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Argon
Kinds of Argon Terms modified by Argon Selected AbstractsStochastic and Relaxation Processes in Argon by Measurements of Dynamic Breakdown VoltagesCONTRIBUTIONS TO PLASMA PHYSICS, Issue 7 2005V. Lj. Abstract Statistically based measurements of breakdown voltages Ub and breakdown delay times td and their variations in transient regimes of establishment and relaxation of discharges are a convenient method to study stochastic processes of electrical breakdown of gases, as well as relaxation kinetics in afterglow. In this paper the measurements and statistical analysis of the dynamic breakdown voltages Ub for linearly rising (ramp) pulses in argon at 1.33 mbar and the rates of voltage rise k up to 800 V s,1 are presented. It was found that electrical breakdowns by linearly rising (ramp) pulses is an inhomogeneous Poisson process caused by primary and secondary ionization coefficients , , , and electron yield Y variations on the voltage (time). The experimental breakdown voltage distributions were fitted by theoretical distributions by applying approximate analytical and numerical models. The afterglow kinetics in argon was studied based on the dependence of the initial electron yield on the relaxation time Y0 (, ) derived from fitting of distributions. The space charge decay was explained by the surface recombination of nitrogen atoms present as impurities. The afterglow kinetics and the surface recombination coefficients on the gas tube and cathode were determined from a gas-phase model. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Influence of the atmosphere on the growth of LiYF4 single crystal fibers by the micro-pulling-down methodCRYSTAL RESEARCH AND TECHNOLOGY, Issue 2 2009D. Maier Abstract Micro-pulling-down growth of LiYF4 single crystal fibers have been performed under different gas atmospheres using stoichiometric LiYF4 single crystal pieces from prior Czochralski experiments as starting material. Completely transparent and phase pure LiYF4 single crystal fibers could be obtained after evacuation of the recipient to 2×10 -6 mbar and subsequent filling with pure (99.995%) CF4 gas. Using a gas mixture of 5% CF4 in Argon or pure 5N Argon leads to the formation of micro crystallites of oxofluorides on the surface. Evacuating only to 3 × 10 -3 mbar leads, independently of atmosphere, to completely white fibers that are heavily contaminated with oxofluorides. DSC measurements of the completely transparent fiber grown under pure CF4 atmosphere reveal congruent melting behavior. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Photochemistry of Salicylaldoxime in Solid Argon: An Experimental and Theoretical StudyEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 27 2010Joanna Grzegorzek Abstract The photochemistry of salicylaldoxime in solid argon has been investigated by FTIR spectroscopy and DFT calculations. The salicylaldoxime molecule trapped in the matrix from the vapor above the solid sample has the most stable syn1 conformation with an intramolecular hydrogen bond. Irradiation (, > 320 nm) leads to conversion of the syn1 conformer into the syn3 one, in which the C(H)NOH and (C)OH groups are rotated around the C,C and C,O bonds, respectively, and the intramolecular hydrogen bond is broken. The photochemistry of syn3 involves three possible routes: (i) conversion of syn3 into anti2 conformer, this process requires rearrangement of the NOH group with respect to the C=N bond; (ii) photodissociation of salicylaldoxime into 2-cyanophenol and water, which form a hydrogen-bonded complex; and (iii) regeneration of the syn1 conformer. The third route is a very small contribution to the overall process. The study performed with [D2]salicylaldoxime indicates that the dehydration reaction of salicylaldoxime involves cleavage of the N,O bond and formation of OH and Ph(OH)C(H)N radicals in the first step. Then, the OH radical abstracts a hydrogen atom from the CH group to form 2-cyanophenol and water molecules. When the sample is exposed to the full output of the mercury lamp the 2-cyanophenol complex with water becomes the dominating product. [source] Tailoring surface properties of cellulose acetate membranes by low-pressure plasma processingJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010Chun Huang Abstract The aim of this study was to tailor the surface properties of cellulose acetate membranes using low-pressure plasma processing. Argon (Ar) plasma and Difluoromethane (CH2F2) plasma were used to control the surface wettabilities of cellulose acetate membranes. Optical emission spectroscopy was used to examine the various chemical species of low-pressure plasma processing. In this investigation, the plasma-treated surfaces were analyzed by X-ray photoelectron spectroscopy, while changes in morphology and surface roughness were determined with confocal laser scanning microscopy. Ar plasma activation resulted in hydrophilic surface. CH2F2 plasma deposited hydrophobic layer onto the cellulose acetate membrane because of strong fluorination of the top layer. The results reveal low-pressure plasma processing is an effective method to control the surface properties of cellulose acetate membranes. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Die Entdeckung des "trägen" GasesPHYSIK IN UNSERER ZEIT (PHIUZ), Issue 6 2004Manfred Jacobi Im Jahr 1904 erhielt der britische Physiker Lord Rayleigh (John William Strutt, 1842 bis 1919) den Nobelpreis für seine Untersuchungen über die Dichte von Gasen und die Entdeckung des Edelgases Argon. [source] A continuous flow mass spectrometry technique of argon isotope measurement for K/Ar geochronology,RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 16 2009Alexander V. Ignatiev A new method for the measurement of argon isotope composition in a continuous flow of helium for potassium/argon geochronology is described. Extraction of argon from geological samples in multiple-sample holders was carried out in a chamber by heating with a continuous Nd-YAG laser. The extracted and pre-concentrated argon is passed through a chromatographic capillary column in a flow of helium. Argon is separated from possible contaminants in the column and is injected through an open split into the ion source of an isotope ratio mass spectrometer. Measurement of the 36Ar, 38Ar and 40Ar isotopes was carried out in dynamic mode, using a triple-collector ion detector. These experiments have shown that continuous flow mass spectrometry can be used for the analysis of radiogenic argon in picogram quantities with an accuracy that is satisfactory for the solution of many geochronological problems. The method of argon isotope measurement in a continuous flow of helium is an alternative to the measurement of argon isotopes in the static mode. The sensitivity and accuracy of argon measurement by this method are comparable with those provided by the classical static method. The measurement of argon isotopes in a continuous flow of helium is simpler and more reliable than measurement in the static mode. Copyright © 2009 John Wiley & Sons, Ltd. [source] Dipeptide Crystals as Excellent Permselective Materials: Sequential Exclusion of Argon, Nitrogen, and Oxygen,ANGEWANDTE CHEMIE, Issue 17 2010Selektive Poren: Mikroporöse Dipeptidkristalle können als einkristalline Membranen eingesetzt werden. Permeationsexperimente mit N2, O2 und Ar, den Hauptkomponenten der Luft, ergeben hohe Permeabilitäten und ausgezeichnete Selektivitäten (siehe Bild). Kristalle von L -Alanyl- L -alanin zeigen extrem hohe O2/N2 -Selektivitäten. [source] Siliciumverbindungen von Neon und Argon,ANGEWANDTE CHEMIE, Issue 46 2009Jana Roithová Dr. Bimolekulare Stöße massenselektierter SiF32+ -Dikationen mit Argon führen zu dem ArSiF22+ -Dikation als Hauptprodukt bei thermischen Energien. Das Dikation weist eine kovalente Ar-Si-Bindung auf und ist damit der erste Vertreter einer neuen Klasse von Edelgasverbindungen. Trotz wesentlich kleinerer Ausbeuten wird auch für die analoge Neonverbindung NeSiF22+ ein eindeutiges Signal beobachtet. Somit können mit dem SiF32+ -Dikation als Elektrophil neuartige Edelgasverbindungen in thermischen Ion-Molekül-Reaktionen erhalten werden. [source] Infrared Spectra of M(OH)1,2,4 (M: Pb, Sn) in Solid Argon.CHEMINFORM, Issue 50 2005Xuefeng Wang No abstract is available for this article. [source] Infrared Spectrum of Hg(OH)2 in Solid Neon and Argon.CHEMINFORM, Issue 12 2005Xuefeng Wang No abstract is available for this article. [source] Infrared Spectra of Thallium Hydrides in Solid Neon, Hydrogen, and Argon.CHEMINFORM, Issue 24 2004Xuefeng Wang No abstract is available for this article. [source] Infrared Spectra and DFT Calculations for the Coinage Metal Hydrides MH, (H2)MH, MH2, M2H, M2H - , and (H2)CuHCu in Solid Argon, Neon, and Hydrogen.CHEMINFORM, Issue 1 2004Xuefeng Wang No abstract is available for this article. [source] ChemInform Abstract: Infrared Spectra of the Novel Ge2H2 and Ge2H4 Species and the Reactive GeH1,2,3 Intermediates in Solid Neon, Deuterium and Argon.CHEMINFORM, Issue 37 2002Xuefeng Wang Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] A study of the intra-operative effect of the Argon and KTP laser in stapes surgeryCLINICAL OTOLARYNGOLOGY, Issue 4 2002M.W. Yung The intraoperative effect of the Argon and KTP laser was studied on 20 patients who had primary stapes surgery under local anaesthetic; 10 had Argon and 10 had KTP laser stapedotomy. Symptoms of inner ear disturbance such as dizziness and tinnitus were systematically recorded during the laser procedure. Both dizziness and tinnitus were relatively uncommon when the laser was used on the promontory. When the laser was used to transect the posterior crus, all the patients reported transient dizziness, probably from the thermal effect through the posterior crus into the inner ear. However, tinnitus was unusual during this stage. When the laser was used to fenestrate the footplate, only 30% of patients reported a transient dizziness as less laser energy was used. On the other hand, 55% of the patients experienced tinnitus during this stage, which indicates an acoustic effect on the inner ear. There is no difference between the Argon and KTP laser. [source] Spectroscopic Diagnostics of Pulsed arc Plasmas for Particle GenerationCONTRIBUTIONS TO PLASMA PHYSICS, Issue 8 2008K. Behringer Abstract Pulsed arc plasmas were diagnosed by means of emission spectroscopy. A capacitor was discharged through argon and hydrogen leading to a few cycles of damped current oscillation with ,120 ,s period and 5-12 kA maximum current. Spectroscopic measurements in the visible range were carried out in order to characterise the electron temperature and density in the arc channel as well as electron and gas temperatures in the afterglow plasmas. Spectra were integrated over 10 ,s time windows and shifted in time from pulse to pulse. The plasmas also contained substantial fractions of electrode material (brass), namely copper and zinc. The electron density was measured in the conventional way from the broadening of H, or from the Ar I Stark width. In the arc channel, it ranged from about 3 · 1022 to 2 · 1023 m,3. The broadening of Zn II lines could also be used. Ratios of Ar I to Ar II and of Zn I to Zn II line intensities were analysed for the electron temperature. Line pairs were found which lay conveniently close in one frame of the spectrometer allowing automatic on-line analysis without relying on reproducibility. Atomic physics models including opacity were developed for Ar II and Zn II in order to check the existence of a Boltzmann distribution of their excited states. These calculations showed that the observed levels were in fact close to thermodynamic equilibrium, in particular, if the resonance lines were optically thick. Electron temperature measurements yielded values between 14000 K and 21000 K. The gas temperature in the afterglow, where particles should have formed, was derived from the rotational and vibrational temperatures of C2 molecular bands. Ratios between Cu I line intensities yielded the electron temperatures. Both were found to be a few 1000 K. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] On the Modelling of a Nonequilibrium Spherical Microwave Discharge at Atmospheric PressureCONTRIBUTIONS TO PLASMA PHYSICS, Issue 3 2007I. R. Rafatov Abstract The work presents results of calculation of a spherical microwave discharge characteristics in an argon at atmospheric pressure against the external parameters (the mode, frequency and power of the applied electromagnetic field and the size of the discharge chamber). Model assumes a thermal and ionization non-equilibrium of discharge plasma and takes into account first three modes of incident electromagnetic waves. Calculation results are compared with the results for the ionization equilibrium model. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Stochastic and Relaxation Processes in Argon by Measurements of Dynamic Breakdown VoltagesCONTRIBUTIONS TO PLASMA PHYSICS, Issue 7 2005V. Lj. Abstract Statistically based measurements of breakdown voltages Ub and breakdown delay times td and their variations in transient regimes of establishment and relaxation of discharges are a convenient method to study stochastic processes of electrical breakdown of gases, as well as relaxation kinetics in afterglow. In this paper the measurements and statistical analysis of the dynamic breakdown voltages Ub for linearly rising (ramp) pulses in argon at 1.33 mbar and the rates of voltage rise k up to 800 V s,1 are presented. It was found that electrical breakdowns by linearly rising (ramp) pulses is an inhomogeneous Poisson process caused by primary and secondary ionization coefficients , , , and electron yield Y variations on the voltage (time). The experimental breakdown voltage distributions were fitted by theoretical distributions by applying approximate analytical and numerical models. The afterglow kinetics in argon was studied based on the dependence of the initial electron yield on the relaxation time Y0 (, ) derived from fitting of distributions. The space charge decay was explained by the surface recombination of nitrogen atoms present as impurities. The afterglow kinetics and the surface recombination coefficients on the gas tube and cathode were determined from a gas-phase model. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] High Density Cascaded Arc Produced Plasma Expanding in a Low Pressure RegionCONTRIBUTIONS TO PLASMA PHYSICS, Issue 5-6 2004R. P. Dahiya Abstract Experimental measurements made in thermal expanding argon, nitrogen and hydrogen plasmas with particular reference to molecular kinetics, surface nitriding and intense flux in magnetic field are discussed. The plasma is generated in a cascaded arc source. In the presence of molecular species (H2 / N2) dissociative recombination reactions involving rovibrationally excited molecules contribute to a rapid decay of the plasma species, especially for hydrogen system. A combination of nitrogen and hydrogen plasma gives an efficient plasma nitriding process, which has been applied for case hardening of machinery components. In another setup a strong axial magnetic field (0.4 - 1.6 T) contains and substantially prolongs the plasma beam in the chamber. In the presence of the magnetic field, an additional current drawn through the plasma beam using a biased substrate and a ring creates dense low temperature plasma giving a new unexplored plasma regime. The plasma kinetics are modified in this regime from the recombining to the ionising mode. When the additional current in the argon plasma beam exceeds 30 A, its light emission is predominantly in the blue region. With the additional current and magnetic field, the emission intensity of H, and other lines arising from higher energy levels in the hydrogen Balmer series is enhanced. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Synthesis and tribological properties of laminated Ti3SiC2 crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2010Qiong Wu Abstract Laminated Ti3SiC2 crystals are prepared of Ti, Si, C and Al powders by the method of hot isostatic pressing with NaCl additive in argon at 1350 °C. The laminated morphology of Ti3SiC2 is presented through the SEM and TEM observations. The results of high resolution transmission electron microscope (HRTEM) and selected area electron diffraction (SAED) patterns combined, it can be seen that the layers are of Ti3SiC2 crystals. The growth mechanism of Ti3SiC2 crystals, controlled by two-dimensional nucleation, is also explained. The tribological properties of Ti3SiC2 crystals as additives in HVI500 base oil are investigated by a UMT-2 ball-on-plate friction and wear tester. The study shows that under determinate conditions, the friction coefficient of the base oil containing Ti3SiC2 crystals is lower than that of pure base oil, and it decreases with the increase of mass percent of Ti3SiC2 nanolayers when its proportion is lower than 5wt. %. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Growth of bismuth tri-iodide platelets by the physical vapor deposition methodCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2004A. Cuña Abstract The work reports the growth of single BI3 crystals with platelets habit. Platelets were grown by physical vapor deposition (PVD) in a high vacuum atmosphere and with argon, polymer or iodine as additives. Crystals grew in the zone of maximum temperature gradient, perpendicular to the ampoule wall. Crystals grown with argon as additive show a very shining surface, have hexagonal (0 0 l) faces, sizes up to 20 x 10 mm2 and thicknesses up to 100 ,m. They were characterized by optical microscopy and scanning electron microscopy (SEM). Dendritic-like structures were found to be their main surface defect. SEM indicates that they grow from the staking of hexagonal unities. Electrical properties of the crystals grown under different growth conditions were determined. Resistivities up to 2 x 1012 ,cm (the best reported value for monocrystals of this material) were obtained. X-ray response was measured by irradiation of the platelets with a 241Am source of 3.5 mR/h. A comparison of results according to the growth conditions was made. Properties of the crystals grown by this method are compared with the ones measured for others previously grown from the melt. Also, results for bismuth tri-iodide platelets are compared with the ones obtained for mercuric and lead iodide platelets. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Renewable Copper and Silver Amalgam Film Electrodes of Prolonged Application for the Determination of Elemental Sulfur Using Stripping VoltammetryELECTROANALYSIS, Issue 7 2008Robert Piech Abstract New, renewable copper (Hg(Cu)FE) and silver (Hg(Ag)FE) based amalgam film electrodes applied for the determination of elemental sulfur using differential pulse cathodic stripping voltammetry are presented. With surface areas adjustable from 1 to 12,mm2, both electrodes are characterized by very good surface reproducibility (,2%) and long-term stability (a few thousand measurement cycles). The mechanical refreshing of the amalgam film takes about 1,2 seconds. The effects of various factors such as instrumental parameters and the supporting electrolyte composition were optimized. Interferences from sulfides are easily removed by the addition of acid, and bubbling with argon, for Hg(Ag)FE. In the case of Hg(Cu)FE, sulfides did not interfere. The calibration graph is linear within the studied range from 16,ng L,1 to 4.8,,g L,1 for Hg(Cu)FE, and up to 6.4,,g L,1 for Hg(Ag)FE (tacc=15,s). The correlation coefficients for the two electrodes were at least 0.997. The detection limits for a low concentration of S(0) and tacc=60,s are as low as 14,ng L,1 for Hg(Cu)FE and 4,ng L,1 for Hg(Ag)FE. The proposed method was successfully applied and validated by studying the recovery of S(0) from spiked river water. [source] Photochemistry of Salicylaldoxime in Solid Argon: An Experimental and Theoretical StudyEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 27 2010Joanna Grzegorzek Abstract The photochemistry of salicylaldoxime in solid argon has been investigated by FTIR spectroscopy and DFT calculations. The salicylaldoxime molecule trapped in the matrix from the vapor above the solid sample has the most stable syn1 conformation with an intramolecular hydrogen bond. Irradiation (, > 320 nm) leads to conversion of the syn1 conformer into the syn3 one, in which the C(H)NOH and (C)OH groups are rotated around the C,C and C,O bonds, respectively, and the intramolecular hydrogen bond is broken. The photochemistry of syn3 involves three possible routes: (i) conversion of syn3 into anti2 conformer, this process requires rearrangement of the NOH group with respect to the C=N bond; (ii) photodissociation of salicylaldoxime into 2-cyanophenol and water, which form a hydrogen-bonded complex; and (iii) regeneration of the syn1 conformer. The third route is a very small contribution to the overall process. The study performed with [D2]salicylaldoxime indicates that the dehydration reaction of salicylaldoxime involves cleavage of the N,O bond and formation of OH and Ph(OH)C(H)N radicals in the first step. Then, the OH radical abstracts a hydrogen atom from the CH group to form 2-cyanophenol and water molecules. When the sample is exposed to the full output of the mercury lamp the 2-cyanophenol complex with water becomes the dominating product. [source] Photochemistry of cis -3-Diazo-5,6-dimethyl-1,4-oxathian-2-one S -Oxide in Argon MatricesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 13 2006Orlagh C. M. O'Sullivan Abstract The photochemistry of the ,-diazo sulfoxide 7 has been investigated in solid argon at 10 K by IR spectroscopy. The sulfinyl carbene was not detected directly but instead underwent photochemically induced hetero-Wolff rearrangement to the sulfine 8 which could be detected and characterized following irradiation at 248 nm. Further photochemical reaction of this intermediate led to the oxathiirane 9 which was most readily detected on irradiation of 7 at 308 nm. The matrix-isolated species were identified by comparison of experimental and calculated IR spectra. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Reactions of Silicon Atoms with Conjugated ,-Systems: A Matrix-Spectroscopic StudyEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 3 2003Günther Maier Abstract The reaction of silicon atoms with cyclopentadiene and butadiene in argon at 10 K has been studied. Addition to the conjugated ,-system of cyclopentadiene occurs in a [1,4]-fashion. Upon irradiation the ,-adduct 3 rearranges to the formal insertion product 2 which has an unusual structure. Remarkably, a photoequilibrium between the two exo,endo isomers 2 and 4 can be observed. In the case of butadiene the addition is less stereospecific. The planar [1,4]-adduct 11 is formed together with the [1,2]-adduct 14. Surprisingly, besides 11 a second, nonplanar [1,4]-adduct 10 can be detected. The isomers 11 and 14 are transformed into 10 upon irradiation. The final photoproduct is silole 9. The structural elucidation of the new species is based on isotopic labelling and a comparison of the experimental observations with the results from density functional calculations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Biocompatibility of Lotus-type Stainless Steel and Titanium in Alveolar BoneADVANCED ENGINEERING MATERIALS, Issue 9 2006Y. Higuchi Abstract Lotus-type porous stainless steel (SUS304L) and porous titanium were fabricated by unidirectional solidification in a mixture gas of hydrogen and argon. The porous metals which were cut into 5,mm cubes (non-dehydrogenated) and 3.4,mm,,×,5,mm cylinders (dehydrogenated) were implanted into the canine mandible alveolar bone for two, four and eight weeks for animal experiments. The changes in the tissues were observed using SEM. For porous stainless steel (cylindrical; dehydrogenated) new formation of bones was observed around the sample in two weeks without any sign of bony ingrowth into the pores. The osteogenesis was found in shallow areas in the pores in four weeks and deep in the pores in eight weeks. Porous titanium, on the other hand, showed deep ingrowth of new bones in four weeks. Our observations allowed us to expect application of the porous metals as biomaterials. They maintain mechanical strength and are lighter in weight so that it is expected to be applied for dental implants and core materials of artificial bones. [source] The effect of overload on the fatigue crack growth behaviour of 304 stainless steel in hydrogenFATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 1 2001M. H. Kelestemur Fatigue crack growth (FCG) behaviour and its characteristics following tensile overloads were investigated for AISI 304 stainless steel in three different atmospheres; namely dry argon, moist air and hydrogen. The FCG tests were performed by MTS 810 servohydraulic machine. CT specimens were used for the tests and crack closure measurements were made using an extensometer. FCG rates of 304 stainless steel at both dry argon and moist air atmospheres have shown almost the same behaviour. In other words, the effect of moisture on FCG of this material is very small. However, in a hydrogen atmosphere, the material showed considerably higher crack growth rate in all regimes. In general, for all environments, the initial effect of overloads was to accelerate the FCG rate for a short distance (less than a mm) after which retardation occurred for a considerable amount of time. The main causes for retardation were found as crack blunting and a long reinitiation period for the fatigue crack. Regarding the environmental effect, the overload retardation was lowest in a hydrogen atmosphere. This low degree of retardation was explained by a hydrogen embrittlement mechanism. In a general sense, hydrogen may cause a different crack closure mechanism and hydrogen induced crack closure has come in to the picture. Scanning electron microscope and light microscope examinations agreed well with the above results. [source] Real-time quadrupole mass spectrometer analysis of gas in borehole fluid samples acquired using the U-tube sampling methodologyGEOFLUIDS (ELECTRONIC), Issue 3 2006B. M. FREIFELD Abstract Sampling of fluids in deep boreholes is challenging because of the necessity of minimizing external contamination and maintaining sample integrity during recovery. The U-tube sampling methodology was developed to collect large volume, multiphase samples at in situ pressures. As a permanent or semi-permanent installation, the U-tube can be used for rapidly acquiring multiple samples or it may be installed for long-term monitoring applications. The U-tube was first deployed in Liberty County, TX to monitor crosswell CO2 injection as part of the Frio CO2 sequestration experiment. Analysis of gases (dissolved or separate phase) was performed in the field using a quadrupole mass spectrometer, which served as the basis for determining the arrival of the CO2 plume. The presence of oxygen and argon in elevated concentrations, along with reduced methane concentration, indicates sample alteration caused by the introduction of surface fluids during borehole completion. Despite producing the well to eliminate non-native fluids, measurements demonstrate that contamination persists until the immiscible CO2 injection swept formation fluid into the observation wellbore. [source] Synthesis of Microporous Carbon Nanofibers and Nanotubes from Conjugated Polymer Network and Evaluation in Electrochemical CapacitorADVANCED FUNCTIONAL MATERIALS, Issue 13 2009Xinliang Feng Abstract One-dimensional fibers and tubes are constructed through the oriented carbon-carbon cross-linking reactions towards rigid conjugated polymer networks. As the result, a template-free and one-step synthesis of CNTs and CNFs is achieved through a simple carbonization of the as-formed carbon-rich tubular and fiberlike polyphenylene precursors under argon. Microporous CNTs and CNFs with a surface area up to 900 m2 g,1 are obtained, together with HR-TEM characterizations indicating the formation of intrinsic microporous structure in these rigid carbon-rich networks. The primary electrochemical experiments reveal their promising applications as advanced electrodes in electrochemical double-layered capacitor (EDLC). [source] The Remarkable Thermal Stability of Amorphous In-Zn-O Transparent Conductors,ADVANCED FUNCTIONAL MATERIALS, Issue 20 2008Matthew P. Taylor Abstract Transparent conducting oxides (TCOs) are increasingly critical components in photovoltaic cells, low-e windows, flat panel displays, electrochromic devices, and flexible electronics. The conventional TCOs, such as Sn-doped In2O3, are crystalline single phase materials. Here, we report on In-Zn-O (IZO), a compositionally tunable amorphous TCO with some significantly improved properties. Compositionally graded thin film samples were deposited by co-sputtering from separate In2O3 and ZnO targets onto glass substrates at 100,°C. For the metals composition range of 55,84 cation% indium, the as-deposited IZO thin films are amorphous, smooth (RRMS,<,0.4,nm), conductive (,,,,3000,,,1,·,cm,1), and transparent in the visible (TVis,>,90%). Furthermore, the amorphous IZO thin films demonstrate remarkable functional and structural stability with respect to heating up to 600,°C in either air or argon. Hence, though not completely understood at present, these amorphous materials constitute a new class of fundamentally interesting and technologically important high performance transparent conductors. [source] Microporous Metal,Organic Frameworks with High Gas Sorption and Separation Capacity,ADVANCED FUNCTIONAL MATERIALS, Issue 8 2007Y. Lee Abstract The design, synthesis, and structural characterization of two microporous metal,organic framework structures, [M(bdc)(ted)0.5]·2,DMF·0.2,H2O (M,=,Zn (1), Cu (2); H2bdc,=,1,4-benzenedicarboxylic acid; ted,=,triethylenediamine; DMF: N,N -dimethylformamide) is reported. The pore characteristics and gas sorption properties of these compounds are investigated at cryogenic temperatures, room temperature, and higher temperatures by experimentally measuring argon, hydrogen, and selected hydrocarbon adsorption/desorption isotherms. These studies show that both compounds are highly porous with a pore volume of 0.65 (1) and 0.52,cm3,g,,1 (2). The amount of the hydrogen uptake, 2.1,wt,% (1) and 1.8,wt,% (2) at 77,K (1,atm; 1,atm,=,101,325,Pa), places them among the group of metal,organic frameworks (MOFs) having the highest H2 sorption capacity. [Zn(bdc)(ted)0.5]·2,DMF·0.2,H2O adsorbs a very large amount of hydrocarbons, including methanol, ethanol, dimethylether (DME), n -hexane, cyclohexane, and benzene, giving the highest sorption values among all metal,organic based porous materials reported to date. In addition, these materials hold great promise for gas separation. [source] | ||||||||||||||||||||||||||||||||||||||||