bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cell density effect in the baculovirus‐insect cells system: A quantitative analysis of energetic metabolism
Authors: Bernal Vicente , Carinhas Nuno , Yokomizo Adriana Y. , Carrondo Manuel J.T. , Alves Paula M. 
Published: April 2009

AbstractThe cell density effect (i.e., the drop in the specific productivity in the baculovirus‐insect cells expression system when cells are infected at high cell densities) has been extensively described in the literature. In this article, a model for the central metabolism of serum‐free suspension cultures of Spodoptera frugiperda Sf9 cells is proposed and used to investigate the metabolic basis for this phenomenon. The main metabolic pathways (glycolysis, pentose phosphate pathway, tricarboxylic acids cycle, glutaminolysis, and amino acids metabolism), cellular growth and energetics were considered. The analysis of the stoichiometric model allowed further understanding of the interplay of the consumption of carbon and nitrogen sources in insect cells. Moreover, metabolic flux analysis revealed that Sf9 cells undergo a progressive inhibition of central metabolism when grown to high cell densities, for which the incorporation of amino acids carbon backbones into the TCA cycle (mainly glutamine) and the down‐regulation of glycolysis are partially responsible. Following infection by baculovirus and cellular division arrest, central energy metabolism depended on the infection strategy chosen (cell concentration at the moment of infection and multiplicity of infection), inhibition being observed at high cell densities. Interestingly, the energetic status of the culture correlated with the decrease in cellular production of baculovirus, meaning that there is room for process optimization through the application of metabolic engineering techniques. Biotechnol. Bioeng. 2009; 104: 162–180 © 2009 Wiley Periodicals, Inc.
Characterization of a gastrointestinal tract microscale cell culture analog used to predict drug toxicity
Authors: Mahler Gretchen J. , Esch Mandy B. , Glahn Raymond P. , Shuler Michael L. 
Published: April 2009

AbstractThe lining of the gastrointestinal (GI) tract is the largest surface exposed to the external environment in the human body. One of the main functions of the small intestine is absorption, and intestinal absorption is a route used by essential nutrients, chemicals, and pharmaceuticals to enter the systemic circulation. Understanding the effects of digestion on a drug or chemical, how compounds interact with and are absorbed through the small intestinal epithelium, and how these compounds affect the rest of the body is critical for toxicological evaluation. Our goal is to create physiologically realistic in vitro models of the human GI tract that provide rapid, inexpensive, and accurate predictions of the body's response to orally delivered drugs and chemicals. Our group has developed an in vitro microscale cell culture analog (µCCA) of the GI tract that includes digestion, a mucus layer, and physiologically realistic cell populations. The GI tract µCCA, coupled with a multi‐chamber silicon µCCA representing the systemic circulation, is described and challenged with acetaminophen. Proof of concept experiments showed that acetaminophen passes through and is metabolized by the in vitro intestinal epithelium and is further metabolized by liver cells, resulting in liver cell toxicity in a dose‐dependent manner. The µCCA response is also consistent with in vivo measurements in mice. The system should be broadly useful for studies on orally delivered drugs or ingestion of chemicals with potential toxicity. Biotechnol. Bioeng. 2009; 104: 193–205 © 2009 Wiley Periodicals, Inc.
Modeling and simulation of liquid–solid circulating fluidized bed ion exchange system for continuous protein recovery
Authors: Mazumder Jahirul , Zhu Jingxu , Bassi Amarjeet S. , Ray Ajay K. 
Published: April 2009

AbstractLiquid–solid circulating fluidized bed (LSCFB) is an integrated two‐column (downcomer and riser) system which can accommodate two separate processes (adsorption and desorption) in the same unit with continuous circulation of the solid particles between the two columns. In this study, a mathematical model based on the assumption of homogeneous fluidization was developed considering hydrodynamics, adsorption‐desorption kinetics and liquid–solid mass transfer. The simulation results showed good agreement with the available experimental results for continuous protein recovery. A parametric sensitivity study was performed to better understand the influence of different operating parameters on the BSA adsorption and desorption capacity of the system. The model developed can easily be extended to other applications of LSCFB. Biotechnol. Bioeng. 2009; 104: 111–126 © 2009 Wiley Periodicals, Inc.
Step change in the efficiency of centrifugation through cell engineering: co‐expression of Staphylococcal nuclease to reduce the viscosity of the bioprocess feedstock
Authors: Balasundaram B. , Nesbeth D. , Ward J.M. , Keshavarz‐Moore E. , Bracewell D.G. 
Published: April 2009

AbstractCell engineering to enable step change improvements in bioprocessing can be directed at targets other than increasing product titer. The physical properties of the process suspension such as viscosity, for example, have a major impact on various downstream processing unit operations. The release of chromosomal DNA during homogenization of Escherichia coli and its influence on viscosity is well‐recognized. In this current article we demonstrate co‐expression of Staphylococcus aureus nuclease in E. coli to reduce viscosity through auto‐hydrolysis of nucleic acids. Viscosity reduction of up to 75% was achieved while the particle size distribution of cell debris was maintained approximately constant (d50 = 0.5–0.6 µm). Critically, resultant step change improvements to the clarification performance under disc‐stack centrifugation conditions are shown. The cell‐engineered nuclease matched or exceeded the viscosity reduction performance seen with the addition of exogenous nuclease removing the expense and validation issues associated with such additions to a bioprocess. The resultant material dramatically altered performance in scale‐down mimics of continuous disc‐stack centrifugation. Laboratory scale data indicated that a fourfold reduction in the settling area of a disc‐stack centrifuge can be expected due to a less viscous process stream achieved through nuclease co‐expression with a recombinant protein. Biotechnol. Bioeng. 2009; 104: 134–142 © 2009 Wiley Periodicals, Inc.
Flow‐dependent entrapment of large bioparticles in porous process media
Authors: Trilisky Egor I. , Lenhoff Abraham M. 
Published: April 2009

AbstractThe need for purification of biomolecules extends to larger bioparticles as well. For example, virus purification is required for production of many vaccines and gene delivery vectors, and understanding virus removal in porous media is also important in downstream processing of therapeutic proteins and in purification of water in soils. A convective entrapment mechanism for retention of large bioparticles is discussed here based on retention of such bioparticles in pore constrictions at high enough flow rates, even under non‐binding conditions. A simple equation to predict whether such entrapment is expected to occur in a given system is derived based on a Péclet number that is proportional to the flow rate and to the cube of the bioparticle diameter. To test the theory, adenovirus was spiked onto chromatographic beds. As expected from the theory, under non‐interacting conditions a progressively larger amount of virus becomes trapped with increasing flow rate. The entrapment is reversible upon flow rate reduction, which, within the proposed model, is based on the possibility of diffusive escape from pore constrictions. This mechanism can be exploited for virus purification or removal, and the theory is also consistent with the anecdotal evidence that monoliths and membranes are more difficult to clean than conventional chromatographic beds, especially at high flow rates. Biotechnol. Bioeng. 2009; 104: 127–133 © 2009 Wiley Periodicals, Inc.
Experimental architecture of a DSP based signal generation for PWM inverter
Authors: Cuma Mehmet Uğraş , Teke Ahmet , Tümay Mehmet , Bayindir K. Çağatay , Özgür M. Salih 
Published: April 2009

AbstractThis article presents the analysis and design of an experimental study on the implementation of digital signal processor (DSP) controlled single‐phase pulse width modulation (PWM) inverter based on Simulink and Real Time Workshop in Matlab. Each stage of PWM signal generation using DSP is comprehensively presented to ease the design and analysis of complicated control algorithms in DSP based solutions. The article also enhances knowledge more about experimental studies in the laboratory. The performance of the DSP based PWM inverter design is analyzed through simulation studies under various switching frequencies and the theoretical considerations are successfully validated with experimental prototype based on TMS320F2812 DSP. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 19: 561–571, 2011
Curve fairing using integral spline operators
Authors: Caliò F. , Miglio E. , Rasella M. 
Published: April 2009

AbstractIn the context of the reverse engineering process one of the main problems is the smoothing (i.e. the elimination of the noise) of curves and surfaces reconstructed starting from a set of scattered points. This process of smoothing is usually called fairing. In this paper we propose an efficient algorithm for planar curve fairing. This algorithm is automatic (no interaction with the user is required) and is composed of two steps: first a global rough fairing is performed on the whole curve and then a local fine fairing is carried out to improve the quality of the final curve. The mathematical tool at the base of the algorithm is an integral spline operator characterized by a shape parameter. This operator is variation‐diminishing. In order to choose the best value for the shape parameter, a suitable functional related to the curvature is minimized. Some test cases are presented in order to show the effectiveness of the proposed algorithm: both academic and a real world test case are considered. Copyright © 2009 John Wiley & Sons, Ltd.
A current‐mode automatic frequency tuning system for filters with current mirrors
Authors: Souliotis George 
Published: April 2009

AbstractA new current‐mode automatic frequency tuning system is proposed in this paper. The system is based on the master–slave technique and is suitable for integrated current‐mode filters based on current mirrors. Automatic control is accomplished by controlling the bias current of the current mirrors employed in the master and slave filters. The proposed scheme has been applied in the leapfrog and wave filters and the corresponding simulation results confirm its validity. Copyright © 2009 John Wiley & Sons, Ltd.
Surface and Chemical Characterization of PolyLA Thin Films Fabricated Using Plasma Polymerization
Authors: Easton Christopher D. , Jacob Mohan V. , Shanks Robert A. , Bowden Bruce F. 
Published: April 2009

AbstractPolymer thin films derived from the essential oil of Lavandula angustifolia (LA) are fabricated using plasma polymerization, and their surface and chemical characteristics investigated. The surface morphology of the polyLA films is examined using an atomic force microscope (AFM). The polymer is found to be uniform and pinhole free, and the average roughness of the films is found to be less than a nanometer and independent of the RF power employed during fabrication. Fourier transform infrared (FTIR) spectroscopy analysis of the polyLA film is performed. Comparison of the FTIR spectra for polyLA film with that of the starting monomer demonstrates that many of the original functional groups are retained during the polymerization process. Bands assigned to CC stretching are lost due to their participation in the polymerization reactions. With increased RF power employed during fabrication, a decrease in intensity of most of the remaining bands in the FTIR spectra for the polyLA films is found. This is attributed to reactions such as dehydration of hydroxyl, cyclization, and aromatization associated with alkenes. In addition, it is found that the duration of exposure to UV irradiation and ion bombardment has an insignificant effect on the chemical structure of the polyLA film. Nuclear magnetic resonance (NMR) spectra of the polymer fabricated at low RF power reveals the presence of aromatics in the chemical structure. Water contact angle measurements demonstrate that the polyLA films range from mildly hydrophilic to mildly hydrophobic, and are stable while in contact with water.
A biologically inspired mobility control framework for energy conservation in sensor networks
Authors: Rao Jayanthi , Biswas Subir 
Published: April 2009

AbstractThis paper presents a paradigm for extending network life by introducing energy‐aware mobility in wireless sensor networks. The concept of controlled mobility for energy saving has been motivated by a natural grouping behavior that is observed in Emperor penguins in the Antarctic region. During the winters, a group of those penguins form a closely huddled group to improve their collective heat insulation. Individual penguins within a group exhibit a local mobility pattern that ensures that each individual spends roughly equal amount of time at the periphery of the group, where heat loss is the maximum. As a result, the total heat loss of the group is thought to be evenly distributed across all the individuals. In this paper, we first draw a parallel between the heat loss of a penguin at the group periphery, and the routing energy burden of sensor nodes near the aggregating base stations in a sensor network. Then we develop a fully distributed and localized mobility control algorithm for collective extension of the network life. Experimental results demonstrate that the proposed controlled mobility paradigm can significantly extend a sensor network's operating life even in situations where the energy cost of physical node movement is modeled as high as up to four orders of magnitude larger than the energy cost for packet transmission. Copyright © 2009 John Wiley & Sons, Ltd.
Gender ratios for reading difficulties
Authors: Hawke Jesse L. , Olson Richard K. , Willcut Erik G. , Wadsworth Sally J. , DeFries John C. 
Published: April 2009

AbstractThe prevalence of reading difficulties is typically higher in males than females in both referred and research‐identified samples, and the ratio of males to females is greater in more affected samples. To explore possible gender differences in reading performance, we analysed data from 1133 twin pairs in which at least one member of each pair had a school history of reading problems and from 684 twin pairs from a comparison sample with no reading difficulties. Although the difference between the average scores of males and females in these two samples was very small, the variance of reading performance was significantly greater for males in both groups. We suggest that a greater variance of reading performance measures in males may account at least in part for their higher prevalence of reading difficulties as well as for the higher gender ratios that are observed in more severely impaired samples. Copyright © 2009 John Wiley & Sons, Ltd.
Multicomponent Reactions of Indole, Ethyl Glyoxylate and Anilines: From Friedel–Crafts to Aza‐Diels–Alder Reactions Catalysed by Scandium Triflate
Authors: Desimoni Giovanni , Faita Giuseppe , Mella Mariella , Toscanini Marco , Boiocchi Massimo 
Published: April 2009

AbstractThe multicomponent reaction (MCR) of indole (1), ethyl glyoxylate (2) and 3,4‐dimethoxy‐ or 3,4‐methylenedioxyanilines (3a,b) give, in analogy to Friedel–Crafts alkylation of indole, expected acetates 4a,b. When the reactions are catalysed by scandium triflate, however, a completely different reaction pathway is followed and two pairs of diastereomeric aza‐Diels–Alder adducts (7a,b and 8a,b) are isolated, which result from the reactions in which the ethyl 2‐(arylimino)acetates (azomethynes of 2 with 3a,b) behave as heterodienes and indole is the dienophile. These products, whose structures were confirmed by X‐ray crystal structure analysis of 7a, are not derived from the scandium‐catalysed rearrangement of 4a,b, because when these latter are treated with Sc(OTf)3, the rearrangement produces acetates 5a,b only. The limits of the aza‐Diels–Alder reaction were investigated by performing the MCR on substituted anilines 3f–k. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Religious identity consolidation and mobilization among Turkish Dutch Muslims
Authors: Verkuyten Maykel , Yildiz Ali Aslan 
Published: April 2009

AbstractThis paper investigates religious identity consolidation in terms of the endorsement of the rights of Dutch Muslims to publicly express their identity, and identity mobilization in terms of the attitude towards normative forms of political organization. Identity consolidation and mobilization were examined as a function of the content of Muslim identity. A distinction was made between an individualized and a communal interpretation of what it means to be a Muslim, in addition to orthodox belief. Personal meaning and personal certainty as two aspects of an individualized interpretation were found to be positively associated to the endorsement of Muslim expressive rights, but not to the attitude towards political organization. Behavioural involvement and Muslim group interdependence were positively associated with identity organization. Orthodoxy was related to both identity consolidation and mobilization. Theoretical implications of these results are discussed. Copyright © 2009 John Wiley & Sons, Ltd.
Short‐term scheduling of a wind generation and hydrogen storage in the electricity market
Authors: Tina G. , Brunetto C. 
Published: April 2009

AbstractIntermittent renewable energy sources (RES) are promising to be the future of electricity generation. In particular wind generation, owing to its stochastic behaviour, has to be carefully managed. Its lack of sufficient predictability decreases the energy value in the current framework of electrical markets, therefore, beyond a certain threshold; this kind of generation into the electrical system represents a problem for the transmission system operator (TSO) during its despatching service. The coupling of wind energy conversion system (WECS) with a storage medium (i.e. hydrogen) could improve the programmability of such generation plants in electrical markets.In this paper, an economical optimization tool has been developed in order to find the short‐term scheduling so as to maximize the economic revenues in the day‐ahead electricity market of a storage plant coupled with a wind farm. This tool needs as input the forecasts of both wind generation power and market prices, obtained with the adoption of pre‐processing input data algorithm based on different methods that involve both statistical and probabilistic approaches. Copyright © 2009 John Wiley & Sons, Ltd.
Dissolved gas analysis of transformers using fuzzy logic approach
Authors: Aghaei J. , Gholami A. , Shayanfar H. A. , Dezhamkhooy A. 
Published: April 2009

AbstractThe power transformer is a major apparatus in a power system, and its correct functioning is vital to system operations. Failure of one power transformer may cause long interruptions in supply, costly repairs and loss revenue. The analysis of oil‐immersed gases as a useful and effective method can prevent main faults through diagnosing internal faults of power transformers and proposing preventive operations. Usually the relation between faults and the reason of their existence in power equipments is complicated. Therefore, fuzzy logic method is proper option in the diagnosis of transformers internal faults. In this paper, three fuzzy methods are used for specifying the internal faults of transformer through the ratio method of oil‐immersed gases. Finally, comparing with commonly used methods, the proposed methods found effective enough. Copyright © 2009 John Wiley & Sons, Ltd.
Forensic evaluation of clothing flammability
Authors: Hirschler M. M. , Zicherman J. B. , Umino Peter Y. 
Published: April 2009

AbstractA set of 17 commercial garments were purchased, categorized based on their fabric composition and fire tested. Three fire exposures were used: (a) a simile of the United States regulatory test for apparel fabrics (16CFR1610), (b) a small vertical candle on a small swatch of fabric and (c) a candle applied to a full garment, placed on a mannequin. Comparisons were made between the results of the various tests and of the various fabrics tested. A general correlation was observed whereby increased fabric areal density [weight/unit fabric area] resulted in improved fire performance. Where outliers to this generalization were observed the improved fire performance was due to the superior inherent fire performance of specific fabric types such as silk. Overall, the quantitative behavior with regard to flame spread rate observed after ignition of cellulosic, thermoplastic and blended fabrics was more heavily dependent on fabric areal density than on their chemical composition. Two key conclusions are that very lightweight fabrics constitute a potential danger and that the United States regulatory value, set at 88.3g/m2 (2.6oz/yd2), represents an essentially arbitrary cut‐off in this regard. Copyright © 2009 John Wiley & Sons, Ltd.
A comparison between the experimental and estimated evaporation paths from emulsions
Authors: Al‐Bawab Abeer , Odeh Fadwa , Bozeya Ayat , Aikens Patricia A. , Friberg Stig E. 
Published: April 2009

AbstractThe evaporation paths in linalool emulsions were experimentally determined using a rotary evaporator coupled to a vacuum pump and calculated from vapour pressures for a series of emulsions with varied oil/water (O/W) ratios. The evaporation paths were comparable to an acceptable degree, suggesting that determination of the evaporation path under reduced pressure, combined with a straightforward calculation using vapour pressures, can be used to estimate the evaporation under different relative humilities. Copyright © 2009 John Wiley & Sons, Ltd.
Antioxidant and antimicrobial activities of essential oil and extracts of fennel (Foeniculum vulgare Mill.) seeds from Pakistan
Authors: Anwar Farooq , Ali Muhammad , Hussain Abdullah Ijaz , Shahid Muhammad 
Published: April 2009

AbstractThe present study was conducted to examine the antioxidant and antimicrobial activities of essential oil, methanol and ethanol extracts of fennel (Foeniculum vulgare Mill.) seeds native to Pakistan. The seed essential oil and extract yields from fennel seeds were found to be 2.81 and 6.21–15.63% w/w, respectively. GC and GC–MS analysis of the fennel essential oil revealed the presence of 23 compounds, with trans‐anethol (69.87%), fenchone (10.23%), estragole (5.45%) and limonene (5.10%) as the major components. The fennel seed extracts contained appreciable levels of total phenolic contents (627.21–967.50 GAE, mg/100 g) and total flavonoid contents (374.88–681.96 CE, mg/100 g). Fennel essential oil and extracts also exhibited good DPPH radical scavenging activity, showing IC50 32.32 and 23.61–26.75 µg/ml, and inhibition of peroxidation 45.05 and 48.80–70.35%, respectively. Of the fennel essential oil and solvent extracts tested, 80% ethanol extract exhibited the maximum antioxidant activity, whereas the essential oil showed appreciable antimicrobial activity against selected strains of bacteria and pathogenic fungi. The results of the present investigation demonstrated significant (p < 0.05) variations in the antioxidant and antimicrobial activities of fennel essential oil and extracts. Copyright © 2009 John Wiley & Sons, Ltd.