bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Two Point-of-Care Lipid Analyzers for Use in Global Cardiovascular Risk Assessments
Authors: Dale Rita A , Jensen Lisa H , Krantz Mori J
Published: April 2008

Background:

Point-of-care (POC) lipid testing is increasingly used in community-and office-based practice. Two analyzers commonly used in the US are CardioChek PA and Cholostech LDX. Both directly measure total cholesterol (TC) and high-density lipoprotein cholesterol (HDL-C), mandatory values in calculating a Framingham Risk Score (FRS). The FRS in turn informs the clinician of the need for lipid-modifying therapy and the degree of therapeutic intensity.

Objective:

To compare the performance of CardioChek PA and Cholestech LDX.

Methods:

Staff members from the Colorado Prevention Center were included in the study, with all having fasted for 12 hours beforo the testing. No medical history was obtained. A venous blood sample was collected for lipid measurements conducted in a laboratory, and 2 finger sticks were obtained at that time and analyzed immediately on-site using the POC analyzers. Intraclass correlation coefficients (ICCs) were determined for each analyzer versus the laboratory analysis, with values greater than 0.75 defined as Indicators of excellent reproducibility. We then assessed how interanalyzer differences in TC or HDL-C impacted the FRS lipid categorization.

Results:

Thirty-four adults (aged 24-56 y) participated in the study. The ICC between Cholestech LDX and the laboratory standard exceeded 075 for all 4 lipid categories (TC, p = 0.96; HDL-C, p = 0.88; low-density lipoprotein cholesterol, ρ = 0.87; triglycerides, ρ = 0.99). By contrast, the only ICC exceeding 0.75 using CardioChek PA was for triglycerides (ρ = 0.84). When applied in calculating the FRS, the Cholestech LDX analyzer misclassified fewer individuals for TC versus the CardioChek PA analyzer (5 vs 21). Overall, Cholestech LDX provided TC and HDL-C values in the correct FRS category more frequently versus CardioChek PA (TC, p < 0.001; HDL-C, p > 0.001). Limitations of the study include use of only 2 POC products and small sample size with no known risk factors. This project does not prove superior accuracy of either device, but reflects a real-world comparison of the analyzers conducted at a single center.

Conclusions:

The Cholestech LDX analyzer demonstrated better reproducibility than the CardioChek PA analyzer when compared with laboratory gold standard analysis and allowed more accurate categorization for FRS. Since results obtained from these analyzers have the potential to impact treatment decisions, larger, prospective, comparative studies seem warranted.
Site-specific Expression of IQGAP1, a Key Mediator of Cytoskeleton, in Mouse Renal Tubules
Authors: Lai Li-Wen , Yong Kim-Chong , Lien Yeong-Hau H.
Published: April 2008

IQGAP1 is a multifunctional junction molecule that is involved in cell migration, proliferation, differentiation, cell polarity, and cell–cell adhesion. It is highly expressed in the kidney and has recently been identified in the glomerular basement membrane as a nephrin-associated protein. However, the distribution of IQGAP1 in renal tubular epithelial cells is unknown. We performed confocal microscopic studies to localize IQGAP1 in each nephron segment using dual immunofluorescence staining with various antibodies against segment-specific markers. We found that IQGAP1 was strongly expressed in the distal convoluted tubule (DCT), collecting duct, and macula densa and moderately in the thick ascending limb and proximal tubule. In the DCT, the IQGAP1–F-actin complex forms a comb-like structure with multiple parallel spikes sitting on the basal membrane. In the macula densa cells, IQGAP1 is strongly expressed in the apical membrane, whereas in type A intercalated cells, IQGAP1 is expressed in the basolateral membrane, where it colocalizes with anion exchanger 1, and in principal cells, it is diffusely expressed. In conclusion, we showed the expression and subcellular localization of IQGAP1 in various nephron segments. The site-specific expression pattern of this potent modulator of multiple biological pathways in the renal tubules suggests that IQGAP1 may have multiple important roles in various renal functions.
C9orf10 Protein, a Novel Protein Component of Purα-containing mRNA-protein Particles (Purα-mRNPs): Characterization of Developmental and Regional Expressions in the Mouse Brain
Authors: Kobayashi Yuriko , Suzuki Keiichi , Kobayashi Hideaki , Ohashi Sachiyo , Koike Katsuya , Macchi Paolo , Kiebler Michael , Anzai Kaijiro
Published: April 2008

Purα has been implicated in mRNA transport and translation in neurons. We previously reported that Purα is a component of mRNA/protein complexes (Purα-mRNPs) with several other proteins. Among them, we found the C9orf10 ( Homo sapiens chromosome 9 open reading frame 10) protein, which was recently characterized as a component of RNA-containing structures. However, C9orf10 itself remains poorly understood. To characterize C9orf10 expression at the protein level, we raised an antibody against C9orf10 and compared the spatial and developmental expressions of this protein and Purα in the mouse brain. C9orf10 was expressed as early as embryo stage 12, whereas Purα was expressed from 5 days after birth. In adults, C9orf10 expression was most prominent in the hippocampus, caudate putamen, cerebral cortex, and cerebellum, unlike the uniform distribution of Purα. C9orf10-positive cells also showed immunoreactivity to Purα. C9orf10 expression was restricted to neurons, judging by the immunoreactivity to neuron-specific nuclear protein or CaM kinase II. These observations suggest an accessory role of C9orf10 for Purα in a limited brain region in addition to other possible functions that have not yet been determined.
Leptin and the Obesity Receptor (OB-R) in the Small Intestine and Colon: A Colocalization Study
Authors: Hansen Gert H. , Niels-Christiansen Lise-Lotte , Danielsen E. Michael
Published: April 2008

Leptin is a hormone that plays an important role in overall body energy homeostasis, and the obesity receptor, OB-R, is widely distributed in the organism. In the intestine, a multitude of leptin actions have been reported, but it is currently unclear to what extent the hormone affects the intestinal epithelial cells by an endocrine or exocrine signaling pathway. To elucidate this, the localization of endogenous porcine leptin and OB-R in enterocytes and colonocytes was studied. By immunofluorescence microscopy, both leptin and OB-R were mainly observed in the basolateral membrane of enterocytes and colonocytes but also in the apical microvillar membrane of the cells. By electron microscopy, coclustering of hormone and receptor in the plasma membrane and localization in endosomes was frequently detected at the basolateral surface of the epithelial cells, indicative of leptin signaling activity. In contrast, coclustering occurred less frequently at the apical cell surface, and subapical endosomal localization was hardly detectable. We conclude that leptin action in intestinal epithelial cells takes place at the basolateral plasma membrane, indicating that the hormone uses an endocrine pathway both in the jejunum and colon. In contrast, the data obtained did not provide evidence for an exocrine, lumenal action of the hormone in the intestine.
Production and Histological Application of Affinity-purified Antibodies to Heat-denatured Green Fluorescent Protein
Authors: Nakamura Kouichi C. , Kameda Hiroshi , Koshimizu Yoshinori , Yanagawa Yuchio , Kaneko Takeshi
Published: April 2008

Enhanced green fluorescent protein (GFP) irreversibly loses not only fluorescence but also antigenicity recognized with conventional anti-GFP antibodies by heat denaturation. This hinders combinatory applications of the GFP immunodetection technique with heat-requiring procedures, such as in situ hybridization histochemistry, antigen retrieval, and Western blot. Here we produced new rabbit and guinea pig antibodies against heat-denatured GFP. The polyclonal antibodies affinity-purified with the antigen column detected a single band corresponding to the molecular size of GFP in Western blot analysis, with mouse brain expressing GFP from the GAD67 locus. By immunofluorescence labeling, the new antibodies detected GFP molecules in heat (≥70C)-treated sections but not in untreated sections of the mouse brain. When the sections were incubated at ≥37C with in situ hybridization buffer containing 50% formamide, a denaturing reagent, the sections lost immunoreactivity with the conventional anti-GFP antibodies but acquired immunoreactivity with the new antibodies to heat-denatured GFP. Finally, GFP immunofluorescence was successfully visualized with the new antibodies in sections of the GFP-expressing mice labeled by fluorescence in situ hybridization histochemistry against GAD67 mRNA. Thus, the antibodies produced in this study may provide an opportunity to combine GFP immunodetection with procedures requiring heat treatment. This manuscript contains online supplemental material at http://www.jhc.org . Please visit this article online to view these materials.
Phenotypic and Genetic Characterization of Circulating Tumor Cells by Combining Immunomagnetic Selection and FICTION Techniques
Authors: Campos María , Prior Celia , Warleta Fernando , Zudaire Isabel , Ruíz-Mora Jesús , Catena Raúl , Calvo Alfonso , José J. Gaforio
Published: April 2008

The presence of circulating tumor cells (CTCs) in breast cancer patients has been proven to have clinical relevance. Cytogenetic characterization of these cells could have crucial relevance for targeted cancer therapies. We developed a method that combines an immunomagnetic selection of CTCs from peripheral blood with the fluorescence immunophenotyping and interphase cytogenetics as a tool for investigation of neoplasm (FICTION) technique. Briefly, peripheral blood (10 ml) from healthy donors was spiked with a predetermined number of human breast cancer cells. Nucleated cells were separated by double density gradient centrifugation of blood samples. Tumor cells (TCs) were immunomagnetically isolated with an anti-cytokeratin antibody and placed onto slides for FICTION analysis. For immunophenotyping and genetic characterization of TCs, a mixture of primary monoclonal anti-pancytokeratin antibodies was used, followed by fluorescent secondary antibodies, and finally hybridized with a TOP2A/HER-2/CEP17 multicolor probe. Our results show that TCs can be efficiently isolated from peripheral blood and characterized by FICTION. Because genetic amplification of TOP2A and ErbB2 (HER-2) in breast cancer correlates with response to anthracyclines and herceptin therapies, respectively, this novel methodology could be useful for a better classification of patients according to the genetic alterations of CTCs and for the application of targeted therapies.
Rapid Microwave Fixation of Cell Monolayers Preserves Microtubule-associated Cell Structures
Authors: Reipert Siegfried , Kotisch Harald , Wysoudil Bhuma , Wiche Gerhard
Published: April 2008

Microwave (MW) fixation has been suggested as a method to rapidly immobilize cellular dynamics for fine structural studies in the electron microscope. To show its suitability for studies on cell monolayers, one has to apply MW fixation systematically in correlation with samples on the light microscopy level. Examples for MW fixation of cell monolayers, however, are still rare. MW-accelerated fixation for relatively long periods of time (1–2 min) has been reported without showing its suitability at the fine structural level. Here, we provide a rapid MW fixation protocol for cell monolayers on a subminute time scale. The impact of the MW-accelerated glutaraldehyde fixation on temperature-sensitive cytoskeletal components such as microtubules was evaluated. For testing the effectiveness of MW-assisted primary fixation, saponin treatment of the monolayers was included. Simultaneous MW-accelerated fixation and extraction by saponin was necessary to achieve a gradual improvement in visualization of cytoskeletal aspects in association with cell junctions, mitochondria, and centrioles. To establish a valuable routine program for fine structural studies of resin-embedded cell models on substrata, a protocol combining MW fixation with automatic processing in a tissue processor is provided.
α-Synuclein Alters Notch-1 Expression and Neurogenesis in Mouse Embryonic Stem Cells and in the Hippocampus of Transgenic Mice
Authors: Crews Leslie , Mizuno Hideya , Desplats Paula , Rockenstein Edward , Adame Anthony , Patrick Christina , Winner Beate , Winkler Juergen , Masliah Eliezer
Published: April 2008

Altered expression and mutations in α-synuclein (α-syn) have been linked to Parkinson's disease (PD) and related disorders. The neurological alterations in PD patients have been associated with degeneration of dopaminergic cells and other neuronal populations. Moreover, recent studies in murine models have shown that alterations in neurogenesis might also contribute to the neurodegenerative phenotype. However, the mechanisms involved and the effects of α-syn expression on neurogenesis are not yet clear. To this end, murine embryonic stem (mES) cells were infected with lentiviral (LV) vectors expressing wild-type (WT) and mutant α-syn. Compared with mES cells infected with LV–green fluorescent protein (GFP), cells expressing WT and mutant α-syn showed reduced proliferation as indicated by lower 5-bromo-2′-deoxyuridine uptake, increased apoptosis, and reduced expression of neuronal markers such as neuron specific enolase and β-III tubulin. The alterations in neurogenesis in α-syn-expressing mES cells were accompanied by a reduction in Notch-1 and Hairy and enhancer of split-5 (Hes-5) mRNA and protein levels. Moreover, levels of total Notch-1 and Notch intracellular domain (NICD) were lower in mES cells expressing WT and mutant α-syn compared with GFP controls. The reduced survival of α-syn-expressing mES cells was reverted by overexpressing constitutively active NICD. Similarly, in α-syn transgenic mice, the alterations in neurogenesis in the hippocampal subgranular zone were accompanied by decreased Notch-1, NICD, and Hes-5 expression. Together, these results suggest that accumulation of α-syn might impair survival of NPCs by interfering with the Notch signaling pathway. Similar mechanisms could be at play in PD and Lewy body disease.
Dopamine Activates the Motor Pattern for Crawling in the Medicinal Leech
Authors: Puhl Joshua G. , Mesce Karen A.
Published: April 2008

Locomotion in segmented animals is thought to be based on the coupling of “unit burst generators,” but the biological nature of the unit burst generator has been revealed in only a few animal systems. We determined that dopamine (DA), a universal modulator of motor activity, is sufficient to activate fictive crawling in the medicinal leech, and can exert its actions within the smallest division of the animal's CNS, the segmental ganglion. In the entire isolated nerve cord or in the single ganglion, DA induced slow antiphasic bursting (∼15 s period) of motoneurons known to participate in the two-step elongation–contraction cycle underlying crawling behavior. During each cycle, the dorsal (DE-3) and ventral (VE-4) longitudinal excitor motoneurons fired ∼180° out of phase from the ventrolateral circular excitor motoneuron (CV), which marks the elongation phase. In many isolated whole nerve cords, DE-3 bursting progressed in an anterior to posterior direction with intersegmental phase delays appropriate for crawling. In the single ganglion, the dorsal (DI-1) and ventral (VI-2) inhibitory longitudinal motoneurons fired out of phase with each DE-3 burst, further confirming that the crawl unit burst generator exists in the single ganglion. All isolated ganglia of the CNS were competent to produce DA-induced robust fictive crawling, which typically lasted uninterrupted for 5–15 min. A quantitative analysis indicated that DA-induced crawling was not significantly different from electrically evoked or spontaneous crawling. We conclude that DA is sufficient to activate the full crawl motor program and that the kernel for crawling resides within each segmental ganglion.
Neurturin-Mediated Ret Activation Is Required for Retinal Function
Authors: Brantley Milam A. , Jain Sanjay , Barr Emily E. , Johnson Eugene M. , Milbrandt Jeffrey
Published: April 2008

The glial cell line-derived neurotrophic factor (GDNF) family ligands (GFLs) [GDNF, NRTN (neurturin), ARTN (artemin), and PSPN (persephin)] interact with GDNF family receptors (GFRαs) and activate intracellular signaling through the Ret receptor tyrosine kinase. To characterize the role of Ret signaling in retinal activity, we examined Ret hypomorphic and Ret conditional mice using electroretinography. We found that aberrant Ret function resulted in markedly diminished scotopic and photopic responses. Using mice deficient in individual GFLs, we found that only NRTN deficiency led to reduced retinal activity. To determine the potential target cell type for NRTN, we examined the retinal expression of its coreceptors (GFRα1 and GFRα2) and Ret using mice expressing fluorescence reporter enhanced green fluorescent protein from their respective loci. We found robust GFRα1 and Ret expression in horizontal, amacrine, and ganglion cells, whereas GFRα2 expression was only detected in a subset of amacrine and ganglion cells. In contrast to previous studies, no expression of GFRα1, GFRα2, or Ret was detected in photoreceptors or Müller cells, suggesting that these cells are not directly affected by Ret. Finally, detailed morphologic analyses of retinas from NRTN- and Ret-deficient mice demonstrated a reduction in normal horizontal cell dendrites and axons, abnormal extensions of horizontal cell and bipolar cell processes into the outer nuclear layer, and mislocalized synaptic complexes. These anatomic abnormalities indicate a possible basis for the abnormal retinal activity in the Ret and NRTN mutant mice.
Dissociation of Metabolic and Neurovascular Responses to Levodopa in the Treatment of Parkinson's Disease
Authors: Hirano Shigeki , Asanuma Kotaro , Ma Yilong , Tang Chengke , Feigin Andrew , Dhawan Vijay , Carbon Maren , Eidelberg David
Published: April 2008

We compared the metabolic and neurovascular effects of levodopa (LD) therapy for Parkinson's disease (PD). Eleven PD patients were scanned with both [15O]-H2O and [18F]-fluorodeoxyglucose positron emission tomography in the unmedicated state and during intravenous LD infusion. Images were used to quantify LD-mediated changes in the expression of motor- and cognition-related PD covariance patterns in scans of cerebral blood flow (CBF) and cerebral metabolic rate for glucose (CMR). These changes in network activity were compared with those occurring during subthalamic nucleus (STN) deep brain stimulation (DBS), and those observed in a test–retest PD control group. Separate voxel-based searches were conducted to identify individual regions with dissociated treatment-mediated changes in local cerebral blood flow and metabolism. We found a significant dissociation between CBF and CMR in the modulation of the PD motor-related network by LD treatment (p< 0.001). This dissociation was characterized by reductions in network activity in the CMR scans (p< 0.003) occurring concurrently with increases in the CBF scans (p< 0.01). Flow–metabolism dissociation was also evident at the regional level, with LD-mediated reductions in CMR and increases in CBF in the putamen/globus pallidus, dorsal midbrain/pons, STN, and ventral thalamus. CBF responses to LD in the putamen and pons were relatively greater in patients exhibiting drug-induced dyskinesia. In contrast, flow–metabolism dissociation was not present in the STN DBS treatment group or in the PD control group. These findings suggest that flow–metabolism dissociation is a distinctive feature of LD treatment. This phenomenon may be especially pronounced in patients with LD-induced dyskinesia.
Disinhibition Combines with Excitation to Extend the Operating Range of the OFF Visual Pathway in Daylight
Authors: Manookin Michael B. , Beaudoin Deborah Langrill , Ernst Zachary Raymond , Flagel Leigh J. , Demb Jonathan B.
Published: April 2008

Cone signals divide into parallel ON and OFF bipolar cell pathways, which respond to objects brighter or darker than the background and release glutamate onto the corresponding type of ganglion cell. It is assumed that ganglion cell excitatory responses are driven by these bipolar cell synapses. Here, we report an additional mechanism: OFF ganglion cells were driven in part by the removal of synaptic inhibition (disinhibition). The disinhibition played a relatively large role in driving responses at low contrasts. The disinhibition persisted in the presence of CNQX andd-AP-5. Furthermore, the CNQX/d-AP-5-resistant response was blocked byl-AP-4, meclofenamic acid, quinine, or strychnine but not by bicuculline. Thus, the disinhibition circuit was driven by the ON pathway and required gap junctions and glycine receptors but not ionotropic glutamate or GABAAreceptors. These properties implicate the AII amacrine cell, better known for its role in rod vision, as a critical circuit element through the following pathway: cone → ON cone bipolar cell → AII cell → OFF ganglion cell. Rods could also drive this circuit through their gap junctions with cones. Thus, to light decrement, AII cells, driven by electrical synapses with ON cone bipolar cells, would hyperpolarize and reduce glycine release to excite OFF ganglion cells. To light increment, the AII circuit would directly inhibit OFF ganglion cells. These results show a new role for disinhibition in the retina and suggest a new role for the AII amacrine cell in daylight vision.
Ischemic Preconditioning Targets the Respiration of Synaptic Mitochondria via Protein Kinase Cε
Authors: Dave Kunjan R. , DeFazio R. Anthony , Raval Ami P. , Torraco Alessandra , Saul Isabel , Barrientos Antoni , Perez-Pinzon Miguel A.
Published: April 2008

In the brain, ischemic preconditioning (IPC) diminishes mitochondrial dysfunction after ischemia and confers neuroprotection. Activation of ε protein kinase C (εPKC) has been proposed to be a key neuroprotective pathway during IPC. We tested the hypothesis that IPC increases the levels of εPKC in synaptosomes from rat hippocampus, resulting in improved synaptic mitochondrial respiration. Preconditioning significantly increased the level of hippocampal synaptosomal εPKC to 152% of sham-operated animals at 2 d of reperfusion, the time of peak neuroprotection. We tested the effect of εPKC activation on hippocampal synaptic mitochondrial respiration 2 d after preconditioning. Treatment with the specific εPKC activating peptide, tat-ψεRACK (tat-ψε-receptor for activated C kinase), increased the rate of oxygen consumption in the presence of substrates for complexes I, II, and IV to 157, 153, and 131% of control (tat peptide alone). In parallel, we found that εPKC activation in synaptosomes from preconditioned animals resulted in altered levels of phosphorylated mitochondrial respiratory chain proteins: increased serine and tyrosine phosphorylation of 18 kDa subunit of complex I, decreased serine phosphorylation of FeS protein in complex III, increased threonine phosphorylation of COX IV (cytochrome oxidase IV), increased mitochondrial membrane potential, and decreased H2O2production. In brief, ischemic preconditioning promoted significant increases in the level of synaptosomal εPKC. Activation of εPKC increased synaptosomal mitochondrial respiration and phosphorylation of mitochondrial respiratory chain proteins. We propose that, at 48 h of reperfusion after ischemic preconditioning, εPKC is poised at synaptic mitochondria to respond to ischemia either by direct phosphorylation or activation of the εPKC signaling pathway.
A Novel Embryonic Nestin-Expressing Radial Glia-Like Progenitor Gives Rise to Zonally Restricted Olfactory and Vomeronasal Neurons
Authors: Murdoch Barbara , Roskams A. Jane
Published: April 2008

Persistent neurogenesis is maintained throughout development and adulthood in the mouse olfactory epithelium (OE). Despite this, the identity and origin of different embryonic OE progenitors, their spatiotemporal induction and contribution to patterning during development, has yet to be delineated. Here, we show that the embryonic OE contains a novel nestin-expressing radial glia-like progenitor (RGLP) that is not found in adult OE, which is antigenically distinct from embryonic CNS radial glia.Nestin-cre-mediated lineage tracing with three different reporters reveals that only a subpopulation of nestin-expressing RGLPs activate “CNS-specific” nestin regulatory elements, and produce spatially restricted olfactory receptor neurons (ORNs) in zone 1 of the OE, and vomeronasal receptor neurons restricted to the VR1 zone. This dorsal-medial restriction of transgene-activating cells is also seen in the embryonic OE ofNestin-GFPtransgenic mice, in which green fluorescent protein (GFP) is found in a subpopulation of GFP+Mash1+ neuronal progenitors, despite the fact that endogenous Nestin expression is found in RGLPs throughout the OE. Embryonic OE progenitors produce three biologically distinct colony subtypesin vitro, a subpopulation of which include nestin-expressing RGLPs duringin vitrocolony formation. When generated from Nestin-cre/ZEG mice, neurogenic colonies also produce GFP+Mash1+ progenitors and ORNs. We thus identify a novel neurogenic precursor, the RGLP of the OE and vomeronasal organ (VNO), and provide the first evidence for intrinsic differences in the origin and spatiotemporal potential of distinct progenitors during development of the OE and VNO.
Gray Matter Increase Induced by Practice Correlates with Task-Specific Activation: A Combined Functional and Morphometric Magnetic Resonance Imaging Study
Authors: Ilg Rüdiger , Wohlschläger Afra M. , Gaser Christian , Liebau Yasmin , Dauner Ruth , Wöller Andreas , Zimmer Claus , Zihl Josef , Mühlau Mark
Published: April 2008

The neurophysiological basis of practice-induced gray matter increase is unclear. To study the relationship of practice-induced gray matter changes and neural activation, we conducted a combined longitudinal functional and morphometric (voxel-based morphometry) magnetic resonance imaging (MRI) study on mirror reading. Compared with normal reading, mirror reading resulted in an activation of the dorsolateral occipital cortex, medial occipital cortex, superior parietal cortex, medial and dorsolateral prefrontal cortex, as well as anterior insula and cerebellum. Daily practice of 15 min for 2 weeks resulted in an increased performance of mirror reading. After correction for pure performance effects, we found a practice-related decrease of activation at the right superior parietal cortex and increase of activation at the right dorsal occipital cortex. The longitudinal voxel-based morphometry analysis yielded an increase of gray matter in the right dorsolateral occipital cortex that corresponded to the peak of mirror-reading-specific activation. This confirms that short-term gray matter signal increase corresponds to task-specific processing. We speculate that practice-related gray matter signal changes in MRI are primarily related to synaptic remodeling within specific processing areas.
Preparation and Characterization of Mn0.4Ni
x
Zn0.6−x
Fe2O4 Soft Spinel Ferrites for Low and High Frequency Applications by Citrate Precursor Method
Authors: Mathur Preeti , Thakur Atul , Singh Mahavir , Harris G.
Published: April 2008

In the present study, preparation and characterization of Mn-Ni-Zn soft ferrites with chemical formula Mn0.4Ni
x
Zn0.6−x
Fe2O4, where x = 0.0, 0.2 and 0.4, by citrate precursor method has been reported. Microstructural properties studied with the help of X-ray diffraction and scanning electron microscopy show that the samples have almost uniform sized crystallites and have single phase spinel structure. The properties like initial permeability, permeability loss, dielectric constant, dielectric loss are studied as a function of frequency. The d.c. resistivity of the samples is also studied. Variation of d.c. resistivity with composition, x, of the ferrite sample shows that pure zinc ferrite has more resistivity than that of nickel substituted zinc ferrite. The dispersion in the magnetic and electrical properties has been discussed by using various mechanisms, models and theories.
Photosensitization of Colloidal TiO2 with ZnTPP and Pyrene
Authors: Kathiravan A. , Anbazhagan V. , Jhonsi M. Asha , Renganathan R.
Published: April 2008

The interaction of Zinc(II) tetraphenyl porphyrin (ZnTPP) and pyrene with colloidal TiO2 was studied by absorption and fluorescence spectroscopy. Upon excitation of its absorption band, the fluorescence emission of ZnTPP and pyrene was quenched by colloidal TiO2. The bimolecular quenching rate constant (kq
) is 4.09 × 1011 M−1s−1 for ZnTPP and 2.09 × 109 M−1s−1 for pyrene. ZnTPP and pyrene adsorbed on colloidal TiO2 can participate in the sensitization process by injecting electrons from their excited states into the conduction band of TiO2. The mechanism is discussed on the basis of free energy change (ΔGet) obtained from Rehm-Weller equation considering quenching rate constants and conduction band potential of colloidal TiO2.
Mechanistic Studies on the Nucleation of Zinc Sulphide Nanoparticles by Means of XAFS Spectroscopy
Authors: Krishnan Venkata , Camozzo Daniele , Armelao Lidia , Bertagnolli Helmut , Tondello Eugenio , Gross Silvia
Published: April 2008

Mechanistic studies on the nucleation of zinc sulphide nanoparticles from thioacetic acid were performed by means of X-ray absorption fine structure spectroscopy. Solutions of thioacetic acid and zinc salt (acetate or oxide) dissolved in a solvent (acetic acid or acetone) were investigated and compared with the corresponding zinc precursor and crystalline zinc sulphide to study the evolution of the structural environment around the zinc atoms in the solution. The investigations reveal that the coordination of sulphur atoms take place immediately when the mixture is prepared and zinc-sulphur species gradually evolve during the course of the reaction. However, the complete formation of zinc sulphide could not be evidenced even after a considerable period of time. This is likely due to the presence of unreacted zinc-oxygen species. The obtained results indicate that, once dissolved, zinc oxide reacts comparatively faster with thioacetic acid than with zinc acetate and that the choice of the reaction medium plays a crucial role in determining the kinetics and mechanism of zinc sulphide nucleation.
Computing Activity Coefficients of Binary Lennard-Jones Mixtures by Gibbs-Duhem Integration
Authors: Paschek Dietmar , Geiger Alfons , Fischer Jan , Sadowski Gabriele
Published: April 2008

We determine activity coefficients of both components of different binary Lennard-Jones mixtures obtained at T
* = 2.0 and ρ
* = 0.6 by using two different strategies: (i) direct evaluation of the excess chemical potentials of both components applying the potential distribution theorem, and (ii) using the Gibbs-Duhem integration based on the activity coefficients of the counter-component, which was calculated directly from the potential distribution theorem approach. Both methods lead numerically to similar results and therefore offer a route to determine activity coefficients of mixtures with large complex molecules by alternatively calculating chemical potentials of potentially simpler counter-constituents.
Who Is Socrates? Desire and Subversion in David's Death of Socrates (1787)
Authors: Padiyar Satish
Published: April 2008

This essay examines the contradictions involved in projecting an Enlightenment visual image of Socrates. I argue that in J.-L. David's canonical painting of 1787, Death of Socrates, the attempt to project a rational transcendental philosophical subjectivity is contaminated by the irruption of a queer sodomitic sexual desire, and that David's repeated attempt to envision the sexually appetitive embodied philosopher ends in aporia.
Thermochemistry and electrical contact properties at the interface between semiconducting BaTiO3 and (Au–Ti) electrodes
Authors: Cann David P. , Randall Clive A.
Published: April 2008

The interfacial characteristics of positive temperature coefficient of resistance (PTCR) BaTiO3-electrode interfaces were studied. Sessile drop wetting experiments in combination with measurements of the contact resistance of the interface were used to establish a fundamental perspective of the electrode-ceramic interface. It was shown that the thermodynamic work of adhesion Wad), which is the sum of the strengths of chemical interactions present at the interface, can be manipulated by the addition of chemically active elements to the electrode metal which enhance adhesion. This same procedure is shown to modify the important electrical interfacial properties such as the contact resistance.
Investigation of the novel charge transfer complex Cd-TCNQ
Authors: Arena A. , Mezzasalma A. M. , Patanè S. , Saitta G.
Published: April 2008

A novel metal salt of TCNQ (tetracyanoquinodimethane) has been synthesized via an electrochemical process using cadmium as donor. Thin films of the same material have been obtained by evaporating under high vacuum the metal and the organic molecule. The electronic properties of a pellet of the powdered material have been investigated by means of standard UV-VIS-IR spectroscopy, x-ray photoelectron spectroscopy, and Auger electron spectroscopy. The complex shows two absorption structures at about 3.4 eV and 1.7 eV due to the in-plane intramolecular transitions and a shoulder at about 1.4 eV probably due to the bond with the metal. The infrared spectrum is dominated by a deep absorption structure distinctive of the charge transfer. The electrical conductivity of the sample shows a semiconductor behavior in the investigated temperature range; the best fit of the transport data provides an activation energy of about 0.12 eV and shows that at low temperature the electrical conductivity is mainly due to a hopping process among differently charged sites.
Strain compensation by heavy boron doping in Si1–xGex layers grown by solid phase epitaxy
Authors: Rodríguez A. , Rodríguez T. , Sanz-Hervás A. , Kling A. , Soares J. C. , da Silva M. F. , Ballesteros C. , Gwilliam R. M.
Published: April 2008

The strain compensation produced by heavy boron doping in Si1−xGex layers with x = 0.21, 0.26, and 0.34 grown by solid phase epitaxy on (001) Si wafers has been analyzed using high resolution electron microscopy, high resolution x-ray diffractometry, and ion channeling. The structure of the epilayers consists of a defect-free region located next to the layer-substrate interface and a top region which contains strain-relieving defects. In the undoped samples the defect-free layers are partially relaxed and their relaxation increases as the Ge fraction increases. Substitutional boron incorporated to the SiGe lattice to levels of 2.8 ± 0 3 × 1020 cm−3 during the growth process reduces the lattice mismatch between the epilayers and the substrate. The boron-doped, defect-free layers are thicker than the corresponding undoped layers of the same Ge content and their strain relaxation is lower. It has been shown that it is possible to grow at least 27 nm thick defect-free and fully strained heavily boron-doped layers with x = 0.21 by solid phase epitaxy.
The viscosity of germanium during substrate relaxation upon thermal anneal
Authors: Rosenberg Sara E. , Madras Cynthia G. , Wong Peter Y. , Miaoulis Ioannis N.
Published: April 2008

Thin-film heterostructures experience structural relaxation when subjected to post-deposition thermal heat treatment. The rate of relaxation, elastic effects, and inelastic effects on the stress and deformation of the structure are determined by the physical properties of the materials, in particular, the solid-phase viscosity. During relaxation, movement of defects causes an increase of viscosity with time at a constant rate as these defects are annihilated. Experimental anneals have been performed on structures with polycrystalline silicon films on (111) germanium substrates, in which the substrate relaxes during thermal annealing. A numerical analysis of the experimental results has determined values for the viscosity and viscosity rate of (111) germanium wafers. In addition, four zones of the relaxation process have been identified, and results indicate that the increasing viscosity with time has a larger effect at lower furnace ramp-up rates.
Liquid-exchange processing and properties of SiC–Al composites
Authors: Hozer Leszek , Chiang Yet-Ming , Ivanova Svetlana , Bar-On Isa
Published: April 2008

In this paper we demonstrate a novel liquid-exchange process to replace a secondary silicon phase in reaction-bonded siliconized silicon carbides (RBSC's) with a ductile metal reinforcement phase. When RBSC is exchanged with pure Al or Al–Si liquid, secondary phase silicon is dissolved and is substituted by Al or Al–Si alloy. The resulting composites show improvements in fracture toughness (single-edge precracked beam technique), with KIC value up to 8.6 Mpa · m1/2, compared to 3–4 MPa · m1/2 in otherwise similar siliconized silicon carbide. Increased fracture strength (four point flexure) was also observed after the liquid exchange process. The processing furthermore allows the coefficient of thermal expansion to be adjusted, and the thermal conductivity increased, for electronic packaging applications.
Neural net formulations for organically modified, hydrophobic silica aerogel
Authors: Noever David , Sibille Laurent , Cronise Raymond , Baskaran Subbiah , Hunt Arlon
Published: April 2008

Organic modification of aerogel chemical formulations is known to transfer desirable hydrophobicity to lightweight solids. However, the effects of chemical modification on other material constants such as elasticity, compliance, and sound dampening present a difficult optimization problem. Here a statistical treatment of a 9-variable optimization is accomplished with multiple regression and an artificial neural network (ANN). The ANN shows 95% prediction success for the entire data set of elasticity, compared to a multidimensional linear regression which shows a maximum correlation coefficient,R= 0.782. In this case, using the Number of Categories Criterion for the standard multiple regression, traditional statistical methods can distinguish fewer than 1.83 categories (high and low elasticity) and cannot group or cluster the data to give more refined partitions. A nonlinear surface requires at least three categories (high, low, and medium elasticities) to define its curvature. To predict best and worst gellation conditions, organic modification is most consistent with changed elasticity for sterically large groups and high hydroxyl concentrations per unit surface area. The isocontours for best silica and hydroxyl concentration have a complex saddle, the geometrical structure of which would elude a simple experimental design based on usual gradient descent methods for finding optimum.
Growth of Ti thin films on sapphire substrates
Authors: Peddada S. Rao , Robertson I. M. , Birnbaum H. K.
Published: April 2008

Titanium thin films have been grown by electron-beam physical vapor deposition on the (0001) surface of sapphire (single crystal α−Al2O3) substrates at growth temperatures ranging from 295 to 1223 K. Single phase α−Ti films grew at all growth temperatures, even at 1223 K which is above the α-β transition temperature of Ti. Crystal quality, as measured by the width of x-ray rocking curves, was found to improve, and the elastic strain to increase, as the growth temperature increased from 295 K to 1023 K. The epitaxial relationship between the Ti and sapphire was (0002)Ti ‖ (0006)Al2O3 and [1120]Ti ‖ [1010]Al2O3. The extent of interdiffusion across the Ti/Al2O3 interface was observed to be small (< 20 nm) at all growth temperatures.
The influence of total pressure in the reactor and carrier gas on the chemical vapor deposition of Al from tri-isobutyl aluminum
Authors: Suzuki Takakazu
Published: April 2008

The influence of total pressure in the chamber and carrier gases on the chemical vapor deposition of aluminum using tri-isobutyl aluminum was studied. The superior penetrability of chemical vapor deposition is expected to make it effective for aluminum deposition onto complex-shaped materials such as turbo-charger rotors, fibrous preform, and multifilament. It may also be a suitable method for the development of fiber-reinforced composite materials. The apparatus was composed of a raw material gas supply system, a three-zone electric furnace, a reaction chamber, an auto pressure controller, and an exhaust system. Aluminum was deposited onto a graphite fiber in the quartz reactor. The results show that, in the diffusion rate-determining stage of aluminum thermal decomposition, the rate of deposition for aluminum shows a marked increase as the pressure increases; in contrast, in the reaction rate-determining stage, this tendency is limited. This can be explained by the fact that, as the total pressure decreases, the gas diffusion coefficient becomes larger, and there is an increase in the uniformity of film formation. On the other hand, as the carrier gas flow rate increases, the amount of raw material supplied increases; consequently, a higher rate of deposition is obtained. Moreover, in the diffusion rate-determining stage, there is a tendency for an increase in flow rate to elevate the probability of arrival of the raw material, and, in combination with high temperatures, for nucleus generation to be accelerated and the average diameter of aluminum granules to become smaller. In the reaction rate-determining stage, there appears to be hardly any dependency of granule diameter on the flow rate. When Ar or He is used as the carrier gas, under the same conditions argon, rather than helium, is seen to increase the rate of deposition.
Gastric cancer patients treated by a general or gastric cancer surgical team: a comparative study
Authors: Souza Fernando O. , Pereira Dalnei V. , Santos Luís H. , Antunes Luis , Chiesa Juarez
Published: April 2008

BACKGROUND: Although gastric cancer has been decreasing in incidence in many countries, it is still the second most common cause of cancer deaths worldwide. Its prognosis is poor and depends, among other factors, on early diagnosis as well as on surgeon expertise. AIM: To compare the outcomes of gastric cancer patients treated at a university hospital by a general surgical team and later on by a gastric cancer surgical team. METHODS: Gastric cancer patients were separated into two groups according to whether they were treated by a general surgical team (group 1, n = 136; 1984 to 1993) or by gastric cancer team (group 2, n = 149; 1994 to 2003). Clinical and pathologic features and survival rates were assessed. RESULTS: During a 20-year period, a decreased number of patients underwent surgical resection in the second period (94% vs 86%), a greater number of upper gastrointestinal endoscopies were performed resulting in an increased number of tumors diagnosed as stage I (5% vs 22%). Also, D2 gastrectomies were more frequently performed instead of D0 gastrectomies and negative surgical margins were adequate. Mortality decreased from 9% to 6% in group 1 and 2, respectively and adjuvant therapy has been considered. CONCLUSION: Surgical specialized units for gastric cancer are necessary if better results are to be expected since this approach definitely provides better patient care.
Prevalence of Barrett's esophagus in individuals without typical symptoms of gastroesophageal reflux disease
Authors: Freitas Mauro Carneiro de , Moretzsohn Luciana Dias , Coelho Luiz G. V.
Published: April 2008

BACKGROUND: Barrett’s esophagus, the major risk factor for esophageal adenocarcinoma, is detected in approximately 10%-14% of individuals submitted to upper endoscopy for the assessment of gastroesophageal reflux disease related symptoms. Prevalence studies of Barrett’s esophagus in individuals without typical symptoms of gastroesophageal reflux disease have reported rates ranging from 0.6% to 25%. AIM: To determine the prevalence of Barrett’s in a Brazilian population older than 50 years without typical symptoms of gastroesophageal reflux disease. METHODS: A total of 104 patients (51 men), mean age of 65 years, with an indication for upper endoscopy but without symptoms of heartburn and/or acid regurgitation (determined with a validated questionnaire) were recruited. Subjects submitted to upper endoscopic examination in the last 10 years or using antisecretory medication (proton pump inhibitors) during the last 6 months were not included. Methylene blue chromoscopy was performed during the endoscopic exam to facilitate identification of the metaplastic epithelium. RESULTS: Barrett’s esophagus was diagnosed endoscopically and confirmed by histology in four patients, all of them males. The metaplastic segment was short (less than 3 cm) and free of dysplasia in all patients. The prevalence of Barrett’s esophagus was 7.75% in the male population and 3.8% in the general population studied. CONCLUSION: Due to the low prevalence of Barrett’s esophagus found in the present study, associated with the finding of short-segment Barrett’s esophagus in all cases diagnosed and the absence of dysplasia in the material analyzed, endoscopic screening for Barrett’s esophagus in patients above the age of 50 without the classical symptoms of gastroesophageal reflux disease is not indicated for the Brazilian population.
O cuidado em situação de rua: revendo o significado do processo saúde-doença
Authors: Rosa Anderson da Silva , Secco Maria Garbriela , Brêtas Ana Cristina Passarela
Published: April 2008

Esta pesquisa qualitativa teve por objetivo conhecer o significado do processo saúde-doença-cuidado para pessoas em situação de rua e trabalhadores de um centro comunitário de atendimento ao povo de rua na cidade de São Paulo. Os dados foram coletados por meio da técnica da entrevista com quatro moradores de rua e quatro trabalhadores. A análise foi realizada por meio da hermenêutica, tomando como referência três categorias analíticas: 1) a compreensão do processo saúde-doença-cuidado; 2) o cuidado com a saúde na rua; 3) "conselhos" para sobrevivência na rua. Os resultados mostram que apesar da heterogeneidade do povo de rua, existe uma cultura da rua relativa ao processo saúde-doença-cuidado que necessita ser apreendida pelos enfermeiros.
Perspectivas atuais da Informática em Enfermagem
Authors: Marin Heimar de Fátima , Cunha Isabel Cristina Kowal Olm
Published: April 2008

A Informática em Enfermagem é a área de conhecimento que estuda a aplicação dos recursos tecnológicos no ensino, na prática, na assistência e no gerenciamento da assistência e do cuidado. Recursos como reconhecimento de voz, bancos de conhecimento, projeto genoma e mesmo a Internet, têm oferecido para a Enfermagem uma gama de possibilidades para melhoria do desempenho profissional e melhoria do atendimento ao cliente/paciente. Este texto relata e exemplifica como tais recursos estão causando impactos e oportunidades para o ensino, pesquisa e principalmente, para a assistência de enfermagem ao cliente/paciente, ainda alerta para a importância do cuidado humanizado num cenário de alta tecnologia.
Perspectivas históricas do Projeto Genoma e a evolução da enfermagem
Authors: Flória-Santos Milena , Nascimento Lucila Castanheira
Published: April 2008

Este artigo tem por objetivo traçar um panorama histórico das principais transformações que estão ocorrendo na enfermagem após a finalização do Projeto Genoma. São apresentadas informações atuais sobre genética, o Projeto Genoma Humano, pesquisa genômica e sua interface com a prática da enfermagem, assim como propostas de vanguarda em várias áreas de pesquisa importantes para os enfermeiros. Descreve o surgimento de nova especialização na área de enfermagem, a enfermagem em genética, e da Sociedade Internacional dos Enfermeiros Geneticistas, que normatiza o exercício da mesma. Traz alguns dados de pesquisas recentemente realizadas, visando a integração da genética e, conseqüentemente, da genômica no ensino, na pesquisa e na assistência de enfermagem.