bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Mixed H2O—CH3CN and H2O—HCONMe2 Solvents on the Rate of Cleavage of N-Benzylphthalamic Acid
Authors: Cheong May-Ye , Ariffin Azhar , Khan Mohammad Niyaz
Published: July 2008

The values of pseudo first-order rate constants, k1, for the O-cyclization and k3 for N-cyclization of N-benzylphthalamic acid 1, obtained at 0.02 M HCl and 35°C, show a respective nonlinear increase from 17.6 × 10−6 to 29.7 × 10−6 s−1 and decrease from 12.5 × 10−7 to 3.75 × 10−7 s−1 with increase in the CH3CN content from 2 to 60% v/v in mixed aqueous solvent. Increase in the CH3CN content from 60 to 90% v/v decreases k1 from 29.7 × 10−6 to 24.4 × 10−6 s−1 and increases k3 from 3.75 × 10−7 to 14.7 × 10−7 s−1. The respective values of k1 and k3 decrease nonlinearly from 16.0 × 10−6 to 3.0 × 10−6 s−1 and 14.0 × 10−7 to ~4.0 × 10−7 s−1 with increase in the content of N,N-dimethylformamide (HCONMe2) from 2 to 80% v/v in mixed aqueous solvents. These results indicate rather mild rate-retarding effects of mixed H2O—CH3CN and H2O—HCONMe2 solvents on the rates of the intramolecular reactions.
Theoretical Study of Solvent and Substituent Effects on the Reactions of 1,4-Benzoquinone with Cyclopentadiene and Cyclohexadiene
Authors: Haqghu Mohammad , Irani Mehdi , Gholami Mohammad Reza
Published: July 2008

Ab initio quantum mechanics and ONIOM calculations were used to study solvent and substituent effects on the reactions of 1,4-benzoquinone with cyclopentadiene and cyclohexadiene derivatives in tetrahydrofuran and greater water solvents. These calculations revealed (i) that increasing the number of electron donating methyl group substituents and (ii) the proximity of substituents to the reacting carbons (carbon atoms which contribute to the forming C—C bonds) on the diene, promote charge transfer from the diene to the dienophile in the transition state. These effects increase the negative charge on the oxygen atoms, destabilize the transition state in the organic solvent by increasing steric interactions, and stabilize the transition state in water solvent by increasing the strength of hydrogen bonding. These results, along with consideration of variations in the solvent-accessible surface area (SASA) confirmed that the dramatic acceleration in the rate of the studied reactions in water solvent arise in part from hydrophobic association of the reactants, but predominantly arise from hydrogen bonding between water molecules and the polarized transition state.
Portraits des forestiers de l'an 2050 (essai) | Portraits of foresters in the year 2050 (essay)
Authors: Métral Roland
Published: July 2008

In the year 2050, the forest will have experienced some more or less significant changes due to the price of wood, the harvesting techniques and natural hazards. More women will be employed within the forest service and the “new forester” will work in a team and be open for changes. In the future, the forest owners' titles will still be restricted by law and the administrative directives.
Nachhaltigkeit und Vielfalt als Zukunftswerte (Essay) | Sustainability and diversity as future values (essay)
Authors: Sieber Otto
Published: July 2008

With an emphasis on biodiversity, this paper focuses on current trends in the Swiss forests. In particular, the continuity of these current trends over the coming decades and the permanent values which will influence Swiss forests and forestry in the future will be discussed. Most of the current trends may persist and include the growing forest area in regions with a weak agricultural potential, the pressure on forests due to urban sprawl, and intensified harvesting with more efficient methods due to the increased use of renewable energies while considering climate change. The forests may change to become more in accordance with the location and forest reserves may become more frequent. Sustainability and diversity are the main values which will shape forests and forestry also in the year 2050.
Kleinflächig spezialisierter, aber weiterhin multifunktionaler Schweizer Wald (Essay) | Typically patchy but multifunctional Swiss forest (essay)
Authors: Schneiter Anja , Sorg Annina
Published: July 2008

Forests and forestry in the year 2050 may be described based on social, ecological and economical influence factors and their consequences. Increased pressure through human settlements and a polarized behaviour during leisure time both belong to social developments which are relevant to the forest. Furthermore, the benefits of a forest such as fresh air, clean water and free access may be assigned a monetary value in the future, whereas currently they are not. In the future, the ecological conditions may be strongly influenced by climate change. The Swiss forest as a whole is not currently in danger; however, pronounced climatic extremes may soon cause extended damage. As a result, the management of protection forests may become even more important. Economical developments such as the shortage of oil and the price increase of natural resources will have consequences for the forest management. Thus, the demand for wood as a source of energy and a substitute for other resources will increase.

All these changes will increase the conflict of interests in the Swiss forest until the year 2050. This will lead to the fact that the various uses of the forest will be segregated more intensely and its multifunctionality will obtain a more important meaning on a higher level.
Wald 2050 – Rückblicke in die Zukunft aus fünf Perspektiven (Essay) | Forest 2050 – review on the future from five perspectives (essay)
Authors: Suda Michael , Schaffner Stefan
Published: July 2008

With the reviews on the future of the forest, the Chair of Forest and Environmental Policy of the Technische Universität München is free to present an experiment on how people may describe forests in the future. For this experiment we approach five different characters which describe what their environment and the world will be like in the year 2050 from different perspectives. Based on five stories about the forests’ future, we reflect on how we may experience and describe the world and the forests with diverse scenarios. We do not provide a solution as to how the future may look but we would like to awaken hope in our future nevertheless.
Wohlstandszunahme als Konstante des Wandels (Essay) | Increase of prosperity as a constant of changes (essay)
Authors: Zürcher Boris
Published: July 2008

The Swiss per-capita income may further increase up to the year 2050. In addition to this materialistic prosperity, further indicators for prosperity are expected to improve significantly, such as life expectancy and a decreasing rate of infant mortality. New products and services will come on the market at reasonable prices. Overall, there are few reasons to assume that the current trend of recorded increase in prosperity will suddenly stop; however, there will be changes in the sectoral composition of employment and value creation. The forest services will remain a niche business. The importance of the forest, however, will increase – not due to timber production but due to the increasing need for recreation.
Palladium‐Catalyzed Trimerizations of Terminal Arylalkynes: Synthesis of 1,3‐Diaryl‐2‐arylethynyl‐1,3‐butadienes[1]
Authors: Wu Yao‐Ting , Lin Wei‐Chih , Liu Chia‐Ju , Wu Chuan‐Yi
Published: July 2008

Various 1,3‐diaryl‐2‐arylethynyl‐1,3‐butadienes 7 have been prepared by the Pd‐catalyzed trimerization of arylalkynes 4. Their structures and stereochemistry have been confirmed by X‐ray crystal analyses. This procedure provides high regioselectivity to generate adducts Z‐7 in moderate to excellent yields. The scope, limitations and regioselectivity of this reaction have been investigated. In DMSO at 180 °C, 1,3‐di(1‐naphthalenyl)‐2‐(1‐naphthalenylethynyl)‐1,3‐butadiene (7m) underwent 6π‐electrocyclization to form 2‐(1‐naphthalenyl)‐3‐(1‐naphthalenylethynyl)‐1,2‐dihydrophenanthrene (21). Under acidic conditions, (1Z)‐1,3‐diphenyl‐2‐(1‐phenylethynyl)‐1,3‐butadiene (Z‐7a) was converted to 1‐methyl‐3‐phenyl‐2‐(2‐phenyl‐1‐ethionyl)‐2‐indene (22) in 75% yield.
Highly Efficient and Stereoselective Julia–Kocienski Protocol for the Synthesis of α‐Fluoro‐α,β‐unsaturated Esters and Weinreb Amides Employing 3,5‐Bis(trifluoromethyl)phenyl (BTFP) Sulfones
Authors: Alonso Diego A. , Fuensanta Mónica , Gómez‐Bengoa Enrique , Nájera Carmen
Published: July 2008

α‐Fluoroacetates 3 and Weinreb amide 4, bearing a α‐[3,5‐bis(trifluoromethyl)phenyl]sulfonyl (BTFP‐sulfonyl) group at the α‐position, are employed in the highly stereoselective synthesis of α‐fluoro‐α,β‐unsaturated alkenoates and Weinreb amides, respectively. Aromatic and aliphatic aldehydes are condensed under extremely mild and simple reaction conditions using potassium carbonate in dimethylformamide at room temperature under solid‐liquid phase‐transfer catalysis conditions in good yields and high Z‐diastereoselectivities, specially in the case of the fluorinated Weinreb amides. A detailed computational mechanistic study suggests a final non‐concerted elimination of sulfur dioxide and 3,5‐bis(trifluoromethyl)phenoxide and explains the observed high stereoselectivities for the reaction on the basis of thermodynamic and kinetic considerations.
New Functionalized Vinyl Monomers by Ethylene‐(Functionalized)‐Norbornene Hetero‐Trimerization Catalyzed by Cobalt(II)‐(Imino)pyridine Complexes
Authors: Toti Alessandro , Giambastiani Giuliano , Bianchini Claudio , Meli Andrea , Luconi Lapo
Published: July 2008

On activation by MAO the (imino)pyridine cobalt(II) complex CoCl2N2 catalyzes the enchainment of one norbornene (NB) molecule with two ethylene molecules to give exo‐2,exo‐3‐ethylvinylnorbornane with high activity and complete diastereoselectivity. Turnover frequencies [TOF, mol NB (mol Co×h)−1] as high as 270,000 have been obtained. The 2E‐1NB hetero‐trimerization reaction has been also accomplished with NBs bearing polar substituents such as norbornenemethanol and norbornenecarboxylic acid provided that the substrate is protected with triisobutylaluminum and the less sterically demanding complex CoCl2N2 is used as catalyst precursor. A mechanism for the hetero‐trimerization reactions is proposed on the basis of experimental evidence.
Organocatalytic and Enantioselective Direct Vinylogous Michael Addition to Maleimides
Authors: Lu Jun , Zhou Wei‐Juan , Liu Feng , Loh Teck‐Peng
Published: July 2008

An organocatalytic enantioselective direct vinylogous Michael addition of α,α‐dicyanoolefins to maleimide has been developed; the products could be obtained in good yields and high enantioselectivities.
Copper‐Catalyzed Cycloaddition of Sulfonyl Azides with Alkynes to Synthesize N‐Sulfonyltriazoles ‘on Water’ at Room Temperature
Authors: Wang Feng , Fu Hua , Jiang Yuyang , Zhao Yufen
Published: July 2008

We have developed a green and practical method for the Huisgen cycloaddition of water‐insoluble sulfonyl azides with alkynes ‘on water’ at room temperature under catalysis of the inexpensive catalyst system CuX/PhSMe, and addition of the ligand (thioanisole) greatly inhibited cleavage of the N1N2 bond in the 5‐cuprated N‐sulfonyltriazole intermediates to amides and improved the yields of N‐sulfonyltriazoles.
Aerobic Oxidations Catalyzed by Zeolite‐Encapsulated Cobalt Salophen
Authors: Johansson Mikael , Purse Byron W. , Terasaki Osamu , Bäckvall Jan‐E.
Published: July 2008

Cobalt salophen was encapsulated in a series of zeolites with a wide variation of the silicon‐to‐aluminium atomic ratio and with different cations. The zeolite‐cobalt salophen catalysts were prepared using the “ship‐in‐a‐bottle technique” where the complex was synthesized in the super cage of the zeolite and therefore locked into the pocket. The encapsulated catalysts were then tested in the aerobic oxidation of hydroquinone to p‐benzoquinone; the best encapsulated catalyst was shown to be an efficient electron‐transfer mediator in a palladium‐catalyzed aerobic oxidative carbocyclization.
Iminium Salt‐Catalysed Asymmetric Epoxidation using Hydrogen Peroxide as Stoichiometric Oxidant
Authors: Page Philip C. Bulman , Parker Phillip , Rassias Gerasimos A. , Buckley Benjamin R. , Bethell Donald
Published: July 2008

Iminium salt organocatalysts can provide high selectivity and high efficiency in catalytic asymmetric epoxidation. They are normally used in conjunction with Oxone as the stoichiometric oxidant. Oxone, however, has limited stability and is insoluble in most organic solvents; we report here for the first time the development of a reaction system driven by hydrogen peroxide as the stoichiometric oxidant, involving an unusual double catalytic cycle.
Electron‐Rich, Bicyclic Biaryl‐Like KITPHOS Monophosphines via [4+2] Cycloaddition between 1‐Alkynylphosphine Oxides and Anthracene: Highly Efficient Ligands for Palladium‐Catalysed CN and CC Bond Formation
Authors: Doherty Simon , Knight Julian G. , Smyth Catherine H. , Jorgenson Graeme A.
Published: July 2008

Electron‐rich, bicyclic biaryl‐like KITPHOS monophosphines have been prepared via Diels–Alder cycloaddition between 1‐alkynylphosphine oxides and anthracene in an operationally straightforward and highly modular synthetic protocol that will allow access to an architecturally and electronically diverse family of ligands. Palladium complexes of these ligands are highly efficient catalysts for the Buchwald–Hartwig amination and Suzuki–Miyaura coupling of a wide range of aryl chlorides, which for the vast majority of substrate combinations outperform their o‐(dicyclohexylphosphino)biphenyl‐based counterparts.
Semicontinuous distillation for ethyl lactate production
Authors: Adams Thomas A. , Seider Warren D.
Published: July 2008

A novel semicontinuous process for the production of ethyl lactate from ethanol and lactic acid is studied. The process utilizes a middle vessel integrated with a distillation column to perform a ternary separation of the reaction mixture. A pervaporation unit separates ethanol from water. This new form of process intensification is shown to be economically superior to traditional batch and continuous alternatives for a wide range of production rates. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Polymorphisms in the 3′ UTR of the serotonin transporter are associated with cognitive flexibility in rhesus macaques
Authors: Vallender Eric J. , Lynch Laurie , Novak Melinda A. , Miller Gregory M.
Published: July 2008

The serotonin system is an important neurophysiological mediator of many behavioral phenotypes. Genetic variation within this system is thought to contribute not only to the natural range of behavioral differences, but also to neuropsychiatric pathologies. Cognitive flexibility, the ability to change patterns of response as reward context shifts, is an important trait that underlies many complex social interactions. Environmental manipulations of the serotonin system have been shown to alter performance on tests measuring cognitive flexibility. Variation at the serotonin transporter promoter region (5HTTLPR) has recently been shown to associate with the performance of rhesus monkeys on an object discrimination reversal learning task [Izquierdo et al., 2007]. Here, we demonstrate that functional genetic variation at the serotonin transporter 3′ untranslated region, independent of 5HTTLPR, also associates with performance in an object discrimination reversal learning task in rhesus macaques. The polymorphisms comprising the T:G:T haplotype (T1970, G1991, and T2327) were associated with fewer errors on a reversal learning test and greater levels of cognitive flexibility. We have previously demonstrated that the T:G:T haplotype renders lower levels of gene expression in vitro, paralleling the functionality of human 3′ UTR haplotypes, as well as the short allele of 5HTTLPR found in both macaques and humans. The 3′ UTR haplotypes are independent and in linkage equilibrium with the 5HTTLPR locus. Together, these data lead to the intriguing possibility that differences observed in human cognitive flexibility, whether naturally or in pathological states, may be associated with genetic variation in the serotonin transporter 3′ untranslated region also. © 2008 Wiley‐Liss, Inc.
Helminth infections associated with multiple sclerosis induce regulatory B cells
Authors: Correale Jorge , Farez Mauricio , Razzitte Gabriela
Published: July 2008

Objective

To assess the importance of B‐cell control during parasite infections in multiple sclerosis (MS) patients.

Methods

Peripheral blood CD19+ B cells from 12 helminth‐infected MS patients, 12 MS patients without infection, 10 patients infected with Trypanosoma cruzi, 8 subjects infected with Paracoccidioides brasiliensis, and 12 healthy control subjects were purified using magnetic cell sorting. Interleukin (IL)‐4, IL‐6, IL‐10, tumor necrosis factor‐α, lymphotoxin, transforming growth factor‐β, brain‐derived neurotrophic factor, and nerve growth factor secretion were evaluated after stimulation with CDw32 L cells and CD40 antibody using enzyme‐linked immunosorbent assays. The production of anti–myelin oligodendrocyte glycoprotein IgG and IgM antibodies was evaluated by enzyme‐linked immunosorbent spot assays. Cell phenotype was assessed by flow cytometry.

Results

Helminth infections in MS patients created a B‐cell population producing high levels of IL‐10, dampening harmful immune responses through a mechanism mediated, at least in part, by the ICOS‐B7RP‐1 pathway. The IL‐10–producing B‐cell phenotype detected expressed high levels of CD1d and was similar to the one observed in mature naive B2 cells (namely, CD11b−, CD5−, CD27−, and IgD+). Moreover, B cells isolated from helminth‐infected MS patients also produced greater amounts of brain‐derived neurotrophic factor and nerve growth factor compared with those of normal subjects, T. cruzi–infected subjects, P. brasiliensis–infected subjects, or uninfected MS patients, raising the possibility that these cells may exert a neuroprotective effect on the central nervous system.

Interpretation

Increased production of B‐cell–derived IL‐10 and of neurotrophic factors are part of the parasite's regulation of host immunity and can alter the course of MS, potentially explaining environmental‐related MS suppression observed in areas with low disease prevalence. Ann Neurol 2008
Control degrees of freedom using the restraining number: further evaluation
Authors: Vasudevan Suraj , Konda N. V. S. N. Murthy , Rangaiah Gade Pandu
Published: July 2008

A simple and effective procedure for the computation of control degrees of freedom (CDOF) using the concept of restraining number has been recently proposed by our group. The goal of the present contribution is to further evaluate and enhance this procedure. The restraining number is applied to a few more important units. In particular, a detailed analysis has been done for determining the restraining number of membrane separators, given their increasing importance in the industry today. The restraining number procedure is then successfully applied to compute the CDOF of several industrial‐scale processes with distinctly unique characteristics. The simplicity, reliability, general applicability and effectiveness of the procedure are thus further demonstrated. To sum up, the present contribution improves upon and details the CDOF procedure clearly, discusses further issues like the restraining number for variable speed pumps and membrane separators, redundancies for absorbers and strippers and finally, the applicability of this procedure to three‐phase distillation columns and complex industrial processes. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
A complex process of the asymmetric reduction of prochiral aromatic ketone by yeast cell with the introduction of an organic solvent as the separation medium
Authors: Yang Zhong‐Hua , Zeng Rong , Wang Yu , Li Wei , Lv Zao‐Sheng
Published: July 2008

Enantiomerically pure aromatic alcohols are important chiral building blocks for many single enantiomer pharmaceuticals. The asymmetric reduction of the corresponding prochiral ketone by active yeast cells is one of the most promising synthesis routes for chiral alcohols. But the space‐time productivity is low. To promote the reaction, a complex process of the asymmetric reduction reaction with the introduction of an organic solvent as a separation factor was studied in this work. The asymmetric reduction of acetophenone (ACP) to chiral α‐phenylethyl alcohol (PEA) by Saccharomyces cerevisiae was chosen as the model reaction. It was found that organic solvents with more than 3.5 of logP, such as n‐octane, were favorable for the asymmetric reduction reaction. The yield of the reaction could be remarkably promoted with this technique. The reaction could further be improved by adding ethanol as cosolvent. The initial ACP concentration could be as high as 60 mmol/l, which is about six times larger than that of reacting in a single aqueous phase. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
Lattice Boltzmann simulations of flows with fluid–fluid interfaces
Authors: Jia Xinli , McLaughlin J. B. , Kontomaris K.
Published: July 2008

This paper reviews recent developments of the lattice Boltzmann method (LBM) for the simulation of isothermal flows containing fluid–fluid interfaces. Two formulations of the fluid–fluid LBM and some recent variants of these formulations are discussed. Simulation results are assessed through comparisons with experimental data or theoretical analyses. The goal of this review is to facilitate the judicious application of the LBM to practical flows. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
Light intensity distribution in heterogenous photocatalytic reactors
Authors: Pareek Vishnu , Chong Siewhui , Tadé Moses , Adesina Adesoji A.
Published: July 2008

In this paper, we have discussed the state of the art on numerical techniques for estimating light intensity distribution in photocatalytic reactors. After giving a brief introduction to various photocatalytic reactor designs, a detailed derivation of the radiation transport equation (RTE) has been presented. The RTE is an integrodifferential equation and needs appropriate boundary conditions and optical properties of the medium. To provide a boundary condition for the light emitted from the radiation sources, a number of lamp source models have been described. Different approaches for the numerical simulation of the RTE have been presented with special emphasis on the Monte Carlo and finite volume (or discrete ordinate) approaches. In the Monte Carlo approach, the reaction space was divided into small cubical cells. The path of a photon was traced using a stochastic approach. A conservative variant of the discrete ordinate model available in FLUENT was used to assess the effect of wall reflectivity, catalyst loading, and phase function parameter on the light intensity distribution. For relatively low catalyst loadings, the wall reflectivity strongly influenced the light intensity distribution. However, for an optically thick medium, the wall reflectivity had very little or no effect. The volume‐averaged light intensity distribution decreased rather sharply with the catalyst loading and an opposite trend was obtained for LVREA. Finally, a semiempirical kinetic model was presented to evaluate the rate of reaction and conversion of a photoreactor using the computational fluid dynamics (CFD) approach. Model verification was carried out using experimental data for photodegradation of Bayer liquor. A correlation coefficient of 0.974 between simulated and experimental results indicated that the proposed model was adequate. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
Correlations for the grindability of the ball mill as a measure of its performance
Authors: Sahoo A. , Roy G. K.
Published: July 2008

A ball mill is the vital component in industries viz. mineral dressing, ore processing, fertilizers, food and diary, pharmaceuticals and many others. The present work involves a meticulous study of the effects of the various parameters on the performance of a ball mill. The parameters studied in this work are particle size, number of balls, time of grinding, particle density, and speed of the ball mill (rpm). An attempt has been made to develop correlation for the performance of the ball mill by correlating these variables with the grindability on the basis of dimensional analysis approach as well as fractional factorial design method. It is observed that these parameters influence the performance of the ball mill significantly. The performance of a ball mill is measured with reference to the quantity of undersize or fines (amount of ground material passing through a 120‐mesh screen) per revolution of the mill, collected for variation of each of the individual parameters.

Finally, the calculated values of the fines in terms of the grindability of the mill obtained through the correlations by both the above‐mentioned methods are compared with the experimental values, thereby justifying the analysis with reasonable deviations. Thus, the developed correlations can be applied to know the grindability of the ball mill over a wide range of parameters. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
A novel atmospheric freeze‐dryer using vortex tube and multimode heat input: simulation and experiments
Authors: Rahman S. M. A. , Mujumdar Arun S.
Published: July 2008

This article presents a study of a novel fixed‐bed atmospheric freeze‐dryer using a vortex tube to generate cryogenic temperature air for drying and multimode heat supply. A two‐layer moving boundary model was developed to simulate the variation of the transient moisture content distribution in the drying product in the form of a thin slab, sublimation front temperature, location of the sublimation front and moisture content as well as temperature distribution inside the dry layer. An experimental setup was designed and fabricated to verify the predicted results. A series of experiments were conducted using rectangular and disc‐shaped potato and carrot samples, as model heat‐sensitive products. Effects of different modes of heat input in various combinations on the drying rate were also investigated both experimentally and numerically. Fairly good agreement was found between the predicted values and the experimental data. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
Statistical optimization and kinetic modeling of xylanase production by Arthrobacter sp.
Authors: Rajendran Aravindan , Selvaraj Vimalnath , Thangavelu Viruthagiri
Published: July 2008

Xylanases are hydrolytic enzymes which randomly cleave the β‐1, 4 backbone of the complex plant cell wall polysaccharide xylan. Diverse forms of these enzymes exist, displaying varying folds, mechanisms of action, substrate specificities, hydrolytic activities, and physicochemical characteristics. This article focuses on the fermentative production of xylanase from Arthrobacter sp. and the factors affecting the production. The batch‐submerged fermentation was carried out in a 250‐ml Erlenmeyer flask. The inoculum size of 5% v/v, initial pH of 7.0, and shaking speed of 150 rpm at 32 °C were maintained for the optimization of medium components. The cell growth, xylanase activity, cellulase activity, protein, and pH were determined at regular time intervals. Plackett–Burman statistical methodology was adopted to study the effect of media components on xylanase production. The effect of temperature and pH was studied using optimized medium composition determined by Plackett–Burman experimental design. The maximum xylanase activity of 4.0 U ml−1 at 84 h at the optimum temperature of 35 °C and pH of 7.0 was obtained. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
Molecular‐scale investigation of polymerization, nucleation, and growth of polystyrene particle by atomic force microscopy
Authors: Yamamoto Tetsuya , Higashitani Ko
Published: July 2008

To clarify the mechanism of the nucleation and growth processes in the soap‐free polymerization of polystyrene latex particles in water, the polymerization process was investigated on a molecular scale, by using an atomic force microscope (AFM), as well as a scanning electron microscope (SEM) and a dynamic light scattering apparatus (DLS). A ‘cationic’ initiator was employed to make all the polymeric materials produced, such as oligomers, embryos, nuclei, and grown particles, adsorb electrostatically on the negatively charged mica plate of molecular‐scale smoothness. This in situ transfer of polymeric materials in the bulk onto the mica surface enables us to observe the images of polymeric materials during the reaction process and to estimate what is happening in the nucleation and growth processes of particles, at least qualitatively. The most important findings of the present study are that1 these molecular‐scale polymeric materials, to which much attention has not been paid probably because of the difficulty of detection, are continuously born in the bulk throughout the reaction process of particle formation, and2 they play an important role in the growth of particles. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
The forces at work in colloidal self‐assembly: a review on fundamental interactions between colloidal particles
Authors: Li Qin , Jonas Ulrich , Zhao X. S. , Kappl Michael
Published: July 2008

Colloidal particles with well‐defined sizes can self‐assemble into ordered, crystalline structures under non‐equilibrium conditions. This phenomenon originates from the various forces acting upon them. In this article, we provide an overview on the forces at work in a colloidal system, in particular, the roles of these forces at various stages in colloidal self‐assembly. Van der Waals, electrostatic, hydrodynamic, and capillary forces, as well as Brownian motions, are extensively discussed, whereas other types of interactions are briefly introduced and summarized. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
Fabrication of gold/silica composite artificial opal by a multiple‐step electroplating process
Authors: Li Wenjiang , Xie Fei , Sun Tan , Liao Yufeng
Published: July 2008

Artificial opal with a three‐dimensional periodic structure was prepared using mono‐dispersed silica microspheres by a force packing method in an Indium Tin Oxide (ITO) glass cell. The gold/silica composite opal was obtained through the infiltration of gold nano‐particles into the voids of the silica opals by electroplating technique. The transmission and reflection spectrum of the gold/silica composite opal presented a red shift with increasing electroplating time. The optical images were taken after each treatment of electroplating–washing–drying circle, which were precisely selected at same area using an optical microscope. The SEM images show that the gold nano‐particles could be directly deposited on the surface of silica spheres in the opaline structure after electroplating. We proposed that the effective refractive index of the composite opal was increased because of the infiltration of gold, which resulted in the spectra shifting to a longer wavelength. The gold/silica composite opal film could provide a simple way to tune the opal properties by controlling the ratio of gold in the silica opal. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
Synthesis and characterization of M‐ZSM‐5 composites prepared from ZSM‐5 zeolite
Authors: Song Chun‐Min , Yan Zi‐Feng
Published: July 2008

Micromesoporous M‐ZSM‐5 composites were hydrothermally synthesized by the self‐assembly of precursors, alkali‐treated ZSM‐5 nanoparticles, with CTMABr surfactant in alkaline media and characterized by X‐ray diffraction (XRD), N2 adsorption, Fourier transform infrared (FT‐IR), transmission electron microscopy (TEM) etc. The XRD and TEM results indicated the M‐ZSM‐5 composites possess ordered hexagonal structure, and the wall of mesopore contains micropores due to the secondary‐building units of the structure of ZSM‐5 zeolite. Simultaneously, M‐ZSM‐5 materials also contain overgrowth mesoporous MCM‐41 on the rough surfaces of microporous ZSM‐5 zeolite. It is found that the microporosity and mesoporosity of M‐ZSM‐5 depend on conditions of synthesis and alkaline treatment for ZSM‐5 zeolite. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
The modification of activated carbons and the pore structure effect on enrichment of coal‐bed methane
Authors: Zhao Guo‐Feng , Bai Peng , Zhu Hong‐Mei , Yan Ri‐Xiong , Liu Xin‐Mei , Yan Zi‐Feng
Published: July 2008

A series of activated carbons (ACs) were modified with HNO3, H2O2, O2 and N2 heat treatment in order to alter the pore structure and investigate the influence of the pore structure on enriching coal‐bed methane. The pore structure and surface chemical property of all samples were characterized by physical adsorption of nitrogen at 77 K, infrared spectroscopy methods (FT‐IR), temperature‐programmed desorption (TPD) and Boehm titrations. Results showed that oxidizing treatments with HNO3, H2O2 and O2 affected the pore structure significantly and introduced oxygen surface groups that could be removed under N2 heat treatment. All the samples were evaluated in the simple pressure swing adsorption (PSA) apparatus and the evaluation results indicated that the concentration of enriched methane increased with the surface area of AC and the most optimum pore size with the best enrichment performance is in the range 0.758–0.776 nm. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
A compact optimization strategy for combustion in a 125 MW tangentially anthracite‐fired boiler by an artificial neural network
Authors: Sun Dan‐Ping , Fang Qing‐Yan , Wang Hua‐Jian , Zhou Huai‐Chun
Published: July 2008

In the past decade, artificial neural networks (ANNs) have been widely utilized to model, control, and optimize combustion processes in utility boilers. Since many highly correlated factors influence the combustion process in a furnace, it is necessary to select several important parameters to form a more simplified ANN model, which can be easily put into real‐time operation. In this paper, a parameter representing the secondary air assignment mode was quantified by the ratio of the damper opening values between the upper and lower secondary air. This parameter, together with the oxygen concentration in flue gas, the volatile matter and the heating value of coal, constitute the four input parameters of the ANN. Its output is the efficiency of the boiler. The ANN model was trained from 34 samples obtained from experiments on a 125 MW pulverized‐coal‐fired boiler, and the results predicted by the network model agreed well with the experimental results. A compact optimization strategy for combustion was proposed, by which the best combination of the oxygen concentration and the secondary air assignment mode can be determined directly according to the volatile matter and the heating value of coal. For two coals, the combustion in the furnace was obviously improved with the help of the optimization strategy, and its applicability was validated. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
Recovery of precious metals from spent automobile catalytic converters using supercritical carbon dioxide
Authors: Faisal Muhammad , Atsuta Yoichi , Daimon Hiroyuki , Fujie Koichi
Published: July 2008

Recovery of precious metals (platinum, palladium, and rhodium) from a solid matrix sample by supercritical carbon dioxide containing a chelating ligand, a tributyl phosphate (TBP), was studied. The effects of temperature, pressure, and static extraction time on the extraction efficiency were investigated. All experiments were performed using a supercritical fluid extraction system at a temperature range of 40–80 °C and a pressure of up to 30 MPa. Results showed that addition of the chelating ligand was necessary to extract the metals. Experiments with pure supercritical carbon dioxide result in no extraction of the metals. It has been observed that the extraction efficiency of metals was strongly dependent on temperature, pressure, and static extraction time. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
Simultaneous recovery of Ni and Co from scrap mobile phone battery by acid leaching process
Authors: Sakultung S. , Pruksathorn K. , Hunsom M.
Published: July 2008

This research was carried out to recover some valuable metals from the electrodes of the scrap mobile phone batteries by using the leaching process in the laboratory. Two types of scrap mobile phone batteries were used in this study: nickel‐metal hydride (Ni–MH) and lithium‐ion batteries (Li–ion). Both batteries were first crushed and their principal components were analyzed. Subsequently leaching was carried out. For simultaneous recovery of both metals, the preliminary results indicated that H2SO4 provided better leaching than HNO3 under the same conditions. The optimum leaching was at an acid concentration of 2.5 M, leaching temperature of 70 °C, solid–liquid ratio of 15 g/l, and leaching time of 60 min. Under these conditions, approximately 95% of nickel (Ni) and 59% of cobalt (Co) were leached. The presence of a reducing agent such as H2O2 had very little effect on the leaching efficiency of both metals. The leaching process of both the metals was a second‐order reaction of the metal concentration in the solution. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
Optimizing separator pressures in the multistage crude oil production unit
Authors: Bahadori Alireza , Vuthaluru Hari B. , Mokhatab Saeid
Published: July 2008

To achieve good separation between gas and liquid mixture coming out of a crude oil production system and to maximize hydrocarbon liquid recovery, it is necessary to use several separation stages at decreasing pressures and then adapting the pressure set‐points to improve product separation and recovery at minimum cost. The aim of this study is to present an accurate methodology for optimizing separator pressures in the crude oil production unit. The new proposed methodology determines the optimum pressures of separators in different stages of separation and consequently optimizes the operating conditions. Using this new method, the optimum separator pressures for a 5724‐m3/day oil production unit were determined. As a result, the oil recovery was increased by 6 and 5 m3/day during summer and winter seasons, respectively. In this work, the C7 + fraction was also treated as one cut and then breakdown of heavy fraction cuts (C7 + splitting) with respect to the most widely used distribution function (gamma probability function). The results obtained showed that the calculations with C7 + fraction breakdown is more accurate than definition of feed stream a with single C7 + fraction. Copyright © 2008 Curtin University of Technology and John Wiley & Sons, Ltd.
Mutational analysis of SHH and GLI3 in anorectal malformations
Authors: Garcia‐Barceló Maria‐Mercè , Chi‐Hang Lui Vincent , Miao Xiaoping , So Man‐ting , Yuk‐yu Leon Thomas , Yuan Zhen‐wei , Li Long , Liu Lei , Wang Bin , Sun Xiao‐bing , Huang Liu‐ming , Tou Jin‐fa , Sau‐wai Ngan Elly , Cherny Stacey S. , Chan Kin‐wai , Lee Kim‐hung , Wang Weiling , Kak‐yuen Wong Kenneth , Kwong‐hang Tam Paul
Published: July 2008

BACKGROUND:

Anorectal malformations (congenital absence of the anal opening) are among the most common pediatric surgical problems and carry a significant chronic morbidity.

METHODS:

Direct sequencing was used to screen 88 anorectal malformations patients for mutations and polymorphisms in SHH and GLI3. These genes were chosen according to the phenotype presented by mutant mice and their expression patterns.

RESULTS:

We report on 10 GLI3 variants (IVS3+141C>G, T183A, IVS4+124T>C, IVS7+17G>A, IVS8+1 G>C, N503N, P941P, P998L, A1005A, A1039A) and four SHH mutation/variants (IVS1‐49C>T, IVS2+111A>C, L214L, G290D).

CONCLUSIONS:

These variants are not over‐represented in the healthy population and most are predicted to be benign. This study conveys the problematic assessment of the pathogenic role in disease of rare point mutations and variants. Birth Defects Research (Part A) 82:644–648, 2008. © 2008 Wiley‐Liss, Inc.
Optimization and validation of a reporter gene assay for screening of phosphodiesterase inhibitors in a high throughput system
Authors: Nanda Kamna , Chatterjee Mou , Arya Ranjana , Mukherjee Shohini , Saini Kulvinder Singh , Dastidar Sunanda , Ray Abhijit
Published: July 2008

Phosphodiesterases (PDEs) hydrolyze cyclic nucleotides, cyclic adenosine monophosphate (cAMP) and guanosine monophosphate (cGMP) into inactive 5' monophosphates, and exist as 11 families. Inhibitors of PDEs allow the elevation of cAMP and cGMP, which leads to a variety of cellular effects including airway smooth muscle relaxation and inhibition of cellular inflammation or of immune responses. PDE4 inhibitors specifically prevent the hydrolysis of cAMP. We have validated the manually developed reporter gene assay in a high‐throughput screening format that allows for fast and cost‐effective identification of potential inhibitors of PDE4 isozymes. The assay is sensitive and robust, with a Z' value of >0.5. The assay is also amenable to 384‐well format.
RNA‐driven cyclin‐dependent kinase regulation: When CDK9/cyclin T subunits of P‐TEFb meet their ribonucleoprotein partners
Authors: Michels Annemieke A. , Bensaude Olivier
Published: July 2008

The positive transcription elongation factor (P‐TEFb) consists of CDK9, a cyclin‐dependent kinase and its cyclin T partner. It is required for transcription of most class II genes. Its activity is regulated by non‐coding RNAs. The 7SK cellular RNA turns the HEXIM cellular protein into a P‐TEFb inhibitor that binds its cyclin T subunit. Thus, P‐TEFb activity responds to variations in global cellular transcriptional activity and to physiological conditions linked to cell differentiation, proliferation or cardiac hypertrophy. In contrast, the Tat activation region RNA plays an activating role. This feature at the 5' end of the human immunodeficiency (HIV) viral transcript associates with the viral protein Tat that in turn binds cyclin T1 and recruits active P‐TEFb to the HIV promoter. This results in enhanced P‐TEFb activity, which is critical for an efficient production of viral transcripts. Although discovered recently, the regulation of P‐TEFb becomes a paradigm for non‐coding RNAs that regulate transcription factors. It is also a unique example of RNA‐driven regulation of a cyclindependent kinase.
Structure‐activity relationship and metabolic stability studies of backbone cyclization and N‐methylation of melanocortin peptides
Authors: Linde Yaniv , Ovadia Oded , Safrai Eli , Xiang Zhimin , Portillo Federico P. , Shalev Deborah E. , Haskell‐Luevano Carrie , Hoffman Amnon , Gilon Chaim
Published: July 2008

Backbone cyclization (BC) and N‐methylation have been shown to enhance the activity and/or selectivity of biologically active peptides and improve metabolic stability and intestinal permeability. In this study, we describe the synthesis, structure‐activity relationship (SAR) and intestinal metabolic stability of a backbone cyclic peptide library, BL3020, based on the linear α‐Melanocyte stimulating hormone analog Phe‐D‐Phe‐Arg‐Trp‐Gly. The drug lead, BL3020‐1, selected from the BL3020 library (compound 1) has been shown to inhibit weight gain in mice following oral administration. Another member of the BL3020 library, BL3020‐17, showed improved biological activity towards the mMC4R, in comparison to BL3020‐1, although neither were selective for MC4R or MC5R. N‐methylation, which restrains conformational freedom while increasing metabolic stability beyond that which is imparted by BC, was used to find analogs with increased selectivity. N‐methylated backbone cyclic libraries were synthesized based on the BL3020 library. SAR studies showed that all the N‐methylated backbone cyclic peptides demonstrated reduced biological activity and selectivity for all the analyzed receptors. N‐methylation of active backbone cyclic peptides destabilized the active conformation or stabilized an inactive conformation, rendering the peptides biologically inactive. N‐methylation of backbone cyclic peptides maintained stability to degradation by intestinal enzymes. © 2008 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 90: 671–682, 2008.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Development of a simultaneous liquid–liquid extraction and chiral derivatization method for stereospecific GC‐MS analysis of amphetamine‐type stimulants in human urine using fractional factorial design
Authors: Aasim W. R. Wan , Gan S. H. , Tan S. C.
Published: July 2008

A stereospecific gas chromatography–mass spectrometry analysis method for amphetamine‐type stimulants in human urine was recently developed. For maximum efficiency, liquid–liquid extraction and chiral derivatization of the analytes using (R)‐(−)‐α‐methoxy‐α‐(trifluoromethyl)phenylacetyl chloride were performed simultaneously. The effects of (1) use of saturated sodium chloride in 2.0msodium hydroxide, (2) extraction solvent volume, (3) percentage of triethylamine, (4) derivatization reagent volume, (5) sample mixing time, (6) incubation temperature and (7) incubation time on method sensitivity and variability were assessed using a two‐level, eight‐run Plackett–Burman design followed by a fold‐over design. The use of saturated sodium chloride solution and the derivatization reagent volume were significant factors (ANOVA,p< 0.01). The saturated sodium chloride solution decreased sensitivity whereas an increased volume of derivatization reagent increased sensitivity. Calibration curves for all analytes were linear between 5 and 500 µg/L, with correlation coefficients of >0.99. Detection limits were ≤2.3 µg/L and quantitation limits ≤7.7 µg/L. Reproducibility was good, with relative standard deviation values at <20%. Recovery exceeded 100% for most analytes. The experimental design enabled easy and rapid identification of significant factors using a minimal number of samples. This method has good potential for studies requiring rapid and sensitive stereospecific quantification of amphetamine‐type stimulants. Copyright © 2008 John Wiley & Sons, Ltd.
Influence of δ‐Functional Groups on the Enantiorecognition of Secondary Alcohols by Candida antarctica Lipase B
Authors: Nyhlén Jonas , Martín‐Matute Belén , Sandström Anders G. , Bocola Marco , Bäckvall Jan‐E.
Published: July 2008

The selectivity of acetylation of δ‐functionalized secondary alcohols catalyzed by Candida antarctica lipase B has been examined by molecular dynamics. The results from the simulation show that a δ‐alcohol functionality forms a hydrogen bond with the carbonyl group of Thr 40. This interaction stabilizes the tetrahedral intermediate and thus leads to selective acetylation of the R enantiomer. A stabilizing interaction of the δ‐(R)‐acetoxy group with the peptide NH of alanine 282 was also observed. No stabilizing interaction could be found for the δ‐keto functionality, and it is proposed that this is the reason for the experimentally observed decrease in enantioselectivity. From these results, it was hypothesized that the enantioselectivity could be restored by mutating the alanine in position 281 for serine. The mutation was made experimentally, and the results show that the E value increased from 9 to 120.