components. Finally, scientific and practical conclusions shall be drawn to configure the optimum implementation way for Pin-In-Paste in Vapor Phase Technology. The authors emphasizes that Vapor Phase Technology has all the conditions to become the disruptive technology of the moment.

  12. Real-time trace detection of vapor-phase elemental mercury and its compounds

    NASA Astrophysics Data System (ADS)

    Tong, Xiaomei; Barat, Robert B.; Poulos, Arthur T.

    1999-12-01

    The high toxicity of mercury species (elemental and compound) has prompted a demand for accurate, real-time inventory and control of their emissions. Our method of choice for mercury compound vapor is Photofragment Fluorescence spectroscopy. Target compound concentrations can be related to the fluorescence intensity from an excited fragment. Fragment identities and distributions, as revealed in the fluorescence spectrum provide information on the composition of the parent species. In the first experimental phase, a static cell (no flow) containing mercury compound (e.g. HgCl2 vapor was probed with a deep ultraviolet (UV) laser to generate characteristic spectra. An atmospheric pressure flow cell was used in the second stage. Limits-of-detection have been estimated. Detection schemes have included both photomultiplier tube (with interference filter) and charge- coupled-device camera (with monochromator). To reduce fluorescence quenching, we have expanded an argon gas stream containing Hg vapor through a micro-jet into a vacuum. The jet is crossed with a laser beam at 253.7 nm to excite atomic fluorescence, which is distinguished from the background by time gating.

  13. Vapor-phase hydrogen peroxide as a surface decontaminant and sterilant.

    PubMed Central

    Klapes, N A; Vesley, D

    1990-01-01

    The feasibility of utilizing vapor-phase hydrogen peroxide (VPHP) as a surface decontaminant and sterilant was evaluated in a centrifuge application. The prototype VPHP decontamination system, retrofitted into a Beckman L8-M ultracentrifuge, was designed to vaporize a 30% (wt/wt) solution of aqueous hydrogen peroxide continuously injecting and withdrawing VPHP in a deep-vacuum flow-through system. VPHP cycles of 4, 8, 16, and 32 min were examined for cidal activity against spores of Bacillus subtilis subsp. globigii and Bacillus stearothermophilus. Spore inocula (approximately 10(6)/coupon) were dried onto 0.5-in. (1.27-cm)-square stainless-steel coupons, and coupons were suspended in the centrifuge chamber, the space between the refrigeration can and the barrier ring (inner gap), and the space between the barrier ring and the vacuum ring (outer gap). At a chamber temperature of 4 degrees C, B. subtilis subsp. globigii spores were inactivated within 8 min, while inactivation of spores located in the outer gap at 27 degrees C required 32 min. The elevated temperature and high surface area/volume ratios in the outer gap may serve to decompose the gas more rapidly, thus reducing cidal efficacy. Of the two test spores, B. stearothermophilus was more resistant to VPHP. Nonetheless, VPHP was shown to possess significant sporicidal capability. For practical decontamination applications of the type described, VPHP shows promise as an effective and safer alternative to currently used ethylene oxide or formaldehyde vapors. PMID:2106287

  14. Vapor-phase hydrogen peroxide as a surface decontaminant and sterilant.

    PubMed

    Klapes, N A; Vesley, D

    1990-02-01

    The feasibility of utilizing vapor-phase hydrogen peroxide (VPHP) as a surface decontaminant and sterilant was evaluated in a centrifuge application. The prototype VPHP decontamination system, retrofitted into a Beckman L8-M ultracentrifuge, was designed to vaporize a 30% (wt/wt) solution of aqueous hydrogen peroxide continuously injecting and withdrawing VPHP in a deep-vacuum flow-through system. VPHP cycles of 4, 8, 16, and 32 min were examined for cidal activity against spores of Bacillus subtilis subsp. globigii and Bacillus stearothermophilus. Spore inocula (approximately 10(6)/coupon) were dried onto 0.5-in. (1.27-cm)-square stainless-steel coupons, and coupons were suspended in the centrifuge chamber, the space between the refrigeration can and the barrier ring (inner gap), and the space between the barrier ring and the vacuum ring (outer gap). At a chamber temperature of 4 degrees C, B. subtilis subsp. globigii spores were inactivated within 8 min, while inactivation of spores located in the outer gap at 27 degrees C required 32 min. The elevated temperature and high surface area/volume ratios in the outer gap may serve to decompose the gas more rapidly, thus reducing cidal efficacy. Of the two test spores, B. stearothermophilus was more resistant to VPHP. Nonetheless, VPHP was shown to possess significant sporicidal capability. For practical decontamination applications of the type described, VPHP shows promise as an effective and safer alternative to currently used ethylene oxide or formaldehyde vapors. PMID:2106287

  15. Liquid-Vapor Phase Extraction of Gasoline for In Situ Amelioration of Contaminated Clayey Soil

    NASA Astrophysics Data System (ADS)

    Sharma, S.; Spencer, S.

    2008-12-01

    Liquid-vapor phase extraction (LVPE) of hydrocarbon is a recognized technique for rapid remediation of gasoline contaminated soils and waters. On site application of LVPE is, however, challenging in clayey soils. Four LVPE events were conducted during a 10-month period at a central Californian site that had been contaminated with gasoline due to leakage of underground storage tanks. The site was underlain by unconsolidated alluvial deposits and the soil profile consisted of layers of sandy clays and silty clays with low water table. The objectives of this study were to reduce floating product volume in well waters and to remove petroleum hydrocarbons within the vadose zone. Groundwater was extracted by lowering a stinger to the groundwater surface and applying vacuum. The stingers were able to extract down to 20 ft below ground surface. Vacuum was applied at 25 in of Hg pressure and the LVPE unit extracted soil vapor at the rate of 54 ft3/min. Samples were collected periodically from the extracted groundwater, treated groundwater, extracted soil vapor, and analyzed for gasoline and its constituents. The LVPE showed a moderate impact on the floating product found beneath the site. The volumes of floating product, although measurable, were reduced significantly after the extraction operations. High hydrocarbon concentrations in soil vapor at initial period of extraction events suggested that hydrocarbon vaporization followed a rapid kinetics. During first couple of extraction events, this surge was a followed by a quick decline in concentrations over time. The vaporization process appeared to have reached steady state after repetitive extraction activities. The LVPE system extracted about 288-336 (x1000) liters of groundwater and 88-358 kg of hydrocarbons during the events. In subsequent monitoring studies, significant concentrations of gasoline and its constituents were detected in the well waters. This suggested that the residual contaminant pool could replenish the mobile hydrocarbon pool despite removal operations. The radius of influence of LVPE remained within 10 ft in both saturated and unsaturated zones due to the clayey soil structure. The overall mass of petroleum hydrocarbons remaining in the vadose zone around the wells appeared to have diminished.

  16. High nitrogen composition GaAsN by atmospheric pressure metalorganic vapor-phase epitaxy

    NASA Astrophysics Data System (ADS)

    Toivonen, J.; Hakkarainen, T.; Sopanen, M.; Lipsanen, H.

    2000-12-01

    Highly luminescent GaAs 1- xN x alloys were successfully grown by atmospheric pressure metalorganic vapor-phase epitaxy (MOVPE). The nitrogen composition x of as high as 5.6% was obtained using trimethylgallium (TMGa), tertiarybutylarsine (TBAs) and dimethylhydrazine (DMHy) precursors. In-situ and post-growth rapid thermal annealing was performed to enhance the optical quality of the material. Intense low temperature photoluminescence was obtained from GaAsN down to 0.9 eV (1.38 ?m).

  17. Low-temperature vapor-phase etching of silicon carbide by dioxygen difluoride

    NASA Astrophysics Data System (ADS)

    Moalem, M.; Olander, D. R.; Balooch, M.

    1995-06-01

    Efficient room-temperature vapor-phase etching of SiC by the compound dioxygen difluoride (FOOF) has been demonstrated. FOOF was generated using a design based on thermal-atomization technique which produced gram quantities of the compound per hour. On both poly- and epitype silicon carbide at room temperature, about 6% of the FOOF molecules striking the surface reacted to form SiF4 and CO. Examination by atomic force microscopy (AFM) showed that the roughness and morphology of the etched surface were virtually indistinguishable from those of the original surface. No residues or anisotropies were present on the etched surface.

  18. Extinction coefficients for the ?-chlorobenzyl and anilino radicals in the vapor phase

    NASA Astrophysics Data System (ADS)

    Bayrakçeken, Fuat; Sa?at, Leman

    1989-06-01

    The absorption spectra of the ?-chlorobenzyl and anilino radicals have been recorded in the vapor phase together with a new band for ?-chlorobenzyl radical at shorter wavelengths (236.5 nm), probably the first Rydberg band of the radical, and subsequent reactions have been investigated by kinetic spectroscopy and gas-liquid chromatography. Flash duration time was short enough to follow the kinetics of the radical decay which occurred predominantly by bimolecular recombination. The absolute extinction coefficients are calculated from the optical densities of the absorption bands, and gas-liquid chromatography data.

  19. Performance Testing of the Vapor Phase Catalytic Ammonia Removal Engineering Development Unit

    NASA Technical Reports Server (NTRS)

    Flynn, Michael; Tleimat, Maher; Nalette, Tim; Quinn, Gregory

    2005-01-01

    This paper describes the results of performance testing of the Vapor Phase Catalytic Ammonia Removal (VPCAR) technology. The VPCAR technology is currently being developed by NASA as a Mars transit vehicle water recycling system. NASA has recently completed-a grant-to develop a next generation VPCAR system. This grant concluded with the shipment of the final deliverable to NASA on 8/31/03. This paper presents the results of mass, power, volume, and acoustic measurements for the delivered system. Product water purity analysis for a Mars transit mission and a simulated planetary base wastewater ersatz are also provided.

  20. Low-Temperature Metalorganic Vapor Phase Epitaxy (MOVPE) of GaN using Tertiarybutylhydrazine

    NASA Astrophysics Data System (ADS)

    Pohl, Udo; Knorr, Kerstin; Möller, Carsten; Gernert, Ulrich; Richter, Wolfgang; Bläsing, Jürgen; Christen, Jürgen; Gottfriedsen, Jochen; Schumann, Herbert

    1999-02-01

    Tertiarybutylhydrazine was used as a novel nitrogen source for metalorganic vapor phase epitaxy of GaN at low temperatures. Hexagonal epilayers with optically smooth and specular surfaces were grown with trimethylgallium on basal plane sapphire as well as GaAs(111)B substrates. On (001)-oriented GaAs, predominantly cubic GaN was grown. Incorporation of carbon impurities was distinctly lower than in layers grown with dimethylhydrazine. The epilayer quality is presently limited by the purity of the available tertiarybutylhydrazine.

  1. Thermodynamics of Si(OH)4 in the vapor phase of water: Henry’s and vapor-liquid distribution constants, fugacity and cross virial coefficients

    NASA Astrophysics Data System (ADS)

    Plyasunov, Andrey V.

    2012-01-01

    The fugacity coefficients of Si(OH)4 are evaluated from solubilities of solid phases of SiO2 in the vapor phase of water. The virial equation of state, truncated at the third virial coefficient, is employed to describe the fugacity coefficients of Si(OH)4. The temperature dependencies of the second, B12, and the third, C112, cross virial coefficients for H2O-Si(OH)4 interactions are approximated by empirical relations. It is found that silica-water interactions in the vapor phase are significantly more non-ideal compared to water-water interactions. Knowledge of B12 and C112 allows calculation of solubilities of quartz (Q) and amorphous silica (AS) in steam up to the density of 200 kg m-3 in satisfactory agreement with available data, and should provide reasonable solubility values at temperatures where no experimental results exist. The calculated values of the solubility of Q and AS in saturated vapor up to the critical temperature of water, Tc, are tabulated. The partial molar properties of dilute solutes close to the critical point of water are governed by the Krichevskii parameter, the value of which for Si(OH)4 is evaluated from available data (mainly vapor-liquid distribution constants for silica) to be equal to -187 ± 10 MPa. The knowledge of the thermodynamic properties of Si(OH)4 in the ideal gas state and in the state of the standard solution in liquid water allows calculating Henry’s constant, kH, for Si(OH)4 up to 623.15 K at water saturation pressure P1?. The theoretically-based equation, containing the Krichevskii parameter, allows extrapolating kH values all the way toward the critical temperature of water. This, in turn, makes possible calculation of the solubility of quartz and amorphous silica in liquid water at P1? at all temperatures up to Tc. The presented results should be useful for modeling solid-liquid-vapor, solid-vapor and liquid-vapor equilibria in the H2O-SiO2 system at steam densities up to 200 kg m-3.

  2. Effectiveness of cigarette filter tips for reducing cadmium in relation to other mainstream smoke constituents

    SciTech Connect

    Bache, C.A.; Lisk, D.J.; Shane, B.S.; Hoffmann, D.; Adams, J.D.

    1987-01-01

    The effectiveness of filter tips for reducing cadmium, tar, nicotine, carbon monoxide and carbon dioxide in cigarettes was studied. The cigarettes were made from tobacco grown on municipal sewage sludge-amended soil and were therefore high in cadmium. When machine-smoked, filter tips did not result in a significant reduction of cadmium deposited on Cambridge filters. This may indicate that a considerable fraction of cadmium is present in the vapor phase of the smoke and therefore not reduced to the same extent as the tar by certain filters. Nicotine and carbon monoxide were reduced to a lesser extent than tar. This indicates that the filter tip has influenced the combustion of the tobacco column during smoking.

  3. Vapor-phase synthesis of uniform silica spheres through two-stage hydrolysis of SiCl{sub 4}

    SciTech Connect

    Park, Hoey K. [Department of Chemical Engineering, Kongju National University, 182 Shinkwandong, Kongju, Chungnam 314-701 (Korea, Republic of); Park, Kyun Y. [Department of Chemical Engineering, Kongju National University, 182 Shinkwandong, Kongju, Chungnam 314-701 (Korea, Republic of)], E-mail: kypark@kongju.ac.kr

    2008-11-03

    We report, for the first time, a vapor-phase synthesis of nearly monodispersed silica spheres 250-300 nm in size through a two-stage hydrolysis of SiCl{sub 4}. In the first stage, SiCl{sub 4} vapor was partially hydrolyzed with water vapor in a batch reactor at 150 deg. C to form silicon oxychloride particles, nearly monodispersed and spherical. In the second stage, these oxychloride particles were converted into silica particles through further hydrolysis at 1000 deg. C in a tubular reactor, while the morphology and size after the first-stage reaction remained virtually unchanged.

  4. Uptake rate constants and partition coefficients for vapor phase organic chemicals using semipermeable membrane devices (SPMDs)

    NASA Astrophysics Data System (ADS)

    Cranor, Walter L.; Alvarez, David A.; Huckins, James N.; Petty, Jimmie D.

    To fully utilize semipermeable membrane devices (SPMDs) as passive samplers in air monitoring, data are required to accurately estimate airborne concentrations of environmental contaminants. Limited uptake rate constants ( kua) and no SPMD air partitioning coefficient ( Ksa) existed for vapor-phase contaminants. This research was conducted to expand the existing body of kinetic data for SPMD air sampling by determining kua and Ksa for a number of airborne contaminants including the chemical classes: polycyclic aromatic hydrocarbons, organochlorine pesticides, brominated diphenyl ethers, phthalate esters, synthetic pyrethroids, and organophosphate/organosulfur pesticides. The kuas were obtained for 48 of 50 chemicals investigated and ranged from 0.03 to 3.07 m 3 g -1 d -1. In cases where uptake was approaching equilibrium, Ksas were approximated. Ksa values (no units) were determined or estimated for 48 of the chemicals investigated and ranging from 3.84E+5 to 7.34E+7. This research utilized a test system (United States Patent 6,877,724 B1) which afforded the capability to generate and maintain constant concentrations of vapor-phase chemical mixtures. The test system and experimental design employed gave reproducible results during experimental runs spanning more than two years. This reproducibility was shown by obtaining mean kua values ( n = 3) of anthracene and p, p'-DDE at 0.96 and 1.57 m 3 g -1 d -1 with relative standard deviations of 8.4% and 8.6% respectively.

  5. Compound nuclear decay and the liquid to vapor phase transition: a physical picture

    E-print Network

    L. G. Moretto; J. B. Elliott; L. Phair

    2005-07-08

    Analyses of multifragmentation in terms of the Fisher droplet model (FDM) and the associated construction of a nuclear phase diagram bring forth the problem of the actual existence of the nuclear vapor phase and the meaning of its associated pressure. We present here a physical picture of fragment production from excited nuclei that solves this problem and establishes the relationship between the FDM and the standard compound nucleus decay rate for rare particles emitted in first-chance decay. The compound thermal emission picture is formally equivalent to a FDM-like equilibrium description and avoids the problem of the vapor while also explaining the observation of Boltzmann-like distribution of emission times. In this picture a simple Fermi gas thermometric relation is naturally justified and verified in the fragment yields and time scales. Low energy compound nucleus fragment yields scale according to the FDM and lead to an estimate of the infinite symmetric nuclear matter critical temperature between 18 and 27 MeV depending on the choice of the surface energy coefficient of nuclear matter.

  6. Uptake rate constants and partition coefficients for vapor phase organic chemicals using semipermeable membrane devices (SPMDs)

    USGS Publications Warehouse

    Cranor, W.L.; Alvarez, D.A.; Huckins, J.N.; Petty, J.D.

    2009-01-01

    To fully utilize semipermeable membrane devices (SPMDs) as passive samplers in air monitoring, data are required to accurately estimate airborne concentrations of environmental contaminants. Limited uptake rate constants (kua) and no SPMD air partitioning coefficient (Ksa) existed for vapor-phase contaminants. This research was conducted to expand the existing body of kinetic data for SPMD air sampling by determining kua and Ksa for a number of airborne contaminants including the chemical classes: polycyclic aromatic hydrocarbons, organochlorine pesticides, brominated diphenyl ethers, phthalate esters, synthetic pyrethroids, and organophosphate/organosulfur pesticides. The kuas were obtained for 48 of 50 chemicals investigated and ranged from 0.03 to 3.07??m3??g-1??d-1. In cases where uptake was approaching equilibrium, Ksas were approximated. Ksa values (no units) were determined or estimated for 48 of the chemicals investigated and ranging from 3.84E+5 to 7.34E+7. This research utilized a test system (United States Patent 6,877,724 B1) which afforded the capability to generate and maintain constant concentrations of vapor-phase chemical mixtures. The test system and experimental design employed gave reproducible results during experimental runs spanning more than two years. This reproducibility was shown by obtaining mean kua values (n??=??3) of anthracene and p,p???-DDE at 0.96 and 1.57??m3??g-1??d-1 with relative standard deviations of 8.4% and 8.6% respectively.

  7. Insight into the structure of polymer-silica nano-composites prepared by vapor-phase.

    PubMed

    Halasz, Istvan; Kierys, Agnieszka; Goworek, Jacek

    2015-03-01

    Using a new synthesis technique, in which mesoporous Amberlite XAD7HP resin beads swollen with TEOS were exposed to vapors of either (H2O+HCl) or (H2O+NH3), we obtained smooth, porous, mechanically stable silica gel spheres after burning out the sacrificial organic template. Combined N2 sorption, SEM, TEM, (29)Si NMR, and Raman measurements were used to characterize the physical properties and molecular structures of the intermediate and final gels. Our atomically resolved TEM pictures provide the first visual demonstration of the presence of 3 to 6 member siloxane rings predicted by our Raman studies and other indirect methods. It is demonstrated that the physical appearance, morphology and porosity of the acid and base set gels are different from each other and also from those silica gels that were earlier polymerized from TEOS or Na-silicate saturated Amberlite XAD7HP with aqueous NH4OH or HCl solutions in liquid phase. We show that the different physical properties of the vapor-phase set gels are associated with different gelling rates at acidic and basic conditions, which generates molecular differences both in the intermediate and the final products. PMID:25490564

  8. Bubbles in liquids with phase transition. Part 1. On phase change of a single vapor bubble in liquid water

    NASA Astrophysics Data System (ADS)

    Dreyer, Wolfgang; Duderstadt, Frank; Hantke, Maren; Warnecke, Gerald

    2012-11-01

    In the forthcoming second part of this paper a system of balance laws for a multi-phase mixture with many dispersed bubbles in liquid is derived where phase transition is taken into account. The exchange terms for mass, momentum and energy explicitly depend on evolution laws for total mass, radius and temperature of single bubbles. Therefore in the current paper we consider a single bubble of vapor and inert gas surrounded by the corresponding liquid phase. The creation of bubbles, e.g. by nucleation is not taken into account. We study the behavior of this bubble due to condensation and evaporation at the interface. The aim is to find evolution laws for total mass, radius and temperature of the bubble, which should be as simple as possible but consider all relevant physical effects. Special attention is given to the effects of surface tension and heat production on the bubble dynamics as well as the propagation of acoustic elastic waves by including slight compressibility of the liquid phase. Separately we study the influence of the three phenomena heat conduction, elastic waves and phase transition on the evolution of the bubble. We find ordinary differential equations that describe the bubble dynamics. It turns out that the elastic waves in the liquid are of greatest importance to the dynamics of the bubble radius. The phase transition has a strong influence on the evolution of the temperature, in particular at the interface. Furthermore the phase transition leads to a drastic change of the water content in the bubble. It is shown that a rebounding bubble is only possible, if it contains in addition an inert gas. In Part 2 of the current paper the equations derived are sought in order to close the system of equations for multi-phase mixture balance laws for dispersed bubbles in liquids involving phase change.

  9. Metal organic vapor phase epitaxy of hexagonal Ge-Sb-Te (GST)

    NASA Astrophysics Data System (ADS)

    Schuck, Martin; Rieß, Sally; Schreiber, Marcel; Mussler, Gregor; Grützmacher, Detlev; Hardtdegen, Hilde

    2015-06-01

    Epitaxial, hexagonal Ge-Sb-Te was grown on Si(111) substrates by Metal Organic Vapor Phase Epitaxy (MOVPE) using the precursor digermane. The effect of reactor pressure, growth temperature and in situ pre-treatment on morphology and Ge-Sb-Te composition was studied. The composition is sensitive to reactor pressure and growth temperature. Compositional control is achieved at a reactor pressure of 50 hPa. Substrate pre-treatment affects film coalescence. The use of hydrogen and a suitable precursor pre-treatment leads to enhanced surface coverage. X-ray diffraction reveals a trigonal structure with lattice parameters close to that reported for Ge1Sb2Te4 crystallizing in the R 3 bar m phase. The composition was confirmed by energy-dispersive X-ray spectroscopy.

  10. Simulation of the gas-phase processes in remote-plasma-activated chemical-vapor deposition of silicon dielectrics using rare gas-silane-

    E-print Network

    Kushner, Mark

    Simulation of the gas-phase processes in remote-plasma-activated chemical-vapor deposition- duce a flux of specificradicals to the substrate. Remote-plasma-activated chemical-vapor deposition September1991;acceptedfor publication 17January 1992) Remote-plasma-activatedchemical-vapor deposition

  11. Stimulated topological condensation of 'vapor phase' photons and possible implications for space power technology

    SciTech Connect

    Dudziak, M. [MODIS Corporation, Washington District of Columbia and Dept. of Physics, Moscow State University (Russian Federation); Pitkaenen, M. [Dept. of Physics, University of Helsinki, Helsinki (Finland)

    1999-01-22

    A quantum topological network model that might allow for the production of energy through the employment of vacuum electromagnetic currents form is based upon foundational principles of topological geometrodynamics (TGD) (Pitkaenen, 1995a, 1995b). Such a production photon-factory would have the capability of drawing upon a seemingly inexhaustible supply of what in TGD formalism is a 'vapor phase' of photons. Particularly in the presence of Bose-Einstein condensate photons, it is theoretically possible to convert these 'vapor phase' photons into condensed photons that can then be harnessed and transformed into useful kinetic energy by more traditional means. TGD presents a view, similar to certain string models, of spacetimes as surfaces within an 8-dimensional space H that is a product of Minkowski space future lightcone M{sub +}{sup 4} and a complex projective space CP{sub 2}. TGD model allows for topological merging, akin to the condensation process in classical physics, of free elementary particle like 3-surfaces to the background surface of larger size. 'Topological evaporation' corresponds to the reverse of this process in which particles go 'outside' the classical spacetime. TGD predicts vacuum electromagnetic fields having as their source vacuum gauge currents instead of currents composed of elementary particles. The vacuum gauge currents generate coherent states of photons and for the lightlike vacuum currents the coherent state arises in a resonant-like manner. A presence of Bose-Einstein condensates of photons in a nearby spacetime sheet external to the coherent-state generator would allow for a transfer of photons from that sheet into a vapor phase. The capture of these photons into an electro-mechanical propulsion system may provide a source of energy which can be converted into a form useful for the propulsion and acceleration of a space craft. An emission of coherent light from a region not containing charged particles would be a clear indication of vacuum current presence. Whether this entire process, if it is feasible, could generate enough useful energy for spacecraft propulsion is a major open question. However, it does appear that in the least such a mechanism could provide for some type of quantum communication with storage of information in both phase and intensity of the coherent emf and with the vacuum currents acting as quantum antennae. An examination of certain models known as quantum cellular automata and networks (QCAM, CLAN) (Dudziak, 1993) and synchronized heterogeneous dynamical networks (SHDN) (Chinarov, 1998) may provide some further insight into how the suggested stimulated coherent production of photons might be initiated, controlled, and stabilized in an application for space travel or communication.

  12. Vapor-deposited non-crystalline phase vs ordinary glasses and supercooled liquids: Subtle thermodynamic and kinetic differences

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Deepanjan; Sadtchenko, Vlad

    2015-04-01

    Vapor deposition of molecules on a substrate often results in glassy materials of high kinetic stability and low enthalpy. The extraordinary properties of such glasses are attributed to high rates of surface diffusion during sample deposition, which makes it possible for constituents to find a configuration of much lower energy on a typical laboratory time scale. However, the exact nature of the resulting phase and the mechanism of its formation are not completely understood. Using fast scanning calorimetry technique, we show that out-of-equilibrium relaxation kinetics and possibly the enthalpy of vapor-deposited films of toluene and ethylbenzene, archetypical fragile glass formers, are distinct from those of ordinary supercooled phase even when the deposition takes place at temperatures above the ordinary glass softening transition temperatures. These observations along with the absolute enthalpy dependences on deposition temperatures support the conjecture that the vapor-deposition may result in formation of non-crystalline phase of unique structural, thermodynamic, and kinetic properties.

  13. 19 CFR 159.5 - Cigars, cigarettes, and cigarette papers and tubes.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...Cigars, cigarettes, and cigarette papers and tubes. 159.5 Section 159.5 Customs...cigarettes, and cigarette papers and tubes. The internal revenue taxes imposed...cigarettes, and cigarette papers and tubes under section 5701 or 7652, Internal...

  14. 19 CFR 159.5 - Cigars, cigarettes, and cigarette papers and tubes.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...Cigars, cigarettes, and cigarette papers and tubes. 159.5 Section 159.5 Customs...cigarettes, and cigarette papers and tubes. The internal revenue taxes imposed...cigarettes, and cigarette papers and tubes under section 5701 or 7652, Internal...

  15. 19 CFR 159.5 - Cigars, cigarettes, and cigarette papers and tubes.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...Cigars, cigarettes, and cigarette papers and tubes. 159.5 Section 159.5 Customs...cigarettes, and cigarette papers and tubes. The internal revenue taxes imposed...cigarettes, and cigarette papers and tubes under section 5701 or 7652, Internal...

  16. 19 CFR 159.5 - Cigars, cigarettes, and cigarette papers and tubes.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...Cigars, cigarettes, and cigarette papers and tubes. 159.5 Section 159.5 Customs...cigarettes, and cigarette papers and tubes. The internal revenue taxes imposed...cigarettes, and cigarette papers and tubes under section 5701 or 7652, Internal...

  17. 19 CFR 159.5 - Cigars, cigarettes, and cigarette papers and tubes.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...Cigars, cigarettes, and cigarette papers and tubes. 159.5 Section 159.5 Customs...cigarettes, and cigarette papers and tubes. The internal revenue taxes imposed...cigarettes, and cigarette papers and tubes under section 5701 or 7652, Internal...

  18. The Effect Of ZnO Addition On Co/C Catalyst For Vapor And Aqueous Phase Reforming Of Ethanol

    SciTech Connect

    Davidson, Stephen; Sun, Junming; Hong, Yongchun; Karim, Ayman M.; Datye, Abhaya K.; Wang, Yong

    2014-02-05

    The effect of ZnO addition on the oxidation behavior of Co along with catalytic performance in vapor and aqueous phase reforming of ethanol were investigated on Co supported on carbon black (XC-72R). Carbon was selected to minimize the support interactions. Effect of ZnO addition during both vapor and aqueous phase reforming were compared at 250 °C. ZnO addition inhibited the reduction of cobalt oxides by H2 and created surface sites for H2O activation. During vapor phase reforming at 450 °C the redox of cobalt, driven by steam oxidation and H2 reduction, trended to an equilibrium of Co0/Co2+. ZnO showed no significant effect on cobalt oxidation, inferred from the minor changes of C1 product yield. Surface sites created by ZnO addition enhanced water activation and oxidation of surface carbon species, increasing CO2 selectivity. At 250 °C cobalt reduction was minimal, in situ XANES demonstrated that ZnO addition significantly facilitated oxidation of Co0 under vapor phase reforming conditions, demonstrated by lower C1 product yield. Sites introduced by ZnO addition improved the COx selectivity at 250 °C. Both Co/C and Co-ZnO/C rapidly oxidized under aqueous phase reaction conditions at 250 °C, showing negligible activity in aqueous phase reforming. This work suggests that ZnO affects the activation of H2O for Co catalysts in ethanol reforming.

  19. A three-dimensional phase field model for nanowire growth by the vapor-liquid-solid mechanism

    NASA Astrophysics Data System (ADS)

    Wang, Yanming; Ryu, Seunghwa; McIntyre, Paul C.; Cai, Wei

    2014-07-01

    We present a three-dimensional multi-phase field model for catalyzed nanowire (NW) growth by the vapor-liquid-solid (VLS) mechanism. The equation of motion contains both a Ginzburg-Landau term for deposition and a diffusion (Cahn-Hilliard) term for interface relaxation without deposition. Direct deposition from vapor to solid, which competes with NW crystal growth through the molten catalyst droplet, is suppressed by assigning a very small kinetic coefficient at the solid-vapor interface. The thermodynamic self-consistency of the model is demonstrated by its ability to reproduce the equilibrium contact angles at the VLS junction. The incorporation of orientation dependent gradient energy leads to faceting of the solid-liquid and solid-vapor interfaces. The model successfully captures the curved shape of the NW base and the Gibbs-Thomson effect on growth velocity.

  20. The intractable cigarette ‘filter problem’

    Microsoft Academic Search

    Bradford Harris

    2011-01-01

    BackgroundWhen lung cancer fears emerged in the 1950s, cigarette companies initiated a shift in cigarette design from unfiltered to filtered cigarettes. Both the ineffectiveness of cigarette filters and the tobacco industry's misleading marketing of the benefits of filtered cigarettes have been well documented. However, during the 1950s and 1960s, American cigarette companies spent millions of dollars to solve what the

  1. Gas phase and surface reactions in subatmospheric chemical vapor deposition of tetraethylorthosilicate-ozone

    SciTech Connect

    Gill, W.N.; Ganguli, S. [Department of Chemical Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180-3590 (United States)] [Department of Chemical Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180-3590 (United States)

    1997-07-01

    A new physical-chemical model, which applies over a wide range of operating pressures, describes the gas phase and surface reactions in subatmospheric chemical vapor deposition of silicon dioxide for producing inter-layer dielectrics in a cold-wall reactor. Tetraethylorthosilicate (TEOS) reacts in the gas phase to form an intermediate which is adsorbed and reacts on the surface to produce a silicon dioxide film. The results compare favorably with experimental data over a pressure range of 100{endash}600 Torr and a temperature range of 370{endash}500{degree}C. The concentration distributions of TEOS, intermediate and ozone in the gas phase and their ratios at the surface of the wafer are determined to study gas phase nucleation and the relationship between composition distributions and film quality. Previous models based on low pressure data in the range of 30{endash}90 Torr need to be modified to predict accurately the rates of deposition from 100 Torr to atmospheric pressure. Gas phase reactions cause the maximum in the deposition rates to shift to higher pressures at lower deposition temperatures, both in the model and experiments. At higher pressures, particulates are formed by the gas phase reactions which must be included to represent properly the chemical dynamics of the process. The deposition rate increases up to an asymptotic value as the TEOS flow rate is increased; above this level no further increase in growth rate occurs. This is a consequence of the basic mechanism of the surface reaction which predicts the asymptotic behavior observed. {copyright} {ital 1997 American Vacuum Society.}

  2. Vapor phase ketonization of acetic acid on ceria based metal oxides

    SciTech Connect

    Liu, Changjun; Karim, Ayman M.; Lebarbier, Vanessa MC; Mei, Donghai; Wang, Yong

    2013-12-01

    The activities of CeO2, Mn2O3-CeO2 and ZrO2-CeO2 were measured for acetic acid ketonization under reaction conditions relevant to pyrolysis vapor upgrading. We show that the catalyst ranking changed depending on the reaction conditions. Mn2O3-CeO2 was the most active catalyst at 350 oC, while ZrO2 - CeO2 was the most active catalyst at 450 oC. Under high CO2 and steam concentration in the reactants, Mn2O3-CeO2 was the most active catalyst at 350 and 450 °C. The binding energies of steam and CO2 with the active phase were calculated to provide the insight into the tolerance of Mn2O3-CeO2 to steam and CO2.

  3. Supersaturation in nucleus and spiral growth of GaN in metal organic vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Akasaka, Tetsuya; Kobayashi, Yasuyuki; Kasu, Makoto

    2010-10-01

    Nucleus and spiral growth mechanisms of GaN were experimentally studied by varying the degree of supersaturation, ?, in selective-area metal organic vapor phase epitaxy. The spiral growth rate of GaN increased proportionally to ?2 in the ? range from 0.0632 to 0.230. The nucleus growth rate of GaN was much smaller than the spiral one in the ? range. The nucleation rate was almost zero at ? lower than 0.130, suddenly increased at higher ? values, and reached ˜107 cm-2 s-1 at ? of 0.230. These results are consistent with a theoretical analysis [W. K. Burton, N. Cabrera, and F. C. Frank, Philos. Trans. R. Soc. London, Ser. A 243, 299 (1951)].

  4. Observation of compositional fluctuations in GaNAs alloys grown by metalorganic vapor-phase epitaxy

    NASA Astrophysics Data System (ADS)

    Takahashi, Mitsuo; Moto, Akihiro; Tanaka, So; Tanabe, Tatsuya; Takagishi, Shigenori; Karatani, Kouichi; Nakayama, Masaaki; Matsuda, Kazunari; Saiki, Toshiharu

    2000-12-01

    Photoluminescence (PL) spectra and scanning near-field optical microscope (SNOM) images have been measured at low temperature to investigate the compositional fluctuations in GaN xAs 1- x epilayers grown on GaAs by metalorganic vapor-phase epitaxy. Time-resolved PL has been employed to study the optical transitions and their dynamic processes. Our results suggest that the PL emission from GaN xAs 1- x epilayer at low temperature is dominated by localized exciton recombination induced by compositional fluctuations. Furthermore, we directly observed the distribution of the compositional inhomogeneity in the GaN xAs 1- x samples even with a small N-content of 0.5% by measuring SNOM images. The emission spot size of less than 1 ?m is estimated for the GaN xAs 1- x (N=0.5%) epilayer, and its size tends to decrease with increasing nitrogen concentration.

  5. High rate InN growth by two-step precursor generation hydride vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Togashi, Rie; Thieu, Quang Tu; Murakami, Hisashi; Kumagai, Yoshinao; Ishitani, Yoshihiro; Monemar, Bo; Koukitu, Akinori

    2015-07-01

    The increase of InN growth rate by a newly developed two-step precursor generation hydride vapor phase epitaxy (HVPE) was investigated for the preparation of freestanding InN and InGaN substrates. An elevated growth rate was achieved by the complete conversion of InCl generated in the first source zone to InCl3 in the second source zone, by the supply of additional Cl2. The growth rate reached 12.4 ?m/h at a growth temperature of 600 °C, and the rate was observed to decrease above this temperature. Specular InN layers grown at 650 °C exhibited a sharp room temperature photoluminescence peak at 0.73 eV with a bulk electron concentration of 1.2×1018 cm-3.

  6. Influence of the carrier gas molar mass on the particle formation in a vapor phase.

    PubMed

    Braun, S; Römer, F; Kraska, T

    2009-08-14

    The influence of the molar mass of a carrier gas on the formation of nanoparticles in the vapor phase is investigated. The function of the carrier gas atmosphere is the regulation of the particle temperature by collisions with the cluster surface. The aim of this work is to optimize the carrier gas in a simulation in order to mimic a large amount of carrier gas atoms by few gas atoms with effective parameters. In this context the efficiency of the heat exchange with the carrier gas depending on its molar mass is analyzed. As a result one finds for varying molar masses and unchanged interaction parameters a competition between the efficiency and the number of the collisions. For too small molar masses the energy exchange per collision is too small while for too high masses the carrier gas atoms become very slow, decreasing the number of collisions. PMID:19691389

  7. Low-temperature vapor-phase etching of silicon carbide by dioxygen difluoride

    SciTech Connect

    Moalem, M.; Olander, D.R. [Department of Nuclear Engineering, University of California, Berkeley, California 94720 (United States)] [Department of Nuclear Engineering, University of California, Berkeley, California 94720 (United States); Balooch, M. [Chemistry and Material Science Division, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)] [Chemistry and Material Science Division, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

    1995-06-19

    Efficient room-temperature vapor-phase etching of SiC by the compound dioxygen difluoride (FOOF) has been demonstrated. FOOF was generated using a design based on thermal-atomization technique which produced gram quantities of the compound per hour. On both poly- and epitype silicon carbide at room temperature, about 6% of the FOOF molecules striking the surface reacted to form SiF{sub 4} and CO. Examination by atomic force microscopy (AFM) showed that the roughness and morphology of the etched surface were virtually indistinguishable from those of the original surface. No residues or anisotropies were present on the etched surface. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  8. Hydride vapor phase GaN films with reduced density of residual electrons and deep traps

    SciTech Connect

    Polyakov, A. Y., E-mail: aypolyakov@gmail.com [National University of Science and Technology MISiS, Leninsky Ave. 4, 119049 Moscow (Russian Federation); Smirnov, N. B.; Govorkov, A. V.; Yugova, T. G. [Institute of Rare Metals, B. Tolmachevsky 5, 119017 Moscow (Russian Federation); Cox, H.; Helava, H.; Makarov, Yu. [Nitride Crystals, Inc., 181E Industry Ct., Ste. B, Deer Park, New York 11729 (United States); Usikov, A. S. [Nitride Crystals, Inc., 181E Industry Ct., Ste. B, Deer Park, New York 11729 (United States); Saint-Petersburg National Research University of Information Technologies, Mechanics and Optics, 49 Kronverkskiy Ave., 197101 Saint Petersburg (Russian Federation)

    2014-05-14

    Electrical properties and deep electron and hole traps spectra are compared for undoped n-GaN films grown by hydride vapor phase epitaxy (HVPE) in the regular process (standard HVPE samples) and in HVPE process optimized for decreasing the concentration of residual donor impurities (improved HVPE samples). It is shown that the residual donor density can be reduced by optimization from ?10{sup 17}?cm{sup ?3} to (2–5)?×?10{sup 14}?cm{sup ?3}. The density of deep hole traps and deep electron traps decreases with decreased donor density, so that the concentration of deep hole traps in the improved samples is reduced to ?5?×?10{sup 13}?cm{sup ?3} versus 2.9?×?10{sup 16}?cm{sup ?3} in the standard samples, with a similar decrease in the electron traps concentration.

  9. Spatially resolved optical control of GaN grown by selective area hydride vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Réveret, F.; André, Y.; Gourmala, O.; Leymarie, J.; Mihailovic, M.; Lagarde, D.; Gil, E.; Castelluci, D.; Trassoudaine, A.

    2015-07-01

    Hydride Vapor Phase Epitaxy (HVPE) growth process is still efficient for the growth of high quality GaN material. In situ-characterization techniques are extremely difficult to implement inside HVPE hot wall reactors. A method based on selective area growth coupled to spatially resolved optical spectroscopies, micro-photoluminescence and micro-reflectivity is developed for a control of GaN optical quality and strain at different growth stages. As highly reproducible HVPE process is used with a two-step epitaxial lateral overgrowth procedure to produce 80 ?m thick GaN layers presenting a weak residual strain with high optical quality comparable to free-standing GaN layers.

  10. High-resolution discrete absorption spectrum of ?-methallyl free radical in the vapor phase

    NASA Astrophysics Data System (ADS)

    Bayrakçeken, Fuat; Telatar, Ziya; Ar?, Fikret; Tunçyürek, Lale; Karaaslan, ?pek; Yaman, Ali

    2006-09-01

    The ?-methallyl free radical is formed in the flash photolysis of 3-methylbut-1-ene, and cis-pent-2-ene in the vapor phase, and then subsequent reactions have been investigated by kinetic spectroscopy and gas-liquid chromatography. The photolysis flash was of short duration and it was possible to follow the kinetics of the radicals' decay, which occurred predominantly by bimolecular recombination. The measured rate constant for the ?-methallyl recombination was (3.5 ± 0.3) × 10 10 mol -1 l s -1 at 295 ± 2 K. The absolute extinction coefficients of the ?-methallyl radical are calculated from the optical densities of the absorption bands. Detailed analysis of related absorption bands and lifetime measurements in the original ?-methallyl high-resolution discrete absorption spectrum image were also carried out by image processing techniques.

  11. Oxygen quenching of excited singlet and triplet states of polycyclic aromatic hydrocarbons in the vapor phase

    NASA Astrophysics Data System (ADS)

    Zalesskaya, G. A.; Kuchinsky, A. V.

    2010-01-01

    The quenching rate constants of excited singlet ( kSO2) and triplet ( kTO2) states by oxygen were investigated in the vapor phase for polycyclic aromatic hydrocarbons having distinguishing oxidation potentials Eox. The significant spread in the rate constants was found (4 × 10 5 s -1 Torr -1 < kSO2 < 1.2 × 10 7 s -1 Torr -1; 5 × 10 2 < kTO2 < 4 × 10 5 s -1 Torr -1). The values of both kSO2 and kTO2 change linearly in the logarithmic scale with free energy change for complete electron transfer ? GET, which points that the charge-transfer interactions are involved in the oxygen quenching of the S 1 and T 1 states.

  12. Influence of the carrier gas molar mass on the particle formation in a vapor phase

    NASA Astrophysics Data System (ADS)

    Braun, S.; Römer, F.; Kraska, T.

    2009-08-01

    The influence of the molar mass of a carrier gas on the formation of nanoparticles in the vapor phase is investigated. The function of the carrier gas atmosphere is the regulation of the particle temperature by collisions with the cluster surface. The aim of this work is to optimize the carrier gas in a simulation in order to mimic a large amount of carrier gas atoms by few gas atoms with effective parameters. In this context the efficiency of the heat exchange with the carrier gas depending on its molar mass is analyzed. As a result one finds for varying molar masses and unchanged interaction parameters a competition between the efficiency and the number of the collisions. For too small molar masses the energy exchange per collision is too small while for too high masses the carrier gas atoms become very slow, decreasing the number of collisions.

  13. An Assessment of the Technical Readiness of the Vapor Phase Catalytic Ammonia Removal Process (VPCAR) Technology

    NASA Technical Reports Server (NTRS)

    Flynn, Michael

    2000-01-01

    This poster provides an assessment of the technical readiness of the Vapor Phase Catalytic Ammonia Removal Process (VPCAR). The VPCAR technology is a fully regenerative water recycling technology designed specifically for applications such as a near term Mars exploration mission. The VPCAR technology is a highly integrated distillation/catalytic oxidation based water processor. It is designed to accept a combined wastewater stream (urine, condensate, and hygiene) and produces potable water in a single process step which requires -no regularly scheduled re-supply or maintenance for a 3 year mission. The technology is designed to be modular and to fit into a volume comparable to a single International Space Station Rack (when sized for a crew of 6). This poster provides a description of the VPCAR technology and a summary of the current performance of the technology. Also provided are the results of two separate NASA sponsored system trade studies which investigated the potential payback of further development of the VPCAR technology.

  14. Optical Properties of ZnO Soccer-Ball Structures Grown by Vapor Phase Transport

    NASA Astrophysics Data System (ADS)

    Nam, Giwoong; Lee, Sang-heon; Kim, Soaram; Kim, Min Su; Kim, Do Yeob; Gug Yim, Kwang; Lee, Dong-Yul; Kim, Jin Soo; Kim, Jong Su; Son, Jeong-Sik; Kim, Sung-O.; Jung, Jae Hak; Leem, Jae-Young

    2012-02-01

    ZnO soccer balls were grown on an Au-catalyzed Si(100) substrate by vapor phase transport (VPT) with a mixture of zinc oxide and graphite powders. Temperature-dependent PL was carried out to investigate the mechanism governing the quenching behavior of the PL spectra. From the PL spectra of the ZnO soccer balls at 10 K, several PL peaks were observed at 3.365, 3.318, 3.249, and 3.183 eV corresponding to excitons bound to neutral donors (DoX), a donor-acceptor pair (DAP), first-order longitudinal optical phonon replica of donor-acceptor pair (DAP-1LO), and DAP-2LO, respectively. The mixed system composed of the free exciton (FX) and DoX and the DAP radiative lifetimes were estimated with a theoretical relation between the lifetime and the spectral width. The exciton radiative lifetimes were observed to increase linearly with temperature.

  15. Vapor-phase adsorption kinetics of 1-decene on H-terminated Si(100).

    SciTech Connect

    Kosuri, Madhava R. (University of New Mexico, Albuquerque, NM); Mayer, Thomas Michael; Han, Sang M. (University of New Mexico, Albuquerque, NM); Bunker, Bruce Conrad; Li, Qiming (University of New Mexico, Albuquerque, NM); Gerung, Henry (University of New Mexico, Albuquerque, NM)

    2003-06-01

    We have investigated in situ and in real time vapor-phase self-assembly of 1-decene on Si, using attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIRS). The adsorption of 1-decene on hydrogenated Si(100) results in a decane-terminated hydrophobic surface, indicated by the sessile-drop water contact angle at 107 {+-} 2. This maximum contact angle is achieved at 160 C under 30 mTorr of vapor-phase 1-decene. The fractional surface coverage of decane, calculated from the IR absorbance of C-H stretching vibrational modes near 2900 cm{sup -1}, follows a Langmuir isotherm. The absolute surface coverage calculated from the IR absorbance saturates at 3.2 x 10{sup 14} cm{sup -2}. On the basis of this isotherm, the empirical rate constant (k{prime}{sub 2}) that governs the rate-limiting step in 1-decene adsorption on HF-treated Si(100) is (3.3 {+-} 0.7) x 10{sup -2} min{sup -1}. The thickness and cant angle of the decane monolayer at the saturation coverage are calculated from angle resolved X-ray photoelectron spectroscopy (AR-XPS). The calculated thickness ranges from 8.4 to 18 {angstrom} due to the uncertainty in the attenuation lengths of C(1s) and Si(2p) photoelectrons through the decane layer. For the same uncertainty, the calculated cant angle ranges from 0 to 55{sup o}. Spectroscopic ellipsometry is independently used to approximate the film thickness at 16 {angstrom}. Monitoring the decane monolayer over a period of 50 days using AR-XPS indicates that the Si surface underneath the decane monolayer gets oxidized with time, leading to the degradation of the decane layer.

  16. Growth of III-Nitrides with Halide Vapor Phase Epitaxy (HVPE)

    NASA Astrophysics Data System (ADS)

    Hemmingsson, Carl; Monemar, Bo; Kumagai, Yoshinao; Koukitu, Akinori

    III-nitrides can be grown by employing several different techniques, such as molecular-beam epitaxy (MBE), metalorganic vapor-phase epitaxy (MOVPE), halide vapor-phase epitaxy (HVPE), high-pressure solution growth, and sputtering. Each of these are suited for a particular application; the specific property of HVPE is a much larger growth rate, which makes this technique the natural choice for growth of very thick layers that can be used as high-quality native substrates for subsequent growth of device structures using other techniques. Such substrates will be needed for certain devices with high current density or high voltage load, where the high defect density caused by growth on foreign substrates (heteroepitaxy) cannot be tolerated. The HVPE technology is still under development, and below we present the present situation with emphasis on GaN. The thermodynamic limitations of HVPE growth are discussed first, including the high-temperature chemistry in both the source zone and growth zone of a growth reactor. Examples of the design of growth systems are given; in particular, issues such as flow patterns, parasitic growth, and growth rates are discussed. Methods to reduce the defect density for growth on foreign substrates are discussed, as well as various lift-off techniques to prepare free-standing GaN wafers. Common characterization techniques are mentioned, and important physical properties of high-quality GaN wafers are given. The ongoing developments of HVPE growth for AlN and InN are also briefly summarized.

  17. Migration of carbon nanotubes from liquid phase to vapor phase in the refrigerant-based nanofluid pool boiling.

    PubMed

    Peng, Hao; Ding, Guoliang; Hu, Haitao

    2011-01-01

    The migration characteristics of carbon nanotubes from liquid phase to vapor phase in the refrigerant-based nanofluid pool boiling were investigated experimentally. Four types of carbon nanotubes with the outside diameters from 15 to 80 nm and the lengths from 1.5 to 10 ?m were used in the experiments. The refrigerants include R113, R141b and n-pentane. The oil concentration is from 0 to 10 wt.%, the heat flux is from 10 to 100 kW·m-2, and the initial liquid-level height is from 1.3 to 3.4 cm. The experimental results indicate that the migration ratio of carbon nanotube increases with the increase of the outside diameter or the length of carbon nanotube. For the fixed type of carbon nanotube, the migration ratio decreases with the increase of the oil concentration or the heat flux, and increases with the increase of the initial liquid-level height. The migration ratio of carbon nanotube increases with the decrease of dynamic viscosity of refrigerant or the increase of liquid phase density of refrigerant. A model for predicting the migration ratio of carbon nanotubes in the refrigerant-based nanofluid pool boiling is proposed, and the predictions agree with 92% of the experimental data within a deviation of ±20%. PMID:21711730

  18. Migration of carbon nanotubes from liquid phase to vapor phase in the refrigerant-based nanofluid pool boiling

    PubMed Central

    2011-01-01

    The migration characteristics of carbon nanotubes from liquid phase to vapor phase in the refrigerant-based nanofluid pool boiling were investigated experimentally. Four types of carbon nanotubes with the outside diameters from 15 to 80 nm and the lengths from 1.5 to 10 ?m were used in the experiments. The refrigerants include R113, R141b and n-pentane. The oil concentration is from 0 to 10 wt.%, the heat flux is from 10 to 100 kW·m-2, and the initial liquid-level height is from 1.3 to 3.4 cm. The experimental results indicate that the migration ratio of carbon nanotube increases with the increase of the outside diameter or the length of carbon nanotube. For the fixed type of carbon nanotube, the migration ratio decreases with the increase of the oil concentration or the heat flux, and increases with the increase of the initial liquid-level height. The migration ratio of carbon nanotube increases with the decrease of dynamic viscosity of refrigerant or the increase of liquid phase density of refrigerant. A model for predicting the migration ratio of carbon nanotubes in the refrigerant-based nanofluid pool boiling is proposed, and the predictions agree with 92% of the experimental data within a deviation of ±20%. PMID:21711730

  19. Cigarette smoke and muscle catabolism in C2 myotubes.

    PubMed

    Rom, Oren; Kaisari, Sharon; Aizenbud, Dror; Reznick, Abraham Z

    2013-01-01

    Previous studies have revealed evidence of muscular damage and up-regulation of genes associated with impaired muscle maintenance in smokers. Cigarette smoking has also been associated with sarcopenia, the age-related loss of muscle mass and strength. In order to investigate the cellular mechanisms by which cigarette smoke (CS) promotes muscle catabolism, C2 myotubes from an in vitro skeletal muscle cell line, were exposed to different levels of whole vapor phase CS using a controlled CS exposure apparatus. Exposure of C2 myotubes to CS caused a reduction in diameter of myotubes and a time- and dose-dependent degradation of myosin heavy chain. Also, CS exposure resulted in increased intracellular oxidative stress and p38 MAPK phosphorylation, which led to up-regulation of the muscle specific E3 ubiquitin ligases: MAFbx/atrogin-1 and MuRF1. Pretreatment with the antioxidant N-acetylcysteine and inhibition of p38 MAPK by SB203580 prevented CS induced catabolism. In conclusion, our results demonstrate that exposure of skeletal myotubes to CS leads to increased oxidative stress and activation of the p38 MAPK pathway resulting in muscle cell atrophy and breakdown of muscle protein mediated by muscle specific E3 ubiquitin ligases. Our findings provide a possible molecular mechanism for the catabolic effects of CS in skeletal muscle. PMID:23262287

  20. Fast vapor phase growth of SiO2 nanowires via surface-flow on Ag core/SiO2 shell structure

    E-print Network

    Zexian, Cao

    Fast vapor phase growth of SiO2 nanowires via surface-flow on Ag core/SiO2 shell structure Lei Gao://aipadvances.aip.org/most_downloaded Information for Authors: http://aipadvances.aip.org/authors #12;AIP ADVANCES 2, 012187 (2012) Fast vapor phase scenario by cooling enables revelation of the vapor-liquid-solid mechanism here in action, which

  1. Experimental studies of the vapor phase nucleation of refractory compounds. VI. The condensation of sodium

    Microsoft Academic Search

    Daniel M. Martínez; Frank T. Ferguson; Richard H. Heist; Joseph A. Nuth

    2005-01-01

    In this paper we discuss the condensation of sodium vapor and the formation of a sodium aerosol as it occurs in a gas evaporation condensation chamber. A one-dimensional model describing the vapor transport to the vapor\\/aerosol interface was employed to determine the onset supersaturation, in which we assume the observed location of the interface is coincident with a nucleation rate

  2. Cigarettes Health Risks

    E-print Network

    Oregon, University of

    lung disease. New studies have shown that about half of all regular cigarette smokers dieCigarettes Health Risks Smoking is the single greatest avoidable cause of disease and death percent of these deaths are from cancer, 35 percent from heart disease and stroke, and 25 percent from

  3. Antimicrobial effects of vapor phase thymol, modified atmosphere and their combination against Salmonella spp. on raw shrimp

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Salmonella contamination of raw shrimp is a food safety concern in the U.S. and other countries. This research evaluated the effects of vapor phase thymol, modified atmosphere (MA) and their combination against Salmonella spp. on raw shrimp. Growth profiles of a Salmonella spp. cocktail (6 strains),...

  4. Tribology Letters Vol. 10, No. 3, 2001 179 Activation of the SiC surface for vapor phase lubrication

    E-print Network

    Gellman, Andrew J.

    Tribology Letters Vol. 10, No. 3, 2001 179 Activation of the SiC surface for vapor phase been the focus of a number of re- cent tribological studies [1­10]. The high physical strength, low on surfaces of inert materials such as SiC, Si3N4 and quartz [8,9]. Tribological tests showed that the flaky

  5. The effect of carrier gas pressure on vapor phase nucleation experiments using a thermal diffusion cloud chamber

    Microsoft Academic Search

    D. Kane; S. P. Fisenko; M. Rusyniak; M. S. El-Shall

    1999-01-01

    Recent measurements of critical supersaturations for the vapor phase homogeneous nucleation of several substances using a diffusion cloud chamber technique exhibit a dependence on the pressure of the carrier gas used in the experiments. A model of droplet growth and motion in a diffusion cloud chamber, combined with the density and temperature profiles of the chamber is presented to explain

  6. THE EFFECT OF WATER (VAPOR-PHASE) AND CARBON ON ELEMENTAL MERCURY REMOVAL IN A FLOW REACTOR

    EPA Science Inventory

    The paper gives results of studying the effect of vapor-phase moisture on elemental mercury (Hgo) removal by activated carbon (AC) in a flow reactor. tests involved injecting AC into both a dry and a 4% moisture nitrogen (N2) /Hgo gas stream. A bituminous-coal-based AC (Calgon WP...

  7. Vapor phase matrix extraction of high purity di-boron trioxide and trace analysis using electrothermal AAS

    Microsoft Academic Search

    K. Dash; S. Thangavel; S. M. Dhavile; S. V. Rao; S. C. Chaurasia; J. Arunachalam

    2005-01-01

    A method has been developed for the determination of Al, Cd, Cr, Cu, Fe, Mg, Mn, Ni, Sb, Sn and Zn at trace levels in high purity di-boron trioxide using ETAAS. The boron trioxide matrix was eliminated as trimethyl borate ester in a multiplex vapor phase matrix extraction (MVPME) device using a mixture of glycerol and methanol. In this MVPME

  8. Method for the generation of variable density metal vapors which bypasses the liquidus phase

    DOEpatents

    Kunnmann, Walter (Stony Brook, NY); Larese, John Z. (Rocky Point, NY)

    2001-01-01

    The present invention provides a method for producing a metal vapor that includes the steps of combining a metal and graphite in a vessel to form a mixture; heating the mixture to a first temperature in an argon gas atmosphere to form a metal carbide; maintaining the first temperature for a period of time; heating the metal carbide to a second temperature to form a metal vapor; withdrawing the metal vapor and the argon gas from the vessel; and separating the metal vapor from the argon gas. Metal vapors made using this method can be used to produce uniform powders of the metal oxide that have narrow size distribution and high purity.

  9. Antibacterial effects of allspice, garlic, and oregano essential oils in tomato films determined by overlay and vapor-phase methods.

    PubMed

    Du, W-X; Olsen, C W; Avena-Bustillos, R J; McHugh, T H; Levin, C E; Mandrell, R; Friedman, Mendel

    2009-09-01

    Physical properties as well as antimicrobial activities against Escherichia coli O157:H7, Salmonella enterica, and Listeria monocytogenes of allspice, garlic, and oregano essential oils (EOs) in tomato puree film-forming solutions (TPFFS) formulated into edible films at 0.5% to 3% (w/w) concentrations were investigated in this study. Antimicrobial activities were determined by 2 independent methods: overlay of the film on top of the bacteria and vapor-phase diffusion of the antimicrobial from the film to the bacteria. The results indicate that the antimicrobial activities against the 3 pathogens were in the following order: oregano oil > allspice oil > garlic oil. Listeria monocytogenes was less resistant to EO vapors, while E. coli O157:H7 was more resistant to EOs as determined by both overlay and vapor-phase diffusion tests. The presence of plant EO antimicrobials reduced the viscosity of TPFFS at the higher shear rates, but did not affect water vapor permeability of films. EOs increased elongation and darkened the color of films. The results of the present study show that the 3 plant-derived EOs can be used to prepare tomato-based antimicrobial edible films with good physical properties for food applications by both direct contact and indirectly by vapors emanating from the films. PMID:19895486

  10. Traveling Waves, Riemann Problems and Computations of a Model of the Dynamics of Liquid\\/Vapor Phase Transitions

    Microsoft Academic Search

    Haitao Fan

    1998-01-01

    A model for the liquid\\/vapor phase transitions in a shock tube is discussed. Computations for the one-dimensional isothermal case is carried out to show that this model exhibits one-dimensional wave patterns observed in actual experiments. The existence of traveling waves under two different scalings are studied. For the first scaling, where the diffusion of different phases is very small relative

  11. EFFECT OF ACETIC ACID ON CO2 CORROSION OF CARBON STEEL IN VAPOR-WATER TWO-PHASE HORIZONTAL FLOW

    Microsoft Academic Search

    P. C. Okafor; S. Nesic

    2007-01-01

    The effect of acetic acid on the corrosion behavior of X 65 and C 1018 carbon steel in vapor-water two-phase stratified flow (Vsg: 2 m\\/s; Vsl: 0.1 m\\/s) at 2 bars total pressure, 1.54 bars CO2 partial pressure, pH 5.5, and 80°C was studied in a low pressure-high temperature multiphase flow horizontal loop using electrochemical and mass loss techniques. The liquid phase

  12. Defect Analysis in III-V Semiconductor Thin Films Grown by Hydride Vapor Phase Epitaxy

    NASA Astrophysics Data System (ADS)

    Schulte, Kevin Louis

    Hydride vapor phase epitaxy (HVPE) is an epitaxial growth technique renowned for its ability to grow III-V semiconductors at high growth rates using lower cost reagents compared to metal-organic vapor phase epitaxy (MOVPE), the current industry standard. Recent interest in III-V photovoltaics has led to increased attention on HVPE. While the technique came to maturity in the 70s, much is unknown about how defects incorporate in HVPE-grown materials. Further understanding of how defects incorporate in III-V materials grown by HVPE is necessary to facilitate wider adoption of the technique. This information would inform strategies for minimizing and eliminating defects in HVPE materials, allowing for the formation of high performance devices. This investigation presents a study of multiple defects in III-V semiconductors grown by HVPE in the context of specific device applications, spanning point defects comprised of individual atoms to extended defects which propagate throughout the crystal. The incorporation of the arsenic anti-site defect, AsGa, intrinsic point defect was studied in high growth rate GaAs layers with potential photovoltaic applications. Relationships between growth conditions and incorporation of AsGa in GaAs epilayers were determined. The incorporation of AsGa depended strongly on the growth conditions employed, and a model was developed to predict the concentration of anti-site defects as a function of those growth conditions. Dislocations and anti-phase domain boundaries (APDBs), two types of extended defects, were investigated in the heteroepitaxial GaAs/Ge system. It was found that the use of 6° miscut substrates and specific growth temperatures led to elimination of APDBs. Dislocation densities were reduced through the use of high growth temperatures. The third and final application investigated was the growth of InxGa1-xAs metamorphic buffer layers (MBLs) by HVPE. The relationships between the growth conditions and the alloy composition were determined, and a model was developed to explain the observed behavior. Compositional grading strategies were explored and insight into the minimization of dislocations in these layers was developed. The dislocation microstructure was analyzed by TEM and related to the layer design, leading to the development of an atomic scale model for dislocation nucleation and propagation throughout the MBL layers.

  13. Chemical Species in the Vapor Phase of Hanford Double-Shell Tanks: Potential Impacts on Waste Tank Corrosion Processes

    SciTech Connect

    Felmy, Andrew R.; Qafoku, Odeta; Arey, Bruce W.; Boomer, Kayle D.

    2010-09-22

    The presence of corrosive and inhibiting chemicals on the tank walls in the vapor space, arising from the waste supernatant, dictate the type and degree of corrosion that occurs there. An understanding of how waste chemicals are transported to the walls and the affect on vapor species from changing supernatant chemistry (e.g., pH, etc.), are basic to the evaluation of risks and impacts of waste changes on vapor space corrosion (VSC). In order to address these issues the expert panel workshop on double-shell tank (DST) vapor space corrosion testing (RPP-RPT-31129) participants made several recommendations on the future data and modeling needs in the area of DST corrosion. In particular, the drying of vapor phase condensates or supernatants can form salt or other deposits at the carbon steel interface resulting in a chemical composition at the near surface substantially different from that observed directly in the condensates or the supernatants. As a result, over the past three years chemical modeling and experimental studies have been performed on DST supernatants and condensates to predict the changes in chemical composition that might occur as condensates or supernatants equilibrate with the vapor space species and dry at the carbon steel surface. The experimental studies included research on both the chemical changes that occurred as the supernatants dried as well as research on how these chemical changes impact the corrosion of tank steels. The chemical modeling and associated experimental studies were performed at the Pacific Northwest National Laboratory (PNNL) and the research on tank steel corrosion at the Savannah River National Laboratory (SRNL). This report presents a summary of the research conducted at PNNL with special emphasis on the most recent studies conducted in FY10. An overall summary of the project results as well as their broader implications for vapor space corrosion of the DST’s is given at the end of this report.

  14. Smoking stimuli from the terminal phase of cigarette consumption may not be cues for smoking in healthy smokers

    Microsoft Academic Search

    Ronald F. Mucha; Paul Pauli; Markus Weber; Markus Winkler

    2008-01-01

    Background  Stimuli from the terminal phase of smoke or drug intake are paired with drug effect but have surprisingly low cue reactivity.\\u000a Smoking terminal stimuli were compared to cues under conditions of different perceived smoke intake to probe whether (1) terminal\\u000a stimuli are only weak cues, (2) any effect is an artifact of rigid test conditions, and (3) terminal stimuli have

  15. Investigation by microarray analysis of effects of cigarette design characteristics on gene expression in human lung mucoepidermoid cancer cells NCI-H292 exposed to cigarette smoke.

    PubMed

    Sekine, Takashi; Sakaguchi, Chikako; Fukano, Yasuo

    2015-02-01

    The effects of tobacco leaf types and the presence or absence of charcoal in the cigarette filters on gene expression were investigated using cigarette prototypes made of either flue-cured (FC) leaf or burley (BLY) leaf and Kentucky Reference 2R4F as a representative blend cigarette with cellulose acetate filters or charcoal filters. NCI-H292, human lung mucoepidermoid carcinoma cell line, was exposed to the total particulate matter (TPM) and gas/vapor phase (GVP) from each prototype for 8h and then the changes in gene expression from microarray data were analyzed. A number of genes associated with oxidative stress, inflammation, DNA damage and xenobiotic response were modified by the two fractions, TPM and GVP, from the three prototypes with cellulose acetate filters. Both TPM and GVP fractions strongly enhanced the gene expression of HMOX1, which is encoding the limiting enzyme in heme degradation and a key regulator of oxidative stress and inflammatory process. Comparing the effects of TPM and GVP fraction, TPM strongly activated Nrf2 pathway-mediated anti-oxidative stress reaction, whereas GVP caused notable DNA damage response. In comparison of FC and BLY, TPM from FC more strongly induced the expression of histone family proteins than that from BLY. GVP from FC markedly induced gene expression associated with HSP70-mediated inflammation relative to that from BLY. Charcoal included in the filter strongly reduced the effects of GVP from each cigarette on gene expression. However, charcoal did not modified the effects of TPM. As a whole, charcoal is a useful material for reducing the biological effects of GVP. PMID:25497788

  16. Mid-infrared laser-absorption diagnostic for vapor-phase measurements in an evaporating n-decane aerosol

    NASA Astrophysics Data System (ADS)

    Porter, J. M.; Jeffries, J. B.; Hanson, R. K.

    2009-09-01

    A novel three-wavelength mid-infrared laser-based absorption/extinction diagnostic has been developed for simultaneous measurement of temperature and vapor-phase mole fraction in an evaporating hydrocarbon fuel aerosol (vapor and liquid droplets). The measurement technique was demonstrated for an n-decane aerosol with D 50˜3 ? m in steady and shock-heated flows with a measurement bandwidth of 125 kHz. Laser wavelengths were selected from FTIR measurements of the C-H stretching band of vapor and liquid n-decane near 3.4 ?m (3000 cm -1), and from modeled light scattering from droplets. Measurements were made for vapor mole fractions below 2.3 percent with errors less than 10 percent, and simultaneous temperature measurements over the range 300 K< T<900 K were made with errors less than 3 percent. The measurement technique is designed to provide accurate values of temperature and vapor mole fraction in evaporating polydispersed aerosols with small mean diameters ( D 50<10 ? m), where near-infrared laser-based scattering corrections are prone to error.

  17. Effects of mainstream cigarette smoke on the global metabolome of human lung epithelial cells.

    PubMed

    Vulimiri, Suryanarayana V; Misra, Manoj; Hamm, Jonathan T; Mitchell, Matthew; Berger, Alvin

    2009-03-16

    Metabolomics is a technology for identifying and quantifying numerous biochemicals across metabolic pathways. Using this approach, we explored changes in biochemical profiles of human alveolar epithelial carcinoma (A549) cells following in vitro exposure to mainstream whole smoke (WS) aerosol as well as to wet total particulate matter (WTPM) or gas/vapor phase (GVP), the two constituent phases of WS from 2R4F Kentucky reference cigarettes. A549 cells were exposed to WTPM or GVP (expressed as WTPM mass equivalent GVP volumes) at 0, 5, 25, or 50 microg/mL or to WS from zero, two, four, and six cigarettes for 1 or 24 h. Cell pellets were analyzed for perturbations in biochemical profiles, with named biochemicals measured, analyzed, and reported in a heat map format, along with biochemical and physiological interpretations (mSelect, Metabolon Inc.). Both WTPM and GVP exposures likely decreased glycolysis (based on decreased glycolytic intermediaries) and increased oxidative stress and cell damage. Alterations in the Krebs cycle and the urea cycle were unique to WTPM exposure, while induction of hexosamines and alterations in lipid metabolism were unique to GVP exposure. WS altered glutathione (GSH) levels, enhanced polyamine and pantothenate levels, likely increased beta-oxidation of fatty acids, and increased phospholipid degradation marked by an increase in phosphoethanolamine. GSH, glutamine, and pantothenate showed the most significant changes with cigarette smoke exposure in A549 cells based on principal component analysis. Many of the changed biochemicals were previously reported to be altered by cigarette exposure, but the global metabolomic approach offers the advantage of observing changes to hundreds of biochemicals in a single experiment and the possibility for new discoveries. The metabolomic approach may thus be used as a screening tool to evaluate conventional and novel tobacco products offering the potential to reduce risks of smoking. PMID:19161311

  18. Towards large area and continuous MoS2 atomic layers via vapor-phase growth: thermal vapor sulfurization.

    PubMed

    Liu, Hongfei; Ansah Antwi, K K; Ying, Jifeng; Chua, Soojin; Chi, Dongzhi

    2014-10-10

    We report on the effects of substrate, starting material, and temperature on the growth of MoS(2) atomic layers by thermal vapor sulfurization in a tube-furnace system. With Mo as the starting material, atomic layers of MoS(2) flakes are obtained on sapphire substrates while a bell-shaped MoS(2) layer, sandwiched by amorphous SiO(2), is obtained on native-SiO(2)/Si substrates under the same sulfurization conditions. An anomalous thickness-dependent Raman shift (A(1g)) of the MoS(2) atomic layers is observed in Mo-sulfurizations on sapphire substrates, which can be attributed to the competition between the effects of thickness and the surface/interface. Both effects vary with the sulfurizing temperatures for a certain initial Mo thickness. The anomalous frequency trend of A(1g) is missing when using MoO(3) instead of Mo as the starting material. In this case, the lateral growth of MoS(2) on sapphire is also largely improved. Furthermore, the area density of the resultant MoS(2) atomic layers is significantly increased by increasing the deposition temperature of the starting MoO(3) to 700 °C; the adjacent ultrathin MoS(2) grains coalesce in one or other direction, forming connected chains in wafer scale. The thickness of the so-obtained MoS(2) is generally controlled by the thickness of the starting material; however, the structural and morphological properties of MoS(2) grains, towards large area and continuous atomic layers, are strongly dependent on the temperature of the initial material deposition, and on the temperature of sulfurization, because of the competition between surface mobility and atom evaporation. PMID:25213380

  19. Science and Electronic Cigarettes: Current Data, Future Needs

    PubMed Central

    Breland, Alison; Spindle, Tory; Weaver, Michael; Eissenberg, Thomas

    2014-01-01

    Electronic cigarettes (ECIGs), also referred to as electronic nicotine delivery systems (ENDS) or ‘e-cigarettes’, generally consist of a power source (usually a battery) and heating element (commonly referred to as an atomizer) that vaporizes a solution (e-liquid). The user inhales the resulting vapor. ECIGs have been increasing in popularity since they were introduced into the US market in 2007. Many questions remain about these products, and limited research has been conducted. This review will describe the available research on what ECIGs are, effects of use, survey data on awareness and use, and the utility of ECIGs to help smokers quit using tobacco cigarettes. This review will also describe arguments for and against ECIGs, and concludes with steps to move research on ECIGs forward. PMID:25089952

  20. Cigarette smoking and schizophrenia 

    E-print Network

    Patrick, Jon Alan

    2007-06-28

    Section 1 Introduction Cigarette smoking is anecdotally seen more often amongst schizophrenic than well subjects. Research has suggested a variety of explanations which are discussed; the role of genetics, psychosocial ...

  1. Vapor phase reactions in polymerization plasma for divinylsiloxane-bis-benzocyclobutene film deposition

    SciTech Connect

    Kinoshita, Keizo; Nakano, Akinori; Kawahara, Jun; Kunimi, Nobutaka; Hayashi, Yoshihiro; Kiso, Osamu; Saito, Naoaki; Nakamura, Keiji; Kikkawa, Takamaro [MIRAI, Association of Super-Advanced Electronics Technologies (ASET), AIST-Tsukuba-West, Tsukuba, Ibaraki 305-8569 (Japan); MIRAI, Advanced Semiconductor Research Center (ASRC), National Institute of Advanced Industrial Science and Technology (AIST), AIST-Tsukuba-West, Tsukuba, Ibaraki 305-8569 (Japan); Energy Electronics Institute, AIST, AIST-Tsukuba-Central, Tsukuba, Ibaraki 305-8568 (Japan); Department of Electrical Engineering, Chubu University, 1200 Matsumoto, Kasugai, Aichi 487-8501 (Japan); Research Center for Nanodevices and Systems, Hiroshima University, Higashi-Hiroshima, Hiroshima 739-8527 (Japan)

    2006-11-15

    Vapor phase reactions in plasma polymerization of divinylsiloxane-bis-benzocyclobutene (DVS-BCB) low-k film depositions on 300 mm wafers were studied using mass spectrometry, in situ Fourier transform infrared, and a surface wave probe. Polymerization via Diels-Alder cycloaddition reaction was identified by the detection of the benzocyclohexene group. Hydrogen addition and methyl group desorption were also detected in DVS-BCB monomer and related large molecules. The dielectric constant k of plasma polymerized DVS-BCB with a plasma source power range up to 250 W was close to {approx}2.7 of thermally polymerized DVS-BCB, and increased gradually over 250 W. The electron density at 250 W was about 1.5x10{sup 10} cm{sup -3}. The increase of the k value at higher power was explained by the decrease of both large molecular species via multistep dissociation and incorporation of silica components into the polymer. It was found that the reduction of electron density as well as precursor residence time is important for the plasma polymerization process to prevent the excess dissociation of the precursor.

  2. Nucleus and spiral growth mechanisms of nitride semiconductors in metalorganic vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Akasaka, Tetsuya; Yamamoto, Hideki

    2014-10-01

    Nucleus and spiral growth mechanisms of GaN and InN are investigated using the selective-area metalorganic vapor phase epitaxy (SA-MOVPE) technique on GaN bulk substrates. Nucleus growth of GaN occurs within selective areas having no screw-type dislocations, while spiral growth occurs within selective areas having screw-type dislocations. These growth modes are simultaneously observed on a single substrate in a single growth run. The nucleus and spiral growths of GaN result in the formation of step-free surfaces and growth spirals, respectively, wherein the interstep distance of growth spirals enables us to estimate the degree of surface supersaturation (?). The ? dependences of nucleus and spiral growth rates of GaN are experimentally investigated. We found that these dependences are well explained by the classical crystal growth theories advocated by Burton, Cabrera, and Frank. We also investigate nucleation of InN using step-free GaN surfaces as an ideal platform.

  3. Synthesis and in-situ characterization of superparamagnetic nanocomposites from vapor phase condensation

    SciTech Connect

    Zachariah, M.R.; McMillin, B.; Shull, R.D. [National Institute of Standards and Technology, Gaithersburg, MD (United States); Biswas, P. [Univ. of Cincinnati, OH (United States)

    1995-12-31

    Recent work on the magnetic characteristics of manometer scale materials has suggested that magnetically isolated manometer magnetic particles would show magnetic behavior different than those found in the bulk. We have investigated application of flame technology for the synthesis of this class of materials. A premixed methane/oxygen flame diluted with nitrogen has been used as the reacting environment in which iron carbonyl and hexamethyldisiloxane was added as the magnetic and non-magnetic precursor materials. The flame structure was adjusted to obtain an oxygen rich environment in which oxides of iron and silica would condense from the vapor. The results based on X-ray diffraction, electron microscopy, Mossbauer effect and magnetization have shown that: (1) Nanometer composite particles are formed containing 5-10 nm Fe{sub 2}O{sub 3}, encased in a silica particle whose diameter ranged from 30-100 nm depending on loading and flame temperature. (2) The iron oxide clusters are magnetically isolated and in some cases show superparamagnetic behavior. In this paper the effect of iron/silica ratio will be discussed along with particle morphology and size sensitivity to flame parameters. In-situ characterization using planar laser induced fluorescence and planar laser light scattering have been used, inconjunction with an image intensified CCD camera to map the temperature, particle field, and FeO and SiO gas phase concentrations.

  4. Environmentally Compatible Vapor-Phase Corrosion Inhibitor for Space Shuttle Hardware

    NASA Technical Reports Server (NTRS)

    Novak, Howard L.; Hall, Phillip B.; McCool, Alex (Technical Monitor)

    2001-01-01

    USA-SRB Element is responsible for the assembly and refurbishment of the non-motor components of the SRB as part of Space Shuttle. Thrust Vector Control (TVC) frames structurally support components of the TVC system located in the aft skirt of the SRB. TVC frames are exposed to the seacoast environment after refurbishment and, also, to seawater immersion after splashdown, and during tow-back to CCAFS-Hangar AF refurbishment facilities. During refurbishment operations it was found that numerous TVC frames were experiencing internal corrosion and coating failures, both from salt air and seawater intrusions. Inspectors using borescopes would visually examine the internal cavities of the complicated aluminum alloy welded tubular structure. It was very difficult for inspectors to examine cavity corners and tubing intersections and particularly, to determine the extent of the corrosion and coating anomalies. Physical access to TVC frame internal cavities for corrosion removal and coating repair was virtually impossible, and an improved method using a Liquid (water based) Vapor-phase Corrosion Inhibitor (LVCI) for preventing initiation of new corrosion, and mitigating and/or stopping existing corrosion growth was recommended in lieu of hazardous paint solvents and high VOC/solvent based corrosion inhibitors. In addition, the borescopic inspection method used to detect corrosion, and/or coating anomalies had severe limitations because of part geometry, and an improved non-destructive inspection (NDI) method using Neutron Radiography (N-Ray) was also recommended.

  5. Vapor Phase Synthesis of Organometal Halide Perovskite Nanowires for Tunable Room-Temperature Nanolasers.

    PubMed

    Xing, Jun; Liu, Xin Feng; Zhang, Qing; Ha, Son Tung; Yuan, Yan Wen; Shen, Chao; Sum, Tze Chien; Xiong, Qihua

    2015-07-01

    Semiconductor nanowires have received considerable attention in the past decade driven by both unprecedented physics derived from the quantum size effect and strong isotropy and advanced applications as potential building blocks for nanoscale electronics and optoelectronic devices. Recently, organic-inorganic hybrid perovskites have been shown to exhibit high optical absorption coefficient, optimal direct band gap, and long electron/hole diffusion lengths, leading to high-performance photovoltaic devices. Herein, we present the vapor phase synthesis free-standing CH3NH3PbI3, CH3NH3PbBr3, and CH3NH3PbIxCl3-x perovskite nanowires with high crystallinity. These rectangular cross-sectional perovskite nanowires have good optical properties and long electron hole diffusion length, which ensure adequate gain and efficient optical feedback. Indeed, we have demonstrated optical-pumped room-temperature CH3NH3PbI3 nanowire lasers with near-infrared wavelength of 777 nm, low threshold of 11 ?J/cm(2), and a quality factor as high as 405. Our research advocates the promise of optoelectronic devices based on organic-inorganic perovskite nanowires. PMID:26043362

  6. Carbon-Supported bimetallic Pd-Fe catalysts for vapor-phase hydrodeoxygenation of guaiacol

    SciTech Connect

    Sun, Junming; Karim, Ayman M.; Zhang, He; Kovarik, Libor; Li, Xiaohong S.; Hensley, Alyssa; McEwen, Jean-Sabin; Wang, Yong

    2013-10-01

    Abstract Carbon supported metal catalysts (Cu/C, Fe/C, Pd/C, Pt/C, PdFe/C and Ru/C) have been prepared, characterized and tested for vapor-phase hydrodeoxygenation (HDO) of guaiacol (GUA) at atmospheric pressure. Phenol was the major intermediate on all catalysts. Over the noble metal catalysts saturation of the aromatic ring was the major pathway observed at low temperature (250 °C), forming predominantly cyclohexanone and cyclohexanol. Substantial ring opening reaction was observed on Pt/C and Ru/C at higher reaction temperatures (e.g., 350 °C). Base metal catalysts, especially Fe/C, were found to exhibit high HDO activity without ring-saturation or ring-opening with the main products being benzene, phenol along with small amounts of cresol, toluene and trimethylbenzene (TMB). A substantial enhancement in HDO activity was observed on the PdFe/C catalysts. Compared with Fe/C, the yield to oxygen-free aromatic products (i.e., benzene/toluene/TMB) on PdFe/C increased by a factor of four at 350 °C, and by approximately a factor of two (83.2% versus 43.3%) at 450 °C. The enhanced activity of PdFe/C is attributed to the formation of PdFe alloy as evidenced by STEM, EDS and TPR.

  7. Radiation-induced defects in GaN bulk grown by halide vapor phase epitaxy

    SciTech Connect

    Duc, Tran Thien; Pozina, Galia; Son, Nguyen Tien; Janzén, Erik; Hemmingsson, Carl [Department of Physics, Chemistry and Biology (IFM), Linköping University, S-581 83 Linköping (Sweden); Ohshima, Takeshi [Japan Atomic Energy Agency (JAEA), Takasaki, Gunma 370-1292 (Japan)

    2014-09-08

    Defects induced by electron irradiation in thick free-standing GaN layers grown by halide vapor phase epitaxy were studied by deep level transient spectroscopy. In as-grown materials, six electron traps, labeled D2 (E{sub C}–0.24?eV), D3 (E{sub C}–0.60?eV), D4 (E{sub C}–0.69?eV), D5 (E{sub C}–0.96?eV), D7 (E{sub C}–1.19?eV), and D8, were observed. After 2?MeV electron irradiation at a fluence of 1?×?10{sup 14?}cm{sup ?2}, three deep electron traps, labeled D1 (E{sub C}–0.12?eV), D5I (E{sub C}–0.89?eV), and D6 (E{sub C}–1.14?eV), were detected. The trap D1 has previously been reported and considered as being related to the nitrogen vacancy. From the annealing behavior and a high introduction rate, the D5I and D6 centers are suggested to be related to primary intrinsic defects.

  8. Investigation of deep levels in bulk GaN material grown by halide vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Duc, Tran Thien; Pozina, Galia; Janzén, Erik; Hemmingsson, Carl

    2013-10-01

    Electron traps in thick free standing GaN grown by halide vapor phase epitaxy were characterized by deep level transient spectroscopy. The measurements revealed six electron traps with activation energy of 0.252 (E1), 0.53 (E2), 0.65 (E4), 0.69 (E3), 1.40 (E5), and 1.55 eV (E6), respectively. Among the observed levels, trap E6 has not been previously reported. The filling pulse method was employed to determine the temperature dependence of the capture cross section and to distinguish between point defects and extended defects. From these measurements, we have determined the capture cross section for level E1, E2, and E4 to 3.2 × 10-16 cm2, 2.2 × 10-17 cm2, and 1.9 × 10-17 cm2, respectively. All of the measured capture cross sections were temperature independent in the measured temperature range. From the electron capturing kinetic, we conclude that trap E1, E2, and E3 are associated with point defects. From the defect concentration profile obtained by double correlated deep level transient spectroscopy, we suggest that trap E4 and E6 are introduced by the polishing process.

  9. High quality long-wavelength lasers grown by atmospheric organometallic vapor phase epitaxy using tertiarybutylarsine

    SciTech Connect

    Miller, B.I.; Young, M.G.; Oron, M.; Koren, U.; Kisker, D. (AT T Bell Telephone Laboratories, Crawfords Corner Road, Holmdel, New Jersey 07733 (USA))

    1990-04-09

    High quality long-wavelength InGaAsP/InP lasers were grown by atmospheric organometallic vapor phase epitaxy using tertiarybutylarsine (TBA) as a substitute for AsH{sub 3}. Electrical and photoluminescence measurements on InGaAs and InGaAsP showed that TBA-grown material was at least as good as AsH{sub 3} material in terms of suitability for lasers. From two wafers grown by TBA, current thresholds {ital I}{sub th} as low as 11 mA were obtained for a 2-{mu}m-wide semi-insulating blocking planar buried heterostructure laser lasing near 1.3 {mu}m wavelength. The differential quantum efficiencies {eta}{sub {ital D}} were as high as 21%/facet with a low internal loss {alpha}=21 cm{sup {minus}1}. In addition {ital I}{sub th} as low as 18 mA and {eta}{sub {ital D}} as high as 18% have been obtained for multiplequantum well lasers at 1.54 {mu}m wavelength. These results show that TBA might be used to replace AsH{sub 3} without compromising on laser performance.

  10. Pentacene/K12 solar cells formed by organic vapor phase deposition

    NASA Astrophysics Data System (ADS)

    Axmann, Sebastian; Brast, Michael; Pandey, Ajay Kumar; Burn, Paul; Meredith, Paul; Heuken, Michael; Vescan, Andrei; Kalisch, Holger

    2014-01-01

    This study reports on an organic solar cell structure utilizing K12 as a new low-temperature processable small-molecule acceptor material. Pentacene (PEN) and K12 were deposited onto indium tin oxide by means of organic vapor phase deposition (OVPD) as bilayer solar cells. The resulting solar cell was characterized electrically by current density-voltage (J-V) measurements and optically by photocurrent and reflectivity measurements. The J-V characteristic under AM 1.5 illumination indicates a short-circuit current of 0.45 mA/cm2 (Jsc), a fill factor of 38% (FF), and an open-circuit (Voc) voltage of 0.71 V. Current generation is found to predominantly occur in the K12 layer, although strong light absorption in the PEN layer is detected. We suggest that either a dipole shift between the layers or the fission of singlet excitons in the PEN layer leads to this observation. Although the efficiency of the device is low in combination with PEN, our experiment successfully demonstrates the use of K12 as a low-temperature acceptor material in OVPD processes.

  11. High quality single and double two-dimensional electron gases grown by metalorganic vapor phase epitaxy

    SciTech Connect

    Chui, H.C.; Hammons, B.E.; Simmons, J.A.; Harff, N.E.; Sherwin, M.E. [Sandia National Laboratories, Albuquerque, New Mexico 87185-0603 (United States)] [Sandia National Laboratories, Albuquerque, New Mexico 87185-0603 (United States)

    1995-09-25

    We demonstrate the metalorganic vapor phase epitaxy (MOVPE) growth of AlGaAs/GaAs two-dimensional electron gases (2DEGs) with mobilities as high as 786 000 cm{sup 2}/V s at a carrier density of 3.0{times}10{sup 11} cm{sup {minus}2} at 0.3 K. The mobility figures of merit ({mu}/{ital n}{sup 3/2}) for these 2DEGs are the highest reported to date for MOVPE materials. These 2DEGs also exhibit the fractional quantum Hall effect (FQHE) with minima in longitudinal resistance corresponding to Landau level filling factors 2/3, 4/3, and 5/3. The temperature dependence and carrier density dependence of mobility were characterized, and the mobility was found to vary linearly with carrier density, implying that the mobility is probably limited by background ionized impurity scattering. A delta-doped 2DEG was also compared with uniformly doped 2DEGs and was found to have a slightly higher mobility. Finally, we obtained high mobility in a coupled double 2DEG structure for 2D to 2D tunneling applications. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  12. High quality single and double two-dimensional electron gases grown by metalorganic vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Chui, H. C.; Hammons, B. E.; Simmons, J. A.; Harff, N. E.; Sherwin, M. E.

    1995-09-01

    We demonstrate the metalorganic vapor phase epitaxy (MOVPE) growth of AlGaAs/GaAs two-dimensional electron gases (2DEGs) with mobilities as high as 786 000 cm2/V s at a carrier density of 3.0×1011 cm-2 at 0.3 K. The mobility figures of merit (?/n3/2) for these 2DEGs are the highest reported to date for MOVPE materials. These 2DEGs also exhibit the fractional quantum Hall effect (FQHE) with minima in longitudinal resistance corresponding to Landau level filling factors 2/3, 4/3, and 5/3. The temperature dependence and carrier density dependence of mobility were characterized, and the mobility was found to vary linearly with carrier density, implying that the mobility is probably limited by background ionized impurity scattering. A delta-doped 2DEG was also compared with uniformly doped 2DEGs and was found to have a slightly higher mobility. Finally, we obtained high mobility in a coupled double 2DEG structure for 2D to 2D tunneling applications.

  13. Vapor phase polymerization deposition of conducting polymer/graphene nanocomposites as high performance electrode materials.

    PubMed

    Yang, Yajie; Li, Shibin; Zhang, Luning; Xu, Jianhua; Yang, Wenyao; Jiang, Yadong

    2013-05-22

    In this paper, we report chemical vapor phase polymerization (VPP) deposition of novel poly(3,4-ethylenedioxythiophene) (PEDOT)/graphene nanocomposites as solid tantalum electrolyte capacitor cathode films. The PEDOT/graphene films were successfully prepared on porous tantalum pentoxide surface as cathode films through the VPP procedure. The results indicated that the high conductivity nature of PEDOT/graphene leads to the decrease of cathode films resistance and contact resistance between PEDOT/graphene and carbon paste. This nanocomposite cathode film based capacitor showed ultralow equivalent series resistance (ESR) ca. 12 m? and exhibited better capacitance-frequency performance than the PEDOT based capacitor. The leakage current investigation revealed that the device encapsulation process does not influence capacitor leakage current, indicating the excellent mechanical strength of PEDOT-graphene films. The graphene showed a distinct protection effect on the dielectric layer from possible mechanical damage. This high conductivity and mechanical strength graphene based conducting polymer nanocomposites indicated a promising application future for organic electrode materials. PMID:23621384

  14. Environmentally Compatible Vapor-Phase Corrosion Inhibitor for Space Shuttle Hardware

    NASA Technical Reports Server (NTRS)

    Novak, Howard L.; Hall, Phillip B.; Martin, David (Technical Monitor)

    2002-01-01

    USA-SRB Element is responsible for the assembly and refurbishment of the non-motor components of the SRB as part of Space Shuttle. Thrust Vector Control (TVC) frames structurally support components of the TVC system located in the aft skirt of the SRB (Solid Rocket Booster). TVC frames are exposed to the seacoast environment after refurbishment and, also, to seawater immersion after splashdown, and during tow-back to CCAFS-Hangar AF refurbishment facilities. During refurbishment operations it was found that numerous TVC frames were experiencing internal corrosion and coating failures, both from salt air and seawater intrusions. Inspectors using borescopes would visually examine the internal cavities of the complicated aluminum alloy welded tubular structure. It was very difficult for inspectors to examine cavity corners and tubing intersections and particularly. to determine the extent of the corrosion and coating anomalies. Physical access to TVC frame internal cavities for corrosion removal and coating repair was virtually impossible, and an improved method using a Liquid (water based) Vapor-phase Corrosion Inhibitor (LVCI) for preventing initiation of new corrosion, and mitigating and/or stopping existing corrosion growth was recommended in lieu of hazardous paint solvents and high VOC/solvent based corrosion inhibitors. In addition, the borescopic inspection method used to detect corrosion, and/or coating anomalies had severe limitations because of part geometry, and an improved non-destructive inspection (NDI) method using Neutron Radiography (N-Ray) was also recommended.

  15. Self-assembly of Arg-Phe nanostructures via the solid-vapor phase method.

    PubMed

    Liberato, Michelle S; Kogikoski, Sergio; Silva, Emerson R; Coutinho-Neto, Mauricio D; Scott, Luis P B; Silva, Ricardo H; Oliveira, Vani X; Ando, Rômulo A; Alves, Wendel A

    2013-01-24

    We report for the first time on the self-assembly of nanostructures composed exclusively of alternating positively charged and hydrophobic amino acids. A novel arginine/phenylalanine octapeptide, RF8, was synthesized. Because the low hydrophobicity of this sequence makes its spontaneous ordering through solution-based methods difficult, a recently proposed solid-vapor approach was used to obtain nanometric architectures on ITO/PET substrates. The formation of the nanostructures was investigated under different preparation conditions, specifically, under different gas-phase solvents (aniline, water, and dichloromethane), different peptide concentrations in the precursor solution, and different incubation times. The stability of the assemblies was experimentally studied by electron microscopy and thermogravimetric analysis coupled with mass spectrometry. The secondary structure was assessed by infrared and Raman spectroscopy, and the arrays were found to assume an antiparallel ?-sheet conformation. FEG-SEM images clearly reveal the appearance of fibrillar structures that form extensive homogeneously distributed networks. A close relationship between the morphology and preparation parameters was found, and a concentration-triggered mechanism was suggested. Molecular dynamics simulations were performed to address the thermal stability and nature of intermolecular interactions of the putative assembly structure. Results obtained when water is considered as solvent shows that a stable lamellar structure is formed containing a thin layer of water in between the RF8 peptides that is stabilized by H-bonding. PMID:23286315

  16. Reactor design and reaction engineering studies related to metalorganic vapor phase epitaxy of compound semiconductors

    NASA Astrophysics Data System (ADS)

    Gupta, Vijay

    Metalorganic Chemical Vapor Phase Epitaxy (MOVPE) has emerged as a versatile and cost-effective technique for growing single-crystalline films and multi-layer structures of compound semiconductors. During MOVPE a mixture of organometallic vapors and other reactant gases flows over a heated substrate resulting in the epitaxial growth of a thin single-crystalline film. Reaction-transport models can become a powerful tool in the analysis, scale up and optimization of MOVPE reactors. A novel counterflow jet reactor has been modeled and optimized for the study of purely homogeneous thermal decomposition reactions in a wall-less environment at near atmospheric pressures. Reaction-transport models and finite element simulations were performed to identify reactor shapes and operating conditions leading to well-defined and stable stagnation flow fields, which are free of buoyancy-driven recirculations. The growth of some compound semiconductors, such as ZnSe is plagued by the pre-reaction of the precursors in the gas phase leading to formation of particulates that hamper film quality. Finite element simulations have been used to optimize a split-inlet gas delivery system of a vertical MOVPE reactor to achieve complete mixing of the precursors just above the substrate and low contact times between the precursors in the gas phase to suppress parasitic pre-reactions. A detailed kinetic model of the MOVPE of Alsb{x}Gasb{(1-x)}As has been developed and coupled to a transport model describing flow, heat and mass transfer along the midplane of a horizontal MOVPE reactor. The kinetic model includes both gas-phase and surface reactions and was validated by comparing predicted growth rates, as well as thickness and compositional variations of the films, with reported experimental observations. The reaction-transport model was subsequently used for optimal design of horizontal MOVPE reactors by inclining the upper wall to counteract the effects of reactant depletion in the downstream direction and to suppress the formation of transverse flow recirculations. Finally, a three-dimensional flow and heat transfer model of a single wafer VPE reactor was developed. The simulations were used to design the reactor exit in order to prevent back-propagation of non-axisymmetric disturbances from the pumping channel and preserve the axial symmetry over the deposition area. A natural extension of this work is the use of three dimensional reaction-transport models to optimize MOVPE reactor shapes and operating conditions. A lumped kinetic model for particulate formation can be coupled to the reaction-transport models for the reactors to gain insight into the particulate formation problems. The ultimate objective is to create virtual MOVPE reactors and perform numerical experiments to optimize them before the actual prototypes are built. To achieve this goal the macroscopic models described in this thesis must be hierarchically coupled with mesoscopic and microscopic models of the growth process.

  17. E-cigarettes: methodological and ideological issues and research priorities.

    PubMed

    Etter, Jean-François

    2015-01-01

    Cigarette combustion, rather than either tobacco or nicotine, is the cause of a public health disaster. Fortunately, several new technologies that vaporize nicotine or tobacco, and may make cigarettes obsolete, have recently appeared. Research priorities include the effects of vaporizers on smoking cessation and initiation, their safety and toxicity, use by non-smokers, dual use of vaporizers and cigarettes, passive vaping, renormalization of smoking, and the development of messages that effectively communicate the continuum of risk for tobacco and nicotine products. A major difficulty is that we are chasing a moving target. New products constantly appear, and research results are often obsolete by the time they are published. Vaporizers do not need to be safe, only safer than cigarettes. However, harm reduction principles are often misunderstood or rejected. In the context of a fierce ideological debate, and major investments by the tobacco industry, it is crucial that independent researchers provide regulators and the public with evidence-based guidance. The methodological and ideological hurdles on this path are discussed in this commentary. PMID:25856794

  18. Selective transport of hydrocarbons in the unsaturated zone due to aqueous and vapor phase partitioning

    Microsoft Academic Search

    Arthur L. Baehr

    1987-01-01

    Long-term ground water contamination can result from vapors and solutes emanating from organic liquids spilled in the unsaturated zone. The mathematical modeling analysis presented in this paper demonstrates for gasoline-range hydrocarbons, and other volatile organics commonly spilled, that diffusive transport in the unsaturated zone in a significant transport mechanism which can cause aqueous and vapor plumes to spread away from

  19. Iron isotope fractionation between liquid and vapor phases of iron pentacarbonyl.

    PubMed

    Wiesli, René A; Beard, Brian L; Braterman, Paul S; Johnson, Clark M; Saha, Susanta K; Sinha, Mahadeva P

    2007-01-15

    Iron isotope fractionation between liquid and vapor iron pentacarbonyl was measured in a closed system at approximately 0 and approximately 21 degrees C to determine if Fe isotope analysis of iron pentacarbonyl vapor is viable using electron-impact, gas-source mass spectrometry. At the 2sigma level, there is no significant Fe isotope fractionation between vapor and liquid under conditions thought to reflect equilibrium. Experiments at approximately 0 degrees C indicate iron pentacarbonyl vapor is approximately 0.05 per mil (per thousand) greater in (56)Fe/(54)Fe than liquid iron pentacarbonyl, which is just resolvable at the 1sigma level. Partial decomposition of iron pentacarbonyl vapor or liquid to an iron oxide or iron metal shows that significant isotopic fractionation occurs, where the decomposed product has a lower (56)Fe/(54)Fe ratio as compared to the starting iron pentacarbonyl. It follows that methods to decompose iron pentacarbonyl must be quantitative to obtain accurate isotope values. PMID:19071272

  20. Cigarette Smoke Components and Disease: Cigarette Smoke Is More Than a Triad of Tar, Nicotine, and Carbon Monoxide

    Microsoft Academic Search

    Jeffrey E. Harris

    INTRODUCTION Cigarette smoke is a complex mixture of chemicals. Some smoke components, such as carbon monoxide (CO), hydrogen cyanide (HCN), and nitrogen oxides, are gases. Others, such as formaldehyde, acrolein, benzene, and certain N-nitrosamines, are volatile chemicals contained in the liquid- vapor portion of the smoke aerosol. Still others, such as nicotine, phenol, polyaromatic hydrocarbons (PAHs), and certain tobacco-specific nitrosamines

  1. Optimization of High-Quality AlN Epitaxially Grown on (0001) Sapphire by Metal-Organic Vapor-Phase Epitaxy

    E-print Network

    Wetzel, Christian M.

    interestdue to unique properties such as its very wide and direct bandgap and high thermal conductivity. High is performed to optimize aluminum nitride (AlN) epilayers grown on (0001) sapphire by metal-organic vapor-organic vapor-phase epitaxy, nitrides, AlGaN, light emitting diodes Aluminum nitride (AlN) has generated much

  2. 27 CFR 40.352 - Cigarette tubes.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Cigarette tubes. 40.352 Section 40.352 Alcohol...TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Manufacture of Cigarette Papers and Tubes Taxes § 40.352 Cigarette...

  3. 27 CFR 40.352 - Cigarette tubes.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2011-04-01 true Cigarette tubes. 40.352 Section 40.352 Alcohol...TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Manufacture of Cigarette Papers and Tubes Taxes § 40.352 Cigarette...

  4. 27 CFR 40.352 - Cigarette tubes.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Cigarette tubes. 40.352 Section 40.352 Alcohol...TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Manufacture of Cigarette Papers and Tubes Taxes § 40.352 Cigarette...

  5. 27 CFR 40.352 - Cigarette tubes.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Cigarette tubes. 40.352 Section 40.352 Alcohol...TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Manufacture of Cigarette Papers and Tubes Taxes § 40.352 Cigarette...

  6. 27 CFR 40.352 - Cigarette tubes.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Cigarette tubes. 40.352 Section 40.352 Alcohol...TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Manufacture of Cigarette Papers and Tubes Taxes § 40.352 Cigarette...

  7. Improved photoluminescence of organometallic vapor phase epitaxial AlGaAs using a new gettering technique on the arsine source

    Microsoft Academic Search

    J. R. Shealy; V. G. Kreismanis; D. K. Wagner; J. M. Woodall

    1983-01-01

    Using an aluminum-gallium-indium ternary melt for the removal of oxygen and moisture from the arsine source, substantial improvement in the quality of organometallic vapor phase epitaxial AlGaAs can be achieved. The arsine is bubbled through the ternary melt at room temperature prior to its introduction into a low-pressure reactor. Low-temperature photoluminescence spectra indicate an improvement in the sharpness of the

  8. Method of varying a characteristic of an optical vertical cavity structure formed by metalorganic vapor phase epitaxy

    DOEpatents

    Hou, Hong Q. (Albuquerque, NM); Coltrin, Michael E. (Albuquerque, NM); Choquette, Kent D. (Albuquerque, NM)

    2001-01-01

    A process for forming an array of vertical cavity optical resonant structures wherein the structures in the array have different detection or emission wavelengths. The process uses selective area growth (SAG) in conjunction with annular masks of differing dimensions to control the thickness and chemical composition of the materials in the optical cavities in conjunction with a metalorganic vapor phase epitaxy (MOVPE) process to build these arrays.

  9. Homoepitaxial growth of ZnO by metalorganic vapor phase epitaxy in two-dimensional growth mode

    Microsoft Academic Search

    S. Heinze; A. Krtschil; J. Bläsing; T. Hempel; P. Veit; A. Dadgar; J. Christen; A. Krost

    2007-01-01

    We describe the successful homoepitaxial growth of ZnO layers on oxygen-face ZnO substrates by metalorganic vapor-phase epitaxy in two-dimensional growth mode. In detail, we discuss the impact of the oxygen\\/zinc precursor ratio using N2O and O2 as oxygen precursors, growth temperature, and reactor pressure on structural properties and surface morphology as obtained by X-ray diffraction, field emission scanning electron microscopy,

  10. Monolithic integration of InGaAsP\\/InP distributed feedback laser and electroabsorption modulator by vapor phase epitaxy

    Microsoft Academic Search

    Masatoshi Suzuki; Yukio Noda; Hideaki Tanaka; Shigeyuki Akiba; Yukitoshi Kushiro; Hideo Isshiki

    1987-01-01

    Monolithic integration of a 1.55-?m InGaAsP\\/InP distributed feedback (DFB) laser and an electroabsorption (EA) modulator was studied. The difference between the lasing photon energy and the bandgap energy of the modulator waveguide was designed to be 30-40 meV, taking into account the linewidth-enhancement factor and the zero-bias absorption loss. The integrated devices were grown by three-step vapor phase epitaxy (VPE).

  11. Separation of butane and xylene isomers with MFI-type zeolitic membrane synthesized by a vapor-phase transport method

    Microsoft Academic Search

    Takaaki Matsufuji; Norikazu Nishiyama; Masahiko Matsukata; Korekazu Ueyama

    2000-01-01

    MFI-type zeolitic membranes were prepared by a vapor-phase transport (VPT) method on porous ?-alumina flat disks. Single- and mixed-gas permeation measurements of butane isomers were performed in the temperature range of 300–375K. The separation factor was always greater than the ideal selectivity. This result is explained by the preferential adsorption of n-butane on MFI in the binary system.The pervaporation tests

  12. Measurement of monoterpene hydrocarbon levels in vapor phase surrounding single-leaf pinyon (Pinus monophylla Torr. & Frem.: Pinaceae) understory litter.

    PubMed

    Wilt, F M; Miller, G C; Everett, R L

    1993-07-01

    A headspace air-sampling experiment was performed in the laboratory to determine the identity and concentrations of monoterpene hydrocarbons that could be attained in the vapor phase surrounding single-leaf pinyon pine (Pinus monophylla Torr. & Frem.) understory litter using controlled air collection conditions at a simulated field temperature of 37.8°C. The total monoterpene hydrocarbon content in 21 sequential samples of air collected from a sealed glass carboy packed with 1.44 kg of single-leaf pinyon litter equivalent to a bulk density of 0.15 g/cm(3) averaged 3.56 ± 1.04 mg/liter. The monoterpenes?-pinene and camphene were present in the vapor phase at the highest concentrations, averaging 2.40±0.64 and 0.68±0.22 mg/ liter, respectively. Myrcene,?-pinene, 3-carene,?-phellandrene, and?-terpinene were all present at average concentrations below 0.30 mg/liter. The first two traps of the sequential air samples yielded the highest concentrations for the monoterpene hydrocarbons; however, the average total levels were relatively stable throughout the remaining 19 traps. Therefore, the data indicate that these hydrocarbons volatilize from the source pinyon litter and maintain an equilibrium in the vapor phase. Although this analysis was conducted using an artificial system, combined with results from our previous studies, mounting evidence indicates that monoterpene hydrocarbons present in the vapor phase of the single-leaf pinyon understory may be toxic to a variety of native plant species and thus further implicates allelopathy as a significant contributor to the observed patterning of associated vegetation in these forests. PMID:24249172

  13. Structure and photoluminescence of AlP\\/GaP short-period superlattices grown by organometallic vapor phase epitaxy

    Microsoft Academic Search

    Xue-Lun Wang; Akihiro Wakahara; Akio Sasaki

    1994-01-01

    Short-period superlattices of (AlP)m\\/(GaP)n (m, n=4–11.5) are grown by atmospheric pressure organometallic vapor phase epitaxy using tertiarybutylphosphine as a phosphorus source. Structural and optical properties of the grown superlattices are characterized by double-crystal x-ray diffraction and photoluminescence (PL) measurements, respectively. By comparing the measured and the calculated full width at half-maximum of satellite peaks, we find that very high quality

  14. Adsorption equilibrium constants of methyl oleate and methyl linoleate in vapor phase on supported copper and nickel catalysts

    Microsoft Academic Search

    J.-O. Lidefelt

    1983-01-01

    Adsorption equilibrium constants for methyl oleate and methyl linoleate in vapor phase on supported copper and nickel catalysts\\u000a have been determined using the technique of pulse gas chromatography. The results are discussed in relation to selectivity\\u000a in fat hydrogenation. Notation: A, column cross-section, m2 ; an,bn, nth Fourier coefficients; c, concentration of adsorbate in bulk flow, mol\\/m3 ; c* =

  15. Magnesium as p dopant in InGaAs/InP heterojunction bipolar transistors grown by metalorganic vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Dildey, F.; Schier, M.; Ebbinghaus, G.

    1992-04-01

    Magnesium has been used as p dopant for the base in InGaAs/InP heterojunction bipolar transistors during growth by metalorganic vapor phase epitaxy. Very sharp and well controlled Mg profiles were achieved resulting in excellent dc-characteristics of the device. With a layer sequence suitable for high frequency applications, the transistors show a common emitter current gain of about 100 with very weak dependence on collector current, low offset voltage, low output conductance, and high breakdown voltage.

  16. Synthesis, optical, and magnetic properties of diluted magnetic semiconductor Zn1?xMnxO nanowires via vapor phase growth

    Microsoft Academic Search

    Y. Q. Chang; D. B. Wang; X. H. Luo; X. Y. Xu; X. H. Chen; L. Li; C. P. Chen; R. M. Wang; J. Xu; D. P. Yu

    2003-01-01

    Diluted magnetic semiconductor Zn1?xMnxO nanowires were synthesized via an in situ doping of manganese in ZnO nanowires using vapor phase growth at 500 °C. The maximum content of the manganese in the ZnO is around 13 at. %, approaching the maximum thermal equilibrium limit of Mn solubility in ZnO at the growth temperature. Structure and composition analysis revealed that the

  17. Synthesis, optical, and magnetic properties of diluted magnetic semiconductor Zn1-xMnxO nanowires via vapor phase growth

    Microsoft Academic Search

    Y. Q. Chang; D. B. Wang; X. H. Luo; X. Y. Xu; X. H. Chen; L. Li; C. P. Chen; R. M. Wang; J. Xu; D. P. Yu

    2003-01-01

    Diluted magnetic semiconductor Zn1-xMnxO nanowires were synthesized via an in situ doping of manganese in ZnO nanowires using vapor phase growth at 500 °C. The maximum content of the manganese in the ZnO is around 13 at. %, approaching the maximum thermal equilibrium limit of Mn solubility in ZnO at the growth temperature. Structure and composition analysis revealed that the

  18. Vapor-phase interactions and diffusion of organic solvents in the unsaturated zone

    USGS Publications Warehouse

    Roy, W.R.; Griffin, R.A.

    1990-01-01

    This article presents an analysis of the interactions and static movement of 37 organic solvents as vapors through the unsaturated soil zone. The physicochemical interactions of the organic vapors with unsaturated soil materials were emphasized with focus on diffusive, and adsorptive interactions. Fick's Law and porous media diffusion coefficients for most of the solvent vapors were either compiled or estimated; coefficients were not available for some of the fluorinated solvents. The adsorption of some of the solvent vapors by silica was concluded to be due to hydrogen bond formation with surface silanol groups. Heats of adsorption data for different adsorbents were also compiled. There were very few data on the adsorption of these solvent vapors by soils, but it appears that the magnitude of adsorption of nonpolar solvents is reduced as the relative humidity of the vapor-solid system is increased. Consequently, the interaction of the vapors may then separated into two processes; (1) gas-water partitioning described by Henry's Law constants, and (2) solid-water adsorption coefficients which may be estimated from liquid-solid partition coefficients (Kd values). ?? 1990 Springer-Verlag New York Inc.

  19. An Experimental Visualization and Image Analysis of Electrohydrodynamically Induced Vapor-Phase Silicon Oil Flow under DC Corona Discharge

    NASA Astrophysics Data System (ADS)

    Ohyama, Ryu-Ichiro; Fukumoto, Masaru

    A DC corona discharge induced electrohydrodynamic (EHD) flow phenomenon for a multi-phase fluid containing a vapor-phase dielectric liquid in the fresh air was investigated. The experimental electrode system was a simple arrangement of needle-plate electrodes for the corona discharges and high-resistivity silicon oil was used as the vapor-phase liquid enclosure. The qualitative observation of EHD flow patterns was conducted by an optical processing on computer tomography and the time-series of discharge current pulse generations at corona discharge electrode were measured simultaneously. These experimental results were analyzed in relationship between the EHD flow motions and the current pulse generations in synchronization. The current pulses and the EHD flow motions from the corona discharge electrode presented a continuous mode similar to the ionic wind in the fresh air and an intermittent mode. In the intermittent mode, the observed EHD flow motion was synchronized with the separated discharge pulse generations. From these experimental results, it was expected that the existence of silicon oil vapor trapped charges gave an occasion to the intermittent generations of the discharge pulses and the secondary EHD flow.

  20. Toxicological evaluation of cigarettes with two banded cigarette paper technologies.

    PubMed

    Theophilus, Eugenia H; Pence, Deborah H; Meckley, Daniel R; Keith Shreve, W; Ayres, Paul H; Bombick, Betsy R; Borgerding, Michael F; Garner, Charles D; Swauger, James E

    2007-09-01

    A tiered testing strategy has been employed to evaluate the potential of tobacco processes, ingredients, or technological developments to change the biological activity resulting from burning cigarette tobacco. The strategy is based on comparative chemical and biological testing. The introduction of banded cigarette papers in cigarettes to meet New York state "Fire Safety Standards for Cigarettes" constitutes an example of a technological development evaluated utilizing this tiered testing strategy that included a comparison of the chemical and biological effects of cigarettes with and without the banded cigarette paper technologies (BCPT) (representative of current marketed technologies). Specific testing included mainstream cigarette smoke chemistry studies; in vitro studies included genotoxicity (Ames and sister chromatid exchange) and cytotoxicity studies (neutral red); in vivo studies included a 13-week inhalation study in Sprague-Dawley rats and a 30-week dermal tumor promotion study in SENCAR mice. Collectively, data indicated that cigarettes with and without BCPT had a similar toxicological profile in this test battery. PMID:17590321

  1. NOVEL CERAMIC-ORGANIC VAPOR PERMEATION MEMBRANES FOR VOC REMOVAL - PHASE I

    EPA Science Inventory

    Vapor permeation holds much promise for becoming a highly efficient means of preventing VOC emissions that are now generated by a variety of stationary sources, including solvent and surface coating operations, gasoline storage operations, and printing operations. A limitation of...

  2. NOVEL CERAMIC-ORGANIC VAPOR PERMEATION MEMBRANES FOR VOC REMOVAL - PHASE II

    EPA Science Inventory

    Vapor permeation with highly permeable and organic-selective membranes is becoming an increasingly popular technique for preventing VOC emissions that are generated by a variety of stationary sources, including solvent and surface coating operations, gasoline storage operat...

  3. III-nitride nanopyramid light emitting diodes grown by organometallic vapor phase epitaxy.

    SciTech Connect

    Wildeson, I. H.; Colby, R.; Ewoldt, D. A.; Liang, Z.; Zakharov, . N.; Zaluzec, N. J.; Gracia, R. E.; Stach, E. A.; Sands, T. D.; Materials Science Division; Purdue Univ.

    2010-10-06

    Nanopyramid light emitting diodes (LEDs) have been synthesized by selective area organometallic vapor phase epitaxy. Self-organized porous anodic alumina is used to pattern the dielectric growth templates via reactive ion etching, eliminating the need for lithographic processes. (In,Ga)N quantum well growth occurs primarily on the six {l_brace}1{bar 1}01{r_brace} semipolar facets of each of the nanopyramids, while coherent (In,Ga)N quantum dots with heights of up to {approx}20 nm are incorporated at the apex by controlling growth conditions. Transmission electron microscopy (TEM) indicates that the (In,Ga)N active regions of the nanopyramid heterostructures are completely dislocation-free. Temperature-dependent continuous-wave photoluminescence of nanopyramid heterostructures yields a peak emission wavelength of 617 nm and 605 nm at 300 K and 4 K, respectively. The peak emission energy varies with increasing temperature with a double S-shaped profile, which is attributed to either the presence of two types of InN-rich features within the nanopyramids or a contribution from the commonly observed yellow defect luminescence close to 300 K. TEM cross-sections reveal continuous planar defects in the (In,Ga)N quantum wells and GaN cladding layers grown at 650-780 C, present in 38% of the nanopyramid heterostructures. Plan-view TEM of the planar defects confirms that these defects do not terminate within the nanopyramids. During the growth of p-GaN, the structure of the nanopyramid LEDs changed from pyramidal to a partially coalesced film as the thickness requirements for an undepleted p-GaN layer result in nanopyramid impingement. Continuous-wave electroluminescence of nanopyramid LEDs reveals a 45 nm redshift in comparison to a thin-film LED, suggesting higher InN incorporation in the nanopyramid LEDs. These results strongly encourage future investigations of III-nitride nanoheteroepitaxy as an approach for creating efficient long wavelength LEDs.

  4. Matrix Isolation Studies of Carbonic Acid—The Vapor Phase above the ?-Polymorph

    PubMed Central

    2013-01-01

    Twenty years ago two different polymorphs of carbonic acid, ?- and ?-H2CO3, were isolated as thin, crystalline films. They were characterized by infrared and, of late, by Raman spectroscopy. Determination of the crystal structure of these two polymorphs, using cryopowder and thin film X-ray diffraction techniques, has failed so far. Recently, we succeeded in sublimating ?-H2CO3 and trapping the vapor phase in a noble gas matrix, which was analyzed by infrared spectroscopy. In the same way we have now investigated the ?-polymorph. Unlike ?-H2CO3, ?-H2CO3 was regarded to decompose upon sublimation. Still, we have succeeded in isolation of undecomposed carbonic acid in the matrix and recondensation after removal of the matrix here. This possibility of sublimation and recondensation cycles of ?-H2CO3 adds a new aspect to the chemistry of carbonic acid in astrophysical environments, especially because there is a direct way of ?-H2CO3 formation in space, but none for ?-H2CO3. Assignments of the FTIR spectra of the isolated molecules unambiguously reveal two different carbonic acid monomer conformers (C2v and Cs). In contrast to the earlier study on ?-H2CO3, we do not find evidence for centrosymmetric (C2h) carbonic acid dimers here. This suggests that two monomers are entropically favored at the sublimation temperature of 250 K for ?-H2CO3, whereas they are not at the sublimation temperature of 210 K for ?-H2CO3. PMID:23631554

  5. Regularly-patterned nanorod light-emitting diode arrays grown with metalorganic vapor-phase epitaxy

    NASA Astrophysics Data System (ADS)

    Tu, Charng-Gan; Su, Chia-Ying; Liao, Che-Hao; Hsieh, Chieh; Yao, Yu-Feng; Chen, Hao-Tsung; Lin, Chun-Han; Chen, Horng-Shyang; Kiang, Yean-Woei; Yang, C. C.

    2015-07-01

    The growth and fabrication of GaN nanorod (NR) light-emitting diode (LED) arrays have attracted much attention because of their advantages of higher crystal quality, larger sidewall emission area, and non-polar or semi-polar quantum well (QW) formation. In this paper, we review the development of regularly-patterned GaN NR LED arrays grown with metalorganic vapor-phase epitaxy. Such an array device is expected to be useful for practical lighting application. A regularly-patterned NR array is grown on a patterned template with either continuous or pulsed growth mode. Usually, with the pulsed growth mode, by switching group-III and V sources on and off alternatively, the NR geometry can be more uniform over an array. InGaN/GaN QWs can be deposited on the c-plane top face, m-plane sidewalls, and { 1 1 bar 0 1 } -plane slant facets on a c-axis-oriented NR with the highest (lowest) growth rate in the c-plane ({ 1 1 bar 0 1 } -plane). After the overgrowth of p-GaN on an NR with n-GaN core and QW deposition, an NR LED array can be implemented by covering the NRs with a transparent conductor. It has been demonstrated that the optical and electrical performances of an NR LED array can be comparable to those of a planar LED. Further developments in NR LED growth and process techniques can lead to an outperforming LED device with the NR structure.

  6. Solid-State, Dye-Labeled DNA Detects Volatile Compounds in the Vapor Phase

    PubMed Central

    White, Joel; Truesdell, Kathleen; Williams, Lloyd B; AtKisson, Mary S; Kauer, John S

    2008-01-01

    This paper demonstrates a previously unreported property of deoxyribonucleic acid—the ability of dye-labeled, solid-state DNA dried onto a surface to detect odors delivered in the vapor phase by changes in fluorescence. This property is useful for engineering systems to detect volatiles and provides a way for artificial sensors to emulate the way cross-reactive olfactory receptors respond to and encode single odorous compounds and mixtures. Recent studies show that the vertebrate olfactory receptor repertoire arises from an unusually large gene family and that the receptor types that have been tested so far show variable breadths of response. In designing biomimetic artificial noses, the challenge has been to generate a similarly large sensor repertoire that can be manufactured with exact chemical precision and reproducibility and that has the requisite combinatorial complexity to detect odors in the real world. Here we describe an approach for generating and screening large, diverse libraries of defined sensors using single-stranded, fluorescent dye–labeled DNA that has been dried onto a substrate and pulsed with brief exposures to different odors. These new solid-state DNA-based sensors are sensitive and show differential, sequence-dependent responses. Furthermore, we show that large DNA-based sensor libraries can be rapidly screened for odor response diversity using standard high-throughput microarray methods. These observations describe new properties of DNA and provide a generalized approach for producing explicitly tailored sensor arrays that can be rationally chosen for the detection of target volatiles with different chemical structures that include biologically derived odors, toxic chemicals, and explosives. PMID:18215112

  7. Vapor-liquid phase coexistence and transport properties of two-dimensional oligomers

    NASA Astrophysics Data System (ADS)

    Patra, Tarak K.; Hens, Abhiram; Singh, Jayant K.

    2012-08-01

    Grand-canonical transition-matrix Monte Carlo and histogram reweighting techniques are used herein to study the vapor-liquid coexistence properties of two-dimensional (2D) flexible oligomers with varying chain lengths (m = 1-8). The phase diagrams of the various 2D oligomers follow the correspondence state (CS) principle, akin to the behavior observed for bulk oligomers. The 2D critical density is not influenced by the oligomer chain length, which contrasts with the observation for the bulk oligomers. Line tension, calculated using Binder's formalism, in the reduced plot is found to be independent of chain length in contrast to the 3D behavior. The dynamical properties of 2D fluids are evaluated using molecular dynamics simulations, and the velocity and pressure autocorrelation functions are investigated using Green-Kubo (GK) relations to yield the diffusion and viscosity. The viscosity determined from 2D non-equilibrium molecular dynamics simulation is compared with the viscosity estimated from the GK relations. The GK relations prove to be reliable and efficient for the calculation of 2D transport properties. Normal diffusive regions are identified in dense oligomeric fluid systems. The influence of molecular size on the diffusivity and viscosity is found to be diminished at specific CS points for the 2D oligomers considered herein. In contrast, the viscosity and diffusion of the 3D bulk fluid, at a reduced temperature and density, are strongly dependent on the molecular size at the same CS points. Furthermore, the viscosity increases and the diffusion decreases multifold in the 2D system relative to those in the 3D system, at the CS points.

  8. Vapor-liquid phase coexistence and transport properties of two-dimensional oligomers.

    PubMed

    Patra, Tarak K; Hens, Abhiram; Singh, Jayant K

    2012-08-28

    Grand-canonical transition-matrix Monte Carlo and histogram reweighting techniques are used herein to study the vapor-liquid coexistence properties of two-dimensional (2D) flexible oligomers with varying chain lengths (m = 1-8). The phase diagrams of the various 2D oligomers follow the correspondence state (CS) principle, akin to the behavior observed for bulk oligomers. The 2D critical density is not influenced by the oligomer chain length, which contrasts with the observation for the bulk oligomers. Line tension, calculated using Binder's formalism, in the reduced plot is found to be independent of chain length in contrast to the 3D behavior. The dynamical properties of 2D fluids are evaluated using molecular dynamics simulations, and the velocity and pressure autocorrelation functions are investigated using Green-Kubo (GK) relations to yield the diffusion and viscosity. The viscosity determined from 2D non-equilibrium molecular dynamics simulation is compared with the viscosity estimated from the GK relations. The GK relations prove to be reliable and efficient for the calculation of 2D transport properties. Normal diffusive regions are identified in dense oligomeric fluid systems. The influence of molecular size on the diffusivity and viscosity is found to be diminished at specific CS points for the 2D oligomers considered herein. In contrast, the viscosity and diffusion of the 3D bulk fluid, at a reduced temperature and density, are strongly dependent on the molecular size at the same CS points. Furthermore, the viscosity increases and the diffusion decreases multifold in the 2D system relative to those in the 3D system, at the CS points. PMID:22938253

  9. Recent progress in GaInAsSb thermophotovoltaics grown by organometallic vapor phase epitaxy

    SciTech Connect

    Wang, C.A.; Choi, H.K.; Oakley, D.C. [Massachusetts Inst. of Tech., Lexington, MA (United States). Lincoln Lab.; Charache, G.W. [Lockheed Martin, Inc., Schenectady, NY (United States)

    1998-06-01

    Studies on the materials development of Ga{sub 1{minus}x}In{sub x}As{sub y}Sb{sub 1{minus}y} alloys for thermophotovoltaic (TPV) devices are reviewed. Ga{sub 1{minus}x}In{sub x}As{sub y}Sb{sub 1{minus}y} epilayers were grown lattice matched to GaSb substrates by organometallic vapor phase epitaxy (OMVPE) using all organometallic precursors including triethylgallium, trimethylindium, tertiarybutylarsine, and trimethylantimony with diethyltellurium and dimethylzinc as the n- and p-type dopants, respectively. The overall material quality of these alloys depends on growth temperature, In content, V/III ratio, substrate misorientation, and to a lesser extent, growth rate. A mirror-like surface morphology and room temperature photoluminescence (PL) are obtained for GaInAsSb layers with peak emission in the wavelength range between 2 and 2.5 {micro}m. The crystal quality improves for growth temperature decreasing from 575 to 525 C, and with decreasing In content, as based on epilayer surface morphology and low temperature PL spectra. A trend of smaller full width at half-maximum for low temperature PL spectra is observed as the growth rate is increased from 1.5 to 2.5 and 5 {micro}m/h. In general, GaInAsSb layers grown on (100) GaSb substrates with a 6{degree} toward (111)B misorientation exhibited overall better material quality than layers grown on the more standard substrate (100)2{degree} toward (110). Consistent growth of high performance lattice-matched GaInAsSb TPV devices is also demonstrated.

  10. Mw Spectroscopy Coupled with Ultrafast UV Laser Vaporization: {RIBOSE} Found in the Gas Phase

    NASA Astrophysics Data System (ADS)

    Cocinero, Emilio J.; Ecija, Patricia; Basterretxea, Francisco J.; Fernandez, Jose A.; Castano, Fernando; Lesarri, Alberto; Grabow, Jens-Uwe

    2012-06-01

    Sugars are aldoses or ketoses with multiple hydroxy groups which have been elusive to spectroscopic studies. Here we report a rotational study of the aldopentose ribose. According to any standard textbook aldopentoses can exhibit either linear forms, cyclic five-membered (furanose) structures or six-membered (pyranose) rings, occurring either as ?- or ?- anomers depending on the orientation of the hydroxy group at C-1 (anomeric carbon). ?-Furanose is predominant in ribonucleosides, RNA, ATP and other biochemically relevant derivatives, but is ?-furanose the native form also of free ribose? Recent condensed-phase X-ray and older NMR studies delivered conflicting results. In order to solve this question we conducted a microwave study on D-ribose that, owing to ultrafast UV laser vaporization, has become the first C-5 sugar observed with rotational resolution. The spectrum revealed six conformations of free ribose, preferentially adopting ?-pyranose chairs as well as higher-energy ?-pyranose forms. The method also allowed for unambiguous distinction between different orientations of the hydroxy groups, which stabilize the structures by cooperative hydrogen-bond networks. No evidence was observed of the ?-/?-furanoses or linear forms found in the biochemical derivatives. i) D. Šišak, L. B. McCusker, G. Zandomeneghi, B. H. Meier, D. Bläser, R. Boese, W. B. Schweizer, R. Gylmour and J. D. Dunitz Angew. Chem. Int. Ed. 49, 4503, 2010. ii) W. Saenger Angew. Chem. Int. Ed. 49, 6487, 2010. i) M. Rudrum, and D. F. Shaw, J. Chem. Soc. 52, 1965. ii) R. U. Lemieux and J. D. Stevens Can. J. Chem. 44, 249, 1966. iii) E. Breitmaier and U. Hollstein Org. Magn. Reson. 8, 573, 1976. E. J. Cocinero, A. Lesarri, P. Écija, F. J. Basterretxea, J. U. Grabow, J. A. Fernández and F. Castaño Angew. Chem. Int. Ed. in press: DOI: 10.1002/anie.201107973, 2012.

  11. Investigation of vapor-phase lubrication in a gas turbine engine

    SciTech Connect

    Van Treuren, K.W.; Barlow, D.N.; Heiser, W.H. [Air Force Academy, Colorado Springs, CO (United States). Dept. of Aeronautics; Wagner, M.J.; Forster, N.H. [Aero Propulsion and Power Directorate, Wright-Patterson AFB, OH (United States). Fuels and Lubrication Div.

    1998-04-01

    The liquid oil lubrication system of current aircraft jet engines accounts for approximately 10--15% of the total weight of the engine. It has long been a goal of the aircraft gas turbine industry to reduce this weight. Vapor-Phase Lubrication (VPL) is a promising technology to eliminate liquid oil lubrication. The current investigation resulted in the first gas turbine to operate in the absence of conventional liquid lubrication. A phosphate ester, commercially known as DURAD 620B, was chosen for the test. Extensive research at Wright Laboratory demonstrated that this lubricant could reliably lubricate rolling element bearings in the gas turbine engine environment. The Allison T63 engine was selected as the test vehicle because of its small size and bearing configuration. Specifically, VPL was evaluated in the number eight bearing because it is located in a relatively hot environment, in line with the combustor discharge, and it can be isolated from the other bearings and the liquid lubrication system. The bearing was fully instrumented and its performance with standard oil lubrication was documented. Results of this baseline study were used to develop a thermodynamic model to predict the bearing temperature with VPL. The engine was then operated at a ground idle condition with VPL with the lubricant misted into the No. 8 bearing at 13 ml/h. The bearing temperature stabilized at 283 C within 10 minutes. Engine operation was continued successfully for a total of one hour. No abnormal wear of the rolling contact surfaces was found when the bearing was later examined. Bearing temperatures after engine shutdown indicated the bearing had reached thermodynamic equilibrium with its surroundings during the test.

  12. Characterization of vapor phase mercury released from concrete processing with baghouse filter dust added cement.

    PubMed

    Wang, Jun; Hayes, Josh; Wu, Chang-Yu; Townsend, Timothy; Schert, John; Vinson, Tim; Deliz, Katherine; Bonzongo, Jean-Claude

    2014-02-18

    The fate of mercury (Hg) in cement processing and products has drawn intense attention due to its contribution to the ambient emission inventory. Feeding Hg-loaded coal fly ash to the cement kiln introduces additional Hg into the kiln's baghouse filter dust (BFD), and the practice of replacing 5% of cement with the Hg-loaded BFD by cement plants has recently raised environmental and occupational health concerns. The objective of this study was to determine Hg concentration and speciation in BFD as well as to investigate the release of vapor phase Hg from storing and processing BFD-added cement. The results showed that Hg content in the BFD from different seasons ranged from 0.91-1.44 mg/kg (ppm), with 62-73% as soluble inorganic Hg, while Hg in the other concrete constituents were 1-3 orders of magnitude lower than the BFD. Up to 21% of Hg loss was observed in the time-series study while storing the BFD in the open environment by the end of the seventh day. Real-time monitoring in the bench system indicated that high temperature and moisture can facilitate Hg release at the early stage. Ontario Hydro (OH) traps showed that total Hg emission from BFD is dictated by the air exchange surface area. In the bench simulation of concrete processing, only 0.4-0.5% of Hg escaped from mixing and curing BFD-added cement. A follow-up headspace study did not detect Hg release in the following 7 days. In summary, replacing 5% of cement with the BFD investigated in this study has minimal occupational health concerns for concrete workers, and proper storing and mixing of BFD with cement can minimize Hg emission burden for the cement plant. PMID:24444016

  13. Vapor phase strengthening of nickel-based alloys for actively-cooled thermostructural panels

    NASA Astrophysics Data System (ADS)

    Perez-Bergquist, Sara Jane

    Actively cooled thermostructural panels for use in emerging hypersonic flight systems require the use of advanced materials able to support substantial loads at elevated temperatures. A major challenge in this advancing technology is identifying formable structural materials that are strong, tough and oxidation resistant. For thermostructural panels to be optimized for low mass with an appropriate combination of mechanical strength and cooling capacity, the panel is required to have a thin-walled geometry. Advanced, high strength cast Ni-based alloys have attractive properties, but the fabrication of sub-millimeter walls with conventional casting processes would be extremely challenging. The purpose of this study is to develop a new processing path that would result in a rectangular channeled panel made of a nickel-based precipitation strengthened alloy in a previously unobtainable thin-walled geometry suitable for active cooling. Beginning with thin sheets of Ni-based solid-solution alloys and subsequently strengthening the material by vapor phase aluminization combined with an annealing treatment, this objective is accomplished. This study includes selecting a wrought nickel-based alloy as the base substrate for panel fabrication, determining a goal gamma + gamma' microstructure, fabricating rectangular channeled panels, and testing the actively cooled panels at high temperature. Thermodynamic, yield strength, and panel geometry modeling was integrated to determine an optimized geometry and microstructure for the strengthened panel. Panels were fabricated with the optimized geometry and tested at high temperature with active cooling in both the as-fabricated and strengthened states. The strengthened panel was able to withstand a temperature 478°C higher than the as-fabricated panel indicating the increase in strengthening and temperature capability possible with this process.

  14. X-ray-induced phase transformation in congruent and vapor-transport-equilibrated lithium tantalate

    E-print Network

    Byer, Robert L.

    of 60 mol % Li2O and 40 mol % Ta2O5 . VTE processing was carried out in the temperature range of 1100 rich. The mixture chosen served as a source of Li2O with a vapor pressure that corresponds exactly with the vapor pressure of Li2O over stoichiometric LT at the same temperature. Co K radiation was used for the x

  15. Influence of mass diffusion on the stability of thermophoretic growth of a solid from the vapor phase

    NASA Technical Reports Server (NTRS)

    Castillo, J. L.; Garcia-Ybarra, P. L.; Rosner, D. E.

    1991-01-01

    The stability of solid planar growth from a binary vapor phase with a condensing species dilute in a carrier gas is examined when the ratio of depositing to carrier species molecular mass is large and the main diffusive transport mechanism is thermal diffusion. It is shown that a deformation of the solid-gas interface induces a deformation of the gas phase isotherms that increases the thermal gradients and thereby the local mass deposition rate at the crests and reduces them at the valleys. The initial surface deformation is enhanced by the modified deposition rates in the absence of appreciable Fick/Brownian diffusion and interfacial energy effects.

  16. Smoke chemistry, in vitro and in vivo toxicology evaluations of the electrically heated cigarette smoking system series K.

    PubMed

    Werley, Michael S; Freelin, Susan A; Wrenn, Susan E; Gerstenberg, Birgit; Roemer, Ewald; Schramke, Heike; Van Miert, Erik; Vanscheeuwijck, Patrick; Weber, Susanne; Coggins, Christopher R E

    2008-11-01

    The Electrically Heated Cigarette Smoking System Series K (EHCSS) produces smoke through the controlled electrical heating of tobacco. Evaluation of the EHCSS was accomplished by comparison with commercial and reference cigarettes, using International Organization for Standardization (ISO) and alternative puffing regimens based on nicotine exposures measured in a short-term clinical study. Using the alternative puffing regimen and compared with conventional cigarettes on a per cigarette basis, the EHCSS had 50-60% reductions in tar and nicotine; at least 90% reductions in carbon monoxide, nitrogen oxides, 1,3-butadiene, isoprene, acrylonitrile, polyaromatic hydrocarbons, hydrogen cyanide, aromatic amines, tobacco specific nitrosamines, and phenol; and least a 40% reduction in 2-nitropropane. Other important smoke constituents in EHCSS smoke were reduced as well. The in vitro studies showed similar large reductions in biological activity. Ames mutagenicity of total particulate matter (TPM) from the EHCSS was reduced by 70-90%; cytotoxicity of the TPM was reduced by approximately 82% and 65% for the gas-vapor phase. In vivo testing under ISO smoking conditions in the mouse skin painting assay demonstrated later dermal tumor onset, lower dermal tumor incidence, reduced dermal tumor multiplicity, and a lower proportion of malignant dermal tumors in EHCSS smoke condensate-exposed mice. Thirty-five day and 90-day nose-only inhalation studies in rats showed reductions in pulmonary inflammation and other biological activity, including histopathological endpoints. We conclude that under the conditions of these in vitro and in vivo studies, the EHCSS demonstrated significantly lower biological activity compared to conventional cigarettes, and may suggest the potential for reductions in human smokers. PMID:18590791

  17. The effect of cigarette smoking on the indexes of immunity and acute phase reaction in subjects with occupational exposure to organic solvents.

    PubMed

    Moszczynski, P

    1993-06-01

    The study was carried out in 156 men, including 49 nonsmokers and 47 smokers who had never been exposed to chemicals, 19 nonsmokers exposed to organic solvents, and 41 smokers exposed to organic solvents. The results of toxicological analysis of air in the working place carried out in the range depending on the type of solvents used in the process of lacquering of steel cans and on the data obtained from the producer showed that the solvents contained benzene, toluene, xylene and their derivatives partly hydrogenated, paraffin hydrocarbons, oleins, naphthenes (components of painter's naphtha), monohydric and polyhydric alcohols (butanol, cyclohexanol, butyloglycol), esters (ethylglycol acetate, butyl acetate) and ketones (methyl isobutyl ketone, cyclohexanone). Measured benzene concentrations varied from 0 to 370 mg x m-3 (0 to 116 ppm), with arithmetic mean annual averages of about 100 mg x m-3 (31 ppm) in the late 1960's and less than 50 mg x m-3 (16 ppm) in the 1970's. In the 1980's values for the TWA were 0-38 mg x m-3 (0-12 ppm) with arithmetic mean averages of about 19 mg x m-3 (6 ppm) and for the level of benzene 0-351 mg x m-3 (0-110 ppm), with arithmetic mean annual averages of about 48 mg x m-3 (15 ppm). Phenol concentration in the urine of the workers in groups was 7.9 +/- 3.5; 10.0 +/- 5.8; 16.8 +/- 6.2 and 18.4 +/- 9.7 mg x 1(-1) respectively. Hippuric acid concentration in the urine of the workers in groups was 496 +/- 326, 538 +/- 341, 982 +/- 420 and 1107 +/- 507 mg x 1(-1) respectively. The parameters of immunity and proteins acute phase reaction were determined, measuring the count of T, B, and "non-T, non-B" circulating lymphocytes, the concentration of immunoglobulins, lysozyme, C3c, C4, alpha 1-acid glycoprotein, haptoglobulin and ceruloplasmin in serum. The results of the presented study suggest the role of cigarette smoking as a co-factor in the immunological changes brought out by occupational exposure to organic solvents. This phenomenon is reflected in the changes of IgA, IgD, IgG, IgM and lysozyme in the serum, and number of circulating T cells. PMID:8305889

  18. Vapor phase synthesis of compound semiconductors, from thin films to nanoparticles

    NASA Astrophysics Data System (ADS)

    Sarigiannis, Demetrius

    A counterflow jet reactor was developed to study the gas-phase decomposition kinetics of organometallics used in the vapor phase synthesis of compound semiconductors. The reactor minimized wall effects by generating a reaction zone near the stagnation point of two vertically opposed counterflowing jets. Smoke tracing experiments were used to confirm the stability of the flow field and validate the proposed heat, mass and flow models of the counterflow jet reactor. Transport experiments using ethyl acetate confirmed the overall mass balance for the system and verified the ability of the model to predict concentrations at various points in the reactor under different flow conditions. Preliminary kinetic experiments were performed with ethyl acetate and indicated a need to redesign the reactor. The counterflow jet reactor was adapted for the synthesis of ZnSe nanoparticles. Hydrogen selenide was introduced through one jet and dimethylzinc-triethylamine through the other. The two precursors reacted in a region near the stagnation zone and polycrystalline particles of zinc selenide were reproducibly synthesized at room temperature and collected for analysis. Raman spectroscopy confirmed that the particles were crystalline zinc selenide, Morphological analysis using SEM clearly showed the presence of aggregates of particles, 40 to 60 nanometers in diameter. Analysis by TEM showed that the particles were polycrystalline in nature and composed of smaller single crystalline nanocrystallites, five to ten nanometers in diameter. The particles in the aggregate had the appearance of being sintered together. To prevent this sintering, a split inlet lower jet was designed to introduce dimethylzinc through the inner tube and a surface passivator through the outer one. This passivating agent appeared to prevent the particles from agglomerating. An existing MOVPE reactor for II-VI thin film growth was modified to grow III-V semiconductors. A novel new heater was designed and built around an easily replaceable, economical, 650-watt, tungsten-halogen lamp. The heater was successfully tested to temperatures up to 1500°F. The deposition reactor was successfully tested by growing a thin film of GaP on GaAs <100>. The film surface was imperfect but the experiments proved that the reactor was ready for service.

  19. Vapor Phase Boric Acid Treatments for Cotton Batting To Meet U.S. Mattress Flammability Standard Ff 4-72

    Microsoft Academic Search

    Nestor B. Knoepfler; John P. Madacsi; Julius P. Neumeyer

    1976-01-01

    The U.S. Mattress Flammability Standard FF 4-72 imple mented in December 1973 requires that mattresses resist ignition by lighted cigarettes placed on the bare mattress surfaces at specified loca tions, as well as similar tests where the cigarettes are placed between two sheets. This standard, while implying flammability, really measures resist ance of cotton mattresses to the initiation of smoldering

  20. Magmatic Vapor Phase Transport of Copper in Reduced Porphyry Copper-Gold Deposits: Evidence From PIXE Microanalysis of Fluid Inclusions

    NASA Astrophysics Data System (ADS)

    Rowins, S. M.; Yeats, C. J.; Ryan, C. G.

    2002-05-01

    Nondestructive proton-induced X-ray emission (PIXE) studies of magmatic fluid inclusions in granite-related Sn-W deposits [1] reveal that copper transport out of reduced felsic magmas is favored by low-salinity vapor and not co-existing high-salinity liquid (halite-saturated brine). Copper transport by magmatic vapor also has been documented in oxidized porphyry Cu-Au deposits, but the magnitude of Cu partitioning into the vapor compared to the brine generally is less pronounced than in the reduced magmatic Sn-W systems [2]. Consideration of these microanalytical data leads to the hypothesis that Cu and, by inference, Au in the recently established "reduced porphyry copper-gold" (RPCG) subclass should partition preferentially into vapor and not high-salinity liquid exsolving directly from fluid-saturated magmas [3-4]. To test this hypothesis, PIXE microanalysis of primary fluid inclusions in quartz-sulfide (pyrite, pyrrhotite & chalcopyrite) veins from two RPCG deposits was undertaken using the CSIRO-GEMOC nuclear microprobe. PIXE microanalysis for the ~30 Ma San Anton deposit (Mexico) was done on halite-saturated aqueous brine (<10 vol.% vapor) and co-existing low-salinity aqueous vapor (<20 vol.% liquid) inclusions. Results indicate that vapor inclusions have higher concentrations of Cu (typically 1000's of ppm; max. 7277 ppm) compared to brine inclusions (typically 100's of ppm). Brine inclusions also are much higher in Cl (Na), K, Ca, Mn, Zn, and Fe. Only Pb concentrations approach those in the vapor. Metal ratios such as Cu/Fe and Cu/Zn are 2 to 167 times higher in the vapor compared with the brine inclusions. Cu/Pb ratios are 2 to 15 times higher in the vapor than in the brine. PIXE microanalysis for the ~617 Ma 17 Mile Hill deposit (W. Australia) was done on halite-saturated "aqueous" inclusions, which contain a small (<10 vol.%) bubble of carbonic fluid, and adjacent "carbonic" inclusions, which have a thin rim of aqueous liquid (<10 vol.%) wetting the walls of the inclusion [3,5]. Results indicate that carbonic inclusions possess higher concentrations of Cu (47 to 2387 ppm; mean 453 ppm) compared to aqueous inclusions (5 to 190 ppm; mean 50 ppm). The aqueous inclusions also are much higher in Cl (Na), K, Ca, and Mn, but have similar abundances of Fe, Zn, and Pb. The metal ratios Cu/Fe, Cu/Zn, and Cu/Pb are 2 to 22 times higher in the carbonic inclusions than in the aqueous inclusions. Interpretation of these 17 Mile Hill PIXE data, however, requires some caution because carbonic and aqueous inclusions in a different grain of quartz from the same vein have similarly low concentrations of Cu (38 to 928 ppm), Fe (152 to 1168 ppm), Zn (26 to 162 ppm) and Pb (121 to 914 ppm). For these inclusions, the preferential partitioning of metals apparently has not occurred. These first PIXE data for deposits of the new RPCG subclass demonstrate the greater potential of these systems, compared to the classically oxidized porphyry Cu-Au systems, to transport Cu and probably precious metals in a magmatic aqueous vapor phase. These PIXE data also support the possibility that Cu partitions preferentially into an immiscible CO2-rich magmatic fluid. References: [1] Heinrich, C.A. et al. (1992) Econ. Geol., 87, 1566-1583. [2] Heinrich, C.A. et al. (1999) Geology, 27, 755-758. [3] Rowins, S.M. (2000) Geology, 28, 491-494. [4] Rowins, S.M. (2000) The Gangue, GAC-MDD Newsletter, 67, 1-7 (www.gac.ca). [5] Rowins, S.M. et al. (1993) Geol. Soc. Australia Abs., 34, 68-70.

  1. Monomolecular layers and thin films of silane coupling agents by vapor-phase adsorption on oxidized aluminum

    SciTech Connect

    Kurth, D.G.; Bein, T. [Purdue Univ., West Lafayette, IN (United States)

    1992-08-06

    Thin films of tetraethoxysilane [TEOS], (3-bromopropyl)trimethoxysilane [BPS], trimethoxyvinylsilane [VS], and 3-(trimethoxysilyl) propyl methacrylate [TPM] on oxidized aluminum surfaces have been investigated by reflection-absorption FTIR spectroscopy, ellipsometry, contact angle, and quartz crystal microbalance (QCM) measurements. Gravimetric measurements with the QCM can reveal quantitative aspects of adsorption and film formation, even for films as thin as monolayers. Adsorption of these silane coupling agents from solution typically produces multilayer films. Vapor-phase adsorption of TEOS and TPM at room temperature results in monomolecular layers. The coupling agents VS and BPS require additional heating after the vapor-phase adsorption to initiate the hydrolysis and condensation reactions necessary for the surface attachment, which produces one to three layers. For vapor adsorbed films a packing density of 4-7 molecules/nm{sup 2} was found. The data strongly suggest that the organic moieties in several of these films have a preferential orientation on the surface; they can be viewed as two-dimensional, oligomeric siloxane networks with oriented organic chains. Subsequent heating of TPM films results in structural rearrangements; heating of TEOS results in complete condensation to SiO{sub 2} films. 43 refs., 6 figs., 4 tabs.

  2. Sol-gel synthesis of MCM-41 silicas and selective vapor-phase modification of their surface

    NASA Astrophysics Data System (ADS)

    Roik, N. V.; Belyakova, L. A.

    2013-11-01

    Silica particles with uniform hexagonal mesopore architecture were synthesized by template directed sol-gel condensation of tetraethoxysilane or mixture of tetraethoxysilane and (3-chloropropyl)triethoxysilane in a water-ethanol-ammonia solution. Selective functionalization of exterior surface of parent materials was carried out by postsynthetic treatment of template-filled MCM-41 and Cl-MCM-41 with vapors of (3-chloropropyl)triethoxysilane and 1,2-ethylenediamine in vacuum. The chemical composition of obtained mesoporous silicas was estimated by IR spectroscopy and chemical analysis of surface products of reactions. Characteristics of porous structure of resulting materials were determined from the data of X-ray, low-temperature nitrogen ad-desorption and transmission electron microscopy measurements. Obtained results confirm invariability of highly ordered mesoporous structure of MCM-41 and Cl-MCM-41 after their selective postsynthetic modification in vapor phase. It was proved that proposed method of vapor-phase functionalization of template-filled starting materials is not accompanied by dissolution of the template and chemical modification of pores surface. This provides preferential localization of grafted functional groups onto the exterior surface of mesoporous silicas.

  3. Vapor-phase activities of cinnamon, thyme, and oregano essential oils and key constituents against foodborne microorganisms.

    PubMed

    López, Patricia; Sanchez, Cristina; Batlle, Ramón; Nerín, Cristina

    2007-05-30

    The aim of the study presented here was to gain knowledge about the vapor-phase antimicrobial activity of selected essential oils and their major putatively active constituents against a range of foodborne bacterial and fungal strains. In a first step, the vapor-phase antimicrobial activities of three commercially available essential oils (EOs)-cinnamon (Cinnamomum zeylanicum), thyme (Thymus vulgaris), and oregano (Origanum vulgare)-were evaluated against a wide range of microorganisms, including Gram-negative bacteria (Escherichia coli, Yersinia enterocolitica, Pseudomonas aeruginosa, and Salmonella choleraesuis), Gram-positive bacteria (Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus, and Enterococcus faecalis), molds (Penicillium islandicum and Aspergillus flavus), and a yeast (Candida albicans). The minimum inhibitory concentrations (MICs) were generally lower for oregano EO than for the thyme and cinnamon EOs, especially against the relatively resistant Gram-negative. The persistence of the EOs' antimicrobial activities over time was assessed, and changes in the composition of the atmosphere they generated over time were determined using single-drop microextraction (SDME) in combination with gas chromatography-mass spectrometry (GC-MS) and subsequent analysis of the data by principal component analysis (PCA). More relevant chemicals were selected. In addition, the vapor-phase activities of putatively key constituents of the oils were screened against representative Gram-positive (L. monocytogenes) and Gram-negative (S. choleraesuis) bacteria, a mold (A. flavus), and a yeast (C. albicans). Of the tested compounds, cinnamaldehyde, thymol, and carvacrol showed the strongest antimicrobial effectiveness, so their MICs, defined as the minimum vapor concentrations that completely inhibited detectable growth of the microorganisms, were calculated. To check for possible interactions between components present in the EOs, cinnamon EO was fortified with cinnamaldehyde and thyme EO with thymol, and then the antimicrobial activities of the fortified oils were compared to those of the respective unfortified EOs using fractional inhibitory concentration (FIC) indices and by plotting inhibition curves as functions of the vapor-phase concentrations. Synergistic effects were detected for cinnamaldehyde on A. flavus and for thymol on L. monocytogenes, S. choleraesuis, and A. flavus. In all other cases the fortification had additive effects, except for cinnamaldehyde's activity against S. choleraesuis, for which the effect was antagonistic. Finally, various microorganisms were found to cause slight changes over time to the atmospheres generated by all of the EOs (fortified and unfortified) except the fortified cinnamon EO. PMID:17488023

  4. Effect of the vapor phase on the salinity of halite-bearing aqueous fluid inclusions estimated from the halite dissolution temperature

    NASA Astrophysics Data System (ADS)

    Steele-MacInnis, Matthew; Bodnar, Robert J.

    2013-08-01

    Salinities of aqueous fluid inclusions are commonly determined by measuring the temperatures of dissolution of solid phases (daughter minerals) during heating. The vapor bubble is, in most cases, considered to have no mass and to have no effect on the bulk salinity, owing to the low density of the vapor. In the present study we test the assumption that the vapor bubble can be ignored when estimating salinity based on the halite dissolution temperature. The errors in bulk salinity that result from neglecting the vapor bubble are generally less than ˜1.5 wt.% NaCl, and errors of this magnitude occur only when there is a large difference between the halite dissolution temperature and the vapor disappearance temperature (e.g., halite dissolution at ˜450 °C and vapor bubble disappearance at 800 °C) or, stated differently, when the vapor bubble occupies a significant volume fraction of the inclusion at the temperature of halite disappearance. In most cases errors are less than 0.5 wt.% NaCl. Salinity estimated based on Tm,H can be adjusted to account for the contribution of H2O from the vapor phase, using an empirical relationship describing the proportion of liquid in the inclusion at Tm,H as a function of the difference between Th,LV and Tm,H.

  5. Treatment of Produced Waters Using a Surfactant Modified Zeolite/Vapor Phase Bioreactor System

    SciTech Connect

    Soondong Kwon; Elaine B. Darby; Li-Jung Chen; Lynn E. Katz; Kerry A. Kinney; R. S. Bowman; E. J. Sullivan

    2005-03-11

    This report summarizes work performed on this project from October 2004 through March 2005. In previous work, a surfactant modified zeolite (SMZ) was shown to be an effective system for removing BTEX contaminants from produced water. Additional work on this project demonstrated that a compost-based biofilter could biodegrade the BTEX contaminants found in the SMZ regeneration waste gas stream. However, it was also determined that the BTEX concentrations in the waste gas stream varied significantly during the regeneration period and the initial BTEX concentrations were too high for the biofilter to handle effectively. A series of experiments were conducted to determine the feasibility of using a passive adsorption column placed upstream of the biofilter to attenuate the peak gas-phase VOC concentrations delivered to the biofilter during the SMZ regeneration process. In preparation for the field test of the SMZ/VPB treatment system in New Mexico, a pilot-scale SMZ system was also designed and constructed during this reporting period. Finally, a cost and feasibility analysis was also completed. To investigate the merits of the passive buffering system during SMZ regeneration, two adsorbents, SMZ and granular activated carbon (GAC) were investigated in flow-through laboratory-scale columns to determine their capacity to handle steady and unsteady VOC feed conditions. When subjected to a toluene-contaminated air stream, the column containing SMZ reduced the peak inlet 1000 ppmv toluene concentration to 630 ppmv at a 10 second contact time. This level of buffering was insufficient to ensure complete removal in the downstream biofilter and the contact time was longer than desired. For this reason, using SMZ as a passive buffering system for the gas phase contaminants was not pursued further. In contrast to the SMZ results, GAC was found to be an effective adsorbent to handle the peak contaminant concentrations that occur early during the SMZ regeneration process. At a one second residence time, the GAC bed reduced peak contaminant concentrations by 97%. After the initial peak, the inlet VOC concentration in the SMZ regeneration gas stream drops exponentially with time. During this period, the contaminants on the GAC subsequently desorbed at a nearly steady rate over the next 45 hours resulting in a relatively steady effluent concentration of approximately 25 ppm{sub v}. This lower concentration is readily degradable by a downstream vapor phase biofilter (VPB) and the steady nature of the feed stream will prevent the biomass in the VPB from enduring starvation conditions between SMZ regeneration cycles. Repetitive sorption and desorption cycles that would be expected in the field were also investigated. It was determined that although the GAC initially lost some VOC sorption capacity, the adsorption and desorption profiles stabilized after approximately 6 cycles indicating that a GAC bed should be suitable for continuous operation. In preparation for the pilot field testing of the SMZ/VPB system, design, ''in-house'' construction and testing of the field system were completed during this project period. The design of the SMZ system for the pilot test was based on previous investigations by the PI's in Wyoming, 2002 and on analyses of the produced water at the field site in New Mexico. The field tests are scheduled for summer, 2005. A cost survey, feasibility of application and cost analyses were completed to investigate the long term effectiveness of the SMZ/VPB system as a method of treating produced water for re-use. Several factors were investigated, including: current costs to treat and dispose of produced water, end-use water quality requirements, and state and federal permitting requirements.

  6. “Smoking Revolution” A Content Analysis of Electronic Cigarette Retail Websites

    PubMed Central

    Grana, Rachel A.; Ling, Pamela M.

    2014-01-01

    Background Electronic cigarettes (e-cigarettes) have been increasingly available and marketed in the U.S. since 2007. As patterns of product adoption are frequently driven and reinforced by marketing, it is important to understand the marketing claims encountered by consumers. Purpose To describe the main advertising claims made on branded e-cigarette retail websites. Methods Websites were retrieved from two major search engines in 2011 using iterative searches with the following terms: electronic cigarette, e-cigarette, e-cig, and personal vaporizer. Fifty-nine websites met inclusion criteria, and 13 marketing claims were coded for main marketing messages in 2012. Results Ninety-five percent of the websites made explicit or implicit health-related claims, 64% had a smoking cessation-related claim, 22% featured doctors, and 76% claimed that the product does not produce secondhand smoke. Comparisons to cigarettes included claims that e-cigarettes were cleaner (95%) and cheaper (93%). Eighty-eight percent stated that the product could be smoked anywhere and 71% mentioned using the product to circumvent clean air policies. Candy, fruit, and coffee flavors were offered on most sites. Youthful appeals included images or claims of modernity (73%), increased social status (44%), enhanced social activity (32%), romance (31%), and use by celebrities (22%). Conclusions Health claims and smoking cessation messages that are unsupported by current scientific evidence are frequently used to sell e-cigarettes. Implied and overt health claims, the presence of doctors on websites, celebrity endorsements, and the use of characterizing flavors should be prohibited. PMID:24650842

  7. Treatment of Produced Water Using a Surfactant Modified Zeolite/Vapor Phase Bioreactor System

    SciTech Connect

    Lynn E. Katz; Kerry A. Kinney; Robert S. Bowman; Enid J. Sullivan; Soondong Kwon; Elaine B. Darby; Li-Jung Chen; Craig R. Altare

    2006-01-31

    Co-produced water from the oil and gas industry accounts for a significant waste stream in the United States. Produced waters typically contain a high total dissolved solids content, dissolved organic constituents such as benzene and toluene, an oil and grease component as well as chemicals added during the oil-production process. It has been estimated that a total of 14 billion barrels of produced water were generated in 2002 from onshore operations (Veil, 2004). Although much of this produced water is disposed via reinjection, environmental and cost considerations can make surface discharge of this water a more practical means of disposal. In addition, reinjection is not always a feasible option because of geographic, economic, or regulatory considerations. In these situations, it may be desirable, and often necessary from a regulatory viewpoint, to treat produced water before discharge. It may also be feasible to treat waters that slightly exceed regulatory limits for re-use in arid or drought-prone areas, rather than losing them to reinjection. A previous project conducted under DOE Contract DE-AC26-99BC15221 demonstrated that surfactant modified zeolite (SMZ) represents a potential treatment technology for produced water containing BTEX. Laboratory and field experiments suggest that: (1) sorption of benzene, toluene, ethylbenzene and xylenes (BTEX) to SMZ follows linear isotherms in which sorption increases with increasing solute hydrophobicity; (2) the presence of high salt concentrations substantially increases the capacity of the SMZ for BTEX; (3) competitive sorption among the BTEX compounds is negligible; and, (4) complete recovery of the SMZ sorption capacity for BTEX can be achieved by air sparging the SMZ. This report summarizes research for a follow on project to optimize the regeneration process for multiple sorption/regeneration cycles, and to develop and incorporate a vapor phase bioreactor (VPB) system for treatment of the off-gas generated during air sparging. To this end, we conducted batch and column laboratory SMZ and VPB experiments with synthetic and actual produced waters. Based on the results of the laboratory testing, a pilot scale study was designed and conducted to evaluate the combined SMZ/VPB process. An economic and regulatory feasibility analysis was also completed as part of the current study to assess the viability of the process for various water re-use options.

  8. Experimental study of arsenic speciation in vapor phase to 500°C: implications for As transport and fractionation in low-density crustal fluids and volcanic gases

    NASA Astrophysics Data System (ADS)

    Pokrovski, Gleb S.; Zakirov, Ildar V.; Roux, Jacques; Testemale, Denis; Hazemann, Jean-Louis; Bychkov, Andrew Y. u.; Golikova, Galina V.

    2002-10-01

    The stoichiometry and stability of arsenic gaseous complexes were determined in the system As-H 2O ± NaCl ± HCl ± H 2S at temperatures up to 500°C and pressures up to 600 bar, from both measurements of As (III) and As (V) vapor-liquid and vapor-solid partitioning, and X-ray absorption fine structure (XAFS) spectroscopic study of As (III)-bearing aqueous fluids. Vapor-aqueous solution partitioning for As (III) was measured from 250 to 450°C at the saturated vapor pressure of the system (P sat) with a special titanium reactor that allows in situ sampling of the vapor phase. The values of partition coefficients for arsenious acid (H 3AsO 3) between an aqueous solution (pure H 2O) and its saturated vapor (K = mAs vapor /mAs liquid) were found to be independent of As (III) solution concentrations (up to ˜1 to 2 mol As/kg) and equal to 0.012 ± 0.003, 0.063 ± 0.023, and 0.145 ± 0.020 at 250, 300, and 350°C, respectively. These results are interpreted by the formation, in the vapor phase, of As(OH) 3(gas), similar to the aqueous As hydroxide complex dominant in the liquid phase. Arsenic chloride or sulfide gaseous complexes were found to be negligible in the presence of HCl or H 2S (up to ˜0.5 mol/kg of vapor). XAFS spectroscopic measurements carried out on As (III)-H 2O (±NaCl) solutions up to 500°C demonstrate that the As(OH) 3 complex dominates As speciation both in dense H 2O-NaCl fluids and low-density supercritical vapor. Vapor-liquid partition coefficients for As (III) measured in the H 2O-NaCl system up to 450°C are consistent with the As speciation derived from these spectroscopic measurements and can be described by a simple relationship as a function of the vapor-to-liquid density ratio and temperature. Arsenic (III) partitioning between vapor and As-concentrated solutions (>2 mol As/kg) or As 2O 3 solid is consistent with the formation, in the vapor phase, of both As 4O 6 and As(OH) 3. Arsenic (V) (arsenic acid, H 3AsO 4) vapor-liquid partitioning at 350°C for dilute aqueous solution was interpreted by the formation of AsO(OH) 3 in the vapor phase. The results obtained were combined with the corresponding properties for the aqueous As(III) hydroxide species to generate As(OH) 3(gas) thermodynamic parameters. Equilibrium calculations carried out by using these data indicate that As(OH) 3(gas) is by far the most dominant As complex in both volcanic gases and boiling hydrothermal systems. This species is likely to be responsible for the preferential partition of arsenic into the vapor phase as observed in fluid inclusions from high-temperature (400 to 700°C) Au-Cu (-Sn, -W) magmatic-hydrothermal ore deposits. The results of this study imply that hydrolysis and hydration could be also important for other metals and metalloids in the H 2O-vapor phase. These processes should be taken into account to accurately model element fractionation and chemical equilibria during magma degassing and fluid boiling.

  9. [Electronic cigarette: Reliable and efficient?].

    PubMed

    Dautzenberg, Bertrand; Dautzenberg, Marie-Dominique

    2014-01-01

    Before 2010, the e-cigarette remains inefficient then, its dissemination explodes in 2013 where more than 10 million people have tried it in France. The best made e-cigarette will always be potentially toxic and an addictive product. The e-cigarette is not a suitable product for non-smokers and could participate to normalize tobacco in society. To end tobacco, e-cigarette must provide a pleasant throat hit to the smoker in the first 6 seconds then deliver an adequate dose of nicotine. The majority of smokers who have tried the e-cigarette do not adopt the product because they did not like it. Health professional must help those who smoke and use e-cigarettes to remove the last cigarettes. PMID:24890639

  10. Molecular Orbital Studies of Titanium Nitride Chemical Vapor Deposition: Gas Phase Complex Formation,

    E-print Network

    Schlegel, H. Bernhard

    for a number of industrial and commercial applications, including wear-resistant coatings for tools, barrier materials and conductive coatings for microelectronics, and decorative coatings.1-3 Chemical vapor be significantly reduced (500-700 °C) if ammonia is used as the nitrogen source:7 However, if the temperature

  11. Real-time trace detection of vapor-phase elemental mercury and its compounds

    Microsoft Academic Search

    Xiaomei Tong; Robert B. Barat; Arthur T. Poulos

    1999-01-01

    The high toxicity of mercury species (elemental and compound) has prompted a demand for accurate, real-time inventory and control of their emissions. Our method of choice for mercury compound vapor is Photofragment Fluorescence spectroscopy. Target compound concentrations can be related to the fluorescence intensity from an excited fragment. Fragment identities and distributions, as revealed in the fluorescence spectrum provide information

  12. Evaluation of Catalysts from Different Origin for Vapor Phase Upgrading in Biomass Pyrolysis

    SciTech Connect

    Zhang, X.; Mukarakate, C.; Zheng, Z.; Nimlos, M.

    2012-01-01

    Liquid fuels and chemicals from biomass resources arouse much interests in research and development. Fast pyrolysis of biomass has the potential to effectively change solid biomass materials into liquid products. However, bio-oil from traditional pyrolysis processes is difficult to apply in industry, because of its complicated composition, high oxygen content, low stability, etc. Upgrading or refining of the bio-oil should be performed for industrial application of biomass pyrolysis. Often, the process would be done in a separate reactor downstream of the pyrolysis process. In this paper, a laboratory scale micro test facility was constructed, wherein the pyrolysis of pine and catalytic upgrading of the resulting vapors were closely coupled in one reactor. The composition of vapor effluent was monitored with a molecular beam mass spectrometer (MBMS) for the online evaluation of the catalyst performance. Catalysts from different origin were tested and compared for the effectiveness of pyrolysis vapor upgrading, namely commercial zeolites, Ni based steam reforming catalyst, CaO, MgO, and several laboratory-made catalysts. The reaction temperature for catalytic upgrading varied between 400 and 600 centigrade, and the gaseous residence time ranged from 0.1 second to above 2 second, to simulate the conditions in industrial application. It is revealed that some catalysts are active in transform most of primary biomass pyrolysis vapors into hydrocarbons, resulting in nonoxygenated products, which is beneficial for downstream utilization. Others are not as effective, results in minor improvement compared with blank test results.

  13. Experimental identification of evaporator dynamics for vapor compression refrigeration cycle during phase transition

    Microsoft Academic Search

    Juan E. Catano; TieJun Zhang; Yoav Peles; Michael K. Jensen; John T. Wen

    2010-01-01

    Experimental identification of the evaporator dynamics in a vapor compression cycle (VCC) subjected to imposed heat flux in the evaporator is studied. The imposed heat flux boundary condition represents a specific application of the VCC for electronics cooling. However, this application requires different models and control algorithms than traditional VCCs with fluid-to-fluid heat exchanges because of the faster time response

  14. Vapor-phase growth of transparent zinc oxide ceramics with c -axis orientation

    SciTech Connect

    Noritake, F.; Yamamoto, N.; Horiguchi, Y. (Dept. of Research and Development, Lion Corporation, Tokyo, 132 (JP)); Fujitsu, S.; Koumoto, K. (Dept. of Industrial Chemistry, Faculty of Engineering, Univ. of Tokyo, Tokyo 113 (JP)); Yanagida, H. (Research Center for Advanced Science and Technology, Univ. of Tokyo, Tokyo 153 (JP))

    1991-01-01

    Large transparent specimens of polycrystalline zinc oxide with c-axis orientation have been prepared by the vapor transport method. Optical transmittance is 80% to 90% at 800 nm. X-ray diffraction peaks from faces other than (001) are negligible.

  15. Physics-based agent to simulant correlations for vapor phase mass transport.

    PubMed

    Willis, Matthew P; Varady, Mark J; Pearl, Thomas P; Fouse, Janet C; Riley, Patrick C; Mantooth, Brent A; Lalain, Teri A

    2013-12-15

    Chemical warfare agent simulants are often used as an agent surrogate to perform environmental testing, mitigating exposure hazards. This work specifically addresses the assessment of downwind agent vapor concentration resulting from an evaporating simulant droplet. A previously developed methodology was used to estimate the mass diffusivities of the chemical warfare agent simulants methyl salicylate, 2-chloroethyl ethyl sulfide, di-ethyl malonate, and chloroethyl phenyl sulfide. Along with the diffusivity of the chemical warfare agent bis(2-chloroethyl) sulfide, the simulant diffusivities were used in an advection-diffusion model to predict the vapor concentrations downwind from an evaporating droplet of each chemical at various wind velocities and temperatures. The results demonstrate that the simulant-to-agent concentration ratio and the corresponding vapor pressure ratio are equivalent under certain conditions. Specifically, the relationship is valid within ranges of measurement locations relative to the evaporating droplet and observation times. The valid ranges depend on the relative transport properties of the agent and simulant, and whether vapor transport is diffusion or advection dominant. PMID:24225584

  16. Vapor phase detection of plastic explosives using a SAW resonator immunosensor array

    Microsoft Academic Search

    Sang-Hun Lee; D. D. Stubbs; W. D. Hunt; P. J. Edmonson

    2005-01-01

    We present the results of a series of experiments demonstrating on-the-spot detection of low vapor pressure plastic explosives containing nitro groups such as RDX, TNT, and their analogous substances, facilitated by the Transportation Security Administration (TSA) Lab. A set of antibody coated SAW resonators inside the flow cell detect the presence of the target molecules diffusing from the sample. Monoclonal

  17. Characterization of particulate and vapor phase polycyclic aromatic hydrocarbons in indoor and outdoor air of primary schools

    NASA Astrophysics Data System (ADS)

    Krugly, Edvinas; Martuzevicius, Dainius; Sidaraviciute, Ruta; Ciuzas, Darius; Prasauskas, Tadas; Kauneliene, Violeta; Stasiulaitiene, Inga; Kliucininkas, Linas

    2014-01-01

    The indoor air of schools is considered as one of the most important factors affecting the health of children. The aim of the presented research was to characterize polycyclic aromatic hydrocarbons (PAHs) in indoor and outdoor air of schools. The sampling campaign was conducted during the heating season of 2011/2012. Five primary schools from various urban settings in the city of Kaunas, Lithuania. 150 daily samples of particulate and vapor phases were collected during the sampling period. The ultrasonic extractions followed by the gas chromatography and mass spectroscopy (GS/MS) analyses were used for the determination of PAHs. The concentration of total PAHs in the PM2.5 fraction ranged from 20.3 to 131.1 ng m-3, while total suspended particles (TSP) fraction contained from 19.9 to 80.3 ng m-3 of total PAHs. The vapor phase concentration of PAHs ranged from 67.2 to 372.5 ng m-3. The most abundant PAH in both phases was naphthalene. In order to define sources of indoor and outdoor PAHs several source apportionment methods were applied. The analysis revealed that emissions from motor vehicles and fuel burning for heating purposes were the major sources of PAHs in the city of Kaunas.

  18. Measurement of two-phase refrigerant liquid-vapor mass flow rate. Part 1: Venturi and void fraction meters

    SciTech Connect

    Abdul-Razzak, A.; Shoukri, M.; Chang, J.S. [McMaster Univ., Hamilton, Ontario (Canada)

    1995-12-31

    The use of a venturi meter for the measurement of refrigerant liquid-vapor mass flow rate in a horizontal pipe is presented. Various models that utilize the output of the venturi flowmeter and the measured void fraction and/or quality to calculate the two-phase mass flow rate were examined. It was found that the applicability of the various models is dependent on the quality range. When the quality is less than 50%, the use of the momentum density model provides the best accuracy. For higher qualities, the use of the homogeneous equilibrium model is recommended.

  19. Dislocation reduction of InAs nanofins prepared on Si substrate using metal-organic vapor-phase epitaxy

    PubMed Central

    2012-01-01

    InAs nanofins were prepared on a nanopatterned Si (001) substrate by metal-organic vapor-phase epitaxy. The threading dislocations, stacked on the lowest-energy-facet plane {111}, move along the SiO2 walls, resulting in a dislocation reduction, as confirmed by transmission electron microscopy. The dislocations were trapped within a thin InAs epilayer. The obtained 90-nm-wide InAs nanofins with an almost etching-pit-free surface do not require complex intermediate-layer epitaxial growth processes and large thickness typically required for conventional epitaxial growth. PMID:23176442

  20. Metal organic vapor phase epitaxy growth of single crystalline GaN on planar Si(211) substrates

    NASA Astrophysics Data System (ADS)

    Ravash, Roghaiyeh; Bläsing, Jürgen; Hempel, Thomas; Noltemeyer, Martin; Dadgar, Armin; Christen, Jürgen; Krost, Alois

    2009-12-01

    We present metal organic vapor phase epitaxy growth of polarization reduced, wurtzitic gallium nitride layers with an 18° inclination of the c-axis to the surface normal on planar Si(211) substrates. The growth of this layer is performed as c-axis oriented growth on the naturally occurring Si(111) planes of the Si(211) substrate. Cathodoluminescence measurements on a ˜1.2 ?m thick structure reveals that it has a low concentration of basal plane stacking faults and no prismatic stacking fault luminescence.

  1. Suppression of metastable-phase inclusion in N-polar (000 1 ¯) InGaN/GaN multiple quantum wells grown by metalorganic vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Shojiki, Kanako; Choi, Jung-Hun; Iwabuchi, Takuya; Usami, Noritaka; Tanikawa, Tomoyuki; Kuboya, Shigeyuki; Hanada, Takashi; Katayama, Ryuji; Matsuoka, Takashi

    2015-06-01

    The metastable zincblende (ZB) phase in N-polar (000 1 ¯) (-c-plane) InGaN/GaN multiple quantum wells (MQWs) grown by metalorganic vapor phase epitaxy is elucidated by the electron backscatter diffraction measurements. From the comparison between the -c-plane and Ga-polar (0001 ) (+c-plane), the -c-plane MQWs were found to be suffered from the severe ZB-phase inclusion, while ZB-inclusion is negligible in the +c-plane MQWs grown under the same growth conditions. The ZB-phase inclusion is a hurdle for fabricating the -c-plane light-emitting diodes because the islands with a triangular shape appeared on a surface in the ZB-phase domains. To improve the purity of stable wurtzite (WZ)-phase, the optimum conditions were investigated. The ZB-phase is dramatically eliminated with decreasing the V/III ratio and increasing the growth temperature. To obtain much-higher-quality MQWs, the thinner InGaN wells and the hydrogen introduction during GaN barriers growth were tried. Consequently, MQWs with almost pure WZ phase and with atomically smooth surface have been demonstrated.

  2. Electronic cigarettes: human health effects

    PubMed Central

    Callahan-Lyon, Priscilla

    2014-01-01

    Objective With the rapid increase in use of electronic nicotine delivery systems (ENDS), such as electronic cigarettes (e-cigarettes), users and non-users are exposed to the aerosol and product constituents. This is a review of published data on the human health effects of exposure to e-cigarettes and their components. Methods Literature searches were conducted through September 2013 using multiple electronic databases. Results Forty-four articles are included in this analysis. E-cigarette aerosols may contain propylene glycol, glycerol, flavourings, other chemicals and, usually, nicotine. Aerosolised propylene glycol and glycerol produce mouth and throat irritation and dry cough. No data on the effects of flavouring inhalation were identified. Data on short-term health effects are limited and there are no adequate data on long-term effects. Aerosol exposure may be associated with respiratory function impairment, and serum cotinine levels are similar to those in traditional cigarette smokers. The high nicotine concentrations of some products increase exposure risks for non-users, particularly children. The dangers of secondhand and thirdhand aerosol exposure have not been thoroughly evaluated. Conclusions Scientific evidence regarding the human health effects of e-cigarettes is limited. While e-cigarette aerosol may contain fewer toxicants than cigarette smoke, studies evaluating whether e-cigarettes are less harmful than cigarettes are inconclusive. Some evidence suggests that e-cigarette use may facilitate smoking cessation, but definitive data are lacking. No e-cigarette has been approved by FDA as a cessation aid. Environmental concerns and issues regarding non-user exposure exist. The health impact of e-cigarettes, for users and the public, cannot be determined with currently available data. PMID:24732161

  3. Synthesis of ultrafine particles of intermetallic compounds by the vapor-phase magnesium reduction of chloride mixtures: Part II. Nickel aluminides

    Microsoft Academic Search

    H. Y. Sohn; S. Paldey

    1998-01-01

    The new chemical synthesis process developed in this laboratory for the preparation of the fine powders of intermetallic compounds\\u000a by the vapor-phase reduction of mixtures of constituent metal chlorides by magnesium vapor, described in Part I for titanium\\u000a aluminides, was applied to the synthesis of nickel aluminide particles. NiAl, NiAl3, and Ni2Al3 were formed by reducing mixtures of NiCl2 and

  4. Vapor Phase Crystallization of Vanadium Oxide by Hydrolysis of Vanadium Oxychloride

    Microsoft Academic Search

    Humihiko Takei

    1968-01-01

    A new method of preparing single crystals of V2O5, VO2, V3O5, V2O3, and VO has been presented, which is based on the chemical decomposition of VOCl3 vapor with moisture in an inert or reducing atmosphere. In this method, V2O5 and VO2 crystallized in a whisker shape, whereas V3O5 and V2O3 in a dendritic form composed of well-developed thin platelets. Thin

  5. Method of fabricating a free-standing diamond single crystal using growth from the vapor phase

    Microsoft Academic Search

    J. B. Posthill; D. P. Malta; T. P. Humphreys; G. C. Hudson; R. E. Thomas; R. A. Rudder; R. J. Markunas

    1996-01-01

    By combining a low temperature (600 °C) chemical vapor deposition process for homoepitaxial diamond and conventional ion implantation, we have made and lifted off a synthetic diamond single crystal plate. Before growth, a type Ia C(100) crystal was exposed to a self implant of 190 keV energy and dose of 1×1016 cm?2. Homoepitaxial diamond growth conditions were used that are

  6. Experimental studies on nucleation, nanoparticle's formation and polymerization from the vapor phase

    Microsoft Academic Search

    Victor Maher Abdelsayed

    2004-01-01

    This research is divided into three major parts. In part I, the critical supersaturations required for the homogeneous nucleation of 2,2,2-trifluorothanol (TFE) vapor have been measured over a temperature range (266-296 K) using an upward thermal diffusion cloud chamber (DCC). The measured supersaturations are in agreement with the predictions of both the classical and the scaled theory of nucleation. Moreover,

  7. Vapor-phase and particulate-associated pesticides and PCB concentrations in eastern North Dakota air samples

    SciTech Connect

    Hawthorne, S.B.; Miller, D.J.; Louie, P.K.K. [Univ. of North Dakota, Grand Forks, ND (United States)] [and others

    1996-05-01

    Vapor-phase and suspended particulate (<50 {mu}m) samples were collected on polyurethane foam (PUF) and quartz fiber filters in rural North Dakota to determine the air concentrations of pesticides in an area where agriculture is a primary source of semivolatile pollutants. Samples were collected at two sites from 1992 to 1994 that were at least 0.4 km from the nearest farmed fields and known application of pesticides, and analyzed for 22 different organochlorine, triazine, and acid herbicide pesticides. Fourteen pesticides were found above the detection limits (typically <1 pg/m{sup 3}). Concentrations of polychlorinated biphenyl (PCB) congeners were much lower (<50 pg/m{sup 3} in all cases) than many of the pesticides. These results demonstrate that pesticides are among the most prevalent chlorinated semivolatile pollutants present in rural North Dakota, that significant transport of pesticides occurs both in the vapor-phase and on suspended particulate matter, and that blown soil may be a significant mechanism for introducing pesticides into surface and ground waters. 32 refs., 2 figs., 4 tabs.

  8. Phase transited and vapor-induced dual capsular system (DCS) for achieving delayed and osmotic release of cefadroxil.

    PubMed

    Philip, Anil K; Philip, Betty

    2011-10-01

    In the present study, an intestinal pH, disintegrating and non-disintegrating dual capsular system using formaldehyde vapor and phase transition technique, respectively, was developed to achieve delayed as well as improved osmotic flow for the model drug cefadroxil. Formaldehyde vapor was used to attain gastric resistance to the outer gelatin capsule, which disintegrated at the intestinal pH to give a non-disintegrating asymmetric membrane capsule (AMC). The AMC was prepared via dry phase inversion process. The effects of different formulation variables were studied based on 2³ factorial design, namely, level of osmogen, ethylcellulose, and pore former, apart from studying the effects of varying osmotic pressure, agitation intensity, and intentional defect on drug release. Scanning electron microscopy showed an outer dense non-porous and an inner lighter porous region for the prepared asymmetric membrane. Statistical test was applied for in-vitro drug release at P?>?0.05. The best formulation in the design closely corresponded to the extra design checkpoint formulation by a similarity (f?) value of 95.28. The drug release was independent of the agitation intensity and intentional defect of the film but dependent on the osmotic pressure of the dissolution medium. The release kinetics followed zero-order, and mechanism of release was Fickian diffusion. PMID:20482448

  9. Cigarette Consumption and Cigarette Smoking Prevalence Among Adults in Kansas

    PubMed Central

    Lai, Sue Min

    2015-01-01

    Introduction Recent tobacco prevention and cessation activities have focused on nonsmoking ordinances and behavioral changes, and in Kansas, the overall prevalence of cigarette smoking among adults has decreased. The objective of this study was to determine whether overall cigarette consumption (mean annual number of cigarettes smoked) in Kansas also decreased. Methods Data on cigarette smoking prevalence for 91,465 adult Kansans were obtained from the Behavioral Risk Factor Surveillance System survey for 1999 through 2010. Data on annual cigarette consumption were obtained from the 2002 and 2006 Kansas Adult Tobacco Survey and analyzed by totals, by sex, and by smoking some days or smoking every day. Linear regression was used to evaluate rate changes over time. Results Among men, but not women, cigarette smoking prevalence decreased significantly over time. The prevalence of smoking every day decreased significantly among both men and women, whereas the prevalence of smoking on some days increased significantly for women but not men. For current smokers, the mean annual number of cigarettes consumed remained the same. Conclusion The decline in overall smoking prevalence coupled with the lack of change in mean annual cigarette consumption may have resulted in a more intense exposure to cigarettes for the smoking population. The significant increase in some day use among women indicates a need for additional prevention and education activities; the impact on future lung cancer incidence rates needs further investigation. PMID:26068414

  10. Significance of vapor phase chemical reactions on CVD rates predicted by chemically frozen and local thermochemical equilibrium boundary layer theories

    NASA Technical Reports Server (NTRS)

    Gokoglu, Suleyman A.

    1988-01-01

    This paper investigates the role played by vapor-phase chemical reactions on CVD rates by comparing the results of two extreme theories developed to predict CVD mass transport rates in the absence of interfacial kinetic barrier: one based on chemically frozen boundary layer and the other based on local thermochemical equilibrium. Both theories consider laminar convective-diffusion boundary layers at high Reynolds numbers and include thermal (Soret) diffusion and variable property effects. As an example, Na2SO4 deposition was studied. It was found that gas phase reactions have no important role on Na2SO4 deposition rates and on the predictions of the theories. The implications of the predictions of the two theories to other CVD systems are discussed.

  11. Application of the Vapor-phase Multi-stage CMD Test to Characterize Contaminant Mass Discharge Associated with Volatile Organic Contaminant Sources in the Vadose Zone

    NASA Astrophysics Data System (ADS)

    Brusseau, M. L.; Mainhagu, J.; Morrison, C. N.; Carroll, K. C.

    2014-12-01

    Vapor-phase multi-stage contaminant mass discharge (CMD) tests were conducted at two field sites to measure mass discharge associated with contaminant sources located in the vadose zone. A CMD of 32 g/d was obtained for a site at which soil vapor extraction (SVE) has been in operation for approximately 6 years. The behavior exhibited for the vapor extractions conducted at this site suggests that there is unlikely to be a significant mass of non-vapor-phase contaminant (e.g., DNAPL, sorbed phase) present in the advective domains, and that most remaining mass is likely located in poorly accessible domains. Given the conditions for this site, this remaining mass is hypothesized to be associated with the low-permeability (and higher water saturation) region in the vicinity of the saturated zone and capillary fringe. This is supported by the results of a sediment-coring effort conducted prior to the CMD test. A CMD of 270 g/d was obtained for a site for which there were no prior SVE operations. The behavior exhibited for the vapor extractions conducted at this site suggest that non-vapor-phase contaminant mass (e.g., DNAPL) may be present in the advective domains. This is consistent with the results of prior characterization activities conducted at the site. Hence, the asymptotic conditions observed for this site most likely derive from a combination of rate-limited mass transfer from DNAPL (and sorbed) phases present in the advective domain as well as mass residing in lower-permeability ("non-advective") regions. The CMD values obtained from the tests were used in conjunction with a recently developed vapor-discharge tool to evaluate the impact of the measured CMDs on groundwater quality.

  12. Solid state phase transition and vapor pressure studies in ammonium nitrate-potassium nitrate binary system

    Microsoft Academic Search

    Wen-Ming Chien

    2003-01-01

    The solid-state phase transitions in ammonium nitrate (NH4NO 3) and potassium nitrate (KNO3) solid solutions and the equilibrium NH4NO3-KNO3 (AN-KN) phase diagram have been determined. The phase transitions and phase diagram were determined by using the differential scanning calorimetry (DSC) and high temperature X-ray diffractometry. Samples of several different compositions were made for these analyses in a special \\

  13. Vapor-liquid phase equilibrium in systems with multiple chemical reactions

    Microsoft Academic Search

    Sophie Ung; Michael F. Doherty

    1995-01-01

    We introduce a new set of composition variables for treating phase equilibria in multicomponent, multi-reaction systems with or without inert components present. These variables provide a way of reducing the dimensionality of the problem and simplifying the analysis. We find that reactive azeotropes occur at points of equal transformed composition in each phase, but not equal mole fraction. Therefore, phase

  14. Growth of Pb 1- xSn xTe ( x?0.12) epitaxial layers by temperature difference under controlled vapor pressure liquid-phase epitaxy

    NASA Astrophysics Data System (ADS)

    Nugraha, .; Tamura, Wataru; Itoh, Osamu; Suto, Ken; Nishizawa, Jun-ichi

    2000-10-01

    Pb 1- xSn xTe ( x?0.12) liquid-phase epitaxial layers have been grown by the temperature difference method under controlled vapor pressure (TDM-CVP) using Pb solvents on PbTe substrates at temperatures 490°C and 600°C. The grown layers are usually n-type, and the optimum Te vapor pressure where the carrier concentration becomes minimum is 3.1×10 -3> PTe>1.4×10 -3 Torr for Tg=600°C, and 3.1×10-5 >P Te>1.4×10-5 Torr for Tg=490°C. The activation energy of the optimum Te vapor pressure for Pb 1- xSn xTe ( x?0.12) is 2.38 eV, which is larger than the activation energy for PbTe, 2.12 eV. Two different types of etch pits are observed on Pb 1- xSn xTe ( x?0.12) layers. The density of the smaller size etch pits tends to become minimum at the optimum Te vapor pressure, while the larger size etch pits are dominantly observed at the vapor pressure region above the optimum vapor pressure. This tendency and lower electron mobility suggest defect aggregation taking place above the optimum vapor pressure.

  15. Molecular Competition of C 7 and C 9 n-Alkanes in Vapor and Liquid-Phase Hydroconversion over Bifunctional Pt–USY Zeolite Catalysts

    Microsoft Academic Search

    Joeri F. M. Denayer; Bruno De Jonckheere; Myriam Hloch; Guy B. Marin; Gina Vanbutsele; Johan A. Martens; Gino V. Baron

    2002-01-01

    Molecular competition effects in the hydroconversion of an equimolar heptane\\/nonane mixture were studied in liquid-phase reaction conditions in a fixed-bed reactor filled with a Pt–ultrastable-Y (USY) catalyst. Liquid-phase conditions were attained by feeding the hydrocarbon mixture with hydrogen dissolved in it at 100 bar and 230°C. Comparative vapor-phase experiments were run at 230°C, a pressure of 4.5 bar, and a

  16. A low phase noise microwave frequency synthesis for a high-performance cesium vapor cell atomic clock.

    PubMed

    François, B; Calosso, C E; Danet, J M; Boudot, R

    2014-09-01

    We report the development, absolute phase noise, and residual phase noise characterization of a 9.192?GHz microwave frequency synthesis chain devoted to be used as a local oscillator in a high-performance cesium vapor cell atomic clock based on coherent population trapping (CPT). It is based on frequency multiplication of an ultra-low phase noise 100 MHz oven-controlled quartz crystal oscillator using a nonlinear transmission line-based chain. Absolute phase noise performances of the 9.192?GHz output signal are measured to be -42, -100, -117 dB?rad(2)/Hz and -129 dB?rad(2)/Hz at 1 Hz, 100 Hz, 1 kHz, and 10 kHz offset frequencies, respectively. Compared to current results obtained in a state-of-the-art CPT-based frequency standard developed at LNE-SYRTE, this represents an improvement of 8 dB and 10 dB at f = 166 Hz and f = 10 kHz, respectively. With such performances, the expected Dick effect contribution to the atomic clock short term frequency stability is reported at a level of 6.2 × 10(-14) at 1 s integration time, that is a factor 3 higher than the atomic clock shot noise limit. Main limitations are pointed out. PMID:25273756

  17. A low phase noise microwave frequency synthesis for a high-performance cesium vapor cell atomic clock

    NASA Astrophysics Data System (ADS)

    François, B.; Calosso, C. E.; Danet, J. M.; Boudot, R.

    2014-09-01

    We report the development, absolute phase noise, and residual phase noise characterization of a 9.192 GHz microwave frequency synthesis chain devoted to be used as a local oscillator in a high-performance cesium vapor cell atomic clock based on coherent population trapping (CPT). It is based on frequency multiplication of an ultra-low phase noise 100 MHz oven-controlled quartz crystal oscillator using a nonlinear transmission line-based chain. Absolute phase noise performances of the 9.192 GHz output signal are measured to be -42, -100, -117 dB rad2/Hz and -129 dB rad2/Hz at 1 Hz, 100 Hz, 1 kHz, and 10 kHz offset frequencies, respectively. Compared to current results obtained in a state-of-the-art CPT-based frequency standard developed at LNE-SYRTE, this represents an improvement of 8 dB and 10 dB at f = 166 Hz and f = 10 kHz, respectively. With such performances, the expected Dick effect contribution to the atomic clock short term frequency stability is reported at a level of 6.2 × 10-14 at 1 s integration time, that is a factor 3 higher than the atomic clock shot noise limit. Main limitations are pointed out.

  18. Chemical evaluation of electronic cigarettes

    PubMed Central

    Cheng, Tianrong

    2014-01-01

    Objective To review the available evidence evaluating the chemicals in refill solutions, cartridges, aerosols and environmental emissions of electronic cigarettes (e-cigarettes). Methods Systematic literature searches were conducted to identify research related to e-cigarettes and chemistry using 5 reference databases and 11 search terms. The search date range was January 2007 to September 2013. The search yielded 36 articles, of which 29 were deemed relevant for analysis. Results The levels of nicotine, tobacco-specific nitrosamines (TSNAs), aldehydes, metals, volatile organic compounds (VOCs), flavours, solvent carriers and tobacco alkaloids in e-cigarette refill solutions, cartridges, aerosols and environmental emissions vary considerably. The delivery of nicotine and the release of TSNAs, aldehydes and metals are not consistent across products. Furthermore, the nicotine level listed on the labels of e-cigarette cartridges and refill solutions is often significantly different from measured values. Phenolic compounds, polycyclic aromatic hydrocarbons and drugs have also been reported in e-cigarette refill solutions, cartridges and aerosols. Varying results in particle size distributions of particular matter emissions from e-cigarettes across studies have been observed. Methods applied for the generation and chemical analyses of aerosols differ across studies. Performance characteristics of e-cigarette devices also vary across and within brands. Conclusions Additional studies based on knowledge of e-cigarette user behaviours and scientifically validated aerosol generation and chemical analysis methods would be helpful in generating reliable measures of chemical quantities. This would allow comparisons of e-cigarette aerosol and traditional smoke constituent levels and would inform an evaluation of the toxicity potential of e-cigarettes. PMID:24732157

  19. Defect reduction of SiNx embedded m-plane GaN grown by hydride vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Woo, Seohwi; Kim, Minho; So, Byeongchan; Yoo, Geunho; Jang, Jongjin; Lee, Kyuseung; Nam, Okhyun

    2014-12-01

    Nonpolar (1 0 -1 0) m-plane GaN has been grown on m-plane sapphire substrates by hydride vapor phase epitaxy (HVPE). We studied the defect reduction of m-GaN with embedded SiNx interlayers deposited by ex-situ metal organic chemical vapor deposition (MOCVD). The full-width at half-maximum values of the X-ray rocking curves for m-GaN with embedded SiNx along [1 1 -2 0]GaN and [0 0 0 1]GaN were reduced to 528 and 1427 arcs, respectively, as compared with the respective values of 947 and 3170 arcs, of m-GaN without SiNx. Cross-section transmission electron microscopy revealed that the basal stacking fault density was decreased by approximately one order to 5×104 cm-1 due to the defect blocking of the embedded SiNx. As a result, the near band edge emission intensities of the room-temperature and low-temperature photoluminescence showed approximately two-fold and four-fold improvement, respectively.

  20. The electronic cigarette. Official statement of the Spanish Society of Pneumology and Thoracic Surgery (SEPAR) on the efficacy, safety and regulation of electronic cigarettes.

    PubMed

    Jimenez Ruiz, Carlos A; Solano Reina, Segismundo; de Granda Orive, Jose Ignacio; Signes-Costa Minaya, Jaime; de Higes Martinez, Eva; Riesco Miranda, Juan Antonio; Altet Gómez, Neus; Lorza Blasco, Jose Javier; Barrueco Ferrero, Miguel; de Lucas Ramos, Pilar

    2014-08-01

    The electronic cigarette (EC) is a device formed by three basic elements: battery, atomizer and cartridge. When assembled, it looks like a cigarette. The cartridge contains different substances: propylene glycol, glycerine and, sometimes, nicotine. When the user "vapes", the battery is activated, the atomizer is heated and the liquid is drawn in and vaporized. The smoker inhales the mist produced. Various substances have been detected in this mist: formaldehyde, acetaldehyde and acrolein and some heavy metals. Although these are found in lower concentrations than in cigarettes, they may still be harmful for the human body. Several surveys show that 3-10% of smokers regularly use e-cigarettes. A randomized study has shown that the efficacy of e-cigarettes for helping smokers to quit is similar to nicotine patches. Nevertheless, the study has relevant methodological limitations and reliable conclusions cannot be deduced. This report sets down the Position Statement of the Spanish Society of Pulmonology and Thoracic Surgery (SEPAR) on the efficacy and safety of e-cigarettes. This statement declares that e-cigarettes should be regulated as medicinal products. PMID:24684764

  1. Cytotoxicity of chronic exposure to 4 cigarette smoke condensates in 2 cell lines.

    PubMed

    Wang, Honggang; Word, Beverly; Lyn-Cook, Lascelles; Yang, Maocheng; Hammons, George; Lyn-Cook, Beverly

    2015-01-01

    Tobacco use is the leading preventable cause of death. The cytotoxicity of cigarette smoke condensate (CSC), the particulate fraction of cigarette smoke without the vapor phase, has mostly been tested in short-term in vitro studies lasting from a few hours to a few days. Here, we assessed the toxicity of CSCs from 2 reference cigarettes, 3R4F and CM6, using a primary human small airway epithelial (PSAE) cell line by quantifying adenosine 5'-triphosphate (ATP), 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxy-methoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS), total glutathione (reduced glutathione [GSH] + oxidized glutathione [GSSG]), and lactate dehydrogenase (LDH) release over the course of 28 days. The CSCs, 0.3 to 10 ?g/mL, promoted cell proliferation at 120 hours of exposure, but demonstrated cytotoxicity at days 14 and 28. Interestingly, CSCs, 0.3 to 3 ?g/mL, showed a cell death effect at day 14 but induced cell proliferation at day 28. Consistently, transformation associated with morphological changes began by day 14 and the transformed cells grew dramatically at day 28. The LDH assay appeared to be sensitive for assessing early cell damage, whereas the ATP, MTS, and GSH assays were more suitable for determining later stage CSCs-induced cytotoxicity. The ATP assay showed greater sensitivity than the MTS and GSH assays. We also assessed the toxicity of CSCs in an human Telomerase Reverse Transcriptase (hTERT)-immortalized Barrett esophagus cell line (CP-C). The CP-C cells demonstrated dose- and time-dependent cytotoxicity over the course of 28 days but displayed higher resistance to CSCs than PSAE cells. This study demonstrates that CSCs cause cytotoxicity and induce transformation related to cell resistance and cell invasion properties. PMID:25800266

  2. Condensed phase conversion and growth of nanorods instead of from vapor

    DOEpatents

    Geohegan, David B.; Seals, Roland D.; Puretzky, Alex A.; Fan, Xudong

    2005-08-02

    Compositions, systems and methods are described for condensed phase conversion and growth of nanorods and other materials. A method includes providing a condensed phase matrix material; and activating the condensed phase matrix material to produce a plurality of nanorods by condensed phase conversion and growth from the condensed chase matrix material instead of from vacor. The compositions are very strong. The compositions and methods provide advantages because they allow (1) formation rates of nanostructures necessary for reasonable production rates, and (2) the near net shaped production of component structures.

  3. Vacuum distillation/vapor filtration water recovery, phases 1 and 2

    NASA Technical Reports Server (NTRS)

    Honegger, R. J.; Remus, G. A.; Krug, E. K.

    1973-01-01

    The research is reported on the development of an evaporator for vacuum distillation/vapor filtration VD/VF water reclamation system for use on manned space flights. The design, fabrication, and tests of a six-man evaporator are described. It is concluded that: (1) A condenser with an internal rotating impeller and coolant surfaces directly opposite the condensing surfaces is an effective condenser. (2) The VD/VF evaporator, catalyst unit and condenser function satisfactorily based on thermal, mechanical and recovery performance during a 145-hour evaluation test. (3) The quality of recovered water, as measured by analyses for total organic carbon, pH, conductivity, turbidity, and viable bacteria density was within established limits for potability.

  4. A Gas Lift Bioreactor for Removal of Contaminants from the Vapor Phase

    PubMed Central

    Ensley, B. D.; Kurisko, P. R.

    1994-01-01

    The cometabolic degradation of trichloroethylene (TCE) as a vapor by two aromatic-metabolizing pseudomonads was evaluated in an airlift reactor. These microorganisms were able to degrade 90 to 95% of TCE in air at concentrations at the reactor inlet of 300 to 4,000 ?g/liter. Although exposure of the cells to high inlet concentrations of TCE (4 mg/liter) caused a decline in enzyme-specific activity and TCE removal efficiency, this loss in activity could be prevented or delayed by increasing the rate of cosubstrate addition. Under the appropriate operating conditions, the microorganisms were able to degrade even high concentrations of TCE and activity of the cells in the reactor could be maintained for periods of at least 2 weeks. PMID:16349158

  5. Amorphous and crystalline aerosol particles interacting with water vapor - Part 1: Microstructure, phase transitions, hygroscopic growth and kinetic limitations

    NASA Astrophysics Data System (ADS)

    Mikhailov, E.; Vlasenko, S.; Martin, S. T.; Koop, T.; Pöschl, U.

    2009-03-01

    Interactions with water are crucial for the properties, transformation and climate effects of atmospheric aerosols. Here we outline characteristic features and differences in the interaction of amorphous and crystalline aerosol particles with water vapor. Using a hygroscopicity tandem differential mobility analyzer (H-TDMA), we performed hydration, dehydration and cyclic hydration&dehydration experiments with aerosol particles composed of levoglucosan, oxalic acid and ammonium sulfate (diameters ~100-200 nm, relative uncertainties <0.4%, relative humidities <5% to 95% at 298 K). The measurements and accompanying Köhler model calculations provide new insights into particle microstructure, surface adsorption, bulk absorption, phase transitions and hygroscopic growth. The results of these and related investigations lead to the following main conclusions: 1. Many organic substances (including carboxylic acids, carbohydrates and proteins) tend to form amorphous rather than crystalline phases upon drying of aqueous solution droplets. Depending on viscosity and microstructure, the amorphous phases can be classified as glasses, rubbers, gels or viscous liquids. 2. Amorphous organic substances tend to absorb water vapor and undergo gradual deliquescence and hygroscopic growth at much lower relative humidity than their crystalline counterparts. 3. In the course of hydration and dehydration, certain organic substances can form rubber- or gel-like structures (supra-molecular networks) and undergo stepwise transitions between swollen and collapsed network structures. 4. Organic gels or (semi-)solid amorphous shells (glassy, rubbery, ultra-viscous) with low molecular diffusivity can kinetically limit the uptake and release of water by submicron aerosol particles on (multi-)second time scales, which may influence the hygroscopic growth and activation of aerosol particles as cloud condensation nuclei (CCN) and ice nuclei (IN). 5. The shape and porosity of amorphous and crystalline particles formed upon dehydration of aqueous solution droplets depend on chemical composition and drying conditions. The apparent volume void fractions of particles with highly porous structures can range up to ~50% or more (xerogels, aerogels). Void fractions as well as residual water in dried aerosol particles that are not water-free (due to kinetic limitations of drying or stable hydrate formation) should be taken into account in Köhler model calculations of hygroscopic growth and CCN activation. 6. For efficient description of water uptake and phase transitions of amorphous and crystalline organic and inorganic aerosol particles and particle components, we propose not to limit the terms deliquescence and efflorescence to equilibrium phase transitions of crystalline substances interacting with water vapor. Instead we propose the following generalized definitions: Deliquescence is the transformation of a (semi-)solid substance into a liquid aqueous solution, whereby water is absorbed from the gas phase ("liquefaction upon humidification/hydration"). Efflorescence is the transformation of a substance from a liquid aqueous solution into a (semi-)solid phase, whereby water is evaporated ("solidification upon drying/dehydration"). According to these definitions, individual components as well as entire aerosol particles can undergo gradual or prompt, partial or full deliquescence or efflorescence.

  6. Cigarette Smoke Induces Cellular Senescence

    Microsoft Academic Search

    Toru Nyunoya; Martha M. Monick; Aloysius Klingelhutz; Timur O. Yarovinsky; Jeffrey R. Cagley; Gary W. Hunninghake

    2006-01-01

    Chronicobstructivepulmonary disease(COPD)isthefourthleading cause of death in the United States, and cigarette smoking is the major risk factor for COPD. Fibroblasts play an important role in repair and lung homeostasis. Recent studies have demonstrated a reduced growth rate for lung fibroblasts in patients with COPD. In this study we examined the effect of cigarette smoke extract (CSE) on fibroblast proliferative capacity.

  7. Behavior of GaN nanoneedles grown by using hydride vapor phase epitaxy for different growth times

    NASA Astrophysics Data System (ADS)

    Shin, Min Jeong; Gwon, Dong-Oh; Ahn, Hyung Soo; Yi, Sam Nyung; Jeon, In-Jun; Yu, Young-Moon

    2015-04-01

    Gallium nitride (GaN) nanoneedles were synthesized by using the hydride vapor phase epitaxy method at various growth temperatures and times under a HCl:NH3 flow ratio of 1:38. The morphology of GaN nanostructures varied according to the growth temperatures, and nanoneedles were formed at 640°C temperature zone. Further, their heights and diameters increased with increasing growth time whereas the stems of the nanoneedles coalesced. X-ray diffraction patterns showed that the GaN nanoneedles were orientated along the [0001] direction and underwent biaxial compressive stress. Also, the Raman spectra exhibited the smallest compressive strain in the sample grown for 60 min compared to the other samples.

  8. Nucleation and growth of Ag nanoparticles on amorphous carbon surface from vapor phase formed by vacuum evaporation

    NASA Astrophysics Data System (ADS)

    Gromov, Dmitry G.; Pavlova, Lydia M.; Savitsky, Andrey I.; Trifonov, Alexey Yu.

    2015-03-01

    We present the results of experimental study of Ag nanoparticle arrays on thin film of amorphous carbon. The arrays were formed by means of vapor phase deposition on non-heated substrate. The investigation was carried out using TEM technique. It has been found that the size of the particles and their surface density significantly depend on the amount of condensing substance. In particular, increasing the portion of evaporating Ag material from 5.1 to 47.5 mg results in drastic reduction of surface density of the particles from ~8,000 to ~40 µm-2, whereas the predominant particle size changes from ~7 to ~60 nm. We present phenomenological description of the process: directed flow of silver atoms to growing Ag particles takes place during condensation.

  9. Homoepitaxial growth of ZnO by metalorganic vapor phase epitaxy in two-dimensional growth mode

    NASA Astrophysics Data System (ADS)

    Heinze, S.; Krtschil, A.; Bläsing, J.; Hempel, T.; Veit, P.; Dadgar, A.; Christen, J.; Krost, A.

    2007-10-01

    We describe the successful homoepitaxial growth of ZnO layers on oxygen-face ZnO substrates by metalorganic vapor-phase epitaxy in two-dimensional growth mode. In detail, we discuss the impact of the oxygen/zinc precursor ratio using N 2O and O 2 as oxygen precursors, growth temperature, and reactor pressure on structural properties and surface morphology as obtained by X-ray diffraction, field emission scanning electron microscopy, and atomic force microscopy measurements. Optimizing the growth parameters leads to smooth layers, ending up in a mirror-like surface grown in two-dimensional growth mode. The structural layer properties are found to be significantly governed by the substrate properties.

  10. Aromatization of n-hexane by platinum-containing molecular sieves. 1. Catalyst preparation by the vapor phase impregnation method

    SciTech Connect

    Suk Bong Hong; Mielczarski, E.; Davis, M.E. (Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States))

    1992-03-01

    A vapor phase impregnation method with Pt(acac){sub 2} has been developed and used to load Pt into aluminosilicate (KL, BaKL, NaY, CsNaY, cubic and hexagonal polytypes of faujasite, ZSM-12, and SSZ-24) and aluminophosphate (AlPO{sub 4}-5 and VPI-5) molecular sieves. Pt-containing molecular sieves are characterized by XRD,TPD, elemental analysis, {sup 13}C MAS NMR, TEM, and H{sub 2} chemisorption. {sup 13}C MAS NMR, TEM, and H{sub 2} chemisorption measurements reveal that Pt can be loaded into the micropores of molecular sieves with both charged and neutral frameworks. Pt impregnated into zeolites and aluminophosphates by this method does not migrate to the exterior surface of the molecular sieve catalysts at n-hexane aromatization reaction conditions of atmospheric pressure and temperatures between 460 and 510 C.

  11. Testing of Performance of a Scroll Pump in Support of Improved Vapor Phase Catalytic Ammonia Removal (VPCAR) Mass Reduction

    NASA Technical Reports Server (NTRS)

    Nahra, Henry K.; Kraft, Thomas G.; Yee, Glenda F.; Jankovsky, Amy L.; Flynn, Michael

    2006-01-01

    This paper describes the results of ground testing of a scroll pump with a potential of being a substitute for the current vacuum pump of the Vapor Phase Catalytic Ammonia Reduction (VPCAR). Assessments of the pressure-time, pump-down time, pump power and the pump noise were made for three configurations of the pump the first of which was without the gas ballast, the second with the gas ballast installed but not operating and the third with the gas ballast operating. The tested scroll pump exhibited optimum characteristics given its mass and power requirements. The pump down time required to reach a pressure of 50 Torr ranged from 60 minutes without the ballast to about 120 minutes with the gas ballast operational. The noise emission and the pump power were assessed in this paper as well.

  12. Thick InGaN Growth by Metal Organic Vapor Phase Epitaxy with Sputtered InGaN Buffer Layer

    NASA Astrophysics Data System (ADS)

    Ohata, Toshiya; Honda, Yoshio; Yamaguchi, Masahito; Amano, Hiroshi

    2013-08-01

    A thick InGaN film was grown on a sapphire substrate by metal organic vapor phase epitaxy using a thin buffer layer of sputter-deposited InGaN. A thick film of highly luminescent In0.2Ga0.8N can be successfully grown at a rate as high as 2 µm/h. The crystal quality of InGaN grown on the sputter-deposited InGaN buffer layer was better than that of InGaN grown directly on the sapphire substrate. The sample showed n-type conduction with a carrier concentration and mobility of 5×1018 cm-3 and 3 cm2/(V.s), respectively.

  13. Optical detection of growth oscillations from high vacuum up to low-pressure metalorganic vapor phase epitaxy like conditions

    NASA Astrophysics Data System (ADS)

    Deppert, K.; Jönsson, J.; Samuelson, L.

    1992-09-01

    We report optical, real-time detection of growth oscillations for pressures up to low-pressure metalorganic vapor phase epitaxy (LP-MOVPE) like conditions. The measurements were performed using the reflectance difference technique during epitaxial growth of GaAs in a vacuum chemical epitaxy (VCE) chamber in which the LP-MOVPE conditions were obtained by adding hydrogen. Growth oscillations could still be obtained over a wide range of V/III ratios at pressures in the mbar range. Under LP-MOVPE conditions we could observe oscillation amplitudes comparable to those found under VCE conditions. Furthermore, the occurrence of oscillations when hydrogen is introduced shows that the layer-by-layer growth is not affected by the presence of hydrogen. These results seem to open the way for the in situ detection of growth oscillations even in conventional MOVPE systems.

  14. Investigation of Growth Mechanism for InGaN by Metal-Organic Vapor Phase Epitaxy Using Computational Fluid Simulation

    NASA Astrophysics Data System (ADS)

    Deura, Momoko; Ichinohe, Fumitaka; Arai, Yu; Shiohama, Kenichi; Hirako, Akira; Ohkawa, Kazuhiro

    2013-08-01

    We investigated the mechanism of metal-organic vapor phase epitaxy (MOVPE) growth for InGaN by comparing experimental and simulation results. The simulation results showed a similar trend to the experimental results. Therefore, the simulation system can be used to speculate on physical and chemical phenomena through the behavior of precursors. InGaN growth is largely affected by the amounts of both trimethylindium (TMIn) and NH3 supplied. This is because InN growth is dependent on the amount of NH2 physisorbed on a surface, which is generated by NH3. Moreover, the decomposition of crystallized InN and the desorption of these decomposed precursors of InN during growth cannot be ignored.

  15. Preparation of mesoporous nanofibers by vapor phase synthesis: control of mesopore structures with the aid of co-surfactants

    NASA Astrophysics Data System (ADS)

    Min, Sa Hoon; Bae, Joonwon; Jang, Jyongsik; Lee, Kyung Jin

    2013-06-01

    Mesoporous nanofibers (MSNFs) can be fabricated in the pores of anodic aluminum oxide (AAO) membrane using diverse methods. Among them vapor phase synthesis (VPS) provides several advantages over sol-gel or evaporation-induced self-assembly (EISA) based methods. One powerful advantage is that we can employ multiple surfactants as structural directing agents (SDAs) simultaneously. By adopting diverse pairs of SDAs, we can control the mesopore structures, i.e. pore size, surface area, and even the morphology of mesostructures. Here, we used F127 as a main SDA, which is relatively robust (thus, difficult to change the mesopore structures), and added a series of cationic co-surfactants to observe the systematical changes in their mesostructure with respect to the chain length of the co-surfactant.

  16. Preparation of mesoporous nanofibers by vapor phase synthesis: control of mesopore structures with the aid of co-surfactants.

    PubMed

    Min, Sa Hoon; Bae, Joonwon; Jang, Jyongsik; Lee, Kyung Jin

    2013-06-28

    Mesoporous nanofibers (MSNFs) can be fabricated in the pores of anodic aluminum oxide (AAO) membrane using diverse methods. Among them vapor phase synthesis (VPS) provides several advantages over sol-gel or evaporation-induced self-assembly (EISA) based methods. One powerful advantage is that we can employ multiple surfactants as structural directing agents (SDAs) simultaneously. By adopting diverse pairs of SDAs, we can control the mesopore structures, i.e. pore size, surface area, and even the morphology of mesostructures. Here, we used F127 as a main SDA, which is relatively robust (thus, difficult to change the mesopore structures), and added a series of cationic co-surfactants to observe the systematical changes in their mesostructure with respect to the chain length of the co-surfactant. PMID:23723185

  17. Using of sonochemically prepared components for vapor phase growing of SbI3.3S8.

    PubMed

    Nowak, M; Kotyczka-Mora?ska, M; Szperlich, P; Bober, ?; Jesionek, M; Kepi?ska, M; Stróz, D; Kusz, J; Szala, J; Moskal, G; Rzycho?, T; M?y?czak, J; Kopczy?ski, K

    2010-06-01

    The using of sonochemically prepared components for growth of SbI(3).3S(8) single crystals from the vapor phase is presented for the first time. The good optical quality of the obtained crystals is important because this material is valuable for optoelectronics due to its non-linear optical properties. The products were characterized by using techniques such as X-ray crystallography, powder X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis, high-resolution transmission electron microscopy, selected area electron diffraction, optical diffuse reflection spectroscopy and optical transmittance spectroscopy. The direct and indirect forbidden energy gaps of SbI(3).3S(8) illuminated with plane polarized light with electric field parallel and perpendicular to the c-axis of the crystal have been determined. The second harmonic generation of light in the grown crystals was observed. PMID:20171922

  18. Increased sulfur tolerance of Pt/KL catalysts prepared by vapor-phase impregnation and containing a Tm promoter

    SciTech Connect

    Jacobs, G.; Ghadiali, F.; Pisanu, A.; Padro, C.L.; Borgna, A.; Alvarez, W.E.; Resasco, D.E.

    2000-04-01

    Tm-containing Pt/KL catalysts were prepared by a variety of techniques, including incipient wetness impregnation (IWI), ion exchange (IE), and vapor-phase impregnation (VPI) methods. The Pt morphology resulting from the addition of Tm and Pt sequentially, using the VPI method, was found to yield the greatest enhancement to the aromatization performance of the Pt/KL catalysts studied. The presence of Tm in the sequential VPI Pt/Tm/KL catalyst resulted reproducibly in a catalyst with higher Pt dispersion than that in an unpromoted VPI catalyst, as determined by EXAFS analysis and DRIFTS of adsorbed CO. VPI catalysts give more finely dispersed Pt clusters than either conventional IWI or IE methods. From TPO of poisoned catalysts, Tm was also found to act as a getter for sulfur, so it delays the poisoning of Pt under sulfur-containing feeds, as further evidenced by reaction studies. In addition, the initial activity of the Tm-promoted VPI catalysts was found to be higher than that of the unpromoted Pt/KL VPI catalysts, suggesting that Tm may directly modify Pt or even participate in accelerating the aromatization reaction. The amount and method of incorporation of Tm were found to be critical to the morphology of the Pt clusters and, subsequently, to catalyst performance under sulfur-free and sulfur-poisoned reaction conditions. While the sequential vapor-phase impregnation method with a small amount of Tm (0.15%) yielded a catalyst with improved catalytic properties, some of the other methods such as coimpregnation of Pt and Tm were found to hinder the dispersion of Pt. This may cause the blocking of the L-zeolite channels, as demonstrated by DRIFTS of adsorbed CO, and a higher deactivation rate in the reaction

  19. Vaporization as a Smokeless Cannabis Delivery System: A Pilot Study

    Microsoft Academic Search

    D I Abrams; H P Vizoso; S B Shade; C Jay; M E Kelly; N L Benowitz; DI Abrams

    2007-01-01

    Although cannabis may have potential therapeutic value, inhalation of a combustion product is an undesirable delivery system. The aim of the study was to investigate vaporization using the Volcano® device as an alternative means of delivery of inhaled Cannabis sativa. Eighteen healthy inpatient subjects enrolled to compare the delivery of cannabinoids by vaporization to marijuana smoked in a standard cigarette.

  20. Decreased respiratory symptoms in cannabis users who vaporize

    Microsoft Academic Search

    Mitch Earleywine; Sara Smucker Barnwell

    2007-01-01

    Cannabis smoking can create respiratory problems. Vaporizers heat cannabis to release active cannabinoids, but remain cool enough to avoid the smoke and toxins associated with combustion. Vaporized cannabis should create fewer respiratory symptoms than smoked cannabis. We examined self-reported respiratory symptoms in participants who ranged in cigarette and cannabis use. Data from a large Internet sample revealed that the use

  1. Overview: MURI Center on spectroscopic and time domain detection of trace explosives in condensed and vapor phases

    NASA Astrophysics Data System (ADS)

    Spicer, James B.; Dagdigian, Paul; Osiander, Robert; Miragliotta, Joseph A.; Zhang, Xi-Cheng; Kersting, Roland; Crosley, David R.; Hanson, Ronald K.; Jeffries, Jay

    2003-09-01

    The research center established by Army Research Office under the Multidisciplinary University Research Initiative program pursues a multidisciplinary approach to investigate and advance the use of complementary analytical techniques for sensing of explosives and/or explosive-related compounds as they occur in the environment. The techniques being investigated include Terahertz (THz) imaging and spectroscopy, Laser-Induced Breakdown Spectroscopy (LIBS), Cavity Ring Down Spectroscopy (CRDS) and Resonance Enhanced Multiphoton Ionization (REMPI). This suite of techniques encompasses a diversity of sensing approaches that can be applied to detection of explosives in condensed phases such as adsorbed species in soil or can be used for vapor phase detection above the source. Some techniques allow for remote detection while others have highly specific and sensitive analysis capabilities. This program is addressing a range of fundamental, technical issues associated with trace detection of explosive related compounds using these techniques. For example, while both LIBS and THz can be used to carry-out remote analysis of condensed phase analyte from a distance in excess several meters, the sensitivities of these techniques to surface adsorbed explosive-related compounds are not currently known. In current implementations, both CRDS and REMPI require sample collection techniques that have not been optimized for environmental applications. Early program elements will pursue the fundamental advances required for these techniques including signature identification for explosive-related compounds/interferents and trace analyte extraction. Later program tasks will explore simultaneous application of two or more techniques to assess the benefits of sensor fusion.

  2. Enhanced quality thin film Cu(In,Ga)Se[sub 2] for semiconductor device applications by vapor-phase recrystallization

    DOEpatents

    Tuttle, J.R.; Contreras, M.A.; Noufi, R.; Albin, D.S.

    1994-10-18

    Enhanced quality thin films of Cu[sub w](In,Ga[sub y])Se[sub z] for semiconductor device applications are fabricated by initially forming a Cu-rich, phase-separated compound mixture comprising Cu(In,Ga):Cu[sub x]Se on a substrate to form a large-grain precursor and then converting the excess Cu[sub x]Se to Cu(In,Ga)Se[sub 2] by exposing it to an activity of In and/or Ga, either in vapor In and/or Ga form or in solid (In,Ga)[sub y]Se[sub z]. Alternatively, the conversion can be made by sequential deposition of In and/or Ga and Se onto the phase-separated precursor. The conversion process is preferably performed in the temperature range of about 300--600 C, where the Cu(In,Ga)Se[sub 2] remains solid, while the excess Cu[sub x]Se is in a liquid flux. The characteristic of the resulting Cu[sub w](In,Ga)[sub y]Se[sub z] can be controlled by the temperature. Higher temperatures, such as 500--600 C, result in a nearly stoichiometric Cu(In,Ga)Se[sub 2], whereas lower temperatures, such as 300--400 C, result in a more Cu-poor compound, such as the Cu[sub z](In,Ga)[sub 4]Se[sub 7] phase. 7 figs.

  3. Enhanced quality thin film Cu(In,Ga)Se.sub.2 for semiconductor device applications by vapor-phase recrystallization

    DOEpatents

    Tuttle, John R. (Denver, CO); Contreras, Miguel A. (Golden, CO); Noufi, Rommel (Golden, CO); Albin, David S. (Denver, CO)

    1994-01-01

    Enhanced quality thin films of Cu.sub.w (In,Ga.sub.y)Se.sub.z for semiconductor device applications are fabricated by initially forming a Cu-rich, phase-separated compound mixture comprising Cu(In,Ga):Cu.sub.x Se on a substrate to form a large-grain precursor and then converting the excess Cu.sub.x Se to Cu(In,Ga)Se.sub.2 by exposing it to an activity of In and/or Ga, either in vapor In and/or Ga form or in solid (In,Ga).sub.y Se.sub.z. Alternatively, the conversion can be made by sequential deposition of In and/or Ga and Se onto the phase-separated precursor. The conversion process is preferably performed in the temperature range of about 300.degree.-600.degree. C., where the Cu(In,Ga)Se.sub.2 remains solid, while the excess Cu.sub.x Se is in a liquid flux. The characteristic of the resulting Cu.sub.w (In,Ga).sub.y Se.sub.z can be controlled by the temperature. Higher temperatures, such as 500.degree.-600.degree. C., result in a nearly stoichiometric Cu(In,Ga)Se.sub.2, whereas lower temperatures, such as 300.degree.-400.degree. C., result in a more Cu-poor compound, such as the Cu.sub.z (In,Ga).sub.4 Se.sub.7 phase.

  4. Real-time acoustic sensing and control of metalorganic chemical vapor deposition precursor concentrations delivered from solid phase sources

    E-print Network

    Rubloff, Gary W.

    Real-time acoustic sensing and control of metalorganic chemical vapor deposition precursor III­V and II­VI optoelectronic compound semiconductors deposited by metalorganic chemical vapor and closed loop control of binary gas mixture compositions delivered from low vapor pressure metalorganic

  5. Utility of the mouse dermal promotion assay in comparing the tumorigenic potential of cigarette mainstream smoke

    Microsoft Academic Search

    Carr J. Smith; Thomas A. Perfetti; Rajni Garg; Corwin Hansch

    2006-01-01

    The International Agency for Research on Cancer (IARC) has classified a number of the chemical constituents reported in cigarette mainstream smoke (MS) as carcinogens. In the international literature, 81 IARC classified carcinogens have been reported historically in MS. Cigarette smoke is a complex aerosol of minute liquid droplets (termed the particulate phase) suspended within a mixture of gases (CO2, CO,

  6. Determination of vapor-phase carbonyls by high-pressure liquid chromatography

    SciTech Connect

    Maskarinec, M.P.; Manning, D.L.; Oldham, P.

    1981-01-01

    Methods have been developed for the trapping and quantitative analysis of low molecular weight carbonyls in complex gas phase mixtures. Formaldehyde, acetaldehyde, acrolein, and acetone are separated as the 2-4-dinitrophenylhydrazones with a sensitivity of less than 10 ppB. The separation can be done on a variety of commercial C/sub 18/ reverse-phase columns. 4 figures, 1 table.

  7. Fundamental studies of thermal transport and liquid-vapor phase change using microscale diagnostic techniques

    Microsoft Academic Search

    Benjamin J Jones

    2010-01-01

    Fundamental studies of thermal transport and fluid flow in single-phase and two-phase systems are conducted using microscale diagnostic techniques. An infrared micro-particle image velocimetry technique is extended to the study of fluid flows in a low signal-to-noise ratio environment. Measurements of flow distribution in a microchannel heat sink are conducted with this technique. It was concluded that careful manifold design

  8. Gas-phase temperature measurement in the vaporizing spray of a gasoline direct-injection injector by use of pure rotational coherent anti-Stokes Raman scattering

    NASA Astrophysics Data System (ADS)

    Beyrau, Frank; Bräuer, Andreas; Seeger, Thomas; Leipertz, Alfred

    2004-02-01

    Pure rotational coherent anti-Stokes Raman spectroscopy is applied for quantitative gas-phase temperature measurements in the vaporizing spray of an automotive fuel injector. Interferences from elastically scattered stray light are greatly reduced by use of a polarization technique and spectral filtering in a double monochromator. The applicability of this technique to probing low-temperature sprays is successfully demonstrated.

  9. Synthesis of a zeolitic thin layer by a vapor-phase transport method: appearance of a preferential orientation of MFI zeolite

    Microsoft Academic Search

    Eiichi Kikuchi; Kazuhiko Yamashita; Sachioko Hiromoto; Korekazu Ueyama; Masahiko Matsukata

    1997-01-01

    Zeolitic membranes were synthesized on a porous alumina support by the vapor-phase transport method using one of two alumina sources: aluminum sulfate and sodium aluminate. By choosing the appropriate period and temperature for drying the aluminosilicate gel on the alumina support, MOR, FER and MFI could be synthesized. MOR was formed when the water content in the dry gel was

  10. This paper presents the model for pattern formation in the course of thermodynamically stable and unstable crystal growth from vapor phase, which is in uenced by rapid spatio-

    E-print Network

    Khenner, Mikhail

    stable and unstable crystal growth from vapor phase, which is in uenced by rapid spatio- temporal of spatiotemporal chaos as the growth rate increases. INTRODUCTION Recent experimental work done in the group crystal surfaces structures are formed by the combined action of the deposition, faceting instability

  11. SIMULTANEOUS QUANTIFICATION OF JASMONIC ACID AND SALICYLIC ACID IN PLANTS BY VAPOR PHASE EXTRACTION AND GAS CHROMATOGRAPHY-CHEMICAL IONIZATION-MASS SPECTROMETRY

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Jasmonic acid and salicylic acid represent important signaling compounds in plant defensive responses against other organisms. Here, we present a new method for the easy, sensitive and reproducible quantification of both compounds by vapor phase extraction and gas chromatography-positive ion chemic...

  12. Evolution of microstructure and dislocation dynamics in InxGa1 xP graded buffers grown on GaP by metalorganic vapor phase

    E-print Network

    on GaP (InxGa1 xP/GaP) by metalorganic vapor phase epitaxy. Transmission electron microscopy- cessible to GaN-based light emitting diode LED and laser diode technologies. GaP also has nearly twice the current transparen

  13. 27 CFR 41.35 - Cigarette tubes.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Cigarette tubes. 41.35 Section 41.35 Alcohol...TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Taxes Tax Rates § 41.35 Cigarette tubes. Cigarette tubes are taxed at...

  14. 27 CFR 41.35 - Cigarette tubes.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Cigarette tubes. 41.35 Section 41.35 Alcohol...TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Taxes Tax Rates § 41.35 Cigarette tubes. Cigarette tubes are taxed at...

  15. 27 CFR 41.35 - Cigarette tubes.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Cigarette tubes. 41.35 Section 41.35 Alcohol...TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Taxes Tax Rates § 41.35 Cigarette tubes. Cigarette tubes are taxed at...

  16. 27 CFR 41.35 - Cigarette tubes.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2011-04-01 true Cigarette tubes. 41.35 Section 41.35 Alcohol...TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Taxes Tax Rates § 41.35 Cigarette tubes. Cigarette tubes are taxed at...

  17. 27 CFR 41.35 - Cigarette tubes.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Cigarette tubes. 41.35 Section 41.35 Alcohol...TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Taxes Tax Rates § 41.35 Cigarette tubes. Cigarette tubes are taxed at...

  18. Functional Analysis and Treatment of Cigarette Pica.

    ERIC Educational Resources Information Center

    Piazza, Cathleen C.; And Others

    1996-01-01

    This study of an adolescent with mental retardation and autism found that pica of cigarette butts was maintained in a condition with no social consequences when cigarettes contained nicotine but not when cigarettes contained herbs without nicotine. A procedure based on stimulus control, which reduced cigarette consumption to zero, is described.…

  19. Metalorganic vapor phase epitaxy growth of ternary tetradymite Bi2Te3-xSex compounds

    NASA Astrophysics Data System (ADS)

    Kuznetsov, P. I.; Yakushcheva, G. G.; Luzanov, V. A.; Temiryazev, A. G.; Shchamkhalova, B. S.; Jitov, V. A.; Sizov, V. E.

    2015-01-01

    We report on a metal organic vapor epitaxy (MOVPE) of Bi2Te3-xSex films over the entire range of compositions (0 ? x ? 3) for the first time. The films were grown on Al2O3(0001) substrates at 465 °C using trimethylbismuth (Bi2Me3), diethyltellurium (Et2Te) and diisopropylselenium (iPro2Se) as metalorganic sources. To realize the 2D growth mode and to grow films with flat surfaces and high crystalline quality, a thin ZnTe buffer layer was used. As-grown films were studied using optical and AFM microscopy techniques and X-ray diffraction. It was found that under steady growth conditions the composition of Bi2Te3-xSex films strongly depends on the film thickness. But a high rate of interdiffusion of chalcogens at the growth temperature rapidly leads to a homogeneous composition of the film in the growth direction. Dependence of the intensity of X-ray reflection (0012) on the composition of Bi2Te3-xSex films x has extremes near x=1 (Bi2Te2 Se) and x=2 (Bi2Se2 Te). The AFM micrographs and profiles show large (above 2 ?m) triangle-shaped atomically flat terraces with step height of a quintuple layer (0.90 nm) of the tetradymite-type compounds. The electronic properties of the grown films have been characterized via four probe magnetotransport measurements.

  20. Involvement of NF-?B and muscle specific E3 ubiquitin ligase MuRF1 in cigarette smoke-induced catabolism in C2 myotubes.

    PubMed

    Kaisari, Sharon; Rom, Oren; Aizenbud, Dror; Reznick, Abraham Z

    2013-01-01

    Cigarette smoking has been identified as a risk factor for muscular damage and sarcopenia, the age-related loss of muscle mass and strength in old age. Cigarette smoke (CS)-induced oxidative stress and p38 MAPK activation have been shown to be the main cellular mechanisms leading to skeletal muscle catabolism. In order to investigate the involvement of NF-?B as another possible cellular mechanism by which CS promotes muscle catabolism, C2 myotubes, from an in vitro skeletal muscle cell line, were exposed to different time periods of whole vapor phase CS in the presence or absence of NF-?B inhibitor, IMD-0354. The CS-induced reduction in diameter of myotubes and time-dependent degradation of the main contractile protein myosin heavy chain were abolished by NF-?B inhibition. Also, C2 exposure to CS resulted in I?B-? degradation and NF-?B activation, which led to upregulation of the muscle specific E3 ubiquitin ligase MuRF1, but not MAFbx/atrogin-1. In conclusion, our results demonstrate that vapor phase CS exposure to skeletal myotubes triggers NF-?B activation leading to skeletal muscle cell damage and breakdown of muscle proteins mediated by muscle specific E3 ubiquitin ligase MuRF1. Our findings provide another possible molecular mechanism for the catabolic effects of CS in skeletal muscle. PMID:23835952

  1. Youths' understandings of cigarette advertisements.

    PubMed

    Freeman, Dan; Brucks, Merrie; Wallendorf, Melanie; Boland, Wendy

    2009-01-01

    This study addresses two questions: (1) when youths are exposed to advertisements for cigarettes, do they primarily see advertisements for brands or products, and (2) is there a relationship between youths' understandings of cigarette advertisements and their susceptibility to smoking? A sample of 271 participants ranging in age from 7 to 12 viewed a series of print advertisements that included cigarette and non-tobacco-related ads. While viewing each ad, participants were asked to indicate what they thought the advertisement was trying to sell. Responses were coded into one of three categories reflecting important differences in participants' comprehension of each advertisement - no understanding, product category understanding, or brand understanding. Results show that youths typically understand the type of product an advertisement is promoting; however, the levels of brand understanding observed for cigarette advertisements were low in an absolute sense, and significantly lower than brand understanding of non-tobacco-related advertisements. Results also show that understanding cigarette ads as promoting specific brands of cigarettes is positively related to susceptibility to smoking. Taken together, these findings provide a glimpse of the psychological mechanisms that may underlie the well established link between exposure to cigarette advertising and youth smoking. PMID:18812253

  2. Vapor-phase synthesis of a solid precursor for {alpha}-alumina through a catalytic decomposition of aluminum triisopropoxide

    SciTech Connect

    Nguyen, Tu Quang [Department of Chemical Engineering, Kongju National University, 275 Budae-dong, Cheonan, Chungnam 330-717 (Korea, Republic of)] [Department of Chemical Engineering, Kongju National University, 275 Budae-dong, Cheonan, Chungnam 330-717 (Korea, Republic of); Park, Kyun Young, E-mail: kypark@kongju.ac.kr [Department of Chemical Engineering, Kongju National University, 275 Budae-dong, Cheonan, Chungnam 330-717 (Korea, Republic of); Jung, Kyeong Youl [Department of Chemical Engineering, Kongju National University, 275 Budae-dong, Cheonan, Chungnam 330-717 (Korea, Republic of)] [Department of Chemical Engineering, Kongju National University, 275 Budae-dong, Cheonan, Chungnam 330-717 (Korea, Republic of); Cho, Sung Baek [Korea Institute of Geoscience and Mineral Resources (KIGAM), 92 Gwahang-no, Yuseong-gu 305-350 (Korea, Republic of)] [Korea Institute of Geoscience and Mineral Resources (KIGAM), 92 Gwahang-no, Yuseong-gu 305-350 (Korea, Republic of)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer A new solid precursor for {alpha}-alumina was prepared at about 200 Degree-Sign C from aluminum tri-isopropoxide vapor. Black-Right-Pointing-Pointer The obtained precursor was calcined at 1200 Degree-Sign C to form {alpha}-alumina particles, 75 nm in surface area equivalent diameter. Black-Right-Pointing-Pointer The weight loss of the precursor upon calcination was 24%, lower than that of Al(OH){sub 3}, a conventional alumina precursor. -- Abstract: A new solid precursor, hydrous aluminum oxide, for {alpha}-alumina nanoparticles was prepared by thermal decomposition of aluminum triisopropoxide (ATI) vapor in a 500 mL batch reactor at 170-250 Degree-Sign C with HCl as catalyst. The conversion of ATI increased with increasing temperature and catalyst content; it was nearly complete at 250 Degree-Sign C with the catalyst at 10 mol% of the ATI. The obtained precursor particles were amorphous, spherical and loosely agglomerated. The primary particle size is in the range 50-150 nm. The ignition loss of the precursor was 24%, considerably lower than 35% of Al(OH){sub 3}, the popular precursor for alumina particles. Upon calcination of the precursor at 1200 Degree-Sign C in the air with a heating rate of 10 Degree-Sign C/min and a holding time of 2 h, the phase was completely transformed into {alpha}. The spherical particles composing the precursor turned worm-like by the calcination probably due to sintering between neighboring particles. The surface area equivalent diameter of the resulting {alpha}-alumina was 75 nm.

  3. A lattice Boltzmann study of phase separation in liquid-vapor systems with gravity

    E-print Network

    A. Cristea; G. Gonnella; A. Lamura; V. Sofonea

    2009-07-16

    Phase separation of a two-dimensional van der Waals fluid subject to a gravitational force is studied by numerical simulations based on lattice Boltzmann methods (LBM) implemented with a finite difference scheme. A growth exponent $\\alpha=1$ is measured in the direction of the external force.

  4. Bundles of carbon nanotubes generated by vapor-phase growth Maohui Ge and Klaus Sattler

    E-print Network

    Sattler, Klaus

    -phase condensation of carbon on highly oriented pyrolytic graphite and analyzed by scanning tunneling microscopy of concentric tubules with 2-4 nm in diameter. Atomic resolution images reveal their graphitic surface structure were found with diameters up to 8 nm. Such a limiting diameter seems to be a general property

  5. DrugFacts: Electronic Cigarettes (e-Cigarettes)

    MedlinePLUS

    ... inhalation of tar and other chemicals produced by tobacco combustion; the pleasurable, reinforcing, and addictive properties of smoking are produced mostly by the nicotine contained in tobacco. E-cigarettes are designed to simulate the act ...

  6. Vapor liquid solid-hydride vapor phase epitaxy (VLS-HVPE) growth of ultra-long defect-free GaAs nanowires: Ab initio simulations supporting center nucleation

    SciTech Connect

    André, Yamina, E-mail: yamina.andre@univ-bpclermont.fr; Lekhal, Kaddour; Hoggan, Philip; Avit, Geoffrey; Réda Ramdani, M.; Monier, Guillaume; Colas, David; Ajib, Rabih; Castelluci, Dominique; Gil, Evelyne [Clermont Université, Université Blaise Pascal, Institut Pascal, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR6602, Institut Pascal, F-63171 Aubière (France); Cadiz, Fabian; Rowe, Alistair; Paget, Daniel [Physique de la matière condensée, Ecole Polytechnique CNRS, Palaiseau (France); Petit, Elodie [Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR 6296, ICCF, F-63171 Aubière (France); Leroux, Christine [Université de Toulon, IM2NP, Bât. R, B.P. 20132, 83957 La Garde Cedex (France); CNRS, UMR 7334, 83957 La Garde Cedex (France); Trassoudaine, Agnès [Clermont Université, Université Blaise Pascal, Institut Pascal, BP 10448, F-63000 Clermont-Ferrand (France); CNRS, UMR6602, Institut Pascal, F-63171 Aubière (France); Clermont Université, Université d’Auvergne, BP 10448, F-63000 Clermont-Ferrand (France)

    2014-05-21

    High aspect ratio, rod-like and single crystal phase GaAs nanowires (NWs) were grown by gold catalyst-assisted hydride vapor phase epitaxy (HVPE). High resolution transmission electron microscopy and micro-Raman spectroscopy revealed polytypism-free zinc blende (ZB) NWs over lengths of several tens of micrometers for a mean diameter of 50 nm. Micro-photoluminescence studies of individual NWs showed linewidths smaller than those reported elsewhere which is consistent with the crystalline quality of the NWs. HVPE makes use of chloride growth precursors GaCl of which high decomposition frequency after adsorption onto the liquid droplet catalysts, favors a direct and rapid introduction of the Ga atoms from the vapor phase into the droplets. High influxes of Ga and As species then yield high axial growth rate of more than 100 ?m/h. The diffusion of the Ga atoms in the liquid droplet towards the interface between the liquid and the solid nanowire was investigated by using density functional theory calculations. The diffusion coefficient of Ga atoms was estimated to be 3 × 10{sup ?9} m{sup 2}/s. The fast diffusion of Ga in the droplet favors nucleation at the liquid-solid line interface at the center of the NW. This is further evidence, provided by an alternative epitaxial method with respect to metal-organic vapor phase epitaxy and molecular beam epitaxy, of the current assumption which states that this type of nucleation should always lead to the formation of the ZB cubic phase.

  7. Perspectives on pulmonary inflammation and lung cancer risk in cigarette smokers.

    PubMed

    Smith, Carr J; Perfetti, Thomas A; King, Judy A

    2006-08-01

    Cigarette mainstream smoke (MSS) inhaled by smokers is a complex aerosol composed of minute liquid droplets suspended within a mixture of combustion gases (CO, CO2, NOx, etc.) and semivolatile compounds. The minute liquid droplets represent the particulate or "tar" phase, while the combustion gases and semivolatiles comprise the vapor phase. For historical and technical reasons, the vast majority of studies on the carcinogenicity of MSS have focused on the particulate phase. The particulate phase is mutagenic and cytotoxic in vitro, proinflammatory, and promotes tumor formation in animal models. In addition to cytotoxic compounds found in the particulate phase, the vapor phase of MSS contains a number of cytotoxic constituents including reactive aldehydes and carbonyls capable of damaging cells and inducing pulmonary inflammation. A large body of evidence suggests that smoking-induced pulmonary inflammation may play an important role in increasing lung cancer risk in smokers. Use of aspirin and nonsteroidal anti-inflammatory drugs is associated with reduced cancer development in animal models and lower lung cancer rates in smokers. A number of benign nonpulmonary and pulmonary diseases characterized by chronic inflammation increase the risk of cancer at the affected site in the absence of chemical exposure. Animal models displaying tumorigenic responses following exposure to either whole smoke or smoke fractions show elevated rates of cellular proliferation. A relationship between pulmonary inflammation and lung cancer is mechanistically plausible because inflammatory cells secrete activated oxygen species, inflammatory mediators, and proteolytic enzymes that can both damage DNA and lead to increases in reparative cell proliferation rates. PMID:16864557

  8. Many Pregnant Women Think E-Cigarettes 'Safer' Than Regular Cigarettes

    MedlinePLUS

    ... news/fullstory_152294.html Many Pregnant Women Think E-Cigarettes 'Safer' Than Regular Cigarettes But expectant moms shouldn' ... only 57 percent of the women believed that e-cigarettes contain nicotine. And fewer than two-thirds of ...

  9. A new analytical methodology for a fast evaluation of semi-volatile polycyclic aromatic hydrocarbons in the vapor phase downstream of a diesel engine particulate filter.

    PubMed

    Portet-Koltalo, F; Preterre, D; Dionnet, F

    2011-02-18

    A new sampling method was developed to collect vapor-phase polycyclic aromatic compounds (PAHs) downstream of a diesel engine equipped with a diesel particulate filter (DPF). This configuration allowed us to collect separately the particulate phase, which was trapped inside the DPF, and the vapor phase, which was sampled downstream of the DPF. PAHs, which were not predominantly absorbed into the poor organic fraction of the diesel soot, but were rather physically sorbed on high energetic adsorption sites, should be extracted using very drastic extraction conditions Microwave-assisted extraction using solvent mixtures composed of pyridine and diethylamine were used to desorb particulate PAHs, and the total PAH amounts corresponded to a very low value, i.e., 8 ?g g?¹ or 0.24 ?g km?¹, with a predominance of low weight PAHs. For collection of the vapor phase, gas bubbling in an aqueous medium was preferred to conventional methods, e.g., trapping on solid sorbents, for several reasons: aqueous trapping allowed us to use a solid phase enrichment process (SPE) that permitted PAH sampling at the sub-picogram levels. Consequently, low volume sampling was possible even if the sampling duration was very short (20 min). Additionally, the amount of time saved for the analysis was considerable when coupling SPE to the analytical system (liquid chromatography with fluorimetric detection). Solvent consumption for the overall sampling and analytical processes was also drastically reduced. Experiments on a diesel engine showed that vapor phase samples collected downstream of the DPF contained all of the 15 target priority PAHs, even the heaviest ones. The total vapor-phase PAH amount was 6.88 ?g N m?³ or 10.02 ?g km?¹, which showed that the gaseous fraction contains more PAHs than the particulate fraction. Partitioning coefficients (K(p)) were estimated showing the predominance in the vapor phase of all the PAHs. However, the DPF technology effects a considerable decrease in the total PAH emission when compared to non-equipped diesel vehicles. PMID:21227441

  10. The Case in Favor of E-Cigarettes for Tobacco Harm Reduction

    PubMed Central

    Nitzkin, Joel L.

    2014-01-01

    A carefully structured Tobacco Harm Reduction (THR) initiative, with e-cigarettes as a prominent THR modality, added to current tobacco control programming, is the most feasible policy option likely to substantially reduce tobacco-attributable illness and death in the United States over the next 20 years. E-cigarettes and related vapor products are the most promising harm reduction modalities because of their acceptability to smokers. There are about 46 million smokers in the United States, and an estimated 480,000 deaths per year attributed to cigarette smoking. These numbers have been essentially stable since 2004. Currently recommended pharmaceutical smoking cessation protocols fail in about 90% of smokers who use them as directed, even under the best of study conditions, when results are measured at six to twelve months. E-cigarettes have not been attractive to non-smoking teens or adults. Limited numbers non-smokers have experimented with them, but hardly any have continued their use. The vast majority of e-cigarette use is by current smokers using them to cut down or quit cigarettes. E-cigarettes, even when used in no-smoking areas, pose no discernable risk to bystanders. Finally, addition of a THR component to current tobacco control programming will likely reduce costs by reducing the need for counseling and drugs. PMID:25003176

  11. The case in favor of E-cigarettes for tobacco harm reduction.

    PubMed

    Nitzkin, Joel L

    2014-06-01

    A carefully structured Tobacco Harm Reduction (THR) initiative, with e-cigarettes as a prominent THR modality, added to current tobacco control programming, is the most feasible policy option likely to substantially reduce tobacco-attributable illness and death in the United States over the next 20 years. E-cigarettes and related vapor products are the most promising harm reduction modalities because of their acceptability to smokers. There are about 46 million smokers in the United States, and an estimated 480,000 deaths per year attributed to cigarette smoking. These numbers have been essentially stable since 2004. Currently recommended pharmaceutical smoking cessation protocols fail in about 90% of smokers who use them as directed, even under the best of study conditions, when results are measured at six to twelve months. E-cigarettes have not been attractive to non-smoking teens or adults. Limited numbers non-smokers have experimented with them, but hardly any have continued their use. The vast majority of e-cigarette use is by current smokers using them to cut down or quit cigarettes. E-cigarettes, even when used in no-smoking areas, pose no discernable risk to bystanders. Finally, addition of a THR component to current tobacco control programming will likely reduce costs by reducing the need for counseling and drugs. PMID:25003176

  12. Resonant Coherent Anti-Stokes Raman Scattering Applied to Vapor Phase InI.

    PubMed

    Bruchhausen; Voigt; Doerk; Hädrich; Uhlenbusch

    2000-05-01

    The metal halide indium iodide (InI) is used as an important additive to mercury discharge lamps. The aim of this paper is to prepare resonant coherent anti-Stokes Raman scattering (RECARS) experiments for measuring concentration and temperature profiles of InI in commercially available metal halide lamps. The spectral positions of possible RECARS lines of InI (double and triple resonances) are calculated up to rotational quantum number J = 280 and vibrational quantum number v = 10. There is evidence for triple resonances leading to strong RECARS signals at J = 174 and J = 231. Dipole transition moments are calculated, which are important input data for the determination of the RECARS spectra. A degenerate-folded BOXCARS setup with a frequency-tripled Nd:YAG laser at 355 nm pumping two dye-laser systems oscillating near 411 nm is utilized to detect RECARS signals of the rovibronic transitions between X:(1)Sigma(+) and A:(3)Pi(0)(0(+)) states of InI. The laser output is attenuated to prevent saturation of the spectra. The tunable dye-laser systems have good beam-pointing stability and a small spectral width (<0.07 cm(-1)). Measured RECARS spectra from a pure InI vapor quartz cell at p = 120 Pa and T = 880 K are compared with theoretical data and good agreement is obtained with respect to the spectral position and RECARS intensity. The scatter signals are achieved with laser-pulse energies of less than 1 µJ. A collision-constant Gamma = 0.0025 cm(-1) describes the line broadening best. The experiments are also performed at a partial InI pressure of 1.12 kPa, a partial Hg pressure of 112 kPa, and a temperature of T = 1073 K and could be interpreted with a broadening constant Gamma = 0.23 cm(-1). Temperature measurements were performed between 900 and 1200 K with an accuracy of 7%. Copyright 2000 Academic Press. PMID:10753612

  13. Electronic cigarettes and thirdhand tobacco smoke: two emerging health care challenges for the primary care provider

    PubMed Central

    Kuschner, Ware G; Reddy, Sunayana; Mehrotra, Nidhi; Paintal, Harman S

    2011-01-01

    Primary care providers should be aware of two new developments in nicotine addiction and smoking cessation: 1) the emergence of a novel nicotine delivery system known as the electronic (e-) cigarette; and 2) new reports of residual environmental nicotine and other biopersistent toxicants found in cigarette smoke, recently described as “thirdhand smoke”. The purpose of this article is to provide a clinician-friendly introduction to these two emerging issues so that clinicians are well prepared to counsel smokers about newly recognized health concerns relevant to tobacco use. E-cigarettes are battery powered devices that convert nicotine into a vapor that can be inhaled. The World Health Organization has termed these devices electronic nicotine delivery systems (ENDS). The vapors from ENDS are complex mixtures of chemicals, not pure nicotine. It is unknown whether inhalation of the complex mixture of chemicals found in ENDS vapors is safe. There is no evidence that e-cigarettes are effective treatment for nicotine addiction. ENDS are not approved as smoking cessation devices. Primary care givers should anticipate being questioned by patients about the advisability of using e-cigarettes as a smoking cessation device. The term thirdhand smoke first appeared in the medical literature in 2009 when investigators introduced the term to describe residual tobacco smoke contamination that remains after the cigarette is extinguished. Thirdhand smoke is a hazardous exposure resulting from cigarette smoke residue that accumulates in cars, homes, and other indoor spaces. Tobacco-derived toxicants can react to form potent cancer causing compounds. Exposure to thirdhand smoke can occur through the skin, by breathing, and by ingestion long after smoke has cleared from a room. Counseling patients about the hazards of thirdhand smoke may provide additional motivation to quit smoking. PMID:21475626

  14. Electronic cigarettes and thirdhand tobacco smoke: two emerging health care challenges for the primary care provider.

    PubMed

    Kuschner, Ware G; Reddy, Sunayana; Mehrotra, Nidhi; Paintal, Harman S

    2011-01-01

    PRIMARY CARE PROVIDERS SHOULD BE AWARE OF TWO NEW DEVELOPMENTS IN NICOTINE ADDICTION AND SMOKING CESSATION: 1) the emergence of a novel nicotine delivery system known as the electronic (e-) cigarette; and 2) new reports of residual environmental nicotine and other biopersistent toxicants found in cigarette smoke, recently described as "thirdhand smoke". The purpose of this article is to provide a clinician-friendly introduction to these two emerging issues so that clinicians are well prepared to counsel smokers about newly recognized health concerns relevant to tobacco use. E-cigarettes are battery powered devices that convert nicotine into a vapor that can be inhaled. The World Health Organization has termed these devices electronic nicotine delivery systems (ENDS). The vapors from ENDS are complex mixtures of chemicals, not pure nicotine. It is unknown whether inhalation of the complex mixture of chemicals found in ENDS vapors is safe. There is no evidence that e-cigarettes are effective treatment for nicotine addiction. ENDS are not approved as smoking cessation devices. Primary care givers should anticipate being questioned by patients about the advisability of using e-cigarettes as a smoking cessation device. The term thirdhand smoke first appeared in the medical literature in 2009 when investigators introduced the term to describe residual tobacco smoke contamination that remains after the cigarette is extinguished. Thirdhand smoke is a hazardous exposure resulting from cigarette smoke residue that accumulates in cars, homes, and other indoor spaces. Tobacco-derived toxicants can react to form potent cancer causing compounds. Exposure to thirdhand smoke can occur through the skin, by breathing, and by ingestion long after smoke has cleared from a room. Counseling patients about the hazards of thirdhand smoke may provide additional motivation to quit smoking. PMID:21475626

  15. A semi-empirical model for the complete orientation dependence of the growth rate for vapor phase epitaxy - Chloride VPE of GaAs

    NASA Technical Reports Server (NTRS)

    Seidel-Salinas, L. K.; Jones, S. H.; Duva, J. M.

    1992-01-01

    A semi-empirical model has been developed to determine the complete crystallographic orientation dependence of the growth rate for vapor phase epitaxy (VPE). Previous researchers have been able to determine this dependence for a limited range of orientations; however, our model yields relative growth rate information for any orientation. This model for diamond and zincblende structure materials is based on experimental growth rate data, gas phase diffusion, and surface reactions. Data for GaAs chloride VPE is used to illustrate the model. The resulting growth rate polar diagrams are used in conjunction with Wulff constructions to simulate epitaxial layer shapes as grown on patterned substrates. In general, this model can be applied to a variety of materials and vapor phase epitaxy systems.

  16. Organic Vapor Phase Deposition (OVPD) for efficient OLED manufacturing: the specific advantages and possibilities of carrier-gas enhanced vapor phase deposition for the manufacturing of organic thin film devices

    NASA Astrophysics Data System (ADS)

    Kreis, Juergen; Schwambera, Markus; Keiper, Dietmar; Gersdorff, Markus; Long, Michael; Heuken, Michael

    2012-09-01

    Being introduced more than 20 years ago, OLEDs have seen a strong push in particular in the last two years, mostly driven by key players in the flat panel display industry. The majority of OLEDs manufactured today are deposited by vacuum thermal evaporation (VTE). Whilst this approach enables the making of high-performance devices scaling up of this approach has met new challenges when substrate dimensions are exceeding the "proof-of-principle" dimensions of pilot lines. Total production costs are increasingly moving into the focus of consideration. With Organic Vapor Phase Deposition (OVPD), AIXTRON has commercialized the principle of utilizing inert carriergas for the transport and controlled condensation of small molecules. While the original concept had been proposed by Prof. Steven Forrest at Princeton University, AIXTRON added its expertise in scaling gas phase processes to make this technology applicable for high-throughput production. Combining the basic concept of OVPD with AIXTRON's comprehensive expertise in utilizing close coupled showerheads and the underlying scaling rules, the disruptive approach offers a number of significant advantages: 1) decoupling of evaporation source and deposition system: additional freedom and independent optimization of source design and deposition area; 2) Utilization of carrier-gas for a more efficient evaporation, potentially increasing process windows; 3) Close-coupled showerhead approach realizes high material utilization with homogeneity; 4) Control of deposition rates by carrier-gas flow instead of the evaporation temperature enables precise rates control, co-deposition of various materials at changing rates. This paper will discuss the most significant differences compared to VTE and explain how the approach addresses requirements for efficient scaling as well as enabling advanced structure designs.

  17. Cigarette tax avoidance and evasion.

    PubMed

    Stehr, Mark

    2005-03-01

    Variation in state cigarette taxes provides incentives for tax avoidance through smuggling, legal border crossing to low tax jurisdictions, or Internet purchasing. When taxes rise, tax paid sales of cigarettes will decline both because consumption will decrease and because tax avoidance will increase. The key innovation of this paper is to compare cigarette sales data to cigarette consumption data from the Behavioral Risk Factor Surveillance System (BRFSS). I show that after subtracting percent changes in consumption, residual percent changes in sales are associated with state cigarette tax changes implying the existence of tax avoidance. I estimate that the tax avoidance response to tax changes is at least twice the consumption response and that tax avoidance accounted for up to 9.6% of sales between 1985 and 2001. Because of the increase in tax avoidance, tax paid sales data understate the level of smoking and overstate the drop in smoking. I also find that the level of legal border crossing was very low relative to other forms of tax avoidance. If states have strong preferences for smoking control, they must pair high cigarette taxes with effective policies to curb smuggling and other forms of tax avoidance or employ alternative policies such as counter-advertising and smoking restrictions. PMID:15721046

  18. Marketing of menthol cigarettes and consumer perceptions

    PubMed Central

    2011-01-01

    In order to more fully understand why individuals smoke menthol cigarettes, it is important to understand the perceptions held by youth and adults regarding menthol cigarettes. Perceptions are driven by many factors, and one factor that can be important is marketing. This review seeks to examine what role, if any, the marketing of menthol cigarettes plays in the formation of consumer perceptions of menthol cigarettes. The available literature suggests that menthol cigarettes may be perceived as safer choices than non-menthol cigarettes. Furthermore, there is significant overlap between menthol cigarette advertising campaigns and the perceptions of these products held by consumers. The marketing of menthol cigarettes has been higher in publications and venues whose target audiences are Blacks/African Americans. Finally, there appears to have been changes in cigarette menthol content over the past decade, which has been viewed by some researchers as an effort to attract different types of smokers. PMID:21624148

  19. Hypothetical Thermodynamic Properties. Subcooled Vaporization Enthalpies and Vapor Pressures of Polyaromatic Heterocycles and Related Compounds

    E-print Network

    Chickos, James S.

    Hypothetical Thermodynamic Properties. Subcooled Vaporization Enthalpies and Vapor Pressures The vaporization enthalpies and vapor pressures of the liqiud phase from T ) 298.15 K to T ) 500 K of a series. The vaporization enthalpies at T ) 298.15 K measured in kilojoules per mole include: tri-n-butylamine (62.7 ( 1

  20. Metalorganic-vapor-phase-epitaxial growth of Mg-doped Ga1 - xAlxAs layers and their properties

    NASA Astrophysics Data System (ADS)

    Kozen, Atsuo; Nojima, Shunji; Tenmyo, Jiro; Asahi, Hajime

    1986-02-01

    Magnesium-doped Ga1-xAlxAs layers are grown by metalorganic vapor-phase epitaxy (MOVPE) on (100)-GaAs substrates using bis-cyclopentadienyl magnesium (Cp2Mg) as the organometallic precursor to Mg. Room-temperature hole concentrations in the range of 1×1017-1×1019 cm-3 are achieved with high controllability. The electrical properties are comparable to those for Zn-doped GaAlAs layers. The Mg acceptor energy Ea increases from 25 meV for an Al composition of x=0 to 42 meV for x=0.7. The x dependence of Ea is smaller than that for Zn. Photoluminescence intensities for GaAs and Ga0.7Al0.3As layers are comparable and increased linearly with hole concentration up to the middle of 1018 cm-3. The Mg diffusion coefficients in GaAs and Ga0.7Al0.3As layers are also similar, and are much smaller than the diffusion coefficient for Zn. These results indicate that Mg is a useful p-type dopant in the MOVPE growth of GaAlAs layers.

  1. Impact of thermal annealing on bulk InGaAsSbN materials grown by metalorganic vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Kim, T. W.; Kim, K.; Lee, J. J.; Kuech, T. F.; Mawst, L. J.; Wells, N. P.; LaLumondiere, S. D.; Sin, Y.; Lotshaw, W. T.; Moss, S. C.

    2014-02-01

    Two different thermal annealing techniques (rapid thermal annealing (RTA) and in-situ post-growth annealing in the metalorganic vapor phase epitaxy (MOVPE) chamber) were employed to investigate their impact on the optical characteristics of double-heterostructures (DH) of InGaAsSbN/GaAs and on the performance of single-junction solar cell structures, all grown by MOVPE. We find that an optimized RTA procedure leads to a similar improvement in the photoluminescence (PL) intensity compared with material employing a multi-step optimized anneal within the MOVPE reactor. Time-resolved photoluminescence techniques at low temperature (LT) and room temperature (RT) were performed to characterize the carrier dynamics in bulk InGaAsSbN layers. Room temperature carrier lifetimes were found to be similar for both annealing methods, although the LT-PL (16 K) measurements of the MOVPE-annealed sample found longer lifetimes than the RTA-annealed sample (680 ps vs. 260 ps) for the PL measurement energy of 1.24 eV. InGaAsSbN-based single junction solar cells processed with the optimized RTA procedure exhibited an enhancement of the electrical performance, such as improvements in open circuit voltage, short circuit current, fill factor, and efficiency over solar cells subjected to the in-situ MOVPE annealing technique.

  2. DNA-induced 2D-to-1D Phase Transition of Nanoparticle Assemblies at Liquid-Vapor Interface

    NASA Astrophysics Data System (ADS)

    Srivastava, Sunita; Nykypanchuk, Dmytro; Fukuto, Masafumi; Gang, Oleg

    2012-02-01

    We have investigated the structure formation and development for two-dimensional assembly of DNA functionalized nanoparticles at liquid-vapor interface. The adsorption of negatively charged DNA-coated particle to the interface was triggered by a positively charged lipid layer. A normal and in-plane structure of the nanoparticle monolayer were probed using in-situ surface scattering methods, x-ray reflectivity and grazing incidence small angle x-ray scattering. We observed the formation of the hexagonally closed packed (HCP) 2D lattice of nanoparticles due to a combination of electrostatic surface-to-particle attraction and interparticle repulsion. Upon an onset of DNA hybridization between particles the phase transition from HCP order to 1D crystalline structure was observed. The control on the interparticle spacing and monolayer confinement were also examined by changing a salt concentration. Our studies demonstrate novel mechanism for transition from ordered 2D to ordered 1D structure due to the domination of DNA-induced attraction over an electrostatic repulsion and open a route for nano-structure manipulations at the interfaces.

  3. Vapor-phase toxicity of Derris scandens Benth.-derived constituents against four stored-product pests.

    PubMed

    Hymavathi, Atmakur; Devanand, Peta; Suresh Babu, Katragadda; Sreelatha, Thonthula; Pathipati, Usha Rani; Madhusudana Rao, Janaswamy

    2011-03-01

    The vapor-phase toxicity of Derris scandens Benth.-derived constituents was evaluated against four stored-product pests ( Callosobruchus chinensis L., Sitophilus oryzae L., Rhyzopertha dominica L., and Tribolium castaneum H.) using fumigation bioassays and compared to those of commonly used insecticides. The structures of all constituents of were characterized by spectroscopic analyses [nuclear magnetic resonance (NMR) and mass spectrometry]. The sensitivity of the test insect to compounds varied with exposure time, concentration, and insect species. Over 100% mortality after 24 h was achieved with the compounds osajin (2), scandinone (5), sphaerobioside (8), and genistein (9) against all of the test insects, while laxifolin (3) and lupalbigenin (4) showed 100% mortality after 72 h against T. csataneum and R. dominica . Scandenone (1), scandenin A (6), and scandenin (7) were less effective. Among the insects, C. chinensis , S. oryzae , and R. dominica were more susceptible to the treatments, whereas T. castaneum was less susceptible. The results of fumigation tests indicated that compounds from D. scandens whole plant extract are potential candidates to control stored-product pests. PMID:21314138

  4. Characteristics of GaSb and GaInSb layers grown by metalorganic vapor phase epitaxy

    SciTech Connect

    Ehsani, H.; Bhat, I.; Hitchcock, C.; Borrego, J.; Gutmann, R. [Rensselaer Polytechnic Inst., Troy, NY (United States)

    1995-07-01

    GaInSb and GaSb layers have been grown on GaSb and GaAs substrates using metalorganic vapor phase epitaxy (MOVPE) with trimethylgallium, trimethylindium and trimethylantimony as the sources. As grown layers are p type with the carrier concentration in the mid 10{sup 16} cm{sup {minus}3} range. N type layers are grown using diethyltellurium as the Te source. Incorporation of Te in high concentration showed compensation and secondary ion mass spectrometry (SIMS) result showed that only 2.5% of Te are active when 2 {times} 10{sup 19} cm{sup {minus}3} of Te was incorporated. The carrier concentration measured in n type samples increases as the temperature is lowered. This is explained by the presence of second band close to the conduction band minima. Silane which is a common n type dopant in GaAs and other III-V systems is shown to behave like p type in GaInSb. P-n junction structures have been grown on GaSb substrates to fabricate TPV cells.

  5. Controlled Vapor Phase Growth of Single Crystalline, Two-Dimensional GaSe Crystals with High Photoresponse

    PubMed Central

    Li, Xufan; Lin, Ming-Wei; Puretzky, Alexander A.; Idrobo, Juan C.; Ma, Cheng; Chi, Miaofang; Yoon, Mina; Rouleau, Christopher M.; Kravchenko, Ivan I.; Geohegan, David B.; Xiao, Kai

    2014-01-01

    Compared with their bulk counterparts, atomically thin two-dimensional (2D) crystals exhibit new physical properties, and have the potential to enable next-generation electronic and optoelectronic devices. However, controlled synthesis of large uniform monolayer and multi-layer 2D crystals is still challenging. Here, we report the controlled synthesis of 2D GaSe crystals on SiO2/Si substrates using a vapor phase deposition method. For the first time, uniform, large (up to ~60??m in lateral size), single-crystalline, triangular monolayer GaSe crystals were obtained and their structure and orientation were characterized from atomic scale to micrometer scale. The size, density, shape, thickness, and uniformity of the 2D GaSe crystals were shown to be controllable by growth duration, growth region, growth temperature, and argon carrier gas flow rate. The theoretical modeling of the electronic structure and Raman spectroscopy demonstrate a direct-to-indirect bandgap transition and progressive confinement-induced bandgap shifts for 2D GaSe crystals. The 2D GaSe crystals show p-type semiconductor characteristics and high photoresponsivity (~1.7?A/W under white light illumination) comparable to exfoliated GaSe nanosheets. These 2D GaSe crystals are potentially useful for next-generation electronic and optoelectronic devices such as photodetectors and field-effect transistors. PMID:24975226

  6. Low-temperature emission in dilute GaAsN alloys grown by metalorganic vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Bentoumi, G.; Yaïche, Z.; Leonelli, R.; Beaudry, J.-N.; Desjardins, P.; Masut, R. A.

    2008-03-01

    We have investigated the optical emission from GaAs1-xNx epilayers with 4.3×10-4vapor phase epitaxy using dimethylhydrazine as the nitrogen precursor. We find that the incorporation of nitrogen in GaAs generates deep radiative centers at around 250meV below the GaAsN band gap. The defects associated with these centers can be eliminated through an optimization of the growth temperature and reactor pressure, and by postgrowth annealing at 700°C. We also find that, contrary to what was suggested by Makimoto et al. [Appl. Phys. Lett. 70, 2984 (1997)], the near-gap emission located close to 25meV below the gap is not related to a free-to-bound transition even in the samples with the lowest nitrogen content. Rather, we associate this emission to excitons bound to overlapping nitrogen clusters.

  7. Impact of thermal annealing on bulk InGaAsSbN materials grown by metalorganic vapor phase epitaxy

    SciTech Connect

    Kim, T. W.; Mawst, L. J., E-mail: mawst@engr.wisc.edu [Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Kim, K.; Lee, J. J. [Department of Electrical and Computer Engineering, Ajou University, Suwon 443-749 (Korea, Republic of); Kuech, T. F. [Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Wells, N. P.; LaLumondiere, S. D.; Sin, Y.; Lotshaw, W. T.; Moss, S. C. [Electronics and Photonics Lab, The Aerospace Corporation, El Segundo, California 90245 (United States)

    2014-02-03

    Two different thermal annealing techniques (rapid thermal annealing (RTA) and in-situ post-growth annealing in the metalorganic vapor phase epitaxy (MOVPE) chamber) were employed to investigate their impact on the optical characteristics of double-heterostructures (DH) of InGaAsSbN/GaAs and on the performance of single-junction solar cell structures, all grown by MOVPE. We find that an optimized RTA procedure leads to a similar improvement in the photoluminescence (PL) intensity compared with material employing a multi-step optimized anneal within the MOVPE reactor. Time-resolved photoluminescence techniques at low temperature (LT) and room temperature (RT) were performed to characterize the carrier dynamics in bulk InGaAsSbN layers. Room temperature carrier lifetimes were found to be similar for both annealing methods, although the LT-PL (16?K) measurements of the MOVPE-annealed sample found longer lifetimes than the RTA-annealed sample (680?ps vs. 260?ps) for the PL measurement energy of 1.24?eV. InGaAsSbN-based single junction solar cells processed with the optimized RTA procedure exhibited an enhancement of the electrical performance, such as improvements in open circuit voltage, short circuit current, fill factor, and efficiency over solar cells subjected to the in-situ MOVPE annealing technique.

  8. Influence of substrate surface defects on the homoepitaxial growth of GaN (0001) by metalorganic vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Zhou, Kun; Liu, Jianping; Ikeda, Masao; Zhang, Shuming; Li, Deyao; Zhang, Liqun; Zeng, Chang; Yang, Hui

    2015-04-01

    Surface morphology of homoepitaxial GaN (0001) grown by metalorganic vapor phase epitaxy was studied. Selective growth was observed on the homoepitaxial GaN layer grown on as-received GaN substrate and was attributed to the existence of substrate surface defects. The steps were pinned by defects and meandered. Due to the pinning effect, the step pattern developed to a wavy surface with a strip-like feature along the [ 11 2 bar 0] direction during the subsequent growth of a thick n-GaN layer. Because of the surface undulations, the emission of InGaN/GaN multiple quantum wells grown on the n-GaN layer was inhomogeneous. The surface defects on GaN substrate could be removed by dry etching and the homoepitaxial layer on the etched substrate showed a smooth morphology and straight atomic steps. As a result, the emission of the InGaN/GaN MQWs became homogeneous.

  9. Vapor-phase Raman spectra, theoretical calculations, and the vibrational and structural properties of cis- and trans-stilbene.

    PubMed

    Egawa, Toru; Shinashi, Kiyoaki; Ueda, Toyotoshi; Ocola, Esther J; Chiang, Whe-Yi; Laane, Jaan

    2014-02-13

    The vapor-phase Raman spectra of cis- and trans-stilbene have been collected at high temperatures and assigned. The low-frequency skeletal modes were of special interest. The molecular structures and vibrational frequencies of both molecules have also been obtained using MP2/cc-pVTZ and B3LYP/cc-pVTZ calculations, respectively. The two-dimensional potential map for the internal rotations around the two Cphenyl-C(?C) bonds of cis-stilbene was generated by using a series of B3LYP/cc-pVTZ calculations. It was confirmed that the molecule has only one conformer with C2 symmetry. The energy level calculation with a two-dimensional Hamiltonian was carried out, and the probability distribution for each level was obtained. The calculation revealed that the "gearing" internal rotation in which the two phenyl rings rotate with opposite directions has a vibrational frequency of 26 cm(-1), whereas that of the "antigearing" internal rotation in which the phenyl rings rotate with the same direction is about 52 cm(-1). In the low vibrational energy region the probability distribution for the gearing internal rotation is similar to that of a one-dimensional harmonic oscillator, and in the higher region the motion behaves like that of a free rotor. PMID:24409818

  10. Crystal growth via metal-organic vapor phase epitaxy of quantum-cascade-laser structures composed of multiple alloy compositions

    NASA Astrophysics Data System (ADS)

    Shin, Jae Cheol; Mawst, Luke J.; Botez, Dan

    2012-10-01

    Metal-organic vapor phase epitaxy (MOVPE) is suitable for the growth of superlattice (SL) structures composed of multiple alloy compositions. By taking advantage of this flexibility of MOVPE, we have demonstrated the crystal growth of varying-layer-composition, 4.8 ?m-emitting, tapered active-region quantum cascade lasers (TA-QCLs), for which the barriers in the active region gradually increase in height from the injection barrier to the exit barrier, resulting, in turn, in a dramatic suppression of carrier leakage. One stage of the TA-QCL structure consists of seven different alloy compositions. The composition and growth rate of each layer are calibrated by using high-resolution X-ray-diffraction rocking curves. Very narrow mid-infrared absorption peaks (˜30 meV full width at half-maximum) have been achieved, at room temperature, from 20 periods of In0.6Ga0.4As/Al0.56In0.44As SL structures, at the designed wavelength. Transmission-electron-microscope analysis of the QCL structure confirms extremely accurate thickness control and layer uniformity for layers as thin as 1 nm.

  11. Effects of transport gradients in a chemical vapor deposition reactor employing vapor-liquid-solid growth of ternary chalcogenide phase-change materials.

    PubMed

    Johnson, Derek C; Morris, Wesley D; Prieto, Amy L

    2010-04-23

    Chemical vapor deposition (CVD) with vapor-liquid-solid (VLS) growth is employed to synthesize individual Ge(2)Sb(2)Te(5) nanowires with the ultimate goal of synthesizing a large scale nanowire array for universal memory storage. A consistent challenge encountered during the synthesis is a lack of control over the composition and morphology across the growth substrate. To better understand the challenges associated with the CVD synthesis of the ternary chalcogenide, computational fluid dynamics simulations are performed to quantify 3D thermal and momentum transients in the growth conditions. While these gradients are qualitatively known to exist, they have not been adequately quantified in both the axial and radial directions when under pressure and flow conditions indicative of VLS growth. These data are not easily acquired by conventional means for the axial direction under vacuum and are a considerable challenge to accurately measure radially. The simulation data shown here provide 3D insights into the gradients which ultimately dictate the region of controllable stoichiometry and morphology. These results help explain the observed inhomogeneity of the characterized ternary chalcogenide growth products at various growth substrate locations. PMID:20351405

  12. Effects of transport gradients in a chemical vapor deposition reactor employing vapor-liquid-solid growth of ternary chalcogenide phase-change materials

    NASA Astrophysics Data System (ADS)

    Johnson, Derek C.; Morris, Wesley D.; Prieto, Amy L.

    2010-04-01

    Chemical vapor deposition (CVD) with vapor-liquid-solid (VLS) growth is employed to synthesize individual Ge2Sb2Te5 nanowires with the ultimate goal of synthesizing a large scale nanowire array for universal memory storage. A consistent challenge encountered during the synthesis is a lack of control over the composition and morphology across the growth substrate. To better understand the challenges associated with the CVD synthesis of the ternary chalcogenide, computational fluid dynamics simulations are performed to quantify 3D thermal and momentum transients in the growth conditions. While these gradients are qualitatively known to exist, they have not been adequately quantified in both the axial and radial directions when under pressure and flow conditions indicative of VLS growth. These data are not easily acquired by conventional means for the axial direction under vacuum and are a considerable challenge to accurately measure radially. The simulation data shown here provide 3D insights into the gradients which ultimately dictate the region of controllable stoichiometry and morphology. These results help explain the observed inhomogeneity of the characterized ternary chalcogenide growth products at various growth substrate locations.

  13. Vapor-phase testing of the memory-effects in benzene- and toluene-imprinted polymers conditioned at elevated temperature.

    PubMed

    Azenha, Manuel; Schillinger, Eric; Sanmartin, Esther; Regueiras, M Teresa; Silva, Fernando; Sellergren, Börje

    2013-11-13

    The preparation of polymers imprinted with common aromatic solvents such as benzene and toluene is an under-exploited subject of research. The present study was aimed at the understanding of whether true solvent memory effects can be achieved by molecular imprinting, as well as if they are stable at elevated temperature. A set of copolymers, comprising low and high cross-linking levels, was prepared from four different combinations of functional monomer and cross-linker, namely methacrylic acid (MAA)/ethylene glycol dimethacrylate (EGDMA), methyl methacrylate (MMA)/EGDMA, MAA/divinyl benzene (DVB) and MMA/DVB. Each possible combination was prepared separately in benzene, toluene and acetonitrile. The obtained materials were applied as coatings onto nickel-titanium (Ni-Ti) alloy wires which were incorporated into solid-phase microextraction devices and finally tested for their ability to competitively adsorb vapors from the headspace of an aqueous solution containing a few volatile organic compounds. Porosity analysis showed that, regardless of the solvent used, only a high cross-linking level permitted the preparation of mesoporous copolymers (BJH radius typically in the range 13-15 nm), a requirement for providing accessibility to the targeted nanoscale-imprinted cavities. A noticeable exception was, however, observed for the MMA/DVB copolymers which exhibited much diminished BJH radius. The porosity data correlated well with the extraction profiles found, which suggested the presence of benzene-imprinted sites in all the highly cross-linked copolymers prepared in benzene, except for the MMA/DVB copolymers. Concerning the effect of an elevated conditioning temperature on the memory-effects created by the imprinting process, the results were clearly indicative that the tested copolymers, including the more robust highly cross-linked ones, are not suitable for high temperature applications such as solid-phase microextraction coupled to gas chromatography. PMID:24176503

  14. Rapid vapor-phase fabrication of organic-inorganic hybrid superlattices with monolayer precision.

    PubMed

    Lee, Byoung H; Ryu, Min Ki; Choi, Sung-Yool; Lee, Kwang-H; Im, Seongil; Sung, Myung M

    2007-12-26

    We report a new layer-by-layer growth method of self-assembled organic multilayer thin films based on gas-phase reactions. In the present molecular layer deposition (MLD) process, alkylsiloxane self-assembled multilayers (SAMs) were grown under vacuum by repeated sequential adsorptions of C=C-terminated alkylsilane and titanium hydroxide. The MLD method is a self- limiting layer-by-layer growth process, and is perfectly compatible with the atomic layer deposition (ALD) method. The SAMs films prepared exhibited good thermal and mechanical stability, and various unique electrical properties. The MLD method, combined with ALD, was applied to the preparation of organic-inorganic hybrid nanolaminate films in the ALD chamber. The organic-inorganic hybrid superlattices were then used as active mediums for two-terminal electrical bistable devices. The advantages of the MLD method with ALD include accurate control of film thickness, large-scale uniformity, highly conformal layering, sharp interfaces, and a vast library of possible materials. The MLD method with ALD is an ideal fabrication technique for various organic-inorganic hybrid superlattices. PMID:18047337

  15. Graphical Interface for the Study of Gas-Phase Reaction Kinetics: Cyclopentene Vapor Pyrolysis

    NASA Astrophysics Data System (ADS)

    Marcotte, Ronald E.; Wilson, Lenore D.

    2001-06-01

    The undergraduate laboratory experiment on the pyrolysis of gaseous cyclopentene has been modernized to improve safety, speed, and precision and to better reflect the current practice of physical chemistry. It now utilizes virtual instrument techniques to create a graphical computer interface for the collection and display of experimental data. An electronic pressure gauge has replaced the mercury manometer formerly needed in proximity to the 500 °C pyrolysis oven. Students have much better real-time information available to them and no longer require multiple lab periods to get rate constants and acceptable Arrhenius parameters. The time saved on manual data collection is used to give the students a tour of the computer interfacing hardware and software and a hands-on introduction to gas-phase reagent preparation using a research-grade high-vacuum system. This includes loading the sample, degassing it by the freeze-pump-thaw technique, handling liquid nitrogen and working through the logic necessary for each reconfiguration of the diffusion pump section and the submanifolds.

  16. Hot wire chemical vapor deposition chemistry in the gas phase and on the catalyst surface with organosilicon compounds.

    PubMed

    Shi, Yujun

    2015-02-17

    CONSPECTUS: Hot wire chemical vapor deposition (HWCVD), also referred to as catalytic CVD (Cat-CVD), has been used to produce Si-containing thin films, nanomaterials, and functional polymer coatings that have found wide applications in microelectronic and photovoltaic devices, in automobiles, and in biotechnology. The success of HWCVD is largely due to its various advantages, including high deposition rate, low substrate temperatures, lack of plasma-induced damage, and large-area uniformity. Film growth in HWCVD is induced by reactive species generated from primary decomposition on the metal wire or from secondary reactions in the gas phase. In order to achieve a rational and efficient optimization of the process, it is essential to identify the reactive species and to understand the chemical kinetics that govern the production of these precursor species for film growth. In this Account, we report recent progress in unraveling the complex gas-phase reaction chemistry in the HWCVD growth of silicon carbide thin films using organosilicon compounds as single-source precursors. We have demonstrated that laser ionization mass spectrometry is a powerful diagnostic tool for studying the gas-phase reaction chemistry when combined with the methods of isotope labeling and chemical trapping. The four methyl-substituted silane molecules, belonging to open-chain alkylsilanes, dissociatively adsorb on W and Ta filaments to produce methyl radical and H2 molecule. Under the typical deposition pressures, with increasing number of methyl substitution, the dominant chemistry occurring in the gas phase switches from silylene/silene reactions to free-radical short chain reactions. This change in dominant reaction intermediates from silylene/silene to methyl radicals explains the observation from thin film deposition that silicon carbide films become more C-rich with a decreasing number of Si-H bonds in the four precursor molecules. In the case of cyclic monosilacyclobutanes, we have shown that ring-opening reactions play a vital role in characterizing the reaction chemistry. On the other hand, exocyclic Si-H(CH3) bond cleavages are more important in the less-puckered disilacyclobutane molecules. Metal filaments are essential in HWCVD since they serve as catalysts to decompose precursor gases to reactive species, which initiate gas-phase reaction chemistry and thin film growth. We discuss the structural changes in metal filaments when exposed to various precursor gases. Depending on the nature of the radical intermediates formed from the hot-wire decomposition and subsequent gas-phase reactions, metal silicides and carbides can be formed. Overall, study of the gas-phase reaction chemistry in HWCVD provides important knowledge of the chemical species produced prior to their deposition on a substrate surface. This helps in identifying the major contributor to alloy formation on the filament itself and the film growth, and consequently, in determining the properties of the deposited films. An integrated knowledge of the gas-phase reaction chemistry, filament alloy formation, and thin film deposition is required for an efficient deposition of high-quality thin films and nanomaterials. PMID:25586211

  17. Transition between the 1 x 1 and ({radical}3 x 2{radical}3)R30{degree} surface structures of GaN in the vapor-phase environment

    SciTech Connect

    Munkholm, A.; Thompson, C.; Stephenson, G. B.; Eastman, J. A.; Auciello, O.; Fini, P.; Speck, J. S.; DenBaars, S. P.

    2000-01-12

    Out-of-plane structures of the GaN(0001) surface in the metal-organic chemical vapor deposition (MOCVD) environment have been determined using in situ grazing-incidence X-ray scattering. The authors measured 11{bar 2}{ell} crystal truncation rod intensities at a variety of temperatures and ammonia partial pressures on both sides of the 1 x 1 to ({radical}3 x 2{radical}3)R30{degree} surface phase transition. The out-of-plane structure of the ({radical}3 x 2{radical}3)R30{degree} phase appears to be nearly independent of temperature below the transition, while the structure of the 1 x 1 phase changes increase rapidly as the phase transition is approached from above. A model for the structure of the 1 x 1 phase with a partially-occupied top Ga layer agrees well with the data. The observed temperature dependence is consistent with a simple model of the equilibrium between the vapor phase and the surface coverage of Ga and N. In addition, the authors present results on the kinetics of reconstruction domain coarsening following a quench into the ({radical}3 x 2{radical}3)R30{degree} phase field.

  18. Scrambled and fried: Cigarette smoke exposure causes antral follicle destruction and oocyte dysfunction through oxidative stress

    SciTech Connect

    Sobinoff, A.P. [Reproductive Science Group, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308 (Australia); Priority Research Centre for Chemical Biology, University of Newcastle, Callaghan, NSW 2308 (Australia); Beckett, E.L.; Jarnicki, A.G. [Centre for Asthma and Respiratory Disease, The University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308 (Australia); Sutherland, J.M. [Reproductive Science Group, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308 (Australia); Priority Research Centre for Chemical Biology, University of Newcastle, Callaghan, NSW 2308 (Australia); McCluskey, A. [Priority Research Centre for Chemical Biology, University of Newcastle, Callaghan, NSW 2308 (Australia); Hansbro, P.M. [Centre for Asthma and Respiratory Disease, The University of Newcastle and Hunter Medical Research Institute, Callaghan, NSW 2308 (Australia); McLaughlin, E.A., E-mail: eileen.mclaughlin@newcastle.edu.au [Reproductive Science Group, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308 (Australia); Priority Research Centre for Chemical Biology, University of Newcastle, Callaghan, NSW 2308 (Australia)

    2013-09-01

    Cigarette smoke is a reproductive hazard associated with pre-mature reproductive senescence and reduced clinical pregnancy rates in female smokers. Despite an increased awareness of the adverse effects of cigarette smoke exposure on systemic health, many women remain unaware of the adverse effects of cigarette smoke on female fertility. This issue is compounded by our limited understanding of the molecular mechanisms behind cigarette smoke induced infertility. In this study we used a direct nasal exposure mouse model of cigarette smoke-induced chronic obstructive pulmonary disease to characterise mechanisms of cigarette-smoke induced ovotoxicity. Cigarette smoke exposure caused increased levels of primordial follicle depletion, antral follicle oocyte apoptosis and oxidative stress in exposed ovaries, resulting in fewer follicles available for ovulation. Evidence of oxidative stress also persisted in ovulated oocytes which escaped destruction, with increased levels of mitochondrial ROS and lipid peroxidation resulting in reduced fertilisation potential. Microarray analysis of ovarian tissue correlated these insults with a complex mechanism of ovotoxicity involving genes associated with detoxification, inflammation, follicular activation, immune cell mediated apoptosis and membrane organisation. In particular, the phase I detoxifying enzyme cyp2e1 was found to be significantly up-regulated in developing oocytes; an enzyme known to cause molecular bioactivation resulting in oxidative stress. Our results provide a preliminary model of cigarette smoke induced sub-fertility through cyp2e1 bioactivation and oxidative stress, resulting in developing follicle depletion and oocyte dysfunction. - Highlights: • Cigarette smoke exposure targets developing follicle oocytes. • The antral follicle oocyte is a primary site of ovarian cigarette smoke metabolism. • Cyp2e1 is a major enzyme involved in ameliorating smoke-induced ovotoxicity. • Cigarette smoke causes oocyte mitochondrial ROS, impairing fertilisation.

  19. Design and performance of a new reactor for vapor phase epitaxy of 3C, 6H, and 4H SiC

    Microsoft Academic Search

    N. Nordell; A. Schoener; S. G. Andersson

    1996-01-01

    The design of a new horizontal reactor for vapor phase epitaxy of SiC is presented. The reactor has a graphite inner cell with rectangular cross section to align the gas stream, and it may handle temperatures up to 1,700 C. The inner cell is surrounded by a highly reflecting heat shield. 6H and 4H SiC were grown homoepitaxially, and 3C

  20. Effect of a Drying Pretreatment on Morphology of Porous Poly(Ether-Imide) Membrane Prepared Using Vapor-Induced Phase Separation

    Microsoft Academic Search

    Chinpa Watchanida; Bouyer Denis; Pochat-Bohatier Céline; Deratani André; Claude Dupuy

    2006-01-01

    Symmetric porous membranes were prepared from concentrated poly(ether-imide) (PEI) solutions using vapor-induced phase separation (VIPS) coupled with a drying pretreatment. Moderately concentrated solutions of PEI in N-methylpyrrolidinone (NMP) (14–16 wt%) were first cast on glass plates and the solvent was then allowed to evaporate under a dry air flow up to the desired concentration (16–38 wt%) before forming the membrane structure by

  1. Direct growth of high-quality thick CdTe epilayers on Si (211) substrates by metalorganic vapor phase epitaxy for nuclear radiation detection and imaging

    Microsoft Academic Search

    M. Niraula; K. Yasuda; H. Ohnishi; H. Takahashi; K. Eguchi; K. Noda; Y. Agata

    2006-01-01

    Direct growth of high-quality, thick CdTe (211) epilayers, with thickness up to 100 m, on Si (211) substrates in a vertical\\u000a metalorganic vapor phase epitaxy system is reported. In order to obtain homo-orientation growth on Si substrates, pretreatment\\u000a of the substrates was carried out in a separate chamber by annealing them together with pieces of GaAs at 800–900C in a

  2. Electron energy-loss spectroscopy characterization of pyramidal defects in metalorganic vapor-phase epitaxy Mg-doped GaN thin films

    Microsoft Academic Search

    M. Benaissa; P. Vennéguès; B. Beaumont; P. Gibart; W. Saikaly; A. Charai

    2000-01-01

    In the present letter, Mg-doped GaN thin films grown by metalorganic vapor-phase epitaxy were studied using parallel electron energy-loss spectroscopy in a transmission electron microscope. A microstructural characterization of such thin films showed the presence of pyramidal defects (PDs) with a density of about 1018 cm-3. Comparison of energy-loss spectra recorded outside a PD and from the PD showed a

  3. Examination of sulfur-functionalized, copper-doped iron nanoparticles for vapor-phase mercury capture in entrained-flow and fixed-bed systems

    Microsoft Academic Search

    D. E. Meyer; S. K. Sikdar; N. D. Hutson; D. Bhattacharyya

    2007-01-01

    The use of copper-doped Fe nanoaggregates silanized with organic sulfur as bis-(triethoxy silyl propyl)-tetra sulfide has been investigated for the capture of elemental mercury (Hg°) from the vapor phase for potential power plant applications. Silanization procedures resulted in 70% deposition of the targeted sulfur level, with particles containing approximately 4 wt % S. The addition of copper was found to

  4. Development of nuclear radiation detectors with energy discrimination capabilities based on thick CdTe Layers grown by metalorganic vapor phase epitaxy

    Microsoft Academic Search

    K. Yasuda; M. Niraula; H. Kusama; Y. Yamamoto; M. Tominaga; K. Takagi; Y. Agata; K. Suzuki

    2005-01-01

    We report on the development of nuclear radiation detectors based on epitaxially grown thick single crystalline CdTe layers. The optimization of the CdTe growth on the GaAs substrates in a metalorganic vapor phase epitaxy resulted high-structural quality and thick CdTe layers of thickness up to 200 ?m. Radiation detectors were fabricated in p-CdTe\\/n-CdTe\\/n+-GaAs structure, where a 2-5 ?m thick iodine-doped

  5. Development of nuclear radiation detectors with energy discrimination capabilities based on thick CdTe layers grown by metalorganic vapor phase epitaxy

    Microsoft Academic Search

    K. Yasuda; M. Niraula; H. Kusama; Y. Yamamoto; M. Tominaga; K. Takagi; Y. Agata; K. Suzuki

    2004-01-01

    We report on the development of nuclear radiation detectors based on epitaxially grown thick single crystalline CdTe layers. The optimization of the CdTe growth on the GaAs substrates in a metalorganic vapor phase epitaxy resulted high-structural quality and thick CdTe layers of thickness up to 200 mum. Radiation detectors were fabricated by growing a 2-5 mum thick iodine-doped n-CdTe buffer

  6. Highly uniform and reproducible vertical-cavity surface-emitting lasers grown by metalorganic vapor phase epitaxy with in situ reflectometry

    Microsoft Academic Search

    H. Q. Hou; H. C. Chui; K. D. Choquette; B. E. Hammons; W. G. Breiland; K. M. Geib

    1996-01-01

    Vertical-cavity surface-emitting lasers (VCSELs) were grown by metalorganic vapor phase epitaxy. Excellent uniformity of Fabry-Perot cavity wavelength for VCSEL materials of ±0.2% across a 3-in diameter wafer was achieved. This results in excellent uniformity of the lasing wavelength and threshold current of VCSEL devices. Employing pregrowth calibrations on growth rates periodically with an in situ reflectometer, we obtained a run-to-run

  7. Formation of Cubic GaN on (111)B GaAs by Metal-Organic Vapor-Phase Epitaxy with Dimethylhydrazine

    NASA Astrophysics Data System (ADS)

    Kuwano, Noriyuki; Kobayashi, Kenki; Oki, Kensuke; Miyoshi, Seiro; Yaguchi, Hiroyuki; Onabe, Kentaro; Shiraki, Yasuhiro

    1994-06-01

    The microstructure of GaN grown on (111)B GaAs by a metal-orgnic vapor-phase epitaxy method has been examined by transmission electron microscopy. Trimethylgallium and dimethylhydrazine were used as the source materials. It was revealed that the GaN crystal has a zincblende structure and is formed heterogeneously penetrating into the GaAs substrate. In a GaN crystal, stacking faults propagate on {111} planes other than those normal to the growth direction.

  8. A model for the effective diffusion of gas or the vapor phase in a fractured media unsaturated zone driven by periodic atmospheric pressure fluctuations

    SciTech Connect

    Vold, E.L.

    1997-03-01

    There is evidence for migration of tritiated water vapor through the tuff in the unsaturated zone from the buried disposal shafts located on a narrow mesa top at Area G, Los Alamos, NM. Field data are consistent with an effective in-situ vapor phase diffusion coefficient of 1.5x10{sup {minus}3} m{sup s}/s, or a factor of 60 greater than the binary diffusion coefficient for water vapor in air. A model is derived to explain this observation of anomolously large diffusion, which relates an effective vapor or gas phase diffusion coefficient in the fractured porous media to the subsurface propagation of atmospheric pressure fluctuations (barometric pumping). The near surface (unattenuated) diffusion coefficient is independent of mode period under the simplified assumptions of a complete {open_quote}mixing mechanism{close_quote} for the effective diffusion process. The unattenuated effective diffusion driven by this barometric pumping is proportional to an average media permeability times the sum of the square of pressure mode amplitudes, while the attenuation length is proportional to the squarer root of the product of permeability times mode period. There is evidence that the permeability needed to evaluate the pressure attenuation length is the in-situ value, approximately that of the matrix. The diffusion which results using Area G parameter values is negligible in the matrix but becomes large at the effective permeability of the fractured tuff matrix. The effective diffusion coefficient predicted by this model, due to pressure fluctuations and the observed fracture characteristics, is in good agreement with the observed in-situ diffusion coefficient for tritium field measurements. It is concluded that barometric pumping in combination with the enhanced permeability of the fractured media is a likely candidate to account for the observed in-field migration of vapor in the near surface unsaturated zone at Area G.

  9. Comparative Analysis of Waterpipe and Cigarette Suppression of Abstinence and Craving Symptoms

    PubMed Central

    Rastam, Samer; Eissenberg, Thomas; Ibrahim, Iman; Ward, Kenneth D; Khalil, Rami; Maziak, Wasim

    2011-01-01

    This study’s objective is to examine the relative effectiveness of cigarettes and waterpipe (WP) in reducing tobacco abstinence symptoms in dual cigarette/WP smokers. Sixty-one dual cigarette/WP smokers participated (mean age ± SD 22.0 ± 2.6 yrs; mean cigarettes/day 22.4 ± 10.1; mean WPs/week 5.2 ± 5.6). After 12-hour abstinence participants completed two smoking sessions (WP or cigarette), while they responded to subjective measures of withdrawal, craving, and nicotine effects administered before smoking and 5, 15, 30 and 45 minutes thereafter. For both tobacco use methods, scores on measures of withdrawal and craving were high at the beginning of session (i.e., before smoking) and were reduced significantly and comparably during smoking. Analysis of smoking and recovery (post-smoking) phases showed similarity in the way both tobacco use methods suppressed withdrawal and craving, but the recovery of some of these symptoms can be faster with cigarette use. This study is the first to show the ability of WP to suppress abstinence effects comparably to cigarettes, and its potential to thwart cigarette cessation. PMID:21316156

  10. Cigars Pose Dangers Similar to Cigarettes

    MedlinePLUS

    ... smoked cigarettes had a much higher risk of lung cancer and chronic obstructive pulmonary disease than those who had not previously smoked cigarettes. The current review included 22 North American and ...

  11. In vitro micronucleus assay for cigarette smoke using a whole smoke exposure system: a comparison of smoking regimens.

    PubMed

    Okuwa, Kosuke; Tanaka, Masahiro; Fukano, Yasuo; Nara, Hidenori; Nishijima, Yosuke; Nishino, Tomoki

    2010-07-01

    Previous studies on the biological assessment of cigarette smoke (CS) mainly focused on the total particulate matter (TPM) collected using a Cambridge filter or gas vapor phase (GVP) bubbled through phosphate-buffered saline (PBS). To study the effects of native CS in vitro, direct exposure methods have been developed. Meanwhile, in vitro micronucleus (MN) assays have been reported to evaluate the mutagenicity of CS. The objective of this research is to investigate the MN-inducing activity of whole smoke (WS) and GVP using a whole smoke exposure system, CULTEX((R)), which allows direct exposure of cultured cells to native CS at the air/liquid interface (ALI). CS was generated according to the International Organization for Standardization (ISO; 35ml, 2s, once per 60s) or the Health Canada Intensive (HCI; 55ml, 2s, once per 30s, with complete ventilation block) regimens and Chinese hamster lung (CHL/IU) cells were then exposed to this smoke. Dosages were adjusted according to the amount of smoke entering the actual exposure position. Under both smoking regimens, WS and GVP from 2R4F reference cigarettes induced MN responses. The concept of the dosage and similar dose-response relationships between theoretical and monitored dosage values under the two regimens enabled us to compare the MN-inducing activities of cigarettes in the direct exposure assay, even in the case of various experimental settings or different TPM amounts. MN-inducing activities of 2R4F under the ISO regimen seemed to be higher than those under HCI estimated by the TPM equivalent calculated values. PMID:19560909

  12. Cigarette smoking, nicotine and pregnancy.

    PubMed

    Haustein, K O

    1999-09-01

    Smoking cigarettes during pregnancy and nursing causes considerable health damage to the fetus and to the infant during the initial growth phase. A smoking mother puts her child at considerable risk, not only of higher incidence of spontaneous abortion, premature ablatio placentae and reduced weight at birth, but also of deformities (cheilognathopalatoschisis, deformed extremities, polycystic kidneys, aortopulmonary septum defects, gastroschisis, skull deformation, etc.). Development of the Down syndrome is the subject of some controversy. These types of damage are caused by the hypoxia followed by carboxyhemoglobinemia occurring during smoking and are also observed in CO poisonings that also result in deformities. Numerous infants die during the first months of life of the so-called sudden infant death syndrome (SIDS), which can also be caused by maternal smoking and passive smoking. The contribution of nicotine to such health damage is still unclear, especially because only animal trial data are available, the applicability of which to human beings is questionable. It can be said that studies to date have revealed no deformities confirmed as having been caused by nicotine. Cardiopulmonary disturbances resulting from changes in the regulation of dopaminergic receptors are under discussion, but have not yet reached the status of a pathogenic principle. On the whole, all child health complications arising during pregnancy can be attributed almost exclusively to tobacco combustion products including the CO formed. Passage of nicotine into human milk has been confirmed in nursing smokers; passive smoking by mother and child also raises nicotine and cotinine levels in the milk and in the infant. These findings could lead to a reconsideration of smoking withdrawal therapy for pregnant women. PMID:10507240

  13. [E-cigarettes also contain detrimental chemicals.

    PubMed

    Tøttenborg, Sandra Søgaard; Holm, Astrid Ledgaard; Wibholm, Niels Christoffer; Lange, Peter

    2014-09-01

    This article reviews studies dealing with the content of electronic (e-) cigarettes. Based on measurements of the e-juice, the inhaled and the exhaled vapour, it is sound to assume that smoking e-cigarettes might have much less detrimental health effects than smoking conventional cigarettes. However, propylene glycol and glycerine are abundant in e-cigarettes and although they are generally perceived as relatively harmless, the long-term effects of heavy exposure to these substances are unknown. PMID:25293843

  14. Cigarette smoke and lung cancer

    SciTech Connect

    Martonen, T.B.; Hofmann, W.; Lowe, J.E.

    1987-01-01

    Cigarette smoke has been implicated in a causal relationship with carcinoma of the lung. An intriguing feature of the disease is the site-selectivity with which bronchogenic cancer manifests itself; most cancers are detected in the main, lobar and segmental bronchi, perhaps specifically at airway bifurcations. The elevated risk of lung cancer to smokers may result from a complex interplay between smoking and exposure to ambient Rn progeny, including the promotional-effect role (as opposed to being the initiating event) of cigarette smoke in tumor development. It has been determined that smokers exposed to average indoor Rn progency levels receive surprisingly high doses at hot spots within bronchial bifurcations.

  15. Determination of Carbon Dioxide, Carbon Monoxide, and Methane Concentrations in Cigarette Smoke by Fourier Transform Infrared Spectroscopy

    ERIC Educational Resources Information Center

    Tan, T. L.; Lebron, G. B.

    2012-01-01

    The integrated absorbance areas of vibrational bands of CO[subscript 2], CO, and CH[subscript 4] gases in cigarette smoke were measured from Fourier transform infrared (FTIR) spectra to derive the partial pressures of these gases at different smoke times. The quantity of the three gas-phase components of cigarette smoke at different smoke times…

  16. Electronic cigarettes (E-cigarettes) are devices that deliver nicotine

    E-print Network

    Derisi, Joseph

    and converting to an aerosol a liquid mixture typically composed of propylene glycol, vegeta- ble glycerin, and carcinogens. Users inhale a heated propylene glycol or glycerin-based solution for which there are no long to smoke tobacco cigarettes (dual use). Because the effects of smoking on the heart, blood, and blood

  17. How do minimum cigarette price laws affect cigarette prices at the retail level?

    PubMed Central

    Feighery, E; Ribisl, K; Schleicher, N; Zellers, L; Wellington, N

    2005-01-01

    Objectives: Half of US states have minimum cigarette price laws that were originally passed to protect small independent retailers from unfair price competition with larger retailers. These laws prohibit cigarettes from being sold below a minimum price that is set by a formula. Many of these laws allow cigarette company promotional incentives offered to retailers, such as buydowns and master-type programmes, to be calculated into the formula. Allowing this provision has the potential to lower the allowable minimum price. This study assesses whether stores in states with minimum price laws have higher cigarette prices and lower rates of retailer participation in cigarette company promotional incentive programmes. Design: Retail cigarette prices and retailer participation in cigarette company incentive programmes in 2001 were compared in eight states with minimum price laws and seven states without them. New York State had the most stringent minimum price law at the time of the study because it excluded promotional incentive programmes in its price setting formula; cigarette prices in New York were compared to all other states included in the study. Results: Cigarette prices were not significantly different in our sample of US states with and without cigarette minimum price laws. Cigarette prices were significantly higher in New York stores than in the 14 other states combined. Conclusions: Most existing minimum cigarette price laws appear to have little impact on the retail price of cigarettes. This may be because they allow the use of promotional programmes, which are used by manufacturers to reduce cigarette prices. New York's strategy to disallow these types of incentive programmes may result in higher minimum cigarette prices, and should also be explored as a potential policy strategy to control cigarette company marketing practices in stores. Strict cigarette minimum price laws may have the potential to reduce cigarette consumption by decreasing demand through increased cigarette prices and reduced promotional activities at retail outlets. PMID:15791016

  18. [The application of FTIR spectroscopy to the analysis of cigarette smoke].

    PubMed

    Zhang, Jing; Wang, Liang-Yu; Zhang, Yun-Hong

    2008-04-01

    In the present paper, Fourier transform infrared aerosol flow tube (FTIR/AFT) and Fourier transform infrared attenuated total reflection (FTIR/ATR) were used as credible technologies to study the cigarette mainstream smoke and cigarette aerosol. In the experiment a convenient and effective setup was used to detect the sample. Before the cigarette was fired, the filter tip should be cut. Then the cigarette was connected with the sample chamber by a gluey tube. The mainstream cigarette smoke was imported by a vacuum pump. The technology of FTIR/AFT could get the information of the whole cigarette smoke including the chief gas phase and fine solid particles. A main peak at 1 230 cm(-1), contributed by the C-O stretching band, indicated the existence of hydroxybenzene. A acuate peak at 1 735 cm(-1) was contributed by the C=O stretching band of carboxyl acide. In addition, the strong peak of CO and CO2 gas can be resolved. Two relative strong peaks at 2 118 and 2 170 cm(-1), respectively were contributed by CO gas. As to the gas CO2, two strong peaks were observed at 2 343 and 2 362 cm(-1), respectively. While by taking the advantage of FTIR/ATR, we could obtain the information of cigarette aerosols deposit on the ZnSe substrate. The spectra of aerosol was correspondingly simple. The peak of CO disappeared and the peak intensity of CO2 decreased greatly. Therefore, using the AFT and ATR techniques could help to understand the formation and the composition of the production of the burning cigarette more clearly. Especially, by analyzing the change of some characteristic bands with time, the processes of the chemical reaction, volatility of some components and theform conglomeration of cigarette combustion were investigated. This has offered a new viewpoint in cigarette study that is different from conventional ideas, and is simple and rapid without pretreatment. PMID:18619307

  19. The effect of carrier gas flow rate and source cell temperature on low pressure organic vapor phase deposition simulation by direct simulation Monte Carlo method

    PubMed Central

    Wada, Takao; Ueda, Noriaki

    2013-01-01

    The process of low pressure organic vapor phase deposition (LP-OVPD) controls the growth of amorphous organic thin films, where the source gases (Alq3 molecule, etc.) are introduced into a hot wall reactor via an injection barrel using an inert carrier gas (N2 molecule). It is possible to control well the following substrate properties such as dopant concentration, deposition rate, and thickness uniformity of the thin film. In this paper, we present LP-OVPD simulation results using direct simulation Monte Carlo-Neutrals (Particle-PLUS neutral module) which is commercial software adopting direct simulation Monte Carlo method. By estimating properly the evaporation rate with experimental vaporization enthalpies, the calculated deposition rates on the substrate agree well with the experimental results that depend on carrier gas flow rate and source cell temperature. PMID:23674843

  20. Determination of Formaldehyde in Cigarette Smoke

    NASA Astrophysics Data System (ADS)

    Wong, Jon W.; Ngim, Kenley K.; Eiserich, Jason P.; Yeo, Helen C. H.; Shibamoto, Takayuki; Mabury, Scott A.

    1997-09-01

    Formaldehdye is considered a hazardous air pollutant with numerous sources that include environmental tobacco smoke (ETS). With the increasing interest regarding ETS and public health the measurement of formaldehyde readily lends itself to a laboratory experiment comparing methods of analysis. This experiment involves the collection, derivatization, extraction, and analysis of formaldehyde from cigarette smoke using two methods. Formaldehyde is extracted from smoke and derivitized with a solution of 2,4-DNPH with subsequent cleanup by solid-phase extraction and analysis of the hydrazone by HPLC with UV detection; additionally a solution of cysteamine yields the corresponding thiazolidine derivative that is liquid/liquid extracted and subsequently analyzed by either GC with NPD or FPD (sulfur mode). Reasonable agreement among the methods was obtained by lab demonstrators with spike recoveries yielding 94.7 + 6.8 (n=5) and 89.2 (n = 4) % for NPD and FPD, respectively while HPLC spiked recoveries were 83.6 + 3.2 (n = 5) %; mean class spike recoveries ranged from 80-100%. Student results (in mg/cigarette) from smoke samples were similar to literature values with 163.2 + 69.2 (n = 7) and 149.4 (n = 7) % for NPD and FPD, respectively; the HPLC result was significantly lower at 45.1 + 23.7(n = 7) with losses presumably due to hydrazone precipitating from the smoke extracted solution. Students particularly benefited from the "real world" nature of the analysis and the experience evaluating disparate methods of determining a common analyte.

  1. Carbonyl compounds generated from electronic cigarettes.

    PubMed

    Bekki, Kanae; Uchiyama, Shigehisa; Ohta, Kazushi; Inaba, Yohei; Nakagome, Hideki; Kunugita, Naoki

    2014-11-01

    Electronic cigarettes (e-cigarettes) are advertised as being safer than tobacco cigarettes products as the chemical compounds inhaled from e-cigarettes are believed to be fewer and less toxic than those from tobacco cigarettes. Therefore, continuous careful monitoring and risk management of e-cigarettes should be implemented, with the aim of protecting and promoting public health worldwide. Moreover, basic scientific data are required for the regulation of e-cigarette. To date, there have been reports of many hazardous chemical compounds generated from e-cigarettes, particularly carbonyl compounds such as formaldehyde, acetaldehyde, acrolein, and glyoxal, which are often found in e-cigarette aerosols. These carbonyl compounds are incidentally generated by the oxidation of e-liquid (liquid in e-cigarette; glycerol and glycols) when the liquid comes in contact with the heated nichrome wire. The compositions and concentrations of these compounds vary depending on the type of e-liquid and the battery voltage. In some cases, extremely high concentrations of these carbonyl compounds are generated, and may contribute to various health effects. Suppliers, risk management organizations, and users of e-cigarettes should be aware of this phenomenon. PMID:25353061

  2. The lingering question of menthol in cigarettes.

    PubMed

    Besaratinia, Ahmad; Tommasi, Stella

    2015-02-01

    Tobacco use is the single most important preventable cause of cancer-related deaths in the USA and many parts of the world. There is growing evidence that menthol cigarettes are starter tobacco products for children, adolescents, and young adults. Accumulating research also suggests that smoking menthol cigarettes reinforces nicotine dependence, impedes cessation, and promotes relapse. However, menthol cigarettes are exempt from the US Food and Drug Administration ban on flavored cigarettes due, in part, to the lack of empirical evidence describing the health consequences of smoking menthol cigarettes relative to regular cigarettes. Determining the biological effects of menthol cigarette smoke relative to regular cigarette smoke can clarify the health risks associated with the use of respective products and assist regulatory agencies in making scientifically based decisions on the development and evaluation of regulations on tobacco products to protect public health and to reduce tobacco use by minors. We highlight the inherent shortcomings of the conventional epidemiologic, clinical, and laboratory research on menthol cigarettes that have contributed to the ongoing debate on the public health impact of menthol in cigarettes. In addition, we provide perspectives on how future investigations exploiting state-of-the-art biomarkers of exposure and disease states can help answer the lingering question of menthol in cigarettes. PMID:25416451

  3. Attention, memory, and cigarette smoking

    Microsoft Academic Search

    Shirley C. Peeke; Harman V. S. Peeke

    1984-01-01

    Four experiments tested the effects of smoking one cigarette on verbal memory and attention. In Experiment I, 18 men were tested under three conditions in a repeated-measures design (pretrial smoking, posttrial smoking, no smoking). Recall of a 50-word list was tested immediately and after intervals of 10 and 45 min. Pretrial smoking resulted in improved recall 10 and 45 min

  4. CIGARETTE SMOKE AND LUNG CANCER

    EPA Science Inventory

    Cigarette smoke has been implicated in a causal relationship with carcinoma of the lung. An intriguing feature of the disease is the site-selectivity with which bronchogenic cancer manifests itself; most cancers are detected in the main, lobar and segmental bronchi, perhaps speci...

  5. Nicotine Content of Domestic Cigarettes, Imported Cigarettes and Pipe Tobacco in Iran

    PubMed Central

    Taghavi, Sahar; Khashyarmanesh, Zahra; Moalemzadeh-Haghighi, Hamideh; Nassirli, Hooriyeh; Eshraghi, Pyman; Jalali, Navid; Hassanzadeh-Khayyat, Mohammad

    2012-01-01

    Background There are many different kinds of cigarettes and tobacco available in the market. Since nicotine content of various brands of cigarettes are very variable, therefore evaluation and comparison of nicotine content of different brands of cigarettes is important. The goal of the present study was to determine and compare nicotine content of various domestic and imported cigarettes available in the area. Methods Fourteen popular imported brands and nine popular domestic brands of cigarettes and three available brands of tobaccos were investigated for the amounts of nicotine content. Nicotine was extracted from each cigarette and tobacco samples and was analyzed by high performance liquid chromatography (HPLC) method. Findings The amount of nicotine in each cigarette was from 6.17 to 12.65 mg (1.23 ± 0.15 percent of tobacco weight in each cigarette) in domestic cigarettes. It was between 7.17-28.86 mg (1.80 ± 0.25 percent of tobacco weight in each cigarette) for imported cigarette, and between 30.08- 50.89 mg (3.82 ± 1.11 percent) for the pipe nicotine. There was significant difference in nicotine amount between imported and domestic brands of cigarettes. There was also no significant difference in nicotine content between light and normal cigarettes in imported brands. Conclusion Nicotine content of all tested cigarettes, imported and domestic brands, were higher than the international standard. PMID:24494133

  6. Liquid chromatographic determination of benzo(a)pyrene in total particulate matter of cigarette smoke

    SciTech Connect

    Tomkins, B.A.; Jenkins, R.A.; Griest, W.H.; Reagan, R.R.; Holladay, S.K.

    1985-09-01

    The benzo(a)pyrene (BaP) delivery of reference and commercially available tobacco cigarettes, as well as reference and placebo marijuana cigarettes, is determined using a sequential liquid chromatographic/liquid chromatographic procedure. The total particulate matter of sample cigarette smoke is collected using a Cambridge filter pad, which is ultrasonically extracted with acetone. The resulting extract is filtered, then fractionated using semipreparative-scale normal phase liquid chromatography (LC). Quantitative determination is achieved using analytical-scale reverse phase LC equipped with a fluorescence detector. The method is precise (+/- 10-15% relative standard deviation) and yields 85% or better BaP recovery at the ng/cig. level. A single pad may be analyzed in 8 person-hours, while a more typical lot of 12 pads (6 pads each for 2 cigarette brands) may be analyzed in 10 person-days.

  7. Inert gas: Vapor mixtures in thermoacoustics

    Microsoft Academic Search

    William Victor Slaton

    2001-01-01

    An analytic solution of sound propagation in wet-walled tubes with a temperature gradient will be presented. The tube contains an inert gas-vapor mixture with a thin layer of condensed vapor coating the tube wall. The vapor phase condenses and evaporates from this layer during an acoustic cycle. This phased evaporation and condensation modifies traditional energy density and wave number equations.

  8. Hand rolling cigarette papers as the reference point for regulating cigarette fire safety

    PubMed Central

    Laugesen, M; Duncanson, M; Fraser, T; McClellan, V; Linehan, B; Shirley, R

    2003-01-01

    Aim: To compare the burning characteristics of the tobacco and paper of manufactured and hand rolled cigarettes, and set a fire safety standard of manufacture to largely reduce the fire risk from discarded cigarettes. Methods: (1) Cigarette extinction test of ignition strength: 40 cigarettes per brand, lit and placed on 15 layers of filter paper, in accordance with ASTM test standard E2187-02. (2) Citrate extracted by 0.1N hydrochloric acid from cigarette papers and from tobacco in manufactured cigarettes, the supernatant analysed by high performance liquid chromatography using ultraviolet visual light spectrophotometer. (3) Survey of 750 nationally representative adults age 18 years and over, by telephone, including 184 smokers. Materials: (a) New Zealand made Holiday, and Horizon, and US made Marlboro manufactured cigarettes; (b) US manufactured Merit with banded paper; (c) Holiday, Horizon and Marlboro hand rolling tobaccos, hand rolled in Rizla cigarette papers; (d) manufactured cigarettes as in (a), reconstructed using Rizla hand rolling cigarette papers. Results: 1. (a) For each brand of manufactured cigarettes, 40/40 burnt full length; (b) for Merit banded paper cigarettes 29/40 (73%) burnt full length; (c) for each brand of hand rolled cigarettes 0/40 burnt full length; (d) 0/40 manufactured cigarettes reconstructed with Rizla hand rolling paper burnt full length. 2. Citrate content: (a) In manufactured cigarette papers: 0.3–0.8 mg; in tobacco of manufactured cigarettes: Holiday 0, Horizon 0, Marlboro 8.8 mg; (b) Merit: in banded paper 0.418 mg; in tobacco 10.23 mg; (c) In hand rolled cigarettes: in the papers < 0.08 mg; in hand rolled tobacco 13.3–15.0 mg; (d) In hand rolling papers of reconstructed cigarettes: < 0.018 mg. 3. Requiring manufactured cigarettes to compulsorily self-extinguish when left unattended was supported by 67% of smokers, 61% of manufactured cigarette smokers, 82% of hand rolled smokers, and by 68% of non-smokers. Conclusion: The wrapping paper is a key determinant of whether or not unpuffed cigarettes burn their full length. Using international test methods, popular brands of manufactured cigarettes all burnt full length, but none did so when re-wrapped in hand rolling cigarette paper. This provides a ready-to-hand smoker acceptable standard for reducing ignition potential from manufactured cigarettes, as a basis for regulation or litigation. PMID:14660777

  9. AQUEOUS AND VAPOR PHASE MERCURY SORPTION BY INORGANIC OXIDE MATERIALS FUNCTIONALIZED WITH THIOLS AND POLY-THIOLS

    EPA Science Inventory

    The objective of the study is the development of sorbents where the sorption sites are highly accessible for the capture of mercury from aqueous and vapor streams. Only a small fraction of the equilibrium capacity is utilized for a sorbent in applications involving short residenc...

  10. A 118 nm vacuum ultraviolet laser/time-of-flight mass spectroscopic study of methanol and ethanol clusters in the vapor phase

    NASA Astrophysics Data System (ADS)

    Shi, Y. J.; Consta, S.; Das, A. K.; Mallik, B.; Lacey, D.; Lipson, R. H.

    2002-04-01

    Clusters of methanol and ethanol formed above neat liquid samples were entrained in a supersonic jet of helium and probed in the expansion using 118 nm vacuum ultraviolet laser single-photon ionization/time-of-flight (TOF) mass spectrometry. Almost every cluster ion observed in the TOF mass spectra could be represented by the formula H(ROH)n+, where R=CH3 or C2H5, and n=1-5. Formation of these species is attributed to a well-established ionization pathway where each protonated (n-1)-mer originates from its n-mer neutral parent. Signals in the TOF mass spectra due to the protonated trimers H(CH3OH)3+ and H(CH3CH2OH)3+ were found to be the most intense and provides direct evidence that these particular cluster ions are "magic-number" structures. The possible relationships between the observed ion data and the neutral cluster vapor phase distributions are discussed. In this context, methanol and ethanol vapor cluster distributions at 298.15 K and at several pressures?the equilibrium vapor pressure were computed using the grand canonical Monte Carlo and molecular dynamics techniques. Lastly, differences between these experiments and the results of bimolecular reaction studies are discussed.

  11. Red to blue wavelength emission of N-polar (000\\bar{1}) InGaN light-emitting diodes grown by metalorganic vapor phase epitaxy

    NASA Astrophysics Data System (ADS)

    Shojiki, Kanako; Tanikawa, Tomoyuki; Choi, Jung-Hun; Kuboya, Shigeyuki; Hanada, Takashi; Katayama, Ryuji; Matsuoka, Takashi

    2015-06-01

    N-polar (000\\bar{1}) (?c-plane) InGaN light-emitting diodes with emission wavelengths ranging from blue to green to red were fabricated on a c-plane sapphire substrate by metalorganic vapor phase epitaxy. The optimization of growth conditions for ?c-plane InGaN/GaN multiple quantum wells was performed. As a result, the extension of the emission wavelength from 444 to 633 nm under a constant current of 20 mA was achieved by changing the growth temperature of quantum wells from 880 to 790 °C.

  12. Stability of In(x) Ga(1-x) N\\/In(y) Ga(1-y) N multiple quantum well structures during growth by metalorganic vapor phase epitaxy

    Microsoft Academic Search

    Jeffrey Craig Ramer

    1998-01-01

    InxGa1-xN\\/InyGa1-yN multiple quantum well (MQW) structures have been grown by metalorganic vapor phase epitaxy under growth conditions with and without H2. The elimination of added H2 from the growth ambient is observed to significantly increase the InN incorporation into InGaN across the range of growth temperatures studied. Specular x-ray reflectivity as a characterization tool for the InGaN MQW structures is

  13. Pulsed and continuous-mode operation at high temperature of strained quantum-cascade lasers grown by metalorganic vapor phase epitaxy

    Microsoft Academic Search

    L. Diehl; D. Bour; S. Corzine; J. Zhu; G. Höfler; B. G. Lee; C. Y. Wang; M. Troccoli; F. Capasso

    2006-01-01

    We present the pulsed operation at room temperature of different strained InGaAs\\/AlInAs quantum-cascade lasers grown by low-pressure metalorganic vapor-phase epitaxy. Devices based on a bound-to-continuum transition design have threshold current densities in pulsed mode as low as 1.84 kA\\/cm2 at 300 K. Identical lasers grown at higher rate (0.5 nm\\/s) also have threshold current densities lower than 2 kA\\/cm2 at

  14. Effect of Growth Interruption on Surface Recombination Velocity in GaInAsSb/AlGaAsSb Heterostructures Grown by Organometallic Vapor Phase Epitaxy

    SciTech Connect

    CA Wang; DA Shiau; D Donetsky; S Anikeev; G Belenky; S Luryi

    2004-04-29

    The effects of growth interruption on the quality of GaInAsSb/AlGaAsSb heterostructures grown by organometallic vapor phase epitaxy are reported. In-situ reflectance monitoring and ex-situ characterization by high-resolution x-ray diffraction, 4K photoluminescence (PL), and time-resolved PL indicate that GaInAsSb is extremely sensitive to growth interruption time as well as the ambient atmosphere during interruption. By optimizing the interruption sequence, surface recombination velocity as low as 20 cm/s was achieved for GaInAsSb/AlGaAsSb double heterostructures.

  15. On the Mechanism of Dislocation and Stacking Fault Formation in a-plane GaN Films Grown by Hydride Vapor Phase Epitaxy

    NASA Astrophysics Data System (ADS)

    Kröger, R.; Paskova, T.; Rosenauer, A.; Hommel, D.; Monemar, B.; Fini, P.; Haskell, B.; Speck, J.; Nakamura, S.

    2007-04-01

    Non-polar a-plane GaN films grown by hydride vapor phase epitaxy were studied by means of transmission electron microscopy in order to elucidate defect formation mechanisms. The typical defects found were I1 basal plane stacking faults and Frank-Shockley partials. Moreover, prismatic stacking faults could be identified, which were lying on the (01-10) and (11-23) planes forming closed domains and occasionally containing rectangular voids, which were found to be nanopipes originating at the interface with the substrate. The energetics of the partial dislocation formation mechanism is discussed.

  16. A novel route to produce thymol by vapor phase reaction of m-cresol with isopropyl acetate over Al-MCM-41 molecular sieves

    Microsoft Academic Search

    K. Shanmugapriya; M. Palanichamy; Banumathi Arabindoo; V. Murugesan

    2004-01-01

    Mesoporous Al-MCM-41 (Si\\/Al = 55 and 104) and Al,Zn-MCM-41 (Si\\/(Al+Zn)=52) molecular sieves were synthesized hydrothermally. The materials were characterized by XRD, TGA, TPD (pyridine), ICP-AES, nitrogen sorption, and FT-IR techniques. The catalytic performance of these materials was examined in the vapor phase alkylation of m-cresol with isopropyl acetate. The products obtained were thymol, isothymol, 2-isopropyl-5-methylphenyl acetate (2-I-5-MPA), and isopropyl-3-methylphenyl ether

  17. Tunable generation and adsorption of energetic compounds in the vapor phase at trace levels: a tool for testing and developing sensitive and selective substrates for explosive detection.

    PubMed

    Bonnot, Karine; Bernhardt, Pierre; Hassler, Dominique; Baras, Christian; Comet, Marc; Keller, Valérie; Spitzer, Denis

    2010-04-15

    Among various methods for landmine detection, as well as soil and water pollution monitoring, the detection of explosive compounds in air is becoming an important and inevitable challenge for homeland security applications, due to the threatening increase in terrorist explosive bombs used against civil populations. However, in the last case, there is a crucial need for the detection of vapor phase traces or subtraces (in the ppt range or even lower). A novel and innovative generator for explosive trace vapors was designed and developed. It allowed the generation of theoretical concentrations as low as 0.24 ppq for hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in air according to Clapeyron equations. The accurate generation of explosive concentrations at subppt levels was verified for RDX and 2,4,6-trinitrotoluene (TNT) using a gas chromatograph coupled to an electron capture detector (GC-ECD). First, sensing material experiments were conducted on a nanostructured tungsten oxide. The sensing efficiency of this material determined as its adsorption capacity toward 54 ppb RDX was calculated to be five times higher than the sensing efficiency of a 54 ppb TNT vapor. The material sensing efficiency showed no dependence on the mass of material used. The results showed that the device allowed the calibration and discrimination between materials for highly sensitive and accurate sensing detection in air of low vapor pressure explosives such as TNT or RDX at subppb levels. The designed device and method showed promising features for nanosensing applications in the field of ultratrace explosive detection. The current perspectives are to decrease the testing scale and the detection levels to ppt or subppt concentration of explosives in air. PMID:20345122

  18. Role of Co-Vapors in Vapor Deposition Polymerization

    NASA Astrophysics Data System (ADS)

    Lee, Ji Eun; Lee, Younghee; Ahn, Ki-Jin; Huh, Jinyoung; Shim, Hyeon Woo; Sampath, Gayathri; Im, Won Bin; Huh, Yang–Il; Yoon, Hyeonseok

    2015-02-01

    Polypyrrole (PPy)/cellulose (PPCL) composite papers were fabricated by vapor phase polymerization. Importantly, the vapor-phase deposition of PPy onto cellulose was assisted by employing different co-vapors namely methanol, ethanol, benzene, water, toluene and hexane, in addition to pyrrole. The resulting PPCL papers possessed high mechanical flexibility, large surface-to-volume ratio, and good redox properties. Their main properties were highly influenced by the nature of the co-vaporized solvent. The morphology and oxidation level of deposited PPy were tuned by employing co-vapors during the polymerization, which in turn led to change in the electrochemical properties of the PPCL papers. When methanol and ethanol were used as co-vapors, the conductivities of PPCL papers were found to have improved five times, which was likely due to the enhanced orientation of PPy chain by the polar co-vapors with high dipole moment. The specific capacitance of PPCL papers obtained using benzene, toluene, water and hexane co-vapors was higher than those of the others, which is attributed to the enlarged effective surface area of the electrode material. The results indicate that the judicious choice and combination of co-vapors in vapor-deposition polymerization (VDP) offers the possibility of tuning the morphological, electrical, and electrochemical properties of deposited conducting polymers.

  19. HOW DO SMOKERS RESPOND TO CIGARETTE TAXES? EVIDENCE FROM CHINA'S CIGARETTE INDUSTRY.

    PubMed

    Liu, Hong; Rizzo, John A; Sun, Qi; Wu, Fang

    2014-07-18

    This paper examines how Chinese smokers respond to tax-driven cigarette price increases by estimating a discrete choice model of demand for differentiated products, using annual nationwide brand-level cigarette sales data in China from 2005 to 2010. We allow for substitution between different cigarette brands and also incorporate key features of rational addiction theory into the model. Results show that the average own-price elasticity of demand for cigarettes at the brand level is -0.807, and the overall price elasticity of cigarettes at the market level is -0.488 in China. We find tax-induced substitution toward low-price cigarettes as well as high-tar cigarettes and that tax hikes encourage within-class substitution more than across-class substitution. These results have important policy implications for the potential effects of cigarette taxation. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25044632

  20. The emerging phenomenon of electronic cigarettes.

    PubMed

    Caponnetto, Pasquale; Campagna, Davide; Papale, Gabriella; Russo, Cristina; Polosa, Riccardo

    2012-02-01

    The need for novel and more effective approaches to tobacco control is unquestionable. The electronic cigarette is a battery-powered electronic nicotine delivery system that looks very similar to a conventional cigarette and is capable of emulating smoking, but without the combustion products accountable for smoking's damaging effects. Smokers who decide to switch to electronic cigarettes instead of continuing to smoke would achieve large health gains. The electronic cigarette is an emerging phenomenon that is becoming increasingly popular with smokers worldwide. Users report buying them to help quit smoking, to reduce cigarette consumption, to relieve tobacco withdrawal symptoms due to workplace smoking restrictions and to continue to have a 'smoking' experience but with reduced health risks. The focus of the present article is the health effects of using electronic cigarettes, with consideration given to the acceptability, safety and effectiveness of this product to serve as a long-term substitute for smoking or as a tool for smoking cessation. PMID:22283580

  1. The health effects of menthol cigarettes as compared to non-menthol cigarettes

    Microsoft Academic Search

    Allison C Hoffman

    2011-01-01

    Since the 1920s, menthol has been added to cigarettes and used as a characterizing flavor. The health effects of cigarette\\u000a smoking are well documented, however the health effects of menthol cigarettes as compared to non-menthol cigarettes is less\\u000a well studied. This review discusses menthol’s effects on 1) biomarkers of tobacco smoke exposure, 2) toxicity and cellular\\u000a effects, 3) lung function

  2. Electronic cigarette use and harm reversal: emerging evidence in the lung.

    PubMed

    Polosa, Riccardo

    2015-01-01

    Electronic cigarettes (ECs) have been rapidly gaining ground on conventional cigarettes due to their efficiency in ceasing or reducing tobacco consumption, competitive prices, and the perception of them being a much less harmful smoking alternative. Direct confirmation that long-term EC use leads to reductions in smoking-related diseases is not available and it will take a few decades before the tobacco harm reduction potential of this products is firmly established. Nonetheless, it is feasible to detect early changes in airway function and respiratory symptoms in smokers switching to e-vapor. Acute investigations do not appear to support negative respiratory health outcomes in EC users and initial findings from long-term studies are supportive of a beneficial effect of EC use in relation to respiratory outcomes. The emerging evidence that EC use can reverse harm from tobacco smoking should be taken into consideration by regulatory authorities seeking to adopt proportional measures for the e-vapor category. PMID:25857426

  3. Synthesis and properties of magnetic fluid based on iron nanoparticles prepared by a vapor-phase condensation process

    Microsoft Academic Search

    Ji-Hun Yu; Dong-Won Lee; Byoung-Kee Kim; Taesuk Jang

    2006-01-01

    Magnetic fluid containing metallic iron nanoparticles was successfully fabricated in this work. The iron nanoparticles were synthesized by chemical vapor condensation process and then dispersed in water-base solution (pH 11) with oleic acid as surfactant. More than 80% of iron nanoparticles were fully dispersed in the fluid and remained stable without any further oxidation over 200h. Both the iron nanoparticles

  4. Electronic cigarettes: product characterisation and design considerations

    PubMed Central

    Brown, Christopher J; Cheng, James M

    2014-01-01

    Objective To review the available evidence regarding electronic cigarette (e-cigarette) product characterisation and design features in order to understand their potential impact on individual users and on public health. Methods Systematic literature searches in 10 reference databases were conducted through October 2013. A total of 14 articles and documents and 16 patents were included in this analysis. Results Numerous disposable and reusable e-cigarette product options exist, representing wide variation in product configuration and component functionality. Common e-cigarette components include an aerosol generator, a flow sensor, a battery and a nicotine-containing solution storage area. e-cigarettes currently include many interchangeable parts, enabling users to modify the character of the delivered aerosol and, therefore, the product's ‘effectiveness’ as a nicotine delivery product. Materials in e-cigarettes may include metals, rubber and ceramics. Some materials may be aerosolised and have adverse health effects. Several studies have described significant performance variability across and within e-cigarette brands. Patent applications include novel product features designed to influence aerosol properties and e-cigarette efficiency at delivering nicotine. Conclusions Although e-cigarettes share a basic design, engineering variations and user modifications result in differences in nicotine delivery and potential product risks. e-cigarette aerosols may include harmful and potentially harmful constituents. Battery explosions and the risks of exposure to the e-liquid (especially for children) are also concerns. Additional research will enhance the current understanding of basic e-cigarette design and operation, aerosol production and processing, and functionality. A standardised e-cigarette testing regime should be developed to allow product comparisons. PMID:24732162

  5. Teen Use of E-Cigarettes, Hookahs Way Up

    MedlinePLUS

    ... age. That includes e-cigarettes, hookahs, cigarettes or cigars, the researchers cautioned. Young brains are still developing, ... to expand its reach to include e-cigarettes, cigars and hookahs. An FDA proposal also recommends a ...

  6. Background Paper on E-cigarettes (Electronic Nicotine Delivery Systems)

    E-print Network

    Grana, Rachel PhD, MPH; Benowitz, Neal MD; Glantz, Stanton A. PhD

    2013-01-01

    cigarette retail websites encouraged the use of the productswebsites and include instructions for taking action against bills designed to include e-cigarette useof nicotine use on cognition. Some e-cigarette websites (as

  7. Background Paper on E-cigarettes (Electronic Nicotine Delivery Systems)

    E-print Network

    Grana, Rachel PhD, MPH; Benowitz, Neal MD; Glantz, Stanton A. PhD

    2013-01-01

    pose less lung cancer risk than fewer cigarettes per day forin lung cancer mortality with greater duration of cigaretteLung cancer mortality in relation to age, duration of smoking, and daily cigarette

  8. (abstract) Experimental and Modeling Studies of the Exchange Current at the Alkali Beta'-Alumina/Porous Electrode/Alkali Metal Vapor Three Phase Boundary

    NASA Technical Reports Server (NTRS)

    Williams, R. M.; Jeffries-Nakamura, B.; Ryan, M. A.; Underwood, M. L.; O'Connor, D.; Kikkert, S.

    1993-01-01

    The microscopic mechanism of the alkali ion-electron recombination reaction at the three phase boundary zone formed by a porous metal electrode in the alkali vapor on the surface of an alkali beta'-alumina solid electrolyte (BASE) ceramic has been studied by comparison of the expected rates for the three simplest reaction mechanisms with known temperature dependent rate data; and the physical parameters of typical porous metal electrode/BASE/alkali metal vapor reaction zones. The three simplest reactions are tunneling of electrons from the alkali coated electrode to a surface bound alkali metal ion; emission of an electron from the electrode with subsequent capture by a surface bound alkali metal ion; and thermal emission of an alkali cation from the BASE and its capture on the porous metal electrode surface where it may recombine with an electron. Only the first reaction adequately accounts for both the high observed rate and its temperature dependence. New results include crude modeling of simple, one step, three phase, solid/solid/gas electrochemical reaction.

  9. Measurement of two-phase refrigerant liquid-vapor mass flow rate. Part 3: Combined turbine and venturi meters and comparison with other methods

    SciTech Connect

    Abdul-Razzak, A.; Shoukri, M.; Chang, J.S. [McMaster Univ., Hamilton, Ontario (Canada)

    1995-12-31

    In determining the mass flow rate of refrigerant R-134a liquid-vapor in a horizontal tube, a simple method that combines the outputs of venturi and turbine flowmeters, without the need for void fraction or quality measurement, was examined. The results showed that this method can be used to determine the two-phase mass flow rate relatively well for the entire quality range. This method was particularly accurate in determining the mass flow rate data in the high-quality range, i.e., in annular flow. Moreover, this method also showed a reasonable accuracy in predicting the void fraction. The use of this method in predicting the two-phase mass flow rate was compared with the use of a venturi meter or a turbine flowmeter and a void fraction meter. The comparison showed that at qualities higher than 0.6, the present method, which combines the output signals of both the turbine and venturi meters, is superior to those that use one of the flow signals and void fraction and/or quality measurement. At lower qualities, the present method still offers a fairly accurate technique for measuring the liquid-vapor refrigeration mass flow rate.

  10. Interface reactions and Kirkendall voids in metal organic vapor-phase epitaxy grown Cu(In ,Ga)Se2 thin films on GaAs

    NASA Astrophysics Data System (ADS)

    Lei, C. H.; Rockett, A. A.; Robertson, I. M.; Papathanasiou, N.; Siebentritt, S.

    2006-12-01

    Cu(In1-xGax)Se2 (CIGS) films were grown on (001) GaAs at 570 or 500°C by means of metal organic vapor-phase epitaxy. All films were Cu-rich [Cu /(In+Ga)>1] with pseudomorphic Cu2Se second phase particles found only on the growth surface. During growth, diffusion of Ga from the substrate and vacancies generated by the formation of CIGS from Cu2Se at the surface occurred. The diffusion processes lead to the formation of Kirkendall voids at the GaAs/CIGS interface. Transmission electron microscopy and nanoprobe energy dispersive spectroscopy were used to analyze the diffusion and void formation processes. The diffusivity of Ga in CIGS was found to be relatively low. This is postulated to be due to a comparatively low concentration of point defects in the epitaxial films. A reaction model explaining the observed profiles and voids is proposed.

  11. Influence of cigarette smoking on the toxicokinetics of toluene in humans

    Microsoft Academic Search

    Ewa Wigaeus Hjelm; Per H. Näslund; Maria Wallén

    1988-01-01

    To study the influence of cigarette smoking on the toxicokinetics of toluene, 10 habitual smokers who intended to stop smoking were exposed to toluene vapor (3.2 mmol\\/m, 4 h) at three different exposure occasions: (I) while the smoking habit was still ongoing, and (II and III) 1 and 3–4 wk, respectively, after the day at which the smoking habit was

  12. Separation and quantitation of monovalent anionic and cationic species in mainstream cigarette smoke aerosols by high-performance ion chromatography.

    PubMed

    Nanni, E J; Lovette, M E; Hicks, R D; Fowler, K W; Borgerding, M F

    1990-08-01

    A simple method has been developed to separate and quantitate monovalent ionic species in mainstream cigarette smoke aerosols based on ion chromatography (IC) with conductivity detection. The method entails collecting the smoke aerosol particulate phase by electrostatic precipitation, dissolving the smoke condensate in methanol (MeOH), and separating the ionic species on either a cation- or anion-exchange column. The method has been applied to the analysis of smoke aerosols from two cigarettes, 1R4F Kentucky Reference cigarettes and a new cigarette that heats but does not burn tobacco. The predominant cations in smoke aerosols from 1R4F Kentucky Reference and the new cigarettes are sodium (Na+), ammonium (NH4+), and potassium (K+) ions; the predominant anions are acetate (AcO-) and formate (HCOO-). Trace amounts of chloride (Cl-), nitrite (NO2-), and nitrate (NO3-) ions are also present. PMID:2229270

  13. Amorphous and crystalline aerosol particles interacting with water vapor: conceptual framework and experimental evidence for restructuring, phase transitions and kinetic limitations

    NASA Astrophysics Data System (ADS)

    Mikhailov, E.; Vlasenko, S.; Martin, S. T.; Koop, T.; Pöschl, U.

    2009-12-01

    Interactions with water are crucial for the properties, transformation and climate effects of atmospheric aerosols. Here we present a conceptual framework for the interaction of amorphous aerosol particles with water vapor, outlining characteristic features and differences in comparison to crystalline particles. We used a hygroscopicity tandem differential mobility analyzer (H-TDMA) to characterize the hydration and dehydration of crystalline ammonium sulfate, amorphous oxalic acid and amorphous levoglucosan particles (diameter ~100 nm, relative humidity 5-95% at 298 K). The experimental data and accompanying Köhler model calculations provide new insights into particle microstructure, surface adsorption, bulk absorption, phase transitions and hygroscopic growth. The results of these and related investigations lead to the following conclusions: (1) Many organic substances, including carboxylic acids, carbohydrates and proteins, tend to form amorphous rather than crystalline phases upon drying of aqueous solution droplets. Depending on viscosity and microstructure, the amorphous phases can be classified as glasses, rubbers, gels or viscous liquids. (2) Amorphous organic substances tend to absorb water vapor and undergo gradual deliquescence and hygroscopic growth at lower relative humidity than their crystalline counterparts. (3) In the course of hydration and dehydration, certain organic substances can form rubber- or gel-like structures (supramolecular networks) and undergo transitions between swollen and collapsed network structures. (4) Organic gels or (semi-)solid amorphous shells (glassy, rubbery, ultra-viscous) with low molecular diffusivity can kinetically limit the uptake and release of water and may influence the hygroscopic growth and activation of aerosol particles as cloud condensation nuclei (CCN) and ice nuclei (IN). Moreover, (semi-)solid amorphous phases may influence the uptake of gaseous photo-oxidants and the chemical transformation and aging of atmospheric aerosols. (5) The shape and porosity of amorphous and crystalline particles formed upon dehydration of aqueous solution droplets depend on chemical composition and drying conditions. The apparent volume void fractions of particles with highly porous structures can range up to ~50% or more (xerogels, aerogels). (6) For efficient description of water uptake and phase transitions of aerosol particles, we propose not to limit the terms deliquescence and efflorescence to equilibrium phase transitions of crystalline substances. Instead we propose generalized definitions according to which amorphous and crystalline components can undergo gradual or prompt, partial or full deliquescence or efflorescence. We suggest that (semi-)solid amorphous phases may be important not only in the upper atmosphere as suggested in recent studies of glass formation at low temperatures. Depending on relative humidity, (semi-)solid phases and moisture-induced glass transitions may also play a role in gas-particle interactions at ambient temperatures in the lower atmosphere.

  14. Temperature-dependent phase transition and desorption free energy of sodium dodecyl sulfate at the water/vapor interface: approaches from molecular dynamics simulations.

    PubMed

    Chen, Meng; Lu, Xiancai; Liu, Xiandong; Hou, Qingfeng; Zhu, Youyi; Zhou, Huiqun

    2014-09-01

    Adsorption of surfactants at the water/vapor interface depends upon their chemical potential at the interface, which is generally temperature-dependent. Molecular dynamics simulations have been performed to reveal temperature influences on the microstructure of sodium dodecyl sulfate (SDS) molecule adsorption layer. At room temperature, SDS molecules aggregate at the interface, being in a liquid-expanded phase, whereas they tend to spread out and probably transit to a gaseous phase as the temperature increases to above 318 K. This phase transition has been confirmed by the temperature-dependent changes in two-dimensional array, tilt angles, and immersion depths to the aqueous phase of SDS molecules. The aggregation of SDS molecules accompanies with larger immersion depths, more coordination of Na(+) ions, and less coordination of water. Desorption free energy profiles show that higher desorption free energy appears for SDS molecules at the aggregate state at low temperatures, but no energy barrier is observed. The shapes of desorption free energy profiles depend upon the distribution of SDS at the interface, which, in turn, is related to the phase state of SDS. Our study sheds light on the development of adsorption thermodynamics and kinetics theories. PMID:25127193

  15. E-cigarettes and conventional cigarette use among US adolescents: A cross-sectional study

    PubMed Central

    Dutra, Lauren M.; Glantz, Stanton A.

    2014-01-01

    Importance E-cigarette use is increasing rapidly among adolescents and e-cigarettes are currently unregulated. Objective Examine e-cigarette use and conventional cigarette smoking. Design Cross-sectional analyses of survey data. Setting 2011 and 2012 National Youth Tobacco Surveys (NYTS) Participants Representative sample of US middle and high school students in 2011 (n=17,353) and 2012 (n=22,529) Exposures Ever and current e-cigarette use Main outcome measures Experimentation with, ever, and current smoking; smoking abstinence Results In pooled analyses, among cigarette experimenters (?1 puff), ever e-cigarette use was associated with higher odds of ever smoking cigarettes (?100 cigarettes; OR= 6.31, 95% CI [5.39-7.39) and current cigarette smoking (OR=5.96 [5.67-6.27]). Current e-cigarette use was positively associated with ever smoking cigarettes (OR=7.42 [5.63-9.79]) and current cigarette smoking (OR= 7.88 [6.01-10.32]. In 2011, current cigarette smokers who had ever used e-cigarettes were more likely to intend to quit smoking within the next year (OR=1.53 [1.03-2.28]). Among experimenters with conventional cigarettes, ever use of e-cigarettes was also associated with lower 30-day (OR=0.24 [0.21-0.28]), 6-month (OR=0.24 [0.21-0.28]), and 1-year (OR=0.25 [0.21-0.30]) abstinence from cigarettes. Current e-cigarette use was also associated with lower 30-day (OR=0.11 [0.08-0.15]), 6-month (OR=0.11 [0.08-0.15]), and 1-year (OR=0.12 [0.07-0.18]) abstinence. Among ever smokers of cigarettes (?100 cigarettes), ever e-cigarette use was negatively associated with 30-day (OR=0.61, [0.42-0.89]), 6-month (OR=0.53, [0.33-0.83]) and one-year (OR=0.32 [0.18-0.56) abstinence from conventional cigarettes. Current e-cigarette use was also negatively associated with 30-day (OR=0.35 [0.18-0.69]), 6-month (OR=0.30 [0.13-0.68]), and one-year (OR=0.34 [0.13-0.87]) abstinence. Conclusions E-cigarette use was associated with higher odds of ever or current cigarette smoking, higher odds of established smoking, higher odds of planning to quit smoking among current smokers, and, among experimenters, lower odds of abstinence from conventional cigarettes. Relevance Results suggest e-cigarette use does not discourage, and may encourage, conventional cigarette use among US adolescents. PMID:24604023

  16. Cigarette Litter: Smokers’ Attitudes and Behaviors

    PubMed Central

    Rath, Jessica M.; Rubenstein, Rebecca A.; Curry, Laurel E.; Shank, Sarah E.; Cartwright, Julia C.

    2012-01-01

    Cigarette butts are consistently the most collected items in litter clean-up efforts, which are a costly burden to local economies. In addition, tobacco waste may be detrimental to our natural environment. The tobacco industry has conducted or funded numerous studies on smokers’ littering knowledge and behavior, however, non-industry sponsored research is rare. We sought to examine whether demographics and smokers’ knowledge and beliefs toward cigarette waste as litter predicts littering behavior. Smokers aged 18 and older (n = 1,000) were interviewed about their knowledge and beliefs towards cigarette waste as litter. Respondents were members of the Research Now panel, an online panel of over three million respondents in the United States. Multivariate logistic regressions were conducted to determine factors significantly predictive of ever having littered cigarette butts or having littered cigarette butts within the past month (p-value < 0.05). The majority (74.1%) of smokers reported having littered cigarette butts at least once in their life, by disposing of them on the ground or throwing them out of a car window. Over half (55.7%) reported disposing of cigarette butts on the ground, in a sewer/gutter, or down a drain in the past month. Those who did not consider cigarette butts to be litter were over three and half times as likely to report having ever littered cigarette butts (OR = 3.68, 95%CI = 2.04, 6.66) and four times as likely to have littered cigarette butts in the past month (OR = 4.00, 95%CI = 2.53, 6.32). Males were significantly more likely to have littered cigarette butts in the past month compared to females (OR = 1.49, 95%CI = 1.14, 1.94). Holding the belief that cigarette butts are not litter was the only belief in this study that predicted ever or past-month littering of cigarette waste. Messages in anti-cigarette-litter campaigns should emphasize that cigarette butts are not just litter but are toxic waste and are harmful when disposed of improperly. PMID:22829798

  17. Effectiveness and tolerability of electronic cigarette in real-life: a 24-month prospective observational study.

    PubMed

    Polosa, Riccardo; Morjaria, Jaymin B; Caponnetto, Pasquale; Campagna, Davide; Russo, Cristina; Alamo, Angela; Amaradio, MariaDomenica; Fisichella, Alfredo

    2014-08-01

    Electronic cigarettes (e-Cigarette) are battery-operated devices designed to vaporise nicotine that may aid smokers to quit or reduce their cigarette consumption. Research on e-Cigarettes is urgently needed to ensure that the decisions of regulators, healthcare providers and consumers are evidence based. Here we assessed long-term effectiveness and tolerability of e-Cigarette used in a 'naturalistic' setting. This prospective observational study evaluated smoking reduction/abstinence in smokers not intending to quit using an e-Cigarette ('Categoria'; Arbi Group, Italy). After an intervention phase of 6 months, during which e-Cigarette use was provided on a regular basis, cigarettes per day (cig/day) and exhaled carbon monoxide (eCO) levels were followed up in an observation phase at 18 and 24 months. Efficacy measures included: (a) ?50% reduction in the number of cig/day from baseline, defined as self-reported reduction in the number of cig/day (?50%) compared to baseline; (b) ?80% reduction in the number of cig/day from baseline, defined as self-reported reduction in the number of cig/day (?80%) compared to baseline; (c) abstinence from smoking, defined as complete self-reported abstinence from tobacco smoking (together with an eCO concentration of ?10 ppm). Smoking reduction and abstinence rates were computed, and adverse events reviewed. Of the 40 subjects, 17 were lost to follow-up at 24 months. A >50% reduction in the number of cig/day at 24 months was shown in 11/40 (27.5%) participants with a median of 24 cig/day use at baseline decreasing significantly to 4 cig/day (p = 0.003). Smoking abstinence was reported in 5/40 (12.5%) participants while combined >50% reduction and smoking abstinence was observed in 16/40 (40%) participants at 24 months. Five subjects stopped e-Cigarette use (and stayed quit), three relapsed back to tobacco smoking and four upgraded to more performing products by 24 months. Only some mouth irritation, throat irritation, and dry cough were reported. Withdrawal symptoms were uncommon. Long-term e-Cigarette use can substantially decrease cigarette consumption in smokers not willing to quit and is well tolerated. ( http://ClinicalTrials.govnumberNCT01195597 ). PMID:23873169

  18. Size-Dependent Phase Diagram of Nanoscale Alloy Drops Used in Vapor-Liquid-Solid Growth of Semiconductor Nanowires

    SciTech Connect

    Sutter, E.; Sutter, P.

    2010-07-19

    We use in situ observations during high-temperature transmission electron microscopy to quantify the exchange of semiconductor material between Au-Ge vapor-liquid-solid seed drops and Ge nanowires (NWs). By performing simultaneous measurements under identical conditions on arrays with systematic variations in NW diameter, we establish the nanoscale size dependence of the temperature-dependent equilibrium composition of the Au-Ge binary alloy. We find a significantly enhanced Ge solubility for drops on thin NWs compared to thicker ones. The controlled modification of the surface of the NW by an ordered carbon shell leads to drastic changes in the solubility.

  19. Size-dependent phase diagram of nanoscale alloy drops used in vapor--liquid--solid growth of semiconductor nanowires.

    PubMed

    Sutter, Eli A; Sutter, Peter W

    2010-08-24

    We use in situ observations during high-temperature transmission electron microscopy to quantify the exchange of semiconductor material between Au-Ge vapor--liquid--solid seed drops and Ge nanowires (NWs). By performing simultaneous measurements under identical conditions on arrays with systematic variations in NW diameter, we establish the nanoscale size dependence of the temperature-dependent equilibrium composition of the Au-Ge binary alloy. We find a significantly enhanced Ge solubility for drops on thin NWs compared to thicker ones. The controlled modification of the surface of the NW by an ordered carbon shell leads to drastic changes in the solubility. PMID:20731466

  20. Safety assessment of mainstream smoke of herbal cigarette.

    PubMed

    Bak, Jong Ho; Lee, Seung Min; Lim, Heung Bin

    2015-03-01

    Owing to the increase in price of cigarettes in Korea, herbal cigarettes have received increasing attention as a non-smoking aid; however, its safety has hardly been studied. We analyzed some of the toxic components in the mainstream smoke of herbal cigarettes, performed a mutagenicity test on smoke condensates for safety assessment, and compared the results with the corresponding values of a general cigarette with the same tar content. Herbal cigarette "A" was smoked using automatic smoking machine under ISO conditions in a manner similar to general cigarette "T". The tar content measured was higher than that inscribed on the outside of a package. The mainstream smoke of herbal cigarette "A" did not contain detectable levels of tobacco-specific nitrosamines and nicotine. Carbon monoxide and benzo(?)pyrene contents in herbal cigarette "A" were higher than those in the general cigarette "T". The phenolic contents such as hydroquinone, resorcinol, and catechol in herbal cigarette "A" were higher than those in the general cigarette "T", but cresol contents in herbal cigarette "A" were lower than those in the general cigarette "T". The content of aromatic amines such as 4-aminobiphenyl in herbal cigarette "A" was higher than that in the general cigarette "T"; however, this difference was not statistically significant. On the other hand, 1-aminonaphthalene, 2-aminonaphthalene, and 3-aminobiphenyl contents in herbal cigarette "A" were lower than those in the general cigarette "T". The smoke condensates of herbal cigarette "A" exhibited a higher mutagenic potential than the condensates from the general cigarette "T" at the same concentration. We concluded that the mainstream smoke of herbal cigarette contains some toxic components, the smoke condensates of herbal cigarettes are mutagenic similar to general cigarette because of combustion products, and that the evaluation of the chemical and biological safety of all types of herbal cigarettes available on the market. PMID:25874032