bluuebunny/crossref_metadata_2025_split huggingface dataset:
Using statistical and contextual information to identify two‐ and three‐character words in Chinese text
Authors: Khoo Christopher S.G. , Dai Yubin , Ee Loh Teck 
Published: August 2002

AbstractNew statistical formulas were developed for identifying two‐ and three‐character words in Chinese text. The formulas were constructed by performing stepwise logistic regression using a sample of sentences that had been manually segmented. For identifying two‐character words, the relative frequency of the adjacent characters and the document frequency of the overlapping bigrams were found to be significant factors. These provide information about the immediate neighborhood or context of the character string. Contextual information was also found to be significant in predicting three‐character words. Local information (the number of times the bigram or trigram occurs in the document being segmented) and the position of the bigram/trigram in the sentence were not found to be useful in identifying words. The new formulas, called contextual information formulas, were found to be substantially better than the mutual information formula in identifying two‐ and three‐character words. Using the contextual information formulas for both two‐ and three‐character words gave significantly better results than using the formula for two‐character words alone. The method can also be used for identifying multiword terms in English text.
Brief exposure to a 50 Hz, 100 μT magnetic field: Effects on reaction time, accuracy, and recognition memory
Authors: Podd John , Abbott Jeana , Kazantzis Nikolaos , Rowland Al 
Published: August 2002

AbstractThe present study investigated both the direct and delayed effects of a 50 Hz, 100 μT magnetic field on human performance. Eighty subjects completed a visual duration discrimination task, half being exposed to the field and the other half sham exposed. The delayed effects of this field were also examined in a recognition memory task that followed immediately upon completion of the discrimination task, Unlike our earlier studies, we were unable to find any effects of the field on reaction time and accuracy in the visual discrimination task. However, the field had a delayed effect on memory, producing a decrement in recognition accuracy. We conclude that after many years of experimentation, finding a set of magnetic field parameters and human performance measures that reliably yield magnetic field effects is proving elusive. Yet the large number of significant findings suggests that further research is warranted. Bioelectromagnetics 23:189–195, 2002. © 2002 Wiley‐Liss, Inc.
Regulation of cell size in growth, development and human disease: PI3K, PKB and S6K
Authors: Kozma Sara C. , Thomas George 
Published: August 2002

AbstractIt has generally been observed that cells grow to a certain size before they divide. In the last few years, the PI3K signal transduction pathway has emerged as one of the main signaling routes utilized by cells to control their increase in size. Here we focus on two components of this pathway, PKB and S6K, and briefly review the experiments that initially uncovered their roles in cell size control. In addition, we discuss a number of recent observations suggesting that the generic models used to describe this pathway to date may have been oversimplified. Indeed, recent observations in Drosophila and mouse support a more complex interaction between these signaling components in development. Finally, we have utilized two contemporary studies involving PKB‐ and S6K‐deficient mice as a paradigm to underscore the importance of cell size and to accurately delineate the connections between signaling pathways for human disease, such as diabetes mellitus. BioEssays 24:65–71, 2002. © 2002 John Wiley & Sons, Inc.
Differential interactions of antitumor antibiotics chromomycin A3 and mithramycin with d(TATGCATA)2 in presence of Mg2+
Authors: Chakrabarti Sukanya , Mir Mohd. Ayoub , Dasgupta Dipak 
Published: August 2002

AbstractThe antitumor antibiotics chromomycin A3 (CHR) and mithramycin (MTR) are known to inhibit macromolecular biosynthesis by reversibly binding to double stranded DNA with a GC base specificity via the minor groove in the presence of a divalent cation such as Mg2+. Earlier reports from our laboratory showed that the antibiotics form two types of complexes with Mg2+: complex I with 1:1 stoichiometry and complex II with 2:1 stoichiometry in terms of the antibiotic and Mg2+. The binding potential of an octanucleotide, d(TATGCATA)2, which contains one potential site of association with the above complexes of the two antibiotics, was examined using spectroscopic techniques such as absorption, fluorescence, and circular dichroism. We also evaluated thermodynamic parameters for the interaction. In spite of the presence of two structural moieties of the antibiotic in complex II, a major characteristic feature was the association of a single ligand molecule per molecule of octameric duplex in all cases. This indicated that the modes of association for the two types of complexes with the oligomeric DNA were different. The association was dependent on the nature of the antibiotics. Spectroscopic characterization along with analysis of binding and thermodynamic parameters showed that differences in the mode of recognition by complexes I and II of the antibiotics with polymeric DNA existed at the oligomeric level. Analysis of the thermodynamic parameters led us to propose a partial accommodation of the ligand in the groove without the displacement of bound water molecules and supported earlier results on the DNA structural transition from B → A type geometry as an obligatory requirement for the accommodation of the bulkier complex II of the two drugs. The role of the carbohydrate moieties of the antibiotics in the DNA recognition process was indicated when we compared the DNA binding properties with the same type of Mg2+ complex for the two antibiotics. © 2001 John Wiley & Sons, Inc. Biopolymers (Biospectroscopy) 62: 131–140, 2001
Model peptide studies of sequence regions in the elastomeric biomineralization protein, Lustrin A. I. The C‐domain consensus—PG—, —NVNCT—motif
Authors: Zhang Bo , Wustman Brandon A. , Morse Daniel , Evans John Spencer 
Published: August 2002

AbstractThe lustrin superfamily represents a unique group of biomineralization proteins localized between layered aragonite mineral plates (i.e., nacre layer) in mollusk shell. Recent atomic force microscopy (AFM) pulling studies have demonstrated that the lustrin‐containing organic nacre layer in the abalone, Haliotis rufescens, exhibits a typical sawtooth force‐extension curve with hysteretic recovery. This force extension behavior is reminiscent of reversible unfolding and refolding in elastomeric proteins such as titin and tenascin. Since secondary structure plays an important role in force‐induced protein unfolding and refolding, the question is, What secondary structure(s) exist within the major domains of Lustrin A? Using a model peptide (FPGKNVNCTSGE) representing the 12‐residue consensus sequence found near the N‐termini of the first eight cysteine‐rich domains (C‐domains) within the Lustrin A protein, we employed CD, NMR spectroscopy, and simulated annealing/minimization to determine the secondary structure preferences for this sequence. At pH 7.4, we find that the 12‐mer sequence adopts a loop conformation, consisting of a “bend” or “turn” involving residues G3–K4 and N7–C8–T9, with extended conformations arising at F1–G3; K4–V6; T9–S10–G11 in the sequence. Minor pH‐dependent conformational effects were noted for this peptide; however, there is no evidence for a salt‐bridge interaction between the K4 and E12 side chains. The presence of a loop conformation within the highly conserved —PG—, —NVNCT— sequence of C1–C8 domains may have important structural and mechanistic implications for the Lustrin A protein with regard to elastic behavior. © 2002 Wiley Periodicals, Inc. Biopolymers 63: 358–369, 2002
Cation–π interaction in a folded polypeptide
Authors: Burghardt Thomas P. , Juranić Nenad , Macura Slobodan , Ajtai Katalin 
Published: August 2002

AbstractCationic and aromatic side chains from protein residues interact to stabilize tertiary structure. The stabilization energy originates in part from electrostatic attraction between the cation, and regions of high electron density in π‐orbitals of the aromatic group, leading to the name cation–π interaction. The lysine and tyrosine containing peptide, N–acetyl–Pro–Pro–Lys–Tyr–Asp–Lys–NH2, has near uv CD characteristic of tyrosine in a structured environment. Nuclear Overhauser effect (NOE), coupling constant, and ring current chemical shift constraints obtained with 1H NMR confirm that the peptide (t6p) folds. Simulated annealing consistent with all NMR constraints produces a 40‐structure ensemble for t6p with potential energies within one standard deviation of the lowest value observed. Calculated binding energies indicate that cation–π and cation–phenolic OH interactions exists between the Lys3 and Tyr4 side chains in most of the structures. The t6p peptide in solution is a model for these interactions in a protein. A perturbing electric field from the cationic ground state charge intermingles the excited states of the aromatic group. This intermingling effect may provide a cation–π signature effect in the tyrosine spectroscopy. The absorption and CD for the lowest energy electronic transitions of the tyrosine phenol were computed for the ensemble. Red‐shifted peak energy and hypochromicity in the absorbance band, and decreasing rotational strength, correlates with increasing binding energy of the complex indicating the cation–π spectroscopic signature. The ensemble average spectroscopic signature effects in t6p are small and in agreement with observation. © 2002 John Wiley & Sons, Inc. Biopolymers 63: 261–272, 2002; DOI 10.1002/bip.10070
Effects of humic substances on the bioavailability and aerobic biodegradation of polychlorinated biphenyls in a model soil
Authors: Fava Fabio , Piccolo Alessandro 
Published: August 2002

AbstractThe very high hydrophobicity of polychlorinated biphenyls (PCBs) strongly reduces their bioavailability in aged contaminated soils, thus limiting their bioremediation. The biodegradability of PCBs in heavily contaminated soils can be significantly enhanced by soil treatment with surface‐active agents. In this work, the effects of naturally occurring surfactants such as humic substances (HS) on the aerobic biodegradation of PCBs in a model soil were studied. The soil was amended with biphenyl (4 g/kg), Fenclor 42 (1,000 mg/kg), the aerobic PCB‐biodegrading bacterial co‐culture ECO3 (inoculum: 108CFU/mL), and treated in aerobic batch slurry‐phase conditions (17.5% w/v) with and without the addition of HS at the rates of 1.5 and 3.0% (w/w). Low PCBs biodegradation and dechlorination yields were observed in the HS‐free microcosms, probably as a result of the rapid disappearance of inoculated bacteria. The presence of HS influenced significantly the activity of the specialized biomass and the biodegradation of PCBs in the microcosms. The microcosms that received HS at the 1.5% rate showed a higher persistence of the specialized bacteria and yields of PCB biodegradation and dechlorination about 150 and 100%, respectively, larger than those found for the HS‐free microcosms. Lower stimulating effects were observed in the microcosms added with the HS at 3.0% rate. These effects were attributed to an increased solubilization of PCBs in the hydrophobic domains of the humic supramolecular associations and to a different accessibility of PCBs by the specialized bacteria at the different rates of HS addition. Although the slurry‐phase treatment generally showed a decrease of the original soil ecotoxicity, the addition of the originally non‐toxic HS decreased soil ecotoxicity for the Collembola animal biomarker and increased that towards the Lepidium sativum vegetal biomarker. © 2002 John Wiley & Sons, Inc. Biotechnol Bioeng 77: 204–211, 2002.
Purification of recombinant cutinase by extraction in an aqueous two‐phase system facilitated by a fatty acid substrate
Authors: Fernandes Sheryl , Johansson Göte , Hatti‐Kaul Rajni 
Published: August 2002

AbstractPurification of recombinant wild‐type cutinase from the culture supernatant of Saccharomyces cerevisiae by extraction in aqueous two‐phase system was investigated. The partition of the enzyme in a polyethylene glycol (PEG)–potassium phosphate system to the top phase was increased with lower molecular weight PEG. Enzyme partition in a 20% PEG/15% phosphate two‐phase system was studied in the presence of detergents, fatty acids, and alcohols, respectively. Addition of 0.5% (w/w) butyrate increased the partition coefficient from 17 to 135 and the purification factor from 10 to 23. The effect of butyrate was also confirmed by using the countercurrent mode of extraction. Recovery of cutinase from the top phase was achieved by a secondary extraction into a new salt phase at a lower pH or a lower temperature. A specific interaction of butyrate to the active site of the enzyme was demonstrated by fluorescence spectroscopy. Size exclusion chromatography showed the cutinase–butyrate complex to be over two times the size of the free enzyme. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 73: 465–475, 2001.
Multivariable control of alcohol concentrations in the production of polyhydroxyalkanoates (PHAs) by Paracoccus denitrificans
Authors: Chanprateep Suchada , Abe Naoya , Shimizu Hiroshi , Yamane Tsuneo , Shioya Suteaki 
Published: August 2002

AbstractA novel multivariable control strategy is developed for alcohol (ethanol and n‐pentanol) concentrations in the production of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate), P(HB‐co‐HV), a biodegradable polymer by Paracoccus denitrificans ATCC 1774. This controller, which is developed to control the mole fraction of P(HB‐co‐HV), consists of two parts: one is for ethanol concentration control and the other is for mole fraction control, based on the concept of metabolic flux distribution control. A simple metabolic reaction (MR) model is constructed for flux distribution analysis. The relationship between mole ratio of specific consumption rate of the two alcohols (ethanol and n‐pentanol) and the mole fraction of 3HV units in the polymer is linear. This result suggests that the split ratio at a branched point of 3‐ketovaleryl‐CoA in the P(HB‐co‐HV) synthetic pathway is constant for several fermentation conditions. When the mole fraction of 3HV units has a target value, the feed rate of n‐pentanol becomes a function of the feed rate of ethanol and the set value of 3HV, based on the MR model. The mole fraction of 3HV units successfully reached the target value using this strategy. The mole fraction control strategy is combined with an optimal production strategy based on the optimal profile of the specific growth rate. The combined strategy is realized using multivariable controllers and P(3HB‐co‐3HV) production is maximized with a given value of mole fraction of 3HV units at the final step of fermentation. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 74: 116–124, 2001.
Influence of the ethanol and glucose supply rate on the rate and enantioselectivity of 3‐oxo ester reduction by baker's yeast
Authors: Chin‐Joe Ifoeng , Straathof Adrie J. J. , Pronk Jack T. , Jongejan Jaap A. , Heijnen Joseph J. 
Published: August 2002

AbstractBaker's‐yeast‐mediated reductions of ketones hold great potential for the industrial production of enantiopure alcohols. In this article we describe the stoichiometry and kinetics of asymmetric ketone reduction by cell suspensions of bakers’ yeast (Saccharomyces cerevisiae). A system for quantitative analysis of 3‐oxo ester reduction was developed and allowed construction of full mass and redox balances as well as determination of the influence of different process parameters on aerobic ketone reduction. The nature of the electron donor (ethanol or glucose) and its specific consumption rate by the biomass (0–1 mol.kg dw−1.h−1) affected the overall stoichiometry and rate of the process and the final enantiomeric excess of the product. Excess glucose as the electron donor, i.e. a very high consumption rate of glucose, resulted in a high rate of alcoholic fermentation, oxygen consumption, and biomass formation and therefore causing low efficiency of glucose utilization. Controlled supply of the electron donor at the highest rates applied prevented alcoholic fermentation but still resulted in biomass formation and a high oxygen requirement, while low rates resulted in a more efficient use of the electron donor. Low supply rates of ethanol resulted in biomass decrease while low supply rates of glucose provided the most efficient strategy for electron donor provision and yielded a high enantiomeric excess of ethyl (S)‐3‐hydroxybutanoate. In contrast to batchwise conversions with excess glucose as the electron donor, this strategy prevented by‐product formation and biomass increase, and resulted in a low oxygen requirement. © 2001 John Wiley & Sons, Inc. Biotechnol Bioeng 75: 29–38, 2001.
Juvenile curfews: are they an effective and constitutional means of combating juvenile violence?*
Authors: Fried Carrie S. 
Published: August 2002

AbstractCurfew ordinances have become a popular way to attempt to combat juvenile crime and victimization. Although the Supreme Court has yet to hear a curfew case, several constitutional challenges have been brought in lower federal courts. The cases are replete with psychological assumptions for which there is limited empirical evidence. In applying the “strict scrutiny” standard, several courts have also questioned whether juvenile curfews are narrowly tailored to further the State's interest in reducing juvenile crime and victimization. While public opinion and reports from several police jurisdictions support the utility of juvenile curfews, recent empirical studies indicate that curfews are not effective at reducing juvenile offending or victimization. This paper argues that the emerging evidence does not support the use of juvenile curfews and urges policy makers and the courts to examine the efficacy of curfew legislation. Directions for future research that could be helpful to the courts in applying the Bellotti factors to curfew cases are also suggested. Copyright © 2001 John Wiley & Sons, Ltd.
New methods for the isolation of skeletal muscle sarcolemma and sarcoplasmic reticulum allowing a comparison between the mammalian and amphibian β2‐adrenergic receptors and calcium pumps
Authors: Hemmings Susan J. 
Published: August 2002

AbstractNew methods were established for the rapid and simultaneous isolation of multiple sarcolemmal and sarcoplasmic reticular fractions from very small amounts (0.25–2.0 g) of skeletal muscle. Theβ2‐adrenergic receptor and calcium transport systems were used as indices of purity and functional integrity as well as being the focal points of the study. These methods were found to be suitable for the special needs of small tissue samples, allowed rapid preparation and were appropriate for skeletal muscle from various species, frogs to mammals. The sarcolemmalβ2‐adrenergic receptor was expressed in frogs and mammals at similar levels of expression (336–454 fmol·mg−1). The calcium pump was also present in sarcolemmal and sarcoplasmic reticular fractions in all species but notable species differences were found. In sarcolemmal fractions, while calcium binding was uniformly low (<1 nmol·mg−1), oxalate stimulation was variable: low in frogs (∼1.05‐fold) high in mammals (120–450‐fold). In sarcoplasmic reticular fractions, calcium binding was low in frogs (4–9 nmol·mg−1) and much higher in mammals (322–383 nmol·mg−1); oxalate stimulated calcium transport to a much greater extent in frogs (<70‐fold) than in mammals (1.6–2‐fold). It is concluded that theβ2‐adrenergic receptor appears to be strongly conserved in skeletal muscle while the use of calcium pumps evolves from reliance in Amphibia on the sarcoplasmic reticular calcium pump to the use in Mammalia of calcium pumps from both the sarcoplasmic reticulum and the plasma membrane. Copyright © 2001 John Wiley & Sons, Ltd.
Stent implantation for superior vena cava occlusion after the mustard operation
Authors: Mohsen Aly El , Rosenthal Eric , Qureshi Shakeel A. , Tynan Michael 
Published: August 2002

AbstractA 25‐year‐old man who had undergone a Mustard repair for complete transposition of the great arteries 21 years previously developed complete occlusion of the superior vena cava and obstruction of the inferior vena cava. Transcatheter recanalization was performed using needle puncture of the superior obstruction followed by stent implantation into both systemic venous pathways with relief of obstructive symptoms. Cathet Cardiovasc Intervent 2001;52:351–354. © 2001 Wiley‐Liss, Inc.
Yb(fod)3 in the spectroscopic determination of the configuration of chiral diols: A survey of the lanthanide diketonate method
Authors: Di Bari Lorenzo , Lelli Moreno , Pintacuda Guido , Salvadori Piero 
Published: August 2002

AbstractA modification of the diketonate method for the determination of the absolute configuration of chiral vicinal diols, first proposed by Nakanishi, is taken under object and tested with a set of aliphatic and aromatic substrates; Yb(fod)3 (fod = 6,6,7,7,8,8,8‐heptafluoro‐2,2‐dimethyl‐3,5‐octanedionate) is employed as the chromophoric species. The replacement of dpm (dpm = dipivalomethanate) with fod ensures the formation of strong and stable signals in the UV region, whose signs are related to the configuration of the chelating molecule. The choice of ytterbium as the central cation introduces two major advantages: the electronic f–f transition of the rare‐earth supplies a second spectral window in the near‐IR, which is sensitive to the chemical environment around the atom. This allowed us to ascertain the number of different species present in solution and the observation of an induced CD also for strongly UV‐absorbing substrates. The pseudocontact shifts induced in the 1H‐NMR spectrum by the unpaired electron of the lanthanide ion provide valuable structural information on the adducts. Chirality 14:265–273, 2002. © 2002 Wiley‐Liss, Inc.