bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis and characterization of nanosized polypyrrole–polystyrene composite particles
Authors: Xu Xiao‐Jun , Gan Leong‐Ming , Siow Kok‐Siong , Wong Ming‐Keong 
Published: November 2003

AbstractNanosized polypyrrole–polystyrene (PPy–PS) composite particles were synthesized by the polymerization of pyrrole on PS nanoparticles in the presence of FeCl3. The PS nanoparticles were prepared from microemulsion polymerizations using the cationic nonpolymerizable surfactant cetyltrimethylammonium bromide (CTAB), the nonionic polymerizable surfactant ω‐methoxy[poly(ethylene oxide)40]undecyl α‐methacrylate (PEO–R–MA‐40), or the cationic polymerizable surfactant ω‐acryloyloxyundecyltrimethylammonium bromide (AUTMAB). For the latexes stabilized by CTAB, the resulting PPy–PS composite particles exhibited relatively poor colloidal stability and the pressed pellets exhibited relatively low electrical conductivities (∼10−7–10−3 S cm−1). However, for the latexes stabilized by polymerizable surfactants, the resulting PPy–PS composite particles exhibited relatively good colloidal stability and relatively high conductivities (∼10−5–10−1 S cm−1). The effect of polymerizable surfactants on the colloidal stability of composite particles and the conducting mechanism of the composites are discussed. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1360–1367, 2004
Supramolecular assembly of collagen triblock peptides
Authors: Martin Raquel , Waldmann Lars , Kaplan David L. 
Published: November 2003

AbstractThe relationship between primary sequence and collagen triple‐helix formation is relatively well characterized, while higher levels of structural assembly from these sequences is poorly understood. To address this gap, a new collagen‐like triblock peptide design was used to study the relationship between amino acid sequence and supramolecular assembly. Four collagen‐like peptides with the sequence (Glu)5(Gly–Xaa–Hyp–Gly–Pro–Hyp)6(Glu)5 and corresponding to Xaa = alanine, proline, serine, or valine, and an analogous peptide without the glutamic acid end blocks, were solubilized in water at high concentrations (20–150 mg/mL) and analyzed in optical polarizing microscopy and transmission electron microscopy. Some of the peptides self‐assembled into supramolecular structures, the nature of which was determined by the core collagen‐like sequence. The globular end blocks appeared necessary for these short triple‐helix‐forming peptides to spontaneously organize into supramolecular structures in solution and also provided enhanced thermal stability based on CD analysis. The results indicate a strong dependence of the peptide triblock assembly behavior on the identity of the guest residue Xaa; nematic order when Xaa was valine, no organization when Xaa was serine, and banded spherulites displaying a cholesteric‐like twist when Xaa was proline or alanine. According to these results, the identity of the amino acid in position Xaa of the triplet Gly–Xaa–Yaa dramatically determined the type of supramolecular assembly formed by short triple helices based on collagen‐triblock like sequences. Moreover, the structural organization observed for these collagen‐triblock peptides was analogous to some assemblies observed for native collagen in vivo and in vitro. The amino acid sequence in the native collagen proteins may therefore be a direct determinant of the different supramolecular architectures found in connective tissues. © 2003 Wiley Periodicals, Inc. Biopolymers 70:435–444, 2003
Fluorescence properties of labeled proteins near silver colloid surfaces
Authors: Maliwal Badri P. , Malicka Joanna , Gryczynski Ignacy , Gryczynski Zygmunt , Lakowicz Joseph R. 
Published: November 2003

AbstractThe fluorescence properties of a monolayer of labeled avidin molecules were studied near silver island films. We first adsorbed a monolayer of biotinylated‐BSA as a base that was used to capture labeled avidin molecules. For labeled avidin on silver island films, we observed an increase of the fluorescence intensity of between 18 and 80 with one‐photon excitation and up to several hundredfold or larger with two‐photon excitation. The probes were moderately more photostable in the presence of silver islands. There was also a dramatic decrease in the lifetimes with the amplitude‐weighted values decreasing from 7‐ to 35‐fold. The data suggest that these spectral changes are due to both increased rates of excitation near the metallic particles and increases in the rates of radiative decay. Because these silver island surfaces are very heterogeneous, we are hopeful that larger increases in intensity and photostability can be obtained for probes situated at an optimal distance from the ideal island surfaces. © 2003 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 70: 585–594, 2003
Nondestructive analyses of unsaturated fatty acid species in dietary oils by attenuated total reflectance with Fourier transform IR spectroscopy
Authors: Yoshida Satoshi , Yoshida Hiroshi 
Published: November 2003

AbstractThe aim of this study was to develop a nondestructive method to quantitate relative amounts of n‐3 and n‐6 polyunsaturated fatty acid (PUFA) species in vegetable oils and oil seeds using Fourier transform IR spectroscopy (FTIR). The alkene CH stretching vibrations of unsaturated fatty acids in oils showed IR absorption bands with various peak positions and intensities at around 3010 cm−1, depending on the extent of unsaturation and PUFA species. With the aid of partial least‐squares regression analysis, the FTIR measurement could practically predict the content of each PUFA species in the oil to be tested. A calculation method was also presented to directly find PUFA species in oils from the FTIR spectra. This technique was applied to dried soybean seeds to demonstrate a nonhomogenous distribution of saturated fatty acids and PUFAs, as well as glycans, in soybean cross sections. © 2003 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 70: 604–613, 2003
Volumetric characterization of homopolymeric amino acids
Authors: Noudeh Gholamreza D. , Taulier Nicolas , Chalikian Tigran V. 
Published: November 2003

AbstractWe have determined the partial molar volumes, expansibilities, and adiabatic compressibilities for poly(L‐alanine), poly(L‐proline), and poly(L‐threonine) within the temperature range of 18–55°C. In addition, we have determined at 25°C changes in volume, ΔV, and adiabatic compressibility, ΔKS, associated with the coil‐to‐helix transitions of poly(L‐lysine) and poly(L‐glutamic acid) and the α‐to‐β transition of poly(L‐lysine). We have interpreted our volumetric data as suggesting that poly(L‐alanine) and poly(L‐proline) are not fully unfolded and, probably, retain some solvent‐inaccessible core. Further, we propose that poly(L‐threonine) is fully unfolded with the majority of its atomic groups being solvent‐exposed. Near zero changes in volume and compressibility accompanying the coil‐to‐helix transitions of poly(L‐lysine) and poly(L‐glutamic acid) suggest that, in the absence of fortuitous compensations, the coil‐to‐helix transitions of the polypeptides do not result in any significant enhancement of solute hydration. By contrast, the α‐to‐β transition of poly(L‐lysine) causes slight but statistically significant increases in volume and compressibility, an observation that may suggest that the β‐sheet conformation of poly(L‐lysine) is slightly less hydrated than its α‐helical conformation. In general, our results provide a quantitative volumetric description of the hydration properties of the homopolymeric polypeptides investigated. Such characterizations should prove useful in developing an understanding of the role that solvent plays in the stabilization/destabilization of folded protein structures and protein complexes. © 2003 Wiley Periodicals, Inc. Biopolymers 70: 563–574, 2003
Hydrophobic tendencies of polar groups as a major force in molecular recognition
Authors: Chalikian Tigran V. 
Published: November 2003

AbstractProteins and nucleic acids are able to adopt their native conformation and perform their biological role only in the presence of water with which they actively interact in a mutually modifying way. Traditionally, hydrophobic effect has been considered to be the major factor stabilizing biopolymeric structures. However, solvent reorganization around polar groups is an event thermodynamically more unfavorable than solvent reorganization around nonpolar groups. Consequently, burial of polar groups with formation of complementary solute‐solute hydrogen bonds out of contact with water is an energetically favorable process that also provides a major force driving macromolecular association and folding. In contrast to nonpolar groups, polar groups may form their complementary intra‐ or intersolute hydrogen bonds out of contact with water only provided that an appropriate solute structure has been formed with properly positioned hydrogen bond donors and acceptors. Formation of such structures is disfavored entropically and may not be possible due to steric reasons. However, the interior of a folded protein, α‐helices and β‐sheets, double helical nucleic acid structures, and protein‐ligand interfaces all provide rigid matrices where polar groups may form their complementary hydrogen bonds. For these structures, the inward drive of polar groups represents a considerable stabilizing factor. © 2003 Wiley Periodicals, Inc. Biopolymers 70: 492–496, 2003
Meta-analysis of randomized clinical trials comparing open and laparoscopic inguinal hernia repair
Authors: Memon M A , Cooper N J , Memon B , Memon M I , Abrams K R 
Published: November 2003

AbstractBackgroundThe aim was to conduct a meta-analysis of the randomized evidence to determine the relative merits of laparoscopic (LIHR) and open (OIHR) inguinal hernia repair.MethodsA search of the Medline, Embase, Science Citation Index, Current Contents and PubMed databases identified all randomized clinical trials that compared OIHR and LIHR and were published in the English language between January 1990 and the end of October 2000. The meta-analysis was prepared in accordance with the Quality of Reporting of Meta-analyses (QUOROM) statement. The six outcome variables analysed were operating time, time to discharge from hospital, return to normal activity and return to work, postoperative complications and recurrence rate. Random effects meta-analyses were performed using odds ratios and weighted mean differences.ResultsTwenty-nine trials were considered suitable for meta-analysis. Some 3017 hernias were repaired laparoscopically and 2972 hernias were repaired using an open method in 5588 patients. For four of the six outcomes the summary point estimates favoured LIHR over OIHR; there was a significant reduction of 38 per cent in the relative odds of postoperative complications (odds ratio 0·62 (95 per cent confidence interval (c.i.) 0·46 to 0·84); P = 0·002), 4·73 (95 per cent c.i. 3·51 to 5·96) days in time to return to normal activity (P &lt; 0·001), 6·96 (95 per cent c.i. 5·34 to 8·58) days in time to return to work (P &lt; 0·001) and 3·43 (95 per cent c.i. 0·35 to 6·50) h in time to discharge from hospital (P = 0·029). There was a significant increase of 15·20 (95 per cent c.i. 7·78 to 22·63) min in the mean operating time for LIHR (P &lt; 0·001). The relative odds of short-term recurrence were increased by 50 per cent for LIHR compared with OIHR, although this result was not statistically significant (odds ratio 1·51 (95 per cent c.i. 0·81 to 2·79); P = 0·194).ConclusionLIHR was associated with earlier discharge from hospital, quicker return to normal activity and work, and significantly fewer postoperative complications than OIHR. However, the operating time was significantly longer and there was a trend towards an increase in the relative odds of recurrence after laparoscopic repair.
Comparison of P-POSSUM risk-adjusted mortality rates after surgery between patients in the USA and the UK
Authors: Bennett-Guerrero E , Hyam J A , Shaefi S , Prytherch D R , Sutton G L , Weaver P C , Mythen M G , Grocott M P , Parides M K 
Published: November 2003

Abstract

Background
The Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (POSSUM) criteria have been used to assess surgical risk in patients in the UK. The aim was to determine how applicable these criteria are to patients undergoing surgery in the USA.

Methods
Two cohorts of patients undergoing major non-cardiac surgery were followed prospectively in the USA (n = 1056) and the UK (n = 1539). Each patient was assigned a risk score for preoperative physiological status and operative severity using the established POSSUM criteria. Death in hospital was the primary outcome measure. For each patient a predicted risk of death was calculated from Portsmouth POSSUM (P-POSSUM) methodology using an established equation. The relationships between predicted and observed mortality rates in each cohort were investigated by means of multivariate logistic regression.

Results
Within each cohort, an increase in risk estimated by P-POSSUM predicted an increase in observed mortality rate (P &lt; 0·001). For any given risk level, however, mortality rates were significantly higher in the UK cohort than in the US cohort (odds ratio 4·50 (95 per cent confidence interval 2·81 to 7·19); Z = 6·25, P &lt; 0·001).

Conclusion
An increase in predicted risk, based on the P-POSSUM methodology, was associated with a higher mortality rate in patients from both countries. However, risk-adjusted mortality rates following major surgery were four times higher in the UK cohort. These marked differences warrant validation in a larger number of centres.
Symptoms and anal sphincter morphology following primary repair of third-degree tears
Authors: Davis K , Kumar D , Stanton S L , Thakar R , Fynes M , Bland J 
Published: November 2003

AbstractBackgroundApproximately 0·6–9 per cent of vaginal deliveries are complicated by third-degree tears. The precise impact of such injuries on future pelvic floor function remains unknown. The aim of this study was to define the extent of structural and physiological damage to the anal sphincter and to investigate anorectal function in women who sustained third-degree tears during vaginal delivery.MethodsFifty-six women who sustained a third-degree tear were investigated prospectively. All patients had a primary repair of the anal sphincter complex, and were assessed by anorectal physiology and endoanal ultrasonography at a mean of 3·6 months. Symptoms were assessed by direct personal interview and also by a self-completed questionnaire.ResultsForty-four patients had a persistent anal sphincter defect on ultrasonography. The mean resting and squeeze anal canal pressures were significantly lower in patients with a combined defect than in those in whom the repair was intact (P = 0·036 and P = 0·005 respectively). At direct interview three patients volunteered current symptoms of faecal and/or urinary incontinence whereas 32 reported bothersome symptoms on the questionnaire (P &lt; 0·001).ConclusionThe anatomical and physiological damage sustained during third-degree tears appears to be much greater than is generally appreciated. Primary repair does not provide lasting integrity. A self-administered questionnaire appears to be more accurate in defining the symptomatology.
Prevalence of multiple endocrine neoplasia type 1 in young patients with apparently sporadic primary hyperparathyroidism or pancreaticoduodenal endocrine tumours
Authors: Langer P , Wild A , Hall A , Celik I , Rothmund M , Bartsch D K 
Published: November 2003

Abstract

Background
The appropriate treatment for a sporadic endocrine tumour may be different from those that present as part of the multiple endocrine neoplasia type 1 (MEN1) syndrome. As primary hyperparathyroidism (pHPT) and pancreaticoduodenal endocrine tumours (PETs) are the most common organ manifestations of MEN1, the prevalence of germline mutations in the MEN1 gene was determined in young patients with apparently sporadic pHPT or PETs.

Methods
Eighteen of 705 patients with pHPT and 11 of 93 patients with PETs operated on between 1987 and 2001 had no family history of MEN1, only one organ manifestation and were aged 40 years or less at the time of diagnosis. Fifteen patients with pHPT and eight with PETs agreed to MEN1 gene mutation analysis, which was performed by single-strand conformational variant analysis and direct DNA sequencing.

Results
Two of 15 patients (13·3 (95 per cent confidence interval (c.i.) 1·6 to 40·4) per cent) with apparently sporadic pHPT had a MEN1 germline mutation. Both mutations were found in patients with pHPT due to multiglandular disease, whereas the remaining 13 patients had a solitary adenoma. None of the eight patients with PETs carried a MEN1 germline mutation.

Conclusion
Sporadic pHPT due to multiglandular disease in patients younger than 40 years may represent the first organ manifestation of MEN1 despite a negative family history.
Decline in admission rates for acute appendicitis in England
Authors: Kang J Y , Hoare J , Majeed A , Williamson R C N , Maxwell J D 
Published: November 2003

Abstract

Background
The incidence of acute appendicitis declined in western countries between the 1930s and the early 1990s. The aim of this study was to determine time trends in hospital admissions for acute appendicitis in England between 1989–1990 and 1999–2000, and in population mortality rates for appendicitis from 1979 to 1999.

Methods
Hospital Episode Statistics for admissions were obtained from the Department of Health and mortality data from the Office for National Statistics.

Results
Between 1989–1990 and 1999–2000, age-standardized hospital admission rates for acute appendicitis decreased by 12·5 per cent in male patients and by 18·8 per cent in female patients. The proportions of admissions that resulted in operation remained stable. Admission rates for non-specific mesenteric lymphadenitis fell. Admission rates for abdominal pain increased between 1989–1990 and 1995–1996, at which time the International Classification of Diseases codes changed. Between 1995–1996 and 1999–2000, admission rates for abdominal pain declined. Analysis of age-specific admission rates for acute appendicitis and abdominal pain from 1989–1990 to 1995–1996 showed that the decline in acute appendicitis could not be accounted for by a change in diagnostic practice. Mortality rates for acute appendicitis remained stable over the study period.

Conclusion
Admission rates for acute appendicitis declined over the study period. This decline cannot be explained by reclassification.
Ischaemia–reperfusion is an event triggered by immune complexes and complement
Authors: Chan R K , Ibrahim S I , Verna N , Carroll M , Moore F D , Hechtman H B 
Published: November 2003

AbstractBackgroundReperfusion injury is a common clinical problem that lacks effective therapy. Two decades of research implicating oxygen free radicals and neutrophils has not led to a single successful clinical trial.MethodsThe aim was to review new clinical and preclinical data pertaining to the alleviation of reperfusion injury. A review of the literature was undertaken by searching the MEDLINE database for the period 1966–2003 without language restrictions.Results and conclusionEvidence now points to complement and immune complexes as critical players in mediating reperfusion injury. Ischaemia is postulated to induce a phenotypical cellular change through the surface expression of a neoantigen. Preformed circulating natural IgM antibodies are then trapped and complement is activated. Final events leading to reperfusion injury include formation of the membrane attack complex and mast cell degranulation.
Chiral Bis(amino alcohol)oxalamide Gelators—Gelation Properties and Supramolecular Organization: Racemate versus Pure Enantiomer Gelation
Authors: Makarević Janja , Jokić Milan , Raza Zlata , Štefanić Zoran , Kojić‐Prodić Biserka , Žinić Mladen 
Published: November 2003

AbstractFour new chiral bis(amino alcohol)oxalamides (1–4: amino alcohol=leucinol, valinol, phenylglycinol, and phenylalaninol, respectively) have been prepared as low‐molecular‐weight organic gelators. Their gelation properties towards various organic solvents and mixtures were determined and these were then compared to related bis(amino acid) oxalamide gelators. Spectroscopic (FTIR, 1H NMR) and X‐ray diffraction studies revealed that the primary organization motif of (S,S)‐1 and racemate 1 (rac‐1) in lipophilic solvents involved the formation of inverse bilayers. The X‐ray crystal structure of (S,S)‐1 also shows this type of bilayer organization. The crystal structure of rac‐2 reveals meso bilayers of hydrogen‐bonded aggregates. Within the bilayers formed, the gelator molecules are connected by cooperative hydrogen bonding between oxalamide units and OH groups, while the interbilayer interactions are realized through lipophilic interactions between the iBu groups of leucinol. Oxalamide meso‐1 lacks any gelation ability and crystallizes in monolayers. In dichloromethane rac‐1 forms an unstable gel; this is prone to crystallization as a result of the formation of symmetrical meso bilayers. In contrast, in aromatic solvents rac‐1 forms stable gels; this indicates that enantiomeric bilayers are formed. Oxalamide rac‐1 is capable of gelling a volume of toluene three times larger than (S,S)‐1. A tranmission electron microscopy investigation of rac‐1 and (S,S)‐1 toluene gels reveals the presence of thinner fibers in the former gel, and, hence, a more compact network that is capable of immobilizing a larger volume of the solvent. The self‐assembly of these types of gelator molecules into bilayers and subsequent formation of fibrous aggregates can be explained by considering the strength and direction of aggregate forces (supramolecular vectors) in three‐dimensional space.
Electron Density Investigation of a Push–Pull Ethylene (C14H24N2O2⋅H2O) by X‐ray Diffraction atT= 21 K
Authors: Forni Alessandra , Destro Riccardo 
Published: November 2003

AbstractThe electron charge distribution in a strongly twisted push–pull ethylene [PPE, 3‐(1,3‐diisopropyl‐2‐imidazolidinylidene)‐2,4‐pentanedione] has been determined by low temperature (T= 21 K) single‐crystal X‐ray diffraction analysis. The derived electronic properties are consistent with a zwitterionic molecule, as indicated by a charge transfer of 0.82(16) efrom thepushto thepullmoieties and a charge polarization of 0.29(7) eon the olefinic bond. A dipole moment of 12(3) D has been determined, which compares well with ab initio theoretical results in terms of both modulus and orientation. The second moments, which have also been obtained with good precision, characterize PPE as a highly quadrupolar molecule. The special electronic features of the molecule confer particular topological properties to the electron density distribution, as evidenced by comparison with “standard” organic molecules. The crystallographic asymmetric unit of the present system includes one water molecule, which is hydrogen bonded to PPE. Its topological properties have also been investigated, together with an analysis of the hydrogen bonds involved.
A new privacy and authentication protocol for end‐to‐end mobile users
Authors: Lee Cheng‐Chi , Yang Chao‐Chen , Hwang Min‐Shiang 
Published: November 2003

AbstractIn this papecr, we propose a new privacy and authentication scheme for end‐to‐end mobile users. There are three goals in our scheme. The first allows two end‐to‐end mobile users to communicate privately each other. The second allows two end‐to‐end mobile users to distribute a session key simply. The third allows two end‐to‐end mobile users to mutually authenticate. Copyright © 2003 John Wiley & Sons, Ltd.