bluuebunny/crossref_metadata_2025 huggingface dataset:
Regulatory Mechanisms Controlling Gene Expression Mediated by the Antioxidant Response Element
Authors: Nguyen Truyen , Sherratt Philip J. , Pickett Cecil B.
Published: January 2003

The expression of genes encoding antioxidative and Phase II detoxification enzymes is induced in cells exposed to electrophilic compounds and phenolic antioxidants. Induction of these enzymes is regulated at the transcriptional level and is mediated by a specific enhancer, the antioxidant response element or ARE, found in the promoter of the enzyme's gene. The transcription factor Nrf2 has been implicated as the central protein that interacts with the ARE to activate gene transcription constitutively or in response to an oxidative stress signal. This review focuses on the molecular mechanisms whereby the trancriptional activation mediated by the interaction between the ARE and NF-E2-related factor 2 (Nrf2) is regulated. Recent studies suggest that the sequence context of the ARE, the nature of the chemical inducers, and the cell type are important for determining the activity of the enhancer in a particular gene.
K+ Channel Structure-Activity Relationships and Mechanisms of Drug-Induced QT Prolongation
Authors: Clancy Colleen E. , Kurokawa Junko , Tateyama Michihiro , Wehrens Xander H.T. , Kass Robert S.
Published: January 2003

Pharmacological intervention, often for the purpose of treating syndromes unrelated to cardiac disease, can increase the vulnerability of some patients to life-threatening rhythm disturbances. This may be due to an underlying propensity stemming from genetic defects or polymorphisms, or structural abnormalities that provide a substrate allowing for the initiation of arrhythmic triggers. A number of pharmacological agents that have proven useful in the treatment of allergic reactions, gastrointestinal disorders, and psychotic disorders, among others, have been shown to reduce repolarizing K+ currents and prolong the QT interval on the electrocardiogram. Understanding the structural determinants of K+ channel blockade may provide new insights into the mechanism and rate-dependent effects of drugs on cellular physiology. Drug-induced disruption of cellular repolarization underlies electrocardiographic abnormalities that are diagnostic indicators of arrhythmia susceptibility.
Alzheimer's Disease: Molecular Understanding Predicts Amyloid-Based Therapeutics
Authors: Selkoe Dennis J. , Schenk Dale
Published: January 2003

Degenerative diseases of the brain were long considered among the most obscure and intractable of human maladies. However, recent advances in understanding their mechanisms have brought us to the verge of potential disease-modifying agents. This progress is perhaps best exemplified by the case of Alzheimer's disease. The application of molecular pathology and genetics has led to the recognition that the four genes implicated to date in familial Alzheimer's disease all chronically elevate cerebral levels of the amyloid β-protein (Aβ). Accordingly, small molecule inhibitors of the β- and γ-secretases, the proteases that generate Aβ from its precursor, are under active development, and some have shown in vivo efficacy in mouse models. An alternative approach, active or passive immunization against Aβ, has received extensive pre-clinical validation in mice, but an effective preparation free of significant side effects in humans is still awaited. Several other potential therapies are also reviewed here. If one or more of these varied approaches is ultimately proven to slow or prevent dementia, Alzheimer's disease will become a salient example of the successful application of reductionist biology to the most complex of organs, the human cerebral cortex.
Human Extrahepatic Cytochromes P450: Function in Xenobiotic Metabolism and Tissue-Selective Chemical Toxicity in the Respiratory and Gastrointestinal Tracts
Authors: Ding Xinxin , Kaminsky Laurence S.
Published: January 2003

Cytochrome P450 (CYP) enzymes in extrahepatic tissues often play a dominant role in target tissue metabolic activation of xenobiotic compounds. They may also determine drug efficacy and influence the tissue burden of foreign chemicals or bioavailability of therapeutic agents. This review focuses on xenobiotic-metabolizing CYPs of the human respiratory and gastrointestinal tracts, including the lung, trachea, nasal respiratory and olfactory mucosa, esophagus, stomach, small intestine, and colon. Many CYPs are expressed in one or more of these organs, including CYP1A1, CYP1A2, CYP1B1, CYP2A6, CYP2A13, CYP2B6, CYP2C8, CYP2C9, CYP2C18, CYP2C19, CYP2D6, CYP2E1, CYP2F1, CYP2J2, CYP2S1, CYP3A4, CYP3A5, and CYP4B1. Of particular interest are the preferential expression of certain CYPs in the respiratory tract and the regional differences in CYP expression profile in different parts of the gastrointestinal tract. Current research activities on the characterization of CYP expression, function, and regulation in these tissues, as well as future research needs, are discussed.
Gene Therapy with Viral Vectors
Authors: Kootstra Neeltje A. , Verma Inder M.
Published: January 2003

A key factor in the success of gene therapy is the development of gene delivery systems that are capable of efficient gene transfer in a broad variety of tissues, without causing any pathogenic effect. Currently, viral vectors based on many different viruses have been developed, and their performance and pathogenicity has been evaluated in animal models. The results of these studies form the basis for the first clinical trials for correcting genetic disorders using retroviral, adenoviral, and adeno-associated viral vectors. Even though the results of these trials are encouraging, vector development is still required to improve and refine future treatment of hereditary disorders.
Fast Lithium-Ion Conducting Glass-Ceramics in the System Li2 S  ­ SiS2 ­  P 2 S 5
Authors: Hayashi Akitoshi , Ishikawa Yoshiharu , Hama Shigenori , Minami Tsutomu , Tatsumisago Masahiro
Published: January 2003

Novel glass-ceramics solid electrolytes were prepared from mechanically milled glassy powders in the ternary system

Li

2

S
­

SiS

2

­

P

2

S

5

.

With an increase in the heat-treatment temperature, an ambient temperature conductivity of the obtained glass-ceramics reached

1.2
×

10

−
3

S

cm

−
1

,

which is higher than the maximum conductivity of the solid solutions in the system

Li

4

SiS

4

­

Li

3

PS

4

.

The enhancement on conductivity by heat-treatment over the crystallization temperature is due to the formation of the highly conductive crystalline phase with the same superlattice structure as the thio-LISICON phase of

Li

4
−
x

Ge

1
−
x

P

x

S

4

(
0.6
<
x
<
0.8
)

showing high conductivities over

10

−
3

S

cm

−
1

at room temperature. © 2003 The Electrochemical Society. All rights reserved.
Selective Copper Deposition on Barrier Layer Ta and TaN in the Presence of a Copper Seed Layer
Authors: Liu Chong-yang , Bard Allen J.
Published: January 2003

Electrochemical deposition of copper on exposed barrier layer (Ta and TaN) was carried out without deposition on an existing Cu seed layer on the same substrate. This was accomplished by immersing the sample in a solution of 1 mM 1-dodecanethiol (RSH) in ethanol, where preferential adsorption of a self-assembled monolayer of RSH deactivated the copper surface. The Cu seed layer could be reactivated again by applying a negative potential pulse. Such an externally controlled reversible change in surface chemistry toward copper deposition is potentially useful for a copper seed layer repair in the fabrication of contacts and interconnects for integrated circuits. © 2003 The Electrochemical Society. All rights reserved.
Transcriptional regulation of the cystathionine-β-synthase gene in Down syndrome and non–Down syndrome megakaryocytic leukemia cell lines
Authors: Ge Yubin , Jensen Tanya L. , Matherly Larry H. , Taub Jeffrey W.
Published: January 2003

Children with Down syndrome (DS) with acute myeloid leukemia (AML) have significantly higher event-free survival rates compared to those with non-DS AML, linked to greater cytosine arabinoside (ara-C) sensitivity and higher transcript levels of the chromosome 21–localized gene, cystathionine-β-synthase(CBS), in DS myeloblasts. In this study, we examined the transcriptional regulation of the CBS gene in the DS megakaryocytic leukemia (AMkL) cell line, CMK, characterized by significantly higher CBS transcripts compared with the non-DS AMkL cell line, CMS. Rapid amplification of 5′-cDNA ends (5′-RACE) analysis demonstrated exclusive use of the CBS−1b promoter in the cell lines, and transient transfections with the full-length CBS −1b luciferase reporter gene construct showed 40-fold greater promoter activity in the CMK than CMS cells. Electrophoretic mobility shift assays showed enhanced binding of the transcription factors Sp1/Sp3 to 2 GC/GT-box elements (GC-f and GT-d) in the upstream regions of the CBS −1b promoter in CMK nuclear extracts and undetectable binding in CMS cells. Mutation of the GC-f– or GT-d–binding site resulted in an approximately 90% decrease of theCBS −1b promoter activity in transient transfections of CMK cells. Chromatin immunoprecipitation assays confirmed in vivo binding of Sp3, USF-1, and nuclear factor YA (NF-YA) to theCBS −1b promoter region in chromatin extracts of CMK and CMS cells. Decreased binding of Sp1/Sp3 in CMK nuclear extracts following treatment with calf alkaline phosphatase suggested a role for phosphorylation of Sp1/Sp3 in regulating CBS promoter activity and in the differential CBS expression between CMK and CMS cells. The results of this study with clinically relevant cell line models suggest potential mechanisms for disparate patterns ofCBS gene expression in DS and non-DS myeloblasts and may, in part, explain the greater sensitivity to chemotherapy shown by patients with DS AML.
Microvoids Present in Anisotropic Mesophase Pitch, Their As-spun and Annealed Fibers
Authors: Yang Hojung , Yoon Seong-Ho , Korai Yozo , Mochida Isao , Katou Osamu
Published: January 2003

The sizes of free volumes in the mesophase pitches, as-spun and annealed fibers were measured by positron annihilation lifetime spectroscopy (PALS). The size of free volume increased with increasing of methyl groups in the mesogen molecules. Spinning increased the free volume while annealing after the spinning decreased it to similar value of the starting pitch.
Unusual Oxidation of Dichalcogenido Complexes of Platinum
Authors: Nagata Kazuto , Takeda Nobuhiro , Tokitoh Norihiro
Published: January 2003

Novel platinum complexes having an oxochalcogenido ligand such as S2O, Se2O, S2O3, and SeO3 were synthesized by the oxidation reactions of the overcrowded dichalcogenido platinum complexes [(BbtMe2P)2PtX2] (Bbt = 2,6-bis[bis(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl; X = S, Se).
Nanoscale Palladium Cluster Immobilized on a TiO2 Surface as an Efficient Catalyst for Liquid-phase Wacker Oxidation of Higher Terminal Olefins
Authors: Choi Kwang-Min , Mizugaki Tomoo , Ebitani Kohki , Kaneda Kiyotomi
Published: January 2003

A Pd nanocluster immobilized on a TiO2 surface acted as an efficient catalyst for the liquid-phase Wacker oxidation of higher terminal olefins in the presence of water and CuCl2 under an O2 atmosphere.
Liquid-Liquid Micro Batch Extraction System for Rapid Separation
Authors: Sasaki Takayuki , Takamiya Koichi
Published: January 2003

The liquid-liquid micro batch extraction system, LMES, was developed for rapid separation of a trace amount of metal ions. The equipment is composed of three simple extraction cells for phase mixing, phase separation, and solvent collection. Separation could be completed in a single operation lasting only a minute, from solvent extraction to preparation for alpha-ray spectrometry.
Silica Gel Fabrication of [60]Fullerene Aggregates Utilizing Poly(N-vinylpyrrolidone) as a “Glue”
Authors: Asai Masayoshi , Fujita Norifumi , Shinkai Seiji
Published: January 2003

Sol-gel polycondensation of tetraethoxysilane in the presence of [60]fullerene/poly(N-vinylpyrrolidone) (PVP) complex yielded novel silica particles composed of [60]fullerene, PVP and thin silica layer.
The New and Efficient Synthesis of a Heptose Moiety of Spicamycin
Authors: Suzuki Tamotsu , Chida Noritaka
Published: January 2003

The new and efficient synthesis of 7-O-acetyl-4-azido-2,3,6-tri-O-benzyl-4-deoxy-l-glycero-α-l-manno-heptopyranosyl acetate (5), a key intermediate for the synthesis of novel anti-cancer antibiotic, spicamycin (1), starting from d-ribose is described.
Cationic Silver Nanoparticles Dispersed in Water Prepared from Insoluble Salts
Authors: Yonezawa Tetsu , Genda Hideo , Koumoto Kunihito
Published: January 2003

Homogeneous and uniform-sized silver nanoparticles were obtained by reduction of insoluble silver halides. As the stabilizing reagent, a small cationic thiol, thiocholine bromide, was used. Even from large crystals of silver halides, nanosized particles were obtained. Under the optimum conditions, highly monodispersed nanoparticles with relative standard deviation of less than 7% were obtained.
Numerous microRNPs in neuronal cells containing novel microRNAs
Authors: DOSTIE JOSÉE , MOURELATOS ZISSIMOS , YANG MICHAEL , SHARMA ANUP , DREYFUSS GIDEON
Published: January 2003

Spinal muscular atrophy (SMA) is a common neurodegenerative disease that is caused by deletions or loss-of-function mutations in the Survival of Motor Neuron (SMN) protein. SMN is part of a large complex that functions in the assembly/restructuring of ribonucleoprotein (RNP) complexes. We recently showed in HeLa cells that two components of the SMN complex, Gemin3 and Gemin4, together with the argonaute protein eIF2C2, also associate with microRNAs (miRNAs) as part of a novel class of RNPs termed miRNPs. Here we report on miRNPs isolated from neuronal cell lines of mouse and human, and describe 53 novel miRNAs. Several of these miRNAs are conserved in divergent organisms, including rat, zebrafish, pufferfish, and the nematode Caenorhabditis elegans. The chromosomal locations of most of the novel miRNAs were identified and indicate some phylogenetic conservation of the likely precursor structures. Interestingly the gene locus of one miRNA, miR-175, is a candidate region for two neurologic diseases: early-onset parkinsonism (Waisman syndrome) and X-linked mental retardation (MRX3). Also, several miRNAs identified as part of miRNPs in these cells appear to constitute two distinct subfamilies. These subfamilies comprise multiple copies of miRNAs on different chromosomes, suggesting an important function in the regulation of gene expression.
Analysis of recombinant yeast decapping enzyme
Authors: STEIGER MICHELLE , CARR-SCHMID ANNE , SCHWARTZ DAVID C. , KILEDJIAN MEGERDITCH , PARKER ROY
Published: January 2003

A critical step in the turnover of yeast mRNAs is decapping. Two yeast proteins, Dcp1p and Dcp2p, are absolutely required for decapping, although their precise roles in the decapping reaction have not been established. To determine the function of both Dcp1p and Dcp2p in decapping, we purified recombinant versions of these proteins from Escherichia coli and examined their properties. These experiments demonstrate that copurification of Dcp1p and Dcp2p yields active decapping enzyme under a variety of conditions. Moreover, Dcp2p alone can have decapping activity under some biochemical conditions. This suggests that Dcp2p can be a catalytic subunit of the decapping complex, and Dcp1p may function to enhance Dcp2p activity, or as an additional active subunit. In addition, recombinant Dcp1p/Dcp2p prefers long mRNA substrates and is sensitive to inhibition by sequestration of the 5′ end but not the 3′ end of the substrate. This suggests that Dcp1p/Dcp2p contains an additional RNA-binding site spatially distinct from the active site. Finally, using two RNA-binding proteins that enhance decapping in vivo (Edc1p and Edc2p), we can reconstitute the activation of decapping with recombinant proteins. This indicates that the Edc1 and Edc2 proteins act directly on the decapping enzyme.
After the ribosome structures: How are the subunits assembled?
Authors: WILLIAMSON JAMES R.
Published: January 2003

The recent structures of the ribosome and the ribosomal subunits only heighten the intrigue of trying to understand how the ribosome is assembled. Biochemical and mechanistic studies have mapped out the basic series of protein binding events that occur, but we do not yet have a clear picture of the RNA conformational changes that must accompany the protein binding. Recent studies point to roles of protein folding chaperones and RNA helicases as facilitators of ribosome assembly, but the basic process of assembly seems to be encoded in the RNA sequences and can occur for the most part spontaneously in vitro, and quite possibly in vivo as well.
The enhancer of decapping proteins, Edc1p and Edc2p, bind RNA and stimulate the activity of the decapping enzyme
Authors: SCHWARTZ DAVID , DECKER CAROLYN J. , PARKER ROY
Published: January 2003

A major pathway of eukaryotic mRNA turnover initiates with deadenylation, which allows a decapping reaction leading to 5′–3′ exonucleolytic degradation. A key control point in this pathway is the decapping of the mRNA. Two proteins, Edc1 and Edc2, were genetically identified previously as enhancers of the decapping reaction. In this work, we demonstrate that Edc1p and Edc2p are RNA-binding proteins. In addition, recombinant Edc1p or Edc2p stimulates mRNA decapping in cell-free extracts or with purified decapping enzyme. These results suggest that Edc1p and Edc2p activate decapping directly by binding to the mRNA substrate and enhancing the activity of the decapping enzyme. Interestingly, edc1Δ strains show defects in utilization of glycerol as a carbon source and misregulation of several mRNAs in response to carbon-source changes. This identifies a critical role for decapping and Edc1p in alterations of gene expression in response to carbon-source changes.
Of urchins and men: Evolution of an alternative splicing unit in fibroblast growth factor receptor genes
Authors: MISTRY NEVILLE , HARRINGTON WHITNEY , LASDA ERIKA , WAGNER ERIC J. , GARCIA-BLANCO MARIANO A.
Published: January 2003

Alternative splicing of mammalian transcripts, which yields many diverse protein products from one gene, is the rule and not the exception. Although the mechanisms that govern alternative splicing are being unraveled, little is known about the evolution of this critical engine of proteome diversity. Here we present a phylogenetic analysis from a sea urchin to humans of the alternative splicing unit encoding the third Ig domain of fibroblast growth factor receptors. The remarkable conservation of intronic control elements, both in structure and function, indicates that the mechanisms that regulate this alternative splicing unit evolved over 600 million years ago.
RNAi: Mammalian oocytes do it without RNA-dependent RNA polymerase
Authors: STEIN PAULA , SVOBODA PETR , ANGER MARTIN , SCHULTZ RICHARD M.
Published: January 2003

Studies in mutant organisms deficient in RNA interference (RNAi) and related post-transcriptional gene silencing implicated a role for a single class of RNA-dependent RNA polymerases (RdRp). Nevertheless, sequence homologs to these RdRps have not been found in coelomate organisms such as Drosophila or mammals. This lack of homologous sequences does not exclude that an RdRp functions in RNAi in these organisms because an RdRp could be acquired by horizontal transfer from an RNA virus. In fact, such a sequence is found in mice (Aquarius) and we observe that it is expressed in mouse oocytes and early embryos, which exhibit RNAi. We report here that cordycepin, an inhibitor of RNA synthesis, does not prevent Mos double-strand RNA (dsRNA) to target endogenous Mos mRNA in mouse oocytes and that targeting a chimeric Mos–EGFP mRNA with dsRNA to EGFP does not reduce the endogenous Mos mRNA, but does target the chimeric mRNA. These results indicate that an RdRp is not involved in dsRNA-mediated mRNA degradation in mammalian oocytes, and possibly in mammals in general, and therefore that only homologous sequences to the dsRNA are targeted for degradation.
Recycling of ethylene propylene diene monomer (EPDM) waste. III. Processability of EPDM rubber compound containing ground EPDM vulcanizates
Authors: Jacob Ceni , Bhattacharya A. K. , Bhowmick A. K. , De P. P. , De S. K.
Published: January 2003

The rheological behavior of ethylene propylene diene monomer (EPDM) compounds containing ground EPDM waste (W‐EPDM) of known composition was studied by using a Monsanto processability tester in a temperature range of 90–110°C and a shear rate range of 306.7–1533.24 s−1. It is found that the shear viscosity decreases slightly with increasing W‐EPDM loading because of wall slip that results from the migration of lubricants from the W‐EPDM. The addition of W‐EPDM to raw EPDM results in a decreased die swell at all temperatures and shear rates. SEM photomicrographs of the EPDM extrudate surface show improved surface smoothness and reduced extrudate distortion when EPDM is blended with W‐EPDM. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2204–2215, 2003
Rubber–clay nanocomposite by solution blending
Authors: Pramanik Monoj , Srivastava Suneel Kumar , Samantaray Biswas Kumar , Bhowmick Anil Kumar
Published: January 2003

Ethylene vinyl acetate rubber (45% vinyl acetate content, EVA‐45) and organomodified clay (12Me‐MMT) composites were prepared by solution blending of the rubber and the clay. A combination of X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy studies showed that the composites obtained are on the nanometer scale. The measurements of the dynamic mechanical properties for different compositions over a temperature range (−100 to +100°C) showed that the storage moduli of these rubber–clay nanocomposites are higher above the glass to rubber transition temperature compared to the neat rubber. The tensile strength of the nanocomposites is about 1.6 times higher than that of the EVA‐45. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2216–2220, 2003
Chemical modification of chitosan: Synthesis and characterization of chitosan‐crown ethers
Authors: Changhong Peng , Weijun Yang , Motang Tang
Published: January 2003

Four novel Schiff‐type chitosan (CTS)‐crown ethers were synthesized through a reaction between NH2 in CTS or crosslinked chitosan (CCTS) and CHO in 4′‐formylbenzo‐crown ethers, and four secondary‐amino‐type CTS‐crown ethers were prepared through the reduced reaction of NaBH4, respectively. Their structures were characterized by elemental analysis, Fourier transform infrared (FTIR) spectra analysis, solid‐state 13C‐NMR analysis, and X‐ray diffraction (XRD) analysis. The elemental analysis results showed that the percentage of nitrogen in all CTS‐crown ethers were lower than that of CTS or CCTS. From the FTIR data of CTS, CCTS, and CTS‐crown ethers I–VIII, we saw that the characteristic peaks of CN, NH, and Ar appeared and that the characteristic peaks of pyranoside in the chain of CTS or CCTS were not destroyed. The XRD spectra demonstrated that CTS‐crown ethers I–VIII gave lower crystallinities than CTS or CCTS, which indicated that these compounds were considerably more amorphous than CTS or CCTS. In the solid‐state 13C‐NMR spectra, all of these CTS‐crown ethers had a particular peak of aromatic at 128 or 129 ppm, and the greatest difference between Schiff‐type CTS‐crown ethers and secondary‐amino‐type CTS‐crown ethers was that the Schiff‐type CTS‐crown ethers had the particular peak of CN, which disappeared in secondary‐type CTS‐crown ethers. All these facts confirmed that the structures of CTS‐crown ethers I–VIII were as expected. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2221–2225, 2003
Some features of phenolic inhibitor consumption in oxidized polypropylene in the presence of synergists–hydroperoxide decomposers
Authors: Shanina E. L. , Zaikov G. E. , Mukmeneva N. A.
Published: January 2003

The influence of sulfur and phosphors containing substances, hydroperoxide decomposers, on the kinetics of the consumption of two phenolic antioxidants in polypropylene (PP) was studied. The induction periods of PP autoxidation at 130°C were measured in the presence of inhibiting compositions that consisted of phenolic inhibitors and decomposers of hydroperoxide. The obtained results indicated that the influence of the hydroperoxide decomposer became significant when the concentration of the phenolic antioxidant became close to a critical value. It was shown also that the influence of the hydroperoxide decomposer significantly depended on the mechanism of the phenolic inhibitor transformation: first of all, on the nature of its transformation products. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2226–2229, 2003
Synthesis of new free‐radical initiators for polymerization
Authors: Gawdzik B. , Ksiȩżopolski J. , Matynia T.
Published: January 2003

Synthesis and properties of new initiating systems formed from commercially available ketones, glycols, and hydrogen peroxide (60%) are presented. In preparation of free radical initiators methyl ethyl ketone, which was oxidized by hydrogen peroxide, was used. Reaction was carried out in etanodiol or 1,4‐butanodiol as diluent. The obtained initiators with cobalt octoate as a promotor were applied for crosslinking of the commercially available unsaturated polyester resin. Properties of the resin were compared with those obtained while it was hardened by the typical curing system containing methyl ethyl ketone hydroperoxide and cobalt octoate. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2238–2243, 2003
Studies on the structure of activated carbon fibers activated by phosphoric acid
Authors: Fu Ruowen , Liu Ling , Huang Wenqiang , Sun Pingchun
Published: January 2003

By solid‐state 13C‐ and 31P‐NMR, XPS, and FTIR, the chemical structure of activated carbon fiber–P (ACF‐P) and its reaction with phosphoric acid were studied. Even when activated at low temperatures, these fibers developed a graphitelike carbon structure with a certain amount of phenol groups as well as acetal (or methylenedioxy) carbon. As expected, the oxygen‐containing groups were greatly reduced at high activation temperatures. Different from the ACF‐W, metaphosphoric acid (or polyphosphates) and a small amount of phosphorus exist on ACF‐P. The original ACF‐P activated at low temperature contained a lot of phosphoric acid, so it had to be washed with water to expose the large surface area. The washing process can be omitted for ACF‐P activated at high temperature because most phosphorus compounds in fiber have volatilized. The ACF‐P activated at lower temperature possessed a large amount of oxygen‐containing surface groups and had enhanced adsorption ability for polar adsorbates. The remaining of metaphosphoric acid enhanced the adsorption of silver ion. The experimental results showed that the peaks of 31P‐NMR, P2p‐XPS, and FTIR at 1620 cm−1 shifted with the increase of activated temperature. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2253–2261, 2003
Study on swelling behavior and pervaporation properties of AA–MMA–BA copolymers for separation of methanol/MTBE/C5 mixtures
Authors: Zhang Lin , Chen Huan‐Lin , Pan Zu‐Ren
Published: January 2003

In this study, the copolymers with different ratios of AA(acrylic acid)–MMA(methyl methacrylate)–BA (butyl acrylate) are synthesized to prepare pervaporation membrane for the separation of methanol/MTBE (methyl tert‐butyl ether)/C5 mixtures. Swelling experiment of these copolymers in pure methanol, MTBE, C5, and methanol/MTBE mixtures are carried out, respectively. The results show that there is a strong interaction between MTBE and copolymer with high content of BA. The pervaporation characteristics of the membranes prepared with different copolymer are measured in the separation of methanol/MTBE mixture. The experimental results show that the pervaporation ability changes with swelling degree in the same direction. The copolymers are characterized by FTIR. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2267–2271, 2003
New fluoro‐modified thermoplastic polyurethanes
Authors: Tonelli Claudio , Ajroldi Giuseppe
Published: January 2003

New fluoro‐modified thermoplastic polyurethanes containing perfluoropolyether (PFPE) blocks were synthesized by the reaction of a fluorinated macrodiol with a hydrogenated prepolymer based on poly(tetramethylene glycol) and 4,4′‐methylene‐bis‐phenylisocyanate, followed by subsequent chain extension with 1,4‐n‐butanediol. This multistep bulk process opened the way for a new family of polymeric materials whose tensile properties appear to be excellent and unchanged in comparison with the corresponding unmodified hydrogenated polymers. Dynamic mechanical analysis and differential scanning calorimetry revealed peculiar characteristics. These polymers showed an unusual multiphase structure in which not only the hard and the hydrogenated soft segments were self‐organized, but also a second soft phase, constituted by the PFPE segments, was present. Moreover, an easier hard‐phase segregation and self‐organization were observed, as was evidenced by the higher melting temperatures of the semicrystalline phase. This unique characteristic combined with a selective enrichment of PFPE segments to the surface, as indicated by the unusually low coefficient of friction data and superior chemical resistance. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2279–2294, 2003
Determination of refractive index profile of partially and highly oriented fibers using double refracting interference microscopy
Authors: El‐Bakary Mohammed A.
Published: January 2003

Double refracting polarizing interference microscope designed by Pluta is used with a suggested method to determine the refractive index profile and birefringence profile of partially and highly oriented fibers. The application of this method depends on using Pluta polarizing interference microscope in two positions (crossed position for the duplicated images and subtractive position for the nonduplicated image of the fiber). The mathematical representation of the suggested method is given. The refraction of the light beam inside the fibers is taken into consideration while measuring the fringe shift profile. The refractive index profiles of polypropylene fiber with draw ratio 3.5 are determined using the conventional method. The results are compared with those obtained with the suggested method and found to be in good agreement. The suggested method is applied to determine the refractive index profile of poly(aryl ether ether ketone) partially oriented fiber and poly(ethylene terephthalate) highly oriented fiber. The diffraction of He–Ne laser beam is used to determine the average diameters of these fibers. Microinterferograms are given for illustration. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2341–2347, 2003
Polyurethane‐infiltrated carbon foams: A coupling of thermal and mechanical properties
Authors: Bunning Timothy J. , Jeon Hong G. , Roy Ajit K. , Kearns Kristen M. , Farmer Barry L. , Adams Walter W.
Published: January 2003

The thermal and mechanical properties of polyurethane‐infiltrated carbon foam of various densities were investigated. By combining the high thermal conductivity of the carbon foam with the mechanical toughness of the pure polyurethane, a mechanically tough composite (relative to the unfilled foam) that could be used at higher temperatures than the polyurethane's degradation was formed. Both the tensile strength and the modulus increased by an order of magnitude for the composites compared to unfilled foam, while the compressive and shear strengths and moduli of the composites approached values exhibited by pure polyurethane. At both 300 and 400°C, the rectangular blocks of pure polyurethane lost their mechanical integrity due to decomposition in air. Thermogravimetric analysis confirms substantial initial weight loss above 290°C. Filled carbon foam blocks, however, maintain their mechanical integrity at both 300 and 400°C indefinitely, although the bulk of the rectangular block mass is polyurethane. Three different carbon foam densities are examined. As expected, the higher density foams show greater heat transfer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2348–2355, 2003
Natural weathering, artificial photo‐oxidation, and thermal aging of low density polyethylene: Grafting of acrylic acid onto aged polyethylene films
Authors: El‐Awady M. M.
Published: January 2003

The photo‐oxidation and thermal initiation changes of commercial low density polyethylene (LDPE) films used in greenhouse covering, in the presence or absence of ultraviolet (UV) stabilizer, were monitored by infrared (IR) spectroscopy, by mechanical tests and by applying the grafting of acrylic acid onto the aged films. It was found that the resistance of PE films to UV irradiation and heat initiation as proved by tensile strength and elongation at break % was better for stabilized PE films compared with the unstabilized ones. A simple correlation was not observed between the fall in mechanical properties and the rate of film oxidation. On the other hand, an almost linear relation was obviously noticed between the degree of PE oxidation (CO) measured by IR spectroscopy and the grafting level. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2365–2371, 2003
Sulfation of silk fibroin by sulfuric acid and anticoagulant activity
Authors: Tamada Yasushi
Published: January 2003

Silk fibroin (Bombyx mori) was sulfated with an aqueous sulfuric acid solution. The sulfated fibroin was characterized by Fourier transform infrared spectroscopy (FTIR), amino acid analysis, and gel filtration chromatography (GFC). Maximum yield was obtained at around 2–4 h, and it decreased at 6 h and more. The molecular size decreased and dispersed with sulfation, and the molecular weight was estimated at around 10,000 by GFC using protein standards. The amino acid composition indicated that the crystal region of the fibroin molecule remained in sulfated fibroin until a sulfation reaction time of 4 h. The incorporation of sulfate groups was confirmed by FTIR and the amount of sulfate groups introduced for 4 h sulfation was estimated in 0.3 mmol/g by acidimetric titration. The efficiency of sulfation was calculated at 15.7%. Blood coagulation was prevented by 20 mg of sulfated fibroin in 1 mL of blood, while original fibroin did not show the effect. This result indicates that sulfate group introduction results in addition of anticoagulant function to silk fibroin. Although a variety of polymer backbones have been used for synthesis of sulfated polymers as anticoagulant materials, no reports are available concerning a sulfated polymer based on a protein backbone. Sulfated fibroin is a new type of anticoagulant material having a protein backbone. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2377–2382, 2003
Development of new concepts for the control of polymerization processes: Multiobjective optimization and decision engineering. I. Application to emulsion homopolymerization of styrene
Authors: Massebeuf Silvère , Fonteix Christian , Hoppe Sandrine , Pla Fernand
Published: January 2003

This article deals with the development of a multicriteria analysis, and its application to the optimization of batch emulsion polymerization processes. This new approach in the domain of polymer reaction engineering illustrates how a multiobjective optimization aided by a genetic algorithm and using the Pareto concept of domination is useful. In this process (emulsion homopolymerization of styrene), several objectives were simultaneously required, e.g., a high quality of the resulting products together with a high productivity. The aim of this study was to find the optimal experimental conditions to obtain simultaneously the minimum reaction time and designed values for both average molecular weights and particles size. To do that, an adapted mathematical model, able to describe all the process physicochemical phenomena, was been first elaborated. The multicriteria analysis then gave a set of nondominated points with conflicting criteria. A decision support system was then developed and applied to rank the Pareto solutions set and to propose some good solutions by taking into account the decision maker's preferences. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2383–2396, 2003
Hydrophobic association and temperature and pH sensitivity of hydrophobically modified poly(N‐isopropylacrylamide/acrylic acid) gels
Authors: Tian Qin , Zhao Xian , Tang Xiaozhen , Zhang Yunxiang
Published: January 2003

Hydrophobically modified poly(acrylic acid/N‐isopropylacrylamide) gels were synthesized by the radical copolymerization of acrylic acid/N‐isopropylacrylamide with a small amount of the hydrophobic comonomer 2‐(N‐ethylperfluorooctanesulfoamido)ethyl acrylate, stearyl acrylate, or lauryl acrylate in tert‐butanol with ethylene glycol dimethacrylate as a crosslinker. Swelling kinetics and fluorescence measurements showed that the hydrophobic association ability of fluorocarbon groups was stronger than that of hydrocarbon analogues in modified hydrogels that contained both physical and chemical crosslinking networks. The effects of the fractions and the species of the hydrophobe on the gel swelling and pH and temperature sensitivity were studied. The results indicated that the swelling behavior and pH and temperature sensitivity of the gels were affected by the degree of hydrophobic modification. A hydrogel with a suitable 2‐(N‐ethylperfluorooctanesulfoamido)ethyl acrylate content (0.349 mol %) showed good pH and temperature sensitivity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2406–2413, 2003
Dynamic mechanical study on the thermal aging of a hydroxyl‐terminated polybutadiene‐based energetic composite
Authors: Fuente José Luis de la , Rodríguez Olga
Published: January 2003

In an attempt to determine the aging behavior of hydroxyl‐terminated polybutadiene‐based composite solid propellants, viscoelastic measurements were used to study the effect of thermal aging on this kind of energetic material. Accelerated‐aging tests at 40, 60, and 80°C were performed for 5000 h. The changes in the dynamic mechanical properties, including the storage modulus (E′) and loss factor or damping efficiency (tan δ), with time and temperature were measured to determine the aging rate and likely mechanisms occurring during this process. An Arrhenius analysis based on the determination of relative rate constants showed a linear tendency from tan δ values, whereas a significant curvature was found from E′ values. In addition, the effects of external (surface) and internal (core) sampling in the intensification of the aging process were analyzed. The results confirmed dynamic mechanical analysis as a powerful tool for determining the aging characteristics of composite propellants. This technique allows the evaluation of the actual state of a propellant grain with a small sample and a straightforward measurement. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 2397–2405, 2003
Molecular genetics of aging in the fly: Is this the end of the beginning?
Authors: Helfand Stephen L. , Rogina Blanka
Published: January 2003

How we age and what we can do about it have been uppermost in human thought since antiquity. The many false starts have frustrated experimentalists and theoretical arguments pronouncing the inevitability of the process have created a nihilistic climate among scientists and the public. The identification of single gene alterations that substantially extend life span in nematodes and flies however, have begun to reinvigorate the field. Drosophila's long history of contributions to aging research, rich storehouse of genetic information, and powerful molecular techniques make it an excellent system for studying the molecular mechanisms underlying the process of aging. In recent years, Drosophila has been used to test current theories on aging and explore new directions of potential importance to the biology of aging. One such example is the surprising finding that, as opposed to the commonly held assumption that adult life is a period of random passive decline in which all things are thought to fall apart, the molecular life of the adult fly appears to be a state of dynamic well‐regulated change. In the fly, the level of expression of many different genes changes in an invariant, often age‐dependent, manner. These as well as other molecular genetic studies and demographic analyses using the fly have begun to challenge widely held ideas about aging providing evidence that aging may be a much more dynamic and malleable process than anticipated. With the enormous success that Drosophila molecular genetics has demonstrated in helping understand complex biological phenomena such as development there is much optimism that similar approaches can be adapted to assist in understanding the process of aging. BioEssays 25:134–141, 2003. © 2003 Wiley Periodicals, Inc.
Levels of polymorphism on the sex‐limited chromosome: a clue to Y from W?
Authors: Ellegren Hans
Published: January 2003

Nucleotide diversity of the human Y chromosome is much lower than that in the rest of the genome. A new hypothesis postulates that this invariance may result from mutations in maternally inherited mitochondrial DNA (mtDNA), leading to impaired reproduction among males and lowered male effective population size. If correct, we should expect to see low levels of polymorphism in the male‐specific Y chromosome of many organisms but not necessarily in the female‐specific W chromosome in organisms with female heterogamety. However, recent observations from birds suggest that the avian W chromosome is very low in nucleotide diversity. This indicates that mtDNA mutations cannot broadly explain the evolution of the sex‐limited chromosome. Other work has suggested that sexual selection at loci involved in sex determination or secondary sexual characteristics might reduce levels of genetic variability on Y through hitch‐hiking effects. Although the W chromosome does not seen to play a dominant role for sex determination in birds, it cannot be excluded that selective sweeps arising from natural or sexual selection contribute to the low levels of genetic variability seen on this chromosome. BioEssays 25:163–167, 2003. © 2003 Wiley Periodicals, Inc.
Stem cells, telomerase and dyskeratosis congenita
Authors: Mason Philip J.
Published: January 2003

Dyskeratosis congenita is a rare skin and bone marrow failure syndrome caused by defective telomere maintenance in stem cells. The major X‐linked form of the disease is due to mutations in a nucleolar protein, dyskerin, that is part of small nucleolar ribonucleoprotein particles that are involved in processing ribosomal RNA. It is also found in the telomerase complex, pointing to an unexpected link between these two processes. An autosomal dominant form is due to mutations in the RNA component of telomerase (hTR). Patients with this form of the disease are more severely affected in later generations that carry the mutations, possibly due to the inheritance of shortened telomeres, disguising the inherited nature of the disease in some cases classified as aplastic anemia. Because of the importance of telomerase in tumour formation and aging, study of this disease may provide important clues about these fundamental processes. BioEssays 25:126–133, 2003. © 2003 Wiley Periodicals, Inc.
Detection of unpaired DNA at meiosis results in RNA‐mediated silencing
Authors: Hynes Michael J. , Todd Richard B.
Published: January 2003

During meiosis, homologous chromosomes must pair in order to permit recombination and correct chromosome segregation to occur. Two recent papers1,2 show that meiotic pairing is also important for correct gene expression during meiosis. They describe data for the filamentous fungus Neurospora crassa that show that a lack of pairing generated by ectopic integration of genes can result in silencing of genes expressed during meiosis. This can result in aberrant meioses whose defects are specific to the function of the unpaired gene. Furthermore, mutations affecting the silencing mechanism have been selected in a gene encoding a putative RNA‐dependent RNA polymerase. This finding indicates the involvement of a meiotic specific post‐transcriptional gene silencing mechanism (PTGS) similar to that observed in vegetative cells in N. crassa and other organisms. Finally, this gene product is essential for normal meiosis, suggesting that RNA‐dependent processes are fundamental to the sexual cycle. BioEssays 25:99–103, 2003. © 2003 Wiley Periodicals, Inc.
A new faculty orientation program: Building a core of new faculty to shape the future of the college
Authors: Welch Gerry F.
Published: January 2003

St. Louis Community College leadership recognized that a new large cohort of faculty hired to replace retiring instructors would shape the college over the next quarter century and beyond. The college challenged its staff development team to create a program that would integrate new faculty into the college and prepare them for the vital role they would play.
Web‐based faculty development using Time‐Revealed Scenarios
Authors: Nellis Patrick , Hosman David , King Jeffrey M. , Armstead Cathleen
Published: January 2003

Just as community colleges are making course work available to their students through a variety of delivery systems, so, too, are staff developers creating on‐line means of providing activities for their faculty. The on‐line faculty development programs at Valencia Community College, Orlando, Florida, and the Art Institute of Dallas use the Time‐Revealed Scenarios software program as the basis of their on‐line approach.
Leading change through faculty development
Authors: Rouseff‐Baker Fay
Published: January 2003

This chapter describes how a center for teaching and learning has become the catalyst for major institutional change through the use of faculty‐owned and ‐driven professional development programs, faculty leadership teams, and a supportive administration.
Presidents Academy: An evolution of leadership development
Authors: Boggs George R. , Kent Evelyn L.
Published: January 2003

This chapter discusses the Presidents Academy of the American Association of Community Colleges. The academy has evolved into a network made up of the nation's community college CEOs that provides a variety of practical leadership development and professional support programs.
Leadership development for the next generation
Authors: Watts Gordon E. , Hammons James O.
Published: January 2003

This chapter addresses the critical need for leadership development, the current options, and recommended solutions for meeting the training needs of a new generation of community college leaders.
Recent advances in retreats: Adapting the Great Teachers Seminar model to serve an entire college
Authors: Bergeron Pam , McHargue Mike
Published: January 2003

Despite the advanced technology on today's community college campuses, the need for sit‐around‐the‐campfire human interaction endures. One way to bring this interesting dichotomy together is through a retreat based on the Great Teachers Seminar model.
Analysis of high‐field RF coils using the method of lines
Authors: Bodganov Gene , Ludwig Reinhold
Published: January 2003

The method of lines is described as a novel and powerful way to analyze radio frequency (RF) coils for high‐field magnetic resonance imaging. Originally developed for optical and microwave circuits, this method enables a full‐wave solution to Maxwell's field equations without the computational burden of pure finite element or finite difference methods. Because only two of the three geometric dimensions are discretized, while seeking an analytic solution in the remaining space dimension, an efficient solution can be obtained at reasonable geometric restrictions. After outlining the theoretical formulation and the computer implementation of this technique, we will apply it to the modeling of microstrip RF transverse electromagnetic resonator coils at 200 and 400 MHz as well as a high‐pass shielded birdcage resonator and a single‐loop surface coil. With single‐frequency solutions obtainable within 5–10 s on a personal computer, the approach proves highly suitable as a design tool and for rapid prototyping. © 2003 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 16B: 22–37, 2003