bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthese und charakterisierung von linearem poly(iminoethylen)
Authors: Bartulín Juan , Rivas Bernabé Luis , Rodríguez‐Baeza Mario , Angne Ursula 
Published: April 2003

AbstractLinear poly(iminoethylene) was synthetised by cationic polymerization of 2‐methyl‐2‐oxazoline using BF3O(C2H5)2, SnCl4, and CH3COBF4 as initiators and in the presence or absence of CH3CN. The resulting product, poly(N‐acetyliminoethylene), was then hydrolysed in basic medium. The resulting poly(iminoethylene) was identified and characterized by 1H NMR, 13C NMR, X‐ray diffraction, and differential scanning calorimetry (DSC). The synthetised polymer will be used as a polymeric support in ionic‐exchange resins as well as in macromolecular pesticides.
Polymerization of isobutene by the inifer technique, 1. Low molecular weight products using 1,4‐bis(1‐chloro‐1‐methylethyl)benzene/BCl3 as initiator
Authors: Nuyken Oskar , Pask Stephen D. , Vischer Axel 
Published: April 2003

AbstractThe cationic polymerization of isobutene by the “inifer”‐technique was studied. Preliminary experiments are described which suggest that useful polymer can be prepared only when BCl3 is rapidly added to the premixed monomer/inifer mixture and that such polymerizations do not go to completion. Some questions regarding the mechanism are discussed and remain open.
Grafting of N‐vinylpyrrolidone onto segmented polyurethane initiated by 2,2′‐azoisobutyronitrile
Authors: Egboh Sunday H. , George Maurice H. , Barrie James A. , Walsh David J. 
Published: April 2003

AbstractAn unsaturated segmented polyurethane was prepared from cis‐2‐butene‐1,4‐diol, poly(ethylene glycol), butane‐1,4‐diol, and methylene bis(4‐phenyl isocyanate). Graft copolymerization of N‐vinylpyrrolidone onto the segmented polyurethane was studied using 2,2′‐azoisobutyronitrile (AIBN) as initiator in DMF as solvent. The graft copolymers were isolated from the homopolymer and the ungrafted polyurethane by selective solvent extraction. The effect of reaction time, temperature, and of monomer and initiator concentrations on the degree of grafting was also investigated. The percent grafting was enhanced with increasing [AIBN] up to 40 mmol.dm‐3, but then decreased at higher concentrations. An explanation based on complex formation between the monomer and the urethane linkages in polyurethane is suggested.
Models and mechanism of the formation of poly(thio‐1,4‐phenylene)
Authors: Koch Wolfgang , Heitz Walter 
Published: April 2003

AbstractThe formation of poly(thio‐1,4‐phenylene) does not proceed by a normal polycondensation process. The mechanism was found to be a one‐electron‐transfer process with radical‐cations as reactive intermediates. This mechanism explains the formation of disulfides as side products. It could be shown in a model reaction that more than 20% of the disulfide can be formed in the early stage of the reaction and that the formation of disulfide is a reversible reaction, which explains the decrease of its content with the reaction time. Oligomers up to the octamer were prepared in a stepwise synthesis. The melting point and the enthalpy of melting of poly(thio‐1,4‐phenylene), crystallized as extended chains, were extrapolated from the melting points of the oligomers. From the UV spectra it could be deduced that the length of conjugated segments in solution is low.
Polymerization of ethylene oxide catalyzed by triphenylstibine oxide
Authors: Nomura Ryoki , Shiomura Yasuro , Ninagawa Akira , Matsuda Haruo 
Published: April 2003

AbstractPolymerization of ethylene oxide (EO) and propylene oxide (PO) catalyzed by two types of triphenylstibine oxide ((C6H5)3SbO, TPSO) was investigated. The polymeric and high melting point triphenylstibine oxide (TPSOa) was found to be active, but it shows a long induction period in the polymerization at 80°C. During the induction period, TPSOa is probably cleaved into an active antimony species by interaction with EO. TPSOa is activated by addition of some O‐containing compounds such as ethanol, 1,4‐dioxane, or water. Monomeric and low melting point triphenylstibine oxides (TPSOb and TPSOc) were found to be inactive. Their activity markedly increases by addition of Lewis bases such as triphenylphosphine. The difference in the activity of TPSOa and TPSOb or TPSOc is considered to result from differences in aggregation.
Vinyl polymers with aromatic substituents, 2. Polymerization of 9‐allylanthracene and structures of the polymers
Authors: Dumitrescu Svetlana , Grigoraş Mircea , Simionescu Cristofor I. 
Published: April 2003

AbstractRadical, cationic, and Ziegler‐Natta polymerizations of 9‐allylanthracene (1) were carried out. The radical polymerization was found to be an inefficient method leading to oligomers with complex structure. Reaction of initiator radicals and growing macroradicals with the anthryl group or with the allylic hydrogen leads to resonance stabilized radicals which stop the polymerization. The cationic and Ziegler‐Natta polymerizations gave a copolymer with 9‐anthrylmethylethylene units (8) (from normal 1,2 addition) and 9,10‐anthrylenepropylene units (11) (from the electrophilic attack of carbocations at the aromatic nucleus). Low polymerization temperatures lead to a preference for the alkylation reaction.
Estimation of the characteristic ratio of polyacrylamide in water and in a mixed theta‐solvent
Authors: Bohdanecký Miloslav , Petrus Vladimír , Sedláček Blahoslav 
Published: April 2003

AbstractSolutions of nine polyacrylamide fractions (3300 g · mol−1 < molar mass < 800 000 g · mol−1) in water at 25°C and in a mixed theta‐solvent (Water‐methanol, 3:2 parts by volume) at 20°C were studied by light scattering, sedimentation and viscometry. From measurements in water the characteristic ratio was estimated to be C∞ = 8,5. A somewhat higher value was obtained in the mixed solvent. An explanation of the large span of the reported C∞ values is proposed.
Determination of the polarization direction of the UV bands of chromophore molecules by use of cyclodextrins
Authors: Kobayashi Nagao , Minato Shingo , Osa Tetsuo 
Published: April 2003

AbstractCyclodextrins (CDxs) were utilized to determine the polarization direction in the UV bands of aromatic compounds. By choosing CDxs of suitable size for an axial inclusionAxial inclusion is the inclusion in which the long‐axis of arenes is parallel to the axis of the CDxs' cavity., the induced circular dichroism (ICD) bands of the included chromophore molecules are well resolved. Thus, except for the bands which consist of two or more perpendicularly polarized transitions with quite a different oscillator strength, the polarization direction is simply determined from the sign of ICD spectra: a plus sign is produced by transitions polarized parallel to the long‐axis while a negative sign by those polarized along the short‐axis. Besides being simple, this method is applicable to bands as short as 195 nm, since water is used as solvent. Thus, several UV bands of some compounds were recorded for the first time and even their polarization directions were determined. Merit and limitation of this method are discussed and compared with other methods.
Tight–loose coupling with customers: the enactment of customer orientation
Authors: Danneels Erwin 
Published: April 2003

AbstractThis article argues that tight linkages with customers present a paradox for the firm. The research question of this study is: What is the behavioral and cognitive process by which a firm establishes close links with its customers, and how can this process be both beneficial and detrimental? Existing theory and data from apparel retailers suggest that firms forge these tight links by enacting their customer environment. In the process of enactment, cognitions and actions reinforce each other and become increasingly focused. The tight coupling generated through enactment comes at the price of increased commitment and restricted vision. The author argues that firms should balance the natural process of tight coupling with a deliberate effort at loose coupling, and draws implications for further research on the organization‐environment interface. Copyright © 2003 John Wiley & Sons, Ltd.
Gastroschisis: can prenatal sonography predict neonatal outcome?
Authors: Japaraj R. P. , Hockey R. , Chan F. Y. 
Published: April 2003

AbstractObjectiveGastroschisis is associated with significant neonatal morbidity, and occasionally mortality. Previous studies looking at ways to prognosticate this condition by antenatal ultrasound have shown conflicting results. The aim of this study was to evaluate the usefulness of prenatal sonographic parameters to predict neonatal outcome of gastroschisis.MethodsThe charts, photographs, and videotapes of all fetuses with gastroschisis who were assessed during pregnancy at the Mater Mothers' Hospital, Brisbane over an 8.5‐year period (Jan 1993—May 2001) were reviewed. Adverse neonatal outcome was defined as death, severe bowel complications (atresia, perforation, necrotic segments), need for multiple bowel operations, or a combination of these. Various sonographic parameters assessed included: gestation at first diagnosis, maximum bowel diameter, maximum bowel wall thickness, presence of other anomalies, evidence of growth restriction, and polyhydramnios.ResultsForty‐five patients met the entry criteria during the study period. Six neonates died, 12 had severe bowel complications, and 15 had a combination of the adverse outcomes. Polyhydramnios was most significantly associated with severe bowel complications, with a likelihood ratio of 11.7 (P = 0.001). Other ultrasound parameters were not significantly correlated with neonatal outcome.ConclusionMost standard ultrasound parameters assessed antenatally in fetal gastroschisis were not significantly associated with adverse neonatal outcome, except for polyhydramnios, which was strongly predictive of severe bowel complications in the neonatal period. This information is important both for parents and for health professionals managing pregnancies with fetal gastroschisis. Copyright © 2003 ISUOG. Published by John Wiley & Sons, Ltd.
Prospective cohort study showing changes in the monthly incidence of Pneumocystis carinii pneumonia
Authors: Lubis N , Baylis D , Short A , Stebbing J , Teague A , Portsmouth S , Bower M , Nelson M , Gazzard B 
Published: April 2003

Abstract
Pneumocystis carinii pneumonia (PCP) remains a serious opportunistic infection in HIV infected individuals. Seasonal changes in climate are associated with changes within individual susceptibility to infection. The possibility of monthly variability in the incidence of PCP was therefore examined by means of a cohort study of a database of 8640 HIV infected individuals attending the Chelsea and Westminster Hospital. There were 792 cases of PCP diagnosed since 1985. A marked decline was observed in the incidence of PCP in mid-1992 coincident with the introduction of PCP prophylaxis. There was a further decline in 1996 after the introduction of highly active antiretroviral therapy. Despite no significant monthly variation in the mean attendance to clinic and CD4 count, both new and all cases of PCP were higher in January than in other months (15.9% and 14.5% of all cases, respectively). A correlation with low rainfall in January and new cases of PCP was observed. These data are consistent with an influence of climatic conditions on the presentation of PCP. The diagnosis of PCP is more common in winter months suggesting that this is a transmissible infection.
Electrocardiographic Changes Related to Parasympathetic Tone during Right Coronary Angioplasty
Authors: Nii Takanobu , Tsuchiya Yoshihiro , Shirai Kazuyuki , Arakawa Kikuo 
Published: April 2003

The role of basal parasympathetic tone in reducing the heart rate and causing electrocardiographic (ECG) changes during right coronary angioplasty was evaluated in 19 patients with angina pectoris. To measure parasympathetic tone, time and frequency domain parameters of heart rate variability were assessed using 24 h of ambulatory ECG data recorded before angioplasty. There was an age-dependent reduction in heart rate. However, no parameters of heart rate variability were responsible for the changes in heart rate. In contrast, the degree of ST segment elevation during angioplasty correlated significantly with the high-frequency component of heart rate variability. Therefore, the increased parasympathetic tone, as assessed by spectral analysis, may augment the early ST segment elevation induced by right coronary occlusion.
Effects on Heart Rate Variability of Isosorbide-5-Mononitrate and Metoprolol in Patients with Recent Onset of Angina pectoris
Authors: Wennerblom Bertil , Lurje Leon , Westberg Staffan , Johansson Mats , Lomsky Milan , Vahisalo Rein , Hjalmarson Åke 
Published: April 2003

<b>Background:</b> β-Blockers reduce sympathetic tone, increase vagal tone and improve prognosis in ischaemic heart disease. Nitroglycerin, being a vasodilator, may theoretically have an opposite effect and worsen the prognosis. The purpose of the present study was to analyse heart rate variability (HRV), which reflects autonomic tone, in angina patients on isosorbide-5-mononitrate (IS-5-MN) and/or metoprolol. <b>Methods and Results:</b> Thirty-two patients (32–81 years old), with recently developed angina (median duration: 3 months), showing no other disease and on no drugs, were Holter-monitored 24–48 h at baseline and after 4–5 days on IS-5-MN (mean daily dose: 33 mg), on metoprolol (mean daily dose: 184 mg) and on the combined treatment. Recordings were analysed on the Marquette Series 8000 Holter scanner. Both IS-5-MN and metoprolol significantly reduced myocardial ischaemia (ST integral) and ventricular tachycardias. Metoprolol induced significant changes in the following parameters (baseline versus metoprolol): high-frequency peak 9 ± 4 versus 11 ± 4 ms (p < 0.001), low-to-high frequency ratio 2.5 ± 0.6 versus 1.9 ± 0.6 (p < 0.0001), root mean square of RR interval difference 23 ± 7 versus 31 ± 9 ms (p < 0.0001), RR intervals differing more than 50 ms from the preceding one 4.8 ± 3.9 versus 10.0 ± 7.0% (p < 0.0001), mean of all 5-min standard deviations 50 ± 12 versus 56 ± 11 ms (p < 0.001) and mean RR interval 819 ± 90 versus 1,019 ± 120 ms (p < 0.00001). The combined treatment caused approximately the same HRV changes as metoprolol alone. IS-5-MN had no significant effect on any HRV parameter, neither alone nor in combination with metoprolol. <b>Conclusion:</b> A clinically effective dose of metoprolol had potentially positive effects on HRV with increase in vagal and decrease in sympathetic tone while IS-5-MN had no effect on HRV, neither positive nor negative, neither alone nor in combination with metoprolol.
Diffuse Narrowing of Coronary Arteries in Diabetic Patients: The Earliest Phase of Coronary Artery Disease
Authors: Mosseri Morris , Nahir Menachem , Rozenman Yoseph , Lotan Chaim , Admon Dan , Raz Itamar , Gotsman Mervyn S. 
Published: April 2003

Coronary arteries in diabetic patients appear to be narrower than in normal subjects, but this has not been examined systematically. To investigate this hypothesis we reviewed the data of 711 consecutive patients with angiographically ‘normal coronary arteries’. Excluded were patients with valvular, myocardial or pericardial disease, and patients with hypertension or hyperlipidemia. Thirteen diabetic patients (10 men) and 22 nondiabetic persons (8 men) constituted the study and control groups, respectively. The diameters of the coronary arteries and their branches were measured and adjusted for body surface area. The sum of the proximal left anterior descending (LAD), circumflex and right coronary arteries (RCA) was calculated and defined as total coronary diameter (TCD). The sum of the distal LAD, first diagonal, first marginal and distal RCA was calculated and defined as total distal coronary diameter (dTCD). The clinical data of both groups were comparable. Adjusted TCD for body surface area was 5.4 ± 1.1 and 6.5 ± 1.1 mm/m<sup>2</sup> (p < 0.05) in diabetics and nondiabetics, respectively, and adjusted dTCD was 4.9 ± 1.2 and 6.1 ± 1.2 mm/m<sup>2</sup> (p = 0.01) in diabetics and normal subjects, respectively. Specific arteries and branches that were significantly smaller in diabetics included: left main coronary artery, distal LAD, first diagonal, proximal RCA, distal RCA, right ventricular branch, and posterolateral and posterior descending artery of RCA origin. Gender was not a confounding factor since the control group had a larger proportion of women and still larger arteries than the diabetic group. In conclusion, coronary arteries and their branches in diabetic patients have smaller diameters than normal subjects. This may be due to increased coronary tone, diffuse mild atherosclerosis or both.
Clinical Application of Two Novel Rapid Bedside Tests for the Detection of Cardiac Troponin T and Creatine Kinase-MB Mass/Myoglobin in Whole Blood in Acute Myocardial Infarction
Authors: Lüscher Michael S. , Ravkilde Jan , Thygesen Kristian 
Published: April 2003

The objective of this study was to determine whether two novel rapid bedside assays for whole-blood detection of cardiac troponin T and creatine kinase (CK)-MB mass/myoglobin could rule out or rule in acute myocardial infarction in patients with acute chest pain. Ninety-two patients with chest pain <12 h prior to admission were investigated. No difference in the cumulative sensitivity of the TropT test and the CARDIAC STATus test (CK-MB mass and myoglobin in combination) was found 6 h after admission (94 vs. 97%). The cumulative positive predictive value of the TropT test and CARDIAC STATus test 6 h after admission was 97 and 76%, respectively. The negative predictive value was 97% for the TropT test and 98% for the CARDIAC STATus test at this time point. Our data show that the rapid assays provide diagnostic as well as prognostic information shortly after admission.
Fuzzy Cluster Analysis of Positive Stress Tests: Comparison with Stress Echocardiography and Nuclear Perfusion Imaging in Patients with Triple Vessel and Left Main Coronary Disease
Authors: Peters Robert M. 
Published: April 2003

Fuzzy cluster analysis (FCA) was used to classify 166 outpatient positive treadmill stress tests as mildly, moderately, or severely abnormal. The method combines ST-segment change with five other stress test variables, and then computes a similarity measure to determine how closely each patient’s stress test resembles a prototypical mildly, moderately, or severely abnormal stress test. All patients had coronary angiography within 1 month of their stress tests. For the 45 patients with triple vessel disease (TVD), FCA classified 34 of these stress tests as severely abnormal (sensitivity = 75%). For the 22 patients with left main disease (LM), FCA classified 19 stress tests as severely abnormal (sensitivity = 86%). For the combined group with high-grade disease (TVD + LM), the sensitivity was 79%. A literature review shows that for stress echocardiography, multiple exercise-induced wall motion abnormalities have a sensitivity in the 70–80% range for patients with high-grade disease. For nuclear stress testing, the high-risk pattern of multiple reversible defects, with or without increased lung uptake, has a sensitivity in the range of 70–80% for patients with high-grade disease. Thus classification of a positive stress test as severely abnormal by FCA has a sensitivity comparable to high-risk patterns on stress echocardiography and nuclear stress testing in patients with TVD or LM.
Is There an Association of Atrial Septal Aneurysm with Arrhythmias?
Authors: Schneider Birke , Hofmann Thomas , Meinertz Thomas 
Published: April 2003

An association of atrial septal aneurysm (ASA) with cardiac arrhythmias has been described, and it has been suggested that undulating movements of the aneurysm initiate these arrhythmias, thereby causing arterial embolism. In this prospective study, all available electrocardiograms were reviewed and Holter monitoring was performed in 50 consecutive patients with echocardiographic diagnosis of ASA in order to assess the relationship between the occurrence of arrhythmias, morphologic characteristics of ASA and arterial embolism. Significant arrhythmias were identified in 26 (52%) patients (supraventricular n = 15, ventricular n = 6, both n= 5). Patients with arrhythmias were older (65 ± 12 vs. 54 ± 13 years, p = 0.005), frequently had palpitations (21/26 vs. 1/24, p < 0.0001) and an abnormal resting electrocardiogram (18/26 vs. 5/24, p < 0.001). By echocardiography, patients with arrhythmias had a larger left atrial (42.8 ± 7.4 vs. 35.3 ± 4.6 mm, p < 0.0001) and left ventricular enddiastolic diameter (53.8 ± 5.6 vs. 49.7 ± 4.1, p < 0.01) and a higher prevalence of associated mitral valve prolapse (12/26 vs. 4/24, p = 0.05). Potential cardiovascular causes for arrhythmia other than ASA were present in the great majority of patients with documented arrhythmias (24/26 vs. 7/24, p < 0.0001). The base diameter of ASA was larger in patients with arrhythmias (25.5 ± 6.2 vs. 21.4 ± 3.4, p < 0.01) and correlated with a larger left atrial diameter (r = 0.72, p < 0.0001). Concerning the mobility of ASA (maximal protrusion or phasic excursion), there was no significant difference between the two patient groups. Arterial embolism, however, predominantly occurred in ASA patients without arrhythmias (16/24 vs. 9/26, p < 0.05). In conclusion, the majority of patients with ASA and arrhythmias has underlying structural heart disease other than ASA which may be responsible for the arrhythmias observed. Arrhythmias in association with ASA do not play a major role as a mechanism for arterial embolism.
Incomplete Expansion of Palmaz-Schatz Stents despite High-Pressure Implantation Technique: Impact on Target Lesion Revascularization
Authors: Blessing Erwin , Hausmann Dirk , Sturm Matthias , Wolpers Hans-Georg , Amende Ivo , Mügge Andreas 
Published: April 2003

Improved expansion of stents using high-pressure implantation technique with subsequent antiplatelet therapy has improved patient outcome regarding the incidence of subacute stent thrombosis, bleeding complications and restenosis. Whether high-pressure implantation per se guarantees adequate stent expansion remains unclear. The aim of the study was to determine (1) stent expansion after high-pressure implantation technique and (2) whether stent expansion influences rate of target lesion revascularization within 6 months of follow-up. One hundred Palmaz-Schatz stents were implanted in 98 lesions (91 native vessels, 7 graft vessels) of 94 patients using high-pressure implantation technique (balloon pressure 12–20 atm). Stent expansion was investigated using intravascular ultrasound imaging (IVUS). Clinical follow-up of the patients was performed for 6 months. After implantation, stent/mean reference ratio was 0.81 ± 0.16. Noncompliant balloons used for implantation were chosen by angiographic criteria. Mean balloon/reference ratio was 1.08 ± 0.22; therefore balloons were not undersized. Additional balloon dilataion using higher pressures and/or larger balloons based on IVUS criteria and subsequent IVUS measurements was performed in 52 patients (55%); in these patients, stent expansion improved from 79 ± 16 to 91 ± 15% (mean ± SD) of average reference areas (p < 0.002). Within the 6 months’ clinical follow-up, target lesion revascularization was performed in 19 patients (20%). The only prognostic factors for the development of in-stent restenosis requiring target lesion revascularization were the vessel size (p < 0.05) and the extent of plaque distal to the stents (p < 0.05). Implantation of Palmaz-Schatz stents using high-pressure technique does not guarantee adequate stent expansion. Additional dilatation with higher pressures and/or larger balloons improves stent expansion. The size of the stented vessel and the extent of plaque at the distal stent end (residual outflow stenosis) but not the degree of stent expansion were predictors for target lesion revascularization within 6 months’ follow-up.