bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of molecular weight of polyvinylpyrrolidone on precipitation kinetics during the formation of asymmetric polyacrylonitrile membrane
Authors: Kang Jong Seok , Lee Young Moo
Published: August 2002

The effects of the molecular weight of polyvinylpyrrolidone (PVP) on the precipitation kinetics during the formation of an asymmetric polyacrylonitrile membrane and the resulting membrane morphology were investigated. The precipitation kinetics of a polyacrylonitrile membrane was explored using the light‐transmission method and optical microscopic observation, with an emphasis on the effective diffusion coefficient of the nonsolvent as a measure of the solvent/nonsolvent exchange rate. The retarded precipitation behaviors were not observed in all dope solutions. Also, the phase‐ separation rate was steeply decreased with the amount of PVP. It was deduced that increase of the viscosity of the polymer solution upon the addition of PVP hindered the intrusion of the nonsolvent, resulting in a decrease of the phase‐separation rate. When the same amount of PVP with a different molecular weight was used, the precipitation rate decreased with increase of the molecular weight of PVP. Therefore, the nonsolvent tolerance, the interaction between PVP and H2O, as well as the viscosity are regarded as important factors influencing the precipitation rate. The effective diffusion coefficient of the nonsolvent is closely related to the nonsolvent tolerance of the polymer solution, resulting from a pseudoternary phase diagram. The use of high molecular weight PVP strongly depressed the formation of macrovoids inside of the membrane and allowed a dense skin layer to form. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 57–68, 2002
Synthesis and characterization of network liquid crystal elastomers and thermosets
Authors: Jia Yinggang , Zhang Baoyan , Zhou Enle , Feng Zhiliu , Zang Baoling
Published: August 2002

A new series of network liquid crystal polymers were synthesized by graft copolymerization of the difunctional mesogenic monomer 4‐allyloxy‐benzoyloxy‐4′‐allyloxybiphenyl (M) upon polymethylhydrosiloxane (PMHS). Monomer M acted not only as a mesogenic unit but also as a crosslinker for the network polymers. The chemical structures of the polymers were confirmed by IR spectroscopy. DSC, TGA, and X‐ray scattering were used to measure their thermal properties and mesogenic properties. The glass transition temperature (Tg) of these network liquid crystal polymers was increased when the monomer was increased, and Td (temperature of 5% weight loss) at first went up and reached a maximum at P1, then went down. The slightly crosslinked polymers (P0, P1) show rubber‐like elasticity, so it was called liquid‐crystal elastomer. Network polymers will lose elasticity property with a highly crosslinked degree, and turn into thermosetting polymers (P4, P5). All polymers exhibited a smectic texture by X‐ray scattering. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 1104–1109, 2002
Impact response of carbon‐epoxy laminates containing buffer‐strip layers
Authors: Kishore  , Khan Bijoysri , Viswanath B.
Published: August 2002

This work looks at the dynamic behavior of laminated carbon‐epoxy (C‐E) composites with inserted interleaf polytetrafluoroethylene (PTFE)‐coated material. Instrumented impact tests performed on the interleaved test samples showed significant differences in the energy absorption characteristics that could be correlated with the failure mode. It was inferred that with the introduction of small amounts of less adherent layers of material at specific locations, the load‐carrying ability decreased while the energy‐absorbing capability was found to improve considerably. These and other experimental observations are discussed in this article. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 752–761, 2002
Kinetic study of olefin polymerization with a supported metallocene catalyst. II. Ethylene/1‐hexene copolymerization in gas phase
Authors: Chakravarti S. , Ray W. Harmon
Published: August 2002

A kinetic study of ethylene/1‐hexene copolymerization is conducted with a supported metallocene catalyst in a gas‐phase reactor. The investigation into the kinetics of ethylene/1‐hexene copolymerization includes the effects of operational parameters such as the reaction temperature, pressure, and comonomer concentration. The large variations in gas‐phase composition using only an initial charge of 1‐hexene are illustrated by experiment. To remedy this, the ability to control the comonomer composition of 1‐hexene online for the entire duration of the reaction is demonstrated. Online perturbation techniques are implemented to determine key kinetic parameters such as the activation energies for propagation and catalyst deactivation. From pressure perturbation results, a reaction rate order close to 1 is obtained for ethylene in the presence of 1‐hexene. Finally, all the parameters obtained from the study are compared to those determined from ethylene–propylene (E–P) copolymerization. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1096–1119, 2001
Phase behavior and morphological studies of polyimide/PVP/solvent/water systems by phase inversion
Authors: Kim Jong Hak , Min Byoung Ryul , Park Hyun Chae , Won Jongok , Kang Yong Soo
Published: August 2002

The solubility gaps for poly(vinyl pyrrolidone) (PVP) in four polyimide solutions (NMP, DMF, GBL, DMSO) were determined by cloud point measurement and correlated with χPI/Solvent and ΔδPVP/Solvent. Membranes prepared with NMP and DMF systems showed a tendency of suppressing fingerlike structure with addition of PVP. On the other hand, membranes prepared with GBL and DMSO systems showed an inclination toward inducing macrovoid formation. These effects of PVP on the membrane morphology were explained by means of miscibility gap, viscosity of the polymer solution, polymer–polymer phase separation, and overall porosity. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 3481–3488, 2001
Carrier‐bound methotrexate. I. Water‐soluble polyaspartamide–methotrexate conjugates with ester links in the polymer–drug spacer
Authors: Meirim M. G. , Neuse E. W. , N'Da D. D.
Published: August 2002

The antifolate‐type anticancer drug methotrexate (MTX) has for many years, in numerous laboratories, been a “workhorse” drug for conjugation with natural and synthetic macromolecular carriers for the purpose of enhancing bioavailability and lowering toxic side effects. In the project here described the polymer–drug conjugation strategy is utilized for the preparation of water‐soluble polyaspartamide–methotrexate conjugates in which the drug is carrier‐anchored through short spacers containing ester groups as biofissionable links. To this end, polyaspartamide carriers 1, poly‐α,β‐D,L‐N‐(2‐hydroxyethyl)aspartamide, and 2, poly‐α,β‐D,L‐N‐[2‐(2‐hydroxyethoxy)ethyl]aspartamide, are treated with MTX in DMF solution in the presence of a carbodiimide coupling agent and 4‐(dimethylamino)pyridine catalyst. The molar MTX/OH feed ratios, 0.28 and lower, are chosen in these coupling reactions so as to provide conjugates featuring drug‐loading levels in the approximate range of 3–16 mol % MTX, roughly corresponding to 6–28% by mass. The water‐soluble product polymers are purified by aqueous dialysis, collected in the solid state by freeze‐drying, and structurally characterized by 1H–NMR spectroscopy. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1844–1849, 2001
Biosynthetic processes for linear polymers
Authors: Asrar Jawed , Hill James C.
Published: August 2002

Biosynthetic processes for production of linear proteins, polysaccharides, and polyhydroxyalkanoates (PHAs) are discussed. Processes for converting the linear biopolymers into useful products are described. Techniques and additives for improving the processability of PHAs and potential applications of PHAs are reviewed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 457–483, 2002
Limnological changes in a sub‐tropical shallow hypertrophic lake during its restoration: two years of a whole‐lake experiment
Authors: Scasso F. , Mazzeo N. , Gorga J. , Kruk C. , Lacerot G. , Clemente J. , Fabián D. , Bonilla S.
Published: August 2002

1. Lake Rodó is a turbid system, a condition attributed to algal biomass. The proximal source of the eutrophication was stormwater discharges from an ill‐defined urban area. This paper describes an attempt to restore the water quality of Lake Rodó, the first time this has been done in Uruguay. In spring 1996 it was drained, sediments were removed and stream inputs were diverted. Groundwater was used to re‐fill the lake. Due to its high nutrient concentration a re‐circulation system was designed, pumping water from associated pools covered with free‐floating plants.

2. After the lake was refilled, the system was characterized by oxygen saturation or over‐saturation, neutral to basic pH, and high phosphorus, nitrogen and silicate concentrations. Ratios of total nitrogen (TN):total phosphorus (TP) and chlorophylla(Chla):TP indicated that phosphorus was the primary limiting nutrient during the period of groundwater supply. Once groundwater pumping had ceased, there was a decrease in TN:TP and Chla:TP ratios, suggesting N‐limiting conditions prevailed in some periods.

3. Before restoration, the phytoplankton community was dominated year‐round byPlanktothrix agardhii; since restoration the community has been more diverse. This change has favoured grazing by mesozooplankton, and the onset of clear‐water phases in spring.

4. Abundant populations of small omnivorous fish maintained a high predation pressure on zooplankton, restricting the abundance of large‐bodied herbivores, which, in turn, allowed an increase in phytoplanton biomass and a decrease in water transparency. Based on this observation, together with the phosphorus concentration and the low abundance of filamentous cyanobacteria compared with previous studies, we suggest that top‐down control has played a key role in increasing transparency in Lake Rodó.

5. A nutrient reduction programme, by the mechanical harvest of floating plants, and a removal of small omnivorous fishes and stocking strictly with piscivores, could be key factors in the achievement of a stable clear‐water phase. However, if blooms ofMicrocystisor other similar genera occur in summer, additional measures (e.g. reduction of the hydraulic residence time) will be needed to improve water transparency.

Copyright © 2001 John Wiley & Sons, Ltd.
From Wolff's law to the Utah paradigm: Insights about bone physiology and its clinical applications
Authors: Frost Harold M.
Published: August 2002

Efforts to understand our anatomy and physiology can involve four often overlapping phases. We studywhatoccurs, thenhow, then askwhy, and then seekclinical applications. In that regard, in 1960 views, bone's effector cells (osteoblasts and osteoclasts) worked chiefly to maintain homeostasis under the control of nonmechanical agents, and that physiology had little to do with anatomy, biomechanics, tissue‐level things, muscle, and other clinical applications. But it seems later‐discovered tissue‐level mechanisms and functions (including biomechanical ones, plus muscle) are the true key players in bone physiology, and homeostasis ranks below the mechanical functions. Adding that information to earlier views led to the Utah paradigm of skeletal physiology that combines varied anatomical, clinical, pathological, and basic science evidence and ideas. While it explains in a general way how strong muscles make strong bones and chronically weak muscles make weak ones, and while many anatomists know about the physiology that fact depends on, poor interdisciplinary communication left people in many other specialties unaware of it and its applications. Those applications concern 1.) healing of fractures, osteotomies, and arthrodeses; 2.) criteria that distinguish mechanically competent from incompetent bones; 3.) design criteria that should let load‐bearing implants endure; 4.) how to increase bone strength during growth, and how to maintain it afterwards on earth and in microgravity situations in space; 5.) how and why healthy women only lose bone next to marrow during menopause; 6.) why normal bone functions can cause osteopenias; 7.) why whole‐bone strength and bone health are different matters; 8.) why falls can cause metaphyseal and diaphyseal fractures of the radius in children, but mainly metaphyseal fractures of that bone in aged adults; 9.) which methods could best evaluate whole‐bone strength, “osteopenias” and “osteoporoses”; 10.) and why most “osteoporoses” should not have bone‐genetic causes and some could have extraosseous genetic causes. Clinical specialties that currently require this information include orthopaedics, endocrinology, radiology, rheumatology, pediatrics, neurology, nutrition, dentistry, and physical, space and sports medicine. Basic science specialties include absorptiometry, anatomy, anthropology, biochemistry, biomechanics, biophysics, genetics, histology, pathology, pharmacology, and cell and molecular biology. This article reviews our present general understanding of this new bone physiology and some of its clinical applications and implications. It must leave to other times, places, and people the resolution of questions about that new physiology, and to understand the many devils that should lie in its details. (Thompson D'Arcy,1917). Anat Rec 262:398–419, 2001. © 2001 Wiley‐Liss, Inc.
Expression of extracellular matrix metalloproteinase inducer and enhancement of the production of matrix metalloproteinases in rheumatoid arthritis
Authors: Tomita Tetsuya , Nakase Takanobu , Kaneko Motoharu , Shi Kenrin , Takahi Koichiro , Ochi Takahiro , Yoshikawa Hideki
Published: August 2002

Objective

To investigate the expression of extracellular matrix metalloproteinase inducer (EMMPRIN) at sites of joint destruction in rheumatoid arthritis (RA) and to correlate it with the production of matrix metalloproteinases (MMPs).

Methods

Reverse transcription‐polymerase chain reaction was performed to study the existence of EMMPRIN in synovial tissue derived from RA and osteoarthritis (OA) patients. In situ hybridization with a human complementary DNA specific for EMMPRIN and immunohistochemistry were performed to characterize the EMMPRIN‐expressing cells at sites of joint destruction, including bone. Northern blot analysis was performed to detect the level of expression of EMMPRIN messenger RNA (mRNA) in synovial tissue. The production of MMP‐1 and MMP‐3 by synovial tissue from RA patients was examined by enzyme‐linked immunosorbent assay.

Results

Expression of EMMPRIN mRNA was detected in synovium from 9 of 11 patients with RA and 1 of 5 patients with OA. The presence of mRNA encoding EMMPRIN was recognized in the invasive synovium at sites of joint destruction in RA but not OA. Fibroblast‐like synovial cells and granulocytes were demonstrated to express EMMPRIN mRNA. MMP‐1 and MMP‐3 production by synovial tissue was correlated with levels of expression of EMMPRIN mRNA, as detected by Northern blotting.

Conclusion

The expression of EMMPRIN stimulates the production of MMP‐1 and MMP‐3 in the synovial tissue of affected joints in RA. The results of this study suggest that EMMPRIN may be one of the important factors in progressive joint destruction in RA.
Declines in strength and balance in older adults with chronic knee pain: A 30‐month longitudinal, observational study
Authors: Messier Stephen P. , Glasser Julie L. , Ettinger Walter H. , Craven Timothy E. , Miller Michael E.
Published: August 2002

Objectives

To document changes in lower extremity strength and balance over a 30‐month period in older adults with chronic knee pain, and to identify relationships among these variables that may prove useful in designing a subsequent clinical intervention trial.

Methods

This longitudinal, 30‐month, observational study was designed to examine the association of physical, psychological, social, and environmental factors with severity and progression of physical disability caused by chronic knee pain. This article will focus on 2 physical measures: strength and dynamic balance. The participants were a cohort of 480 adults 65 years of age or older with chronic knee pain. Measurements included: 1) force platform dynamic balance measure of the center of pressure excursion during a forward and subsequent backward lean, 2) isokinetic strength measures of concentric and eccentric knee flexion and extension, and concentric ankle plantar flexion and dorsiflexion, and 3) body mass index and a knee pain scale to measure obesity and knee pain, respectively.

Results

A maximum‐likelihood analysis revealed an overall significant decline in knee (P< 0.001) and ankle (P= 0.012) strength, and balance (P< 0.001) after a 30‐month followup period. Participants with greater knee strength at baseline had less expected decline in balance at followup than their weaker counterparts (4.2% versus 7.7% for the 75th versus 25th percentiles of strength;P= 0.023). However, the absolute decline in balance over 30 months was similar regardless of baseline ankle strength.

Conclusions

Adults age ≥65 years with chronic knee pain experience significant declines in balance and lower extremity strength over a 30‐month period. Moreover, greater knee and ankle muscular strength is associated with better balance. Previous studies have shown that weight training is effective in improving balance in older adults with knee osteoarthritis. Taken together, these studies present a strong rationale for incorporating weight training into an exercise prescription for older adults with chronic knee pain.
Believe it or not: Factors influencing credibility on the Web
Authors: Wathen C. Nadine , Burkell Jacquelyn
Published: August 2002

This article reviews selected literature related to the credibility of information, including (1) the general markers of credibility, and how different source, message and receiver characteristics affect people's perceptions of information; (2) the impact of information medium on the assessment of credibility; and (3) the assessment of credibility in the context of information presented on the Internet. The objective of the literature review is to synthesize the current state of knowledge in this area, develop new ways to think about how people interact with information presented via the Internet, and suggest next steps for research and practical applications. The review examines empirical evidence, key reviews, and descriptive material related to credibility in general, and in terms of on‐line media. A general discussion of credibility and persuasion and a description of recent work on the credibility and persuasiveness of computer‐based applications is presented. Finally, the article synthesizes what we have learned from various fields, and proposes a model as a framework for much‐needed future research in this area.
Stochastic modeling of usage patterns in a web‐based information system
Authors: Chen Hui‐Min , Cooper Michael D.
Published: August 2002

Users move from one state (or task) to another in an information system's labyrinth as they try to accomplish their work, and the amount of time they spend in each state varies. This article uses continuous‐time stochastic models, mainly based on semi‐Markov chains, to derive user state transition patterns (both in rates and in probabilities) in a Web‐based information system. The methodology was demonstrated with 126,925 search sessions drawn from the transaction logs of the University of California's MELVYL® library catalog system (www.melvyl.ucop.edu). First, user sessions were categorized into six groups based on their similar use of the system. Second, by using a three‐layer hierarchical taxonomy of the system Web pages, user sessions in each usage group were transformed into a sequence of states. All the usage groups but one have third‐order sequential dependency in state transitions. The sole exception has fourth‐order sequential dependency. The transition rates as well as transition probabilities of the semi‐Markov model provide a background for interpreting user behavior probabilistically, at various levels of detail. Finally, the differences in derived usage patterns between usage groups were tested statistically. The test results showed that different groups have distinct patterns of system use. Knowledge of the extent of sequential dependency is beneficial because it allows one to predict a user's next move in a search space based on the past moves that have been made. It can also be used to help customize the design of the user interface to the system to facilitate interaction. The group CL6 labeled “knowledgeable and sophisticated usage” and the group CL7 labeled “unsophisticated usage” both had third‐order sequential dependency and had the same most‐frequently occurring search pattern: screen display, record display, screen display, and record display. The group CL8 called “highly interactive use with good search results” had fourth‐order sequential dependency, and its most frequently occurring pattern was the same as CL6 and CL7 with one more screen display action added. The group CL13, called “known‐item searching” had third‐order sequential dependency, and its most frequently occurring pattern was index access, search with retrievals, screen display, and record display. Group CL14 called “help intensive searching,” and CL18 called “relatively unsuccessful” both had third‐order sequential dependency, and for both groups the most frequently occurring pattern was index access, search without retrievals, index access, and again, search without retrievals.
Volatility analysis during the Asia crisis: a multivariate GARCH‐M model for stock returns in the U.S., Germany and Japan
Authors: Polasek Wolfgang , Ren Lei
Published: August 2002

The Asia crisis in the summer of 1997 triggered a negative shock to the world economy. But when did it hit the major stock markets? In this paper we analyse the daily stock returns in the U.S., Germany and Japan for a period of 2 years (June 21st, 1996 to June 22nd, 1998). We estimate a VAR‐GARCH in mean model to investigate the multivariate volatility effects between the time series. We are also interested in the question of whether or not the volatility of the 3 stock returns will feed back on the returns themselves. Using the marginal likelihood criterion for model selection of the stock returns we find a VAR(1)‐GARCH(2,2)‐M (1) model. The model is estimated using MCMC methods and the coefficients show quite a rich transmission pattern between the stock markets. Comparing the models before and after the Asia crisis we see that the dynamic structure of the VAR model has changed. Copyright © 2001 John Wiley & Sons, Ltd.
Estimation in integer‐valued moving average models
Authors: Brännäs Kurt , Hall Andreia
Published: August 2002

The paper presents new characterizations of the integer‐valued moving average model. For four model variants, we give moments and probability generating functions. Yule–Walker and conditional least‐squares estimators are obtained and studied by Monte Carlo simulation. A new generalized method of moment estimator based on probability generating functions is presented and shown to be consistent and asymptotically normal. The small sample performance is in some instances better than those of alternative estimators. Copyright © 2001 John Wiley & Sons, Ltd.
The corticostriatal junction: A crucial region for forebrain development and evolution
Authors: Molnár Zoltán , Butler Ann B.
Published: August 2002

Most parts of the brain are conserved across reptiles and birds (sauropsids) and mammals. Two major qualitative differences occur in the upper part, or pallium, of the telencephalon, the most rostral part of the brain. Mammals have a six‐layered neocortex and also exhibit a different morphological organization in the lateral half, or sector, of their pallium than do sauropsids. These differences of lateral pallial construction may derive from small but crucial differences in migration patterns of neuronal precursors generated at or above the corner of the lateral ventricle, the corticostriatal junction (CS). Sauropsids have a large structure, the dorsal ventricular ridge, that is proliferated from this region, and its anterior part (ADVR) receives ascending projections from the dorsal thalamus. Mammals have multiple structures in this same region—the lateral part of neocortex, amygdala, and claustrum‐endopiriform formation. We propose here that, as the degree of development of structures that form the deeper tier of the pallium varies across the stages of embryology and across phylogeny, mutations may have occurred during evolution at the origin of mammals that had profound consequences for the fate of neural populations generated in the region of the CS and its neighboring pallial germinal zone. BioEssays 24:530–541, 2002. © 2002 Wiley Periodicals, Inc.
Enzymatic degradation of carboxymethyl cellulose hydrolyzed by the endoglucanases Cel5A, Cel7B, and Cel45A from Humicola insolens and Cel7B, Cel12A and Cel45Acore from Trichoderma reesei
Authors: Karlsson Johan , Momcilovic Dane , Wittgren Bengt , Schülein Martin , Tjerneld Folke , Brinkmalm Gunnar
Published: August 2002

Enzymatic hydrolysis of carboxymethyl cellulose (CMC) has been studied with purified endoglucanases Hi Cel5A (EG II), Hi Cel7B (EG I), and Hi Cel45A (EG V) from Humicola insolens, and Tr Cel7B (EG I), Tr Cel12A (EG III), and Tr Cel45Acore (EG V) from Trichoderma reesei. The CMC, with a degree of substitution (DS) of 0.7, was hydrolyzed with a single enzyme until no further hydrolysis was observed. The hydrolysates were analyzed for production of substituted and non‐substituted oligosaccharides with size exclusion chromatography (SEC) and with matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐TOF‐MS). Production of reducing ends and of nonsubstituted oligosaccharides was determined as well. The two most effective endoglucanases for CMC hydrolysis were Hi Cel5A and Tr Cel7B. These enzymes degraded CMC to lower molar mass fragments compared with the other endoglucanases. The products had the highest DS determined by MALDI‐TOF‐MS. Thus, Hi Cel5A and Tr Cel7B were less inhibited by the substituents than the other endoglucanases. The endoglucanase with clearly the lowest activity on CMC was Tr Cel45Acore. It produced less than half of the amount of reducing ends compared to Tr Cel7B; furthermore, the products had significantly lower DS. By MALDI‐TOF‐MS, oligosaccharides with different degree of polymerization (DP) and with different number of substituents could be separated and identified. The average oligosaccharide DS as function of DP could be measured for each enzyme after hydrolysis. The combination of techniques for analysis of product formation gave information on average length of unsubstituted blocks of CMC. © 2002 John Wiley & Sons, Inc. Biopolymers 63: 32–40, 2002
Protein unfolding during reversed‐phase chromatography: II. Role of salt type and ionic strength
Authors: McNay Jennifer L. M. , O'Connell John P. , Fernandez Erik J.
Published: August 2002

While reversed‐phase chromatography (RPC) may be a powerful method for purification of proteins at the analytical scale, both preparative and analytical applications have been hindered by the complex chromatographic behavior of proteins compared to small molecules. Further, preparative applications have been limited because of poor yields caused by the denaturing conditions involved. One means for modulating both the stability and chromatographic behavior of proteins is through the use of added salt. In this investigation, we show how salt type and ionic strength affect protein conformation on RPC surfaces. Exposure of amide groups of adsorbed BPTI was monitored using nuclear magnetic resonance (NMR) spectroscopy and hydrogen–deuterium isotope exchange. Sodium chloride, sodium acetate, and ammonium sulfate were studied at ionic strengths up to I = 0.375, with adsorption hold times being 5 min and 2 h. We found that increasing ionic strength decreased exposure of the exchange reporter groups in essentially all cases. However, even at the same ionic strength the level and distribution of residue protection varied with salt type and hold time. NaCl does not protect certain reporter groups at all, while those that it does protect to some degree at short hold times can exchange slightly more at longer times. The pattern and level of protection for NaAc at short times is similar to that for NaCl, but at longer times more uniform protection is seen as the reporter groups completely exposed at short times become more protected. For (NH4)2SO4 the pattern of protection at short hold time is similar to those of the other salts, although it protects all groups much more. This would be expected from the Hofmeister series. However, at longer times the level of protection with (NH4)2SO4 decreases below that of the other salts, while it uniquely protects all groups to nearly the same level. Such subtle variations in the protein structure would not have been detected without the measurements and analysis used here. Chromatographic retention times and peak shapes were obtained for the above systems. Variations of behavior were seen that could not be correlated with any of the above protection patterns and levels or even with heuristics such as the Hofmeister series. This suggests further conformational changes upon elution may be critical to the retention process. However, an excellent correlation was found between peak width at half‐height and the average degree of unfolding, as indicated by the average level of isotopic exchange. Thus, while further studies are needed to definitively determine the connection between protein unfolding and retention, use of this correlation may improve designing and screening for chromatographic conditions that minimize protein unfolding. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 76: 233–240, 2001.
Metabolic control of recombinant monoclonal antibody N‐glycosylation in GS‐NS0 cells
Authors: Hills Anna E. , Patel Ashvin , Boyd Paul , James David C.
Published: August 2002

Variable N‐glycosylation at Asn297 in the Fc region of recombinant therapeutic immunoglobulin G (IgG) molecules, specifically terminal galactosylation and sialylation, may affect both pharmacokinetic behavior and effector functions of recombinant therapeutic antibodies. We investigated the hypothesis that IgG Fc glycosylation can be controlled by manipulation of cellular nucleotide‐sugar metabolism. In control cultures, N‐glycans associated with the Fc domain of a recombinant humanized IgG1 produced by GS‐NS0 cells in culture were predominantly biantennary, variably β‐galactosylated (average 0.3 mol galactose complex N‐glycan−1) structures with no bisecting N‐acetylglucosamine residues, sialylation, or α1,3‐linked galactosylation evident. However, a variable proportion (5% to 15%) of high‐mannose (Man5 to Man9) oligosaccharides were present. To manipulate the cellular content of the nucleotide sugar precursor required for galactosylation, UDP‐Gal, we included either 10 mM glucosamine or 10 mM galactose in the culture medium. In the case of the former, a 17‐fold increase in cellular UDP‐N‐acetylhexosamine content was observed, with a concomitant reduction (33%) in total UDP‐hexose, although the ratio of UDP‐Glc:UDP‐Gal (4:1) was unchanged. Associated with these alterations in cellular UDP‐sugar content was a significant reduction (57%) in the galactosylation of Fc‐derived oligosaccharides. The proportion of high‐mannose‐type N‐glycans (specifically Man5, the substrate for N‐acetylglucosaminyltransferase I) at Asn297 was unaffected. In contrast, inclusion of 10 mM galactose in culture specifically stimulated UDP‐Gal content almost five‐fold. However, this resulted in only a minimal, insignificant increase (6%) in β1,4‐galactosylation of Fc N‐glycans. Sialylation was not improved upon the addition of the CMP–sialic acid (CMP‐SA) precursor N‐acetylmannosamine (20 mM), even with an associated 44‐fold increase in cellular CMP‐SA content. Analysis of recombinant IgG1 Fc glycosylation during batch culture showed that β1,4‐linked galactosylation declined slightly during culture, although, in the latter stages of culture, the release of proteases and glycosidases by lysed cells were likely to have contributed to the more dramatic drop in galactosylation. These data demonstrate: (i) the effect of steric hindrance on Fc N‐glycan processing; (ii) the extent to which alterations in cellular nucleotide‐sugar content may affect Fc N‐glycan processing; and (iii) the potential for direct metabolic control of Fc N‐glycosylation. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 75: 239–251, 2001.
A new fluid distribution system for scale‐flexible expanded bed adsorption
Authors: Hubbuch Jürgen J. , Heebøll–Nielsen Anders , Hobley Timothy J. , Thomas Owen R. T.
Published: August 2002

A new fluid distribution system designed for expanded bed adsorption was introduced and studied in a 150‐cm diameter column. Based on fluid application through a rotating distributor, it eradicates the need for perforated plates, meshes, or local mixers. The effect of rotation rate on column performance was examined by fluidizing a 30‐cm high bed of supports with tap water and introducing pulses of dye or acetone tracer. Linear bed expansion was seen as the superficial fluid velocity was raised from 170 cm · h−1 to 450 cm · h−1 (3000 L · h−1 to 8000 L · h−1), and there was little change in expansion characteristics as distributor rotation rate was increased from 2.5 to 10 rpm. The distributor was observed to generate a flow pattern suitable for expanded bed adsorption when the supports were fluidized at a superficial fluid velocity of 283 cm · h−1 and dye pulses introduced. At a rotation rate of 2.5 rpm, no significant dead zones were observed, and a discrete band was formed that moved up through the bed. Furthermore, the pattern of dye movement could be used to calculate interstitial linear fluid velocities of 460 cm · h−1 and 572 cm · h−1 at the column wall and center, respectively, indicating a parabolic flow profile. The distributor rotation rate giving the best operating conditions was found to be 2.5 rpm when the bed was fluidized at a flow velocity of 283 cm · h−1 and the residence time distribution of acetone tracer examined. Under these conditions, the coefficient of axial dispersion was 6.1 × 10−6 m2 · s−1 and 29 theoretical plates were measured. When the rotation rate was raised to 10 rpm, the coefficient of axial dispersion increased to 8.08 × 10−6 m2 · s−1 and the number of theoretical plates decreased to 22. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 78: 35–43, 2002; DOI 10.1002/bit.10170
Oxygen transfer rate and sophorose lipid production by Candida bombicola
Authors: Guilmanov Vladimir , Ballistreri Alberto , Impallomeni Giuseppe , Gross Richard A.
Published: August 2002

Sophorose lipids (SLs) have applications as surfactants and are produced at high levels by several yeasts. We developed a fed‐batch shake‐flask method for the production of SLs by Candida bombicola ATCC 22214. Optimal aeration, expressed in terms of oxygen transfer rate, was between 50 and 80 mM O2/L h−1 and resulted in maximum values for both volumetric product formation (1–1.5 g/L h−1) and SL yield (350 g/L). The lowest aeration levels resulted in the enrichment in saturated fatty acid SLs at the expense of unsaturated fatty acid SLs. © 2002 John Wiley & Sons, Inc. Biotechnol Bioeng 77: 489–494, 2002; DOI 10.1002/bit.10177
Avoiding acetate accumulation in Escherichia coli cultures using feedback control of glucose feeding
Authors: Åkesson M. , Hagander P. , Axelsson J. P.
Published: August 2002

An automated glucose feeding strategy that avoids acetate accumulation in cultivations of Escherichia coli is discussed. We have previously described how a probing technique makes it possible to detect and avoid overflow metabolism using a dissolved oxygen sensor. In this article these ideas are extended with a safety net that guarantees that aerobic conditions are maintained. The method is generally applicable, as no strain‐specific information is needed and the only sensor required is a standard dissolved oxygen probe. It also gives the highest feed rate possible with respect to limitations from overflow metabolism and oxygen transfer, thus maximizing bioreactor productivity. The strategy was implemented on three different laboratory‐scale platforms and fed‐batch cultivations under different operating conditions were performed with three recombinant strains, E. coli K‐12 UL635, E. coli BL21(DE3), and E. coli K‐12 UL634. In spite of disturbances from antifoam and induction of recombinant protein production, the method reproducibly gave low concentrations of acetate and glucose. The ability to obtain favorable cultivation conditions independently of strain and operating conditions makes the presented strategy a useful tool, especially in situations where it is important to get good results on the first attempt. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 73: 223–230, 2001.
Adsorption of avidin on microfabricated surfaces for protein biochip applications
Authors: Bashir R. , Gomez R. , Sarikaya A. , Ladisch M. R. , Sturgis J. , Robinson J. P.
Published: August 2002

The adsorption of the protein avidin from hen egg white on patterns of silicon dioxide and platinum surfaces on a microchip and the use of fluorescent microscopy to detect binding of biotin are described. A silicon dioxide microchip was formed using plasma‐enhanced chemical vapor deposition while platinum was deposited using radiofrequency sputtering. After cleaning using a plasma arc, the chips were placed into solutions containing avidin or bovine serum albumin. The avidin was adsorbed onto the microchips from phosphate‐buffered saline (PBS) or from PBS to which ammonium sulfate had been added. Avidin was also adsorbed onto bovine serum albumin (BSA)‐coated surfaces of oxide and platinum. Fluorescence microscopy was used to confirm adsorption of labeled protein, or the binding of fluorescently labeled biotin onto previously adsorbed, unlabeled avidin. When labeled biotin in PBS was presented to avidin adsorbed onto a BSA‐coated microchip, the fluorescence signal was significantly higher than for avidin adsorbed onto the biochip alone. The results show that a simple, low‐cost adsorption process can deposit active protein onto a chip in an approach that has potential application in the development of protein biochips for the detection of biological species. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 73: 324–328, 2001.
Alteration of lipase chain length specificity in the hydrolysis of esters by random mutagenesis
Authors: Gaskin Duncan J. H. , Romojaro Ana , Turner Nigel A. , Jenkins John , Vulfson Evgeny N.
Published: August 2002

The feasibility of altering the chain length specificity of industrially important Rhizomucor miehei lipase was investigated by randomly mutating Phe94 in the protein groove which is responsible for accommodating the acyl chain of the substrate. The recombinant lipase was initially expressed in E. coli. Individual colonies were selected, grown, and the DNA sequence of the lipase gene determined. Fourteen of the 19 possible mutants were identified and each of these was transformed into Pichia pastoris which expresses the enzyme extracellularly. The yeast was grown and the supernatants assessed in several assays with long and short chain substrates. Based on this preliminary screen, one mutant, Phe94Gly, was selected and purified to homogeneity for further analysis. It was found that the substitution of phenylalanine 94 with glycine led to an enzyme which was about six times less active against resorufin ester but displayed 3–4 times higher activity with short chain substrates such as butyric acid esters. The observed alteration to the enzyme specificity was rationalised using the available 3D structure of the lipase. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 73: 433–441, 2001.
Drugs of abuse in a non‐conventional sample; detection of methamphetamine and its main metabolite, amphetamine in abusers' clothes by HPLC with UV and fluorescence detection
Authors: Al‐Dirbashi Osama Y. , Ikeda Kyoko , Takahashi Masakatsu , Kuroda Naotaka , Ikeda Sachiko , Nakashima Kenichiro
Published: August 2002

In this paper, we report the detection of methamphetamine and its major metabolite, amphetamine, in garments belong to known‐abusers. These compounds were extracted from the textile using a mixture of chloroform:propan‐2‐ol (3:1, v/v), derivatized with 4‐(4,5‐diphenyl‐1H‐imidazol‐2‐yl) benzoyl chloride and separated using a reversed‐phase high‐performance liquid chromatography. The derivatives were detected by measuring either fluorescence at 440 nm or absorbance at 330 nm. By using 1‐methyl‐3‐phenyl propylamine as an internal standard, calibration curves of spiked textile samples were linear over a wide range with correlation coefficients of 0.997 or better. Detection limits at a signal‐to‐noise ratio of 3 were less than or equal to 37.3 and 0.4 pg on column for the high‐performance liquid chromatography‐ultraviolet and ‐fluorescence detection methods, respectively. Intra‐ and inter‐day variations at high and low concentrations (n ≥ 3) were ≤12.7%. The developed methods were successfully applied to the determination of methamphetamine and amphetamine in clothes samples belong to abusers. Copyright © 2001 John Wiley & Sons, Ltd.

Abbreviations used:

AP

amphetamine

DIB‐Cl

4‐(4,5‐diphenyl‐1H‐imidazol‐2‐yl)benzoyl chloride

fL

fluorescence

MP

methamphetamine

MPA

1‐methyl‐3‐phenyl propylamine

p‐HMP

para‐hydroxymethamphetamine
Collective action in the face of international environmental regulation
Authors: Harrison Debbie , Easton Geoff
Published: August 2002

Most studies of environmental impacts operate at the level of the individual firm. However, firms can act collectively in the face of threats such as that described in this paper: the banning of CFCs. A framework based upon concepts from theories of collective action is used to explain why two different forms of collective action were initiated by producers of CFCs. Economic calculation operating within the social institutions of the industry seemed to provide a plausible explanation for the occurrence of co‐operative behaviour. In particular the concepts of collective goods and free riding proved to be helpful in explicating the driving forces that led to joint action in these circumstances. Copyright © 2002 John Wiley & Sons, Ltd. and ERP Environment
The lacrimal fascia redefined
Authors: Shinohara Harumichi , Taniguchi Yutaka , Kominami Rieko , Yasutaka Satoru , Kawamata Sei‐Ichi
Published: August 2002

It has been commonly accepted that the lacrimal fascia is an intact septum, composed of connective tissue, that separates the orbital cavity into a large compartment, which contains the eyeball, and a small compartment, which contains the lacrimal sac and nasolacrimal duct. the septum, however, is not necessarily always intact. We found a circular or oval opening in the lacrimal fascia in 37 of 52 specimens (71.2%) examined. The opening, which we shall refer to as the lacrimal fascial foramen, was located at variable levels in the lacrimal fossa. The lacrimal fascial foramen was buried in fatty tissue through which passed a branch of either the inferior palpebral artery or the infraorbital artery and a vein of the nasolacrimal duct. The clinical implications of the lacrimal fascial foramen in obstruction of the nasolacrimal duct are discussed. Clin. Anat. 6:401–405, 2001. © 2001 Wiley‐Liss, Inc.
Institutional responses to barriers to the transfer process
Authors: Zamani Eboni M.
Published: August 2002

The extent to which community college students make the transition from two‐ to four‐year institutions is contingent on the cooperation of these institutions. This chapter examines the creation of transfer centers and other initiatives to address the challenges in the transfer process.
The problem of arteria lusoria in right transradial coronary angiography and angioplasty
Authors: Abhaichand Rajpal K. , Louvard Yves , Gobeil Jean‐François , Loubeyre Christophe , Lefèvre Thierry , Morice Marie‐Claude
Published: August 2002

The retroesophageal right subclavian artery (arteria lusoria) is one of the anatomical abnormalities encountered by interventional cardiologists who perform right transradial procedures. We report on 11 patients with arteria lusoria in whom 14 right transradial coronary angiography or angioplasty procedures were attempted among a series of 3,730 consecutive right transradial attempts. This abnormality can be easily detected by angiographic visualization, in the anteroposterior projection, of the angle of the catheter when it engages the ascending aorta, and by manual angiography at the ostium of the right subclavian artery. In such a case, catheterization of the ascending aorta may be difficult or even impossible (7.1%). Selective catheterization of both coronary arteries is more difficult, takes longer, and requires more catheters. The Judkins catheters are recommended, although they are seldom used for the left coronary artery via the right radial approach, for both arteries. All catheter exchanges should be performed on long guidewires. Cathet Cardiovasc Intervent 2001;54:196–201. © 2001 Wiley‐Liss, Inc.
Meeting Review: The Intelligent Systems in Bioinformatics Conference 2001 (ISMB2001)
Authors: Woodwark K. Cara
Published: August 2002

Meeting Review of the Intelligent Systems in Bioinformatics Conference 2001 (ISMB2001), held 21–25 July, Tivoli Gardens, Copenhagen.
Absolute configuration at C14 and C85 in prymnesin‐2, a potent hemolytic and ichthyotoxic glycoside isolated from the red tide alga Prymnesium parvum
Authors: Morohashi Akio , Satake Masayuki , Oshima Yasukatsu , Igarashi Tomoji , Yasumoto Takeshi
Published: August 2002

Prymnesin‐2 is a potent red tide toxin characterized by a highly oxidized C90 carbon chain and multiple functional groups. Succeeding the assignment of the relative stereochemistry in the polycyclic‐ether segment, the absolute configurations of two chiral centers in linear chain parts were elucidated. The configuration at C14 bearing an amino group was determined to be S by using a chiral anisotropic reagent and that at chlorinated C85 to be S by fluorimetric chiral HPLC comparison between a degradation product and synthetic references. Chirality 13:601–605, 2001. © 2001 Wiley‐Liss, Inc.
Organizational competence analysis: Experience of a Japanese multinational
Authors: Wang Clement K.
Published: August 2002

As global competition intensifies rather than abates, firms must develop skills in scanning and monitoring other firms' competencies and assess their future focus and paths relative to their own. I propose a competence‐based approach to competitive analysis for understanding how rival firms in technology‐based industries may compete into the future. I propose an organizational competence analysis (OCA) framework that links the strategic component of competitive analysis to decision making by emphasizing the identification and interpretation of a competitor's organizational competencies (both technical and nontechnical). I apply the OCA framework by analyzing a large Japanese multinational (Firm X) in a technology‐based industry. The results obtained from open source materials are assessed and evaluated by Firm X's technical staff members for validity. Based on the feedback, we conclude that a firm could benefit, as a result of using the OCA framework, from increased understanding of a competing firm's source of competitiveness in the form of its organizational competencies, substantiated by ongoing monitoring of relevant competitive information from both the firm and industry levels. © 2001 John Wiley & Sons, Inc.