bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on blown film extrusion. III. Bubble instability
Authors: Han Chang Dae , Park Jong Yoo
Published: April 2003

An experimental study has been carried out to investigate flow instabilities in blown film extrusion. Two types of flow instabilities were observed, depending on whether a bubble was under uniaxial or biaxial stretching. Under biaxial stretching, the phenomenon of a surface wave‐type instability was observed, yielding wavy bubble shapes which very much resembled water waves at the free surface. Under uniaxial stretching, another type of instability, frequently referred to as draw resonance, was observed. It was also observed that, once draw resonance occurs, the amplitude and frequency of bubble diameter pulsing increased with stretch ratio. Quantitative information was obtained from a series of motion pictures taken of bubble diameter in both types of flow instability. It was observed further that an increase in extrusion melt temperature enhanced the severity of bubble instability.
Gelation of dilute collagen solutions by ultraviolet light
Authors: Hamed Gary , Rodriguez Ferdinand
Published: April 2003

Dilute collagen and collagen–polymer solutions were irradiated at 4°C with UV light (254 nm) under a nitrogen atmosphere. The collagen had been recovered from native tissue by a process of simultaneous acid solubilization together with proctase treatment to remove telopeptides. In the range of concentrations studied (0.1% to 0.9% collagen), gelation occurs after a few minutes, and the dynamic mechanical properties are followed thereafter using a freely oscillating torsion pendulum. During the irradiation, crosslinking and scission reactions compete. Initially crosslinking reactions dominate and the storage modulus increases. However, with extensive irradiation, scission reactions become important, and the storage modulus passes through a maximum and finally decreases. Furthermore, the time for incipient gelation decreases with concentration and the maximum storage modulus increases with concentration to the 2.5 power for collagen solutions. As an example, the maximum storage modulus for a 0.5% solution is 1.1×104 dynes/cm2. The modulus–dose behavior can be reduced to a single relationship in which the ratio of modulus to maximum modulus is a function of dose divided by dose to reach the maximum modulus.
The mechanism of corona and ultraviolet light‐induced self‐adhesion of poly(ethylene terephthalate) film
Authors: Owens D. K.
Published: April 2003

The ability of corona treatment to render polyethylene film self‐adherent has been previously reported and the mechanism explained. A similar effect has now been found with corona‐treated poly(ethylene terephthalate) film which adheres strongly to itself when joined under conditions of heat and pressure that give no adhesion with untreated film. Poly(ethylene terephthalate) films irradiated with short‐wave UV light also become self‐adherent. The behavior of the adhesive joints in both cases is the same as that reported for corona‐treated polythylene film in that the joint strength is zero in the presence of hydrogen‐bonding liquids, but recovers completely if the joint is allowed to dry undisturbed. Chemical and physical tests have shown that the adhesive bond is a hydrogen bond between the hydrogens of phenol groups created by corona or UV irradiation in one surface with carboxyl carbonyl groups in the other surface. Thin‐layer chromatography of surface extracts from corona‐ and UV‐treated films has shown the products of treatment to be practically identical for both types of treatment, supporting the conclusion that the mechanism of corona treatment resembles that of greatly accelerated photo‐oxidation.
Oxidative degradation of polyolefins. I. Thermal oxidative degradation of atactic polypropylene in solution
Authors: Niki Etsuo , Shiono Takeo , Ido Teruyoshi , Kamiya Yoshio
Published: April 2003

Atactic polypropylene was oxidized in solution with radical initiator in the absence and presence of metal catalyst to considerably high conversion over the temperature range of 70° to 125°C, and oxidation products and the change in molecular weight distribution were measured. The unoxidized polypropylene had no ultraviolet absorption at 253.7 nm, whereas the oxidized polypropylene showed distinct absorption over a wide range of molecular weights. It was found that oxygen was incorporated into the polymer chain as hydroperoxide, acid, carbonyl, and hydroxy groups. Much of the absorbed oxygen was found to be involved in smaller fraction of low molecular weight products. Although the average molecular weight of the oxidized polypropylene decreased significantly, the formation of low‐boiling products was quite small.
Fracture properties of rigid polyurethane foams
Authors: Anderton G. E.
Published: April 2003

The fracture behavior of rigid polyurethane foams has been investigated and is shown to obey the Griffith criterion for fracture in so far as the predicted behavior of tensile strength on the size of artificially introduced cracks is concerned. The energy for crack propagation (fracture surface energy) has been measured as 91.4J/m2. From this result, the intrinsic flaw size of the material is calculated. This value was found to be within the range of cell dimensions of the material.
Cuticular hydrocarbons and wax esters of the ectoparasitoid Habrobracon hebetor: Ontogenetic, reproductive, and nutritional effects
Authors: Howard Ralph W. , Baker James E.
Published: April 2003

Hydrocarbon and wax ester components of cuticular lipids of the braconid parasitoid Habrobracon hebetor Say reared at 25°C on larvae of a pyralid moth have been identified by GC‐MS and analyzed with respect to adult age, mating status, and diet. The hydrocarbons range in carbon number from C21 to C45 and consist of a homologous series of n‐alkanes, 11‐, 13‐, and 15‐methyl alkanes, 13,17‐dimethyl alkanes, and Z‐5, Z‐7, and Z‐9‐alkenes. The wax esters found in the cuticular lipid fraction are a series of homologous compounds with the acid portion being short chain, unbranched, even carbon number acids from C8 to C20 (predominately C8 to C16). The alcohol portions of the esters are secondary alcohols with carbon number from C22 to C25 (predominately C23 and C25) with the hydroxyl function located at C6, C7, C8, and C9. Gender, age, and nutritional states were significant factors for variation in several of the individual esters, but mating status did not affect wax ester composition. Ontogenetic examinations indicated that prepupal, and early pupal cuticular lipids contain only hydrocarbons. Low levels of wax esters are detectable in late stage pupae, and somewhat greater quantities of wax esters are present on newly eclosed adults. When pharate adults emerge from the cocoon, however, their cuticular lipids consist of approximately equal amounts of hydrocarbons and wax esters, and 6d post emergence from the cocoon, wax esters are the predominant lipid component. Arch. Insect Biochem. Physiol. 53:1–18, 2003. Published 2003 Wiley‐Liss, Inc.†
Proteolytic gut activities in the rice water weevil, Lissorhoptrus brevirostris Suffrian (Coleoptera: Curculionidae)
Authors: Hernández Carlos A. , Pujol Merardo , Alfonso‐Rubí Julio , Armas Raúl , Coll Yamilet , Pérez Maylin , González Annerys , Ruiz Marisa , Castañera Pedro , Ortego Félix
Published: April 2003

Digestive endoprotease activities of the rice water weevil, Lissorhoptrus brevirostris Suffrian (Coleoptera: Curculionidae), were characterized based on the ability of gut extracts to hydrolyze specific synthetic substrates, optimal pH, and hydrolysis sensitivity to protease inhibitors. Larvae of this species were found to use a complex proteolytic system that includes cathepsin D‐, cathepsin B‐, trypsin‐, and chymotrypsin‐like activities. Trypsin‐like activity was evenly distributed among the anterior, middle, and posterior portions of the gut, whereas cathepsin B– and cathepsin D–like activities were mainly located in the anterior and middle sections, and the chymotrypsin‐like activity was highest in the middle and posterior sections. Gelatin‐containing native‐PAGE gels indicated the presence of several aspartyl, cysteine, and serine protease forms and confirmed the spatial organization of the proteolytic digestive process. Arch. Insect Biochem. Physiol. 53:19–29, 2003. © 2003 Wiley‐Liss, Inc.
Midgut proteases from Mamestra configurata (Lepidoptera: Noctuidae) larvae: Characterization, cDNA cloning, and expressed sequence tag analysis
Authors: Hegedus Dwayne , Baldwin Doug , O'Grady Michael , Braun Lorraine , Gleddie Steve , Sharpe Andrew , Lydiate Derek , Erlandson Martin
Published: April 2003

The activities of digestive protease within the midgut of Mamestra configurata (bertha armyworm) larvae were examined using specific substrates and protease inhibitors. The bulk of the activity was associated with serine proteases comprising trypsin‐, chymotrypsin‐, and elastase‐like enzymes. At least 10–15 serine protease isozymes were detected using one‐dimension gelatin gel electrophoresis. Cysteine or aspartic protease activities were not present; however, amino‐ and carboxypeptidase activities were associated with the midgut extract. Midgut proteases were active in the pH range of 5.0–12.0 with peaks at pH 7.5 and 11.0. In general, the middle region of the midgut exhibited a higher pH (approximately 8.0) than either the posterior or anterior regions (approximately 7.3–7.7). Moulting larvae possessed a neutral gut pH that was 0.5–1.5 units below that of feeding larvae. Degenerate PCR and expressed sequence tag (EST)‐based approaches were used to isolate 30 distinct serine protease encoding cDNAs from a midgut‐specific cDNA library including 8 putative trypsins, 9 chymotrypsins, 1 elastase, and 12 whose potential activities could not be determined. cDNAs encoding three amino‐ and two carboxypeptidases were also identified. Larvae feeding upon artificial diet containing 0.2% soybean trypsin inhibitor experienced a significant delay in development. Arch. Insect Biochem. Physiol. 53:30–47, 2003. © 2003 Wiley‐Liss, Inc.
The connection between the research of a university and counts of links to its web pages: An investigation based upon a classification of the relationships of pages to the research of the host university
Authors: Thelwall Mike , Harries Gareth
Published: April 2003

Results from recent advances in link metrics have demonstrated that the hyperlink structure of national university systems can be strongly related to the research productivity of the individual institutions. This paper uses a page categorization to show that restricting the metrics to subsets more closely related to the research of the host university can produce even stronger associations. A partial overlap was also found between the effects of applying advanced document models and separating page types, but the best results were achieved through a combination of the two.
Type/Token‐Taken informetrics
Authors: Egghe Leo
Published: April 2003

Type/Token‐Taken informetrics is a new part of informetrics that studies the use of items rather than the items itself. Here, items are the objects that are produced by the sources (e.g., journals producing articles, authors producing papers, etc.). In linguistics a source is also called a type (e.g., a word), and an item a token (e.g., the use of words in texts). In informetrics, types that occur often, for example, in a database will also be requested often, for example, in information retrieval. The relative use of these occurrences will be higher than their relative occurrences itself; hence, the name Type/Token‐Taken informetrics. This article studies the frequency distribution of Type/Token‐Taken informetrics, starting from the one of Type/Token informetrics (i.e., source–item relationships). We are also studying the average number μ* of item uses in Type/Token‐Taken informetrics and compare this with the classical average number μ in Type/Token informetrics. We show that μ* ≥ μ always, and that μ* is an increasing function of μ. A method is presented to actually calculate μ* from μ, and a given α, which is the exponent in Lotka's frequency distribution of Type/Token informetrics. We leave open the problem of developing non‐Lotkaian Type/Token‐Taken informetrics.
Adapting measures of clumping strength to assess term‐term similarity
Authors: Bookstein Abraham , Kulyukin Vladimir , Raita Timo , Nicholson John
Published: April 2003

Automated information retrieval relies heavily on statistical regularities that emerge as terms are deposited to produce text. This paper examines statistical patterns expected of a pair of terms that are semantically related to each other. Guided by a conceptualization of the text generation process, we derive measures of how tightly two terms are semantically associated. Our main objective is to probe whether such measures yield reasonable results. Specifically, we examine how the tendency of a content bearing term to clump, as quantified by previously developed measures of term clumping, is influenced by the presence of other terms. This approach allows us to present a toolkit from which a range of measures can be constructed. As an illustration, one of several suggested measures is evaluated on a large text corpus built from an on‐line encyclopedia.
Relevant term suggestion in interactive web search based on contextual information in query session logs
Authors: Huang Chien‐Kang , Chien Lee‐Feng , Oyang Yen‐Jen
Published: April 2003

This paper proposes an effective term suggestion approach to interactive Web search. Conventional approaches to making term suggestions involve extracting co‐occurring keyterms from highly ranked retrieved documents. Such approaches must deal with term extraction difficulties and interference from irrelevant documents, and, more importantly, have difficulty extracting terms that are conceptually related but do not frequently co‐occur in documents. In this paper, we present a new, effective log‐based approach to relevant term extraction and term suggestion. Using this approach, the relevant terms suggested for a user query are those that co‐occur in similar query sessions from search engine logs, rather than in the retrieved documents. In addition, the suggested terms in each interactive search step can be organized according to its relevance to the entire query session, rather than to the most recent single query as in conventional approaches. The proposed approach was tested using a proxy server log containing about two million query transactions submitted to search engines in Taiwan. The obtained experimental results show that the proposed approach can provide organized and highly relevant terms, and can exploit the contextual information in a user's query session to make more effective suggestions.
A novel method for discovering fuzzy sequential patterns using the simple fuzzy partition method
Authors: Chen Ruey‐Shun , Hu Yi‐Chung
Published: April 2003

Sequential patterns refer to the frequently occurring patterns related to time or other sequences, and have been widely applied to solving decision problems. For example, they can help managers determine which items were bought after some items had been bought. However, since fuzzy sequential patterns described by natural language are one type of fuzzy knowledge representation, they are helpful in building a prototype fuzzy knowledge base in a business. Moreover, each fuzzy sequential pattern consisting of several fuzzy sets described by the natural language is well suited for the thinking of human subjects and will help to increase the flexibility for users in making decisions. Additionally, since the comprehensibility of fuzzy representation by human users is a criterion in designing a fuzzy system, the simple fuzzy partition method is preferable. In this method, each attribute is partitioned by its various fuzzy sets with pre‐specified membership functions. The advantage of the simple fuzzy partition method is that the linguistic interpretation of each fuzzy set is easily obtained. The main aim of this paper is exactly to propose a fuzzy data mining technique to discover fuzzy sequential patterns by using the simple partition method. Two numerical examples are utilized to demonstrate the usefulness of the proposed method.
HelpfulMed: Intelligent searching for medical information over the internet
Authors: Chen Hsinchun , Lally Ann M. , Zhu Bin , Chau Michael
Published: April 2003

Medical professionals and researchers need information from reputable sources to accomplish their work. Unfortunately, the Web has a large number of documents that are irrelevant to their work, even those documents that purport to be “medically‐related.” This paper describes an architecture designed to integrate advanced searching and indexing algorithms, an automatic thesaurus, or “concept space,” and Kohonen‐based Self‐Organizing Map (SOM) technologies to provide searchers with fine‐grained results. Initial results indicate that these systems provide complementary retrieval functionalities. HelpfulMed not only allows users to search Web pages and other online databases, but also allows them to build searches through the use of an automatic thesaurus and browse a graphical display of medical‐related topics. Evaluation results for each of the different components are included. Our spidering algorithm outperformed both breadth‐first search and PageRank spiders on a test collection of 100,000 Web pages. The automatically generated thesaurus performed as well as both MeSH and UMLS—systems which require human mediation for currency. Lastly, a variant of the Kohonen SOM was comparable to MeSH terms in perceived cluster precision and significantly better at perceived cluster recall.
Pharmacokinetic profile of a modified release formulation of trimetazidine (TMZ MR 35 mg) in the elderly and patients with renal failure
Authors: Barré J. , Ledudal P. , Oosterhuis B. , Brakenhoff J.P.G. , Wilkens G. , Sollie F.A.E. , Tran D.
Published: April 2003

Objectives – To study the effect of age and renal function on the pharmacokinetic profile of a modified release tablet of trimetazidine (TMZ MR 35 mg) administered twice daily.

Methods– Study 1: Twelve healthy elderly subjects (CLcreat 72±8 ml/min, 72±4 years mean±SD) and eight young volunteers (CLcreat 134±18 ml/min, 25±8 years) received TMZ MR 35 mg b.i.d. (eight doses). Study 2: eight patients with severe renal failure (CLcreat. 17±5 ml/min, 54±10 years), five patients with moderate renal failure (CLcreat. 39±6 ml/min, 54±15 years) and eight volunteers (CLcreat. 104±17 ml/min, 53±9 years) received TMZ MR 35 mg b.i.d. (patients: ten doses, volunteers: eight doses). Serial blood and urine samples were obtained following administration of the last dose in each study. TMZ plasma and urine concentrations were determined by gas chromatography (NPD‐detector). The resulting data were analysed using standard non‐compartmental pharmacokinetic methods.

Results– Study 1: Elimination half‐life of TMZ was significantly longer and renal clearance significantly lower in the elderly subjects. Study 2: In patients with either moderate or severe renal failure, exposure (AUC0–24) was significantly increased and renal clearance (CLR) was significantly decreased. Significant correlations were observed between CLcreat and CLR (r=0.94) and between CLcreat and AUC0–24 (r=−0.94).

Conclusion – With repeated administration of TMZ MR 35 mg b.i.d., a decrease in CLcreat is directly related to a decrease in CLR and results in an increase in exposure to TMZ. Copyright © 2003 John Wiley & Sons, Ltd.
Impact of solutol HS 15 on the pharmacokinetic behaviour of colchicine upon intravenous administration to male Wistar rats
Authors: Bittner Beate , González Roberto Carlos Bravo , Walter Isabelle , Kapps Martin , Huwyler Jörg
Published: April 2003

In the current investigation, the alkaloid colchicine was administered intravenously to male Wistar rats both as a solution in isotonic sodium chloride (NaCl 0.9%, control group) and in NaCl 0.9%:Solutol HS 15 (95:5) at 1.5 mg/kg. At predetermined time points, plasma and urine were collected from the animals and analysed for colchicine and its demethylated metabolites by LC/MS‐MS.

In the presence of Solutol HS 15, colchicine clearance (CI) was significantly decreased and its maximum plasma concentration (cmax) was significantly increased as compared to the control group (CI: 15.6±7.0 ml/min/kg vs 34.3±2.3 ml/min/kg; cmax 3055.1±587.4 h vs 1260.1±223.7 h; p<0.05). Moreover, the amount of parent colchicine excreted into urine was markedly increased in the Solutol HS 15 treated group (41.50±3.23 vs 1.17±0.41% of total dose; p<0.05). By contrast, there was no statistically significant difference but a trend to lower values only in the volume of distribution (Vd 13.3±2.2 l/h vs 31.4±17.7 l/h, p=0.35). The half‐lives for the first (t1/2 1stphase. 0.21±0.02 h vs 0.20±0.03 h) and second phase (t1/2 2ndphase. 18.5±6.9 h vs 18.3±7.7 h) did not differ significantly in dependence on the dosing vehicle. The free fraction in rat plasma (FF), the blood/plasma (λ) and erythrocyte/plasma concentration ratios (Ke) were not significantly changed in the presence of different concentrations of Solutol HS 15 compared with surfactant‐free incubations (overall means: 72.25±0.50% for FF, 0.80±0.02 for λ, 0.46±0.04 for Ke). In vitro, in rat hepatocytes, the clearance of colchicine was significantly reduced at 0.003% Solutol HS 15 present in the incubation medium (0.86±0.15 μl/min/10−6 cells vs 1.46±0.06 μl/min/10−6 cells). As colchicine exhibits a comparatively high aqueous solubility, an impact of Solutol HS 15 on the solubility of the alkaloid is very unlikely to be a reason for the observed effect. Therefore, our results indicate that the most likely reasons for the changed pharmacokinetic behaviour of colchicine in the presence of Solutol HS 15 are alterations of metabolism and/or transport as well as distribution and elimination processes. Copyright © 2003 John Wiley & Sons, Ltd.
Pharmacokinetics of an ultralong sustained‐release theophylline formulation when given twice daily in elderly patients with chronic obstructive pulmonary disease: Monitoring implications
Authors: Armijo Juan A. , Sánchez Blanca M. , Peralta F. Galo , González‐Ruiz Mario , Cuadrado Antonio , Verdejo Asunción , Cos María A. de , Arjona Rafael
Published: April 2003

The steady‐state pharmacokinetics of an ultralong sustained release formulation of theophylline (Unilong®) twice daily (bid) in elderly hospitalized patients suffering from chronic obstructive pulmonary disease (COPD) have been studied in order to establish guidelines for monitoring. The study was carried out in 37 patients (33 men), aged 60–87 years. Samples were collected from 0 to 12 h after the morning dose on day 9 of treatment with 250 mg bid (n=25) or 375 mg bid (n=12). Considerable variability in apparent clearance (range 0.33–1.49 ml/min per kg of ideal body weight), Cssmin/D (range 0.28–1.86), Cssmax/D (range 0.65–2.33) and (Cssmax–Cssmin)/Cssavg (range 0.18–0.80) was observed. There was no significant correlation between the patient's age and apparent clearance within this elderly population. The concentration‐to‐dose ratio and the relationship between the steady‐state plasma concentration at different times during the dosage interval and Cssavg are described. It is concluded that the interpatient variability in peak‐trough fluctuation of this formulation was higher than that described in healthy volunteers by other investigators, and that the apparent clearance did not decrease with age within this elderly population with COPD. The importance of theophylline monitoring is emphasized and rules to estimate Cssavg and Css5h from Css0h when only a single sample obtained before the morning dose is available are given. Copyright © 2003 John Wiley & Sons, Ltd.
Determination of procaine hydrochloride using flow injection inhibitory chemiluminescence
Authors: Li Nianbing , Chi Yuwu , Wang Jian , Duan Jianping , Chen Guonan
Published: April 2003

A new flow injection chemiluminescent method has been developed for the determination of procaine hydrochloride, based on the inhibition of the chemiluminescence reaction of luminol–hydrogen peroxide by procaine hydrochloride. The influence of several surfactants and β‐cyclodextrin on the chemiluminescence intensity were studied. It was found that β‐cyclodextrin enhanced the decrease in chemiluminescence intensity. The method is simple, convenient and sensitive, with a detection limit (3 σ) of 0.08 µg/mL. The decreased chemiluminescence intensity is linear, with the concentration of procaine hydrochloride in the range 0.2–100.0 µg/mL and 100.0–400.0 µg/mL. The relative standard deviation for 10 repeated measurements were 4.5% and 3.4% for 1.0 and 20.0 µg/mL procaine hydrochloride, respectively. The method has been successfully applied to the determination of procaine hydrochloride in injection solutions of this drug. Copyright © 2003 John Wiley & Sons, Ltd.
Comparison of the spectral emission of lux recombinant and bioluminescent marine bacteria
Authors: Thouand Gérald , Daniel Philippe , Horry Habib , Picart Pascal , Durand Marie José , Killham Ken , Knox Oliver GG , DuBow Michael S , Rousseau Michel
Published: April 2003

The purpose of the present paper was to study the influence of bacteria harbouring the luciferase‐encoding Vibrio harveyi luxAB genes upon the spectral emission during growth in batch‐culture conditions. In vivo bioluminescence spectra were compared from several bioluminescent strains, either naturally luminescent (Vibrio fischeri and Vibrio harveyi) or in recombinant strains (two Gram‐negative Escherichia coli::luxAB strains and a Gram‐positive Bacillus subtilis::luxAB strain). Spectral emission was recorded from 400 nm to 750 nm using a highly sensitive spectrometer initially devoted to Raman scattering. Two peaks were clearly identified, one at 491–500 nm (± 5 nm) and a second peak at 585–595 (± 5 nm) with the Raman CCD. The former peak was the only one detected with traditional spectrometers with a photomultiplier detector commonly used for spectral emission measurement, due to their lack of sensitivity and low resolution in the 550–650 nm window. When spectra were compared between all the studied bacteria, no difference was observed between natural or recombinant cells, between Gram‐positive and Gram‐negative strains, and growth conditions and growth medium were not found to modify the spectrum of light emission. Copyright © 2003 John Wiley & Sons, Ltd.
Transient formation of the oxo–iron(IV) porphyrin radical cation during the reaction of iron(III) tetrakis‐5,10,15,20‐(N‐methyl‐4‐pyridyl)porphyrin with hydrogen peroxide in aqueous solution
Authors: Saha Tapan Kumar , Karmaker Subarna , Tamagake Keietsu
Published: April 2003

The reaction of iron(III) tetrakis‐5,10,15,20‐(N‐methyl‐4‐pyridyl)porphyrin (Fe(III)TMPyP) with hydrogen peroxide (H2O2) and the catalytic activity of the reaction intermediates on the luminescent peroxidation of luminol in aqueous solution were studied by using a double‐mixing stopped‐flow system. The observed luminescence intensities showed biphasic decay depending on the conditions. The initial flashlight decayed within <1 s followed by a sustained emission for more than 30 s. Computer deconvolution of the time‐resolved absorption spectra under the same conditions revealed that the initial flashlight appeared during the formation of the oxo–iron(IV) porphyrin, TMPyPFe(IV) = O, which is responsible for the sustained emission. The absorption spectra 0.0–0.5 s did not reproduce well by a simple combination of the two spectra of Fe(III)TMPyP and TMPyPFe(IV) = O, indicating that transient species was formed at the initial stage. Addition of uric acid (UA) caused a significant delay in the initiation of the luminol emission as well as in the formation of the TMPyPFe(IV) = O. Both of them were completely diminished in the presence of UA equimolar with H2O2, while mannitol had no effect at all. The delay of the light emission as well as the appearance of TMPyPFe(IV) = O was directly proportional to the [UA]0 but other kinetic profiles were not changed significantly. Based on these observations and the kinetic analysis, we confirmed the involvement of the oxo–iron(IV) porphyrin radical cation, (TMPyP)·+Fe(IV) = O, as an obligatory intermediate in the rate‐determining step of the overall reaction, Fe(III)TMPyP + H2O2 → TMPyPFe(IV) = O, with a rate constant of k = 4.3 × 104/mol/L/s. The rate constants for the reaction between the (TMPyP)·+Fe(IV) = O and luminol, and between the TMPyPFe(IV) = O and luminol were estimated to be 3.6 × 106/mol/L/s and 1.31 × 104/mol/L/s, respectively. Copyright © 2003 John Wiley & Sons, Ltd.
Interaction of aromatic compounds with Photobacterium leiognathi luciferase: fluorescence anisotropy study
Authors: Kudryasheva N. S. , Nemtseva E. V. , Visser A. J. W. G. , van Hoek A.
Published: April 2003

The time‐resolved and steady‐state fluorescence techniques were employed to elucidate possible interactions of four aromatic compounds (anthracene, POPOP, MSB and 1,4‐naphthalendiol) with bacterial luciferase. Fluorescence spectra and fluorescence anisotropy decays of these compounds were studied in ethanol, water–ethanol solutions and in the presence of bacterial luciferase. Shifts of fluorescent spectra and differences in rotational correlation times are interpreted in terms of weak (hydrophobic) interactions of the molecules with the enzyme. These interactions suggest the feasibility of intermolecular energy transfer by an exchange resonance mechanism with a collision‐interaction radius as a way of excitation of these compounds in the reaction catalysed by bacterial luciferase. Copyright © 2003 John Wiley & Sons, Ltd.
Measurement of adenine nucleotides in plasma
Authors: Gorman Mark W. , Marble David R. , Ogimoto Kayoko , Feigl Eric O.
Published: April 2003

The goal of this study was to identify the most important variables affecting bioluminescent ATP, ADP and AMP measurements in plasma and to develop an assay that takes these variables into account. Blood samples were drawn from conscious dogs. A ‘stop solution’ containing EDTA was prepared, which greatly retarded plasma ATP degradation by chelating Mg+2 and Ca+2 that are co‐factors for many ATPases. Stop solution and blood were mixed using a two‐syringe withdrawal system. Samples were centrifuged twice in order to remove red blood cells, and ATP was measured in the supernatant using the firefly luciferase assay. Sample pH was adjusted to the optimal range (7.75–7.95) and Mg2+ (necessary for the luciferase reaction) was added back to the sample within the luminometer 2 s prior to luciferase addition. Four assay tubes were prepared for each plasma sample, containing standard additions of 0–15 pmol added ATP, in order to quantify native plasma ATP content. In separate plasma/stop solution samples ADP + ATP was measured after converting ADP to ATP via the pyruvate kinase reaction, and AMP + ADP + ATP was measured after addition of both myokinase and pyruvate kinase. Addition of forskolin and isobutylmethylxanthine (IBMX) to the stop solution to inhibit platelets resulted in lower ATP concentrations. Measurement of ATP and haemoglobin from lysed erythrocytes revealed that haemolysis exerts a strong influence on plasma ATP concentration that must be taken into account. Copyright © 2003 John Wiley & Sons, Ltd.
Experimental investigations of multiple steady states in aerobic continuous cultivations of Saccharomyces cerevisiae
Authors: Lei Frede , Olsson Lisbeth , Jørgensen Sten Bay
Published: April 2003

The steady‐state behavior of a glucose‐limited, aerobic, continuous cultivation of Saccharomyces cerevisiae CEN.PK113‐7D was investigated around the critical dilution rate. Oxido‐reductive steady states were obtained at dilution rates up to 0.09 h−1 lower than the critical dilution rate by operating the bioreactor as a productostat, where the dilution rate was controlled on the basis of an ethanol measurement. Thus, the experimental investigations revealed that multiple steady states exist in a region of dilution rates below the critical dilution rate. The existence of multiple steady states was attributed to two distinct physiological effects occurring when growth changed from oxidative to oxido‐reductive: (i) a decrease in the efficiency of ATP production and utilization (at ethanol concentrations below 3 g/L) and (ii) repression of the oxidative metabolism (at higher ethanol concentrations). The first effect was best observed at low ethanol concentrations, where multiple steady states were observed even when no repression of the oxidative metabolism was evident, i.e., the oxidative capacity was constant. However, at higher ethanol concentrations repression of the oxidative metabolism was observed (the oxidative capacity decreased), and this resulted in a broader range of dilution rates where multiple steady states could be found. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 82: 766–777, 2003.
Dynamics of the anaerobic process: Effects of volatile fatty acids
Authors: Pind Peter F. , Angelidaki Irini , Ahring Birgitte K.
Published: April 2003

A complex and fast dynamic response of the anaerobic biogas system was observed when the system was subjected to pulses of volatile fatty acids (VFAs). It was shown that a pulse of specific VFAs into a well‐functioning continuous stirred tank reactor (CSTR) system operating on cow manure affected both CH4 yield, pH, and gas production and that a unique reaction pattern was seen for the higher VFAs as a result of these pulses. In this study, two thermophilic laboratory reactors were equipped with a novel VFA‐sensor for monitoring specific VFAs online. Pulses of VFAs were shown to have a positive effect on process yield and the levels of all VFA were shown to stabilize at a lower level after the biomass had been subjected to several pulses. The response to pulses of propionate or acetate was different from the response to butyrate, iso‐butyrate, valerate, or iso‐valerate. High concentrations of propionate affected the degradation of all VFAs, while a pulse of acetate affected primarily the degradation of iso‐valerate or 2‐methylbutyrate. Pulses of n‐butyrate, iso‐butyrate, and iso‐valerate yielded only acetate, while degradation of n‐valerate gave both propionate and acetate. Product sensitivity or inhibition was shown for the degradation of all VFAs tested. Based on the results, it was concluded that measurements of all specific VFAs are important for control purposes and increase and decrease in a specific VFA should always be evaluated in close relationship to the conversion of other VFAs and the history of the reactor process. It should be pointed out that the observed dynamics of VFA responses were based on hourly measurements, meaning that the response duration was much lower than the hydraulic retention time, which exceeds several days in anaerobic CSTR systems. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 82: 791–801, 2003.
Potential of cell retention techniques for large‐scale high‐density perfusion culture of suspended mammalian cells
Authors: Voisard D. , Meuwly F. , Ruffieux P.‐A. , Baer G. , Kadouri A.
Published: April 2003

This review focuses on cultivation of mammalian cells in a suspended perfusion mode. The major technological limitation in the scaling‐up of these systems is the need for robust retention devices to enable perfusion of medium as needed. For this, cell retention techniques available to date are presented, namely, cross‐flow filters, hollow fibers, controlled‐shear filters, vortex‐flow filters, spin‐filters, gravity settlers, centrifuges, acoustic settlers, and hydrocyclones. These retention techniques are compared and evaluated for their respective advantages and potential for large‐scale utilization in the context of industrial manufacturing processes. This analysis shows certain techniques have a limited range of perfusion rate where they can be implemented (most microfiltration techniques). On the other hand, techniques were identified that have shown high perfusion capacity (centrifuges and spin‐filters), or have a good potential for scale‐up (acoustic settlers and inclined settlers). The literature clearly shows that reasonable solutions exist to develop large‐scale perfusion processes. © 2003 Wiley Periodicals, Inc. Biotechol Bioeng 82: 751–765, 2003.
Effect of salts on lysozyme stability at the water–oil interface and upon encapsulation in poly(lactic‐co‐glycolic) acid microspheres
Authors: Pérez Caroline , Griebenow Kai
Published: April 2003

Encapsulation of proteins in poly(lactic‐co‐glycolic) acid (PLGA) microspheres by the water‐in‐oil‐in‐water (w/o/w) technique is very challenging because of the inherent physical instability of proteins. In particular, exposure of proteins to the first water‐in‐oil emulsion causes unwanted interface‐induced protein inactivation and aggregation. We tested whether salts could afford stabilization of a model protein, hen egg‐white lysozyme, against the detrimental events occurring at the w/o interface and subsequently upon w/o/w encapsulation. First, we investigated the effect of salts on the specific enzyme activity and generation of soluble precipitates and insoluble aggregates upon emulsification of an aqueous lysozyme solution with methylene chloride. It was found that lysozyme precipitation occurred upon emulsification. The amount of precipitate formed at salt concentrations between 10–100 mM was related to the position of the anion in the electroselectivity series (SO42− > SCN− > Cl− > H2PO4−) while high salt concentrations (1M) led to > 80% of lysozyme precipitation regardless of the salt. The precipitates consisted of buffer‐soluble protein precipitates and water‐insoluble noncovalent aggregates. Lysozyme precipitation, aggregation, and inactivation upon emulsification were largely prevented in the presence of 50 mM KH2PO4 while KSCN caused an increase in these detrimental events. Second, it was tested whether the improved structural integrity of lysozyme at the w/o interface would improve its stability upon w/o/w encapsulation in PLGA microspheres. Some conditions indeed led to improved stability, particularly codissolving lysozyme with 50 mM KH2PO4 reduced loss in the specific activity and aggregation. In conclusion, the type and concentration of salts is a critical parameter when encapsulating protein in PLGA microspheres. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 82: 825–832, 2003.
Development of apoptosis‐resistant dihydrofolate reductase‐deficient Chinese hamster ovary cell line
Authors: Lee Suk Kyoo , Lee Gyun Min
Published: April 2003

Apoptosis‐resistant dihydrofolate reductase‐deficient CHO cell line (dhfr− CHO‐bcl2) was developed by introduction of the bcl‐2 gene into the dhfr− CHO cell line (DUKX‐B11, ATCC CRL‐9096) and subsequent selection of clones stably overexpressing Bcl‐2 in the absence of selection pressure. When the dhfr− CHO‐bcl2 cell line was used as a host cell line for development of a recombinant CHO (rCHO) cell line expressing a humanized antibody, it displayed stable expression of the bcl‐2 gene during rCHO cell line development and no detrimental effect of Bcl‐2 overexpression on specific antibody productivity. Taken together, the results obtained demonstrate that the use of an apoptosis‐resistant dhfr− CHO cell line as the host cell line saves the effort of establishing an apoptosis‐resistant rCHO cell line and expedites the development process of apoptosis‐resistant rCHO cells producing therapeutic proteins. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 82: 872–876, 2003.
Flocculation behavior of Sphingobium chlorophenolicum in degrading pentachlorophenol at different life stages
Authors: Chang You‐Im , Su Chia‐Ying
Published: April 2003

The cell flocculation behavior of degrading pentachlorophenol (PCP) by using Sphingobium chlorophenolicum (Flavobacterium sp., ATCC 39723) is investigated in the present paper. It is found that these Sphingobium cells can efficiently degrade PCP when the concentration of this toxic compound is below 150 ppm. These degradation rates of PCP can be facilitated with the additions of three supplementary carbons: glutamate (4.0 g/L), glucose (3.2 g/L), and cellobiose (3.05 g/L), among which the highest specific growth rate of cells is obtained when glucose is added. More importantly, in these biodegradation experiments described herein, in order to investigate the cell flocculation behavior, the temporal variations of cell size, zeta potential, and stability ratio of the cell suspension are also measured. It is found that, no matter what kind of supplementary carbon source is added, the highest stability ratio of the cell suspension can be always obtained at the end of the exponential growth phase, which can be well explained by using the results of cell size and zeta potential measurements according to the DLVO theory. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 82: 843–850, 2003.
High level of expression of recombinant human granulocyte‐macrophage colony stimulating factor in transgenic rice cell suspension culture
Authors: Shin Yun‐Ji , Hong Shin‐Young , Kwon Tae‐Ho , Jang Yong‐Suk , Yang Moon‐Sik
Published: April 2003

Recombinant human granulocyte‐macrophage colony stimulating factor (hGM‐CSF) has been previously produced in tobacco cell suspension cultures. However, the amount of hGM‐CSF accumulated in the culture medium dropped quickly from its maximum of 150 μg/L at 5 d after incubation. To overcome this problem, we sought an expression system in which heterologous gene expression could be induced at high levels. We selected a rice amylase expression system in which the promoter Ramy3D is induced to express recombinant protein by sucrose starvation. This induction system was found to give good yield of recombinant hGM‐CSF in transgenic rice cell suspension culture and protease activity of this culture medium was low compared to that of tobacco culture system. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 82: 778–783, 2003.
Chemical biotechnology for the specific oxyfunctionalization of hydrocarbons on a technical scale
Authors: Bühler Bruno , Bollhalder Irene , Hauer Bernhard , Witholt Bernard , Schmid Andreas
Published: April 2003

Oxygenases catalyze, among other interesting reactions, highly selective hydrocarbon oxyfunctionalizations, which are important in industrial organic synthesis but difficult to achieve by chemical means. Many enzymatic oxygenations have been described, but few of these have been scaled up to industrial scales, due to the complexity of oxygenase based biocatalysts and demanding process implementation. We have combined recombinant whole‐cell catalysis in a two‐liquid phase system with fed‐batch cultivation in an optimized medium and developed an industrially feasible process for the kinetically controlled and complex multistep oxidation of pseudocumene to 3,4‐dimethylbenzaldehyde using the xylene monooxygenase of Pseudomonas putida mt‐2 in Escherichia coli. Successful scale up to 30 L working volume using downscaled industrial equipment allowed a productivity of 31 g L−1 d−1 and a product concentration of 37 g L−1. These performance characteristics meet present industry requirements. Product purification resulted in the recovery of 469 g of 3,4‐dimethyl‐ benzaldehyde at a purity of 97% and an overall yield of 65%. This process illustrates the general feasibility of industrial biocatalytic oxyfunctionalization. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 82: 833–842, 2003.
A novel pathway to enzyme deactivation: The cutinase model
Authors: Baptista R. P. , Chen L. Y. , Paixão A. , Cabral J. M. S. , Melo E. P.
Published: April 2003

Cutinase in aqueous solution at pH 4.5 deactivates following a parallel pathway. At 53°C, 88% of the cutinase molecules are in the unfolded conformation, which can aggregate with a reaction order of 3 if the protein concentration is high (≥12 μM). The aggregates show a sixfold increase in size as determined by dynamic light scattering. This aggregation process is the first phase observed during a deactivation experiment; however, after significant cutinase depletion and maturation of the aggregates, a first‐order step starts to dominate and a second phase independent of the protein concentration is observed. Kinetic partitioning between aggregation and first‐order irreversible changes of the unfolded conformation can occur during enzyme deactivation when the equilibrium between the native and the unfolded conformation is shifted and kept toward the unfolded conformation. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 82: 851–857, 2003.
Alternative Teacher Certification Programs and Texas Community Colleges
Authors: May Paul B. , Katsinas Stephen G. , Moore Lin
Published: April 2003

This chapter describes factors contributing to the successful planning and implementation of alternative teacher certification programs in one Texas community college district.
Accrediting Standards Affecting Mid‐Level Teacher Education Preparation in the Community College
Authors: Imig David G. , Harrill‐McClellan Mary
Published: April 2003

This chapter reviews the accrediting standards of the National Council for the Accreditation of Teacher Education and the Teacher Education Accreditation Council, assessess the ease or difficulty with which community colleges could meet the required standards, and suggests accreditation models appropriate for community colleges.
The Role of State Postsecondary Education Policy in Supporting Teacher Education at the Community College
Authors: Coulter Tricia , Crowe Edward
Published: April 2003

This chapter discusses the evolving role of the community college in teacher education from the standpoint of state policy issues.
Sources and information: Teacher education at community colleges
Authors: Gerdeman R. Dean
Published: April 2003

This concluding chapter describes resources related to teacher education at community colleges, including national perspectives, issue papers, examinations of student experiences, and literature summaries.
Taking the Golden State Path to Teacher Education: California Partnerships Among Two‐Year Colleges and University Centers
Authors: Serra Hagedorn Linda , Newman Fran , Duffy Janet
Published: April 2003

This chapter describes the current teacher credentialing situation in California, the community college Teacher and Reading Development Partnership (TRDP) program, and six California community college programs dedicated to the elimination of an acute teacher shortage.
Multi‐wavelength image space: another Grid‐enabled science
Authors: Williams Roy , Berriman Bruce , Deelman Ewa , Good John , Jacob Joseph , Kesselman Carl , Lonsdale Carol , Oliver Seb , Prince Thomas A.
Published: April 2003

We describe how the Grid enables new research possibilities in astronomy through multi‐wavelength images. To see sky images in the same pixel space, they must be projected to that space, a computer‐intensive process. There is thus a virtual data space induced that is defined by an image and the applied projection. This virtual data can be created and replicated with Planners and Replica catalog technology developed under the GriPhyN project. We plan to deploy our system (MONTAGE) on the U.S. Teragrid. Grid computing is also needed for ingesting data—computing background correction on each image—which forms a separate virtual data space. Multi‐wavelength images can be used for pushing source detection and statistics by an order of magnitude from current techniques; for optimization of multi‐wavelength image registration for detection and characterization of extended sources; and for detection of new classes of essentially multi‐wavelength astronomical phenomena. The paper discusses both the Grid architecture and the scientific goals. Copyright © 2003 John Wiley & Sons, Ltd.