bluuebunny/crossref_metadata_2025 huggingface dataset:
Transient dopant segregation and precipitation in yttrium-doped alumina
Authors: Gülgün Mehmet A. , Šturm Sašo , Cannon Rowland M. , Rühle Manfred
Published: February 2009

Ultra-pure AI2O3 ceramics doped with 2000 ppm of Y2O3 were sintered at 1500 °C or 1650 °C for 2 or 12 h. The re-sulting microstructure consisted of alumina matrix grains and second-phase precipitates. Y-doped alumina samples sintered at 1550 °C for shorter times (<2 h) contained primarily YAIO3-YAP precipitates. This is in contradiction of the binary equilibrium phase diagram for AI2O3 and Y2O3, which predicts Y3AI5O12- YAG to be the first phase to appear, as the Y-concentration exceeds the solubility limit of α-A12O3. The formation of YAG in co-existence with the YAP precipitates was observed in samples sintered at 1550°C for 12h and 1650°C for 2 h. The excess of yttrium in the grain boundary was 5.5 ± 0.9 Y-atoms/nm2 for the specimen containing primarily YAP and 4.2 ± 1.2 Y-atoms/nm2 in samples where YAP and YAG co-existed. The study demonstrates that in samples containing multiple precipitates, the grain-boundary excess concentration of Y atoms is controlled by the composition of the precipitates.
A study of phase equilibria in the Al-rich part of the Al-Mn alloy system
Authors: Grushko Benjamin , Balanetskyy Sergiy
Published: February 2009

Following new findings by Y. Du et al. (Int. J. Mater. Res. 98 (2007) 855), the Al-Mn phase diagram was re-examined in the compositional range of ∼4 to 27 at.% Mn using scanning and transmission electron microscopy, energy-dispersive X-ray analysis and differential thermal analysis. The corrections to the Al-Mn phase diagram concerning the reactions involving the Al6Mn and Al4Mn phases reported in the above-mentioned contribution were not confirmed. Instead, our results were in agreement with those reported earlier by Murray et al. (Metall. Trans. A18 (1987) 385): the reaction Al6Mn + μ ↔ λ occurs at 695 °C, and L + μ ↔ Al6Mn at 705 °C. At higher Al concentrations, the reactions μ ↔ L + T, μ + v ↔ T and T ↔ L + γ1 were revealed at ∼923, 913°C and 1001 °C, respectively, in good agreement with the literature data.

Kinetic effects during phase transitions of the Al-Mn alloys are discussed on the basis of experimental results.
Interpretation of inorganic melts' surface properties on the basis of chemical status and structural relations
Authors: Dudek Rostislav , Dobrovsky Ludovit , Dobrovskâ Jana
Published: February 2009

This article is devoted to experimental investigation of the influence of chemical composition on surface properties of inorganic oxidic systems. Through its contents it belongs to a broader area of investigation of systems that form a basis of refining metallurgical slags. The experiment itself was realised on equipment using the sessile drop method modified for high temperatures. The results were compared with theoretical concepts about intrinsic structural relations in melts. Due to the occurrence of anomalies in the temperature dependence of surface tension in the systems investigated and ensuing disagreement with theories, we have used high-temperature X-ray phase analysis. This analysis determined precipitation of individual phases during thermal load and added information for theoretical exploration and consideration about physico-chemical properties of melts working only with binary or ternary systems.
Modeling of the hot deformation behavior of boron microalloyed steels under uniaxial hot-compression conditions
Authors: Mejia Ignacio , López-Chipres Edgar , Maldonado Cuauhtemoc , Bedolla-Jacuinde Arnoldo , Cabrera José Maria
Published: February 2009

The present study shows that the hot deformation behavior of boron microalloyed steels can be quantitatively described by constitutive equations. These equations take into account both dynamic recovery and recrystallization phenomena. They have been fitted using experimental data taken from hot compression tests of four boron microalloyed steels in order to determine their characteristic parameters. The tests were carried out over a wide range of temperatures (950, 1000, 1050 and 1100°C) and strain rates (10−3, 10−2 and 10−1 s−1). The analysis of the characteristic parameters of the constitutive equations describing the hot flow behavior of these steels shows that boron additions play a major role in softening mechanisms rather than on hardening. A quantification of the boron effect is also presented. The experimental data were compared with the predictions of the proposed model and an excellent agreement between measured and predicted values for all boron micro-alloyed steels over a wide range of temperatures and strain rates was obtained.
Thermodynamic description of the C-Fe-Mn system with key experiments and its practical applications
Authors: Zhang Lijun , Du Yong , Chen Qing , Xu Honghui , Zheng Feng , Tang Chengying , Chen Hailin
Published: February 2009

Based on the critically reviewed experimental data available in the literature, new phase transition temperatures and phase equilibria at 800 °C close to the Cu-Fe side of the Cu-Fe-Mn system were measured in the present work. The composition-invariant (γFe, γMn) → (αFe) massive transformations were observed in the two quenched alloys in the Fe-rich region. A set of consistent thermodynamic parameters of the Cu-Fe-Mn system was then obtained by taking into account all kinds of experimental data. Comparisons between the calculated and measured phase diagrams indicate that most of the experimental information is satisfactorily described by the present thermodynamic modeling. The liquidus isolines, liquidus projection and reaction scheme of this ternary system are also presented. Significant improvements have been made, compared with the previous assessments. The presently obtained parameters were applied in successfully solving the !surface fissure" during hot rolling of steel and controlling the micro-structure of the Cu-Fe based alloys in rapid solidification.
The effect of pre-structure process on magnetorheological elastomer performance
Authors: Li Jianfeng , Gong Xinglong , Xu ZhenBang , Jiang Wanquan
Published: February 2009

On fabricating magnetorheolgoical elastomer, the mixture of iron particles and un-vulcanized rubber is placed under a curing magnetic field for some time so that iron particles are driven by the magnetic force to form a columnar structure; this process is called the pre-structure process. The microstructure of a magnetorheological elastomer sample is influenced by the pre-structure process, however, few reports address this problem in detail. This paper aims to study the effect of the pre-structure process on the magnetorheological elastomer performance. The pre-structure process is dominated by three influencing factors: magnetic field, curing time and temperature. A variety of magnetorheological elastomer samples were fabricated under different pre-structure conditions and their shear moduli were measured by using a dynamic mechanics analyzer machine. Scanning electron microscope images of these samples were also taken. The results demonstrated the magnetic field-induced modulus shows an increasing trend with magnetic strength before the magnetorheological elastomer samples reach magnetic saturation. The relative magnetorheological effect has an optimal value when the pre-structure field is 110 mT. The effects of the pre-structure time and temperature on the magnetorheological effect were also addressed by using the optimal pre-structure field. These three pre-structure conditions also affect each other. Thus, to fabricate higher-performance magnetorheological elastomer, these pre-structure conditions should be optimized. These results were also explained by study of the particle motion within the matrix.
Corrosion protective double layer hard coatings
Authors: Afshari N. , Novinrooz A. J.
Published: February 2009

A Cr + TiN double layer was coated on an SS-420 substrate using a hollow cathode discharge gun. The compositional analysis of the samples carried out by glow discharge optical emission spectroscopy confirmed the Cr/TiN constituents. X-ray diffraction pattern studies showed that due to the presence of chromium in the TiN matrix, preferential growth of TiN was changed from (200) to (111) reflection plane, leading to formation of a Cr + TiN double layer hard composite. However, at the same time, the hard coating layers exhibited unavoidable defects exposing them to corrosive environments. In this work, the corrosion protective behaviour of the Cr + TiN double layer was examined by potentiodynamic measurements in sodium chloride solution. It was inferred from this study that the increase in corrosion potential from −505 mV to −452 mV corresponding to the bare substrate and Cr + TiN coatings, respectively, led to the formation of more corrosion protective layers. The electrochemical impedance spectra analysis of the SS-420 substrate, TiN and Cr + TiN layers revealed that corrosion resistance increased and the electrochemical impedance of the Cr + TiN layer decreased. This is attributed to the corrosion protective properties of the resultant coating and its reduced permeability to the corrosive environment.
Reassessment of the Ni–B system supported by key experiments and first-principles calculation
Authors: Sun Wei-Hua , Du Yong , Kong Yi , Xu Hong-Hui , Xiong Wei , Liu Shu-Hong
Published: February 2009

The Ni – B system is reassessed based on critical literature review and the results of key experiments and first-principles calculation. Eight Ni – B alloys are prepared by arc melting the pure elements. The samples are analyzed by means of chemical analysis, X-ray diffraction and differential thermal analysis. NiB12 and NiB2 are not found in the equilibrium condition. Four invariant temperatures are measured: 1098 ± 2 °C for L ↔ fcc(Ni) + Ni3B, 1114 ± 2 °C for L ↔ Ni3B + Ni2B, 1025 ± 2 °C for L ↔ Ni2B + orthorhombic-Ni4B3 and 1044 ± 2 °C for L + βB ↔ NiB. The heat capacity of NiB is determined to be 58.46092 + 0.0012 · T – 1 597 915.59793 · T– 2 (J mol– 1 K– 1, T in Kelvin) in the temperature range from 40 to 950 °C by differential scanning calorimetry. First-principles calculation indicates that the energy of inserting a B atom into the interstitial site of the lattice for Ni atoms is lower than that of substituting for an Ni atom with a B atom. Consequently, the sublattice model (Ni) (B, Va) in which B atoms occupy the interstitial sites is employed for the fcc(Ni) phase rather than the model (Ni, B) (Va) in which B atoms substitute for Ni atoms. In addition, the enthalpies of formation for the five compounds are obtained via first-principles calculation to supplement the modeling. A self-consistent set of thermodynamic parameters for the Ni – B system is finally obtained and the calculated results show good agreement with the experimental data.
Surface tension of liquid binary alloys – theory versus experiment
Authors: Brillo J. , Chatain D. , Egry I.
Published: February 2009

In the present study, we compare available experimental surface tension data with two theoretical concepts: the Butler equation and a multilayer model in which the surface is described as a stacking of atomic layers. The experimental data were measured systematically over a wide temperature and concentration range using electromagnetic levitation and the oscillating drop technique. Three classes of alloys are studied: alloys with rather weak or no segregation, alloys with strong segregation, and associate forming alloys.
The anatomy of the International Journal of Materials Research1 in the light of bibliometry
Authors: Marx Werner
Published: February 2009

Bibliometric methods, in particular citation analysis, are used to evaluate the International Journal of Materials Research (IJMR) and its two predecessor journals Zeitschrift für Metallkunde (ZfM) and Internationale Zeitschrift für Metallographie (IZfM). Firstly, the coverage of the journals by the various literature databases is discussed and the number of articles per year is determined. The time evolution of the publications with respect to German and English as original languages is established and the language dependent impact is analyzed. A ranking of the most important countries of authors is given. Furthermore, the ensemble of ZfM and IJMR articles is analyzed with respect to the occurrence of substances (metals, alloys, compounds) and some subject specific terms (diffusion, microstructure, recrystallization, mechanical properties). A listing of the twenty most frequently cited articles and the citation time evolution (citation history) of the top three articles are presented. Moreover, the distribution of the citations on the articles is determined and the amount of simultaneous citations with other journals (co-citations) is given. The citing papers of the IJMR and ZfM articles are analyzed with respect to the most frequently appearing countries of authors and journals. Finally, the Journal Impact Factor (JIF), the Cited Half-Life and the Citing Half-Life as bibliometric indicators of a journal as a whole are analyzed. The meaning of the widely used JIF is discussed and hints for its careful and cautious use are given.
Verhakungen, dislocations, solitons, and kinks
Authors: Seeger Alfred
Published: February 2009

The paper retraces, from a personal viewpoint, the development of atomistic models of dislocations in crystals from the model of Prandtl, Dehlinger, Frenkel, and Kontorova, first conceived in 1912, to recent work on kinks in dislocations. Among the topics discussed in some detail are the emergence of the theory of solitons, the rate theory of kink-pair generation, and the interplay of experiment and theory in the quantitative investigation of kinks by mechanical relaxation and flow-stress measurements. An outcome of this interplay, the determination of the planes of the elementary slip steps of screw dislocations in refractory body-centred cubic metals, has become the ‘open sesame!’ of quite a number of puzzling phenomena in which the plastic deformation of bcc metals differs from that of fcc metals and alloys. These phenomena include non-uniformities in the flow-stress – temperature relationship, anomalous slip, tension – compression asymmetry in uniaxial straining tests, alloy softening, and the enigma of ‘reversible’ vs. ‘irreversible’ γ-relaxation. The key for their understanding is a first-order transition transforming the cores of a0<111>/2 screw dislocations from a low-temperature configuration capable of slipping on {110} planes to a configuration with a {112} slip plane at elevated temperatures. Various problems needing further research are pointed out.
Study on Warpage Behavior and Filler Orientation during Injection Molding
Authors: Michii T. , Seto M. , Yamabe M. , Kubota Y. , Aoki G. , Ohtsuka H.
Published: February 2009

In this study, the warping mechanism was examined in terms of the difference in warpage behavior due to the presence or absence of fiber filler, using a ribbed plate. It was found that the warping mechanism due to anisotropic shrinkage is caused by the filler orientation distribution and filler form, including its size and geometry. It is seen that the sensitivity (the effect of the rib thickness on the amount of warpage) increased as the glass flake content was increased in PBT-hybrid filler. From this result, the glass flake used in this study were sufficiently small and that aspect ratio was approximately 2 compared with the glass fiber (aspect ratio: 10 ∼ 20). It can be inferred therefore that the glass flake acted like spherical filler, which contributed to reducing the anisotropic shrinkage.
Effect of Compatibilizer on Morphology and Mechanical Properties of SAN/EPDM Blends
Authors: Ptiček A. , Hrnjak-Murgić Z. , Jelenčić J.
Published: February 2009

Miscibility of styrene-acrylonitrile (SAN) and ethylene-propylene-diene (EPDM) blends containing high impact polystyrene (HIPS) as a compatibilizer were studied. Blends were characterized by determination of mechanical properties, glass transition temperatures and their morphology was inspected by scanning electronic microscopy. Blends were separated into components to clarify the effects of the extrusion process and the obtained components were characterized by FTIR spectroscopy and by gel permeation chromatography. It was observed that significant fraction of in situ formed graft copolymer is formed during extrusion, which contributes to the homogeneity of the studied systems. The results show finer morphology and size reduction of the dispersed phase due to enhanced interface adhesion in compatibilized blends, with enhanced mechanical properties.
Effect of Electric Current on Beads Formation in Electrospinning of Poly(Vinyl Alcohol)
Authors: Kadomae Y. , Amagasa M. , Sugimoto M. , Taniguchi T. , Koyama K.
Published: February 2009

We investigate effects of electric current on formations of beads in electrospinning by changing an electric conductivity of a poly(vinyl alcohol) (PVA) aqueous solution and spinning conditions, such as applied voltage, distance between a tip of needle and a collector, and relative humidity. From the results of experiments done by changing the conductivity of PVA aqueous solution and spinning conditions, we found that a beads formation is suppressed at a lower electric current. Furthermore, when the electrospinnings are performed at a certain constant electric current in various spinning conditions where the applied voltage and tip-collector distance are changed so as to give the same constant electric current, resultant PVA fibers have no beads and almost the same distribution of fiber diameter.
Ultrasound Assisted Single Screw Extrusion Process for Dispersion of Carbon Nanofibers in Polymers
Authors: Isayev A. I. , Jung C. , Gunes K. , Kumar R.
Published: February 2009

A novel method for the continuous dispersion of carbon nanofibers (CNFs) in a polymer matrix for manufacturing high performance nanocomposites was developed using an ultrasonically assisted single screw extrusion process. The effect of ultrasound on die pressure, electrical and thermal conductivity, rheological, morphological and mechanical properties of polyetherimide (PEI) filled with 1 to 20 wt.% CNFs was studied. A reduction in the die pressure and percolation threshold of CNF/PEI nanocomposites with a permanent increase in the viscosity and a permanent decrease in tan δ was achieved through ultrasonic treatment. Morphological studies of the treated nanocomposites revealed their improved homogeneity leading to an increase of the Young's modulus and electrical and thermal conductivity.
A Comparison of Statistical Process Control (SPC) and On-Line Multivariate Analyses (MVA) for Injection Molding
Authors: Kazmer D. O. , Westerdale S. , Hazen D.
Published: February 2009

Manufacturing process automation is often impeded by limitations related to automatic quality assurance. Many plastics manufacturers use univariate statistical process control (SPC) for quality control by charting the critical process states relative to defined control limits. Alternatively, principal component analysis (PCA) and projection to latent stuctures (PLS) are multivariate methods that measure the process variance by the distance to the model (DModX) and the Hotelling t-squared (T2) values. A methodology for robust model development is described to perturb the manufacturing process for process characterization based on a design of experiments; best subset analysis is used to provide an optimal set of regressors for univariate SPC. Four different statistical models were derived from the same data set for a highly instrumented injection molding process. The performance of these models was then assessed with respect to fault diagnosis and defect identification when the molding process was subjected to twelve common process faults. Across two hundred molding cycles, the univariate SPC models correctly diagnosed five of the twelve process faults with one false positive, detecting only eighteen of twenty four defective products while indicating two false positives. With the same molding cycles, PCA and PLS provided nearly identical performance by correctly diagnosing ten of the twelve process faults and detecting twenty three of the twenty four defective products; PCA indicated two false positives while PLS indicated only one false positive.
Potassium Dichromate Induced Cytotoxicity, Genotoxicity and Oxidative Stress in Human Liver Carcinoma (HepG2) Cells
Authors: Patlolla Anita K. , Barnes Constance , Hackett Diahanna , Tchounwou Paul B.
Published: February 2009

Chromium is a widespread industrial waste. The soluble hexavalent chromium Cr (VI) is an environmental contaminant widely recognized to act as a carcinogen, mutagen and teratogen towards humans and animals. The fate of chromium in the environment is dependent on its oxidation state. Hexavalent chromium primarily enters the cells and undergoes metabolic reduction to trivalent chromium, resulting in the formation of reactive oxygen species together with oxidative tissue damage and a cascade of cellular events. However, the results from in vitro studies are often conflicting. The aim of this study was to develop a model to establish relationships between cytotoxicity, genotoxicity and oxidative stress, in human liver carcinoma [HepG2] cells exposed to potassium dichromate. HepG2 cells were cultured following standard protocols and exposed to various concentrations [0-50 µM] of potassium dichromate [K2Cr2O7]. Following exposure to the toxic metal, the MTT assay was performed to assess the cytotoxicity, the thiobarbituric acid test to evaluate the degree of lipid peroxidation as an indicator of oxidative stress and the alkaline comet assay was used to assess DNA damage to study genotoxicity. The results of the study indicated that potassium dichromate was cytotoxic to HepG2 cells. The LD50 values of 8.83 ± 0.89 µg/ml, 6.76 ± 0.99 µg/ml, respectively, for cell mortality at 24 and 48 hrs were observed, indicating a dose- and time-dependent response with regard to the cytotoxic effects of potassium dichromate. A statistically significant increase in the concentration of malondialdehyde [MDA], an indicator of lipid peroxidation, was recorded in exposed cells [15.9 – 69.9 µM] compared to control [13 µM]. Similarly, a strong dose-response relationship (p
Selective Binding, Self-Assembly and Nanopatterning of the Creutz-Taube Ion on Surfaces
Authors: Wang Yuliang , Lieberman Marya , Hang Qingling , Bernstein Gary
Published: February 2009

The surface attachment properties of the Creutz-Taube ion, i.e., [(NH3)5Ru(pyrazine)Ru(NH3)5]5+, on both hydrophilic and hydrophobic types of surfaces were investigated using X-ray photoelectron spectroscopy (XPS). The results indicated that the Creutz-Taube ions only bound to hydrophilic surfaces, such as SiO2 and –OH terminated organic SAMs on gold substrates. No attachment of the ions on hydrophobic surfaces such as –CH3 terminated organic SAMs and poly(methylmethacrylate) (PMMA) thin films covered gold or SiO2 substrates was observed. Further ellipsometric, atomic force microscopy (AFM) and time-dependent XPS studies suggested that the attached cations could form an inorganic analog of the self-assembled monolayer on SiO2 substrate with a “lying-down” orientation. The strong electrostatic interaction between the highly charged cations and the anionic SiO2 surface was believed to account for these observations. Based on its selective binding property, patterning of wide (~200 nm) and narrow (~35 nm) lines of the Creutz-Taube ions on SiO2 surface were demonstrated through PMMA electron resist masks written by electron beam lithography (EBL).
Developmental adaptation: Where we go from here
Authors: Frisancho A. Roberto
Published: February 2009

The concept of developmental adaptation is a powerful framework that can be used for understanding the origin of population differences in phenotypic and genotypic biological traits. There is great deal of information describing how developmental responses can shape adult biological outcomes. Specifically, current research suggest that individuals developing in stressful environments such as high altitude will attain an adult enlarged residual lung volume that contribute to the successful cardiovascular adaptation of the high‐altitude Andean native. Likewise, studies on the etiology of the metabolic syndrome indicate that development under poor nutritional environments elicit efficient physiological and metabolic responses for the utilization of nutrients and energy, which become disadvantageous when the adult environmental conditions provide abundant access to food and low energy expenditure. Epigenetic research in experimental animals and retrospective research in humans confirm that environmental influences during developmental period have profound consequences on the phenotypic expression of biological and behavioral traits during adulthood. Research on epigenetics is a productive direction for human biologists concerned with understanding the origins of human biological variability. Am. J. Hum. Biol., 2009. © 2009 Wiley‐Liss, Inc.
Neuropsychological attention deficits in tuberous sclerosis complex (TSC)
Authors: de Vries Petrus J. , Gardiner Julian , Bolton Patrick F.
Published: February 2009

Tuberous sclerosis complex (TSC) (OMIM191100) is a genetic disorder with multi‐system involvement including neurodevelopmental manifestations. There is great interest in understanding the pathogenetic mechanisms underlying these neurobehavioral and neurocognitive manifestations. However, there are still significant gaps in knowledge about the exact neuropsychiatric phenotypes observed in TSC. Here we report on the first systematic evaluation of neuropsychological attentional skills in a population‐derived sample of children and adolescents with TSC. The study showed that, even when age, gender, IQ, and intra‐familial clustering were controlled for, the TSC group had significantly lower scores than their unaffected siblings on a range of neuropsychological attentional tasks, and that they had significantly more neuropsychological attention deficits. Eighteen of the 20 children (90%) showed deficits on one or more attentional tasks, with dual task performance most consistently impaired (85%) and visual selective attention a relative strength. Active seizures and anti‐epilepsy medication did not influence attentional profiles. Furthermore, parent rating of attention‐related behaviors were not able to identify children at risk of neuropsychological deficits. The findings suggest that clinical neuropsychological evaluation of attentional skills should be performed in children and adolescents with TSC even when they have normal global intellectual abilities, no seizures, and no disruptive behaviors. Results suggest that the mechanisms underlying these deficits may include contributions from structural, seizure‐related and molecular factors. © 2009 Wiley‐Liss, Inc.
Family risk and related education and counseling needs: Perceptions of adults with bipolar disorder and siblings of adults with bipolar disorder
Authors: Peay H.L. , Hooker G.W. , Kassem L. , Biesecker B.B.
Published: February 2009

Genetics and mental health professionals increasingly provide education and counseling related to risk for psychiatric illness, but there is insufficient evidence about patient perceptions and needs to guide such interventions. Affected individuals and relatives may perceive increased family risk and have interest in genetic education and counseling. Our objectives were to explore perceptions of family vulnerability, perceived control, and coping strategies related to familial risk and needs from genetic counseling. Our methods included conducting semi‐structured interviews (n = 48) with individuals with bipolar disorder (BPD) and unaffected siblings. Content analysis generated descriptive data that provide guidance for clinical interventions and themes to evaluate in future studies. The results showed that participants perceived increased personal and family risk, attributing BPD to genes and family environment. Causal attributions were often uncertain and at times inconsistent. Participants wished to modify psychiatric risk to relatives, but were uncertain how to do so; despite the uncertainty, most parents reported risk‐modification efforts. Efforts to cope with family vulnerability included monitoring and cognitive distancing. Participants endorsed the usefulness of education and psychological support, but described more ambivalence about receiving risk assessment. Educational and supportive interventions around family risk for BPD should focus on perceptions of cause and vulnerability, reproductive decision‐making, and early intervention and risk modification in young relatives. Psychological support is an important component. Providers should evaluate patient coping strategies, which could facilitate or hinder genetic counseling interventions, and should not assume interest in quantitative risk assessment. Published 2009 Wiley‐Liss, Inc.
Influence of granulometry and organic treatment of a Brazilian montmorillonite on the properties of poly(styrene‐co‐n‐butyl acrylate)/layered silicate nanocomposites prepared by miniemulsion polymerization
Authors: Moraes Raul P. , Valera Ticiane S. , Demarquette Nicole R. , Oliveira Pedro C. , da Silva Maria Lúcia C.P. , Santos Amilton M.
Published: February 2009

The influence of granulometry and organic treatment of a Brazilian montmorillonite (MMT) clay on the synthesis and properties of poly(styrene‐co‐n‐butyl acrylate)/layered silicate nanocomposites was studied. Hybrid latexes of poly(styrene‐co‐butyl acrylate)/MMT were synthesized via miniemulsion polymerization using either sodium or organically modified MMT. Five clay granulometries ranging from clay particles smaller than 75 μm to colloidal size were selected. The size of the clay particles was evaluated by specific surface area measurements (BET). Cetyl trimethyl ammonium chloride was used as an organic modifier to enhance the clay compatibility with the monomer phase before polymerization and to improve the clay distribution and dispersion within the polymeric matrix after polymerization. The sodium and organically modified natural clays as well as the composites were characterized by X‐ray diffraction analysis. The latexes were characterized by dynamic light scattering. The mechanical, thermal, and rheological properties of the composites obtained were characterized by dynamical‐mechanical analysis, thermogravimetry, and small amplitude oscillatory shear tests, respectively. The results showed that smaller the size of the organically modified MMT, the higher the degree of exfoliation of nanoplatelets. Hybrid latexes in presence of Na‐MMT resulted in materials with intercalated structures. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Improving the hydrophilic properties of wool fabrics via corona discharge and hydrogen peroxide treatment
Authors: Wang Xin , Cao Genyang , Xu Weilin
Published: February 2009

Corona discharge has been widely applied to modify the surfaces of polymers. In this study, corona discharge was combined with a hydrogen peroxide treatment to improve the hydrophilic properties of wool fabric. Scanning electron microscopy photographs showed that the tip of wool scales was etched after corona discharge and that parts of the scales were peeled off after the hydrogen peroxide treatment. The surface hydrophilic properties of the wool fabric were improved greatly by corona discharge. Increases in the discharge voltage and the number of treatment passages enhanced the hydrophilic properties dramatically, but the improved properties deteriorated with increases in the number of washing cycles and storage time. The hydrogen peroxide treatment could improve the hydrophilic properties and especially the wicking properties of the wool fabric. The fabric became weaker and flexible with an average weight loss of 3% after the hydrogen peroxide treatment. A combination of corona discharge treatment and the hydrogen peroxide treatment made the wool fabric absolutely hydrophilic; the water penetration time of the treated fabric was less than 1 s even when the fabric was washed for several cycles or stored for 6 months. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and properties of soy hull‐reinforced biocomposites from conjugated soybean oil
Authors: Quirino Rafael L. , Larock Richard C.
Published: February 2009

The tensile and flexural properties of new thermosetting composites made by the free radical polymerization of a conjugated soybean oil (CSO)‐based resin reinforced with soy hulls have been determined for various resin compositions. The effects of reinforcement particle size and filler/resin ratio have been assessed. The thermal stability of the new materials has been determined by thermogravimetric analysis and the wt % of oil incorporation has been calculated after Soxhlet extraction (the extracts have been identified by 1H‐NMR spectroscopy). The resin consists initially of 50 wt % CSO and varying amounts of divinylbenzene (DVB; 5–15 wt %), dicyclopentadiene (DCPD; 0–10 wt %), and n‐butyl methacrylate (BMA; 25–35 wt %). Two soy hull particle sizes have been tested (<177 and <425 μm) and two different filler/resin ratios have been compared (50 : 50 and 60 : 40). An appropriate cure sequence has been established by differential scanning calorimetry (DSC) analysis. The results show a decrease in the properties whenever DVB or BMA is substituted by DCPD. Also, larger particle sizes and higher filler/resin ratios are found to have a negative effect on the tensile properties of the new materials. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Dispersion and properties of cellulose nanowhiskers and layered silicates in cellulose acetate butyrate nanocomposites
Authors: Petersson L. , Mathew A. P. , Oksman K.
Published: February 2009

The aim of this work was to develop well dispersed nanocomposites, in a non water soluble polymer using a non aqueous, low polarity solvent as a dispersion medium. The nanoreinforcements were cellulose whiskers and layered silicates (LSs) and matrix was cellulose acetate butyrate (CAB). Before nanocomposite processing, a homogenizer was used in combination with sonification to achieve full dispersion of the nanoreinforcements in a medium of low polarity (ethanol). After processing, the cellulose nanowhiskers (CNW) showed flow birefringence in both ethanol and dissolved CAB, which indicated well dispersed whiskers. The microscopy studies indicated that the processing was successful for both nanocomposites. The CNW showed a homogeneous dispersion on nanoscale. The LS nanocomposite contained areas with lower degree of dispersion and separation of the LS sheets and formed mainly an intercalated structure. The produced materials were completely transparent, which indicated good dispersion. Transparency measurements also indicated that the nanocomposite containing CNW showed similar performance as the pure CAB. Dynamic mechanical thermal analysis (DMTA) showed improved storage modulus for a wide temperature range for both nanocomposites compared with the pure CAB matrix. This study indicated that CNW have a potential application in transparent nanocomposites based on fully renewable resources. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Segregation analysis of cleft lip with or without cleft palate in the First Nations (Amerindian) people of British Columbia and review of isolated cleft palate etiologies
Authors: Lowry R. Brian , Johnson Candice Y. , Gagnon France , Little Julian
Published: February 2009

BACKGROUND: The First Nations (Amerindian) population of British Columbia, Canada, has the highest reported birth prevalence in the world of cleft lip with or without cleft palate (CL/P) at nearly 3 per 1000 births. In addition, a substantial proportion of cleft palate only (CPO) cases in this population has been reported to be X‐linked. The aims of this study were to perform complex segregation analysis to investigate the mode of inheritance of CL/P in the First Nations people of British Columbia and to review the etiology of the CPO cases. METHODS: All First Nations children born in British Columbia between 1952 and 1971 with an orofacial cleft were included in the study. Multiple sources of ascertainment were used, so that nearly 100% of live births were identified and included during this time. No stillbirths were found but would likely have been ascertained. Extended pedigrees were constructed from these probands and examination of immediate family members, e.g., parents and siblings, was done wherever possible. Complex segregation analysis included all family members. In addition, a CPO case review was conducted. RESULTS: Complex segregation analysis supports the hypothesis that the most likely mode of inheritance of CL/P in this population is a mixed model; that is, an autosomal major gene with polygenic component. The review of 26 CPO cases showed that a substantial proportion are syndromic. Birth Defects Research (Part A), 2009. © 2009 Wiley‐Liss, Inc.
Maternal thyroid disease, thyroid medication use, and selected birth defects in the National Birth Defects Prevention Study
Authors: Browne Marilyn L. , Rasmussen Sonja A. , Hoyt Adrienne T. , Waller D. Kim , Druschel Charlotte M. , Caton Alissa R. , Canfield Mark A. , Lin Angela E. , Carmichael Suzan L. , Romitti Paul A.
Published: February 2009

BACKGROUND: Although thyroid disorders are present in approximately 3% of pregnant women, little is known about the association between maternal thyroid disease and birth defects. METHODS: We assessed the association between maternal thyroid disease, thyroid medication use, and 38 types of birth defects among 14,067 cases and 5875 controls in the National Birth Defects Prevention Study, a multisite, population‐based, case‐control study. Infants in this study were born between October 1997 and December 2004. Information on exposures including maternal diseases and use of medications was collected by telephone interview. RESULTS: We found statistically significant associations between maternal thyroid disease and left ventricular outflow tract obstruction heart defects (1.5; 95% CI, 1.0–2.3), hydrocephaly (2.9; 95% CI, 1.6–5.2), hypospadias (1.6; 95% CI, 1.0–2.5), and isolated anorectal atresia (2.4; 95% CI, 1.2–4.6). Estimates for the association between periconceptional use of thyroxine and specific types of birth defects were similar to estimates for any thyroid disease. Given that antithyroid medication use was rare, we could not adequately assess risks for their use for most case groups. CONCLUSIONS: Our results are consistent with the positive associations between maternal thyroid disease or thyroid medication use and both hydrocephaly and hypospadias observed in some previous studies. New associations with left ventricular outflow tract obstruction heart defects and anorectal atresia may be chance findings. Birth Defects Research (Part A), 2009. © 2009 Wiley‐Liss, Inc.
Interaction of PDGFRA promoter haplotypes and maternal environmental exposures in the risk of spina bifida
Authors: Toepoel Mascha , Steegers‐Theunissen Regine P. M. , Ouborg N. Joop , Franke Barbara , Ladd Angela M. González‐Zuloeta , Joosten Paul H. L. J. , van Zoelen Everardus J. J.
Published: February 2009

BACKGROUND: Neural tube defects are multifactorial malformations involving both environmental exposures, such as maternal nutrition, and genetic factors. Aberrant expression of the platelet‐derived growth factor alpha‐receptor (PDGFRA) gene has been implicated in neural‐tube‐defect etiology in both mice and humans. METHODS: We investigated possible interactions between the PDGFRA promoter haplotype of mother and child, as well as maternal glucose, myo‐inositol, and zinc levels, in relation to spina bifida offspring. Distributions were determined of the PDGFRA promoter haplotypes H1 and H2 in a Dutch cohort, consisting of 88 spina bifida children with 56 of their mothers, and 74 control children with 72 of their mothers, as well as maternal plasma glucose, myo‐inositol, and red blood cell zinc concentrations. RESULTS: A significantly higher frequency of H1 was observed in children with spina bifida than in controls (30.1 vs. 20.3%; OR = 1.69, 95% CI 1.02–2.83). High maternal body mass index (BMI) and glucose were significant risk factors for both H1 and H2 children, whereas low myo‐inositol and zinc were risk factors for H2 but not for H1 children. Stepwise multiple logistic regression analysis showed that high maternal glucose and low myo‐inositol are the main risk factors for H2 spina bifida children, whereas for H1 spina bifida children, maternal BMI was the main risk factor. Interestingly, H1 mothers (median 165.5 cm) showed a significantly lower body height than H2 mothers (median 169.1 cm; p = 0.003). CONCLUSIONS: These data suggest that the child's PDGFRA promoter haplotype is differentially sensitive for periconceptional exposure to glucose, myo‐inositol, and zinc in the risk of spina bifida. Birth Defects Research (Part A), 2009. © 2009 Wiley‐Liss, Inc.
Surveillance of urothelial carcinoma
Authors: David Kevin A. , Mallin Katherine , Milowsky Matthew I. , Ritchey Jamie , Carroll Peter R. , Nanus David M.
Published: February 2009

BACKGROUND:

Previous investigators have detected shifts to lower stages at diagnosis for renal cell carcinoma and prostate cancer. The authors investigated whether a similar pattern is seen for urothelial carcinomas of the bladder, ureter, and renal pelvis and sought to identify changes in cancer grade and survival trends from 1993 to 2005.

METHODS:

The National Cancer Data Base (NCDB) collects data on approximately 75% of all newly diagnosed cancer cases annually. The authors queried the database for cases of urothelial carcinomas diagnosed in 1993‐2005 in patients aged 18 years and older. All cancer stage data were forward converted to the sixth edition of the American Joint Committee on Cancer staging definitions.

RESULTS:

A total of 334,480 bladder cancer cases, 15,105 renal pelvis cancer cases, and 10,128 ureteral carcinoma cases were identified. Stage data were available for 84% of bladder cases, 83% of renal pelvis cases, and 82% of ureter cases. With the classification of early stage tumors as stage 0a, 0is, and I and late stage tumors as II, III, and IV, the percentage of early stage renal pelvis and ureter tumors increased slightly from 1993 to 2005, whereas no stage migration was seen in bladder tumors. In looking specifically at early stage tumors, a significant increase in the proportion of stage 0a and a significant decrease in the proportion of stage I tumors for each cancer site was seen between 1993 and 2005. The proportion of high grade tumors in each disease site significantly increased from 1993 to 2005. For cases diagnosed in 1993‐1996 and 1997‐2000, a significant decrease in 5‐year relative survival was observed for patients with stage I and stage II bladder cancer. The absolute change, however, was relatively small, and for bladder cases was not significantly different when adjusted for low or high grade tumors.

CONCLUSIONS:

When differentiating between early and late stage tumors, a slight stage migration was seen in renal pelvis and ureteral carcinomas, whereas no stage migration was seen in bladder tumors. Within early stage tumors of all sites, a stage shift was seen, most notably with the proportion of stage 0a tumors increasing and stage I tumors decreasing. The proportion of high grade tumors in all sites increased. No change in overall survival was observed, underscoring the need for new therapeutic advances. Cancer 2009. © 2009 American Cancer Society.
Clinical application of fuzzy‐controlled blood pressure stabilization in patients prone to hypotension during hemodialysis
Authors: Hickstein Heiko , Stange Jan , Roeher Ottfried , Korth Steffen , Schmidt Reinhard
Published: February 2009

BACKGROUND

The prevalence of intradialytic hypotensive events is still high in patients undergoing hemodialysis (HD). A biofeedback control system to prevent hypotensive destabilization of the patient during hemodialysis was developed.

METHODS

A blood pressure (BP)–guided closed‐loop system consists of a non‐invasive blood pressure measurement device connected to a fuzzy controller (FC). It regulates ultrafiltration rate (UFR) and dialysate conductivity (DC) depending on the actual BP and its short‐ and long‐term trends as well. Twenty‐eight HD patients prone to hypotension were selected for the study. In 102 HD sessions it was proven whether an increase in DC from 14.3 mS/cm to a maximum of 17.0 mS/cm infl uenced the serum sodium concentration of the patients and interdialytic weight gain (IDGW), when DC was reset to 14.3 mS/cm for the remaining 60 minutes of treatment. In the next step, 69 conventional HD sessions without the fuzzy controller and 144 sessions with fuzzy‐controlled ultrafiltration were compared with 32 sessions with simultaneous fuzzy‐controlled ultrafiltration and modification of dialysate conductivity.

RESULTS

No significant differences in serum sodium concentration and weight gain were observed when DC was reset for the remaining 60 minutes of treatment. In conventional HD the frequency of low blood pressure situations, <90 mmHg, increased progressively toward the end of the treatment. The HD treatments with fuzzy‐controlled UFR resulted in no increases in the number of hypotensive episodes. Moreover, there was a significant decrease in the third and fourth treatment hours. The simultaneous fuzzy control of UFR + DC resulted in the lowest occurrence of BP drops.

CONCLUSIONS

Fuzzy control of HD treatments provides reliable blood pressure stabilization in patients prone to hypotension. This kind of treatment is safe because significant changes in body weight and serum sodium concentration do not occur. The cost of this treatment is limited because no special disposables are necessary.
A review of mathematical learning disabilities in children with fragile X syndrome
Authors: Murphy Melissa M.
Published: February 2009

The prevalence rate of mathematical learning disabilities (MLD) among children with fragile X syndrome who do not meet criteria for intellectual and developmental disabilities (∼50% of female children) exceeds the rate reported in the general population. The purpose of this article is two‐fold: (1) to review the findings on MLD in persons with fragile X syndrome; and (2) to discuss fragile X syndrome as a possible model for understanding pathways to MLD. © 2009 Wiley‐Liss, Inc. Dev Disabil Res Rev 2009;15:21–27.
Mathematical learning disabilities in special populations: Phenotypic variation and cross‐disorder comparisons
Authors: Dennis Maureen , Berch Daniel B. , Mazzocco Michèle M.M.
Published: February 2009

What is mathematical learning disability (MLD)? The reviews in this special issue adopt different approaches to defining the construct of MLD. Collectively, they demonstrate the current status of efforts to establish a consensus definition and the challenges faced in this endeavor. In this commentary, we reflect upon the proposed pathways to mathematical learning difficulties and disabilities presented across the reviews. Specifically we consider how each of the reviews contributes to identifying the MLD phenotype by specifying the range of assets and deficits in mathematics, identifying sources of individual variation, and characterizing the natural progression of MLD over the life course. We show how principled comparisons across disorders address issues about the cognitive and behavioral co‐morbidities of MLD, and whether commonalities in brain dysmorphology are associated with common mathematics performance profiles. We project the status of MLD research ten years hence with respect to theoretical gains, advances in methodology, and principled intervention studies. © 2009 Wiley‐Liss, Inc. Dev Disabil Res Rev 2009;15:80–89.