bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermally treated low density polyethylene biodegradation by Penicillium pinophilum and Aspergillus niger
Authors: Volke‐Sepúlveda T. , Saucedo‐Castañeda G. , Gutiérrez‐Rojas M. , Manzur A. , Favela‐Torres E. 
Published: August 2002

AbstractDifferential scanning calorimetry (DSC), X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to determine morphological, structural and surface changes (biodegradation) on thermo‐oxidized (80°C, 15 days) low‐density polyethylene (TO‐LDPE) incubated with Aspergillus niger and Penicillium pinophilum fungi, with and without ethanol as cosubstrate for 31 months. TO‐LDPE mineralization by fungi was also evaluated. Significantly morphological and structural final changes on biologically treated TO‐LDPE samples were observed. Decreases to three units on crystallinity and crystalline lamellar thickness (0.4–1.8 Å), and increases in small‐crystals content (up to 3.2%) and mean crystallite size (8.4–14 Å) were registered. An oxidation decrease (almost twice) on samples without ethanol with respect to the control was observed, while in those with ethanol it was increased (up to 2.5 times). Double bond index increased more than twice from 21 to 31 months. The higher TO‐LDPE changes and fungi‐LDPE interaction was observed in samples with ethanol, suggesting that ethanol favors the TO‐LDPE biodegradation, at least in case of P. pinophilum, probably by means of a cometabolic process. Mineralization of 0.50 % and 0.57 % for A. niger, and of 0.64 % and 0.37 % for P. pinophilum were obtained, for samples with and without ethanol, respectively. A model to explain morphological and structural changes on biologically treated TO‐LDPE is also proposed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 305–314, 2002
A mucoadhesive polymer prepared by template polymerization of acrylic acid in the presence of poly(ethylene glycol) macromer
Authors: Chun Myung‐Kwan , Choi Hoo‐Kyun , Kang Dong‐Wan , Kim Oh‐Joong , Cho Chong‐Su 
Published: August 2002

AbstractA new mucoadhesive polymer complex was prepared by the template polymerization of acrylic acid with poly(ethylene glycol) macromer (PEGM) as a template polymer. Fourier transform infrared results showed that the poly(acrylic acid) (PAA)/PEGM mucoadhesive polymer complex was formed by hydrogen bonding between the carboxyl groups of PAA and the ether groups of PEGM. The glass‐transition temperature of the PAA/PEGM mucoadhesive polymer complexes was shifted to a lower temperature as the repeating unit ratio of PAA/PEGM in the complex decreased. The dissolution rate of the PAA/PEGM mucoadhesive polymer complex was much slower than that of the PAA/poly(ethylene glycol) (PEG) mucoadhesive polymer complex and was dependent on the pH and molecular weight of PEGM. The mucoadhesive force of the PAA/PEGM mucoadhesive polymer complexes was stronger than that of commercial Carbopol 971P NF and almost the same as that of the PAA/PEG mucoadhesive polymer complex. The PAA/PEGM interpolymer complex seemed to be a better mucoadhesive polymer matrix than the PAA/PEG interpolymer complex. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1904–1910, 2002
Effects of aging and moisture on the dynamic viscoelastic properties of oriental lacquer (urushi) film
Authors: Obataya Eiichi , Furuta Yuhzo , Ohno Yoshitaka , Norimoto Misato , Tomita Bunichiro 
Published: August 2002

AbstractThe effects of aging and moisture on the dynamic viscoelastic properties of three oriental lacquer films were investigated. With aging over 1000 days at room temperature, the glass‐transition temperature of the lacquer films (Tα) shifted to higher temperatures, the maximum loss tangent (tanδα) decreased, and the storage modulus at 20°C (E) increased. These changes were analogous irrespective of lacquers. With increasing moisture content, E decreased and tanδ increased at room temperature. Although the equilibrium moisture content of the virgin lacquer (sap) film was higher than that of the clear lacquer film, its E and tanδ were more stable with an increase of moisture content. It was speculated that the polysaccharides aggregated in the sap film did not effectively contribute to the mechanical properties of the film, while their hygroscopicity resulted in higher moisture content. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2288–2294, 2002
Cognitive and task influences on Web searching behavior
Authors: Kim Kyung‐Sun , Allen Bryce 
Published: August 2002

AbstractUsers' individual differences and tasks are important factors that influence the use of information systems. Two independent investigations were conducted to study the impact of differences in users' cognition and search tasks on Web search activities and outcomes. Strong task effects were found on search activities and outcomes, whereas interactions between cognitive and task variables were found on search activities only. These results imply that the flexibility of the Web and Web search engines allows different users to complete different search tasks successfully. However, the search techniques used and the efficiency of the searches appear to depend on how well the individual searcher fits with the specific task.
Studies of the interactions between melatonin and 2 Hz, 0.3 mT PEMF on the proliferation and invasion of human breast cancer cells
Authors: Leman Eddy S. , Sisken Betty F. , Zimmer Stephen , Anderson Kimberly W. 
Published: August 2002

AbstractInteractions between the hormone melatonin at pharmacological concentrations (10−3 M) and 2 Hz, 0.3 mT pulsed electromagnetic fields (PEMF) on the proliferation and invasion of human breast cancer cells were studied in vitro. Three types of human breast cancer cells were used in this study: MDA‐MB‐435, MDA‐MB‐231, and MCF‐7. Results showed that cellular growth of MDA‐MB‐231 cells, which were reported to be lowly metastatic, and MCF‐7 cells, which were reported to be nonmetastatic, were both significantly reduced by melatonin regardless of the presence of the field. Results also showed that MDA‐MB‐435 and MDA‐MB‐231 cells were invasive, with MDA‐MB‐231 cells being more invasive than the MDA‐MB‐435 cells for both unexposed and experimental‐PEMF groups. In addition, invasion studies showed that MCF‐7 cells were not invasive and that melatonin did not have any effects on the invasion of these cells, with or without the PEMF. It is also suggested that since metastasis requires growth and invasion into tissue, anti‐invasion agents can be used in conjunction with melatonin to prevent formation of secondary metastases. The overall studies suggest that PEMF at 2 Hz, 0.3 mT does not influence cancer metastasis; while having clinical merit in the healing of soft tissue injury, this field has shown no influence on cancer cells as 60 Hz power line fields have. Bioelectromagnetics 22:178–184, 2001. © 2001 Wiley‐Liss, Inc.
Dielectric response of some biological tissues
Authors: El‐Lakkani Ali 
Published: August 2002

AbstractThe dielectric properties of two freshly excised mice tissue samples (kidney, skeletal muscle) and also freshly excised Ehrlich solid tumor were measured in the frequency range from 20 Hz to 100 kHz using RLC bridges. The data were fitted to a summation of multiple Cole–Cole dispersion and also to the constant power law which is related formally to the fractal geometries of tissues using a genetic algorithm for optimization developed by the author. The data were in good agreement with the Cole–Cole equation for the three samples. Bioelectromagnetics 22:272–279, 2001. © 2001 Wiley‐Liss, Inc.
Basis for optimization of in vitro exposure apparatus for health hazard evaluations of mobile communications
Authors: Schönborn Frank , Poković Katja , Burkhardt Michael , Kuster Niels 
Published: August 2002

AbstractThe main objective of this paper is to carefully study the fields induced in flasks exposed to RF electromagnetic fields. The study focuses on the widely used 60 mm Petri dishes and rectangular T‐75 flasks for the two following cases: 1) cells in homogeneous suspension and 2) cell monolayers. The dependence of the coupling and the homogeneity of the SAR distribution on frequency (0.7 GHz to 2.5 GHz), polarization (E, H and k polarizations) and the amount of medium (1.9 mm to 4.7 mm medium height) is studied. In addition, the effects of the environment, meniscus and field impedance as well as the distortion of the incident field are discussed. Based on these results, advantages and disadvantages of different fundamental designs of apparatus used in the past are compared. These are TEM cells, HF chambers, radial transmission lines (RTL), waveguides and wire patch cells. Furthermore, the major optimization parameters are identified for the development of highly optimized exposure systems, enabling the conduct of high quality experiments. Bioelectromagnetics 22:547–559, 2001. © 2001 Wiley‐Liss, Inc.
Raman spectroscopy study of acid–base and structural properties of 9‐[2‐(phosphonomethoxy)ethyl]adenine in aqueous solutions
Authors: Kopecký Vladimír , Mojzeš Peter , Burda Jaroslav V. , Dostál Lubomír 
Published: August 2002

AbstractThe acid–base properties of the acyclic antiviral nucleotide analogue 9‐ [2‐(phosphonomethoxy)ethyl] adenine (PMEA) in aqueous solutions are studied by means of Raman spectroscopy in a pH range of 1–11 and compared with the properties of its common adenosine monophosphate counterparts (5′‐AMP, 3′‐AMP, and 2′‐AMP). Factor analysis is used to separate the spectra of pure ionic species (PMEA2−, HPMEA−, H2PMEA, H3PMEA+) in order to determine their abundance, sites of protonation, and corresponding spectroscopic pKa values. The characteristic Raman features of the neutral adenine moiety in PMEA2− and HPMEA− species resemble those of neutral adenine in the AMPs, whereas significant differences are observed between the Raman spectra of the N1‐protonated adenine of the solute zwitterionic H2PMEA and its N1‐protonated AMP counterparts. On the contrary, the spectrum of crystalline H2PMEA, adopting an “anti‐like” conformation, is found to be similar to the N1‐protonated AMPs in solution. To explain peculiar Raman features a “syn‐like” conformation is suggested for N1‐protonated PMEA species in aqueous solutions instead of an anti‐like one adopted by H2PMEA in crystals or by common AMPs in aqueous solutions. A physical mechanism of the anti‐like to syn‐like conformational transition of the solute PMEA that is due to adenine protonation and the flexibility of the (phosphonomethoxy)ethyl group is proposed and discussed. © 2002 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 67: 285–288, 2002
FTIR study of five complex β‐lactam molecules
Authors: Gil Manuel , Núñez José Luís , Palafox Mauricio Alcolea , Iza Nerea 
Published: August 2002

AbstractFive monocyclic 4‐benzoyl‐4‐phenyl‐β‐lactam derivatives in carbon tetrachloride solutions were studied by FTIR spectroscopy. The Fourier self‐deconvolution method was applied to enhance the resolution of the FTIR spectra. The calculated spectra of these five compounds, which were obtained by quantum mechanical methods, were compared with FTIR data. A complete assignment of the vibrational frequencies in the 4000–400 cm−1 range was made. Several vibrations were selected as being useful to characterize the β‐lactam ring. Substituents on N1 (p‐methoxyphenyl) and C3 (methyl, phenyl, maleimidyl, and phthalimidyl) on the β‐lactam ring increase the amide resonance and the planarity of the ring. The optimized geometry along with the total electric charges on the four atoms of the ring support an antibiotic action mechanism by a nucleophilic attack of the enzymes on the carbonyl carbon atom of the β‐lactam ring. © 2001 John Wiley & Sons, Inc. Biopolymers (Biospectroscopy) 62: 278–294, 2001
On‐line estimation of the metabolic burden resulting from the synthesis of plasmid‐encoded and heat‐shock proteins by monitoring respiratory energy generation
Authors: Hoffmann Frank , Rinas Ursula 
Published: August 2002

AbstractHuman basic fibroblast growth factor (hFGF‐2) was produced in high‐cell density cultures of recombinant Escherichia coli using a temperature‐inducible expression system. The synthesis rates of proteins were followed by two‐dimensional gel electrophoresis of the 35S‐methionine‐labeled proteom. After temperature induction of hFGF‐2 synthesis, the rate of total protein synthesis per biomass increased by a factor of three, mainly as a result of the additional synthesis of hFGF‐2 and heat‐shock proteins. The synthesis rates of heat‐shock proteins and constitutive plasmid‐encoded proteins increased after the temperature upshift also in the control strain without hFGF‐2 gene but followed time profiles different from the producing strain. The energy demand for the extra synthesis of plasmid‐encoded and heat‐shock proteins resulted in an elevated respiratory activity and, consequently, in a reduction of the growth rate and the biomass yield. A procedure was developed to relate the energy demand for the additional synthesis of these proteins to the generation of energy in the respiratory pathway. Specific energy production was estimated based on on‐line measurable rates of oxygen consumption, or carbondioxide evolution and growth, respectively. In this way, the metabolic burden resulting from the synthesis of plasmid‐encoded and heat‐shock proteins was quantified from on‐line accessible data. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 76: 333–340, 2001.
Direct transesterification of gases by “dry” immobilized lipase
Authors: Cameron Paula A. , Davison Brian H. , Frymier Paul D. , Barton John W. 
Published: August 2002

AbstractSeveral different reactor configurations, including single pass, continuous recycle, and batch reactor modes, were used to investigate the effects of temperature and water activity, or relative humidity, on lipase‐catalyzed, gas‐phase transesterifications. Temperature and relative humidity were controlled both inside reactors and throughout the course of the reaction to account for and optimize their effects. Results indicated that, at low relative humidity, reaction rates increased with temperature up to 60°C. However, when relative humidity was increased, a similar increase in temperature resulted in the loss of nearly all enzyme activity. These results are consistent with the idea that enzymes without free water are more thermally stable. Furthermore, at constant ambient temperatures, production increased dramatically with an increase in relative humidity, confirming the idea that an increase in water activity increases catalytic activity. A mass balance performed on reactors at higher relative humidity revealed that hydrolysis (rather than transesterification) of the ester substrate could significantly decrease product yields. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 78: 251–256, 2002.
Fast and efficient alkaline peroxide treatment to enhance the enzymatic digestibility of steam‐exploded softwood substrates
Authors: Yang Bin , Boussaid Abdel , Mansfield Shawn D. , Gregg David J. , Saddler John N. 
Published: August 2002

AbstractThe enzymatic digestibility of steam‐exploded Douglas‐fir wood chips (steam exploded at 195°C, 4.5 min, and 4.5% (w/w) SO2) was significantly improved using an optimized alkaline peroxide treatment. Best hydrolysis yields were attained when the steam‐exploded material was post‐treated with 1% hydrogen peroxide at pH 11.5 and 80°C for 45 min. This alkaline peroxide treatment was applied directly to the water‐washed, steam‐exploded material eliminating the need for independent alkali treatment with 0.4% NaOH, which has been traditionally used to post‐treat wood samples to try to remove residual lignin. Approximately 90% of the lignin in the original wood was solubilized by this novel procedure, leaving a cellulose‐rich residue that was completely hydrolyzed within 48 h, using an enzyme loading of 10 FPU/g cellulose. About 82% of the originally available polysaccharide components of the wood could be recovered. The 18% of the carbohydrate that was not recovered was lost primarily to sugar degradation during steam explosion. © 2002 John Wiley & Sons, Inc. Biotechnol Bioeng 77: 678–684, 2002; DOI 10.1002/bit.10159
A metabolic model for acetate uptake under anaerobic conditions by glycogen accumulating organisms: Stoichiometry, kinetics, and the effect of pH
Authors: Filipe Carlos D. M. , Daigger Glen T. , Grady C. P. Leslie 
Published: August 2002

AbstractA metabolic model for the stoichiometry of acetate uptake under anaerobic conditions by an enriched culture of glycogen accumulating organisms (GAOs) was developed and tested by experimental studies. Glycogen served as the source of both reducing power and energy to drive the process of acetate uptake. The amount of glycogen consumed and poly‐β‐hydroxyvalerate (PHV) accumulated in the cells increased with increasing pH, indicating that the energy requirements for acetate uptake increased with pH. The composition of the accumulated poly‐β‐hydroxyalkanoates (PHAs) was adequately predicted using the assumption that acetyl‐CoA and propionyl‐CoA condense randomly to produce PHA. In addition, the rate of acetate uptake was strongly affected by the pH. The rate decreased with increasing pH and this dependence could be described with a saturation type of expression. A comparison of the rate of acetate uptake at low pH with the rates observed in enriched cultures of phosphorus accumulating organisms (PAOs) indicated that GAOs are able to compete effectively with PAOs in nutrient removal systems under certain conditions. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 76: 17–31, 2001.
Evolution of a recombinant (gucoamylase‐producing) strain of Fusarium venenatum A3/5 in chemostat culture
Authors: Wiebe Marilyn G. , Robson Geoffrey D. , Shuster Jeff , Trinci Anthony P.J. 
Published: August 2002

AbstractFusarium venenatum JeRS 325 is a transformant of strain A3/5 which produces Aspergillus niger glucoamylase (GAM) under the control of a Fusarium oxysporum trypsin‐like protease promoter. The evolution of JeRS 325 was studied in glucose‐limited chemostat cultures grown on NaNO3 or (NH4)2SO4 as the nitrogen source. Thirteen mutants which were more highly branched and four mutants which were more sparsely branched than the parental strain were isolated from the NaNO3 chemostat. The highly branched mutants detected in this chemostat did not displace the sparsely branched population. The mutants isolated from the NaNO3 chemostat complemented representative strains previously isolated from glucose‐limited chemostat cultures of F. venenatum A3/5 grown on (NH4)2SO4, but showed little complementation between themselves. By contrast, a highly branched mutant isolated from the (NH4)2SO4 chemostat culture displaced the sparsely branched mycelial population. None of the mutants isolated from the NaNO3 or (NH4)2SO4 chemostats produced as much GAM as JeRS 325. Southern blot analysis showed that all except one mutant had lost copies of both the glucoamylase and the acetamidase (the selectable marker) genes. However, specific GAM production was not necessarily correlated with the extent of glaA gene loss observed. Further, 10 of the mutants had lost the ability to grow on acetamide as the sole nitrogen source, although they retained copies of the amdS gene. In competition studies, mutants which could not utilize acetamide displaced mutants which could. The presence of foreign DNA in JeRS 325 resulted in a reduced specific growth rate (compared to A3/5), but the presence of the foreign DNA did not prevent the evolution of the strain or the isolation of mutants which had improved growth rates. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 73: 146–156, 2001.
Efficient polycyclic aromatic hydrocarbons dihydroxylation in direct micellar systems
Authors: Randazzo Demetrio , Berti Debora , Briganti Fabrizio , Baglioni Piero , Scozzafava Andrea , Di Gennaro Patrizia , Galli Enrica , Bestetti Giuseppina 
Published: August 2002

AbstractOptimization of whole‐cell bioconversion of the polycyclic aromatic hydrocarbons (PAHs) anthracene, phenanthrene, and naphthalene to the enantiomerically pure corresponding cis‐dihydroxydihydro derivatives by the Escherichia coli JM109 (pPS1778) recombinant strain, carrying the naphthalene dioxygenase and corresponding regulatory genes cloned from Pseudomonas fluorescens N3, in micellar systems, is presented. We show that direct microemulsion systems, where a nonionic surfactant such as 1.5% (v/v) Triton X‐100 plus 0.6% to 1.0% (v/v) selected oils are able to solubilize the PAHs tested at relatively high concentrations (initial concentrations in the reaction medium ≥10 mM for naphthalene and phenanthrene and ≥2 mM for anthracene), and allow for more efficient substrate bioconversion. These media, while not affecting bacteria viability and performance, provide increased efficiency and final product yields (100% for naphthalene, >30% for anthracene, >60% for phenanthrene). The phase behavior of the direct microemulsion systems for the different substrates and oils utilized was monitored as a function of their volume fraction by light scattering experiments, and related to the bioconversion results. For anthracene and phenanthrene, the dihydroxylated products have an inhibitory effect on the conversion reactions, thus hindering complete turnover of the substrates. We ascertain that such inhibition is reversible because removal of the products formed allowed the process to start over at rates comparable to initial rates. To allow for complete conversion of the PAHs tested a stepwise or continuous separation of the product formed from the micellar reaction environment is being developed. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 74: 240–248, 2001.
Capillary isoelectric focusing–mass spectrometry: analysis of protein mixtures from human body fluids
Authors: Clarke Nigel J. , Naylor Stephen 
Published: August 2002

AbstractIsoelectric focusing within a fused silica capillary (cIEF) has proved to be a powerful and practical method for high‐resolution separation of analytes from complex biological mixtures. This technique overcomes many of the problems of isoelectric focusing within slab gel media. However current cIEF systems commonly utilize UV detection which limits the detail of analyte structural information that is obtained during analysis. The use of mass spectrometry (MS) as the detection system provides much greater structural information about the detected analytes allowing accurate relative molecular mass (Mr) determination for proteins and polypeptides. We have constructed a cIEF‐MS interface and compared the separation of standard proteins analyzed by cIEF‐UV with cIEF‐MS. This allowed rapid optimization of the cIEF‐MS system performance. Further we have demonstrated the use of MS as a detection system provides accurate Mr information and can provide analyte modification details. These factors increase the likelihood of absolute identification for physiological proteins within complex in vivo‐derived mixtures. To demonstrate the value of cIEF‐MS in such analyses we have undertaken an examination of cerebrospinal fluid (CSF), and tentatively identified a number of constituent proteins. We have also analyzed whole blood from control and diabetic patients. We show that glycated α‐ and β‐ chains of hemoglobin are found in almost equal abundance in diabetic patient blood. From these results we suggest cIEF‐MS is an efficient and useful tool for the separation and examination of in vivo‐derived analytes within physiological fluids. Copyright © 2002 John Wiley & Sons, Ltd.