bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemoenzymatic Synthesis of Enantiomerically Pure (2S,3R,4S)‐4‐Hydroxyisoleucine, an Insulinotropic Amino Acid Isolated from Fenugreek Seeds
Authors: Rolland‐Fulcrand Valérie , Rolland Marc , Roumestant Marie‐Louise , Martinez Jean 
Published: February 2004

AbstractA short six‐step synthesis of (2S,3R,4S)‐4‐hydroxyisoleucine (1a) with total control of stereochemistry is reported, the last step being the enzymatic resolution by hydrolysis of a N‐phenylacetyl lactone derivative using the commercially available penicillin acylase G immobilized on Eupergit C (E‐PAC). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
From α,β‐Unsaturated Fischer Carbene Complexes to Highly Substituted 3‐Ethoxycyclopentadienes, Masked Cyclopentenones
Authors: Wu Yao‐Ting , Flynn Bernard , Schirmer Heiko , Funke Frank , Müller Stefan , Labahn Thomas , Nötzel Markus , de Meijere Armin 
Published: February 2004

AbstractThe β‐amino‐substituted α,β‐unsaturated Fischer carbene complexes 3 are readily available by a four step one‐pot procedure from terminal alkynes, chromium hexacarbonyl and secondary amines (24 examples with yields of 68−99% and 7 examples with yields of 26−63%). The formal [3+2] cycloadditions of complexes 3 with different alkynes including diynes and enynes performed in donor solvents such as pyridine or acetonitrile afforded highly substituted 5‐(dialkylamino)‐3‐ethoxycyclopentadienes 7, generally in medium to excellent yields (25 examples with yields of 60−95% and 7 examples with yields of 18−53%). The steric and electronic effects of the substituents on the carbene complexes and the incorporated alkynes on the regio‐ and stereoselectivity of the ring‐forming reaction have been elaborated. An interesting 1,5‐ or, more likely, 1,2‐migration of the dimethylamino group was observed for 5‐(dimethylamino)‐3‐ethoxycyclopentadienes with trimethylsilyl and iPr substituents at C‐5. Attempted asymmetric syntheses of cyclopentadienes 7 from complexes 3 with chiral amino groups or substituents were only moderately successful. At a center of chirality in the secondary amino group, complexes of type 3 gave compounds 7 with diastereomeric excesses of, at best, 59% in yields of 54%, and with a stereogenic center in the substituent R1 attached to the vinyl group of 3, diastereomeric excesses as high as 94% could be achieved, but with poor chemical yields (21%). In general, cyclopentenones 21 could be easily obtained from the cyclopentadienes 7 under acidic conditions in very good yields (4 examples with yields of 81−98%, 1 example with an overall yield of 50% from complex 3). Intramolecular aldol reactions of dicarbonyl compounds generated by hydrolysis of cyclopentadienes 7 with acetal‐protected aldehyde or ketone carbonyl groups in either the 5‐substituent R1 or the N‐substituent R2 led to the bicyclic compounds 22 and 23. The dimethylamino group in cyclopentenones 21 could be either eliminated or transformed into other functional groups via the quaternary ammonium salts 24. The elimination product, cyclopentadienone 27 can undergo dimerization either by a formal [4+2] or [2+2] cycloaddition. Cyclopentenone 21naaa with a bromovinyl‐terminated side chain undergoes an intramolecular Heck reaction to form 5‐methyl‐4,6‐dimethylenebicyclo[3.3.0]oct‐1‐en‐3‐one (32) (37% yield). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Overcrowded 5,10,15‐Trisubstituted Derivatives: Synthesis of 5,10,15‐Tri(fluorenylidene)truxene
Authors: Ruiz Marta , Gómez‐Lor Berta , Santos Amelia , Echavarren Antonio M. 
Published: February 2004

AbstractSterically crowded 5,10,15‐triarylated truxenes are obtained by reaction of truxenetrione with aryllithium compounds (aryl = 1‐naphthyl, 2‐naphthyl, 9‐phenanthryl, 9‐anthracenyl), followed by reduction of the tertiary alcohols with Et3SiH and BF3. Base‐catalyzed isomerization of the anti derivatives provides syn‐5,10,15‐triarylated derivatives, with the exception of the 9‐anthracenyl that could not be isomerized. Overcrowded 5,10,15‐tri(fluorenylidene)truxene was also synthesized starting form the addition of fluorenyllithium to truxenetrione. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
A multiple family group intervention for first‐time juvenile offenders: Comparisons with probation and dropouts on recidivism
Authors: Quinn William H. , Van Dyke David J. 
Published: February 2004

AbstractThis study evaluated a multiple‐family group‐intervention program (MFGI) for first‐time juvenile offenders. The recidivism rate for subjects who completed the MFGI (the Family Solutions Program) was compared to recidivism rates of two other groups of first‐time juvenile offenders. Using logistic regression analysis predicting who will recidivate, juvenile first offenders who were placed on probation (N = 95) were 9.3 times more likely to re‐offend compared to the Family Solutions Program (FSP) graduates (N = 267). Families referred to FSP but who dropped out (most never attended the 10 session program) (N = 93) also were 4.4 times more likely to re‐offend compared to FSP graduates. An intent‐to‐treat model comparing the combined group of FSP graduates and dropouts with the probation group indicated that a youth in the probation group was 8.1 times more likely to re‐offend than a youth referred to the FSP. Results indicating better outcomes on recidivism for FSP graduates were significant for both male and female youths. Implications for policy and practitioners are discussed. © 2004 Wiley Periodicals, Inc. J Comm Psychol 32: 177–200, 2004.
Mediating effects of social support on firefighters' sense of community and perceptions of care
Authors: Cowman Shaun E. , Ferrari Joseph R. , Liao‐Troth Matthew 
Published: February 2004

AbstractThis study examined the relationship between psychological sense of community, social‐support networks, and care‐giver stress and satisfaction among firefighters. No significant gender differences were obtained, but zero‐order correlates demonstrated significant relationships among all four variables. In examining the mediating effects of social‐support satisfaction, partial mediation for psychological sense of community on care‐giver satisfaction was determined, as well as full mediation for psychological sense of community on care‐giver stress. Therefore, firefighters who are satisfied with the support they receive may experience less stress with their care giving than those who experience low levels of support satisfaction. Future studies should assess these relationships more extensively in other areas of civic responsibility among public‐service employees to delineate effective support avenues. © 2004 Wiley Periodicals, Inc. J Comm Psychol 32: 121–126, 2004.
Determination of the weaker phase in the pitting corrosion of non‐standard low‐Ni high‐Mn‐N duplex stainless steels
Authors: Merello R. , Botana F. J. , Botella J. , Marcos M. 
Published: February 2004

AbstractIn this paper, the use of Energy Dispersive Spectrometry (EDS) is proposed to determine the partition coefficients of the elements of a new family of duplex stainless steels that are characterized by having low contents of nickel, together with high levels of manganese and nitrogen.From the values of the partition coefficients, the chemical compositions of the constituting phases have been determined, in order subsequently to calculate the value of the Pitting Resistance Equivalent Number (PREN) of each phase. The proposition put forward in this study is that the phase having the lower PREN determines the pitting corrosion behaviour of these types of steels.Results obtained by means of optical and scanning electron microscopy have provided confirmation that the pitting corrosion behaviour of these new materials gets determined by the resistance of the weaker phase and consequently by the phase having the lower PREN value.Lastly it has been proved possible to determine the existence of an exponential relationship between the alloys pitting potential (Ep) and the weaker phase PREN; this can be utilized for the low‐nickel duplex stainless steels design in which the pitting corrosion resistance is controlled.
Atmospheric corrosion of carbon steels pre‐corroded by different pollutants
Authors: Wan Y. , Yan C. , Cao C. , Tan J. 
Published: February 2004

AbstractCarbon steels were pre‐corroded in atmospheres containing certain pollutants such as sulfur dioxide or hydrogen sulfide or nitrogen dioxide for certain period of time. Then the pre‐corroded samples were further exposed at two central test stations in the country to evaluate the influence of pre‐corrosion on the behavior of long‐term atmospheric corrosion of carbon steel by gravimetric measurement and rust examinations with FT‐IR and XRD. The results showed that the corrosion rates of every kind of carbon steel at Jiangjin station were two times higher than that at Beijing station. The influence of different pre‐corrosion conditions on the long‐term atmospheric corrosion of carbon steel was analyzed. It followed that the pre‐corrosion conditions made the long‐term atmospheric corrosion performance of three kinds of carbon steels different, but the differences were small. Among the three pollutants, NO2 showed the strongest influence to the process. As the exposure time was going on, all the samples corroded slowly at Beijing and Jiangjin stations.
An Ehrenfeucht‐Fraïssé class game
Authors: Boulos Lotfallah Wafik 
Published: February 2004

AbstractThis paper introduces a new Ehrenfeucht‐Fraïssé type game that is played on two classes of models rather than just two models. This game extends and generalizes the known Ajtai‐Fagin game to the case when there are several alternating (coloring) moves played in different models. The game allows Duplicator to delay her choices of the models till (practically) the very end of the game, making it easier for her to win. This adds on the toolkit of winning strategies for Duplicator in Ehrenfeucht‐Fraïssé type games and opens up new methods for tackling some open problems in descriptive complexity theory. As an application of the class game, it is shown that, if m is a power of a prime, then first order logic augmented with function quantifiers F1n of arity 1 and height n < m can not express that the size of the model is divisible by m. This, together with some new expressibility results for Henkin quantifiers H1n gives some new separation results on the class of finite models among various F1n on one hand and between F1n and H1n on the other. Since function quantifiers involve a bounded type of second order existential quantifiers, the class game (in a sense) solves an open problem raised by Fagin, which asks for some inexpressibility result using a winning strategy by Duplicator in a game that involves more than one coloring round. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A finite element model for thermomechanical analysis of sheet metal forming
Authors: Bergman G. , Oldenburg M. 
Published: February 2004

AbstractA thermal model based on explicit time integration is developed and implemented into the explicit finite element code DYNA3D to model simultaneous forming and quenching of thin‐walled structures. A staggered approach is used for coupling the thermal and mechanical analysis, wherein each analysis is performed with different time step sizes. The implementation includes a thermal shell element with linear temperature approximation in the plane and quadratic in the thickness direction, and contact heat transfer. The material behaviour is described by a temperature‐dependent elastic–plastic model with a non‐linear isotropic hardening law. Transformation plasticity is included in the model. Examples are presented to validate and evaluate the proposed model. The model is evaluated by comparison with a one‐sided forming and quenching experiment. Copyright © 2004 John Wiley & Sons, Ltd.
Radical copolymerization of 2‐trifluoromethylacrylic monomers. III. Kinetics and monomer reactivities in the copolymerization of t‐butyl 2‐trifluoromethylacrylate and methacrylate with styrene bearing hexafluoroisopropanol
Authors: Ito Hiroshi , Okazaki Masaki , Miller Dolores C. 
Published: February 2004

AbstractRadical copolymerizations of t‐butyl 2‐trifluoromethylacrylate (TBTFMA) and styrene‐bearing hexafluoroisopropanol [4‐(1,1,1,3,3,3‐hexafluoro‐2‐hydroxypropyl)styrene (STHFA)] with 2,2′‐azobisisobutyronitrile were investigated in detail through the analysis of the kinetics in situ with 1H NMR and through the determination of the monomer reactivity ratios. TBTFMA incorporation was less than 50 mol % unless its concentration in the feed was greater than 90 mol %. Furthermore, the penultimate model provided a better description of the TBTFMA–STHFA copolymerization. In contrast, t‐butyl methacrylate copolymerized with STHFA according to the terminal model. The copolymerizations were simulated on the basis of the monomer reactivity ratios to calculate the feed and copolymer composition changes, sequence distributions, and so forth as a function of the initial feed ratio and conversion. The simulation results showed excellent agreement with the kinetic data. The copolymers described in this article were evaluated as chemical amplification resist polymers for the emerging field of 157‐nm lithography. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1506–1527, 2004
Synthesis and cationic photopolymerization of new silicon‐containing oxetane monomers
Authors: Sangermano M. , Bongiovanni R. , Malucelli G. , Priola A. , Olbrych J , Harden A. , Rehnberg N. 
Published: February 2004

AbstractThe cationic photopolymerization of oxetane‐based systems containing silicon monomers was investigated. For this purpose, three new silicon‐containing oxetane monomers were synthesized through a simple and straightforward synthetic method. The silicon‐containing monomers were added to a typical oxetane resin, 3,3′‐[oxydi(methylene)]bis(3‐ethyloxetane), in concentrations of 1–5 wt %. They exploited a certain surface tension effect without affecting the rate of polymerization. Enrichment only on the air side was achieved, which induced hydrophobicity in the photocured films, depending on the monomer structure and concentration. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1415–1420, 2004
Transport properties of uniaxially oriented aliphatic polyketone
Authors: Backman A. , Lange J. , Hedenqvist M. S. 
Published: February 2004

AbstractThe oxygen, carbon dioxide, and water‐transport properties of a uniaxially oriented aliphatic polyketone were determined. The polyketone was drawn to 5–10 times its original length. The transport properties were related to changes in crystallinity estimated by differential scanning calorimetry and density measurements and by changes in the molecular and crystal orientation assessed by, respectively, infrared and X‐ray spectroscopy. The film structures were characterized by confocal scanning laser microscopy and scanning electron microscopy. Stress‐strain tests on the drawn specimens enabled the impacts of orientation on the transport and mechanical properties to be compared. A draw‐induced increase in crystallinity and molecular orientation yielded permeabilities at a draw ratio of 10 that were 30–40% of the original value, and the percentage decrease was basically independent of the type of gas/vapor molecule. Also, the diffusivities of oxygen and carbon dioxide decreased by an order of magnitude. The fact that the amorphous permeability was peaking at a draw ratio of about 5 was a consequence of a peak in amorphous solubility, which was very high for oxygen and absent for water. It was suggested that the peak in solubility was mainly caused by the destruction of the polymer hydrogen‐bond network during drawing and crystal reorientation. The impact of structural reorganization within the polymer and presence of surface valleys seemed to have less impact on the mechanical properties than on the transport properties. This suggested that transport data are more sensitive than mechanical data in probing material defects and changes in molecular packing and morphology. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 947–955, 2004
Unusual relaxation process in polybutadiene: Resolving the controversy
Authors: Ding Y. , Novikov V. N. , Sokolov A. P. 
Published: February 2004

AbstractWe report the observation of an unusual relaxation process in depolarized light scattering spectra of polybutadiene (PBD) with two different vinyl contents. The process showed up in the gigahertz frequency range with relatively mild temperature dependence and was similar to a secondary relaxation process. The most surprising observation was that the process exists even at high temperatures and does not merge with the segmental relaxation up to a temperature of 400 K (T > 2Tg). Possible mechanisms of this particular relaxation in PBD are discussed. The process is compared to the so‐called E process, double‐bond hopping process, and dielectric β process. We emphasize that this process differs from the dielectric β process, is unique for 1,4‐PBD, and has not been observed in other polymers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 994–999, 2004
Polypropylene modified with elastomeric metallocene‐catalyzed polyolefin blends: Fracture behavior and development of damage mechanisms
Authors: Fasce Laura A. , Frontini Patricia M. , Wong Shing‐Chung , Mai Yiu‐Wing 
Published: February 2004

AbstractThe fracture behavior and deformation mechanisms of polypropylene modified by elastomeric metallocene‐catalyzed polyolefin blends were investigated under both static and dynamic loading conditions. The fracture toughness was evaluated with the J integral approach. The development of damage mechanisms was studied by the examination of fracture surfaces with scanning electron microscopy and by the examination of single‐edge, double‐notch, four‐point‐bending or low‐impact‐energy fractured samples with optical microscopy. In addition, tensile dilatometry measurements were carried out to determine the nature of the deformation micromechanisms. The fracture behavior and the size and shape of the damage zones were drastically influenced by the elastomeric particles and the imposed constraint. The role of the elastomeric particles was different, depending on the strain rate. Under impact loading, particle pullout and crazing were responsible for the increased fracture toughness of polypropylene. Under quasistatic loading, stable fracture growth was caused by particle cavitation, which promoted ductile tearing of polypropylene before failure continued in an unstable fashion via crazing. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1075–1089, 2004
Complex formation and degradation in poly(acrylonitrile‐co‐vinyl acetate) containing copper nitrate
Authors: Silverstein Michael S. , Najary Youval , Grader Gideon S. , Shter Gennady E. 
Published: February 2004

AbstractThe pyrolysis of polymers containing metal nitrates may provide a relatively simple, rapid, and advantageous method of producing high‐temperature superconductors (HTSCs). The advantage lies in the ability to use conventional polymer processing or microlithographic patterning before pyrolysis. A copolymer of acrylonitrile and vinyl acetate [P(AN‐VA)], a well‐known fiber‐forming polymer, was investigated as a potential HTSC precursor. Complex formation with the highly polar acrylonitrile groups was expected to enhance atomic‐level mixing and hinder nitrate recrystallization. The metal nitrates were found to have a profound effect on P(AN‐VA) pyrolysis. P(AN‐VA) containing copper nitrate (CuN) exhibited complex formation and an exothermic decomposition that began at about 170 °C (reaction 1‐CuN). Reaction 1‐CuN had a heat of about 3.5 kJ/gNO3 and a mass loss of about 0.99 g/gNO3. As reaction 1‐CuN also involved the nitrile groups, it disrupted the nitrile cyclization reaction at about 290 °C. For a P(AN‐VA)/CuN ratio of 2/1, there was no nitrile cyclization, and the thermooxidative degradation temperature was reduced by approximately 200 °C. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1023–1032, 2004
Chondrocyte viability in press‐fit cryopreserved osteochondral allografts
Authors: Gole Madhura D. , Poulsen Dan , Marzo John M. , Ko Seung‐Hee , Ziv Israel 
Published: February 2004

AbstractThe viability of chondrocytes in press‐fit glycerol‐preserved osteochondral allografts was compared to that in fresh autografts, after transplantation into load‐bearing and non‐load‐bearing sites in mature sheep stifle joints. We used macroscopic grading, tonometer pen indentation testing, histology, sulfate uptake and viability as determined by confocal‐microscopy to assess cartilage condition. Despite there being no statistical differences between macroscopic appearance and tonometer testing of all grafts, confocal microscopy and histology demonstrated a positive effect of load‐bearing placement on cryopreserved osteochondral allografts. Allografts transplanted into load‐bearing sites demonstrated superior confocal microscopy‐measured chondrocyte viability (77% ± 17%SD) than those transplanted into non‐load‐bearing sites (25%±2%). Load‐bearing effect was not seen in autografts (78%±15%), and was comparable in adjacent cartilage (83%±9%). Similarly, load‐bearing allografts demonstrated histological scoring closer to that of autografts and adjacent cartilage, all of which fared significantly better than non‐load‐bearing allografts. Load‐bearing allografts had a greater amount of fibrocartilage than autografts or adjacent cartilage but less fibrocartilage than non‐load‐bearing allografts. Both autografts and allografts had non‐significant increases in metabolism compared to adjacent cartilage as measured by sulfate‐uptake. Load‐bearing placement improved chondrocyte viability of glycerol cryopreserved osteochondral allograft following a press‐fit implantation. Published by Elsevier Ltd. All on behalf of orthopaedic Research Society.
Chasing Rainbow Notions: Enacting Community Psychology in the Classroom and Beyond in Post‐1994 South Africa
Authors: Sigogo Thabani Ngonyama ka , Hooper Megan , Long Carol , Lykes M. Brinton , Wilson Kenneth , Zietkiewicz Estelle 
Published: February 2004

AbstractThis paper discusses tensions and contradictions experienced by a group of psychologists in post‐1994 South Africa as we struggled to develop an MA program in community psychology. Situating our work within the history of the subdiscipline and the historical context confronting South Africans in the “wake of apartheid,” we explore models of community psychology that informed praxis under apartheid and contemporary challenges confronting a country in transition. We discuss three tensions that inform the ongoing program development. These include (1) the construction and deconstruction of Western and indigenous knowledge systems; (2) assessment and intervention at multiple levels and from differing value perspectives; and (3) paradoxes experienced by a team of university‐educated, primarily White academic staff committed to challenging oppression. We conclude our discussion by suggesting that, within these shifting sands of economic, political, cultural, and institutional change community psychology must, of necessity, resist rigid self‐definition and seek to position itself as a “work‐in‐progress.” We suggest that this seemingly anomalous self‐description may be suggestive for other community psychologists‐in‐the‐making facing similar challenges within the majority world.