bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of hydrodynamic parameters of a fluidized‐bed reactor with immobilized yeast
Authors: Fouad Sarrouh Boutros , Converti Attilio , da Silva Silvio Silvério 
Published: February 2008

AbstractThe fluidized bed reactor has successfully been used to perform biotechnological processes addressed to the production of high added value. The present work evaluates hydrodynamic parameters of a bench‐scale fluidized bed reactor with cells of the yeast Candida guilliermondii immobilized either in calcium alginate beads or in polyvinyl alcohol (PVA). The effects of the following variables on cell immobilization were evaluated at 30 °C and feeding a synthetic medium containing 50 g L−1 xylose: total particle density (cells plus support), terminal velocity, particle drag force, minimum fluidization velocity and bed porosity. According to the results obtained, the reactor was shown to operate like a fixed‐bed bioreactor at ξ < 0.5 and a fluidized bed bioreactor at ξ > 0.5. The maximum flow rate needed to obtain maximum bed fluidization in the reactor was equal to the terminal velocity of the immobilized cell particles. Particles of cells immobilized within these supports showed values of drag coefficient lower than those reported for other high‐density supports. The evaluation of these hydrodynamic characteristics lead to an adequate bed fluidization inside the reactor, thus improving oxygen transference and availability in the fermentation medium, making the process more viable for future scale‐up. Copyright © 2008 Society of Chemical Industry
Solid–liquid mass transfer characteristics of an unbaffled agitated vessel with an unsteadily forward–reverse rotating impeller
Authors: Tezura Shuichi , Kimura Akihiro , Yoshida Masanori , Yamagiwa Kazuaki , Ohkawa Akira 
Published: February 2008

AbstractTo develop an enhanced form of solid‐liquid apparatus, an unbaffled agitated vessel has been constructed, fitted with an agitation system using an impeller whose rotation alternates unsteadily in direction, i.e. a forward‐reverse rotating impeller. In this vessel, solid‐liquid mass transfer was studied using a disc turbine impeller with six flat blades. The effect of impeller rotation rate as an operating variable on the mass transfer coefficient was evaluated experimentally using various geometrical conditions of the apparatus, such as impeller diameter and height, in relation to the impeller power consumption. Mixing of gas above the free surface into the bulk liquid, i.e. surface aeration, which accompanied the solid‐liquid agitation, was also investigated. Comparison of the mass transfer characteristics between this type of vessel and a baffled vessel with a unidirectional rotating impeller underscored the sufficient solid‐liquid contact for prevention of gas mixing in the forward‐reverse rotation mode of the impeller. Copyright © 2008 Society of Chemical Industry
Efficient enzymatic regioselective benzoylation of 5‐fluorouridine catalysed by Novozym 435
Authors: Wu Jian , Zong Min‐Hua , Wu Hong , Lou Wen‐Yong 
Published: February 2008

AbstractBACKGROUND: This work focuses on developing a mild, efficient and regioselective enzymatic procedure to synthesise 5′‐O‐benzoyl‐5‐fluorouridine, a more powerful antitumour drug than 5‐fluorouridine itself, and examining the influences of several key variables on the reaction.RESULTS: The enzymatic regioselective benzoylation of 5‐fluorouridine can be successfully conducted with Novozym 435. The end‐product was confirmed to be 5′‐O‐benzoyl‐5‐fluorouridine by 13C nuclear magnetic resonance analysis. A co‐solvent mixture of hexane and tetrahydrofuran (THF) (50:50 v/v) was found to be the best reaction medium. The optimal initial water activity, molar ratio of vinyl benzoate to 5‐fluorouridine and reaction temperature were 0.07, 25:1 and 70 °C respectively. Under the optimised conditions the initial reaction rate, substrate conversion and regioselectivity were found to be 32.8 mmol L−1 h−1, 98.9% and > 99% respectively. In addition, Novozym 435 still maintained 88.2% of its original activity even after being reused for ten batches at 70 °C, indicating excellent thermal and operational stability of the enzyme in the co‐solvent mixture of hexane and THF.CONCLUSION: The results clearly show that the Novozym 435‐catalysed regioselective benzoylation of 5‐fluorouridine is a novel and facile route for efficient preparation of 5′‐O‐benzoyl‐5‐fluorouridine with potential antitumour activity. Copyright © 2008 Society of Chemical Industry
Influence of light quality and intensity in the cultivation of Spirulina platensis from Toliara (Madagascar) in a closed system
Authors: Ravelonandro Pierre H , Ratianarivo Dominique H , Joannis‐Cassan Claire , Isambert Arsène , Raherimandimby Marson 
Published: February 2008

AbstractBACKROUND: Spirulina platensis (Toliara, Madagascar) provides a food supplement which can fight against malnutrition and food insufficiency in Madagascar. In this country, the current production from three open basins is not sufficient to cover needs, and presents drawbacks such as low productivity and possible contamination. Thus cultivation of S. platensis in a closed photobioreactor opens the possibility of extending this microalga production. In this study, the influence of colour and intensity of the light on S. platensis growth and protein content was investigated in a bubble column.RESULTS: Growth kinetics were obtained for four colours (green, white, red and blue) and four intensities (400, 800, 1000 and 1200 lux) of light. The influence of light colour on Spirulina growth was discussed. The highest productivity (183.6 mg L−1 d−1) and concentration (2643 mg L−1) were obtained for green light at 1200 lux. The protein content was 58%.CONCLUSION: Using green light allows improvement of S. platensis growth. Performance obtained with the closed system was higher than that reported in the literature. Copyright © 2008 Society of Chemical Industry
Lipase‐catalyzed ethanolysis of soybean oil in a solvent‐free system using central composite design and response surface methodology
Authors: Rodrigues Rafael Costa , Volpato Giandra , Ayub Marco Antônio Záchia , Wada Keiko 
Published: February 2008

AbstractBACKGROUND: In this work we describe the synthesis of ethyl esters, commonly known as biodiesel, using refined soybean oil and ethanol in a solvent‐free system catalyzed by lipase from Thermomyces lanuginosus. Central composite design and response surface methodology (RSM) were employed to optimize the biodiesel synthesis parameters, which were: reaction time, temperature, substrate molar ratio, enzyme content, and added water, measured as percentage of yield conversion.RESULTS: The optimal conditions obtained were: temperature, 31.5 °C; reaction time, 7 h; substrate molar ratio, 7.5:1 ethanol:soybean oil; enzyme content, 15% (g enzyme g−1 oil); added water, 4% (g water g−1 oil). The experimental yield conversion obtained under these conditions was 96%, which is very close to the maximum predicted value of 94.4%. The reaction time‐course at the optimal values indicated that 5 h was necessary to obtain high yield conversions.CONCLUSION: A high yield conversion was obtained under the optimized conditions, with relative low enzyme content and short time. Comparison of predicted and experimental values showed good correspondence, implying that the empirical model derived from RSM can be used to adequately describe the relationship between the reaction parameters and the response (yield conversion) in lipase‐catalyzed biodiesel synthesis. Copyright © 2008 Society of Chemical Industry
Insulated hsp70B′ promoter: stringent heat‐inducible activity in replication‐deficient, but not replication‐competent adenoviruses
Authors: Rohmer Stanimira , Mainka Astrid , Knippertz Ilka , Hesse Andrea , Nettelbeck Dirk M. 
Published: February 2008

AbstractBackgroundKey to the realization of gene therapy is the development of efficient and targeted gene transfer vectors. Therapeutic gene transfer by replication‐deficient or more recently by conditionally replication‐competent/oncolytic adenoviruses has shown much promise. For specific applications, however, it will be advantageous to provide vectors that allow for external control of gene expression. The efficient cellular heat shock system in combination with available technology for focused and controlled hyperthermia suggests heat‐regulated transcription control as a promising tool for this purpose.Methods and resultsWe investigated the feasibility of a short fragment of the human hsp70B′ promoter, with and without upstream insulator elements, for the regulation of transgene expression by replication‐deficient or oncolytic adenoviruses. Two novel adenoviral vectors with an insulated hsp70B′ promoter were developed and showed stringent heat‐inducible gene expression with induction ratios up to 8000‐fold. In contrast, regulation of gene expression from the hsp70B′ promoter without insulation was suboptimal. In replication‐competent/oncolytic adenoviruses regulation of the hsp70B′ promoter was lost specifically during late replication in permissive cells and could not be restored by the insulators.ConclusionsWe developed novel adenovirus gene transfer vectors that feature improved and stringent regulation of transgene expression from the hsp70B′ promoter using promoter insulation. These vectors have potential for gene therapy applications that benefit from external modulation of therapeutic gene expression or for combination therapy with hyperthermia. Furthermore, our study reveals that vector replication can deregulate inserted cellular promoters, an observation which is of relevance for the development of replication‐competent/oncolytic gene transfer vectors. Copyright © 2008 John Wiley & Sons, Ltd.
Silica‐overcoated substrates for detection of proteins by surface‐enhanced Raman spectroscopy
Authors: Scholes F. H. , Bendavid A. , Glenn F. L. , Critchley M. , Davis T. J. , Sexton B. A. 
Published: February 2008

AbstractAg film over nanosphere (AgFON) substrates for surface‐enhanced Raman spectroscopy (SERS) are shown to be ineffective for the detection of proteins in phosphate buffer solution (PBS) because of the decomposition of the substrate resulting in a total loss of SERS activity. However, modification of these substrates with SiO2 overlayers overcomes this problem. The SiO2 overlayers are produced by filtered arc deposition (FAD) and are characterised by atomic force microscopy (AFM). Their porosity is examined using Raman spectroscopy and the detection of cytochrome c and bovine serum albumin in PBS is successfully demonstrated. These findings show promise for the detection of proteins in biologically relevant conditions using Ag‐based SERS substrates. Copyright © 2008 John Wiley & Sons, Ltd.
Application of micro‐ and nano‐HPLC to the determination and characterization of bioactive and biomarker peptides
Authors: Saz José María , Marina María Luisa 
Published: February 2008

AbstractThis article reviews the works published since 2001 (included) on the micro/nano‐HPLC analysis of bioactive and biomarker peptides. The main achievements related to the improvement of the detection sensitivity, quantitation repeatability and reproducibility, and separation selectivity are highlighted. A wide attention is paid to the application of micro/nano‐HPLC to the analysis of bioactive peptides in biological matrices. The uses of micro/nano‐HPLC in peptidomics to discover new endogenous bioactive peptides and to develop quantitation procedures to compare the levels of peptides of interest in two different biological samples are also considered. Finally, the application of micro/nano‐HPLC to the analysis of biomarker peptides for various diseases is also included in this review.
Photocatalytic decomposition of gaseous acetone using TiO2and Pt/TiO2catalysts
Authors: Ku Young , Tseng Kun‐Yu , Ma Chih‐Ming 
Published: February 2008

AbstractMetallic platinum was photodeposited on TiO2particles, and morphological characteristics of the Pt/TiO2catalyst were determined. The dispersion of metallic platinum was uniform and did not alter the morphology of the TiO2particles. However, absorbance of the Pt/TiO2catalyst for light with wavelength more than 400 nm was significantly improved by the addition of metallic platinum. Gaseous acetone was decomposed in an annular photoreactor coated with TiO2or Pt/TiO2catalysts using a UV or a fluorescent lamp as light source. The decomposition of acetone with the application of a UV lamp was obviously enhanced for experiments conducted with Pt/TiO2catalyst. Decomposition of acetone was promoted considerably with increasing oxygen concentration for experiments conducted with oxygen less than 50,000 ppmv, yet the decomposition of acetone was kept relatively constant for experiments conducted with oxygen above 50,000 ppmv. On the basis of the mass balance for carbon species, the amount of organic intermediates formed for experiments conducted under various conditions was found to be minimal. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 209–216, 2008
A simulation of the mass‐transfer effects on the kinetics of solid–gas reactions
Authors: Ortega A. 
Published: February 2008

AbstractA theoretical analysis of the influence of mass‐transfer effect on the kinetic of solid–gas reactions has been carried out by assuming that the partial pressures of the gases generated in the reaction are proportional to the reaction rate. The influence of mass‐transfer phenomena on the apparent activation energy, calculated by the isoconversional methods of Friedman, and on the reaction model is discussed. In the present study, simulated nonisotherm, isotherm, and controlled rate thermal analysis (CRTA) data have been used. Master plots based on the differential forms of the kinetic equations describing solid‐state reactions have been employed by using the concept of the generalized time (θ), introduced by Ozawa; this permits the application of these master plots to the kinetic analysis of reactions whatever the type of temperature program used for recording the experimental data. It has been shown that when the simulated mass‐transfer effect is present the variable effective activation energy E remains nearly constant while the reaction model approaches zero order. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 217–222, 2008
Energy forms on conformal C1‐diffeomorphic images of the Sierpinski gasket
Authors: Freiberg Uta Renata , Lancia Maria Rosaria 
Published: February 2008

AbstractThe energy form on a conformal C1‐diffeomorphic image G of the Sierpinski gasket K is constructed by integrating the Lagrangian LG on G, which is given in terms of the pullback of the Lagrangian LK on K and of the differential of the diffeomorphism. The extension of this approach to the class of nested fractals is outlined. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Second‐order properties of the point process of nodes in a stationary Voronoi tessellation
Authors: Heinrich Lothar , Muche Lutz 
Published: February 2008

AbstractIn this paper we derive representation formulae for the second factorial moment measure of the point process of nodes and the second moment of the number of vertices of the typical cell associated with a stationary normal Voronoi tessellation in ℝd . In case the Voronoi tessellation is generated by a stationary Poisson process with intensity λ > 0 the corresponding pair correlation function gV,λ (r) can be expressed by a weighted sum of d +2 (numerically tractable) multiple parameter integrals. The asymptotic variance of the number of nodes in an increasing cubic domain as well as the second moment of the number of vertices of the typical Poisson Voronoi cell are calculated exactly by means of these parameter integrals. The existence of a (d − 1)st‐order pole of gV,λ (r) at r = 0 is proved and the exact value of limr →0 rd –1 gV,λ (r) is determined. In the particular cases d = 2 and d = 3 the graph of gV,1(r) including its local extreme points, the points of level 1 of gV, 1(r) and other characteristics are computed by numerical integration. Furthermore, an asymptotically exact confidence interval for the intensity of nodes is obtained. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Best simultaneous approximation in L∞(μ, X)
Authors: Pakhrou Tijani 
Published: February 2008

AbstractLet Y be a reflexive subspace of the Banach space X, let (Ω, Σ, μ) be a finite measure space, and let L∞(μ, X) be the Banach space of all essentially bounded μ ‐Bochner integrable functions on Ω with values in X, endowed with its usual norm. Let us suppose that Σ0 is a sub‐σ ‐algebra of Σ, and let μ0 be the restriction of μ to Σ0. Given a natural number n, let N be a monotonous norm in ℝn . We prove that L∞(μ, Y) is N ‐simultaneously proximinal in L∞(μ,X), and that if X is reflexive then L∞(μ0, X) is N ‐simultaneously proximinal in L∞(μ, X) in the sense of Fathi, Hussein, and Khalil [3]. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Compact operators which factor through subspaces of lp
Authors: Prasad Sinha Deba , Kumar Karn Anil 
Published: February 2008

AbstractLet 1 ≤ p ≤ ∞. A subset K of a Banach space X is said to be relatively p ‐compact if there is an 〈xn 〉 ∈ ls p (X) such that for every k ∈ K there is an 〈αn 〉 ∈ lp ′ such that k = σ∞n=1 αn xn . A linear operator T: X → Y is said to be p ‐compact if T (Ball (X)) is relatively p ‐compact in Y. The set of all p ‐compact operators Kp (X, Y) from X to Y is a Banach space with a suitable factorization norm κp and (Kp , κp ) is a Banach operator ideal. In this paper we investigate the dual operator ideal (Kd p , κd p ). It is shown that κd p (T) = πp (T) for all T ∈ B (X, Y) if either X or Y is finite‐dimensional. As a consequence it is proved that the adjoint ideal of Kd p is Ip ′, the ideal of p ′‐integral operators. Further, a composition/decomposition theorem Kd p = Πp K is proved which also yields that (Πmin p )inj = Kd p . Finally, we discuss the density of finite rank operators in Kd p and give some examples for different values of p in this respect. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Double structures on rational space curves
Authors: Eivind Vatne Jon 
Published: February 2008

AbstractThere are very many non‐reduced schemes. In this paper, we consider two examples to back this statement: we give lists of double scheme structures on a twisted cubic, and we construct rank two bundles on projective 3‐space with prescribed Chern classes, from double structures on smooth rational curves. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Behavior of the constant in Korenblum's maximum principle
Authors: Wang Chunije 
Published: February 2008

AbstractLet Ap (𝔻) (p ≥ 1) be the Bergman space over the open unit disk 𝔻 in the complex plane. Korenblum's maximum principle states that there is an absolute constant c ∈ (0, 1) (may depend on p), such that whenever |f (z)| ≤ |g (z)| (f, g ∈ Ap (𝔻)) in the annulus c < |z | < 1, then ∥f ≤ ∥g ∥. For p ≥ 1, let cp be the largest value of c for which Korenblum's maximum principle holds. In this note we prove that cp → 1 as p → ∞. Thus we give a positive answer of a question of Hinkkanen. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A constitutive model for unsaturated soil interfaces
Authors: Hamid Tariq B. , Miller Gerald A. 
Published: February 2008

AbstractA constitutive model based on the disturbed state concept is presented to describe the behavior of interfaces in unsaturated soil. The model is an extension of an existing model developed for a sand–steel interface. As opposed to the original model, the modified model incorporates two independent stress variables, which are the net normal stress and matric suction. The saturated and dry state of the interface can be modeled as a special case using the constitutive model presented in this paper. The modified model is capable of capturing the main features of unsaturated interfaces observed during laboratory testing, including increasing shear strength and strain softening with increasing suction and net normal stress and increasing dilatancy with increasing suction. Laboratory tests were carried out on unsaturated interfaces in a modified direct shear test apparatus. The observed behavior of interfaces between unsaturated soil and steel plates (rough and smooth) is presented in comparison with model predictions. Copyright © 2008 John Wiley & Sons, Ltd.
Two‐point constitutive equations and integration algorithms for isotropic‐hardening rate‐independent elastoplastic materials in large deformation
Authors: Wang Zhi‐Qiao , Dui Guan‐Suo 
Published: February 2008

AbstractThis paper presents alternative forms of hyperelastic–plastic constitutive equations and their integration algorithms for isotropic‐hardening materials at large strain, which are established in two‐point tensor field, namely between the first Piola–Kirchhoff stress tensor and deformation gradient. The eigenvalue problems for symmetric and non‐symmetric tensors are applied to kinematics of multiplicative plasticity, which imply the transformation relationships of eigenvectors in current, intermediate and initial configurations. Based on the principle of plastic maximum dissipation, the two‐point hyperelastic stress–strain relationships and the evolution equations are achieved, in which it is considered that the plastic spin vanishes for isotropic plasticity. On the computational side, the exponential algorithm is used to integrate the plastic evolution equation. The return‐mapping procedure in principal axes, with respect to logarithmic elastic strain, possesses the same structure as infinitesimal deformation theory. Then, the theory of derivatives of non‐symmetric tensor functions is applied to derive the two‐point closed‐form consistent tangent modulus, which is useful for Newton's iterative solution of boundary value problem. Finally, the numerical simulation illustrates the application of the proposed formulations. Copyright © 2008 John Wiley & Sons, Ltd.
Increased uptake of non‐pathogenic E. coli via the follicle‐associated epithelium in longstanding ileal Crohn's disease
Authors: Keita ÅV , Salim SY , Jiang T , Yang P‐C , Franzén L , Söderkvist P , Magnusson K‐E , Söderholm JD 
Published: February 2008

AbstractIn Crohn's disease (CD), inflammation is driven by luminal commensal micro‐organisms; however, mechanisms of early phases of inflammation need further clarification. The earliest observable lesions of recurrent CD are microscopic erosions at the specialized follicle‐associated epithelium (FAE), which lines the Peyer's patches. Therefore, our aim was to investigate the mucosal barrier to non‐pathogenic bacteria in FAE of CD. The FAE of macroscopically normal ileum from patients with longstanding CD, ulcerative colitis, and controls was studied in Ussing chambers regarding electrophysiology and permeability to 51Cr‐EDTA, horseradish peroxidase, and non‐pathogenic E. coli strains. Transepithelial passage routes and uptake into dendritic cells were studied by confocal and electron microscopy. FAE of CD showed increased numbers of adherent bacteria, after E. coli exposure in Ussing chambers, as well as spontaneously in non‐exposed archival surgical tissues. Further, we found increased uptake of fluorescent E. coli K‐12 and HB101 across FAE of CD, but not in ulcerative colitis. Microscopy demonstrated intercellular and transcellular uptake of E. coli in CD, but only transcellular in controls. FAE exposed to E. coli demonstrated changes in conductance and 51Cr‐EDTA permeability, suggesting that bacteria affected the paracellular pathway in CD mucosa. Following bacterial uptake, CD mucosa also demonstrated an increased percentage of E. coli co‐localizing with dendritic cells, and augmented tissue release of TNF‐α. Our data present novel insights into the pathophysiology of CD by demonstrating a previously unrecognized defect of FAE barrier to bacteria in ileal CD, leading to increased load of commensal bacteria to the inductive sites of mucosal immunity. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.