Home About us Contact
|
Home About us Contact | ||
|
|
||
Oxide
Kinds of Oxide Terms modified by Oxide Selected AbstractsANTIOXIDANT ACTIVITY OF FERMENTED BERRY JUICES AND THEIR EFFECTS ON NITRIC OXIDE AND TUMOR NECROSIS FACTOR-ALPHA PRODUCTION IN MACROPHAGES 264.7 GAMMA NO(,) CELL LINEJOURNAL OF FOOD BIOCHEMISTRY, Issue 3 2006TRI VUONG ABSTRACT Serratia vaccinii, a novel bacterium isolated from blueberry microflora, increased the phenolic content of berry juices, and thus increased antioxidant activities. The fermentation capacity of Serratia was investigated with Saskatoon berries, cranberries, strawberries and grapes in both aerobic and anaerobic conditions. It was shown to be compatible with wine yeast in anaerobic fermentations, producing wine with high antioxidant activity. The effects of fermented berry juices were tested on lipopolysaccharide/inferon-gamma-activated macrophages 264.7 NO(,). Data indicated that fermented berry juices strongly inhibited activated-macrophage NO production but induced tumor necrosis factor-alpha production. [source] EFFECT OF RE-STERILIZATION OF SURGICAL SUTURES BY ETHYLENE OXIDEANZ JOURNAL OF SURGERY, Issue 1-2 2007Prem Anand Nagaraja Background: Surgical suture packs are opened (and external packaging removed) on the operating table prior to surgery. Some of these suture packs may not be used in the surgery for reasons of inappropriateness or change in the surgical technique or following accidental contact with a non-sterile surface. These unused sutures with their foil packs still unopened are sometimes re-sterilized using ethylene oxide to allow for reuse. This re-sterilization of unopened suture packs can be contentious, due to legislation and health regulations in developed countries. The purpose of the present paper was to measure the effect of such repeated gas sterilization on sutures. Methods: The knot tensile strength was measured for new sterile sutures and ethylene oxide re-sterilized sutures. The tests were conducted on two available brands of sutures, including both absorbable and non-absorbable synthetic sutures. Results: No statistically significant difference was observed in the tensile strengths between the two sets of sutures, before and after re-sterilization. Some foil packs showed slight crimping after re-sterilization, but remained intact. No humidity was observed inside the foil packs. Conclusions: Re-sterilization of unused suture foil packs can be carried out without loss of tensile strength. [source] INTERPLAY OF REACTIVE OXYGEN SPECIES AND NITRIC OXIDE IN THE PATHOGENESIS OF EXPERIMENTAL LEAD-INDUCED HYPERTENSIONCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 9 2007ND Vaziri SUMMARY 1Lead is a common environmental and industrial toxin that can cause a variety of acute and chronic illnesses. For example, chronic exposure to low levels of lead has been shown to raise arterial pressure and promote renal and cardiovascular complications. 2Several mechanisms have been identified by which chronic lead exposure can cause hypertension and cardiovascular disease. In recent years, increasing evidence has emerged pointing to the role of oxidative stress as a major mediator of lead-induced hypertension. 3The present article provides an overview of the published studies on this subject. [source] DOES NITRIC OXIDE MODULATE TRANSMITTER RELEASE AT THE MAMMALIAN NEUROMUSCULAR JUNCTION?CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 4 2007Travis J Nickels SUMMARY 1Application of the nitric oxide (NO) donor, sodium nitrite and the NO synthase substrate l -arginine had no effect on nerve-evoked transmitter release in the rat isolated phrenic nerve/hemidiaphragm preparation; however, when adenosine A1 receptors were blocked with the adenosine A1 receptor antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX) prior to application of sodium nitrate or l -arginine, a significant increase in transmitter release was observed. In addition, the NO donor s -nitroso- N -acetylpenicillamine (SNAP) significantly increased transmitter release in the presence of DPCPX. In the present study, we have made the assumption that these NO donors elevate the level of NO in the tissue. Future studies should test other NO-donating compounds and also monitor the NO concentrations in the tissue to ensure that these effects are, in fact, NO induced. 2Elevation of cGMP in this preparation with the guanylyl cyclase activator 3-(5,-hydroxymethyl-2,-furyl)-1-benzyl indazole (YC-1) significantly enhanced transmitter release. In the presence of DPCPX and the selective guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), which blocks the production of cGMP, the excitatory effects of sodium nitrite and l -arginine were abolished. 3These results suggest that NO serves to enhance transmitter release at the rat neuromuscular junction (NMJ) via a cGMP pathway and this facilitation of transmitter release can be blocked with adenosine. Previously, we demonstrated that adenosine inhibits N-type calcium channels. Because NO only affects transmitter release when adenosine A1 receptors are blocked, we suggest that NO enhances transmitter release by enhancing calcium influx via N-type calcium channels. Further studies are needed to confirm that NO alters transmitter release via cGMP and that this action involves the N-type calcium channel. 4The results of the present study are consistent with a model of NO neuromodulation that has been proposed for the mammalian vagal,atrial junction. This model suggests that NO acts on NO-sensitive guanylyl cyclase to increase the intracellular levels of cGMP. In turn, cGMP inhibits phosphodiesterase-3, increasing levels of cAMP, which then acts on the N-type calcium channels to enhance calcium influx, leading to an increase in transmitter release. Our only modification to this model for the NMJ is that adenosine serves to block the modulation of transmitter release by NO. [source] IMPACT OF OBESITY AND INSULIN RESISTANCE ON VASOMOTOR TONE: NITRIC OXIDE AND BEYONDCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 5-6 2006David W Stepp SUMMARY 1Obesity is rapidly increasing in Western populations, driving a parallel increase in hypertension, diabetes and vascular disease. Prior to the development of overt diabetes or hypertension, obese patients spend years in a state of progressive insulin resistance and metabolic disease. Mounting evidence suggests that this insulin-resistant state has deleterious effects on the control of blood flow, thus placing organ systems at a higher risk for end-organ damage and increasing cardiovascular mortality. 2The purpose of the present review is to examine the current literature on the effects of obesity and insulin resistance on the acute control of vascular tone. Effects on nitric oxide (NO)-mediated control of vascular tone are particularly examined with regard to proximal causes and distal mechanisms of the impaired NO-mediation of vasodilation. 3Finally, novel pathways of impaired control of perfusion are summarized from the recent literature to identify new avenues of exploring impaired vascular function in patients with metabolic disease. [source] NANOMOLAR LEVEL OF OUABAIN INCREASES INTRACELLULAR CALCIUM TO PRODUCE NITRIC OXIDE IN RAT AORTIC ENDOTHELIAL CELLSCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 5-6 2004Xian Hui Dong Summary 1.,Changes in [Ca2+]i across the cell membrane and/or the sarcoplasmic reticulum regulate endothelial nitric oxide (NO) synthase activity. 2.,In the present study, we investigated the effect of ouabain, a specific inhibitor of Na+/K+ -ATPase, on NO release and [Ca2+]i movements in cultured rat aortic endothelial cells (RAEC) by monitoring NO production continuously using an NO-specific real-time sensor and by measuring the change in [Ca2+]i using a fluorescence microscopic imaging technique with high-speed wavelength switching. The t½ (half-time of the decline of [Ca2+]i to basal levels after stimulation with 10 µmol/L bradykinin) was used as an index of [Ca2+]i extrusion. 3.,A very low concentration of ouabain (10 nmol/L) did not increase the peak of NO production, but decreased the decay of NO release and, accordingly, increased integral NO production by the maximal dose,response concentration induced by bradykinin. The same dose of ouabain affected [Ca2+]i movements across the cell membrane and/or sarcoplasmic reticulum induced by bradykinin with a time-course similar to that of NO release. Moreover, the t½ was significantly increased. 4.,Pretreatment of RAEC with Na+ -free solution, an inhibitor of the Na+/Ca2+ exchanger, and nickel chloride hexahydrate prevented the effects induced by bradykinin and ouabain. 5.,These observations using real-time recording indicate that a small amount of ouabain contributes to the bradykinin-stimulated increase of NO production through inhibition of plasma membrane Na+/K+ -ATPase activity and an increase in intracellular Na+ concentrations. The membrane was then depolarized, leading to a decline in the bradykinin-stimulated increase in [Ca2+]i by forward mode Na+/Ca2+ exchange to prolong the Ca2+ signal time. 6.,From these results, we suggest that nanomolar levels of ouabain modulate [Ca2+]i movements and NO production in RAEC. [source] Growth of lead bromide polycrystalline filmsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2004M. Giles Abstract Lead bromide polycrystalline films were grown by the physical vapor deposition method (PVD). Glass 1,x1, in size, uncoated, and coated with Indium Tin Oxide (ITO), was used as substrate and rear contact. The starting material was evaporated at temperatures from 395°C to 530°C under high vacuum atmosphere (6 x 10 -3 Pa) and during 8 days. The substrate temperature was prefixed from 190°C to 220°C. Film thickness yielded values from 40 to 90 ,m. Optical microscopy and scanning electron microscopy (SEM) were performed on the films. Grain size resulted to be from 1.0 to 3.5 ,m. SEM and X-ray diffraction indicate that films grow with a preferred orientation with the (0 0 l) planes parallel to the substrate. The Texture Coefficient (TC) related to the plane (0 0 6) was 7.3. Resistivity values in the order of 1012 ,cm were obtained for the oriented samples, but a strong polarization indicates severe charge transport problems in the films. Film properties were correlated with the growth temperature and with previous results for films of other halides. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Comment on "Endothelially Derived Nitric Oxide Affects the Severity of Early Acetaminophen-induced Hepatic Injury in Mice"ACADEMIC EMERGENCY MEDICINE, Issue 9 2006Kari Scantlebury MD No abstract is available for this article. [source] Endothelially Derived Nitric Oxide Affects the Severity of Early Acetaminophen-induced Hepatic Injury in MiceACADEMIC EMERGENCY MEDICINE, Issue 5 2006Steven D. Salhanick MD Abstract Objectives: The precise mechanism of hepatocellular toxicity following acetaminophen (APAP) poisoning remains unclear. Nitric oxide is implicated in APAP toxicity as an inflammatory signaling molecule and as a precursor to the free radical peroxynitrate. The effects of inducible nitric oxide synthase (iNOS)-derived NO in APAP toxicity are known; however, the role of endothelial nitric oxide synthase (eNOS)-derived NO is unknown. The authors sought to evaluate the effect of eNOS-derived NO during APAP toxicity. Methods: C57BL6/J mice deficient in eNOS (eNOS KO) or iNOS (iNOS KO) and wild-type mice (WT) were treated with 300 mg/kg APAP. Alanine aminotransferase levels and plasma nitrate and nitrite levels were measured. Hypoxia inducible factor (HIF)-1, and Glucose Transporter 1 (Glut-1) levels were determined by Western blot. Results: Alanine aminotransferase levels were significantly elevated in all treated animals. Alanine aminotransferase levels were significantly lower in eNOS KO and iNOS KO than in treated WT animals. Plasma nitrate/nitrite levels were significantly higher in WT animals than in iNOS KO and eNOS KO animals. HIF-1, expression was increased in WT mice and decreased in iNOS KO mice. Glut-1 is a downstream, indirect marker of HIF function. Glut-1 expression was increased in WT and eNOS KO mice. Conclusions: Deficiency of either iNOS or eNOS results in decreased NO production and is associated with reduced hepatocellular injury following APAP poisoning. HIF-1, and Glut-1 levels are increased following APAP poisoning, implying that HIF-1, is functional during the pathogenic response to APAP poisoning. [source] A Comparison of Membrane Inlet Mass Spectrometry and Nitric Oxide (NO) Electrode Techniques to Detect NO in Aqueous SolutionELECTROANALYSIS, Issue 4 2010Chingkuang Tu Abstract The NO electrode and membrane inlet mass spectrometry (MIMS) have the advantage of being sensitive, direct, and real time detectors of NO in aqueous solution. They do not require reacting NO with labels or purging of NO with an inert gas. We show that the NO electrode and MIMS are comparable in sensitivity detecting NO concentrations to 0.5,nM in aqueous solution, and both give identical results in a biological measurement, the reactions of deoxyhemoglobin with nitrite. [source] Novel Thorium Membrane Sensors with Anionic Response Based on Trioctylphosphine Oxide and Toluate IonophoresELECTROANALYSIS, Issue 19 2008Abstract Two novel potentiometric polymeric membrane sensors for rapid and accurate determination of thorium are described. These are based on the use of trioctylphosphine oxide (TOPO) and thorium toluate (Th-TA) as ionophores dispersed in poly(vinyl chloride) matrix membranes plasticized with nitrophenyloctyl ether. In strong nitric acid medium, Th(IV) nitrate is converted into [Th(NO3)6]2, complex and sensed as anionic divalent ion which exclude most cationic effect. Validation of the assay methods using the quality assurance standards (linearity range, accuracy, precision, within-day variability, between-day-repeatability, lower detection limit and sensitivity) reveals excellent performance characteristics of both sensors. The sensors exhibit near-Nernstian response for 1.0×10,6,1.0×10,1 M Th over the pH range 2.5,4.5. Calibration slopes of ,32.3±0.3 and ,27.2±0.2,mV/decade, precision of ±0.5 and ±0.8% and accuracy of 98.8±0.9 and 97.9±0.7% are obtained with TOPO and Th-TA based sensors, respectively. Negligible interferences are caused by most interfering mono-, di-, tri-, tetra-, penta-, and hexa-valent elements commonly associated with thorium in naturally occurring minerals and ores. High concentrations of Cl,, F,, SO42,, and NO3, ions have no diverse effect. Complete removal of the effect of the interferents in complex matrices is achieved by retention of [Th(NO3)6]2, complex from 5,M nitric acid/methanol mixture (1,:,9,v/v) on a strong anion exchanger, washing out the cationic interferents followed by stripping off thorium anion complex and measurements. Both sensors are used for determining thorium in certified thorium ore samples (20,120,mg Th/kg) and some naturally occurring ores (200,600,mg Th/kg). The results obtained agree fairly well with the certified labeled values or the data obtained using X-ray fluorescence spectrometry [source] Electrocatalysis and Amperometric Detection of the Reduced Form of Nicotinamide Adenine Dinucleotide at Toluidine Blue/Zinc Oxide Coated ElectrodesELECTROANALYSIS, Issue 18 2007Ashok Kumar Abstract Thin toluidine blue (TBO) and zinc oxide (ZnO) hybrid films have been grown on glassy carbon electrode (GCE) and indium tin oxide coated (SnO2) glass electrodes by using cyclic voltammetry (CV). Scanning electron microscopy (SEM) images revealed spherical and beads-like shape of highly oriented TBO/ZnO hybrid films. Energy dispersive spectrometry (EDS) results declared that the films composed mainly of Zn and O. Moreover, TBO/ZnO hybrid films modified electrode is electrochemically active, dye molecules were not easily leached out from the ZnO matrix and the hybrid films can be considered for potential applications as sensor for amperometric determination of reduced nicotinamide adenine dinucleotide (NADH) at 0.0,V. A linear correlation between electrocatalytic current and NADH concentration was found to be in the range between 25,,M and 100,,M in phosphate buffer. In addition, we observed that dopamine, ascorbic acid and uric acid are not interference in amperometric detection of NADH in this proposed method. In addition, TBO/ZnO hybrid film modified electrode was highly stable and its response to the NADH also remained relentless. [source] Copper Oxide , Graphite Composite Electrodes: Application to Nitrite SensingELECTROANALYSIS, Issue 1 2007Biljana, ljuki Abstract A simple method for the modification of carbon powder with copper oxides is presented. Carbon powder is impregnated with copper(II) nitrate by stirring carbon powder in copper(II) nitrate solution for 1 hour and subsequently thermally treated at 823,K. The modified carbon powder was characterized using electrochemical and spectroscopic techniques. The existence of both copper(I) and copper(II) oxides have been established. The copper oxide modified carbon powder was used for preparation of composite electrodes, and the electrochemical and electrocatalytic behavior of the resulting composite electrodes was studied. The copper oxide modified carbon powder , epoxy composite electrodes showed a high electrocatalytic activity for the nitrite detection in aqueous media, with the detection limit comparable or lower than detection limits obtained with other electrochemical sensors. [source] Role of Nitric Oxide in Pentylenetetrazol-Induced Seizures: Age-Dependent Effects in the Immature RatEPILEPSIA, Issue 4 2000Anne Pereira de Vasconcelos Summary: Purpose: Seizure susceptibility and consequences are highly age dependent. To understand the pathophysiologic mechanisms involved in seizures and their consequences during development, we investigated the role of nitric oxide (NO) in severe pentylenetetrazol (PTZ)-induced seizures in immature rats. Methods: Four cortical electrodes were implanted in 10-day-old (P10) and 21-day-old (P21) rats, and seizures were induced on the following day by repetitive injections of subconvulsive doses of PTZ. The effects of NG -nitro- l -arginine methyl ester (l -NAME; 10 mg/kg) and 7-nitroindazole (7NI; 40 mg/kg), two NO synthase (NOS) inhibitors, and l -arginine (l -arg; 300 mg/kg), the NOS substrate, were evaluated regarding the mean PTZ dose, seizure type and duration, and mortality rate. Results: At P10, the postseizure mortality rate increased from 18,29% for the rats receiving PTZ only to 100% and 89% for the rats receiving l -NAME and 7NI, respectively; whereas l -arg had no effect. Conversely, at P21, NOS inhibitors did not affect the 82,89% mortality rate induced by PTZ alone, whereas l -arg decreased the mortality rate to 29%. In addition, all NO-related drugs increased the duration of ictal activity at P10, whereas at P21, L -arg and L -NAME affected the first seizure type, producing clonic seizures with L -arg and tonic seizures with L -NAME. Conclusions: The relative natural protection of very immature rats (P10) against PTZ-induced deaths could be linked to a high availability of L -arg and, hence, endogenous NO. At P21, the modulation of seizure type by NO-related compounds may be related to the maturation of the brain circuitry, in particular the forebrain, which is involved in the expression of clonic seizures. [source] Antimony Amide Oxide and Antimony Chloride Oxide Wrapped in an Organoaluminum FrameworkEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 7 2008Sanjay Singh Abstract Syntheses of trimetallic aluminum and antimony compounds containing an Al2O2SbN and an Al2O2SbCl core in [LAl(Me)(,-O)]2Sb(NMe2) and [LAl(Me)(,-O)]2SbCl, respectively, are reported. The former compound represents an example of an amide oxide of antimony and the latter is an example of a chloride oxide of antimony incorporated in an organoaluminum framework which in turn is supported by a sterically encumbered ,-diketiminate ligand L {L = HC[C(Me)N-2,6- iPr2C6H3]2}. The solid-state structure of [LAl(Me)(,-O)]2Sb(NMe2) was elucidated by the aid of single-crystal X-ray diffraction technique which shows the molecule to crystallize in the triclinic space group P. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Unprecedented Rearrangement of Molybdenum(VI) Oxide to (,2 -Oxido)bis[dioxidomolybdenum(VI)] HexamolybdateEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 25 2007Marķa R. Pedrosa Abstract MoO2(acac)2 reacts with water, amides, sulfoxides, and phosphane oxides in aqueous methanol, under mild conditions, to afford a new family of molybdates of composition [Mo2O5L6][Mo6O19] (L = H2O, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dibutyl sulfoxide, tributylphosphane oxide, triphenylphosphane oxide, hexamethylphosphoramide). The crystal and molecular structures of the two first structurally characterized (,2 -oxido)bis[dioxidomolybdenum(VI)] hexamolybdates were established by X-ray diffraction analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Tungsten Oxide and Tungsten Oxide-Titania Thin Films Prepared by Aerosol-Assisted Deposition , Use of Preformed Solid NanoparticlesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 10 2007Uzma Qureshi Abstract Aerosol-assisted deposition (AAD) was used to deposit films of WO3 from a suspension of solid nanoparticulate WO3 in toluene. Titania films were deposited by the aerosol-assisted chemical vapour deposition of [Ti(OiPr)4] in the presence of WO3 nanoparticles. The WO3 and TiO2 films exhibited photoactivity and photoinduced superhydrophilicity, further the titania films showed very unusual highly crenulated microstructures. These microstructures could not be obtained by sol-gel, atmospheric pressure chemical vapour deposition or evaporation routes. Furthermore, the microstructures could not be obtained from [Ti(OiPr)4] in the absence of nanoparticulate WO3. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Lanthanum(III) Oxide as a Recyclable Catalyst for the Synthesis of Diaryl Sulfides and Diaryl SelenidesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 34 2009Sabbavarapu Narayana Murthy Abstract La2O3 as a new and efficient recyclable catalyst in coupling various aryl halides with aromatic/alkyl thiols and diphenyl diselenide in combination with KOH as a base and DMEDA as a ligand in DMSO at 110 °C is reported. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Photochemistry of cis -3-Diazo-5,6-dimethyl-1,4-oxathian-2-one S -Oxide in Argon MatricesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 13 2006Orlagh C. M. O'Sullivan Abstract The photochemistry of the ,-diazo sulfoxide 7 has been investigated in solid argon at 10 K by IR spectroscopy. The sulfinyl carbene was not detected directly but instead underwent photochemically induced hetero-Wolff rearrangement to the sulfine 8 which could be detected and characterized following irradiation at 248 nm. Further photochemical reaction of this intermediate led to the oxathiirane 9 which was most readily detected on irradiation of 7 at 308 nm. The matrix-isolated species were identified by comparison of experimental and calculated IR spectra. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Conductance Enhancement Mechanisms of Printable Nanoparticulate Indium Tin Oxide (ITO) Layers for Application in Organic Electronic Devices,ADVANCED ENGINEERING MATERIALS, Issue 4 2009Michael Gross We present and discuss several methods to enhance the electrical properties of nanoparticle dispersion derived ITO-layers. A maximum conductance of 132,,,1,cm,1 was achieved and films with a sheet resistance down to 5,,/, were produced. To demonstrate their applicability as electrodes in optoelectronic elements we assembled functioning polymer LED-s on them. [source] Direct Electrochemical Preparation of NbSi Alloys from Mixed Oxide Preform Precursors,ADVANCED ENGINEERING MATERIALS, Issue 3 2009Fanke Meng A new method of preparation of NbSi alloys has been provided in this article. Electro-deoxidizing mixed Nb2O5 and SiO2 small cylindrical pellets in molten CaF2 at high temperature (1500,°C) could produce homogenous NbSi alloys. And then, the cyclic voltammogram (CV) method was used to analyze the electroreduction mechanism. This effective method could shorten procedures of production of NbSi alloys and will be promising for industrial utilization. [source] Inhibition of Neuronal Nitric Oxide Reduces Heart Rate Variability in the Anaesthetised DogEXPERIMENTAL PHYSIOLOGY, Issue 5 2001F. Markos In the vagally intact anaesthetised dog, we have investigated the role of nitric oxide (NO) on a normal sinus arrhythmia using an inhibitor of neuronally released NO, 1-(2-trifluoromethylphenyl) imidazole (TRIM). The mean and S.D. of the R-R interval was used to describe mean heart rate and heart rate variability, respectively. TRIM (0.8 mg I.C.) injected into the sinus node artery increased the mean heart rate slightly but reduced heart rate variability 3-fold from a control of 790 ± 124 ms (mean ± S.D.; n = 5) to 666 ± 36 ms (P < 0.01 Student's paired t test, n = 5). These results suggest that neuronally released NO may have a vagal facilitatory role in the maintenance of sinus arrhythmia in the normal heart. [source] Mechanisms Associated with the Negative Inotropic Effect of Deuterium Oxide in Single Rat Ventricular MyocytesEXPERIMENTAL PHYSIOLOGY, Issue 2 2000K. Hongo Deuterium oxide (D2O) is known to cause a negative inotropic effect in muscle although the mechanisms associated with this response in cardiac muscle are not well understood. We studied the effects of D2O in single rat ventricular myocytes in order to characterise the mechanisms associated with its negative inotropic effect and to assess its possible use as an acute modulator of microtubules. D2O rapidly reduced the magnitude of contraction in rat ventricular myocytes, and there was some recovery of contraction in the presence of D2O. Colchicine, an agent known to depolymerise microtubules, did not modify the effect of D2O. D2O decreased the L-type Ca2+ current (ICa), measured under whole cell and perforated patch clamp conditions. Slowing of the time to peak and a delay in inactivation of ICa were observed. Intracellular calcium ([Ca2+]i) and sodium ([Na+]i) were measured using the fluorescent indicators fura-2 and SBFI, respectively. The fall in contraction upon exposure to D2O was not associated with a fall in the [Ca2+]i transient; this response is indicative of a reduction in myofilament Ca2+ sensitivity. Both the [Ca2+]i transient and [Na+]i increased during the partial recovery of contraction in the presence of D2O. We conclude that a decrease in the myofilament sensitivity for Ca2+ and a reduction in Ca2+ influx via ICa are principally responsible for the negative inotropic effect of D2O in cardiac muscle. We found no evidence to explain the negative inotropic effect of D2O in terms of microtubule proliferation. In addition we suggest that acute application of D2O is not a useful procedure for the investigation of the role of microtubules in excitation-contraction coupling in cardiac muscle. [source] High-Nanofiller-Content Graphene Oxide,Polymer Nanocomposites via Vacuum-Assisted Self-AssemblyADVANCED FUNCTIONAL MATERIALS, Issue 19 2010Karl W. Putz Abstract Highly ordered, homogeneous polymer nanocomposites of layered graphene oxide are prepared using a vacuum-assisted self-assembly (VASA) technique. In VASA, all components (nanofiller and polymer) are pre-mixed prior to assembly under a flow, making it compatible with either hydrophilic poly(vinyl alcohol) (PVA) or hydrophobic poly(methyl methacrylate) (PMMA) for the preparation of composites with over 50 wt% filler. This process is complimentary to layer-by-layer assembly, where the assembling components are required to interact strongly (e.g., via Coulombic attraction). The nanosheets within the VASA-assembled composites exhibit a high degree of order with tunable intersheet spacing, depending on the polymer content. Graphene oxide,PVA nanocomposites, prepared from water, exhibit greatly improved modulus values in comparison to films of either pure PVA or pure graphene oxide. Modulus values for graphene oxide,PMMA nanocomposites, prepared from dimethylformamide, are intermediate to those of the pure components. The differences in structure, modulus, and strength can be attributed to the gallery composition, specifically the hydrogen bonding ability of the intercalating species [source] A Graphene Oxide,Streptavidin Complex for Biorecognition , Towards Affinity PurificationADVANCED FUNCTIONAL MATERIALS, Issue 17 2010Zunfeng Liu Abstract In our postgenomic era, understanding of protein-protein interactions by characterizing the structure of the corresponding protein complex is becoming increasingly important. An important problem is that many protein complexes are only stable for a few minutes. Dissociation will occur when using the typical, time-consuming purification methods such as tandem affinity purification and multiple chromatographic separations. Therefore, there is an urgent need for a quick and efficient protein-complex purification method for 3D structure characterization. The graphene oxide (GO)·streptavidin complex is prepared via a GO·biotin·streptavidin strategy and used for affinity purification. The complex shows a strong biotin recognition capability and an excellent loading capacity. Capturing biotinylated DNA, fluorophores and Au nanoparticles on the GO·streptavidin complexes demonstrates the usefulness of the GO·streptavidin complex as a docking matrix for affinity purification. GO shows a high transparency towards electron beams, making it specifically well suited for direct imaging by electron microscopy. The captured protein complex can be separated via a filtration process or even via on-grid purification and used directly for single-particle analysis via cryo-electron microscopy. Therefore, the purification, sample preparation, and characterization are rolled into one single step. [source] Graphite Oxide as a Photocatalyst for Hydrogen Production from WaterADVANCED FUNCTIONAL MATERIALS, Issue 14 2010Te-Fu Yeh Abstract A graphite oxide (GO) semiconductor photocatalyst with an apparent bandgap of 2.4,4.3,eV is synthesized by a modified Hummers' procedure. The as-synthesized GO photocatalyst has an interlayer spacing of 0.42,nm because of its moderate oxidation level. Under irradiation with UV or visible light, this GO photocatalyst steadily catalyzes H2 generation from a 20,vol % aqueous methanol solution and pure water. As the GO sheets extensively disperse in water, a cocatalyst is not required for H2 generation over the GO photocatalyst. During photocatalytic reaction, the GO loses some oxygen functional groups, leading to bandgap reduction and increased conductivity. This structural variation does not affect the stable H2 generation over the GO. The encouraging results presented in this study demonstrate the potential of graphitic materials as a medium for water splitting under solar illumination. [source] Photovoltaics Based on Hybridization of Effective Dye-Sensitized Titanium Oxide and Hole-Conductive Polymer P3HTADVANCED FUNCTIONAL MATERIALS, Issue 15 2009Ke-Jian Jiang Abstract Here, the fabrication of quasi-solid-state TiO2/dye/poly(3-hexylthiophene) (P3HT) solar cells is reported, in which the dyes with oleophilic thienyl groups were employed and ionic liquid (IL), 1-ethyl-3-methylimidazolium (EMIm) containing lithium bis(trifluromethanesulfone)amide (Li-TFSI) and 4- tert -butylpyridine (t -BP) are assembled with dyed TiO2 surfaces. One of the devices gave a high conversion efficiency of up to 2.70% under 1 sun illumination. The excellent performance is ascribed to successful molecular self-organization at interface of the dye molecules and P3HT, and to the efficient charge separation and diffusion acquired by introduction of the IL coupled with Li-TFSI and t-BP. [source] Efficient Reduction of Graphite Oxide by Sodium Borohydride and Its Effect on Electrical ConductanceADVANCED FUNCTIONAL MATERIALS, Issue 12 2009Hyeon-Jin Shin Abstract The conductivity of graphite oxide films is modulated using reducing agents. It is found that the sheet resistance of graphite oxide film reduced using sodium borohydride (NaBH4) is much lower than that of films reduced using hydrazine (N2H4). This is attributed to the formation of CN groups in the N2H4 case, which may act as donors compensating the hole carriers in reduced graphite oxide. In the case of NaBH4 reduction, the interlayer distance is first slightly expanded by the formation of intermediate boron oxide complexes and then contracted by the gradual removal of carbonyl and hydroxyl groups along with the boron oxide complexes. The fabricated conducting film comprising a NaBH4 -reduced graphite oxide reveals a sheet resistance comparable to that of dispersed graphene. [source] Low-Temperature-Grown Transition Metal Oxide Based Storage Materials and Oxide Transistors for High-Density Non-volatile MemoryADVANCED FUNCTIONAL MATERIALS, Issue 10 2009Myoung-Jae Lee Abstract An effective stacked memory concept utilizing all-oxide-based device components for future high-density nonvolatile stacked structure data storage is developed. GaInZnO (GIZO) thin-film transistors, grown at room temperature, are integrated with one-diode (CuO/InZnO),one-resistor (NiO) (1D,1R) structure oxide storage node elements, fabricated at room temperature. The low growth temperatures and fabrication methods introduced in this paper allow the demonstration of a stackable memory array as well as integrated device characteristics. Benefits provided by low-temperature processes are demonstrated by fabrication of working devices over glass substrates. Here, the device characteristics of each individual component as well as the characteristics of a combined select transistor with a 1D,1R cell are reported. X-ray photoelectron spectroscopy analysis of a NiO resistance layer deposited by sputter and atomic layer deposition confirms the importance of metallic Ni content in NiO for bi-stable resistance switching. The GIZO transistor shows a field-effect mobility of 30,cm2,V,1,s,1, a Vth of +1.2,V, and a drain current on/off ratio of up to 108, while the CuO/InZnO heterojunction oxide diode has forward current densities of 2,×,104,A,cm,2. Both of these materials show the performance of state-of-the-art oxide devices. [source] Solution-Deposited Zinc Oxide and Zinc Oxide/Pentacene Bilayer Transistors: High Mobility n-Channel, Ambipolar, and Nonvolatile Devices,ADVANCED FUNCTIONAL MATERIALS, Issue 12 2008Bhola Nath Pal Abstract A solution processed n-channel zinc oxide (ZnO) field effect transistor (FET) was fabricated by simple dip coating and subsequent heat treatment of a zinc acetate film. The field effect mobility of electrons depends on ZnO grain size, controlled by changing the number of coatings and zinc acetate solution concentration. The highest electron mobility achieved by this method is 7.2,cm2 V,1 s,1 with On/Off ratio of 70. This electron mobility is higher than for the most recently reported solution processed ZnO transistor. We also fabricated bilayer transistors where the first layer is ZnO, and the second layer is pentacene, a p-channel organic which is deposited by thermal evaporation. By changing the ZnO grain size (or thickness) this type of bilayer transistor shows p-channel, ambipolar and n-channel behavior. For the ambipolar transistor, well balanced electron and hole mobilities are 7.6,×,10,3 and 6.3,×,10,3,cm2 V,1 s,1 respectively. When the ZnO layer is very thin, the transistor shows p-channel behavior with very high reversible hysteresis. The nonvolatile tuning function of this transistor was investigated. [source] | ||||||||||||||||||||||||||||||||||||||||||||||