bluuebunny/crossref_metadata_2025 huggingface dataset:
Organic–inorganic hybrid boron‐containing phenol–formaldehyde resin/SiO2 nanocomposites
Authors: Gao Jungang , Jiang Chaojie , Ma Weitao
Published: December 2007

The organic–inorganic hybrid boron‐containing phenol–formaldehyde (BPFR) resin/SiO2 nanocomposites was synthesized in‐situ from boric acid, phenol, and tetramethoxysilane. The structure of BPFR modified and the distributions of silicon element were studied by Fourier‐transform infrared spectroscopy, energy dispersive X‐ray spectrometry, and transmission electron microscope, respectively. The glass transition temperature (Tg) was determined by torsional braid analysis. The results show that silicon element distribution is homogeneous, and the size of nanosilica is about 40–60 nm. The thermal stability and kinetics parameters of thermal degradation were determined by thermogravimetry analysis (TGA). TGA results show that the resin modified has higher heat resistance property when the additive quantity of SiO2 was 3 wt%. The temperature of 5% weight loss is 487.7°C, which is 12.4°C higher than that of common BPFR. The residual ratio of 3 wt% SiO2/BPFR was 62.3% at the temperature of 900°C, which is 11.2% higher than that of common BPFR. The mechanics loss peak Tp of 3% SiO2/BPFR is 33°C higher than common BPFR. Fiberglass‐reinforced BPFR modified by 3 wt% SiO2 has better mechanical and dielectric properties than that of common BPFR. POLYM. COMPOS., 2008. © 2007 Society of Plastics Engineers
Sliding wear and friction characteristics of sisal fibre reinforced polyester composites: Effect of silane coupling agent and applied load
Authors: Chand Navin , Dwivedi U.K.
Published: December 2007

Chopped sisal fibre‐reinforced polyester composites with and without silane modification were prepared. Wear and friction measurements on the chopped sisal fibre reinforced polyester composites have been performed at different loads for different weight percentages of sisal fibre by using a pin‐on‐disc wear and friction tester. It has been found that increase of chopped sisal fibre content increased the Pressure‐Velocity (PV) limit of composites. Silane modification improved the wear resistance of untreated sisal fibre reinforced polyester composite. Coefficient of friction increased with increase of fibre content and decreased with increase of load. Wear mechanism has been discussed with the help of SEM observations. POLYM. COMPOS., 2008. © 2007 Society of Plastics Engineers
Novel biodegradable flame retardant, poly(butyl methacrylate)/sodium silicate/Mg(OH)2 nanocomposite
Authors: Samal Ramakanta , Rana Pradeep K. , Mishra Girija P. , Sahoo Prafulla K.
Published: December 2007

Flame retardant poly(butyl methacrylate)/sodium silicate/Mg(OH)2 (MH) nanocomposite has been prepared via in situ emulsion polymerization of BMA, benzoyl peroxide, layered silicate, and conventional fire retardant additive, MH. The morphology, thermal stability, and flammability properties of the nanocomposite were characterized by IR, XRD, TEM, TGA, cone calorimetry, and limiting oxygen index. The thermal stability and the flame retardant properties of the polymer‐silicate‐MH showed significant improvements in the decomposition temperature and the lower heat release rates due to the formation of nanocomposites with layered silicates. Biodegradation testing by Bacillus cereus (gram‐positive) revealed the ecofriendly nature of the nanocomposite. POLYM. COMPOS., 2008. © 2007 Society of Plastics Engineers
Effect of hygrothermal aging on the diffusion of seawater in epoxy/glass composites studied by positron lifetime spectroscopy
Authors: Radha J.C. , Ranganathaiah C.
Published: December 2007

The effect of hygrothermal aging on the free volume controlled diffusion of seawater in the epoxy/glass (E/G) composite samples with E‐glass fibers woven at 0° and 45° to the epoxy matrix has been studied using Positron lifetime technique. The equilibrium mass uptake of seawater is assessed by the gravimetric method. The positron results indicate that the free volume hole size increases with hygrothermal aging in the composite E/G (0°) suggesting swelling while the hole size shows continuous decrease in the E/G (45°) composite up to 45°C. We also found that hygrothermal aging process in the present composites is an exothermic process. Although the equilibrium uptake of seawater decreases with the increasing temperature in both the cases, the magnitude of decrease is more in 0°‐oriented composite than in 45°‐oriented composite. The heat of absorption calculated from the temperature dependence of equilibrium mass uptake is found to be negative in both the cases. POLYM. COMPOS., 2008. © 2007 Society of Plastics Engineers
Recent developments in chemical modification and characterization of natural fiber‐reinforced composites
Authors: John Maya Jacob , Anandjiwala Rajesh D.
Published: December 2007

A critical review of the literature on the various aspects of natural fibers and biocomposites with a particular reference to chemical modifications is presented in this paper. A notable disadvantage of natural fibers is their polarity which makes it incompatible with hydrophobic matrix. This incompatibility results in poor interfacial bonding between the fibers and the matrix. This in turn leads to impaired mechanical properties of the composites. This defect can be remedied by chemical modification of fibers so as to make it less hydrophilic. This paper reviews the latest trends in chemical modifications and characterizations of natural fibers. The structure and properties of natural fibers have been discussed. Common chemical modifications and their mechanisms have also been elaborated. The importance of chemical modifications and the resultant enhancement in the properties of the composites have also been reviewed. Recent investigations dealing with chemical modifications of natural fiber‐reinforced composites have also been cited. POLYM. COMPOS., 2008. © 2007 Society of Plastics Engineers
Coefficient of thermal expansion for Twaron® fibers using crystallographic data
Authors: Jain Anjana
Published: December 2007

The effect of in situ heating on the unit cell dimensions of crystalline aramid fiber (Twaron® fibers) has been studied in the temperature range 20–280°C. The changes in the unit cell dimensions have been used to estimate the coefficients of thermal expansion along the axial directions. On heating, the a and b axes expand, the coefficients of thermal expansion being αa = 35.84 × 10−6/°C and αb = 38 × 10−6/°C at room temperature. The c‐axis contracts on heating, giving negative coefficient of thermal expansion αc = −5.38 × 10−6/°C at room temperature. Volume coefficient of thermal expansion αV however is positive, being 101.22 × 10−6/°C. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers
Morphology of PA‐6 vibration welded joints and its effect on weld strength
Authors: Chung Young‐Mi , Kamal Musa R.
Published: December 2007

The microstructure of the heat affected zone (HAZ) in vibration welded joints of polyamide‐6 were studied using polarized light microscopy (PLM), Fourier transform infrared (FTIR) microspectrometry, scanning electron microscopy (SEM), and modulated differential scanning calorimetry (MDSC). PLM images showed the existence of two distinct HAZ layers: an inner layer (HAZ‐I) with small spherulites and an outer deformed layer (HAZ‐II) adjacent to the bulk zone. The thickness of the HAZ‐I and HAZ‐II layers and the size of spherulites in HAZ‐I depended on welding parameters, such as weld pressure and amplitude. The microstructure study of molecular orientation, using birefringence, and crystal phase type, using FTIR, suggests that HAZ‐I originates from a molten polymer film, while HAZ‐II arises in the polymer in the rubbery state. Etched HAZ surfaces also show clear distinction between the two HAZ layers. Therefore, HAZ‐I is renamed as the recrystallized layer and HAZ‐II as the deformed layer. Fracture tests show that the weakest part of the joint occurs in the recrystallized layer region adjacent to the deformed layer. MDSC analysis indicates that the determining factor of the weld strength is the crystallinity of the recrystallized layer, not the thickness of HAZ. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers
Optical monitoring of polypropylene crystallization during injection molding
Authors: Favaro Márcia M. , Marinelli Alessandra L. , Farah Marcelo , Bretas Rosario E.S.
Published: December 2007

The nonisothermal crystallization of polypropylene resins, i‐PP, during injection molding, using an optical device inserted in the injection mold cavity was monitored. The device detected the change of optical properties which occurs in polymers during their crystallization process; thus the intensity of a laser beam after it passed through the crystallizing polymer was measured during an injection molding cycle. The collected light intensity after the end of the cycle was correlated with the morphologies and final crystallinity degree of the samples. The influence of nucleating agents and the change of the parameters of the injection molding process on the morphology and optical signals were also investigated. The morphologies were analyzed by polarized light optical microscopy, PLOM. The % of crystallinity of the samples was measured by wide angle X‐rays diffraction, WAXS. It was concluded that the optical device was sensible to different polymer crystallization kinetics, morphology type, and changes in the injection molding parameters. It was also found that the mold temperature and packing pressure and time were the factors that affected most the kinetics of crystallization of these polymers in this particular disk geometry. The WAXS results showed that the lower the final light intensity the higher the % of crystallinity in the samples. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers
Thermal residual stress development for semi‐crystalline polymers in rotational molding
Authors: Xu H. , Bellehumeur C.T.
Published: December 2007

In rotational molding, polymer powders are subjected to heating, melting, cooling, and subsequent crystallization processes. Because of the asymmetrical cooling condition, thermally induced residual stresses are created inside molded parts leading to part warpage. A detailed theoretical heat transfer model is presented for the entire rotational molding process including the consideration of endothermic and exothermic transitions. At the same time, the development of residual stress inside the molded parts is simulated with thermoelastic model. The warpage values are calculated under different processing cases, and the generated numerical results are in good agreement with data reported in the literature. Our results show that both crystallinity and temperature gradients developing within the polymer during the cooling process greatly affect the dimensional stability of ethylene copolymers typically processed in rotational molding. The latter is found to be the determining factor in evaluating the effect of cooling conditions on the warpage generated in a molded product. Our results also demonstrate the importance of the crystallization kinetics, the material stiffness, and its evolution during the solidification process on the dimensional stability of the molded products. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers
Tribological properties of blends of melamine‐formaldehyde resin with low density polyethylene
Authors: Brostow Witold , Datashvili Tea , Huang Bernard
Published: December 2007

Tribological properties of blends of melamine‐formaldehyde resin (MFR) with low density polyethylene (LDPE) containing 1, 5, 10, 20, 25 wt% MFR were investigated. We have determined sliding wear by multiple scratching along the same groove using a micro scratch tester. Instantaneous penetration depth is lowered by the MFR addition to LDPE. However, there is less viscoelastic recovery and the residual (healing) depths increase with increasing MFR concentration. Microindentation hardness increases along with the MFR content. Since MFR is only partially miscible with LDPE, MFR‐rich islands in the PE matrix offer more interfaces and so increase hardness. Friction determined with a pin‐on‐disk tribometer using silicon nitride balls as a function of MFR concentration shows a minimum. The result is explained in terms of surface morphology seen in scanning electron microscopy. At the same time, all blend friction values are lower than for neat LDPE. Wear determined in the pin‐on‐disk tribometer decreases along with the MFR concentration increase. Thus, pin‐on‐disk wear and friction show different faces of blends tribology. Blending can be used to improve tribological properties of LDPE. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers
Thermoplastic polyurethane elastomers based on polycarbonate diols with different soft segment molecular weight and chemical structure: Mechanical and thermal properties
Authors: Eceiza A. , Martin M.D. , de la Caba K. , Kortaberria G. , Gabilondo N. , Corcuera M.A. , Mondragon I.
Published: December 2007

A series of thermoplastic polyurethane elastomers based on polycarbonate diol, 4,4′‐diphenylmethane diisocyanate and 1,4‐butanediol was synthesized in bulk by two‐step polymerization varying polycarbonate diol soft segment molecular weight and chemical structure, and also hard segment content, and their effects on the thermal and mechanical properties were investigated. Dynamic mechanical analysis termogravimetric analysis, differential scanning calorimetry, Fourier transform infrared‐attenuated total reflection spectroscopy and mechanical tests were employed to characterize the polyurethanes. Thermal and mechanical properties are discussed from the viewpoint of microphase domain separation of hard and soft segments. On one hand, an increase in soft segment length, and on the other hand an increase in the hard segment content, i.e., hard segment molecular weight, was accompanied by an increase in the microphase separation degree, hard domain order and crystallinity, and stiffness. In phase separated systems more developed reinforcing hard domain structure is observed. These hard segment structures, in addition to the elastic nature of soft segment, provide enough physical crosslink sites to have elastomeric behavior. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers
A macroscopic mathematical model for tensioned‐web slot coating
Authors: Lin Fang‐Ho , Liu Chi‐Ming , Liu Ta‐Jo , Wu Ping‐Yao
Published: December 2007

A mathematical model was developed to predict the performance of tensioned‐web slot coating (TWSC), in particular, the minimum wet thickness. The model was based on the lubrication approximation for the coating solution flow and a simplified membrane theory for the moving web. The theoretical predictions compared reasonably well with available experimental data. The effects of fluid viscosity, web tension, coating speed, and wrapping angle on the performance of TWSC were evaluated. An example was presented to illustrate how die lip design could be varied to improve its performance. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers
Numerical study of nonisothermal polymer extrusion flow with a differential viscoelastic model
Authors: Mu Yue , Zhao Guoqun
Published: December 2007

A numerical study of nonisothermal viscoelastic flow is conducted to investigate the complex flow characteristics of polymer melts in the extrusion process. A general thermodynamic model for the energy conversion related to viscoelastic fluid flow is introduced. The mathematical model for three‐dimensional nonisothermal viscoelastic flow of the polymer melts obeying a differential constitutive equation (Phan‐Thien and Tanner model) is established. A decoupled algorithm based on the penalty finite element method is performed on the calculation. The discrete elastic‐viscous split stress (DEVSS) algorithm, incorporating the streamline‐upwind Petrov‐Galerkin (SUPG) scheme is employed to improve the computation stability. Essential flow characteristics of polymer melts in the extrusion die for hollow square plastic profile is investigated based on the proposed numerical scheme with ignoring the outer thermal resource. The energy partitioning, which quantified the conversion of mechanical energy into thermal energy, is discussed. The effects of volume flow rate and die contraction angle upon the flow patterns are further investigated. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers
From peripheral to central, the story of Melanie's metamorphosis in an urban middle school science class
Authors: Tan Edna , Barton Angela Calabrese
Published: December 2007

Identity formation is a critical dimension of how and why students engage in science to varying degrees. In this paper, we use the lens of identity formation, and in particular identities in practice, to make sense of how and why Melanie, over the course of sixth grade, transformed from a marginalized member of the science class with a failing grade to a highly valued member of the sixth‐grade science community with a perfect score of a 100% for the sixth‐grade exit project. Our findings reveal that the different figured worlds of the science classroom, such as whole class, small group work, and individual work, offered Melanie different affordances for identity formation that were built upon across such spaces, in both productive and unproductive ways. Our findings also take up the kinds of critical roles that members of her classroom community, in particular teacher and peers, play in supporting and constraining such a transformation. We discuss the implications identity formation has for understanding issues of gender equity and science learning. © 2007 Wiley Periodicals, Inc. Sci Ed 92:567–590, 2008
rAAV‐asPLB transfer attenuates abnormal sarcoplasmic reticulum Ca2+‐ATPase activity and cardiac dysfunction in rats with myocardial infarction
Authors: Zhao Xiao‐Yan , Hu Shen‐Jiang , Li Jiang , Mou Yun , Bian Ka , Sun Jian , Zhu Zhao‐Hui
Published: December 2007

Background:

Diminished myocardial sarcoplasmic reticulum Ca2+‐ATPase (SERCA) activity and upregulated phospholamban (PLB) level during cardiac dysfunction, had been reported in many studies.

Aims:

The current study was designed to examine the effects of rAAV‐antisense phospholamban (asPLB) gene transfer on cardiac function, SERCA expression and activity, as well as PLB expression and phosphorylation (Pser16‐PLB), in a rat myocardial infarction (MI) model.

Methods and results:

Rat MI model was generated by ligating the left anterior descending coronary artery. Four weeks later, left ventricular ejection fraction (LVEF), left ventricular systolic pressure (LVSP), the maximal rates of increase and decrease in intraventricular pressure (±dp/dtmax) were significantly depressed, and left ventricular end diastolic pressure (LVEDP) was increased. Myocardial PLB was markedly increased while both SERCA activity and Pser16‐PLB level were decreased. In rAAV‐asPLB transfected rats, rAAV‐asPLB, which was injected into the myocardium around the infarction area immediately after the coronary artery ligation, effectively attenuated the depression of cardiac function, significantly inhibited the expression of PLB, restored Pser16‐PLB level and enhanced myocardium SERCA activity.

Conclusion:

rAAV‐asPLB transfer in rats with MI effectively prevented the progression of heart failure.
C‐reactive protein, diastolic dysfunction, and risk of heart failure in patients with coronary disease: Heart and Soul Study
Authors: Williams Eric S. , Shah Sanjiv J. , Ali Sadia , Na Bee Ya , Schiller Nelson B. , Whooley Mary A.
Published: December 2007

Background:

High‐sensitivity C‐reactive protein (CRP) is an inflammatory marker that predicts coronary heart disease (CHD) and, in recent studies, incident heart failure (HF). Whether the association of inflammation with incident HF is explained by worse baseline left ventricular dysfunction or by underlying CHD is unknown.

Methods and results:

Serum CRP was measured in a cohort of 985 outpatients with established CHD from the Heart and Soul Study. During 3 years of follow‐up, 15% of the participants with elevated CRP levels (>3mg/L) were hospitalised for HF, compared with 7% of those with CRP ≤3 mg/L. In multivariate analysis, elevated CRP was associated with HF after adjustment for traditional risk factors, baseline CHD severity and interim MI (adjusted HR 2.1, 95% CI, 1.2–3.6; p=0.009). However, elevated CRP was no longer associated with HF after further adjustment for the presence of diastolic dysfunction on echocardiography (adjusted HR 1.6, 95% CI, 0.8–3.2; p=0.1).

Conclusions:

Among outpatients with stable CHD, elevated CRP levels predict hospitalisation for heart failure, independent of baseline heart failure, medication use, CHD severity, and subsequent MI events. This relationship appears to be at least partly explained by abnormal diastolic function in patients with elevated CRP levels.
Chronotropic incompetence, beta‐blockers, and functional capacity in advanced congestive heart failure: Time to pace?
Authors: Jorde Ulrich P. , Vittorio Timothy J. , Kasper Michael E. , Arezzi Emma , Colombo Paolo C. , Goldsmith Rochelle L. , Ahuja Kartikya , Tseng Chi‐Hong , Haas Francois , Hirsh David S.
Published: December 2007

Background:

Chronotropic incompetence (CI) is often seen in subjects with chronic congestive heart failure (CHF). The prevalence of CI, its mechanisms and association with beta‐blocker use as well as exercise capacity have not been clearly defined.

Methods and results:

Cardiopulmonary exercise tolerance testing data for 278 consecutive patients with systolic CHF was analyzed. CI, defined as the inability to reach 80% of maximally predicted heart rate was present in 128 of 278 subjects (46%). The prevalence of CI was highest in those with most impaired exercise capacity (72, 48, and 24% for subjects with a VO2 of <14.0, 14.0–20.0, and >20.0ml/kg/min respectively; p=0.001). While subjects with CI had lower peak exercise heart rate (114 vs. 152 bpm), and lower peak VO2 (15.4 vs. 19.9 ml/kg/min), they were equally likely to be on chronic beta‐blocker therapy (74% vs. 71%; p=0.51).

Heart rate and norepinephrine (NE) levels were measured during exercise in a separate cohort of 24 subjects with CHF. There was no difference in beta‐blocker dose between subjects with and without CI, however, exercise induced NE release and Chronotropic Responsiveness Index, a measure of post‐synaptic beta‐receptor sensitivity to NE, were lower in subjects with CI (1687±911 vs. 2593±1451pg/ml p=0.08; CRI 12.7±5.7 vs. 22.1±4.7, p=0.002).

Conclusions:

CI occurs in >70% of subjects with advanced systolic CHF irrespective of beta‐blocker use and is associated with a trend toward impaired NE release, post‐synaptic beta‐receptor desensitization and reduced exercise capacity.
Number of pain sites is associated with demographic, lifestyle, and health‐related factors in the general population
Authors: Kamaleri Yusman , Natvig Bård , Ihlebaek Camilla M. , Benth Jurate Saltyte , Bruusgaard Dag
Published: December 2007

Research on widespread pain often relies upon case definitions bounded by duration limits or “cut‐offs.” In clinical reality, however, there are no natural cut‐off points between localized and widespread pain. Rather, pain is best represented by a continuum of “widespreadness” from localized pain to pain spread across the body. The objective of this paper was to describe the number of pain sites (NPS) reported in a population study and its association with demographic, lifestyle, and health‐related factors. Using a cross‐sectional design, the Standardized Nordic Questionnaire was used to measure musculoskeletal pain among seven age groups in Ullensaker, Norway (n=2926). Results showed that women reported a higher mean NPS than men. A higher NPS was also found for individuals who were separated or divorced, undergoing rehabilitation, or who had a disability pension. Additionally, greater NPS was reported by smokers, individuals with less physical activity, and a higher BMI. A strong linear relationship was found between NPS and reduction in overall health, sleep quality, and psychological health. Results from a multivariate linear regression analysis showed that overall health, sleep quality, and gender demonstrated the strongest associations with increasing NPS, accounting for 31.4% of the variance. Our study indicates that the straightforward and simple method of counting the NPS could be important in managing the complex problem of musculoskeletal pain.
A descriptive case-register study of delusional disorder
Authors: de Portugal Enrique , González Nieves , Haro Josep M. , Autonell Jaume , Cervilla Jorge A.
Published: December 2007

Objective

A few empirically based studies' data on delusional disorder (DD) exist. We aim to describe sociodemographic and clinical correlates of DD and to identify clinical profiles associated to DD and its subtypes.

Methods

This is a case-register study based on all those subjects attending community mental health services within a geographically well-defined area. Four hundred and sixty-seven patients had been diagnosed as DD cases at psychiatric services serving a catchment area of some 607,494 inhabitants living in South Barcelona (Spain) during a three-year period (2001–2003). A thorough systematic review of computerised medical records was used to establish DSM-IV diagnosis, rendering a valid sample of 370 patients who fulfilled DSM-IV criteria for DD. Independent variables gathered include sociodemographic data, family and personal psychiatric history, and comorbid diagnoses on all DSM-IV axes (including GAF). We used descriptive and univariate statistical methods to explore sample frequencies and correlates across DD types.

Results

The mean age of the patients was 55 years and the sample had a mean GAF score of 51 suggesting a poor functionality; 56.5% of the patients were female. The most frequent DD types were persecutory (48%), jealous (11%), mixed (11%) and somatic (5%), whilst 23% qualified for the NOS type. Most frequent symptoms identified were self-reference (40%), irritability (30%), depressive mood (20%) and aggressiveness (15%). Hallucinations were present in 16% of the patients (6% tactile; 4% olfactory). Nearly 9% had a family history of schizophrenia (higher among those with the jealous subtype) and 42% had a comorbid axis II diagnosis (mostly paranoid personality disorder). Depression was significantly more frequent among the persecutory and jealous types. Finally, global functioning was significantly better among jealous and mixed types and worse amongst erotomanic and grandiose cases (p = 0.008).

Conclusions

In the absence of other similar empirical data, this modest study provides unique empirical evidence of some clinical and risk correlates of DD and its subtypes.
Finding of abnormal scanning behavior in the Span of Apprehension task in schizophrenia but diagnostic non-specificity of sum scores
Authors: Koelkebeck Katja , Ohrmann Patricia , Pedersen Anya , Hetzel Guenter , Arolt Volker , Suslow Thomas
Published: December 2007

Deficits in the Span of Apprehension (SOA) task have been discussed controversially as a trait marker of schizophrenia. The task was administered to 47 schizophrenia and 48 depressed patients as well as to 46 controls. Results indicate a non-specificity of the SOA sum scores but differential abnormalities in spatial visual processing.
Parallel increase in p70 kinase activation and tau phosphorylation (S262) with Aβ overproduction
Authors: Zhou Xin-Wen , Tanila Heikki , Pei Jin-Jing
Published: December 2007

This study set out to search for a link between overproduction of Aβ and p70S6 kinase (p70S6K) phosphorylation/activation. Results showed that levels of p‐p70S6K at T421/S424 and T389 are significantly increased in mouse N2a neuroblastoma cells carrying human APP with Swedish mutation (APPswe), and in transgenic APPswe/PS1 (A246E) mice as compared with respective controls, corresponding to the increase of tau phosphorylation at S262. This parallel increase in p70S6K activation and tau phosphorylation could be demonstrated by treating wild‐type N2a cells with Aβ25–35. Our results suggest that the Aβ deposition in senile plaques in Alzheimer disease brains might be a primary event that activates p70S6K and phosphorylates tau at S262, resulting in microtubule disruption.
Cx23, a connexin with only four extracellular‐loop cysteines, forms functional gap junction channels and hemichannels
Authors: Iovine M. Kathryn , Gumpert Anna M. , Falk Matthias M. , Mendelson Tamra C.
Published: December 2007

Gap junction channels may be comprised of either connexin or pannexin proteins (innexins and pannexins). Membrane topologies of both families are similar, but sequence similarity is lacking. Recently, connexin‐like sequences have been identified in mammalian and zebrafish genomes that have only four conserved cysteines in the extracellular domains (Cx23), a feature of the pannexins. Phylogenetic analyses of the non‐canonical “C4” connexins reveal that these sequences are indeed connexins. Functional assays reveal that the Cx23 gap junctions are capable of sharing neurobiotin, and further, that Cx23 connexins form hemichannels in vitro.
Functional role of Zic2 phosphorylation in transcriptional regulation
Authors: Ishiguro Akira , Aruga Jun
Published: December 2007

Zic2 is a transcriptional activator that plays a crucial role in mammalian forebrain development. It activates the transcription of target genes by DNA binding and recruitment of RNA helicase A (RHA). We recently reported that the Zic2–RHA interaction is decreased by phosphatase treatment in vitro. We have now identified the phosphorylation site (serine 200) in mouse Zic2. Zic2S200A was defective in RHA‐binding, and its transcriptional activation ability was diminished. These data indicate that Zic2S200 is a target for phosphorylation by DNA‐dependent protein kinase, regulating Zic2‐mediated transcriptional activation.
A conserved domain of herpes simplex virus ICP34.5 regulates protein phosphatase complex in mammalian cells
Authors: Zhang Cuizhu , Tang Jun , Xie Jia , Zhang Hongkai , Li Yapeng , Zhang Jie , Verpooten Dustin , He Bin , Cao Youjia
Published: December 2007

ICP34.5, encoded by herpes simplex virus 1, is a protein phosphatase 1 (PP1) regulatory subunit that mediates dephosphorylation of the α subunit of translation initiation factor 2 (eIF2α). However, the mechanism of its action remains poorly understood. Here, we show that amino acid substitutions in the arginine‐rich motif have differential effects on ICP34.5 activity. The phenotypes parallel with viral protein synthesis and cytopathic effects in virus infected cells. Besides the consensus PP1 binding motif, the Arg‐motif appears to enhance the interaction between ICP34.5 and PP1. These results suggest that concerted action between the PP1 binding domain and the effector domain of ICP34.5 is crucial for eIF2α dephosphorylation and viral protein synthesis.
Inflammation and Alzheimer's disease: Possible role of periodontal diseases
Authors: Kamer Angela R. , Craig Ronald G. , Dasanayake Ananda P. , Brys Miroslaw , Glodzik‐Sobanska Lidia , de Leon Mony J.
Published: December 2007

The molecular and cellular mechanisms responsible for the etiology and pathogenesis of Alzheimer's disease (AD) have not been defined; however, inflammation within the brain is thought to play a pivotal role. Studies suggest that peripheral infection/inflammation might affect the inflammatory state of the central nervous system. Chronic periodontitis is a prevalent peripheral infection that is associated with gram‐negative anaerobic bacteria and the elevation of serum inflammatory markers including C‐reactive protein. Recently, chronic periodontitis has been associated with several systemic diseases including AD. In this article we review the pathogenesis of chronic periodontitis and the role of inflammation in AD. In addition, we propose several potential mechanisms through which chronic periodontitis can possibly contribute to the clinical onset and progression of AD. Because chronic periodontitis is a treatable infection, it might be a readily modifiable risk factor for AD.
Realizing the potential of positron emission tomography with 18F‐fluorodeoxyglucose to improve the treatment of Alzheimer's disease
Authors: Foster Norman L. , Wang Angela Y. , Tasdizen Tolga , Fletcher P. Thomas , Hoffman John M. , Koeppe Robert A.
Published: December 2007

Positron emission tomography (PET) with 18F‐fluorodeoxyglucose (FDG‐PET) thus far rarely has been used to advance the development of new treatments for Alzheimer's disease (AD). Now that FDG‐PET with standard acquisition protocols for dementia is widely available, change in cerebral glucose metabolism is a feasible outcome variable for clinical drug trials. Individual analysis of FDG‐PET results also might prove valuable. FDG‐PET can detect metabolic changes very early in the course of AD and identify subjects for earlier treatment. FDG‐PET reliably distinguishes AD from frontotemporal dementia so that only those most likely to benefit are enrolled in trials. Finally, objectively identifying phenotypic variations of AD with FDG‐PET might have pathogenic and prognostic implications that can be used for personalized treatment approaches. The judicious use of FDG‐PET is needed to accelerate the evaluation of promising new drugs and more rationally target treatments for dementing diseases.
Electroencephalography and event‐related potentials as biomarkers of mild cognitive impairment and mild Alzheimer's disease
Authors: Jackson Colleen E. , Snyder Peter J.
Published: December 2007

Background

Successful early detection of mild cognitive impairment (MCI) and Alzheimer's disease demands the identification of biomarkers capable of distinguishing individuals with prodromal or early cognitive impairment from healthy aging adults. Many laboratories are engaged in the discovery and validation of a wide array of potential genetic, proteomic, cognitive, and other types of biomarkers.

Methods

This review focuses on the application of quantitative electroencephalography (qEEG) and event‐related potential (ERP) technologies as markers of prodromal impairment and early disease progression. It is the aim of this review to critically assess where this field currently stands, as well as future directions for EEG biomarker development.

Results

As a neuroimaging tool that is relatively inexpensive, potentially portable, and capable of providing high‐density spatial mapping, qEEG offers a noninvasive, rapid, and replicable method for assessing age‐related and disease‐related neurophysiologic change.

Conclusions

As different signature changes associated with particular stages of disease burden are identified and validated, we anticipate expanded application of qEEG as a reliable and sensitive biomarker(s) of MCI and early Alzheimer's disease.
One‐week dose titration of extended release galantamine in patients with Alzheimer's disease
Authors: Scharre Douglas W. , Shiovitz Thomas , Zhu Young , Amatniek Joan
Published: December 2007

Background

Our purpose was to assess the safety and tolerability of extended‐release galantamine (GAL‐ER), using a 1‐week dose titration in Alzheimer's patients.

Methods

An open‐label, 12‐week, multicenter study was performed (n = 82). Results were compared with findings from a placebo‐controlled trial using a 4‐week titration of GAL‐ER and immediate‐release galantamine. The primary analysis compared incidences of adverse events (AEs).

Results

Although not statistically significant, more patients in the 1‐week titration study experienced an AE. More patients with a 1‐week titration had at least one prespecified gastrointestinal (GI) AE. These findings correlated with a higher baseline incidence of GI disturbances. Four patients experienced serious AEs; no deaths occurred. Mean Mini‐Mental State Examination scores improved by 1.8 and 1.9 points at weeks 4 and 12, respectively.

Conclusions

A 1‐week titration of GAL‐ER was generally safe and well tolerated, with a potential risk of more GI side effects. A 1‐week titration may permit dosing flexibility and promote increased adherence to medication regimens.
Memory health clinics—a first step to prevention
Authors: Vellas Bruno , Gillette‐Guyonnet Sophie , Andrieu Sandrine
Published: December 2007

A few years ago at the European Alzheimer's Disease Consortium–Alzheimer's Disease Cooperative Study meeting in Geneva we discussed with Leon Thal the possibility of building large multi‐domain primary preventive international trials for Alzheimer's disease (AD) both in North America and in the European Union. AD is a multifactorial phenomenon, and we will be more likely to succeed in preventive trials if we build a strategy using all potential protective factors to have the most potential effect instead of a simple and unique intervention. Leon Thal suggested that this could have a much bigger impact than all the drugs we might ever hope to develop. The main objective of this article is to present the rationale for multi‐domain preventive approaches.
Eyes on the prize: Federal Alzheimer's research effort aims to facilitate interventions
Authors: Hodes Richard J. , Buckholtz Neil , Cahan Vicky , Morrison‐Bogorad Marcelle
Published: December 2007

The public Alzheimer's disease (AD) research enterprise began in earnest in the mid‐1970s with the creation by Congress of the National Institute on Aging at the National Institutes of Health. Today, AD research is a maturing field of study, with federal effort seeking to encourage the creativity and insights of individual investigators, and targeting special areas for emphasis. It is inspired by the legacy of our friend and colleague Leon Thal, whose innovative and collaborative approach to scientific research serves as a guidepost as we move toward the discovery of new and effective ways to prevent AD or slow its progression. This article describes the progress to date and potentially promising areas of study from the vantage point of the National Institute on Aging.
Prevention therapeutics of dementia
Authors: Schneider Lon S.
Published: December 2007

In the absence of effective drugs for Alzheimer's disease (AD) and a validated roadmap or guideline for drug development, it is important to consider some of the limitations currently hampering AD drug development and some general principles for moving forward. This paper will address current barriers to developing drugs for AD, and offer new considerations for accelerating drug discovery, development, and clinical trials.
The oldest old and the 90+ Study
Authors: Kawas Claudia H.
Published: December 2007

Memories are the gifts from friends and family that stay with us forever, unless a person develops Alzheimer's disease. Leon J. Thal left many, many memories, along with his desire to create a world where people did not lose them to the ravages of dementing illnesses. Working from the bench to the clinic, he was an incomparable leader, scientist, and educator to whom many, including myself, owe much. The present description of a clinical, genetic, and pathologic study of the oldest old contains much of Leon's influence. With data from >950 subjects, a brain repository, and our collection of DNA, the investigators of the 90+ Study are receptive to collaborations. Through our collective efforts, we will continue the scientific work that Leon so strongly supported.
Current challenges for the successful treatment and prevention of Alzheimer's disease: Treating the pathologies of the disease to change its clinical course
Authors: Schenk Dale
Published: December 2007

The need to develop meaningful therapeutics for Alzheimer's disease is beginning to reach the general awareness of the public. Matching this awareness is the accelerated pace of compounds entering clinical trials. In addition, the development of diagnostic tools, biomarkers, and imaging modalities of the past decade in AD have improved dramatically. Unfortunately, the use of these diagnostic and scientific tools in clinical trial practice has not yet aligned or optimized. Most agents still target clinical end points associated with mild to moderate AD rather than focus on modulation of the underlying pathologies. Although there are obvious practical reasons for this, meaningful progress in other areas of medicine such as cardiology and oncology have generally targeted and monitored improvement or abatement of pathology as the primary end point as a successful disease‐modifying strategy. Perhaps it is time to consider a similar approach in treatment of Alzheimer's disease.
Debatable questions of Boreal Triassic stratigraphy: boundary between middle and upper series
Authors: Konstantinov A.G.
Published: December 2007

Various opinions on the position of the Middle/Upper Triassic boundary have been concisely reviewed. The lower boundary of the Carnian Stage is accepted at the base of the Trachyceras aon Zone. The recentmost data on biostratigraphy of boundary beds of the Ladinian and Carnian Stages of the Southern Alps, Himalayas, British Columbia, northeastern Asia, Svalbard, and Arctic Canada have been considered and critically analyzed. Using sections of British Columbia with mixed Boreal and Tethyan fauna of Ammonoidea, we compared biostratigraphic schemes of the Middle/Upper Triassic boundary interval of the Boreal and Tethyan regions. On the basis of correlations and paleontological data, the lower boundary of the Carnian Stage in Northeastern Asia is suggested to be drawn at the base of the ammonoid “Protrachyceras” omkutchanicum Zone and its equivalents in other Boreal regions.
Tectonic evolution of the western margin of the Ordos Basin (Central China)
Authors: Rongxi Li , Youzhu Li
Published: December 2007

The western half of the Ordos Basin lies in the north of Central China, on the western margin of the North Chinese Platform. In the southwest and south it borders the Qilian and Qinling folded systems. Their frontal northeastern flank is thrust over the Paleozoic nappe of the Ordos Basin and consists of a series of large parallel linear folds separated by thrusts. The basement of the basin is made up of deformed metamorphic rocks of tentatively Late Proterozoic age. Carbonate and terrigenous intracratonic facies accumulated on the Ordos block from Early Cambrian through Middle Ordovician. From Middle Ordovician through Middle Carboniferous, the western edge of the block was uplifted as a land as a result of Caledonian tectonic movement and underwent denudation for about 150 Myr. In the Late Paleozoic, a series of coal-bearing formations was deposited. In the Triassic, the Ordos Basin became filled with fluviolacustrine delta facies. Thrusts and folds on the southwestern margin of the basin formed in the Mesozoic and were intensified by Himalayan tectonic movements.
Glacial deposits and “watershed pebbles” in the Western Baikal area
Authors: Akulov N.I. , Agafonov B.P. , Rubtsova M.N.
Published: December 2007

Results of the activity of Quaternary glaciations in the western Baikal area are considered based on new factual material. Also, the problem of the formation of “watershed pebbles” in the area is discussed. Data indicating the fluvioglacial origin of the pebbles are reported. Special attention is given to the composition, lithology, and stratigraphy of glacial deposits and their geomorphologic position in the study area, which is one of the most hardly accessible and interesting regions in East Siberia in terms of both the geology of Quaternary deposits and archaeology. Results of spore-and-pollen analyses and archaeological evidence are reported.
Mercury in soils and plants in the area of Lake Bol’shoe Yarovoe (Altai Territory)
Authors: Malikova I.N. , Ustinov M.T. , Anoshin G.N. , Badmaeva Zh.O. , Malikov Yu.I.
Published: December 2007

We examined mercury distribution in soils and plants of the catchment area of Lake Bol’shoe Yarovoe with the Altaikhimprom chemical industrial complex situated on its shore. Data on mercury contents show a considerable mercury flow into the environment, though the industrial complex and its waste do not pose serious threat. The revealed pollution in the immediate vicinity of the industrial complex, including that due to atmospheric transport, as well as the elevated content of mercury in hydrochloric and alkaline extracts suggest its intense migration from the waste. Therefore, it is necessary to make up an inventory of the industrial-complex waste and perform a detailed study of the lake ecosystem as a model unit.
High-temperature conductance of chromite and host dunite-harzburgite ophiolites in the Urals: a comparative study
Authors: Bakhterev V.V.
Published: December 2007

Electrical resistance measurements, thin-section, chemical, thermal differential, and thermal gravity analyses have been applied to study samples of chromite and the host serpentinite from the Podenny and Kurman deposits in the Alapaevsk ophiolite and from the Piany Bor and southern deposits in the Klyuchevskoi ophiolite. Samples from the four sites exhibit similar patterns of activation energy E0) vs. resistance coefficient (log R0). The E0–log R0 points of samples collected away from ore fields align along a straight line corresponding to the log R0 = a – bE0 relationship typical of nonmineralized rocks, with the a and b coefficients as in alpine ultramafics. The samples of mineralized rocks depart from the basic line, the departure increasing as they approach the orebody. Though having similar patterns, the E0–log R0 fields of the samples from different sites show no overlap. The revealed features may be useful as implicit diagnostic criteria for ophiolite-hosted chromite mineralization.
High resolution paleoenvironmental and chronological investigations of Norselandnámat Tasiusaq, Eastern Settlement, Greenland
Authors: Edwards Kevin J. , Schofield J. Edward , Mauquoy Dmitri
Published: December 2007

High-resolution paleoenvironmental data from a peat profile with a small pollen source area are used to reconstruct the impacts oflandnámon vegetation and soils at a Norse farm complex (∅2 at Tasiusaq) comprising two farms in the Eastern Settlement of Greenland. Analyses include the AMS14C dating of plant macrofossil samples and the use of Bayesian radiocarbon calibration to construct improved age–depth models for Norse cultural horizons. The onset of a regionallandnámmay be indicated by the clearance ofBetula pubescenswoodland immediately prior to local settlement. The latter is dated to AD 950–1020 (2σ) and is characterised by possible burning ofBetula glandulosascrub to provide grassland pasture for domestic stock. Clearance and grazing resulted in accelerated levels of soil erosion at a westerly farm. This was followed by an easterly migration of settlement and agriculture. Site constraints prevent an assessment of the demise of the easterly farm, but pressures of overgrazing and land degradation may have been the major factors responsible for the abandonment of the earlier farm.