bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fiber diameter of polybutylene terephthalate melt‐blown nonwovens
Authors: Chen Ting , Li Liqing , Huang Xiubao 
Published: May 2005

AbstractA polymer air‐drawing model of Polybutylene Terephthalate (PBT) melt‐blown nonwovens has been established. The predicted fiber diameter coincides with the experimental data. The effects of the processing parameters on the fiber diameter have been investigated. A lower polymer flow rate, a higher initial air velocity, and a larger die‐to‐collector distance can all produce finer fibers, whereas too high an initial air velocity and too large a die‐to‐collector distance contribute little to the polymer drawing of PBT melt‐blown nonwovens. The results show the great potential of this research for the computer‐assisted design of melt‐blowing technology. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1750–1752, 2005
Web citation data for impact assessment: A comparison of four science disciplines
Authors: Vaughan Liwen , Shaw Debora 
Published: May 2005

AbstractThe number and type of Web citations to journal articles in four areas of science are examined: biology, genetics, medicine, and multidisciplinary sciences. For a sample of 5,972 articles published in 114 journals, the median Web citation counts per journal article range from 6.2 in medicine to 10.4 in genetics. About 30% of Web citations in each area indicate intellectual impact (citations from articles or class readings, in contrast to citations from bibliographic services or the author's or journal's home page). Journals receiving more Web citations also have higher percentages of citations indicating intellectual impact. There is significant correlation between the number of citations reported in the databases from the Institute for Scientific Information (ISI, now Thomson Scientific) and the number of citations retrieved using the Google search engine (Web citations). The correlation is much weaker for journals published outside the United Kingdom or United States and for multidisciplinary journals. Web citation numbers are higher than ISI citation counts, suggesting that Web searches might be conducted for an earlier or a more fine‐grained assessment of an article's impact. The Web‐evident impact of non‐UK/USA publications might provide a balance to the geographic or cultural biases observed in ISI's data, although the stability of Web citation counts is debatable.
Green flavoprotein from P. leiognathi: Purification, characterization and identification as the product of the lux G(N) gene
Authors: Raibekas Andrei A. 
Published: May 2005

AbstractA green flavoprotein (GFP) was isolated and purified to homogeneity from Photobacterium leiognathi, strain 208. GFP is a homodimer of molecular weight 54000 and contains two molecules of an unusual flavin per molecule of protein. Various biochemical characteristics including isoelectric point, trypsin and chymotrypsin degradation, SDS and temperature influence on subunit dissociation and the dissociation of the flavin chromophore, were investigated. The sequence of 23 N‐terminal amino acids was determined and found to be concurrent with the N‐terminal amino acids was determined and found to be concurrent with the N‐terminal amino acid sequence encoded by the lux G (N) gene of P. leiognathi. This fact suggests that GFP is a structural component of the Photobacterium luminescence system.
Extra‐weak chemiluminescence of drugs. XII. Effect of the molar ratio of amino acid to sugar on extra‐weak chemiluminescence in the Maillard reaction
Authors: Kurosaki Yuichiro , Sato Hideaki , Ishizawa Fumiaki , Mizugaki Michinao 
Published: May 2005

AbstractThe extra‐weak chemiluminescence in the Maillard reaction caused by the reaction between L‐lysine and D‐arabinose was measured, and a linear relationship was found between the chemiluminescence and the amount of L‐lysine added. After a 1‐hour reaction equimolar amounts of D‐arabinose and L‐lysine were consumed regardless of the initial concentration of D‐arabinose. The chemiluminescence of the Maillard reaction originates from Maillard reaction products formed by the equimolar reaction between sugar and amino acid and depends on the concentration of amino acid.
Kinetics of bactericidal activity of antibiotics measured by luciferin‐luciferase assay
Authors: de Rautlin de la Roy Y. , Messedi N. , Grollier G. , Grignon B. 
Published: May 2005

AbstractATP production, measured by the luciferin‐luciferase assay, is an indicator of bacterial metabolic activity. This enzymatic assay yields rapid results (< 5 minutes), permitting multiple measurements and establishment of ATP growth curves in order to study the kinetics of antibiotics in bacterial populations. The measurement of free or extracellular ATP, total ATP (extra and intracellular) and the ratio of free to total ATP are additional means of studying the bacteriostatic or bactericidal activity of antibiotics. An increase in free ATP is an indicator of extracellular movement due to alteration of the cell wall. The ratio free ATP/total ATP × 100 ≥ 50%, indicates bacteriallysis. These assays were used to study the effects of 14 antibiotics on two reference strains of Escherichia coli ATCC 25922 and Staphylococcus aureus 25923.
Influence of different luminols on the characteristics of the chemiluminescence reaction in human neutrophils
Authors: Lundqvist Helen , Kricka Larry J. , Stott Richard A. , Thorpe Gary H. G. , Dahlgren Claes 
Published: May 2005

AbstractIn search for a luminol with very high output of light, 20 different luminol samples were tested for their ability to enhance the chemiluminescence reaction in phorbol myristate acetate activated human neutrophils. We found that the majority of luminols tested (17 samples) gave almost the same light output from neutrophils, and that the major part of the activity was from an intracellular origin. Owing to the fact that three isoluminol samples were unable to monitor respiratory burst activity taking place intracellularly, a very low level of chemiluminescence was obtained with these samples. Their light output was, however, greatly increased when horseradish peroxidase or myeloperoxidase was added, showing that the light‐generating reaction with isoluminol as well as with luminol is peroxidase‐dependent.The fact that isoluminol could also use myeloperoxidase as amplifying peroxidase, suggests that the lack of measurable intracellular activity in the presence of isoluminol is somehow related to a limited or restricted diffusion of the molecule to intracellular sites. The isoluminol system constitutes a sensitive system for measuring release of oxygen metabolites from phagocytic cells.
Reverse micelle‐based chemiluminescence system for quinine sulphate
Authors: Tang Guofeng , Huang Yuming , Shi Wenbing 
Published: May 2005

AbstractA new chemiluminescence (CL) method is proposed for the determination of quinine sulphate, which is based on the dichloromethane solvent extraction of the ion‐pair complex of tetrachloroaurate (III) with quinine sulphate, and luminol CL detection in a reversed micellar medium formed by the cation surfactant cetyltrimethylammonium bromide in a dichloromethane–cyclohexane (3:7, v[sol ]v)–water (0.35 mol[sol ]L Na2CO3 buffer solution, pH 11.5). The ion‐pair complex of tetrachloroaurate (III) with quinine sulphate produced an analytical CL signal when it entered the reversed micellar water pool. In optimum conditions, CL intensities are proportional to the concentrations of the studied drug over the range 0.015–10 µg[sol ]mL, with a detection limit of 1.5 ng[sol ]mL. The relative standard deviation (RSD) is 1.38% for 2.5 µg[sol ]mL quinine sulphate (n = 11). The method has been applied to the determination of the studied drug in biological fluids, with satisfactory results. Copyright © 2005 John Wiley & Sons, Ltd.
Time‐resolved spectroscopic fluorescence imaging, transient absorption and vibrational spectroscopy of intact and photo‐inhibited photosynthetic tissue
Authors: Lukins Philip B. , Rehman Shakil , Stevens Gregory B. , George Doaa 
Published: May 2005

AbstractFluorescence, absorption and vibrational spectroscopic techniques were used to study spinach at the photosystem II (PS II), chloroplast and cellular levels and to determine the effects and mechanisms of ultraviolet‐B (UV‐B) photoinhibition of these structures. Two‐photon fluorescence spectroscopic imaging of intact chloroplasts shows significant spatial variations in the component fluorescence spectra in the range 640–740 nm, indicating that the type and distribution of chlorophylls vary markedly with position in the chloroplast. The chlorophyll distributions and excitonic behaviour in chloroplasts and whole plant tissue were studied using picosecond time‐gated fluorescence imaging, which also showed UV‐induced kinetic changes that clearly indicate that UV‐B induces both structural and excitonic uncoupling of chlorophylls within the light‐harvesting complexes. Transient absorption measurements and low‐frequency infrared and Raman spectroscopy show that the predominant sites of UV‐B damage in PS II are at the oxygen‐evolving centre (OEC) itself, as well as at specific locations near the OEC‐binding sites. Copyright © 2005 John Wiley & Sons, Ltd.
Determination of MDMA and MDA in rat urine by semi‐micro column HPLC‐fluorescence detection with DBD‐F and their monitoring after MDMA administration to rat
Authors: Wada Mitsuhiro , Nakamura Shinichi , Tomita Mamoru , Nakashima Mihoko N. , Nakashima Kenichiro 
Published: May 2005

AbstractA simultaneous semi‐micro column HPLC method with fluorescence detection of abused drugs, such as 3,4‐methylenedioxymethamphetamine (MDMA), 3,4‐methylenedioxyamphetamine (MDA), amphetamine (AP) and methamphetamine (MP) in rat urine was examined by using 4‐(N,N‐dimethylaminosulphonyl)‐7‐fluoro‐1,2,3‐benzoxadiazole (DBD‐F) as a labelling reagent and α‐phenylethylamine as an internal standard (IS). A sample (50 µL) of rat urine was added to 5 µL IS and 100 µL 100 mmol[sol ]L borate buffer (pH 12) and extracted with 1.5 mL n‐hexane. After evaporation, 50 µL 75 mmol[sol ]L borate buffer (pH 8.5) and 50 µL 20 mmol[sol ]L DBD‐F in CH3CN were added to the residue and mixed well. The resultant solution was heated for 20 min at 80°C and then cooled in an ice bath. A good separation of DBD‐derivatives could be achieved within 45 min using a semi‐micro ODS column with an eluent of CH3CN[sol ]CH3OH[sol ]10 mmol[sol ]L imidazole–HNO3 buffer (pH 7.0) (= 45:5:50, v[sol ]v[sol ]v %). The DBD derivatives were monitored at 565 nm with an excitation at 470 nm. The calibration curves showed good linearity (r = 0.997) with 0.5–15 ng[sol ]mL detection limits at a S[sol ]N ratio of 3. MDMA and MDA in rat urine could be monitored for 15 h after a single administration of MDMA to rat (2.0 mg[sol ]kg, i.p.). The concentrations for MDMA and MDA (n = 3) were 0.13–160.1 and 0.17–10.9 µg[sol ]mL, respectively. Copyright © 2005 John Wiley & Sons, Ltd.
Preliminary electrochemiluminescence study of allantoin in the presence of tris(2,2′‐bipyridine) ruthenium (II)
Authors: Chen Xi , Tao Ying , Zhao Li , Xie Zenghong , Chen Guonan 
Published: May 2005

AbstractElectrochemiluminescence (ECL) based on allantoin and tris(2,2′‐bipyridine)ruthenium (II) [Ru(bpy)32+] was studied in aqueous alkaline buffer solution (pH 11.0). In a flowing system, the eluted allantoin was mixed with 1.0 mmol[sol ]L Ru(bpy)32+. When the solution passed through a thin layer flow electrolytic cell equipped with a glassy carbon disc electrode (22.1 mm2), both hydroxyl groups of allantoin and Ru(bpy)32+ were oxidized at the potential of +1.50 V (vs. Ag[sol ]AgCl). The luminescence with λmax 610 nm caused by the reaction of electrolytically formed Ru(bpy)32+ with alkoxide radical to generate the excited state of Ru(bpy)32+*. A possible ECL process of allantoin in Ru(bpy)32+ alkaline solution has been discussed. In addition, the factors affecting the ECL response of allantoin are also investigated. Copyright © 2005 John Wiley & Sons, Ltd.
Flow‐injection resonance light scattering detection of proteins at the nanogram level
Authors: Tan Kejun , Li Yuanfang , Huang Chengzhi 
Published: May 2005

AbstractA resonance light scattering (RLS) detection method for protein was developed, using a flow‐injection system based on the enhancement of RLS signals from Biebrich scarlet (BS) by protein. The enhanced RLS intensities at 286.0 nm, in acidic aqueous medium, were proportional to the protein concentration over the range 0.005–18 µg[sol ]mL and 0.008–16 µg[sol ]mL for human serum albumin (HSA) and bovine serum albumin (BSA), respectively, with corresponding limits of detection (3σ) of 5.00 ng[sol ]mL for HSA, and 7.80 ng[sol ]mL for BSA. The method was successfully applied to the quantification of total proteins in human serum samples. Copyright © 2005 John Wiley & Sons, Ltd.
Method of determining the relative stability of different conformational states of biological macromolecules
Authors: Ptitsyn O. B. , Birshtein T. M. 
Published: May 2005

AbstractA general approach to the determination of relative stability of any pair of con‐formational states of biological macromolecules or their complexes (in particular, to the determination of relative stability of native and disordered states of the macromolecule) has been suggested. For determining the free energy difference of the two states under the conditions when one of them is considerably more advantageous than the other, it is necessary for the macromolecule to be influenced by the transforming agent which levels free energies of both the conformational states, and to determine the external parameter derivative of the free energy difference in the region of the conformational transition induced by the change in this parameter. If the character of the dependence of this derivative on the external parameter (temperature, solvent composition, etc.) is known, then this allows the determination of the free energy difference of the two states under the conditions considered, even including conditions far from the transition region. The value of the derivative of the free energy difference in the transition region in many cases can be measured directly (in particular, when using calorimetry), while in cases when a direct measurement of the derivative is impossible, it can often he estimated experimentally from the steepness of the conformational transition. The methods of this estimation and also a possible character of the change of the considered derivative during variation of the external parameter are considered for the case when the transforming agent is one of the components of the solvent and, consequently, the derivative of the free energy difference is equal to the difference of number of molecules of this component hound with the macromolecule in two conformational states.
Mechanical properties of poly(glutamic acid) in aqueous solution
Authors: Konno Akira , Kaneko Motozo 
Published: May 2005

AbstractThe interaction between ionizable carboxyl groups and the conformation of poly‐(glutamic acid) (PGA) in aqueous solution were investigated by the mechanical method. The dynamic rigidity of the PGA solution has a maximum value at the pH corresponding to about 50% neutralization point. This may be due to establishing of a maximum attractive force by proton/charge fluctuation between ionizable carboxyl groups at that pH. The dynamic viscosity has a sharp change in the region of pH 5.5–6.5. It is suggested that this behavior is due to the helix–coil transition.
Heats of fusion of various amounts of absorbed water in wool keratin
Authors: Haly A. R. , Snaith J. W. 
Published: May 2005

AbstractWool–water systems, at water contents above a threshold value of 22.7 g of water per 100 g of wool keratin, yielded curves of specific heat against temperature showing peaks that are ascribed to the fusion of the absorbed water. Integral and incremental heats of fusion were obtained. Integral heats increase as the square of the water content above the threshold, and incremental heats follow a linear relationship. The incremental heat reaches a value of 55 cal/absorbed water, at the saturation water content, at 0°C of 33.9 g of water per 100 g of keratin. The state of the absorbed water is discussed. Clustering of water molecules takes place only above the threshold water content.
Salt effects on the denaturation of DNA
Authors: Gruenwedel Dieter W. , Hsu Chi‐Hsia 
Published: May 2005

AbstractWhen DNA's of differing GC:AT base ratios, e.g. synthetic poly dAT, T4 DNA, calf thymus DNA, E. coli DNA, and M. Iysodeiklicus DNA, are heat‐denatured at, neutral pH in increasing concentrations of Na2SO4 or Cs2SO4 as supporting electrolytes, the variation of melting temperature with average base composition, dTm/dXG C, changes from 45°C (in 0.002M Na) to 11°C (in 4.5M Na) and from 42°C (in 0.002M Cs) to 3°C (in 4.5M Cs). The decrease of dTm/dXG C is a monotonic function of decreasing water activity in the salt, solutions. We interpret this decreased composition dependence of the thermal stability of the various DNA's as being due to a destabilization of the GC base pairs relative to the AT base pairs by the concentrated salt media. A simple quantitative treatment shows that k = sG C/sA T decreases from a value of 4.14 (in 0.01.M Na) to 1.86 (in 3 M Na) and from 4.18 (in 0.01 M Cs) to 1.42 (in 3 M Cs). SA T is the equilibrium constant for the formation of a hydrogen‐bonded AT base pair from a pair of unbonded bases at, the junction between a helical region and a denatured region and sG C is the like constant for the formation of a GC base pair. These results corroborate our previous findings of a strongly reduced composition dependence of the negative logarithm of the methylmercurie hydroxide concentration necessary to produce 50% denaturation when the helix–coil transition of DNA is studied in concentrated Cs2SO4 (ultracentrifugation) instead of in dilute Na2SO4 (ultraviolet spectrophotometry).
Far‐infrared spectra of poly(‐α‐amino acids) with basic alkyl group side chains
Authors: Itoh Koichi , Shimanouchi Takehiko , Oya Masanao 
Published: May 2005

AbstractFar‐infrared spectra in the region from 700 to 60 cm−1 have been measured for the α‐helix structures of poly(L‐α‐amino‐n‐butyric acid), poly‐L‐norvaline, poly‐L‐norleucine, and poly‐L‐leucine and for the β‐form structures of poly(L‐α‐amino‐n‐butyric acid), poly‐L‐valine, poly(DL‐amino‐n‐butyric acid), poly‐DL‐norvaline, and poly‐DL‐norleucine. The changes of the spectra on N‐deuteration have been measured in the region between 700 and 400 cm−1. It is concluded that, the α‐helix has characteristic bauds near 690, 650, 610, 380, 150, and 100 cm−1, and that the β‐form has characteristic bands near 700, 240, and 120 cm−1. The main‐chain vibrations in the region from 600 to 200 cm−1 are strongly coupled with the side‐chain deformation vibrations.
Interaction des Ions Métalliques avec le DNA. II. Adsorption préférentielle de l'Ion césium par les Acides nucléiques
Authors: Doppler‐Bernardi F. , Daune M. 
Published: May 2005

AbstractPreferential adsorption of cations occurs in the solvated shell surrounding polyanions, especially polynucleotides and nucleic acids. The solvation parameter Γ is determined from sedimentation coefficients which are considered as pienometric determinations of the specific volume of the sample. By comparing two identical concentrations (0.1M) of monovalent salts, NaCl and CsCl, and using the model of DNA described in the preceding paper, one can relate the ratio SCs/SNa to solvation parameters ΓCs, and ΓNa.On the other hand, Γ can be related to the difference of energy W, between cation and water, to be extracted from the solution and placed in the vicinity of the polyanion. One finds generally a preferential solvation of the polarizable caesium ion by means of London–van der Waals interactions with bases. With reasonable assumptions, an estimate of W can be made, and the predicted value of Γ can be compared to the experimental one. An average of six sites is found around each base in a single‐stranded polymer, but‐only one in the double‐stranded structure. The amount of secondary structure can thus be estimated from the simple measurement of the ratio of two sediment constants.
Studies of a specific association between acriflavine and DNA in intact cells
Authors: Roth Daniel , Manjon Maria L. 
Published: May 2005

AbstractThe nature of a specific association between acriflavine and cellular DNA was investigated by subjecting the DNA of intact cells to denaturation, ultraviolet radiation, and base analog substitution. The predictable modifications of DNA structure were then correlated with the quantitative alterations in dye adsorption by the cells. It was concluded that, under experimental conditions of limited dye availability, the bonding of dye was restricted to sites of highest bonding affinity. These were shown to be situated between adjacent thymine molecules on a single strand of DNA. The 5‐methyl groups of thymine may endow the bond with its specificity.
Concerning the kinetics of polypeptide synthesis on polyribosomes
Authors: MacDonald Carolyn T. , Gibbs Julian H. 
Published: May 2005

AbstractThe kinetics of biosynthesis of polypeptides on polyribosomes is analyzed in accordance with a simple mathematical model. Each ribosome is assumed to block L adjacent. (m‐RNA) template sites but to move a distance of one, and only one, template site (nucleotide triplet) upon the addition of each monomer unit to the growing polypeptide chain bound to it. Solutions are sought, for the probability, nj(t), that a template possesses, at time t, a polypeptide chain that has reached degree of polymerization j.Several classes of steady‐state solutions are obtained via machine computation. These correspond to various choices of relative rates of initiation, polymerization along templates, and termination (release of completed chains from templates).Experimental data available from radioactive pulse labeling experiments are discussed. The data obtained by Dintzis, and by Winslow and Ingram, in studies of the synthesis of the α chain of rabbit hemoglobin and human hemoglobin, respectively, are consistent with steady‐state solutions obtained from the current theoretical calculations when the rates of initiation and termination are of comparable magnitude and rate‐determining. In this case, a (relatively) small number of chains are polymerized at a (relatively) fast rate each near the beginning of the template, and there exists a transition to a situation near the end of the template in which a (relatively) large number of chains are polymerized at a (relatively) slow rate each. For this solution the situation near the end of the template is entirely analogous to a traffic jam in automobile traffic.
Influence of temperature on the helix sense of several polyamino acids
Authors: Lotan N. , Momany F. A. , Yan J. F. , Vanderkooi G. , Scheraga H. A. 
Published: May 2005

AbstractAn increase in temperature causes an increase in the amplitudes of intramolecular and intermolecular motions and mainfests itself as an increase in the effective radii of the various atoms, especially hydrogen atoms. If one uses a Lennard‐Jones 6‐12 potential function to account for nonbonded interactions, this increase in the radius of the hydrogen atom is equivalent to a modification of the coefficient of the repulsive part of the Lennard‐Jones potential. Accordingly, this effect of increasing temperature on the helix sense of several polyamino acids is computed by allowing the effective radius of the hydrogen atom to increase. It is found that the preferred sense of several polyamino acid helices changes from right‐ to left‐handed as the temperature is increased. This accounts for recent experimental observations of changes in helix sense with temperature.