bluuebunny/crossref_metadata_2025 huggingface dataset:
Corporate Governance and Challenges of Financial Leverage of Privatised Cement Industry in Nigeria
Authors: Gombe Bappayo Masu , Mukhtar Mustapha
Published: April 2024

The paper studies new corporate governance and the challenges of financial Leverage of privatised cement industry in Nigeria. The variables studied were leverage ratio as Performance proxy (dependent variables) and fourteen Corporate Governance proxies as independent variables. Data was collected from secondary sources, and the statistical tools employed in the Methodology were Trend Analysis and Pooled OLS regressions. Trend Analysis result suggests that;Devaluation, high cost of importation, insufficient power supply, bank strike, and deflation of global oil prices created capacity underutilization in cement industry and severe burden of financial leverage to sustain operational activities pre privatization. The result also, reveals that, the leverage ratio remarkably declined post privatization, however, the global financial crisis of 2009 inflicted high cost of production on the industry which necessitated increased leverage in order to cushion the effects on operational activities. Inferential Statistics Result suggests that corporate governance has positive and significant impact on the leverage ratio of the industry in general. The study concludes that, despite the challenges of unfavourable macroeconomic environment, the new corporate governance reduced the leverage ratio post privatisation and it has positive and significant impact on the financial leverage of the Cement Industry. The researcher recommends that Nigerian government should ensure favourable macroeconomic environment and improve private sector activities. Collectively, the new Corporate Governance of Cement Industry should strategize on how to; Increase Revenue, profitability, better management of inventory, and restructuring of debt to mitigate increased leverage.
Effect of low‐molar‐mass liquid crystal on the melt processing conditions of polycarbonate using single screw extruder
Authors: Khunprasert Supaluk , Thongyai Supakanok , Chinsirikul Wannee , Wacharawichanant Sirirat
Published: March 2009

This research concerned about the effects of low‐molar‐mass liquid crystal (LMLC) blend with polycarbonates (PCs) that influence the processing conditions (torques) without detrimental to the benign properties of PC. The two PCs, having different weight‐average molar mass (PC2600 and PC2405), were blended with LMLC (CBC‐33) at concentration about 0.2 wt % using a single screw extruder. As confirmed by the previous observation of Motong et al. (J Appl Polym Sci 2008, 107, 1108), the LMLC could act as a melt viscosity reduction additive for PCs. Because of the reduction in melt viscosity of PC, the operating torque of a single screw extruder used when extruding PC blended with LMLC was reduced up to 83% depended on the mixing condition of LMLC. The mechanical properties were determined by tensile testing specimens from injection molding machine, and the difference of tensile strengths and modulus of elasticity between pure PCs and their blends was less than 10%, which indicated the very low detrimental effects to mechanical properties of the LMLC blend. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Cationic polymerization of ethylene oxide with Maghnite‐H as a clay catalyst in the presence of ethylene glycol
Authors: Yahiaoui Ahmed , Hachemaoui Aïcha , Belbachir Mohammed
Published: March 2009

The activated‐monomer cationic ring‐opening polymerization of ethylene oxide, initiated with ethylene glycol and using an acid‐exchanged montmorillonite clay called Maghnite‐H+ as an effective catalyst, was carried out to obtain the corresponding homopolymers with narrow polydispersity ratios. The molecular weights of the obtained polymers were controlled with the feed ratio of the monomer to the initiator. The effects of the amount of the catalyst and time on the polymerization yield and viscosity of the polymers were studied. The structure was confirmed with proton nuclear magnetic resonance and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effect of zinc supplementation on the antioxidant, copper, and iron status of physically active adolescents
Authors: de Oliveira Karla de Jesus Fernandes , Donangelo Carmen Marino , de Oliveira Astrogildo Vianna , da Silveira Carmen Lucia Porto , Koury Josely Correa
Published: March 2009

Puberty associated with intense physical activity results in oxidation stress. Zinc supplementation may benefit antioxidant capacity although it may also affect iron and copper status. This study evaluated the effect of zinc supplementation on antioxidant, zinc and copper status of physically active male football players (13 years ± 0.4 years), divided in two groups and studied during 12 weeks: Zn‐supplemented (Zn‐SUP, 22 mg Zn d−1 as zinc gluconate, n = 21) and placebo (PLA, n = 26). At baseline, there was no significant difference in biochemical indices between the two groups. After treatment, plasma zinc and erythrocyte iron increased in both groups (p < 0.001); urinary zinc increased (p < 0.001) only in Zn‐SUP, and erythrocyte zinc decreased (p = 0.002) only in PLA. Plasma iron and copper decreased (p = 0.01 and p = 0.015, respectively) only in Zn‐SUP. Plasma ferric‐reducing ability and plasma conjugated dienes increased, and erythrocyte osmotic fragility decrease in both groups, although the latter two were significantly lower in Zn‐SUP compared to PLA (p < 0.01). In conclusion, our study indicates that the use of 22 mg d−1 of supplemental zinc during 12 week in adolescent athletes did not affect growth, improved markers of antioxidant status but reduced plasma iron and copper. Therefore, it appears that the use of zinc supplementation by healthy adolescent athletes benefits their antioxidant capacity but impairs copper and iron nutritional status. Copyright © 2009 John Wiley & Sons, Ltd.
Highly Selective Stereodivergent Synthesis of Separable Amide Rotamers, by Using Pd Chemistry, and Their Thermodynamic Behavior
Authors: Ototake Nobutaka , Nakamura Masashi , Dobashi Yasuo , Fukaya Haruhiko , Kitagawa Osamu
Published: March 2009

Going separate ways: By using π‐allyl–palladium chemistry (path A) and PdII‐catalyzed Claisen chemistry (path B), a highly selective stereodivergent synthesis of separable amide rotamers was achieved (see scheme).

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By using Pd chemistry, a highly selective stereodivergent synthesis of separable amide rotamers was achieved. Allylation of 2,4,6‐tri‐tert‐butylanilides using a π‐allyl–Pd catalyst gave N‐allylated anilides with moderate‐to‐excellent Z‐rotamer selectivity (Z/E=3 to >50). The Z‐rotamer selectivity depends considerably on the substituent on the anilide substrates. On the other hand, the E rotamers of N‐allylated 2,4,6‐tri‐tert‐butylanilides were obtained with almost complete selectivity (E/Z>50) through O‐allylation of 2,4,6‐tri‐tert‐butylanilides and the subsequent PdII‐catalyzed Claisen rearrangement of the resulting O‐allyl imidate. The prepared anilide rotamers changed to equilibrium mixtures in which the E rotamer was the major isomer when heated in toluene.
Heat exchanger fouling by olefin‐kerosene mixtures
Authors: Asomaning S. , Watkinson A. P.
Published: March 2009

Fouling resistances of solutions of olefins in kerosene were measured on a hot wire probe and an annular probe operating in parallel at liquid temperatures of about 80°C and heat fluxes from 180‐350 kW/m2. Straight chain terminal olefins, octene‐1 and decene‐1 showed little fouling, whereas hexadecene‐1, and the cyclic olefins 4‐vinyl‐cyclohexene, indene and dicyclopentadiene all showed marked fouling. The effects of heat flux, air versus nitrogen saturation, and the presence of an inhibitor were determined. The probable mechanism of fouling is discussed.
Solubilities of carbon dioxide, hydrogen sulfide and sulfur dioxide in physical solvents
Authors: Xu Yuming , Schutte Richard P. , Hepler Loren G.
Published: March 2009

Solubilities expressed by Henry's law constants for carbon dioxide, hydrogen sulfide and sulfur dioxide in four physical solvents (propylene carbonate, N‐formyl morpholine, Selexol, and methyl cyanoacetate) have been measured at several temperatures ranging from 25°C to 70°C, using gas‐liquid chromatography. Thermodynamic properties including enthalpies and entropies of solution have been derived from the solubility data.
Ultrapyrolysis of automobile shredder residue
Authors: Shen Z. , Day M. , Cooney J. D. , Lu G. , Briens C. L. , Bergougnou M. A.
Published: March 2009

A fast pyrolysis (Ultrapyrolysis) process was employed to convert automobile shredder residue (ASR) into chemical products. Experiments were conducted at atmospheric pressure and temperatures between 700 and 850°C with residence times between 0.3 and 1.4 seconds. Pyrolysis products included 59 to 68 mass% solid residue, 13 to 23 mass% pyrolysis gas (dry) and 4 to 12 mass% pyrolytic water from a feed containing 39 mass% organic matter and 2 mass% moisture. No measurable amounts of liquid pyrolysis oil were produced. The five most abundant pyrolysis gases, in vol%, were CO (18–29), CO2 (20–23), CH4 (17–22), C2H4 (20–22) and C3H6 (1–11), accounting for more than 90% of the total volume. The use of a higher organic content ASR feed (58 mass%) resulted in less solid residue and more pyrolysis gas. However, no significant changes were noted in the composition of the pyrolysis gas.
Gas phase flow in bubble columns: A convective phenomenon
Authors: Hyndman Caroline L. , Guy Christophe
Published: March 2009

The axial dispersion model has been commonly used to describe gas phase flow in bubble columns. Scatter in dispersion coefficients reported to date may be a result of the misuse of the axial dispersion model when a convective model would be more appropriate. Using simple tests with radioactive tracer response curve moments, convective and dispersive behaviours are differentiated. A convective model is presented. The model fits both tracer response curves and mean gas velocity well in both the bubbly and churn turbulent flow regimes, and may be used as a technique to calculate bubble rise velocity distributions.
Process design of condensers for vapor mixtures in the presence of non‐condensable gases
Authors: Mazzarotta Barbara , Sebastiani Enzo
Published: March 2009

A mathematical model is proposed to design condensers for vapor mixtures containing a non‐condensable gas. The Colburn and Drew (1937) film model is used, assuming the liquid flux to be completely mixed, but taking into account the interactions due to diffusion in the gaseous mixture. Some computational examples are given to show how the present model compares with the previous ones for the condensation of water‐methanol in the presence of air in a single tube condenser, and how the condensation of water‐ethanol mixtures in the presence of carbon dioxide in a shell‐and‐tube condenser evolves at different operating conditions.
Factors affecting catalytic performance in yadh‐catalyzed reductions in non‐conventional media
Authors: Nikolova P. , Goldman H. , Ward O. P.
Published: March 2009

The effects of parameters including water content, the amount of celite and the co‐factor regeneration system on reduction of benzaldehyde to benzyl alcohol by yeast alcohol dehydrogenase (YADH) immobilized on celite in non‐conventional media were investigated. Kinetic parameters (apparent) such as Vmax, Km, and kcar for different organic solvents used (butyl acetate, hexane, heptane and i‐octane) were determined. Km values for benzaldehyde increased as the solvent was varied in the following manner: butyl acetate < hexane < i‐octane < heptane. The highest Km value (20.26 mmol/L) was noted in heptane and the lowest (3.24 mmol/L) in butyl acetate. The Vmax value in heptane was more than an order of magnitude higher than that in butyl acetate. Catalytic efficiencies (as expressed by kcar/Km) ranged from 0.703 × 10−4 L/mol · s for hexane to 0.171 × 10−4 L/mol · s for butyl acetate. In general, linear relationships were observed between kcar/Km and the following solvent physico‐chemical constants: dielectric constant logarithm of the saturated molar solubility of water in the organic solvents, log Sw/o, logarithm of partition coefficient of organic solvent in water/octanol two‐phase system, log P, Hildebrand solubility parameter, δ, and solvatochromism of pyridinium‐N‐phenoxide betaine dye, ET(30).
Mathematical modeling and steady‐state analysis of a scheibel extraction column
Authors: Alatiqi I. , Aly G. , Mjalli F. , Mumford C. J.
Published: March 2009

The steady‐state behavior of a nine‐stage Scheibel extraction column was modeled and simulated using a back flow stagewise model. Steady‐state experiments were conducted, using the system water‐acetone‐toluene, for three phase ratios and three agitator speeds. The mathematical model was validated with the experimental concentration profiles by a single parameter fitting technique with an unconstrained optimization algorithm.

Steady‐stage analysis of the experiments was performed for a further control study. The calculated steady‐state gain matrices were used for interaction analysis using different steady‐state analysis methods, e.g. Bristol numbers, Condition numbers, Morari Indexes of Integral Controllability, and Niederlinski Indexes. The results indicate that both agitator speed and phase ratio have a substantial influence on the control structure. Dynamic analysis should therefore be performed to verify the optimum control method for this process.
Estimation of equation of state parameters for 1,1,1,2‐tetrafluoroethane in a modified benedict‐webb‐rubin equation
Authors: Sörner Maria , Ström Krister H. U.
Published: March 2009

Thermodynamic properties of refrigerants are of great importance in the design and simulation of heat pumps and refrigeration units. The parameter values in the modified Benedict‐Webb‐Rubin equation of state proposed by Lee and Kesler (1975) have been determined for HFC 134a with the Error‐in‐Variables Model. The types of data used for the parameter estimation have been: pressure‐volume‐temperature data for subcooled and superheated conditions, vapour pressures, saturated vapour and liquid volumes, isobaric arid isochoric heat capacities and second virial coefficients. Calculations carried out with the equation of state according to Lee and Kesler, with the parameters here proposed, agree well with experimental data for the fluid.
Contrǒle hydrodynamique en convection mixte de l'épaisseur de dépǒts en phase gazeuse de semi‐conducteurs sur des corps à symétrie de révolution
Authors: Cherif A. Ali , Daïf A. , Rakotomalala M. , Daguenet M.
Published: March 2009

Les auteurs résolvent à l'aide d'une méthode aux différences finies les équations de la couche limite laminaire et permanente qui entoure des corps à symétrie de révolution (sphère, ellipsoïdes allongé et aplati), au nez orienté vers le haut, portés, à 500°C, en rotation uniforme autour d'un axe vertical dans un écoulement axial descendant de gaz d'hydrogène à 25°C. La variabilité des propriétés physiques; du fluide en fonction de la température est prise en compte ainsi que la convection naturelle qui en résulte. Les auteurs montrent que l'écoulement et les transferts dépendent de façon significative de cette variabilité et qu'il est possible de contrǒler la croissance des couches limites thermique et massique en agissant sur les conditions opératoires, notamment sur le profil des corps. Une application directe de ce travail est le contrǒle des dépǒts en phase vapeur.
Optimum dimensions of longitudinal rectangular fins and cylindrical pin fins with variable heat transfer coefficient
Authors: Yeh Rong‐Hua
Published: March 2009

Considering a temperature dependent heat transfer coefficient, the optimum dimensions of longitudinal rectangular fins and cylindrical pin fins have been investigated analytically. Employing the parameters of fin thickness or fin diameter and tip temperatures, the optimum dimensions, heat dissipation, and efficiency of fins are obtained by Lagrange's multiplier method. It is shown that the fin efficiency of an optimum cylindrical pin fin is higher than that of an optimum rectangular fin. To facilitate the thermal design of the heat transfer components, very simple mathematical expressions for the optimum dimensions of fins are presented in this study.
Mathematical modelling of the transient behaviour of cstrs with reactive particulates: Part 1 — The population balance framework
Authors: Rubisov Dmitri H. , Papangelakis Vladimiros G.
Published: March 2009

The population balance model appears to be the best approach to model particulate systems where multiple heterogeneous reactions occur. This work demonstrates a mathematical formulation that is based on the population balance model, and aims at simulating the non steady‐state behaviour of a single‐stage CSTR under isothermal operation. The chemical reaction system is a typical example from the field of hydrometallurgy with two parallel reactions, one being leaching, the other precipitation with simultaneous reactant regeneration. The solution of the resulting system of the partial and ordinary differential equations is achieved by combining the moment transformation of the population balance equations with the numerical method of lines, using the Mathematica® software. Finally, examples are given for a reactor startup in two cases: a single leaching reaction, and simultaneous leaching and precipitation reactions. In the first case, the difference between simultaneous and sequential feeding in achieving steady‐state is also discussed.
Kinetics of acetic acid esterification over ion exchange catalysts
Authors: Xu Z. P. , Chuang K. T.
Published: March 2009

Computer simulation showed that catalytic distillation is an attractive process for the removal of dilute acetic acid from wastewater. Selection of catalysts and kinetic data have been obtained for the design of the catalytic distillation column.

Kinetic measurements were conducted in a batch reactor. Methanol was added to the dilute acetic acid solutions and reacted with the acid in water to form methyl acetate and water. The reaction can be catalyzed by solid acid catalysts. It was found that Amberlyst 15 was an effective catalyst for this reaction. The effects of stirrer speed, reaction temperature, reactant concentration and catalyst loading on reaction rate were investigated. A complete kinetic equation for describing the reaction catalyzed by Amberlyst 15 was developed. This equation can be used in the simulation and design of the catalytic distillation column for removing acetic acid from wastewater.
Unsteady states in metallurgical sulphuric acid plants after SO2 concentration drop in the feed gas
Authors: Gosiewski Krzysztof
Published: March 2009

The paper presents results of dynamic mathematical model simulations for selected two characteristic flowsheets of metallurgical SO2 oxidation plant after temporary decrease of reactant concentration in the feed gas. An analysis of dynamic resistance of the plant for the concentration drop, from the point of view of the dynamic autothermal properties is given.
Transient and resonant behavior for no reduction by CO over a Pt/Al2O3 catalyst during forced composition cycling
Authors: Sadhankar Ramakant R. , Lynch David T.
Published: March 2009

The reduction of NO by CO over a Pt/Al2O3 catalyst has been investigated using the technique of forced concentration cycling in an isothermal recycle reactor at 485 K. Time‐average conversions exhibit resonant behavior with increasing frequency. Maximum time‐average NO conversion of 78%, compared with the steady‐state conversion of 3.8%, was attained during out‐of‐phase feed concentration cycling. The effect of the phase angle between the NO and CO feed cycles has been examined. Higher conversions are obtained by decreasing the NO phase lead below 180°. The convergence to cycle‐invariance was slow for high frequency cycling.
Sorbent development for continuous regenerative H2S removal in a rotating monolith reactor
Authors: Bakker WridzerJ. W. , Vriesendorp Maaike , Kapteijn Freek , Moulijn Jacob A.
Published: March 2009

A high capacity and regenerable manganese based sorbent for desulfurization of hot dry fuel gas from coal gasification has been developed. Pure γ‐Al2O3 and washcoated cordierite monoliths impregnated with manganese acetate and calcined at 973 K resulted in highly dispersed Mn3O4 on γ‐Al2O3. MnS was formed during sulfidation and MnAl2O4 during subsequent regeneration with steam. The optimal operation temperature was found to be between 1123 and 1223 K. The maximum capacity of the acceptor was 17 mass% sulfur which was obtained for a 32 mass% manganese loading. A deactivation test of 65 subsequent sulfidation and regeneration cycles showed minor deactivation during the first cycles followed by a stable performance.

This sorbent will be used in a rotating monolith reactor in which absorption and regeneration takes place simultaneously in separate sections, which enables a continuous operation.
Energy trapping during reverse flow operation with discrete power introduction: Experiments and theory
Authors: Snyder Jon D. , Subramaniam Bala
Published: March 2009

It is shown that reverse flow operation is well‐suited for packed‐bed operation requiring energy addition from sources external to the packing. Packed‐bed temperature profiles are dictated by (a) how the power is distributed axially, and (b) the temperature‐profile movement, proportional to the volume of flowing gas introduced during the semicycle (flow rate × semicycle period). While peak‐shaped temperature profiles result for energy input at axially central locations, plateau‐shaped temperature profiles result for energy distribution offset from the center and for relatively large volumes of gas introduced during a semicycle. In both cases, however, efficient energy integration is achieved with the maximum temperature rise being hundreds of degrees greater than the adiabatic temperature rise for unidirectional flow operation.
Choosing the right model: Case studies on the use of statistical modeldiscrimination experiments
Authors: Burke A. L. , Duever T. A. , Penlidis A.
Published: March 2009

Statistical model discrimination methods were developed to efficiently and reliably choose the ‘best’ model for a system from a set of candidate models. Three promising model discrimination techniques are compared using three chemical engineering examples in this paper. The examples were studied via computer simulations in which experimental data were generated using a known model. The use of a computer simulation allowed factors such as error magnitude to be studied at different levels in repeat runs of the program. The results indicated the exact entropy method is the best method for use with non‐nested nonlinear models, while the Buzzi‐Ferraris and Forzatti (1983) method is best for use with nonlinear nested models.
Kinetics of the dissolution of silica in aqueous sodium hydroxide solutions at high pressure and temperature
Authors: Jendoubi F. , Mgaidi A. , El Maaoui M.
Published: March 2009

The kinetic of the reaction of sand with aqueous NaOH corresponding to the ratio SiO2/Na2O = 2 was studied in a pressure vessel at 220°C and 2.7 MPa. Since the kinetic curves could not be obtained directly from the experimental data, a new method is proposed to plot the entire kinetic graph from experimental data. An analytical expression of the type α = A [1 ‐exp(‐Bt)] describes the system perfectly. The constants A and B were calculated for a silica sample having a narrow granulometric distribution (range i.e. 300–315 μm). The value of A is found to be almost constant, between 0.95 to 0.99 and B ranges from 0.03 to 0.14 when [OH‐] increases from 0.5 to 12.5 mol/L. The kinetic order with respect to OH− is equal to 0.470 + 0.013 and the kinetic constant at 220°C is 3.933 × 10−6 g/m2.s.
Solid‐liquid mass transfer coefficients in gas‐solid‐liquid agitated vessels
Authors: Grisafi Franco , Brucato Alberto , Rizzuti Lucio
Published: March 2009

The research on mass transfer coefficients in solid‐liquid agitated systems has received substantial attention in the past, due both to the interest in fundamental aspects of mass transfer between particles and turbulent fluids and to the importance of practical applications. In contrast, little information is available on solid‐liquid mass transfer when a third gaseous phase is also dispersed into the system, in spite of the importance of the applications of gas‐solid‐liquid agitated systems. In this work a suitable dissolution technique was used to measure the solid‐liquid mass transfer coefficient in gas‐solid‐liquid vessels stirred by either radial or axial impellers. The mechanical power dissipated by the stirrers at various agitation speeds and gas flow rates was also measured by means of a new technique. The mass transfer data obtained were found to be well correlated to the 0.25 power of the specific power dissipation, indicating that the Kolmogorov's theory of mass transfer applies to these systems, while no clear influence of the gas hold‐up was ascertained.
A hybrid expert‐procedural system for the design of reverse‐osmosis desalination plants
Authors: Voivontas Dimosthenis , Papafotiou Kostas , Assimacopoulos Dionysis , Mitsoulis Evan
Published: March 2009

The problem of computer‐aided design and synthesis of a reverse‐osmosis desalination plant is presented. A hybrid expert‐procedural system has been developed that deal with the synthesis problem at two levels of abstraction. The expert part of the system uses qualitative data, and through heuristics, makes decisions about the structure of the plant. The procedural part of the system uses the decisions of the expert part as a basis for detailed design and optimisation. The heuristics used in the expert part come from experienced designers and from proposals of membrane manufacturers. The detailed calculations are based on mass balance equations and correlations for the permeators. The system developed can be used to propose a reverse‐osmosis plant structure and to perform detailed calculations for possible design scenarios envisaged by the user. A case study on such a plant is also given and shows how the expert system handles the design problem of a reverse osmosis desalination plant.
Drying of soybean seeds in a crossflow moving bed
Authors: Barrozo Marcos A. S. , Henrique Humberto M. , Sartori Dermeval J. M. , Freire José T.
Published: March 2009

The aim of this work was to investigate simultaneous heat and mass transfer between air and soybean seeds in a crossflow moving bed dryer. A model was developed from mass and energy conservation applied to the fluid and particulate phases. The equilibrium, heat transfer and mass transfer equations were taken from studies published earlier. Equations for drying kinetics were obtained from a thin layer study, and the equilibrium equation was chosen from rival model discrimination based on nonlinearity measures. The experimental part of this work involved the determination of air temperature distribution, grain moisture through the bed and air humidity at the bed outlet. The model equations were discretized by orthogonal collocation in the air flow direction. The resulting differential‐algebraic equations were solved using a method based on backward differential formulas. Simulation results showed good agreement with experimental data.
Iron—molybdenum—oxide catalysts for selective oxidation of hydrogen sulfide to sulfur
Authors: Li Kuo‐Tseng , Huang Chun‐Hsiung
Published: March 2009

The selective oxidation of hydrogen sulfide to sulfur was studied over iron‐molybdenum oxides with various Fe‐Mo ratios. Strong synergistic phenomenon in catalytic activity was observed for the Fe‐Mo‐O binary oxides. Under identical reaction conditions, the areal rates of the binary oxides were superior to those of the corresponding single oxide catalysts, which suggest that the new compound Fe2(MO4)3 formed in the binary oxide is more active than Fe2O3 and MoO3. The oxidation rates of H2S were found to exhibit first‐order dependence on the hydrogen sulfide concentration, which implies that the activation of H2S is the rate‐limiting step.
Power draw of a high‐Shear homogenizer
Authors: Myers Kevin J. , Reeder Mark F. , Ryan David
Published: March 2009

The power draw of a high‐shear rotor‐stator homogenizer has been characterized in laminar, transitional, and turbulent operation. The power draw is comprised of two components — that associated with mixing and that associated with a bushing and bearings in the device. In turbulent operation, the mixing power draw is influenced primarily by pumping mode (up‐ or down‐pumping), and to a lesser extent, by vessel baffling and other geometric parameters. Mixing power draw can be characterized in terms of power number across the Reynolds number spectrum if an empirical Froude number correction is applied.
An update on the genotoxicity and carcinogenicity of marketed pharmaceuticals with reference to in silico predictivity
Authors: Snyder Ronald D.
Published: March 2009

Information from the 1999 through 2008 Physicians' Desk Reference (PDR) was used to evaluate the genotoxicity of marketed drugs. Where available, data regarding the rodent carcinogenicity results were included (PDR and Gold potency database). In addition, computational predictivity of genotoxicity (DEREK, MC4PC) is included and expanded upon from two previous reviews. The present paper contains genotoxicity data on 545 marketed drugs. Excluded from analysis were most cytotoxic anti‐cancer and antiviral drugs, nucleosides (all with known mechanistic genotoxicity), steroids with class‐specific genotoxicity and biologicals or peptide‐based drugs. Per assay type, the percentage of positive drugs was: Bacterial mutagenesis assay: 38/525 (7.1%), in vitro chromosome aberrations: 88/380 (26.1%); mouse lymphoma assays (MLA): 32/163 (19.1%), in vivo cytogenetics: 49/438 (11.1%). The relationship among positive genetic toxicity findings, rodent carcinogenicity, and in silico prediction is discussed. Finally, supporting evidence is presented for the idea that the presence of an N‐dialkyl group or piperidine aryl ketone may somehow be associated with genotoxicity, perhaps through DNA intercalation and consequent DNA topoisomerase II inhibition. Environ. Mol. Mutagen. 2009. © 2009 Wiley‐Liss, Inc.
Steady‐state priors for vector autoregressions
Authors: Villani Mattias
Published: March 2009

Bayesian priors are often used to restrain the otherwise highly over‐parametrized vector autoregressive (VAR) models. The currently available Bayesian VAR methodology does not allow the user to specify prior beliefs about the unconditional mean, or steady state, of the system. This is unfortunate as the steady state is something that economists usually claim to know relatively well. This paper develops easily implemented methods for analyzing both stationary and cointegrated VARs, in reduced or structural form, with an informative prior on the steady state. We document that prior information on the steady state leads to substantial gains in forecasting accuracy on Swedish macro data. A second example illustrates the use of informative steady‐state priors in a cointegration model of the consumption‐wealth relationship in the USA. Copyright © 2009 John Wiley & Sons, Ltd.
Doxycycline enhances the Ras‐MAPK signaling and proliferation of mouse thymic epithelial cells
Authors: Chen Xun , Xia Sheng , Li Rong , Liu Hui , Huang Ying , Qian Xiaoping , Xiao Xueyuan , Xu Xun , Lin Xin , Tian Yuxiang , Zong Yangyong , He Dacheng , Chen Weifeng , Zhang Yu , Shao Qixiang
Published: March 2009

Depletion of T‐cell‐dependent immunity is a major consideration for patients suffering from infections of human immunodeficiency virus (HIV), those undergoing organ transplantation, and those receiving anti‐cancer chemotherapy and/or radiotherapy. In general, T‐cell regeneration occurs in the thymus through thymopoiesis. We have found that doxycycline (Dox), a tetracycline derivative, enhances the proliferation of mouse thymic epithelial cells, which are unique in their capacity to support positive selection and are essential throughout the development of thymocytes. Cell cycle analysis indicates that the increased cell proliferation is due to a shortened G0/G1 phase. To reveal the underlying mechanisms, we examined the expression of an array of molecules that regulate the cell cycle. The results show that in mouse thymic medullary‐type epithelial cell line 1 (MTEC1) Dox leads to elevated levels of H‐Ras, phosphorylated extracellular signal‐regulated kinase 1/2 (p‐ERK1/2), cyclin E, cyclin dependent kinase 4/2 (CDK4/CDK2), E2F3, and c‐myc. These data, and the observation that the proliferation‐enhancing effect is largely abolished following treatment with an ERK inhibitor support an active role of the Ras‐ERK/mitogen‐activated protein kinase (MAPK) signaling pathway. In conclusion, the present study reveals a new activity of an old family of antibiotics. The in vivo effect of Dox on immune reconstitution warrants further exploration. J. Cell. Biochem. 107: 494–503, 2009. © 2009 Wiley‐Liss, Inc.
High‐resolution narrowband CARS spectroscopy in the spectral fingerprint region
Authors: Chimento P. F. , Jurna M. , Bouwmans H. S. P. , Garbacik E. T. , Hartsuiker L. , Otto C. , Herek J. L. , Offerhaus H. L.
Published: March 2009

Coherent anti‐Stokes Raman scattering (CARS) spectroscopy is an important technique for spectroscopy and chemically selective microscopy, but wider implementation requires dedicated versatile tunable sources. We describe an optical parametric oscillator (OPO) based on a magnesium oxide‐doped periodically poled lithium niobate crystal, with a novel variable output coupler, used as a tunable coherent light source. The OPO's signal wavelength ranges from 880 to 1040 nm and its idler wavelength from 1090 to 1350 nm.

We use this OPO to demonstrate high‐resolution narrowband CARS spectroscopy on bulk polystyrene from 900 to 3600 cm−1, covering a large part of the molecular fingerprint region. Recording vibrational spectra using narrowband CARS spectroscopy has several advantages over spontaneous Raman spectroscopy, which we discuss. We isolate the resonant part of the CARS spectrum and compare it to the spontaneous Raman spectrum of polystyrene using the maximum entropy method of phase retrieval; we find them to be in extremely good agreement. Copyright © 2009 John Wiley & Sons, Ltd.
Preparation of polyaniline/vermiculite clay nanocomposites by in situ chemical oxidative grafting polymerization
Authors: Tang Zhaobin , Liu Peng , Guo Jinshan , Su Zhixing
Published: March 2009

BACKGROUND: Recently, conducting polymers have attracted much attention, since they have interesting physical properties and many potential applications, such as in conductive coating charge storage. Hence the synthesis of conducting polymer nanocomposites is also an area of increasing research activity.

RESULTS: Vermiculites (VMTs) were successfully delaminated using an acid treatment. Polyaniline (PANI)/VMT nanocomposites were prepared by in situ chemical oxidative grafting polymerization.

CONCLUSION: The chemical grafting of PANI/VMTs was confirmed by Fourier transform infrared and UV‐visible spectroscopy. The percentage of grafted PANI was 142.7 wt% as a mass ratio of the grafting PANI and charged nano‐VMTs, investigated using thermogravimetric analysis. In addition, characteristic agglomerate morphology of PANI was observed in the composites using scanning electron microscopy. Thermal analyses indicated that the introduction of VMT nanosheets had a beneficial effect on the thermal stability of PANI. The electrical conductivity of the nanocomposites was 3.9 × 10−3 S cm−1, a value typical for semiconductors. Copyright © 2009 Society of Chemical Industry
Modelling and analysis techniques for cross‐organizational workflow systems
Authors: Xu Lida , Liu Huimin , Wang Song , Wang Kanliang
Published: March 2009

Emerging e‐business, e‐commerce, and virtual enterprises are leading to the trend of managing workflows across organizational boundaries. A cross‐organizational workflow is generally comprised of intra‐organizational workflows and inter‐organization workflows. The modeling techniques for the intra‐organizational workflows are relatively matured. In this paper, they are briefly reviewed and contrasted to show their strong points and weaknesses. The modeling approaches for the inter‐organizational workflows is emphasized and introduced in detail in this paper. The inter‐organizational workflow emphasizes more on combining the workflows of different partners together and reconciling the relationships between them. Thus, the modeling approaches are described in two directions by their functions: routing languages introduced to combine individual workflows and interaction patterns proposed for collaborative partners to interact with each other. In this paper, some techniques are summarized, and some interesting research issues in the area are discussed in both technical and managerial perspectives. Copyright © 2009 John Wiley & Sons, Ltd.
An optimal bandwidth allocation and data droppage scheme for differentiated services in a wireless network
Authors: Sheikh Waseem , Ghafoor Arif
Published: March 2009

This paper presents an optimal proportional bandwidth allocation and data droppage scheme to provide differentiated services (DiffServ) for downlink pre‐orchestrated multimedia data in a single‐hop wireless network. The proposed resource allocation scheme finds the optimal bandwidth allocation and data drop rates under minimum quality‐of‐service (QoS) constraints. It combines the desirable attributes of relative DiffServ and absolute DiffServ approaches. In contrast to relative DiffServ approach, the proposed scheme guarantees the minimum amount of bandwidth provided to each user without dropping any data at the base‐station, when the network has sufficient resources. If the network does not have sufficient resources to provide minimum bandwidth guarantees to all users without dropping data, the proportional data dropper finds the optimal data drop rates within acceptable levels of QoS and thus avoids the inflexibility of absolute DiffServ approach. The optimal bandwidth allocation and data droppage problems are formulated as constrained nonlinear optimization problems and solved using efficient techniques. Simulations are performed to show that the proposed scheme exhibits the desirable features of absolute and relative DiffServ. Copyright © 2009 John Wiley & Sons, Ltd.
A distributed MAC scheme supporting voice services in mobilead hocnetworks
Authors: Jiang Hai , Wang Ping , Poor H. Vincent , Zhuang Weihua
Published: March 2009

Future mobilead hocnetworks are expected to support voice traffic. The requirement for small delay and jitter of voice traffic poses a significant challenge for medium access control (MAC) in such networks. User mobility presents unique difficulties in this context due to the associated dynamic path attenuation. In this paper, a MAC scheme for mobilead hocnetworks supporting voice traffic is proposed. With the aid of a low‐power probe prior to DATA transmissions, resource reservation is achieved in a distributed manner, thus leading to small packet transmission delay and jitter. The proposed scheme can automatically adapt to dynamic path attenuation in a mobile environment. Statistical multiplexing of on/off voice traffic can also be achieved by partial resource reservation for off voice flows. Simulation results demonstrate the effectiveness of the proposed scheme. Copyright © 2009 John Wiley & Sons, Ltd.
Individual‐based modeling of the spread of pine wilt disease: vector beetle dispersal and the Allee effect
Authors: Takasu Fugo
Published: March 2009

Pine wilt disease is caused by the pinewood nematode Bursaphelenchus xylophilus, which is vectored by the Japanese pine sawyer beetle Monochamus alternatus. Due to their mutualistic relationship, according to which the nematode weakens and makes trees available for beetle reproduction and the beetle in turn carries and transmits the nematode to healthy pine trees, this disease has resulted in severe damage to pine trees in Japan in recent decades. Previous studies have worked on modeling of population dynamics of the vector beetle and the pine tree to explore spatial expansion of the disease using an integro‐difference equation with a dispersal kernel that describes beetle mobility over space. In this paper, I revisit these previous models but retaining individuality: by considering mechanistic interactions at the individual level it is shown that the Allee effect, an increasing per‐capita growth rate as population abundance increases, can arise in the beetle dynamics because of the necessity for beetles to contact pine trees at least twice to reproduce successfully. The incubation period after which a tree contacted by a first beetle becomes ready for beetle oviposition by later beetles is crucial for the emergence of this Allee effect. It is also shown, however, that the strength of this Allee effect depends strongly on biological mechanistic properties, especially on beetle mobility. Realistic individual‐based modeling highlights the importance of how spatial scales are dealt with in mathematical models. The link between mechanistic individual‐based modeling and conventional analytical approaches is also discussed.
Identification of LTR‐specific small non‐coding RNA in FeLV infected cells
Authors: Forman Lora W. , Pal-Ghosh Ruma , Spanjaard Remco A. , Faller Douglas V. , Ghosh Sajal K.
Published: March 2009

The U3‐LTR region of leukemia viruses transactivates cancer‐related signaling pathways through the production of a non‐coding RNA transcript although the role of this transcript in virus infection remains unknown. In this study we demonstrate for the first time that an long terminal repeat (LTR)‐specific small non‐coding RNA is produced from a feline leukemia virus (FeLV)‐infected feline cell line. RNA cloning identified this as a 104 base transcript that originates from the U3‐LTR region. We also demonstrate that in in vitro assays this LTR‐RNA transcript activates NFκB signaling. Taken together, our findings suggest a possible role for this LTR transcript in FeLV pathogenesis.
Periconception folic acid supplementation, fetal growth and the risks of low birth weight and preterm birth: the Generation R Study
Authors: Timmermans Sarah , Jaddoe Vincent W. V. , Hofman Albert , Steegers-Theunissen Régine P. M. , Steegers Eric A. P.
Published: March 2009

Countries worldwide, including the Netherlands, recommend that women planning pregnancy use a folic acid supplement during the periconception period. Some countries even fortify staple foods with folic acid. These recommendations mainly focus on the prevention of neural tube defects, despite increasing evidence that folic acid may also influence birth weight. We examined whether periconception folic acid supplementation affects fetal growth and the risks of low birth weight, small for gestational age (SGA) and preterm birth, in the Generation R Study in Rotterdam, the Netherlands. Main outcome measures were fetal growth measured in mid- and late pregnancy by ultrasound, birth weight, SGA and preterm birth in relation to periconception folic supplementation (0·4–0·5 mg). Data on 6353 pregnancies were available. Periconception folic acid supplementation was positively associated with fetal growth. Preconception folic acid supplementation was associated with 68 g higher birth weight (95 % CI 37·2, 99·0) and 13 g higher placental weight (95 % CI 1·1, 25·5), compared to no folic acid supplementation. In these analyses parity significantly modified the effect estimates. Start of folic acid supplementation after pregnancy confirmation was associated with a reduced risk of low birth weight (OR 0·61, 95 % CI 0·40, 0·94). Similarly, reduced risks for low birth weight and SGA were observed for women who started supplementation preconceptionally, compared to those who did not use folic acid (OR 0·43, 95 % CI 0·28, 0·69 and OR 0·40, 95 % CI 0·22, 0·72). In conclusion, periconception folic acid supplementation is associated with increased fetal growth resulting in higher placental and birth weight, and decreased risks of low birth weight and SGA.
Governing Aliens in Times of Upheaval: Immigration Control and Modern State Practice in Early Twentieth-Century Britain, Compared with Prussia
Authors: Reinecke Christiane
Published: March 2009

In the history of immigration control, the period from the 1880s to the 1920s saw an international dynamic of growing restrictions. World War I in particular has been regarded as watershed marking the end of laissez-faire migration policy. But whether 1914 can be seen as a crucial turning point depends on the country under consideration, as well as on the chosen analytical approach. Analysing Britain’s politics of immigration control before and after the war and comparing it with its Prussian equivalent, this article discusses the shifts and continuities in the concrete administration of migration. Focusing on the changing practice of expelling foreigners, it suggests a chronology of control that does not entirely correspond with the overall political changes. By 1918, the British bureaucracy possessed elaborate means to monitor aliens, and the state increasingly impacted on the migrants’ lives. In contrast, Prussia was maintaining a tightly regulated regime already, which its authorities had established well before 1914.
The Improvement of Poor Pastures
Authors: Middleton T. H.
Published: March 2009

1. The results of six experiments in the manuring of poor pastures are described. The experiments were made in the counties of Northumberland, Northampton, Cambridge, Essex, Norfolk, and Hants. The results are given for a period of three years at all stations (except Norfolk, two years), and for two further periods of three and two years at the Northumberland station.

2. In Norfolk on a light soil a potash manure slightly improved the pasture; the other manures had no influence on the yield. At the remaining five stations on heavy soils phosphatic manures produced highly profitable returns. In the first period, the use of other manures was not justified by the results. Where, however, the experiment was continued for eight years, lime proved profitable in the second, and potash in the third period. Under the special conditions of the experiment nitrogenous manures were either injurious or but very slightly increased the yield.
Probable Error in Pig Feeding Trials
Authors: Robinson G. W. , Halnan E. T.
Published: March 2009

In a recent number of this Journal, T. B. Wood and F. J. M. Stratton have discussed the probable error of field and feeding experiments, but in the latter case their investigations included only cattle and sheep.

The following work was undertaken as a necessary preliminary to a series of pig feeding experiments which are in contemplation. It is published at once in the hope that the results obtained may be of use to others who may be engaged in planning similar feeding trials.