bluuebunny/crossref_metadata_2025_split huggingface dataset:
Indirect identification of isoprenoid quinones in Escherichia coli by LC‐MS with atmospheric pressure chemical ionization in negative mode
Authors: Gao Mengchun , Liu HongJun , Yang Min , Hu JianYing , Shao Bing 
Published: November 2004

AbstractA novel analytical method was applied for identification of isoprenoid quinones in Escherichia coli by liquid chromatography atmospheric press chemical ionization mass spectrometry in negative mode (LC‐NI‐APCI‐MS). Extraction and clean‐up of sample were carried out on Sep‐Pak Plus Silica solid‐phase extraction cartridges. Ubiquinone‐7 (UQ‐7), Ubiquinone‐8 (UQ‐8) and Mequinone‐8 (MK‐8) were determined directly using combined information on retention time, molecular ion mass, fragment ion masses and UV characteristic spectrometry without any standard reagent. It was found that UQ‐8 was the major component of isoprenoid quinones in Escherichia coli under aerobic condition. Compared with UQ‐8, the relative abundance of UQ‐7 and MK‐8 is only 15% and 14%, respectively. The average recoveries of UQ‐6, UQ‐10 and vitamin K1 in Escherichia coli were investigated by standard spiking experiment. The recoveries were achieved in the range from 94 to 106%, and the relative standard deviations (RSD) of the triplicate analysis of the spiked samples (UQ‐6, UQ‐10 and vitamin K1) ranged from 3 to 8%. The detection limits of LC‐NI‐APCI‐MS were estimated to be 5, 40 and 0.8 μg/g dry cell for UQ‐6, UQ‐10 and vitamin K1, respectively. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Bacillus megaterium comE locus encodes a functional DNA uptake protein
Authors: Lammers Michael , Nahrstedt Hannes , Meinhardt Friedhelm 
Published: November 2004

AbstractFrom Bacillus megaterium, a genomic region was isolated and structurally characterized which strongly resembles the Bacillus subtilis competence locus comE encoding proteins involved in DNA uptake. Functionality of the B. megaterium comEA gene was proven by complementing a DNA‐receptor mutant of B. subtilis. This finding provides first evidence for a latent ability of B. megaterium to develop natural competence, although such physiological state has not as yet been identified in this organism. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characterization of a Poly(2‐oxazoline) Library by High‐Throughput, Automated Contact‐Angle Measurements and Surface‐Energy Calculations
Authors: Wijnans Sanne , de Gans Berend‐Jan , Wiesbrock Frank , Hoogenboom Richard , Schubert Ulrich S. 
Published: November 2004

AbstractSummary: The feasibility of automated, high‐throughput contact‐angle measurements is demonstrated using a modified commercial contact‐angle measuring apparatus. Droplets are automatically dispensed, analyzed and aspirated. The system automatically measures more than 100 contact angles per hour using two test liquids, and calculates surface energies using the equation of state method. A library of poly(2‐oxazoline) homo‐ and block copolymers was investigated. Polymers with a 2‐nonyl‐2‐oxazoline block were found to have considerably lower surface energies.Setup used here for characterization of the surface properties of a library of poly(2‐oxazoline) homo‐ and block copolymers.imageSetup used here for characterization of the surface properties of a library of poly(2‐oxazoline) homo‐ and block copolymers.
Towards the Nature of Active Sites in Polymerization of Cyclic Esters Initiated by Aluminium Alkoxides: First Structurally Authenticated Aluminium‐ε‐Caprolactone Complex
Authors: Lewiński Janusz , Horeglad Paweł , Tratkiewicz Ewa , Grzenda Wojciech , Lipkowski Janusz , Kolodziejczyk Edyta 
Published: November 2004

AbstractSummary: The isolation and structural characterization of a methylaluminium(bisphenoxide)‐ε‐caprolactone complex is reported. While the three‐coordinate methylaluminium complex was found not to catalyze the polymerization of ε‐caprolactone, its oxygenation led to the formation of an aluminium methoxide compound, which appeared to be a very good initiator. The relative propensity of the AlX bonds for monomer insertion in the initial step of polymerization is also discussed.Structure of the methylaluminium(bisphenoxide)‐ε‐caprolactone complex reported here.imageStructure of the methylaluminium(bisphenoxide)‐ε‐caprolactone complex reported here.
Asymptotics of solutions for sub critical non‐convective type equations
Authors: Hayashi Nakao , Kaikina Elena I. , Naumkin Pavel I. 
Published: November 2004

AbstractWe study the Cauchy problem for non‐linear dissipative evolution equationsequation imagewhere ℒ︁ is the linear pseudodifferential operatorand the non‐linearity is a quadratic pseudodifferential operatorequation imageû≡ ℱx→ξuis the Fourier transformation. We consider non‐convective type non‐linearity, that is we suppose thata(t,0,y) ≠ 0. Let the initial data$u_{0} \in {\bf H}^{\varrho,0} \cap {\bf H}^{0, \varrho}, \varrho > {1\over 2}$, are sufficiently small and have a non‐zero total mass$\int u_{0}(x){\rm d}x \ne 0$, whereis the weighted Sobolev space. Then we give the main term of the large time asymptotics of solutions in the sub critical case. Copyright © 2004 John Wiley & Sons, Ltd.
Second‐order analysis and design of steel structures allowing for member and frame imperfections
Authors: Gu J. X. , Chan S. L. 
Published: November 2004

AbstractConventional linear analysis is deficient in handling the design of slender frames since the effective length and other non‐linear effects are difficult to assess accurately. Some proposed non‐linear analyses cannot be directly employed for practical design since they are unable to re‐produce the buckling curves of the basic structural element, a simple column under axial force, by a single element per member. This paper describes an advanced element, using the same physical significance as the advanced and second‐order analysis proposed by a number of researchers and the BS5950(2000) and AS4100 (1995), for practical design of slender steel frames. The proposed element captures the physical behaviour of a structural member that the buckling strength of the member can be predicted using a single element per member and without assuming any effective length. Copyright © 2004 John Wiley & Sons, Ltd.
Dynamic response and reliability analysis of structures with uncertain parameters
Authors: Li Jie , Chen Jian‐Bing 
Published: November 2004

AbstractAn original approach for dynamic response and reliability analysis of stochastic structures is proposed. The probability density evolution equation is established which implies that incremental rate of the probability density function is related to the structural response velocity. Therefore, the response analysis of stochastic structures becomes an initial‐value partial differential equation problem. For the dynamic reliability problem, the solution can be derived through solving the probability density evolution equation with an initial value condition and an absorbing boundary condition corresponding to specified failure criterion. The numerical algorithm for the proposed method is suggested by combining the precise time integration method and the finite difference method with TVD scheme. To verify and validate the proposed method, a SDOF system and an 8‐storey frame with random parameters are investigated in detail. In the SDOF system, the response obtained by the proposed method is compared with the counterparts by the exact solution. The responses and the reliabilities of a frame with random stiffness, subject to deterministic excitation or random excitation, are evaluated by the proposed method as well. The mean, the standard deviation and the reliabilities are compared, respectively, with the Monte Carlo simulation. The numerical examples verify that the proposed method is of high accuracy and efficiency. Moreover, it is found that the probability transition of structural responses is like water flowing in a river with many whirlpools, showing complexity of probability transition process of the stochastic dynamic responses. Copyright © 2004 John Wiley & Sons, Ltd.
Safety of anthrax vaccine: an expanded review and evaluation of adverse events reported to the Vaccine Adverse Event Reporting System (VAERS)
Authors: Sever John L. , Brenner Alan I. , Gale Arnold D. , Lyle Jerry M. , Moulton Lawrence H. , Ward Brian J. , West David J. 
Published: November 2004

AbstractPurposeTo assess the safety of a licensed anthrax vaccine (AVA) given to more than 500 000 US military personnel, through review and medical evaluation of adverse events (AEs) reported to the Vaccine Adverse Event Reporting System (VAERS).MethodsAEs were summarized by person, vaccine lot, type, frequency and impact. A Delphic approach was used to tentatively assess causality in an effort to detect serious AEs (SAEs) or other medically important AEs (OMIAEs) possibly attributable to AVA.ResultsThe Anthrax Vaccine Expert Committee (AVEC) reviewed 1841 reports describing 3991 AEs (9.4 reports/10 000 doses of AVA) that were submitted to VAERS from 1Q1998 through 4Q2001. One hundred forty‐seven reports described an SAE or OMIAE, of which 26 were tentatively rated as possible, probable or certain consequences of vaccination (injection‐site reaction [12], ‘anaphylactic‐like reaction’ [5] and eight other systemic AEs [1–2 each]).ConclusionsThis review produced no evidence for an unusual rate of any SAE or OMIAE attributable to AVA. It supported an earlier impression that AVA may cause significant local inflammation and should be administered over the deltoid rather than the triceps to avoid direct or compression injury to the ulnar nerve. The subjects of VAERS reports tended to be older than all recipients of AVA. Females generally had and/or reported AEs more often than males, but transient articular reactions were surprisingly more common in males. Variations in the frequency or severity (as judged by hospitalization and/or loss of duty) of reported AEs did not suggest a significant problem with (1) a particular lot of AVA, (2) recurrent AEs after multiple doses or (3) vaccination of persons with a concomitant illness or those given other vaccines or medications. Copyright © 2004 John Wiley & Sons, Ltd.
Predictors of receipt of a fluoroquinolone versus trimethoprim‐sulfamethoxazole for treatment of acute pyelonephritis in women in Manitoba, Canada
Authors: Carrie Anita G. , Metge Colleen J. , Collins David M. , Harding Godfrey K. M. , Zhanel George G. 
Published: November 2004

AbstractPurposeThe increasing and comparatively high proportion of uropathogens in Canada resistant to trimethoprim‐sulfamethoxazole (TMP‐SMX) may be partially responsible for the increasing use of fluoroquinolones. A number of patient‐specific variables have been identified as risk factors for infections caused by antibiotic‐resistant pathogens. However, variables unrelated to need, have also been associated with receipt of broad‐spectrum antibiotics. We identified patient variables associated with receipt of a fluoroquinolone versus TMP‐SMX for treatment of acute pyelonephritis.MethodsHealthcare claims from the province of Manitoba, Canada for the period February 1996 to March 1999 were examined to identify episodes of pyelonephritis in non‐pregnant females between 18 and 65 years of age treated with TMP‐SMX or a fluoroquinolone. Patient variables were identified based on healthcare claims review and data from Statistics Canada. Logistic regression was used to model the probability of receipt of a fluoroquinolone.ResultsA total of 1084 women met inclusion criteria; 653 treated with TMP‐SMX and 431 treated with a fluoroquinolone. Age, income, rural residence, recent antibiotic use, recent hospitalization and presentation to an emergency room (ER) were positively associated with receipt of a fluoroquinolone.ConclusionsPatient variables reportedly associated with an increased probability of resistant organisms (e.g., age, recent antibiotic use and recent hospitalization) were significantly associated with an increased probability of receipt of fluoroquinolones. However, variables unrelated to antibiotic resistance (e.g., income, rural residence and presentation to an ER) were also significantly associated with receipt of a fluoroquinolone. Copyright © 2004 John Wiley & Sons, Ltd.
Factors affecting the adsorption of cationic dyes on polymeric hydrogels prepared by gamma irradiation
Authors: Ismail Laila FM , Maziad Nabila A , Abo‐Farha Samia A 
Published: November 2004

AbstractThe adsorption of the cationic dyes Rhodamine B (RB) and Crystal Violet (CV) on polyacrylamide/poly(acrylic acid) (poly(AAm/AAc), 25:25 % weightwise) and polyacrylamide/poly(sodium acrylate) (poly(AAm/AAcNa), 25:25 % weightwise) hydrogels was studied, employing the Langmuir and Freundlich isotherms. The results of swelling tests at pH 5.5 indicate that poly(AAm/AAcNa) hydrogel shows maximum percentage swelling (%S) was 4400 %. Moreover, the results show that the adsorption capacity is pH‐ and concentration‐dependent. At pH >5 adsorption of RB and CV increases due to ionization of COOH and COONa groups of (poly(AAm/AAc) and (poly(AAm/AAcNa) and interactions with the cationic groups of the dyes. However, at pH lower than 5, adsorption is still high, which can be explained by considering the formation of hydrogen bonds between the amino groups of the dyes and the COOH groups of the polymeric hydrogels. Moreover, the kinetics of adsorption follows a first‐order equation. Furthermore, scanning electron microscopy (SEM) micrographs of polymeric hydrogels doped with CV and RB have morphological differences from the pure form. Our data show that Rhodamine B adsorbs more efficiently on both polyacrylamide/poly(acrylic acid) and polyacrylamide/poly(sodium acrylate) hydrogels than CV. Copyright © 2004 Society of Chemical Industry
Poly(ether ketone)–polyisobutylene block copolymers: Synthesis and phase behavior
Authors: Binder Wolfgang H. , Machl Doris 
Published: November 2004

AbstractTelechelic poly(ether ketone)s (PEKs) and polyisobutylenes (PIBs) were combined to form PIBPEKPIB triblock copolymers and (PIBPEK)n multiblock copolymers via the formation of urea linkages. Monovalent and bivalent amino telechelic PIBs were prepared quantitatively from allyl telechelic PIBs by a newly developed reaction sequence featuring nucleophilic reaction steps. Telechelic PEKNCO polymers were prepared from the corresponding amino telechelic PEKs via a reaction with diphosgene. The highly reactive PEKNCO and PIBNH2 telechelics formed PEKPIB block copolymers only quantitatively when appropriately reactive primary amino groups were present on the amino telechelic PIBs. The obtained block copolymers were microphase‐separated and featured mostly lamellar structures, as determined by small‐angle X‐ray scattering (SAXS). Temperature‐dependent SAXS measurements revealed ordered polymers in the melt up to 210 °C. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 188–202, 2005
Synthesis, characterization, thermal properties, and antimicrobial activity of 4‐chloro‐3‐methyl phenyl methacrylate/8‐quinolinyl methacrylate copolymers
Authors: Patel Milan V. , Patel Jatin N. , Ray Arabinda , Patel Rajni M. 
Published: November 2004

Abstract4‐Chloro‐3‐methyl phenyl methacrylate (CMPM) and 8‐quinolinyl methacrylate (8‐QMA) were synthesized through the reaction of 4‐chloro‐3‐methyl phenol and 8‐hydroxy quinoline, respectively, with methacryloyl chloride. The homopolymers and copolymers were prepared by free‐radical polymerization with azobisisobutyronitrile as the initiator at 70 °C. Copolymers of CMPM and 8‐QMA of different compositions were prepared. The monomers were characterized with IR spectroscopy and 1H NMR techniques. The copolymers were characterized with IR spectroscopy. UV spectroscopy was used to obtain the compositions of the copolymers. The monomer reactivity ratios were calculated with the Fineman–Ross method. The molecular weights and polydispersity values of the copolymers were determined with gel permeation chromatography. The thermal stability of the polymers was evaluated with thermogravimetric analysis under a nitrogen atmosphere. The homopolymers and copolymers were tested for their antimicrobial activity againstbacteria, fungi, and yeast. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 157–167, 2005
Synthesis of photosensitive and thermosetting poly(phenylene ether) based on poly[2,6‐di(3‐methyl‐2‐butenyl)phenol‐co‐2,6‐dimethyl‐phenol] and a photoacid generator
Authors: Matsumoto Kazuya , Shibasaki Yuji , Ando Shinji , Ueda Mitsuru 
Published: November 2004

AbstractA chemically amplified photosensitive and thermosetting polymer based on poly[2,6‐di(3‐methyl‐2‐butenyl)phenol (15 mol %)‐co‐2,6‐dimethylphenol (85 mol %)] (3c) and a photoacid generator [(5‐propylsulfonyloxyimino‐5H‐thiophen‐2‐ylidene)‐(2‐methylphenyl)acetonitrile] was developed. Poly[2,6‐bis(3‐methyl‐2‐butenyl)phenol]‐co‐2,6‐dimethylphenol)] (3) with high molecular weights (number‐average molecular weight ∼ 24,000) was prepared by the oxidative coupling copolymerization of 2,6‐di(3‐methyl‐2‐butenyl)phenol with 2,6‐dimethylphenol in the presence of copper(I) chloride and pyridine as the catalyst under a stream of oxygen. The structures of 3 were characterized with IR, 1H NMR, and 13C NMR spectroscopy. 3 was crosslinked by a thermal treatment at 300 °C for 1 h under N2. The 5% weight loss temperatures and glass‐transition temperatures of the cured copolymers reached around 420 °C in nitrogen and 300 °C, respectively. The average refractive index of the cured copolymer (3c) film was 1.5452, from which the dielectric constant at 1 MHz was estimated to be 2.6. The resist showed a sensitivity of 35 mJ cm−2 and a contrast of 1.6 when it was exposed to 436‐nm light, postexposure‐baked at 145 °C for 5 min, and developed with toluene at 25 °C. A fine negative image featuring 8‐μm line‐and‐space patterns was obtained on a film exposed to 100 mJ cm−2 with 436‐nm light in the contact‐printed mode. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 149–156, 2005
Synthesis, characterization, and application of melamine‐based dendrimers supported on silica gel
Authors: Acosta Erick J. , Gonzalez Sergio O. , Simanek Eric E. 
Published: November 2004

AbstractDendrimers based on melamine have been covalently attached to silica gel with convergent and divergent approaches. These approaches yield different products. Each step of the synthesis can be monitored with Fourier transform infrared spectroscopy, thermal gravimetric analysis, and X‐ray photoelectron spectroscopy. The organic molecules can be isolated by chemical etching the organosilica material with HF and then analyzed by mass spectrometry. The convergent approach, which relies on the solution‐phase synthesis of the dendrimer before its attachment onto silica gel, produces materials that are ∼20% w/w organic regardless of the generation of the dendrimer used in the preparation of these composites and without apparent defects in the dendrimer structure. Materials prepared with the divergent approach show increasing percentages of organic material with each generation, but the dendrimers show structural defects including incomplete branching. In a survey of sequestration potential, materials obtained with the divergent approach removed more atrazine from solution than the more homogeneous materials obtained from the convergent approach. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 168–177, 2005
Microemulsion copolymerization of styrene and acrylonitrile with n‐butanol as the cosurfactant
Authors: Shi Yuanchang , Wu Youshi , Hao Jingcheng , Li Ganzuo 
Published: November 2004

AbstractThe microemulsion copolymerization of styrene and acrylonitrile in an n‐butanol/cetyltrimethylammonium bromide/oil/water microemulsion system was studied. The solubilization sites of the two monomers were determined with an NMR technique. The results showed that the solubilization behaviors of the two monomers were quite different. Most of the styrene was solubilized in the palisade layer of the microemulsion, whereas the acrylonitrile had an equilibrium distribution in the aqueous phase and palisade layer of the microemulsion. The reactivity ratios of styrene and acrylonitrile in the microemulsion system were different from those in other media. The effect of the monomer feed composition on the copolymerization kinetics was investigated, and the mechanism of nucleation of the latex particles was examined. The experimental results showed that the copolymerization loci were changed from the microemulsion droplets to the aqueous phase when the concentration of acrylonitrile in the monomer feed reached approximately 80%; this could be further proved by the effect of the monomer feed composition on the copolymerization kinetics. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 203–216, 2005
Evolution of the termination rate coefficient in styrene polymerization
Authors: Arcos‐Casarrubias José Antonio , Olayo Roberto , Bernechea Jaime Noriega 
Published: November 2004

AbstractStyrene bulk polymerization was conducted at 70 °C with a high initiator concentration, and this ensured that the dominant chain‐stopping mechanism was the combination of free radicals. The evolution of the molecular weight distribution (MWD) of the polymer was measured via the periodic removal of samples during the course of the reaction and their analysis with gel permeation chromatography. The overall termination rate coefficient was independent of the conversion in the dilute regime, as observed from cumulative MWDs. In the middle of the conversion range, the observed trend was compatible with a translational‐diffusion‐controlled mechanism for the termination step. A bimodal distribution of the molecular weights was also found at high conversions and could be explained in terms of an increase in the free‐radical concentration and a very low termination rate coefficient. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 178–187, 2005
Issues in high‐throughput comparative modelling: A case study using the ubiquitin E2 conjugating enzymes
Authors: Winn P.J. , Battey J.N.D. , Schleinkofer K. , Banerjee A. , Wade R.C. 
Published: November 2004

AbstractSequences of the ubiquitin‐conjugating enzyme (UBC or E2) family were used as a test set to investigate issues associated with the high‐throughput comparative modelling of protein structures. A semi‐automatic method was initially developed with particular emphasis on producing models of a quality suitable for structural comparison. Structural and sequence features of the E2 family were used to improve the sequence alignment and the quality of the structural templates. Initially, failure to correct for subtle structural inconsistencies between templates lead to problems in the comparative analysis of the UBC electrostatic potentials. Modelling of known UBC structures using Modeller 4.0 showed that multiple templates produced, on average, no better models than the use of just one template, as judged by the root‐mean‐squared deviation between the comparative model and crystal structure backbones. Using four different quality‐checking methods, for a given target sequence, it was not possible to distinguish the model most similar to the experimental structure. The UBC models were thus finally modelled using only the crystal structure template with the highest sequence identity to the target to be modelled, and producing only one model solution. Quality checking was used to reject models with obvious structural anomalies (e.g., bad side‐chain packing). The resulting models have been used for a comparison of UBC structural features and of their electrostatic potentials. The work was extended through the development of a fully automated pipeline that identifies E2 sequences in the sequence databases, aligns and models them, and calculates the associated electrostatic potential. Proteins 2005. © 2004 Wiley‐Liss, Inc.