bluuebunny/crossref_metadata_2025_split huggingface dataset:
Metallocene‐Catalyzed Solution Polymerization of Ethene at Elevated Pressure
Authors: Dornik Hans Peter , Luft Gerhard , Rau Alexander , Wieczorek Thomas 
Published: July 2003

AbstractThe kinetic of ethene polymerization catalyzed by (nBuCp)2ZrCl2/AliBu3/[Me2PhNH]+[B(C6F5)4]− has been investigated at 100 and 140 °C at pressures from 2 to 7 MPa. The initial polymerization rate Rp0 increases linearly with increasing catalyst concentration, whereas a second‐order dependence of Rp0 on the ethene concentration is found the number‐average molecular weight Mn increases with increasing ethene pressure (ethene concentration). The relation between Mn and ethene concentration can be explained by an equation based on a kinetic model involving a single center, two‐state catalyst system.Influence of the Zr concentration on the initial polymerization rate Rp0. pEthene = 7 MPa, solvent (toluene/ethene) = 275 mL.magnified imageInfluence of the Zr concentration on the initial polymerization rate Rp0. pEthene = 7 MPa, solvent (toluene/ethene) = 275 mL.
Sheet‐Molded Polyolefin Natural Fiber Composites for Automotive Applications
Authors: Pervaiz Muhammad , Sain Mohini M. 
Published: July 2003

AbstractThe use of natural fibers as reinforcing filler in thermoplastics is a relatively new application and has great potential in replacing glass fiber products in automotive industry. However, most of the research in this area has been focused primarily on flax fiber. In the first part of the work presented here, hemp fiber non‐woven mats are used exclusively in combination with a poly(propylene) matrix to study the mechanical properties of natural fiber mat thermoplastics (NMT) in the absence of binder. Film stacking was used as the method of preparation. The results show that hemp‐based NMT have comparable or even higher strength properties as compared with conventional flax‐based thermoplastics. A value of 63 MPa for the flexural strength is achieved at a fiber content of 64 wt.‐%. The influence of the compression ratio on the mechanical properties and density of NMT is also reported. A definite increase in strength is observed with increasing compression together with a much more uniform density profile. In the second part of this study, a unique combination of random hemp fibers, non‐woven mats and poly(propylene) films was employed in film stacking to evaluate strength properties and economic implications. The same fiber content (64 wt.‐%) was maintained in the final NMT by replacing 78 wt.‐% of the mats by random fibers. Preliminary tests reveal better mechanical properties especially in terms of impact energy, which is 50 to 100% higher, as compared with different mats‐only/poly(propylene) combinations. Further, a net saving of 40% in fiber cost is anticipated by replacing 78% non‐woven mats with an equivalent amount of random fibers. Overall results of this study indicate that hemp‐based NMT are promising candidates in automotive applications where high specific stiffness is required.Tensile Strength of different NMTs and GMT.magnified imageTensile Strength of different NMTs and GMT.
Mechanical and Thermal Properties of Poly(L‐lactide) Incorporating Various Inorganic Fillers with Particle and Whisker Shapes
Authors: Urayama Hiroshi , Ma Chenghuan , Kimura Yoshiharu 
Published: July 2003

AbstractPoly(L‐lactide) (PLLA) composites incorporating various inorganic fillers (ifR‐PLA) were prepared by the melt blending technique, and their mechanical and thermal properties were evaluated. The filler types influenced the mechanical properties of ifR‐PLA; for those incorporating particle‐ and whisker‐type fillers the tensile moduli were 3.1–3.7 and 3.7–4.5 GPa, respectively, and the flexural moduli were 4.1–4.8 and 4.8–6.1 GPa. It was found that the tensile strength and modulus, as well as the flexural modulus, of ifR‐PLA incorporating whisker‐type fillers increased in proportion to the volume percent of the fillers (Vf). The flexural strength of ifR‐PLA incorporating 9Al2O3 · 2B2O3 whiskers showed a similar increase, while that of ifR‐PLA incorporating CaCO3 whiskers showed a decrease with increasing Vf. This difference may be because the 9Al2O3 · 2B2O3 with its large aspect ratio kept its original fibrous shape, while the CaCO3 lost its fibrous shape during the blending process. However, the reinforcing effect of these fillers was relatively low compared with that known for the corresponding composites of the conventional polymeric materials, probably because of the poor surface adhesion of PLLA to the fillers.Comparison of effect on storage moduli of different fillers.magnified imageComparison of effect on storage moduli of different fillers.
The Cross‐Linking of Polyurethane Incorporated with Starch Granules and their Rheological Properties: Influences of Starch Content and Reaction Conditions
Authors: Ha Seung‐Kyu , Broecker Hans‐Christoph 
Published: July 2003

AbstractTwo series of polyurethanes were synthesized using one‐ and two‐step reactions in a bulk phase at 175 °C with polycaprolactone diol, butane‐1,4‐diol, and 4,4‐diphenylmethane diisocyanate (MDI) in a suspension of starch granules to observe cross‐linking phenomena. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC) analysis, and complex viscosity η*(ω), storage G′(ω), and loss‐modulus G″(ω) as rheological measurements, were carried out to characterize the cross‐linking in the polyurethane incorporated with starch. SEM micrographs indicated that grafted polyurethane was cross‐linked between starch granules forming a three‐dimensional network. The plots of η* against ω, and log G′ against log G″ showed that the starch content increased cross‐linking, so as to induce gelation (G′ ≥ G″). However, the cross‐linked networking was decreased over the higher range of starch contents (> 33 wt.‐% for the low hard‐segment series, psb2m3 and > 27 wt.‐% for the high hard‐segment series, psb4m5). Cross‐linking is also enhanced in the high hard‐segment series compared to the low hard‐segment series. Increasing the catalyst concentration also enhanced the cross‐linking inside of the polyurethane phase.Plots of η* against ω for p7s3b4m5(OSR C0.01) and p7s3b4m5(TSR C0.01).magnified imagePlots of η* against ω for p7s3b4m5(OSR C0.01) and p7s3b4m5(TSR C0.01).
Mechanistic Investigation into the Unique Orientation Textures of Poly(vinylidene fluoride) in Blends with Nylon 11
Authors: Li Yongjin , Kaito Akira 
Published: July 2003

AbstractSelf‐seeded crystallization experiments were carried out to detect the mechanism of the unique orientation behavior of poly(vinylidene fluoride) (PVDF) in oriented PVDF/nylon 11 blends. It was found that primary nuclei have no effects on the final orientation textures adopted by PVDF. The results show that the PVDF crystal orientation in the oriented blends is determined in the early stage of crystal growth, thus a trans crystallization mechanism is preferred.Isothermal crystallization kinetics for the self‐seeded and non‐self‐seeded crystallization at 145 °C.magnified imageIsothermal crystallization kinetics for the self‐seeded and non‐self‐seeded crystallization at 145 °C.
An Improved Catalytic Method for Alkoxyamine Synthesis – Functionalized and Biradical Initiators for Nitroxide‐Mediated Radical Polymerization
Authors: Bothe Marc , Schmidt‐Naake Gudrun 
Published: July 2003

AbstractMn(salen)Cl was applied as a low‐cost catalyst for the formation of alkoxyamines from nitroxides and substituted styrenes. These “unimolecular initiators” for nitroxide‐mediated radical polymerization (NMRP) were synthesized using 2,2,6,6‐tetramethyl‐1‐piperidine‐1‐oxyl and 2,2,5‐trimethyl‐4‐phenyl‐3‐azahexane‐3‐oxyl. Functionalized alkoxyamines were obtained from 4‐vinylbenzyl chloride and 4‐vinylbenzyl alcohol. The divinyl compound 1,2‐bis(4‐vinylphenyl)ethane was converted to an alkoxyamine monomer and to bisaminooxy compounds, which can be used as “biradical initiators” for NMRP.Formation of alkoxyamines using Mn(salen)Cl as the catalyst.magnified imageFormation of alkoxyamines using Mn(salen)Cl as the catalyst.
Characterization of Chlorine‐, Amine‐ and Acrylate‐Functionalized TEMPO‐Capped and Bis‐TEMPO‐Capped Polystyrenes Using MALDI‐TOF MS
Authors: Bartsch Andreas , Dempwolf Wibke , Bothe Marc , Flakus Silke , Schmidt‐Naake Gudrun 
Published: July 2003

AbstractChlorine‐functionalized TEMPO‐capped polystyrenes were investigated using the matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) technique. Amine‐ and acrylate‐functionalized agents and bifunctional TEMPO‐capped polystyrene were also analyzed to demonstrate the applicability of this method. Using this technique allowed to analyze the conversion of the chlorine function to an acrylate function, which was previously difficult to detect with other methods.MALDI‐TOF mass spectrum of a polystyrene described in this article, as obtained with DHB as the matrix.magnified imageMALDI‐TOF mass spectrum of a polystyrene described in this article, as obtained with DHB as the matrix.
Correlation between Polymer Particle Size and in‐situ NIR Spectra
Authors: Reis Marlon M. , Araújo Pedro H. H. , Sayer Claudia , Giudici Reinaldo 
Published: July 2003

AbstractThis work describes the estimation of polymer particle size from NIR spectra collected in situ and online in an automated reactor. A good linearity between spectra and average polymer particle diameter is found. The multivariate linear model is also tested with an independent data set not used in the model fitting. Despite varying monomer and polymer concentrations and temperature changes along the process, the average particle sizes are well predicted and can be monitored by NIR spectroscopy during emulsion polymerization reactions.Evolution of average particle diameter with polymer content for three different BA/Sty semi‐continuous emulsion polymerization reactions. Open symbols correspond to spectra used in the model fitting and solid symbols to the test data set. The different symbol types correspond to the three different reactions.magnified imageEvolution of average particle diameter with polymer content for three different BA/Sty semi‐continuous emulsion polymerization reactions. Open symbols correspond to spectra used in the model fitting and solid symbols to the test data set. The different symbol types correspond to the three different reactions.
Ring and Disk‐Like CdSe Nanoparticles Stabilized with Copolymers
Authors: Wagih Fahmi Amir , Oertel Ulrich , Steinert Volker , Froeck Christian , Stamm Manfred 
Published: July 2003

AbstractCdSe nanoparticles stabilized with the amphiphilic diblock copolymer polystyrene‐block‐poly(4‐vinylpyridine) were spread from toluene dispersion on the water surface. Monolayers could be transferred onto solid substrates using the Langmuir‐Blodgett technique. By means of atomic force and scanning electron microscopy highly symmetric ring and disk‐like structures with diameters ranging between 150 nm and 1200 nm were observed.AFM image of a mixed monolayer of copolymer 12 and CdSe nanoparticles stabilized with polystyrene‐block‐poly(4‐vinylpyridine).magnified imageAFM image of a mixed monolayer of copolymer 12 and CdSe nanoparticles stabilized with polystyrene‐block‐poly(4‐vinylpyridine).
New Star‐Shaped Metallo‐Polymeric Chromophores
Authors: Viau Lydie , Even Michael , Maury Olivier , Haddleton David M. , Le Bozec Hubert 
Published: July 2003

AbstractThe synthesis of new star‐shaped polymers, prepared by atom transfer radical polymerization of methyl methacrylate with tris(dialkylaminostyryl‐2,2′‐bipyridine) zinc(II) and iron(II) metalloinitiators, is reported. Their thermal and optical (absorption and emission) properties are discussed.Structure of the star‐shaped polymers.magnified imageStructure of the star‐shaped polymers.
Alternating Diene Metathesis Polycondensation (ALTMET) – A Versatile Tool for the Preparation of Perfectly Alternating AB Copolymers
Authors: Demel Sandra , Slugovc Christian , Stelzer Franz , Fodor‐Csorba Katalin , Galli Giancarlo 
Published: July 2003

AbstractPerfectly alternating copolymers can be synthesised by reacting diacrylates with terminal dienes using alternating diene metathesis polycondensation (ALTMET). This novel method is very versatile and allows preparation of diverse structures of polymers, including main‐chain liquid crystalline polymers.Main‐chain liquid crystalline polymer obtained by ALTMET.magnified imageMain‐chain liquid crystalline polymer obtained by ALTMET.
State‐of‐the‐Art and Future of Combinatorial Polymer Research: 2nd DPI Workshop on Automated Synthesis and High‐Throughput Experimentation in Polymer and Materials Research
Authors: Schubert Ulrich S. , Meier Michael A. R. 
Published: July 2003

AbstractThis section contains reports on topical conferences. Reports are usually written at the request of the editorial office, but unsolicited contributions are also welcome. Suggestions should be sent to the editorial office of the Macromolecular journals, preferably by E‐mail to macromol@wiley‐vch.de.
Proteomic tools for quantitation by mass spectrometry
Authors: Lill Jennie 
Published: June 2003

Abstract

I.
Introduction
182

II.
Relative Quantitation
184

A.  2‐D Gel Electrophoresis
184

B.  Metabolic Isotopic Labeling
185

1.  15N
185

2.  13C Enrichment and Depletion
185

3.  Select Isotopic Amino Acid Incorporation
186

C.  Chemical Labeling
186

1.  Labeling During Proteolysis: 18O Incorporation During Enzymatic Cleavage
186

2.  Isotopic Tags—Isotope‐Codes Affinity Tag Reagents (ICAT)
187

3.  Isotopic Tags—Acid‐Labile Isotope‐Coded Extractants (ALICE)
188

4.  Lysine‐Specific Labeling
189

5.  Phosphoserine‐ and Phosphothreonine‐Specific Labeling
189

6.  N‐Terminus Labeling
189

a.  Nicotinyl‐N‐hyxroxysuccinimide
189

b.  Acylation
189

c.  Amidination‐quantitation using enhanced signal tags (QUEST)
190

d.  C‐terminusu labeling
190

D.  Differential Mass Mapping
190

III.
Absolute Quantitation
191

IV.
Choice of Instrumentation
191

V.
Overview, Discussion, and Future Directions
191

References

192

Techniques for the quantitation of proteins and peptides by mass spectrometry (MS) are reviewed. A range of labeling processes is discussed, including metabolic, enzymatic, and chemical labeling, and techniques that can be employed for comparative and absolute quantitation are presented. Advantages and drawbacks of the techniques are discussed, and suggestions for the appropriate uses of the methodologies are explained. Overall, the metabolic incorporation of isotopic labels provides the most accurate labeling strategy, and is most useful when an internal standard for comparative quantitation is needed. However, that technique is limited to research that uses cultured cells. © 2003 Wiley Periodicals, Inc., Mass Spec Rev 22:182–194, 2003; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/mas.10048
Quantitative high‐throughput analysis of drugs in biological matrices by mass spectrometry
Authors: Hopfgartner Gérard , Bourgogne Emmanuel 
Published: June 2003

Abstract

I.
Introduction
195

II.
Automated Sample Preparation
197

A.  Sample Collection
197

B.  Sample Pooling
197

C.  Off‐Line Sample Preparation
199

D.  On‐Line Sample Preparation
200

1.  Drirect Plasma Injection
201

a.  Turbulent flow and large‐particle high‐flow separation
202

b.  Restricted‐access media columns
203

2.  Sample Pre‐Treatment
203

III.
Sample Analysis
203

A.  Separation Techniques
203

B.  Serial Approaches
204

1.  Fast Chromatography
204

2.  Monolithic HPLC Columns
204

3.  Packed Column Supercritical Fluid Chromatography
205

C.  Parallel Approaches
205

IV.
Detection
207

A.  Mass Analyzer
207

B.  Matrix Suppression
208

C.  Metabolite Interferences
209

V.
Future Perspectives and Conclusions
209

Acknowledgments

210

References

210

To support pharmacokinetic and drug metabolism studies, LC–MS/MS plays more and more an essential role for the quantitation of drugs and their metabolites in biological matrices. With the new challenges encountered in drug discovery and drug development, new strategies are put in place to achieve high‐throughput analysis, using serial and parallel approaches. To speed‐up method development and validation, generic approaches with the direct injection of biological fluids is highly desirable. Column‐switching, using various packing materials for the extraction columns, is widely applied. Improvement of mass spectrometers performance, and in particular triple quadrupoles, also strongly influences sample preparation strategies, which remain a key element in the bioanalytical process. © 2003 Wiley Periodicals, Inc., Mass Spec Rev 22:195–214, 2003; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/mas.10050
The causes of mergers: tests based on the gains to acquiring firms' shareholders and the size of premia
Authors: Mueller Dennis C. , Sirower Mark L. 
Published: June 2003

AbstractDespite the large number of event studies of mergers that have been undertaken, considerable disagreement still exists over whether mergers increase the value of the merging firms, and if so why. Most event studies measure the average returns to the acquired and acquiring companies' shareholders separately, and based on these averages conclude either that mergers increase wealth, or that they reduce it. From this the authors go on to claim support either for a hypothesis about how mergers increase efficiency, or for one that claims they do not. This paper develops a methodology that uses the distribution of gains and losses across the two samples of firms, and their relationship to one another to test four hypotheses about why mergers occur: (1) the market‐for‐corporate‐control hypothesis, (2) the synergy hypothesis, (3) the managerial discretion hypothesis, and (4) the hubris hypothesis. The hypotheses are tested with data for 168 mergers between large companies from 1978 through 1990. Considerable support is found for the managerial discretion and hubris hypotheses, and some support is found for the market‐for‐corporate‐control hypothesis. Little or no support is found for the hypothesis that mergers create synergies and that shareholders of both the acquiring and acquired firms share gains from these synergies. Copyright © 2003 John Wiley & Sons, Ltd.
The profitability‐risk tradeoff of just‐in‐time manufacturing technologies
Authors: Callen Jeffrey L. , Morel Mindy , Fader Chris 
Published: June 2003

AbstractQualitative survey studies and a recent quantitative study by Callen et al. (2000) indicate that JIT manufacturing is more profitable than conventional non‐JIT manufacturing. This study tests the hypothesis that the excess profitability of JIT manufacturing just compensates for the additional operational risks of JIT technology relative to conventional manufacturing. An often‐suggested alternative hypothesis is that JIT manufacturing dominates conventional manufacturing in reducing costs and increasing revenues and that risk is not an issue. The multivariate results unambiguously reject the hypothesis that excess JIT profits are compensation for additional risk. We find that profitability is inversely related to risk, especially for JIT plants. We also find that the JIT plants in our sample are more profitable than non‐JIT plants even after adjusting for risk, consistent with the dominance argument. Copyright © 2003 John Wiley & Sons, Ltd.
Productive efficiency of English football teams—a data envelopment analysis approach
Authors: Haas Dieter J. 
Published: June 2003

AbstractThis paper investigates how close to their potential English Premier League Clubs play. Using a deterministic Data Envelopment Analysis Approach, the productive efficiency of 20 teams in the 2000/2001 season is measured and weaknesses of individual teams are disclosed. The sensitivity of results is analyzed with regard to different model specifications and variable combinations. Copyright © 2003 John Wiley & Sons, Ltd.
An economic analysis of Japanese distribution systems
Authors: Utaka Atsuo 
Published: June 2003

AbstractWe investigate Japanese distribution systems by using a successive monopoly model in which the dealer can increase demand for the commodity. We compare the Tatene system (TS) with the open price system (OPS), and show that in cases where the dealer's power of sales promotion is small (large), the total profits obtained through TS become larger (smaller) than those of the OPS. This result justifies the actual change from TS to OPS from an economic point of view. Copyright © 2003 John Wiley & Sons, Ltd.
Mast cells in the rat brain synthesize gonadotropin‐releasing hormone
Authors: Khalil Mona H. , Silverman Ann‐Judith , Silver Rae 
Published: June 2003

AbstractMast cells occur in the brain and their number changes with reproductive status. While it has been suggested that brain mast cells contain the mammalian hypothalamic form of gonadotropin‐releasing hormone (GnRH‐I), it is not known whether mast cells synthesize GnRH‐I de novo. In the present study, mast cells in the rat thalamus were immunoreactive to antisera generated against GnRH‐I and the GnRH‐I associated peptide (GAP); mast cell identity was confirmed by the presence of heparin, a molecule specific to mast cells, or serotonin. To test whether mast cells synthesize GnRH‐I mRNA, in situ hybridization was performed using a GnRH‐I cRNA probe, and the signal was identified as being within mast cells by the binding of avidin to heparin. GnRH‐I mRNA was also found, using RT‐PCR, in mast cells isolated from the peritoneal cavity. Given the function of GnRH‐I in the regulation of reproduction, changes in the population of brain GnRH‐I mast cells were investigated. While housing males with sexually receptive females for 2 h or 5 days resulted in a significant increase in the number of brain mast cells, the proportion of mast cells positive for GnRH‐I was similar to that in males housed with a familiar male. These findings represent the first report showing that mast cells synthesize GnRH‐I and that the mast cell increase seen in a reproductive context is the result of a parallel increase in GnRH‐I positive and non‐GnRH‐I positive mast cells. © 2003 Wiley Periodicals, Inc. J Neurobiol 56: 113–124, 2003
Vibration signals from the FT joint can induce phase transitions in both directions in motoneuron pools of the stick insect walking system
Authors: Bässler Ulrich , Sauer Arne E. , Büschges Ansgar 
Published: June 2003

AbstractThe influence of vibratory signals from the femoral chordotonal organ fCO on the activities of muscles and motoneurons in the three main leg joints of the stick insect leg, i.e., the thoraco–coxal (TC) joint, the coxa–trochanteral (CT) joint, and the femur–tibia (FT) joint, was investigated when the animal was in the active behavioral state. Vibration stimuli induced a switch in motor activity (phase transition), for example, in the FT joint motor activity switched from flexor tibiae to extensor tibiae or vice versa. Similarly, fCO vibration induced phase transitions in both directions between the motoneuron pools of the TC joint and the CT joint. There was no correlation between the directions of phase transition in different joints. Vibration stimuli presented during simultaneous fCO elongation terminated the reflex reversal motor pattern in the FT joint prematurely by activating extensor and inactivating flexor tibiae motoneurons. In legs with freely moving tibia, fCO vibration promoted phase transitions in tibial movement. Furthermore, ground vibration promoted stance–swing transitions as long as the leg was not close to its anterior extreme position during stepping. Our results provide evidence that, in the active behavioral state of the stick insect, vibration signals can access the rhythm generating or bistable networks of the three main leg joints and can promote phase transitions in motor activity in both directions. The results substantiate earlier findings on the modular structure of the single‐leg walking pattern generator and indicate a new mechanism of how sensory influence can contribute to the synchronization of phase transitions in adjacent leg joints independent of the walking direction. © 2003 Wiley Periodicals, Inc. J Neurobiol 56: 125–138, 2003