bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolutionary analysis ofArabidopsis, cyanobacterial, and chloroplast genomes reveals plastid phylogeny and thousands of cyanobacterial genes in the nucleus
Authors: Martin William , Rujan Tamas , Richly Erik , Hansen Andrea , Cornelsen Sabine , Lins Thomas , Leister Dario , Stoebe Bettina , Hasegawa Masami , Penny David
Published: September 2002

Chloroplasts were once free-living cyanobacteria that became endosymbionts, but the genomes of contemporary plastids encode only ≈5–10% as many genes as those of their free-living cousins, indicating that many genes were either lost from plastids or transferred to the nucleus during the course of plant evolution. Previous estimates have suggested that between 800 and perhaps as many as 2,000 genes in theArabidopsisgenome might come from cyanobacteria, but genome-wide phylogenetic surveys that could provide direct estimates of this number are lacking. We compared 24,990 proteins encoded in theArabidopsisgenome to the proteins from three cyanobacterial genomes, 16 other prokaryotic reference genomes, and yeast. Of 9,368Arabidopsisproteins sufficiently conserved for primary sequence comparison, 866 detected homologues only among cyanobacteria and 834 other branched with cyanobacterial homologues in phylogenetic trees. Extrapolating from these conserved proteins to the whole genome, the data suggest that ≈4,500 ofArabidopsisprotein-coding genes (≈18% of the total) were acquired from the cyanobacterial ancestor of plastids. These proteins encompass all functional classes, and the majority of them are targeted to cell compartments other than the chloroplast. Analysis of 15 sequenced chloroplast genomes revealed 117 nuclear-encoded proteins that are also still present in at least one chloroplast genome. A phylogeny of chloroplast genomes inferred from 41 proteins and 8,303 amino acids sites indicates that at least two independent secondary endosymbiotic events have occurred involving red algae and that amino acid composition bias in chloroplast proteins strongly affects plastid genome phylogeny.
RecX protein abrogates ATP hydrolysis and strand exchange promoted by RecA: Insights into negative regulation of homologous recombination
Authors: Venkatesh R. , Ganesh N. , Guhan N. , Reddy M. Sreedhar , Chandrasekhar T. , Muniyappa K.
Published: September 2002

In many eubacteria, coexpression of
recX
with
recA
is essential for attenuation of the deleterious effects of
recA
overexpression; however, the molecular mechanism has remained enigmatic. Here, we show that
Mycobacterium tuberculosis
RecX binds directly to
M. tuberculosis
RecA as well as
M. smegmatis
and
E. coli
RecA proteins
in vivo
and
in vitro
, but not single-stranded DNA binding protein. The direct association of RecX with RecA failed to regulate the specificity or extent of binding of RecA either to DNA or ATP, ligands that are central to activation of its functions. Significantly, RecX severely impeded ATP hydrolysis and the generation of heteroduplex DNA promoted by homologous, as well as heterologous, RecA proteins. These findings reveal a mode of negative regulation of RecA, and imply that RecX might act as an anti-recombinase to quell inappropriate recombinational repair during normal DNA metabolism.
Crystal structure of calcineurin–cyclophilin–cyclosporin shows common but distinct recognition of immunophilin–drug complexes
Authors: Huai Qing , Kim Hwa-Young , Liu Yudong , Zhao Yingdong , Mondragon Angelo , Liu Jun O. , Ke Hengming
Published: September 2002

Calcineurin, a Ca2+/calmodulin-dependent protein phosphatase, is the common target for two immunophilin–immunosuppressant complexes, cyclophilin A–cyclosporin A (CyPA-CsA) and FKBP–FK506. How the two structurally distinct immunophilin–drug complexes bind the same target has remained unknown. We report the crystal structure of calcineurin (CN) in complex with CyPA-CsA at 2.8-Å resolution. The CyPA-CsA complex binds to a composite surface formed by the catalytic and regulatory subunits of CN, where the complex of FK506 and its binding protein FKBP also binds. While the majority of the CN residues involved in the binding are common for both immunophilin-immunosuppressant complexes, a significant number of the residues are distinct. Unlike FKBP-FK506, CyPA-CsA interacts with Arg-122 at the active site of CN, implying direct involvement of CyPA-CsA in the regulation of CN catalysis. The simultaneous interaction of CyPA with both the composite surface and the active site of CN suggests that the composite surface may serve as a substrate recognition site responsible for the narrow substrate specificity of CN. The comparison of CyPA-CsA-CN with FKBP-FK506-CN significantly contributes to understanding the molecular basis of regulation of CN activity by the immunophilin–immunosuppressant.
Nitrogen monoxide-mediated control of ferritin synthesis: Implications for macrophage iron homeostasis
Authors: Kim Sangwon , Ponka Prem
Published: September 2002

Intracellular iron homeostasis is regulated posttranscriptionally by iron regulatory proteins 1 and 2 (IRP1 and IRP2). In the absence of iron in the labile pool, IRPs bind to specific nucleotide sequences called iron responsive elements (IREs), which are located in the 5′ untranslated region of ferritin mRNA and the 3′ untranslated region of transferrin receptor mRNA. IRP binding to the IREs suppresses ferritin translation and stabilizes transferrin receptor mRNA, whereas the opposite scenario develops in iron-replete cells. Binding of IRPs to the IREs is also affected by nitrogen monoxide (NO), but there are conflicting reports regarding the effect of NO on ferritin synthesis. In this study, we demonstrated that a short exposure of RAW 264.7 cells (a macrophage cell line) to the NO+donor, sodium nitroprusside (SNP), resulted in a dramatic increase in ferritin synthesis. The SNP-mediated increase of ferritin synthesis could be blocked by MG132, an inhibitor of proteasome-dependent protein degradation, which also prevented the degradation of IRP2 caused by SNP treatment. Moreover, treatment of RAW 264.7 cells with IFN-γ and lipopolysaccharide caused IRP2 degradation and stimulated ferritin synthesis, changes that could be prevented by specific inhibitors of inducible nitric oxide synthase. Furthermore, the SNP-mediated increase in ferritin synthesis was associated with a significant enhancement of iron incorporation into ferritin. These observations indicate that NO+-mediated modulation of IRP2 plays an important role in controlling ferritin synthesis and iron metabolism in murine macrophages.
Cloning the vaccinia virus genome as a bacterial artificial chromosome in
Escherichia coli
and recovery of infectious virus in mammalian cells
Authors: Domi Arban , Moss Bernard
Published: September 2002

The ability to manipulate the vaccinia virus (VAC) genome, as a plasmid in bacteria, would greatly facilitate genetic studies and provide a powerful alternative method of making recombinant viruses. VAC, like other poxviruses, has a linear, double-stranded DNA genome with covalently closed hairpin ends that are resolved from transient head-to-head and tail-to-tail concatemers during replication in the cytoplasm of infected cells. Our strategy to construct a nearly 200,000-bp VAC-bacterial artificial chromosome (BAC) was based on circularization of head-to-tail concatemers of VAC DNA. Cells were infected with a recombinant VAC containing inserted sequences for plasmid replication and maintenance in
Escherichia coli
; DNA concatemer resolution was inhibited leading to formation and accumulation of head-to-tail concatemers, in addition to the usual head-to-head and tail-to-tail forms; the concatemers were circularized by homologous or Cre–loxP-mediated recombination; and
E. coli
were transformed with DNA from the infected cell lysates. Stable plasmids containing the entire VAC genome, with an intact concatemer junction sequence, were identified. Rescue of infectious VAC was consistently achieved by transfecting the VAC–BAC plasmids into mammalian cells that were infected with a helper nonreplicating fowlpox virus.
A protease assay for two-photon crosscorrelation and FRET analysis based solely on fluorescent proteins
Authors: Kohl Tobias , Heinze Katrin G. , Kuhlemann Rene , Koltermann Andre , Schwille Petra
Published: September 2002

GFP and the red fluorescent protein, DsRed, have been combined to design a protease assay that allows not only for fluorescence resonance energy transfer (FRET) studies but also for dual-color crosscorrelation analysis, a single-molecule-based method that selectively probes the concomitant movement of two distinct tags. The measurement principle is based on a spectrally resolved detection of single molecules diffusing in and out of a diffraction-limited laser focus. Double-labeled substrate molecules are separated into two single-labeled products by specific cleavage at a protease cleavage site between the two flanking tags, DsRed and GFP, thus disrupting joint fluctuations in the two detection channels and terminating FRET between the two labels. In contrast to enzyme assays based solely on FRET, this method of dual-color crosscorrelation is not limited to a certain range of distances between the fluorophores and is much more versatile with respect to possible substrate design. To simplify the measurement setup, two-photon excitation was used, allowing for simultaneous excitation of both tags with a single infrared laser wavelength. The general concept was experimentally verified with a GFP–peptide–DsRed construct containing the cleavage site for tobacco etch virus protease. Two-photon excitation in the infrared and the use of cloneable tags make this assay easily adaptable to intracellular applications. Moreover, the combination of FRET and crosscorrelation analysis in a single-molecule-based approach promises exciting perspectives for miniaturized high-throughput screening based on fluorescence spectroscopy.
The two-component system BvrR/BvrS essential for
Brucella
abortus
virulence regulates the expression of outer membrane proteins with counterparts in members of the
Rhizobiaceae
Authors: Guzmán-Verri C. , Manterola L. , Sola-Landa A. , Parra A. , Cloeckaert A. , Garin J. , Gorvel J.-P. , Moriyón I. , Moreno E. , López-Goñi I.
Published: September 2002

The
Brucella
BvrR/BvrS two-component regulatory system is homologous to the ChvI/ChvG systems of
Sinorhizobium
meliloti
and
Agrobacterium
tumefaciens
necessary for endosymbiosis and pathogenicity in plants. BvrR/BvrS controls cell invasion and intracellular survival. Probing the surface of
bvrR
and
bvrS
transposon mutants with monoclonal antibodies showed all described major outer membrane proteins (Omps) but Omp25, a protein known to be involved in
Brucella
virulence. Absence of Omp25 expression was confirmed by two-dimensional electrophoresis of envelope fractions and by gene reporter studies. The electrophoretic analysis also revealed reduction or absence in the mutants of a second set of protein spots that by matrix-assisted laser desorption ionization MS and peptide mass mapping were identified as a non-previously described Omp (Omp3b). Because
bvrR
and
bvrS
mutants are also altered in cell-surface hydrophobicity, permeability, and sensitivity to surface-targeted bactericidal peptides, it is proposed that BvrR/BvrS controls cell envelope changes necessary to transit between extracellular and intracellular environments. A genomic search revealed that Omp25 (Omp3a) and Omp3b belong to a family of Omps of plant and animal cell-associated α-
Proteobacteria
, which includes
Rhizobium
leguminosarum
RopB and
A.
tumefaciens
AopB. Previous work has shown that RopB is not expressed in bacteroids, that AopB is involved in tumorigenesis, and that dysfunction of
A.
tumefaciens
ChvI/ChvG alters surface properties. It is thus proposed that the BvrR/BvrS and Omp3 homologues of the cell-associated α-
Proteobacteria
play a role in bacterial surface control and host cell interactions.
MYO18B
, a candidate tumor suppressor gene at chromosome 22q12.1, deleted, mutated, and methylated in human lung cancer
Authors: Nishioka Michiho , Kohno Takashi , Tani Masachika , Yanaihara Nozomu , Tomizawa Yoshio , Otsuka Ayaka , Sasaki Shigeru , Kobayashi Keiko , Niki Toshiro , Maeshima Arafumi , Sekido Yoshitaka , Minna John D. , Sone Saburo , Yokota Jun
Published: September 2002

Loss of heterozygosity on chromosome 22q has been detected in approximately 60% of advanced nonsmall cell lung carcinoma (NSCLC) as well as small cell lung carcinoma (SCLC), suggesting the presence of a tumor suppressor gene on 22q that is involved in lung cancer progression. Here, we isolated a myosin family gene,
MYO18B
, located at chromosome 22q12.1 and found that it is frequently deleted, mutated, and hypermethylated in lung cancers. Somatic
MYO18B
mutations were detected in 19% (14/75) of lung cancer cell lines and 13% (6/46) of primary lung cancers of both SCLC and NSCLC types.
MYO18B
expression was reduced in 88% (30/34) of NSCLC and 47% (8/17) of SCLC cell lines. Its expression was restored by treatment with 5-aza-2′-deoxycytidine in 11 of 14 cell lines with reduced
MYO18B
expression, and the promoter CpG island of the
MYO18B
gene was methylated in 17% (8/47) of lung cancer cell lines and 35% (14/40) of primary lung cancers. Furthermore, restoration of MYO18B expression in lung carcinoma cells suppressed anchorage-independent growth. These results indicate that the
MYO18B
gene is a strong candidate for a novel tumor suppressor gene whose inactivation is involved in lung cancer progression.
Cytoplasmic poly(A) polymerases mediate cellular responses to S phase arrest
Authors: Read Rebecca L. , Martinho Rui G. , Wang Shao-Win , Carr Antony M. , Norbury Chris J.
Published: September 2002

The S–M checkpoint delays mitosis until DNA replication is complete; cells defective in this checkpoint lose viability when DNA replication is inhibited. This inviability can be suppressed in fission yeast by overexpression of Cid1 or the related protein Cid13. Fission yeast contain six
cid1/cid13
-like genes, whereas budding yeast has just two,
TRF4
and
TRF5
. Trf4 and Trf5 were recently reported to comprise an essential DNA polymerase activity required for the establishment of sister chromatid cohesion. In contrast, we find that Cid1 is not a DNA polymerase but instead uses RNA substrates and has poly(A) polymerase activity. Unlike the previously characterized yeast poly(A) polymerase, which is a nuclear enzyme, Cid1 and Cid13 are constitutively cytoplasmic. Cid1 has a degree of substrate specificity
in vitro
, consistent with the notion that it targets a subset of cytoplasmic mRNAs for polyadenylation
in vivo
, hence increasing their stability and/or efficiency of translation. Preferred Cid1 targets presumably include mRNAs encoding components of the S–M checkpoint, whereas Cid13 targets are likely to be involved in dNTP metabolism. Cytoplasmic polyadenylation is known to be an important regulatory mechanism during early development in animals. Our findings in yeast suggest that this level of gene regulation is of more general significance in eukaryotic cells.
MULTIFRACTAL FRACTURE AND SIZE EFFECT
Authors: MOSOLOV ALEXEI
Published: September 2002

The fractal geometry is applied to describe the size effect in the fracture. We proposed a multifractal model for stress distribution in inhomogeneous solids and obtained the exponents in the scaling laws for the critical stress as well as for the apparent fracture energy. These exponents are connected with parameters of fractal geometry of damage.
DETECTION OF ABNORMAL CHANGE IN A TIME SERIES OF GRAPHS
Authors: SHOUBRIDGE PETER , KRAETZL MIRO , WALLIS WAL , BUNKE HORST
Published: September 2002

In the management of large enterprise communication networks, it becomes difficult to detect and identify causes of abnormal change in traffic distributions when the underlying logical topology is dynamic. This paper describes a novel approach to abnormal network change detection by representing periodic observations of logical communications within a network as a time series of graphs. A number of graph distance measures are proposed to assess the difference between successive graphs and identify abnormal behaviour. Localisation techniques have also been described to show where in the network most change occurred.
A SIX-STRUT MODEL FOR NONLINEAR DYNAMIC ANALYSIS OF STEEL INFILLED FRAMEs
Authors: CHRYSOSTOMOU C. Z. , GERGELY P. , ABEL J. F.
Published: September 2002

A two-dimensional computational model for infill walls is presented. The behavior of an infill wall is prescribed by a strength envelope and a hysteretic loop equation which provide smooth continuous curves. The infill is idealized with six compression-only inclined struts, which follow the behavior defined by the strength envelope and hysteretic loop equations. Three parallel struts are used in each direction, and the off-diagonal struts are located to represent the interaction between the infill and confining steel frame at locations along the beam-column spans where plastic hinges have been observed to form. The advantages of this analytical model are the following: (a) both strength and stiffness degradation of infill walls are modeled; (b) the parameters of the model have physical meaning and can be readily adapted to fit experimental data; (c) the off-diagonal struts allow modeling of the interaction between the infill and the bounding frame; and (d) local behavior, such as the effects of openings, lack of fit, and interface conditions, can be modeled.
BUCKLING OF SYMMETRICALLY LAMINATED COMPOSITE PLATES USING THE ELEMENT-FREE GALERKIN METHOD
Authors: LIU G. R. , CHEN X. L. , REDDY J. N.
Published: September 2002

An element free Galerkin (EFG) method is presented for buckling analyses of isotropic and symmetrically laminated composite plates using the classical plate theory. The shape functions are constructed using the moving least squares (MLS) approximation, and no element connectivity among nodes is required. The deflection can be easily approximated with higher-order polynomials as desired. The discrete eigenvalue problem is derived using the principle of minimum total potential energy of the system. The essential boundary conditions are introduced into the formulation through the use of the Lagrange multiplier method and the orthogonal transformation techniques. Since the dimension of the eigenvalue problem obtained by the present method is only one third of that in the conventional finite element method (FEM), solving the eigenvalue problem in the EFG is computationally more efficient compared to the FEM. Buckling load param-eters of isotropic and symmetrically laminated composite plates for different boundary conditions are calculated to demonstrate the efficiency of the present method.
ASYMMETRIC CONTESTS FOR BREEDING SITES BETWEEN MONOGAMOUS PAIRS OF CONVICT CICHLIDS (ARCHOCENTRUS NIGROFASCIATUM, CICHLIDAE): PAIR EXPERIENCE PAYS
Authors: Draud Matthew , Lynch Pamela
Published: September 2002

Research on fighting has emphasized contests between individuals, typically males, but pairs also compete. Monogamous pairs of convict cichlids (Archocentrus nigrofasciatum) compete with other pairs for breeding sites in nature. We simulated such contests with competing pairs who differed in one or two of three possible asymmetries: body size, residency, and pair experience. In single-asymmetry experiments, larger pairs defeated smaller pairs, resident pairs defeated intruder pairs, and experienced pairs (those that had been together for 96 hours) defeated novice pairs (those that had been together for 48 hours). Thus, each of the three asymmetries was important in determining the outcome of contests. In further experiments, pairs had two contrasting asymmetries simultaneously. Larger pairs always defeated smaller pairs (15-25% difference in male standard length) even though the larger pair was inferior in one of the other asymmetries. When the two pairs were similar in size (standard length of males differed less than 6%), experienced intruder pairs defeated novice resident pairs nearly half the time. This is the first study to investigate the effects of pair experience on fighting ability. Although we predicted that experience might benefit pairs through improved coordination of their behaviour, behavioral measures such as time spent at the spawning site and pair digging behaviour showed no significant differences among groups. We posit that more experienced pairs fought harder for the breeding site because they were closer to spawning and the expected payoff for winning the breeding site was therefore higher. Finally, when both pairs were of similar size but differed in residence status and experience, there was more escalated fighting than in contests between size-disparate pairs; two possible interpretations of this result are discussed.
TOOLS AND BRAINS IN BIRDS
Authors: Lefebvre Louis , Nicolakakis Nektaria , Boire Denis
Published: September 2002

Tools are traditionally defined as objects that are used as an extension of the body and held directly in the hand or mouth. By these standards, a vulture breaking an egg by hitting it with a stone uses a tool, but a gull dropping an egg on a rock does not. This distinction between true and borderline (or proto-tool) cases has been criticized for its arbitrariness and anthropocentrism. We show here that relative size of the neostriatum and whole brain distinguish the true and borderline categories in birds using tools to obtain food or water. From two sources, the specialized literature on tools and an innovation data base gathered in the short note sections of 68 journals in 7 areas of the world, we collected 39 true (e.g. use of probes, hammers, sponges, scoops) and 86 borderline (e.g. bait fishing, battering and dropping on anvils, holding with wedges and skewers) cases of tool use in 104 species from 15 parvorders. True tool users have a larger mean residual brain size (regressed against body weight) than do users of borderline tools, confirming the distinction in the literature. In multiple regressions, residual brain size and residual size of the neostriatum (one of the areas in the avian telencephalon thought to be equivalent to the mammalian neocortex) are the best predictors of true tool use reports per taxon. Innovation rate is the best predictor of borderline tool use distribution. Despite the strong concentration of true tool use cases in Corvida and Passerida, independent constrasts suggest that common ancestry is not responsible for the association between tool use and size of the neostriatum and whole brain. Our results demonstrate that birds are more frequent tool users than usually thought and that the complex cognitive processes involved in tool use may have repeatedly co-evolved with large brains in several orders of birds.
Sphericity beyond Topicity in Characterizing Stereochemical Phenomena. Novel Concepts Based on Coset Representations and Their Subductions
Authors: Fujita Shinsaku
Published: September 2002

Fundamental concepts proposed for comprehending stereochemical phenomena are described in order to bring out a more systematized format to conventional concepts and terminologies. The concept of coset representation (CR), the symbol of which is G(/Gi), is intuitively introduced by considering the global symmetry G and the local symmetry Gi for an orbit of stereochemically equivalent objects (e.g. atoms in a molecule). The SCR (set-of-coset-representations) notation for classifying molecular symmetries is proposed to remedy the usual insufficient classification based on point groups. According to the chirality/achirality of G and Gi, the sphericity concept (homospheric, enantiospheric, and hemispheric) and the relevant concept of chirality fittingness are proposed to specify the stereochemical phenomena of the G(/Gi)-orbit. The sphericity terms are shown to be superior to the well-known topicity terms (homotopic, enantiotopic, and heterotopic; chirotopic and achirotopic) especially in comprehending complicated stereochemical phenomena. In fact, the topicity terms as well as the terms “stereogenicity and prostereogenicity” and “prochirality” can be derived subsidiarily from the sphericity terms. The concept of subduction of CRs, for which the symbol G(/Gi) ↓ Gi has been coined, is proposed to characterize the desymmetrization of molecules. Thereby, the design of high-symmetry molecules is discussed in term of desymmetrization by atom replacement and by bond replacement. In order to characterize the stereochemistry of non-rigid molecules with rotatable ligands, the concept of proligand/promolecule is proposed; here biphenyl derivatives, methane derivatives, ethane derivatives, and ferrocene derivatives are examined in terms of matched and mismatched molecules. Applications to combinatorial enumeration, symmetry adapted functions, flexible six-membered cyclic compounds, and symmetry numbers are also described.
Synthesis of Mono-Dispersed Mesoporous Silica Spheres with Hexagonal Symmetry
Authors: Yano Kazuhisa , Suzuki Noritomo , Akimoto Yuusuke , Fukushima Yoshiaki
Published: September 2002

Mono-dispersed mesoporous silica spheres with ordered hexagonal regularity were synthesized from tetramethoxysilane and dodecyltrimethylammonium bromide as a surfactant under very specific conditions. By adjusting the optimum concentrations of the reactants, silica particles with diverse morphology were obtained at higher initial concentrations. Dilution of the reactants led to the formation of silica spheres with various sizes and relatively less mesoporous regularity. Mono-dispersed silica spheres could not be obtained when hexadecyltrimethylammonium bromide and tetradecyltrimethylammonium bromide were used as surfactants.
Anodic Oxidation of Benzil Hydrazones in the Presence of Halide Ions
Authors: Okimoto Mitsuhiro , Takahashi Yukio
Published: September 2002

Benzil hydrazones were subjected to electrolytic oxidation in MeOH containing a halide ion source, such as KI and KBr. The results show that the reaction products were dependent on both the electrolytes and the substituents. In the presence of KI, benzoylphenyldiazomethanes were obtained, whereas in the presence of KBr, benzil dimethyl acetals were obtained.
Soccer referees’ experience of threat and aggression: Effects of age, experience, and life orientation on outcome of coping strategy
Authors: Folkesson Per , Nyberg Claes , Archer Trevor , Norlander Torsten
Published: September 2002

The present study examined the circumstances pertaining to threat and aggression during soccer matches as experienced by 107 provincial Soccer Association referees. Three sources of aggression were identified—soccer players, coaches/trainers, and spectators—and the main measures included threat and physical and verbal aggression. Several outcomes, including prematch worry and effects on concentration, performance, and motivation, were affected by the incidence of threat and aggression, and these outcomes were found to be affected by the age, degree of experience, and life orientation of the referees. Younger referees were shown to be the most prone to threat and aggression. Referees with a generally pessimistic orientation experienced less motivation, worse performance, and greater problems coping with aggressive behavior from the spectators compared with referees with a generally optimistic orientation. Aggr. Behav. 28:317–327, 2002. © 2002 Wiley‐Liss, Inc.
Rubber toughening of glass fiber reinforced nylon‐6,6 with functionalized block copolymer SEBS‐g‐MA
Authors: Karayannidis George P. , Bikiaris Demetris N. , Papageorgiou George Z. , Bakirtzis Vassilios
Published: September 2002

The toughening of glass fiber reinforced nylon‐6,6 (PA‐6,6) by using the functionalized triblock copolymer styrene‐(ethylene‐co‐butylene)‐styrene, grafted with maleic anhydride (SEBS‐g‐MA) was examined. Blends containing 2.5, 5, 7.5, 10, and 12.5 wt% copolymer were prepared by melt blending in a single‐screw extruder. Emphasis was given to the study of mechanical properties in comparison with morphology and thermal properties of the aforementioned samples. Although the amount of SEBS‐g‐MA that was added in PA‐6,6 was not enough to produce a super‐tough material, a significant increase in the resistance to crack propagation and impact strength was observed in all blends. This behavior was proportional to the amount of SEBS‐g‐MA that was added for samples having up to 10%, rubber, while additional amounts seem to have no further effect. A small decrease in tensile strength was also observed. From FTIR spectroscopy and DSC analysis it was shown that the grafting extent of SEBS‐g‐MA to PA‐6,6 was very low. © 2002 Wiley Periodicals, Inc. Adv Polym Techn 21: 153–163, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/adv.10023
Severe farm injuries among New York farmers
Authors: Hwang Syni‐An , Gomez Marta I. , Stark Alice D. , St. John Tonya Lowery , May John J. , Hallman Eric M.
Published: September 2002

Background

Data from the telephone interview portion of the New York State Farm Family Health and Hazard Surveillance were used to study the incidence and predictors of severe farm injury.

Methods

One thousand seven hundred and six participants completed two telephone interviews in which they reported all injuries over a 12‐month period.

Results

Nine percent of participants reported at least one severe farm injury. Using logistic regression the significant risk factors for sustaining at least one severe farm injury are younger age, the presence of hearing loss or joint trouble, working more hours per day, being the owner/operator of the farm, and being from a farm with higher gross sales.

Conclusions

There needs to be continuing education of all farmers as to the risks of injury. However, when resources are limited, we recommend that injury education and interventions in this farming population should target younger farmers, those who work longer hours, owner/operators, farmers from higher grossing farms, with special attention to farmers who have physical impairments. Am. J. Ind. Med. 40:32–41, 2001. © 2001 Wiley‐Liss, Inc.
Familial frontotemporal dementia and parkinsonism with a novel mutation at an intron 10+11‐splice site in the tau gene
Authors: Miyamoto Katsuichi , Kowalska Anna , Hasegawa Masato , Tabira Takeshi , Takahashi Keikichi , Araki Wataru , Akiguchi Ichiro , Ikemoto Akito
Published: September 2002

We report a case of familial frontotemporal dementia and parkinsonism characterized by early onset with mental retardation. The patient died at the age of 54; neuronal loss was severe in the frontal and temporal cortices, globus pallidus, substantia nigra, red nucleus and dentate nucleus. Anti‐tau‐positive fibrillary changes were observed in neurons and glia in these regions. Although the patient had 2 novel point mutations of the tau gene, P301P (CCG to CCA) and an intron 10+11‐splice site (T to C), exon trapping analysis indicated that the latter was pathogenic.
Chemical speciation of inorganic and methylarsenic(III) compounds in aqueous solutions
Authors: Hasegawa Hiroshi , Sohrin Yoshiki , Matsui Masakazu , Takeda Noriko , Ueda Kazumasa
Published: September 2002

Speciation of inorganic and methylarsenic(III) species in aqueous hydrochloric acid solutions has been studied by the solvent extraction method. In a hydrochloric acid–carbon tetrachloride system, inorganic and methylarsenic(III) species formed the corresponding chlorides and were extracted into the organic phase. The extractability of inorganic and methylarsenic(III) species increased as the number of methyl groups attached to the arsenic atom increased. In addition, dimerization of dimethylarsinous acid occurred with decreasing acidity in the aqueous phase. On the basis of the data obtained, we determined the stability constants for the proposed species, and evaluated the effect of methyl groups on the speciation and the reactivity of inorganic and methylarsenic(III) species in aqueous solutions. Copyright © 2002 John Wiley & Sons, Ltd.
Synthesis, characterization, and properties of a selective adsorbent to mercury(II) ions
Authors: Rivas Bernabé L. , Pooley S. Amalia , Aceitón Evelyn , Geckeler Kurt E.
Published: September 2002

A resin containing 3‐(dimethylamine)propyl acrylate and 4‐vinylpyridine was synthesized by radical polymerization (in 1:1 mole ratio). Ammonium persulfate (0.5 mol %) and N,N′‐methylene‐bis‐acrylamide (2 mol %) were used as initiator and crosslinking reagents, respectively. The resin was characterized by Fourier transform infrared (FTIR) and ultraviolet‐visible (UV‐Vis) spectroscopy. The ability to bind Hg(II), Cd(II), Zn(II), Pb(II), Cu(II), and Cr(III) as well as the maximum adsorption capacity and elution of Hg(II) ions from the loaded resin was studied. Sorption selectivity from ternary mixture Hg(II), Cd(II), and Zn(II) was studied at the optimum sorption pH value. At pH 2 the adsorbent retained 98% of Hg(II); the retention of the other metal ions was lower than 20%. The elution assay was made in HClO4 solutions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2559–2563, 2002
Study of compatibilization of HDPE–PET blends by adding grafted or statistical copolymers
Authors: Torres N. , Robin J. J. , Boutevin B.
Published: September 2002

The reactive compatibilization of blends of HDPE–PET [high‐density polyethylene–poly(ethylene terephthalate)] was investigated in this study. The compatibilizers used were two grafted copolymers prepared by reactive extrusion containing 1.20–2.30 wt % GMA such as HDPE‐g‐GMA and one statistical copolymer containing 1 wt % GMA such as Lotader AX8920. HDPE was successfully functionalized using a melt free‐radical grafting technique. Grafting was initiated in two ways: adding an initiator in the polymer–monomer mixture or activation by ozone of polymer. Ozonization of HDPE by the introduction of a peroxide lead to a better grafting yield and to better grafting efficiency of the samples. The effects of the three compatibilizers were evaluated by studying the morphology and the thermal and mechanical properties of HDPE–PET (70/30 wt %) blends. Significant improvements were observed, especially in morphology, elongation at break, and Charpy impact strength of the compatibilized blends. A more pronounced compatibilizing effect was obtained with the statistical copolymer, for which the elongation at break and the impact strength were increased by 100%, while the uncompatibilized blends showed a 60% decrease in the Young's modulus and the strength at break. We also were able to show that the grafting yield increase of 1.20–2.30 wt % of GMA did not affect the properties of the blends because the grafted copolymers possess very similar chemical structures. However, compatibilization of blends with grafted copolymers is an interesting method, particularly for recycled blends, because the synthesis of these compatibilizers is easy and cheap in comparison to statistical copolymer. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2377–2386, 2001
Molecular weight and distribution of copolymer of lignin‐phenol in copolymerization catalyzed by peroxidase
Authors: Liu Junhong , Li Liangzhi , Cheng Jiangfeng , Wang Lixin , Ye Lin
Published: September 2002

The molecular weight and distribution of lignin‐cresol polymer in peroxidase‐catalyzed copolymerization of lignin with cresol in the reversed micellar system can be controlled by adjusting the surfactant concentration and other factors. The maximal mean molecular weight of copolymer obtained is 1890 kDa. The surfactant sustains chain growth. The cresol and/or polycresol is incorporated into the copolymer, and the thermal property of the copolymer is improved. A correlation for copolymer mean molecular weight is developed. The synthesized copolymer drops out of solution and can be easily recovered. The materials appear to act as thermosets and may have applications as replacements of conventional phenolic resins. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2408–2418, 2001
Synthesis and thermal analysis of emulsion terpolymers of N‐phenylmaleimide, methyl methacrylate, and acrylonitrile
Authors: Yang Liting , Zhang Liucheng , Liu Guodong , Gao Jungang , Yang Mingshan , Jin Riguang
Published: September 2002

Terpolymers of N‐phenylmaleimide (PMI), methyl methacrylate (MMA), and acrylonitrile (AN) were synthesized by emulsion polymerization. The thermal properties of the terpolymers, at different PMI and AN feed contents, were investigated by TBA, TGA, and the Vicat softening point test. The results show that the glass transition temperature (Tg) and decomposition temperature of the terpolymers increase with increasing PMI feed content. Furthermore, the Vicat softening points of the terpolymers increase with the PMI feed content. The M̄w and M̄n of the terpolymers were also determined by GPC. The results show that the M̄w and M̄n of the terpolymers have a maximum value in the range of 0–30% PMI feed content and decrease with an increasing AN feed content. The mechanical properties (tensile strength and impact strength) of the terpolymers decrease with an increasing PMI feed content and increase with an increasing AN feed content. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2455–2462, 2001
Study of the thermal properties and relaxation transitions in tetrafluoroethene‐ethene copolymers
Authors: Kostov G. , Nikolov Al. , Atanassov At.
Published: September 2002

Copolymerization of tetrafluoroethene (TFE) with ethene (E) in water‐alcohol medium initiated by 2,2′‐azo‐bis‐izobutyronitrile (AIBN) at 338 K and 4.2 MPa was conducted in an autoclave by employing a semiflow procedure to feed the comonomers. The thermal properties of the copolymers under both the static and dynamic conditions of thermal treatment in air (ageing) were studied. The most pronounced changes in the initial temperature of destruction were observed for the compositions containing more than 42 mol % TFE, which corresponded to the formation of alternating copolymers. The reaction of thermal degradation was found to follow the first order kinetic equation, with the activation energy 174 kJ · mol−1. The higher thermal stability of the alternating TFE‐E copolymers was proved by IR spectroscopy and DTA analysis. Both the melting and crystallization DSC scans of copolymers of various compositions were analyzed. Monomodal peak of melting (and respectively, crystallization) was observed in both scans for the alternating copolymer, whereas the second peak appeared for the copolymer fractions with the higher content of ethylene block fragments and 30–40 mol % TFE units. The dynamic‐mechanical analysis showed three relaxation transitions (γ, β1 and β2, α) in the temperature interval from 173–433 K, related to the mobility of structural units of different type in the copolymers prepared. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2626–2632, 2001
Electro‐optic properties of CO2 fixed‐polymer/nematic LC composite films
Authors: Cho Yeong Hee , Kim Byung Kyu
Published: September 2002

Bis(cyclic carbonate) was obtained from the epoxide and CO2 reaction with a quaternary ammonium halide salt catalyst. Cyclic carbonate derivatives were then reacted with amine to obtain quantitatively poly(hydroxy)urethanes that were reacted with isophorone diisocyanate (IPDI) and end capped with acrylate to form prepolymers. These prepolymers were mixed with reactive diluents and nematic LCs, and subjected to UV cure to form polymer/LC composite films in a transparent cell. Three types of diglycidyl ether [poly(propyleneglycol), cyclohexane, bisphenol A], three types of end‐capping acrylates [2‐hydroxyethyl acrylate (HEA), 2‐hydroxypropyl acrylate (HPA), and 2‐hydroxyethyl methacrylate (HEMA)], three types of multyfunctional diluents [tripropylene glycol diacrylate (TPGDA), trimethylolpropane triacrylate (TMPTA), dipentaerythritol hydroxy penta/hexa acrylate (DPHPA)], and three types of photoinitiators (Irgacure‐651, Irgacure‐184, Darocure‐1173) were incorporated to control the morphology, and hence, the electro‐optic properties of the polymer/nematic LC composite films. Poly(propylene glycol) diglycidyl ether segment of polyurethane acrylate (PUA) showed lower viscosity and gave larger domain size resulting in lower threshold (V10) and driving (V90) voltages, together with larger nematic–isotropic transition temperature depression. HEA end‐capped PUA gave larger polymer–LC phase separation and smaller V10 as well as V90. TPGDA‐based PUA showed the lowest V10 and V90 and the shortest response time. Among the three types of photoinitiators used Irgacure‐651 showed the larger LC domain, and smaller V10 and V90. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2744–2753, 2001
Novel copolyesters containing naphthalene structure III. Copolyesters prepared from 2,6‐dimethyl naphthalate, ethylene glycol, and 2,2‐dialkyl‐1,3‐propanediols
Authors: Sun Yih‐Min , Liu Hung‐Hsin
Published: September 2002

Poly(ethylene naphthalate) (PEN) copolymers were prepared by melt polycondensation of dimethyl naphthalate and excess ethylene glycol with 5–40 mol % (in feed) of 1,3‐propanediol or 2,2‐dialkyl‐1,3‐propanediols, where the dialkyl groups are dimethyl, diethyl, and butyl‐ethyl. No significant depression of reduced specific viscosity was observed. The comonomer contents in the copolymers are considerably higher than those in the feed. The effects of the copolymer composition on the structures of the films were investigated using thermal analyses, density measurements, X‐ray diffraction methods, and other physical tests. The crystallinities and densities of heat‐treated films decreased with increasing content of comonomer and length of alkyl side chain in the comonomer. The glass transition temperature (Tg) and melting temperature (Tm) were decreased by the copolymerization, while an increase in the length of the alkyl side chain hardly affected Tms of the heat‐treated films. Alkali resistance, moisture resistance, dye ability, and thermal shrinkage were increased by the incorporation of comonomer having an alkyl side chain. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2754–2763, 2001
Rigid amorphous phase and low temperature melting endotherm of poly(ethylene terephthalate) studied by modulated differential scanning calorimetry
Authors: Song M.
Published: September 2002

The rigid amorphous phase, the low temperature melting endotherm, and their development with thermal treatment in poly(ethylene terephthalate) (PET) were investigated by means of modulated differential scanning calorimetry. The differential of the reversing heat capacity and nonreversing heat flow signals were used to analyze the behavior of the glass transition and the low temperature melting endotherm. With increasing annealing time, the increment of the heat capacity at the glass‐transition temperature decreased and the increment of heat capacity at the annealing temperature increased. It was suggested that the origin of the low temperature melting endotherm mainly resulted from the transition of the rigid amorphous fraction for the PET used. The glasslike transition of the rigid amorphous fraction occurred between the glass transition and melting. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2779–2785, 2001
Development of novel elastomeric blends containing natural rubber and ultra‐low‐density polyethylene
Authors: Tanrattanakul V. , Udomkichdecha W.
Published: September 2002

This study sought to develop novel elastomeric compounds using natural rubber (NR) and ultra‐low‐density polyethylene (ULDPE). Blends were prepared by means of a two‐roll mill for three ratios (70/30, 60/40, and 50/50 NR/ULDPE). Conventional vulcanization was performed in a compression mold. The physical and mechanical properties of the blend were determined according to ASTM standards. The results were compared with those obtained from NR blended with styrene‐butadiene rubber (SBR). The morphological examinations with scanning electron microscopy indicated that ULDPE was compatible with NR; thus, the addition of a compatibilizer was not necessary. The cocontinuous phase was dominant in the NR/ULDPE blend containing 50 and 60 wt % NR. The tensile properties, tear resistance, and aging resistance of the NR/ULDPE blends were found to be superior to those of NR/SBR blends. On the other hand, the abrasion and flex cracking resistances of the NR/ULDPE blend were inferior to those exhibited by SBR blends but the Mooney viscosity and resilience of both blends fell in the same range. However, the addition of dicumyl peroxide appeared to have caused crosslinking of the ULDPE phase in the blend, which in turn increased the tensile properties and abrasion and aging resistance. The properties of the tertiary NR/SBR/ULDPE blend were investigated as well. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 650–660, 2001
Determination of bone volume by osteocyte population
Authors: Vashishth D. , Gibson G. , Kimura J. , Schaffler M.B. , Fyhrie D.P.
Published: September 2002

During development and growth, biological tissues and organisms can control their size and mass by regulating cell number (Raff, 1992; Conlon and Raff, 1999). Later in life both cell number and organ mass decrease (Buetow, 1985). We demonstrate that the number density of bone cells buried in the calcified matrix (osteocyte lacunar density) predicts extracellular matrix volume for both cancellous and cortical bone in a broad cross‐section of the population (males and females, age range 23–91 years, r2 = 0.98). Our hypothesis is that bone mass is determined by the control of osteocyte number, and that this is a particular instance of the control of organ size through the social controls on cell survival and death (Raff, 1992; Conlon and Raff, 1999). Anat Rec 267:292–295, 2002. © 2002 Wiley‐Liss, Inc.
Very low prevalence of hip osteoarthritis among Chinese elderly in Beijing, China, compared with whites in the United States: The Beijing osteoarthritis study
Authors: Nevitt Michael C. , Xu Ling , Zhang Yuqing , Lui Li‐Yung , Yu Wei , Lane Nancy E. , Qin Mingwei , Hochberg Marc C. , Cummings Steven R. , Felson David T.
Published: September 2002

Objective

To compare the prevalence of osteoarthritis (OA) of the hip among elderly persons in China and the US.

Methods

We recruited a population‐based sample of 1,506 persons (82% of those enumerated) ages ≥60 years living in Beijing, China. Subjects answered questions about joint symptoms and underwent radiography of the pelvis. Radiographs of the Beijing subjects were intermingled with hip radiographs of white women ages ≥65 years from the Study of Osteoporotic Fractures (SOF) and white men and women ages 60–74 years from the First National Health and Nutrition Examination Survey (NHANES‐I) and were then interpreted. Radiographic hip OA was defined as the presence of 1 of the following 3 findings in either hip: minimum joint space of ≤1.5 mm, definite osteophytes and joint space narrowing, or ≥3 radiographic features of OA. Symptomatic hip OA was defined as both radiographic OA and hip pain.

Results

The crude prevalence of radiographic hip OA in Chinese ages 60–89 years was 0.9% in women and 1.1% in men; it did not increase with age. Chinese women had a lower age‐standardized prevalence of radiographic hip OA compared with white women in the SOF (age‐standardized prevalence ratio 0.07) and the NHANES‐I (prevalence ratio 0.22). Chinese men had a lower prevalence of radiographic hip OA compared with white men of the same age in the NHANES‐I (prevalence ratio 0.19). There were no cases of symptomatic hip OA in the Chinese men and only 1 case in the Chinese women; 35 cases were expected in both sexes.

Conclusion

This is the first population‐based study of hip OA in China to use standardized radiographic methods and definitions. We found that hip OA was 80–90% less frequent than in white persons in the US. Identification of the genetic and environmental factors that underlie these differences may help elucidate the etiology and prevention of hip OA.