bluuebunny/crossref_metadata_2025 huggingface dataset:
Iliofemoral distraction and hip reconstruction for the sequelae of a septic dislocated hip with chronic femoral osteomyelitis
Authors: Nagarajah K. , Aslam N. , McLardy Smith P. , McNally M.
Published: May 2005

We describe a technique of ‘cross-hip distraction’ to reduce a dislocated hip with subsequent reconstruction of the joint for septic arthritis with extensive femoral osteomyelitis. A 27-year-old woman presented with a dislocated, collapsed femoral head and chronic osteomyelitis of the femur. Examination revealed a leg-length discrepancy of 7 cm and an irritable hip. A staged technique was used with primary clearance of osteomyelitis and secondary reconstruction of the hip. A cross-hip monolateral external fixator was used to establish normal anatomy followed by an arthroplasty. A good functional outcome was achieved. The use of cross-hip distraction avoids soft-tissue and nerve damage and achieved improved abductor function before arthroplasty.
Entrapment of a displaced common peroneal nerve following knee ligament reconstruction
Authors: Montgomery A. S. , Birch R. , Malone A.
Published: May 2005

We present a case of disruption of the posterolateral corner of the knee with avulsion of the tendon of biceps femoris. Repair and reconstruction included an allogenic tendon graft to replace the posterior cruciate ligament. Surgery was followed by a complete common peroneal nerve palsy. Revision surgery revealed that the nerve had been displaced anteriorly by avulsion of the biceps tendon and the tendon graft encircled it. Release of the nerve restored normal function at five months.
“Kissing a Baby Is Not at All Good for Him”: Infant Mortality, Medicine, and Colonial Modernity in the U.S.‐Occupied Philippines
Authors: McELHINNY BONNIE
Published: May 2005

Feminist scholars have begun to consider the ways indigenous practices of child rearing were and are challenged in (post)colonial discourse and practice, and how these practices have become a terrain on which definitions of nation, state, and economy are contested. In this article, I adopt a historical anthropological approach to consider how Filipino child‐rearing strategies were described and stigmatized in educational, public health, and public welfare discourses in the U.S.‐occupied Philippines in the early 20th century. I demonstrate how public health practices and discourses that were generated as part of a “benevolent” campaign against high rates of infant mortality were strategically used as a weapon against Filipino arguments for independence. I also consider how discourses constructing Filipino caregivers as overly indulgent were linked to metropolitan concerns about production of the “new industrial man” and were used to develop a racialized critique of the cultural practices of Filipinos.
High-Diversity Genes in the Arabidopsis GenomeSequence data from this article have been deposited with the EMBL/GenBank Data Libraries under accession nos. DQ132063, DQ132370.
Authors: Cork Jennifer M , Purugganan Michael D
Published: May 2005

High-diversity genes represent an important class of loci in organismal genomes. Since elevated levels of nucleotide variation are a key component of the molecular signature for balancing selection or local adaptation, high-diversity genes may represent loci whose alleles are selectively maintained as balanced polymorphisms. Comparison of 4300 random shotgun sequence fragments of the Arabidopsis thaliana Ler ecotype genome with the whole genomic sequence of the Col-0 ecotype identified 60 genes with putatively high levels of intraspecific variability. Eleven of these genes were sequenced in multiple A. thaliana accessions, 3 of which were found to display elevated levels of nucleotide polymorphism. These genes encode the myb-like transcription factor MYB103, a putative soluble starch synthase I, and a homeodomain-leucine zipper transcription factor. Analysis of these genes and 4–7 flanking genes in 14–20 A. thaliana ecotypes revealed that two of these loci show other characteristics of balanced polymorphisms, including broad peaks of nucleotide diversity spanning multiple linked genes and an excess of intermediate-frequency polymorphisms. Scanning genomes for high-diversity genomic regions may be useful in approaches to adaptive trait locus mapping for uncovering candidate balanced polymorphisms.
FRIGIDA-Independent Variation in Flowering Time of Natural Arabidopsis thaliana Accessions
Authors: Werner Jonathan D , Borevitz Justin O , Uhlenhaut N Henriette , Ecker Joseph R , Chory Joanne , Weigel Detlef
Published: May 2005

FRIGIDA (FRI) and FLOWERING LOCUS C (FLC) are two genes that, unless plants are vernalized, greatly delay flowering time in Arabidopsis thaliana. Natural loss-of-function mutations in FRI cause the early flowering growth habits of many A. thaliana accessions. To quantify the variation among wild accessions due to FRI, and to identify additional genetic loci in wild accessions that influence flowering time, we surveyed the flowering times of 145 accessions in long-day photoperiods, with and without a 30-day vernalization treatment, and genotyped them for two common natural lesions in FRI. FRI is disrupted in at least 84 of the accessions, accounting for only ∼40% of the flowering-time variation in long days. During efforts to dissect the causes for variation that are independent of known dysfunctional FRI alleles, we found new loss-of-function alleles in FLC, as well as late-flowering alleles that do not map to FRI or FLC. An FLC nonsense mutation was found in the early flowering Van-0 accession, which has otherwise functional FRI. In contrast, Lz-0 flowers late because of high levels of FLC expression, even though it has a deletion in FRI. Finally, eXtreme array mapping identified genomic regions linked to the vernalization-independent, late-flowering habit of Bur-0, which has an alternatively spliced FLC allele that behaves as a null allele.
Effects of Natural Selection on Interpopulation Divergence at Polymorphic Sites in Human Protein-Coding Loci
Authors: Hughes Austin L , Packer Bernice , Welch Robert , Bergen Andrew W , Chanock Stephen J , Yeager Meredith
Published: May 2005

To develop new strategies for searching for genetic associations with complex human diseases, we analyzed 2784 single-nucleotide polymorphisms (SNPs) in 396 protein-coding genes involved in biological processes relevant to cancer and other complex diseases, with respect to gene diversity within samples of individuals representing the three major historic human populations (African, European, and Asian) and with respect to interpopulation genetic distance. Reduced levels of both intrapopulation gene diversity and interpopulation genetic distance were seen in the case of SNPs located within the 5′-UTR and at nonsynonymous SNPs, causing radical changes to protein structure. Reduction of gene diversity at SNP loci in these categories was evidence of purifying selection acting at these sites, which in turn causes a reduction in interpopulation divergence. By contrast, a small number of SNP sites in these categories revealed unusually high genetic distances between the two most diverged populations (African and Asian); these loci may have historically been subject to divergent selection pressures.
Distinguishing Between Selective Sweeps and Demography Using DNA Polymorphism Data
Authors: Jensen Jeffrey D , Kim Yuseob , DuMont Vanessa Bauer , Aquadro Charles F , Bustamante Carlos D
Published: May 2005

In 2002 Kim and Stephan proposed a promising composite-likelihood method for localizing and estimating the fitness advantage of a recently fixed beneficial mutation. Here, we demonstrate that their composite-likelihood-ratio (CLR) test comparing selective and neutral hypotheses is not robust to undetected population structure or a recent bottleneck, with some parameter combinations resulting in a false positive rate of nearly 90%. We also propose a goodness-of-fit test for discriminating rejections due to directional selection (true positive) from those due to population and demographic forces (false positives) and demonstrate that the new method has high sensitivity to differentiate the two classes of rejections.
The Rate of Compensatory Mutation in the DNA Bacteriophage φX174
Authors: Poon Art , Chao Lin
Published: May 2005

A compensatory mutation occurs when the fitness loss caused by one mutation is remedied by its epistatic interaction with a second mutation at a different site in the genome. This poorly understood biological phenomenon has important implications, not only for the evolutionary consequences of mutation, but also for the genetic complexity of adaptation. We have carried out the first direct experimental measurement of the average rate of compensatory mutation. An arbitrary selection of 21 missense substitutions with deleterious effects on fitness was introduced by site-directed mutagenesis into the bacteriophage φX174. For each deleterious mutation, we evolved 8–16 replicate populations to determine the frequency at which a compensatory mutation, instead of the back mutation, was acquired to recover fitness. The overall frequency of compensatory mutation was ∼70%. Deleterious mutations that were more severe were significantly more likely to be compensated for. Furthermore, experimental reversion of deleterious mutations revealed that compensatory mutations have deleterious effects in a wild-type background. A large diversity of intragenic compensatory mutations was identified from sequencing fitness-recovering genotypes. Subsequent analyses of intragenic mutation diversity revealed a significant degree of clustering around the deleterious mutation in the linear sequence and also within folded protein structures. Moreover, a likelihood analysis of mutation diversity predicts that, on average, a deleterious mutation can be compensated by about nine different intragenic compensatory mutations. We estimate that about half of all compensatory mutations are located extragenically in this organism.
In Vivo Characterization of the Nonessential Budding Yeast Anaphase-Promoting Complex/Cyclosome Components Swm1p, Mnd2p and Apc9p
Authors: Page Andrew M , Aneliunas Vicky , Lamb John R , Hieter Philip
Published: May 2005

We have examined the in vivo requirement of two recently identified nonessential components of the budding yeast anaphase-promoting complex, Swm1p and Mnd2p, as well as that of the previously identified subunit Apc9p. swm1Δ mutants exhibit synthetic lethality or conditional synthetic lethality with other APC/C subunits and regulators, whereas mnd2Δ mutants are less sensitive to perturbation of the APC/C. swm1Δ mutants, but not mnd2Δ mutants, exhibit defects in APC/C substrate turnover, both during the mitotic cell cycle and in α-factor-arrested cells. In contrast, apc9Δ mutants exhibit only minor defects in substrate degradation in α-factor-arrested cells. In cycling cells, degradation of Clb2p, but not Pds1p or Clb5p, is delayed in apc9Δ. Our findings suggest that Swm1p is required for full catalytic activity of the APC/C, whereas the requirement of Mnd2p for APC/C function appears to be negligible under standard laboratory conditions. Furthermore, the role of Apc9p in APC/C-dependent ubiquitination may be limited to the proteolysis of a select number of substrates.
Bayesian Model Selection for Genome-Wide Epistatic Quantitative Trait Loci Analysis
Authors: Yi Nengjun , Yandell Brian S , Churchill Gary A , Allison David B , Eisen Eugene J , Pomp Daniel
Published: May 2005

The problem of identifying complex epistatic quantitative trait loci (QTL) across the entire genome continues to be a formidable challenge for geneticists. The complexity of genome-wide epistatic analysis results mainly from the number of QTL being unknown and the number of possible epistatic effects being huge. In this article, we use a composite model space approach to develop a Bayesian model selection framework for identifying epistatic QTL for complex traits in experimental crosses from two inbred lines. By placing a liberal constraint on the upper bound of the number of detectable QTL we restrict attention to models of fixed dimension, greatly simplifying calculations. Indicators specify which main and epistatic effects of putative QTL are included. We detail how to use prior knowledge to bound the number of detectable QTL and to specify prior distributions for indicators of genetic effects. We develop a computationally efficient Markov chain Monte Carlo (MCMC) algorithm using the Gibbs sampler and Metropolis-Hastings algorithm to explore the posterior distribution. We illustrate the proposed method by detecting new epistatic QTL for obesity in a backcross of CAST/Ei mice onto M16i.
Sobo, a Recently Amplified Satellite Repeat of Potato, and Its Implications for the Origin of Tandemly Repeated Sequences
Authors: Tek Ahmet L , Song Junqi , Macas Jiri , Jiang Jiming
Published: May 2005

Highly repetitive satellite DNA sequences are main components of heterochromatin in higher eukaryotic genomes. It is well known that satellite repeats can expand and contract dramatically, which may result in significant genome size variation among genetically related species. The origin of satellite repeats, however, is elusive. Here we report a satellite repeat, Sobo, from a diploid potato species, Solanum bulbocastanum. The Sobo repeat is mapped to a single location in the pericentromeric region of chromosome 7. This single Sobo locus spans ∼360 kb of a 4.7-kb monomer. Sequence analysis revealed that the major part of the Sobo monomer shares significant sequence similarity with the long terminal repeats (LTRs) of a retrotransposon. The Sobo repeat was not detected in other Solanum species and is absent in some S. bulbocastanum accessions. Sobo monomers are highly homogenized and share >99% sequence identity. These results suggest that the Sobo repeat is a recently emerged satellite and possibly originated by a sudden amplification of a genomic region including the LTR of a retrotransposon and its flanking genomic sequences.
Genetic Analysis Reveals a Role for the C Terminus of the Saccharomyces cerevisiae GTPase Snu114 During Spliceosome Activation
Authors: Brenner Tamara J , Guthrie Christine
Published: May 2005

Snu114 is the only GTPase required for mRNA splicing. As a homolog of elongation factor G, it contains three domains (III–V) predicted to undergo a large rearrangement following GTP hydrolysis. To assess the functional importance of the domains of Snu114, we used random mutagenesis to create conditionally lethal alleles. We identified three main classes: (1) mutations that are predicted to affect GTP binding and hydrolysis, (2) mutations that are clustered in 10- to 20-amino-acid stretches in each of domains III–V, and (3) mutations that result in deletion of up to 70 amino acids from the C terminus. Representative mutations from each of these classes blocked the first step of splicing in vivo and in vitro. The growth defects caused by most alleles were synthetically exacerbated by mutations in PRP8, a U5 snRNP protein that physically interacts with Snu114, as well as in genes involved in snRNP biogenesis, including SAD1 and BRR1. The allele snu114-60, which truncates the C terminus, was synthetically lethal with factors required for activation of the spliceosome, including the DExD/H-box ATPases BRR2 and PRP28. We propose that GTP hydrolysis results in a rearrangement between Prp8 and the C terminus of Snu114 that leads to release of U1 and U4, thus activating the spliceosome for catalysis.
Book Reviews
Authors: Kenesei Andrea , Tóth Zsuzsa N. , Perego Elisa , Godó Ágnes
Published: May 2005

Anthony Pym: The Moving Text Localization, Translation, and Distribution. Benjamins Translation Library 49 Amsterdam: John Benjamins. 2004, 223 pp. ISBN 902721655X; Sándor Albert: Fordítás és filozófia [Translation and Philosophy]. Budapest: Tinta Könyvkiadó. 2003, 154 pp. ISBN 963 9372 39 0; The translator. Studies in intercultural communication. Special Issue: Screen translation, Guest Editor: Yves Gambier, Volume 9, Number 2, 2003. Manchester: St. Jerome Publishing. ISBN 1-900650-71-1; Barbara Kroll (ed.) Exploring the Dynamics of Second Language Writing. Cambridge: CUP. 2003, 342 pp. ISBN 0-521-52983-2;
Quadratic functionals on modules over *-rings
Authors: Ilišević Dijana
Published: May 2005

The aim of this paper is to give a solution to the problem of the representability of quadratic functionals, acting on modules over *-rings, by symmetric (weak) sesquilinear forms. The obtained results generalize the one given by P. Šemrl and B. Zalar to a larger class of *-rings.
On curves contained in convex subsets of the plane
Authors: Coppersmith Don , Nagy Győző , Ravsky Sasha
Published: May 2005

If K' ?  K are convex bodies of the plane then the perimeter of K' is not greater than the perimeter of K. We obtain the following generalization of this fact. Let K be a convex compact body of the plane with perimeter p and diameter d and let  r ? 1 be an integer. Let s be the smallest number such that for any curve of length greater than s contained in K there is a straight line intersecting the curve at least in r+1 different points. Then s = rp/2 if r is even and  s = (r-1) p/2 + d if r is odd.
Encouraging Independent Reading With Ambience: The Book Bistro in Middle and Secondary School Classes
Authors: Kasten Wendy C. , Wilfong Lori G.
Published: May 2005

This article makes a case for devoting time to independent reading and then describes the “Book Bistro,” a strategy for promoting independent reading. Research concerning adolescents and reading is reviewed, followed by detailed instructions for implementing Book Bistro and advice from teachers. In Book Bistro, adolescent students are invited once per month to bring an independent reading choice to a café setting created in the classroom or school lunchroom. Students evaluate classmates to their right and to their left, creating material for each student's reading file. Book Bistro implements the best of what is known about encouraging independent reading using self‐selected reading, book discussion, and peer interaction about books. One action research study and one field‐testing initiative are described, along with suggestions for further study with different age groups.
Myth Education: Rationale and Strategies for Teaching Against Linguistic Prejudice
Authors: Zuidema Leah A.
Published: May 2005

People frequently make assumptions about others because of their spoken or written use of a particular dialect or language. The varieties of English that people use are often regarded as indicators of corresponding intelligence, competence, motives, and morality. Such assumptions—frequently based on myths and misconceptions about the nature of language—can lead to discriminatory practices. Literacy educators should work to combat prejudice by dispelling linguistic myths and working with students to expose and critique the processes and institutions that perpetuate such misconceptions. This article outlines and critiques common myths that contribute to language‐based discrimination. These myths include misunderstandings about grammar and usage rules, misinformed beliefs about particular language varieties as “random” rather than rule governed, and misconceptions about how to judge the relative value or quality of specific language varieties. In addition, the author suggests activities that encourage learners to investigate the actual nature of linguistic diversity and to question the ways that linguistic prejudice is propagated institutionally.
Multicultural Literature and Discussion as Mirror and Window?
Authors: Glazier Jocelyn , Seo Jung‐A
Published: May 2005

In recent years, multicultural literature has made its way into language arts education reform documents, onto classrooms shelves, and ultimately into the hands of the diverse student body in the United States. This article documents the experiences of a ninth‐grade class as students read and responded to N. Scott Momaday's The Way to Rainy Mountain and related texts. By including multicultural texts in her curriculum, the teacher helped her students respect and understand their own culture and that of others. While the experience enabled minority students to find their voices in the classroom, in some respects it simultaneously stifled the voices of majority students. Although the use of multicultural literature sheds light on the cultures of others and holds up a mirror to students' own culture, it can also reinforce notions of “culturelessness” among white, European American student populations. If multicultural literature is to act as mirror and window for all students, thus leading to a more culturally affirming reality in schools, it is imperative for teachers and students to include “whiteness” in conversations about culture.
Effects of Public Policy on Adolescents’ Cigar Use: Evidence From the National Youth Tobacco Survey
Authors: Ringel Jeanne S. , Wasserman Jeffrey , Andreyeva Tatiana
Published: May 2005

To determine the effect of prices and regulations on youth cigar demand, we estimated logistic regression models of the probability of current cigar smoking among students in grades 6 to 12 with data from the 1999 and 2000 waves of the National Youth Tobacco Survey. We found that youth cigar demand is sensitive to price but not state tobacco-control regulations. The results suggested that raising excise taxes on cigars could reduce cigar use prevalence among youths.
Preference for Fall From Height as a Method of Suicide by Elderly Residents of New York City
Authors: Abrams Robert C. , Marzuk Peter M. , Tardiff Kenneth , Leon Andrew C.
Published: May 2005

We studied all medical examiner–certified suicides in New York City from 1990 to 1998 to compare suicide methods used by elderly and younger adults. Associations between age and suicide method and place of occurrence were examined. Fall from height was more likely to have been used by individuals 65 or older than by those who were younger. Among persons who died by fall from height, those 65 or older were more likely than others to have fallen from buildings where they lived.
Prevalence of Depression by Race/Ethnicity: Findings From the National Health and Nutrition Examination Survey III
Authors: Riolo Stephanie A. , Nguyen Tuan Anh , Greden John F. , King Cheryl A.
Published: May 2005

Depression prevalence was examined by race/ethnicity in a nationally representative sample. The Diagnostic Interview Schedule was administered to 8449 (response rate=96.1%) participants (aged 15–40 years). Prevalence of major depressive disorder was significantly higher in Whites than in African Americans and Mexican Americans; the opposite pattern was found for dysthymic disorder. Across racial/ethnic groups, poverty was a significant risk factor for major depressive disorder, but significant interactions occurred between race/ethnicity, gender, and education in relation to prevalence of dysthymic disorder.
In Situ Hybridization to Metaphase Chromosomes and Interphase Nuclei
Authors: Knoll Joan H. M. , Lichter Peter
Published: May 2005

In situ hybridization is used to determine the chromosomal map location and the relative order of genes and DNA sequences within a chromosomal band. It can also be used to detect aneuploidy, gene amplification, and subtle chromosomal rearrangements. Fluorescence in situ hybridization (FISH), probably the most widely used method, is described in the first basic protocol. Two support protocols are provided to amplify weak fluorescent signals obtained in FISH. Nonisotopic probes can also be detected by enzymatic reactions using horseradish peroxidase or alkaline phosphatase, as described in alternate protocols. Nonisotopic labeling of DNA probes by nick translation is described in a support protocol. The order of closely spaced FISH probes along chromosomes in interphase nuclei can be determined. A basic protocol for isotopic in situ hybridization (IISH) with 3H is provided followed by a support protocol for preparation of autoradiographic emulsion.
Strategies for Large‐Insert Cloning and Analysis
Authors: Smith Douglas R. , Moir Donald T.
Published: May 2005

This revised introduction provides an up‐to‐date overview of available resources and methods for identifying, mapping, manipulating, and analyzing large‐insert (BAC, YAC, PAC, and P1) clones from the human genome or from other genomes. The table listing available libraries and clone resources has been updated, emphasizing widely used resources that are readily available and that were also used to map and sequence the human genome. Mapping references have been updated, along with links to web sites that provide online access to integrated mapping and sequencing resources. Additional information is included on restriction endonuclease fingerprinting approaches and on transformation‐associated recombination (TAR) cloning methods for rescue of genes or genomic segments from specific cell types or individuals.
An Overview of Spotfire for Gene‐Expression Studies
Authors: Kaushal Deepak , Naeve Clayton W.
Published: May 2005

Spotfire DecisionSite for Functional Genomics (referred to here as Spotfire) is a powerful data mining and visualization application with use in many disciplines. This unit provides an overview of Spotfire's utility in analyzing gene expression data obtained from DNA microarray experiments. Analysis of microarray data requires software‐based solutions able to handle and manipulate the enormous amount of data generated. Spotfire provides a solution for accessing, analyzing and visualizing data generated from microarray experiments. Spotfire is designed to allow biologists with little or no programming or statistical skills to transform, process, and analyze microarray data.
Standardization, Calibration, and Control in Flow Cytometry
Authors: Hoffman Robert A.
Published: May 2005

Because flow cytometers are designed to measure particle characteristics, particles are the most common materials used to calibrate, control, and standardize the instruments. Definitions are provided for common terms to alert the reader to critical distinctions in meaning. The unit presents extensive background on particle types and cautions and goes on to describe practical aspects of methods to standardize and calibrate instruments, in terms of optical alignment, fluorescence and light scatter resolution, and sensitivity. Finally, suggestions follow for analyzing particles used for calibration.
Multiparameter Analysis of Intracellular Phosphoepitopes in Immunophenotyped Cell Populations by Flow Cytometry
Authors: Perez Omar D. , Mitchell Dennis , Campos Roberto , Gao Guo‐Jian , Li Li , Nolan Garry P.
Published: May 2005

This unit presents protocols for measuring intracellular phosphoepitopes by flow cytometry for biochemical investigations in both human and murine primary cells as well as in cell lines. Conventional methods that require cellular lysis cannot discriminate between proteins from different cellular subsets. Intracellular detection of phosphorylated and nonphosphorylated signaling molecules, on the other hand, has recently exposed the heterogeneity that can be observed upon signal transduction. Although staining methodologies for cytokines and cell cycle antigens have been appreciated for years, detection of phosphorylated molecules presents several new challenges, including generation of reagents and details of the staining technique. As these techniques are adapted to new applications, the protocols continue to be refined. This unit describes signal amplification of intracellular signals upon detergent‐based permeabilizations, staining protocol for adherent cells, methodology for whole‐blood staining, and multiparameter staining procedures for surface and intracellular antigens.
Output‐feedback co‐ordinated decentralized adaptive tracking: The case of MIMO subsystems with delayed interconnections
Authors: Mirkin Boris M. , Gutman Per‐Olof
Published: May 2005

Exact decentralized output‐feedback Lyapunov‐based designs of direct model reference adaptive control (MRAC) for linear interconnected delay systems with MIMO subsystems are introduced. The design process uses a co‐ordinated decentralized structure of adaptive control with reference model co‐ordination which requires an exchange of signals between the different reference models. It is shown that in the framework of the reference model co‐ordination zero residual tracking error is possible, exactly as in the case with SISO subsystems. We develop decentralized MRAC on the base ofa prioriinformation about only the local subsystems gain frequency matrices without additionala prioriknowledge about the full system gain frequency matrix. To achieve a better adaptation performance we propose proportional, integral time‐delayed adaptation laws. The appropriate Lyapunov–Krasovskii type functional is suggested to design the update mechanism for the controller parameters, and in order to prove stability. Two different adaptive DMRAC schemes are proposed, being the first asymptotic exact zero tracking results for linear interconnected delay systems with MIMO subsystems. Copyright © 2005 John Wiley & Sons, Ltd.
Block Copolymer Nanocomposites: Perspectives for Tailored Functional Materials
Authors: Bockstaller M. R. , Mickiewicz R. A. , Thomas E. L.
Published: May 2005

Heterogeneous materials in which the characteristic length scale of the filler material is in the nanometer range—i.e., nanocomposites—is currently one of the fastest growing areas of materials research. Polymer nanocomposites have expanded beyond the original scope of polymer–nanocrystal dispersions for refractive‐index tuning or clay‐filled homopolymers primarily pursued for mechanical reinforcement, to include a wide range of applications. This article highlights recent research efforts in the field of structure formation in block copolymer‐based nanocomposite materials, and points out opportunities for novel materials based on inclusion of different types of nanoparticles. The use of block copolymers instead of homopolymers as the matrix is shown to afford opportunities for controlling the spatial and orientational distribution of the nanoelements. This, in turn, allows much more sophisticated tailoring of the overall properties of the composite material.
Electrowinning of copper in a lab‐scale squirrel‐cage cell with anion membrane
Authors: Cifuentes L. , Ortiz R. , Casas J. M.
Published: May 2005

This work describes the design and optimization of a laboratory‐scale copper electrowinning cell based on reactive electrodialysis that incorporates a cathode made of copper granules contained in a rotating squirrel‐cage–type enclosure. It also incorporates the Fe2+ → Fe3+ + e anodic reaction to overcome the principal disadvantages of conventional electrowinning technology. With this design, anolyte (aqueous FeSO4 + H2SO4) and catholyte (aqueous CuSO4 + H2SO4) are kept separate by an anion membrane that prevents cation transport between the electrolytes. Experiments were carried out to characterize cell performance under various conditions, and results show that energy requirements with this cell can be 25% lower than conventional industrial values. The same results also show that the squirrel‐cage cell can be used to electrowin copper from impoverished electrolytes. © 2005 American Institute of Chemical Engineers AIChE J, 2005
Cavitation in creeping shear flows
Authors: Kottke Peter A. , Bair Scott S. , Winer Ward O.
Published: May 2005

Liquid failure has been observed in low Reynolds number (Stokes) shear flows where reduction of the hydrodynamic pressure should not occur. Cavitation in Stokes flows has implications in lubrication, polymer processing, and rheological measurements. Such cavitation can be predicted by a principal normal stress cavitation criterion (PNSCC). We present results of a direct experimental test of the PNSCC. Imaging of the cavitation events suggests that the cavitation is gaseous and originates from preexisting nuclei. Crevice‐stabilized gas nuclei are assumed, and numerical simulations are used to investigate the cavitation event for a Newtonian liquid. The inception of cavitation from a preexisting nucleus, the persistence of suitable nuclei, and the growth and deformation of shed bubbles are considered. © 2005 American Institute of Chemical Engineers AIChE J, 2005
Local liquid holdups and hysteresis in a 2‐D packed bed using X‐ray radiography
Authors: Basavaraj M. G. , Gupta G. S. , Naveen K. , Rudolph V. , Bali R.
Published: May 2005

An X‐ray visualization technique has been used for the quantitative determination of local liquid holdups distribution and liquid holdup hysteresis in a nonwetting two‐dimensional (2‐D) packed bed. A medical diagnostic X‐ray unit has been used to image the local holdups in a 2‐D cold model having a random packing of expanded polystyrene beads. An aqueous barium chloride solution was used as a fluid to achieve good contrast on X‐ray images. To quantify the local liquid holdup, a simple calibration technique has been developed that can be used for most of the radiological methods such as gamma ray and neutron radiography. The global value of total liquid holdup, obtained by X‐ray method, has been compared with two conventional methods: drainage and tracer response. The X‐ray technique, after validation, has been used to visualize and quantify the liquid hysteresis phenomena in a packed bed. The liquid flows in preferred paths or channels that carry droplets/rivulets of increasing size and number as the liquid flow rate is increased. When the flow is reduced, these paths are retained and the higher liquid holdup that persists in these regions leads to the holdup hysteresis effect. Holdup in some regions of the packed bed may be an order of magnitude higher than average at a particular flow rate. © 2005 American Institute of Chemical Engineers AIChE J, 2005
Gas absorption in a wetted‐wire column
Authors: Migita Hirofumi , Soga Kohei , Mori Yasuhiko H.
Published: May 2005

This study aims to examine the performance, as a gas absorber, of a “wetted‐wire column,” a novel gas–liquid contact device equipped with a bundle of built‐in vertically oriented wires. This device allows a liquid absorbent to flow down each wire, being in contact with a gas mixture flowing countercurrently. A prototype column having 109 wires was constructed and then tested in experimental CO2‐absorption operations, using aqueous monoethanolamine absorbents. In every operation, a monoethanolamine solution was supplied to the column at a constant rate such that its flow on each wire assumed a “string‐of‐beads” pattern consisting of annular thin liquid films sheathing the wire and teardrop‐shaped liquid beads alternately aligned on the wire at regular intervals. It was confirmed that the wetted‐wire column has an absorption performance quite comparable to conventional packed‐bed columns, while it imposes, on the internal gas flow, only a pressure loss smaller than that in packed‐bed columns of the same height by one to two orders. © 2005 American Institute of Chemical Engineers AIChE J, 2005
Gas–liquid catalytic hydrogenation reaction in small catalyst channel
Authors: Liu Wei , Roy Shantanu , Fu Xiaodong
Published: May 2005

A study is presented on the performance potential of gas–liquid–solid multiphase catalytic reactions in small‐size structured catalyst/reactor channels. A hydrogenation reaction is performed over the Ni/alumina monolith catalyst module with a model feed consisting of styrene, 1‐octene, and toluene. The gas/liquid feed stream is directly delivered into a single, representative channel of the multichannel monolith catalyst module to eliminate any flow distribution problem. The reaction tests are conducted with different channel sizes, wall structures, and feed compositions. The cocurrent downflow operation is compared to the cocurrent upflow. The olefin hydrogenation reaction is found to be severely limited by mass‐transfer rates. Because of intensified mass transfer inside the small catalyst channel, substantial olefin conversion (>50%) is achieved even at unconventionally high LHSV (∼2000 v/v/h). Liquid and gas superficial linear velocities were varied over a wide range (UL = 1–50 cm/s, UG = 1–2000 cm/s) to elucidate effects of possibly different flow regimes on the reaction performance. The mass‐transfer rate constant of liquid reactant from bulk fluid onto the channel surface in a 1‐mm reaction channel is found to be related to the flow conditions by a simple equation, akLS (1/s) = 0.094(UL + 0.1UG)0.788. The mass‐transfer equation is useful for selection of suitable flow conditions for a given catalytic reaction rate. © 2005 American Institute of Chemical Engineers AIChE J, 2005
Possibility for neurogenesis in substantia nigra of parkinsonian brain
Authors: Yoshimi Kenji , Ren Yong‐Ri , Seki Tatsunori , Yamada Masanori , Ooizumi Hideki , Onodera Masafumi , Saito Yuko , Murayama Shigeo , Okano Hideyuki , Mizuno Yoshikuni , Mochizuki Hideki
Published: May 2005

Recent studies of enhanced hippocampal neurogenesis by antidepressants suggest enhancement of neurogenesis is a potentially effective therapy in neurodegenerative diseases. In this study, we evaluated nigral neurogenesis in animals and autopsy brains including patients with Parkinson's disease (PD). First, proliferating cells in substantia nigra were labeled with retroviral transduction of green fluorescent protein, which is an efficient method to label neuronal stem cells. Subsequent differentiation of labeled cells was followed; many transduced cells became microglia, but no differentiation into tyrosine hydroxylase–positive neurons was detected at 4 weeks after injection, in both intact rodents and those treated with 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine. Second, polysialic acid (PSA)–like immunoreactivity, indicative of newly differentiated neurons, was detected in the substantia nigra of rodent, primate, and human midbrains. A large number of PSA‐positive cells were detected in the substantia nigra pars reticulata of some patients with PD. In rats and a macaque monkey, the dopamine‐depleted hemispheres showed more PSA staining than the intact side. A small number of tyrosine hydroxylase–positive cells were PSA‐positive. Our results suggest enhanced neural reconstruction in PD, which may be important in the design of new therapies against the progression of PD. Ann Neurol 2005
Functional anatomy of the basal ganglia in X‐linked recessive dystonia‐parkinsonism
Authors: Goto Satoshi , Lee Lillian V. , Munoz Edwin L. , Tooyama Ikuo , Tamiya Gen , Makino Satoshi , Ando Satoshi , Dantes Marita B. , Yamada Kazumichi , Matsumoto Sadayuki , Shimazu Hideki , Kuratsu Jun‐Ichi , Hirano Asao , Kaji Ryuji
Published: May 2005

Dystonia is a neurological syndrome characterized by sustained muscle contractions that produce repetitive twisting movements or abnormal postures. X‐linked recessive dystonia parkinsonism (XDP; DYT3; Lubag) is an adult‐onset disorder that manifests severe and progressive dystonia with a high frequency of generalization. In search for the anatomical basis for dystonia, we performed postmortem analyses of the functional anatomy of the basal ganglia based on the striatal compartments (ie, the striosomes and the matrix compartment) in XDP. Here, we provide anatomopathological evidence that, in the XDP neostriatum, the matrix compartment is relatively spared in a unique fashion, whereas the striosomes are severely depleted. We also document that there is a differential loss of striatal neuron subclasses in XDP. In view of the three‐pathway basal ganglia model, we postulate that the disproportionate involvement of neostriatal compartments and their efferent projections may underlie the manifestation of dystonia in patients with XDP. This study is the first to our knowledge to show specific basal ganglia pathology that could explain the genesis of dystonia in human heredodegenerative movement disorders, suggesting that dystonia may result from an imbalance in the activity between the striosomal and matrix‐based pathways. Ann Neurol 2005
A PD‐1 polymorphism is associated with disease progression in multiple sclerosis
Authors: Kroner Antje , Mehling Matthias , Hemmer Bernhard , Rieckmann Peter , Toyka Klaus V. , Mäurer Mathias , Wiendl Heinz
Published: May 2005

T cells are considered to play a pivotal role in orchestrating the self‐reactive immune responses in multiple sclerosis (MS). Programmed death 1 (PD‐1) is a member of the B7/CD28 superfamily of costimulatory molecules exerting inhibitory functions on T cells. Recently, an intronic 7146G/A polymorphism within the PD‐1 gene was described and suggested to be associated with autoimmunity. We investigated whether this genetic polymorphism is a genetic modifier for risk and progression of MS. Blood samples from 939 German MS patients (mean age, 39 years; range, 13–71; 566 patients [60%] with relapsing‐remitting MS, 279 (30%) with secondary, and 94 (10%) with primary progressive MS) and 272 healthy white controls were tested. Genotyping was performed by polymerase chain reaction and restriction enzyme digestion; results were confirmed by automatic sequencing. A significant association of the mutated allele with a progressive disease course was detected (44% 7146G vs 56% 7146A, χ2 p = 0.002). Consequences of the PD‐1 mutation for T‐cell function were assessed ex vivo in some patients using microsphere‐stimulated peripheral blood lymphocytes and purified CD4 cells. Importantly, PD‐1–mediated inhibition of T‐cell cytokine secretion (interferon‐γ) is impaired in patients carrying the PD‐1 polymorphism. In conclusion, our data suggest that PD‐1 polymorphism is a genetic modifier of the progression of MS, possibly through inducing a partial defect in PD‐1–mediated inhibition of T‐cell activation. Ann Neurol 2005
Isothermal crystallization of poly(ethylene‐co‐glycidyl methacrylate)/clay nanocomposites
Authors: Huang Jiann‐Wen , Kang Chiun‐Chia , Chen Tse‐Hsin
Published: May 2005

Poly(ethylene‐co‐glycidyl methacrylate) (PEGMA)/clay nanocomposites with clay concentrations of 1, 3, or 5 wt % were prepared via y melt blending in a twin‐screw extruder. Wide‐angle X‐ray diffraction showed that the clay layers were intercalated by PEGMA. Differential scanning calorimetry was used to analyze the isothermal crystallization, and the equilibrium melting temperature was determined with the Hoffman–Weeks method. The Avrami, Tobin, Malkin, and Urbanovici–Segal models were applied to describe the kinetics of crystallization from the melt state under isothermal conditions. The crystallization kinetics showed that the addition of clay facilitated the crystallization of PEGMA, with the clay functioning as a heterophase nucleating agent; at higher concentrations, however, the physical hindrance of the clay layers to the motion of PEGMA chains retarded the crystallization process. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1051–1064, 2005
New composite systems on the base of polyethylene porous films covered by polypyrrole and polyacrylic acid
Authors: Elyashevich G. K. , Rosova E. Yu. , Andreeva D. V. , Polotskaya G. A. , Trchová M. , Pientka Z.
Published: May 2005

New composite systems were prepared by deposition of conducting polymer (polypyrrole) and polyacrylic acid onto polyethylene porous support. Polypyrrole layers were formed by oxidative polymerization from the gas phase of the monomer, and the layers of polyacrylic acid were deposited from a water solution. Morphology of the systems was studied by atomic force microscopy. Measurements of density, electric, and mechanical characteristics of composites were carried out. The interactions between components of systems were investigated by IR spectroscopy. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1410–1417, 2005
Rice husk–polyester composites: The effect of chemical modification of rice husk on the mechanical and dimensional stability properties
Authors: Rozman H. D. , Musa L. , Abubakar A.
Published: May 2005

Rice husk was used as filler in the production of rice husk (RH)–polyester composites and was subjected to three types of chemical modification. The chemical reagents employed in this study were glycidyl methacrylate (GMA), maleic anhydride (MAH), and succinic anhydride (SAH). This study revealed that the chemical modification of RH with GMA and MAH resulted in the enhancements of tensile and flexural properties of RH–polyester composites. The reduction in these properties with respect to those modified with SAH were attributed to the absence of CC unsaturated groups. Water immersion test showed that chemical modification of the RH improved the dimensional stability of the composites. This was shown in the GMA‐ and MAH‐modified RH–polyester composites. The modification increased the hydrophobicity as well as the crosslinking between the RH and matrix in the composites. The lower performance demonstrated by the SAH‐modified composites was due to the inability of the SAH to form crosslinking with the matrix. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1237–1247, 2005
Proton‐exchange membranes via the grafting of styrene and acrylic acid onto fluorinated ethylene propylene copolymer by a preirradiation technique. IV. Dynamic mechanical analysis, X‐ray diffraction, and scanning electron microscopy studies of grafted and sulfonated membranes
Authors: Phadnis S. , Patri M. , Chakraborty B. C. , Singh P. K. , Deb P. C.
Published: May 2005

The grafting of styrene and acrylic acid onto fluorinated ethylene propylene copolymer was carried out by a preirradiation technique. The resulting membranes were sulfonated with concentrated sulfuric acid. The effects of the degree of grafting and sulfonation on the structure of the membranes were studied by X‐ray diffraction and scanning electron microscopy. The crystallinity percentage decreased with increasing grafting. Scanning electron microscopy studies confirmed that grafting took place by a front mechanism, by which grafting started at the surface and slowly proceeded inwards. The dynamic mechanical properties of the membranes and their sulfonated derivatives were also investigated. The storage modulus at room temperature increased with grafting and increased further with sulfonation. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1426–1431, 2005
Effect of poly(ethylene glycol) on the hydrophobic interactions and rheology of proanthocyanidin biopolymers from Pinus radiata
Authors: Sarathchandra W. D. , Mainwaring D. E.
Published: May 2005

The rheology of solutions of extracts from the bark of Pinus radiata was investigated in the presence of poly(ethylene glycol)s (PEGs) of different molecular weights. PEG with a molecular weight of 4600 (1% w/w) was sufficient to reduce the viscosity of a concentrated (40% w/w) pine tannin extract by one order of magnitude. The reduction of the viscosity was due to the inhibition of molecular association via hydrogen bonding and hydrophobic interactions between tannin and PEG and depended on the molecular weight of PEG. PEG effectively reduced the viscosity of polyphenolic tannins but retained high reactivity toward paraformaldehyde for adhesive formulations. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1254–1260, 2005