bluuebunny/crossref_metadata_2025 huggingface dataset:
Upregulation of galectins‐1 and ‐3 in human colon cancer and their role in regulating cell migration
Authors: Hittelet Axel , Legendre Hugues , Nagy Nathalie , Bronckart Yves , Pector Jean‐Claude , Salmon Isabelle , Yeaton Paul , Gabius Hans‐Joachim , Kiss Robert , Camby Isabelle
Published: December 2002

To probe the potential contribution of β‐galactoside‐contributing epitopes and receptor proteins (gal‐1 and gal‐3) to colon malignancy, we first examined the expression of galectins and binding sites in clinical specimens by lectin and immunohistochemistry. Sixty‐seven colonic surgical resections were studied, including 10 normal, 10 mild dysplasias, 10 severe dysplasias and 37 cancers. gal‐1 and gal‐3 were expressed in variable amounts in the epithelial cells and the connective tissue of normal colon. Their expression significantly increased with the degree of dysplasia, suggesting that gal‐1 and gal‐3 and their binding sites are related to malignant progression, while gal‐8 has been associated with suppressor activity. To study the functional aspects, the influence of these galectins on the migration of 4 human colorectal cancer cell lines (HCT‐15, LoVo, DLD‐1, CoLo201) was studied. In agreement with histopathologic monitoring, these tumor cells were found to produce gal‐3, while only CoLo201 was positive for gal‐1. Except for DLD‐1 and gal‐1, the lines exhibited gal‐1 binding sites on the surface, prompting study by computer‐assisted videomicroscopy of the effect on cell migration of the presence of galectin on the culture substrate. The level of cell migration for HCT‐15, LoVo and CoLo201 cells was significantly reduced by 0.15 μg/cm2 gal‐1, and the presence of a blocking antibody at least reduced this effect. gal‐3 significantly reduced cell migration in all 4 of the in vitro cell lines. © 2002 Wiley‐Liss, Inc.
Inquiry projects in science teacher education: What can investigative experiences reveal about teacher thinking and eventual classroom practice?
Authors: Windschitl Mark
Published: December 2002

Science education reform documents emphasize the importance of inquiry experiences for young learners. This means that teachers must be prepared with the knowledge, skills, and habits of thinking to mentor their students through authentic investigations. This study examines how preservice teachers' inquiry experiences, in a science methods course, influenced and were influenced by their conceptions of inquiry. The study also assesses how these experiences were associated with eventual classroom practice. Six preservice secondary teachers were observed during a 2‐month inquiry project and then followed into the classroom as they began a 9‐week teaching practicum. Data revealed that participants' preproject conceptions of the inquiry process were related to the conduct and interpretation of their own inquiry project, and that the project experience modified the inquiry conceptions of those participants who already had sophisticated understandings of scientific investigations. Perhaps most importantly, the participants who eventually used guided and open inquiry during their student teaching were not those who had more authentic views of inquiry or reflected most deeply about their own inquiry projects, but rather they were individuals who had significant undergraduate or professional experiences with authentic science research. Finally, this article advocates that independent science investigations be part of preservice education and that these experiences should be scaffolded to prompt reflection specifically about the nature of inquiry and conceptually linked to ways in which inquiry can be brought into the K‐12 classroom. © 2002 Wiley Periodicals, Inc. Sci Ed 87:112–143, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/sce.10044
Portraying epistemology: School science in historical context
Authors: Rudolph John L.
Published: December 2002

Current debates over the nature of science in the school curriculum have centered on where the boundary between “traditional” science and other forms of knowledge should be drawn. What has been missing from these discussions, however, is a careful examination of how what lies within the boundary of “traditional” school science itself has been determined. Given the diversity of scientific practices and the inherent limitations of space in the curriculum, the portrayal of traditional science (its epistemology in particular) should be understood to be only a selective representation of the real‐world practices of science. Such representations are inevitably shaped by not just what scientists do, but also by the social and political context in which they are developed. Taking a historical perspective, the curricular ideas of John Dewey and Joseph Schwab are used to illustrate the subtle ways in which epistemological portrayals have been influenced by this sociohistorical context and the consequences those portrayals have had with respect to the public's relationship with institutional science in the United States at two key points during the twentieth century. © 2002 Wiley Periodicals, Inc. Sci Ed 87:64–79, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/sce.1055
Rotavirus gene silencing by small interfering RNAs
Authors: Déctor Miguel Angel , Romero Pedro , López Susana , Arias Carlos F.
Published: December 2002

RNA interference is an evolutionarily conserved double‐stranded RNA‐triggered mechanism for suppressing gene expression. Rotaviruses, the leading cause of severe diarrhea in young children, are formed by three concentric layers of protein, from which the spike protein VP4 projects. Here, we show that a small interfering RNA corresponding to the VP4 gene efficiently inhibits the synthesis of this protein in virus‐infected cells. A large proportion of infected cells had no detectable VP4 and the yield of viral progeny was reduced. Most of the virus particles purified from these cells were triple‐layered, but lacked VP4, and were poorly infectious. We also show that VP4 might not be required for the last step of virus morphogenesis. The VP4 gene silencing was specific, since the synthesis of VP4 from rotavirus strains that differ in the target sequence was not affected. These findings offer the possibility of carrying out reverse genetics in rotaviruses.
COP9 signalosome components play a role in the mating pheromone response of S. cerevisiae
Authors: Maytal‐Kivity Vered , Piran Ron , Pick Elah , Hofmann Kay , Glickman Michael H.
Published: December 2002

A family of genetically and structurally homologous complexes, the proteasome lid, Cop9 signalosome (CSN) and eukaryotic translation initiation factor 3, mediate different regulatory pathways. The CSN functions in numerous eukaryotes as a regulator of development and signaling, yet until now no evidence for a complex has been found in Saccharomyces cerevisiae. We identified a group of proteins, including a homolog of Csn5/Jab1 and four uncharacterized PCI components, that interact in a manner suggesting they form a complex analogous to the CSN in S. cerevisiae. These newly identified subunits play a role in adaptation to pheromone signaling. Deletants for individual subunits enhance pheromone response and increase mating efficiency. Overexpression of individual subunits or a human homolog mitigates sst2‐induced pheromone sensitivity. Csi1, a novel CSN interactor, exhibits opposite phenotypes. Deletants also accumulate Cdc53/cullin in a Rub1‐modified form; however, this role of the CSN appears to be distinct from that in the mating pathway.
Liver receptor homolog 1 controls the expression of the scavenger receptor class B type I
Authors: Schoonjans Kristina , Annicotte Jean‐Sebastien , Huby Thierry , Botrugno Oronza A. , Fayard Elisabeth , Ueda Yukihiko , Chapman John , Auwerx Johan
Published: December 2002

The scavenger receptor class B type I (SR‐BI), which mediates selective cellular cholesterol uptake from high‐density lipoproteins (HDLs), plays a key role in reverse cholesterol transport. The orphan nuclear receptor liver receptor homolog 1 (LRH‐1) and SR‐BI are co‐expressed in liver and ovary, suggesting that LRH‐1 might control the expression of SR‐BI in these tissues. LRH‐1 induces human and mouse SR‐BI promoter activity by binding to an LRH‐1 response element in the promoter. Retroviral expression of LRH‐1 robustly induces SR‐BI, an effect associated with histone H3 acetylation on the SR‐BI promoter. The decrease in SR‐BI mRNA levels in livers of LRH‐1+/− animals provides in vivo evidence that LRH‐1 regulates SR‐BI expression. Our data demonstrate that SR‐BI is an LRH‐1 target gene and underscore the pivotal role of LRH‐1 in reverse cholesterol transport.
Formation of extrachromosomal circles from telomeric DNA in Xenopus laevis
Authors: Cohen Sarit , Méchali Marcel
Published: December 2002

Instability and plasticity of telomeric DNA, which includes extrachromosomal DNA, are usually correlated with the absence of telomerase and with abnormal growth of mammalian cells. Here, we show the formation of extrachromosomal circular DNA of telomeric repeats (tel‐eccDNA) during the development of Xenopus laevis. Tel‐eccDNA is double‐stranded relaxed circles composed of the vertebrate consensus telomeric repeats (TTAGGG)n. Its size varies from <2 to >20 kb and it comprises up to 10% of the total cellular telomere content of the early embryo (pre‐MBT stage). The amount of tel‐eccDNA is reduced in later developmental stages and in adult tissues. Using a cell‐free system derived from Xenopus egg extracts, we show that tel‐eccDNA can be formed de novo from the telomere chromosomal tracts of sperm nuclei and naked DNA in a replication‐independent manner. These results reveal an unusual plasticity of telomeric DNA during normal development of Xenopus.
The D‐Box‐activating domain (DAD) is a new proteolysis signal that stimulates the silent D‐Box sequence of Aurora‐A
Authors: Castro Anna , Vigneron Suzanne , Bernis Cyril , Labbé Jean‐Claude , Prigent Claude , Lorca Thierry
Published: December 2002

We have demonstrated previously that Xenopus Aurora‐A is degraded at late mitosis by the APC/Fizzy‐Related in a D‐Box‐dependent manner. Here we demonstrate that, although Aurora‐B possesses the same D‐Box as Aurora‐A, Aurora‐B is not degraded by this ubiquitin ligase. We have constructed a chimera Aurora‐A/B with the N‐terminus of Aurora‐A and the C‐terminus of Aurora‐B and we have examined its degradation by APC/Fizzy‐Related. We demonstrate that the N‐terminus of Aurora‐A confers degradation capacity on the C‐terminus of Aurora‐B and that this feature is blocked by mutation of the conserved D‐Box sequence. We characterize the minimal degradation signal at the N‐terminus of Aurora‐A and demonstrate that its deletion blocks the degradation of this protein by APC/Fizzy‐Related. Thus, we conclude that two different degradation signals are required for proteolysis of Aurora‐A. The first one, which we designated D‐Box‐activating domain, within the N‐terminal domain of Aurora‐A confers the functionality to the second, a silent D‐Box, present within the C‐terminus of the kinase.
Genomic expansion and clustering of ZAD‐containing C2H2 zinc‐finger genes in Drosophila
Authors: Chung Ho‐Ryun , Schäfer Ulrich , Jäckle Herbert , Böhm Siegfried
Published: December 2002

C2H2 zinc‐finger proteins (ZFPs) constitute the largest family of nucleic acid binding factors in higher eukaryotes. In silico analysis identified a total of 326 putative ZFP genes in the Drosophila genome, corresponding to ∼2.3% of the annotated genes. Approximately 29% of the Drosophila ZFPs are evolutionary conserved in humans and/or Caenorhabditis elegans. In addition, ∼28% of the ZFPs contain an N‐terminal zinc‐finger‐associated C4DM domain (ZAD) consisting of ∼75 amino acid residues. The ZAD is restricted to ZFPs of dipteran and closely related insects. The evolutionary restriction, an expansion of ZAD‐containing ZFP genes in the Drosophila genome and their clustering at few chromosomal sites are features reminiscent of vertebrate KRAB‐ZFPs. ZADs are likely to represent protein–protein interaction domains. We propose that ZAD‐containing ZFP genes participate in transcriptional regulation either directly or through site‐specific modification and/or regulation of chromatin.
Neuroglobin and cytoglobin
Authors: Pesce Alessandra , Bolognesi Martino , Bocedi Alessio , Ascenzi Paolo , Dewilde Sylvia , Moens Luc , Hankeln Thomas , Burmester Thorsten
Published: December 2002

Neuroglobin and cytoglobin are two recently discovered members of the vertebrate globin family. Both are intracellular proteins endowed with hexacoordinated heme‐Fe atoms, in their ferrous and ferric forms, and display O2 affinities comparable with that of myoglobin. Neuroglobin, which is predominantly expressed in nerve cells, is thought to protect neurons from hypoxic–ischemic injury. It is of ancient evolutionary origin, and is homologous to nerve globins of invertebrates. Cytoglobin is expressed in many different tissues, although at varying levels. It shares common ancestry with myoglobin, and can be traced to early vertebrate evolution. The physiological roles of neuroglobin and cytoglobin are not completely understood. Although supplying cells with O2 is the likely function, it is also possible that both globins act as O2‐consuming enzymes or as O2 sensors. Here, we review what is currently known about neuroglobin and cytoglobin in terms of their function, tissue distribution and relatedness to the well‐known hemoglobin and myoglobin. Strikingly, the data reveal that O2 metabolism in cells is more complicated than was thought before, requiring unexpected O2‐binding proteins with potentially novel functional features.
Synthesis and characterization of the binuclear diamido titanium chalcogenides [(Ar)NCH2CH2CH2N(Ar)]2Ti(µ-E)2 (E = Se, Te)
Authors: Zhang Tianle , Piers Warren E , Parvez Masood
Published: December 2002

Reaction of McConville's chelating amido titanium complex [(Ar)NCH2CH2CH2N(Ar)]Ti(CH3)2 (Ar = 2,6-i-Pr2C6H3) with either elemental Se or the tellurium atom source Te=PBu3 resulted in the formation of bis-µ-chalcogenido dimers [(Ar)NCH2CH2CH2N(Ar)]2Ti(µ-E)2 (E = Se, 2; Te, 3) with concommitant loss of EMe2. The dimers 2 and 3 were characterized spectroscopically and via X-ray crystallography. The two compounds are isostructural in the solid state. The tellurido dimer 3 may also be synthesized by reduction of the diamido dichloride [(Ar)NCH2CH2CH2N(Ar)]2TiCl2 with NaHg amalgam followed by treatment with Te=PBu3. This dimer is unreactive toward further Te=PBu3 or stannanes such as HSnBu3. Unlike decamethyltitanocene derivatives, the diamido complex is not an effective catalyst precursor for the heterohydrodecoupling of Te=PBu3 and HSnBu3.Key words: diamido titanium complexes, selenides, tellurides.
Synthesis and characterization of a spirocyclic phosphaverdazyl radical - cyclophosphazene hybrid: Evidence for spin transfer from a verdazyl radical to a phosphazene ring
Authors: Barclay Tosha M , Hicks Robin G , Ichimura Andrew S , Patenaude Greg W
Published: December 2002

The synthesis and characterization of a new 6-phosphaverdazyl radical incorporated into a spirocyclic framework containing a cyclotriphosphazene ring is described. Reaction of 1,1,3,3-bis[spiro-2',2''-dioxy-1',1''-biphenyl]-5,5-bis(1-methylhydrazido)-1,3,5,2,4,6-cyclotriphosphazene (7) with trimethylorthobenzoate yielded 6-[2,2,4,4-bis(2,2'-dioxy-1,1'-biphenyl)-2,4,6,1,3,5-cyclotriphosphazen-6-yl]-1,2,5,6-tetrahydro-1,5-dimethyl-3-phenyl-1,2,4,5,6-tetrazaphosphorine (8), which was characterized spectroscopically and by X-ray diffraction. Oxidation of 8 yielded 6-[2,2,4,4-bis(2,2'-dioxy-1,1'-biphenyl)-2,4,6,1,3,5-cyclotriphosphazen-6-yl]-1,5-dimethyl-3-phenyl-6-phosphaverdazyl (5), which was characterized by EPR and ENDOR spectroscopy. Analysis of both spectra indicate that spin density from the phosphaverdazyl ring induces spin polarization into the phosphazene ring, as evidenced by hyperfine coupling to all three phosphorus nuclei.Key words: heterocycle, phosphorusnitrogen compounds, phosphazenes, stable radicals, verdazyls.
The synthesis and reactivity of a mixed nitrosylphosphinidene cluster of ruthenium: Formation of nitride and nitrene clusters
Authors: Scoles Ludmila , Sterenberg Brian T , Udachin Konstantin A , Carty Arthur J
Published: December 2002

Reaction of the aminophosphinidene complex [Ru5(CO)15(µ4-PN-i-Pr2)] (1) with [PPN][NO2] (PPN = Ph3P=N=PPh3) led to the mixed nitrosyl  phosphinidene cluster complex [PPN][Ru5(CO)13(µ2-NO)(µ4-PN-i-Pr2)] (2). Reaction of 2 with HBF4·Et2O led to a mixture of the nitridophosphido cluster [Ru5(CO)13(µ5-N){µ2-P(F)N-i-Pr2}] (3) and the nitrenephosphinidene cluster [Ru5(CO)10(µ-CO)2(µ3-CO)(µ4-NH)(µ3-PN-i-Pr2)] (4). If the BF4 counterion is avoided through use of trifluoromethanesulfonic acid, 4 is the only isolated product. Reaction of 2 with methyltrifluoromethanesulfonate leads to the nitridophosphido cluster [Ru5(CO)13(µ5-N){µ2-P(OMe)N-i-Pr2}] (5), which is structurally analogous to 3.Key words: ruthenium, cluster, nitrosyl, nitrene, phosphinidene, phosphido.
Syntheses and structures of bis(imido)organophosphine dianions
Authors: Jack Kevin S , Jeffery John C , Leedham Angela P , Lynam Jason M , Niedzwiecki Michael , Russell Christopher A
Published: December 2002

A bis(imido)phosphine dianion, [R'P(NR)2]2 (R' = n-Bu, R = N-N=CPh2) is produced from the reaction of PCl3 with benzophenone hydrazone (1:3 equiv) in THFNEt3, followed by metallation of the reaction mixture with 3 equiv n-BuLi. A more straightforward synthesis of a comparable dianion (with R' = Ph, R = N-N=CPh2) is the reaction of PhPCl2 with benzophenone hydrazone (1:2 equiv) in THFNEt3, followed by metallation of the reaction mixture with 2 equiv n-BuLi.Key words: phosphorus, lithium, imido, complexes, X-ray.
2,6-Diisopropylphenylphosphane: A new, bulky primary phosphane and its mono- and disilylated Si(CH3)3and Si(CH3)2-t-Bu derivatives  A synthetic, crystallographic, and dynamic NMR investigation
Authors: Boeré René T , Masuda Jason D
Published: December 2002

The bulky primary phosphane 2,6-diisopropylphenylphosphane, DipPH2, has been prepared from 1-bromo-2,6-diisopropylbenzene via the reaction of the Grignard reagent with PCl3. The resulting mixed phosphonous dihalides DipP(Cl,Br)2are reduced with LiAlH4to yield the title compound in reasonable yield and on a synthetically useful scale. DipPH2is also used to prepare the monosilylated derivatives DipPHSi(CH3)3and DipPH{Si(CH3)2-t-Bu} as well as the disilylated compounds DipP{Si(CH3)3}2and DipP{Si(CH3)2-t-Bu}2. All products have been fully characterized by IR, mass, and NMR spectroscopy. The crystal structure of DipPH{Si(CH3)2-t-Bu} was determined from single-crystal diffraction data: C18H33PSi, P21/c, Z = 4, a = 8.5768(10), b = 28.104(3), c = 8.1102(4) Å, β = 93.341(3)° (R = 0.0518). Changes in the NMR spectrum of DipPH{Si(CH3)2-t-Bu} were observed over the temperature range 178380 K. Barrier heights were determined from the peak separation at low temperature and the coalescence points: ΔG[Formula: see text] 40 kJ mol1for C(aryl)P bond rotation and [Formula: see text] 72 kJ mol1for pyramidal inversion at phosphorus.Key words: crystal structure, 2,6-diisopropylphenyl, bulky substituents, steric congestion, dynamic NMR, primary phosphane, silyl phosphane.
A theoretical study of the77Se NMR and vibrational spectroscopic properties of SenS8nring molecules
Authors: Komulainen J , Laitinen R S , Suontamo R J
Published: December 2002

The structures and spectroscopic properties of SenS8nring molecules have been studied by the use of ab initio molecular orbital techniques and density functional techniques involving Stuttgart relativistic large core effective core potential approximation with double zeta basis sets for valence orbitals augmented by two polarization functions for both sulfur and selenium. Full geometry optimizations have been carried out for all 30 isomers at the Hartree-Fock level of theory. The optimized geometries and the calculated fundamental vibrations and Raman intensities of the SenS8nmolecules agree closely with experimental information where available. The nuclear magnetic shielding tensor calculations have been carried out by the Gauge-independent atomic orbital method at the DFT level using Becke's three-parameter hybrid functional with Perdew/Wang 91 correlation. The isotropic shielding tensors correlate well with the observed chemical shift data. The calculated chemical shifts provide a definite assignment of the observed77Se NMR spectroscopic data and can be used in the prediction of the chemical shifts of unknown SenS8nring molecules.Key words: selenium sulfides, ab initio, DFT, effective core potentials, geometry optimization, energetics, fundamental vibrations,77Se chemical shifts.
Synthesis and characterization of titanium complexes containing phosphinimido and tropidinyl ligands: Crystal structure of (trop)(t-Bu3PN)TiCl2
Authors: Brown Steve J , Gao Xiaoliang , Kowalchuk Matthew G , Spence Rupert E.v.H. , Stephan Douglas W , Swabey John
Published: December 2002

A new class of titanium complexes containing a tropidinyl (trop) ligand and a phosphinimido (R3P=N-) or a ketimide ligand (R2C=N-) were synthesized and characterized. The combination of the cyclopentadienyl equivalent tropidinyl and phosphinimido ligands enables the formation of a group of novel non-metallocene catalysts for olefin polymerization. The crystal structure of (trop)(t-Bu3PN)TiCl2 was determined by single crystal X-ray crystallography. Polymerization of ethylene with this complex was studied in a high-temperature solution process.Key words: tropidinyl, phosphinimido, ketimide, catalyst, polymerization.
The promise of sociocultural theory in democratizing adult education
Authors: Alfred Mary V.
Published: December 2002

The most dominant perspectives used to understand adult learning and guide the practice of adult education continue to be those that focus on learning as an individual endeavor with little regard for the sociocultural environment. Sociocultural theory therefore holds promise for incorporating multiple worldviews into the study and practice of adult education.
Cross‐cultural mentoring as a context for learning
Authors: Johnson‐Bailey Juanita , Cervero Ronald M.
Published: December 2002

Cross‐cultural mentoring relationships are an important site of struggle for learning and for power. We use the example of one mentoring relationship to illustrate six common issues facing people involved in these relationships.
Socialization and immigrant students' learning in adult education programs
Authors: Lee Ming‐Yeh , Sheared Vanessa
Published: December 2002

In the field of adult education, the context of immigration as it influences the learning experiences of foreign‐born learners has received scant attention. This chapter examines the influence of early formal and informal socialization on the learning behavior of immigrants and second language learners in U.S. adult education.
Adult literacy as cultural practice
Authors: Sparks Barbara
Published: December 2002

This chapter proposes a rationale for shifting the predominant adult literacy education model of decontextualized and monologic programs to a sociocultural approach. Such an approach takes into account the functions of literacy as a cultural practice within social relations in a particular social context.
Linking the personal and the social for a more critical democratic adult education
Authors: Alfred Mary V.
Published: December 2002

The literature of adult education highlights the need for educators to foster an inclusive learning environment to accommodate the multiple worldviews that learners bring. Missing from the discussion is the interplay among critical reflection of self and practice, knowledge and understanding of the problematic issues, and critical action.
An adaptive cascade control for a class of chemical reactors
Authors: Alvarez‐Ramirez Jose , Alvarez Jesus , Morales America
Published: December 2002

This paper is addressed to the problem of designing an adaptive cascade controller to stabilize a jacketed continuous chemical reactor whose isothermal dynamics are globally stable. Assuming that the heat generation and transfer models are uncertain, the controller is built on the basis of back‐stepping procedure in conjunction with the mass and energy conservation principles that underlie the reactor behaviour. The corresponding closed‐loop dynamics are studied yielding a semiglobal stability criterion coupled with a systematic construction‐tuning procedure. The resulting cascade controller has aPI‐type structure with an antireset windup scheme, and is put in perspective with its industrial‐type counterpart. A simulated example is used to illustrate the functioning of the proposed controller. Copyright © 2002 John Wiley & Sons, Ltd.
Studies on the electrostatic self‐assembly of polyelectrolytes and organic dyes with atomic force microscopy
Authors: Zhong Anyong , Lin Xianjun , Chen Deben , Zhou Zonghua
Published: December 2002

An ultrathin film was formed by the electrostatic self‐assembly of polyelectrolyte poly‐N‐ethyl‐N,N‐dimethyaminoethyl methacrylate (PDMAEB) and the organic dye metanil yellow (MY) on a smooth glass sheet. An atomic force microscope was used to study the topography and the phase of the two samples and the ultrathin film (PDMAEB–MY). The dynamic course of the surface structure was researched by atomic force microscopy also. It is illustrated that the existence of electrostatic interactions between PDMAEB and MY made MY arrange in order on the polyelectrolyte surface. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1029–1033, 2003
Solution properties of gas‐phase‐polymerized sodium acrylate microparticles. I. Influence of coinitiators
Authors: Sanderson R. D. , Sadiku E. R.
Published: December 2002

A partially neutralized sodium acrylate (NaAc) monomer was polymerized in the gas phase in the presence of ammonium peroxydisulfate [(NH4)2S2O8] as the primary initiator and zinc acetate (ZnAc) as the coinitiator. The effect of the coinitiator on the solution properties of the spray‐polymerized product was investigated for the conversion percentage as a function of (1) the primary initiator (NH4)2S2O8 concentration, with the concentration (14.8% with respect to the monomer) of the coinitiator kept constant; (2) the coinitiator (ZnAc) concentration, with the primary initiator concentration (4% with respect to the monomer) kept constant; and (3) the reaction temperature. The viscosity of the product as a function of the coinitiator concentration was also investigated. The conversion percentage of gas‐phase‐polymerized NaAc increased by approximately 8% (i.e., from 91.6 to 99.3%) with an increasing (NH4)2S2O8 concentration (0.5–5% with respect to the monomer). The conversion percentage as a function of the coinitiator concentration (0–15% with respect to the monomer) increased by 25% (from 75 to 100%). When the concentrations of the initiators (NH4)2S2O8 and ZnAc were kept constant at 4 and 14.8% (with respect to the monomer), respectively, the conversion increased from 48 to 83% when the reaction temperature was increased from 100 to 140°C. The viscosity (at 20°C) of sodium polyacrylate decreased with an increasing coinitiator concentration. The relative rate of polymerization, as a function of the pH of the polymer, showed a minimum at pH ≈ 6 and subsequently increased steeply, reaching a plateau at pH ≈ 11; it then decreased again very sharply. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1034–1043, 2003
Synthesis and morphology of platinum‐coated hollow‐fiber carbon membranes
Authors: Sanderson R. D. , Sadiku E. R.
Published: December 2002

Hollow‐fiber carbon membranes were prepared and used as support media for a platinum catalyst. The platinum metal was deposited onto the surface of the hollow‐fiber carbon membranes by three different techniques: solution coating with chloroplatinic acid, which is the commonly used technique; vapor deposition, involving the sublimation of the platinum metal; and magnetron sputter coating, the most effective method. The hollow‐fiber carbon membranes coated with a chloroplatinic acid solution were studied with scanning electron microscopy (SEM) and energy‐dispersive X‐ray analysis (EDAX). The platinum coating grew on the surface, unevenly, in the form of small crystals. The percentage of platinum on the surface was too low to be detected by EDAX. The high‐vacuum evaporation coating of the membranes with platinum was also studied with both SEM and EDAX. Again, because of the low percentage of platinum, EDAX did not reveal any platinum on the surfaces of the membranes. The magnetron sputter coating of platinum onto the membranes was performed and studied with SEM. The thickness of the coated platinum could be varied through variations in the coating time. The cavities observed in the micrographs were formed during the coating operations by the presence of dust particles on the membranes. An SEM micrograph of a hollow‐fiber carbon membrane, produced from a polyacrylonitrile‐based precursor, spun with a low amount of dimethyl sulfoxide in the bore fluid, and coated with platinum, showed a skin on the outside and a porous elongated structure inside the skin. The distance between the inner and outer skins contained fingerlike pores of various sizes. The largest pores were found near the inside skin, whereas the smallest pores were next to the outside skin. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1051–1058, 2003
Gas permeability of NH3‐plasma‐treated poly(methyl methacrylate) membranes
Authors: Yamamoto Y. , Maegawa M. , Kumazawa H.
Published: December 2002

The effect of NH3 plasma treatment on glassy poly(methyl methacrylate) (PMMA) membranes on the diffusion process for penetrant gases (CO2, O2, and N2) was investigated from mean permeability data. The mean permeability coefficient for CO2 definitely depended on the upstream pressure, whereas those for O2 and N2 remained constant regardless of the upstream pressure. For O2 transport, the permeability increased a little with increasing treatment power, and for N2 transport, it was not affected by the treatment power. For CO2 transport, NH3 plasma treatment promoted the transport of Langmuir mode, presumably through an increased Langmuir capacity constant for CO2. NH3 plasma treatment for PMMA membranes resulted in an increase in the separation factor of CO2 relative to N2 and in the permeability to CO2. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1068–1072, 2003
Curing and mechanical properties of dicyanate/poly(ether sulfone) semi‐interpenetrating polymer networks
Authors: Roh Seung‐Sang , Hong Bong‐Taek , Kim Dae Su
Published: December 2002

Semi‐interpenetrating polymer networks (semi‐IPNs) composed of a dicyanate resin and a poly(ether sulfone) (PES) were prepared, and their curing behavior and mechanical properties were investigated. The curing behavior of the dicyanate/PES semi‐IPN systems catalyzed by an organic metal salt was analyzed. Differential scanning calorimetry was used to study the curing behavior of the semi‐IPN systems. The curing rate of the semi‐IPN systems decreased as the PES content increased. An autocatalytic reaction mechanism was used to analyze the curing reaction of the semi‐IPN systems. The glass‐transition temperature of the semi‐IPNs decreased with increasing PES content. The thermal decomposition behavior of the semi‐IPNs was investigated. The morphology of the semi‐IPNs was investigated with scanning electron microscopy. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1079–1084, 2003
Water and oil repellency of polysiloxanes with highly fluorinated alkyl side chains
Authors: Furukawa Yutaka , Kotera Mami
Published: December 2002

A series of fluorinated polysiloxanes (FLSs) with the 3,3,4,4,5,5,6,6,6‐nonafluorohexyl group (C4F9C2H4), 4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11‐heptadecafluoroundecyl group (C8F17C3H6), 3‐(2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9‐heptadecafluorononanamido) propyl group [HDFNAG; C8F17(CO)NHC3H6], and 3‐(N‐methyl‐2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9‐heptadecafluorononanamido) propyl group [C8F17(CO)N(CH3)C3H6] were synthesized. Their homopolymers (homo‐FLSs) and copolymers with dimethylsiloxane (co‐FLSs) were included. The polyester fabrics were treated with these FLSs, and their water and oil repellency was evaluated. These fabrics showed a moderate to good level of water repellency but a poor to zero level of oil repellency, except for those fabrics treated with homo‐FLSs with HDFNAG. The characterization of the surface chemical composition by X‐ray photoelectron spectroscopy showed that the concentration of fluorine at the surface was not particularly high for poly(ethylene terephthalate) films treated with homo‐FLSs with HDFNAG. Differential scanning calorimetry measurements of these FLSs revealed that only homo‐FLSs with HDFNAG had a high melting temperature of 75.7°C. These two measurements suggested that the reason the fabrics treated with homo‐FLSs with HDFNAG showed good oil repellency was not because the concentration of fluorine at the surface was much higher than for the others but because the reorientation of HDFNAG did not take place for its packing after contact with oil. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1085–1091, 2003
Copolymerization of CO2 and cyclohexene oxide using a novel polymeric diimide catalyst
Authors: Zhang Min , Chen Liban , Qin Gang , Liu Baohua , Yan Zhairong , Li Zhuomei
Published: December 2002

A catalyst for the copolymerization of CO2 and cyclohexene oxide was prepared by using acetylacetone and 4,4′‐methylenedianiline. The catalyst was characterized as composed of a novel structure of the polymeric diimide Zn complex. The catalyst tended to produce an alternative copolymer with efficiency as high as 128 g polymer/g of catalyst. The obtained copolymers were characterized by IR and NMR. Effects of reaction conditions such as reaction time and temperature, CO2 pressure, and catalyst concentration on copolymerization were investigated. Best results were obtained from the reaction at 90°C for 24 h, with catalyst concentration of 0.13 g/mL, and CO2 pressure of 2–3 MPa. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1123–1128, 2003
Beyond logs and surveys: In‐depth measures of people's web use skills
Authors: Hargittai Eszter
Published: December 2002

Finding information on the Web can be a much more complex search process than previously experienced on many pre‐Web information retrieval systems given that finding content online does not have to happen via a search algorithm typed into a search field. Rather, the Web allows for a myriad of search strategies. Although there are numerous studies of Web search techniques, these studies often limit their focus to just one part of the search process and are not based on the behavior of the general user population, nor do they include information about the users. To remedy these shortcomings, this project looks at how people find information online in the context of their other media use, their general Internet use patterns, in addition to using information about their demographic background and social support networks. This article describes the methodology in detail, and suggests that a mix of survey instruments and in‐person observations can yield the type of rich data set that is necessary to understand in depth the differences in people's information retrieval behavior online.
Scenarios in the Afya project as a participatory action research (PAR) tool for studying information seeking and use across the “digital divide”
Authors: Mehra Bharat , Peterson Bishop Ann , Bazzell Imani , Smith Cynthia
Published: December 2002

This article explores the role of scenarios (or use‐oriented design representations) in the Afya project as a participatory action research (PAR) tool for studying information seeking and use across the “digital divide.” With the aim of improving access to health information and services for Black women, the Afya project has involved forging community‐level partnerships with SisterNet, a local grassroots group of Black women devoted to improving their physical, emotional, intellectual, and spiritual health. In the context of community health care, scenarios in the Afya project as a socially grounded planning and design methodology have taken the form of personal narratives of Black women that capture their social experiences and typical problematic health situations. Scenarios of Black women point towards the need to foster social justice by nurturing equitable and participative social activities around technological development and use associated with health information services. Scenarios also suggest specific action‐oriented strategies for empowering Black women to build social and digital technologies that we hope will make the provision of health care in our community more just.
Analysis of Scifinder Scholar and Web of Science citation searches
Authors: Whitley Katherine M.
Published: December 2002

Chemical Abstracts Service recently unveiled citation searching in Chemical Abstracts. With Chemical Abstracts and Science Citation Index both now available for citation searching, this study compares the duplication and uniqueness of citing references for works of chemistry researchers for the years 1999–2001. The two indexes cover very similar source material, so one would expect the citation results to be very similar. This analysis of SciFinder Scholar and Web of Science shows some important differences as the databases are currently offered. Authors and institutions using citation counts as measures of scientific productivity should take note.
Simple NMR‐mouse with a bar magnet
Authors: Blümich B. , Anferov V. , Anferova S. , Klein M. , Fechete R. , Adams M. , Casanova F.
Published: December 2002

A new concept of the NMR Mobile Universal Surface Explorer (NMR‐MOUSE) using simple bar magnets instead of u‐shaped magnets is described. The magnetic field profiles are comparatively homogeneous in extended lateral planes, and close to the magnet pole face the axial gradient is nearly constant. Different geometric arrangements of figure‐8 coils adapted to the sample geometry are described. Simulations and measurements of the magnetic field from the magnets and the radio frequency coils are discussed. © 2002 Wiley Periodicals, Inc. Concepts in Magnetic Resonance (Magn Reson Engineering) 15: 255–261, 2002
Conserving Galerkin weak formulations for computational fracture mechanics
Authors: Li Shaofan , Simkins Daniel C.
Published: December 2002

In this paper, a notion of invariant Galerkin‐variational weak forms is proposed. Two specific invariant variational weak forms, the J‐invariant and the L‐invariant, are constructed based on the corresponding conservation laws in elasticity, one of which is the conservation of Eshelby's energy‐momentum (Eshelby. Philos. Trans. Roy. Soc. 1951; 87: 12; In Solid State Physics, Setitz F, Turnbull D (eds). Academic Press: New York, 1956; 331; Rice, J. Appl. Mech. 1968; 35: 379).

It is shown that the finite element solution obtained from the invariant Galerkin weak formulations proposed here can conserve the value of J‐integral, or L‐integral exactly. In other words, the J and L integrals of the Galerkin finite element solutions are path independent in the discrete sense. It is argued that by using the J‐invariant Galerkin weak form to compute near crack‐tip field in an elastic solid, one may accurately calculate the crack extension energy release rate and subsequently the stress intensity factors in numerical computations, because the flux of the energy‐momentum is conserved in discrete computations. This may provide an alternative means to accurately simulate crack growth and propagation. Copyright © 2002 John Wiley & Sons, Ltd.
Optimal vibration control of continuous structures by FEM: Part II—the computer implementation
Authors: Grewal I. S. , Szyszkowski W.
Published: December 2002

Dynamic problems of active optimal vibration control of elastic structures are solved by applying ‘static’ beam elements from standard structural FEM software. The approach uses an analogy between the optimality equations for the vibration control problem and the equations for the static bending of certain beams. The computer implementation of the analogy, which was presented in Part I of the paper, is discussed here in detail. Copyright © 2002 John Wiley & Sons, Ltd.
Sexual interactions of maturing male guinea pigs with their mothers, sisters, and unfamiliar adult females in the home cage
Authors: Hennessy Michael B. , Reed Jennifer , Wilson Shannon E. , Pitstick Lisa
Published: December 2002

During observations in the home cage in the light and dark on days 5, 15, 25, 35, and 45, male guinea pigs mounted and exhibited anogenital investigation of the mother, though appropriately directed mounting occurred infrequently and was not shown by all males. Mothers nipped and kicked advancing males. No mounting of a female sibling was observed. When behavioral interactions of ∼35‐day‐old males with the mother or an unfamiliar adult female were compared during 1‐hr tests in the home cage, males exhibited much higher levels of mounting and anogenital investigation, and received many more nips and kicks, when with the unfamiliar female. The results 1) demonstrate that limited maternally directed sexual behavior occurs in the home cage, 2) support earlier findings indicating that continuous housing with the mother suppresses maternally directed sexual behavior in periadolescent guinea pig males, and 3) suggest that sexual behavior toward female siblings also is suppressed. © 2003 Wiley Periodicals, Inc. Dev Psychobiol 42: 91–96, 2003.
Human chromosome 5 carries a putative telomerase repressor gene
Authors: Kugoh Hiroyuki , Shigenami Katsuyo , Funaki Kenji , Barrett J. Carl , Oshimura Mitsuo
Published: December 2002

Telomerase, the ribonucleoprotein enzyme that maintains the telomere, is active in human germ and stem cells and in a majority of tumor tissues and immortalized cell lines. In contrast, telomerase activity is not detected in most somatic cells, suggesting that normal human cells contain a regulatory factor(s) to repress this activity. To identify which human chromosomes carry a gene or genes that function as telomerase repressors, we investigated telomerase activity in hybrids of the B16‐F10 cell line, which contain individual human chromosomes transferred previously by microcell fusion and therefore represent a hybrid panel for the entire genome except for the Y chromosome. Microcell hybrids with an introduced normal human chromosome 5 showed inhibition of telomerase activity, but clones at a late passage exhibited reactivation of telomerase activity. Reactivation of telomerase activity was accompanied by deletion and/or rearrangement of the transferred human chromosome 5. The introduction of other human chromosomes did not significantly affect the telomerase activity of B16‐F10 cells. The effect of suppression of telomerase activity in microcell hybrids containing chromosome 5 was accompanied by a reduction in the level of mTERT mRNA, which encodes a component of the telomerase complex. The putative telomerase repressor gene was mapped to human chromosome bands 5p11–p13 by a combination of functional analysis using transfer of subchromosomal transferable fragments of chromosome 5 into B16‐F10 cells and deletion mapping of revertant clones with reactivated telomerase activity. Thus, these results suggest that loss of a gene(s) on this chromosome was responsible for telomerase reactivation, indicating that human chromosome 5 contains a gene or genes that can regulate the expression of mTERT in B16‐F10 cells. © 2002 Wiley‐Liss, Inc.
Genomic characterization of MOZ/CBP and CBP/MOZ chimeras in acute myeloid leukemia suggests the involvement of a damage‐repair mechanism in the origin of the t(8;16)(p11;p13)
Authors: Panagopoulos Ioannis , Isaksson Margareth , Lindvall Charlotta , Hagemeijer Anna , Mitelman Felix , Johansson Bertil
Published: December 2002

The t(8;16)(p11;p13), which is strongly associated with acute myeloid leukemia (AML) displaying monocytic differentiation, erythrophagocytosis by the leukemic cells, and a poor response to chemotherapy, fuses the MOZ gene (8p11) with the CBP gene (16p13). Although genomic rearrangements of MOZ and CBP have been detected using fluorescence in situ hybridization and Southern blot analyses, characterization of the breakpoints at the sequence level has never been performed. We have sequenced the breakpoints in four t(8;16)‐positive AML cases with the aim to identify molecular genetic mechanisms underlying the origin of this translocation. In addition, an exon/intron map of the MOZ gene was constructed, which was found to be composed of 17 exons. Long‐range‐PCR with CBP forward primers in exon 2 and MOZ reverse primers in exon 17 as well as with a MOZ forward primer in exon 16 and a CBP reverse primer in intron 2 successfully amplified CBP/MOZ and MOZ/CBP hybrid genomic DNA fragments in all four AMLs. The breaks clustered in both CBP intron 2 and MOZ intron 16, and were close to repetitive elements, and in one case an Alu‐Alu junction for the CBP/MOZ hybrid was identified. Additional genomic events (i.e., deletions, duplications, and insertions) in the breakpoint regions in both the MOZ and CBP genes were found in all four cases. Thus, the t(8;16) does not originate through a simple end‐to‐end fusion. The findings of multiple breaks and rearrangements rather suggest the involvement of a damage‐repair mechanism in the origin of this translocation. © 2002 Wiley‐Liss, Inc.
Delineation of the minimal region of loss at 13q14 in multiple myeloma
Authors: Elnenaei Manal O. , Hamoudi Rifat A. , Swansbury John , Gruszka‐Westwood Alicja M. , Brito‐Babapulle Vasantha , Matutes Estella , Catovsky Daniel
Published: December 2002

Previous studies have focused on the incidence and prognostic implications of 13q14 deletions in multiple myeloma (MM), but none has sought to delineate the minimal common deleted region (CDR). In an effort to do so, dual‐color interphase fluorescence in situ hybridization (FISH) was applied on 82 myeloma cases, initially by use of three probes for 13q14 (RB1, D13S319, and D13S25). Deletions were detected in 29/82 (35.4%) cases, and all except one were monoallelic. Subsequently, contiguous YACs, PACs, and a BAC spanning the 13q14–q21 region were employed for deletion mapping in addition to a 13q telomere probe. Large deletions extending to the 13q34 region were found in 55% of the deleted cases, whereas an additional 13.8% showed loss of both 13q34 and 13q14 regions with retention of 13q21. A CDR of approximately 350 kb was identified at 13q14 with the proximal border approximately 120 kb centromeric from D13S319, encompassing an area rich in expressed sequence tagged sites and containing DLEU1, DLEU2, and RFP2 genes. Direct sequencing of the RFP2 gene revealed no mutations in six patients and four MM cell lines harboring deletions of the CDR. However, a role for RFP2 in the pathogenesis of MM cannot yet be excluded, given that alternative mechanisms such as haploinsufficiency remain possible. © 2002 Wiley‐Liss, Inc.