bluuebunny/crossref_metadata_2025_split huggingface dataset:
Block copolymers of unsaturated polyesters and functional elastomers
Authors: Cherian A. Benny , Thachil Eby Thomas 
Published: September 2004

AbstractBlock copolymers of unsaturated polyester were prepared by condensation polymerization of hydroxyl or carboxyl terminated liquid rubbers with maleic anhydride, phthalic anhydride, and propylene glycol. The condensate obtained was mixed with styrene monomer to get an unsaturated polyester resin formulation. In this study, copolymers of unsaturated polyesters with hydroxy terminated polybutadiene, carboxy terminated nitrile rubber, and hydroxy terminated natural rubber were prepared. Mechanical properties such as tensile strength, tensile modulus, elongation at break, toughness, impact strength, surface hardness, abrasion resistance, and water absorption were evaluated after the resin was cured in appropriate molds for comparison with the control resin. The fracture toughness and impact resistance of CTBN‐modified unsaturated polyester show substantial improvement by this copolymerization without seriously affecting any other property. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1956–1964, 2004
Softening of wood polymers induced by moisture studied by dynamic FTIR spectroscopy
Authors: Åkerholm Margaretha , Salmén Lennart 
Published: September 2004

AbstractThe softening of the wood polymers is very important in the utilization of wood fiber products. To better to understand how the hemicelluloses interact with the other wood polymers in the fiber ultrastructure and contribute to the mechanical properties of the wood, their softening inside the cell wall of pulp fibers was studied by dynamic FTIR spectroscopy under humid conditions. The two hemicelluloses of spruce, glucomannan and xylan, exhibited different softening behaviors indicating a different organization of the two hemicelluloses inside the cell wall. Lignin in mechanical pulp showed a more viscoelastic behavior already under dry conditions than the polysaccharides of the cell wall. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2032–2040, 2004
Water‐swellable hydrophobic porous copolymer resins based on divinylbenzene and acrylonitrile. II. Pore structure and adsorption behavior
Authors: Tang Xiaoshan , Wang Xunhua , Yan Jun 
Published: September 2004

AbstractBy using purified divinylbenzene (DVB, 98.8%) or technical DVB (79.3%), the hydrophobic, but water‐wettable or swellable porous copolymer resins based on DVB and acrylonitrile (AN) could be prepared with a wide range of pore structures under certain conditions. The specific surface area for the resulting AN/DVB resin, with an AN/DVB ratio of 40/60 (by mole), could reach a value of 704 m2/g, while such a resin is still water wettable or swellable by direct contact with water. The adsorption behavior of the AN/DVB resins was investigated by focusing on the comparison between the resins with and without prewetting, using caffeine and phenol as model adsorbates. Adsorption behavior of the AN/DVB resins, without prewetting, correlates well with the wetting ability of the resins in water, suggesting that a well water‐wettable hydrophobic porous AN/DVB resin could be directly applied, in a dry state, to the adsorption in an aqueous medium, almost without diminishing the ability of the resin to adsorb the solutes. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2050–2056, 2004
The affective costs of overconfidence
Authors: McGraw A. Peter , Mellers Barbara A. , Ritov Ilana 
Published: September 2004

AbstractPositive illusions, though often beneficial (Taylor & Brown, 1988), can diminish the pleasure of outcomes. This prediction follows from decision affect theory. We investigated this prediction by measuring the confidence that recreational basketball players felt while making shots and the pleasure they felt with subsequent outcomes. Results showed that most players were overconfident. Those who were more overconfident tended to experience less enjoyment with their outcomes. Using individual parameter estimates from decision affect theory, we estimated how each player would have felt if their self assessments had been accurate. For the vast majority, better calibration would have led to greater pleasure. In a second study, we randomly assigned players to a debiasing treatment condition or a control condition. Relative to the control players, debiased players were better calibrated and derived greater average pleasure from the task. Copyright © 2004 John Wiley & Sons, Ltd.
The role of urban community colleges in educating diverse populations
Authors: Hagedorn Linda Serra 
Published: September 2004

AbstractThis chapter uses data from the Transfer and Retention of Urban Community College Students project to provide evidence of success among racially diverse students in the Los Angeles Community College District. Through interviews with student services personnel, it also describes the specific efforts that may be responsible for this success. In addition, it provides insight into the current and anticipated effects of severe budget cuts on minority student success initiatives.
Diversity in the two‐year college academic workforce
Authors: Jackson Jerlando F. L. , Phelps L. Allen 
Published: September 2004

AbstractThis chapter compares the racial and ethnic diversity among faculty and academic leaders with that of the student population in two‐year colleges. Using two national data sets, this study reveals that African American and Hispanic faculty and academic leaders remain underrepresented compared to the number of students of color attending the nation's two‐year colleges.
Thermal Effects and Vibrational Corrections to Transition Metal NMR Chemical Shifts
Authors: Grigoleit Sonja , Bühl Michael 
Published: September 2004

AbstractBoth zero‐point and classical thermal effects on the chemical shift of transition metals have been calculated at appropriate levels of density functional theory for a number of complexes of titanium, vanadium, manganese and iron. The zero‐point effects were computed by applying a perturbational approach, whereas classical thermal effects were probed by Car–Parrinello molecular dynamics simulations. The systematic investigation shows that both procedures lead to a deshielding of the magnetic shielding constants evaluated at the GIAO‐B3 LYP level, which in general also leads to a downfield shift in the relative chemical shifts, δ. The effect is small for the titanium and vanadium complexes, where it is typically on the order of a few dozen ppm, and is larger for the manganese and iron complexes, where it can amount to several hundred ppm. Zero‐point corrections are usually smaller than the classical thermal effect. The pronounced downfield shift is due to the sensitivity of the shielding of the metal centre with regard to the metal–ligand bond length, which increase upon vibrational averaging. Both applied methods improve the accuracy of the chemical shifts in some cases, but not in general.
EPR Studies of Amine Radical Cations, Part 1: Thermal and Photoinduced Rearrangements of n‐Alkylamine Radical Cations to their Distonic Forms in Low‐Temperature Freon Matrices
Authors: Janovský I. , Knolle W. , Naumov S. , Williams F. 
Published: September 2004

AbstractThe thermal and photochemical transformations of primary amine radical cations (n‐propyl 1.+, n‐butyl 5.+) generated radiolytically in freon matrices have been investigated by using low‐temperature EPR spectroscopy. Assignment of the spectra was facilitated by parallel studies on the corresponding N,N‐dideuterioamines. The identifications were supported by quantum chemical calculations on the geometry, electronic structure, hyperfine splitting constants and energy levels of the observed transient radical species. The rapid generation of the primary species by a short exposure (1–2 min) to electron‐beam irradiation at 77 K allowed the thermal rearrangement of 1.+ to be monitored kinetically as a first‐order reaction at 125–140 K by the growth in the well‐resolved EPR signal of the distonic radical cation .CH2CH2CH2NH3+. By comparison, the formation of the corresponding .CH2CH2CH2CH2NH3+ species from 5.+ is considerably more facile and already occurs within the short irradiation time. These results directly verify the intramolecular hydrogen‐atom migration from carbon to nitrogen in these ionised amines, a reaction previously proposed to account for the fragmentation patterns observed in the mass spectrometry of these amines. The greater ease of the thermal rearrangement of 5.+ is in accordance with calculations on the barrier heights for these intramolecular 1,5‐ and 1,4‐hydrogen shifts, the lower barrier for the former being associated with minimisation of the ring strain in a six‐membered transition state. For 1.+, the 1,4‐hydrogen shift is also brought about directly at 77 K by exposure to ∼350 nm light, although there is also evidence for the 1,3‐hydrogen shift requiring a higher energy. A more surprising result is the photochemical formation of the H2CN. radical as a minor product under hard‐matrix conditions in which diffusion is minimal. It is suggested that this occurs as a consequence of the β‐fragmentation of 1.+ to the ethyl radical and the CH2NH2+ ion, followed by consecutive cage reactions of deprotonation and hydrogen transfer from the iminonium group. Additionally, secondary ion–molecule reactions were studied in CFCl2CF2Cl under matrix conditions that allow diffusion. The propane‐1‐iminyl radical CH3CH2CHN. was detected at high concentrations of the n‐propylamine substrate. Its formation is attributed to a modified reaction sequence in which 1.+ first undergoes a proton transfer within a cluster of amine molecules to yield the aminyl radical CH3CH2CH2N.H. A subsequent disproportionation of these radicals can then yield the propane‐1‐imine precursor CH3CH2CHNH, which is known to easily undergo hydrogen abstraction from the nitrogen atom. The corresponding butane‐1‐iminyl radical was also observed.
Total Synthesis of Salicylihalamides A and B
Authors: Herb Christian , Bayer Alexander , Maier Martin E. 
Published: September 2004

AbstractThe paper illustrates two efficient routes to macrolactone 19 containing a 3‐(para‐methoxybenzyloxy)propyl side chain at C‐15. The chiral center at C‐15 was introduced by a Noyori reduction of keto ester 5. The intermediate common to both routes, aldehyde 8, was prepared from keto ester 5. The subsequent chain extension utilized Evans aldol reactions. The first route leads to the alkene 14, which was used, after hydroboration, for a Suzuki cross‐coupling reaction with vinyl iodide 15. The derived seco acid 18 was converted into the macrolactone 19 by a Mitsunobu lactonization by using immobilized triphenylphosphine. Alternatively, an aldol reaction of 8 with the 4‐pentenoyl derivative 20 was used to prepare alkene 26. This building block led to ester 28, which could also be converted into macrolactone 19 by the classical ring‐closing metathesis. After conversion of the C‐15 side chain to the corresponding aldehyde, the enamide was introduced through hemiaminal formation and formal elimination of water. Separation of the double‐bond isomers and removal of the silyl protecting groups provided salicylihalamides A (E)‐1 and B (Z)‐1.
Emission trading regimes and incentives to participate in international climate agreements
Authors: Buchner Barbara , Carraro Carlo 
Published: September 2004

AbstractThis paper analyses whether different emission trading regimes provide different incentives to participate in a cooperative climate agreement. Different incentive structures are discussed for those countries, namely the US, Russia and China, that are most important in the climate negotiation process. Our analysis confirms the conjecture that, by appropriately designing the emission trading regime, it is possible to enhance the incentives to participate in a climate agreement. Therefore, participation and optimal policy should be jointly analysed. Moreover, our results show that the US, Russia and China have different most preferred climate coalitions and therefore adopt conflicting negotiation strategies. Copyright © 2004 John Wiley & Sons, Ltd and ERP Environment.
Usefulness of fluorine‐18 fluorodeoxyglucose positron emission tomography in patients with a residual structural abnormality after definitive treatment for squamous cell carcinoma of the head and neck
Authors: Ware Robert E. , Matthews Jane P. , Hicks Rodney J. , Porceddu Sandro , Hogg Annette , Rischin Danny , Corry June , Peters Lester J. 
Published: September 2004

AbstractBackground.Residual structural abnormalities after definitive treatment of head and neck squamous cell carcinoma (HNSCC) are common and pose difficult management problems. The usefulness of fluorine‐18 fluorodeoxyglucose positron emission tomography (FDG PET) to supplement conventional evaluation with clinical and standard radiologic examination (CE) in such patients was assessed.Methods.Fifty‐three eligible patients were identified with residual structural abnormalities on CE. True disease extent could be validated in 46 patients. Patients had a median potential follow‐up of 55 months (range, 41–75 months) from the date of PET scan to the analysis closeout date.Results.PET had better diagnostic accuracy than CE (p = .0002) and induced management change in 21 patients (40%; 95% confidence interval [CI], 26%–54%), including avoidance of unnecessary planned surgery in 14 patients with negative PET. Appropriate management change was confirmed in 19 (95%) of 20 evaluable cases. Disease presence and extent assessment by PET were significant predictors of survival (p < .0001), whereas the extent of disease determined by CE was not.Conclusion.PET added significantly to the value of CE in restaging disease in patients with structural abnormalities after definitive treatment of HNSCC. Management decisions based on PET were appropriate in most patients. © 2004 Wiley Periodicals, Inc. Head Neck 26: 1008–1017, 2004
Dynamic mechanical analysis of viscoelastic functions in packable composite resins measured by torsional resonance
Authors: Papadogiannis Y. , Helvatjoglu‐Antoniades M. , Lakes R. S. 
Published: September 2004

AbstractThe objective of this study was to evaluate the viscoelastic functions of packable composite resins with the use of a resonant dynamic mechanical analysis technique in torsion. The materials tested were: Alert (Jeneric Pentron), Prodigy Condensable (Kerr Corporation), Surefil (Dentsply DeTrey), and Filtek P60 (3M Dental Products). Dynamic torsional loading was conducted in the frequency range from 1 to 150 Hz. Composite specimens were tested after storage in water at 37°C for 24 h. One group was thermal cycled for 3000 cycles with temperatures of 5–37–50°C. Measurements were taken at 21°C dry, and at 37 and 50°C wet. Storage modulus, loss tangent, and other viscoelastic parameters were determined from the amplitude/frequency curves. Data for storage modulus and loss tangent of the materials were analyzed by means of ANOVA and Student‐Newman‐Keuls test (α = 0.05). It was found that there were significant differences (P < 0.001) in storage modulus and loss tangent among the packable composites tested. The highest value of storage modulus, in measurements at 21°C, was for Alert (10.3 GPa), followed by Filtek P60 (9.31 GPa), Surefil (7.29 GPa), and Prodigy Condensable (6.74 GPa). There were significant differences (P < 0.001) in storage modulus and loss tangent among the four different conditions tested. Storage modulus decreased at higher temperatures, whereas the loss tangent increased. Thermal cycling increased storage modulus and decreased loss tangent. The results showed that both monomer and filler composition and filler loading of the materials significantly affect their viscoelastic functions, and the mechanical properties of the products cannot be characterized from the packability alone. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 71B: 327–335, 2004
Opsonization of polyethylene wear particles regulates macrophage and osteoblast responses in vitro
Authors: Elfick A.P.D. , Green S.M. , McCaskie A.W. , Birch M.A. 
Published: September 2004

AbstractThe cellular reaction to wear debris may result in the failure of an artificial joint's fixation to the skeleton. The influence of debris opsinization on cell activity has received little attention. This study seeks to establish whether different proteinaceous culture environments may invoke variant cellular responses to debris challenge. Consideration of the zeta potential of a low density polyethylene particle group and an ex vitro ultrahigh molecular weight polyethylene particle group revealed that the nature of the protein adsorbants is related to the concentration of the proteins in solution. Furthermore, the composition of the adsorbed layer was shown to vary with the spectra of proteins in solution. In standard cell culture conditions zeta potential approached zero, indicating the high probability of particle agglomeration. Cell challenge studies with U937 macrophages showed that BSA and FCS protein adsorption mediated increased cell adhesion, while bovine IgG showed little change over control values. No changes in behavior of osteoblastic cells were observed in similar experiments. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 71B: 244–251, 2004
Somatic gene targeting with RNA/DNA chimeric oligonucleotides: an analysis with a sensitive reporter mouse system
Authors: Ino Asami , Yamamoto Seiji , Kaneda Yasufumi , Kobayashi Ichizo 
Published: September 2004

AbstractBackgroundTargeted gene correction provides a potentially powerful method for gene therapy. RNA/DNA chimeric oligonucleotides were reported to be able to correct a point mutation with a high efficiency in cultured rodent cells, in the body of mice and rats, and in plants. The efficiency of correction in the liver of rats was claimed to be as high as 20% after tail‐vein injection. However, several laboratories have failed to reproduce the high efficiency.MethodsIn order to sensitively detect and measure sequence changes by the chimeric oligonucleotides, we used Muta™Mouse, a transgenic mouse system for mutation detection in vivo. It carries, on its chromosome, multiple copies of the lambda phage genome with the lacZ+ gene. Two chimeric oligonucleotides were designed to make a point mutation at the active site of the LacZ gene product. They were injected into the liver with HVJ liposomes, which were demonstrated to allow reliable gene delivery. One week later, DNA was extracted from the liver, and lambda::lacZ particles were recovered by in vitro packaging. The lacZ‐negative phage was detected by selection with phenyl‐beta‐D‐galactoside.ResultsThe mutant frequency of the injected mice was at the same level as the control mouse (∼1/10000). Our further restriction analysis and sequencing did not detect the designed mutations.ConclusionsGene correction frequency in mouse liver by these oligonucleotides was shown to be less than 1/20000 in our assay with the Muta™Mouse system. Copyright © 2004 John Wiley & Sons, Ltd.
Production of lentiviral vectors by transient expression of minimal packaging genes from recombinant adenoviruses
Authors: Kuate Seraphin , Stefanou Daniela , Hoffmann Dennis , Wildner Oliver , Überla Klaus 
Published: September 2004

AbstractBackgroundThe potential of lentiviral vectors for clinical gene therapy has not yet been evaluated. One of the reasons is the cytotoxicity of lentiviral packaging genes which makes the generation of stable producer cell lines difficult. Therefore, a novel packaging system for lentiviral vectors based on transient expression of packaging genes by recombinant adenoviruses was developed.MethodsAdenoviral vectors expressing VSV‐G, codon‐optimized HIV‐1 gag‐pol, and codon‐optimized SIV gag‐pol under the control of a tetracycline‐regulatable promoter (adenoviral lenti‐pack vectors) were constructed and the production levels of this vector system were evaluated.ResultsThe generated adenoviral lenti‐pack vectors could be grown to high titers when transgene expression was suppressed and no evidence for instabilities was obtained. Cells stably transfected with a SIV‐based vector construct were converted into lentiviral vector producer cells by infection with the adenoviral lenti‐pack vectors. Lentiviral vector titers obtained were as high as vector titers obtained by transient cotransfection experiments. A protocol was developed that allowed preparation of lentiviral vector stocks with undetectable levels of contaminating adenoviral lenti‐pack vectors.ConclusionsThe adenoviral lenti‐pack vectors described should provide a convenient alternative approach to inducible packaging cell lines for large‐scale lentiviral vector production. Transient expression of cytotoxic lentiviral packaging genes by the adenoviral lenti‐pack vectors circumvents loss of titers during prolonged culture of packaging cell lines. The design of the adenoviral lenti‐pack vectors should reduce the risk of transfer of packaging genes to target cells and at the same time provide flexibility with respect to the lentiviral vector constructs that can be packaged. Copyright © 2004 John Wiley & Sons, Ltd.
Widespread gene transduction to the central nervous system by adenovirus in utero: implication for prenatal gene therapy to brain involvement of lysosomal storage disease
Authors: Shen Jin‐Song , Meng Xing‐Li , Maeda Hiroshi , Ohashi Toya , Eto Yoshikatsu 
Published: September 2004

AbstractBackgroundIn some lysosomal storage diseases, considerable alterations of the central nervous system (CNS) occur prior to birth and neurodegeneration progresses rapidly soon after birth causing early death in patients. No effective treatment is available after birth. Treatment may need to be initiated before birth to prevent the onset or progression of neurological changes and thereby irreversible brain damage. The aim of this study is to investigate the feasibility and effectiveness of brain‐directed prenatal gene therapy for lysosomal storage diseases.MethodsRecombinant adenovirus encoding the lacZ gene was injected into the lateral ventricles of mouse embryos and the pattern of gene transduction to the CNS was investigated. In the therapeutic experiment, adenovirus expressing β‐glucuronidase was injected into the cerebral ventricles of the embryos of mucopolysaccharidosis VII mice and the therapeutic effects on the brain were evaluated.ResultsInjection of adenoviral vectors to the cerebral ventricles of mouse embryos led to widespread gene transduction throughout the brain and the spinal cord and transgene expression persisted over 10 months in those surviving the procedure. The prenatal transduction of the therapeutic gene to the brain of the mucopolysaccharidosis VII mouse efficiently prevented lysosomal storage in most brain cells before birth until 4 months after birth.ConclusionsBrain‐directed in utero gene therapy through an intra‐ventricular route would be an effective strategy to treat some lysosomal storage diseases with early and severe CNS alterations. Copyright © 2004 John Wiley & Sons, Ltd.