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Conditions.
Kinds of Conditions. Selected AbstractsAn educational tool for controlling of SRMCOMPUTER APPLICATIONS IN ENGINEERING EDUCATION, Issue 4 2008Tuncay Yigit Abstract This article introduces an educational tool for a switched reluctance motor (SRM) drive system. It is prepared for undergraduate and graduate level students. Classical PI and Genetic PI controllers are used in SRM drive system. The Genetic PI controller was applied to the speed loop, replacing the classical PI controller. The tool software was implemented using C++ Builder on a PC. It has flexible structure and graphical interface. The students can be easily establishing a thorough understanding of both classical PI and genetic PI controller for a SRM drive system. The education tool allowed the student to interact with the SRM drive system and it is using controllers. Then it is responses on a dynamic and instantaneous basis under different operating conditions. © 2008 Wiley Periodicals, Inc. Comput Appl Eng Educ 16: 268,279, 2008; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae20148 [source] NMR in photo-induced chemical exchange systems.CONCEPTS IN MAGNETIC RESONANCE, Issue 5 2006-dipyridyl)ethene photoisomerization kinetics, Double-resonance inverse fractional population transfer application for investigation of Abstract The analytical expression describing the dynamics of nuclear magnetization with the use of double-resonance NMR by the procedure of inverse fractional population transfer in requirements of photo-induced chemical exchange (PICE) is obtained in this article. Laser-induced (, = 308 nm) photoisomerization of 1,2-(2,2,-dipyridyl)ethene was studied by NMR and UV absorption spectroscopy under irreversible and photostationary conditions. © 2006 Wiley Periodicals, Inc. Concepts Magn Reson Part A 28A: 337,346, 2006 [source] On Kinetic Effects during Parallel Transport in the SOLCONTRIBUTIONS TO PLASMA PHYSICS, Issue 1-3 2008D. Tskhakaya Abstract 1D kinetic (PIC) and fluid simulations have been performed in order to study boundary conditions and heat flux and viscosity limiting coefficients in the inter-ELM and ELMy SOLs. Simulated plasma parameters correspond to the JET SOL under different conditions. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Sheath Physics and Boundary Conditions for Edge PlasmasCONTRIBUTIONS TO PLASMA PHYSICS, Issue 1-3 2004R. H. Cohen Abstract The boundary conditions of mass, momentum, energy, and charge appropriate for fluid formulations of edge plasmas are surveyed. We re-visit the classic problem of 1-dimensional flow, and note that the "Bohm sheath criterion" is requirement of connectivity of the interior plasma with the external world, not the result of termination of the plasma by a wall. We show that the nature of the interior plasma solution is intrinsically different for ion sources that inject above and below the electron sound speed. We survey the appropriate conditions to apply, and resultant fluxes, for a magnetic field obliquely incident on a wall, including the presence of drifts and radial transport. We discuss the consequences of toroidal asymmetries in wall properties, as well as experimental tests of such effects. Finally, we discuss boundary-condition modifications in the case of rapidly varying plasma conditions. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Solvothermal production of CdS nanorods using polyvinylpyrrolidone as a templateCRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2009Titipun Thongtem Abstract CdS nanorods were solvothermally produced using Cd(NO3)2 and S powder in ethylenediamine containing different amounts of polyvinylpyrrolidone (PVP). The phase with hexagonal structure was detected using X-ray diffraction (XRD) and selected area electron diffraction (SAED). Their SAED patterns were in accordance with those of the simulations. Scanning and transmission electron microscopies (SEM and TEM) revealed the presence of CdS nanorods with their lengths influenced by different amounts of PVP. The nanorods were also characterized using high resolution TEM (HRTEM). They grew in the [001] direction normal to the (002) parallel crystallographic planes composing the nanorods. Raman spectra showed the 1LO (first harmonic) and 2LO (second harmonic) modes at the same wavenumbers although the products were produced under different conditions. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Numerical modeling and investigation of liquid phase epitaxy of Hg1,xCdxTe infrared detectorsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2005K. Lin Abstract Numerical investigations have been performed for modeling the global temperature field of an industrial liquid phase epitaxy (LPE) facility and to estimate the temperature fluctuations in a Te-rich solution during the LPE growth. The numerical results agreed well with experimental data and therefore provide reliable reference points for experimenters for further improvements of the growth conditions. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The effect of alloying elements on the crystallization behaviour and on the properties of galvanized coatingsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 1 2004G. Vourlias Abstract The influence of the alloying elements on the interface reactions of zinc coatings during the galvanization process was examined. These reactions affect the crystallization and the structure and properties of the outer layer of the coatings. Depending on the type and concentration of the alloying additions in the galvanizing bath differences were induced in the crystallization process of the Fe-Zn phases. It was found that both the concentration and the distribution of the alloying elements played an important role in the growth of the phases. The formation of the phases and the distribution of the alloying elements in the coatings were determined using X-Ray diffraction (XRD) and Scanning Electron Microscopy (SEM) associated with an Energy Dispersive X-Ray Spectroscopy (EDS) analysis. Finally the behaviour of the galvanized coatings was examined under accelerated salt spray corrosion conditions. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Long maternal separation has protective effects in rats exposed to activity-based anorexiaDEVELOPMENTAL PSYCHOBIOLOGY, Issue 8 2009O. Carrera Abstract This study examined the effect of three neonatal treatments of maternal separation during infancy in young adult rats exposed to standard activity-based anorexia (ABA) consisting of food restriction plus free access to an activity wheel. During the first 20 postnatal days of life rat pups were exposed to periods of either brief maternal separation (BMS, 15,min), long maternal separation (LMS, 180,min), or were non-handled (NH). Thereafter, male and female rats were exposed to ABA. Neonatal treatment produced no significant differences in the survival time of male rats, whereas survival was greater in female rats exposed to LMS than in NH rats under ABA procedure. In conclusion, prolonged maternal separation appears to promote resistance in female animals subjected to harsh ABA life-threatening conditions. © 2009 Wiley Periodicals, Inc. Dev Psychobiol 51: 616,624, 2009 [source] An agent-based scheduling method enabling rescheduling with trial-and-error approachELECTRICAL ENGINEERING IN JAPAN, Issue 1 2007Hiroyasu Mitsui Abstract Scheduling optimization is an extremely difficult problem; therefore, many scheduling methods such as linear programming or stochastic searching have been investigated in order to obtain better solutions close to the optimum one. After obtaining a certain solution, scheduling managers may need to reschedule another solution that corresponds to changes in requirements or resources. However, rescheduling problems become more difficult as they become larger in scale. In this paper, we propose an agent-based rescheduling system using the linear programming approach. In our system, agents can autonomously conduct rescheduling on behalf of managers by repeated trial and error in balancing loads or changing the priority of resource allocation until it reaches a better solution for the requirement is obtained. In addition, managers can engage in trial and error with the help of agents to seek a better solution by changing constraint conditions. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 159(1): 26,38, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20434 [source] Bis(terdentate) Pyrazole/Pyridine Ligands: Synthesis, Crystal Structures and Magnetic Properties of Bridged Binuclear and Tetranuclear Copper(II) ComplexesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 23 2009Akhilesh Kumar Singh Abstract A new binucleating bis(terdentate) ligand, 3,5-[3-bis(2-pyridyl)pyrazole-1-ylmethyl]pyrazole (HL2), was synthesized. Reaction of the deprotonated ligand L2 with hydrated CuII salts gives (,-pyrazolato)(,-hydroxido)-bridged binuclear and tetranuclear complexes [L2Cu2(,-OH)(ClO4)(MeCN)](ClO4) (2), [L2Cu2(dmf)2(,3 -OH)]2(ClO4)4·4dmf (3·4dmf) and [L2L,Cu2](ClO4)2 [4; HL, = 3-(2-pyridyl)pyrazole]. In these complexes, both ,-OH and ,3 -OH bridges were observed. This contrasts the situation for a dicopper(II) complex of the related bis(terdentate) ligand 3,5-bis[6(2,2,-dipyridyl)]pyrazole (HL1), {L1Cu2(OMe)(MeOH)[,1 - O -(NO3)]}{[Cu2(NO3)2(,-OMe)2]}0.5·MeOH (1·MeOH), where the shorter and more rigid ligand side arms enforce a larger Cu···Cu separation and the formation of a MeO,HOMe moiety within the bimetallic pocket. Molecular structures of all complexes were elucidated by X-ray crystallography. Variable-temperature magnetic susceptibility measurements (295,2 K) for powdered samples of complexes 2,4 reveal strong antiferromagnetic coupling between two copper centres. The magnitude of the coupling is discussed in view of the structural features. During the preparation of complex 4, partial ligand hydrolysis was also observed, but this strongly depends on the reaction conditions.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Direct Synthesis of Zr-Containing Hybrid Periodic Mesoporous Organosilicas with Tunable Zirconium ContentEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 35 2007Shang-Ru Zhai Abstract Highly ordered Zr-containing periodic mesoporous organosilicas (ZrPMO) with different Zr/Si ratios were successfully synthesized, for the first time, by employing a ZrOCl2/NaCl combination as the promoting agent and by simply adjusting the molar ratio of the zirconium species to the organosilica precursor; no addition of mineral acids was necessary. The effect of preparation parameters on the structural and textural properties were carefully investigated by using different ratios of NaCl/Si and Zr/Si. It was found that both salts are essential for this system and highly ordered ZrPMOs can be prepared within fairly wide Si/Zr ratios (5,100) while keeping the NaCl/Si ratio constant. To prove the effectiveness of this synthetic pathway with a higher Zr incorporation, ZrPMO materials were also synthesized under strongly acidic conditions for the purpose of comparison. The synthesized ZrPMO materials were thoroughly characterized by ICP-AES, SAXS, N2 sorption, TEM, SEM, 13C CP/29Si MAS NMR spectroscopy, XPS, and TGA. Elemental analyses show that the amount of Zr incorporated into ZrPMO, which was synthesized under mild conditions, is greater than that obtained in a strongly acidic environment, and the Zr content, with a Si/Zr ratio up to 12, is close to that in the initial gel composition. A plausible assembly mechanism based on the synergistic effect of both "nonhydrolyzable" (NaCl) and "hydrolyzable" (ZrOCl2) inorganic salts was discussed in detail, where the "salting out" effect and self-generated acidity from both inorganic salts, respectively, are believed to be key factors for the formation of ordered SBA-15-type ZrPMO materials under the synthetic conditions.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] A Two-Dimensional, Hydrogen-Bond-Cross-Linked Molybdenum(VI) Network Polymer with Catalytic ActivityEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 9 2007Yi Luan Abstract The new hybrid inorganic,organic polymer [MoO2Cl2(H2O)2]·(H2dipy-pra)Cl2 (1), where dipy-pra = 1,3-bis(4-pyridyl)propane, has been synthesized and crystallographically characterized. MoO2Cl2(H2O)2 and the [H2dipy-pra]2+ cation are cross-linked by Mo,H2O···Cl and H2dipy-pra···Cl hydrogen bonds to form a two-dimensional layer structure. Complex 1 is an efficient catalyst, with H2O2 as the oxygen-source oxidant and NaHCO3 as the cocatalyst, in the epoxidation of olefinic compounds under ambient conditions.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Current-Voltage Characterisation of Monolayer-Supported Au-Nanoclusters by Scanning Tunnelling Microscopy under Ambient ConditionsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2005Volker Jacobsen Abstract The current-voltage characteristics of a double-tunnel junction based on a gold crystallite with a diameter of ca. 2 nm, separated from a gold surface by ca. 1 nm was investigated by scanning tunnelling microscopy. The sample architecture was built by attaching gold nanoparticles covered with 2-mercaptosuccinic acid to an atomically flat gold surface which was covered by a self-assembled monolayer (SAM) of 6-amino-1-hexanethiol. Surface plasmon and infrared spectroscopy as well as STM imaging were employed to identify suitable preparation conditions and prove the existence of the desired architecture. No reproducible steps in the current-voltage characteristics are observed on this system under ambient conditions. Nonetheless, a sound signature for tunnelling through the double-tunnel junction is established by a quantitative fit of the averaged experimental data to a theoretical model of a single-tunnel junction. Firstly, the current on the particle is strongly reduced at low absolute external voltage and secondly the current voltage characteristics are asymmetric. Since both deviations from theory are absent in reference experiments on the bare monolayer, they may serve as a robust signature for double-tunnel junctions and open the door to the investigation of single-electron tunnelling under ambient conditions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Nd(OTf)3 -Catalyzed Cascade Reactions of Vinylidenecyclopropanes with Enynol: A New Method for the Construction of the 5,7,6 Tricyclic Framework and Its Scope and LimitationsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 24 2009Liang-Feng Yao Abstract We report in this paper a Lewis acid [Nd(OTf)3]-catalyzed protocol to construct compounds containing a 5,7,6 tricyclic framework in good yield from readily accessible starting materials vinylidenecyclopropanes (VDCPs) 1 and enynols 2a,c under mild conditions. Upon examination of the scope and limitations of this reaction, it was found that the corresponding highly functionalized cyclopentane derivatives could be formed in good yields from the reaction VDCPs 1 and enol 2e or dienol 2c under identical conditions.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] From Central to Axial to Central Chirality: Enantioselective Construction of the trans -4,5,9,10-Tetrahydroxy-9,10-dihydrophenanthrene SystemEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 34 2007Georgi Stavrakov Abstract Enantioselective synthesis of the core trans -4,5,9,10-tetrahydroxy-9,10-dihydrophenanthrene parent system of the antibiotics benanimicin, pradimicin and FD 594 has been accomplished. The synthesis employs a chiral tether approach and makes use of efficient central to axial to central chirality transfer. Key to success was an "imine-directed" atropdiastereoselective Ullmann coupling under mild reaction conditions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Synthesis of Tyrosine-Derived Tetrahydroisoquinolines by Lewis Acid Catalyzed Cyclization of N -(Phenylsulfonyl)alkyloxazolidinones,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 33 2007Stefan Tussetschläger Abstract N -Boc-protected tyrosine esters 5a,b were converted into tetrahydroisoquinolines 13 and 14 in four steps by reduction and ring closure to oxazolidinones 9 and 10, addition of benzenesulfinic acid and aldehydes to sulfones 11 and 12 and subsequent Lewis acid catalyzed cyclization. In the case of m -tyrosine derivative 5a, selective protection with bromine prevented the formation of undesired regioisomers. Debromination of target compounds 13 was readily achieved under radical reduction conditions by using Bu3SnH/AIBN. Tetrahydroisoquinolines 13 and 14 were isolated as single diastereomers whose trans configuration was confirmed by X-ray crystal structure analysis. Partial epimerization of trans - 13i and trans - 21 to the corresponding cis diastereomers was achieved under basic conditions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Structural Determination of the O-Chain Polysaccharide from the Lipopolysaccharide of the Haloalkaliphilic Halomonas pantelleriensis Bacterium,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 7 2006M. Michela Corsaro Abstract The structural determination of the O-chain repeating unit of the lipopolysaccharide from the haloalkaliphilic Halomonas pantelleriensis bacterium is described. The structure of the repeating unit was suggested on the basis of chemical analysis and NMR and MS data. The 4- O -[(S)-1-carboxyethyl]- D -GlcA residue has been found for the first time in a lipopolysaccharide, being previously only found in capsular polysaccharides. A comparison of the O-chain structures of Halomonas magadiensis and H. pantelleriensis is also reported. The results show that both bacteria present lipopolysaccharides containing a high number of carboxylate groups whose salification might determine a protective buffer effect on bacterium against extreme life conditions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Toward Diels,Alder Reactions on a Solid Support Using Polymer Bound N -Substituted 3-Hydroxy-4,4-dimethyl-2-pyrrolidinone Acrylate DerivativesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 11 2004Rhalid Akkari Abstract Several N -substituted 3-hydroxy-4,4-dimethyl-2-pyrrolidinone acrylate derivatives, selected to allow their attachment to a polymer, have been prepared and tested as dienophiles in the Diels,Alder reaction. The experiments, performed under TiCl4 catalysis in solution or the solid phase with isoprene and cyclopentadiene as dienes, pointed out the difficulties associated with some of these compounds that failed to give the corresponding cycloadduct. 13C NMR studies provided some evidence regarding the nature of the interactions between the acrylate compounds and TiCl4. It appears that the outcome of the reaction is dependent on the acrylate structure and that the 4-(3-hydroxy-4,4-dimethyl-2-oxopyrrolidin-1-yl)benzoic acid acrylate derivatives are highly efficient to give the cycloadduct in good yield and with high regio- or endoselectivity in both solution and solid-phase reaction conditions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Total Synthesis without Protection: Three-Step Synthesis of Optically Active Clavicipitic Acids by a Biomimetic RouteEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2004Yuusaku Yokoyama Abstract A three-step synthesis of a mixture of optically active cis - and trans -clavicipitic acids 6, which are ergot alkaloids, was achieved, starting from 4-bromoindole (7) and dl -serine (dl - 2). This short synthesis was made possible by omitting the protection and deprotection steps from the synthetic route. The key step was the spontaneous cyclization of 4-vinyltryptophan (10) formed from the Heck reaction of 4-bromotryptophan (8) with 2-methyl-3-buten-2-ol (9) in aqueous media. During this investigation, we also found that the palladium-catalyzed reaction of 8 with 9 showed an interesting pH dependence; under strongly basic conditions, the Heck reaction occurred to give a C4 -vinylated product 10, whereas an N -allylated product 19b was formed under neutral or weakly basic conditions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] P2Y1 receptor signaling enhances neuroprotection by astrocytes against oxidative stress via IL-6 release in hippocampal culturesGLIA, Issue 3 2009Takumi Fujita Abstract Cell survival is a critical issue in the onset and progression of neurodegenerative diseases and following pathological events including ischemia and traumatic brain injury. Oxidative stress is the main cause of cell damage in such pathological conditions. Here, we report that adenosine 5,-triphosphate (ATP) protects hippocampal astrocytes from hydrogen peroxide (H2O2)-evoked oxidative injury in astrocyte monocultures. The effect of ATP was prevented by a selective antagonist of or siRNAs against P2Y1R. Interestingly, in astrocyte-neuron cocultures, ATP also produced neuroprotective effects against H2O2 -evoked neuronal cell death, whereas ATP did not produce any neuroprotective effects in monocultures. The ATP-induced neuroprotection in cocultures was completely inhibited by silencing of astrocytic P2Y1R expression, indicating that ATP acts on astrocytes and enhances their neuroprotective functions by activating P2Y1R. Furthermore, this neuroprotective effect was mimicked by applying conditioned medium from astrocytes that had been stimulated by ATP, implying an involvement of diffusible factors from astrocytes. We found that, in both purified astrocyte cultures and astrocyte-neuronal cocultures, ATP and the P2Y1R agonist 2-methylthioadenosine 5, diphosphate (2MeSADP) induced the release of interleukin-6 (IL-6), but this did not occur in neuron monocultures. Moreover, exogenous IL-6 produced a neuroprotective effect, and the neuroprotection induced by P2Y1R-stimulated astrocytes was prevented in the presence of an anti-IL-6 antibody. Taken together, these results suggest that P2Y1R-stimulated astrocytes protect against neuronal damage induced by oxidative stress, and that IL-6 is a crucial signaling molecule released from astrocytes. Thus, activation of P2Y1R in astrocytes may rescue neurons from secondary cell death under pathological conditions. © 2008 Wiley-Liss, Inc. [source] Transfer or adapt business practices internationally?GLOBAL BUSINESS AND ORGANIZATIONAL EXCELLENCE, Issue 3 2010Some answers from Southeast Asia International organizations have long been torn between transferring their existing practices into new locations or adapting to local conditions. A major miscalculation can have extremely negative consequences for companies as they expand internationally. An examination of business practices in the Theravada Buddhist countries of Southeast Asia illustrates how breaking down business practices into their strategic, tactical, and operational levels may provide a useful guide for setting up initial operations in a foreign environment. It is proposed that strategic principles can be transferred but strategic practices should adapt to local conditions; tactical-level business practices will generally need to adapt to the local environment, while it is likely that best practices at the operational level can be transferred across international borders with little need to adapt to local conditions. © 2010 Wiley Periodicals, Inc. [source] Convective heat transfer and pressure drop of annular tubes with three different internal longitudinal finsHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 1 2008Lin Tian Abstract Pressure drop and heat transfer characteristics of air in three annular tubes with different internal longitudinal fins were investigated experimentally at uniform wall heat flux. The tested tubes have a double-pipe structure with the inner blocked tube as an insertion. Three different kinds of fins, plain rectangle fin, plain rectangle fin with periodical ridges and wave-like fin, were located peripherally in the annulus. The friction factor and Nusselt number can be corrected by a power-law correction in the Reynolds number range tested. It was found that the tube with periodical ridges on the plain fin or with wave-like fin could augment heat transfer; however, the pressure drop was increased simultaneously. In order to evaluate the comprehensive heat transfer characteristics of the tested tubes, two criteria for evaluating the comprehensive thermal performance of tested tubes were adopted. They are: 1) evaluating the comprehensive heat transfer performance under three conditions: identical mass flow, identical pumping power, and identical pressure drop; 2) the second law of thermodynamics, i.e., the entropy generation. According to the two different evaluating methods, it was found that the tube with wave-like fins provided the most excellent comprehensive heat transfer performance among the three tubes, especially when it was used under higher Reynolds number conditions. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 37(1): 29,40, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20186 [source] Prediction of critical heat flux on natural convective boiling in vertical short-thick tube submerged in saturated liquidHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 5 2003Zhen-Hua Liu Abstract An experimental and semitheoretical study was carried out for the critical heat flux (CHF) on natural convective boiling in uniformly heated vertical short-thick tubes and vertical short-thick annular tubes submerged in saturated liquids. By adapting a mathematical dealing method based on the theoretical formulas of CHF of both the natural convective boiling in vertical narrow-long tubes and the pool boiling, a simple semitheoretical formula was derived. The new formula expands the prediction range of CHF from pool boiling of vertical plates to very long vertical tubes and agrees well with the data of the tubes, annular tubes submerged in water or other liquids under various pressure conditions. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(5): 402,410, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.10103 [source] Thiiranation of 2,-adamantylidene-9-benzonorbornenylidene using 4,4,-oligothiodimorpholine and brønsted acidHETEROATOM CHEMISTRY, Issue 1 2009Yoshiaki Sugihara On leaving 4,4,-dithiodimorpholine 6 powder undisturbed at room temperature over 10 years, it led to the formation of 4,4,-tetrathiodimorpholine 7. Reactions of 2,-adamantylidene-9-benzonorbornenyidene 1 with 6, 7, and 4,4,-thiodimorpholine 8 and a Brønsted acid in CH2Cl2 at room temperature proceeded to afford the corresponding thiiranes, 2 and 3. The order of reactivity of 4,4,-oligothiodimorpholines combined with a Brønsted acid is 7 > 6 > 8. The thiirane 3 was transformed to 1 and 2 under the reaction conditions. © 2009 Wiley Periodicals, Inc. Heteroatom Chem 20:12,18, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20505 [source] Triphenylphosphine catalyzed formation of functionalized 2-aminothiophenesHETEROATOM CHEMISTRY, Issue 3 2007David Virieux Triphenylphosphine was used as a nucleophilic catalyst in the addition,cyclization reaction of phenyl isothiocyanate with electron-deficient allenes. This strategy offers a new approach for the synthesis of 2-aminothiophenes under neutral conditions. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:312,315, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20300 [source] Conversion of bis(o -nitrophenyl)diselenides to heterocycles containing selenium and nitrogen with the aid of samarium diiodideHETEROATOM CHEMISTRY, Issue 4 2002Xiaoyuan Chen Treatment of bis(o-nitrophenyl)diselenides with SmI2 led to simultaneous reduction of nitro groups and reductive cleavage of SeSe bonds as well as to the formation of the intermediates 2. The intermediates 2 were "living" double-anions formed in situ, and reacted readily with ,-bromoketones and ,-bromocarboxylic acid derivatives to afford the desired 2H-1,4-benzoselenazines and 2H-1,4-benzoselenazin-3(4H)-ones, respectively, in moderate to high yields and under mild conditions. © 2002 Wiley Periodicals, Inc. Heteroatom Chem 13:302,306, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/hc.10034 [source] First-order stochastic cellular automata simulations of the lindemann mechanismINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 4 2004Chad A. Hollingsworth The Lindemann mechanism explains how apparent unimolecular chemical reactions arise from bimolecular collisions. In this mechanism an ingredient M activates reactants A through collisions, and the resulting activated species A* can either decay to products P or be deactivated back to A, again via collisions with M. A first-order stochastic cellular automata model described previously [Seybold, Kier, and Cheng, J Chem Inf Comput Sci 1997, 37, 386] has been modified to simulate this mechanism. It is demonstrated that this model accurately reflects the salient features of the Lindemann mechanism, including the normal second-order kinetic behavior at low [M] and apparent first-order kinetics at high [M]. At low [M] the mechanism is equivalent to a rate-limited sequential process, whereas at high [M] it becomes a preequilibrium with leakage to products. The model also allows an examination of the validity of the steady-state approximation normally employed in a deterministic analysis of this mechanism, and it is seen that this approximation is not well justified under reasonable conditions. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 230,237 2004 [source] Catalytic cracking, dehydrogenation, and aromatization of isobutane over Ga/HZSM-5 and Zn/HZSM-5 at low pressuresINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 8 2002Yanping Sun Isobutane cracking, dehydrogenation, and aromatization over Ga/HZSM-5 and Zn/HZSM-5 has been investigated in a Knudsen cell reactor and the kinetics of the primary reaction steps for isobutene and propene formation have been accurately determined. Although cracking is the dominant reaction channel, with propene and methane being primary products, methane formation is significantly less than propene formation. This indicates that a proportion of the cracking proceeds via Lewis acid attack at CC bonds, and not just via alkanium ion formation at Bronsted acid sites. This is particularly apparent over Zn/HZSM-5. Intrinsic rate constants for cracking, calculated from the rate of propene formation, are and for dehydrogenation, calculated from the rate of isobutene formation, are Large preexponential factors for cracking and dehydrogenation over Ga/HZSM-5 indicate that either the coverage of active sites is significantly less than the coverage of exposed sites or the intrinsic reaction step involves a large entropy change between reactant and transition state. For Zn/HZSM-5 the small preexponential factors suggest either small entropy changes during activation, perhaps initiated by Lewis acid sites, or a steady-state distribution of active and exposed sites is rapidly reached. Differences in intrinsic activation energies may reflect the ratio of Lewis and Bronsted acid sites on the respective catalyst surfaces. Aromatization is more prolific over Ga/HZSM-5 than over Zn/HZSM-5 under the low-pressure conditions. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 467,480, 2002 [source] Some methodological problems concerning nonisothermal kinetic analysis of heterogeneous solid,gas reactionsINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 10 2001P. Budrugeac Isoconversional methods, those using only one curve , = ,(T) (, is the conversion degree and T is the temperature), and invariant kinetic parameter method were applied to estimate the kinetic parameters from the following nonisothermal data: (1) simulated TG curves for a single reaction; (2) TG curves for thermal degradation of PVC; and (3) TG curves for the dehydration of CaC2O4·H2O. The results obtained by applying various methods for the same system are compared and discussed. Finally, a procedure of kinetic analysis is suggested. Its application could lead to kinetic parameter values that can be used to predict either , = ,(t) curves for other heating rates or , = ,(T) curves for isothermal conditions. © 2001 John Wiley & Sons, Inc. Int J chem Kinet 33: 564,573, 2001 [source] Color invariant object recognition using entropic graphsINTERNATIONAL JOURNAL OF IMAGING SYSTEMS AND TECHNOLOGY, Issue 5 2006Jan C. van Gemert Abstract We present an object recognition approach using higher-order color invariant features with an entropy-based similarity measure. Entropic graphs offer an unparameterized alternative to common entropy estimation techniques, such as a histogram or assuming a probability distribution. An entropic graph estimates entropy from a spanning graph structure of sample data. We extract color invariant features from object images invariant to illumination changes in intensity, viewpoint, and shading. The Henze,Penrose similarity measure is used to estimate the similarity of two images. Our method is evaluated on the ALOI collection, a large collection of object images. This object image collection consists of 1000 objects recorded under various imaging circumstances. The proposed method is shown to be effective under a wide variety of imaging conditions. © 2007 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 16, 146,153, 2006 [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||