bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Unusual Characteristics of the Aerobic Oxidation of 3,4‐Dimethoxytoluene with Metal/Bromide Catalysts
Authors: Partenheimer Walt 
Published: October 2004

AbstractDMtoluene (3,4‐dimethoxytoluene; DM=3,4‐dimethoxy), a model compound for lignin oxidation, can be autoxidized in acetic acid using a Co/Mn/Br catalyst to its benzaldehyde in 51 mol % yield, and to its acid in 85–92 mol % yield. This synthesis is unusual because a number of unprecedented phenomena occur. 1) The rate of molecular oxygen reacting with the substrate is bi‐phasic, i.e., two maximum in the rate of reaction are observed. 2) In the first phase, all of the 3,4‐dimethoxytoluene is converted to intermediates, but very little to the carboxylic acid. 3) During the second maximum of activity, virtually all the intermediates are converted to the carboxylic acid with 95–100% mass accountability. 4) The rate of carbon monoxide and carbon dioxide formation is considerably higher during the second phase during which 5) 9–12% of methyl 3,4‐dimethoxybenzoate (the methyl ester of the benzoic acid) is formed. Mechanisms are suggested for these unusual phenomena.
Dendronized Poly(Ru‐BINAP) Complexes: Highly Effective and Easily Recyclable Catalysts For Asymmetric Hydrogenation
Authors: Deng Guo‐Jun , Yi Bing , Huang Yi‐Yong , Tang Wei‐Jun , He Yan‐Mei , Fan Qing‐Hua 
Published: October 2004

AbstractA new kind of dendronized polymeric chiral BINAP ligands has been synthesized and applied to the Ru‐catalyzed asymmetric hydrogenation of simple aryl ketones and 2‐arylacrylic acids. These dendronized poly(Ru‐BINAP) catalysts exhibited high catalytic activity and enantioselectivity, very similar to those obtained with the corresponding parent Ru(BINAP) and the Ru(BINAP)‐cored dendrimers. It was found that the pendant dendrons had a major impact on the solubility and the catalytic properties of the polymeric ligands. These polymeric catalysts could be easily recovered from the reaction solution by using solvent precipitation, and the reused catalyst showed no loss of activity or enantioselectivity.
Palladium‐Carbene Catalysts for Aerobic, Intramolecular Wacker‐Type Cyclisation Reactions
Authors: Muñiz Kilian 
Published: October 2004

AbstractA catalyst derived from in situ complexation of N‐heterocyclic carbenes to palladium bistrifluoroacetate promotes efficient intramolecular Wacker‐type cyclisation reactions under aerobic conditions. A variety of 2‐allylphenols undergo oxidative conversion to dihydrobenzofurans.
Changes in foot and mouth disease status and evolving world beef markets
Authors: Ekboir Javier , Jarvis Lovell S. , Sumner Daniel A. , Bervejillo José E. , Sutton William R. 
Published: October 2004

AbstractArgentina and Uruguay eradicated foot and mouth disease (FMD) in 2000 and 1995, and subsequently gained greater access to FMD‐free markets. Although both South American countries suffered from the reintroduction of FMD in late 2000, and had to temporarily cease exports to FMD‐free markets, they are expected to eradicate FMD again and will continue to increase exports to FMD‐free markets. This article analyzes the changes in international beef trade and, especially, in beef prices that are expected. We use a simulation model that captures the effects of market segmentation due to the FMD status and of the trade policies of exporting and importing countries. The ongoing realignment of trade flows has potential to significantly affect prices in both the FMD‐free and the FMD‐endemic segments of the world beef market. We demonstrate how growing beef exports from South America to FMD‐free markets interact with other on‐going changes in international beef markets. © 2002 Wiley Periodicals, Inc. [EconLit citations: Q110: Agriculture, Aggregate Supply and Demand; Q170: Agriculture, International Trade]
A repositioning strategy for olive oil in the UK market
Authors: Martínez Marian García , Aragonés Zulema , Poole Nigel 
Published: October 2004

AbstractDespite a rapid growth in olive oil consumption in recent few years, the culinary use of olive oil is still relatively new to UK consumers, and is still regarded as a set of particular attributes rather than as an everyday cooking oil. To increase sales and attract new users, olive oil needs to be seen by UK consumers as an ‘everyday’ cooking oil, and enter into direct competition with standard vegetable oils. To achieve this, we argue in this paper that standard olive oil needs to be repositioned and distanced from extra virgin olive oil in order to give customers sufficient cues to revise their opinions and consumption strategies. The objective of this paper is to report the results of a conjoint study as a tool for the analysis of attribute trade‐offs made in product choices by consumers, applied to the UK standard olive oil market. The ideal standard olive oil profile for 130 UK users of olive oil was found to be one packed in medium sized PET bottles (750 ml) at a price of £2.99. [Econ‐Lit citations: M310, M370]. © 2002 Wiley Periodicals, Inc.
Dyssegmental dysplasia, Silverman‐Handmaker type: Unexpected role of perlecan in cartilage development#
Authors: Arikawa‐Hirasawa Eri , Wilcox William R. , Yamada Yoshihiko 
Published: October 2004

AbstractDyssegmental dysplasia, Silverman‐Handmaker type (DDSH), is a lethal autosomal recessive form of dwarfism with characteristic anisospondylic micromelia. The remarkable similarities in the radiographic, clinical, and chondroosseous morphology of DDSH patients to those of perlecan‐null mice led to the identification of mutations in the perlecan gene (HSPG2) of DDSH. Perlecan, a large heparan sulfate proteoglycan, is expressed in various tissues and is a component of all basement membrane extracellular matrices. A chondrodysplasia phenotype caused by the loss of perlecan was unexpected, because cartilage does not have basement membranes. Insertion and splicing mutations in HSPG2 of DDSH were found that were predicted to create a premature termination codon. Immunostaining and biochemical analysis revealed that the mutant perlecan molecules were unstable and not secreted into the extracellular matrix. These results indicate that DDSH is caused by functional null mutations of HSPG2 and that perlecan is essential for cartilage development. Published 2002 Wiley‐Liss, Inc.
Endohedrale Zintl‐Ionen: intermetalloide Cluster
Authors: Fässler Thomas F. , Hoffmann Stephan D. 
Published: October 2004

AbstractTetrele sind aussichtsreiche Kandidaten für den Aufbau größerer Cluster. Jüngste Beispiele zeigen, dass solche Cluster durch ein Zentralatom stabilisiert werden können, wie durch [Pt@Pb12]2− belegt wird. Viele Salze der polyedrischen Anionen sind löslich, andere – in der Regel die höher negativ geladenen Vertreter – sind aber nur als quasi diskrete Einheiten in ionogenen Kristallverbänden (Zintl‐Phasen) oder als Baugruppen in intermetallischen Phasen beobachtet worden. In diesem Kurzaufsatz wird die Chemie der intermetalloiden Cluster im Zusammenhang mit den Systemen der endohedralen Zintl‐Ionen, Zintl‐Phasen und polyedrischen Baueinheiten intermetallischer Verbindungen sowie der heteroatomaren Gasphasen‐Spezies an ausgewählten Beispielen beleuchtet und im Kontext mit den Fortschritten auf dem Gebiet metalloider Cluster und (endohedraler) Fullerene und Fulleride diskutiert.
Endohedral Zintl Ions: Intermetalloid Clusters
Authors: Fässler Thomas F. , Hoffmann Stephan D. 
Published: October 2004

AbstractTetrels can be regarded as most promising candidates for the construction of larger clusters. Recent examples have shown that larger clusters are particularly stable if they contain interstitial atoms (e.g. [Pt@Pb12]2−). Many salts of the polyhedral anions are soluble, but a number of examples—usually those with higher charges—occur only as quasi‐discrete units in saltlike crystals (Zintl phases) or as building blocks in intermetallic phases. In this Minireview, the chemistry of intermetalloid clusters is reviewed with reference to the endohedral Zintl ions, Zintl phases, and polyhedral building blocks of intermetallic compounds, including heteroatomic species in the gas phase. We focus on selected examples and discuss the new findings in the context of recent advances in the field of metalloid clusters and (endohedral) fullerenes and fullerides.
Creep and shrinkage behavior of improved ultrathin polymeric films
Authors: Higashioji Takuji , Bhushan Bharat 
Published: October 2004

AbstractLong‐term creep‐deformation and shrinkage characteristics of improved ultrathin polymeric films for magnetic tapes are presented. These films include poly(ethylene terephthalate) (PET), poly(ethylene naphthalate) (PEN), and aromatic polyamide (ARAMID). PET film is currently the standard substrate used for magnetic tapes, and thinner tensilized‐type PET, PEN, and ARAMID have recently been used as alternate substrates with improved material properties. The thickness of the films ranges from 6.2 to 4.8 μm. More dimensional stability is required for advanced magnetic tapes, and the study of creep and shrinkage behavior is important for estimating the dimensional stability. Creep measurements were performed on all available substrates at 25, 40, and 55°C for 100 h. Based on these data, master curves were generated using time–temperature superposition to predict dimensional stability after several years. The amount of creep deformation is considerably smaller for ARAMID and tensilized‐type PET than for PEN, although Standard PET shows the largest amount of creep. In addition, creep measurements under high humidity also show similar trends. Shrinkage measurements at 55°C for 100 h show that the shrinkage of ARAMID is lower than that of PET and PEN. The relationship between the polymeric structure and dimensional stability are also discussed. Based on the creep and shrinkage behavior, ARAMID and tensilized‐type PET seem to be suitable for advanced magnetic tapes. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1477–1498, 2002; DOI 10.1002/app.10012
Structure and ionic conductive properties of polydioxolane–polyurethane‐based electrolytes
Authors: Zhu Weihua , Yang Bing , Wang Xinling , Wang Lei , Tang Xiaozhen , Yang Changzheng 
Published: October 2004

AbstractA series of polyurethanes (PUs) with different polyether soft segments [polydioxolane (PDXL), polyethylene glycol (PEG), or PDXL/PEG] were synthesized successfully, and solid polymer electrolytes based on PU/LiClO4 complexes were prepared. The relations between structure and the ionic conductive properties of the PU‐based electrolytes were investigated by means of Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical analysis, and complex impedance analysis. Results showed that the glass‐transition temperature (Tg) of PDXL–PU was lower than that of PEG–PU. Doped lithium perchlorate (LiClO4) salt could be dissolved well in soft segments of PDXL–PU. The ionic conductivity of the PDXL–PU/LiClO4 complex could reach a value of 2 × 10−5 S/cm at room temperature without the addition of an organic plasticizer. The system with PDXL/PEG as a soft segment had a higher Tg and a lower ionic conductivity than the one with PDXL as a soft segment. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 103–111, 2002
Isothermal gravimetric analysis of poly(trimethylene terephthalate)
Authors: Wang Xue‐Song , Li Xin‐Gui , Yan Deyue 
Published: October 2004

AbstractPoly(trimethylene terephthalate) was investigated by isothermal thermogravimetry in nitrogen at six temperatures, including 304, 309, 314, 319, 324, and 336°C. The isothermal data have been analyzed using both a peak maximum technique and an iso‐conversional procedure. Both techniques gave apparent activation energies of 201 and 192 kJ mol−1, respectively, for the isothermal degradation of poly(trimethylene terephthalate) in nitrogen. The decomposition reaction order is calculated to be 1.0. The natural logarithms of the frequency factor based on the peak maximum and the iso‐conversional techniques are 36 and 34 min−1, respectively, for poly(trimethylene terephthalate) decomposed isothermally in nitrogen. These isothermal kinetic parameters are in good agreement with those derived by the Kissinger technique on the basis of the dynamic thermogravimetric data reported elsewhere (209 kJ mol−1, 1.0 and 37 min−1). The isothermal decomposition of poly(trimethylene terephthalate) in nitrogen undergoes two processes, a relative fast degradation process in the initial period and a subsequent one with a slower weight‐loss rate. The former process may be due to the removal of ester groups, trimethylene groups, and aromatic hydrogen atoms from the chain of poly(trimethylene terethphalate). The latter one may be ascribed to the further pyrolysis of the carbonaceous char. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1600–1608, 2002; DOI 10.1002/app.10476
Melt‐spinning process of a tetrafluoroethylene– hexafluoropropylene copolymer
Authors: Uno Taiko , Miyata Seizo , Shirai Hirohusa 
Published: October 2004

AbstractAn industrial melt‐spinning process of tetrafluoroethylene– hexafluoropropylene copolymer (FEP) using an extruder was studied. The novel “spinneret,” having both a large‐diameter spinning nozzle and a high‐temperature vessel, was used to solve the problem of filament breakage on the spinning line caused by high melting viscosity of FEP. The extruder, with its long feed zone, was newly designed to function with a geared pump. The strength of fibers increased with drawing of as‐spun fiber. FEP fibers up to six denier were continuously produced through long‐run production. According to this new process, FEP fibers can be supplied for textile or industrial application. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2366–2371, 2002
Evolution of molecular weight and molecular weight distribution in ab initio styrene emulsion polymerizations using series of rigid rodlike cationic amphiphiles as surfactants
Authors: Zaragoza‐Contreras Erasto Armando , Navarro‐Rodríguez Dámaso , Maldonado‐Textle Hortensia 
Published: October 2004

AbstractThe emulsion polymerization of styrene is carried out using a series of unconventional rigid rodlike cationic surfactants (1‐[ω‐(4′‐methoxy‐4‐biphenylyloxy)alkyl]pyridinium bromides, PCX) of different lengths. The evolution of the molecular weight (M) and molecular weight distribution of the polymers is analyzed to obtain information about the chain stopping mechanism. Our results indicate that the M is strongly dependent on the initial surfactant concentration and is not dependent on the alkyl chain length. The Clay and Gilbert model [ln P(M) versus M plots] yields a concave‐up region at low molecular weights and a linear region that extends to high values. The slope of the linear region, which is related to the rate coefficient of the chain transfer to the monomer versus the propagation rate coefficient ratio, decreases as the PCX concentration increases. This behavior indicates that as the PCX concentration increases the chain transfer to monomer becomes the dominant chain stopping mechanism. On the other hand, the ln P(M) versus M plots of polymer samples taken at low and high conversions show differences in slope, particularly at low PCX concentration. It is likely that at low conversion the chain transfer to monomer competes with other chain stopping mechanisms that could be associated with a coagulative nucleation process. The formation of a high molecular weight fraction at low conversion supports this explanation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1513–1523, 2002; DOI 10.1002/app.10489
The effect of particle concentration of poly(p‐phenylene) on electrorheological response
Authors: Sohn Jeong‐In , Sung Jun H. , Choi Hyoung J. , Jhon Myung S. 
Published: October 2004

AbstractPoly(p‐phenylene) (PPP) particle‐based electrorheological (ER) fluids were prepared from FeCl3‐doped PPP and silicone oil. The effect of the volume fraction of PPP and applied electric field strength on ER response was investigated via measured rheological properties, including flow curve, shear viscosity, and yield stress. Furthermore, the yield stresses of the PPP‐based ER fluid, which exhibit the typical characteristics of a Bingham fluid, were measured. The yield stress data collapse on a universal scaling function proposed by Choi et al. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2397–2403, 2002
Synthesis and characterization of urethane/acrylate composite latex
Authors: Wu Limin , You Bo , Li Dan 
Published: October 2004

AbstractPolyurethane dispersion and urethane/acrylate composite latex were synthesized and characterized by using a particle size analyzer, gel permeation chromatograph (GPC), Fourier transform infrared spectroscopy coupled with attenuated total reflectance (FTIR‐ATR), dynamic mechanical analysis (DMA), and instron test machine. The amount of solvent and dimethylolpropionic acid (DMPA) used during synthesis of polyurethane resin straightway affected the average particle size and stability of aqueous polyurethane dispersion. The particle size of polyurethane dispersion had nothing to do with that of composite latex. FTIR‐ATR analyses displayed both air‐facing and substrate‐facing surfaces, containing more polyurethane component than the average composition. Some crosslinking reactions occurred in preparing urethane/acrylic composite latex, as indicated by FTIR analyses and solvent extraction. DMA demonstrated three glass transitions for the film from composite latex. Instron tests exhibited better film performance properties for the composite latex than for the corresponding blend latex. A possible particle growth mechanism for preparing urethane/acrylate composite latex was proposed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1620–1628, 2002; DOI 10.1002/app.10526
Ultrasonic improvement of rheological behavior of polystyrene
Authors: Chen Guangshun , Guo Shaoyun , Li Huilin 
Published: October 2004

AbstractThe effects of ultrasonic oscillation on die pressure, productivity of extrusion, melt viscosity, and melt oscillating flow of polystyrene (PS) as well as their mechanism were studied in a special ultrasonic oscillations extrusion system developed in our lab. The experimental results show that in the presence of ultrasonic oscillations, the PS melt oscillating flow or surface distortion of PS extrudate is inhibited or disappears. The surface appearance of PS extrudate gets greatly improved. The die pressure, melt viscosity, flow activation energy, and consistency efficiency of PS decreased and the productivity of PS extrudate increased in the presence of ultrasonic oscillation. The shear sensitivity of PS melt viscosity is decreased because of the increase of its power law index in the presence of ultrasonic oscillation. Introduction of ultrasonic oscillation into PS melt can greatly improve the processibility of PS. Their possible mechanism is also proposed in this article. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2451–2460, 2002
Synthesis of 5‐vinyl‐m‐ phenylene‐m′‐phenylene‐32‐ crown‐10 and its radical polymerization behavior
Authors: Jin Long Yi , Mah Soukil 
Published: October 2004

AbstractSynthesis of a vinyl monomer, containing a 32‐membered crown ether unit (VCE) as a pendant group, was achieved by using tetra(ethylene glycol) dichloride, resorcinol, and 3,5‐dihydroxyacetophenone as starting materials. The product was identified by means of FTIR and 1H‐NMR. It was found that this monomer readily polymerizes by the conventional radical initiator 2,2′‐ azobisisobutyronitrile (AIBN) to afford a polymer whose number‐average molecular weight is 36 kg/mol; however, the final conversion of the polymer was < 80%. The results of the copolymerization of VCE with styrene (ST) or acrylonitrile (AN) are also discussed. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2372–2379, 2002
Studies on graft copolymerization of 4‐vinylpyridine onto guar gum
Authors: Taunk Kavita , Behari Kunj 
Published: October 2004

AbstractGraft copolymerization of 4‐vinylpyridine (4‐VP) onto guar gum (GOH) using potassium monopersulfate (PMS)/thioacetamide (TAA) as a redox pair was studied in an aqueous medium under inert atmosphere. The concentration of potassium monopersulfate and thioacetamide should be 1.0 × 10−2 and 5.0 × 10−3 mol dm−3, respectively, for highest grafting ratio and efficiency. Efficient grafting was observed at 19.25 × 10−2 and 4.87 × 10−2 mol dm−3 concentration of 4‐vinylpyridine and sulfuric acid, respectively. The optimum temperature for grafting is 30°C. As the time period of reaction is increased, the grafting ratio increases, whereas efficiency decreases. The plausible mechanism of grafting has been suggested. A sample of guar gum and guar‐ g‐4‐vinylpyridine were subjected to thermogravimetric analysis with the objective of studying the effect of grafting 4‐vinylpyridine on the thermal stability of guar gum. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2380–2385, 2002
Viscosity of polydimethylsiloxane gum: Shear and temperature dependence from dynamic and capillary rheometry
Authors: Swallow Frank E. 
Published: October 2004

AbstractThe rheology of Dow Corning polydimethylsiloxane gum (PDMS/silicone gum) was studied over a time range of 10−2 to 105 s−1 and a temperature range of 23–150°C using both capillary and dynamic rheometry. A low shear Newtonian region is observed at room temperature below 0.01 rad/s (increasing to 0.1 rad/s at 150°C) for which an Arrhenius activation energy for a viscous flow of 13.3 kJ/mol was determined. The Cox–Merz rule for merging of shear and complex viscosities is found to be valid up to 10 s−1. Viscosity is found to be independent of temperature above 100 s−1, where terminal power‐law flow is encountered. This is exhibited in the dynamic data as equal plateau moduli for the various temperature curves. Gross wall slippage is seen in capillary flows above approximately 100 s−1, corresponding to a stress value of 70–100 kPa. Slip‐stick (spurt) flow is not observed. The viscosity data are best fitted by the Carreau–Yasuda model with a fitting parameter a of 0.7, a power‐law index n of 0.05 (low because of slip effect), and a zero shear viscosity of 32 kPa s at 23°C. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2533–2540, 2002
Novel biocompatible waterborne polyurethane using L‐lysine as an extender
Authors: Chen Hong , Jiang Xuwei , He Lin , Zhang Tao , Xu Min , Yu Xuehai 
Published: October 2004

AbstractPolyurethane (PU) prepolymers based on isophorone diisocyanates, dimethylolpropionic acid, and polycaprolactone were prepared and chain‐ extended in water using L‐lysine (PU–L), ethylenediamine (PU–E), and their mixture (PU– L–E) as extenders, respectively. The produced emulsion exhibited satisfactory freeze/thaw stability. Films cast from emulsions exhibited excellent mechanical properties and good antiblood coagulation character. Although the water‐swelling ratio for 24 h for PU–L was higher than those of PU–L–E and PU–E, it possessed the smallest hydrolysis rate among the three samples. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2474–2480, 2002