Atm Of Air Research Articles

Effect of Temperature on La<sub>1.85</sub>Sr<sub>0.15</sub>CuO<sub>4</sub> Single Crystal Growth by Floating Zone Method

Superconducting single crystals of La1.85Sr0.15CuO4 have been grown at various temperatures without single crystal seeds by the traveling-solvent floating-zone method. In order to avoid the formation of bubbles during the crystal growth process, a flowing atmosphere of 2 atm oxygen or 1 atm air was applied in different temperature range. It was found that the crystal quality could be improved by raising the growth temperature in a certain range, and the orientation changed from (110) to (100) at higher temperature. X-ray diffraction results showed that the full-width at half-maximum of the best as-prepared crystal was 0.086°. The crystals grown in 2 atm oxygen showed a superconducting transition temperature (Tc) of 37.3 K, while the crystals grown in floating air showed a Tc of about 35 K and it could be improved to 36.5 K by annealing in flowing oxygen.

Oxygen separation from compressed air using a mixed conducting perovskite-type oxide membrane

An oxygen separation tube with a composite structure in which a dense membrane is formed on a porous body was successfully fabricated using a newly developed mixed conducting oxide, SrCo 0.9Nb 0.1O 3− δ (SCN). Using the tube obtained, it was confirmed that high-purity oxygen was separated from compressed air. The permeation rate reached 9 cm 3 min − 1 cm - 2 at an oxygen collection rate of 20% under the condition of 900 °C and 10 atm air. It was also suggested that the oxygen separation rate followed the theoretical equation assuming a diffusion-limited process even in thin-membrane regions of, for example, 50 μm. From the measured permeation rate, oxide ionic conductivity was estimated to be around 100 S/m at 900 °C. Furthermore, stable oxygen separation from higher air pressure up to 20 atm was successfully observed, which proved the high stability of SCN as well as its superior permeability. The reliability of the fabricated separation tube was also confirmed through a long-term separation test over a half-year period conducted under 900 °C, 10 atm air.

Intelligent agent concepts in the modern library

PurposeIntelligent agents – software components designed to perform complex tasks for the user (with or without the presence of the user) – are used in a variety of settings, from instant messaging and web auctions, to ATM network management and air traffic control systems. The technology also has applicability within libraries, adding a level of user‐oriented control and flexibility to activities such as digital collection management and virtual reference. The use of intelligent agents to assist users with their searches has perhaps the greatest potential. The purpose of this article is to provide background information on the use of agent technology in information settings, and review three library‐based projects that utilize agent technology in a practical way.Design/methodology/approachA comprehensive literature review combined with brief case studies of practical applications of agent technology in three modern library settings. A conceptual model of a virtual, agent‐based personalized library is also presented.FindingsLibrarians and others in the information profession recognize the potential of agent technology within the library setting. The paper presents a number of practical scenarios for using agents, from supporting digital libraries and teaching information literacy to virtual reference.Practical implicationsThere are numerous implications for current and future use of agent technology in libraries, including how to engage IT staff in the development process, how to educate users about the benefits of the technology, and how to make sure library professionals have the skill set to allow them to participate in the conceptualization, design and implementation of agents.Originality/valueThere is a wealth of professional literature on agent technology and its uses, mostly from a computing or engineering perspective. This paper has value in that it presents the concept from a library perspective, and includes references to relevant library literature and projects.

Thermodynamics of chemical and electrochemical stability of corrosion active nonmetal inclusions

Diagrams potential-pH are plotted for different phase components of corrosive nonmetal inclusions in steels in sulfide-containing media at 25°C, 1 atm (air), and a i = 10−3 mol/l. Thermodynamic peculiarities of their corrosion and electrochemical behavior are analyzed.

Aerobic oxidation of cyclohexane with γ-alumina supported metallophthalocyanines in the gas phase

Abstract Unsubstituted phthalocyanines of Co, Fe and Mn supported on γ-alumina were synthesized and characterized with UV–vis and IR spectroscopic techniques. Catalytic activities of the supported phthalocyanines for oxidation of cyclohexane to cyclohexanol and cyclohexanone by air were studied in the gas phase in the absence of solvents and reducing agents. These metallophthalocyanines (MPc) supported on γ-alumina were effective catalysts in a temperature range of 300–400 °C at 1 atm of air. Under these reaction conditions, the order of catalytic activities is as follows: CoPc/γ-alumina > FePc/γ-alumina > MnPc/γ-alumina. When the reaction was catalyzed with γ-alumina without any phthalocyanines, the reaction yield and conversion were reduced considerably compared to those of supported γ-alumina. With 10% CoPc supported on γ-alumina and under our experimental conditions, the conversion percent of cyclohexane is 32.6% with 37.3% selectivity of cyclohexanol + cyclohexanone and 17.4% cyclohexene at 340 °C. To achieve higher conversion of cyclohexane and better selectivity toward cyclohexanone + cyclohexanol, factors such as type and percentage of the metallophthalocyanine, reaction temperature and space velocity were studied, and optimized conditions were investigated.

Comments on the size effect on the microcantilever quality factor in free air space

This study presents a numerical approach to investigate the size effect on the quality factor associated with the first mode of microcantilever vibration in 1 atm air. The numerical simulation results are verified by experiments and compared with the approximate analytical solutions. Bulk micromachined cantilever arrays are employed as the test vehicles. Based on the experimental and numerical results, this paper proposes a modification to the existing approximate models for air damping analysis by taking into account the geometry effects of the microcantilevers. The arrived semi-empirical equation suggests that the quality factors of the microcantilevers are approximately proportional to L −1.62 and b 0.62 at a low kinetic Reynolds number. Thus, the quality factor of the microcantilever resulting from the free space air can be precisely predicted for design purposes.

Characterization of an electropolymerized Pt(II) diamino phenyl porphyrin polymer suitable for oxygen sensing

The electropolymerization of di-phenyl-di-(4-aminophenyl)-porphyrin-Pt(II) and the application of this polymer to oxygen sensing using spectroscopic measurements is presented. The main advantage of this sensor is that the lumophore forms part of the sensing polymer. The absorption and luminescence spectra of the polymer retain the characteristic shape of the porphyrin monomer spectra indicating that the polymerization process does not perturb the porphyrin molecular orbitals. Images of the polymer surface obtained using atomic force microscopy suggest that a homogeneous polymer is formed and that the polymer structure grows in layers. The luminescence properties of this polymer are exploited for determining oxygen in the concentration range 0 to 0.2 atm (air). The weighted average luminescence lifetime of the polymer was found to vary from 63.7 µs to 30.9 µs in nitrogen and air environments respectively. The sensitivity of the polymer was determined from the Stern–Volmer plot which was linear over the concentration range studied giving a Stern–Volmer quenching constant (KSV) of 5.05 ± 0.14 atm−1.

A Study on Electric Conductivity of Phosphoric Acid Supported on Nano-Pore Rice Husk Silica in H2|Pt|H3PO4/RHS|Pt|O2 Fuel Cells

PEMFC (Polymer Electrolyte Membrane Fuel Cell) is widely considered as an energy conversion system from the chemical energy of hydrogen to electric energy. But, hydrogen fuel obtained from hydrocarbons has trace amount of carbon monoxide which is a potential poison for platinum electrode at the cell operating temperature approximately 100 degrees C and it becomes a huddle for the general usage of PEMFC. On the other hand PAFC (Phosphoric Acid Fuel Cell) operates at a higher temperature and the platinum electrode oxidizes carbon monoxide poison while there is a leakage problem of the liquid phase. To combine the advantages of two fuel cells, the electrolyte systems of phosphoric acid supported silica on ceramics are recently being tested. In this study, we investigated the nm pore rice husk silica as a support for phosphoric acid and tested the electric conductivity of the silica plate and the characteristics of a prototype fuel cell H2/Pt/H3PO4 / RHS/Pt/O2 at 100-200 degrees C. The conductivity of H3PO4/RHS was 8 mS cm(-1) above 175 degrees C under 200 torr H2O. In the fuel cell, the apparent conductance of the electrolyte from I-V characteristics was 2.45 mS/cm at 160 degrees C under 1 atm H2 and air at present.

High Temperature Oxidation of TiAl-1.5wt.%Mn-(0, 5, 10)wt.%Y<sub>2</sub>O<sub>3</sub> Alloys

TiAl-Mn-(0,5,10) wt.%Y2O3 alloys were prepared by the MA-SPS process, and their oxidation behavior was studied between 800 and 1000oC in 1 atm of air. The added Y2O3 particles were segregated along the matrix grain boundaries. The addition of (5~10) wt.%Y2O3, viz. (0.9~1.8) mol%Y2O3 increased the tendency to form the rutile phase along the grain boundaries, resulting in the increment of the oxidation rate and decrement of scale adherence. Mn was oxidized to Mn2O3. The primary mode of scale growth was the outward diffusion of Ti and Mn cations for the outer TiO2 scale, and the inward transport of oxygen anions for the inner (TiO2+Al2O3) mixed scale.

Fluorous Biphasic Catalytic Oxidation of Alkenes and Aldehydes with Air and 2‐Methylpropanal in the Presence of (β‐Perfluoroalkylated tetraphenylporphyrin)cobalt Complexes

AbstractA simple and facile fluorous biphasic catalytic oxidation of alkenes and aldehydes with 1 atm of air and 2‐methylpropanal in the presence of the (β‐perfluoroalkylated tetraphenylporphyrin)cobalt complexes [Co{TPP(C8F17)4}] (Co2) has been demonstrated for the first time. This kind of β‐perfluoroalkylated tetraphenylporphyrin may be used in other catalytic applications because of its ready availability and unique properties. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Room temperature oxidation of alcohols with 1 atm dioxygen and air catalyzed by a novel three-dimensional microporous ruthenium(II,III) 4,4′,4″,4‴-(21H,23H-porphine-5,10,15,20-tetrayl)tetrakisbenzoate tetrafluoroborate

A novel three-dimensional microporous ruthenium (II,III) polymer complex, [ Ru 2 II , III ( H 2 TCPP ) ] BF 4 ( 1) (H 2TCPP = 4,4′,4′,4‴-(21H,23H-porphine-5,10,15,20-tetrayl)tetrakis benzoic acid) was synthesized and characterized by elemental analysis, TG/DTA, magnetic susceptibility, FT-IR, diffuse reflectance UV–Vis, ESR, X-ray powder diffraction, BET analysis, and nitrogen and oxygen adsorption measurements. Complex 1 exhibited an effective catalytic performance for the heterogeneous oxidation of various types of alcohols, particularly primary aliphatic alcohols, with molecular oxygen and air without any additives at room temperature.

Measuring acetylene concentrations using a frequency chirped continuous wave diode laser operating in the near infrared

Two frequency chirped continuous wave diode lasers operating in the near infrared (IR) at wavelengths of lambda approximately 1.535 microm and lambda approximately 1.520 microm have been used to measure acetylene concentrations using the P(17) and R(9) rotational lines of the (nu1 + nu3) vibrational combination band. The diode lasers were frequency chirped by applying an electrical current pulse to the laser driver at a repetition rate of greater than 1 kHz. As the laser is operated at high repetition rates, more than 1000 spectra per second can, in principle, be acquired and summed, allowing fast accumulation of data, rapid averaging and consequent improvement of the signal to noise ratio and detection limit. Experiments were performed using a single-pass cell with a path length of 16.4 cm, and also an astigmatic multi-pass absorption cell aligned to give a path length of 56 m. Detection limits corresponding to minimum detectable absorption coefficients, alpha(min), of 5.6 x 10(-5) and 7.8 x 10(-8) cm(-1), respectively, were obtained over a 4 s detection bandwidth. These detection limits would correspond to mixing ratios of 21 parts per million by volume (ppmv) and 59 parts per billion by volume (ppbv) of acetylene at 1 atm in air, with the deleterious effects of pressure broadening accounted for. The single-pass cell was used to perform breakthrough volume (BTV) experiments for the low volume adsorbent traps used to pre-concentrate organic compounds in air, taking advantage of the capability of the system to measure concentrations in real time.

High Temperature Oxidation of Steels in Air and CO2–O2 Atmosphere

Three kinds of hot rolled steel slabs, viz. high strength steel, bake hardened steel and low carbon steel, were oxidized isothermally between 1100 and 1250 °C for up to 2 hr in 1 atm of air and an 85%N2–10%CO2–5%O2 gas mixture. The steels were oxidized in a similar fashion in both the atmospheres. The oxidation process followed an initial linear rate law, which then gradually transformed to a nearly parabolic rate law. Thick, porous and nonadherent scales formed rapidly, due to the high oxidation temperature. The scales formed consisted of Fe2O3,(Fe2O3+Fe3O4), (Fe3O4+Fe2O3 +FeO) and (FeO+Fe3O4) from the outer surface. The presence of supersaturated oxygen beneath the scale resulted in grain boundary oxidation and the formation of internal oxide precipitates.

Highly reactive catalysts for aerobic thioether oxidation: The Fe-substituted polyoxometalate/hydrogen dinitrate system

A new type of polyoxometalate (POM), one with a hydrogen dinitrate group associated with a d-electron-substituted polyoxometalate, Fe III[H(ONO 2) 2]PW 11O 39 5− ( 1), has been developed that catalyzes highly effective aerobic sulfoxidation (RR′S + 0.5 O 2 → RR′SO) under ambient conditions (1 atm of air at room temperature). Comparison of the rates for aerobic sulfoxidation of the mustard simulant 2-chloroethyl ethyl sulfide (CEES) catalyzed by 1 and several other species reported to be catalysts for this class of reactions, including NO +, NO 2, (NH 4) 2Ce IV(NO 3) 6 and Au IIICl 2NO 3(CH 3CN) indicate that 1 is clearly the most effective catalyst. Conversions and selectivities for the desired sulfoxide decontamination product (CEESO in these studies) are both effectively quantitative. The low or nonexistent catalytic activity of Fe II(NO)PW 11O 39 6−, Fe(NO 3) 3 and HNO 3 argues strongly that nitrosyl and nitrate derivatives of the Fe polyoxometalate and nitric acid are not species important in catalytic turnover. The techniques of single crystal X-ray diffraction, solution NMR, FTIR, TGA, DSC, cyclic voltammetry, elemental and wet chemical analyses were applied to the characterization of 1 and these are collectively consistent with the α-Keggin structure with a strongly associated hydrogen dinitrate group and a more weakly associated nitrate of crystallization.

Atmospheric Chemistry of CH3CHF2 (HFC-152a): Kinetics, Mechanisms, and Products of Cl Atom- and OH Radical-Initiated Oxidation in the Presence and Absence of NOx

Smog chamber/Fourier transform infrared (FTIR) and laser-induced fluorescence (LIF) spectroscopic techniques were used to study the atmospheric degradation of CH3CHF2. The kinetics and products of the Cl(2P(3/2)) (denoted Cl) atom- and the OH radical-initiated oxidation of CH3CHF2 in 700 Torr of air or N2; diluents at 295 +/- 2 K were studied using smog chamber/FTIR techniques. Relative rate methods were used to measure k(Cl + CH3CHF2) = (2.37 +/- 0.31) x 10(-13) and k(OH + CH3CHF2) = (3.08 +/- 0.62) x 10(-14) cm3 molecule(-1) s(-1). Reaction with Cl atoms gives CH3CF2 radicals in a yield of 99.2 +/- 0.1% and CH2CHF2 radicals in a yield of 0.8 +/- 0.1%. Reaction with OH radicals gives CH3CF2 radicals in a yield >75% and CH2CHF2 radicals in a yield <25%. Absolute rate data for the Cl reaction were measured using quantum-state selective LIF detection of Cl(2P(j)) atoms under pseudo-first-order conditions. The rate constant k(Cl + CH3CHF2) was determined to be (2.54 +/- 0.25) x 10(-13) cm3 molecule(-1) s(-1) by the LIF technique, in good agreement with the relative rate results. The removal rate of spin-orbit excited-state Cl(2P(1/2)) (denoted Cl) in collisions with CH3CHF2 was determined to be k(Cl + CH3CHF2) = (2.21 +/- 0.22) x 10(-10) cm3 molecule(-1) s(-1). The atmospheric photooxidation products were examined in the presence and absence of NO(x). In the absence of NO(x)(), the Cl atom-initiated oxidation of CH3CHF2 in air leads to formation of COF2 in a molar yield of 97 +/- 5%. In the presence of NO(x), the observed oxidation products include COF2 and CH3COF. As [NO] increases, the yield of COF2 decreases while the yield of CH3COF increases, reflecting a competition for CH3CF2O radicals. The simplest explanation for the observed dependence of the CH3COF yield on [NO(x)] is that the atmospheric degradation of CH3CF2H proceeds via OH radical attack to give CH3CF2 radicals which add O2 to give CH3CF2O2 radicals. Reaction of CH3CF2O2 radicals with NO gives a substantial fraction of chemically activated alkoxy radicals, [CH3CF2O]. In 1 atm of air, approximately 30% of the alkoxy radicals produced in the CH3CF2O2 + NO reaction possess sufficient internal excitation to undergo "prompt" (rate >10(10) s(-1)) decomposition to give CH3 radicals and COF2. The remaining approximately 70% become thermalized, CH3CF2O, and undergo decomposition more slowly at a rate of approximately 2 x 10(3) s(-1). At high concentrations (>50 mTorr), NO(x) is an efficient scavenger for CH3CF2O radicals leading to the formation of CH3COF and FNO.

Diagrams of Chemical and Electrochemical Stability of Thermal-Diffusion Zinc Coatings

Cutsets are calculated for the Zn-Fe-O system phase diagram at 700 and 298 K and the Zn-Fe-H2O system potential-pH diagram at 298 K, 1 atm (air), and a i = 10−6 mol/l with zinc excess (C Zn al > C Zn cr ) or deficiency (C Zn al < C Zn cr ) in the alloy surface layer of the Zn-Fe alloy. Thermodynamics of corrosion-electrochemical behavior of different phases in thermal-diffusion zinc coatings are discussed.

Pulsed volume discharge in a nonuniform electric field at a high pressure and the short leading edge of a voltage pulse

It is shown that a volume discharge is formed in a nonuniform electric field for the short leading edge of a voltage pulse and nanosecond pulse duration without any additional preionisation source in various gases at pressures higher than atmospheric (6 atm in helium and 3 atm in nitrogen). Lasing at atomic transitions in Xe is obtained in an Ar—Xe mixture under a pressure of 1.2 atm for an active length of 1.5 cm. A record-high specific power input (more than 0.8 GW cm-3 under a pressure 1 atm in air) is realised in the volume discharge stage. The volume discharge is formed due to preionisation of the discharge gap by fast electrons accelerated due to amplification of the electric field in the cathode region and in the gap. In a nonuniform electric field, volume discharge is realised under a quasistationary voltage from 10 to 180 kV across the gap, at a pulse repetition rate of up to 160 Hz and for various discharge gap geometries.

Directional solidification of [formula omitted] ferroelectric crystals at 1 and 7 atm

Single crystals of 0.65 Pb ( Mg 1 / 3 Nb 2 / 3 ) O 3 – 0.35 PbTiO 3 were directionally solidified from the melt exposed to 7 atm air pressure (7 atm). The X-ray studies show that the obtained crystals have rhombohedral or tetragonal structure depending on the composition. In contrast to the experiments conducted at atmospheric pressure, the experiments conducted under 7 atm of air yielded transparent light-yellow crystals, free of pyrochlore phase. The temperature and frequency dependence of the dielectric constant and dielectric loss demonstrate a relaxor ferroelectric behavior. The room temperature dielectric constant ε measured on unpoled (0 0 1) oriented specimens is 8200, demonstrating high crystalline perfection.

Co-containing polyoxometalate-based heterogeneous catalysts for the selective aerobic oxidation of aldehydes under ambient conditions

Tetra- n-butylammonium (TBA) salts of the cobalt-monosubstituted Keggin polyoxometalate (Co-POM), TBA 4HPW 11CoO 39 ( I) and TBA 5PW 11CoO 39 ( II), have been prepared and characterized by using elemental analysis, potentiometric titration, IR, UV–vis, 31P NMR, and cyclic voltammetry. Different modes of heterogenization of the Co-POM, including anchoring to both NH 2- and NH 3 +-modified mesoporous silica surfaces and sol–gel synthesis, have been performed. The resulting solid catalysts were characterized by N 2-adsorption measurements, elemental analysis, DR-UV–vis, and FT-IR spectroscopy. The activity of the solid Co-POM materials to catalyze aerobic oxidation of two representative aldehydes, isobutyraldehyde (IBA) in MeCN and formaldehyde in H 2O under mild conditions (20–40 °C, 1 atm of air), was assessed and compared with the catalytic activity of the corresponding homogeneous Co-POMs. An emphasis has been placed on leaching tests and catalyst recycling. The effect of protonation of the amine-modified silica surface or the Co-POM on the loading, stability, and activity of the Co-POM solid catalyst was evaluated.

Absorption cross-sections and pressure broadening of rotational lines in the ν5+ ν9band of ethene measured by diode laser cavity ring down spectroscopy

Absorption cross sections are reported for several rotationally resolved lines in the QQ-branch of the ν5 + ν9 combination vibrational band of ethene (ethylene) at wavelengths around 1.625 μm. The measurements were made using cavity ring-down spectroscopy with a near infra-red diode laser. In the strongest region of the band, a line-integrated absorption cross section for the QQ4(4) feature of 5.08 ± 0.38 × 10−22 cm2 molecule−1 cm−1 is obtained, with a peak cross section at line centre of 3.23 ± 0.03 × 10−20 cm2 molecule−1. The effects of addition of pressures of up to 200 Torr of air on spectral linewidths are analysed to obtain an air broadening coefficient (HWHM) of γ = 0.1060 ± 0.0011 cm−1 atm−1. In 1 atm of air, the line centre absorption cross sections in the QQ4 branch are reduced by a factor of ∼8 because of line broadening. The consequences of these data for direct monitoring of ethene in the atmosphere using sensors based on diode laser cavity ring-down spectroscopy are discussed.