bluuebunny/crossref_metadata_2025_split huggingface dataset:
ACE inhibitors and diabetes: from HOPE to PROGRESS
Authors: Kennon Brian , Fisher Miles 
Published: September 2002

AbstractThe HOPE study was a large, multi‐centre study conducted in many countries, which recruited patients over the age of 55 who were at high cardiovascular risk, either because of the presence of existing vascular disease, or because of the presence of diabetes and at least one other cardiovascular risk factor. Ramipril reduced the end‐point of cardiovascular death, myocardial infarction and stroke, and these effects were greater than could be explained by blood pressure lowering alone. Recent criticism has focused on slight differences in baseline risk factors between placebo and intervention groups, but these may have been incorrectly interpreted and the influence on the results exaggerated. It is now up to the reader, armed with differing interpretations of the same data, to return to the primary publications, read these and draw their own conclusions. The recently published PROGRESS study examined the use of perindopril plus or minus a diuretic in reducing the risk of recurrence of stroke in patients with a previous stroke. The results indicate benefit from blood pressure reduction in these patients, but no added benefit was seen with the use of an ACE inhibitor. Two other large studies on the use of ACE inhibitors in patients who are at high cardiovascular risk are currently under way. Copyright © 2002 John Wiley & Sons, Ltd.
Flexibility improvement of epoxy resin by liquid rubber modification
Authors: Kaynak C , Ozturk A , Tincer T 
Published: September 2002

AbstractThe objective of this study was to improve the flexibility of diglycidyl ether of bisphenol‐A based epoxy resin by using a liquid rubber. For this purpose, hydroxyl terminated polybutadiene (HTPB) was used at two concentrations of 1 % and 1.5 % by weight. In order to improve compatibility between liquid rubber and epoxy, a silane coupling agent (SCA) was also used. Bending test specimens were moulded by using four different orders of mixing of HTPB with SCA and hardener to investigate the compatibility of HTPB and epoxy matrix. Three‐point bending tests indicated that the specimens containing HTPB rubber had higher flexibility than neat epoxy specimens. Moreover, liquid rubber modification resulted in increased plastic strain at failure due to the possible decrease in crosslinking density with the change in reactions path. Fractographic examinations under scanning electron microscope indicated the formation of rubber domains in the epoxy matrix. The deformed rubber domains and increased incidence of deformation lines, especially in the third and fourth group specimens, assessed the improvement in flexibility.© 2002 Society of Chemical Industry
Preparation and characterization of hyperbranched polyacrylate copolymers by self‐condensing vinyl copolymerization (SCVCP)
Authors: Hong Chun‐Yan , Pan Cai‐Yuan 
Published: September 2002

AbstractA series of hyperbranched polyacrylate copolymers have been synthesized by self‐condensing vinyl copolymerization (SCVCP) of 2‐(2‐bromopropionyloxy)‐ethyl acrylate (BPEA) and methyl acrylate (MA) in the presence of CuBr and bipyridine. The structures and properties of the polymers obtained are characterized by NMR and SEC/RALLS/DV/RI measurements. The effects of reaction conditions on molecular weight (MW), molecular weight distribution (MWD) and degree of branching (DB) are investigated.© 2002 Society of Chemical Industry
Synthesis of carboxy‐terminated telechelic oligostyrenes by Dead End Polymerization
Authors: David Ghislain , Boutevin Bernard , Robin Jean‐Jacques , Loubat Cedric , Zydowicz Nathalie 
Published: September 2002

AbstractStyrene was polymerized with 4,4′‐azobiscyanovaleric acid (ACVA) in order to obtain carboxy‐telechelic polystyrene (CTPS) using the Dead‐End Polymerization (DEP) conditions. First, we focused on experimental conditions leading to oligomers with molecular weights about 2000 g mol−1. Second, we demonstrated by‐products of ACVA radicals are also synthesized in the DEP conditions by combination or by disproportionation. The purification of CTPS was investigated in order to extract the by‐products of ACVA. An extraction of these by‐products in H2O pH 7 is suggested. Finally, the acid functionality of oligostyrene is evaluated by 1H NMR and conductimetric titrations. A functionality about 2 is obtained that confirmed the synthesis of CTPS.Copyright © 2002 Society of Chemical Industry
Dynamic mechanical and dielectric relaxation behaviour of poly(methacrylate)s containing saturated rings with seven and eight members in the side‐chains
Authors: Díaz‐Calleja Ricardo , García‐Bernabé Abel , Sánchez‐Martínez Enrique , Hormazábal Andrea , Gargallo Ligia , Radić Deodato 
Published: September 2002

AbstractDynamic mechanical and dielectric behaviour of poly(cycloheptyl methacrylate), poly(cycloheptylmethyl methacrylate) and poly(cyclooctyl methacrylate) have been investigated. The study was performed by determining the components of the complex relaxation modulus E* and the complex dielectric permittivity ϵ*. Results are discussed in terms of the effect of the size and structure of the side ring. The saturated ring group shows mechanical and dielectric activity at low temperature that is analyzed in terms of the Fuoss–Kirkwood equation. The free volume for the three polymers was determined. The conductive and interfacial phenomena were studied by MacDonald and Coelho models, where the dipolar contribution was introduced.© 2002 Society of Chemical Industry
Mission applicability assessment of integrated power components and systems
Authors: Raffaelle R. P. , Hepp A. F. , Landis G. A. , Hoffman D. J. 
Published: September 2002

AbstractThe need for smaller, lightweight, autonomous power systems has increased with the current focus on micro‐ and nanosatellites. Small‐area, high‐efficiency, thin‐film batteries and solar cells are an attractive choice for such applications. The NASA Glenn Research Center, Johns Hopkins Applied Physics Laboratory, Lithium Power Technologies, MicroSat Systems, and others, have been working on the development of autonomous monolithic packages combining these elements, or what are called integrated power supplies (IPS). These supplies can be combined with individual satellite components and are capable of providing continuous power, even under intermittent illumination associated with a spinning or earth‐orbiting satellite. This paper discusses the space mission applicability, benefits, and current development efforts associated with IPS components and systems. The characteristics and several mission concepts for an IPS that combines thin‐film photovoltaic power generation with thin‐film lithium ion energy storage are described. Based on this preliminary assessment, it is concluded that the most likely and beneficial application of an IPS will be for small ‘nanosatellites’ or in specialized applications serving as a decentralized or as a distributed power source or uninterruptible power supply. Copyright © 2002 John Wiley & Sons, Ltd.
CIGS2 thin‐film solar cells on flexible foils for space power
Authors: Dhere Neelkanth G. , Ghongadi Shantinath R. , Pandit Mandar B. , Jahagirdar Anant H. , Scheiman David 
Published: September 2002

AbstractCuIn1−xGaxS2(CIGS2) thin‐film solar cells on flexible stainless steel foil are of interest for space power because of the near optimum bandgap, potential for higher specific power, and superior radiation resistance. This paper describes development of CIGS2 solar cells on 127‐μm and 20‐μm‐thick, flexible SS foils for space power. A large‐area, dual‐chamber, deposition system has been fabricated. Cu‐rich Cu‐Ga/In layers were sputter‐deposited on unheated Mo‐coated foils.p‐type CIGS2 thin films were obtained by etching Cu‐rich surface layer from CIGS2 films prepared by sulfurization in Ar:H2S 1:0.04 mixture at 475°C for 60 min with an intermediate 30‐min annealing step at 135°C. Solar cells were completed by deposition of CdS/ZnO/ZnO:Al layers and Ni/Al contact fingers. AM0 PV parameters of a CIGS2 solar cell on 127‐μm‐thick SS foil measured at NASA‐GRC were:VOC = 802.9 mV,JSC = 25.07 mA/cm2, FF = 60.06%, and efficiency = 8.84%. For this cell, AM1.5 PV parameters measured at NREL wereVOC = 763 mV,JSC = 20.6 mA/cm2, FF = 67.4%, and efficiency = 10.4%. Copyright © 2002 John Wiley & Sons, Ltd.
Single‐junction InGaP/GaAs solar cells grown on Si substrates with SiGe buffer layers
Authors: Ringel S. A. , Carlin J. A. , Andre C. L. , Hudait M. K. , Gonzalez M. , Wilt D. M. , Clark E. B. , Jenkins P. , Scheiman D. , Allerman A. , Fitzgerald E. A. , Leitz C. W. 
Published: September 2002

AbstractSingle junction InGaP/GaAs solar cells displaying high efficiency and record high open‐circuit voltage values have been grown by metal–organic chemical vapor deposition on Ge/graded SiGe/Si substrates. Open‐circuit voltages of 980 mV under AM0 conditions have been verified to result from a single GaAs junction, with no evidence of Ge‐related sub‐cell photoresponse. AM0 efficiencies close to 16% have been measured for a large number of small‐area cells, the performance of which is limited by non‐fundamental current losses due to significant surface reflection resulting from> 10% front‐surface metal coverage and wafer handling during the growth sequence for these prototype cells. It is shown that at the material quality currently achieved for GaAs grown on Ge/SiGe/Si substrates, namely a 10 ns minority‐carrier lifetime that results from complete elimination of anti‐phase domains, and maintaining a threading dislocation density of ∼8 × 105 cm−2, 19–20% AM0 single‐junction GaAs cells are imminent. Experiments show that the high performance is not degraded for larger‐area cells, with identical open‐circuit voltages and higher short‐circuit current (due to reduced front metal coverage) values being demonstrated, indicating that large‐area scaling is possible in the near term. Comparison with a simple model indicates that the voltage output of these GaAs‐on‐Si cells follows the ideal behavior expected for lattice‐mismatched devices, demonstrating that unaccounted‐for defects and issues that have plagued other methods to epitaxially integrate III–V cells with Si are resolved by using SiGe buffers and proper GaAs nucleation methods. These early results already show the enormous and realistic potential of the virtual SiGe substrate approach for generating high‐efficiency, lightweight and strong III–V solar cells. Copyright © 2002 John Wiley & Sons, Ltd.
Progress in the development of metamorphic multi‐junction III–V space solar cells
Authors: Sinharoy Samar , Patton Martin O. , Valko Thomas M. , Weizer Victor G. 
Published: September 2002

AbstractTheoretical calculations have shown that highest‐efficiency III–V multi‐junction solar cells require alloy structures that cannot be grown on a lattice‐matched substrate. Ever since the first demonstration of high‐efficiency metamorphic single‐ junction 1.1 and 1.2 eV InGaAs solar cells, interest has grown in the development of multi‐junction cells of this type, using graded buffer layer technology. Essential Research Incorporated (ERI) is currently developing a dual‐junction 1.6 eV InGaP/1.1 eV InGaAs tandem cell (projected practical air‐mass zero (AM0), one‐sun efficiency of 27%, and 100‐sun efficiency of 31.1%) under a Ballistic Missile Defense Command (BMDO) SBIR Phase II program. A second ongoing research effort involves the development of a 2.1 eV AlGaInP/1.6 eV InGaAsP/1.2 eV InGaAs triple‐junction concentrator tandem cell (projected practical AM0 efficiency 36.5% under 100 suns) under a SBIR Phase II program funded by the Air Force. We are in the process of optimizing the dual‐junction cell performance. For the triple‐junction cell, we have developed the bottom and the middle cell, and are in the process of developing the layer structures needed for the top cell. A progress report is presented in this paper. Copyright © 2002 John Wiley & Sons, Ltd.
Quantum dot solar cells
Authors: Raffaelle Ryne P. , Castro Stephanie L. , Hepp Aloysius F. , Bailey Sheila G. 
Published: September 2002

AbstractWe have been investigating the synthesis of quantum dots of CdSe, CuInS2, and CuInSe2 for use in an intermediate bandgap solar cell. We have prepared a variety of quantum dots, using the typical organometallic synthesis routes pioneered by Bawendi et al. in the early 1990s. However, unlike previous work in this area, we have also utilized single‐source precursor molecules in the synthesis process. We present XRD, TEM, SEM and EDS characterization of our initial attempts at fabricating these quantum dots. Investigation of the size distributions of these nanoparticles via laser light scattering and scanning electron microscopy is also presented. Theoretical estimates on appropriate quantum dot composition, size, and inter‐dot spacing along with potential scenarios for solar cell fabrication is discussed. Copyright © 2002 John Wiley & Sons, Ltd.
Phase behaviors of partially ionized hydrogels in aqueous salt solutions: Applicability of the modified double‐lattice model
Authors: Hong Young Pyo , Bae Young Chan 
Published: September 2002

AbstractWe investigated the effect of charge densities of the gel network and ionic strength of solution on swelling behaviors of ionized gels. We used the modified double‐lattice model, Flory–Erman's elastic model, and the ideal Donnan theory to describe swelling behaviors of the electrolyte bounded hydrogels. Energy parameters (ϵ/k, δϵ/k) were obtained from fitting liquid–liquid equilibria data of the linear poly‐N‐isopropylacrylamide/water system and two adjustable model parameters obtained from a nonelectrolyte hydrogel system. Calculated values agreed with experimental data for the given systems. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2333–2338, 2002
Processing, mechanical properties, and fracture behavior of cereal protein/poly(hydroxyl ester ether) blends
Authors: Wang C. , Carriere C. J. , Willett J. L. 
Published: September 2002

AbstractBlends of poly(hydroxy ester ether) (PHEE), a recently developed bisphenol A ether‐based synthetic biodegradable thermoplastic polymer, with a soybean protein isolate and two hydrolyzed wheat glutens were studied. Blends of the proteins with PHEE were produced from 20 to 70% by weight of protein content. Young's moduli of the protein/PHEE blends fall in the range of 0.8–1.5 GPa with tensile strengths ranging from 10 to 30 MPa. Critical stress‐intensity factors of the blends ranged from 2 to 9 MPa‐m1/2 depending on the amount of protein added. Morphological analysis indicated a moderate degree of adhesion between the protein and PHEE phases in the blends. In general, as the protein content was increased the materials lost ductility and failed in a brittle manner; however, the mechanical properties of several compositions were comparable to commercial thermoplastics such as polystyrene. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2324–2332, 2002
Crystallization behavior of a propylene/ethylene copolymer: Nucleation and a clarifying additive
Authors: Martin C. P. , Vaughan A. S. , Sutton S. J. , Swingler S. G. 
Published: September 2002

AbstractThe isothermal crystallization behavior of a propylene/ethylene copolymer containing a clarifying additive has been studied in detail and compared with the equivalent unclarified grade. Differential scanning calorimetry was used to obtain crystallization exotherms for both the unclarified system and the clarified analogue. Avrami analysis of these data was then performed, using both linear and nonlinear data‐fitting techniques. Linear analysis revealed a change from a primary to a secondary crystallization process in the clarified system at about 50% relative crystallinity. Nonlinear techniques, however, led to more reliable estimates of the Avrami parameters and provided estimates of crystallization‐induction times. By combining the preceding with isothermal crystal‐growth‐rate data, the nucleation density in each material was obtained as a function of crystallization temperature. In the unclarified case, this fell exponentially with temperature. The nucleation density in the sorbitol‐clarified copolymer was 103–106 times greater than in the unclarified material, but decreased only slowly with increasing crystallization temperature throughout the temperature range investigated here. This final result appears entirely contradictory to previous morphological work in which a distinct morphological transition was observed at 128 °C and associated with a marked reduction in the nucleating efficiency of the sorbitol. Possible explanations for this apparent contradiction are considered. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2178–2189, 2002
Reversible melting of polyethylene extended‐chain crystals detected by temperature‐modulated calorimetry
Authors: Pak Jeongihm , Wunderlich Bernhard 
Published: September 2002

AbstractThe melting and crystallization of extended‐chain crystals of polyethylene are analyzed with standard differential scanning calorimetry and temperature‐modulated differential scanning calorimetry. For short‐chain, flexible paraffins and polyethylene fractions up to 10 nm length, fully reversible melting was possible for extended‐chain crystals, as is expected for small molecules in the presence of crystal nuclei. Up to 100 nm length, full eutectic separation occurs with decreasingly reversible melting. The higher‐molar‐mass polymers form solid solution crystals and retain a rapidly decreasing reversible component during their melting that decreases to zero about 1.5 K before the end of melting. An attempt is made to link this reversible melting to the known, detailed morphology and phase diagram of the analyzed sample that was pressure‐crystallized to reach chain extension and practically complete crystallization. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2219–2227, 2002
Relating fracture energy to entanglements at partially miscible polymer interfaces
Authors: Gorga Russell E. , Narasimhan Balaji 
Published: September 2002

AbstractA new model has been developed to calculate the areal chain density of entanglements (Σeff) at partially miscible polymer–polymer interfaces. The model for Σeff is based on a stochastic approach that considers the miscibility of the system. The values agree between Σeff calculated from the model and literature values for the reinforced interfaces. Using Σeff calculated from the model, the interfacial width, and the average distance between entanglements, an equation for the fracture energy of nonreinforced polymer interfaces is proposed. This equation is used to model the transition from chain pullout to crazing. As a function of system miscibility, the model for Σeff also accurately predicts a maximum in mode I fracture energy (Gc) as a result of the transition from gradient‐driven to miscibility‐limited interdiffusion, which is observed experimentally. As Σeff increases, the fracture energy increases accordingly. Compared with a recent model developed by Brown, the new model correctly predicts a reduced Gc (attributed to chain pullout) when the interfacial width is less than the average distance between entanglements. Theoretical predictions of the change in fracture energy with respect to interfacial width agree with the experimental measurements. Finally, it is postulated that the use of a miscibility criterion for Gc may reveal the universal nature of the pullout to crazing transition. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2292–2302, 2002
Molecular weight and aggregation of Aeromonas gum treated with dimethyl sulfoxide in aqueous solution
Authors: Xu Xiaojuan , Zhang Lina , Norisuye Takashi 
Published: September 2002

AbstractAeromonas (A) gum, an acidic hetero polysaccharide, in 0.2 M LiCl/dimethyl sulfoxide (DMSO) was fractionated satisfactorily according to the nonsolvent addition method. Eight fractions were chosen to examine their aggregation behavior in aqueous solution. The weight‐average molecular weight (Mw), radius of gyration 〈S2〉1/2, and intrinsic viscosities [η] of the fractions in 0.2 M LiCl/DMSO and 0.5 M NaCl aqueous solution at 25 °C were measured by static light scattering and viscometry. The results indicated that the A gum was aggregated in 0.5 M NaCl aqueous solution at 25 °C, and the aggregates were broken in 0.2 M LiCl/DMSO. The apparent weight‐average aggregation number (Nap) of the fractions increased with the process of fractionation, that is,Napincreased from 1.1 to 15 with decreasingMwof the single chain. The fractions obtained by treating with DMSO were more easily dissociated in the aqueous solution, and itsNapwas lower than that of the A gum fractions that were not treated with DMSO. Moreover, the A gum molecules with relatively lowMwaggregated easily to form a compact spherelike structure in the aqueous solution. Elemental analysis and13C NMR spectroscopy indicated that DMSO was adsorbed on the A gum molecules caused by the fractionation program; DMSO not only prevented the polysaccharide aggregation but also increased the solubility. A model has been proposed to describe the aggregation behavior of the A gum chains with DMSO overcoat in the aqueous solution. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2269–2276, 2002
Interfacial tension of poly(lactic acid)/polystyrene blends
Authors: Biresaw G. , Carriere C. J. 
Published: September 2002

AbstractPoly(lactic acid) (PLA) is a biodegradable synthetic polyester with unique properties that make it an excellent candidate for biomaterial blends. It provides improved moisture resistance to blends with biopolymers and biodegradability/biocompatibility to blends with synthetic polymers, without impairing the useful properties of blend components. The successful development of materials from blends of PLA requires an understanding of the factors affecting the interfacial properties of such blends. In this work, the effect of temperature on the interfacial tension of PLA/polystyrene (PS) blends was measured at 170–200 °C with the imbedded fiber retraction (IFR) method. IFR allows for the direct measurement of the interfacial tension of blends with high molecular weight/high viscosity components. In the temperature range studied, the interfacial tension of PLA/PS was independent of temperature and had a value of 5.4 ± 1.3 dyn/cm. The interfacial tension was also calculated from the surface energies of PLA and PS with geometric mean (GM), harmonic mean (HM), and Antonoff's equations and from solubility parameters with the procedure of Luciani et al. IFR measured values were similar to those predicted by the procedure of Luciani et al. and Antonoff's equations, which gave 4.4 and 3.0 ± 1.4 dyn/cm, respectively. The GM and HM methods predicted much lower values of 1.1 ± 0.5 and 1.7 ± 1.1 dyn/cm, respectively. Published 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2248–2258, 2002