bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stereoselective degradation of fungicide triadimenol in cucumber plants
Authors: Dong Fengshou , Liu Xingang , Zheng Yongquan , Cao Qiao , Li Chongjiu 
Published: June 2009

AbstractThe stereoselective degradation of triadimenol in different cucumber plant tissues (root, stem, leaf, and fruit) has been investigated. Rac‐triadimenol was applied to cucumber plants by root irrigation mode under field conditions. The degradation kinetics and the enantiomer fraction were determined by normal‐phase high‐performance liquid chromatography with diode array detector and on‐line optical rotatory dispersion detector on Chiralpak® AS‐H column. It has been shown that the degradation of triadimenol in cucumber plants was stereoselective under field conditions. The results indicated that RS enantiomer was degraded faster than SR enantiomer, and SS enantiomer was degraded faster than RR enantiomer, which resulted in plants enriched with SR and RR enantiomers. Furthermore, it was found that leaf was the dominating location for triadimenol enantiomer accumulation and stereoselective degradation, comparing with the root, stem, and fruit tissue. Chirality 2010. © 2009 Wiley‐Liss, Inc.
The stereodynamics of 1,2‐dipropyldiaziridines
Authors: Trapp Oliver , Sahraoui Laila , Hofstadt Werner , Könen Werner 
Published: June 2009

AbstractN‐alkylated trans‐diaziridines are an intriguing class of compounds with two stereogenic nitrogen atoms which easily interconvert. In the course of our investigations of the nature of the interconversion process via nitrogen inversion or electrocyclic ring opening ring closure, we synthesized and characterized the three constitutionally isomeric diaziridines 1,2‐di‐n‐propyldiaziridine 1, 1‐isopropyl‐2‐n‐propyldiaziridine 2, and 1,2‐diisopropyldiaziridine 3 to study the influence of the substituents on the interconversion barriers. Enantiomer separation was achieved by enantioselective gas chromatography on the chiral stationary phase Chirasil‐β‐Dex with high separation factors α (1‐isopropyl‐2‐n‐propyldiaziridine: 1.18; 1, 2‐diisopropyldiaziridine: 1.24; 100°C 50 kPa He) for the isopropyl substituted diaziridines. These compounds showed pronounced plateau formation between 100 and 150°C, and peak coalescence at elevated temperatures. The enantiomerization barriers ΔG‡ and activation parameters ΔH‡ and ΔS‡ were determined by enantioselective dynamic gas chromatography (DGC) and direct evaluation of the elution profiles using the unified equation implemented in the software DCXplorer. Interestingly, 1‐isopropyl‐2‐n‐propyldiaziridine and 1,2‐diisopropyldiaziridine exhibit similar high interconversion barriers ΔG‡ (100°C) of 128.3 ± 0.4 kJ mol−1 and 129.8 ± 0.4 kJ mol−1, respectively, which indicates that two sterically demanding substituents do not substantially increase the barrier as expected for a distinct nitrogen inversion process. Chirality, 2010. © 2009 Wiley‐Liss, Inc.
Absolute configuration of eremophilane sesquiterpenes from Petasites hybridus: Comparison of experimental and calculated circular dichroism spectra
Authors: Bodensieck Antje , Fabian Walter M.F. , Kunert Olaf , Belaj Ferdinand , Jahangir Sajid , Schühly Wolfgang , Bauer Rudolf 
Published: June 2009

AbstractIn‐depth conformational analyses of 10 known eremophilane (= (1S,4aR,7R,8aR)‐decahydro‐1,8a‐dimethyl‐7‐(1‐methylethyl)napththalene) sesquiterpenes, 1–10, from Petasites hybridus were performed with molecular mechanics as well as density functional theory methods. Electronic transition energies and rotational strengths of these eight eremophilane lactones and two petasins were calculated by time‐dependent density functional theory (B3PW91/TZVP). The absolute configurations of the constituents could be assigned by comparison of their simulated and experimental circular dichroism (CD) spectra in methanol as (4S,5R,8S,10R) (1, 2), (2R,4S,5R,8S,10R) (3, 4, 5), (2R,4S,5R,8R,9R,10R) (6), (2R,4S,5R,8R,10R) (7, 8), and (3R,4R,5R) (9, 10). Single‐crystal X‐ray diffraction data of 8β‐hydroxyeremophilanolide ((8S)‐8‐hydroxyeremophil‐7(11)‐en‐12,8‐olide) (1) served as starting point for the theoretical conformational calculations of the 8β‐epimers of the eremophilane lactones. Experimental CD spectra as well as 1H NMR spectra of compound 1 in methanol were considerably dependent on sample concentration. Chirality, 2010. © 2009 Wiley‐Liss, Inc.
Kontaktauflaung von Nanopartikeln bei Impaktion
Authors: Weber A. P. , Wu T. 
Published: June 2009

AbstractDer Ladungstransfer auf metallische Nanopartikel bei der Impaktion auf eine Cu‐Platte und anschließendem Wiederabspringen wurde gemessen. Aus Auftreffgeschwindigkeit und Ladungstransfer lässt sich prinzipiell die Fließgrenze der Partikel bestimmen. Die größte Unsicherheit entstammt dabei der mangelhaften Kenntnis des Reibungswiderstands von Nanopartikeln mit dem Trägergas im Niederduckbereich.
Biopartikel: Eine Alternative zur Produktion nanoskaliger anorganischer Partikel
Authors: Perner‐Nochta I. , Krumov N. , Oder S. , Posten C. , Angelov A. 
Published: June 2009

AbstractDie Herstellung von Nanopartikeln mit Hilfe von Mikroorganismen ist ein vielversprechendes neues Feld der Biotechnologie. Interessant sind nanostrukturierte Materialien aufgrund ihrer einzigartigen Eigenschaften und potenziellen Einsatzgebiete, von der Medizin bis hin zur Elektrotechnik. Dieser Übersichtsartikel gibt eine systematische Zusammenfassung von Mikroorganismen, die befähigt sind, Nanopartikel zu bilden, geht auf die zellulären Bildungsmechanismen von Nanopartikeln ein und umreißt die Kultivierungsbedingungen, die diesen Syntheseprozess effizient gestalten.
A computer model for moving beds — chemical reaction in fluid phase only
Authors: Leung P. K. , Quon D. 
Published: June 2009

AbstractThe problem of a steady state plug flow transport or moving bed reactor has been solved by computer techniques for the case where the solid phase acts as a heat carrier and chemical reaction occurs only in the gas phase. The mathematical model reduces to a set of simultaneous ordinary first order differential equations, which are solved by both the Runge‐Kutta‐Gill method on a digital computer and by simulation on an analog computer.
Flow of suspensions of solids in pipelines: Part I. Flow with a stable stationary deposit
Authors: Shook C. A. , Daniel S. M. 
Published: June 2009

AbstractUsing the concepts of dilatant suspension behavior introduced by Bagnold, an equation has been derived for the hydraulic gradient necessary to transport solids in a two‐dimensional channel where suspension arises from the Bagnold dispersive stress.The equation has been tested for the case where a stationary bed of solids exists and the empirical constant in the equation is found to agree with that obtained by Bagnold for shear in an annulus.The equation bears a strong resemblance to that verified experimentally for circular pipes by Abbott.
Experimental verification of the mathematical model for a continuous stirred‐tank reactor
Authors: Kermode Richard I. , Stevens William F. 
Published: June 2009

AbstractThis paper reports the dynamic behavior of a particular continuous stirred‐tank reactor system, which has been investigated in detail both experimentally and on an analog computer. The two sets of data were taken under comparable conditions to facilitate comparison. The reaction between formaldehyde and ammonia was chosen for study, because of its high heat of reaction and its significant reaction rate at room temperature. Agreement between the experimental data and the computer results was quite good, with most deviations being explainable as arising from the use of an approximate form for the kinetic rate expression.
Critical temperatures and pressures of the ternary system, ethane—n‐pentane—n‐heptane
Authors: Dastur Soli P. , Thodos George 
Published: June 2009

AbstractThe critical temperatures and critical pressures established in the vapor‐liquid equilibrium studies of the ethane —n‐pentane—n‐heptane system, in conjunction with the critical behavior of the three corresponding binary systems, were used to develop the critical behavior of this ternary system. The results of this development are presented in the form of triangular plots for critical temperature and critical pressure and cover the complete range of composition for this system.
Dynamic response equations for various reactor models
Authors: Wen C. Y. , Chung S. F. 
Published: June 2009

AbstractTransient equations based on impulse, step, ramp, parabolic and sinusoidal inputs for reactors of various flow models are presented. The flows accompanied by the first order irreversible chemical reaction are considered. The response expressions are useful for the selection of a proper model and for the evaluation of the residence time distributions in a given reactor.
Experimental tests of generalised newtonian models containing a zero‐shear viscosity and a characteristic time
Authors: Bird R. Byron 
Published: June 2009

AbstractThis paper is a summary of six experiments which have contributed to our understanding of the utility of generalized Newtonian fluid (GNF) models, and particularly those which have a “zero‐shear viscosity” and some kind of a “characteristic time”. The accumulated evidence seems to support the use of such models for a wide range of technical applications: steady state flow in complex systems, steady state heat transfer, and slow unsteady‐state flow.
A rate equation for the reduction of ferrous chloride by hydrogen
Authors: Yannopoulos J. C. , Themelis N. J. 
Published: June 2009

AbstractPellets of FeCl2 were suspended from a thermogravimetric balance and reduced by hydrogen. Fine thermocouples were embedded in the particles and recorded the reaction temperature.In the abserrce of diffusion control through the boundary layer (H2HCI), the reduction was controlled by chemical reaction at the interface between the reduced and unreduced layers. The rate of advance of the interface towards the centre of the particle was constant with time and independent of the thickness of the reduced layer. A correlation of experimental data on different particle sizes reduced over the range 450–635°C. is presented.
Use of a shock tube in the study of high temperature gas reactions
Authors: Rao V. V. , Mackay D. , Trass O. 
Published: June 2009

AbstractA modified single‐pulse shock tube has been used to study the pyrolysis of methane in the presence of nitrogen. The reactants are rapidly heated by a reflected shock wave for about a millisecond and cooled by rarefaction waves. In the temperature range 1600–2500°K., nitrogen is found to have no effect on the first order decomposition rates of methane. Above 2500°K., considerable quantities of hydrogen cyanide are observed due to the reaction of nitrogen with hydrocarbons.
The self‐diffusivity of dilute and dense gases
Authors: Stiel Leonard I. , Thodos George 
Published: June 2009

AbstractAvailable experimental values of the self‐diffusivity at moderate pressures for 14 substances were used to establish a relationship between (ρD)* ξ and TR, where ξ = Tc1/6M1/2Pc2/3. The resulting relationship was found to reproduce 62 experimental points with an average deviation of 3.9%. For dense gases, the product of the self‐diffusion and binary diffusion coefficients with density was found to be independent of density up to ρR= 1.00. Therefore, values of the self‐diffusivity for dense gases can be calculated from the relationship between (ρD)*ξ and TR. For both nonpolar and polar mixtures values of the binary diffusion coefficient can be calculated from expressions developed previously for the force constants ξ/Kand δ, by the use of appropriate combining rules.
Simulation of the steady‐state behavior of a multicomponent, multifeed reboiled‐absorber
Authors: Petryschuk W. F. , Johnson A. I. 
Published: June 2009

AbstractThe simulation of the steady state behavior of a multi‐component, multifeed reboiled‐absorber has been studied using the θ method of obtaining convergence.Methods of representing equilibrium and enthalpy data for the digital computer are discussed. Techniques for forcing convergence by controlling temperature changes, and changes in θ are presented.The computer results are compared with the operation of a commercial column.
Anomalous flow behavior of polyisobutylene
Authors: Lund J. Kenneth , Pohl Herbert A. 
Published: June 2009

AbstractRheological data have been obtained on a polyisobutylene melt using a new type of double cone and plate rheometer. These data indicate the presence of two regions of flow behavior, exhibiting significantly different flow activation energies. Normal entanglement flow is encountered in one of these regions. The other is apparently dominated by a different mechanism which results in lower activation energies. A model of rotating flow units is proposed and applied to describe the latter region.
Flow mechanism of two‐phase annular flow
Authors: Russell T. W. F. , Lamb D. E. 
Published: June 2009

AbstractA mechanism which accounts for the formation and maintenance of two‐phase annular flow in horizontal pipes is proposed and tested experimentally. Time‐average circumferential and axial components of the film velocity were measured.Dispersion of liquid in the circumferential and axial directions and the interchange of droplets between the liquid film and gas core was studied. A pseudo steady state model was derived to describe the dispersion processes.This model was used to predict the distribution of salt downstream from a point source of salt solution located in the annular film. Experimental measurements of salt conntration using an electrical conductivity probe were in cord with values predicted by the model.
Pressurized particle‐liquid cocurrent downward flow through a tube with restricting geometries
Authors: Chon W. Y. , Chen E. C. 
Published: June 2009

AbstractCocurrent downward flow of a bed of particles in a fluid medium through straight tubes with an orifice and a gradually converging cone at the lower end, was studied. Two dimensionless groups, i.e., effluent flow ratio defined as the ratio of particle flow rate to total flow rate, and Reynolds number, have been correlated for intermediate flow region. For low flow rate region, however, excess flow rate of liquid, was found to control the effluent flow ratio.Such a correlation serves as a terminal condition, and enables one to predict the absolute particle flow rate in a pressurized flow system, when used together with conventional moving bed correlations.
A kinetic study of the formation of the tetrahydrofuran gas hydrate
Authors: Pinder K. L. 
Published: June 2009

AbstractThe rate of formation of the tetrahydrofuran hydrate has been followed by the concentration changes in a solution having other than 17 moles of water per mole of tetrahydrofuran; the hydrate concentration. The concentration was found to vary in a stepwise manner with breaks at concentrations which correspond to water to tetrahydrofuran mole ratios of 10:1, 8:1, 7:1, 5.5:1, 5:1, 3.5:1, 3:1 and 2.5.1. For each concentration range the slope of the concentration time curve was found to be stirrer rate dependent. It is postulated that the observed results are due to hydrogen bonding in the solution, causing association complexes of definite molar ratios of water to tetrahydrofuran corresponding to the breaks in the concentration‐time curves. The rate would therefore be controlled by diffusion of reactant from one complex to the other.
Foam fractionation of the ferric oxide‐dodecyl sodium sulphate system
Authors: Grieves Robert B. , Bhattacharyya Dibakar 
Published: June 2009

AbstractAn experimental investigation is presented of the batch foam fractionation‐flotation of a positively‐charged colloid‐anionic surfactant system, to determine the feasibility of the process for the removal of trivalent iron from water supplies. Ferric oxide (trivalent iron) initial concentrations are varied from 17.5 to 219 mg./l., dodecyl sodium sulphate initial concentrations from 10 to 30 mg./l., and nitrogen rates from 600 to 8000 ml./min.Excellent separations of both ferric oxide and DSS are obtained with residual iron concentrations as low as 0.003‐0.031 of initial concentrations around 25 mg./l., depending on the intital concentration of DSS. The residual DSS concentration remains virtually constant. The ferric oxide enrichment ratio is an inverse power function of the initial iron concentration and is maximized at minimum gas rate.
Factors affecting which phase will disperse when immiscible liquids are stirred together
Authors: Selker A. H. , Sleicher C. A. 
Published: June 2009

AbstractFactors that affect control over which of two immiscible liquids would be continuous in stirred tanks were studied. Variables that were investigated were viscosities, densities, speed of mixing, manner of initiating the dispersion, and the materials and construction of the mixing apparatus.It was found that for a given liquid pair there is a wide range of relative volumes in which either liquid could be stably continuous. Within this range the phase that becomes continuous is prescribed by the manner of initiating the dispersion. This range was found to be a function principally of the viscosity ratio.
Design of perforated‐plate extraction columns from rate equations
Authors: Skelland A. H. P. , Cornish A. R. H. 
Published: June 2009

AbstractThis paper develops a procedure for the design of perforated plate—or spray—columns in terms of rate equations for mass transfer during droplet formation, free rise (or fall), and coalescence on each plate. A summary is then presented of the available relationships necessary for all stages of the procedure.
Combined free‐and‐forced convection: II. Heat transfer in opposing flow
Authors: Brown C. K. , Gavvin W. H. 
Published: June 2009

AbstractThe rate of heat transfer to air flowing downward at low velocities through a heated tube was studied. The apparatus has been described in a previous work. The investigation covered a flow rate ranging from 85 to 930 lb./hr.ft.2, (NRc) from 380 to 6,900, (NGr) from 0.18 × 106 to 7.3 × 106 and nominal wall temperatures of 100, 500 and 950°C.The local Nusselt number could be correlated with the Grashof number independently of its axial position, over a range of Grashof numbers not previously investigated. In particular, it was noted that a marked change in the slope of the (NNu)‐vs‐(NGr) curve occurred around a Grashof number of 106.
An analysis of spray evaporation in a high‐temperature environment: III. Calculation of the heat flux distribution in a cylindrical column containing a cloud of evaporating droplets
Authors: Hoffman T. W. , Gauvin W. H. 
Published: June 2009

AbstractThe aim of the present paper is to develop a method for calculating the heat‐flux distribution along the hot walls of a vertical cylindrical column containing a suspension of evaporating droplets in an absorbing atmosphere flowing downward. The method of calculation is illustrated by applying it to a specific experimental condition which has been reported previously (2).The agreement between the calculation and experimental results is only fair. A discussion of some of the difficulties in the analysis and recommendations for further investigations are presented.
The thermal history of a granule in a rotary cooler
Authors: Turner G. A. 
Published: June 2009

AbstractA formula is developed (from which a computer program has been written) that allows the temperature to be calculated of a granule that undergoes alernating periods of being cooled and of being allowed to ‘soak’ without cooling. This is the process, repeated many times, that a particle suffers in a rotary cooler. The result should provide a design method that utilizes only basic physical quantities.
Sublimation mass transfer in supersonic flow. The effect of compressibility and schmidt number
Authors: Olvet S. I. , Trass Olev 
Published: June 2009

AbstractRates of sublimation mass transfer from an adiabatic sharp‐edged flat plate have been measured. The plate was coated with ice, naphthalene, thymol, and camphor (Schmidt number range 0.60 to 2.9) and exposed to parallel supersonic (Mach 3.28) air flow. The coating thickness decrease during the run was measured and surface temperatures and flow variables were monitored. Turbulent data were obtained over a Reynolds number range from 2 × 105 to 106. The results show that at Sc > 1 the effect of compressibility on mass transfer is greater than on heat and momentum transfer while at Sc < 1 the effect is reversed. This is in qualitative agreement with theory; quantitative agreement was obtained only with ice. Sublimation data of Sherwood and Trass are reviewed briefly.
A computer model for the regenerative bed
Authors: Leung P. K. , Quon D. 
Published: June 2009

AbstractThe transient behavior of a packed bed of uniform spheres is considered, where heat (or mass) transfer inside the sphere is described by a linear parabolic second order partial differential equation — the standard diffusivity equation. One dimenisonal plug flow is assumed; hence, the fluid behavior is given by a set of first order partial differential equations, with bed axial position and time as the independent variables. The existence of chemical reaction in the fluid makes these equations non‐linear. The two systems of equations describing the solid and the gas are coupled by the equations for heat (or mass) transfer at the surface. Numerical methods for solving both the linear (no reaction) and non‐linear (with reaction) cases are presented. In the former, the implicit Crank‐Nicholson method is used; in the latter the two systems of equations are first decoupled and then solved separately.
The enskog modulus for p‐hydrogen in the gaseous and liquid states
Authors: Elzinga D. Jack , Thodos George 
Published: June 2009

AbstractThe recent PVT measurements of p‐hydrogen reported by the National Bureau of Standards(1,2,3) have been utilized to establish the Enskog modulus, bpx, for pressures up to 350 atm and temperatures up to 100°K. These conditions define both the gaseous and liquid regions and also include the saturation envelope from the triple point to the critical point of this substance. This modulus is expressed graphically as a function of reduced pressure and reduced temperature. The best available PVT measurements coupled with a precise calculational procedure conducted on an IBM 709 computer have produced a bpx correlation which readily permits the calculation of the pressure dependence of the transport properties of p‐hydrogen according to the Enskog theory for the dense gaseous and liquid regions.
Gas absorption in horizontal cocurrent bubble flow
Authors: Scott D. S. , Hayduk W. 
Published: June 2009

AbstractCocurrent flow pipeline reactors would have several advantages for gas‐liquid reacting systems. However, design data are lacking, particularly for absorption rates of gas. The present study was purely exploratory, for the purpose of obtaining the first data on liquid‐phase controlled absorption of gases in horizontal cocurrent two phase flow. CO2 and helium were used as gases and water, ethanol and ethylene glycol as liquids over a wide range of operating conditions.The data in the bubble and plug flow regions have been correlated by an equation based on qualitative observation and analogy to the case of a single flowing fluid. The resulting expression, reproduces most bubble flow data to ± 15%, and includes the effects of gas and liquid flow rates, pipe diameter, surface tension, liquid viscosity and diffusivity.
Longitudinal particle mixing in a screen‐packed gas‐solid fluidized bed
Authors: Kang W. K. , Osberg G. L. 
Published: June 2009

AbstractLongitudinal particle mixing in a screen‐packed, gas‐solid fluidized bed, 5 cm. I.D. × 100 cm. bed height, has been studied by employing a colorimetric concentration impulse technique. The packings were 1/2‐in. × 1/2‐in. open‐end screen cylinders.For the screen‐packed bed the results were in good agreement with a diffusion model, while the results for the unpacked fluidized bed showed that the simple diffusion model could not be readily applied. A cell model was also developed and compared with the diffusion model. The experimental data were analysed in terms of these models.