These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

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

SciTech Connect

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.

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

1985-01-01

2

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

PubMed

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

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

2015-01-01

3

Vapor phase pyrolysis  

NASA Technical Reports Server (NTRS)

The vapor phase pyrolysis process is designed exclusively for the lunar production of oxygen. In this concept, granulated raw material (soil) that consists almost entirely of metal oxides is vaporized and the vapor is raised to a temperature where it dissociates into suboxides and free oxygen. Rapid cooling of the dissociated vapor to a discrete temperature causes condensation of the suboxides, while the oxygen remains essentially intact and can be collected downstream. The gas flow path and flow rate are maintained at an optimum level by control of the pressure differential between the vaporization region and the oxygen collection system with the aid of the environmental vacuum.

Steurer, Wolfgang

1992-01-01

4

High Levels of Cancer-Linked Chemical in E-Cigarette Vapor  

MedlinePLUS

... please enable JavaScript. High Levels of Cancer-Linked Chemical in E-Cigarette Vapor, Study Finds When users ... produce vapor with large amounts of formaldehyde-containing chemical compounds. This could pose a risk to users ...

5

Chemical hazards present in liquids and vapors of electronic cigarettes.  

PubMed

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

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

2014-07-01

6

Policy #3220 Policy on the Use of Tobacco and Smoking-Related Products and Electronic Cigarettes and Vaporizers 1  

E-print Network

Policy #3220 ­ Policy on the Use of Tobacco and Smoking-Related Products and Electronic Cigarettes-RELATED PRODUCTS AND ELECTRONIC CIGARETTES AND VAPORIZERS Responsible Oversight Executive: Vice President's restrictions on the use of tobacco and smoking-related products and electronic cigarettes and vaporizers. B

7

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

PubMed

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

Popa, Cristina

2015-05-01

8

Vapor Phase Catalytic Ammonia Reduction  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

9

Vapor phase heat transport systems  

SciTech Connect

Vapor phase heat-transport systems are being tested in two of the passive test cells at Los Alamos. The systems consist of an active fin-and-tube solar collector and a condenser inside a water storage tank. The refrigerant, R-11, can be returned to the collector by a pump or by a self-pumping scheme. In one of the test cells the liquid was self-pumped to the roof-mounted collector 17 ft above the condenser. A mechanical valve was designed and tested that showed that the system could operate in a completely passive mode. Performance comparisons have been made with a passive water wall test cell.

Hedstrom, J.C.

1984-01-01

10

Ethanol vapor phase carburetion. [For irrigation  

Microsoft Academic Search

An experimental prototype device, called a ''vapor-phase carburetor'' (VPC) was designed, fabricated, and tested. The principle of operation was to vaporize the ethanol\\/water fuel blend utilizing residual heat from the coolant of the internal combustion engine in a slightly pressurized (10 to 15 psi) heat exchanger with vapor temperature about 232°F; mix the vaporous fuel with preheated air at about

J. R. Myron; B. F. Hanson

1983-01-01

11

Application of headspace solid phase microextraction to qualitative and quantitative analysis of tobacco additives in cigarettes  

Microsoft Academic Search

Cigarettes may contain up to 10% by weight additives which are intended to make them more attractive. A fast and rugged method for a cigarette-screening for additives with medium volatility was developed using automatic headspace solid phase microextraction (HS-SPME) with a 65?m carbowax-divinylbenzene fiber and gas chromatography–mass spectrometry (GC–MS) with standard electron impact ionisation. In three runs, each cigarette sample

Careen Merckel; Fritz Pragst; Astrid Ratzinger; Beat Aebi; Werner Bernhard; Frank Sporkert

2006-01-01

12

Vapor phase lubrication of high temperature alloys  

SciTech Connect

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.

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

1995-06-01

13

Water vapor radiometry research and development phase  

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

14

Application of Thioether for Vapor Phase Lubrication  

NASA Technical Reports Server (NTRS)

The objective of these studies was to identify the optimal conditions for vapor phase lubrication using Thioether for both sliding and rolling wear. The important variable include; (1) The component materials including M50 steel, monel and silicon nitride. (2) The vapor concentration and flow rate. (3) The temperature in the range of 600 F to 1500 F. (4) The loads and rolling and/or sliding speeds.

Graham, E. Earl

1997-01-01

15

A Protocol for Detecting and Scavenging Gas-phase Free Radicals in Mainstream Cigarette Smoke  

PubMed Central

Cigarette smoking is associated with human cancers. It has been reported that most of the lung cancer deaths are caused by cigarette smoking 5,6,7,12. Although tobacco tars and related products in the particle phase of cigarette smoke are major causes of carcinogenic and mutagenic related diseases, cigarette smoke contains significant amounts of free radicals that are also considered as an important group of carcinogens9,10. Free radicals attack cell constituents by damaging protein structure, lipids and DNA sequences and increase the risks of developing various types of cancers. Inhaled radicals produce adducts that contribute to many of the negative health effects of tobacco smoke in the lung3. Studies have been conducted to reduce free radicals in cigarette smoke to decrease risks of the smoking-induced damage. It has been reported that haemoglobin and heme-containing compounds could partially scavenge nitric oxide, reactive oxidants and carcinogenic volatile nitrosocompounds of cigarette smoke4. A 'bio-filter' consisted of haemoglobin and activated carbon was used to scavenge the free radicals and to remove up to 90% of the free radicals from cigarette smoke14. However, due to the cost-ineffectiveness, it has not been successfully commercialized. Another study showed good scavenging efficiency of shikonin, a component of Chinese herbal medicine8. In the present study, we report a protocol for introducing common natural antioxidant extracts into the cigarette filter for scavenging gas phase free radicals in cigarette smoke and measurement of the scavenge effect on gas phase free radicals in mainstream cigarette smoke (MCS) using spin-trapping Electron Spin Resonance (ESR) Spectroscopy1,2,14. We showed high scavenging capacity of lycopene and grape seed extract which could point to their future application in cigarette filters. An important advantage of these prospective scavengers is that they can be obtained in large quantities from byproducts of tomato or wine industry respectively11,13 PMID:22230844

Yu, Long-Xi; Dzikovski, Boris G.; Freed, Jack H.

2012-01-01

16

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...

17

Vapor-liquid phase separator studies  

NASA Technical Reports Server (NTRS)

Porous plugs serve as both entropy rejection devices and phase separation components separating the vapor phase on the downstream side from liquid Helium 2 upstream. The liquid upstream is the cryo-reservoir fluid needed for equipment cooling by means of Helium 2, i.e Helium-4 below its lambda temperature in near-saturated states. The topics outlined are characteristic lengths, transport equations and plug results.

Yuan, S. W. K.; Lee, J. M.; Kim, Y. I.; Hepler, W. A.; Frederking, T. H. K.

1983-01-01

18

Liquid-phase compositions from vapor-phase analyses  

SciTech Connect

Arsenic normally is not considered to be a contaminant. However, because arsenic was found in many cylinders of UF{sub 6}, including in corrosion products, a study was performed of the distribution of the two arsenic fluorides, AsF{sub 3} and AsF{sub 5}, between liquid and vapor phases. The results of the study pertain to condensation or vaporization of liquid UF{sub 6}. This study includes use of various experimental data plus many extrapolations necessitated by the meagerness of the experimental data. The results of this study provide additional support for the vapor-liquid equilibrium model of J.M. Prausnitz and his coworkers as a means of describing the distribution of various impurities between vapor and liquid phases of UF{sub 6}. Thus, it is concluded that AsF{sub 3} will tend to concentrate in the liquid phase but that the concentration of AsF{sub 5} in the vapor phase will exceed its liquid-phase concentration by a factor of about 7.5, which is in agreement with experimental data. Because the weight of the liquid phase in a condensation operation may be in the range of thousands of times that of the vapor phase, most of any AsF{sub 5} will be in the liquid phase in spite of this separation factor of 7.5. It may also be concluded that any arsenic fluorides fed into a uranium isotope separation plant will either travel with other low-molecular-weight gases or react with materials present in the plant. 25 refs., 3 figs., 6 tabs.

Davis, W. Jr. (Oak Ridge Gaseous Diffusion Plant, TN (USA)); Cochran, H.D. (Oak Ridge National Lab., TN (USA))

1990-02-01

19

Selective Detection of Vapor Phase Hydrogen Peroxide with Phthalocyanine Chemiresistors  

E-print Network

Selective Detection of Vapor Phase Hydrogen Peroxide with Phthalocyanine Chemiresistors Forest I and toxicity (OSHA PEL ) 1 ppm), vapor phase monitoring of hydrogen peroxide (H2O2) is also an important, California 92093 Received November 14, 2007; E-mail: wtrogler@ucsd.edu Vapor phase monitoring of peroxides

Kummel, Andrew C.

20

Vapor-phase heat-transport system  

SciTech Connect

A vapor-phase heat-transport system is being tested in one of the passive test cells at Los Alamos. The system consists of one selective-surface collector and a condenser inside a water storage tank. The refrigerant, R-11, can be returned to the collector by gravity or with a pump. Results from several operating configurations are presented, together with a comparison with other passive systems. A new self-pumping concept is presented.

Hedstrom, J.C.

1983-01-01

21

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...

22

Mixed metal vapor phase matching for third-harmonic generation  

NASA Technical Reports Server (NTRS)

Phase matching for frequency tripling of 1.06 microns is demonstrated in a homogeneous mixture of sodium and magnesium vapor. The ratio of Mg to Na vapor pressures required for phase matching is 2:1. This ratio is about 1/75 of that required to phase match Na with Xe.

Bloom, D. M.; Young, J. F.; Harris, S. E.

1975-01-01

23

Simultaneous analysis of 22 volatile organic compounds in cigarette smoke using gas sampling bags for high-throughput solid-phase microextraction.  

PubMed

Quantifying volatile organic compounds (VOCs) in cigarette smoke is necessary to establish smoke-related exposure estimates and evaluate emerging products and potential reduced-exposure products. In response to this need, we developed an automated, multi-VOC quantification method for machine-generated, mainstream cigarette smoke using solid-phase microextraction gas chromatography-mass spectrometry (SPME-GC-MS). This method was developed to simultaneously quantify a broad range of smoke VOCs (i.e., carbonyls and volatiles, which historically have been measured by separate assays) for large exposure assessment studies. Our approach collects and maintains vapor-phase smoke in a gas sampling bag, where it is homogenized with isotopically labeled analogue internal standards and sampled using gas-phase SPME. High throughput is achieved by SPME automation using a CTC Analytics platform and custom bag tray. This method has successfully quantified 22 structurally diverse VOCs (e.g., benzene and associated monoaromatics, aldehydes and ketones, furans, acrylonitrile, 1,3-butadiene, vinyl chloride, and nitromethane) in the microgram range in mainstream smoke from 1R5F and 3R4F research cigarettes smoked under ISO (Cambridge Filter or FTC) and Intense (Health Canada or Canadian Intense) conditions. Our results are comparable to previous studies with few exceptions. Method accuracy was evaluated with third-party reference samples (?15% error). Short-term diffusion losses from the gas sampling bag were minimal, with a 10% decrease in absolute response after 24 h. For most analytes, research cigarette inter- and intrarun precisions were ?20% relative standard deviation (RSD). This method provides an accurate and robust means to quantify VOCs in cigarette smoke spanning a range of yields that is sufficient to characterize smoke exposure estimates. PMID:24933649

Sampson, Maureen M; Chambers, David M; Pazo, Daniel Y; Moliere, Fallon; Blount, Benjamin C; Watson, Clifford H

2014-07-15

24

[Electronic cigarette].  

PubMed

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

Králíková, Eva; Jezek, Martin

2012-01-01

25

Mechanistic study of organometallic vapor phase epitaxy  

SciTech Connect

Only AsH{sub 3} and PH{sub 3} have been used as the group V source molecules for organometallic vapor phase epitaxy (OMVPE) of III/V semiconductors until recently, since they have been the only precursors yielding device quality materials. This paper reviews recent work on the pyrolysis of individual organometallic molecules, with emphasis on the group V sources, including: (1) the methylarsines, di- and tri-methylarsine, (2) the ethylarsines, mono-, di-, and tri-ethylarsine, and (3) the singly substituted tertiarybutyl arsine and phosphine molecules. The pyrolysis and growth reactions occurring when both group III and group V precursors are present simultaneously, i.e., the reactions occuring during OMVPE growth of several III/V semiconductors, are also briefly reviewed.

Stringfellow, G.B.

1990-12-31

26

Mechanistic study of organometallic vapor phase epitaxy  

SciTech Connect

Only AsH{sub 3} and PH{sub 3} have been used as the group V source molecules for organometallic vapor phase epitaxy (OMVPE) of III/V semiconductors until recently, since they have been the only precursors yielding device quality materials. This paper reviews recent work on the pyrolysis of individual organometallic molecules, with emphasis on the group V sources, including: (1) the methylarsines, di- and tri-methylarsine, (2) the ethylarsines, mono-, di-, and tri-ethylarsine, and (3) the singly substituted tertiarybutyl arsine and phosphine molecules. The pyrolysis and growth reactions occurring when both group III and group V precursors are present simultaneously, i.e., the reactions occuring during OMVPE growth of several III/V semiconductors, are also briefly reviewed.

Stringfellow, G.B.

1990-01-01

27

Monitoring of vapor phase polycyclic aromatic hydrocarbons  

DOEpatents

An apparatus for monitoring vapor phase polycyclic aromatic hydrocarbons in a high-temperature environment has an excitation source producing electromagnetic radiation, an optical path having an optical probe optically communicating the electromagnetic radiation received at a proximal end to a distal end, a spectrometer or polychromator, a detector, and a positioner coupled to the first optical path. The positioner can slidably move the distal end of the optical probe to maintain the distal end position with respect to an area of a material undergoing combustion. The emitted wavelength can be directed to a detector in a single optical probe 180.degree. backscattered configuration, in a dual optical probe 180.degree. backscattered configuration or in a dual optical probe 90.degree. side scattered configuration. The apparatus can be used to monitor an emitted wavelength of energy from a polycyclic aromatic hydrocarbon as it fluoresces in a high temperature environment.

Vo-Dinh, Tuan; Hajaligol, Mohammad R.

2004-06-01

28

Phase relationship, vaporization, and thermodynamic properties of neodymium hexaboride  

Microsoft Academic Search

The Nd-B system was studied between NdBâ â⁠and NdBâ ââ, and between 1700 and 2100 K by Langmuir and Knudsen techniques to determine the phase relationship, the chemical activity of the components, the vaporization rate, and the vapor composition. At 1900 K, the neodymium hexaboride phase exists bwtween NdBâ âââ and NdBâ â with a congruently vaporizing composition at

E. K. Storms

1981-01-01

29

Atmospheric Phase Correction using Water Vapor Radiometers Melvyn Wright  

E-print Network

Atmospheric Phase Correction using Water Vapor Radiometers Melvyn Wright Radio Astronomy Laboratory radiometers used for atmospheric phase correction on the BIMA array. Over intervals of a few minutes the WVR, leading to the use of water vapor radiometers to measure the path length through the atmosphere. In April

30

Toxicological assessment of kretek cigarettes: Part 1: background, assessment approach, and summary of findings.  

PubMed

This publication introduces a series of six other publications describing the toxicological assessment of kretek cigarettes, i.e., cigarettes characterized primarily by the use of a significant amount of cloves as an ingredient added to the tobacco. This paper presents background information on kretek cigarettes, describes the general approach of the in vitro and in vivo toxicological assessment of mainstream smoke from kretek cigarettes, presents the methodology used, and summarizes the results of the assessment program. In summary, the smoke from kretek cigarettes gives rise to the typical cigarette smoke-related effects known from American-blended cigarettes, does not reveal any novel toxicity, and exhibits an unexpected distinct attenuation of pulmonary inflammation. Based on equal amounts of smoke total particulate matter (TPM), kretek cigarettes deliver less toxicants when compared to American-blended cigarettes; when assessed in vitro, the smoke from kretek cigarettes is less cytotoxic (gas/vapor phase) and less mutagenic (TPM). When assessed in vivo, kretek cigarette smoke shows lower toxicity in the respiratory tract. When based on an equal nicotine basis, several of the toxicity endpoints in kretek cigarettes become equivalent to American-blended cigarettes. The data do not indicate an increased hazard potential of kreteks compared to American-blended cigarettes. PMID:25498000

Roemer, E; Dempsey, R; Schorp, M K

2014-12-01

31

Studies on toxicological mechanisms of gas-phase cigarette smoke and protection effects of GTP  

Microsoft Academic Search

Gas-phase cigarette smoke (GPCS) was able to induce lipid peroxidation in lecithin liposomes, rat liver microsomes, and rat\\u000a lung cells (RLC), and change the membrane fluidity of RLCs. Lipid free radicals were trapped in a GPCS-treated microsomal\\u000a suspension by using 4-POBN as the spin trap. In addition, it was found that GPCS-peroxidized liposomes in appropriate degree\\u000a of lipid peroxidation had

F.-J. Yang; B.-L. Zhao; W.-J. Xin

1992-01-01

32

Growth Rates of Zinc Crystals from the Vapor Phase  

Microsoft Academic Search

The rate of growth of zinc crystals from the vapor phase has been studied as a function of the vapor supersaturation ? at a temperature of 390°C. The ? values ranged between 0.009 and 0.09. The rate R was found to vary approximately linearly with ?, permitting estimates to be made of the two parameters ?1 and ?C0, appearing in

Robert L. Parker; Lawrence M. Kushner

1961-01-01

33

External fuel vaporization study, phase 1  

NASA Technical Reports Server (NTRS)

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.

Szetela, E. J.; Chiappetta, L.

1980-01-01

34

FIELD TRAPPING OF SUBSURFACE VAPOR PHASE PETROLEUM HYDROCARBONS  

EPA Science Inventory

Soil gas samples from intact soil cores were collected on adsorbents at a field site, then thermally desorbed and analyzed by laboratory gas chromatography (GC). ertical concentration profiles of predominant vapor phase petroleum hydrocarbons under ambient conditions were obtaine...

35

Gas phase reaction of sulfur trioxide with water vapor  

Microsoft Academic Search

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

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

1994-01-01

36

Early specific free radical-related cytotoxicity of gas phase cigarette smoke and its paradoxical temporary inhibition by tar  

Microsoft Academic Search

Electron paramagnetic resonance (EPR) spin trapping studies demonstrated aqueous tar particulate matter (TPM) and gas phase cigarette smoke (GPCS) to behave as different sources of free radicals in cigarette smoke (CS) but their cytotoxic implications have been only assessed in CS due to its relevance to the natural smoking process. Using a sensitive spin trapping detection with 5-(diethoxyphosphoryl)-5-methyl-1-pyrroline-N-oxide (DEPMPO), this

Marcel Culcasi; Agnès Muller; Anne Mercier; Jean-Louis Clément; Olivier Payet; Antal Rockenbauer; Véronique Marchand; Sylvia Pietri

2006-01-01

37

Vapor Phase Deposition Using Plasma Spray-PVD™  

NASA Astrophysics Data System (ADS)

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.

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

2010-01-01

38

Identification and Characterization of Chemistry of Different Radicals in Mainstream Gas- phase Cigarette Smoke by ESI-MS method  

E-print Network

We have investigated some of the free radicals in cigarette smoke. Free radicals in the gas phase, mainstream cigarette smoke have been trapped directly by using a nitroxide probe, 3- amino- 2, 2, 5, 5- tetramethyl-1- pyrrolidinyloxy (3AP) which is supported on a solid phase, derivatized by fluorescamine, and analyzed by electrospray ionization mass spectrometry (EI- MS). We have identified some specific radicals in cigarette smoke mainstream gas phase derived from nicotine, isoprene, and glucose radicals which may be produced by reactions of OH radical through H-abstraction or addition reactions. Nicotine may undergo both OH radical addition and abstraction. However nicotine shows more tendencies to react with hydrogen abstraction from methyl group on nicotine. The addition reaction of OH radical with nicotine may happen on double bond of 6 member ring of nicotine. Isoprene and glucose react with OH radical by addition and abstraction reaction, respectively. In order to confirm the results obtained for the i...

Nejad, Maryam Abili

2010-01-01

39

Calibration of an explosives vapor generator based on vapor diffusion from a condensed phase  

SciTech Connect

In the field of explosives detection there is currently a need for a calibrated source of explosives vapor. Such a source could be used to test and calibrate explosives detection systems which identify explosives via the collection of vapor or air borne particulate matter. This paper describes the principles of operation and evaluation of one such explosives vapor generator. This generator is based on the diffusion of vapor from a condensed phase (i.e., solid or liquid) in a source reservoir, and the output has been tied to a National Institute of Standards and Technology (NIST) mass standard. We discuss results of the calibration of this generator using the explosives 2,4,6-trinitrotoluene (TNT) and cyclonite (RDX). The mass output of this generator is stable over hundreds of hours of continuous operation, and is adjustable from the low picograms(pg)/sec range to at least 10 nanograms(ng)/sec. In the case of TNT, the mass output correlates well with predictions based on gas phase diffusion theory. In the case of RDX, the agreement with theory is less good. This may be attributable to a variety of factors, possibly including inaccuracies in the published data on RDX vapor pressure as a function of temperature.

Parmeter, J.E. [Sandia National Labs., Albuquerque, NM (United States); Eiceman, G.A.; Preston, D.A.; Tiano, G.S. [New Mexico State Univ., Las Cruces, NM (United States)

1996-08-01

40

Effect of vapor-phase oxygen on chemical vapor deposition growth of graphene  

NASA Astrophysics Data System (ADS)

To obtain a large-area single-crystal graphene, chemical vapor deposition (CVD) growth on Cu is considered the most promising. Recently, the surface oxygen on Cu has been found to suppress the nucleation of graphene. However, the effect of oxygen in the vapor phase was not elucidated sufficiently. Here, we investigate the effect of O2 partial pressure (PO2) on the CVD growth of graphene using radiation-mode optical microscopy. The nucleation density of graphene decreases monotonically with PO2, while its growth rate reaches a maximum at a certain pressure. Our results indicate that PO2 is an important parameter to optimize in the CVD growth of graphene.

Terasawa, Tomo-o.; Saiki, Koichiro

2015-03-01

41

Quantitative Infrared Spectra of Vapor Phase Chemical Agents  

SciTech Connect

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).

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

2003-04-21

42

Vapor-phase mechanism of the laser oxidation of metals  

Microsoft Academic Search

Based on an analysis of experimental results obtained for D16 Duralumin specimens, a model is proposed for the oxidation of metals irradiated by short laser pulses. The oxidation process involves metal evaporation, its oxidation in the vapor phase, onset of a backflow of oxide molecules, and their condensation and additional oxidation on the specimen surface. This oxidation mechanism, which has

A. G. Akimov; A. M. Bonch-Bruevich; A. P. Gagarin; I. A. Dorofeev; V. G. Dorofeev

1987-01-01

43

Fog Machines, Vapors, and Phase Diagrams  

ERIC Educational Resources Information Center

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…

Vitz, Ed

2008-01-01

44

Phase effects for electrons in liquid water and water vapor  

SciTech Connect

The objective of these studies is to compare transport, energy loss, and other phenomena for electrons in water in the liquid and vapor phases. Understanding the differences and similarities is an interesting physics problem in its own right. It is also important for applying the relatively large body of experimental data available for the vapor to the liquid, which is of greater relevance in radiobiology. This paper presents a summary of results from a series of collaborative studies carried out by the authors at Oak Ridge National Laboratory (ORNL) and the Gesellschaft fuer Strahlen- und Umweltforschung (GSF). 14 figs.

Turner, J.E.; Paretzke, H.G.; Wright, H.A.; Hamm, R.N.; Ritchie, R.H.

1988-01-01

45

Vapor-phase exchange of perchloroethene between soil and plants  

USGS Publications Warehouse

Tree core concentrations of tetrachloroethylene (perchloroethene, PCE) at the Riverfront Superfund Site in New Haven, MO, were found to mimic the profile of soil phase concentrations. The observed soil-tree core relationship was stronger than that of groundwater PCE to tree core concentrations at the same site. Earlier research has shown a direct, linear relationship between tree core and groundwater concentrations of chlorinated solvents and other organics. Laboratory-scale experiments were performed to elucidate this phenomenon, including determining partitioning coefficients of PCE between plant tissues and air and between plant tissues and water, measured to be 8.1 and 49 L/kg, respectively. The direct relationship of soil to tree core PCE concentrations was hypothesized to be caused by diffusion between tree roots and the soil vapor phase in the subsurface. The central findings of this research are discovering the importance of subsurface vapor-phase transfer for VOCs and uncovering a direct relationship between soil vapor-phase chlorinated solvents and uptake rates that impact contaminant translocation from the subsurface and transfer into the atmosphere. ?? 2005 American Chemical Society.

Struckhoff, G.C.; Burken, J.G.; Schumacher, J.G.

2005-01-01

46

Supported complex catalysts for vapor-phase carbonylations  

SciTech Connect

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.

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

1996-10-01

47

nanocrystallites condensed in vapor-phase for photocatalyst applications  

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

48

Sex Differences and Menstrual Cycle Phase-Dependent Modulation of Craving for Cigarette: An fMRI Pilot Study  

PubMed Central

While overall more men than women smoke cigarettes, women and girls take less time to become dependent after initial use and have more difficulties quitting the habit. One of the factors contributing to these differences may be that women crave cigarettes more than men and that their desire to smoke is influenced by hormonal fluctuations across the menstrual cycle. Therefore, the purpose of the present study was twofold: (a) to examine potential sex/gender differences in functional neuroanatomy of craving and to (b) delineate neural correlates of cigarette cravings in women across their menstrual cycle. Fifteen tobacco-smoking men and 19 women underwent a functional MRI during presentation of neutral and smoking-related images, known to elicit craving. Women were tested twice: once during early follicular phase and once during midluteal phase of their menstrual cycle. The analysis did not reveal any significant sex differences in the cerebral activations associated with craving. Nevertheless, the pattern of activations in women varied across their menstrual cycle with significant activations in parts of the frontal, temporal, and parietal lobe, during follicular phase, and only limited activations in the right hippocampus during the luteal phase. PMID:25478563

Dinh-Williams, Laurence; Bourque, Josiane; Potvin, Stéphane

2014-01-01

49

Crystal growth from the vapor phase experiment MA-085  

NASA Technical Reports Server (NTRS)

Three vapor transport experiments on multicomponent systems were performed during the Apollo Soyuz mission to determine the effects of microgravity forces on crystal morphology and mass transport rates. The mixed systems used germanium selenide, tellurium, germanium tetraiodide (transport agent), germanium monosulfide, germanium tetrachloride (transport agent), and argon (inert atmosphere). The materials were enclosed in evacuated sealed ampoules of fused silica and were transported in a temperature gradient of the multipurpose electric furnace onboard the Apollo Soyuz spacecraft. Preliminary evaluation of 2 systems shows improved quality of space grown crystals in terms of growth morphology and bulk perfection. This conclusion is based on a direct comparison of space grown and ground based crystals by means of X-ray diffraction, microscopic, and chemical etching techniques. The observation of greater mass transport rates than predicted for a microgravity environment by existing vapor transport models indicates the existence of nongravity caused transport effects in a reactive solid/gas phase system.

Wiedemeir, H.; Sadeek, H.; Klaessig, F. C.; Norek, M.

1976-01-01

50

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

PubMed

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

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

1986-01-01

51

E-cigarettes: promise or peril?  

PubMed

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

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

2012-03-01

52

Processes affecting free-phase hydrocarbon removal by vapor extraction  

SciTech Connect

A laboratory-scale soil vapor extraction test was conducted to evaluate the mechanisms that affect removal of mobile free-phase hydrocarbon from the subsurface. The test was performed inside a steel-reinforced acrylic tank, 183 cm long by 183 cm high by 25 cm wide, which was filled with No. 60 industrial grade silica sand. A water table was initially established with a piezometric head of 54 cm above the base of the tank and a gradient of 0.01 to simulate a field groundwater system. Twenty liters (5.3 gallons) of gasoline (free-phase hydrocarbon) was added through the side of the tank to avoid residual phase hydrocarbon in the vadose zone. Upon equilibration, the oil/air interface at the inlet side was 68.5 cm and the piezometric surface was 54.1 cm above the base of the tank, respectively. Vapor extraction began at a rate of approximately 25.5 liters/min. (0.9 scfm), which resulted in an initially high mass removal rate of 3600 g/day (25 %/day) of gasoline range organics. This mass recovery rate decreased within the first 1.5 hours of extraction. During the course of five weeks of vapor extraction, cumulative mass recovery rates of total GRO (gasoline range organics) and eleven individual gasoline components, including BTEX and MTBE (methyl-tert-butyl-ether), continued to increase in a generally linear trend. Recovery rates at the end of five weeks were 50 g/day (0.35 %/day) for total GRO and 2 g/day (0.4 %/day) for benzene. MTBE showed an affinity to volatilize and be remediated through vapor extraction. MTBE comprised approximately 10.5 percent of the gasoline used for this experiment. Since vapor extraction began, approximately 40 percent of that initial mass had been removed and its mass removal rate continued to be approximately 13.5 g/day (0.88 %/day) at the end of the experiment.

Frank, R.J. [CH2M Hill, Tempe, AZ (United States); Huntley, D. [San Diego State Univ., CA (United States)

1997-12-31

53

Vapors-liquid phase separator. [infrared telescope heat sink  

NASA Technical Reports Server (NTRS)

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.

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

1980-01-01

54

Detection and separation of gas-phase carbon-centered radicals from cigarette smoke and diesel exhaust.  

PubMed

Carbon-centered radicals were trapped from gas-phase cigarette smoke and diesel engine exhaust by reaction with a nitroxide, 3-amino-2,2,5,5-tetramethyl-1-pyrrolidinyloxy (3AP). The resulting mixture of stable, diamagnetic adducts was derivatized with naphthalenedicarboxaldehyde (NDA) to produce highly fluorescent products. Derivatives were separated by high-performance liquid chromatography (HPLC), which revealed distinctly different suites of radicals present in the two systems. Integration of HPLC peaks gave approximately 22 ± 7 nmol of radicals per cigarette and 3 ± 1 nmol of radicals per liter of diesel engine exhaust. An estimated 8-10 different carbon-centered radical species are present in each system. PMID:21651292

Flicker, T M; Green, S A

1998-05-01

55

Effect of dimensionality on vapor-liquid phase transition  

SciTech Connect

Dimensionality play significant role on ‘phase transitions’. Fluids in macroscopic confinement (bulk or 3-Dimensional, 3D) do not show significant changes in their phase transition properties with extent of confinement, since the number of molecules away from the surrounding surfaces is astronomically higher than the number of molecules in close proximity of the confining surfaces. In microscopic confinement (quasi 3D to quasi-2D), however, the number of molecules away from the close proximity of the surface is not as high as is the case with macroscopic (3D) confinement. Hence, under the same thermodynamic conditions ‘phase transition’ properties at microscopic confinement may not remain the same as the macroscopic or 3D values. Phase transitions at extremely small scale become very sensitive to the dimensions as well as the surface characteristics of the system. In this work our investigations reveal the effect of dimensionality on the phase transition from 3D to quasi-2D to 2D behavior. We have used grand canonical transition matrix Monte Carlo simulation to understand the vapor–liquid phase transitions from 3D to quasi-2D behavior. Such studies can be helpful in understanding and controlling the fluid film behaviour confined between solid surfaces of few molecular diameters, for example, in lubrication applications.

Singh, Sudhir Kumar, E-mail: sksingh@thapar.edu [Department Chemical Engineering, Thapar University, Patiala-147004 Punjab (India)

2014-04-24

56

Cigarette smoke extract increases albumin flux across pulmonary endothelium in vitro  

SciTech Connect

Cigarette smoking causes lung inflammation, and a characteristic of inflammation is an increase in vascular permeability. To determine if cigarette smoke could alter endothelial permeability, we studied flux of radiolabeled albumin across monolayers of porcine pulmonary artery endothelium grown in culture on microporous membranes. Extracts (in either dimethylsulfoxide or phosphate-buffered saline) of cigarette smoke in a range estimate of concentrations simulating cigarette smoke exposure to the lungs in vivo caused a dose-dependent increase in albumin flux that was dependent on extracellular divalent cations and associated with polymerization of cellular actin. The effect was reversible, independent of the surface of endothelial cells exposed (either luminal or abluminal), and due primarily to components of the vapor phase of smoke. The effects occurred without evidence of cell damage, but subtle morphological changes were produced by exposure to the smoke extracts. These findings suggest that cigarette smoke can alter permeability of the lung endothelium through effects on cytoskeletal elements.

Holden, W.E.; Maier, J.M.; Malinow, M.R.

1989-01-01

57

Debris cloud characterization in the liquid-vapor phase  

SciTech Connect

A series of experiments has been performed on the Sandia Hypervelocity Launcher to impact a 1.25-mm thick aluminum bumper by an aluminum flier plate 17-mm diameter by 0.92-mm thick over the velocity range of 5 km/s to 11 km/s. Radiographic techniques were employed to record the debris cloud generated upon impact. The shape of the debris cloud is found to depend on the flier plate tilt. Generally the data indicate a central core of higher density surrounded by a diffused layer. These experiments allow measurements of debris cloud expansion velocities as the material undergoes a phase change from solid fragments at impact velocities of 5 km/s to a mixture of liquid and vapor phase at higher impact velocities. The expansion velocity of the debris cloud increases with increasing impact velocity, with the high-density leading edge traveling faster than the impact velocity. There is a difference between the X-ray and photographic measurements of expansion velocities at higher impact velocities. This is believed to be due to the presence of very low- density vapor in the photographic records that are not detected using X-ray techniques.

Chhabildas, L.C.; Boslough, M.B.; Reinhart, W.D.; Hall, C.A.

1993-10-01

58

A load dampening system for vapor phase bioreactors  

SciTech Connect

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.

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

1999-07-01

59

Healing defective CVD-graphene through vapor phase treatment  

NASA Astrophysics Data System (ADS)

Structural defects present on chemical vapor deposition (CVD)-graphene have usually originated from the growth stage and transfer process. They limit the electronic transport properties of graphene and degrade performance of related devices. Here we report that these inherent atomic defects could be selectively healed by a simple vapor phase treatment performed in equipment conventionally used for atomic layer deposition (ALD). The unique chemistry of Al2O3 ALD facilitated selective depositions of AlxOy compounds on the defects, which could be readily probed and visualized using AFM imaging. The healing agent, AlxOy, was observed to bind tightly to the defects and lead to doping of the CVD-graphene, which was reflected in the noticeable improvement in electrical sheet resistance. In contrast with the chemically doped graphene, the ALD-treated graphenes revealed notable long-term stability under environmental conditions. Our approach promises selective healing of defects present in most materials and possibly ensures considerable improvement in electrical and mechanical properties. ALD with a broad spectrum of material selection could be a versatile tool for upgrading properties of materials.Structural defects present on chemical vapor deposition (CVD)-graphene have usually originated from the growth stage and transfer process. They limit the electronic transport properties of graphene and degrade performance of related devices. Here we report that these inherent atomic defects could be selectively healed by a simple vapor phase treatment performed in equipment conventionally used for atomic layer deposition (ALD). The unique chemistry of Al2O3 ALD facilitated selective depositions of AlxOy compounds on the defects, which could be readily probed and visualized using AFM imaging. The healing agent, AlxOy, was observed to bind tightly to the defects and lead to doping of the CVD-graphene, which was reflected in the noticeable improvement in electrical sheet resistance. In contrast with the chemically doped graphene, the ALD-treated graphenes revealed notable long-term stability under environmental conditions. Our approach promises selective healing of defects present in most materials and possibly ensures considerable improvement in electrical and mechanical properties. ALD with a broad spectrum of material selection could be a versatile tool for upgrading properties of materials. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr00775a

van Lam, Do; Kim, Sang-Min; Cho, Youngji; Kim, Jae-Hyun; Lee, Hak-Joo; Yang, Jun-Mo; Lee, Seung-Mo

2014-05-01

60

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...

61

EPR study of the toxicological effects of gas-phase cigarette smoke and the protective effects of grape seed extract on the mitochondrial membrane  

Microsoft Academic Search

Electron paramagnetic resonance spin trapping and spin labeling techniques were used to study the effects of grape seed extract\\u000a on the biophysical propertiers of the mitochondrial membrane exposed to gas-phase cigarette smoke. The spin trapping results\\u000a indicated that grape seed extract can effectively scavenge free radicals in cigarette smoke and the lipid free radicals generated\\u000a from the lipid peroxidation of

J. Gao; H. Tang; Y. Li; H. Liu; B. Zhao I

2002-01-01

62

Vaporization behavior of non-stoichiometric refractory carbide materials and direct observations of the vapor phase using laser diagnostics  

NASA Astrophysics Data System (ADS)

Transition metal and actinide carbides, such as ZrC or NbC and UC or ThC, exhibit a wide range of stoichiometry, and therefore vaporize incongruently. At long times, steady state vaporization can be achieved where relative concentrations of atomic species on solid surface equals that in the gas phase. The surface composition under these steady state conditions is termed the congruently vaporizing composition, (CVC). Modeling the vaporization or corrosion behavior of this dynamic process is complex and requires an understanding of how the surface composition changes with time and a knowledge of CVC, which is both temperature and atmosphere dependent. This paper describes vaporization and corrosion behavior of non-stoichiometric refractory carbide materials and, as an example, describes a thermokinetic model that characterizes the vaporization behavior of the complex carbide U(x)Zr(1-x)C(y) in hydrogen at 2500 to 3200 K. This model demonstrates that steady state corrosion of U(x)Zr(1-x)C(y) is rate limited by gaseous transport of Zr where partial pressure of Zr is determined by CVC. This paper also briefly describes efforts to image and characterize the vapor phase above the surface of ZrC in static and flowing gas environments using planar laser induced fluorescence. We have developed the method for monitoring and controlling the corrosion behavior of nuclear fuels in nuclear thermal rockets. However, the techniques described can be used, to image boundary layers, and could be used verifying corrosion models.

Butt, D. P.; Wantuck, P. J.; Rehse, S. J.; Wallace, T. C., Sr.

63

Evidence of Phase Separation during Vapor Deposition Polymerization  

NASA Astrophysics Data System (ADS)

Initiated chemical vapor deposition (iCVD) is a solventless, free radical technique predominately used to deposit homogeneous films of linear and crosslinked polymers directly from gas phase feeds. We are developing multicomponent iCVD techniques to induce phase separation during film growth. Small molecule porogens and crosslinkers are introduced into the iCVD process during film growth of poly(glycidyl methacrylate). Analogous to well established polymerization induced phase separation (PIPS) processes, porogens, such as dimethyl phthalate, are well mixed at the growing gas-film interface but are immiscible with high molecular weight polymer. Polymerization, crosslinking and PIPS are intended to occur simultaneously on the substrate, resulting in a vitrified microstructure. A series of films were grown by varying deposition rate, porogen type, and reagent flowrates. Deposited films were studied by electron microscopy and spectroscopic techniques. Experiments are compared to Cahn-Hilliard theory predictions that relate the length and time scale of the phase separation to the polymer-porogen interaction energy, the rate of polymerization and the species mobility.

Tao, Ran; Anthamatten, Mitchell

2013-03-01

64

A High Temperature Vapor Phase Lubrication Study Utilizing a Thioether Liquid Lubricant  

NASA Technical Reports Server (NTRS)

Much of the experimental work on vapor phase lubrication has employed certain organo phosphorous compounds as the vapor phase lubricant. Graham and Klaus, for instance, used tricresyl phosphate (TCP) and tributyl phosphate to vapor phase lubricate a four-ball wear tester using M50 steel balls at 370 C. Makki and Graham were able to vapor phase lubricate a reciprocating pin on plate tribometer using 1018 steel at 280 C with TCP vapor. Although a few organo phosphorous compounds, such as TCP, have been successfully used as vapor phase lubricants in many laboratory experiments, many problems remain unsolved. Two areas of concern relate to the 'durability' of phosphate deposited films and to the ability of the lubricating system to "self-recover" when vapor phase lubricated with an organo phosphorous compound. Durability refers to the ability of the deposited film to provide effective lubrication, for a period of time, after the vapor flow to the lubricating surfaces has been interrupted. Vapor phase lubrication tests, conducted at Cleveland State University with their high temperature tribometer, revealed that when TCP vapor flow to the lubricating surfaces was interrupted the frictional coefficient of the system rapidly increased from a value less than 0.1 to a value of 0.3 which was selected as our failure point. Self-recovery means the ability of the vapor phase lubricant to reduce the frictional coefficient of the lubricating system back down to value less than 0.1 after startup of the interrupted vapor flow. Lubrication tests conducted at Cleveland State University revealed that the high temperature tribometer could not self-recover after startup of the interrupted TCP vapor flow.

Morales, Wilfredo; Graham, E. Earl; Galvin, Thomas

1997-01-01

65

Quantitative infrared spectra of vapor phase chemical agents  

NASA Astrophysics Data System (ADS)

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 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 the Dugway Proving Ground (DPG).

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

2003-08-01

66

Quantitative Infrared Spectra of Vapor Phase Chemical Agents  

SciTech Connect

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).

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

2003-08-01

67

Condensed-phase transitions in binary systems during dynamic vaporization experiments. Effusion and transpiration  

SciTech Connect

During a condensed-phase transition at equilibrium in a vaporization experiment, three phases are present. In this paper, equations relating vapor pressure, temperature, and compositions of the vapor and condensed phases are derived for systems undergoing such transitions. Previously observed unusual phenomena, such as vapor pressures that increase at constant temperature and vapor pressures that increase with decreasing temperature, are explained. It is shown that equilibrium condensed-phase transitions in the presence of the vapor are always hysteretic in the temperature; the transition occurs at a higher temperature in the increasing-temperature direction than in the decreasing-temperature direction. The particular cases of effusion and transpiration experiments are treated in detail. 31 refs., 5 figs.

Edwards, J.G. [Univ. of Toledo, OH (United States); Franzen, H.F. [Ames Lab., IA (United States)

1995-03-30

68

Airborne and vapor phase hydrocarbons over the Mediterranean Sea  

SciTech Connect

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.

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

1990-11-01

69

Liquid-vapor phase equilibrium in a tin-selenium system  

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

70

Cigarettes Commencemet  

E-print Network

'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

Pilyugin, Sergei S.

71

Phase relationship, vaporization, and thermodynamic properties of the lanthanum--boron system  

Microsoft Academic Search

The La-B system was studied between LaB\\/sub 4.24\\/ and LaB\\/sub 29.2\\/, and between 1400 and 2100 K to determine the phase relationship, the chemical activity of the components, the vaporization rate, and the vapor composition. A blue colored phase near LaBâ was found to exist between purple colored LaBâ and elemental boron. Diffusion is so much slower than vaporization that

Edmund Storms; Barbara Mueller

1978-01-01

72

Vapor phase elemental sulfur amendment for sequestering mercury in contaminated soil  

DOEpatents

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.

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

2014-07-08

73

Metalorganic vapor phase growth of quantum well structures on thick metamorphic buffer layers grown by hydride vapor phase epitaxy  

NASA Astrophysics Data System (ADS)

The hydride vapor phase epitaxy technique (HVPE) can deposit uniform materials at high growth rates, making it suitable for the formation of metamorphic buffer layers (MBLs). HVPE was used to form InxGa1-x As-based MBLs as substrates in the metalorganic vapor phase epitaxy (MOVPE) of superlattice (SL) structures. Samples were grown over a range of deposition temperatures and reactant flows and their effect on the ternary alloy composition and growth rate was determined. Over the compositional range of xInAs<0.4, the alloy composition varied almost linearly with indium chloride pressure (PInCl). A compositionally step-graded MBL consisting of nine intermediate steps followed by a thick, constant composition layer of xInAs˜0.23 was grown. The MBL was characterized by high-resolution x-ray diffraction (HRXRD) and reciprocal space mapping. The topmost layer was highly relaxed, exhibiting a residual strain of -0.0011±0.0002. Chemical-mechanical polishing (CMP) was used to reduce the surface cross hatching, affecting a decrease in rms roughness from 2.10 to 1.39 nm. A 20 period, In0.33Ga0.67As (3.1 nm)/Al0.90In0.10As (7.2 nm) strain-balanced superlattice (SL) structure was grown by MOVPE on the as-grown and CMP-prepared MBL and characterized by HRXRD. The diffraction pattern of the SL grown on the CMP-prepared MBL was significantly more intense with narrower x-ray diffraction peaks when compared with the SL on as-grown MBL.

Schulte, Kevin L.; Garrod, Toby J.; Wan Kim, Tae; Kirch, Jeremy; Ruder, Steven; Mawst, Luke J.; Kuech, T. F.

2013-05-01

74

Quantitative Fourier transform infrared analysis of gas phase cigarette smoke and other gas mixtures  

SciTech Connect

A new method for the analysis of selected components in complex gas mixtures has been developed utilizing a relatively inexpensive Fourier transform infrared spectrometer and a continuous flow gas cell. The method was used to monitor nitric oxide and nitrogen dioxide concentrations in cigarette smoke with time. Using multivariate least-square regression analysis, it is possible to simultaneously quantitate both NO and NO{sub 2}, even in the presence of overlapping peaks. Using this method, the oxidation of nitric oxide in the presence of isoprene in cigarette smoke and in a model system was followed with time. The method also can be applied to other compounds in smoke or to any other gaseous mixture.

Cueto, R.; Church, D.F.; Pryor, W.A. (Louisiana State Univ., Baton Rouge (USA))

1989-03-01

75

Crystallization from a vapor phase in igneous rocks -- A conceptual model  

SciTech Connect

Euhedral, late-stage crystals in pocket pegmatite and in vesicles of volcanic rocks are commonly cited as examples of crystallization from a vapor phase. If, however, crystallization takes place only from the cavity forming vapor, that vapor cannot contain sufficient material for the formation of the observed crystals. The approximate amount of H[sub 2]O vapor and percentage of dissolved silicate matter (1) for shallow pocket pegmatite is 0.5 g/cm[sup 3] and 0.3 percent; (2) for vesicles is 0.002 g/cm[sup 3] and [much lt]1 percent. These values show that the silicate matter dissolved in the vapor is insufficient for the formation of the observed crystals. No (or little) recharge of the vapor is an unstated assumption in most discussions of enclosed cavities. This, however, is not quite correct. For a simplified system, four phases will exist in equilibrium: (1) mineral grains growing from liquid, (2) late-stage, H[sub 2]O-enriched, silicate liquid, (3) vapor, (4) crystals growing from vapor. The total system (for transferal of silicate matter) is given. Little silicate matter is dissolved in the vapor at any one time, but it is replenished as the crystals grow. The vapor becomes a continuously resupplied reservoir of dissolved silicate matter; crystallization from the vapor continues until the silicate liquid is depleted.

Kleck, W.D. (Orange Coast Coll., Costa Mesa, CA (United States))

1993-04-01

76

The nuclear liquid-vapor phase transition: Equilibrium between phases or free decay in vacuum?  

SciTech Connect

Recent analyses of multifragmentation in terms of Fisher's model and the related construction of a phase diagram brings forth the problem of the true existence of the vapor phase and the meaning of its associated pressure. Our analysis shows that a thermal emission picture is equivalent to a Fisher-like equilibrium description which avoids the problem of the vapor and explains the recently observed Boltzmann-like distribution of the emission times. In this picture a simple Fermi gas thermometric relation is naturally justified. Low energy compound nucleus emission of intermediate mass fragments is shown to scale according to Fisher's formula and can be simultaneously fit with the much higher energy ISiS multifragmentation data.

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

2002-11-14

77

Determination of oxides of nitrogen (NO/sub x/) in cigarette smoke by chemiluminescent analysis  

SciTech Connect

The successful application of a commercial chemiluminescent No/sub x/ analyzer to the determination of oxides of nitrogen in cigarette smoke is reported. Individual puffs of the smoke vapor phase are rapidly diluted in an air stream before introduction into the analyzer. This acts to both reduce quenching of the chemiluminescent response by CO/sub 2/ and to prevent side reactions of the NO/sub x/ with vapor phase organic constituents. Sweeping the dilute smoke through a reduced silver-ion exchange resin bed removed a substantial positive interference from hydrogen cyanide. A range of deliveries of 3 to 47 ..mu..mol of NO/sub x/ per cigarette was observed for nine types of experimental cigarettes. Statistically significant differences between NO/sub x/ and NO levels (NO/sub x/ - NO = NO/sub 2/) in smoke were observed in only one type of cigarette, presumably due to large cigarette-to-cigarette variability in constituent deliveries. 2 figures, 3 tables.

Jenkins, R.A.; Gill, B.E.

1980-05-01

78

Nanostructure-based optoelectronic sensing of vapor phase explosives - a promising but challenging method  

NASA Astrophysics Data System (ADS)

Optoelectronic sensing of gas phase hazardous chemicals is a newly explored field, which shows great advantages towards low concentration sensing when compared to normal gas sensing in the dark. Here, based on the recent progress on nanostructured vapor phase explosive gas sensors operated in dark conditions, the attractiveness of developing optoelectronic sensors for vapor phase explosive detection was highlighted. Furthermore, we try to propose some new insights to enhance optoelectronic sensing of vapor phase explosives. We suggest employing photocatalysis principles to enhance the sensitivity and employing a molecular imprinting technique (MIT) to enhance the selectivity.

Zu, Baiyi; Guo, Yanan; Dou, Xincun

2013-10-01

79

Vaporization behavior of non-stoichiometric refractory carbide materials and direct observations of the vapor phase using laser diagnostics  

SciTech Connect

Transition metal and actinide carbides, such as ZrC or NbC and UC or ThC, exhibit a wide range of stoichiometry, and therefore vaporize incongruently. At long times, steady state vaporization can be achieved where relative concentrations of atomic species on solid surface equals that in the gas phase. The surface composition under these steady state conditions is termed the congruently vaporizing composition, (CVC). Modeling the vaporization or corrosion behavior of this dynamic process is complex and requires an understanding of how the surface composition changes with time and a knowledge of CVC, which is both temperature and atmosphere dependent. This paper describes vaporization and corrosion behavior of non-stoichiometric refractory carbide materials and, as an example, describes a thermokinetic model that characterizes the vaporization behavior of the complex carbide U{sub x}Zr{sub 1-x}C{sub y} in hydrogen at 2500 to 3200 K. This model demonstrates that steady state corrosion of U{sub x}Zr{sub l-x}C{sub y} is rate limited by gaseous transport of Zr where partial pressure of Zr is determined by CVC. This paper also briefly describes efforts to image and characterize the vapor phase above the surface of ZrC in static and flowing gas environments using planar laser induced fluorescence. We have developed the method for monitoring and controlling the corrosion behavior of nuclear fuels in nuclear thermal rockets. However, the techniques described can be used, to image boundary layers, and could be used verifying corrosion models.

Butt, D.P.; Wantuck, P.J.; Rehse, S.J.; Wallace, T.C. Sr.

1993-09-01

80

VALIDATION OF CHEMICAL AND BIOLOGICAL TECHNIQUES FOR EVALUATION OF VAPORS IN AMBIENT AIR/MUTAGENICITY TESTING OF TWELVE (12) VAPOR-PHASE COMPOUNDS  

EPA Science Inventory

The overall objective of this research was to further validate Ames mutagenicity preincubation system for detection of vapors in ambient air. Parametes for detection of vapors in the Ames/Salmonella mutagenicity assay were investigated and 12 vapor-phase compounds were tested for...

81

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

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

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

2015-01-01

82

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

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

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

2015-01-01

83

Laboratory retention of vapor-phase PAHs using XAD adsorbents  

NASA Astrophysics Data System (ADS)

This investigation focuses on the retention of polycyclic aromatic hydrocarbons (PAHs) on XAD (-2, -4, and -16) resins, which is crucial for estimating PAH gas/particle partition coefficients. The XAD resins were found to exhibit higher specific retention volumes ( Vg, net gas-phase retention volume per unit weight (gram) of sorbent) than PUF for some 3-ring PAHs at 20 oC. The 3-ring compounds broke through the XAD adsorbents more easily than the 4-ring compounds at constant temperature. For the equation, Log Vg= m log PL+ b ( PL: subcooled liquid vapor pressure) the average m values were approximately -0.2 and -0.3 at 20 and 40 oC, respectively. Moreover, the Vg values were lower at 40 oC than at 20 oC for each PAH compound. The XAD-4 appeared to have a greater Vg value (adsorbent weight based) for each compound among the adsorbents at 40 oC. It was possible that PAH micropore adsorption dominated on XAD-4, different from the predominance of the PAH surface adsorption on the other two adsorbents.

Lee, James J.; Huang, Kuo-Lin; Yu, Yaochien Y.; Chen, Minsung S.

84

Numerical Modeling of Liquid-Vapor Phase Change  

NASA Technical Reports Server (NTRS)

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.

Esmaeeli, Asghar; Arpaci, Vedat S.

2001-01-01

85

Irritants in cigarette smoke plumes.  

PubMed Central

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. PMID:7125032

Ayer, H E; Yeager, D W

1982-01-01

86

Calibration of an explosives vapor generator based on vapor diffusion from a condensed phase  

SciTech Connect

Development of a vapor generator for consistently producing accurate amounts of vapor from low vapor pressure explosive materials is a pressing need within the explosives detection community. Of particular importance for reproducibility and widespread acceptance of results is the correlation of such a vapor generator to a National Institute of Standards and Technology (NIST) mass standard. This paper describes an explosives vapor generator recently developed at Varian in which a solid explosive sample in a precision bore glass tube is put in an oven at constant temperature, and vapor diff-using from the top of the tube is entrained in a carrier gas flow. The rate of vapor output is thus dependent on both the equilibrium vapor pressure of the solid at oven temperature and the rate of diffusion up the length of the tube. Correlation to a NIST mass standard is achieved by periodic weighing of the sample tube on a microbalance. We report results obtained with the explosives TNT and RDX. Results for TNT show that the mass output rate is constant over hundreds of hours of continuous use, with outputs of {approximately} 10--2000 pg/sec for oven temperatures in the range of 60--120{degrees}C. Both the mass loss experiments and calibration with an ion mobility spectrometer (IMS) give a TNT mass output value of 85 pg/sec at 79{degrees}C, and this result is supported by transport theory calculations. Mass loss curves for RDX are also linear with time, and show the expected exponential increase of mass output with oven temperature.

Parmeter, J.E.; Rhykerd, L. Jr.; Conrad, F.J. [Sandia National Labs., Albuquerque, NM (United States); Tiano, G.S.; Preston, D.; Eiceman, G.A. [New Mexico State Univ., Las Cruces, NM (United States). Dept. of Chemistry and Biochemistry; Arnold, J.T. [Varian Associates, Palo Alto, CA (United States). Ginzton Research Laboratory

1995-12-31

87

A Numerical Method for Multiphase Incompressible Thermal Flows with Solid-Liquid and Liquid-Vapor Phase Transformations  

Microsoft Academic Search

A numerical method for multiphase incompressible thermal flows with solid–liquid and liquid–vapor phase transformations is presented. The flow is mainly driven by thermocapillary force and vaporization. Based on the level set method and mixture continuum model, a set of governing equations valid for solid, liquid, and vapor phases is derived, considering phase boundary conditions as source terms in the transport

Hyungson Ki; Pravansu S. Mohanty; Jyoti Mazumder

2005-01-01

88

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

PubMed

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

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

2014-07-01

89

Homogeneous nucleation of particles from the vapor phase in thermal plasma synthesis  

Microsoft Academic Search

Particle nucleation and growth are simulated for iron vapor in a thermal plasma reactor with an assumed one-dimensional flow field and decoupled chemistry and aerosol dynamics. Including both evaporation and coagulation terms in the set of cluster-balance rate equations, a sharply defined homogeneous nucleation event is calculated. Following nucleation the vapor phase is rapidly depleted by condensation, and thereafter particle

S. L. Girshick; C.-P. Chiu

1989-01-01

90

Molecular Orbital Studies of Titanium Nitride Chemical Vapor Deposition: Gas Phase Complex Formation,  

E-print Network

Molecular Orbital Studies of Titanium Nitride Chemical Vapor Deposition: Gas Phase Complex Received June 6, 2000 The chemical vapor deposition (CVD) of titanium nitride can be carried out with TiCl4 Titanium nitride thin films have a variety of proper- ties, such as extreme hardness, high chemical

Schlegel, H. Bernhard

91

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...

92

Electronic cigarettes. Potential harms and benefits.  

PubMed

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

Drummond, M Bradley; Upson, Dona

2014-02-01

93

The mode of lymphoblastoid cell death in response to gas phase cigarette smoke is dose-dependent  

PubMed Central

Background Cigarette smoke (CS) is the main cause in the development of chronic obstructive pulmonary disease (COPD), the pathogenesis of which is related to an extended inflammatory response. In this study, we investigated the effect of low and high doses of gas phase cigarette smoke (GPS) on cultured lymphocyte progenitor cells, using techniques to assess cell viability and to elucidate whether cells die of apoptosis or necrosis upon exposure to different doses of GPS. Methods In our approach we utilised a newly-established system of exposure of cells to GPS that is highly controlled, accurately reproducible and simulates CS dosage and kinetics that take place in the smokers' lung. This system was used to study the mode of cell death upon exposure to GPS in conjunction with a range of techniques widely used for cell death studies such as Annexin V staining, activation of caspase -3, cytoplasmic release of cytochrome C, loss of mitochondrial membrane potential and DNA fragmentation. Results Low doses of GPS induced specific apoptotic indexes in CCRF-CEM cells. Specifically, cytochrome C release and cleaved caspase-3 were detected by immunofluorescence, upon treatment with 1-3 puffs GPS. At 4 h post-exposure, caspase-3 activation was observed in western blot analysis, showing a decreasing pattern as GPS doses increased. Concomitant with this behaviour, a dose-dependent change in ??m depolarization was monitored by flow cytometry 2 h post-exposure, while at 4 h ??m collapse was observed at the higher doses, indicative of a shift to a necrotic demise. A reduction in DNA fragmentation events produced by 5 puffs GPS as compared to those provoked by 3 puffs GPS, also pointed towards a necrotic response at the higher dose of GPS. Conclusion Collectively, our results support that at low doses gas phase cigarette smoke induces apoptosis in cultured T-lymphocytes, whereas at high doses GPS leads to necrotic death, by-passing the characteristic stage of caspase-3 activation and, thus, the apoptotic route. PMID:19744320

2009-01-01

94

Comparative Study of Solution Phase and Vapor Phase Deposition of Aminosilanes on Silicon Dioxide Surfaces  

PubMed Central

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

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

2014-01-01

95

Vapor-condensed phase processes in the early solar system  

NASA Astrophysics Data System (ADS)

Equilibrium thermodynamic calculations of the sequence of condensation of phases from a cooling gas of solar composition at total pressures thought to have prevailed in the inner part of the solar nebula successfully predict the primary mineral assemblages of refractory inclusions in CM2 and CV3 chondrites. Many refractory inclusions in CM2 chondrites contain a relatively SiO2-poor assemblage (spinel, hibonite, grossite, perovskite, corundum) that represents a high-temperature stage of condensation, and some may be pristine condensates that escaped later melting. Compact Type A and Type B refractory inclusions, consisting of spinel, melilite, perovskite, Ca-rich clinopyroxene +/- anorthite, in CV3 chondrites are more SiO2-rich and equilibrated with the solar nebular gas at a slightly lower temperature. Textures of many of these objects indicate that they underwent melting after condensation, crystallizing into the same phase assemblage as their precursors. The Ti3+/Ti4+ ratio of their pyroxene indicates that this process occurred in a gas whose oxygen fugacity () was approximately 8.5 log units below that of the iron-wüstite buffer, making them the only objects in chondrites known to have formed in a system whose composition was close to that of the sun. Relative to CI chondrites, these inclusions are uniformly enriched in a group of elements (e.g., Ca, REE, Zr, Ta, Ir) that are chemically diverse except for their high condensation temperatures in a system of solar composition. The enrichment factor, 17.5, can be interpreted to mean that these objects represent either the first 5.7 wt% of the condensable matter to condense during nebular cooling or the residue after vaporization of 94.3% of a CI chondrite precursor. The Mg and Si isotopic compositions of Types A and B inclusions are mass-fractionated by up to 10 and 4 ‰/amu, respectively. When interpreted in terms of Rayleigh fractionation during evaporation of Mg and Si from the inclusions while they were molten, the isotopic compositions imply that up to 60% of the Mg and up to 25% of the Si were evaporated, and that approximately 80% of the enrichment in refractory (CaO+Al2O3) relative to more volatile (MgO+SiO2) in the average inclusion is due to initial condensation and approximately 20% due to subsequent evaporation. The mineralogical composition, including the Ti3+/Ti4+ ratio of the pyroxene, in Inti, a particle sampled from Comet Wild 2 by the Stardust spacecraft, is nearly identical to that of a Type B inclusion, indicating that comets contain not only the lowest-temperature condensates in the form of ices but the highest-temperature condensates as well. The FeO/(FeO+MgO) ratios of olivine and pyroxene in the matrix and chondrules of carbonaceous and ordinary chondrites are too high to be made in a system of solar composition, requiring s only 1 or 2 log units below iron-wüstite, more than 105 times higher than that of a solar gas. Various ways have been devised to generate cosmic gases sufficiently oxidizing to stabilize significant FeO in olivine at temperatures above those where Fe-Mg interdiffusion in olivine ceases. One is by vertical settling of dust toward the nebular midplane, enriching a region in dust relative to gas. Because dust is enriched in oxygen compared to carbon and hydrogen relative to solar composition, a higher results from total vaporization of the region, but the factor by which theoretical models have so far enriched the dust is 10 times too low. Another is by transporting icy bodies from the outer part of the nebula into the hot, inner part where vaporization of water ice occurs. Not only does this method fail to make the needed by a factor of 30-1000 but it also ignores simultaneous evaporation of carbon-bearing ices that would make the even lower.

Grossman, Lawrence

2010-01-01

96

XeF2 vapor phase silicon etch used in the fabrication of movable SOI structures  

Microsoft Academic Search

Vapor phase XeF has been used in the fabrication of various types of devices including MEMS, resonators, RF switches, and micro-fluidics, and for wafer level packaging. In this presentation we demonstrate the use of XeF Si etch in conjunction with deep reactive ion etch (DRIE) to release single crystal Si structures on Silicon On Insulator (SOI) wafers. XeF vapor phase

M. Wiwi; Carlos Anthony Sanchez; Thomas Alvin Plut; M. Salazar; Jeffrey Stevens; Todd M. Bauer; C. Ford; Randy John Shul; Grant David Grossetete

2010-01-01

97

The particulate and vapor phase components of airborne polyaromatic hydrocarbons (PAHs) in coal gasification pilot plants  

E-print Network

THE PARTICULATE AND VAPOR PHASE COMPONENTS OF AIRBORNE POLYAROMATIC HYDROCARBONS(PAHs) IN COAL GASIFICATION PILOT PLANTS A Thesis by ERIC JON BRINK Submitted to the Graduate College of Texas A & M University in partial fulfillment... of the requirement for the degree of MASTER OF SCIENCE December 1980 Major Subject: Industrial Hygiene THE PARTICULATE AND VAPOR PHASE COMPONENTS OF AIRBORNE POLYAROMATIC HYDROCARBONS (PAHs) IN COAL GASIFICATION PILOT PLANTS A Thesis by ERIC JON BRINK...

Brink, Eric Jon

1980-01-01

98

Vapor-phase self-assembled monolayers for improved MEMS reliability  

Microsoft Academic Search

This paper presents the application of vapor-phase DDMS (dichlorodimethylsilane) self-assembled monolayer (SAM) coating which significantly reduced stiction behavior in optical MEMS components exposed to humidity. Previously SAMs have been deposited in liquid form, making them unsuitable for application in high aspect ratio MEMS\\/NEMS structures; now vapor-phase SAM deposition is a novel option for improving MEMS in-use reliability. DDMS and ODS

Anna Rissanen; Kirsi Tappura; Mari Laamanen; Riikka Puurunen; Elina Färm; Mikko Ritala; Markku Leskelä

2010-01-01

99

Third harmonic generation in phase-matched alkali metal vapors  

NASA Technical Reports Server (NTRS)

We report improvements in conversion efficiency for third harmonic generation in sodium and rubidium vapor. 30-psec pulses of radiation at 1.064 micron have been converted to 0.3547 micron with an energy conversion efficiency of 10%. Factors limiting conversion efficiency are discussed.

Bloom, D. M.; Young, J. F.; Harris, S. E.; Bekkers, G. W.

1975-01-01

100

A Level Set Method for vaporizing two-phase flows  

NASA Astrophysics Data System (ADS)

Development and applications of numerical methods devoted to reactive interface simulations are presented. Emphasis is put on vaporization, where numerical difficulties arise in imposing accurate jump conditions for heat and mass transfers. We use both the Level Set Method and the Ghost Fluid Method to capture the interface motion accurately and to handle suitable jump conditions. A local vaporization mass flow rate per unit of surface area is defined and Stefan flow is involved in the process. Specific care has been devoted to the extension of discontinuous variables across the interface to populate ghost cells, in order to avoid parasitic currents and numerical diffusion across the interface. A projection method is set up to impose both the velocity field continuity and a divergence-free condition for the extended velocity field across the interface. The d2 law is verified in the numerical simulations of the vaporization of an isolated static drop. Results are then presented for a water droplet moving in air. Vapor mass fraction and temperature fields inside and outside the droplet are presented.

Tanguy, Sébastien; Ménard, Thibaut; Berlemont, Alain

2007-02-01

101

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...

102

Student Understanding of Liquid-Vapor Phase Equilibrium  

ERIC Educational Resources Information Center

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…

Boudreaux, Andrew; Campbell, Craig

2012-01-01

103

Vapor-Phase Stoichiometry and Heat Treatment of CdTe Starting Material for Physical Vapor Transport  

NASA Technical Reports Server (NTRS)

Six batches of CdTe, having total amounts of material from 99 to 203 g and gross mole fraction of Te, X(sub Te), 0.499954-0.500138, were synthesized from pure Cd and Te elements. The vapor-phase stoichiometry of the assynthesized CdTe batches was determined from the partial pressure of Te2, P(sub Te2) using an optical absorption technique. The measured vapor compositions at 870 C were Te-rich for all of the batches with partial pressure ratios of Cd to Te2, P(sub Cd)/P(sub Te2), ranging from 0.00742 to 1.92. After the heat treatment of baking under dynamic vacuum at 870 C for 8 min, the vapor-phase compositions moved toward that of the congruent sublimation, i.e. P(sub Cd)/P(sub Te2) = 2.0, with the measured P(sub Cd)/P(sub Te2) varying from 1.84 to 3.47. The partial pressure measurements on one of the heat-treated samples also showed that the sample remained close to the congruent sublimation condition over the temperature range 800-880 C.

Su, Ching-Hua; Sha, Yi-Gao; Lehoczky, S. L.; Liu, Hao-Chieh; Fang, Rei; Brebrick, R. F.

1998-01-01

104

The intractable cigarette ‘filter problem’  

PubMed Central

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

2011-01-01

105

Infrared analysis of vapor phase deposited tricresylphosphate (TCP)  

NASA Technical Reports Server (NTRS)

Infrared transmission was employed to study the formation of a lubricating film deposited on two different substrates at 700 C. The deposit was formed from tricresylphosphate vapors and collected onto a NaCl substrate and on an iron coated NaCl substrate. Analysis of the infrared data suggests that a metal phosphate is formed initially, followed by the formation of organophosphorus polymeric compounds.

Morales, Wilfredo; Hanyaloglu, Bengi; Graham, Earl E.

1994-01-01

106

Producing titanium powder by continuous vapor-phase reduction  

Microsoft Academic Search

One of the goals of the U.S. Department of Energy's Albany Research Center is to reduce the cost of titanium parts by developing a continuous titanium process. In this work, titanium powder was produced by feeding liquid TiCl4, with argon as a carrier gas, and magnesium wire into a shaft reactor at 1,000°C. The magnesium and TiCl4 vaporized and reacted

Dennis A. Hansen; Stephen J. Gerdemann

1998-01-01

107

Producing titanium powder by continuous vapor-phase reduction  

Microsoft Academic Search

One of the goals of the U.S. Department of Energy’s Albany Research Center is to reduce the cost of titanium parts by developing\\u000a a continuous titanium process. In this work, titanium powder was produced by feeding liquid TiCl4, with argon as a carrier gas, and magnesium wire into a shaft reactor at 1,000C. The magnesium and TiCl4 vaporized and reacted

Dennis A. Hansen; Stephen J. Gerdemann

1998-01-01

108

Growth Rates of Potassium Crystal from the Vapor Phase  

Microsoft Academic Search

Measurements of the growth rate of potassium (110) faces, for low vapor supersaturations ? between 3.1 and 0.11 (the lowest value studied) have given unit condensation coefficients for all supersaturations. This result is in agreement with the theory of Burton, Cabrera, and Frank and gives the values ?C0 = 1, ?1?0.046 for potassium. No evidence of two-dimensional surface nucleation was

R. L. Parker

1962-01-01

109

Evidence for extreme partitioning of copper into a magmatic vapor phase.  

PubMed

The discovery of copper sulfides in carbon dioxide- and chlorine-bearing bubbles in phenocryst-hosted melt inclusions shows that copper resides in a vapor phase in some shallow magma chambers. Copper is several hundred times more concentrated in magmatic vapor than in coexisting pantellerite melt. The volatile behavior of copper should be considered when modeling the volcanogenic contribution of metals to the atmosphere and may be important in the formation of copper porphyry ore deposits. PMID:17772911

Lowenstern, J B; Mahood, G A; Rivers, M L; Sutton, S R

1991-06-01

110

Bundles of carbon nanotubes generated by vapor-phase growth Maohui Ge and Klaus Sattler  

E-print Network

-phase condensation of carbon on highly oriented pyrolytic graphite and analyzed by scanning tunneling microscopy of carbon on a highly oriented pyrolytic graphite (HOPG) substrate in ultrahigh vacuum (UHV). The graphiteBundles of carbon nanotubes generated by vapor-phase growth Maohui Ge and Klaus Sattler Department

Sattler, Klaus

111

Geometric Phase in the Condensed Vapor of rb Under Pressure and External Magnetic Field  

NASA Astrophysics Data System (ADS)

By using the Lewis-Riesenfeld invariant theory, we have studied the geometric phase in the condensed vapor of Rb under pressure and external time-dependent magnetic field. We find that the geometric phase in the cycle case has nothing to do with the coupling constant between electron and atomic nucleus, and the external time-dependent magnetic field.

Yu, Zhao-Xian; Jiao, Zhi-Yong; Li, Xiang-Gui

112

Vapor-Phase Lubricants: Nanometer-scale Lubrication Mechanisms and Uptake on Silicon  

NASA Astrophysics Data System (ADS)

The concept of lubricating high temperature bearing surfaces with organic vapors which react with a surface to form a solid lubricating film has existed for at least forty years, with substantial efforts beginning in the 1980's and continuing to the present day. While vapor-phase lubricants have primarily been studied within the context of macroscopic system performance, they may well prove to be of critical importance to tribological performance in sub-micron mechanical systems as well. This is because the vapor phase may ultimately prove to be the most effective, if not only, means to deliver and/or replenish a lubricant that can withstand a variety of extreme environmental conditions that a MEMS device is likely to encounter. In order to investigate the viability of vapor-phase lubrication for MEMS applications, we have studied molecular scale tribological properties and gas uptake rates for four known organophosphate lubricants in controlled environments on silicon and gold substrates. The first study involves Quartz Crystal Microweighing investigations of the uptake rates of lubricant vapors from the vapor phase in vacuum conditions. With the intent of modelling actual MEMS contacts, we have also constructed a simple nanomechanical system consisting of a Scanning Tunneling Microscope tip dragging on the surface of a Quartz Crystal Microbalance electrode. This system allows us to monitor lubricant performance in realistic sliding conditions of up to 2 m/s. Finally, work is in progress to study the effect of these vapor-phase lubricants on actual MEMS devices with contacting silicon surfaces. Work supported by NSF and AFOSR.

Neeyakorn, Worakarn; Varma, Manju; Jaye, Cherno; Hook, Adam; Krim, Jacqueline

2004-03-01

113

Identification of stable cytotoxic factors in the gas phase extract of cigarette smoke and pharmacological characterization of their cytotoxicity.  

PubMed

Smoking is a major risk factor for atherosclerotic vascular diseases, but the mechanism for its genesis is unknown. We have recently shown that the gas phase of cigarette smoke (nicotine- and tar-free cigarette smoke extract; CSE) likely to reach the systemic circulation contains stable substances which cause cytotoxicity like plasma membrane damage and cell death in cultured cells, and also that the plasma membrane damage is caused through sequential activation of protein kinase C (PKC) and NADPH oxidase (NOX) and the resulting generation of reactive oxygen species (PKC/NOX-dependent mechanism), whereas cell death is caused through PKC/NOX-dependent and -independent mechanisms. To identify these stable substances, the CSE was prepared by passing the main-stream smoke of 10 cigarettes through a Cambridge glass fiber filter, trapping of the smoke in a vessel cooled at -80°C, and subsequent dissolution in 10ml of water. The CSE was fractionated into nine fractions using reversed-phase HPLC, and each fraction was screened for cytotoxicity in cultured cells, using propidium iodide uptake assay for cell membrane damage and MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] reduction assay for cell viability. The cytotoxicity was positive in two of the nine fractions (Fr2 and Fr5). After extraction of the active fractions into dichloromethane, GC/MS analysis identified 2-cyclopenten-1-one (CPO) in Fr5 but none in Fr2. After derivatization of the active fractions with O-(2,3,4,5,6-pentafluorobenzyl) hydroxylamine hydrochloride, GC/MS analysis identified acrolein, acetone and propionaldehyde in Fr2, and methyl vinyl ketone (MVK) in Fr5. After 4-h incubation, authentic acrolein and MVK induced concentration-dependent cytotoxicity with EC50 values of 75.9±8.2 and 47.0±8.0?M (mean±SEM; n=3), respectively, whereas acetone, propionaldehyde and CPO were without effect. However, after 24-h incubation, CPO induced concentration-dependent cytotoxicity with an EC50 value of 264.0±16.9?M (n=3). The concentrations of acrolein, MVK and CPO in the CSE were 3368±334, 2429±123 and 392.9±31.8?M (n=4), respectively, which were higher than the cytotoxic concentrations. The cytotoxicity of acrolein and MVK consisted of plasma membrane damage and decreased cell viability: the plasma membrane damage was totally prevented by treatment with an inhibitor of PKC or NOX, whereas the decreased cell viability was only partially prevented by these inhibitors. The cytotoxicity of CPO consisted only of decreased cell viability, which was totally resistant to these inhibitors. These results show that acrolein and MVK are responsible for the acute cytotoxicity of the CSE through PKC/NOX-dependent and -independent mechanisms, whereas CPO is responsible for the delayed cytotoxicity of the CSE through a PKC/NOX-independent mechanism. PMID:23981515

Noya, Yoichi; Seki, Koh-Ichi; Asano, Hiroshi; Mai, Yosuke; Horinouchi, Takahiro; Higashi, Tsunehito; Terada, Koji; Hatate, Chizuru; Hoshi, Akimasa; Nepal, Prabha; Horiguchi, Mika; Kuge, Yuji; Miwa, Soichi

2013-12-01

114

Liquid-vapor and solid-liquid-vapor phase equilibria in natural gas systems. Annual report 1 Jan 83-1 Jan 84  

SciTech Connect

Solid-liquid-vapor phase equilibria were measured for the binary systems carbon dioxide plus methane, carbon dioxide plus ethane, and carbon dioxide plus propane over the temperature region 204 to 216 K. Vapor-liquid phase equilibria were measured for carbon dioxide plus methane at 212 K, carbon dioxide plus ethane at 204, 209, and 212 K, and carbon dioxide plus propane at 216 K.

Kidney, A.J.; Sloan, E.D.

1984-01-01

115

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

SciTech Connect

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.

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

2008-01-01

116

Bottom-up nanofabrication through catalyzed vapor phase HF etching of SiO2  

NASA Astrophysics Data System (ADS)

We show that a wide range of inorganic and organic molecules or nanostructures can enhance the vapor phase HF etching of SiO2 resulting in a negative tone pattern transfer to a SiO2 substrate. The templates used in this study include micron- and nanometer-sized NaCl crystals, graphene oxide flakes, and albumin molecules. In all cases, a negative-tone pattern transfer to the underlying SiO2 substrate was obtained. The results suggest that vapor phase HF etching could be a general purpose pattern transfer technique for nanoscale and supramolecular templates.

Zhao, Shichao; Liu, Haitao

2015-01-01

117

Toxicological assessment of kretek cigarettes Part 6: the impact of ingredients added to kretek cigarettes on smoke chemistry and in vitro toxicity.  

PubMed

Mainstream smoke (MS) from experimental kretek cigarettes with three ingredient mixes at low (typical use level) and high (2.5 or 3 times that level) inclusion rates was compared to a control kretek cigarette of identical construction (cloves and humectants), but without the addition of ingredients. 350 ingredients, commonly used in various combinations and in a limited number in a given brand in the manufacture of marketed kretek cigarettes were assessed. The MS composition of the kretek cigarettes was characterized by a comprehensive set of analytes (55 smoke constituents). Furthermore, the smoke was assessed in vitro for its cytotoxicity in the Neutral Red Uptake assay (particle phase and gas/vapor phase separately) in mouse embryo BALB/c 3T3 cells, and for mutagenicity/genotoxicity in the Salmonella typhimurium reverse mutation assay and the mammalian cell mouse lymphoma TK assay in L5178Y cells, the latter with and without metabolic activation. There were some statistically significant differences in the yield of smoke constituents (increases as well as decreases, nearly all of them less than ± 20%) as a result of the addition of the ingredient mixes. However, the addition of the three different mixes of ingredients to the experimental kreteks did not change the in vitro cytotoxicity and mutagenicity/genotoxicity of the smoke, when compared to the control kretek cigarette. PMID:25496764

Roemer, E; Dempsey, R; Hirter, J; Deger Evans, A; Weber, S; Ode, A; Wittke, S; Schorp, M K

2014-12-01

118

Condensed phase conversion and growth of nanorods and other materials instead of from vapor  

DOEpatents

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 phase matrix material instead of from vapor. 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.

Geohegan, David B. (Knoxville, TN); Seals, Roland D. (Oak Ridge, TN); Puretzky, Alex A. (Knoxville, TN); Fan, Xudong (Oak Ridge, TN)

2010-10-19

119

High power laser fiber fabricated through vapor phase doping of Ytterbium  

NASA Astrophysics Data System (ADS)

We present the characteristics of an ytterbium-doped alumino-silicate fiber, fabricated through vapor phase doping of aluminum and ytterbium in the core, along with silica and in conjunction with the modified chemical vapor deposition process. The vapor phase doping of rare-earths provides the opportunity to fabricate large core active fibers with a uniform distribution of dopants. The fibers fabricated exhibited low OH? content, negligible center dip and good optical properties. Lasing performance was tested up to output power of 105?W, with a slope efficiency of 77% with respect to launched pump power. The linear variation of the laser power with a pump shows its potentiality for further power scaling.

Sen, R.; Saha, M.; Pal, A.; Pal, M.; Leich, M.; Kobelke, J.

2014-08-01

120

Producing titanium powder by continuous vapor-phase reduction  

NASA Astrophysics Data System (ADS)

One of the goals of the U.S. Department of Energy’s Albany Research Center is to reduce the cost of titanium parts by developing a continuous titanium process. In this work, titanium powder was produced by feeding liquid TiCl4, with argon as a carrier gas, and magnesium wire into a shaft reactor at 1,000°C. The magnesium and TiCl4 vaporized and reacted to produce a mixture of titanium, MgCl2, and magnesium powder. Ti/Mg/MgCl2 powder was removed from the argon gas stream by an electrostatic precipitator, and the titanium powder was separated from the magnesium and MgCl2 by either vacuum distillation or leaching. Vacuum distillation produced sintered titanium powder with lower oxygen levels, but unacceptably high levels of magnesium and chlorine. Leached powder was spherical and free-flowing with low levels of magnesium and chlorine, but the oxygen content was no lower than 0.82%. The high oxygen content of the leached powder is caused by surface oxidation of the submicrometer titanium powder.

Hansen, Dennis A.; Gerdemann, Stephen J.

1998-11-01

121

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...

122

Control Approach for Mitigating Off-Axis Position Variation in Vapor-Phase Axial Deposition  

Microsoft Academic Search

VAD (vapor-phase axial deposition) is a widely used glass soot fabrication process for the creation of high purity optical glass fiber. It is critical for low signal loss and manufacturing productivity that the core and clad geometry remain constant. Variation (off-axis) of the deposition torch position relative to the deposited core soot tip can cause an appreciable change in the

Hodge E. Jenkins; R. Radharamanan

2007-01-01

123

Sulfur Impregnation on Activated Carbon Fibers through H2S Oxidation for Vapor Phase  

E-print Network

Sulfur Impregnation on Activated Carbon Fibers through H2S Oxidation for Vapor Phase Mercury: Sulfur was impregnated onto activated carbon fibers ACFs through H2S oxidation catalyzed by the sorbent surface in a fixed-bed reactor. By changing the temperature and duration of the sulfur impregnation

Borguet, Eric

124

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...

125

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...

126

The control of gas phase kinetics to maximize densification during chemical vapor infiltration  

Microsoft Academic Search

A serious problem during the fabrication of composite materials by isothermal chemical vapor infiltration is that the matrix forms more rapidly at the external edges of the body and traps a large amount of porosity inside. In theory, this problem can be eliminated by controlling the gas-phase kinetics to obtain densification which is more rapid in the center of a

Brian W. Sheldon

1990-01-01

127

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

128

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

Microsoft Academic Search

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

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

2009-01-01

129

Organic vapor phase deposition for the growth of large area organic electronic devices  

Microsoft Academic Search

We demonstrate that material utilization efficiencies of 50% and deposition nonuniformities <=2.5% are achievable over substrate diameters of 200 mm using a simplified, organic vapor phase deposition (OVPD) system. The OVPD system is used to demonstrate doped electrophosphorescent organic light emitting diodes whose performance is comparable to those grown by vacuum thermal evaporation. Through continuum modeling, we demonstrate that analogous

Richard R. Lunt; Brian E. Lassiter; Jay B. Benziger; Stephen R. Forrest

2009-01-01

130

Organic vapor phase deposition for the growth of large area organic electronic devices  

Microsoft Academic Search

We demonstrate that material utilization efficiencies of 50% and deposition nonuniformities ?2.5% are achievable over substrate diameters of 200 mm using a simplified, organic vapor phase deposition (OVPD) system. The OVPD system is used to demonstrate doped electrophosphorescent organic light emitting diodes whose performance is comparable to those grown by vacuum thermal evaporation. Through continuum modeling, we demonstrate that analogous

Richard R. Lunt; Brian E. Lassiter; Jay B. Benziger; Stephen R. Forrest

2009-01-01

131

Vapor-Phase Growth Kinetics of Potassium Whiskers by Field Emission  

Microsoft Academic Search

Using the method originated by Gomer, we have studied the growth kinetics of potassium whiskers, as they grow from the vapor phase in an electron field emission tube. To the best of our knowledge, this represents the first use of an alkali metal as a field emitter.The results for potassium whiskers show some features similar to those previously found for

R. L. Parker; S. C. Hardy

1962-01-01

132

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...

133

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

Microsoft Academic Search

This report summarizes work of this project from October 2003 through March 2004. The major focus of the research was to further investigate BTEX removal from produced water, to quantify metal ion removal from produced water, and to evaluate a lab-scale vapor phase bioreactor (VPB) for BTEX destruction in off-gases produced during SMZ regeneration. Batch equilibrium sorption studies were conducted

Lynn E. Katz; Kerry A. Kinney; R. S. Bowman; E. J. Sullivan

2004-01-01

134

Modification of fly ash composition via additive addition in the vapor phase  

Microsoft Academic Search

The most troublesome impurities in the fossil fuels are ash constituents, which accumulate on heat transfer surfaces in boiler furnaces. The mechanism of high-temperature fouling was investigated on a large utility boiler. It was found that vapor phase addition of an additive produces scales that are nonadherent, preventing high-temperature fouling and corrosion. A method of estimating scale friability from the

S. N. S

1977-01-01

135

Highly efficient detection of hydrogen peroxide in solution and in the vapor phase via fluorescence quenching.  

PubMed

Herein we report the highly efficient and sensitive detection of hydrogen peroxide in both aqueous solution and in the vapor phase via fluorescence quenching (turn-off mechanism) of the amplified fluorescent conjugated polymer-titanium complex induced by hydrogen peroxide. Inter- and intra-polymer energy migration leads to extremely high sensitivity. PMID:25806424

Marks, Patrick; Radaram, Bhasker; Levine, Mindy; Levitsky, Igor A

2015-04-25

136

VAPOR PHASE MERCURY SORPTION BY ORGANIC-SULFIDE COATED BIMETALLIC IRON-COPPER NANOPARTICLE AGGREGATES  

EPA Science Inventory

Tetra sulfide silane coated iron-copper nano-particle aggregates are found to be potentially very high capacity sorbents for vapor phase mercury capture. High equilibrium capacities were obtained for the silane coated iron copper nano-aggregate sorbent at 70 oC and 120 oC. Even a...

137

ORIGINAL PAPER Dynamics of Vapor-phase Organophosphates on Silicon and OTS  

E-print Network

ORIGINAL PAPER Dynamics of Vapor-phase Organophosphates on Silicon and OTS Worakarn Neeyakorn Æ of the uptake and nanotribology of organophosphate (tricresylphosphate (TCP) and t-butyl phenyl phosphate (TBPP applications. About 3­5 monolayer-thick organophosphate films are observed to form readily on both silicon

Krim, Jacqueline

138

Growth and morphology of Er-doped GaN on sapphire and hydride vapor phase epitaxy substrates  

E-print Network

Growth and morphology of Er-doped GaN on sapphire and hydride vapor phase epitaxy substrates R properties of Er-doped GaN grown by solid source molecular beam epitaxy on sapphire and hydride vapor phase epitaxy GaN substrates. The GaN was grown by molecular beam epitaxy on sapphire substrates using solid

Steckl, Andrew J.

139

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

E-print Network

lubrication by Fe chemical vapor deposition from Fe(CO)5 Daxing Ren, Dougyong Sung and Andrew J. Gellman to the vapor phase lubrication of ceramics using organophosphorus compounds. The surface of SiC is shown phase lubricants such as tricresylphosphate. In order to activate the surface of SiC it has been exposed

Gellman, Andrew J.

140

Are Published Minimum Vapor Phase Spark Ignition Energy Data Valid?  

SciTech Connect

The use of sprayed flammable fluids as solvents in dissolution and cleaning processes demand detailed understanding of ignition and fire hazards associated with these applications. When it is not feasible to inert the atmosphere in which the spraying process takes place, then elimination of all possible ignition sources must be done. If operators are involved in the process, the potential for human static build-up and ultimate discharge is finite, and it is nearly impossible to eliminate. The specific application discussed in this paper involved the use of heated Dimethyl Sulfoxide (DMSO) to dissolve high explosives (HE). Search for properties of DMSO yielded data on flammability limits and flash point, but there was no published information pertaining to the minimum energy for electrical arc ignition. Due to the sensitivity of this procedure, The Hazards Control Department of Lawrence Livermore National Laboratory (LLNL) was tasked to determine the minimum ignition energy of DMSO aerosol and vapor an experimental investigation was thus initiated. Because there were no electrical sources in spray chamber, Human Electro-Static Discharge (HESD) was the only potential ignition source. Consequently, the electrostatic generators required for this investigation were designed to produce electrostatic arcs with the defined voltage and current pulse characteristics consistent with simulated human capacitance. Diagnostic procedures required to insure these characteristics involve specific data gathering techniques where the voltage and current sensors are in close proximity to the electrodes, thus defining the arc energy directly between the electrodes. The intriguing finding derived from this procedure is how small these measured values are relative to the arc energy as defined by the capacitance and the voltage measure at the capacitor terminals. The suggested reason for this difference is that the standard procedure for determining arc energy from the relation; E = 1/2CV{sup 2} does not account for the total capacitance and impedance of the system.

Staggs, K J; Alvares, N J; Greenwood, D W

2001-11-21

141

Gallium hydride vapor phase epitaxy of GaN nanowires  

PubMed Central

Straight GaN nanowires (NWs) with diameters of 50 nm, lengths up to 10 ?m and a hexagonal wurtzite crystal structure have been grown at 900°C on 0.5 nm Au/Si(001) via the reaction of Ga with NH3 and N2:H2, where the H2 content was varied between 10 and 100%. The growth of high-quality GaN NWs depends critically on the thickness of Au and Ga vapor pressure while no deposition occurs on plain Si(001). Increasing the H2 content leads to an increase in the growth rate, a reduction in the areal density of the GaN NWs and a suppression of the underlying amorphous (?)-like GaN layer which occurs without H2. The increase in growth rate with H2 content is a direct consequence of the reaction of Ga with H2 which leads to the formation of Ga hydride that reacts efficiently with NH3 at the top of the GaN NWs. Moreover, the reduction in the areal density of the GaN NWs and suppression of the ?-like GaN layer is attributed to the reaction of H2 with Ga in the immediate vicinity of the Au NPs. Finally, the incorporation of H2 leads to a significant improvement in the near band edge photoluminescence through a suppression of the non-radiative recombination via surface states which become passivated not only via H2, but also via a reduction of O2-related defects. PMID:21711801

2011-01-01

142

Gallium hydride vapor phase epitaxy of GaN nanowires  

NASA Astrophysics Data System (ADS)

Straight GaN nanowires (NWs) with diameters of 50 nm, lengths up to 10 ?m and a hexagonal wurtzite crystal structure have been grown at 900°C on 0.5 nm Au/Si(001) via the reaction of Ga with NH3 and N2:H2, where the H2 content was varied between 10 and 100%. The growth of high-quality GaN NWs depends critically on the thickness of Au and Ga vapor pressure while no deposition occurs on plain Si(001). Increasing the H2 content leads to an increase in the growth rate, a reduction in the areal density of the GaN NWs and a suppression of the underlying amorphous (?)-like GaN layer which occurs without H2. The increase in growth rate with H2 content is a direct consequence of the reaction of Ga with H2 which leads to the formation of Ga hydride that reacts efficiently with NH3 at the top of the GaN NWs. Moreover, the reduction in the areal density of the GaN NWs and suppression of the ?-like GaN layer is attributed to the reaction of H2 with Ga in the immediate vicinity of the Au NPs. Finally, the incorporation of H2 leads to a significant improvement in the near band edge photoluminescence through a suppression of the non-radiative recombination via surface states which become passivated not only via H2, but also via a reduction of O2-related defects.

Zervos, Matthew; Othonos, Andreas

2011-12-01

143

Gallium hydride vapor phase epitaxy of GaN nanowires.  

PubMed

Straight GaN nanowires (NWs) with diameters of 50 nm, lengths up to 10 ?m and a hexagonal wurtzite crystal structure have been grown at 900°C on 0.5 nm Au/Si(001) via the reaction of Ga with NH3 and N2:H2, where the H2 content was varied between 10 and 100%. The growth of high-quality GaN NWs depends critically on the thickness of Au and Ga vapor pressure while no deposition occurs on plain Si(001). Increasing the H2 content leads to an increase in the growth rate, a reduction in the areal density of the GaN NWs and a suppression of the underlying amorphous (?)-like GaN layer which occurs without H2. The increase in growth rate with H2 content is a direct consequence of the reaction of Ga with H2 which leads to the formation of Ga hydride that reacts efficiently with NH3 at the top of the GaN NWs. Moreover, the reduction in the areal density of the GaN NWs and suppression of the ?-like GaN layer is attributed to the reaction of H2 with Ga in the immediate vicinity of the Au NPs. Finally, the incorporation of H2 leads to a significant improvement in the near band edge photoluminescence through a suppression of the non-radiative recombination via surface states which become passivated not only via H2, but also via a reduction of O2-related defects. PMID:21711801

Zervos, Matthew; Othonos, Andreas

2011-01-01

144

Properties of nuclear waste melts and glasses: Contact-refractory corrosion and vapor phase hydration  

Microsoft Academic Search

Control of refractory corrosion in waste glass melts and meeting vapor phase hydration test (VHT) requirement for Hanford low-activity waste (LAW) glass product are two critical issues among many technical challenges of nuclear waste vitrification. In this study, refractory corrosion was treated as a complex non-equilibrium, multi-component and multi-phase reactive transport process and studied both thermodynamically and kinetically. Dissolution tests

Xiaodong Lu

2003-01-01

145

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

NASA Astrophysics Data System (ADS)

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.

von Niessen, Konstantin; Gindrat, Malko

2011-06-01

146

Solid and Vapor Phase UV Photocathodes for Gaseous Detectors  

SciTech Connect

We measured the relative quantum efficiency of four organic materials: tetrathiafulvalene and bis(cyclopentadienyl)magnesium in the solidphase and t-butylferrocene and n-butylferrocene in the vapour phase. The measurements were performed in the wavelength range of 150-220 nm. We also present a new quantum efficiency measurement of ethylferrocene. The three ferrocene derivatives exhibit relatively high quantum efficiency.

Vasileiadis, G.; Malamud, G.; Mine, P.; Vartsky, D.; /Ecole Polytechnique

2012-09-20

147

Phase-transition thresholds and vaporization phenomena for ultrasound phase-change nanoemulsions assessed via high-speed optical microscopy.  

PubMed

Ultrasonically activated phase-change contrast agents (PCCAs) based on perfluorocarbon droplets have been proposed for a variety of therapeutic and diagnostic clinical applications. When generated at the nanoscale, droplets may be small enough to exit the vascular space and then be induced to vaporize with high spatial and temporal specificity by externally-applied ultrasound. The use of acoustical techniques for optimizing ultrasound parameters for given applications can be a significant challenge for nanoscale PCCAs due to the contributions of larger outlier droplets. Similarly, optical techniques can be a challenge due to the sub-micron size of nanodroplet agents and resolution limits of optical microscopy. In this study, an optical method for determining activation thresholds of nanoscale emulsions based on the in vitro distribution of bubbles resulting from vaporization of PCCAs after single, short (<10 cycles) ultrasound pulses is evaluated. Through ultra-high-speed microscopy it is shown that the bubbles produced early in the pulse from vaporized droplets are strongly affected by subsequent cycles of the vaporization pulse, and these effects increase with pulse length. Results show that decafluorobutane nanoemulsions with peak diameters on the order of 200 nm can be optimally vaporized with short pulses using pressures amenable to clinical diagnostic ultrasound machines. PMID:23760161

Sheeran, Paul S; Matsunaga, Terry O; Dayton, Paul A

2013-07-01

148

Assessment of the Vapor Phase Catalytic Ammonia Removal (VPCAR) Technology at the MSFC ECLS Test Facility  

NASA Technical Reports Server (NTRS)

The Vapor Phase Catalytic Ammonia. Removal (VPCAR) technology has been previously discussed as a viable option for. the Exploration Water Recovery System. This technology integrates a phase change process with catalytic oxidation in the vapor phase to produce potable water from exploration mission wastewaters. A developmental prototype VPCAR was designed, built and tested under funding provided by a National Research. Announcement (NRA) project. The core technology, a Wiped Film Rotating Device (WFRD) was provided by Water Reuse Technologies under the NRA, whereas Hamilton Sundstrand Space Systems International performed the hardware integration and acceptance test. of the system. Personnel at the-Ames Research Center performed initial systems test of the VPCAR using ersatz solutions. To assess the viability of this hardware for Exploration. Life Support (ELS) applications, the hardware has been modified and tested at the MSFC ECLS Test facility. This paper summarizes the hardware modifications and test results and provides an assessment of this technology for the ELS application.

Tomes, Kristin; Long, David; Carter, Layne; Flynn, Michael

2007-01-01

149

Molecular dynamics simulation of liquid-vapor phase equilibria in polar fluids  

NASA Astrophysics Data System (ADS)

A new molecular dynamics simulation technique in the grand canonical ensemble [H. Eslami, F. Müller-Plathe, J. Comput. Chem. 28 (2007) 1763], has been employed to calculate the chemical potentials in the coexisting liquid and vapor phases of pure water, methanol, and acetonitrile. Calculating the chemical potentials in the liquid phase, a new method [J. Vrabec, H. Hasse, Mol. Phys. 100 (2002) 3375], has been employed to calculate the phase coexistence point. In this method just two independent simulations in the grand canonical ensemble are needed to be performed and the molecules are inserted into or deleted from the system in a dynamical way.

Eslami, Hossein; Dargahi, Ali; Behnejad, Hassan

2009-04-01

150

Vapor-phase self-assembled monolayers of aminosilane on plasma-activated silicon substrates.  

PubMed

Aminosilane self-assembled monolayers on silicon substrates have been prepared via a gas-phase procedure based on the consecutive reactions of the aminosilane precursor and water vapor. X-ray photoelectron spectroscopy, atomic force microscopy, and contact angle measurements have been used to characterize the aminosilane layers. For comparison, substrates modified with aminosilane through a liquid-phase procedure have been prepared and characterized by means of the same techniques. The vapor-based procedure was found to yield more uniform layers characterized by fewer and smaller aggregates as compared with liquid-treated substrates. Grazing angles reflection Fourier transform infrared measurements were carried out on the vapor-treated substrates before and after water exposure to investigate the hydrolysis of the alkoxy groups and further reaction to form siloxane bonds. The surface density of amino groups, as estimated through a colorimetric method, is very similar for vapor- and liquid-treated substrates, suggesting a similar reactivity and accessibility of the functional groups on the surface. PMID:18258249

Fiorilli, S; Rivolo, P; Descrovi, E; Ricciardi, C; Pasquardini, L; Lunelli, L; Vanzetti, L; Pederzolli, C; Onida, B; Garrone, E

2008-05-01

151

Novel Process for Removal and Recovery of Vapor Phase Mercury  

SciTech Connect

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.

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

1998-03-09

152

Mass Transport through the Carrier Gas Boundary Layer in Organic Vapor Phase Deposition  

NASA Astrophysics Data System (ADS)

We investigate the dynamics of molecular transport across the gas boundary layer formed above a cold substrate used in the organic vapor phase deposition of small organic molecules. The boundary layer properties ultimately determine film thickness uniformity and morphology, and material utilization efficiency. We use laser-induced fluorescence to spatially resolve the temperature and the concentration of organic molecules within the boundary layer. Under conditions typically used in organic vapor phase deposition of chamber pressures less than 5 torr, we find that the boundary layer extends to a remarkable distance of over 10 cm from the cooled substrate surface. Analytical and numerical models of molecular transport processes are developed to understand the transport of organic molecules to the substrate. Our models provide insights into conditions required to optimize film uniformity and material utilization efficiency in the growth of organic electronic devices.

Rolin, Cedric; Song, Byeongseop; Forrest, Stephen R.

2014-04-01

153

GaAs whiskers grown by metal-organic vapor-phase epitaxy using Fe nanoparticles  

NASA Astrophysics Data System (ADS)

GaAs nanowhiskers were grown by metal-organic vapor-phase epitaxy on (111)B GaAs substrates. The diameter of the nanowhiskers was defined by monodisperse Fe nanoparticles deposited on the GaAs substrate from the vapor phase. The growth temperature of the whiskers was investigated from 480to520°C. The whiskers are preferentially directed along the crystal orientations of ?001?, ?111?, and their equivalents. High-resolution transmission electron microscopy characterization including energy disperse x-ray spectroscopy measurements revealed not only iron oxide but also arsenic inside the seed particle at the top of the GaAs whiskers. This indicates that the particle stays at the top during the whisker growth.

Regolin, Ingo; Khorenko, Victor; Prost, Werner; Tegude, Franz J.; Sudfeld, Daniela; Kästner, Jochen; Dumpich, Günter; Hitzbleck, Klemens; Wiggers, Hartmut

2007-03-01

154

Exciton-exciton scattering in vapor phase ZnO nanoparticles  

NASA Astrophysics Data System (ADS)

Photoluminescence (PL) properties of suspended ZnO nanoparticles formed in vapor phase due to the condensation of the Nd:YAG laser ablated ZnO plasma species are investigated by varying both ablating and excitation intensity at different time delays with respect to the ablating pulse and at different axial distances from the target surface. Emission due to inelastic exciton-exciton (X-X) scattering is observed and is found to be dependent on the size of the vapor phase ZnO nanoparticles. The PL intensity shows nonlinear behavior with increasing ablating intensity, indicating generation and participation of more excitons in X-X scattering process in lager size ZnO nanoparticles.

Mohanta, Antaryami; Kung, Patrick; Thareja, Raj K.

2015-01-01

155

Characterization of High-Pressure Vapor-Phase Silicon Etching for MEMS Processing  

Microsoft Academic Search

Typical release for structures in microelectromechanical systems (MEMS) devices requires the use of sacrificial layers and wet etchants. As an alternative, bulk Si can be utilized for nonsilicon MEMS or structures as the sacrificial material when exposed to vapor-phase XeF2 . This paper presents the results of using relatively high pressures (> 3.0 torr) for the purpose of MEMS processing,

Clayton Easter; Chad B. O'Neal

2009-01-01

156

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

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

157

Removal of Oxygen from Electronic Materials by Vapor-Phase Processes  

NASA Technical Reports Server (NTRS)

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.

Palosz, Witold

1997-01-01

158

Phase composition and morphology of TaC coating on carbon fibers by chemical vapor infiltration  

Microsoft Academic Search

Chemical vapor infiltration was applied to deposit TaC thin film on carbon fibers using TaCl5–Ar–C3H6–H2 source. The influence of temperature, pressure and addition of H2 on phase composition and morphology of the coating had been studied. The results showed that the composition of the coating changes with temperature. The films are mainly composed of TaC and C when deposited at

Zhao-ke Chen; Xiang Xiong; Bai-yun Huang; Guo-dong Li; Feng Zheng; Peng Xiao; Hong-bo Zhang; Jian Yin

2008-01-01

159

Sorption equilibria of vapor-phase organic pollutants on unsaturated soils and soil minerals. Final report, Mar 85-Mar 89  

SciTech Connect

Most groundwater pollutants are volatile organic compounds; however, there is relatively little understanding of the sorption reactions that control the transport and fate of organic vapors in the vadose zone. This investigation identified the physical/chemical properties of the soil matrix and organic vapors which control vapor-solid phase distribution. The dominant property which regulates vapor sorption in the unsaturated zone is the moisture content of the soil. Under very dry conditions, soil mineral/vapor interactions are regulated by specific surface area, indicating the dominance of a relatively non-specific physical adsorption process. However, at moisture contents exceeding an average surface coverage of four to eight layers of water, vapor uptake is controlled by partitioning reactions into soil moisture and soil organic matter.

Lion, L.W.; Ong, S.K.; Linder, S.R.; Swager, J.L.; Schwager, S.J.

1990-04-01

160

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

NASA Astrophysics Data System (ADS)

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.

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

2015-01-01

161

A description of the vapor phase in the lithium thionyl chloride battery  

E-print Network

A DESCRIPTION OF TIIE YAPOP, PHASE IN THF. LITHIUM THIONYI. CHLORIDE BATTERY A Thesis by RODOLFO MORALES, JR. Submitted to the Graduate College of Texas AEzM University in partial fulfrHment of the requirement for the degree oi' MASTER... OF SCIENCE August 1988 Major Subject: Chemical Engineering A DESCRIPTION OF THE VAPOR PHASE IN THE LITHIUM THIONYL CHLORIDE BATTERY A Thesis bv RODOLFO 'vIORALES, JR. Approved as to style and content by: Ralph E. White (Chairman of Committee) James...

Morales, Rodolfo

1988-01-01

162

The mechanism of vapor phase hydration of calcium oxide: implications for CO2 capture.  

PubMed

Lime-based sorbents are used for fuel- and flue-gas capture, thereby representing an economic and effective way to reduce CO2 emissions. Their use involves cyclic carbonation/calcination which results in a significant conversion reduction with increasing number of cycles. To reactivate spent CaO, vapor phase hydration is typically performed. However, little is known about the ultimate mechanism of such a hydration process. Here, we show that the vapor phase hydration of CaO formed after calcination of calcite (CaCO3) single crystals is a pseudomorphic, topotactic process, which progresses via an intermediate disordered phase prior to the final formation of oriented Ca(OH)2 nanocrystals. The strong structural control during this solid-state phase transition implies that the microstructural features of the CaO parent phase predetermine the final structural and physicochemical (reactivity and attrition) features of the product hydroxide. The higher molar volume of the product can create an impervious shell around unreacted CaO, thereby limiting the efficiency of the reactivation process. However, in the case of compact, sintered CaO structures, volume expansion cannot be accommodated in the reduced pore volume, and stress generation leads to pervasive cracking. This favors complete hydration but also detrimental attrition. Implications of these results in carbon capture and storage (CCS) are discussed. PMID:25233236

Kud?acz, Krzysztof; Rodriguez-Navarro, Carlos

2014-10-21

163

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

PubMed Central

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

2013-01-01

164

Custom Mentholation of Commercial Cigarettes for Research Purposes  

PubMed Central

In the U.S. menthol remains the sole permitted characterizing cigarette flavor additive in part because efforts to link menthol cigarette use to increased tobacco-related disease risk have been inconclusive. To perform definitive studies, cigarettes that differ only in menthol content are required, yet these are not commercially available. We prepared research cigarettes differing only in menthol content by deposition of L-menthol vapor directly onto commercial nonmenthol cigarettes, and developed a method to measure a cigarette’s menthol and nicotine content. With our custom-mentholation technique we achieved the desired moderately high menthol content (as compared to commercial brands) of 6.7 ± 1.0 mg/g (n = 25) without perturbing the cigarettes’ nicotine content (17.7 ± 0.7 mg/g [n = 25]). We also characterized other pertinent attributes of our custom-mentholated cigarettes, including percent transmission of menthol and nicotine to mainstream smoke and the rate of loss of menthol over time during storage at room temperature. We are currently using this simple mentholation technique to investigate the differences in human exposure to selected chemicals in cigarette smoke due only to the presence of the added menthol. Our cigarettes will also aid in the elucidation of the effects of menthol on the toxicity of tobacco smoke. PMID:25621204

MacGregor, Ian C.; Stanfill, Stephen B.; Gordon, Sydney M.; Turner, Douglas J.; Butler, Jenny M.; Hanft, Elizabeth A.; Kim, Hyoshin; Kroeger, Robyn R.; Brinkman, Marielle C.; Tefft, Margaret E.; Clark, Pamela I.; Buehler, Stephanie S.

2014-01-01

165

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

PubMed

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

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

2014-11-18

166

Resonance enhanced Raman scatter in liquid benzene at vapor-phase absorption peaks.  

PubMed

The resonance enhanced Raman spectra in the 1B2u mode of the forbidden benzene electronic transition band, ~230-270 nm, has been investigated. Resonance enhanced Raman scattering in both liquid benzene and liquid toluene exhibit the greatest enhancement when the wavelength of excitation is tuned to the vapor-phase absorption peaks; even though the sample volume is in a liquid state. Raman signals for the symmetric breathing mode of the carbon ring are found to be resonantly enhanced by several orders of magnitude (>500X) with deep UV excitation compared to non-resonant visible excitation. Since the benzene absorbs near this resonant wavelength, its effect on the sampled volume cannot be neglected in determining the resonance gain, as we discuss in detail. Large resonant gains correspond with excitation at the 247, 253, and 259 nm absorption peaks in the benzene vapor spectrum. The narrow region of resonance gain is investigated in detail around the absorption peak located at 259 nm using 0.25 nm steps in the excitation wavelength. We observe the resonance gain tracking the vapor phase absorption peaks and valleys within this narrow range. Results are interpreted in terms of the coherence forced by the use of a forbidden transition for resonance excitation. PMID:24216839

Willitsford, Adam; Chadwick, C Todd; Hallen, Hans; Kurtz, Stewart; Philbrick, C Russell

2013-11-01

167

Ordered organic thin films self-assembled from the vapor phase  

NASA Technical Reports Server (NTRS)

Organic films self-assembled from a liquid phase, as in Langmuir-Blodgett or adsorption from solution, have received much attention in the past decade as techniques to achieve highly oriented-ordered polymeric thin films. Many organic compounds including some of the same fatty acids have been vapor deposited as well. However, organic pigments and dyes comprise a major class of important materials which have very low solubilities yet excellent thermal stabilities, making them ideally suited for film deposition from the vapor phase. Surprisingly, such molecular systems exhibit a significant propensity to self order, a high sensitivity to deposition parameters, and a range of microstructural forms that cannot be duplicated by the less energetic mechanisms associated with solution adsorption processes. Molecular solids such as heterocyclic polynuclear aromatics are excellent candidates for film formation by vacuum deposition means. Over the past decade, our work and that of others investigating a wide variety of perylene and phthalocyanine derivatives identified five deposition parameters that can significantly affect film morphology, physical microstructure, and type and extent of ordering developed in vacuum and vapor transport grown films. These parameters are substrate temperature, deposition rate, substrate chemistry and epitaxy, ambient gas convective flows, and post deposition annealing. Examples of how each of these conditions manifest themselves in the film structure and ordering, most frequently revealed by scanning electron microscopy, reflection absorption infrared spectroscopy (RAIR), and grazing incidence x-ray diffraction (GIX), are presented.

Debe, M. K.

1993-01-01

168

Electronic cigarettes: the road ahead.  

PubMed

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

Besaratinia, Ahmad; Tommasi, Stella

2014-09-01

169

Cross-correlation video recording of gas-vapor-droplet two-phase flows  

NASA Astrophysics Data System (ADS)

The experimental investigations of gas-vapor-droplet two-phase flow formation during single water droplets and their aggregate motion through high-temperature (more than 1000 K) combustion products have been conducted with usage of cross-correlation measuring facility and optical methods of "tracer" visualization ("Particle Image Velocimetry" and "Interferometric Particle Imaging"). Modes of droplet motion in high-temperature gases area have been established. It has been determined the influence of the main droplet (sizes, composition, temperature, dispersability, form, velocity) and gas (temperature and velocity) characteristics on parameters of forming gas-vapor-droplet mixtures. The main elements of advanced firefighting technologies with the usage of time and space apportioned polydisperse composition water droplet flows have been formulated. Physical and predictive mathematical models have been developed to determine the basic parameters of equipment which is necessary for operation with these technology usage.

Volkov, Roman S.; Vysokomornaya, Olga V.; Zhdanova, Alyona O.; Strizhak, Pavel A.

2015-01-01

170

Fabrication of MEMS devices by using anhydrous HF gas-phase etching with alcoholic vapor  

NASA Astrophysics Data System (ADS)

In silicon surface micromachining, anhydrous HF GPE process was verified as a very effective method for the dry release of microstructures. The developed gas-phase etching (GPE) process with anhydrous hydrogen fluoride (HF) gas and alcoholic vapor such as methanol, isopropyl alcohol (IPA) was characterized and its selective etching properties were discussed. The structural layers are P-doped multi-stacked polysilicon and silicon-on-insulator (SOI) substrates and sacrificial layers are tetraethylorthosilicate (TEOS), low-temperature oxide (LTO), plasma enhanced chemical vapor deposition (PECVD) oxide, phosphosilicate glass (PSG) and thermal oxides on silicon nitride or polysilicon substrates. We successfully fabricated and characterized micro electro mechanical system (MEMS) devices with no virtually process-induced stiction and no residues. The characteristics of the MEMS devices for microsensor and microactuator, microfluidic elements and optical MEMS application were evaluated by experiment.

Ick Jang, Won; Auck Choi, Chang; Lee, Myung Lae; Jun, Chi Hoon; Kim, Youn Tae

2002-05-01

171

Novel vapor phase reactions for the synthesis and modification of carbon nanotubes and inorganic nanowires.  

PubMed

Several vapor phase methods have been developed for the preparation and modification of carbon nanotubes and inorganic nanowires. Thus, nebulized spray pyrolysis has been employed for the synthesis of carbon nanotubes and metal nanowires. Multi-walled carbon nanotubes (MWNTs) with fairly uniform diameters and aligned nanotube bundles have been obtained by nebulized spray pyrolysis using solutions of organometallics such as ferrocene in hydrocarbon solvents. Single-crystalline nanowires of zinc, cadmium, cobalt, and lead are obtained by the decomposition of metal acetates. By reacting acid-treated carbon nanotubes with vapors of metal halides, followed by reaction with water and calcination chemically-bonded oxide layers can be obtained on the nanotubes. A similar procedure has been employed to prepare chemically-bonded oxide layers on Al2O3, ZnO, and silicon nanowires by the reaction of the metal halides with the surface hydroxyl groups present on these nanowire surfaces. PMID:17654926

Govindaraj, A; Vivekchand, S R C; Rao, C N R

2007-06-01

172

Nonphosphor White Light Emitting Diodes by Mixed-Source Hydride Vapor Phase Epitaxy  

NASA Astrophysics Data System (ADS)

In this paper, we approached a novel fabrication for non phosphor white light emitting diodes (LEDs) by the growth of AlGaN/InAlGaN double-hetero structures using by mixed-source hydride vapor phase epitaxy (HVPE) system with multi-sliding boat. It is unique crystal growth technology different from conventional HVPE and metal organic chemical vapor deposition (MOCVD) system using mixed metal source of aluminum, indium and gallium. The characterization of non phosphor white LEDs was examined by photoluminescence (PL) and electroluminescence (EL). The results of EL were found green and yellow emissions as spectrum peaks near 500, 550, and 610 nm definitely. The CIE chromaticity coordinates of white LEDs was measured at injection current 30 mA. Our results are nearly positions; at x = 0.28 and y = 0.31. Even though the LED needs more improved in optical properties, we demonstrated achieving phosphor-free solid-state white lighting.

Lee, Gang Seok; Jeon, Hunsoo; Jung, Se-Gyo; Bae, Seon Min; Shin, Min Jung; Kim, Kyoung Hwa; Yi, Sam Nyung; Yang, Min; Ahn, Hyung Soo; Yu, Young-Moon; Kim, Suck-Whan; Ha, Hong-Ju; Sawaki, Nobuhiko

2012-01-01

173

Properties of nuclear waste melts and glasses: Contact-refractory corrosion and vapor phase hydration  

NASA Astrophysics Data System (ADS)

Control of refractory corrosion in waste glass melts and meeting vapor phase hydration test (VHT) requirement for Hanford low-activity waste (LAW) glass product are two critical issues among many technical challenges of nuclear waste vitrification. In this study, refractory corrosion was treated as a complex non-equilibrium, multi-component and multi-phase reactive transport process and studied both thermodynamically and kinetically. Dissolution tests of granular refractory materials into under-saturated melts coupled with crystallization tests from supersaturated melts were used to determine the possible equilibrium points. The test results show that spinet phase is the most stable phase of K-3 refractory. Solubility of glass-refractory interface material controls the long term refractory corrosion rate and protects refractory from further corrosion. Therefore, refractory corrosion rate can be possibly adjusted by controlling the underlying solubility of the interface material. A set of monolithic refractory corrosion and dissolution tests was carried out to study the kinetic effects of refractory porosity and glass melt viscosity, the two major kinetic factors associated with reactive transport process. The test results show that temperature and glass melt viscosity have intensive effects on refractory material dissolution rate. Fast closure of channels near the glass-refractory interface during corrosion reaction by fast transformation of solid solution to spinel and spinel re-crystallization helps stop further corrosion reaction. Glass composition can be "passivated" by engineering the formulation to maximizing the beneficial alteration process. For the study of VHT kinetics, data from simulated LAW glasses studied previously at Pacific Northwest National Laboratory and Vitreous State Laboratory was modeled based on Avrami equation and its variant, the so-called generalized Avrami equation for better modeling of the VHT data. The results show that the kinetics of the complex vapor hydration process is described satisfactorily by the generalized Avrami equation. The generalized Avrami equation allows the characterization of vapor phase hydration data obtained at different times and temperatures quantitatively on a common basis. The three parameters associated with the generalized Avrami equation depend strongly on glass composition. It seems that both compositional mismatch and incompatibility of a host glass to the transformed hydrous crystalline phases slow down the vapor hydration rate.

Lu, Xiaodong

174

Electronic cigarettes: a review of safety and clinical issues.  

PubMed

This clinical case conference discusses 3 cases of patients using electronic cigarettes. Electronic cigarettes, also referred to as electronic nicotine delivery systems or "e-cigarettes," generally consist of a power source (usually a battery) and a heating element (commonly referred to as an atomizer) that vaporize a solution (e-liquid). The user inhales the resulting vapor. E-liquids contain humectants such as propylene glycol and/or vegetable glycerin, flavorings, and usually, but not always, nicotine. Each patient's information is an amalgamation of actual patients and is presented and then followed by a discussion of clinical issues. PMID:25089953

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

2014-01-01

175

Columnar jointing in vapor-phase-altered, non-welded Cerro Galán Ignimbrite, Paycuqui, Argentina  

USGS Publications Warehouse

Columnar jointing is thought to occur primarily in lavas and welded pyroclastic flow deposits. However, the non-welded Cerro Galán Ignimbrite at Paycuqui, Argentina, contains well-developed columnar joints that are instead due to high-temperature vapor-phase alteration of the deposit, where devitrification and vapor-phase crystallization have increased the density and cohesion of the upper half of the section. Thermal remanent magnetization analyses of entrained lithic clasts indicate high emplacement temperatures, above 630°C, but the lack of welding textures indicates temperatures below the glass transition temperature. In order to remain below the glass transition at 630°C, the minimum cooling rate prior to deposition was 3.0?×?10?3–8.5?×?10?2°C/min (depending on the experimental data used for comparison). Alternatively, if the deposit was emplaced above the glass transition temperature, conductive cooling alone was insufficient to prevent welding. Crack patterns (average, 4.5 sides to each polygon) and column diameters (average, 75 cm) are consistent with relatively rapid cooling, where advective heat loss due to vapor fluxing increases cooling over simple conductive heat transfer. The presence of regularly spaced, complex radiating joint patterns is consistent with fumarolic gas rise, where volatiles originated in the valley-confined drainage system below. Joint spacing is a proxy for cooling rates and is controlled by depositional thickness/valley width. We suggest that the formation of joints in high-temperature, non-welded deposits is aided by the presence of underlying external water, where vapor transfer causes crystallization in pore spaces, densifies the deposit, and helps prevent welding.

Wright, Heather M.; Lesti, Chiara; Cas, Ray A.F.; Porreca, Massimiliano; Viramonte, Jose G.; Folkes, Christopher B.; Giordano, Guido

2011-01-01

176

Dry phase of tropical lower stratospheric water vapor: Role of BDC, convection and ozone variability  

NASA Astrophysics Data System (ADS)

In the present paper, the relationship between dry phase of water vapor in the tropical lower stratosphere (TLS) and 100 hPa temperatures (T100) has been examined. Role of various processes, such as Brewer-Dobson circulation (BDC), convective activities and seasonal minimum of ozone mixing ratio, has been quantified to explain the reason of low T100 over Indonesian-Australian western Pacific region (IAWPR). Aura MLS data show that low water vapor mixing ratio (WVMR) first appears over the western Pacific during northern hemisphere (NH) winters and directs the dry phase of TLS. Observations of low T100 (~188 K), close association between WVMR and T100, slow transport of water vapor in TLS and saturation of air close to 82.5-100 hPa over IAWPR indicate conditions favorable for 'freeze drying'. Present analysis has brought out several interesting features (a) in addition to BDC, convective activities and low ozone mixing ratio near the tropopause level seems to be contributing to the low T100 over IAWPR during NH winter/spring, (b) apart from the seasonal decrease, T100 over IAWPR is noted to be continually low throughout the year by ~1.2 K than the zonal mean value where part of such decrease in T100 (i.e. ~0.7 K) can be understood in terms of water vapor feedback process and (c) wave activity of different temporal scale and amplitude (~1-2 K) also modulate T100 over IAWPR. MLS observations also provide an evidence of coupling between the surface and TLS processes, if the sea surface temperature over IAWPR is more than 301.7 K.

Jain, Shipra; Jain, A. R.; Mandal, T. K.

2014-12-01

177

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

SciTech Connect

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.

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

2001-07-03

178

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

NASA Astrophysics Data System (ADS)

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.

Chien, Wen-Ming

179

Vaporizing Vapor  

NSDL National Science Digital Library

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.

2012-08-03

180

New mechanism for autocatalytic decomposition of H2CO3 in the vapor phase.  

PubMed

In this article, we present high level ab initio calculations investigating the energetics of a new autocatalytic decomposition mechanism for carbonic acid (H2CO3) in the vapor phase. The calculation have been performed at the MP2 level of theory in conjunction with aug-cc-pVDZ, aug-cc-pVTZ, and 6-311++G(3df,3pd) basis sets as well as at the CCSD(T)/aug-cc-pVTZ level. The present study suggests that this new decomposition mechanism is effectively a near-barrierless process at room temperature and makes vapor phase of H2CO3 unstable even in the absence of water molecules. Our calculation at the MP2/aug-cc-pVTZ level predicts that the effective barrier, defined as the difference between the zero-point vibrational energy (ZPE) corrected energy of the transition state and the total energy of the isolated starting reactants in terms of bimolecular encounters, is nearly zero for the autocatalytic decomposition mechanism. The results at the CCSD(T)/aug-cc-pVTZ level of calculations suggest that the effective barrier, as defined above, is sensitive to some extent to the levels of calculations used, nevertheless, we find that the effective barrier height predicted at the CCSD(T)/aug-cc-pVTZ level is very small or in other words the autocatalytic decomposition mechanism presented in this work is a near-barrierless process as mentioned above. Thus, we suggest that this new autocatalytic decomposition mechanism has to be considered as the primary mechanism for the decomposition of carbonic acid, especially at its source, where the vapor phase concentration of H2CO3 molecules reaches its highest levels. PMID:24617952

Ghoshal, Sourav; Hazra, Montu K

2014-04-01

181

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

PubMed Central

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

Klapes, N A; Vesley, D

1990-01-01

182

Surfactant controlled growth of GaInP by organometallic vapor phase epitaxy  

SciTech Connect

The effect of the surfactant Sb has been studied for GaInP semiconductor alloys grown by organometallic vapor phase epitaxy. Dramatic changes in the optical and electrical properties of GaInP with CuPt ordering have been observed. A small concentration of triethylantimony (TESb) in the vapor is found to cause Sb to accumulate at the surface. In situ surface photoabsorption analysis indicates that Sb changes the surface bonding by replacing the [1(bar sign)10] P dimers that are responsible for the formation of the CuPt structure during growth with [1(bar sign)10] Sb dimers. As a result, the degree of order for the GaInP layers is decreased, as shown by transmission electron diffraction studies. The 20 K photoluminescence spectra show a 131 meV peak energy increase for GaInP layers grown on vicinal substrates when a small amount of Sb [Sb/P(v)=4x10{sup -4}] is added to the system during growth. The use of surfactants to control specific properties of materials is expected to be a powerful tool for producing complex structures. In this article, the growth of heterostructures by modulating the Sb concentration in the vapor is demonstrated. (c) 2000 American Institute of Physics.

Lee, R. T. [Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)] [Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Shurtleff, J. K. [Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)] [Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Fetzer, C. M. [Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)] [Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Stringfellow, G. B. [Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)] [Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Lee, S. [Department of Materials Science and Engineering, Kwangiu Institute of Science and Technology, Kwangju 506-712, Korea (Korea, Republic of)] [Department of Materials Science and Engineering, Kwangiu Institute of Science and Technology, Kwangju 506-712, Korea (Korea, Republic of); Seong, T. Y. [Department of Materials Science and Engineering, Kwangiu Institute of Science and Technology, Kwangju 506-712, Korea (Korea, Republic of)] [Department of Materials Science and Engineering, Kwangiu Institute of Science and Technology, Kwangju 506-712, Korea (Korea, Republic of)

2000-04-15

183

Hydride vapor phase epitaxy of AlN using a high temperature hot-wall reactor  

NASA Astrophysics Data System (ADS)

Aluminum nitride (AlN) was grown on c-plane sapphire substrates by hydride vapor phase epitaxy (HVPE). The experiments utilized a two zone inductively heated hot-wall reactor. The surface morphology, crystal quality, and growth rate were investigated as a function of growth temperature in the range of 1450-1575 °C. AlN templates grown to a thickness of 1 ?m were optimized with double axis X-ray diffraction (XRD) rocking curve full width half maximums (FWHMs) of 135? for the (002) and 513? for the (102).

Baker, Troy; Mayo, Ashley; Veisi, Zeinab; Lu, Peng; Schmitt, Jason

2014-10-01

184

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

NASA Astrophysics Data System (ADS)

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.

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

1999-02-01

185

Simulation and testing of a vertical organometallic vapor phase epitaxy reactor  

NASA Astrophysics Data System (ADS)

The purpose of the study is to design a single wafer vertical organo-metallic vapor phase epitaxy (OMVPE) reactor which gives a uniform deposition around the symmetry axis. The vertical reactor under the consideration consist of a diffuser and a system of coaxial cylinders to laminarize the flow which may lead to a uniform deposition without rotating the susceptor. The simulation shows that for a susceptor with a radius of 2.5 cm, a uniformity can be achieved in a region of a radius of 2 cm within 1% for certain operating condition. The result is compared with the experimental measurement of TiO2 deposition from TTIP.

Sani, R. A.; Barmawi, M.; Mindara, J. Y.

1998-02-01

186

Vapor-phase bioreactors: Avoiding problems through better design and operation  

SciTech Connect

Vapor-phase bioreactors are an efficient method to treat air contaminated with volatile organic compounds. To ensure stable long term performance, several design and operating factors must be considered. Common problems include nutrient limitations, biomass clogging, inactive biomass, low moisture content and reductions in pH. Based on several bioreactor studies, the underlying cause of each of these problems is identified, monitoring requirements are outlined and a range of appropriate response actions are presented. These solutions range from modification of bioreactor design and operation (e.g., step feed configuration and directionally switching operation) to the use of alternative types of microorganisms (e.g., fungi).

Kinney, K.A.; Loehr, R.C.; Corsi, R.L.

1999-09-30

187

Phase-Sensitive Amplification by Four-Wave Mixing in an Atomic Vapor  

NASA Astrophysics Data System (ADS)

A phase-sensitive amplifier (PSA) is based on a parametric process that can amplify or deamplify a signal depending on the phase of the input. It does so without degrading the signal to noise ratio of the input, contrary to a phase-insensitive amplifier (PIA) which adds at least 3dB of noise to the signal in the limit of high gain. This makes it possible to obtain noiseless amplification of a signal, making it a key element in optical communication systems. For the particular case where the input signal's phase is chosen for maximum deamplification the PSA can generate squeezed light. We present an experimental realization of a phase-sensitive optical amplifier using a four-wave mixing interaction based on a double-lambda configuration in hot Rb vapor. We report nearly noiseless amplification for a range of gains as well as the generation of ``single-beam'' squeezing. We compare the results obtained with a theorical phase-insensitive scheme. The lack of a cavity in our system and relaxed phase-matching conditions can be used to observe noiseless amplification of multi-spatial-mode signals (i.e. images).

Corzo, Neil; Marino, Alberto; Clark, Jeremy; Lance, Andrew; Jones, Kevin; Lett, Paul

2010-03-01

188

Disseminator for rapid, selectable, and quantitative delivery of low and semivolatile liquid species to the vapor phase  

NASA Astrophysics Data System (ADS)

Nelson and Griggs [Rev. Sci. Instrum. 39, 927 (1968)] introduced a quantitative method for disseminating liquid samples to the vapor phase using a lead screw to depress the plunger of a syringe whose body was heated and whose ambient tip was placed into the flow of a carrier gas. In order to measure quantitative vapor-phase infrared spectra, we have modified a commercial device to improve the accuracy and precision for quantitative vapor delivery. Design changes have focused on disseminating reactive or low volatility liquids by heating only the syringe tip and dispensed liquid. Performance features include quantitative vapor-phase generation with greater than three orders of magnitude concentration range, including low volatility species, with most equilibration times <40s. The method has been vetted by comparing the derived gas-phase infrared data versus IR spectra taken using both gravimetric (National Institute of Standards Technology) and passive vapor generation (Pacific Northwest National Laboratory) techniques. Quantitative vapor spectra of low volatility samples are reported.

Johnson, Timothy J.; Sharpe, Steven W.; Covert, Matthew A.

2006-09-01

189

E-Cigarettes  

MedlinePLUS

... nicotine — a highly addictive drug — into your body. Electronic cigarettes are battery-powered smoking devices often designed to ... an unhealthy dose of nicotine and other chemicals. Electronic cigarettes started out being marketed to smokers as a ...

190

The influence of temperature on the polymerization of ethyl cyanoacrylate from the vapor phase  

SciTech Connect

The polymerization of ethyl cyanoacrylate fumes from surface bound initiators is an important step in many novel and mature technologies. Understanding the effect of temperature on the rate of poly(ethyl cyanoacrylate) (PECA) growth and its molecular weight during its polymerization from the vapor phase from surface bound initiators provides insight into the important mechanistic aspects that impact the polymerizations success. In these studies, it is shown that the amount of PECA formed during the polymerization of ECA from a latent fingerprint increases with decreasing temperature, while the polymer molecular weight varies little. This is interpreted to be the result of the loosening of the ion pair that initiates the polymer chain growth and resides on the end of the growing polymer chain with decreasing temperature. Comparison of temperature effects and counter-ion studies show that in both cases loosening the ion pair results in the formation of more polymer with similar molecular weight, verifying this interpretation. These results further suggest that lowering the temperature may be an effective method to optimize anionic vapor phase polymerizations, including the improvement of the quality of aged latent prints and preliminary results are presented that substantiate this prediction.

Dadmun, Mark D [ORNL; Algaier, Dana [University of Tennessee, Knoxville (UTK); Baskaran, Durairaj [University of Tennessee, Knoxville (UTK)

2011-01-01

191

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

PubMed

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

Halasz, Istvan; Kierys, Agnieszka; Goworek, Jacek

2015-03-01

192

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

E-print Network

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.

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

2005-07-08

193

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

NASA Astrophysics Data System (ADS)

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.

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

194

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

USGS Publications Warehouse

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.

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

2009-01-01

195

Vapor phase polymerization of EDOT from submicrometer scale oxidant patterned by dip-pen nanolithography.  

PubMed

Some of the most exciting recent advances in conducting polymer synthesis have centered around the method of vapor phase polymerization (VPP) of thin films. However, it is not known whether the VPP process can proceed using significantly reduced volumes of oxidant and therefore be implemented as part of nanolithography approach. Here, we present a strategy for submicrometer scale patterning of the conducting polymer poly(3,4-ethylenedioxythiophene) (PEDOT) via in situ VPP. Attolitre (10(-18) L) volumes of oxidant "ink" are controllably deposited using dip-pen nanolithography (DPN). DPN patterning of the oxidant ink is facilitated by the incorporation of an amphiphilic block copolymer thickener, an additive that also assists with stabilization of the oxidant. When exposed to EDOT monomer in a VPP chamber, each deposited feature localizes the synthesis of conducting PEDOT structures of several micrometers down to 250 nm in width. PEDOT patterns are characterized by atomic force microscopy (AFM), conductive AFM, two probe electrical measurement, and micro-Raman spectroscopy, evidencing in situ vapor phase synthesis of conducting polymer at a scale (picogram) which is much smaller than that previously reported. Although the process of VPP on this scale was achieved, we highlight some of the challenges that need to be overcome to make this approach feasible in an applied setting. PMID:22651696

O'Connell, Cathal D; Higgins, Michael J; Nakashima, Hiroshi; Moulton, Simon E; Wallace, Gordon G

2012-07-01

196

Evaluation of solid-phase microextraction in detection of contraband drug vapors  

NASA Astrophysics Data System (ADS)

Solid phase microextraction (SPME) has emerged as a rapid alternative to conventional sample extraction techniques. SPME can be used in solids, liquids, and sample headspace. Compounds are sorbed by a stationary phase coated on a fused silica fiber. The compounds are desorbed, and analyzed using gas chromatography (GC), and high performance liquid chromatography (HPLC). As a part of the present work we have found that SPME can also be used conveniently with ion mobility spectrometry (IMS). Cocaine and heroin vapors sorbed on a SPME fiber were detected using IMS. The use of SPME-GC or SPME-HPLC has been reported in analysis of urine samples containing cocaine and its metabolites. We are evaluating SPME-IMS, and SPME-GC systems for the detection of cocaine and heroin and their decomposition products in the headspace above surfaces. This is part of our research on the surface decomposition of contraband drugs for detection applications. This paper will give a variety of examples in the use of SPME in the detection of contraband drugs and their reaction/decomposition products in the vapor state. An example is the detection of cocaine in the headspace above cocaine HCl at room temperature.

Orzechowska, Grazyna E.; Poziomek, Edward J.; Tersol, Vangielynn; Homstead, Juliana

1997-02-01

197

Feasibility Study of Vapor-Mist Phase Reaction Lubrication Using a Thioether Liquid  

NASA Technical Reports Server (NTRS)

A primary technology barrier preventing the operation of gas turbine engines and aircraft gearboxes at higher temperatures is the inability of currently used liquid lubricants to survive at the desired operating conditions over an extended time period. Current state-of-the-art organic liquid lubricants rapidly degrade at temperatures above 300 C; hence, another form of lubrication is necessary. Vapor or mist phase reaction lubrication is a unique, alternative technology for high temperature lubrication. The majority of past studies have employed a liquid phosphate ester that was vaporized or misted, and delivered to bearings or gears where the phosphate ester reacted with the metal surfaces generating a solid lubricious film. This method resulted in acceptable operating temperatures suggesting some good lubrication properties, but the continuous reaction between the phosphate ester and the iron surfaces led to wear rates unacceptable for gas turbine engine or aircraft gearbox applications. In this study, an alternative non-phosphate liquid was used to mist phase lubricate a spur gearbox rig operating at 10,000 rpm under highly loaded conditions. After 21 million shaft revolutions of operation the gears exhibited only minor wear.

Morales, Wilfredo; Handschuh, Robert F.; Krantz, Timothy L.

2007-01-01

198

Reaction mechanisms in the organometallic vapor phase epitaxial growth of GaAs  

NASA Technical Reports Server (NTRS)

The decomposition mechanisms of AsH3, trimethylgallium (TMGa), and mixtures of the two have been studied in an atmospheric-pressure flow system with the use of D2 to label the reaction products which are analyzed in a time-of-flight mass spectrometer. AsH3 decomposes entirely heterogeneously to give H2. TMGa decomposes by a series of gas-phase steps, involving methyl radicals and D atoms to produce CH3D, CH4, C2H6, and HD. TMGa decomposition is accelerated by the presence of AsH3. When the two are mixed, as in the organometallic vapor phase epitaxial growth of GaAs, both compounds decompose in concert to produce only CH4. A likely model is that of a Lewis acid-base adduct that forms and subsequently eliminates CH4.

Larsen, C. A.; Buchan, N. I.; Stringfellow, G. B.

1988-01-01

199

On the existence of vapor-liquid phase transition in dusty plasmas  

SciTech Connect

The phenomenon of phase transition in a dusty-plasma system (DPS) has attracted some attention in the past. Earlier Farouki and Hamaguchi [J. Chem. Phys. 101, 9876 (1994)] have demonstrated the existence of a liquid to solid transition in DPS where the dust particles interact through a Yukawa potential. However, the question of the existence of a vapor-liquid (VL) transition in such a system remains unanswered and relatively unexplored so far. We have investigated this problem by performing extensive molecular dynamics simulations which show that the VL transition does not have a critical curve in the pressure versus volume diagram for a large range of the Yukawa screening parameter ? and the Coulomb coupling parameter ?. Thus, the VL phase transition is found to be super-critical, meaning that this transition is continuous in the dusty plasma model given by Farouki and Hamaguchi. We provide an approximate analytic explanation of this finding by means of a simple model calculation.

Kundu, M.; Sen, A.; Ganesh, R. [Institute for Plasma Research, Bhat, Gandhinagar 382 428, Gujarat (India); Avinash, K. [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)

2014-10-15

200

Controlling interfacial film formation in mixed polymer-surfactant systems by changing the vapor phase.  

PubMed

Here we show that transport-generated phase separation at the air-liquid interface in systems containing self-assembling amphiphilic molecules and polymers can be controlled by the relative humidity (RH) of the air. We also show that our observations can be described quantitatively with a theoretical model describing interfacial phase separation in a water gradient that we published previously. These phenomena arises from the fact that the water chemical potential corresponding to the ambient RH will, in general, not match the water chemical potential in the open aqueous solution. This implies nonequilibrium conditions at the air-water interface, which in turn can have consequences on the molecular organization in this layer. The experimental setup is such that we can control the boundary conditions in RH and thereby verify the predictions from the theoretical model. The polymer-surfactant systems studied here are composed of polyethylenimine (PEI) and hexadecyltrimethylammonium bromide (CTAB) or didecyldimethylammonium bromide (DDAB). Grazing-incidence small-angle X-ray scattering results show that interfacial phases with hexagonal or lamellar structure form at the interface of dilute polymer-surfactant micellar solutions. From spectroscopic ellipsometry data we conclude that variations in RH can be used to control the growth of micrometer-thick interfacial films and that reducing RH leads to thicker films. For the CTAB-PEI system, we compare the phase behavior of the interfacial phase to the equilibrium bulk phase behavior. The interfacial film resembles the bulk phases formed at high surfactant to polymer ratio and reduced water contents, and this can be used to predict the composition of interfacial phase. We also show that convection in the vapor phase strongly reduces film formation, likely due to reduction of the unstirred layer, where diffusive transport is dominating. PMID:25084476

Mokhtari, Tahereh; Pham, Quoc Dat; Hirst, Christopher; O'Driscoll, Benjamin M D; Nylander, Tommy; Edler, Karen J; Sparr, Emma

2014-08-26

201

APTS and rGO co-functionalized pyrenated fluorescent nanonets for representative vapor phase nitroaromatic explosive detection  

NASA Astrophysics Data System (ADS)

For the first time, flexible PVP/pyrene/APTS/rGO fluorescent nanonets were designed and synthesized via a one-step electrospinning method to detect representative subsaturated nitroaromatic explosive vapor. The functional fluorescent nanonets, which were highly stable in air, showed an 81% quenching efficiency towards TNT vapor (~10 ppb) with an exposure time of 540 s at room temperature. The nice performance of the nanonets was ascribed to the synergistic effects induced by the specific adsorption properties of APTS, the fast charge transfer properties and the effective ?-? interaction with pyrene and TNT of rGO. Compared to the analogues of TNT, the PVP/pyrene/APTS/rGO nanonets showed notable selectivity towards TNT and DNT vapors. The explored functionalization method opens up brand new insight into sensitive and selective detection of vapor phase nitroaromatic explosives.For the first time, flexible PVP/pyrene/APTS/rGO fluorescent nanonets were designed and synthesized via a one-step electrospinning method to detect representative subsaturated nitroaromatic explosive vapor. The functional fluorescent nanonets, which were highly stable in air, showed an 81% quenching efficiency towards TNT vapor (~10 ppb) with an exposure time of 540 s at room temperature. The nice performance of the nanonets was ascribed to the synergistic effects induced by the specific adsorption properties of APTS, the fast charge transfer properties and the effective ?-? interaction with pyrene and TNT of rGO. Compared to the analogues of TNT, the PVP/pyrene/APTS/rGO nanonets showed notable selectivity towards TNT and DNT vapors. The explored functionalization method opens up brand new insight into sensitive and selective detection of vapor phase nitroaromatic explosives. Electronic supplementary information (ESI) available: Vapor pressure of TNT and its analogues, fluorescence quenching kinetics, fluorescence quenching efficiencies and additional SEM images. See DOI: 10.1039/c3nr04960d

Guo, Linjuan; Zu, Baiyi; Yang, Zheng; Cao, Hongyu; Zheng, Xuefang; Dou, Xincun

2014-01-01

202

Cigars, Cigarettes, and Adolescents  

ERIC Educational Resources Information Center

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…

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

2008-01-01

203

ALMA Temporal Phase Stability and the Effectiveness of Water Vapor Radiometer  

E-print Network

Atacama Large Millimeter/submillimeter Array (ALMA) will be the world largest mm/submm interferometer, and currently the Early Science is ongoing, together with the commissioning and science verification (CSV). Here we present a study of the temporal phase stability of the entire ALMA system from antennas to the correlator. We verified the temporal phase stability of ALMA using data, taken during the last two years of CSV activities. The data consist of integrations on strong point sources (i.e., bright quasars) at various frequency bands, and at various baseline lengths (up to 600 m). From the observations of strong quasars for a long time (from a few tens of minutes, up to an hour), we derived the 2-point Allan Standard Deviation after the atmospheric phase correction using the 183 GHz Water Vapor Radiometer (WVR) installed in each 12 m antenna, and confirmed that the phase stability of all the baselines reached the ALMA specification. Since we applied the WVR phase correction to all the data mentioned abov...

Matsushita, S; Barkats, D; Hills, R E; Fomalont, E; Nikolic, B

2012-01-01

204

Triple sorbent thermal desorption/gas chromatography/mass spectrometry determination of vapor phase organic contaminants  

SciTech Connect

A thermal desorption/ps chromatography/mass spectrometry (TD/GC/MS) has been evaluated for the determination of volatile organic compounds (VOCS) in vapor phase samples using Carbosieve S-III/Carbotrap/Carotrap C triple sorbent traps (TST) similar to those available from a commercial source. The analysis was carried out with a Hewlett-Packard 5985A or 5995 GC/MS system with a modified injector to adapt an inhouse manufactured short-path desorber for transferring desorbate directly onto a cryofocusing loop for subsequent GC/MS analysis. Vapor phase standards generated from twenty six compounds were used for method validation, including alkanes, alkyl alcohols, alkyl ketones, and alkyl nitrites, a group of representative compounds that have previously been identified in a target airborne matrix. The method was validated based on the satisfactory results in terms of reproducibility, recovery rate, stability, and linearity. A relative, standard deviation of 0.55 to 24.3 % was obtained for the entire TD process (generation of gas phase standards, spiking the standards on and desorbing from TST) over a concentration range of 20 to 500 ng/trap. Linear correlation coefficients for the calibration curves as determined ranged from 0.81 to 0.99 and limits of detection ranged from 3 to 76 ng. For a majority of standards, recoveries of greater than 90% were observed. For three selected standards spiked on TSTS, minimal loss (10 to 22%) was observed after storing the spiked in, a 4{degree}C refrigerator for 29 days. The only chromatographable artifact observed was a 5% conversion of isopropanol to acetone. The validated method been successfully applied, to the determination of VOCs collected from various emission sources in a diversified concentration range.

Ma, C.Y.; Skeen, J.T.; Dindal, A.B.; Higgins, C.E.; Jenkins, R.A.

1994-05-01

205

Tank vapor sampling and analysis data package for tank 241-C-106 waste retrieval sluicing system process test phase III  

SciTech Connect

This data package presents sampling data and analytical results from the March 28, 1999, vapor sampling of Hanford Site single-shell tank 241-C-106 during active sluicing. Samples were obtained from the 296-C-006 ventilation system stack and ambient air at several locations. Characterization Project Operations (CPO) was responsible for the collection of all SUMMATM canister samples. The Special Analytical Support (SAS) vapor team was responsible for the collection of all triple sorbent trap (TST), sorbent tube train (STT), polyurethane foam (PUF), and particulate filter samples collected at the 296-C-006 stack. The SAS vapor team used the non-electrical vapor sampling (NEVS) system to collect samples of the air, gases, and vapors from the 296-C-006 stack. The SAS vapor team collected and analyzed these samples for Lockheed Martin Hanford Corporation (LMHC) and Tank Waste Remediation System (TWRS) in accordance with the sampling and analytical requirements specified in the Waste Retrieval Sluicing System Vapor Sampling and Analysis Plan (SAP) for Evaluation of Organic Emissions, Process Test Phase III, HNF-4212, Rev. 0-A, (LMHC, 1999). All samples were stored in a secured Radioactive Materials Area (RMA) until the samples were radiologically released and received by SAS for analysis. The Waste Sampling and Characterization Facility (WSCF) performed the radiological analyses. The samples were received on April 5, 1999.

LOCKREM, L.L.

1999-08-13

206

Evaluating the robustness of the enantioselective stationary phases on the Rosetta mission against space vacuum vaporization  

NASA Astrophysics Data System (ADS)

The European Space Agency's Rosetta mission was launched in March 2004 in order to reach comet 67P/Churyumov-Gerasimenko by August 2014. The Cometary Sampling and Composition experiment (COSAC) onboard the Rosetta mission's lander "Philae" has been designed for the cometary in situ detection and quantification of organic molecules using gas chromatography coupled to mass spectrometry (GC-MS). The GC unit of COSAC is equipped with eight capillary columns that will each provide a specific stationary phase for molecular separation. Three of these stationary phases will be used to chromatographically resolve enantiomers, as they are composed of liquid polymers of polydimethylsiloxane (PDMS) to which chiral valine or cyclodextrin units are attached. Throughout the ten years of Rosetta's journey through space to reach comet 67P, these liquid stationary phases have been exposed to space vacuum, as the capillary columns within the COSAC unit were not sealed or filled with carrier gas. Long term exposures to space vacuum can cause damage to such liquid stationary phases as key monomers, volatiles, and chiral selectors can be vaporized and lost in transit. We have therefore exposed identical spare units of COSAC's chiral stationary phases over eight years to vacuum conditions mimicking those experienced in space and we have now investigated their resolution capabilities towards different enantiomers both before and after exposure to space vacuum environments. We have observed that enantiomeric resolution capabilities of these chiral liquid enantioselective stationary phases has not been affected by exposure to space vacuum conditions. Thus we conclude that the three chiral stationary phases of the COSAC experiment onboard the Rosetta mission lander "Philae" can be considered to have maintained their resolution capacities throughout their journey prior to cometary landing in November 2014.

Meierhenrich, Uwe J.; Cason, Julie R. L.; Szopa, Cyril; Sternberg, Robert; Raulin, François; Thiemann, Wolfram H.-P.; Goesmann, Fred

2013-12-01

207

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

SciTech Connect

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.

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

2014-02-05

208

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

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

209

Vapor-phase biofilters make bid for VOC control in industrial applications  

SciTech Connect

Biofiltration of contaminated air streams containing volatile organic compounds (VOCs) is a relatively new application of biotechnology in the waste management industry. The primary stimulus for development of vapor-phase biofiltration in Europe is its capability for efficient and reliable VOC destruction without forming hazardous by-products, coupled with low operating and life-cycle costs compared to conventional physical-chemical alternatives. The filters operate by passing the contaminated air stream through a bed of compost, peat, soil or other permeate material, which acts as an attachment site for rich microbial fauna. After the VOCs have been sorbed from the air stream while passing through the bed, the microorganisms use the sorbed organics as a food source, converting the pollutant into carbon dioxide and water vapor. As the organic pollutant is metabolized, the binding site to which it was attached again becomes available to strip additional VOC molecules from the incoming air stream. Thus, the biofilters reach a steady state, and sorption and biological destruction is followed by re-sorption of fresh volatile pollutants. Under proper conditions, this sequence of reactions occurs quite rapidly.

Stewart, W.C.; Thom, R.R. [Bio-Reaction Industries Inc., Tualatin, OR (United States)

1996-09-01

210

Effect of Phase Purity on Dislocation Density of Pressurized-Reactor Metalorganic Vapor Phase Epitaxy Grown InN  

NASA Astrophysics Data System (ADS)

The effect of the metastable zincblende (ZB) InN inclusion in the stable wurtzite (WZ) InN on the threading dislocation densities (TDDs) of an InN film grown by pressurized-reactor metalorganic vapor phase epitaxy has been studied by X-ray diffraction measurements. InN films are directly grown on c-plane sapphire substrates with nitrided surfaces at 1600 Torr with the different growth temperature from 500 to 700 °C. Films including ZB-InN show the correlation between the ZB volume fraction and the edge component of TDDs, not the screw component of TDDs. This result can be crystallographically understood by a simple model explaining how the ZB structure is included, i.e., ZB domains existing side-by-side with WZ domains and twined ZB domains. This can be clearly observed by electron backscatter diffraction.

Iwabuchi, Takuya; Liu, Yuhuai; Kimura, Takeshi; Zhang, Yuantao; Prasertsuk, Kiattiwut; Watanabe, Haruna; Usami, Noritaka; Katayama, Ryuji; Matsuoka, Takashi

2012-04-01

211

Effects of ventilated cigarette holders on cigarette smoking by humans  

Microsoft Academic Search

Heavy cigarette smokers individually attended daily 3-h test sessions which were run in specially designed cigarette smoking evaluation rooms. Subjects were required to use the cigarette holder provided, and were required to extinguish each cigarette 4 min after the first puff on the cigarette. Other than these restrictions, subjects were allowed to smoke ad libitum. The concentration of delivered tobacco

Jack E. Henningfield; Roland R. Griffiths

1980-01-01

212

Long-lived chemiluminescence in cigarette smoke  

Microsoft Academic Search

Cigarette smoke contains high concentrations of unstable molecules that react with oxygen to produce chemiluminescence. The chemiluminescent activity concentrated in the aerosol phase that can be absorbed on glass-fiber filters and extracted into organic solvents. Cigarette smoke in N,N-dimethylformamide produces a long-lasting luminescence visible to the dark-adapted eye. We have demonstrated the oxygen dependence and have measured the kinetics, activation

H. H. Seliger; W. H. Biggley; J. P. Hamman

1974-01-01

213

Transmission electron microscope characterization of AlGaInP grown by organometallic vapor phase epitaxy  

SciTech Connect

AlGaInP epitaxial layers grown at 690 {degree}C by atmospheric pressure organometallic vapor phase epitaxy are investigated by transmission electron microscopy. For the first time, compositionally modulated and ordered structures are simultaneously observed in AlGaInP alloys. The ordering is of the CuPt type with ordering along the {l brace}111{r brace} directions. The ordered regions appear as plate-like microdomains, while the composition modulation takes the form of a fine columnar constrast oriented along the growth direction. In addition, from the results of (001) plan-view diffraction contrast examination, the principal strain direction associated with the modulation structures is found to be perpendicular to the growth direction and lies in the surface plane. Thus, it is concluded that the spinodal decomposition is initiated and developed on the surface during the growth of the AlGaInP epitaxial layers and, finally, forms the columnar structure.

Chen, G.S.; Wang, T.Y.; Stringfellow, G.B. (Department of Materials Science, University of Utah, Salt Lake City, Utah 84112 (USA) Engineering and Electrical Engineering, University of Utah, Salt Lake City, Utah 84112 (USA))

1990-04-09

214

Vapor phase ketonization of acetic acid on ceria based metal oxides  

SciTech Connect

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.

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

2013-12-01

215

Organometallic vapor phase epitaxy growth of upright metamorphic multijunction solar cells  

Microsoft Academic Search

We demonstrate an integrated metamorphic AlGaInP\\/AlGaInAs\\/GaInAs\\/Ge 4J solar cell on Ge substrate using organometallic vapor phase epitaxy (OMVPE). A step graded GaInAs buffer was grown right after the Ge subcell was formed to change the lattice constant from that of Ge to that of Ga0.8In0.2As lattice constant followed by a 1.14eV Ga0.8In0.2As subcell, a 1.5eV (AlGa)0.8In0.2As subcell, and a 1.85eV

X. Q. Liu; C. M. Fetzer; E. Rehder; H. Cotal; S. Mesropian; D. Law; R. R. King

216

Accumulation of Background Impurities in Hydride Vapor Phase Epitaxy Grown GaN Layers  

NASA Astrophysics Data System (ADS)

We report on accumulation of background Si and O impurities measured by secondary ion mass spectrometry (SIMS) at the sub-interfaces in undoped, Zn- and Mg-doped multi-layer GaN structures grown by hydride vapor phase epitaxy (HVPE) on sapphire substrates with growth interruptions. The impurities accumulation is attributed to reaction of ammonia with the rector quartz ware during the growth interruptions. Because of this effect, HVPE-grown GaN layers had excessive Si and O concentration on the surface that may hamper forming of ohmic contacts especially in the case of p-type layers and may complicate homo-epitaxial growth of a device structure.

Usikov, Alexander; Soukhoveev, Vitali; Kovalenkov, Oleg; Syrkin, Alexander; Shapovalov, Liza; Volkova, Anna; Ivantsov, Vladimir

2013-08-01

217

Polarity control of GaN thin films grown by metalorganic vapor phase epitaxy  

NASA Astrophysics Data System (ADS)

Control of the polarity of GaN thin films grown on c-plane sapphire by low-pressure metalorganic vapor phase epitaxy has been achieved. Growth of either polarity was realized by identifying and selecting appropriate substrate pre-treatments and AlN LT-buffer growth conditions. N-face (-c) GaN films were only obtained by pre-nitridation of the sapphire substrate after a H2 anneal. Smooth films of each type of polarity were obtained by using N2 as a transport and dilution gas and a V/III ratio of less than 500. The same growth rate of 1.2 ?m/h was observed for both types of polarities under the same growth conditions. Further analysis of the growth conditions demonstrated that by using N2 as the dilution gas the transport was mass-transfer limited.

Collazo, R.; Mita, S.; Schlesser, R.; Sitar, Z.

2005-05-01

218

The 2nd phase of the LEANDRE program: Water-vapor DIAL measurement  

NASA Technical Reports Server (NTRS)

As a follow-on of the backscattered lidar, a differential absorption lidar (LEANDRE 2) is now being developed as part of the LEANDRE program for airborne meteorological studies. The primary measurement objective of LEANDRE 2 is water vapor. Pressure and temperature measurements are aimed at a second stage. The goals are to obtain a horizontal resolution of a few hundred meters for a vertical resolution of less than a hundred meters, with an absolute accuracy of 10 percent for humidity measurement. As compatibility is an important feature between the 2 first phases of LEANDRE, most of the LEANDRE 1 sub-system will be used and adapted for LEANDRE 2. For example, detection electronics, central computer, detectors and telescope will be the same. However, important modifications have to be done on the laser source, and spectral control has to be added. Most of the work is thus devoted to those developments, and the status is presented here.

Quaglia, P.; Bruneau, D.; Pelon, J.

1992-01-01

219

Growth and characterization of low defect GaN by hydride vapor phase epitaxy  

NASA Astrophysics Data System (ADS)

Low defect density GaN boules were produced using hydride vapor phase epitaxy. A high growth rate of over 100 ?m/h enabled the growth of GaN boules longer than 3 mm in length. GaN wafers generated from the boules were characterized by X-ray diffraction, synchrotron white beam X-ray transmission topography, and microscopy of etched surfaces. It was found that the dislocation density decreased with the thickness of the grown material. GaN samples with dislocation density less than 10 4 cm -2 were produced. The high crystal quality of the GaN samples was further demonstrated with a full-width at half-maximum of 38 arcsec for the GaN(0 0 0 4) double crystal X-ray rocking curve.

Xu, Xueping; Vaudo, R. P.; Loria, C.; Salant, A.; Brandes, G. R.; Chaudhuri, J.

2002-12-01

220

Heterojunction Hybrid Devices from Vapor Phase Grown MoS2  

PubMed Central

We investigate a vertically-stacked hybrid photodiode consisting of a thin n-type molybdenum disulfide (MoS2) layer transferred onto p-type silicon. The fabrication is scalable as the MoS2 is grown by a controlled and tunable vapor phase sulfurization process. The obtained large-scale p-n heterojunction diodes exhibit notable photoconductivity which can be tuned by modifying the thickness of the MoS2 layer. The diodes have a broad spectral response due to direct and indirect band transitions of the nanoscale MoS2. Further, we observe a blue-shift of the spectral response into the visible range. The results are a significant step towards scalable fabrication of vertical devices from two-dimensional materials and constitute a new paradigm for materials engineering. PMID:24975741

Yim, Chanyoung; O'Brien, Maria; McEvoy, Niall; Riazimehr, Sarah; Schäfer-Eberwein, Heiko; Bablich, Andreas; Pawar, Ravinder; Iannaccone, Giuseppe; Downing, Clive; Fiori, Gianluca; Lemme, Max C.; Duesberg, Georg S.

2014-01-01

221

Homoepitaxial growth of ?-Ga2O3 layers by halide vapor phase epitaxy  

NASA Astrophysics Data System (ADS)

Thick high-purity ?-Ga2O3 layers of high crystalline quality were grown homoepitaxially by halide vapor phase epitaxy (HVPE) using gaseous GaCl and O2 on (001) ?-Ga2O3 substrates prepared by edge-defined film-fed growth. The surface morphology and structural quality of the grown layer improved with increasing growth temperature. X-ray diffraction ?-rocking curves for the (002) and (400) reflections for the layer grown at 1000 °C had small full widths at half maximum. Secondary ion mass spectrometry and electrical characteristics revealed that the growth of high-purity ?-Ga2O3 layers with low effective donor concentration (Nd ? Na < 1013 cm?3) is possible by HVPE.

Murakami, Hisashi; Nomura, Kazushiro; Goto, Ken; Sasaki, Kohei; Kawara, Katsuaki; Thieu, Quang Tu; Togashi, Rie; Kumagai, Yoshinao; Higashiwaki, Masataka; Kuramata, Akito; Yamakoshi, Shigenobu; Monemar, Bo; Koukitu, Akinori

2015-01-01

222

Chloride vapor-phase epitaxy of gallium nitride on silicon: Effect of a silicon carbide interlayer  

NASA Astrophysics Data System (ADS)

A new approach is described, according to which the use of a thin silicon carbide (SiC) interlayer ensures the suppression of cracking and the simultaneous release of elastic strain in gallium nitride (GaN) epilayers grown by hydride-chloride vapor-phase epitaxy (HVPE) on 1.5-inch Si(111) substrates. Using this method, 20-?m-thick GaN epilayers have been grown by HVPE on Si substrates with AlN (300 nm) and SiC (100 nm) interlayers. A high quality of the obtained GaN epilayers is confirmed by the photoluminescence spectra, where an exciton band with hvmax = 3.45 eV and a half-width (FWHM) of 68 meV is observed at 77 K, as well as by the X-ray rocking curves exhibiting GaN(0002) reflections with a half-width of ?? = 600 arc sec.

Aksyanov, I. G.; Bessolov, V. N.; Zhilyaev, Yu. V.; Kompan, M. E.; Konenkova, E. V.; Kukushkin, S. A.; Osipov, A. V.; Rodin, S. N.; Feoktistov, N. A.; Sharofidinov, Sh.; Shcheglov, M. P.

2008-06-01

223

Detection of condensed-phase explosives via laser-induced vaporization, photodissociation, and resonant excitation.  

PubMed

We investigate the remote detection of explosives via a technique that vaporizes and photodissociates the condensed-phase material and detects the resulting vibrationally excited NO fragments via laser-induced fluorescence. The technique utilizes a single 7 ns pulse of a tunable laser near 236.2 nm to perform these multiple processes. The resulting blue-shifted fluorescence (226 nm) is detected using a photomultiplier and narrowband filter that strongly block the scatter of the pump laser off the solid media while passing the shorter wavelength photons. Various nitro-bearing compounds, including 2,6-dinitrotoluene (DNT), 2,4,6-trinitrotoluene (TNT), pentaerythritol tetranitrate (PETN), and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) were detected with a signal-to-noise of 25 dB. The effects of laser fluence, wavelength, and sample morphology were examined. PMID:19122718

Wynn, C M; Palmacci, S; Kunz, R R; Clow, K; Rothschild, M

2008-11-01

224

Liquid-vapor phase diagram and cluster formation of two-dimensional ionic fluids  

NASA Astrophysics Data System (ADS)

Direct molecular dynamics simulations on interfaces at constant temperature are performed to obtain the liquid-vapor phase diagram of the two-dimensional soft primitive model, an equimolar mixture of equal size spheres carrying opposite charges. Constant temperature and pressure simulations are also carried out to check consistency with interface simulations results. In addition, an analysis of the cluster formation of mixtures of particles with charge asymmetry in the range 1:1 to 1:36 at low and high densities is performed. The number of free ions, when plotted as a function of the positive ion charge, Z+, has an oscillatory behavior and is independent of the density. The formation of aggregates is analyzed in terms of the attraction and repulsion between ions.

Méndez-Maldonado, Gloria Arlette; González-Melchor, Minerva; Alejandre, José

2012-08-01

225

Science and electronic cigarettes: current data, future needs.  

PubMed

Electronic cigarettes (ECIGs), also referred to as electronic nicotine delivery systems 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. Electronic cigarettes 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 describes 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 also describes arguments for and against ECIGs and concludes with steps to move research on ECIGs forward. PMID:25089952

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

2014-01-01

226

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

SciTech Connect

This report summarizes work of this project from October 2003 through March 2004. The major focus of the research was to further investigate BTEX removal from produced water, to quantify metal ion removal from produced water, and to evaluate a lab-scale vapor phase bioreactor (VPB) for BTEX destruction in off-gases produced during SMZ regeneration. Batch equilibrium sorption studies were conducted to evaluate the effect of semi-volatile organic compounds commonly found in produced water on the sorption of benzene, toluene, ethylbenzene, and xylene (BTEX) onto surfactant-modified zeolite (SMZ) and to examine selected metal ion sorption onto SMZ. The sorption of polar semi-volatile organic compounds and metals commonly found in produced water onto SMZ was also investigated. Batch experiments were performed in a synthetic saline solution that mimicked water from a produced water collection facility in Wyoming. Results indicated that increasing concentrations of semi-volatile organic compounds increased BTEX sorption. The sorption of phenol compounds could be described by linear isotherms, but the linear partitioning coefficients decreased with increasing pH, especially above the pKa's of the compounds. Linear correlations relating partitioning coefficients of phenol compounds with their respective solubilities and octanol-water partitioning coefficients were developed for data collected at pH 7.2. The sorption of chromate, selenate, and barium in synthetic produced water were also described by Langmuir isotherms. Experiments conducted with a lab-scale vapor phase bioreactor (VPB) packed with foam indicated that this system could achieve high BTEX removal efficiencies once the nutrient delivery system was optimized. The xylene isomers and benzene were found to require the greatest biofilter bed depth for removal. This result suggested that these VOCs would ultimately control the size of the biofilter required for the produced water application. The biofilter recovered rapidly from shutdowns showing that the system was resilient to discontinuous feed conditions therefore provided flexibility on the SMZ regeneration process.

Lynn E. Katz; Kerry A. Kinney; R. S. Bowman; E. J. Sullivan

2004-03-11

227

Vapor phase toxicity of marjoram oil compounds and their related monoterpenoids to Blattella germanica (Orthoptera: Blattellidae).  

PubMed

The toxicity of marjoram, Origanum majorana L., oil, 41 monoterpenoids, and 2 sesquiterpenoids against adult females of the German cockroach, Blattella germanica L., was examined using direct contact and vapor phase toxicity bioassays and compared with those of deltamethrin, dichlorvos, permethrin, and propoxur, four commonly used insecticides. In a filter-paper contact toxicity bioassay, the adulticidal activities of pulegone (0.06 mg/cm2), (+/-)-camphor (0.07 mg/cm2), and verbenone (0.07 mg/cm2) were comparable to that of permethrin (0.05 mg/cm2) but more pronounced than that of propoxur (0.18 mg/cm2), as judged by the 24-h LC50 values. These compounds were less effective than either deltamethrin (0.013 mg/cm2) or dichlorvos (0.007 mg/cm2). The toxicity of marjoram oil, thymol, alpha-terpineol, (-)-alpha-thujone, linalool, 1,8-cineole, (-)-camphor, and (+)-carvone, ranging from 0.08 to 0.18 mg/cm2, was higher than that of propoxur. In vapor phase toxicity tests, verbenone (11.48 mg/L air) was the most toxic compound followed by (-)-alpha-thujone (18.43 mg/L of air), thymol (18.76 mg/L of air), alpha-terpineol (21.89 mg/L of air), (+/-)-camphor (24.59 mg/L of air), linalool (26.20 mg/L of air), and marjoram oil (38.28 mg/L of air) on the basis of the 24-h LC50 values. Dichlorvos (0.07 mg/L of air) was the most potent fumigant. Structure-activity relationships indicate that structural characteristics, such as degrees of saturation and types of functional groups rather than types of carbon skeleton, and hydrophobicity and vapor pressure parameters appear to play a role in determining the monoterpenoid toxicities to adult B. germanica. Marjoram oil and the monoterpenoids described merit further study as potential fumigants or leads for the control of B. germanica. PMID:16190647

Jang, Young-Su; Yang, Young-Cheol; Choi, Dal-Soon; Ahn, Young-Joon

2005-10-01

228

A NEW VAPOR RECOVERY NOZZLE FOR AIR POLLUTION CONTROL - PHASE II  

EPA Science Inventory

The vapor recovery nozzle is an air pollution control device which relates to Stage II emission control equipment designed to capture gasoline vapors during automobile refueling at service stations. The existing vapor recovery nozzles are difficult to handle, the bellows pr...

229

Perceived efficacy of e-cigarettes versus nicotine replacement therapy among successful e-cigarette users: a qualitative approach  

PubMed Central

Background Nicotine is widely recognized as an addictive psychoactive drug. Since most smokers are bio-behaviorally addicted, quitting can be very difficult and is often accompanied by withdrawal symptoms. Research indicates that nicotine replacement therapy (NRT) can double quit rates. However, the success rate for quitting remains low. E-cigarettes (electronic cigarettes) are battery-powered nicotine delivery devices used to inhale doses of vaporized nicotine from a handheld device similar in shape to a cigarette without the harmful chemicals present in tobacco products. Anecdotal evidence strongly suggests that e-cigarettes may be effective in helping smokers quit and preventing relapse, but there have been few published qualitative studies, especially among successful e-cigarette users, to support this evidence. Methods Qualitative design using focus groups (N?=?11); 9 men and 2 women. Focus groups were conducted by posing open-ended questions relating to the use of e-cigarettes, comparison of effectiveness between NRTs and e-cigarettes, barriers to quitting, and reasons for choosing e-cigarettes over other methods. Results Five themes emerged that describe users’ perceptions of why e-cigarettes are efficacious in quitting smoking: 1) bio-behavioral feedback, 2) social benefits, 3) hobby elements, 4) personal identity, and 5) distinction between smoking cessation and nicotine cessation. Additionally, subjects reported their experiences with NRTs compared with e-cigarettes, citing negative side effects of NRTs and their ineffectiveness at preventing relapse. Conclusion These findings suggest tobacco control practitioners must pay increased attention to the importance of the behavioral and social components of smoking addiction. By addressing these components in addition to nicotine dependence, e-cigarettes appear to help some tobacco smokers transition to a less harmful replacement tool, thereby maintaining cigarette abstinence. PMID:23497603

2013-01-01

230

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

DOEpatents

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.

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

2001-01-01

231

GaAs tunnel junction grown by metalorganic vapor-phase epitaxy for multigap cascade solar cells  

NASA Astrophysics Data System (ADS)

GaAs tunnel p-n junctions with peak current densities up to 45 A cm-2 were grown by metallorganic vapor-phase epitaxy. These tunnel diodes are suitable for intercell ohmic contacts between the case of integrated tandem photovoltaic subcells in solar cells based on GaAs. The peak current is high enough for concentration up to C=1000.

Basmaji, P.; Guittard, M.; Rudra, A.; Carlin, J. F.; Gibart, P.

1987-09-01

232

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...

233

Potential phase control of chromium oxide thin films prepared by laser-initiated organometallic chemical vapor deposition  

E-print Network

Potential phase control of chromium oxide thin films prepared by laser-initiated organometallic used laser-initiated chemical vapor deposition to grow the chromium oxide thin films through chromium oxide CrO2 with Tc 397 K Ref. 5 has been predicted to be half metallic metallic for one spin

Idzerda, Yves

234

Effect of surfactant Sb on In incorporation and thin film morphology of InGaN layers grown by organometallic vapor phase epitaxy  

E-print Network

Effect of surfactant Sb on In incorporation and thin film morphology of InGaN layers grown. Biefeld Available online 11 April 2013 Keywords: A3. Organometallic vapor phase epitaxy A3. Surfactant of the surfactant Sb on InGaN grown by organometallic vapor phase epitaxy (OMVPE) were studied. Eight samples of In

Simons, Jack

235

Ferromagnetism in (In,Mn)As diluted magnetic semiconductor thin films grown by metalorganic vapor phase epitaxy  

Microsoft Academic Search

In1-xMnxAs diluted magnetic semiconductor (DMS) thin films have been grown using metalorganic vapor phase epitaxy (MOVPE). Tricarbonyl(methylcyclopentadienyl)manganese was used as the Mn source. Nominally single-phase, epitaxial films were achieved with Mn content as high as x=0.14 using growth temperatures Tg>475 C. For lower growth temperatures and higher Mn concentrations, nanometer scale MnAs precipitates were detected within the In1-xMnxAs matrix. Magnetic

A. J. Blattner

2002-01-01

236

The role of gas-phase reactions in modeling of the forced-flow chemical vapor infiltration process  

Microsoft Academic Search

An analytical model is presented, which includes the effects of both gas-phase and surface reactions, and the pressure changes due to the chemical reactions in the forced-flow chemical vapor infiltration (FCVI) process. For the FCVI process controlled by the gas-phase reactions, improvements of the process by using the forced-flow are limited. However, for the FCVI process controlled by the surface

Ching Yi Tsai; J. N. Reddy; Seshu B. Desu; Chien C. Chiu

1993-01-01

237

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

Microsoft Academic Search

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

P. C. Okafor; S. Nesic

2007-01-01

238

Vapor-phase catalytic oxidesulfurization (ODS) of organosulfur compounds over supported metal oxide catalysts  

NASA Astrophysics Data System (ADS)

Sulfur in transportation fuels remains a leading source of SOx emissions from vehicle engines and is a major source of air pollution. The very low levels of sulfur globally mandated for transportation fuels in the near future cannot be achieved by current practices of hydrodesulfurization (HDS) for sulfur removal, which operate under severe conditions (high T, P) and use valuable H2. Novel vapor-phase catalytic oxidesulfurization (ODS) processes of selectively oxidizing various organosulfur compounds (carbonyl sulfide, carbon disulfide, methanethiol, dimethyl sulfide (DMS), dimethyl disulfide (DMDS), thiophene, 2,5-dimenthylthiophene) typically found in various industrial streams (e.g., petroleum refining, pulp and paper) into valuable chemical intermediates (H 2CO, CO, H2, maleic anhydride and concentrated SO2) has been extensively studied. This research has primarily focused on establishing the fundamental kinetics and mechanisms of these selective oxidation reactions over well-defined supported metal oxide catalysts. The selective oxidation reactions of COS + O2 ? CO + SO2; 2CS2 + 5O2 ? 2CO + 4SO2; CH3SH + 2O 2 ? H2CO + SO2 + H2O; C4 H4S + 3O2 ? C4H2O 3 + H2O + SO2; were studied. Raman spectroscopy revealed that the supported metal oxide phases were 100% dispersed on the oxide substrate. All the catalysts were highly active and selective for the oxidesulfurization of carbonyl sulfide, carbon disulfide, methanethiol, and thiophene between 290--330°C, 230--270°C, 350--400°C, and 250--400°C, respectively and did not deactivate. The TOFs (turnover frequency, normalized activity per active catalytic site) for all ODS reactions over supported vanadia catalysts, only containing molecularly dispersed surface vanadia species, varied within one order of magnitude and revealed the V-O-Support bridging bond was involved in the critical rate-determining kinetic steps. The surface reaction mechanism for each reaction was revealed by in situ IR (infrared) and temperature programmed surface reaction-mass spectroscopy (TPSR-MS). The systematic investigation of vapor-phase oxidesulfurization (ODS) reactions of organosulfur compounds over catalytic supported metal oxides revealed the facile S-O exchange mechanisms allow for the efficient removal of sulfur while producing value-added chemicals and represents the discovery of a new series of catalytic reactions.

Choi, Sukwon

239

Vapor-phase transport deposition, characterization, and applications of large nanographenes.  

PubMed

Recently, chemical synthesis of a range of large nanographene molecules with various shapes and sizes opened a new path to utilize them in various applications and devices. However, due to their extended aromatic cores and high molecular weight, film formation of large nanographene molecules, bearing more than 90 sp(2) carbon atoms in aromatic cores, is very challenging, which has prevented their applications such as in thin-film transistors. Here, we developed an effective approach to prepare films of such large nanographene molecules using a vapor-phase transport (VPT) technique based on molecule sublimation. The VPT of these molecules was made possible by combining the molecules and the target substrate in a small confinement of vacuum-sealed glass tube, so that a small amount of sublimation can be utilized to create films. Surprisingly, such heavy and large molecules can be deposited on any substrate by this method to create films of assembled large nanographene molecules while maintaining their aromatic cores intact, which was confirmed using mass spectrometry measurements. Moreover, field-effect transistors based on these films are depleted and show significantly improved current on/off ratio compared to previous large nanographene-based transistors fabricated using liquid-phase-based process. Our work shows that VPT deposition can be a viable technique to prepare films based on large nanographene molecules and potentially other high molecular weight compounds, which may find exciting applications in electronics and optoelectronics. PMID:25823532

Abbas, Ahmad N; Liu, Bilu; Narita, Akimitsu; Dössel, Lukas F; Yang, Bo; Zhang, Wen; Tang, Jianshi; Wang, Kang L; Räder, Hans Joachim; Feng, Xinliang; Müllen, Klaus; Zhou, Chongwu

2015-04-01

240

"Light" Cigarettes and Cancer Risk  

MedlinePLUS

... with a smoking machine, the smoke from a so-called light cigarette has a lower yield of tar ... is to stop smoking completely. What is a so-called light cigarette? Tobacco manufacturers have been redesigning cigarettes ...

241

Organic-inorganic field effect transistor with SnI-based perovskite channel layer using vapor phase deposition technique  

Microsoft Academic Search

High field-effect hole mobility of 0.28 cm2 \\/V·s (on\\/off ratio is more than 105, and threshold voltage is 3.2 V) in organic-inorganic layered perovskite film (C6H5C2H4NH3)2SnI4 prepared by a vapor phase deposition technique have been demonstrated through the octadecyltrichlorosilane treatment of substrate. Previously, the (C6H5C2H4NH3)2PbI4 films prepared on the octadecyltrichlorosilane-covered substrates using a vapor evaporation showed not only intense exciton

Toshinori Matsushima; Takeshi Yasuda; Katsuhiko Fujita; Tetsuo Tsutsui

2003-01-01

242

Molecular dynamics study of kinetic boundary condition at an interface between a polyatomic vapor and its condensed phase  

NASA Astrophysics Data System (ADS)

The kinetic boundary condition for the Boltzmann equation at an interface between a polyatomic vapor and its liquid phase is investigated by the numerical method of molecular dynamics, with particular emphasis on the functional form of the evaporation part of the boundary condition, including the evaporation coefficient. The present study is an extension of a previous one for argon [Ishiyama, Yano, and Fujikawa, Phys. Fluids 16, 2899 (2004)] to water and methanol, typical examples of polyatomic molecules. As in the previous study, molecular dynamics simulations of vapor-liquid equilibrium states and those of evaporation from liquid into a virtual vacuum are carried out for water and methanol. In spite of the formation of molecular clusters in the vapor phase and the presence of the preferential orientation of molecules at the interface, essentially the same results as in the previous study are obtained. When the bulk liquid temperature is relatively low, the evaporation part is the product of the half range Maxwellian for the translational velocity of molecules of saturated vapor at the temperature of the bulk liquid phase, the equilibrium distribution of rotational energy of molecules at the temperature, and the evaporation coefficient (or the condensation coefficient in the equilibrium state). The evaporation coefficients of water and methanol are determined without any ambiguity as decreasing functions of the temperature, and are found to approach unity with the decrease of the temperature.

Ishiyama, Tatsuya; Yano, Takeru; Fujikawa, Shigeo

2004-12-01

243

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

SciTech Connect

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. - Graphical abstract: Sol–gel synthesis and postsynthetic chemical modification of template-filled MCM-41 and Cl-MCM-41 with (3-chloropropyl)triethoxysilane and 1,2-ethylenediamine in vapor phase. Display Omitted - Highlights: • Synthesis of MCM-41 silica by template directed sol–gel condensation. • Selective vapor-phase functionalization of template-filled silica particles. • Preferential localization of grafted groups onto the exterior surface of mesoporous silicas.

Roik, N.V., E-mail: roik_nadya@ukr.net; Belyakova, L.A.

2013-11-15

244

m-Plane Homoepitaxy and Equilibrium Crystal Shapes of Gallium Nitride by Hydride Vapor Phase Epitaxy  

NASA Astrophysics Data System (ADS)

Nonpolar and semipolar growth of GaN has been shown to offer a promising path for high performance devices. These non-basal plane orientations allow for minimization of the polarization effects seen in c-plane GaN which cause spatial separation of the electron and hole wavefunctions (Quantum Confined Stark Effect). Yet despite the advantages these planes present, there remains consistent problems in both their growth and the lack of substrates. This dissertation focuses on the growth of these nonpolar and semipolar planes, in particular the homoepitaxy of m-plane GaN. The equilibrium crystal shape of GaN and its stable facets were also investigated. It is hoped that with this work, progress is made towards low defect large area nonpolar and semipolar substrates and their improved vapor phase growth. Work was initially done on m-plane regrowth by hydride vapor phase epitaxy. Extended defect generation, in particular basal plane stacking faults (BPSF), and poor morphology control are consistent problems in m-plane growth. These issues have prevented the expansion and multiplication of m-plane GaN substrates. In this work the effects of carrier gas were investigated on m-plane regrowth. Hydrogen carrier gas was shown to create highly faceted 3D nucleation. These islands had exposed N-face facets which lead to BPSF generation. In contrast, nitrogen carrier gas lead to 2D growth and thus minimized BPSF generation. These stacking faults were then characterized by both reciprocal space mapping and cathodolumienscence where type I1 and I2 faults were observed in the regrown GaN. Further work was done in exploring the equilibrium crystal shapes of GaN under varying growth conditions. Selective area growth experiments were done on high quality bulk m-plane GaN substrates where GaN facets were exposed to show the stable polar, semipolar and nonpolar planes. From these facets the kinetic Wulff plots for GaN were constructed. This work highlights the stable growth conditions for nonpolar and semipolar GaN and leads to improved growth conditions. AlN growth by HVPE is also investigated in this dissertation with work being done on thick AlN growth on patterned sapphire substrates (PSS). These templates were made for the purpose of substrates for UV LEDs.

Bryant, Benjamin Nathaniel

245

Bubbles in liquids with phase transition—part 2: on balance laws for mixture theories of disperse vapor bubbles in liquid with phase change  

NASA Astrophysics Data System (ADS)

We study averaging methods for the derivation of mixture equations for disperse vapor bubbles in liquids. The carrier liquid is modeled as a continuum, whereas simplified assumptions are made for the disperse bubble phase. An approach due to Petrov and Voinov is extended to derive mixture equations for the case that there is a phase transition between the carrier liquid and the vapor bubbles in water. We end up with a system of balance laws for a multi-phase mixture, which is completely in divergence form. Additional non-differential source terms describe the exchange of mass, momentum and energy between the phases. The sources depend explicitly on evolution laws for the total mass, the radius and the temperature of single bubbles. These evolution laws are derived in a prior article (Dreyer et al. in Cont Mech Thermodyn. doi:10.1007/s00161-0225-6, 2011) and are used to close the system. Finally, numerical examples are presented.

Dreyer, Wolfgang; Hantke, Maren; Warnecke, Gerald

2014-07-01

246

A model of laser ablation with temperature-dependent material properties, vaporization, phase explosion and plasma shielding  

NASA Astrophysics Data System (ADS)

Laser ablation of metals using nanosecond pulses occurs mainly due to vaporization. However, at high fluences, when the target is heated close to its critical temperature, phase explosion also occurs due to homogeneous nucleation. Due to a wide variation in target temperature, the material properties also show a considerable variation. In this paper, a model of laser ablation is presented that considers vaporization and phase explosion as mechanisms of material removal and also accounts for the variation in material properties up to critical temperature using some general and empirical theories. In addition, plasma shielding due to inverse bremsstrahlung and photo-ionization is considered. The model predicts accurately (within 5 %) the phase explosion threshold fluence of Al. The predictions of ablation depth by the model are in reasonable agreement with experimental measurements at low fluences. Whereas, the degree of error marginally increases at high laser fluences.

Marla, Deepak; Bhandarkar, Upendra V.; Joshi, Suhas S.

2014-07-01

247

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

PubMed

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 maximum. We then present and discuss the resulting nucleation onset supersaturation data within the context of nucleation theory based on the liquid droplet model. Nucleation results appear to be consistent with a cesium vapor-to-liquid nucleation study performed in a thermal diffusion cloud chamber. PMID:16108655

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

2005-08-01

248

Enhancing the adsorption of vapor-phase mercury chloride with an innovative composite sulfur-impregnated activated carbon.  

PubMed

Mercury chloride (HgCl(2)) is the major mercury derivate emitted from municipal solid waste incinerators, which has high risk to the environment and human health. This study investigated the adsorption of vapor-phase HgCl(2) with an innovative composite sulfurized activated carbon (AC), which was derived from the pyrolysis, activation, and sulfurization of waste tires. The composite sulfur-impregnation process impregnated activated carbon with aqueous-phase sodium sulfide (Na(2)S) and followed with vapor-phase elemental sulfur (S(0)). Thermogravimetric analysis (TGA) was applied to investigate the adsorptive capacity of vapor-phase HgCl(2) using the composite sulfurized AC. The operating parameters included the types of composite sulfurized AC, the adsorption temperature, and the influent HgCl(2) concentration. Experimental results indicated that the sulfur-impregnation process could increase the sulfur content of the sulfurized AC, but decreased its specific surface area. This study further revealed that the composite sulfurized AC impregnated with aqueous-phase Na(2)S and followed with vapor-phase S(0) (Na(2)S+S(0) AC) had much higher saturated adsorptive capacity of HgCl(2) than AC impregnated in the reverse sequence (S(0)+Na(2)S AC). A maximum saturated adsorptive capacity of HgCl(2) up to 5236 ?g-HgCl(2)/g-C was observed for the composite Na(2)S+S(0) AC, which was approximately 2.00 and 3.17 times higher than those for the single Na(2)S and S(0) ACs, respectively. PMID:22410724

Ie, Iau-Ren; Chen, Wei-Chin; Yuan, Chung-Shin; Hung, Chung-Hsuang; Lin, Yuan-Chung; Tsai, Hsieh-Hung; Jen, Yi-Shiu

2012-05-30

249

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

SciTech Connect

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.

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

2013-10-01

250

Hydride vapor phase epitaxy and characterization of high-quality ScN epilayers  

NASA Astrophysics Data System (ADS)

The heteroepitaxial growth of ScN films was investigated on various substrates by hydride vapor phase epitaxy (HVPE). Single crystalline mirror-like ScN(100) and ScN(110) layers were successfully deposited on r- and m-plane sapphire substrates, respectively. Homogeneous stoichiometric films (N/Sc ratio 1.01 ± 0.10) up to 40 ?m in thickness were deposited. Their mosaicity drastically improved with increasing the film thickness. The band gap was determined by optical methods to be 2.06 eV. Impurity concentrations including H, C, O, Si, and Cl were investigated through energy dispersive X-ray spectrometry and secondary ion mass spectrometry. As a result, it was found that the presence of impurities was efficiently suppressed in comparison with that of HVPE-grown ScN films reported in the past, which was possible thanks to the home-designed corrosion-free HVPE reactor. Room-temperature Hall measurements indicated that the residual free electron concentrations ranged between 1018-1020 cm-3, which was markedly lower than the reported values. The carrier mobility increased monotonically with the decreasing in carrier concentration, achieving the largest value ever reported, 284 cm2 V-1 s-1 at n = 3.7 × 1018 cm-3.

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

2014-04-01

251

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

SciTech Connect

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.

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

252

Hydride vapor phase epitaxy and characterization of high-quality ScN epilayers  

SciTech Connect

The heteroepitaxial growth of ScN films was investigated on various substrates by hydride vapor phase epitaxy (HVPE). Single crystalline mirror-like ScN(100) and ScN(110) layers were successfully deposited on r- and m-plane sapphire substrates, respectively. Homogeneous stoichiometric films (N/Sc ratio 1.01?±?0.10) up to 40??m in thickness were deposited. Their mosaicity drastically improved with increasing the film thickness. The band gap was determined by optical methods to be 2.06?eV. Impurity concentrations including H, C, O, Si, and Cl were investigated through energy dispersive X-ray spectrometry and secondary ion mass spectrometry. As a result, it was found that the presence of impurities was efficiently suppressed in comparison with that of HVPE-grown ScN films reported in the past, which was possible thanks to the home-designed corrosion-free HVPE reactor. Room-temperature Hall measurements indicated that the residual free electron concentrations ranged between 10{sup 18}–10{sup 20}?cm{sup ?3}, which was markedly lower than the reported values. The carrier mobility increased monotonically with the decreasing in carrier concentration, achieving the largest value ever reported, 284?cm{sup 2}?V{sup ?1}?s{sup ?1} at n?=?3.7?×?10{sup 18}?cm{sup ?3}.

Oshima, Yuichi, E-mail: OSHIMA.Yuichi@nims.go.jp; Víllora, Encarnación G.; Shimamura, Kiyoshi [Environment and Energy Materials Research Division, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)

2014-04-21

253

ZnO nanorod growth by plasma-enhanced vapor phase transport with different growth durations  

SciTech Connect

In this study, the structural properties of ZnO nanostructures grown by plasma-enhanced vapor phase transport (PEVPT) were investigated. Plasma-treated oxygen gas was used as the oxygen source for the ZnO growth. The structural properties of ZnO nanostructures grown for different durations were measured by scanning electron microscopy, x-ray diffraction, and transmission electron microscopy. The authors comprehensively analyzed the growth of the ZnO nanostructures with different growth durations both with and without the use of plasma-treated oxygen gas. It was found that PEVPT has a significant influence on the growth of the ZnO nanorods. PEVPT with plasma-treated oxygen gas facilitated the generation of nucleation sites, and the resulting ZnO nanorod structures were more vertical than those prepared by conventional VPT without plasma-treated oxygen gas. As a result, the ZnO nanostructures grown using PEVPT showed improved structural properties compared to those prepared by the conventional VPT method.

Kim, Chang-Yong; Oh, Hee-bong [Department of Nano Science and Engineering, Inje University, Obang-dong, Gimhae, Gyeongnam 621-749 (Korea, Republic of); Ryu, Hyukhyun, E-mail: hhryu@inje.ac.kr [Department of Nano Science and Engineering, Center for Nano Manufacturing, Inje University, Obang-dong, Gimhae, Gyeongnam 621-749 (Korea, Republic of); Yun, Jondo [Department of Nano Science and Engineering, Kyungnam University, Changwon, Gyeongnam 631-701 (Korea, Republic of); Lee, Won-Jae [Department of Materials and Components Engineering, Dong-Eui University, 995 Eomgwangno, Busanjin-gu, Busan 614-714 (Korea, Republic of)

2014-09-01

254

Influence of plasma treatment time on plasma induced vapor phase grafting modification of PBO fiber surface  

NASA Astrophysics Data System (ADS)

The surface of poly-p-phenylene benzobisthiazole (PBO) fibers was treated through oxygen plasma induced vapor phase grafting (PIVPG) method under various oxygen plasma pre-treatment time conditions. The surface chemical composition, surface morphologies and surface free energy of pristine and treated PBO fibers were studied using X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, and Cahn DCAA system. The mechanics property of these fibers was evaluated by tensile strength and interfacial shear strength (IFSS). It was found that the surface characteristics of treated PBO fibers occurred significant change compare with the pristine PBO fibers. After treatment, the polar functional groups were introduced on the fiber surface. Carbon concentration decreased; oxygen concentration and elemental ratio of oxygen to carbon increased. Acrylic acid can react with the activated PBO fibers surface, which led to the fiber surface roughness increased. The surface free energy increased from 41.4 mN/m to 62.8 mN/m when PBO fibers were plasma pre-treated for 10 min, while the IFSS of PBO fibers with epoxy resin increased from 36.6 MPa to 55.8 MPa. Therefore, PIVPG can be used to enhance the interfacial bond between PBO fibers and epoxy resin.

Song, B.; Meng, L. H.; Huang, Y. D.

2012-05-01

255

Pentacene/K12 solar cells formed by organic vapor phase deposition  

NASA Astrophysics Data System (ADS)

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.

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

2014-01-01

256

Growth mechanism of InGaN quantum dots during metalorganic vapor phase epitaxy  

NASA Astrophysics Data System (ADS)

Growth mechanism of InGaN quantum dots on GaN was studied during metalorganic vapor phase epitaxy in a temperature range of 600-750 °C in a horizontal reactor. Atomic force microscopy and high resolution X-ray diffraction show that InGaN quantum dots on GaN are formed according to the Stranski-Krastanov growth mode. When growth temperature was varied between 600 and 750 °C, a 2-3-dimensional growth transition was observed below 650 °C due to the increase in indium content. While the layer thickness was varied, similar transitions were observed with critical thicknesses of ?2.7 nm and ?4 nm at growth temperatures of 625 °C (In0.31Ga0.69N) and 675 °C (In0.22Ga0.78N), respectively. InGaN quantum dots with a density of ?1010 cm-2, an average diameter of ?40 nm and average height of ?4 nm were obtained. Reciprocal space maps from the asymmetric (10-15) reflection show that all the InGaN samples are fully strained. Strong green emission at 534 nm was observed from InGaN grown at 675 °C.

Kadir, Abdul; Meissner, Christian; Schwaner, Tilman; Pristovsek, Markus; Kneissl, Michael

2011-11-01

257

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

PubMed

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

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

2013-05-22

258

Unintentional Ga incorporation in metalorganic vapor phase epitaxy of In-containing III-nitride semiconductors  

NASA Astrophysics Data System (ADS)

We prepared InAlN barrier layer films on GaN buffer layers using the metalorganic vapor phase epitaxy (MOVPE) method and investigated the InAlN/GaN heterointerfaces. Secondary ion spectroscopy experiments revealed that a quaternary alloy of InAlGaN is grown on GaN even when trimethylindium (TMIn) and trimethylaluminum (TMAl) are exclusively supplied as group-III precursors, indicating that Ga is unintentionally incorporated into the InAlN layers. This Ga incorporation is also observed in InGaN/GaN heterostructures. Our systematic investigations of the growth condition dependence, such as the TMIn flow rate, indicate that the Ga is supplied by a transmetalation reaction between TMIn and residual Ga on the flow distributor in the reactor. Here, we show that the Ga incorporation can be eliminated by adopting an elaborate growth sequence, including reactor cleaning and regrowth processes. This study provides guides for designing the MOVPE reactor configuration, as well as the growth sequences, for the growth of device structures with In-containing nitride layers.

Hiroki, Masanobu; Oda, Yasuhiro; Watanabe, Noriyuki; Maeda, Narihiko; Yokoyama, Haruki; Kumakura, Kazuhide; Yamamoto, Hideki

2013-11-01

259

Growth of thick InGaN layers by tri-halide vapor phase epitaxy  

NASA Astrophysics Data System (ADS)

This is the first study to report InGaN growth by tri-halide vapor phase epitaxy (THVPE) using InCl3 and GaCl3 generated by the reactions between metal sources (i.e., metallic indium and gallium) and gaseous chlorine. The influence of the surface orientation of the initial substrate on InGaN-THVPE growth was investigated using freestanding (0001) and (000\\bar{1}) GaN substrates. Only a N-polar InGaN epitaxial layer was obtained by THVPE because of the instability of GaCl3 adsorption toward nitrogen atoms on the Ga-polar surface. In addition, we investigated the influence of the group-III input partial pressure on the growth rate and solid composition of InGaN layers grown on a (000\\bar{1}) GaN substrate. The growth rate increased linearly with group-III concentration, and a maximum growth rate of 15.6 µm/h was achieved at PIII = 2.0 × 10-3 atm.

Hirasaki, Takahide; Asano, Kazuma; Banno, Mizuki; Ishikawa, Masato; Sakuma, Fumiaki; Murakami, Hisashi; Kumagai, Yoshinao; Koukitu, Akinori

2014-01-01

260

Environmentally Compatible Vapor-Phase Corrosion Inhibitor for Space Shuttle Hardware  

NASA Technical Reports Server (NTRS)

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.

Novak, Howard L.; Hall, Phillip B.

2003-01-01

261

Exchange of Na+ and K+ between water vapor and feldspar phases at high temperature and low vapor pressure  

USGS Publications Warehouse

In order to determine whether gas (steam) containing a small amount of dissolved alkali chloride is effective in promoting base exchange of Na+ and K+ among alkali feldspars and coexisting brine or brine plus solid salt, experiments were carried out at 400-700??C and steam densities ranging down to less than 0.05. For bulk compositions rich in potassium, the low pressure results are close to previous high-pressure results in composition of the fluid and coexisting solid phase. However, when the bulk composition is more sodic, alkali feldspars are relatively richer in potassium at low pressure than at high pressure. This behaviour corresponds to enrichment of potassium in the gas phase relative to coexisting brine and precipitation of solid NaCl when the brine plus gas composition becomes moderately sodic. The gas phase is very effective in promoting base exchange between coexisting alkali feldspars at high temperature and low water pressure. This suggests that those igneous rocks which contain coexisting alkali feldspars out of chemical equilibrium either remained very dry during the high-temperature part of their cooling history or that the pore fluid was a gas containing very little potassium relative to sodium. ?? 1976.

Fournier, R.O.

1976-01-01

262

Field tests of a chemiresistor sensor for in-situ monitoring of vapor-phase contaminants  

NASA Astrophysics Data System (ADS)

An in-situ chemiresistor sensor has been developed that can detect volatile organic compounds in subsurface environmental applications. Several field tests were conducted in 2001 and 2002 to test the reliability, operation, and performance of the in-situ chemiresistor sensor system. The chemiresistor consists of a carbon-loaded polymer deposited onto a microfabricated circuit. The polymer swells reversibly in the presence of volatile organic compounds as vapor-phase molecules absorb into the polymer, causing a change in the electrical resistance of the circuit. The change in resistance can be calibrated to known concentrations of analytes, and arrays of chemiresistors can be used on a single chip to aid in discrimination. A waterproof housing was constructed to allow the chemiresistor to be used in a variety of media including air, soil, and water. The integrated unit, which can be buried in soils or emplaced in wells, is connected via cable to a surface-based solar-powered data logger. A cell-phone modem is used to automatically download the data from the data logger on a periodic basis. The field tests were performed at three locations: (1) Edwards Air Force Base, CA; (2) Nevada Test Site; and (3) Sandia's Chemical Waste Landfill near Albuquerque, NM. The objectives of the tests were to evaluate the ruggedness, longevity, operation, performance, and engineering requirements of these sensors in actual field settings. Results showed that the sensors could be operated continuously for long periods of time (greater than a year) using remote solar-powered data-logging stations with wireless telemetry. The sensor housing, which was constructed of 304 stainless steel, showed some signs of corrosion when placed in contaminated water for several months, but the overall integrity was maintained. The detection limits of the chemiresistors were generally found to be near 0.1% of the saturated vapor pressure of the target analyte in controlled laboratory conditions (e.g., ~100 ppmv for TCE), but fluctuations in environmental parameters and other interferences increased the detection limit by about an order of magnitude in the field tests. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000.

Ho, C.; McGrath, L.; Wright, J.

2003-04-01

263

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

USGS Publications Warehouse

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.

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

1990-01-01

264

GaAs tunnel junction grown by metalorganic vapor-phase epitaxy for multigap cascade solar cells  

SciTech Connect

GaAs tunnel p-n junctions with peak current densities up to 45 A cm/sup -2/ were grown by metallorganic vapor-phase epitaxy. These tunnel diodes are suitable for intercell ohmic contacts between the case of integrated tandem photovoltaic subcells in solar cells based on GaAs. The peak current is high enough for concentration up to C = 1000.

Basmaji, P.; Guittard, M.; Rudra, A.; Carlin, J.F.; Gibart, P.

1987-09-01

265

Dual wavelength InGaN\\/GaN multi-quantum well LEDs grown by metalorganic vapor phase epitaxy  

Microsoft Academic Search

InGaN\\/GaN multiple quantum well (MQW) light-emitting diodes (LEDs) with different well widths and barrier widths were grown on sapphire substrates using metalorganic vapor phase epitaxy (MOVPE). The designed emission wavelengths were in the blue and green regions. The blue MQWs and green MQWs were deposited sequentially and the growth parameters were separately optimized for single color blue and green emission

Y. D. Qi; H. Liang; W. Tang; Z. D. Lu; Kei May Lau

2004-01-01

266

Thermal effects on light-emission properties of GaN LEDs grown by metal-organic vapor phase epitaxy  

Microsoft Academic Search

Photoluminescence (PL) spectra of GaN layers grown on sapphire substrates by metal-organic vapor phase epitaxy (MOVPE) were observed at temperatures from RT to 500K. The spectra include the near-band-edge emission (NBE) and yellow luminescence (YL). The peak energy of the NBE is shifted towards lower energy with increasing observed temperature. UV light-emitting diodes (LEDs) utilizing band-gap narrowing due to thermal

Tohru Honda; Toshiaki Kobayashi; Shinichi Egawa; Masaru Sawada; Koichi Sugimoto; Taichi Baba

2007-01-01

267

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

DOEpatents

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.

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

2001-01-01

268

Advanced Life Support Water Recycling Technologies Case Studies: Vapor Phase Catalytic Ammonia Removal and Direct Osmotic Concentration  

NASA Technical Reports Server (NTRS)

Design for microgravity has traditionally not been well integrated early on into the development of advanced life support (ALS) technologies. NASA currently has a many ALS technologies that are currently being developed to high technology readiness levels but have not been formally evaluated for microgravity compatibility. Two examples of such technologies are the Vapor Phase Catalytic Ammonia Removal Technology and the Direct Osmotic Concentration Technology. This presentation will cover the design of theses two systems and will identify potential microgravity issues.

Flynn, Michael

2004-01-01

269

An Evaluation of the Vapor Phase Catalytic Ammonia Removal Process for Use in a Mars Transit Vehicle  

NASA Technical Reports Server (NTRS)

An experimental program has been developed to evaluate the potential of the Vapor Phase Catalytic Ammonia Reduction (VPCAR) technology for use as a Mars Transit Vehicle water purification system. Design modifications which will be required to ensure proper operation of the VPCAR system in reduced gravity are also evaluated. The VPCAR system is an integrated wastewater treatment technology that combines a distillation process with high temperature catalytic oxidation. The distillation portion of the system utilizes a vapor compression distillation process to provide an energy efficient phase change separation. This portion of the system removes any inorganic salts and large molecular weight, organic contaminates, i.e., non-volatile, from the product water stream and concentrates these contaminates into a byproduct stream. To oxidize the volatile organic compounds and ammonia, a vapor phase, high temperature catalytic oxidizer is used. This catalytic system converts these compounds along with the aqueous product into CO2, H2O, and N2O. A secondary catalytic bed can then be used to reduce the N2O to nitrogen and oxygen (although not evaluated in this study). This paper describes the design specification of the VPCAR process, the relative benefits of its utilization in a Mars Transit Vehicle, and the design modification which will be required to ensure its proper operation in reduced gravity. In addition, the results of an experimental evaluation of the processors is presented. This evaluation presents the processors performance based upon product water purity, water recovery rates, and power.

Flynn, Michael; Borchers, Bruce

1998-01-01

270

Vapor-phase concentrations of PAHs and their derivatives determined in a large city: correlations with their atmospheric aerosol concentrations.  

PubMed

Thirteen PAHs, five nitro-PAHs and two hydroxy-PAHs were determined in 55 vapor-phase samples collected in a suburban area of a large city (Madrid, Spain), from January 2008 to February 2009. The data obtained revealed correlations between the concentrations of these compounds and a series of meteorological factors (e.g., temperature, atmospheric pressure) and physical-chemical factors (e.g., nitrogen and sulfur oxides). As a consequence, seasonal trends were observed in the atmospheric pollutants. A "mean sample" for the 14-month period would contain a total PAH concentration of 13835±1625 pg m(-3) and 122±17 pg m(-3) of nitro-PAHs. When the data were stratified by season, it emerged that a representative sample of the coldest months would contain 18900±2140 pg m(-3) of PAHs and 150±97 pg m(-3) of nitro-PAHs, while in an average sample collected in the warmest months, these values drop to 9293±1178 pg m(-3) for the PAHs and to 97±13 pg m(-3) for the nitro-PAHs. Total vapor phase concentrations of PAHs were one order of magnitude higher than concentrations detected in atmospheric aerosol samples collected on the same dates. Total nitro-PAH concentrations were comparable to their aerosol concentrations whereas vapor phase OH-PAHs were below their limits of the detection, indicating these were trapped in airborne particles. PMID:23816454

Barrado, Ana Isabel; García, Susana; Sevillano, Marisa Luisa; Rodríguez, Jose Antonio; Barrado, Enrique

2013-11-01

271

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

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

Sekine, Takashi; Sakaguchi, Chikako; Fukano, Yasuo

2015-02-01

272

Engineering of compound semiconductor nanostructures by metalorganic vapor-phase epitaxy  

NASA Astrophysics Data System (ADS)

The structure and chemistry of compound semiconductor surfaces during metalorganic vapor-phase epitaxy have been investigated. In particular, surface roughness, interface structure, and heterogeneous reaction kinetics of the group V precursors were studied. Moreover, the structures of the compound semiconductor surfaces have been examined using scanning tunneling microscopy, x-ray photoemission spectroscopy, and reflectance difference spectroscopy. The surface roughness of gallium arsenide (001) films changes with the temperature and growth rate. Height-height correlation analysis of scanning tunneling micrographs reveals that the root-mean height difference on the surface follows a power law dependence on lateral separation, i.e., Gamma(L) = kLalpha, up to a critical distance, Lc, after which it remains constant. For layer-by-layer growth, the roughness exponent, alpha, equals 0.25 +/- 0.05, whereas the critical distance increases from 50 to 150 nm as the substrate temperature increases from 825 to 900 K. The roughness exponent jumps to 0.65 +/- 0.1 upon transitioning to three-dimensional island growth. By relating the height-height correlation function to the Einstein diffusivity relationship, the activation energy for gallium surface diffusion was estimated: Ed = 1.35 +/- 0.1 eV. Exposing indium phosphide films to 10 mTorr of tertiarybutylarsine below 500°C results in the deposition of a thin indium arsenide layer from 1.5 to 5.0 atomic layers thick (2.3 to 7.5 A). The surface of this layer remains atomically smooth independent of arsenic exposure time. However, in an overpressure of tertiarybutylarsine at or above 500°C, the arsenic atoms diffuse into the bulk, creating strained InAsP films. These films form three-dimensional island structures to relieve the built-up strain. The activation energy and pre-exponential factor for arsenic diffusion into indium phosphide was found to be: Ed = 1.7 +/- 0.2 eV and Do = 2.3 +/- 1.0 x 10-7 cm2/s. The kinetics of phosphine adsorption and phosphorus desorption from gallium phosphide and indium phosphide (001) surfaces have been studied using reflectance difference spectroscopy to monitor the phosphorus coverage in real time. The adsorption and desorption processes follow first-order reactions. The rate parameters were determined by fitting the experimental data to a kinetic model. The initial sticking coefficients of phosphine on GaP (2x4), (1x1), and InP (2x4) surfaces were found to be 730.0·exp(-0.6 +/- 0.2(eV)/kT), 1.6·exp(-0.4 +/- 0.2(eV)/kT) and 0.0055·exp(-0.1 +/- 0.2eV/kT), respectively. The desorption of phosphorus from the GaP (2x1) and (1x1) surfaces was first-order in coverage with rate constants of 5.0 x 1015(s-1)·exp(-2.6 +/- 0.2(eV)/kT) and 5.0 x 1015(s-1 )·exp(-2.9 +/- 0.4(eV)/kT). The results presented in this thesis illustrate how molecular-scale chemical phenomena affect the evolution of compound semiconductor nanostructures during metalorganic vapor-phase epitaxy.

Law, Daniel Ching Bong

273

Recent progress in GaInAsSb thermophotovoltaics grown by organometallic vapor phase epitaxy  

SciTech Connect

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.

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

274

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

NASA Astrophysics Data System (ADS)

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.

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

2012-06-01

275

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

PubMed

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

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

2014-02-18

276

Polycrystalline indium phosphide on silicon by indium assisted growth in hydride vapor phase epitaxy  

NASA Astrophysics Data System (ADS)

Polycrystalline InP was grown on Si(001) and Si(111) substrates by using indium (In) metal as a starting material in hydride vapor phase epitaxy (HVPE) reactor. In metal was deposited on silicon substrates by thermal evaporation technique. The deposited In resulted in islands of different size and was found to be polycrystalline in nature. Different growth experiments of growing InP were performed, and the growth mechanism was investigated. Atomic force microscopy and scanning electron microscopy for morphological investigation, Scanning Auger microscopy for surface and compositional analyses, powder X-ray diffraction for crystallinity, and micro photoluminescence for optical quality assessment were conducted. It is shown that the growth starts first by phosphidisation of the In islands to InP followed by subsequent selective deposition of InP in HVPE regardless of the Si substrate orientation. Polycrystalline InP of large grain size is achieved and the growth rate as high as 21 ?m/h is obtained on both substrates. Sulfur doping of the polycrystalline InP was investigated by growing alternating layers of sulfur doped and unintentionally doped InP for equal interval of time. These layers could be delineated by stain etching showing that enough amount of sulfur can be incorporated. Grains of large lateral dimension up to 3 ?m polycrystalline InP on Si with good morphological and optical quality is obtained. The process is generic and it can also be applied for the growth of other polycrystalline III-V semiconductor layers on low cost and flexible substrates for solar cell applications.

Metaferia, Wondwosen; Sun, Yan-Ting; Pietralunga, Silvia M.; Zani, Maurizio; Tagliaferri, Alberto; Lourdudoss, Sebastian

2014-07-01

277

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

PubMed Central

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

2013-01-01

278

Polycrystalline indium phosphide on silicon by indium assisted growth in hydride vapor phase epitaxy  

SciTech Connect

Polycrystalline InP was grown on Si(001) and Si(111) substrates by using indium (In) metal as a starting material in hydride vapor phase epitaxy (HVPE) reactor. In metal was deposited on silicon substrates by thermal evaporation technique. The deposited In resulted in islands of different size and was found to be polycrystalline in nature. Different growth experiments of growing InP were performed, and the growth mechanism was investigated. Atomic force microscopy and scanning electron microscopy for morphological investigation, Scanning Auger microscopy for surface and compositional analyses, powder X-ray diffraction for crystallinity, and micro photoluminescence for optical quality assessment were conducted. It is shown that the growth starts first by phosphidisation of the In islands to InP followed by subsequent selective deposition of InP in HVPE regardless of the Si substrate orientation. Polycrystalline InP of large grain size is achieved and the growth rate as high as 21 ?m/h is obtained on both substrates. Sulfur doping of the polycrystalline InP was investigated by growing alternating layers of sulfur doped and unintentionally doped InP for equal interval of time. These layers could be delineated by stain etching showing that enough amount of sulfur can be incorporated. Grains of large lateral dimension up to 3??m polycrystalline InP on Si with good morphological and optical quality is obtained. The process is generic and it can also be applied for the growth of other polycrystalline III–V semiconductor layers on low cost and flexible substrates for solar cell applications.

Metaferia, Wondwosen; Sun, Yan-Ting, E-mail: yasun@kth.se; Lourdudoss, Sebastian [Laboratory of Semiconductor Materials, Department of Materials and Nano Physics, KTH—Royal Institute of Technology, Electrum 229, 164 40 Kista (Sweden); Pietralunga, Silvia M. [CNR-Institute for Photonics and Nanotechnologies, P. Leonardo da Vinci, 32 20133 Milano (Italy); Zani, Maurizio; Tagliaferri, Alberto [Department of Physics Politecnico di Milano, P. Leonardo da Vinci, 32 20133 Milano (Italy)

2014-07-21

279

TREATMENT OF PRODUCED WATERS USING A SURFACTANT MODIFIED ZEOLITE/VAPOR PHASE BIOREACTOR SYSTEM  

SciTech Connect

Co-produced water from the oil and gas industry accounts for a significant waste stream in the United States. It is by some estimates the largest single waste stream in the country, aside from nonhazardous industrial wastes. Characteristics of produced water include high total dissolved solids content, dissolved organic constituents such as benzene and toluene, an oil and grease component, and chemicals added during the oil-production process. While most of the produced water is disposed via reinjection, some of them must be treated to remove organic constituents before the water is discharged. Current treatment options are successful in reducing the organic content; however, they cannot always meet the levels of current or proposed regulations for discharged water. Therefore, an efficient, cost-effective treatment technology is needed. Surfactant-modified zeolite (SMZ) has been used successfully to treat contaminated ground water for organic and inorganic constituents. In addition, the low cost of natural zeolites makes their use attractive in water-treatment applications. Our previous DOE research work (DE-AC26-99BC15221) demonstrated that SMZ could successfully remove BTEX compounds from the produced water. In addition, SMZ could be regenerated through a simple air sparging process. The primary goal of this project is to develop a robust SMZ/VPB treatment system to efficiently remove the organic constituents from produced water in a cost-effective manner. This report summarizes work of this project from October 2002 to March 2003. In this starting stage of this study, we have continued our investigation of SMZ regeneration from our previous DOE project. Two saturation/stripping cycles have been completed for SMZ columns saturated with BTEX compounds. Preliminary results suggest that BTEX sorption actually increases with the number of saturation/regeneration cycles. Furthermore, the experimental vapor phase bioreactors for this project have been designed and are currently being assembled to treat the off-gas from the SMZ regeneration process.

Lynn E. Katz; Kerry A. Kinney; R.S. Bowman; E.J. Sullivan

2003-04-01

280

Investigation of vapor-phase lubrication in a gas turbine engine  

SciTech Connect

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.

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

281

Simultaneous absorption of vapor phase polycyclic aromatic hydrocarbon and carbon dioxide in anionic surfactant solutions.  

PubMed

The goal of this work was to investigate whether the solubility of vapor phase polycyclic aromatic compounds (PAHs) and CO2 in water could be enhanced by adding anionic surfactant during the absorption process. Naphthalene was the PAH surrogate and sodium dodecyl sulfate (SDS) was the anionic surfactant. A series of batch experiments in an absorption cell were performed at 50 degrees C with the surfactant concentration both lower than and higher than the critical micelle concentration (CMC). The experimental findings indicate that the CMC was not a function of pH at values of 3, 5 and 7. Furthermore, at surfactant concentrations less than the CMC, naphthalene apparent solubility increased slightly. On the other hand, the equilibrium naphthalene or CO2 apparent solubility increased linearly, in proportion to the surfactant concentration at concentrations greater than the CMC. This is due to the solubilization effect of micelles, which were formed by the surfactant at concentrations above the CMC. During simultaneous absorption of the two, the presence of CO2 only slightly decreased naphthalene apparent solubility, while the apparent solubility of CO2 was drastically reduced in the presence of naphthalene. As the magnitude of the micelle solubilization effect was greater than the reduction of the mass transfer coefficient in the presence of the surfactant, the total gas absorption rate increased. When the surfactant concentration was 0.1 M, the enrichment factor (the ratio of the solubility in surfactant solution to that in water) values of naphthalene both with and without CO2 increased to 9.05 and 8.60, respectively. These experimental findings demonstrate that anionic surfactant may be applied to increase the removal efficiency of hydrophobic compounds and CO2 through either a spray or packed tower. PMID:11545346

Huang, H L; Lee, W M

2001-01-01

282

Desalination-of water by vapor-phase transport through hydrophobic nanopores  

E-print Network

We propose a new approach to desalination of water whereby a pressure difference across a vapor-trapping nanopore induces selective transport of water by isothermal evaporation and condensation across the pore. Transport ...

Lee, Jongho

283

VAPOR PHASE MERCURY SORPTION BY ORGANIC SULFIDE MODIFIED BIMETALLIC IRON-COPPER NANOPARTICLE AGGREGATES  

EPA Science Inventory

Novel organic sulfide modified bimetallic iron-copper nanoparticle aggregate sorbent materials have been synthesized for removing elemental mercury from vapor streams at elevated temperatures (120-140 °C). Silane based (disulfide silane and tetrasulfide silane) and alkyl sulfide ...

284

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...

285

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

PubMed

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

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

2009-03-16

286

Toxicological assessment of kretek cigarettes Part 4: mechanistic investigations, smoke chemistry and in vitro toxicity.  

PubMed

The smoke chemistry and in vitro toxicity of mainstream smoke (MS) was investigated in American-blended cigarettes with or without the addition of 2.5%, 5% or 10% eugenol to the tobacco and in Indonesian-blended cigarettes with and without the addition of cloves, cloves extracted with hot ethanol, and extracted cloves replenished with eugenol or clove oil. The addition of eugenol reduced the concentration of nearly all toxicants measured in MS as well as the in vitro cytotoxicity of the gas/vapor phase. Reductions were also seen in bacterial mutagenicity of the total particulate matter (TPM) assessed by the Ames Assay. The addition of extracted cloves led to increases and decreases of toxicant concentrations in MS. Replenishment with eugenol or clove oil decreased the toxicant concentrations; with most smoke constituent concentrations reduced below the concentration found in tobacco-only cigarettes. Cytotoxicity of the TPM was not affected by the clove preparations. However, GVP cytotoxicity was reduced (untreated cloves showing the highest reductions). Mutagenicity of TPM was decreased by the clove preparations. Mechanisms for the reductions, (up to 40%), are most likely due to dilution effects by eugenol, changed burning characteristics of the tobacco, and free radical scavenging by eugenol. PMID:25455230

Roemer, E; Dempsey, R; Lawless-Pyne, J; Lukman, S; Evans, A Deger; Trelles-Sticken, E; Wittke, S; Schorp, M K

2014-12-01

287

Ferromagnetism in (In,Mn)As Diluted Magnetic Semiconductor Thin Films Grown by Metalorganic Vapor Phase Epitaxy  

Microsoft Academic Search

In1-xMnxAs diluted magnetic semiconductor (DMS) thin films have been grown\\u000ausing metalorganic vapor phase epitaxy (MOVPE).\\u000aTricarbonyl(methylcyclopentadienyl)manganese was used as the Mn source.\\u000aNominally single-phase, epitaxial films were achieved with Mn content as high\\u000aas x=0.14 using growth temperatures Tg>475 C. For lower growth temperatures and\\u000ahigher Mn concentrations, nanometer scale MnAs precipitates were detected\\u000awithin the In1-xMnxAs matrix. Magnetic

A. J. Blattner; B. W. Wessels

2002-01-01

288

Observation of photoluminescence from Al1-xInxN heteroepitaxial films grown by metalorganic vapor phase epitaxy  

NASA Astrophysics Data System (ADS)

We have observed photoluminescence of Al1-xInxN films. The films were grown on GaN by atmospheric pressure metalorganic vapor phase epitaxy. GaN was grown on a c-plane sapphire substrate with a low-temperature deposited AlN buffer layer. Photoluminescence, absorption, and x-ray diffraction measurements have shown that each spectral peak shifts with alloy composition x and that Al1-xInxN heteroepitaxial films are not macroscopically in phase separation and are constituted in the wurzite structure.

Yamaguchi, Shigeo; Kariya, Michihiko; Nitta, Shugo; Takeuchi, Tetsuya; Wetzel, Christian; Amano, Hiroshi; Akasaki, Isamu

1998-08-01

289

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

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

290

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

PubMed

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

Etter, Jean-François

2015-01-01

291

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

PubMed

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:25779729

Etter, Jean-François

2015-12-01

292

Cigarette smoking and schizophrenia   

E-print Network

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 ...

Patrick, Jon Alan

2007-06-28

293

Chemical analysis of cigarette smoke particulate generated in the MSB-01 in vitro whole smoke exposure system.  

PubMed

Cigarette mainstream smoke (MS) is a dynamic aerosol consisting of a gas-vapor phase and a particulate phase. In recent years, novel in vitro whole smoke exposure systems have been developed to expose cells directly to whole MS. One such system is the Burghart Mimic Smoker-01 (MSB-01). Our previous data using the MSB-01 indicated that a 50 +/- 10% loss of particulate matter occurred prior to MS delivery into the exposure chamber. Additionally, a change in aerosol particle diameter was also measured, suggesting that the chemical composition of MS might be changing within the system. In this study, we have expanded on our previous work and compared the particulate phase chemical composition of undiluted and diluted MS generated by the instrument and that of the MS delivered into the exposure chamber. The average percent delivery of cigarette smoke condensate (CSC) detected for all the measured chemical constituents was 35 +/- 13% for undiluted MS and 23 +/- 8% for 1:1 diluted MS. The data also indicate that under our experimental conditions, incomplete mixing of the freshly generated MS occurs during its dilution by the system. Taken together, the data presented here show that significant chemical changes occur between the generation of MS by the system and its delivery into the exposure chamber. This indicates that due to the dynamic nature of cigarette smoke, it is important to characterize the exposure conditions in order to gain the best insight and accurately correlate exposure with biological endpoints. PMID:19772483

Scian, Mariano J; Oldham, Michael J; Miller, John H; Kane, David B; Edmiston, Jeffery S; McKinney, Willie J

2009-10-01

294

Anomalous features in the optical properties of Al1xInxN on GaN grown by metal organic vapor phase epitaxy  

E-print Network

Anomalous features in the optical properties of Al1ÀxInxN on GaN grown by metal organic vapor phase and Electronic Engineering, Meijo University, 1-501 Shiogamaguchi Tempaku-ku, Nagoya, 468-8502, Japan ChristianInxN thin films grown on GaN by metal organic vapor phase epitaxy. X-ray diffraction analysis of and -2

Wetzel, Christian M.

295

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

NASA Astrophysics Data System (ADS)

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.

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

2002-05-01

296

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

SciTech Connect

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.

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

1992-08-06

297

Uniform phase modulation via control of refractive index in a thermal atom vapor with vanishing diffraction or absorption  

NASA Astrophysics Data System (ADS)

A scheme is proposed to achieve substantial controllable phase modulation for a probe field propagating through a thermal atomic vapor in double-? configuration. The phase modulation is based on manipulating the linear susceptibility of the probe field, paraxial diffraction is eliminated by exploiting the thermal motion of atoms, and residual absorption is compensated via an incoherent pump field. As a result of the homogeneous change in the refractive index, a strong controllable uniform phase modulation without paraxial diffraction is achieved essentially independent of the spatial profile or the intensity of the probe field. This phase shift can be controlled via the intensities of the control or the incoherent pump fields. A possible proof-of-principle experiment in alkali-metal atoms is discussed.

Zhang, Lida; Evers, Jörg

2014-08-01

298

The role of polymer formation during vapor phase lubrication of silicon.  

SciTech Connect

The lubrication of silicon surfaces with alcohol vapors has recently been demonstrated. With a sufficient concentration of pentanol vapor present, sliding of a silica ball on an oxidized silicon wafer can proceed with no measurable wear. The initial results of time-of-flight secondary ion mass spectrometry (ToF-SIMS) analysis of wear surfaces revealed a reaction product having thickness on the order of a monolayer, and with an ion spectrum that included fragments having molecular weights of 200 or more that occurred only inside the wear tracks. The parent alcohol molecule pentanol, has molecular weight of 88amu, suggesting that reactions of adsorbed alcohols on the wearing surfaces allowed polymerization of the alcohols to form higher molecular weight species. In addition to pin-on-disk studies, lubrication of silicon surfaces with pentanol vapors has also been demonstrated using MicroElectroMechanical Systems (MEMS) devices. Recent investigations of the reaction mechanisms of the alcohol molecules with the oxidized silicon surfaces have shown that wearless sliding requires a concentration of the alcohol vapor that is dependent upon the contact stress during sliding, with higher stress requiring a greater concentration of alcohol. Different vapor precursors including those with acid functionality, olefins, and methyl termination also produce polymeric reaction products, and can lubricate the silica surfaces. Doping the operating environment with oxygen was found to quench the formation of the polymeric reaction product, and demonstrates that polymer formation is not necessary for wearless sliding.

Dugger, Michael Thomas; Dirk, Shawn M.; Ohlhausen, James Anthony

2010-10-01

299

Toxicological assessment of kretek cigarettes: Part 2: kretek and American-blended cigarettes, smoke chemistry and in vitro toxicity.  

PubMed

Two commercial kretek cigarettes typical for the Indonesian market and a reference kretek cigarette were compared to the American-blended reference cigarette 2R4F by smoke chemistry characterization and in vitro cytotoxicity and mutagenicity assessments. Despite the widely diverse designs and deliveries of the selected kretek cigarettes, their smoke composition and in vitro toxicity data present a consistent pattern when data were normalized to total particulate matter (TPM) deliveries. This confirms the applicability of the studies' conclusions to a wide range of kretek cigarette products. After normalization to TPM delivery, nicotine smoke yields of kretek cigarettes were 29-46% lower than that of the 2R4F. The yields of other nitrogenous compounds were also much lower, less than would be expected from the mere substitution of one third of the tobacco filler by clove material. Yields of light molecular weight pyrolytic compounds, notably aldehydes and hydrocarbons, were reduced, while yields of polycyclic aromatic hydrocarbons were unchanged and phenol yield was increased. The normalized in vitro toxicity was lowered accordingly, reflecting the yield reductions in gas-phase cytotoxic compounds and some particulate-phase mutagenic compounds. These results do not support a higher toxicity of the smoke of kretek cigarettes compared to American-blended cigarettes. PMID:25497993

Piadé, J-J; Roemer, E; Dempsey, R; Hornig, G; Deger Evans, A; Völkel, H; Schramke, H; Trelles-Sticken, E; Wittke, S; Weber, S; Schorp, M K

2014-12-01

300

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

SciTech Connect

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.

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

2005-03-11

301

27 CFR 41.34 - Cigarette papers.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2011-04-01 true Cigarette papers. 41.34 Section 41...IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED... Taxes Tax Rates § 41.34 Cigarette papers. Cigarette papers...

2012-04-01

302

27 CFR 41.35 - Cigarette tubes.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Cigarette tubes. 41.35 Section 41...IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED... Taxes Tax Rates § 41.35 Cigarette tubes. Cigarette tubes...

2014-04-01

303

27 CFR 41.38 - Cigarettes.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2011-04-01 true Cigarettes. 41.38 Section 41.38 Alcohol... IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO... Classification of Large Cigars and Cigarettes § 41.38 Cigarettes. For...

2012-04-01

304

27 CFR 41.34 - Cigarette papers.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Cigarette papers. 41.34 Section 41...IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED... Taxes Tax Rates § 41.34 Cigarette papers. Cigarette papers...

2010-04-01

305

27 CFR 41.34 - Cigarette papers.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Cigarette papers. 41.34 Section 41...IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED... Taxes Tax Rates § 41.34 Cigarette papers. Cigarette papers...

2014-04-01

306

27 CFR 41.38 - Cigarettes.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Cigarettes. 41.38 Section 41.38 Alcohol... IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO... Classification of Large Cigars and Cigarettes § 41.38 Cigarettes. For...

2011-04-01

307

27 CFR 41.34 - Cigarette papers.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Cigarette papers. 41.34 Section 41...IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED... Taxes Tax Rates § 41.34 Cigarette papers. Cigarette papers...

2011-04-01

308

27 CFR 41.38 - Cigarettes.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Cigarettes. 41.38 Section 41.38 Alcohol... IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO... Classification of Large Cigars and Cigarettes § 41.38 Cigarettes. For...

2013-04-01

309

27 CFR 41.35 - Cigarette tubes.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Cigarette tubes. 41.35 Section 41...IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED... Taxes Tax Rates § 41.35 Cigarette tubes. Cigarette tubes...

2013-04-01

310

27 CFR 41.35 - Cigarette tubes.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2011-04-01 true Cigarette tubes. 41.35 Section 41...IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED... Taxes Tax Rates § 41.35 Cigarette tubes. Cigarette tubes...

2012-04-01

311

27 CFR 41.34 - Cigarette papers.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Cigarette papers. 41.34 Section 41...IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED... Taxes Tax Rates § 41.34 Cigarette papers. Cigarette papers...

2013-04-01

312

27 CFR 41.38 - Cigarettes.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Cigarettes. 41.38 Section 41.38 Alcohol... IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO... Classification of Large Cigars and Cigarettes § 41.38 Cigarettes. For...

2014-04-01

313

27 CFR 41.35 - Cigarette tubes.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Cigarette tubes. 41.35 Section 41...IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED... Taxes Tax Rates § 41.35 Cigarette tubes. Cigarette tubes...

2010-04-01

314

27 CFR 41.38 - Cigarettes.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Cigarettes. 41.38 Section 41.38 Alcohol... IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO... Classification of Large Cigars and Cigarettes § 41.38 Cigarettes. For...

2010-04-01

315

27 CFR 41.35 - Cigarette tubes.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Cigarette tubes. 41.35 Section 41...IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED... Taxes Tax Rates § 41.35 Cigarette tubes. Cigarette tubes...

2011-04-01

316

E-cigarettes and E-hookahs  

MedlinePLUS

... cigarette Use Linked to Conventional Cigarette Smoking Among Adolescents. http://www.cancer.org/cancer/news/e-cigarette-use-linked-to-conventional-cigarette-smoking-among-adolescents. Accessed March 28, 2014. American Cancer Society. Restrict ...

317

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

SciTech Connect

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.

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

318

TREATMENT OF PRODUCED WATERS USING A SURFACTANT MODIFIED ZEOLITE/VAPOR PHASE BIOREATOR SYSTEM  

SciTech Connect

Co-produced water from the oil and gas industry is by some estimates the largest single waste stream in the country, aside from nonhazardous industrial wastes. Characteristics of produced water include high total dissolved solids content, dissolved organic constituents such as benzene and toluene, an oil and grease component, and chemicals added during the oil-production process. While most of the produced water is disposed via reinjection, some of them must be treated to remove organic constituents before the water is discharged. An efficient, cost-effective treatment technology is needed to remove these constituents. Surfactant-modified zeolite (SMZ) has been used successfully to treat contaminated ground water for organic and inorganic constituents. In addition, the low cost of natural zeolites makes their use attractive in water-treatment applications. Our previous DOE research work (DE-AC26-99BC15221) demonstrated that SMZ could successfully remove BTEX compounds from the produced water. In addition, SMZ could be regenerated through a simple air sparging process. The primary goal of this project is to develop a robust SMZ/VPB treatment system to efficiently remove the organic constituents from produced water in a cost-effective manner. This report summarizes work of this project from March 2003 through September 2003. We have continued our investigation of SMZ regeneration from our previous DOE project. Ten saturation/stripping cycles have been completed for SMZ columns saturated with BTEX compounds. The results suggest that BTEX sorption capacity is not lost after ten saturation/regeneration cycles. The composition of produced water from a site operated by Crystal Solutions Ltd. in Wyoming has been characterized and was used to identify key semi-volatile components. Isotherms with selected semi-volatile components have been initiated and preliminary results have been obtained. The experimental vapor phase bioreactors for this project have been designed and assembled to treat the off-gas from the SMZ regeneration process. These columns will be used both in the laboratory and in the proposed field testing to be conducted next year. Innocula for the columns that degrade all of the BTEX columns have been developed.

LYNN E. KATZ; KERRY A. KINNEY; R.S. BOWMAN; E.J. SULLIVAN

2003-10-01

319

Metalorganic vapor-phase epitaxy of indium phosphide and related materials  

NASA Astrophysics Data System (ADS)

The surface chemistry of indium phosphide and related compound semiconductors during metalorganic vapor-phase epitaxy (MOVPE) has been investigated. In particular, the group V precursor chemistry, indium phosphide (001) atomic structure and the InP oxidation process have been examined. The properties of the semiconductors were studied using infrared spectroscopy, molecular cluster calculations, x-ray photoelectron spectroscopy, reflectance difference spectroscopy, x-ray diffraction, and photoluminescence spectroscopy. Indium phosphide, gallium arsenide phosphide, and aluminum indium phosphide have been deposited by MOVPE using tertiarybutylphosphine and tertiarybutylarsine. Minimum incorporation in InP was observed at 565°C and a V/III ratio of 32. In this case, the material contained a background carrier concentration of 2.7 x 1014 cm-3, and the Hall mobilities were 4,970 and 135,000 cm2/V·s at 300 and 77 K. The oxygen contamination in AlInP was found to be only 9.0 x 10 15 cm-3 for deposition at 650°C and a V/III ratio of 35. The relative distribution of arsenic to phosphorus in GaAs yP1-y was determined at temperatures between 525 and 575°C. The distribution coefficient [(NAs/ NP)film/(PTBAs /PTBP)gas] ranged from 25.4 to 8.4, and exhibited an Arrhenius relationship with an apparent activation energy of 1.2 eV. The surface structure of the indium phosphide (001)-(2 x 1) reconstruction has been clarified in this thesis. Infrared spectra collected during atomic deuterium titration of the (2 x 1) surface revealed a sharp P-H stretching mode at 2308 cm-1. Based on theoretical cluster calculations using density functional theory, this mode was due to a single hydrogen atom bonded to one end of a buckled phosphorus dimer. These results confirmed that the (2 x 1) structure was stabilized by hydrogen. Indium phosphide oxidation has been found to be an activated process and strongly structure sensitive. The In-rich (2 x 4) surface reacted with oxygen at 300 K and above. X-ray photoemission spectra revealed that the O 2 dissociatively chemisorbed onto the (2 x 4), inserting into the In-In dimer and In-P back bonds. By contrast, the P-rich (2 x 1) reconstruction did not absorb oxygen up to 5 x 105 L at 300 K. Above 455 K, oxygen reacted with the (2 x 1) inserting preferentially into the In-P back bonds and to a lesser extent into the phosphorus dimer bonds.

Chen, Gangyi

320

Metalorganic vapor phase epitaxy of II-VI compound semiconductors and diluted magnetic semiconductors  

NASA Astrophysics Data System (ADS)

II-VI compound semiconductors and diluted magnetic semiconductors (DMS) were grown in a vertical stagnation flow MOVPE reactor. The reactor was equipped with a split inlet configuration to inhibit parasitic, gas-phase prereactions. Films of ZnSe and ZnSSe were routinely deposited and characterized by standard techniques. Single-crystal line films were deposited at 666 K and 120 Torr with a growth rate of 4 m m/hr. The sources used for Zn, S, and Se were dimethylzinc triethylamine, hydrogen sulfide, and hydrogen selenide. ZnFeSe was grown for the first time in a MOVPE reactor using iron pentacarbonyl as the Fe source. The bandgap energy and surface roughness of the ZnFeSe films increased with x. ZnFeSe is a DMS with potential application in optical devices such as modulators, isolators, and switches. Doping of ZnSe was attempted using tertiary butylamine (tBNH2) as the doping source. Vapors of tBNH2 were transported to the reactor by flowing hydrogen through a liquid bubbler. Abnormal behavior of the devices constructed from the nitrogen doped ZnSe films was observed. Multilayer structures composed of alternating layers of Fe and ZnSe were investigated. The crystallinity of the structures was dependent on the initial layer. Fe films were deposited on GaAs (100) wafers at 573 K and 666 K. The films deposited at the lower temperature were more uniform. An effort to combine the techniques of evaporation and MOVPE was made. Transition metal elements for which liquid sources were not available were targeted for the purpose of creating novel DMS films. Clustering of the evaporating atoms and desorption of water from the reactor walls lead to the formation and deposition of powders. Experiments were performed to study the thickness uniformity in a multi-aperture reactor. ZnSe was deposited on Si (100) wafers. The resulting thickness variation was measured using the colored fringe patterns exhibited by the interference with light. Thickness uniformity was demonstrated over a 1 cm diameter area using a coaxial split inlet. Experiments indicated the use of a multi-aperture distributor could extend the uniformity over the entire 2" diameter wafer.

Peck, John Douglas, III

321

She smoked a cigarette : elle fumait une cigarette ou elle fuma une cigarette Prtrit simple et construction de la tlicit  

E-print Network

1 1 She smoked a cigarette : elle fumait une cigarette ou elle fuma une cigarette ? Prétérit simple a cigarette and held it in her bright red lips. When she took it out the cigarette had a pattern of fine red traduction de la phrase en italique par S. Mayoux, dans l'édition française2 : Elle fumait une cigarette qu

Paris-Sud XI, Université de

322

Theoretical approaches and experimental evidence for liquid-vapor phase transitions in nuclei  

SciTech Connect

The leptodermous approximation is applied to nuclear systems for T > 0. The introduction of surface corrections leads to anomalous caloric curves and to negative heat capacities in the liquid-gas coexistence region. Clusterization in the vapor is described by associating surface energy to clusters according to Fisher's formula. The three-dimensional Ising model, a leptodermous system par excellence, does obey rigorously Fisher's scaling up to the critical point. Multifragmentation data from several experiments including the ISiS and EOS Collaborations, as well as compound nucleus fragment emission at much lower energy follow the same scaling, thus providing the strongest evidence yet of liquid-vapor coexistence.

Moretto, L.G.; Elliott, J.B.; Phair, L.; Wozniak, G.J.; Mader, C.M.; Chappars, A.

2001-01-01

323

Computational studies of the metalorganic vapor phase epitaxy (MOVPE) of III-V compound semiconductors  

NASA Astrophysics Data System (ADS)

Although Metalorganic Vapor Phase Epitaxy (MOVPE) has emerged as the most versatile and cost-effective technique for the growth of virtually any compound semiconductor it is still hampered by the lack of ample kinetic information and by excessive experimental trial and error. Detailed reaction-transport models can help in gaining the necessary physicochemical insight and can lead to optimal reactor designs, producing uniform films and abrupt heterojunctions. Furthermore, accurate, low-order dynamic models of MOVPE are essential tools for the development of closed-loop control strategies. A kinetic model of the MOVPE of InP from trimethyl-indium and phosphine---including gas-phase and surface reactions---was constructed and coupled to a 2-dimensional transport model of the flow, heat and mass transfer in horizontal reactors. Unknown rate parameters were estimated by comparing predicted growth rates with experimental ones. A reduced kinetic mechanism able to accurately predict growth rates, with lower computational cost was extracted through sensitivity analysis and was used in parametric studies of the effects of operating conditions on film growth rates. The Low-Pressure MOVPE of GaAs from triethyl-gallium and arsine---a precursor combination that produces GaAs films with very low carbon contamination---was also studied. A kinetic model based on reported decomposition mechanisms was developed and coupled to a transport model of an experimental reactor. Finite Element (FEM) simulations were performed to estimate rate parameters of the growth reactions and to investigate the effects of surface chemistry and susceptor temperatures on film growth and uniformity. Robustness issues of reaction-transport models were addressed. The MOVPE of GaAs from trimethyl-gallium (TMG) and arsine was considered with the objective to construct reactor-independent models. A kinetic mechanism was extracted from reported kinetic studies and the frequency factor of the growth reaction was adjusted to match experimental observations from a rotating-disk (RD) reactor. The model was able to reproduce reported growth rates and uniformities from a horizontal reactor in 2- and 3-D FEM simulations, without further adjustments. A reaction-transport model of the MOVPE of GaN from TMG and ammonia in stagnation-flow and RD reactors was developed and employed in the design of axisymmetric gas inlets which feed precursors separately into the reactor to eliminate parasitic pre-reactions. FEM simulations were performed to identify designs that can lead to the growth of uniform films over large area substrates. Finally, a systematic method for order reduction of dynamic MOVPE models was demonstrated. Transients arise in MOVPE due to precursor switching during the growth of heterostructures. The Proper Orthogonal Decomposition (POD) method was employed to obtain accurate reduced models from full-scale FEM dynamic simulations of TMG dispersion in a horizontal MOVPE reactor. Reduced models can be coupled with in-situ probes of the growth and used for on-line, model-based feedback control, which is an essential step towards the realization of a Virtual MOVPE reactor.

Theodoropoulos, Constantinos

324

Physics-based agent to simulant correlations for vapor phase mass transport.  

PubMed

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

Willis, Matthew P; Varady, Mark J; Pearl, Thomas P; Fouse, Janet C; Riley, Patrick C; Mantooth, Brent A; Lalain, Teri A

2013-12-15

325

Evaluation of Catalysts from Different Origin for Vapor Phase Upgrading in Biomass Pyrolysis  

SciTech Connect

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.

Zhang, X.; Mukarakate, C.; Zheng, Z.; Nimlos, M.

2012-01-01

326

Development of vapor phase hydrogen peroxide sterilization process for spacecraft applications  

NASA Technical Reports Server (NTRS)

This paper will present test data and discussion on the work we are conducting at JPL to address the following issues: 1) efficacy of sterilization process; 2) diffusion of hydrogen peroxide under sterilization process conditions into hard to reach places; 3) materials and components compatibility with the sterilization process and 4) development of methodology to protect sensitive components from hydrogen peroxide vapor.

Rohatgi, N.; Schubert, W.; Knight, J.; Quigley, M.; Forsberg, G.; Ganapathi, G.; Yarbrough, C.; Koukol, R.

2001-01-01

327

Vapor-phase growth of transparent zinc oxide ceramics with c -axis orientation  

SciTech Connect

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.

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

328

Characterization of particulate and vapor phase polycyclic aromatic hydrocarbons in indoor and outdoor air of primary schools  

NASA Astrophysics Data System (ADS)

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.

Krugly, Edvinas; Martuzevicius, Dainius; Sidaraviciute, Ruta; Ciuzas, Darius; Prasauskas, Tadas; Kauneliene, Violeta; Stasiulaitiene, Inga; Kliucininkas, Linas

2014-01-01

329

Electronic cigarettes (E-cigarettes) are devices that deliver nicotine  

E-print Network

e490 Electronic cigarettes (E-cigarettes) are devices that deliver nicotine to a user by heating of smoking).4,5 Thus, use of electronic cigarettes to cut (Circulation. 2014;129:e490-e492.) © 2014 American is not a substitute for medical advice, and the American Heart Association recommends consultation with your doctor

Derisi, Joseph

330

PATTERNS OF CIGARETTE SMOKING. PA'ITERNS OF CIGARETTE SMOKING  

E-print Network

, increasing public awareness of the health con- sequences of smoking has resulted in significant changesPART I: PATTERNS OF CIGARETTE SMOKING. #12;PA'ITERNS OF CIGARETTE SMOKING Introduction This chapter traces the evolution of cigarette smoking among successive generations of American women and men during

Gabrieli, John

331

Bi surfactant effects on ordering in GaInP grown by organometallic vapor-phase epitaxy  

SciTech Connect

The effect of the isoelectronic surfactant Bi on surface structure and ordering has been studied for GaInP semiconductor alloys grown by organometallic vapor-phase epitaxy. A small amount of Bi (trimethylbismuth) added during growth is found to result in disordering for layers grown using conditions that would otherwise produce highly ordered materials. An order of magnitude increase in the step velocity was observed by atomic-force microscopy. Bi completely eliminates three-dimensional islands on the singular (001) surface. (c) 2000 American Institute of Physics.

Jun, S. W. [Department of Materials Science and Engineering, College of Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)] [Department of Materials Science and Engineering, College of Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Fetzer, C. M. [Department of Materials Science and Engineering, College of Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)] [Department of Materials Science and Engineering, College of Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Lee, R. T. [Department of Materials Science and Engineering, College of Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)] [Department of Materials Science and Engineering, College of Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Shurtleff, J. K. [Department of Materials Science and Engineering, College of Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)] [Department of Materials Science and Engineering, College of Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Stringfellow, G. B. [Department of Materials Science and Engineering, College of Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)] [Department of Materials Science and Engineering, College of Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)

2000-05-08

332

Photoresponse properties of large-area MoS{sub 2} atomic layer synthesized by vapor phase deposition  

SciTech Connect

Photoresponse properties of a large area MoS{sub 2} atomic layer synthesized by vapor phase deposition method without any catalyst are studied. Scanning electron microscopy, atomic force microscopy, Raman spectrum, and photoluminescence spectrum characterizations confirm that the two-dimensional microstructures of MoS{sub 2} atomic layer are of high quality. Photoelectrical results indicate that the as-prepared MoS{sub 2} devices have an excellent sensitivity and a good reproducibility as a photodetector, which is proposed to be ascribed to the potential-assisted charge separation mechanism.

Luo, Siwei; Qi, Xiang, E-mail: xqi@xtu.edu.cn, E-mail: jxzhong@xtu.edu.cn; Ren, Long; Hao, Guolin; Fan, Yinping; Liu, Yundan; Han, Weijia; Zang, Chen; Li, Jun; Zhong, Jianxin, E-mail: xqi@xtu.edu.cn, E-mail: jxzhong@xtu.edu.cn [Hunan Key Laboratory for Micro-Nano Energy Materials and Devices, People's Republic of China Laboratory for Quantum Engineering and Micro-Nano Energy Technology, and Faculty of Materials and Optoelectronic Physics, Xiangtan University, Hunan 411105 (China)

2014-10-28

333

Wide bandwidth AlAs/AlGaAs tandem Bragg reflectors grown by organometallic vapor phase epitaxy  

NASA Astrophysics Data System (ADS)

Wide bandwidth AlAs/Al0.6Ga0.4As tandem Bragg reflectors were grown by organometallic vapor phase epitaxy. Quarter-wave reflector stacks designed for different wavelengths were placed in cascade in epitaxially grown structures to expand the high reflectance bands. Intermediate low-index layers were put in between every two stacks to suppress the transmission peaks in the centers of the combined high reflectance bands. While a single-stack structure showed a full width half-maximum bandwidth of 500 Å, the two-stack and the three-stack structures effectively doubled and tripled this bandwidth to approximately 1000 and 1500 Å, respectively.

Lee, W. I.

1995-12-01

334

Characterization of the Nonpolar GaN Substrate Obtained by Multistep Regrowth by Hydride Vapor Phase Epitaxy  

NASA Astrophysics Data System (ADS)

One of the most promising methods of obtaining nonpolar GaN substrates is regrowth of thick GaN crystals using hydride vapor phase epitaxy (HVPE). The multistep growth was performed along the c polar direction. After HVPE depositions, the crystal was sliced along (1120) nonpolar planes. On such samples, we performed structural high-resolution X-ray characterization. The full width at half maximum of the X-ray rocking curves for the 1120 reflection achieved 27 arcsec. The interfaces between each regrowth step were clearly visible in cathodoluminescence (CL), due to different concentrations of residual dopants before and after a regrowth step.

Teisseyre, Henryk; Zbigniew Domagala, Jaroslaw; Lucznik, Boleslaw; Reszka, Anna; Jerzy Kowalski, Bogdan; Bockowski, Michal; Kamler, Grzegorz; Grzegory, Izabella

2012-01-01

335

Identification of vapor-phase chemical warfare agent simulants and rocket fuels using laser-induced breakdown spectroscopy  

SciTech Connect

Application of laser-induced breakdown spectroscopy (LIBS) to the identification of security threats is a growing area of research. This work presents LIBS spectra of vapor-phase chemical warfare agent simulants and typical rocket fuels. A large dataset of spectra was acquired using a variety of gas mixtures and background pressures and processed using partial least squares analysis. The five compounds studied were identified with a 99% success rate by the best method. The temporal behavior of the emission lines as a function of chamber pressure and gas mixture was also investigated, revealing some interesting trends that merit further study.

Stearns, Jaime A.; McElman, Sarah E.; Dodd, James A.

2010-05-01

336

Dioxins in cigarette smoke  

SciTech Connect

Dioxins in cigarettes, smoke, and ash were determined using gas chromatography/mass spectrometry. The total concentration of polychlorinated dibenzo-p-dioxins (PCDDs) in cigarette smoke was approximately 5.0 micrograms/m3 at the maximum level, whereas various congeners from tetra-octa-chlorodibenzo-p-dioxin (-CDD) were detected. Particullary, the total concentration of hepta-CDD congeners was the highest among these congeners. Mass fragmentograms of various PCDD congeners were similar to those in flue gas samples collected from a municipal waste incinerator. The PCDD congeners that were not present in the cigarettes were found in the smoke samples. The 2,3,7,8-TCDD toxic equivalent value--an index for effects on humans--for total PCDDs in smoke was 1.81 ng/m3 using the toxic factor of the United States Environment Protection Agency. Daily intake of PCDDs by smoking 20 cigarettes was estimated to be approximately 4.3 pg.kg body weight/day. This value was close to that of the ADIs: 1-5 pg.kg body weight/day reported in several countries. A heretofore unrecognized health risk was represented by the presence of PCDDs in cigarette smoke.

Muto, H.; Takizawa, Y.

1989-05-01

337

Vapor-liquid phase equilibria of water modelled by a Kim-Gordon potential  

SciTech Connect

Gibbs ensemble Monte Carlo simulations were carried out to investigate the properties of a frozen-electron-density (or Kim-Gordon, KG) model of water along the vapor-liquid coexistence curve. Because of its theoretical basis, such a KG model provides for seamless coupling to Kohn-Sham density functional theory for use in mixed quantum mechanics/molecular mechanics (QM/MM) implementations. The Gibbs ensemble simulations indicate rather limited transferability of such a simple KG model to other state points. Specifically, a KG model that was parameterized by Barker and Sprik to the properties of liquid water at 300 K, yields saturated vapor pressures and a critical temperature that are significantly under- and over-estimated, respectively.

Maerzke, K A; McGrath, M J; Kuo, I W; Tabacchi, G; Siepmann, J I; Mundy, C J

2009-03-16

338

Two-phase pressure drop during CO 2 vaporization in horizontal smooth minichannels  

Microsoft Academic Search

Pressure drop experiments for a natural refrigerant vaporization of CO2 were performed in horizontal minichannels. The test section was made of stainless steel tubes with inner diameters of 1.5mm and 3.0mm and with lengths of 2000 and 3000mm. This test section was uniformly heated by applying electric current directly to the tubes. Experiments were performed at inlet saturation temperatures of

A. S. Pamitran; Kwang-Il Choi; Jong-Taek Oh; Hoo-Kyu Oh

2008-01-01

339

Determination of Methane Hydrate Solubility in the Absence of Vapor Phase by in-situ Raman Spectroscopy  

NASA Astrophysics Data System (ADS)

Prediction of the occurrence, distribution, and evolution of methane hydrate in porous marine sediments requires information on solubilities of methane hydrate in water. Solubilities of methane hydrate in the presence of a vapor phase are well established, but those in the absence of a vapor phase are not well defined with differences up to 30%. We have measured methane concentrations in pure water in equilibrium with sI methane hydrate, in the absence of vapor phase, by in-situ Raman spectroscopy at temperatures (T) from 2 to 20 (± 0.3) °C and pressures (P) at 10, 20, 30, and 40 (± 0.4%) MPa. Methane hydrate was synthesized in a high-pressure capillary optical cell (Chou et al., 2005; Advances in High-Pressure Technology for Geophysical Applications. Ed. J. Chen et al., Chapter 24, p. 475, Elsevier). A small quantity of methane was first loaded in an evacuated cell and then pressurized by water. Hydrate crystals were formed near the liquid-vapor interface near the enclosed end of the optical tube at room T, and were then placed at the center of a USGS-type heating-cooling stage. By adjusting sample P and T, the crystals went through dissolution-formation cycles three to four times in three days until the vapor phase was completely consumed and several crystals (typically 40 x 40 x 10 ?m) were formed. These crystals were located at about 200 ?m from the enclosed end and were about 20 to 40 ?m from each other. Raman spectra were collected for the liquid phase adjacent to hydrate crystals near the enclosed end of the tube. A volumetric decrease in crystal size was observed away from the sampling spot; however, no such volumetric decrease was observed in or near the sampling spot. Therefore, equilibrium was likely established locally within the sampling area. The results are represented by the following linear isobaric equations: 10 MPa: ln [X(CH4)] = 0.06175 T - 6.79507; r2 = 0.9991 (n = 6) 20 MPa: ln [X(CH4)] = 0.06170 T - 6.82816; r2 = 0.9985 (n = 6) 30 MPa: ln [X(CH4)] = 0.06186 T - 6.87463; r2 = 0.9971 (n = 10) 40 MPa: ln [X(CH4)] = 0.06147 T - 6.95384; r2 = 0.9983 (n = 22), where X(CH4) is the mole fraction of CH4 in solution and n is the number of observations. These results are in good agreement with measurements by Servio and Englezos (2002, J. Chem. Eng. Data., 47, p. 87) and Kim et al. (2003, Ind. Eng. Chem. Res., 42, p. 2409) and predictions by Glew et al. (2003, Can. J. of Chem., 81, p.1443). However, our solubilities are about 10 to 30% higher than those measured by Yang et al. (2001, Fluid Phase Equilibria, 185, p. 53) and those predicted by Davie et al. (2004, Marine Geol., 203, p. 177) and Zhang and Xu (2003, Earth and Planet. Sci. Lett., 213, p. 133). It should be noted that our solubilities are minimum values if an equilibrium state was not reached during our measurements. When compared with previous direct sampling method, the advantages of our method include: (1) the use of in-situ Raman signals for methane concentration measurements eliminates possible uncertainty caused by pressure drops during sampling; (2) simple and efficient; and (3) high-pressure data can be obtained without safety concern.

Lu, W.; Chou, I.; Burruss, R.

2006-12-01

340

Biological vapor-phase treatment using biofilter and biotrickling filter reactors: Practical operating regimes  

SciTech Connect

The biological treatment of volatile organic compounds (VOCs) and air toxics has received increased attention in recent years. Biotreatment of airborne contaminants offers an inexpensive alternative to conventional air treatment technologies such as carbon adsorption and incineration. Most biological air treatment technologies commercially available are fixed-film systems that rely on growth of a biofilm layer on an inert organic support such as compost or peat (biofilters), or an inorganic support such as ceramic or plastic (biotrickling filters). If designed properly, these systems combine the advantages of high biomass concentration with high specific surface area for mass transfer. At economically viable vapor residence times (1 to 1.5 minutes), biofilters can be used for treating vapor streams containing up to approximately 1500 [mu]g/L of readily biodegradable compounds. Biotrickling filters may offer greater performance than biofilters at high contaminant loadings, possibly due to higher internal biomass concentrations. Both systems are best suited for treating vapor streams containing one or two major compounds. If designed properly, biofilters are especially well suited for treating streams that vary in concentration from minute to minute. 11 refs., 8 figs.

Togna, A.P.; Singh, M. (Envirogen, Inc., Lawrenceville, NJ (United States))

1994-05-01

341

Molecularly imprinted polymer sensors for detection in the gas, liquid, and vapor phase.  

PubMed

Fast, reliable, and inexpensive analytical techniques for detection of airborne chemical warfare agents are desperately needed. Recent advances in the field of molecularly imprinted polymers have created synthetic nanomaterials that can sensitively and selectively detect these materials in aqueous environments, but thus far, they have not been demonstrated to work for detection of vapors. The imprinted polymers function by mimicking the function of biological receptors. They can provide high sensitivity and selectivity but, unlike their biological counterparts, maintain excellent thermal and mechanical stability. The traditional imprinted polymer approach is further enhanced in this work by the addition of a luminescent europium that has been introduced into the polymers to provide enhanced chemical affinity as well as a method for signal transduction to indicate the binding event. The europium in these polymers is so sensitive to the bound target; it can distinguish between species differing by a single methyl group. The imprinted polymer technology is fiber optic-based making it inexpensive and easily integratable with commercially available miniature fiber optic spectrometer technologies to provide a shoebox size device. In this work, we will describe efforts to apply these sensors for detection of airborne materials and vapors. Successful application of this technology will provide accurate low level vapor detection of chemical agents or pesticides with little to no false positives. PMID:22641530

Jenkins, Amanda L; Ellzy, Michael W; Buettner, Leonard C

2012-06-01

342

CCMR: Conductivity Optimization of Poly(3,4-ethylenedioxythiophene): Tosylate Films Fabricated via Vapor Phase Polymerization for Use in Organic Light-Emitting Diodes (OLEDs)  

NSDL National Science Digital Library

A new conductive polymer, Poly(3,4-ethylenedioxythiophene) (PEDOT) was studied for application in organic light-emitting diodes (OLEDs). Thin film coating of PEDOT was applied through vapor-phase polymerization of 3,4-ethylenedioxythiophene (EDOT) on glass slide substrates coated with Fe (III): Tosylate. Polymerization temperature was optimized to be 30ºC, and the absence of ambient water vapor during polymerization was found to have negative effects on the conductivity. While the conductivity of PEDOT: Tosylate films were not optimized, insight was gained on how water vapor and rate of polymerization affect the overall conductivity of these films.

Newsky, Sarah E.

2009-08-15

343

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

PubMed Central

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

Grana, Rachel A.; Ling, Pamela M.

2014-01-01

344

Vapor-phase and particulate-associated pesticides and PCB concentrations in eastern North Dakota air samples  

SciTech Connect

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.

Hawthorne, S.B.; Miller, D.J.; Louie, P.K.K. [Univ. of North Dakota, Grand Forks, ND (United States)] [and others

1996-05-01

345

Investigation of cracks in GaN films grown by combined hydride and metal organic vapor-phase epitaxial method  

PubMed Central

Cracks appeared in GaN epitaxial layers which were grown by a novel method combining metal organic vapor-phase epitaxy (MOCVD) and hydride vapor-phase epitaxy (HVPE) in one chamber. The origin of cracks in a 22-?m thick GaN film was fully investigated by high-resolution X-ray diffraction (XRD), micro-Raman spectra, and scanning electron microscopy (SEM). Many cracks under the surface were first observed by SEM after etching for 10 min. By investigating the cross section of the sample with high-resolution micro-Raman spectra, the distribution of the stress along the depth was determined. From the interface of the film/substrate to the top surface of the film, several turnings were found. A large compressive stress existed at the interface. The stress went down as the detecting area was moved up from the interface to the overlayer, and it was maintained at a large value for a long depth area. Then it went down again, and it finally increased near the top surface. The cross-section of the film was observed after cleaving and etching for 2 min. It was found that the crystal quality of the healed part was nearly the same as the uncracked region. This indicated that cracking occurred in the growth, when the tensile stress accumulated and reached the critical value. Moreover, the cracks would heal because of high lateral growth rate. PMID:21711601

2011-01-01

346

A vapor phase hydrothermal modification method converting a honeycomb structured hybrid film into photoactive TiO2 film.  

PubMed

Transforming an organic/inorganic hybrid material into a pure inorganic material without losing its original structure is of interest for a range of applications. In this work, a simple and effective vapor phase hydrothermal method was developed to transform a 3D honeycomb structured PS/TTIP hybrid film into a photoactive TiO2 film without dismantling the originally templated 3D structure. The method utilizes the vapor phase hydrothermal process to create titania network/clusters with sufficient mechanical strength via the formation of Ti-oxo bridges. The organic components of the sample can be removed by means of pyrolysis while perfectly maintaining the original 3D honeycomb structure. The resultant film can be directly used for photocatalysis applications and could be further modified for other applications. In principle, this method can be used to preserve 3D structures of other organic/inorganic hybrid films during their conversion to pure inorganic films via a pyrolysis process, if mechanically strong networks can be formed as a result of hydrolysis reactions. The ability to preserve the preferred 3D structure during the subsequent conversion processes enables realization of the full benefit of unique architectures created by a templating method. PMID:19496571

Zhao, Huijun; Shen, Yanming; Zhang, Shanqing; Zhang, Haimin

2009-09-15

347

Phase-graded deposition of diamond-like carbon on nanotips by near-field induced chemical vapor deposition  

NASA Astrophysics Data System (ADS)

Diamond-like carbon (DLC) films were deposited on tungsten (W) tips under the KrF excimer laser in a laser chemical vapor deposition (LCVD) chamber. Raman spectroscopy showed that the deposited DLC films were phase-graded along the tips from the apexes. The DLC films were more diamondlike at or near the tip apexes. From numerical simulation, there is a strongly confined and enhanced optical field at the tip apexes. The simulation also indicates that there is an optical-field gradient from tip apexes to tip bodies. Therefore, the variations in the phases of deposited DLC films were attributed to the corresponding variations in local optical intensities along the tips. Hence, optical local near field was confirmed to be responsible to the DLC deposition.

Shi, J.; Lu, Y. F.; Chen, X. Y.; Cherukuri, R. S.; Mendu, K. K.; Wang, H.; Batta, N.

2005-03-01

348

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)

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.

Gokoglu, Suleyman A.

1988-01-01

349

Surface acoustic waves in semi-insulating Fe-doped GaN films grown by hydride vapor phase epitaxy  

NASA Astrophysics Data System (ADS)

The propagation properties of surface acoustic waves (SAWs) in semi-insulating Fe-doped GaN films grown on sapphire substrates by hydride vapor phase epitaxy are investigated. Compared with native n-type GaN, Fe-doped GaN exhibits a higher electromechanical coupling coefficient due to its high electrical resistivity. In addition, guided longitudinal leaky surface acoustic wave (LLSAW) was observed experimentally with a very high phase velocity (about 7890 m/s), and this mode was verified by numerical simulations. The small propagation attenuation of LLSAW along liquid/solid interfaces was demonstrated in glycerol solutions, which implies the potential applications in high-frequency chemical sensing.

Fan, Yingmin; Liu, Zhenghui; Xu, Gengzhao; Zhong, Haijian; Huang, Zengli; Zhang, Yumin; Wang, Jianfeng; Xu, Ke

2014-08-01

350

Vapor phase exsolution as a controlling factor in hydrogen isotope variation in granitic rocks: the Notch Peak granitic stock, Utah  

USGS Publications Warehouse

The Notch Peak granitic stock, western Utah, is comprised of three concentric sequentially intruded rock types, from granite at the rim, to quartz monzonite I, to quartz monzonite II at the core. The ??18O values of whole rocks vary about an average of 9.4 (SMOW), irrespective of the rock type and position relative to contact, suggesting that the three magmas had the same parent. The whole rock ??D values in the stock range from -100 to -55. ??D values increase toward the cores of both quartz monzonite I and quartz monzonite II, resulting in concentric contours. The ??D contours of quartz monzonite II cross-cut those of quartz monzonite I, suggesting little isotopic interaction between these bodies and the absence of a late pervasive fluid phase. There is a positive correlation between ??D values and water content of the samples, where samples from each body define a distinct field. The positive correlation is explained by isotopic fractionation attendant on vapor exsolution from the crystallizing magma. An observed increase in ??D with the degree of chloritization, a trend opposite to that observed in systems where participation of meteoric water has been demonstrated, is the result of subsolidus interaction with the exsolved fluids. These results show that large variations in the hydrogen isotope ratios of a granitoid can arise by exsolution of a vapor phase from the melt on crystallization. In general, magmas with larger modal amount of primary hydrous phases will tend to have higher ??D values than those with small amounts of hydrous phases. Furthermore, the relatively high ??D values of chlorites at Notch Peak confirm the applicability of classical concepts of closed-system deuteric alteration to some granitoid bodies. Thus, meteoric water interaction need not be always invoked to explain hydrogen isotope variation and deuteric alteration in granitoids. ?? 1983.

Nabelek, P.I.; O'Neil, J.R.; Papike, J.J.

1983-01-01

351

Real-Time Optical Monitoring and Simulations of Gas Phase Kinetics in InN Vapor Phase Epitaxy at High Pressure  

NASA Technical Reports Server (NTRS)

Understanding the kinetics of nucleation and coalescence of heteroepitaxial thin films is a crucial step in controlling a chemical vapor deposition process, since it defines the perfection of the heteroepitaxial film both in terms of extended defect formation and chemical integrity of the interface. The initial nucleation process also defines the film quality during the later stages of film growth. The growth of emerging new materials heterostructures such as InN or In-rich Ga(x)In(1-x)N require deposition methods operating at higher vapor densities due to the high thermal decomposition pressure in these materials. High nitrogen pressure has been demonstrated to suppress thermal decomposition of InN, but has not been applied yet in chemical vapor deposition or etching experiments. Because of the difficulty with maintaining stochiometry at elevated temperature, current knowledge regarding thermodynamic data for InN, e.g., its melting point, temperature-dependent heat capacity, heat and entropy of formation are known with far less accuracy than for InP, InAs and InSb. Also, no information exists regarding the partial pressures of nitrogen and phosphorus along the liquidus surfaces of mixed-anion alloys of InN, of which the InN(x)P(1-x) system is the most interesting option. A miscibility gap is expected for InN(x)P(1-x) pseudobinary solidus compositions, but its extent is not established at this point by experimental studies under near equilibrium conditions. The extension of chemical vapor deposition to elevated pressure is also necessary for retaining stoichiometric single phase surface composition for materials that are characterized by large thermal decomposition pressures at optimum processing temperatures.

Dietz, Nikolaus; Woods, Vincent; McCall, Sonya D.; Bachmann, Klaus J.

2003-01-01

352

[Electronic cigarette: Reliable and efficient?].  

PubMed

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

Dautzenberg, Bertrand; Dautzenberg, Marie-Dominique

2014-01-01

353

E-Cigarettes  

MedlinePLUS

... problems it can cause is to never start smoking or vaping. While kids and teens often don't consider how their current behaviors can affect their future health, it's important to ... of smoking regular cigarettes more closely than other quitting options. ...

354

Laboratory studies of silicon vapor deposition, phase A. [feasibility of producing thin films for photovoltaic applications  

NASA Technical Reports Server (NTRS)

A system is described capable of carrying out silicon vapor deposition experiments in the low 10 to the minus 10th power torr vacuum range. The system was assembled and tested for use in a program aimed at exploration of vacuum heteroepitaxy of silicon on several substrates of potential interest for photovoltaic applications. An experiment is described in which a silicon layer 2.5 microns thick was deposited on a pyrolytically cleaned tungsten substrate held at a temperature of 400 C. Using a resistance heated silicon source, thicker layers can be deposited in periods of hours by utilizing closer source to substrate distances.

Frost, R. T.; Racette, G. W.; Stockhoff, E. H.

1977-01-01

355

Development of a polysilicon process based on chemical vapor deposition, phase 1  

NASA Technical Reports Server (NTRS)

The goal of this program is to demonstrate that a dichlorosilane-based reductive chemical vapor deposition (CVD) process is capable of producing, at low cost, high quality polycrystalline silicon. Physical form and purity of this material will be consistent with LSA material requirements for use in the manufacture of high efficiency solar cells. Four polysilicon deposition runs were completed in an intermediate size reactor using dichlorosilane fed from 250 pound cylinders. Results from the intermediate size reactor are consistent with those obtained earlier with a small experimental reactor. Modifications of two intermediate size reactors were completed to interface with the dichlorosilane process demonstration unit (PDU).

Plahutnik, F.; Arvidson, A.; Sawyer, D.

1982-01-01

356

Vapor-liquid phase equilibrium in systems with multiple chemical reactions  

Microsoft Academic Search

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

Sophie Ung; Michael F. Doherty

1995-01-01

357

Geographic patterns of cigarette butt waste in the urban environment  

Microsoft Academic Search

BackgroundThis reports the initial phase of a study to quantify the spatial pattern of cigarette butt waste in an urban environment.MethodsGeographic Information Systems (GIS) was used to create a weighted overlay analysis model which was then applied to the locations of businesses where cigarettes are sold or are likely to be consumed and venues where higher concentrations of butts may

Maacah Marah; Thomas E Novotny

2011-01-01

358

Vapor Phase Infrared Spectroscopy and Ab Initio Fundamental Anharmonic Frequencies of Ammonia Borane  

SciTech Connect

Infrared absorption spectra of ammonia borane vapor have been recorded between 3600 and 600 cm-1. Of the eleven infrared active modes, seven of the vibrational modes of NH3 11BH3 have been observed and four of the vibrational modes of NH3 10BH3 were observed. The spectra were recorded with sufficient resolution to observe the rotational structure of the bands, which allowed for preliminary least squares fitting of the band origins and rotational constants. First principals electronic structure calculations were performed to obtain anharmonic band origins and their intensities. The band assignments are discussed in relation to other spectroscopic techniques that have been used to study this molecule. A semi empirical estimate of the vapor pressure of ammonia borane at room temperature (22 °C) was made and found to be ~ 1 × 10-4 Torr. The assignment of the measured modes was aided by the calculated anharmonic frequencies and their infrared intensities. The combination of the CCSD(T) harmonic frequencies with the B3LYP anharmonicities, obtained from second order vibrational perturbation theory, was found to produce an overall best agreement with the measured band origins.

Sams, R. L.; Xantheas, Sotiris S.; Blake, Thomas A.

2012-03-29

359

Coumarins in the gaseous phase. III. Coumarin 6 vapor laser with 12% efficiency  

SciTech Connect

Lasing of coumarin 6 (C6) vapor mixed with diethyl ether (tauapprox.210 /sup 0/C) was observed in the range of 520 nm for transverse pumping with the third harmonic of a neodymium laser (355 nm, 20 nsec, 100 mJ). The dependence of the lasing efficiency on the transmission of the resonator mirrors was used to estimate the internal losses (0.02--0.03 cm/sup -1/) and the gain in the active medium. The amplification cross section of C6 in the 520 nm range was 3.5 x 10/sup -17/ cm/sup 2/. At the beginning of a pump pulse the lasing efficiency in the optimal resonator was 15% (and the corresponding quantum efficiency was 22%), but at the end of the pulse it fell to 10%. A study was made of the mechanisms of the induced losses. The observed fall of the efficiency was mainly due to an increase in the induced absorption and the pump wavelength. Feasibility of constructing a cw C6 vapor laser was considered.

Logunov, O.A.; Startsev, A.V.; Stoilov, Y.Y.

1982-06-01

360

Phase control of GaN on Si by nanoscale faceting in metalorganic vapor-phase epitaxy  

Microsoft Academic Search

Phase stability of GaN on (111)–(001) nanoscale faceted Si is investigated. Nanoscale faceting (nanofaceting) is accomplished on a Si(001) substrate with interferometric lithography and anisotropic wet etching. By relying on the nucleation and associated lateral growth depending on orientation and crystal structure, spatial separation of a cubic-phase region from hexagonal-phase GaN regions which initiate on the facing Si(111) sidewalls of

S. C. Lee; X. Y. Sun; S. D. Hersee; S. R. J. Brueck

2004-01-01

361

Cigarette smoke inhibition of ion transport in canine tracheal epithelium  

SciTech Connect

To determine the effect of cigarette smoke on airway epithelial ion transport, the electrical properties and transepithelial Na and Cl fluxes were measured in canine tracheal epithelium. In vivo, the inhalation of the smoke from one cigarette acutely and reversibly decreased the electrical potential difference across the tracheal epithelium. In vitro, exposure of the mucosal surface of the epithelium to cigarette smoke decreased the short circuit current and transepithelial resistance. The decrease in short circuit current was due to an inhibition of the rate of Cl secretion with minimal effect on the rate of Na absorption. The effect of cigarette smoke was reversible, was not observed upon exposure of the submucosal surface to smoke, and was most pronounced when secretion was stimulated. The particulate phase of smoke was largely responsible for the inhibitory effect, since filtering the smoke minimized the effect. The effect of cigarette smoke was not prevented by addition of antioxidants to the bathing solutions, suggesting that the inhibition of Cl secretion cannot be entirely attributed to an oxidant mechanism. These results indicate that cigarette smoke acutely inhibits active ion transport by tracheal epithelium, both in vivo and in vitro. This effect may explain, in part, both the abnormal mucociliary clearance and the airway disease observed in cigarette smokers.

Welsh, M.J.

1983-06-01

362

A low phase noise microwave frequency synthesis for a high-performance cesium vapor cell atomic clock.  

PubMed

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

François, B; Calosso, C E; Danet, J M; Boudot, R

2014-09-01

363

A low phase noise microwave frequency synthesis for a high-performance cesium vapor cell atomic clock  

SciTech Connect

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{sup 2}/Hz and ?129 dB?rad{sup 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{sup ?14} at 1 s integration time, that is a factor 3 higher than the atomic clock shot noise limit. Main limitations are pointed out.

François, B.; Boudot, R. [FEMTO-ST, CNRS, Université de Franche-Comté, 26 chemin de l'Epitaphe, 25030 Besançon (France); Calosso, C. E. [INRIM, Strada delle Cacce 91, 10135 Torino (Italy); Danet, J. M. [LNE-SYRTE, Observatoire de Paris, CNRS-UPMC, 61 avenue de l'Observatoire, 75014 Paris (France)

2014-09-15

364

A low phase noise microwave frequency synthesis for a high-performance cesium vapor cell atomic clock  

NASA Astrophysics Data System (ADS)

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.

François, B.; Calosso, C. E.; Danet, J. M.; Boudot, R.

2014-09-01

365

Magnetic property variation with vapor-phase alteration in the Bishop Tuff, and implications for paleointensity studies  

NASA Astrophysics Data System (ADS)

To obtain reliable estimates of the absolute strength of the geomagnetic field, samples must contain fine-grained (single domain) particles of magnetic minerals, which are thermally stable enough to withstand the arduous measurement process. Ash flow tuffs (ignimbrites) usually fit this first requirement, but may also contain coarser grained material. Ignimbrites may have a complicated thermal and/or chemical magnetic remanence and complex magnetic mineralogies due to emplacement and post-emplacement alteration conditions. The origin and nature of their magnetic remanence must be known in order to interpret the paleointensity. We examined ignimbrites from the 0.76 Ma Bishop Tuff, collecting samples from three stratigraphic sections of the Owens' river gorge that complement two previously sampled sections. Four of the Owens' river gorge sites are within the zone of vapor-phase alteration, three of which are in the zone of fumarolic mounds, but not associated with any specific fumaroles. Within each section there is a range in degree of welding, and between sections there were variations in emplacement and post-emplacement conditions. Previous ?18O studies show ?18O varies considerably with depth within the fumarole zone, where values are dramatically depleted due to meteoric-hydrothermal alteration; however, more densely welded material lower in the same sections did not experience alteration because of their lower permeability. We therefore made an evaluation of the effects of vapor-phase alteration on the ignimbrite's magnetization. We observe a significant decrease in magnetic susceptibility in two sections within the fumarole zone with a sharp increase in the densely welded tuff, which corroborates the ?18O evidence. Hysteresis loops also show the effect of the vapor-phase alteration on the magnetic mineralogy. Coincident with the decrease in susceptibility, at least, one section has wasp-waisted hysteresis loops indicating two coercivity fractions. The high-coercivity fraction is thought to be titanohematite resulting from the alteration process. These effects seem to be spatially heterogeneous however; the decrease in susceptibility and distorted hysteresis loops are not observed at all of the sections within the fumarole zone. Previous work suggest that despite its complex alteration the Bishop Tuff gives an internally consistent estimate of the paleofield; modified Thellier-Thellier experiments are underway to investigate this further. Ignimbrites are globally abundant and many are well dated making them possibly valuable sources of much needed absolute paleointensity information.

Avery, M. S.; Gee, J. S.; Bowles, J. A.; Jackson, M. J.

2012-12-01

366

Growth and Characterization of ZnO, SnO 2 and ZnO\\/SnO 2 Nanostructures from the Vapor Phase  

Microsoft Academic Search

Zinc oxide (ZnO), tin dioxide (SnO2) and compounds ZnO\\/SnO2 (ZTO) nanostructures have been synthesized successfully from the vapor phase without a catalyst using three different approaches.\\u000a XRD analyses showed that ZnO with a wurtzite crystal structure, SnO2 with a rutile crystal structure and zinc stannate (ZnSnO3) and\\/or dizinc stannate (Zn2SnO4) were condensed from the vapor phase when Zn and\\/or Sn

O. A. Fouad; G. Glaspell; M. S. El-Shall

2008-01-01

367

Absolute integrated intensities of vapor-phase hydrogen peroxide (H202) in the mid-infrared at atmospheric pressure  

SciTech Connect

We report quantitative broadband infrared spectra of vapor-phase hydrogen peroxide (H2O2) with all spectra pressure broadened to atmospheric pressure. The spectra were generated by flowing a concentrated solution (83 weight%) of H2O2 into a gently heated disseminator and diluting with a flow of pure nitrogen carrier gas. The water vapor lines were subtracted from the resulting spectra to yield the spectrum of pure H2O2. Comparison with previous results for the ?6 band strength (including hot bands) compares favorably with the results of Klee et al. [(1999) J. Mol. Spectr. 195, 154] as well as HITRAN. The present results are 433 and 467 cm-2 atm-1 (±8% and ±3% at 298 and 323 K, respectively) for the band strength, matching well the Klee value (S = 467 cm-2 atm-1 at 296 K) for the integrated band. Other bands in the 520-7500 cm-1 interval and their potential for atmospheric monitoring are discussed.

Johnson, Timothy J.; Sams, Robert L.; Burton, Sarah D.; Blake, Thomas A.

2009-09-01

368

The Validation of Vapor Phase Hydrogen Peroxide Microbial Reduction for Planetary Protection and a Proposed Vacuum Process Specification  

NASA Technical Reports Server (NTRS)

The Jet Propulsion Laboratory, in conjunction with the NASA Planetary Protection Officer, has selected the vapor phase hydrogen peroxide sterilization process for continued development as a NASA approved sterilization technique for spacecraft subsystems and systems. The goal is to include this technique, with an appropriate specification, in NPR 8020.12C as a low temperature complementary technique to the dry heat sterilization process.To meet microbial reduction requirements for all Mars in-situ life detection and sample return missions, various planetary spacecraft subsystems will have to be exposed to a qualified sterilization process. This process could be the elevated temperature dry heat sterilization process (115 C for 40 hours) which was used to sterilize the Viking lander spacecraft. However, with utilization of such elements as highly sophisticated electronics and sensors in modern spacecraft, this process presents significant materials challenges and is thus an undesirable bioburden reduction method to design engineers. The objective of this work is to introduce vapor hydrogen peroxide (VHP) as an alternative to dry heat microbial reduction to meet planetary protection requirements.The VHP process is widely used by the medical industry to sterilize surgical instruments and biomedical devices, but high doses of VHP may degrade the performance of flight hardware, or compromise material properties. Our goal for this study was to determine the minimum VHP process conditions to achieve microbial reduction levels acceptable for planetary protection.

Chung, Shirley; Barengoltz, Jack; Kern, Roger; Koukol, Robert; Cash, Howard

2006-01-01

369

Condensed phase conversion and growth of nanorods instead of from vapor  

DOEpatents

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.

Geohegan, David B.; Seals, Roland D.; Puretzky, Alex A.; Fan, Xudong

2005-08-02

370

Electronic cigarettes: human health effects  

PubMed Central

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

Callahan-Lyon, Priscilla

2014-01-01

371

Electronic cigarette: a possible substitute for cigarette dependence.  

PubMed

Cigarette smoking is the leading cause of premature mortality in western countries and it is important for smokers to stop as early as possible. Electronic cigarettes are a popular phenomenon of global proportion. Recent uncontrolled studies, reported that a certain number of smokers have quit using electronic cigarettes. This could hint a role for electronic cigarettes to be used for smoking cessation, and therefore merits further evaluation for this purpose. Besides vaporising nicotine to be inhaled, electronic cigarettes may also provide a coping mechanism for conditioned smoking cues by replacing some of the rituals associated with smoking gestures, and for these reasons cigarette could become a tool--if studied more extensively--in the fight against tobacco-related morbidity and mortality. PMID:23741941

Caponnetto, P; Russo, C; Bruno, C M; Alamo, A; Amaradio, M D; Polosa, R

2013-03-01

372

A gas lift bioreactor for removal of contaminants from the vapor phase.  

PubMed

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 mug/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

Ensley, B D; Kurisko, P R

1994-01-01

373

A Gas Lift Bioreactor for Removal of Contaminants from the Vapor Phase  

PubMed Central

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

Ensley, B. D.; Kurisko, P. R.

1994-01-01

374

Modified halloysite nanotubes: nanoarchitectures for enhancing the capture of oils from vapor and liquid phases.  

PubMed

We prepared hybrid halloysite nanotubes (HNT/sodium alkanoates) in which the inner cavity of the nanoclay was selectively modified. Physicochemical studies evidenced the interactions between HNT and sodium alkanoates, ruled out clay exfoliation, quantified the amount of the loaded substance, and showed an increase of the total net negative charge, allowing us to obtain rather stable aqueous nanoclay dispersions. These dispersions were exploited as inorganic micelles to capture hydrocarbon and aromatic oils in the vapor and liquid states and were revealed to be nonfoaming but very efficient in encapsulating oils. Here, we have fabricated biocompatibile and low-cost inorganic micelles that can be exploited for industrial applications on a large scale. PMID:24328045

Cavallaro, Giuseppe; Lazzara, Giuseppe; Milioto, Stefana; Parisi, Filippo; Sanzillo, Vincenzo

2014-01-01

375

Vacuum distillation/vapor filtration water recovery, phases 1 and 2  

NASA Technical Reports Server (NTRS)

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.

Honegger, R. J.; Remus, G. A.; Krug, E. K.

1973-01-01

376

Development of a polysilicon process based on chemical vapor deposition (phase 1)  

NASA Technical Reports Server (NTRS)

A dichlorosilane-based reductive chemical vapor deposition (CVD) process demonstrated is capable of producing, at low cost, high quality polycrystalline silicon. Testing of decomposition reactor heat shields to insure that the shield provides adequate personnel protection assuming a worst case explosion was completed. Minor modifications to a production reactor heat shield provided adequate heat shield integrity. Construction of the redesigned PDU (Process Development Unit) to accommodate all safety related information proceeded on schedule. Structural steel work was completed as is the piping and instrumentation design work. Major pieces of process equipment were received and positioned in the support structure and all transfer piping and conduits to the PDU were installed. Construction was completed on a feed system for supplying DCS to an intermediate sized reactor. The feed system was successfully interfaced with a reactor equipped with a modified heat shield. Reactor checkout was completed.

Mccormick, J.; Arvidson, A.; Sawyer, D.; Plahutnik, F.

1981-01-01

377

Development of a polysilicon process based on chemical vapor deposition, phase 1  

NASA Technical Reports Server (NTRS)

The development of a dichlorosilane-based reductive chemical vapor deposition process for the production of polycrystalline silicon is discussed. Experimental data indicate that the ease of ignition and explosion severity of dichlorosilane (DCS)/air mixtures is substantially attenuated if the DCS is diluted with hydrogen. Redesign of the process development unit to accommodate safety related information is described. Several different sources of trichlorosilane were used to generate a mixture of redistributed chlorosilanes via Dowex ion exchange resin. The unseparated mixtures were then fed to an experimental reactor in which silicon was deposited and the deposited silicon analyzed for electrically active impurities. At least one trichlorosilane source provided material of requisite purity. Silicon grown in the experimental reactor was converted to single crystal material and solar cells fabricated and tested.

Mccormick, J.; Sharp, K.; Arvidson, A.; Sawyer, D.

1981-01-01

378

Membrane vapor recovery systems. Phase 2, Progress report, 1 October 1991--29 September 1992  

Microsoft Academic Search

This report describes Phase II of a project to design, construct, and demonstrate in the membrane separation system able to recover volatile organic compounds field a condensation\\/membrane separation system able to recover volatile organic compounds from effluent air streams. In the first phase of the program, a number of the high-pressure membrane modules to be installed in the system were

R. W. Baker; J. E. Davidson; V. D. Helm; T. R. Hofmann; H. D. Kamaruddin; J. Kaschemekat; R. P. Olsen; M. E. Rose; J. G. Wijmans

1992-01-01

379

Amorphous and crystalline aerosol particles interacting with water vapor - Part 1: Microstructure, phase transitions, hygroscopic growth and kinetic limitations  

NASA Astrophysics Data System (ADS)

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.

Mikhailov, E.; Vlasenko, S.; Martin, S. T.; Koop, T.; Pöschl, U.

2009-03-01

380

Diffuse diffracted features and ordered domain structures in GaInP layers grown by organometallic vapor phase epitaxy  

SciTech Connect

Transmission electron diffraction (TED) and transmission electron microscope (TEM) studies have been made of organometallic vapor phase epitaxial Ga{sub x}In{sub 1{minus}x}P layers (x {approx} 0.5) grown at temperatures in the range 570--690 C to investigate ordering and ordered domain structures. TED and TEM examination shows that the size and morphology of ordered domains depend on the growth temperature. The ordered domains change from a fine rod-like shape to a plate-like shape as the growth temperature increases. The domains are of width 0.6--2 nm and of length 1{approximately}10 nm. Characteristic diffuse features observed in TED patterns are found to depend on the growth temperature. Extensive computer simulations show a direct correlation between the ordered domain structures and such diffuse features. A possible model is suggested to describe the temperature dependence of the ordered domain structure.

Yang, J.J.; Spirydon, R.; Seong, T.Y. [Kwangju Inst. of Science and Technology (Korea, Republic of). Dept. of Materials Science and Engineering; Lee, S.H.; Stringfellow, G.B. [Univ. of Utah, Salt Lake City, UT (United States). Dept. of Materials Science and Engineering

1998-10-01

381

Chemical reactions on the surface of dispersed silica during gas-phase modification with MoCl{sub 5} vapors  

SciTech Connect

The characteristic features of the gas-phase modification of silica by molybdenum pentachloride vapors were investigated. The grafted molybdenum chloride groups {triple_bond}SiOMoCl{sub 4} formed as a result of the reaction of MoCl{sub 5} with the silanol groups and siloxane bridges of the SiO{sub 2} surface undergo a rearrangement as a result of their instability, forming chlorosilyl groups and molybdenum oxychloride, which is removed from the silica surface. In the presence of an excess of the modifier MoCl{sub 5}, the reaction with siloxane bridges of the surface layer leads to the formation of silicon tetrachloride and is accompanied by etching of the surface of the dispersed silica globules.

Plyuto, Yu.V.; Gomenyuk, A.A.; Babich, I.V.; Nuiko, A.A. [Institute of Surface Chemistry, Kiev (Ukraine)

1994-05-01

382

Morphological, electrical, and optical properties of InN grown by hydride vapor phase epitaxy on sapphire and template substrates  

NASA Astrophysics Data System (ADS)

We report studies of the morphological, electrical, and optical properties of InN grown by hydride vapor phase epitaxy. The layers have been grown on c-plane sapphire substrates and epitaxial GaN, Al0.7Ga0.3N, and AlN templates grown on sapphire. InN properties are found to depend on template type with improvement of crystal structure in the template substrate order AlN-->AlGaN-->GaN. X-ray studies reveal InN layers grown on template substrates to be relaxed with lattice constants a=3.542 A? and c=5.716 A?. The Raman spectra and optical gaps of the InN layers, vary with free-carrier concentration in agreement with previous studies. We obtain a value of 2.5+/-0.2 for the index of refraction of InN.

Song, D. Y.; Kuryatkov, V.; Basavaraj, M.; Rosenbladt, D.; Nikishin, S. A.; Holtz, M.; Syrkin, A. L.; Usikov, A. S.; Ivantsov, V. A.; Dmitriev, V. A.

2006-06-01

383

AlN Grown on a- and n-Plane Sapphire Substrates by Low-Pressure Hydride Vapor Phase Epitaxy  

NASA Astrophysics Data System (ADS)

We have studied the properties of AlN layers grown by low-pressure hydride vapor phase epitaxy (HVPE) on n-plane (11bar 23) sapphire substrates and compared them with those of AlN layers on a-plane (11bar 20) sapphire substrates. c-Plane AlN was grown on a-plane sapphire. In the case of AlN growth on n-plane sapphire, the c-axis of AlN was tilted by about 1.2° relative to the n-axis of sapphire, unlike AlN growth on a-plane sapphire. For AlN grown on a-plane sapphire, the in-plane epitaxial relationship between AlN and sapphire changed with nitridation temperature in the initial-stage of growth, but it remained constant for AlN grown on n-plane sapphire.

Goriki, Naoki; Miyake, Hideto; Hiramatsu, Kazumasa; Akiyama, Toru; Ito, Tomonori; Eryu, Osamu

2013-08-01

384

Examination of growth rate during hydride vapor phase epitaxy of GaN on ammonothermal GaN seeds  

NASA Astrophysics Data System (ADS)

One of the main advantages of the hydride vapor phase epitaxy (HVPE) method for crystallizing bulk gallium nitride is the crystallization of GaN with a relatively high growth rate (>100 ?m/h). In this paper various growth rates in the c-direction during crystallization of GaN by HVPE on ammonothermally grown GaN crystals are determined and examined. The influence of the highest (380 ?m/h) and the lowest (40 ?m/h) growth rate on the structural quality and purity of the HVPE-GaN crystals is analyzed. The optimal macroscopically stable growth rate (without cracks and pits) and the way of achieving it are presented and discussed.

Sochacki, T.; Amilusik, M.; Fijalkowski, M.; Lucznik, B.; Weyher, J. L.; Grzegory, I.; Kucharski, R.; Iwinska, M.; Bockowski, M.

2014-12-01

385

In situ X-ray reflectivity of indium supplied on GaN templates by metal organic vapor phase epitaxy  

NASA Astrophysics Data System (ADS)

The indium supplied on c-plane GaN templates using Metal organic vapor phase epitaxy was studied by in situ X-ray reflectivity (XRR) at 800 °C. The presence of liquid indium layers on the GaN (0001) surface was demonstrated using data-fitting of XRR measurements, ex situ atomic force microscope, auger electron spectroscopy, and cross-sectional scanning electron microscope. These measurements demonstrated that a liquid indium layer coexisted with indium droplets on top of the GaN (0001) surface at 800 °C. The liquid indium film thicknesses increased with increasing TMIn supply time and did not change during cooling from 800 °C to room temperature.

Ju, Guangxu; Fuchi, Shingo; Tabuchi, Masao; Takeda, Yoshikazu

2013-09-01

386

Hydride Vapor-Phase Epitaxy of c-Plane AlGaN Layers on Patterned Sapphire Substrates  

NASA Astrophysics Data System (ADS)

Growth of Al x Ga1- x N layers by hydride vapor-phase epitaxy on patterned sapphire substrates is investigated. The pattern consists of honeycombs which by their orientation and size promote the formation of coalesced c-plane-oriented Al x Ga1- x N layers with reduced crack density. The orientation of parasitic crystallites in the honeycomb openings is investigated using scanning electron microscopy and electron back-scatter diffraction. Crystallites with their [ .0] and [52.3] directions parallel to the vertical growth direction of the Al0.3Ga0.7N layer are observed and successfully overgrown by a 20- ?m-thick fully coalesced c-plane-oriented layer.

Richter, E.; Fleischmann, S.; Goran, D.; Hagedorn, S.; John, W.; Mogilatenko, A.; Prasai, D.; Zeimer, U.; Weyers, M.; Tränkle, G.

2014-04-01

387

Nucleation and growth of Ag nanoparticles on amorphous carbon surface from vapor phase formed by vacuum evaporation  

NASA Astrophysics Data System (ADS)

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.

Gromov, Dmitry G.; Pavlova, Lydia M.; Savitsky, Andrey I.; Trifonov, Alexey Yu.

2015-03-01

388

Formation of magnetic nanocolumns during vapor phase deposition of a metal-polymer nanocomposite: experiments and kinetic Monte Carlo simulations  

E-print Network

Metal-polymer nanocomposites have been investigated extensively during the last years due to their interesting functional applications. They are often produced by vapor phase deposition which generally leads to the self-organized formation of spherical metallic nanoparticles in the organic matrix, while nanocolumns are only obtained under very specific conditions. Experiments\\cite{Grev+06} have shown that co-evaporation of the metallic and organic components in a simple single-step process can give rise to the formation of ultrahigh-density Fe-Ni-Co nanocolumnar structures embedded in a fluoropolymer matrix. Here we present a kinetic Monte Carlo approach which is based on an new model involving the depression of the melting point on the nanoscale and a critical nanoparticle size required for solidification. In addition we present new experimental results down to a deposition temperature of \\cel{-70} and also report the magnetic properties. The simulations provide a detailed understanding of the transition fro...

Rosenthal, L; Zaporojtchenko, V; Strunskus, T; Faupel, F; Bonitz, M

2013-01-01

389

ZnO/Cu(InGa)Se2 solar cells prepared by vapor phase Zn doping  

DOEpatents

A process for making a thin film ZnO/Cu(InGa)Se2 solar cell without depositing a buffer layer and by Zn doping from a vapor phase, comprising: depositing Cu(InGa)Se2 layer on a metal back contact deposited on a glass substrate; heating the Cu(InGa)Se2 layer on the metal back contact on the glass substrate to a temperature range between about 100.degree. C. to about 250.degree. C.; subjecting the heated layer of Cu(InGa)Se2 to an evaporant species from a Zn compound; and sputter depositing ZnO on the Zn compound evaporant species treated layer of Cu(InGa)Se2.

Ramanathan, Kannan; Hasoon, Falah S.; Asher, Sarah E.; Dolan, James; Keane, James C.

2007-02-20

390

Deep-level transient spectroscopy studies of Ni- and Zn-diffused vapor-phase-epitaxy n-GaAs  

NASA Technical Reports Server (NTRS)

The paper presents deep-level transient spectroscopy studies of Ni- and Zn-diffused vapor-phase epitaxy n-GaAs. Nickel diffused into VPE n-GaAs reduces the hole diffusion length L sub p from 4.3 to 1.1 microns. Deep-level transient spectroscopy was used to identify energy levels in Ni-diffused GaAs; the as-grown VPE GaAs contains traces of these levels and an electron trap. Ni diffusion reduces the concentration of this level by an amount that matches the increase in concentration of each of the two Ni-related levels. A technique for measuring minority-carrier capture cross sections was developed, which indicates that L sub p in Ni-diffused VPE n-GaAs is controlled by the E sub c - 0.39 eV defect level.

Partin, D. L.; Chen, J. W.; Milnes, A. G.; Vassamillet, L. F.

1979-01-01

391

A model for arsenic anti-site incorporation in GaAs grown by hydride vapor phase epitaxy  

NASA Astrophysics Data System (ADS)

GaAs growth by hydride vapor phase epitaxy (HVPE) has regained interest as a potential route to low cost, high efficiency thin film photovoltaics. In order to attain the highest efficiencies, deep level defect incorporation in these materials must be understood and controlled. The arsenic anti-site defect, AsGa or EL2, is the predominant deep level defect in HVPE-grown GaAs. In the present study, the relationships between HVPE growth conditions and incorporation of EL2 in GaAs epilayers were determined. Epitaxial n-GaAs layers were grown under a wide range of deposition temperatures (TD) and gallium chloride partial pressures (PGaCl), and the EL2 concentration, [EL2], was determined by deep level transient spectroscopy. [EL2] agreed with equilibrium thermodynamic predictions in layers grown under conditions in which the growth rate, RG, was controlled by conditions near thermodynamic equilibrium. [EL2] fell below equilibrium levels when RG was controlled by surface kinetic processes, with the disparity increasing as RG decreased. The surface chemical composition during growth was determined to have a strong influence on EL2 incorporation. Under thermodynamically limited growth conditions, e.g., high TD and/or low PGaCl, the surface vacancy concentration was high and the bulk crystal was close to equilibrium with the vapor phase. Under kinetically limited growth conditions, e.g., low TD and/or high PGaCl, the surface attained a high GaCl coverage, blocking As adsorption. This competitive adsorption process reduced the growth rate and also limited the amount of arsenic that incorporated as AsGa. A defect incorporation model which accounted for the surface concentration of arsenic as a function of the growth conditions, was developed. This model was used to identify optimal growth parameters for the growth of thin films for photovoltaics, conditions in which a high growth rate and low [EL2] could be attained.

Schulte, K. L.; Kuech, T. F.

2014-12-01

392

Enhanced quality thin film Cu(In,Ga)Se.sub.2 for semiconductor device applications by vapor-phase recrystallization  

DOEpatents

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.

Tuttle, John R. (Denver, CO); Contreras, Miguel A. (Golden, CO); Noufi, Rommel (Golden, CO); Albin, David S. (Denver, CO)

1994-01-01

393

Enhanced quality thin film Cu(In,Ga)Se[sub 2] for semiconductor device applications by vapor-phase recrystallization  

DOEpatents

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.

Tuttle, J.R.; Contreras, M.A.; Noufi, R.; Albin, D.S.

1994-10-18

394

DNA typing from cigarette butts  

Microsoft Academic Search

We performed DNA typing for D1S80, HLADQA1, TH01 and PM using the butts of 100 cigarettes that were smoked by ten different individuals (ten cigarettes per individual). The results obtained from DNA typing for D1S80 agreed with the results obtained using bloodstains in 76 cigarette butt samples. Sixteen samples produced false results, showing the loss of the longer allelic hetero-band.

Yoshihisa Watanabe; Tomohiro Takayama; Keiji Hirata; Sadao Yamada; Atsushi Nagai; Isao Nakamura; Yasuo Bunai; Isao Ohya

2003-01-01

395

27 CFR 40.351 - Cigarette papers.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2011-04-01 true Cigarette papers. 40.351 Section 40.351... MANUFACTURE OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Manufacture of Cigarette Papers and Tubes Taxes §...

2012-04-01

396

27 CFR 40.352 - Cigarette tubes.  

Code of Federal Regulations, 2010 CFR

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

2010-04-01

397

27 CFR 40.352 - Cigarette tubes.  

Code of Federal Regulations, 2013 CFR

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

2013-04-01

398

27 CFR 40.352 - Cigarette tubes.  

Code of Federal Regulations, 2011 CFR

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

2011-04-01

399

27 CFR 40.351 - Cigarette papers.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Cigarette papers. 40.351 Section 40.351... MANUFACTURE OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Manufacture of Cigarette Papers and Tubes Taxes §...

2013-04-01

400

27 CFR 40.351 - Cigarette papers.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Cigarette papers. 40.351 Section 40.351... MANUFACTURE OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Manufacture of Cigarette Papers and Tubes Taxes §...

2010-04-01

401

27 CFR 40.352 - Cigarette tubes.  

Code of Federal Regulations, 2012 CFR

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

2012-04-01

402

27 CFR 40.351 - Cigarette papers.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Cigarette papers. 40.351 Section 40.351... MANUFACTURE OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Manufacture of Cigarette Papers and Tubes Taxes §...

2011-04-01

403

27 CFR 40.351 - Cigarette papers.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Cigarette papers. 40.351 Section 40.351... MANUFACTURE OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Manufacture of Cigarette Papers and Tubes Taxes §...

2014-04-01

404

27 CFR 40.352 - Cigarette tubes.  

Code of Federal Regulations, 2014 CFR

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

2014-04-01

405

Metalorganic vapor phase epitaxy growth of ternary tetradymite Bi2Te3-xSex compounds  

NASA Astrophysics Data System (ADS)

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.

Kuznetsov, P. I.; Yakushcheva, G. G.; Luzanov, V. A.; Temiryazev, A. G.; Shchamkhalova, B. S.; Jitov, V. A.; Sizov, V. E.

2015-01-01

406

MW Spectroscopy Coupled with Ultrafast UV Laser Vaporization: Succinic Acid in the Gas Phase  

NASA Astrophysics Data System (ADS)

Recent lab and field measurements have indicated critical roles of organic acids in enhancing new atmospheric aerosol formation. In order to understand the nucleation process, here we report an experimental and theoretical investigation of chemical structure of succinic acid. We have used the technique of Fourier Transform Microwave Spectroscopy (FTMW). Succinic acid was vaporized by UV ultrafast laser ablation to suppress thermal decomposition processes^a and seeded into an expanding stream of Ne forming a supersonic jet. The rotational spectrum detected the presence of a single most stable conformation in the cm- mm- wave regions for which accurate rotational and centrifugal distortion parameters have been determined. The study was extended to all monosubstituted isotopic species (^{13}C, ^{18}O, D(O)), which were positively identified, leading to an accurate determination of the effective and substitution structures of the molecule. The experimental study was supplemented by ab initio (MP2) and DFT (M06-2X and B3LYP) calculations. ^{a} E. J. Cocinero, A. Lesarri, P. écija, F. J. Basterretxea, J. U. Grabow, J. A. Fernández and F. Castaño, Angew. Chem. Int. Ed., 51, 3119-3124, 2012.

Mendez, Estibaliz; Ecija, Patricia; Cocinero, Emilio J.; Castano, Fernando; Basterretxea, Francisco J.; Godfrey, Peter D.; McNaughton, Don; Jahn, Michaela K.; Nair, K. P. Rajappan; Grabow, Jens-Uwe

2013-06-01

407

The formation of PdCx over Pd-based catalysts in vapor-phase vinyl acetate synthesis: does a PdAu alloy catalyst resist carbide formation?  

E-print Network

The formation of PdCx over Pd-based catalysts in vapor-phase vinyl acetate synthesis: does a Pd­Au alloy catalyst resist carbide formation? Y.-F. Han, D. Kumar, C. Sivadinarayana, A. Clearfield, and D acetate (VA) was investigated over Pd/SiO2 catalysts with two different Pd particle sizes, as well as over

Goodman, Wayne

408

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...

409

Bulk Property Modification of Fiber Forming Polymers using Vapor Phase Techniques  

NASA Astrophysics Data System (ADS)

Atomic layer deposition provides the opportunity to introduce nanoscale inorganic coatings to organic polymers creating coatings with varied compositions of finish and distinctive interfaces. Prior research has shown that ALD materials nucleation on polymers varies in composition and structure based on how the precursor interacts with the polymer chemistry and the process conditions. To study this in more detail, in-situ quartz crystal microgravimetry is employed to understand the infiltration and saturation behavior of trimethyl aluminum in polymer thin films. Emphasis is placed on understanding reactive vapor diffusion into polymers as the exposure temperature is varied. Potential growth mechanisms based on the temperature dependent observations in this work are proposed which leads to the understanding of hybrid organic-inorganic formation in polymers. Furthermore, polymers which have subtle variations in microstructure are explored to elucidate the nucleation behavior of inorganic coatings on polymers in more detail. Specifically, in-situ quartz crystal microgravimetry is employed to understand the nucleation behavior of alumina ALD in a series of poly-n-methacrylate and polyester thin films. The work indicates the effect that a subtle change in polymer microstructure has on the properties of the polymer film and the resultant absorption/desorption characteristics during TMA/water exposures. The effect of % crystallinity on the infiltration mechanism is also investigated in polymer films with varied crystallinities. Finally, the effect of the hybrid modification on the mechanical behavior of fibrous materials is also explored. In particular this dissertation highlights the process-property relationships between modified and unmodified fibers infiltrated with TMA. The results indicate that the peak load and elongation of the fibers increase with exposure to TMA. Therefore, this work has important implications on high impact applications as well as the introduction of inorganic material properties to flexible polymer systems.

Padbury, Richard Paul

410

Vapor-phase transport of explosives from buried sources in soils.  

PubMed

The fate and transport of explosives in the soil pore vapor spaces affects both the potential detection of buried ordnance by chemical sensors and vadose zone transport of explosives residues. The efficacy of chemical sensors and their potential usefulness for detecting buried unexploded ordnance (UXO) is difficult to determine without understanding how its chemical signatures are transported through soil. The objectives of this study were to quantify chemical signature transport through soils under various environmental conditions in unsaturated soils and to develop a model for the same. Flux chambers, large soil containers, and batch tests were used to determine explosives signature movement and process descriptors for model development. Low signatures were observed for explosives (2,4-dinitrotoluene, 2,6-dinitrotoluene, and 1,3-dinitrobenzene) under all environmental conditions. A diffusion model was used to describe the chemical transport mechanism in the soil pore air. The soil-air partition constant was treated as a fit parameter in the model owing to the uncertainty in its a priori estimation. The model predictions of the trends in experimental fluxes and the soil concentration were only marginal at best. It was concluded that better estimates of the partition constant are required for more accurate estimation of the chemical concentration at the soil-air interface. Chemical sensors will need to be very sensitive because of low signatures. However, this may result in many false alarms because of explosives residues not associated with UXO on firing ranges. Low explosives signatures also should result in insignificant air environmental exposures. PMID:15648390

Ravikrishna, Raghunathan; Valsaraj, Kalliat T; Price, Cynthia B; Brannon, James M; Hayes, Charolett A; Yost, Sally L

2004-12-01

411

Effect of cigarette menthol content on mainstream smoke emissions.  

PubMed

The 2009 Family Smoking Prevention and Tobacco Control Act empowered the U.S. Food and Drug Administration to study "the impact of the use of menthol in cigarettes on the public health, including such use among children, African Americans, Hispanics and other racial and ethnic minorities," and develop recommendations. Current scientific evidence comparing human exposures between menthol and nonmenthol smokers shows mixed results. This is largely because of the many differences between commercial menthol and nonmenthol cigarettes other than their menthol content. We conducted an innovative study using two types of test cigarettes: a commercial nonmenthol brand that we mentholated at four different levels, and Camel Crush, a commercial cigarette containing a small capsule in the filter that releases menthol solution into the filter when crushed. Cigarettes were machine-smoked at each of the menthol levels investigated, and the total particulate matter (TPM) was collected on a quartz fiber filter pad and analyzed by gas chromatography/mass spectrometry for menthol, nicotine, tobacco-specific nitrosamines (TSNAs), polycyclic aromatic hydrocarbons (PAHs), cotinine, and quinoline. The mainstream smoke was also monitored continuously in real time on a puff-by-puff basis for seven gas-phase constituents (acetaldehyde, acetonitrile, acrylonitrile, benzene, 1,3-butadiene, isoprene, and 2,5-dimethylfuran), using a proton transfer reaction-mass spectrometer. Average yields (in micrograms/cigarette) for the analytes were determined. Menthol in the TPM samples increased linearly with applied menthol concentration, but the amounts of nicotine along with the target TSNAs, PAHs, cotinine, and quinoline in the cigarettes remained essentially unchanged. Similarly, yields of the targeted volatile organic compounds (VOCs) in whole smoke from the mentholated nonmenthol cigarettes that were measured in real-time were largely unaffected by their menthol levels. In the Camel Crush cigarettes, however, the VOC yields appeared to increase in the presence of menthol, especially in the gas phase. Although we succeeded in characterizing key mainstream smoke constituents in cigarettes that differ only in menthol content, further study is needed to definitively answer whether menthol affects exposure to selected cigarette constituents and thereby influences harm. PMID:21888394

Gordon, S M; Brinkman, M C; Meng, R Q; Anderson, G M; Chuang, J C; Kroeger, R R; Reyes, I L; Clark, P I

2011-10-17

412

Solid phase extraction of mercury on sulfur loaded with N-(2-chloro benzoyl)-N?-phenylthiourea as a new adsorbent and determination by cold vapor atomic absorption spectrometry  

Microsoft Academic Search

This paper reports sulfur powder loaded with N-(2-chloro benzoyl)-N?-phenylthiourea as a new solid phase extractor for determination of ultra trace amounts of mercury. The mercury ions were retained on a mini-column filled with the solid phase at a flow rate of 16mLmin?1. The retained Hg(II) ions were eluted with 3molL?1 solution of HCl and measured by cold vapor atomic absorption

N. Pourreza; H. Parham; A. R. Kiasat; K. Ghanemi; N. Abdollahi

2009-01-01

413

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

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

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

414

Vapor-phase synthesis of a solid precursor for {alpha}-alumina through a catalytic decomposition of aluminum triisopropoxide  

SciTech Connect

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.

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

415

Chemical evaluation of electronic cigarettes  

PubMed Central

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

Cheng, Tianrong

2014-01-01

416

Use of dissolved and vapor-phase gases to investigate methanogenic degradation of petroleum hydrocarbon contamination in the subsurface  

USGS Publications Warehouse

[1] At many sites contaminated with petroleum hydrocarbons, methanogenesis is a significant degradation pathway. Techniques to estimate CH4 production, consumption, and transport processes are needed to understand the geochemical system, provide a complete carbon mass balance, and quantify the hydrocarbon degradation rate. Dissolved and vapor-phase gas data collected at a petroleum hydrocarbon contaminated site near Bemidji, Minnesota, demonstrate that naturally occurring nonreactive or relatively inert gases such as Ar and N2 can be effectively used to better understand and quantify physical and chemical processes related to methanogenic activity in the subsurface. In the vadose zone, regions of Ar and N2 depletion and enrichment are indicative of methanogenic and methanotrophic zones, and concentration gradients between the regions suggest that reaction-induced advection can be an important gas transport process. In the saturated zone, dissolved Ar and N2 concentrations are used to quantify degassing driven by methanogenesis and also suggest that attenuation of methane along the flow path, into the downgradient aquifer, is largely controlled by physical processes. Slight but discernable preferential depletion of N2 over Ar, in both the saturated and unsaturated zones near the free-phase oil, suggests reactivity of N2 and is consistent with other evidence indicating that nitrogen fixation by microbial activity is taking place at this site. Copyright 2005 by the American Geophysical Union.

Amos, R.T.; Mayer, K.U.; Bekins, B.A.; Delin, G.N.; Williams, R.L.

2005-01-01

417

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

SciTech Connect

This report summarizes work performed on this project from April 2004 through September 2004. Our previous work demonstrated that a polyurethane foam biofilter could successfully biodegrade the BTEX contaminants found in the SMZ regeneration waste gas stream. However, establishing the biomass on the polyurethane foam packing was relatively time consuming and daily recirculation of a concentrated nutrient solution was required for efficient operation of the foam biofilter. To simplify the start up and operating requirements of the biofilter system, a simple, compost-based biofilter was investigated for its ability to treat the BTEX contaminants generated during the SMZ regeneration process. The investigation of the compost biofilter was divided into three experimental phases that spanned 180 days of biofilter operation. During Phase 1, the biofilter was continuously supplied a BTEX-contaminated waste gas stream. During Phase 2, a series of periodic shutdown tests were conducted to assess how the biofilter responded when the BTEX feed was discontinued for periods ranging from 1 day to 2.8 days. The Phase 3 experiments focused on determining how the biofilter would handle periodic spikes in inlet BTEX concentration as would be expected when it is coupled with an SMZ column. Results from the continuous feed (Phase 1) experiments demonstrated that the compost biofilter could maintain BTEX removals of greater than 98% within two weeks of startup. Results of the shutdown experiments indicated that benzene removal was the most sensitive to interruptions in the BTEX feed. Nevertheless, the BTEX removal efficiency exceeded 95% within 6 hours of reestablishing the BTEX feed to the biofilter. When the biofilter was subjected to periodic spikes in BTEX concentration (Phase 3), it was found that the total BTEX removal efficiency stabilized at approximately 75% despite the fact that the biofilter was only fed BTEX contaminants 8 hours per day. Finally, the effects of nutrient supply and EBCT on compost biofilter performance were also investigated. The bioreactor maintained greater than 95% removal efficiency for over 40 days without an additional supply of nutrients when a 10X concentrated HCMM was mixed with the compost packing at the beginning of the experiments. Results also suggest that an EBCT greater than 30 seconds is required to maintain high BTEX removal efficiencies in the compost biofilter system.

Lynn E. Katz; Kerry A. Kinney; R. S. Bowman; E. J. Sullivan

2004-09-11

418

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

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.

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

419

Geographic patterns of cigarette butt waste in the urban environment  

PubMed Central

Background This reports the initial phase of a study to quantify the spatial pattern of cigarette butt waste in an urban environment. Methods Geographic Information Systems (GIS) was used to create a weighted overlay analysis model which was then applied to the locations of businesses where cigarettes are sold or are likely to be consumed and venues where higher concentrations of butts may be deposited. The model's utility was tested using a small-scale litter audit in three zip codes of San Diego, California. Results We found that cigarette butt waste is highly concentrated around businesses where cigarettes are sold or consumed. The mean number of butts for predicted high waste sites was 38.1 (SD 18.87), for predicted low waste sites mean 4.8 (SD 5.9), p<0.001. Conclusions Cigarette butt waste is not uniformly distributed in the urban environment, its distribution is linked to locations and patterns of sales and consumption. A GIS and weighted overlay model may be a useful tool in predicting urban locations of greater and lesser amounts of cigarette butt waste. These data can in turn be used to develop economic cost studies and plan mitigation strategies in urban communities. PMID:21504924

Novotny, Thomas E

2011-01-01

420

Electronic Cigarettes: Vulnerability of Youth  

PubMed Central

Electronic cigarettes have become popular and are heavily promoted as a safer cigarette and an aid to quit smoking. Although they may have value in reducing cigarette use among smokers, they are of limited value in smoking cessation and pose many problems, particularly in children. Nicotine is highly addictive and affects virtually all cells in the body. It is particularly harmful to developing brains and other organs. The electronic nicotine delivery systems are largely uncontrolled and safety risks are manifold. Initiating nicotine use and increasing dependence in the population may be linked with increased tobacco and other addictive substance abuse even if the individual electronic cigarette delivers less harm than a combustible cigarette does.

2015-01-01

421

Sampling and analysis of cigarette smoke using the solid adsorbent Tenax  

SciTech Connect

The commercial introduction of ultra-low-tar delivery cigarette products has posed challenges in the analysis of their smoke constituents. The application of solid sorbent trapping and thermal desorption, programmed-temperature glass-capillary-column gas chromatography has proven useful for both gas phase and particulate matter analyses. In gas phase analysis the cigarette is smoked directly through a Cambridge filter and Tenax trap, and in whole smoke analysis through the Tenax trap alone. For cigarettes having deliveries of < 1 mg tar/cigarette the entire trap content, or a fraction thereof, is desorbed at 250/sup 0/C in the injection port of the gas chromatograph, and the cryothermally trapped organic desorbate is separated by programmed temperature gas chromatography. Tenax used to trap smoke from higher tar delivery cigarettes is duluted with clean Tenax and homogenized before analysis. Quantitation is made by the method of external standards, the RSD for smoke components averaging generally +-20%. Higher RSD's of +-60% in the case of some ultra-low cigarette smoke components may be influenced by mainstream enrichment by sidestream smoke drifting near the air dilution vents in the filter rod. This method of analysis when applied to whole smoke can determine the entire cigarette delivery of many gas phase and particulate matter components, and has sufficient sensitivity that flavor related components in cigarette smoke are analyzable. The distribution of some semivolatile components between gas and particulate phases has been determined by application of this method and is reported.

Higgins, C.E.; Griest, W.H.; Guerin, M.R.

1984-05-01

422

Cardiovascular and Mood Responses to Quantified Doses of Cigarette Smoke in Oral Contraceptive Users and Nonusers  

Microsoft Academic Search

Previous research suggests that the female sex hormones may moderate cardiovascular and mood responses to cigarette smoking and abstinence. To test this possibility, acute effects of cigarette smoking on cardiovascular reactivity and mood were examined in 12 oral contraceptive users and 12 nonusers across two menstrual phases (early and late cycle). After overnight deprivation, each participant attended two sessions in

Carmen L. Masson; David G. Gilbert

1999-01-01

423

DNA typing from cigarette butts.  

PubMed

We performed DNA typing for D1S80, HLADQA1, TH01 and PM using the butts of 100 cigarettes that were smoked by ten different individuals (ten cigarettes per individual). The results obtained from DNA typing for D1S80 agreed with the results obtained using bloodstains in 76 cigarette butt samples. Sixteen samples produced false results, showing the loss of the longer allelic hetero-band. When examined using agarose gel electrophoresis, high-molecular weight DNA was not observed in these samples. The same results were also observed for buccal swab samples and saliva stains obtained from the same individuals. In the remaining eight cigarette butt samples, PCR products were not detected. The results obtained from DNA typing for TH01, HLADQA1 and PM agreed with the results obtained using bloodstains in 90 samples. In the remaining ten samples of a specific kind of cigarette (Marlboro), the PCR products were not detected. The extracts from the ends of the Marlboro cigarettes were stained yellow. When the DNA extracted from Marlboro cigarette butts was treated with Microcon-100 (amicon) or SizeSep 400 Span Columns (Amersham Pharmacia Biotech), PCR products could be detected. When PCR amplification was performed after adding extracts from the ends of unsmoked Marlboro cigarettes to DNA extracted from bloodstains, PCR products could not be detected. The present data indicate that the degradation of high-molecular weight DNA and the inhibition of PCR by dyes of the cigarette end should be kept in mind when performing DNA typing using cigarette ends. PMID:12935582

Watanabe, Yoshihisa; Takayama, Tomohiro; Hirata, Keiji; Yamada, Sadao; Nagai, Atsushi; Nakamura, Isao; Bunai, Yasuo; Ohya, Isao

2003-03-01

424

Liquid-vapor phase diagram and surface properties in oppositely charged colloids represented by a mixture of attractive and repulsive Yukawa potentials  

NASA Astrophysics Data System (ADS)

The liquid-vapor phase diagrams of equal size diameter ? binary mixtures of screened potentials have been reported for several ranges of interaction using Monte Carlo simulation methods [J. B. Caballero, A. M. Puertas, A. Fer?andez-Barbero, F. J. de las Nieves, J. M. Romero-Enrique, and L. F. Rull, J. Chem. Phys. 124, 054909 (2006), 10.1063/1.2159481; A. Fortini, A.-P. Hynninen, and M. Dijkstra, J. Chem. Phys. 125, 094502 (2006), 10.1063/1.2335453]. Both works report controversial results about the stability of the phase diagram with the inverse Debye screening length ?. Caballero found stability for values of ?? up to 20 while Fortini reported stability for ?? up to 20 while Fortini reported stability for ?? ? 4. In this work a spinodal decomposition process where the liquid and vapor phases coexist through an interface in a slab geometry is used to obtain the phase equilibrium and surface properties using a discontinuous molecular dynamics simulations for mixtures of equal size particles carrying opposite charge and interacting with a mixture of attractive and repulsive Yukawa potentials at different values of ??. An crude estimation of the triple point temperatures is also reported. The isothermal-isobaric method was also used to determine the phase stability using one phase simulations. We found that liquid-vapor coexistence is stable for values of ?? > 20 and that the critical temperatures have a maximum value at around ?? = 10, in agreement with Caballero et al. calculations. There also exists a controversy about the liquid-vapor envelope stability of the pure component attractive Yukawa model which is also discussed in the text. In addition, details about the equivalence between continuous and discontinuous molecular dynamics simulations are given, in the Appendix, for Yukawa and Lennard-Jones potentials.

Chapela, Gustavo A.; del Río, Fernando; Alejandre, José

2013-02-01

425

Liquid-vapor phase diagram and surface properties in oppositely charged colloids represented by a mixture of attractive and repulsive Yukawa potentials.  

PubMed

The liquid-vapor phase diagrams of equal size diameter ? binary mixtures of screened potentials have been reported for several ranges of interaction using Monte Carlo simulation methods [J. B. Caballero, A. M. Puertas, A. Fern?andez-Barbero, F. J. de las Nieves, J. M. Romero-Enrique, and L. F. Rull, J. Chem. Phys. 124, 054909 (2006); A. Fortini, A.-P. Hynninen, and M. Dijkstra, J. Chem. Phys. 125, 094502 (2006)]. Both works report controversial results about the stability of the phase diagram with the inverse Debye screening length ?. Caballero found stability for values of ?? up to 20 while Fortini reported stability for ?? up to 20 while Fortini reported stability for ?? ? 4. In this work a spinodal decomposition process where the liquid and vapor phases coexist through an interface in a slab geometry is used to obtain the phase equilibrium and surface properties using a discontinuous molecular dynamics simulations for mixtures of equal size particles carrying opposite charge and interacting with a mixture of attractive and repulsive Yukawa potentials at different values of ??. An crude estimation of the triple point temperatures is also reported. The isothermal-isobaric method was also used to determine the phase stability using one phase simulations. We found that liquid-vapor coexistence is stable for values of ?? > 20 and that the critical temperatures have a maximum value at around ?? = 10, in agreement with Caballero et al. calculations. There also exists a controversy about the liquid-vapor envelope stability of the pure component attractive Yukawa model which is also discussed in the text. In addition, details about the equivalence between continuous and discontinuous molecular dynamics simulations are given, in the Appendix, for Yukawa and Lennard-Jones potentials. PMID:23406133

Chapela, Gustavo A; del Río, Fernando; Alejandre, José

2013-02-01

426

Development of a water recovery subsystem based on Vapor Phase Catalytic Ammonia Removal (VPCAR)  

NASA Technical Reports Server (NTRS)

An integrated engineering breadboard subsystem for the recovery of potable water from untreated urine was designed, fabricated and tested. It was fabricated from commercially available components without emphasis on weight, volume and power requirement optimization. Optimizing these parameters would make this process competitive with other spacecraft water recovery systems. Unlike other phase change systems, this process is based on the catalytic oxidation at elevated temperatures of ammonia and volatile hydrocarbons to innocuous products; therefore, no urine pretreatment is required. The testing program consisted of parametric tests, one month of daily tests, and a continuous run of 165 hours. The recovered water is low in ammonia, hydrocarbons and conductivity and requires only adjustment of its pH to meet drinking water standards.

Budininkas, P.; Rasouli, F.; Wydeven, T.

1986-01-01

427

An international analysis of cigarette affordability  

PubMed Central

Objective: To investigate how affordable cigarettes are in developed and developing countries, and to calculate by how much the affordability of cigarettes has changed between 1990 and 2001; and secondly, to investigate the relation between cigarette affordability and consumption. Design: Affordability was defined as the cost of cigarettes relative to per capita income. Trends in cigarette affordability, and affordability elasticities of demand, were estimated using regression techniques. Subjects: Seventy countries were investigated, of which 28 are categorised as high income developed countries, while 42 are categorised as developing countries. Cigarette prices were obtained for the main city/cities in the countries. Results: Despite the fact that cigarettes are more expensive in developed countries, the high levels of income make cigarettes more affordable in these countries vis-à-vis developing countries. Of the 28 developed countries, cigarettes became more affordable in 11 and less affordable in 17 countries during the 1990s. Of the 42 developing countries, cigarettes became more affordable in 24 and less affordable in 18 countries. Based on a cross sectional analysis, a 1% increase in the relative income price (the inverse of cigarette affordability) is expected to decrease cigarette consumption by between 0.49–0.57%. Conclusions: Cigarette affordability, more than just the price, determines cigarette consumption. While cigarettes have become more affordable in many developing countries, some developing countries (for example, South Africa, Poland, and Thailand) have implemented strong and effective tobacco control policies, and have been able to decrease cigarette consumption as a result. PMID:15564616

Blecher, E; van Walbeek, C P

2004-01-01

428

Cigarette Advertisements and Youth Attitudes about Smoking  

Microsoft Academic Search

Cigarette advertisements are commonly believed to play an important causal role in encouraging youth to start smoking. The 1998 Master Settlement Agreement between cigarette manufacturers and the states included a ban on cigarette advertising that targets youth. The 2009 Family Smoking Prevention and Tobacco Control Act – which granted regulatory authority over the cigarette industry to the Food and Drug

Donald Kenkel; Hua Wang

2010-01-01

429

Electronic-Cigarette Smoking Experience Among Adolescents  

Microsoft Academic Search

ObjectivesTo investigate the level of awareness and contact routes to electronic cigarette (e-cigarette), and to identify significant factors that may affect adolescent use of e-cigarettes; this study explores the experience of e-cigarettes among adolescents.

Jun Ho Cho; Eunyoung Shin; Sang-Sik Moon

2011-01-01

430

Functional Analysis and Treatment of Cigarette Pica.  

ERIC Educational Resources Information Center

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.…

Piazza, Cathleen C.; And Others

1996-01-01

431

Speciated fine-particle (<2.5 {micro}m aerodynamic diameter) and vapor-phase acid concentrations in southern California  

SciTech Connect

A fine-particle (<2.5 {micro}m aerodynamic diameter) and vapor-phase acid sampling network has been in operation among 12 communities in southern California since late 1993. The data from this network consists of concentrations of particulate matter <10 {micro}m in aerodynamic diameter (PM10), nitrogen dioxide, ozone, vapor-phase hydrochloric, nitric, acetic, and formic acids, particulate matter <2.5 {micro}m in aerodynamic diameter (PM2.5), and the chloride, nitrate, sulfate, and ammonium components of PM2.5. These measurements are the basis of the exposure assessment estimates of the Children`s Health Study, a multi-year study, mainly of lung function development and respiratory illness, taking place in southern California. One of the goals of the Children`s Health Study is to utilize a cost-effective means of obtaining continuous fine-particle and vapor-phase acid data for a multi-year study with enough time resolution to allow seasonal estimates of exposure. A two-week sampler was developed to meet these needs. Four continuous years of vapor-phase acid and PM2.5 mass, chloride, nitrate, sulfate, and ammonium data have been collected. During this time, the sampler has proven to be reliable. A decline in PM2.5 mass, nitrate, and ammonium ions in most of the communities from 1994 to 1997 was observed. In contrast, very little change in vapor-phase acids was observed. There has been increased interest at the national level in fine particles and their characteristics. The network provides a rich database that can be used to characterize southern California communities on the basis of their level of fine particles (and their components) and vapor-phase acids and should prove valuable with respect to both prospective and retrospective health studies. The database also provides a general characterization of the levels of PM2.5 affecting 25 million people in southern California.

Taylor, C.A. Jr.; Stover, C.A.; Westerdahl, F.D. [California Air Resources Board, Sacramento CA (United States). Research Div.

1998-12-31

432

Bi surfactant control of ordering and surface structure in GaInP grown by organometallic vapor phase epitaxy  

SciTech Connect

The surfactant Bi has been added during organometallic vapor phase epitaxial growth (OMVPE) of GaInP using the precursor trimethylbismuth. The addition of a small amount of Bi during growth results in disordered material using conditions that would otherwise produce highly ordered GaInP. Significant changes in the surface structure are observed to accompany the disordering. Atomic force microscopy measurements show that Bi causes an order of magnitude increase in step velocity, leading to the complete elimination of three-dimensional islands for growth on singular (001) GaAs substrates, and a significant reduction in surface roughness. Surface photoabsorption measurements indicate that Bi reduces the number of [1(bar sign)10] P dimers on the surface. Secondary ion mass spectroscopy measurements reveal that the Bi is rejected from the bulk, even though it changes the surface reconstruction. Clearly, Bi acts as a surfactant during OMVPE growth of GaInP. The difference in band gap energy caused by the reduction in order parameter during growth is measured using photoluminescence to be about 110 meV for layers grown on singular substrates. Disorder/order/disorder heterostructures were successfully produced in GaInP with a constant solid composition by modulating the TMBi flow rate during growth. (c) 2000 American Institute of Physics.

Jun, S. W. [Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)] [Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Lee, R. T. [Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)] [Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Fetzer, C. M. [Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)] [Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Shurtleff, J. K. [Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)] [Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Stringfellow, G. B. [Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)] [Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Choi, C. J. [Department of Materials Science and Engineering, Kwangju Institute of Science and Technology, Kwangju 506-712, Korea (Korea, Republic of)] [Department of Materials Science and Engineering, Kwangju Institute of Science and Technology, Kwangju 506-712, Korea (Korea, Republic of); Seong, T.-Y. [Department of Materials Science and Engineering, Kwangju Institute of Science and Technology, Kwangju 506-712, Korea (Korea, Republic of)] [Department of Materials Science and Engineering, Kwangju Institute of Science and Technology, Kwangju 506-712, Korea (Korea, Republic of)

2000-10-01

433

Atomic ordering in InAs sub 0. 5 P sub 0. 5 grown by organometallic vapor phase epitaxy  

SciTech Connect

InAsP epilayers grown by organometallic vapor phase epitaxy have been investigated using transmission electron microscopy. Electron diffraction studies using {l angle}110{r angle} cross sections indicate the formation of CuPt-like ordering on the group V sublattice. Only two of the four possible ordered variants are observed for epilayers grown on the exactly (001) oriented InP substrates. All the order-induced diffraction spots for InAsP are found to occur on the (110) cross section. Thus, the variants found in InAsP are 1/2({bar 1}11) and 1/2(1{bar 1}1), exactly the same as those found in GaInP, an alloy with CuPt ordering on the group III sublattice. This result is in agreement with recent studies on GaAsP and is contradictory to expectations based on the bond-length model proposed previously for GaInP alloys. The direction of substrate misorientation has a strong effect on the formation of ordered structures for normally (001) oriented InP substrates.

Jaw, D.H.; Chen, G.S.; Stringfellow, G.B. (Departments of Electrical Engineering and Materials Science and Engineering, 304 EMRO, University of Utah, Salt Lake City, Utah 84112 (USA))