bluuebunny/crossref_metadata_2025_split huggingface dataset:
Biomass/adsorbent electrostatic interactions in expanded bed adsorption: A zeta potential study
Authors: Lin Dong‐Qiang , Brixius Peter J. , Hubbuch Jürgen J. , Thömmes Jörg , Kula Maria‐Regina 
Published: May 2003

AbstractExpanded bed adsorption is an integrated technology that allows the introduction of particle‐containing feedstock without the risk of blocking the bed. The biomass particles contained in the feedstock have to be treated as an integral part of the process and potential interactions between suspended biomass and the adsorbent must be excluded during process design. Because the electrostatic forces dominate the interactions between the biomass and adsorbent, the zeta potential has been studied as a tool to characterize biomass/adsorbent electrostatic interactions. The zeta potentials of four types of biomass (yeast intact cells, yeast homogenate, Escherichia coli intact cells, and E. coli homogenate) and two types of ion exchanger were measured systematically at varying process conditions. Using the cell transmission index from biomass pulse‐response experiments as a parameter, the relations between zeta potential and the biomass/adsorbent interaction were evaluated. Combining the influences from zeta potential of adsorbent (ζa), zeta potential of biomass (ζb), and biomass size (d), parameter (−ζaζbd) was found to be an appropriate indicator of the biomass/adsorbent interactions in expanded beds under various liquid‐phase conditions for different types of biomass. The threshold value of parameter (−ζaζbd) can be defined as 120 mV2 μm for cell transmission of >90%, which means that systems with (−ζaζbd) < 120 may have a considerable probability of forming stable expanded beds in a biomass suspension under the particular experimental conditions. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 149–157, 2003.
Method for generation of homogeneous multicellular tumor spheroids applicable to a wide variety of cell types
Authors: Kelm Jens M. , Timmins Nicholas E. , Brown Catherine J. , Fussenegger Martin , Nielsen Lars K. 
Published: May 2003

AbstractMulticellular tumor spheroids (MCTS) are used as organotypic models of normal and solid tumor tissue. Traditional techniques for generating MCTS, such as growth on nonadherent surfaces, in suspension, or on scaffolds, have a number of drawbacks, including the need for manual selection to achieve a homogeneous population and the use of nonphysiological matrix compounds. In this study we describe a mild method for the generation of MCTS, in which individual spheroids form in hanging drops suspended from a microtiter plate. The method has been successfully applied to a broad range of cell lines and shows nearly 100% efficiency (i.e., one spheroid per drop). Using the hepatoma cell line, HepG2, the hanging drop method generated well‐rounded MCTS with a narrow size distribution (coefficient of variation [CV] 10% to 15%, compared with 40% to 60% for growth on nonadherent surfaces). Structural analysis of HepG2 and a mammary gland adenocarcinoma cell line, MCF‐7, composed spheroids, revealed highly organized, three‐dimensional, tissue‐like structures with an extensive extracellular matrix. The hanging drop method represents an attractive alternative for MCTS production, because it is mild, can be applied to a wide variety of cell lines, and can produce spheroids of a homogeneous size without the need for sieving or manual selection. The method has applications for basic studies of physiology and metabolism, tumor biology, toxicology, cellular organization, and the development of bioartificial tissue. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 173–180, 2003.
Cadmium tolerance and antioxidative defenses in hairy roots of the cadmium hyperaccumulator, Thlaspi caerulescens
Authors: Boominathan Rengasamy , Doran Pauline M. 
Published: May 2003

AbstractPlant species capable of hyperaccumulating heavy metals are of considerable interest for phytoremediation and phytomining. This work aims to identify the role of antioxidative metabolism in heavy metal tolerance in the Cd hyperaccumulator, Thlaspi caerulescens. Hairy roots of T. caerulescens and the non‐hyperaccumu‐ lator, Nicotiana tabacum (tobacco), were used to test the effects of high Cd environments. In the absence of Cd, endogenous activities of catalase were two to three orders of magnitude higher in T. caerulescens than in N. tabacum. T. caerulescens roots also contained significantly higher endogenous superoxide dismutase activity and glutathione concentrations. Exposure to 20 ppm (178 μM) Cd prevented growth of N. tabacum roots and increased hydrogen peroxide (H2O2) levels by a factor of five relative to cultures without Cd. In contrast, growth was maintained in T. caerulescens, and H2O2 concentrations were controlled to low, nontoxic levels in association with a strong catalase induction response. Treatment of roots with the glutathione synthesis inhibitor, buthionine sulfoximine (BSO), exacerbated H2O2 accumulation in Cd‐treated N. tabacum, but had a relatively minor effect on H2O2 levels and did not reduce Cd tolerance in T. caerulescens. Lipid peroxidation was increased by Cd treatment in both the hyperaccumulator and non‐hyperaccumulator roots. This work demonstrates that metal‐induced oxidative stress occurs in hyperaccumulator tissues even though growth is unaffected by the presence of heavy metals. It also suggests that superior antioxidative defenses, particularly catalase activity, may play an important role in the hyperaccumulator phenotype of T. caerulescens. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 158–167, 2003.
Separation of α‐lactalbumin and β‐lactoglobulin using membrane ultrafiltration
Authors: Cheang Beelin , Zydney Andrew L. 
Published: May 2003

AbstractThere is considerable commercial interest in the preparation of individual whey proteins as high‐value food additives, nutraceuticals, and therapeutics. This study examined the use of membrane filtration for the separation of α‐lactalbumin and β‐lactoglobulin. Stirred cell filtration experiments were performed using both cellulosic and polyethersulfone membranes to determine the optimal pH, ionic strength, and filtration conditions. Selectivities of greater than 55 could be achieved at pH 5.5 and 50 mM ionic strength using a 30‐kD cellulose membrane. A diafiltration process was then designed for the protein separation. A 16‐diavolume filtration yielded β‐lactoglobulin as the retentate product with a purification factor of 100 and recovery of 90%. The α‐lactalbumin was recovered in the filtrate with a purification factor of more than 10 and nearly 99% yield. Model calculations were in good agreement with the experimental data. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 201–209, 2003.
Constitutive versus thermoinducible expression of heterologous proteins in Escherichia coli based on strong PR,PL promoters from phage lambda
Authors: Menart Viktor , Jevševar Simona , Vilar Mateja , Trobiš Andreja , Pavko Aleksander 
Published: May 2003

AbstractConstitutive and thermoinducible expression plasmids based on strong PR,PL promoters from phage lambda were compared for production of TNF‐alpha and its analogs under various conditions. Much higher accumulation of TNF was obtained in a constitutive system, so the wider applicability of such systems was studied. In constitutive systems, proteolytically susceptible proteins can be produced easily at low cultivation temperatures and the addition of expensive or toxic chemical inducers is not required. On the other hand, toxic proteins cannot be produced and selection pressure must be strictly maintained to ensure segregational stability of plasmids. Accumulation of TNF‐alpha and various analogs at levels up to 25% of total soluble protein was repeatedly achieved, which was 2–3‐fold higher than in a thermoinducible system. The stable behavior of the constitutive system in laboratory fermentors was also confirmed. We propose the constitutive system described here as a general model for many currently used expression systems containing strong but not completely repressed promoters. Such systems may be considered as constitutive ones with reduced promoter strengths, but still exhibiting all the intrinsic properties of constitutive expression systems. Although all modern expression systems are inducible, wider use of a constitutive system is evidently possible. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 181–190, 2003.
Asymmetric synthesis of L‐homophenylalanine by equilibrium‐shift using recombinant aromatic L‐amino acid transaminase
Authors: Cho Byung‐Kwan , Seo Joo‐Hyun , Kang Tae‐Won , Kim Byung‐Gee 
Published: May 2003

AbstractL‐Homophenylalanine (L‐HPA) was asymmetrically synthesized from 2‐oxo‐4‐phenylbutyric acid (2‐OPBA) and L‐aspartate using a recombinant aromatic amino acid transaminase (AroAT). To screen microorganisms having such an L‐specific AroAT with a relaxed substrate inhibition in the asymmetric synthesis of unnatural amino acids, enrichment cultures were performed in a minimal media containing 50 mM L‐HPA as a sole nitrogen source. To reduce the intracellular background synthetic activity by amino acid pools in the cells, a two‐step screening method was used. The putative AroAT (i.e., AroATEs) from the screened Enterobacter sp. BK2K‐1 was cloned, sequenced, and overexpressed in E. coli cells. The activity of the overexpressed AroATEs was 314‐fold higher than that of the wild‐type cell. The substrate specificities of the enzyme and homology search revealed that the cloned transaminase is true AroAT. The AroATEs showed a substrate inhibition by 2‐OPBA from 40 mM in the asymmetric synthesis, which made it difficult to perform batch asymmetric synthesis of L‐HPA at high concentrations of 2‐OPBA. To avoid the substrate inhibition by 2‐OPBA, intermittent addition of the solid‐state substrate was attempted to obtain a high concentration of L‐HPA. By using the cell extract (75 U) obtained from the recombinant E. coli harboring the AroATEs gene, the asymmetric synthesis of L‐HPA at 840 mM of 2‐OPBA resulted in >94% of conversion yield and >99% ee of L‐HPA of optical purity. Due to the low solubility (<2 mM) of L‐HPA in the reaction buffer, synthesized L‐HPA was continuously precipitated in the reaction media, which drives the reaction equilibrium towards the product formation. After full completion of the reaction, L‐HPA of high purity (>99% ee) was easily recovered by simple pH shift of the reaction media. This method can permit very efficient asymmetric synthesis of other unnatural amino acids using a single transaminase reaction. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 226–234, 2003.
Modulation of translation‐initiation in CHO‐K1 cells by rapamycin‐induced heterodimerization of engineered eIF4G fusion proteins
Authors: Schlatter Stefan , Senn Claudia , Fussenegger Martin 
Published: May 2003

AbstractTranslation‐initiation is a predominant checkpoint in mammalian cells which controls protein synthesis and fine‐tunes the flow of information from gene to protein. In eukaryotes, translation‐initiation is typically initiated at a 7‐methyl‐guanylic acid cap posttranscriptionally linked to the 5′ end of mRNAs. Alternative cap‐independent translation‐initiation involves 5′ untranslated regions (UTR) known as internal ribosome entry sites, which adopt a particular secondary structure. Translation‐initiating ribosome assembly at cap or IRES elements is mediated by a multiprotein complex of which the initiation factor 4F (eIF4F) consisting of eIF4A (helicase), eIF4E (cap‐binding protein), and eIF4G is a major constituent. eIF4G is a key target of picornaviral protease 2A, which cleaves this initiation factor into eIF4GΔ and ΔeIF4G to redirect the cellular translation machinery exclusively to its own IRES‐containing transcripts. We have designed a novel translation control system (TCS) for conditional as well as adjustable translation of cap‐ and IRES‐dependent transgene mRNAs in mammalian cells. eIF4GΔ and ΔeIF4G were fused C‐ and N‐terminally to the FK506‐binding protein (FKBP) and the FKBP‐rapamycin‐binding domain (FRB) of the human FKBP‐rapamycin‐associated protein (FRAP), respectively. Rapamycin‐induced heterodimerization of eIF4GΔ‐FKBP and FRB‐ΔeIF4G fusion proteins reconstituted a functional chimeric elongation factor 4G in a dose‐dependent manner. Rigorous quantitative expression analysis of cap‐ and IRES‐dependent SEAP‐ (human placental secreted alkaline phosphatase) and luc‐ (Photinus pyralis luciferase) encoding reporter constructs confirmed adjustable translation control and revealed increased production of desired proteins in response to dimerization‐induced heterologous eIF4G in Chinese hamster ovary (CHO‐K1) cells. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 210–225, 2003.
Fermentation of corn stover to carboxylic acids
Authors: Thanakoses Piyarat , Black Amanda S. , Holtzapple Mark T. 
Published: May 2003

AbstractThis article describes countercurrent fermentation to anaerobically convert corn stover and pig manure to mixed carboxylic acids using a mixed culture of mesophilic microorganisms. Corn stover was pretreated with lime to increase digestibility. The Continuum Particle Distribution Model (CPDM) was used to simulate continuous fermentors based on data collected from batch experiments. This model saves considerable time in determining optimum operating conditions. For 80% corn stover/20% pig manure, the highest total carboxylic acid productivity was 1.81 g/(L of liquid · d) at a concentration of 21.4 g total acid/L. The highest total acid selectivity, yield, and conversion were 0.714 g total acid/g volatile solids (VS) digested, 0.550 g total acid/g VS fed, and 0.770 g VS digested/g VS fed, respectively, at a concentration of 16.0 g total acid/L. CPDM predicted the acid concentration and conversion within 13.4 and 11.6%, respectively. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 191–200, 2003.
Vibrating membrane filtration for recovery and concentration of insect killing nematodes
Authors: Wilson J. A. , Postlethwaite J. , Pearce J. D. , Leach G. , Lye G. J. , Ayazi Shamlou P. 
Published: May 2003

AbstractNew experimental data are reported that demonstrate the use of a novel vibrating membrane filter (VMF) for the combined recovery and concentration of two species of nematodes, S. feltiae and P. hermaphrodita, from mature liquid fermentation cultures. The disk membrane module had a working surface area of 0.2 m2 and was operated at a constant flow rate of 0.2 m3 h−1. The recovery of the viable nematodes from the spent media and nonviable nematodes was assisted by an independently imposed oscillatory motion of the disk assembly, which produced an intense shear field at the membrane surface with calculated mean values on the order of 104 s−1. Adult (nonviable) nematodes in the fermentation culture were preferentially dissolved in a detergent (sodium dodecylsulfate) and successfully separated from the juveniles using the VMF equipment. Permeate fluxes on the order of 15 to 30 L/m2/h were achieved for an operating transmembrane pressure of 800 mbar. Industrial‐scale liquid fermentation for the manufacture of nematodes as biopesticides produces the viable nematode life stages in low‐concentration suspension containing large quantities of spent media and other waste material. The VMF equipment provided a flexible operation for separation, cleaning, and concentration of viable nematodes from the fermentation broths. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 235–240, 2003.
Ex vivo monitoring of protein production in baculovirus‐infected Trichoplusia ni larvae with a GFP‐specific optical probe
Authors: Kramer Shannon F. , Kostov Yordan , Rao Govind , Bentley William E. 
Published: May 2003

AbstractTrichoplusia ni larvae were infected with baculoviruses containing genes for the expression of ultraviolet optimized green fluorescent protein (GFPuv) and several product proteins. A GFP‐specific optical probe was used to both excite the green fluorescent protein (λex = 385 nm), and subsequently monitor fluorescence emission (λem = 514 nm) from outside the infected larvae. The probe's photodetector was connected to a voltmeter, which was used to quantify the amount of GFPuv expressed in infected larvae. Voltage readings were significantly higher for infected vs. uninfected larvae and, by Western analysis, linear with the amount of GFPuv produced. In addition, the probe sensitivity and range were sufficient to delineate infection efficiency and recombinant protein production for model proteins, chloramphenicol acetyltransferase and human interleukin‐2. This work represents a critical step in developing an automated process for the production of recombinant proteins in insect larvae. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 83: 241–247, 2003.
Neural networks teaching using Evenet‐2000
Authors: Gonzalez E. J. , Hamilton A. , Moreno L. , Aguilar R. M. , Marichal R. L. 
Published: May 2003

AbstractIn optimization problems, neural networks have been proved as an efficient method. Because of this, students of Engineering should learn this tool properly in subjects as “Optimal Control” or “Intelligent Control.” In this paper, a planning for neural networks teaching is proposed. As tool, Evenet‐2000, a Java‐based toolkit which allows to design and train neural networks with arbitrary architecture, is used. © 2003 Wiley Periodicals, Inc. Comput Appl Eng Educ 11: 1–5, 2003; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.10033
Digital control systems simulation using spreadsheets
Authors: El‐Hajj Ali , Karaki Sami , Kabalan Karim Y. 
Published: May 2003

AbstractThis study presents a method for simulating digital control systems using spreadsheets. This method consists of simulating as basic blocks: a delay, a first order transfer function, and a second order transfer function. Any transfer function in the z domain can be obtained by connecting a number of these blocks with appropriate coefficients. This simulation allows the determination of the time response of a sampled data system without solving equations. The simulation interface is customized using graphics and toolbars. The method is suitable for educational environments. © 2003 Wiley Periodicals, Inc. Comput Appl Eng Educ 11: 6–12, 2003; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.10034
MATLABbased GUIs for linear controller design via convex optimization
Authors: Khaisongkram Wathanyoo , Banjerdpongchai David 
Published: May 2003

AbstractOwing to the current evolution of computational tools, a complicated parameter optimization problem could be effectively solved by a computer. In this paper, a CAD tool for multi‐objective controller design based on MATLABprogram is developed. In addition, we construct simple GUIs (using GUIDE tools within MATLAB) to provide a visual approach in specifying the constraints. The linear controller design problem can be cast as the convex optimization subjected to time domain and frequency domain constraints. This optimization problem is efficiently solved within a finite dimensional subspace by a practical ellipsoid algorithm. In the design process, we include a model reduction of the resulting controller to speed up the computational efficiency. Finally, a numerical example shows the capability of the program to design multi‐objective controller for a one‐link flexible robot arm. © 2003 Wiley Periodicals, Inc. Comput Appl Eng Educ 11: 13–24, 2003; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.10035
Development of a web‐based mass transfer processes laboratory: System development and implementation
Authors: Li Yusong , LeBoeuf Eugene J. , Basu P. K. , Turner Louis Hampton 
Published: May 2003

AbstractA web‐based environment is utilized as a means to introduce advanced mass transfer processes concepts in environmental engineering and science courses. System development and implementation is presented, including detailed descriptions of the techniques employed to link software written in high‐level computer languages such as C++ and FORTRAN to an internet‐based, user‐friendly graphical user interface for both program input and output. © 2003 Wiley Periodicals, Inc. Comput Appl Eng Educ 11: 25–39, 2003; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.10036
Animated instructional media for stress transformations in a Mechanics of Materials course
Authors: Philpot Timothy A. , Hall Richard H. , Hubing Nancy , Flori Ralph , Oglesby David B. , Vikas Yellamraju 
Published: May 2003

AbstractTwo unique instructional modules—the Plane Stress Transformations Module and the Mohr's Circle for Plane Stress Module—developed for the Mechanics of Materials course are presented. Formative assessment data gathered from Mechanics of Materials students pertaining to these courseware modules are presented and discussed. General conclusions and recommendations are presented. © 2003 Wiley Periodicals, Inc. Comput Appl Eng Educ 11: 40–52, 2003; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.10037
Parental mental health and child protection—making the links through training
Authors: Pearce Jennifer 
Published: May 2003

AbstractThis article refers to the impact on single discipline working on professional understanding of mental disorder, particularly as it relates to child protection. The dilemmas of bringing a multi‐agency group with diverse experiences and knowledge base together into one training event are considered, with suggestions as to how the difficulty might be addressed. Topics of common concern are identified and training techniques and methods described. The benefits and outcomes of joint training across disciplines and agencies is acknowledged in relation to child protection and parental mental disorder Copyright © 2003 John Wiley & Sons, Ltd.
Understanding communication in child protection networks
Authors: Reder Peter , Duncan Sylvia 
Published: May 2003

AbstractReviews of fatal child abuse cases regularly identify communication problems between the professionals. Understanding their origins requires an analysis of the psychology of communication as well as its technology, since it is a complex process in which interpersonal factors impact on the meaning that each person attributes to the messages given and received. The contexts within which the communications occur also colour how the messages are comprehended. Examples in practice from the Victoria Climbié Inquiry Report (Lord Laming, 2003) will be cited. Effective communication between professionals requires a mindset that can be developed through training. Copyright © 2003 John Wiley & Sons, Ltd.