bluuebunny/crossref_metadata_2025 huggingface dataset:
Poly(2,5-Benzimidazole) Membranes: Physico-Chemical Characterization and High Temperature PEMFC Application
Authors: Linares José J. , Sánches Cassandra , Paganin Valdecir Antônio , González Ernesto R.
Published: October 2011

Poly 2,5-benzimidazole (ABPBI) membranes cast from sufficiently high molecular weight polymer were doped with phosphoric acid in order to provide proton conductivity with values ranging between 0.01 and 0.07 Scm-1, depending on the operation conditions. Positive characteristics of these doped membranes are the excellent thermal stability, and acceptable mechanical properties (though weakened after doping). Also, membrane permeability to alcohols is also reduced compared to Nafion®, and no pre-humidification is necessary during fuel cell operation. However, acid doped ABPBI membranes possess certain weak points, such as a higher hydrogen/oxygen gas permeability compared to Nafion®, and a limited resistance to hydroxyl radicals. Nonetheless, satisfactory fuel cell results can be obtained when operating the cells with H2/air, with a maximum power of 170 mW cm-2 at 170ºC and atmospheric pressure.
Oxygen Electroreduction on PtxCo1-x and PtxCu1-x Alloy Nanoparticles for Basic and Acidic PEM Fuel Cell
Authors: Oezaslan Mehtap , Hasché Frédéric , Strasser Peter
Published: October 2011

Our study presents the electrochemical characterization of PtxCo1-x and PtxCu1-x nanoparticle electrocatalysts after the voltammetric treatment in basic and acidic electrolytes at room temperature. The chemical composition and mean particle size of the Pt alloy nanoparticles were determined before and after the voltage cycling using TEM and EDS. The electrochemical experiments were conducted with the RDE technique. We show that the electrochemical conditioning is a critical step for the formation of highly active Pt alloy nanoparticle electrocatalysts for ORR. The voltage cycling in acid leads to the leaching of less noble metal to generate a reactive Pt enriched particle surface, while in basic stable metal hydroxide/oxide are primarily formed on the surface of the Pt alloy particles. In particular, in basic voltammetric pretreated PtM3 shows the lowest Pt mass based activity for ORR. In contrast, in acid dealloyed PtCu3 and PtCo3 exhibit 3 - 4 fold increase in jmass compared with Pt/HSAC.
Electrooxidation of Ethylene Glycol and Glycerol by Pt Based Binary and Ternary Templated Catalysts in Alkaline Media
Authors: Falase Akinbayowa , Garcia Kristen , Main Michelle , Lau Carolin , Atanassov Plamen
Published: October 2011

Spray pyrolysis of metal precursors was used to synthesize binary and ternary templated Pt based catalysts. Characterization of the catalysts was performed using SEM, TEM, and EDS to determine morphology, purity and composition. The electrochemical performance of PtRu, PtSn, and PtRuSn was evaluated via cyclic voltammetry and steady state polarization for oxidation of ethylene glycol and glycerol. The ternary PtRuSn catalyst had the highest metal utilization, as well as the highest maximum current. This work emphasizes the gains provided by adding modifiers to Pt catalysts for oxidation of complex alcohols.
Pt7Sn3 Catalysts for Ethanol Electro-Oxidation: Correlation between Surface Structure and Catalytic Activity
Authors: Baranova Elena A. , Artyushkova Kateryna , Halevi Barr , Amir Tariq , Martinez Ulises , Atanassov Plamen
Published: October 2011

X-ray photoelectron spectroscopy has been chosen to study the surface chemistry of carbon-supported PtSn catalysts of 70:30 at.% composition. Correlation of XPS structural information with catalytic performance for ethanol electro-oxidation in acidic solution, average particle size and structural characteristics is accomplished by application of multivariate statistical methods of data analysis (MVA). From structure to property correlations it was found that the best performing electrocatalysts do not have largest absolute amounts of Pt and Sn on the surface, whereas samples with largest amount of total Pt and Sn have the worst catalytic activity. It is shown that relative distribution of types of Pt and Sn is more important than the absolute amounts. Samples showing the highest current densities have small amounts of both metals, but have largest relative amount of both metallic Pt and metallic Sn. The same best performing samples have fewest amounts of all types of oxides, i.e. PtO, PtO2 and SnOx.
Comparative Study on Electrochemical Oxidation of Sodium Borohydride on Carbon Supported PtSn and Pt
Authors: Hou Junbo , Ellis Michael
Published: October 2011

Pt/C and PtSn/C were investigated for electrochemical activity towards borohydride oxidation in direct borohydride fuel cell applications. Voltammetry on stationary electrode and rotating disk electrode, chronopotentiometry and chronoamperometry were conducted on a thin film electrode. The results indicate that the presence of Sn in the catalyst may facilitate the borohydride oxidation reaction. An adsorption-electrochemical step is proposed to explain the enhanced activity for the PtSn/C.
Multiscale Simulation of Hydroxide Solvation and Transport in Anion Exchange Membranes
Authors: Lindberg Gerrick E. , Knight Chris , Jorn Ryan , Dama James F. , Voth Gregory A.
Published: October 2011

Fuel cells are an attractive alternative to other energy conversion methods because of their efficiency and energy density. Unfortunately, the high expense and limited durability of catalysts in common fuel cells has slowed their commercialization. The limitations of current anion exchange membranes (AEMs) may be minimized by improved design and material optimization. This work aims to improve the understanding of fuel cell AEMs from a fundamental perspective through multiscale simulation techniques. Studies on hydroxide anions in relevant AEMs reveal the importance of explicitly including the physics of proton shuttling to properly describe the solvation and transport of the ions in these systems. These results are in turn bridged to a mesoscopic simulation methodology that incorporates the morphological features of the membrane, leading to a better understanding of the coupling of domain structure to charge transport processes and its affect on ion conductance properties.
Calculating Hydroxide Conductivity in Alkaline Anion Exchange Membranes
Authors: Kiss Andrew M. , Myles Timothy D. , Grew Kyle N. , Peracchio Aldo A. , Nelson George J. , Chiu Wilson K.
Published: October 2011

Alkaline anion exchange membrane (AEM) fuel cells have received increased interest for portable power applications because of the ability to use alcohol fuels and non-platinum group metal catalysts. Present AEMs typically have ionic conductivities which are significantly lower than that of other low temperature fuel cells, which increases the losses that are attributed to the membrane. By using a permeation experiment to measure water flux across the membrane, ionic conductivity can be predicted with measured water flux data and the dusty fluid model. The ability to better understand and predict mass transport in the AEM can provide valuable information about how to improve membrane performance.
Expanded Graphite Epoxy Composite Bipolar Plates for PEM Fuel Cells
Authors: Unveroglu Begum , Dundar Furkan , Ay Fatih , Yazici Suha , Ata Ali
Published: October 2011

Light weight, flexible and thin single layer epoxy impregnated expanded graphite bipolar plates were manufactured and evaluated as a PEM fuel cell bipolar plate material. Mechanical strength values up to 17.41 MPa, in-plane electrical conductivity values up to 136.6 S/cm, through-plane electrical resistance of 0.027 Ohm-cm and flexibility (deflection at mid-span) values up to % 4.38 were obtained with epoxy impregnation in expanded graphite foams. The low thickness (~0.5 mm) and density (~1.2 g/cm3) values of the prepared composite plates put them one step ahead for mobile applications which require high mass and volumetric power density (W/kg, W/L). On the other hand, corrosion current and contact angle values of these composite plates couldn't achieve desired values.
The Use of Proton Exchange Membrane Fuel Cell Technology to Recover Gaseous Helium from Rocket Testing Systems
Authors: Angelo Michael , Haberbusch Mark , Nguyen Chinh , Bethune Keith , Rocheleau Richard
Published: October 2011

In this work, the use of proton exchange membrane fuel cell (PEMFC) technology is demonstrated as a novel method to separate gaseous hydrogen (GH2) from gaseous helium (GHe). This was accomplished by operating a PEMFC system in an electrolytic mode to electrochemically oxidize hydrogen and transport it away from the inert GHe stream. Quantification of the amount of GH2 removed from the anode stream was determined by measuring the inlet and outlet GH2 concentration and the rate of the hydrogen oxidation reaction (HOR) using different techniques. Exit streams with < 50 parts per million GH2 concentrations were obtained. The HOR was shown modeled as a first order mass transport limited process for dilute GH2 streams at the limiting current density. A model based on a differential reactor design and first order kinetics is presented herein to obtain an estimate of the minimum active area required to remove specific quantities of GH2.
Effect of the Content of Platinum and Carbon Support in Cathode Catalyst on the Cell Performance under Low and High Relative Humidity
Authors: Nakajima Hitoshi , Matsutani Koichi , Kaieda Takeshi , Tada Tomoyuki
Published: October 2011

The cell performances under low or high relative humidity were examined for Pt / C cathode catalysts of various Pt / C ratio and various lower catalyst loading. At the same ionomer to carbon ratio (I / C) and the same Pt loading (0.4 mg cm-2), the cell voltage were almost identical against the weight ratios of platinum to carbon under both RH=30% and RH=100%. The highest cell voltage was obtained around I / C = 1.0, independent of the weight ratios of platinum to carbon and ionomer, and RH. HSAC-1 and Vulcan XC-72R exhibited the similar trend to the dependence on Pt / C ratio. At the same Pt / C ratio, HSAC-1 and Vulcan XC-72R showed similar cell performance in general. In the case of Pt loading was 0.05 mg cm-2, the best cell voltage was observed at I / C =0.6 and lower than that of high Pt loading. The cell resistance excluding the membrane resistance was increased as the decrease of Pt loading.
The Use of Ionic and Non-Ionic Surfactants for the Control of Platinum Nanoparticle Aggregation in Proton Exchange Membrane Fuel Cells (PEMFCs)
Authors: Pollet Bruno , Newton Jill E. , Preece Jon A. , Curnick Oliver J.
Published: October 2011

This investigation focuses on the aggregation behaviour of Pt catalyst nanoparticles in Proton Exchange Membrane Fuel Cells (PEMFCs). Here, Pt nanoparticles were prepared using various surfactants which are known to prevent aggregation. Dispersed nanoparticles are thought to have a higher available electrochemical surface area, hence exhibiting higher catalytic activity than aggregated nanoparticles. In our study, Pt nanoparticles were prepared in aqueous dispersion using tetradecyltrimethylammonium bromide (C14TAB), cetyltrimethylammonium bromide (C16TAB) and nonylphenolethoxylate (NP9). The aggregation behaviour of the nanoparticles was studied using Transmission Electron Microscopy (TEM), Nanosight and Dynamic Light Scattering (DLS). Electrochemical experiments on Pt Rotating Disc Electrode (RDE) in the absence and presence of surfactants at 298K show that the surfactants have a marked effect on the obtained linear sweep voltammograms (LSVs). The movement of the onset potential to lower overpotentials suggests the surfactant is 'poisoning' catalytic sites on the electrode. This also demonstrates that the surfactant selection is vital to obtaining effective PEMFC cathode catalyst.
Development of Oxygen Reduction Electrocatalysts Based on Manganese Oxides for AEMFCs
Authors: Takakuwa Tatsuya , Akiyoshi Masato , Kenko Takuya , Saito Morihiro , Daimon Hideo , Tasaka Akimasa , Inaba Minoru , Shiroishi Hidenobu , Hatai Takeo , Kuwano Jun
Published: October 2011

Perovskite and Mn oxide nanosheet-based electrocatalysts were synthesized as the cathode of anion-exchange membrane fuel cells (AEMFCs), and their oxygen reduction reaction (ORR) activities and AMFC performances were evaluated. Perovskite La0.6Sr0.4MnO3 (LS0.4M/KB) loaded on Ketjen Black exhibited the highest ORR activity (onset potential: ca. 0.9 V vs. reversible hydrogen electrode (RHE) and efficiency for 4-electron reduction of O2: > 90%), and achieved a maximum power density of ca. 92 mW cm-2.
Investigation of Titanium Supported Au-Ni and Pt-Ni Bimetallic Nanoparticles as Electrocatalysts for Direct Borohydride Fuel Cells
Authors: Tamašauskaitė-Tamašiu¯naitė Loreta , Balčiu¯naitė Aldona , Cekaviciu¯tė Rasa , Selskis Algirdas
Published: October 2011

Here we report the study and use of titanium supported Au-Ni and Pt-Ni nanoparticles as electrocatalysts for direct borohydride fuel cells. The electrocatalysts with different amounts of Au and Pt nanoparticles, respectively, were fabricated on titanium surface through galvanic displacement reactions between hierarchical Ni thin films prepared by electroless deposition and solutions of HAuCl4 and H2PtCl6. The surface morphology and composition of the catalysts were examined using scanning electron microscopy and energy dispersive X-ray spectroscopy. The electrocatalytic activity of these catalysts was evaluated towards borohydride oxidation by means of cyclic voltammetry, chronoamperometry and chronopotentiometry. The fabricated nano-Au(Ni)/Ti and nano-Pt(Ni)/Ti catalysts exhibit an enhanced electrochemical activity towards electrochemical oxidation of borohydride as compared to that of bulk Au and Pt electrodes.
Electrocatalytic Activity for Oxygen Reduction Reaction of Au Core/Pt Shell Catalysts
Authors: Inoue Hiroshi , Hayashi Kiyoaki , Chiku Masanobu , Higuchi Eiji
Published: October 2011

Au nanoparticles-loaded carbon black (Au/CB) was prepared by bubbling CO as a reducing agent in KAuCl4 aqueous solutions containing various stabilizers and then being loaded on CB. After CO bubbling, an edge peak due to surface plasmon resonance was observed in UV-Vis absorption spectra. The lowest peak wavelength was observed with PVA, indicating the formation of the smallest nanoparticles. Transmission electron microscopy revealed that the size and its distribution of the Au nanoparticles on CB was 3.3 ± 0.7 nm. Pt monolayers were deposited on the Au/CB nanoparticles (Ptx/Au/CB (x= number of monolayers)) by the Cu-underpotential deposition method and then galvanic replacement with Pt. The activity per unit mass of Pt for the oxygen reduction reaction at 0.9 V vs. RHE for the Pt1/Au/CB was 5.1 times as high as that of commercial Pt/CB. The durability against Pt dissolution for the Ptx/Au/CB electrodes was equivalent or superior to that for the commercial Pt/CB electrode.
Electrochemical Studies of Novel Pt/Ceria/C Oxygen Reduction Catalysts for Fuel Cells
Authors: Chlistunoff Jerzy , Wilson Mahlon , Garzón Fernando
Published: October 2011

Novel Pt/ceria/carbon catalysts with sub-2 nm ceria crystallites embedded in carbon matrixes, recently developed at Los Alamos National Laboratory, were studied in aqueous acidic media using rotating ring disk electrode (RRDE) and voltammetric techniques. The ceria nanophase was either pure or doped with trivalent gadolinium or praseodymium. The catalysts with lower Pt contents (3.8-5%) had higher specific surface areas and performed better than those with higher Pt contents (≥8.5%). The doping with either Pr or Gd was found to improve the catalyst specific surface area, whereas Pr doped catalysts exhibited higher specific activities in oxygen reduction reaction (ORR) than non doped and Gd doped catalysts. The former are also more selective for four-electron ORR. The presence of ceria in the catalyst support was found to increase the catalyst tolerance to CO poisoning.
Translational control mechanisms in metabolic regulation: critical role of RNA binding proteins, microRNAs, and cytoplasmic RNA granules
Authors: Adeli Khosrow
Published: October 2011

Regulated cell metabolism involves acute and chronic regulation of gene expression by various nutritional and endocrine stimuli. To respond effectively to endogenous and exogenous signals, cells require rapid response mechanisms to modulate transcript expression and protein synthesis and cannot, in most cases, rely on control of transcriptional initiation that requires hours to take effect. Thus, co- and posttranslational mechanisms have been increasingly recognized as key modulators of metabolic function. This review highlights the critical role of mRNA translational control in modulation of global protein synthesis as well as specific protein factors that regulate metabolic function. First, the complex lifecycle of eukaryotic mRNAs will be reviewed, including our current understanding of translational control mechanisms, regulation by RNA binding proteins and microRNAs, and the role of RNA granules, including processing bodies and stress granules. Second, the current evidence linking regulation of mRNA translation with normal physiological and metabolic pathways and the associated disease states are reviewed. A growing body of evidence supports a key role of translational control in metabolic regulation and implicates translational mechanisms in the pathogenesis of metabolic disorders such as type 2 diabetes. The review also highlights translational control of apolipoprotein B (apoB) mRNA by insulin as a clear example of endocrine modulation of mRNA translation to bring about changes in specific metabolic pathways. Recent findings made on the role of 5′-untranslated regions (5′-UTR), 3′-UTR, RNA binding proteins, and RNA granules in mediating insulin regulation of apoB mRNA translation, apoB protein synthesis, and hepatic lipoprotein production are discussed.
Mesenchymal stem cell transplantation for the infarcted heart: a role in minimizing abnormalities in cardiac-specific energy metabolism
Authors: Hughey Curtis C. , Johnsen Virginia L. , Ma Lianli , James Freyja D. , Young Pampee P. , Wasserman David H. , Rottman Jeffrey N. , Hittel Dustin S. , Shearer Jane
Published: October 2011

Intense interest has been focused on cell-based therapy for the infarcted heart given that stem cells have exhibited the ability to reduce infarct size and mitigate cardiac dysfunction. Despite this, it is unknown whether mesenchymal stem cell (MSC) therapy can prevent metabolic remodeling following a myocardial infarction (MI). This study examines the ability of MSCs to rescue the infarcted heart from perturbed substrate uptake in vivo. C57BL/6 mice underwent chronic ligation of the left anterior descending coronary artery to induce a MI. Echocardiography was performed on conscious mice at baseline as well as 7 and 23 days post-MI. Twenty-eight days following the ligation procedure, hyperinsulinemic euglycemic clamps assessed in vivo insulin sensitivity. Isotopic tracer administration evaluated whole body, peripheral tissue, and cardiac-specific glucose and fatty acid utilization. To gain insight into the mechanisms by which MSCs modulate metabolism, mitochondrial function was assessed by high-resolution respirometry using permeabilized cardiac fibers. Data show that MSC transplantation preserves insulin-stimulated fatty acid uptake in the peri-infarct region (4.25 ± 0.64 vs. 2.57 ± 0.34 vs. 3.89 ± 0.54 μmol·100 g−1·min−1, SHAM vs. MI + PBS vs. MI + MSC; P < 0.05) and prevents increases in glucose uptake in the remote left ventricle (3.11 ± 0.43 vs. 3.81 ± 0.79 vs. 6.36 ± 1.08 μmol·100 g−1·min−1, SHAM vs. MI + PBS vs. MI + MSC; P < 0.05). This was associated with an enhanced efficiency of mitochondrial oxidative phosphorylation with a respiratory control ratio of 3.36 ± 0.18 in MSC-treated cardiac fibers vs. 2.57 ± 0.14 in the infarct-only fibers ( P < 0.05). In conclusion, MSC therapy exhibits the potential to rescue the heart from metabolic aberrations following a MI. Restoration of metabolic flexibility is important given the metabolic demands of the heart and the role of energetics in the progression to heart failure.
The function of neuromuscular compartments in human shoulder muscles
Authors: Wickham J. B. , Brown J. M. M.
Published: October 2011

The aim of this study was to use a surface electromyographic (sEMG) technique with a ballistic isotonic shoulder joint adduction movement to determine the function of the neuromuscular compartments (NMCs) within the pectoralis major, deltoid, and latissimus dorsi muscles. Sixteen male subjects (mean age 22 yr) with no known history of shoulder pathologies volunteered to participate. Timing and intensity of muscle contraction, recorded with 15 pairs of bipolar sEMG electrodes, were compared during performance of 40° coronal-plane ballistic [movement time (MT) < 400 ms] shoulder joint adduction movements. The results suggested that heterogeneous sEMG was present across the breadth of all three muscles, indicating the presence of individual NMCs with significant ( P < 0.05) differences observed within the three muscles in NMC onset, duration, timing of peak NMC intensity, or relative intensity of NMC activation. For example, within the deltoid NMC activation was closely related to moment arm (MA) length with the NMC, with the largest antagonist MA deltoid NMC3 having a late period of activation [antagonist (Ant)] to slow glenohumeral joint (GHJ) rotation and maintain its final joint position [with agonist 2 burst (Ag2)]. The most obvious triphasic EMG patterns (e.g., Ag1-Ant-Ag2) were observed between the first NMCs activated in the two agonist muscles and the last NMC activated in the antagonist deltoid muscle. In conclusion, our findings suggest the presence of in-parallel NMCs within the superficial muscles of the GHJ and show that biomechanical parameters, such as the MA at end-point movement position, influence the function of each NMC and its contribution to alternating patterns of agonist and antagonist muscle activity typical of ballistic movement.
Assessing the role of inferior olivary sensory signaling in the expression of conditioned eyeblinks using a combined glutamate/GABAA receptor antagonist protocol
Authors: Zbarska Svitlana , Bracha Vlastislav
Published: October 2011

The inferior olive (IO) is a major component of the eyeblink conditioning neural network. The cerebellar learning hypothesis assumes that the IO supplies the cerebellum with a “teaching” unconditioned stimulus input required for the acquisition of the conditioned response (CR) and predicts that inactivating this input leads to the extinction of CRs. Previous tests of this prediction attempted to block the teaching input by blocking glutamatergic sensory inputs in the IO. These tests were inconclusive because blocking glutamate neurotransmission in the IO produces a nonspecific tonic malfunction of cerebellar circuits. The purpose of the present experiment was to examine whether the behavioral outcomes of blocking glutamate receptors in the IO could be counterbalanced by reducing GABA-mediated inhibition in the IO. We found that injecting the IO with the glutamate antagonist γ-d-glutamylglycine (DGG) abolished previously learned CRs, whereas injecting the GABAA receptor antagonist gabazine at the same site did not affect CR incidence but shortened CR latencies and produced tonic eyelid closure. To test whether the glutamate antagonist-induced behavioral deficit could be offset by elevating IO activity with GABAA antagonists, rabbits were first injected with DGG and then with gabazine in the same training session. While DGG abolished CRs, follow-up injections of gabazine accelerated their recovery. These findings suggest that the level of IO neuronal activity is critical for the performance of CRs, and that combined pharmacological approaches that maintain spontaneous activity at near normal levels hold tremendous potential for unveiling the role of IO-mediated signals in eyeblink conditioning.
Determinant Efficiencies in Ill‐Conditioned Models
Authors: Jensen D. R.
Published: October 2011

The canonical correlations between subsets of OLS estimators are identified
with design linkage parameters between their regressors. Known collinearity indices are extended to encompass angles between each regressor vector and remaining vectors. One such angle quantifies the collinearity of regressors with the intercept, of concern
in the corruption of all estimates due to ill‐conditioning. Matrix identities factorize a determinant in terms of principal subdeterminants and the canonical Vector Alienation Coefficients between subset estimators—by duality, the Alienation Coefficients between
subsets of regressors. These identities figure in the study of D and Ds as determinant efficiencies for estimators and their subsets, specifically, Ds‐efficiencies for the constant, linear, pure quadratic, and interactive coefficients in eight known small second‐order
designs. Studies on D‐ and Ds‐efficiencies confirm that designs are seldom efficient for both. Determinant identities demonstrate the propensity for Ds‐inefficient subsets to be masked through near collinearities in overall D‐efficient designs.
Modern Contraceptive and Dual Method Use among HIV-Infected Women in Lusaka, Zambia
Authors: Chibwesha Carla J. , Li Michelle S. , Matoba Christine K. , Mbewe Reuben K. , Chi Benjamin H. , Stringer Jeffrey S. A. , Stringer Elizabeth M.
Published: October 2011

HIV-infected women in sub-Saharan Africa are at substantial risk of unintended pregnancy and sexually transmitted infections (STIs). Linkages between HIV and reproductive health services are advocated. We describe implementation of a reproductive health counseling intervention in 16 HIV clinics in Lusaka, Zambia. Between November 2009 and November 2010, 18,407 women on antiretroviral treatment (ART) were counseled. The median age was 34.6 years (interquartile range (IQR): 29.9–39.7), and 60.1% of women were married. The median CD4+cell count was 394 cells/uL (IQR: 256–558). Of the women counseled, 10,904 (59.2%) reported current modern contraceptive use. Among contraceptive users, only 17.7% reported dual method use. After counseling, 737 of 7,503 women not previously using modern contraception desired family planning referrals, and 61.6% of these women successfully accessed services within 90 days. Unmet contraceptive need remains high among HIV-infected women. Additional efforts are needed to promote reproductive health, particularly dual method use.
Metals and Disease: A Global Primary Health Care Perspective
Authors: Mamtani Ravinder , Stern Penny , Dawood Ismail , Cheema Sohaila
Published: October 2011

Metals are an important and essential part of our daily lives. Their ubiquitous presence and use has not been without significant consequences. Both industrial and nonindustrial exposures to metals are characterized by a variety of acute and chronic ailments. Underreporting of illnesses related to occupational and environmental exposures to chemicals including metals is of concern and presents a serious challenge. Many primary care workers rarely consider occupational and environmental exposures to chemicals in their clinical evaluation. Their knowledge and training in the evaluation of health problems related to such exposures is inadequate. This paper presents documented research findings from various studies that have examined the relationship between metal exposures and their adverse health effects both in developing and developed countries. Further, it provides some guidance on essential elements of a basic occupational and environmental evaluation to health care workers in primary care situations.
Cell Transformation and the Evolution of a Field of Precancerization As It Relates to Oral Leukoplakia
Authors: Feller L. , Lemmer J.
Published: October 2011

Potentially malignant oral leukoplakias arise within precancerized epithelial fields consisting of cytogenetically altered keratinocytes at various stages of transformation. The evolution of a clone of keratinocytes culminating in a precancerous phenotype is a function of the number of mutagenic events, rather than the sequential order in which they occur. The altered molecular configurations of the transformed precancerous keratinocytes may confer upon them a growth advantage in relation to the unaltered neighbouring keratinocytes. Replicative clonal expansion of these keratinocytes results in the progressive replacement of the surrounding normal keratinocytes by the fitter clone or clones of altered cells. The precancerized oral epithelial field may have a clinically normal appearance and microscopically may be normal or may show dysplasia. Oral leukoplakias arising within a precancerized epithelial field in which the keratinocytes show DNA aneuploidy or loss of heterozygosity at certain specific chromosomal loci have the potential to progress to carcinoma. The pathogenic mechanisms that drive the carcinomatous transformation of oral leukoplakias, in which cytogenetic alterations in the keratinocytes cannot be detected, are unknown.
Both Basic and Acidic Amino Acid Residues of IpTxa Are Involved in Triggering Substate of RyR1
Authors: Seo In Ra , Kang Dae Eun , Song Dong Woo , Kim Do Han
Published: October 2011

Imperatoxin A (IpTxa) is known to modify the gating of skeletal ryanodine receptor (RyR1). In this paper, the ability of charged aa residues of IpTxa to induce substate of native RyR1 in HSR was examined. Our results show that the basic residues (e.g., Lys19, Lys20, Lys22, Arg23, and Arg24) are important for producing substate of RyR1. In addition, other basic residues (e.g., Lys30, Arg31, and Arg33) near the C‐terminus and some acidic residues (e.g., Glu29, Asp13, and Asp2) are also involved in the generation of substate. Residues such as Lys8 and Thr26 may be involved in the self‐regulation of substate of RyR1, since alanine substitution of the aa residues led to a drastic conversion to the substate. The modifications of the channel gating by the wild‐type and mutant toxins were similar in purified RyR1. Taken together, the specific charge distributions on the surface of IpTxa are essential for regulation of the channel gating of RyR1.
TFE3 Translocation-Associated Renal Cell Carcinoma Presenting as Avascular Necrosis of the Femur in a 19-Year-Old Patient: Case Report and Review of the Literature
Authors: Nelius T. , Al-Khalil I. , Vordermark J. , Rinard-Holden K. , Cammack T. , Mamlok V. , Filleur S.
Published: October 2011

In the United States, renal cell carcinoma (RCC) accounts for approximately 3% of adult malignancies and 90–95% of all neoplasms arising from the kidney. According to the National Cancer Institute, 58 240 new cases and 13 040 deaths from renal cancer will occur in 2010. RCC usually occurs in older adults between the ages of 50 and 70 and is rare in young adults and children. We describe a case of a TFE3 translocation-associated RCC in a 19-year-old patient presenting as avascular necrosis of the femur. Due to the rarity of this malignancy, we present this case including a review of the existing literature relative to diagnosis and treatment.
Approximate Solutions of Klein-Gordon Equation with Kratzer Potential
Authors: Hassanabadi H. , Rahimov H. , Zarrinkamar S.
Published: October 2011

Approximate solutions of theD-dimensional Klein-Gordon equation are obtained for the scalar and vector general Kratzer potential for anylby using the ansatz method. The energy behavior is numerically discussed.
Bulk-Brane Matching in Bianchi-Types Brane World
Authors: Sevinc O. , Gudekli E.
Published: October 2011

We discuss a comprehensive description of the geometry of the brane-world cosmologies, and present bulk and brane structure and matching between brane and bulk metrics. It is clear that the possibility of the matching condition is not always obvious and therefore it requires a separate analysis. In this study we have shown, under the assumption of consideration of the anisotropic metric except Kasner-AdS like, matching procedure is not achieved for Bianchi-types bulk metrics. Examples of this result are presented by the illustrations of the Bianchi-types II and V bulk metrics.
Intravenous Thrombolysis in Ischemic Stroke Patients with Intracranial Neoplasms: Two Cases and a Literature Review
Authors: Neil William , Ovbiagele Bruce
Published: October 2011

Based on exclusion criteria in the landmark NINDS-rtPA trial, current expert consensus guidelines preclude the use of intravenous recombinant tissue plasminogen activator (IV rtPA) in acute ischemic stroke (AIS) patients with intracranial neoplasm. There are only 3 published cases of administration of IV rtPA to AIS patients with intracranial neoplasms in the literature. Two of these published cases involved malignant brain parenchymal lesions discovered only after rtPA was inadvertently given, and one of these cases was associated with hemorrhage within the tumor. In this paper, we report two cases of administration of IV rtPA in AIS patients with intracranial neoplasms observed on neuroimaging prior to IV rtPA administration. In both cases, the tumor was outside of the brain parenchyma. The first case was an acoustic schwannoma and the second a falcine meningioma. Neither case was associated with intratumoral hemorrhage as of at least one week following IV rtPA treatment. More published cases are definitely warranted, but our experience with these two cases suggests that administration of IV rtPA to AIS patients in the presence of extraparenchymal brain tumors may not necessarily precipitate intra-tumoral bleeding and thereby worsen clinical outcomes.
Analytical Behavior Prediction for Skewed Thick Plates on Elastic Foundation
Authors: Chun Pang-jo , Lim Yun Mook
Published: October 2011

This paper presents analytical solutions for the problem of skewed thick plates under transverse load on a Winkler foundation, which has not been reported in the literature. The thick plate solution is obtained by using a framework of an oblique coordinate system. First, the governing differential equation in that system is derived, and the solution is obtained using deflection and rotation as derivatives of the potential function developed here. This method is applicable for arbitrary loading conditions, boundary conditions, and materials. The solution technique is applied to two illustrative application examples, and the results are compared with numerical solutions. The two approaches yielded results in good agreement.
Homotopy Perturbation Method for Solving Wave‐Like Nonlinear Equations with Initial‐Boundary Conditions
Authors: Aslanov Afgan
Published: October 2011

The homotopy perturbation method is employed to obtain approximate analytical solutions of the wave‐like nonlinear equations with initial‐boundary conditions. An efficient way of choosing the auxiliary operator is presented. The
results demonstrate reliability and efficiency of the method.
Geometric Integrability of Some Generalizations of the Camassa‐Holm Equation
Authors: Christov Ognyan
Published: October 2011

We study the Camassa‐Holm (CH) equation and recently introduced μCH equation from the geometric point of view. We show that Kupershmidt deformations of these equations describe pseudospherical surfaces and hence are geometrically integrable.
Weighted Transition Based Reordering, Columnwise Bit Filling, and Difference Vector: A Power-Aware Test Data Compression Method
Authors: Mehta Usha , Dasgupta K. S. , Devashrayee N. M.
Published: October 2011

Test data compression is the major issues for the external testing of IP core-based SoC. From a large pool of diverse available techniques for compression, run length-based schemes are most appropriate for IP cores. To improve the compression and to reduce the test power, the test data processing schemes like “don't care bit filling” and “reordering” which do not require any modification in internal structure and do not demand use of any test development tool can be used for SoC-containing IP cores with hidden structure. The proposed “Weighted Transition Based Reordering-Columnwise Bit Filling-Difference Vector (WTR-CBF-DV)” is a modification to earlier proposed “Hamming Distance based Reordering—Columnwise Bit Filling and Difference vector.” This new method aims not only at very high compression but also aims at shift in test power reduction without any significant on-chip area overhead. The experiment results on ISCAS89 benchmark circuits show that the test data compression ratio has significantly improved for each case. It is also noteworthy that, in most of the case, this scheme does not involve any extra silicon area overhead compared to the base code with which it used. For few cases, it requires an extra XOR gate and feedback path only. As application of this scheme increases run length of zeroes in test set, as a result, the number of transitions during scan shifting is reduced. This may lower scan power. The proposed scheme can be easily integrated into the existing industrial flow.
Optimal Fuzzy and Dynamics Design of Ecological Sandwich Panel Vessel Roofs
Authors: Martikka Heikki , Taitokari Erkki
Published: October 2011

In this study the basic engineering principles, goals, and constraints are all combined with fuzzy methodology and applied to optimally design sandwich panel circular plate roofs for large vessels loaded statically and dynamically. These panels are made up of two stiff, strong veneer skins separated by vertical and peripheral stiffener plates. Advantages are high strength, lightweight, and sustainability. In the present approach, first the goals and constraints of the end user are identified and expressed as decision variables which are formulated using the engineering variables for materials, geometry, and function. Then same consistent fuzzy satisfaction functions are formed over the desired ranges to suit the customer's desires. The risk of extreme dynamic loadings exciting resonance is studied by natural frequency and mode analysis by FEM and analytical models. The results show the most critical locations and give guidelines for innovative remedies of the concept before detailed FEM analyses to finalize the design.
Colorectal Oncogenesis and Inflammation in a Rat Model Based on Chronic Inflammation due to Cycling DSS Treatments
Authors: Håkansson Åsa , Bränning Camilla , Molin Göran , Adawi Diya , Hagslätt Marie-Louise , Nyman Margareta , Jeppsson Bengt , Ahrné Siv
Published: October 2011

Inflammation is known to be linked with development of colorectal cancer, and the aim was to assess the malignant potential and degree of inflammation in a dextran-sulphate-sodium-(DSS-) induced cyclic colonic tumour model (CTM) in rats and to compare it with the azoxymethane-(AOM-) induced CTM model. Tumours developed in both groups, although, in the DSS group, the colonic mucosa appeared edematous and the number of haemorrhagic erosions and quantity of dysplastic lesions were higher as well as the mucosal concentration of myeloperoxidase and faecal viable count ofEnterobacteriaceae. The livers were affected as evaluated by steatosis, parenchymal loss, haemorrhage, and inflammatory infiltrations, and higher proportions of acetate and lower proportions of butyrate in colonic content were found. The DSS model seems to mimic the clinical situation and may be valuable for investigation of inflammation-related dysplasia and colon cancer, as well as for altered liver function by endogenous inflammatory mediators.
H∞ Observers Design for a Class of Continuous Time Nonlinear Singular Systems
Authors: Zerrougui Mohamed , Boutat-Baddas Latifa , Darouach Mohamed
Published: October 2011

This paper considers
the problem of H∞ observers
design for a class of Lipschitz continuous
nonlinear singular systems. The method is based
on the parameterization of the solution of the
generalized Sylvester equations obtained from
the estimation errors. Sufficient conditions for
the existence of the observers which guarantee
stability and the worst case observers error
energy over all bounded energy disturbances is
minimized are given. The approach also unifies
the full‐order, the reduced‐order, and the
minimal‐order observers design. The solutions
are obtained through linear matrix inequalities
(LMIs) formulation. A numerical example is
given to illustrate our results.
Oxidative Stress Induced by MnSOD-p53 Interaction: Pro- or Anti-Tumorigenic?
Authors: Robbins Delira , Zhao Yunfeng
Published: October 2011

The formation of reactive oxygen species (ROS) is a result of incomplete reduction of molecular oxygen during cellular metabolism. Although ROS has been shown to act as signaling molecules, it is known that these reactive molecules can act as prooxidants causing damage to DNA, proteins, and lipids, which over time can lead to disease propagation and ultimately cell death. Thus, restoring the protective antioxidant capacity of the cell has become an important target in therapeutic intervention. In addition, a clearer understanding of the disease stage and molecular events that contribute to ROS generation during tumor promotion can lead to novel approaches to enhance target specificity in cancer progression. This paper will focus on not only the traditional routes of ROS generation, but also on new mechanisms via the tumor suppressor p53 and the interaction between p53 and MnSOD, the primary antioxidant enzyme in mitochondria. In addition, the potential consequences of the p53-MnSOD interaction have also been discussed. Lastly, we have highlighted clinical implications of targeting the p53-MnSOD interaction and discussed recent therapeutic mechanisms utilized to modulate both p53 and MnSOD as a method of tumor suppression.
A Model of Tuberculosis Screening for Pregnant Women in Resource-Limited Settings Using Xpert MTB/RIF
Authors: Turnbull Eleanor R. , Kancheya Nzali G. , Harris Jennifer B. , Topp Stephanie M. , Henostroza German , Reid Stewart E.
Published: October 2011

Timely diagnosis and treatment of maternal tuberculosis (TB) is important to reduce morbidity and mortality for both the mother and child, particularly in women who are coinfected with HIV. The World Health Organization (WHO) recommends the integration of TB/HIV screening into antenatal services but available diagnostic tools are slow and insensitive, resulting in delays in treatment initiation. Recently the WHO endorsed Xpert MTB/RIF, a highly sensitive, real-time PCR assay forMycobacterium tuberculosisthat simultaneously detects rifampicin resistance directly from sputum and provides results within 100 minutes. We propose a model for same-day TB screening and diagnosis of all pregnant women at antenatal care using Xpert MTB/RIF. Pilot studies are urgently required to evaluate strategies for the integration of TB screening into antenatal clinics using new diagnostic technologies.
Three-Dimensional Anatomic Evaluation of the Anterior Cruciate Ligament for Planning Reconstruction
Authors: Hoshino Yuichi , Kim Donghwi , Fu Freddie H.
Published: October 2011

Anatomic study related to the anterior cruciate ligament (ACL) reconstruction surgery has been developed in accordance with the progress of imaging technology. Advances in imaging techniques, especially the move from two-dimensional (2D) to three-dimensional (3D) image analysis, substantially contribute to anatomic understanding and its application to advanced ACL reconstruction surgery. This paper introduces previous research about image analysis of the ACL anatomy and its application to ACL reconstruction surgery. Crucial bony landmarks for the accurate placement of the ACL graft can be identified by 3D imaging technique. Additionally, 3D-CT analysis of the ACL insertion site anatomy provides better and more consistent evaluation than conventional “clock-face” reference and roentgenologic quadrant method. Since the human anatomy has a complex three-dimensional structure, further anatomic research using three-dimensional imaging analysis and its clinical application by navigation system or other technologies is warranted for the improvement of the ACL reconstruction.
Reorganization of Extracellular Matrix in Placentas from Women with Asymptomatic Chagas Disease: Mechanism of Parasite Invasion or Local Placental Defense?
Authors: Duaso Juan , Yanez Erika , Castillo Christian , Galanti Norbel , Cabrera Gonzalo , Corral Gabriela , Maya Juan Diego , Zulantay Inés , Apt Werner , Kemmerling Ulrike
Published: October 2011

Chagas disease, produced by the protozoanTrypanosoma cruzi(T. cruzi), is one of the most frequent endemic diseases in Latin America. In spite the fact that in the past few yearsT. cruzicongenital transmission has become of epidemiological importance, studies about this mechanism of infection are scarce. In order to explore some morphological aspects of this infection in the placenta, we analyzed placentas fromT. cruzi-infected mothers by immunohistochemical and histochemical methods. Infection in mothers, newborns, and placentas was confirmed by PCR and by immunofluorescence in the placenta.T. cruzi-infected placentas present destruction of the syncytiotrophoblast and villous stroma, selective disorganization of the basal lamina, and disorganization of collagen I in villous stroma. Our results suggest that the parasite induces reorganization of this tissue component and in this way may regulate both inflammatory and immune responses in the host. Changes in the ECM of placental tissues, together with the immunological status of mother and fetus, and parasite load may determine the probability of congenital transmission ofT. cruzi.
The Chylomicron: Relationship to Atherosclerosis
Authors: Tomkin Gerald H. , Owens Daphne
Published: October 2011

The B-containing lipoproteins are the transporters of cholesterol, and the evidence suggests that the apo B48-containing postprandial chylomicron particles and the triglyceride-rich very low density lipoprotein (VLDL) particles play an important part in the development of the plaque both directly and indirectly by their impact on LDL composition. The ratio of dietary to synthesised cholesterol is variable but tightly regulated: hence intervention with diet at best reduces serum cholesterol by <20% andusually <10%. Statins are the mainstay of cholesterol reduction therapy, but they increase cholesterol absorption, an example of the relationship between synthesis and absorption. Inhibition of cholesterol absorption with Ezetimibe, an inhibitor of Niemann Pick C1-like 1 (NPC1-L1), the major regulator of cholesterol absorption, increases cholesterol synthesis and hence the value of adding an inhibitor of cholesterol absorption to an inhibitor of cholesterol synthesis. Apo B48, the structural protein of the chylomicron particle, is synthesised in abundance so that the release of these particles is dependent on the amount of cholesterol and triglyceride available in the intestine. This paper will discuss cholesterol absorption and synthesis, chylomicron formation, and the effect of postprandial lipoproteins on factors involved in atherosclerosis.
In Vivo Disintegration of Four Different Luting Agents
Authors: Gemalmaz Deniz , Pameijer Cornelis H. , Latta Mark , Kuybulu Ferah , Alcan Toros
Published: October 2011

The purpose of this study was to evaluate the disintegration of luting agents. An intraoral sample holder was made having four holes of 1.4 mm diameter and 2 mm depth. The holder was soldered onto the buccal surface of an orthodontic band, which was cemented to the first upper molar in 12 patients, average age 26 years. The holes were filled with a zinc phosphate (Phosphate Kulzer), a glass ionomer (Ketac Cem), a resin-modified-glass ionomer (Fuji Plus), and a resin cement (Calibra). Impressions were made at baseline, and 6, 12, and 18 months from which epoxy replicas were made, which were scanned with an optical scanner. Total volume loss was calculated. The rank order of mean volume loss was as follows: Phosphate cement > Ketac Cem = Fuji Plus = Calibra. Cement type and time had statistically significant effects on volume loss of cements (P<0.001). Under in vivo conditions, zinc phosphate cement disintegrated the most, whereas no significant difference was observed for glass ionomer and resin-based cements. As intraoral conditions are considerably less aggressive than experimental laboratory conditions, the erosion behavior of glass ionomer cement was found to be similar to the resin-based cements in contradiction to previous laboratory results.