Sample records for nanotubes suppress potassium

  1. Multi-walled carbon nanotubes suppress potassium channel activities in PC12 cells (United States)

    Xu, Haifei; Bai, Juan; Meng, Jie; Hao, Wei; Xu, Haiyan; Cao, Ji-Min


    The advancement in nanotechnology has produced technological and conceptual breakthroughs but the effects nanomaterials have on organisms at the cellular level are poorly understood. Here we report that carboxyl-terminated multi-walled carbon nanotubes (MWCNTs) act as antagonists of three types of potassium channels as assessed by whole-cell patch clamp electrophysiology on undifferentiated pheochromocytoma (PC12) cells. Our results showed that carboxyl-terminated MWCNTs suppress the current densities of Ito, IK and IK1 in a time-dependent and irreversible manner. The suppressions were most distinct 24 h after incubation with MWCNTs. However, MWCNTs did not significantly change the expression levels of reactive oxygen species (ROS) or intracellular free calcium and also did not alter the mitochondrial membrane potential (ΔΨm) in PC12 cells. These results suggest that oxidative stress was not involved in the MWCNTs suppression of Ito, IK and IK1 current densities. Nonetheless, the suppression of potassium currents by MWCNTs will impact on electrical signaling of excitable cells such as neurons and muscles.

  2. Conformal Carbon Nanotubes for Stray Light Suppression (United States)

    National Aeronautics and Space Administration — We have developed ultra-black CVD (chemical vapor deposition) and embedded carbon nanotube surface treatments for use in the near UV to far infrared for stray light...

  3. Effects of potassium hydroxide post-treatments on the field-emission properties of thermal chemical vapor deposited carbon nanotubes. (United States)

    Lee, Li-Ying; Lee, Shih-Fong; Chang, Yung-Ping; Hsiao, Wei-Shao


    In this study, a simple potassium hydroxide treatment was applied to functionalize the surface and to modify the structure of multi-walled carbon nanotubes grown on silicon substrates by thermal chemical vapor deposition. Scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and energy dispersive spectrometry were employed to investigate the mechanism causing the modified field-emission properties of carbon nanotubes. From our experimental data, the emitted currents of carbon nanotubes after potassium hydroxide treatment are enhanced by more than one order of magnitude compared with those of untreated carbon nanotubes. The emitted current density of carbon nanotubes increases from 0.44 mA/cm2 to 7.92 mA/cm2 after 30 minutes KOH treatment. This technique provides a simple, economical, and effective way to enhance the field-emission properties of carbon nanotubes.

  4. Potassium (United States)

    ... and blackberries Root vegetables, such as carrots and potatoes Citrus fruits, such as oranges and grapefruit Your kidneys help to keep the right amount of potassium in your body. If you have chronic kidney disease, your kidneys may not remove extra potassium from ...

  5. Proximity Glare Suppression using Carbon Nanotubes, Phase I (United States)

    National Aeronautics and Space Administration — Carbon nanotubes (CNT) are the darkest material known to man and are an enabling technology for scientific instrumentation of interest to NASA. The chemical vapor...

  6. Carbon Nanotubes on Titanium Substrates for Stray Light Suppression (United States)

    Hagopian, John; Getty, Stephanie; Quijada, Manuel


    A method has been developed for growing carbon nanotubes on a titanium substrate, which makes the nano tubes ten times blacker than the current state-of-the-art paints in the visible to near infrared. This will allow for significant improvement of stray light performance in scientific instruments, or any other optical system. Because baffles, stops, and tubes used in scientific observations often undergo loads such as vibration, it is critical to develop this surface treatment on structural materials. This innovation optimizes the carbon nano - tube growth for titanium, which is a strong, lightweight structural material suitable for spaceflight use. The steps required to grow the nanotubes require the preparation of the surface by lapping, and the deposition of an iron catalyst over an alumina stiction layer by e-beam evaporation. In operation, the stray light controls are fabricated, and nanotubes (multi-walled 100 microns in length) are grown on the surface. They are then installed in the instruments or other optical devices.

  7. Fear conditioning suppresses large-conductance calcium-activated potassium channels in lateral amygdala neurons. (United States)

    Sun, P; Zhang, Q; Zhang, Y; Wang, F; Wang, L; Yamamoto, R; Sugai, T; Kato, N


    It was previously shown that depression-like behavior is accompanied with suppression of the large-conductance calcium activated potassium (BK) channel in cingulate cortex pyramidal cells. To test whether BK channels are also involved in fear conditioning, we studied neuronal properties of amygdala principal cells in fear conditioned mice. After behavior, we made brain slices containing the amygdala, the structure critically relevant to fear memory. The resting membrane potential in lateral amygdala (LA) neurons obtained from fear conditioned mice (FC group) was more depolarized than in neurons from naïve controls. The frequencies of spikes evoked by current injections were higher in neurons from FC mice, demonstrating that excitability of LA neurons was elevated by fear conditioning. The depolarization in neurons from FC mice was shown to depend on BK channels by using the BK channel blocker charybdotoxin. Suppression of BK channels in LA neurons from the FC group was further confirmed on the basis of the spike width, since BK channels affect the descending phase of spikes. Spikes were broader in the FC group than those in the naïve control in a manner dependent on BK channels. Consistently, quantitative real-time PCR revealed a decreased expression of BK channel mRNA. The present findings suggest that emotional disorder manifested in the forms of fear conditioning is accompanied with BK channel suppression in the amygdala, the brain structure critical to this emotional disorder. Copyright © 2014 Elsevier Inc. All rights reserved.

  8. Effects of Potassium and Manganese Promoters on Nitrogen-Doped Carbon Nanotube-Supported Iron Catalysts for CO2 Hydrogenation

    Directory of Open Access Journals (Sweden)

    Praewpilin Kangvansura


    Full Text Available Nitrogen-doped carbon nanotubes (NCNTs were used as a support for iron (Fe nanoparticles applied in carbon dioxide (CO2 hydrogenation at 633 K and 25 bar (1 bar = 105 Pa. The Fe/NCNT catalyst promoted with both potassium (K and manganese (Mn showed high performance in CO2 hydrogenation, reaching 34.9% conversion with a gas hourly space velocity (GHSV of 3.1 L·(g·h−1. Product selectivities were high for olefin products and low for short-chain alkanes for the K-promoted catalysts. When Fe/NCNT catalyst was promoted with both K and Mn, the catalytic activity was stable for 60 h of reaction time. The structural effect of the Mn promoter was demonstrated by X-ray diffraction (XRD, temperature-programmed reduction (TPR with molecular hydrogen (H2, and in situ X-ray absorption near-edge structure (XANES analysis. The Mn promoter stabilized wüstite (FeO as an intermediate and lowered the TPR onset temperature. Catalytic ammonia (NH3 decomposition was used as an additional probe reaction for characterizing the promoter effects. The Fe/NCNT catalyst promoted with both K and Mn had the highest catalytic activity, and the Mn-promoted Fe/NCNT catalysts had the highest thermal stability under reducing conditions.

  9. Potassium-doped carbon nanotubes toward the direct electrochemistry of cholesterol oxidase and its application in highly sensitive cholesterol biosensor

    Energy Technology Data Exchange (ETDEWEB)

    Li Xiaorong [State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Xu Jingjuan, E-mail: [State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China); Chen Hongyuan [State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093 (China)


    We demonstrate herein a newly developed serum total cholesterol biosensor by using the direct electron transfer of cholesterol oxidase (ChOx), which is based on the immobilization of cholesterol oxidase and cholesterol esterase (ChEt) on potassium-doped multi-walled carbon nanotubes (KMWNTs) modified electrodes. The KMWNTs accelerate the electron transfer from electrode surface to the immobilized ChOx, achieving the direct electrochemistry of ChOx and maintaining its bioactivity. As a new platform in cholesterol analysis, the resulting electrode (ChOx/KMWNTs/GCE) exhibits a sensitive response to free cholesterol, with a linear range of 0.050-16.0 {mu}mol L{sup -1} and a detection limit of 5.0 nmol L{sup -1} (S/N = 3). Coimmobilization of ChEt and ChOx (ChEt/ChOx/KMWNTs/GCE) allows the determination of both free cholesterol and esterified cholesterol. The resulting biosensor shows the same linear range of 0.050-16.0 {mu}mol L{sup -1} for free cholesterol and cholesteryl oleate, with the detection limit of 10.0 and 12.0 nmol L{sup -1} (S/N = 3), respectively. The concentrations of total (free and esterified) cholesterol in human serum samples, determined by using the techniques developed in the present study, are in good agreement with those determined by the well-established techniques using the spectrophotometry.

  10. Epigenetic suppression of potassium-chloride co-transporter 2 expression in inflammatory pain induced by complete Freund's adjuvant (CFA). (United States)

    Lin, C-R; Cheng, J-K; Wu, C-H; Chen, K-H; Liu, C-K


    Multiple mechanisms contribute to the stimulus-evoked pain hypersensitivity that may be experienced after peripheral inflammation. Persistent pathological stimuli in many pain conditions affect the expression of certain genes through epigenetic alternations. The main purpose of our study was to investigate the role of epigenetic modification on potassium-chloride co-transporter 2 (KCC2) gene expression in the persistence of inflammatory pain. Persistent inflammatory pain was induced through the injection of complete Freund's adjuvant (CFA) in the left hind paw of rats. Acetyl-histone H3 and H4 level was determined by chromatin immunoprecipitation in the spinal dorsal horn. Pain behaviour and inhibitory synaptic function of spinal cord were determined before and after CFA injection. KCC2 expression was determined by real time RT-PCR and Western blot. Intrathecal KCC2 siRNA (2 μg per 10 μL per rat) or HDAC inhibitor (10 μg per 10 μL per rat) was injected once daily for 3 days before CFA injection. Persistent inflammatory pain epigenetically suppressed KCC2 expression through histone deacetylase (HDAC)-mediated histone hypoacetylation, resulting in decreased inhibitory signalling efficacy. KCC2 knock-down caused by intrathecal administration of KCC2 siRNA in naïve rats reduced KCC2 expression in the spinal cord, leading to sensitized pain behaviours and impaired inhibitory synaptic transmission in their spinal cords. Moreover, intrathecal HDAC inhibitor injection in CFA rats increased KCC2 expression, partially restoring the spinal inhibitory synaptic transmission and relieving the sensitized pain behaviour. These findings suggest that the transcription of spinal KCC2 is regulated by histone acetylation epigenetically following CFA. Persistent pain suppresses KCC2 expression through HDAC-mediated histone hypoacetylation and consequently impairs the inhibitory function of inhibitory interneurons. Drugs such as HDAC inhibitors that suppress the influences of

  11. Pharmacological activation of rapid delayed rectifier potassium current suppresses bradycardia-induced triggered activity in the isolated guinea pig heart

    DEFF Research Database (Denmark)

    Hansen, Rie Schultz; Olesen, Søren-Peter; Grunnet, Morten


    Recently, attention has been drawn to compounds that activate the human ether-a-go-go channel potassium channel (hERG), which is responsible for the repolarizing rapid delayed rectifier potassium current (I(Kr)) in the mammalian myocardium. The compound NS3623 [N-(4-bromo-2-(1H-tetrazol-5-yl...

  12. The endosomal trafficking factors CORVET and ESCRT suppress plasma membrane residence of the renal outer medullary potassium channel (ROMK). (United States)

    Mackie, Timothy D; Kim, Bo-Young; Subramanya, Arohan R; Bain, Daniel J; O'Donnell, Allyson F; Welling, Paul A; Brodsky, Jeffrey L


    Protein trafficking can act as the primary regulatory mechanism for ion channels with high open probabilities, such as the r enal o uter m edullary (ROMK) channel. ROMK, also known as Kir1.1 (KCNJ1), is the major route for potassium secretion into the pro-urine and plays an indispensable role in regulating serum potassium and urinary concentrations. However, the cellular machinery that regulates ROMK trafficking has not been fully defined. To identify regulators of the cell-surface population of ROMK, we expressed a pH-insensitive version of the channel in the budding yeast Saccharomyces cerevisiae We determined that ROMK primarily resides in the endoplasmic reticulum (ER), as it does in mammalian cells, and is subject to ER-associated degradation (ERAD). However, sufficient ROMK levels on the plasma membrane rescued growth on low-potassium medium of yeast cells lacking endogenous potassium channels. Next, we aimed to identify the biological pathways most important for ROMK regulation. Therefore, we used a synthetic genetic array to identify non-essential genes that reduce the plasma membrane pool of ROMK in potassium-sensitive yeast cells. Genes identified in this screen included several members of the endosomal complexes required for transport (ESCRT) and the class-C core vacuole/endosome tethering (CORVET) complexes. Mass spectroscopy analysis confirmed that yeast cells lacking an ESCRT component accumulate higher potassium concentrations. Moreover, silencing of ESCRT and CORVET components increased ROMK levels at the plasma membrane in HEK293 cells. Our results indicate that components of the post-endocytic pathway influence the cell-surface density of ROMK and establish that components in this pathway modulate channel activity.

  13. Formation of layer-by-layer assembled titanate nanotubes filled coating on flexible polyurethane foam with improved flame retardant and smoke suppression properties. (United States)

    Pan, Haifeng; Wang, Wei; Pan, Ying; Song, Lei; Hu, Yuan; Liew, Kim Meow


    A fire blocking coating made from chitosan, titanate nanotubes and alginate was deposited on a flexible polyurethane (FPU) foam surface by a layer-by-layer assembly technique in an effort to reduce its flammability. First, titanate nanotubes were prepared by a hydrothermal method. And then the coating growth was carried out by alternately submerging FPU foams into chitosan solution, titanate nanotubes suspension and alginate solution. The mass gain of coating on the surface of FPU foams showed dependency on the concentration of titanate nanotubes suspension and the trilayers's number. Scanning electron microscopy indicated that titanate nanotubes were distributed well on the entire surface of FPU foam and showed a randomly oriented and entangled network structure. The cone calorimeter result indicated that the coated FPU foams showed reduction in the peak heat release rate (peak HRR), peak smoke production rate (peak SPR), total smoke release (TSR) and peak carbon monoxide (CO) production compared with those of the control FPU foam. Especially for the FPU foam with only 5.65 wt % mass gain, great reduction in peak HRR (70.2%), peak SPR (62.8%), TSR (40.9%) and peak CO production (63.5%) could be observed. Such a significant improvement in flame retardancy and the smoke suppression property for FPU foam could be attributed to the protective effect of titanate nanotubes network structure formed, including insulating barrier effect and adsorption effect.

  14. Flame-retardant-wrapped polyphosphazene nanotubes: A novel strategy for enhancing the flame retardancy and smoke toxicity suppression of epoxy resins. (United States)

    Qiu, Shuilai; Wang, Xin; Yu, Bin; Feng, Xiaming; Mu, Xiaowei; Yuen, Richard K K; Hu, Yuan


    The structure of polyphosphazene nanotubes (PZS) is similar to that of carbon nanotubes (CNTs) before modification. For applications of CNTs in polymer composites, surface wrapping is an economically attractive route to achieve functionalized nanotubes. Based on this idea, functionalized polyphosphazene nanotubes (FR@PZS) wrapped with a cross-linked DOPO-based flame retardant (FR) were synthesized via one-step strategy and well characterized. Then, the obtained FR@PZS was introduced into epoxy resin (EP) to investigate flame retardancy and smoke toxicity suppression performance. Thermogravimetric analysis indicated that FR@PZS significantly enhanced the thermal stability of EP composites. Cone calorimeter results revealed that incorporation of FR@PZS obviously improved flame retardant performance of EP, for example, 46.0% decrease in peak heat release rate and 27.1% reduction in total heat release were observed in the case of epoxy composite with 3wt% FR@PZS. The evolution of toxic CO and other volatile products from the EP decomposition was significantly suppressed after the introduction of FR@PZS, Therefore, the smoke toxicity associates with burning EP was reduced. The presence of both PZS and a DOPO-based flame retardant was probably responsible for this substantial diminishment of fire hazard. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Suppression of Powdery Mildew Using the Water Extract of Xylogone ganodermophthora and Aqueous Potassium Phosphonate Solution on Watermelon under Greenhouse Conditions

    Directory of Open Access Journals (Sweden)

    Hyo-Jung Kang


    Full Text Available Xylogone ganodermophthora (Xg is an ascomycetous fungus that causes yellow rot on cultivated Ganoderma lucidum. Previously, we reported in vitro antifungal activities of a Xg culture extract against several watermelon pathogens. In 2014, we conducted greenhouse experiments to evaluate the control efficacy of a water extract of cultured Xg on watermelon powdery mildew (WPM. The test material (stock solution, ca. 4,000 µg/ml was prepared by an autoclaved Xg culture in water at a ratio of 800 g of culture per 6 liter of water, and then filtering it through filter paper. Six foliar applications of the solutions (diluted 100- and 1,000-fold significantly suppressed the formation of conidiophores and conidia. The inhibitory effect of aqueous potassium phosphonate solution on the disease and its phytotoxicity was tested. Phytotoxicity on watermelon plants was observed at concentrations of 1,000 and 2,000 µg/ml as irregular brownish spots. The control efficacies against WPM were 91.9% at 2,000 µg/ml, 64.9% at 1,000 µg/ml, and 62.2% at 500 µg/ml.

  16. Inhibition of SK4 Potassium Channels Suppresses Cell Proliferation, Migration and the Epithelial-Mesenchymal Transition in Triple-Negative Breast Cancer Cells.

    Directory of Open Access Journals (Sweden)

    Panshi Zhang

    Full Text Available Treatments for triple-negative breast cancer (TNBC are limited; intermediate-conductance calcium-activated potassium (SK4 channels are closely involved in tumor progression, but little is known about these channels in TNBC. We aimed to investigate whether SK4 channels affect TNBC. First, by immunohistochemistry (IHC and western blotting (WB, increased SK4 protein expression in breast tumor tissues was detected relative to that in non-tumor breast tissues, but there was no apparent expression difference between various subtypes of breast cancer (p>0.05. Next, functional SK4 channels were detected in the TNBC cell line MDA-MB-231 using WB, real-time PCR, immunofluorescence and patch-clamp recording. By employing SK4 specific siRNAs and blockers, including TRAM-34 and clotrimazole, in combination with an MTT assay, a colony-formation assay, flow cytometry and a cell motility assay, we found that the suppression of SK4 channels significantly inhibited cell proliferation and migration and promoted apoptosis in MDA-MB-231 cells (p<0.05. Further investigation revealed that treatment with epidermal growth factor (EGF/basic fibroblast growth factor (bFGF caused MDA-MB-231 cells to undergo the epithelial-mesenchymal transition (EMT and to show increased SK4 mRNA expression. In addition, the down-regulation of SK4 expression inhibited the EMT markers Vimentin and Snail1. Collectively, our findings suggest that SK4 channels are expressed in TNBC and are involved in the proliferation, apoptosis, migration and EMT processes of TNBC cells.

  17. Continuous Carbon Nanotube-Ultrathin Graphite Hybrid Foams for Increased Thermal Conductivity and Suppressed Subcooling in Composite Phase Change Materials. (United States)

    Kholmanov, Iskandar; Kim, Jaehyun; Ou, Eric; Ruoff, Rodney S; Shi, Li


    Continuous ultrathin graphite foams (UGFs) have been actively researched recently to obtain composite materials with increased thermal conductivities. However, the large pore size of these graphitic foams has resulted in large thermal resistance values for heat conduction from inside the pore to the high thermal conductivity graphitic struts. Here, we demonstrate that the effective thermal conductivity of these UGF composites can be increased further by growing long CNT networks directly from the graphite struts of UGFs into the pore space. When erythritol, a phase change material for thermal energy storage, is used to fill the pores of UGF-CNT hybrids, the thermal conductivity of the UGF-CNT/erythritol composite was found to increase by as much as a factor of 1.8 compared to that of a UGF/erythritol composite, whereas breaking the UGF-CNT bonding in the hybrid composite resulted in a drop in the effective room-temperature thermal conductivity from about 4.1 ± 0.3 W m(-1) K(-1) to about 2.9 ± 0.2 W m(-1) K(-1) for the same UGF and CNT loadings of about 1.8 and 0.8 wt %, respectively. Moreover, we discovered that the hybrid structure strongly suppresses subcooling of erythritol due to the heterogeneous nucleation of erythritol at interfaces with the graphitic structures.

  18. Potassium clavulanate

    Directory of Open Access Journals (Sweden)

    Kotaro Fujii


    Full Text Available The title salt, K+·C8H8NO5− [systematic name: potassium (2R,5R,Z-3-(2-hydroxyethylidene-7-oxo-4-oxa-1-azabicyclo[3.2.0]heptane-2-carboxylate], a widely used β-lactam antibiotic, is usually chemically unstable even in the solid state owing to its tendency to be hydrolysed. In the crystal structure, the potassium cations are arranged along the a axis, forming interactions to the carboxylate and hydroxy groups, resulting in one-dimensional ionic columns. These columns are arranged along the b axis, connected by O—H...O hydrogen bonds, forming a layer in the ab plane.

  19. Radiodine administration under suppression of TSH for identification of false positive receptions in patients with thyroid differentiated carcinoma (TDC): utility of the potassium perchlorate

    International Nuclear Information System (INIS)

    Santangelo, L.A.; Pitoia, F.; Sanz, C.; Niepomniszcze, H.; El Tamer, Elias


    The total body scan, after a dose of 131 I correlated with the measurement of stimulated Tg, constitute the principal pillars in follow-up of patients with TDC (thyroid differentiated carcinoma). A bibliographical search revealed more than 70 situations that can cause false total body scans positive. The examination is essential to avoid unnecessary treatment with radioiodine. The object is to evaluate the effectiveness of the radioiodine administration under hormonal therapy thyroid suppressive (THST) to eliminate the possibility of a false total body scan positive in five patients with TDC with stimulated Tg <1ng/ml

  20. Potassium Blood Test (United States)

    ... page: Potassium Blood Test To use the sharing features on this page, please enable JavaScript. What is a Potassium Blood Test? A potassium blood test measures the amount of ...

  1. Elevated extracellular potassium ion concentrations suppress ...

    African Journals Online (AJOL)

    To address this question, we examined how elevations of [K+]o affect hippocampal oscillations in Scn1a mutant mouse, a mouse model of Dravet syndrome, a devastating genetic-epilepsy associated with gliosis, a major cause of dysregulated K+ homeostasis in epileptic brain. Methods: To this end, performing local field ...

  2. Subwoofer and nanotube butterfly acoustic flame extinction

    NARCIS (Netherlands)

    Aliev, Ali E.; Mayo, Nathanael K.; Baughman, Ray H.; Mills, Brent T.; Habtour, Ed


    Nonchemical flame control using acoustic waves from a subwoofer and a lightweight carbon nanotube thermoacoustic projector was demonstrated. The intent was to manipulate flame intensity, direction and propagation. The mechanisms of flame suppression using low frequency acoustic waves were discussed.

  3. Function of RSKS-1-AAK-2-DAF-16 signaling cascade in enhancing toxicity of multi-walled carbon nanotubes can be suppressed by mir-259 activation in Caenorhabditis elegans (United States)

    Zhuang, Ziheng; Li, Min; Liu, Hui; Luo, Libo; Gu, Weidong; Wu, Qiuli; Wang, Dayong


    Caenorhabditis elegans is an important non-mammalian alternative assay model for toxicological study. Previous study has indicated that exposure to multi-walled carbon nanotubes (MWCNTs) dysregulated the transcriptional expression of mir-259. In this study, we examined the molecular basis for mir-259 in regulating MWCNTs toxicity in nematodes. Mutation of mir-259 induced a susceptible property to MWCNTs toxicity, and MWCNTs exposure induced a significant increase in mir-259::GFP in pharyngeal/intestinal valve and reproductive tract, implying that mir-259 might mediate a protection mechanisms for nematodes against MWCNTs toxicity. RSKS-1, a putative ribosomal protein S6 kinase, acted as the target for mir-259 in regulating MWCNTs toxicity, and mutation of rsks-1 suppressed the susceptible property of mir-259 mutant to MWCNTs toxicity. Moreover, mir-259 functioned in pharynx-intestinal valve and RSKS-1 functioned in pharynx to regulate MWCNTs toxicity. Furthermore, RSKS-1 regulated MWCNTs toxicity by suppressing the function of AAK-2-DAF-16 signaling cascade. Our results will strengthen our understanding the microRNAs mediated protection mechanisms for animals against the toxicity from certain nanomaterials.

  4. Nanotube junctions (United States)

    Crespi, Vincent Henry; Cohen, Marvin Lou; Louie, Steven Gwon Sheng; Zettl, Alexander Karlwalter


    The present invention comprises a new nanoscale metal-semiconductor, semiconductor-semiconductor, or metal-metal junction, designed by introducing topological or chemical defects in the atomic structure of the nanotube. Nanotubes comprising adjacent sections having differing electrical properties are described. These nanotubes can be constructed from combinations of carbon, boron, nitrogen and other elements. The nanotube can be designed having different indices on either side of a junction point in a continuous tube so that the electrical properties on either side of the junction vary in a useful fashion. For example, the inventive nanotube may be electrically conducting on one side of a junction and semiconducting on the other side. An example of a semiconductor-metal junction is a Schottky barrier. Alternatively, the nanotube may exhibit different semiconductor properties on either side of the junction. Nanotubes containing heterojunctions, Schottky barriers, and metal-metal junctions are useful for microcircuitry.

  5. Inorganic nanotubes. (United States)

    Tenne, Reshef; Rao, C N R


    Following the discovery of carbon fullerenes and carbon nanotubes, it was hypothesized that nanoparticles of inorganic compounds with layered (two-dimensional) structure, such as MoS(2), will not be stable against folding and form nanotubes and fullerene-like structures: IF. The synthesis of numerous other inorganic nanotubes has been reported in recent years. Various techniques for the synthesis of inorganic nanotubes, including high-temperature reactions and strategies based on 'chemie douce' (soft chemistry, i.e. low-temperature) processes, are described. First-principle, density functional theory based calculations are able to provide substantial information on the structure and properties of such nanotubes. Various properties of inorganic nanotubes, including mechanical, electronic and optical properties, are described in brief. Some potential applications of the nanotubes in tribology, protection against impact, (photo)catalysis, batteries, etc., are discussed.

  6. Potassium in diet (United States)

    ... potassium to: Build proteins Break down and use carbohydrates Build muscle Maintain normal body growth Control the electrical activity of the heart Control the acid-base balance Food Sources Many foods contain potassium. All meats (red meat ...

  7. KV7 potassium channels

    DEFF Research Database (Denmark)

    Stott, Jennifer B; Jepps, Thomas Andrew; Greenwood, Iain A


    Potassium channels are key regulators of smooth muscle tone, with increases in activity resulting in hyperpolarisation of the cell membrane, which acts to oppose vasoconstriction. Several potassium channels exist within smooth muscle, but the KV7 family of voltage-gated potassium channels have been...

  8. Potassium fluorotitanate preparation

    International Nuclear Information System (INIS)

    Perillo, Patricia; Ares, Osvaldo; Botbol, Jose.


    In order to determine the best conditions for potassium fluotitanate preparation as intermediate step in the electrolytic production of metalic titanium, the effects of a number of experimental variables have been studied. This method is a process of sintering titanium dioxide with potassium fluosilicate and potassium chloride, followed by leaching with boiling water and further crystallization by cooling the solution. An overall yield of 90% has been attained under the following conditions: working temperature: 750 deg C; heating time for sintering: 3 hours; molar ratio: titanium dioxide: potassium fluosilicate: potassium chloride: 1 : 2 : 0.4; number of leachings: 6. (Author) [es

  9. High potassium level (United States)

    ... level URL of this page: // High potassium level To use the sharing features on this page, ... There are often no symptoms with a high level of potassium. When symptoms do occur, they may include: Nausea Slow, weak, or irregular pulse Sudden collapse, when ...

  10. Chemical functionalization of carbon nanotubes with 3-methacryloxypropyltrimethoxysilane (3-MPTS) (United States)

    Bag, Dibyendu S.; Dubey, Rama; Zhang, N.; Xie, J.; Varadan, V. K.; Lal, D.; Mathur, G. N.


    Multiwalled carbon nanotubes (MWNTs) were functionalized by oxidation with potassium permanganate using a phase transfer catalyst. The functionalized nanotubes (f-CNTs) were allowed to react with a functional chemical such as 3-methacryloxypropyltrimethoxysilane (3-MPTS). The f-CNTs and the reaction product of f-CNTs and 3-MPTS (fs-CNTs) were characterized by Fourier transform infrared and energy dispersion spectroscopy and also by scanning electron microscopy and transmission electron microscopy analysis. The MWNTs attached to the organofunctional moieties have a greater versatility for further utilization of nanotubes in different applications.

  11. Nanotube cathodes.

    Energy Technology Data Exchange (ETDEWEB)

    Overmyer, Donald L.; Lockner, Thomas Ramsbeck; Siegal, Michael P.; Miller, Paul Albert


    Carbon nanotubes have shown promise for applications in many diverse areas of technology. In this report we describe our efforts to develop high-current cathodes from a variety of nanotubes deposited under a variety of conditions. Our goal was to develop a one-inch-diameter cathode capable of emitting 10 amperes of electron current for one second with an applied potential of 50 kV. This combination of current and pulse duration significantly exceeds previously reported nanotube-cathode performance. This project was planned for two years duration. In the first year, we tested the electron-emission characteristics of nanotube arrays fabricated under a variety of conditions. In the second year, we planned to select the best processing conditions, to fabricate larger cathode samples, and to test them on a high-power relativistic electron beam generator. In the first year, much effort was made to control nanotube arrays in terms of nanotube diameter and average spacing apart. When the project began, we believed that nanotubes approximately 10 nm in diameter would yield sufficient electron emission properties, based on the work of others in the field. Therefore, much of our focus was placed on measured field emission from such nanotubes grown on a variety of metallized surfaces and with varying average spacing between individual nanotubes. We easily reproduced the field emission properties typically measured by others from multi-wall carbon nanotube arrays. Interestingly, we did this without having the helpful vertical alignment to enhance emission; our nanotubes were randomly oriented. The good emission was most likely possible due to the improved crystallinity, and therefore, electrical conductivity, of our nanotubes compared to those in the literature. However, toward the end of the project, we learned that while these 10-nm-diameter CNTs had superior crystalline structure to the work of others studying field emission from multi-wall CNT arrays, these nanotubes still

  12. Nanotube cathodes

    International Nuclear Information System (INIS)

    Overmyer, Donald L.; Lockner, Thomas Ramsbeck; Siegal, Michael P.; Miller, Paul Albert


    Carbon nanotubes have shown promise for applications in many diverse areas of technology. In this report we describe our efforts to develop high-current cathodes from a variety of nanotubes deposited under a variety of conditions. Our goal was to develop a one-inch-diameter cathode capable of emitting 10 amperes of electron current for one second with an applied potential of 50 kV. This combination of current and pulse duration significantly exceeds previously reported nanotube-cathode performance. This project was planned for two years duration. In the first year, we tested the electron-emission characteristics of nanotube arrays fabricated under a variety of conditions. In the second year, we planned to select the best processing conditions, to fabricate larger cathode samples, and to test them on a high-power relativistic electron beam generator. In the first year, much effort was made to control nanotube arrays in terms of nanotube diameter and average spacing apart. When the project began, we believed that nanotubes approximately 10 nm in diameter would yield sufficient electron emission properties, based on the work of others in the field. Therefore, much of our focus was placed on measured field emission from such nanotubes grown on a variety of metallized surfaces and with varying average spacing between individual nanotubes. We easily reproduced the field emission properties typically measured by others from multi-wall carbon nanotube arrays. Interestingly, we did this without having the helpful vertical alignment to enhance emission; our nanotubes were randomly oriented. The good emission was most likely possible due to the improved crystallinity, and therefore, electrical conductivity, of our nanotubes compared to those in the literature. However, toward the end of the project, we learned that while these 10-nm-diameter CNTs had superior crystalline structure to the work of others studying field emission from multi-wall CNT arrays, these nanotubes still

  13. Penicillin V Potassium (United States)

    ... if you are allergic to penicillin V potassium, tartrazine (a yellow dye in some processed foods and ... in, tightly closed, and out of reach of children. Store the tablets at room temperature and away ...

  14. Nanotube phonon waveguide (United States)

    Chang, Chih-Wei; Zettl, Alexander K.


    Disclosed are methods and devices in which certain types of nanotubes (e.g., carbon nanotubes and boron nitride nanotubes conduct heat with high efficiency and are therefore useful in electronic-type devices.

  15. Nanotube News (United States)

    Journal of College Science Teaching, 2005


    Smaller, faster computers, bullet-proof t-shirts, and itty-bitty robots--such are the promises of nanotechnology and the cylinder-shaped collection of carbon molecules known as nanotubes. But for these exciting ideas to become realities, scientists must understand how these miracle molecules perform under all sorts of conditions. This brief…

  16. Errors in potassium balance

    International Nuclear Information System (INIS)

    Forbes, G.B.; Lantigua, R.; Amatruda, J.M.; Lockwood, D.H.


    Six overweight adult subjects given a low calorie diet containing adequate amounts of nitrogen but subnormal amounts of potassium (K) were observed on the Clinical Research Center for periods of 29 to 40 days. Metabolic balance of potassium was measured together with frequent assays of total body K by 40 K counting. Metabolic K balance underestimated body K losses by 11 to 87% (average 43%): the intersubject variability is such as to preclude the use of a single correction value for unmeasured losses in K balance studies

  17. Carbon nanotubes: Sensor properties. A review

    Directory of Open Access Journals (Sweden)

    Irina V. Zaporotskova


    Full Text Available Recent publications dealing with dealing with the fabrication of gas and electrochemical biosensors based on carbon nanotubes have been reviewed. Experimental and theoretical data on the working principles of nanotubes have been presented. The main regularities of the structure, energy parameters and sensor properties of modified semiconducting systems on the basis of cabon nanotubes have been studied by analyzing the mechanisms of nanotubule interaction with functional groups (including carboxyl and amino groups, metallic nanoparticles and polymers leading to the formation of chemically active sensors. The possibility of using boundary modified nanotubes for the identification of metals has been discussed. Simulation results have been reported for the interaction of nanotubes boundary modified by –СООН and –NH2 groups with atoms and ions of potassium, sodium and lithium. The simulation has been carried out using the molecular cluster model and the MNDO and DFT calculation methods. Sensors fabricated using this technology will find wide application for the detection of metallic atoms and their ions included in salts and alkali.

  18. Carbon nanotube composite materials (United States)

    O'Bryan, Gregory; Skinner, Jack L; Vance, Andrew; Yang, Elaine Lai; Zifer, Thomas


    A material consisting essentially of a vinyl thermoplastic polymer, un-functionalized carbon nanotubes and hydroxylated carbon nanotubes dissolved in a solvent. Un-functionalized carbon nanotube concentrations up to 30 wt % and hydroxylated carbon nanotube concentrations up to 40 wt % can be used with even small concentrations of each (less than 2 wt %) useful in producing enhanced conductivity properties of formed thin films.

  19. Functionalization of Carbon Nanotubes (United States)

    Khare, Bishun N. (Inventor); Meyyappan, Meyya (Inventor)


    Method and system for functionalizing a collection of carbon nanotubes (CNTs). A selected precursor gas (e.g., H2 or F2 or CnHm) is irradiated to provide a cold plasma of selected target species particles, such as atomic H or F, in a first chamber. The target species particles are d irected toward an array of CNTs located in a second chamber while suppressing transport of ultraviolet radiation to the second chamber. A CNT array is functionalized with the target species particles, at or below room temperature, to a point of saturation, in an exposure time interval no longer than about 30 sec. *Discrimination against non-target species is provided by (i) use of a target species having a lifetime that is much greater than a lifetime of a non-target species and/or (2) use of an applied magnetic field to discriminate between charged particle trajectories for target species and for non-target species.

  20. Potassium Channelopathies and Gastrointestinal Ulceration. (United States)

    Han, Jaeyong; Lee, Seung Hun; Giebisch, Gerhard; Wang, Tong


    Potassium channels and transporters maintain potassium homeostasis and play significant roles in several different biological actions via potassium ion regulation. In previous decades, the key revelations that potassium channels and transporters are involved in the production of gastric acid and the regulation of secretion in the stomach have been recognized. Drugs used to treat peptic ulceration are often potassium transporter inhibitors. It has also been reported that potassium channels are involved in ulcerative colitis. Direct toxicity to the intestines from nonsteroidal anti-inflammatory drugs has been associated with altered potassium channel activities. Several reports have indicated that the long-term use of the antianginal drug Nicorandil, an adenosine triphosphate-sensitive potassium channel opener, increases the chances of ulceration and perforation from the oral to anal regions throughout the gastrointestinal (GI) tract. Several of these drug features provide further insights into the role of potassium channels in the occurrence of ulceration in the GI tract. The purpose of this review is to investigate whether potassium channelopathies are involved in the mechanisms responsible for ulceration that occurs throughout the GI tract.

  1. Potassium Sensing by Renal Distal Tubules Requires Kir4.1. (United States)

    Cuevas, Catherina A; Su, Xiao-Tong; Wang, Ming-Xiao; Terker, Andrew S; Lin, Dao-Hong; McCormick, James A; Yang, Chao-Ling; Ellison, David H; Wang, Wen-Hui


    The mammalian distal convoluted tubule (DCT) makes an important contribution to potassium homeostasis by modulating NaCl transport. The thiazide-sensitive Na + /Cl - cotransporter (NCC) is activated by low potassium intake and by hypokalemia. Coupled with suppression of aldosterone secretion, activation of NCC helps to retain potassium by increasing electroneutral NaCl reabsorption, therefore reducing Na + /K + exchange. Yet the mechanisms by which DCT cells sense plasma potassium concentration and transmit the information to the apical membrane are not clear. Here, we tested the hypothesis that the potassium channel Kir4.1 is the potassium sensor of DCT cells. We generated mice in which Kir4.1 could be deleted in the kidney after the mice are fully developed. Deletion of Kir4.1 in these mice led to moderate salt wasting, low BP, and profound potassium wasting. Basolateral membranes of DCT cells were depolarized, nearly devoid of conductive potassium transport, and unresponsive to plasma potassium concentration. Although renal WNK4 abundance increased after Kir4.1 deletion, NCC abundance and function decreased, suggesting that membrane depolarization uncouples WNK kinases from NCC. Together, these results indicate that Kir4.1 mediates potassium sensing by DCT cells and couples this signal to apical transport processes. Copyright © 2017 by the American Society of Nephrology.

  2. High frequency conductivity in carbon nanotubes

    Directory of Open Access Journals (Sweden)

    S. S. Abukari


    Full Text Available We report on theoretical analysis of high frequency conductivity in carbon nanotubes. Using the kinetic equation with constant relaxation time, an analytical expression for the complex conductivity is obtained. The real part of the complex conductivity is initially negative at zero frequency and become more negative with increasing frequency, until it reaches a resonance minimum at ω ∼ ωB for metallic zigzag CNs and ω < ωB for armchair CNs. This resonance enhancement is indicative for terahertz gain without the formation of current instabilities induced by negative dc conductivity. We noted that due to the high density of states of conduction electrons in metallic zigzag carbon nanotubes and the specific dispersion law inherent in hexagonal crystalline structure result in a uniquely high frequency conductivity than the corresponding values for metallic armchair carbon nanotubes. We suggest that this phenomenon can be used to suppress current instabilities that are normally associated with a negative dc differential conductivity.

  3. Carbon nanotube nanoelectrode arrays (United States)

    Ren, Zhifeng; Lin, Yuehe; Yantasee, Wassana; Liu, Guodong; Lu, Fang; Tu, Yi


    The present invention relates to microelectode arrays (MEAs), and more particularly to carbon nanotube nanoelectrode arrays (CNT-NEAs) for chemical and biological sensing, and methods of use. A nanoelectrode array includes a carbon nanotube material comprising an array of substantially linear carbon nanotubes each having a proximal end and a distal end, the proximal end of the carbon nanotubes are attached to a catalyst substrate material so as to form the array with a pre-determined site density, wherein the carbon nanotubes are aligned with respect to one another within the array; an electrically insulating layer on the surface of the carbon nanotube material, whereby the distal end of the carbon nanotubes extend beyond the electrically insulating layer; a second adhesive electrically insulating layer on the surface of the electrically insulating layer, whereby the distal end of the carbon nanotubes extend beyond the second adhesive electrically insulating layer; and a metal wire attached to the catalyst substrate material.

  4. Potassium oxalurate monohydrate

    Directory of Open Access Journals (Sweden)


    Full Text Available The title salt, poly[aqua-μ3-oxalurato-potassium(I], [K(C3H3N2O4(H2O]n, which was obtained from a water solution of oxaluric acid and KOH at room temperature, crystallizes as potassium and oxalurate ions along with a water molecule. The K+ cation lies on a crystallographic twofold rotation axis (site symmetry 2, Wyckoff position f, and the water and oxalurate molecules are located within different mirror planes (site symmetry m, Wyckoff position g. The K+ cation is eight-coordinated by six O atoms of six oxalurate ligands and two O atoms from two water molecules in a distorted square-antiprismatic geometry. All of the eight coordinated O atoms are in a monodentate bridging mode, with alternate bridged K...K distances of 3.5575 (12 and 3.3738 (12 Å. The oxalurate ligand shows a μ3-bridging coordination mode, which links the K+ cation into a three-dimensional network. The oxalurate ligands and the water molecules are involved in inter- and intramolecular N—H...O, and O—H...O hydrogen bonds, which stabilize the network.

  5. 21 CFR 184.1619 - Potassium carbonate. (United States)


    ... solution of potassium hydroxide with excess carbon dioxide to produce potassium carbonate; (3) By treating a solution of potassium hydroxide with carbon dioxide to produce potassium bicarbonate, which is... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium carbonate. 184.1619 Section 184.1619 Food...

  6. Potassium in milk and milk products

    International Nuclear Information System (INIS)

    Sombrito, E.Z.; Nuguid, Z.F.S.; Tangonan, M.C.


    The amount of potassium in imported processed milk was determined by gamma spectral analysis. The results show that the potassium content of diluted infant formula milk is closest to the reported mean concentration of potassium in human milk while other milk types have potassium values similar to the potassium content of cow milk. (Auth.). 2 figs., 5 refs

  7. Carbon nanotube quantum dots

    NARCIS (Netherlands)

    Sapmaz, S.


    Low temperature electron transport measurements on individual single wall carbon nanotubes are described in this thesis. Carbon nanotubes are small hollow cylinders made entirely out of carbon atoms. At low temperatures (below ~10 K) finite length nanotubes form quantum dots. Because of its small

  8. Dietary reference values for potassium

    DEFF Research Database (Denmark)

    Sjödin, Anders Mikael


    Following a request from the European Commission, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) derives dietary reference values (DRVs) for potassium. The Panel decides to set DRVs on the basis of the relationships between potassium intake and blood pressure and stroke...

  9. Potassium supplementation and heart rate

    NARCIS (Netherlands)

    Gijsbers, L.; Molenberg, Famke; Bakker, S.J.L.; Geleijnse, J.M.


    Background and aims: Increasing the intake of potassium has been shown to lower blood pressure, but whether it also affects heart rate (HR) is largely unknown. We therefore assessed the effect of potassium supplementation on HR in a meta-analysis of randomized controlled trials. Methods and

  10. Neural synchronization via potassium signaling

    DEFF Research Database (Denmark)

    Postnov, Dmitry E; Ryazanova, Ludmila S; Mosekilde, Erik


    Using a relatively simple model we examine how variations of the extracellular potassium concentration can give rise to synchronization of two nearby pacemaker cells. With the volume of the extracellular space and the rate of potassium diffusion as control parameters, the dual nature of this reso...

  11. Neural Synchronization via Potassium Signaling,

    DEFF Research Database (Denmark)

    Postnov, D. E.; Ryazanova, L. S.; Sosnovtseva, Olga


    Using a relatively simple model we examine how variations of the extracellular potassium concentration can give rise to synchronization of two nearby pacemaker cells. With the volume of the extracellular space and the rate of potassium diffusion as control parameters, the dual nature of this reso...

  12. Can Diuretics Decrease Your Potassium Level? (United States)

    ... of low potassium? Can diuretics decrease your potassium level? Answers from Sheldon G. Sheps, M.D. Yes, ... your urine. This can lead to low potassium levels in your blood (hypokalemia). Signs and symptoms of ...

  13. Cardiac potassium channel subtypes

    DEFF Research Database (Denmark)

    Schmitt, Nicole; Grunnet, Morten; Olesen, Søren-Peter


    . The underlying posttranscriptional and posttranslational remodeling of the individual K(+) channels changes their activity and significance relative to each other, and they must be viewed together to understand their role in keeping a stable heart rhythm, also under menacing conditions like attacks of reentry......About 10 distinct potassium channels in the heart are involved in shaping the action potential. Some of the K(+) channels are primarily responsible for early repolarization, whereas others drive late repolarization and still others are open throughout the cardiac cycle. Three main K(+) channels...... that they could constitute targets for new pharmacological treatment of atrial fibrillation. The interplay between the different K(+) channel subtypes in both atria and ventricle is dynamic, and a significant up- and downregulation occurs in disease states such as atrial fibrillation or heart failure...

  14. Potassium iodide stockpiling

    International Nuclear Information System (INIS)

    Krimm, R.W.


    After examination by the Federal Emergency Management Agency (FEMA) and other federal agencies of federal policy on the use and distribution of potassium iodide (KI) as a thyroid-blocking agent for use in off-site preparedness around commercial nuclear powerplants, FEMA believes the present shelf life of KI is too short, that the minimum ordering quantities are an obstacle to efficient procurement, and that the packaging format offered by the drug industry does not meet the wishes of state and local government officials. FEMA has asked assistance from the Food and Drug Administration in making it possible for those states wishing to satisfy appropriate requirements to do so at the minimum cost to the public. Given an appropriate packaging and drug form, there appears to be no reason for the federal government to have further involvement in the stockpiling of KI

  15. Suppression of c-Myc is involved in multi-walled carbon nanotubes' down-regulation of ATP-binding cassette transporters in human colon adenocarcinoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhaojing [Department of Pharmacology, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan (China); Xu, Yonghong [Institute of Ophthalmological Research, Department of Ophthalmology, Renmin Hospital of Wuhan University, 430060 Wuhan (China); Meng, Xiangning [School of Materials and Metallurgy, Northeastern University, Shenyang 110819 (China); Watari, Fumio [Department of Biomedical, Dental Materials and Engineering, Graduate School of Dental Medicine, Hokkaido University, Sapporo 060-8586 (Japan); Liu, Hudan, E-mail: [Department of Pharmacology, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan (China); Chen, Xiao, E-mail: [Department of Pharmacology, School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan (China)


    Over-expression of ATP-binding cassette (ABC) transporters, a large family of integral membrane proteins that decrease cellular drug uptake and accumulation by active extrusion, is one of the major causes of cancer multi-drug resistance (MDR) that frequently leads to failure of chemotherapy. Carbon nanotubes (CNTs)-based drug delivery devices hold great promise in enhancing the efficacy of cancer chemotherapy. However, CNTs' effects on the ABC transporters remain under-investigated. In this study, we found that multiwalled carbon nanotubes (MWCNTs) reduced transport activity and expression of ABC transporters including ABCB1/Pgp and ABCC4/MRP4 in human colon adenocarcinoma Caco-2 cells. Proto-oncogene c-Myc, which directly regulates ABC gene expression, was concurrently decreased in MWCNT-treated cells and forced over-expression of c-Myc reversed MWCNTs' inhibitory effects on ABCB1 and ABCC4 expression. MWCNT-cell membrane interaction and cell membrane oxidative damage were observed. However, antioxidants such as vitamin C, β-mecaptoethanol and dimethylthiourea failed to antagonize MWCNTs' down-regulation of ABC transporters. These data suggest that MWCNTs may act on c-Myc, but not through oxidative stress, to down-regulate ABC transporter expression. Our findings thus shed light on CNTs' novel cellular effects that may be utilized to develop CNTs-based drug delivery devices to overcome ABC transporter-mediated cancer chemoresistance.

  16. Functionalized Carbon Nanotubes (United States)

    Lebron, Marisabel; Mintz, Eric; Meador, Michael A.; Hull, David R.; Scheiman, Daniel A.; Willis, Peter; Smalley, Richard E.


    Carbon nanotubes have created a great deal of excitement in the Materials Science community because of their outstanding mechanical, electrical, and thermal properties. Use of carbon nanotubes as reinforcements for polymers could lead to a new class of composite materials with properties, durability, and performance far exceeding that of conventional fiber reinforced composites. Organized arrays of carbon nanotubes, e.g., nanotube monolayers, could find applications as thermal management materials, light emitting devices, and sensor arrays. Carbon nanotubes could also be used as templates upon which nanotubes from other materials could be constructed. Successful use of carbon nanotubes in any of these potential applications requires the ability to control the interactions of nanotubes with each other and with other materials, e.g., a polymer matrix. One approach to achieving this control is to attach certain chemical groups to the ends and/or side-walls of the nanotubes. The nature of these chemical groups can be varied to achieve the desired result, such as better adhesion between the nanotubes and a polymer. Under a joint program between NASA Glenn, Clark Atlanta University, and Rice University researchers are working on developing a chemistry "tool-kit" that will enable the functionalization of carbon nanotubes with a variety of chemical groups. Recent results of this effort will be discussed.

  17. High frequency nanotube oscillator (United States)

    Peng, Haibing [Houston, TX; Zettl, Alexander K [Kensington, TX


    A tunable nanostructure such as a nanotube is used to make an electromechanical oscillator. The mechanically oscillating nanotube can be provided with inertial clamps in the form of metal beads. The metal beads serve to clamp the nanotube so that the fundamental resonance frequency is in the microwave range, i.e., greater than at least 1 GHz, and up to 4 GHz and beyond. An electric current can be run through the nanotube to cause the metal beads to move along the nanotube and changing the length of the intervening nanotube segments. The oscillator can operate at ambient temperature and in air without significant loss of resonance quality. The nanotube is can be fabricated in a semiconductor style process and the device can be provided with source, drain, and gate electrodes, which may be connected to appropriate circuitry for driving and measuring the oscillation. Novel driving and measuring circuits are also disclosed.

  18. Effects of potassium on kesterite solar cells: Similarities, differences and synergies with sodium

    Directory of Open Access Journals (Sweden)

    S. G. Haass


    Full Text Available Addition of alkali dopants is essential for achieving high-efficiency conversion efficiency of thin film solar cells based on chalcogenide semiconductors like Cu(In,GaSe2 (CIGS and Cu2ZnSn(S,Se4 (CZTSSe also called kesterite. Whereas the treatment with potassium allows boosting the performance of CIGS solar cells as compared to the conventional sodium doping, it is debated if similar effects can be expected for kesterite solar cells. Here the influence of potassium is investigated by introducing the dopant during the solution processing of kesterite absorbers. It is confirmed that the presence of potassium leads to an enhanced grain growth and a ten-fold lower potassium concentration is sufficient for obtaining grain size similar to sodium-containing absorbers. Potassium is located predominantly at grain boundaries and it suppresses incorporation of sodium into the absorber layer. The potassium doping increases the apparent carrier concentration to ∼2×1016 cm-3 for a potassium concentration of 0.2 at%. The potassium-doped solar cells yield conversion efficiency close to 10%, on par with only sodium-doped samples. Co-doping with potassium and sodium has not revealed any beneficial synergetic effects and it is concluded that both dopants exhibit similar effects on the kesterite solar cell performance.

  19. Suppressed Belief

    Directory of Open Access Journals (Sweden)

    Komarine Romdenh-Romluc


    Full Text Available Moran’s revised conception of conscious belief requires us to reconceptualise suppressed belief. The work of Merleau-Ponty offers a way to do this. His account of motor-skills allows us to understand suppressed beliefs as pre-reflective ways of dealing with the world.

  20. Potassium Channels in Neurofbromatosis-1

    National Research Council Canada - National Science Library

    Chen, Mingkui


    .... We were the first to investigate potential mechanisms of cognitive impairment in NF-1 at the molecular level involving potassium channels, and demonstrated a possible mechanism for the learning deficits seen in NF1...

  1. Superconductivity in an Inhomogeneous Bundle of Metallic and Semiconducting Nanotubes

    Directory of Open Access Journals (Sweden)

    Ilya Grigorenko


    Full Text Available Using Bogoliubov-de Gennes formalism for inhomogeneous systems, we have studied superconducting properties of a bundle of packed carbon nanotubes, making a triangular lattice in the bundle's transverse cross-section. The bundle consists of a mixture of metallic and doped semiconducting nanotubes, which have different critical transition temperatures. We investigate how a spatially averaged superconducting order parameter and the critical transition temperature depend on the fraction of the doped semiconducting carbon nanotubes in the bundle. Our simulations suggest that the superconductivity in the bundle will be suppressed when the fraction of the doped semiconducting carbon nanotubes will be less than 0.5, which is the percolation threshold for a two-dimensional triangular lattice.

  2. 21 CFR 184.1631 - Potassium hydroxide. (United States)


    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium hydroxide. 184.1631 Section 184.1631 Food... Specific Substances Affirmed as GRAS § 184.1631 Potassium hydroxide. (a) Potassium hydroxide (KOH, CAS Reg... pellets, flakes, sticks, lumps, and powders. Potassium hydroxide is obtained commercially from the...

  3. 21 CFR 184.1643 - Potassium sulfate. (United States)


    ... hydroxide or potassium carbonate. (b) The ingredient meets the specifications of the “Food Chemicals Codex... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium sulfate. 184.1643 Section 184.1643 Food... Specific Substances Affirmed as GRAS § 184.1643 Potassium sulfate. (a) Potassium sulfate (K2SO4, CAS Reg...

  4. Purification of carbon nanotubes via selective heating

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, John A.; Wilson, William L.; Jin, Sung Hun; Dunham, Simon N.; Xie, Xu; Islam, Ahmad; Du, Frank; Huang, Yonggang; Song, Jizhou


    The present invention provides methods for purifying a layer of carbon nanotubes comprising providing a precursor layer of substantially aligned carbon nanotubes supported by a substrate, wherein the precursor layer comprises a mixture of first carbon nanotubes and second carbon nanotubes; selectively heating the first carbon nanotubes; and separating the first carbon nanotubes from the second carbon nanotubes, thereby generating a purified layer of carbon nanotubes. Devices benefiting from enhanced electrical properties enabled by the purified layer of carbon nanotubes are also described.

  5. 21 CFR 184.1625 - Potassium citrate. (United States)


    ... acid with potassium hydroxide or potassium carbonate. It occurs as transparent crystals or a white... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium citrate. 184.1625 Section 184.1625 Food... Specific Substances Affirmed as GRAS § 184.1625 Potassium citrate. (a) Potassium citrate (C6H5K3O7·H2O, CAS...

  6. Resonant ablation of single-wall carbon nanotubes by femtosecond laser pulses

    International Nuclear Information System (INIS)

    Arutyunyan, N R; Komlenok, M S; Kononenko, V V; Pashinin, V P; Pozharov, A S; Konov, V I; Obraztsova, E D


    The thin 50 nm film of bundled arc-discharge single-wall carbon nanotubes was irradiated by femtosecond laser pulses with wavelengths 675, 1350 and 1745 nm corresponding to the absorption band of metallic nanotubes E 11 M , to the background absorption and to the absorption band of semiconducting nanotubes E 11 S , respectively. The aim was to induce a selective removal of nanotubes of specific type from the bundled material. Similar to conducted thermal heating experiments, the effect of laser irradiation results in suppression of all radial breathing modes in the Raman spectra, with preferential destruction of the metallic nanotubes with diameters less than 1.26 nm and of the semiconducting nanotubes with diameters 1.36 nm. However, the etching rate of different nanotubes depends on the wavelength of the laser irradiation. It is demonstrated that the relative content of nanotubes of different chiralities can be tuned by a resonant laser ablation of undesired nanotube fraction. The preferential etching of the resonant nanotubes has been shown for laser wavelengths 675 nm (E 11 M ) and 1745 nm (E 11 S ). (paper)

  7. Nanotubes and nanowires

    Indian Academy of Sciences (India)


    nanotubes are likely to be useful as nanochips since they exhibit diode properties at the junction. By making use of carbon nanotubes, nanowires of metals, metal oxides and GaN have been obtained. Both the oxide and GaN nanowires are single crystalline. Gold nanowires exhibit plasmon bands varying markedly with.

  8. Extrarenal potassium adaptation: role of skeletal muscle

    International Nuclear Information System (INIS)

    Blachley, J.D.; Crider, B.P.; Johnson, J.H.


    Following the ingestion of a high-potassium-content diet for only a few days, the plasma potassium of rats rises only modestly in response to a previously lethal dose of potassium salts. This acquired tolerance, termed potassium adaptation, is principally the result of increased capacity to excrete potassium into the urine. However, a substantial portion of the acute potassium dose is not immediately excreted and is apparently translocated into cells. Previous studies have failed to show an increase in the content of potassium of a variety of tissues from such animals. Using 86 Rb as a potassium analogue, we have shown that the skeletal muscle of potassium-adapted rats takes up significantly greater amounts of potassium in vivo in response to an acute challenge than does that of control animals. Furthermore, the same animals exhibit greater efflux of 86 Rb following the termination of the acute infusion. We have also shown that the Na+-K+-ATPase activity and ouabain-binding capacity of skeletal muscle microsomes are increased by the process of potassium adaptation. We conclude that skeletal muscle is an important participant in potassium adaptation and acts to temporarily buffer acute increases in the extracellular concentration of potassium

  9. Sustained Release of Antibacterial Agents from Doped Halloysite Nanotubes

    Directory of Open Access Journals (Sweden)

    Shraddha Patel


    Full Text Available The use of nanomaterials for improving drug delivery methods has been shown to be advantageous technically and viable economically. This study employed the use of halloysite nanotubes (HNTs as nanocontainers, as well as enhancers of structural integrity in electrospun poly-e-caprolactone (PCL scaffolds. HNTs were loaded with amoxicillin, Brilliant Green, chlorhexidine, doxycycline, gentamicin sulfate, iodine, and potassium calvulanate and release profiles assessed. Selected doped halloysite nanotubes (containing either Brilliant Green, amoxicillin and potassium calvulanate were then mixed with poly-e-caprolactone (PLC using the electrospinning method and woven into random and oriented-fibered nanocomposite mats. The rate of drug release from HNTs, HNTs/PCL nanocomposites, and their effect on inhibiting bacterial growth was investigated. Release profiles from nanocomposite mats showed a pattern of sustained release for all bacterial agents. Nanocomposites were able to inhibit bacterial growth for up to one-month with only a slight decrease in bacterial growth inhibition. We propose that halloysite doped nanotubes have the potential for use in a variety of medical applications including sutures and surgical dressings, without compromising material properties.

  10. 21 CFR 184.1610 - Potassium alginate. (United States)


    .... 9005-36-1) is the potassium salt of alginic acid, a natural polyuronide constituent of certain brown algae. Potassium alginate is prepared by the neutralization of purified alginic acid with appropriate pH...

  11. 21 CFR 172.800 - Acesulfame potassium. (United States)


    ... HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION... not preclude such use, under the following conditions: (a) Acesulfame potassium is the potassium salt...

  12. Radiation dosimetry by potassium feldspar

    Indian Academy of Sciences (India)


    Radiation dosimetry by potassium feldspar. ARUN PANDYA*, S G VAIJAPURKAR and P K BHATNAGAR. Defence Laboratory, Jodhpur 342 011, India. MS received 12 July 1999; revised 15 February 2000. Abstract. The thermoluminescence (TL) properties of raw and annealed feldspar have been studied for their.

  13. Increased serum potassium affects renal outcomes

    DEFF Research Database (Denmark)

    Miao, Y; Dobre, D; Heerspink, H J Lambers


    To assess the effect of an angiotensin receptor blocker (ARB) on serum potassium and the effect of a serum potassium change on renal outcomes in patients with type 2 diabetes and nephropathy.......To assess the effect of an angiotensin receptor blocker (ARB) on serum potassium and the effect of a serum potassium change on renal outcomes in patients with type 2 diabetes and nephropathy....

  14. Suppression chamber

    International Nuclear Information System (INIS)

    Goto, Hiroshi; Tsuji, Akio.


    Purpose: To miniaturize the storage tank of condensated water in BWR reactor. Constitution: A diaphragm is provided in a suppression chamber thereby to partition the same into an inner compartment and an outer compartment. In one of said compartments there is stored clean water to be used for feeding at the time of separating the reactor and for the core spray system, and in another compartment there is stored water necessary for accomplishing the depressurization effect at the time of coolant loss accident. To the compartment in which clean water is stored there is connected a water cleaning device for constantly maintaining water in clean state. As this cleaning device an already used fuel pool cleaning device can be utilized. Further, downcomers for accomplishing the depressurization function are provided in both inner compartment and outer compartment. The capacity of the storage tank can be reduced by the capacity of clean water within the suppression chamber. (Ikeda, J.)

  15. Nanotube resonator devices (United States)

    Jensen, Kenneth J; Zettl, Alexander K; Weldon, Jeffrey A


    A fully-functional radio receiver fabricated from a single nanotube is being disclosed. Simultaneously, a single nanotube can perform the functions of all major components of a radio: antenna, tunable band-pass filter, amplifier, and demodulator. A DC voltage source, as supplied by a battery, can power the radio. Using carrier waves in the commercially relevant 40-400 MHz range and both frequency and amplitude modulation techniques, successful music and voice reception has been demonstrated. Also disclosed are a radio transmitter and a mass sensor using a nanotube resonator device.

  16. Tunable multiwalled nanotube resonator (United States)

    Jensen, Kenneth J; Girit, Caglar O; Mickelson, William E; Zettl, Alexander K; Grossman, Jeffrey C


    A tunable nanoscale resonator has potential applications in precise mass, force, position, and frequency measurement. One embodiment of this device consists of a specially prepared multiwalled carbon nanotube (MWNT) suspended between a metal electrode and a mobile, piezoelectrically controlled contact. By harnessing a unique telescoping ability of MWNTs, one may controllably slide an inner nanotube core from its outer nanotube casing, effectively changing its length and thereby changing the tuning of its resonance frequency. Resonant energy transfer may be used with a nanoresonator to detect molecules at a specific target oscillation frequency, without the use of a chemical label, to provide label-free chemical species detection.

  17. Obtaining of potassium dicyan-argentate

    International Nuclear Information System (INIS)

    Sattarova, M.A.; Solojenkin, P.M.


    This work is devoted to obtaining of potassium dicyan-argentate. By means of exchange reaction between silver nitrate and potassium cyanide the potassium dicyan-argentate was synthesized. The analysis of obtained samples was carried out by means of titration and potentiometry.

  18. 21 CFR 582.1631 - Potassium hydroxide. (United States)


    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Potassium hydroxide. 582.1631 Section 582.1631 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1631 Potassium hydroxide. (a) Product. Potassium hydroxide. (b) Conditions of use. This...

  19. 21 CFR 172.160 - Potassium nitrate. (United States)


    ... Preservatives § 172.160 Potassium nitrate. The food additive potassium nitrate may be safely used as a curing... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium nitrate. 172.160 Section 172.160 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN...

  20. Potassium nutrition of heat-stressed lactating

    African Journals Online (AJOL)

    total dietary potassium, dietary potassium bicarbonate. (KHC03) and sodium bicarbonate (NaHC03) on pro- duction responses. It was postulated that mineral buffers might increase efficiency of fermentation by increasing ruminal pH. Also, KHC03 might serve as a source of bicarbonate and supplemental potassium.

  1. Thanatochemistry: Study of vitreous humor potassium | Tumram ...

    African Journals Online (AJOL)

    This study has been carried out to determine the death interval from the biochemical parameter of vitreous potassium. In 308 medicolegal cases vitreous humor was taken and analyzed for potassium with known time of death. There was a linear rise in potassium concentration with increasing death interval. Regression ...

  2. 75 FR 23298 - Potassium Permanganate From China (United States)


    ... COMMISSION Potassium Permanganate From China AGENCY: United States International Trade Commission. ACTION: Institution of a five-year review concerning the antidumping duty order on potassium permanganate from China... antidumping duty order on potassium permanganate from China would be likely to lead to continuation or...

  3. Disorder, Pseudospins, and Backscattering in Carbon Nanotubes

    International Nuclear Information System (INIS)

    McEuen, Paul L.; Bockrath, Marc; Cobden, David H.; Yoon, Young-Gui; Louie, Steven G.


    We address the effects of disorder on the conducting properties of metal and semiconducting carbon nanotubes. Experimentally, the mean free path is found to be much larger in metallic tubes than in doped semiconducting tubes. We show that this result can be understood theoretically if the disorder potential is long ranged. The effects of a pseudospin index that describes the internal sublattice structure of the states lead to a suppression of scattering in metallic tubes, but not in semiconducting tubes. This conclusion is supported by tight-binding calculations. (c) 1999 The American Physical Society

  4. Boron Nitride Nanotubes (United States)

    Smith, Michael W. (Inventor); Jordan, Kevin (Inventor); Park, Cheol (Inventor)


    Boron nitride nanotubes are prepared by a process which includes: (a) creating a source of boron vapor; (b) mixing the boron vapor with nitrogen gas so that a mixture of boron vapor and nitrogen gas is present at a nucleation site, which is a surface, the nitrogen gas being provided at a pressure elevated above atmospheric, e.g., from greater than about 2 atmospheres up to about 250 atmospheres; and (c) harvesting boron nitride nanotubes, which are formed at the nucleation site.

  5. Paraconductivity in Carbon Nanotubes


    Livanov, D. V.; Varlamov, A. A.


    We report the calculation of paraconductivity in carbon nanotubes above the superconducting transition temperature. The complex behavior of paraconductivity depending upon the tube radius, temperature and magnetic field strength is analyzed. The results are qualitatively compared with recent experimental observations in carbon nanotubes of an inherent transition to the superconducting state and pronounced thermodynamic fluctuations above $T_{c}$. The application of our results to single-wall ...

  6. Influence of Thermal Modification and Morphology of TiO₂ Nanotubes on Their Electrochemical Properties for Biosensors Applications. (United States)

    Arkusz, Katarzyna; Paradowska, Ewa; Nycz, Marta; Krasicka-Cydzik, Elżzbieta


    The morphology of self-assembled TiO2 nanotubes layer plays a key role in electrical conductivity and biocompatibility properties in terms of cell proliferation, adhesion and mineralization. Many research studies have been reported in using a TiO2 nanotubes for different medical applications, there is a lack of unified correlation between TNT morphology and its electrochemical properties. The aim of this study was to examine the effects of diameter and annealing conditions on TiO2 nanotubes with identical height and their behaviour as biosensor platform. TiO2 nanotubes layer, 1000 nm thick with nanotubes of diameters in range: 25 ÷ 100 nm, was prepared by anodizing of the titanium foil in ethylene glycol solution. To change the crystal structure and improve the electrical conductivity of the semiconductive TiO2 nanotubes layer the thermal treatment by annealing in argon, nitrogen or air was used. Basing on the electrochemical tests, the XPS and scanning microscopy examinations, as well as the contact angle measurements and the amperometric detection of potassium ferricyanide, it was concluded that the 1000 nm thick TiO2 nanotubes layer with nanotubes of 50 nm diameter, annealed in argon, showed the best physicochemical properties, which helps investigate the adsorption immobilization mechanism. The possibility of using TNT as a biosensor platform was confirmed in hydrogen detection.

  7. Carbon Nanotube Underwater Acoustic Thermophone (United States)


    Attorney Docket No. 300009 1 of 8 A CARBON NANOTUBE UNDERWATER ACOUSTIC THERMOPHONE STATEMENT OF GOVERNMENT INTEREST [0001] The...the Invention [0003] The present invention is an acoustically transparent carbon nanotube thermophone. (2) Description of the Prior Art [0004...amplitude of the resulting sound waves. [0006] Recently, there has been development of underwater acoustic carbon nanotube (CNT) yarn sheets capable

  8. Carbon nanotube junctions and devices

    NARCIS (Netherlands)

    Postma, H.W.Ch.


    In this thesis Postma presents transport experiments performed on individual single-wall carbon nanotubes. Carbon nanotubes are molecules entirely made of carbon atoms. The electronic properties are determined by the exact symmetry of the nanotube lattice, resulting in either metallic or

  9. Formation of TiO2 nanotubes via anodization and potential applications for photocatalysts, biomedical materials, and photoelectrochemical cell

    International Nuclear Information System (INIS)

    Sreekantan, Srimala; Saharudin, Khairul Arifah; Wei, Lai Chin


    One-dimensional nanotube systems with high surface-to-volume ratios possess unique properties and are thus utilized in various applications. In this study, self-organized TiO 2 nanotubes were prepared by anodization of a Ti foil in glycerol containing 5 wt% ammonium fluoride (NH 4 F) and 6 wt% ethylene glycol (EG). The surface morphology, average inner diameter, and average length of the nanotubes varied with the electrochemical anodization parameters. Nanotubes with uniform surface morphologies, an average diameter of 85 nm, and an average length of 1.1 μm were obtained at 30 V for 1 h The as-prepared nanotubes were amorphous but they crystallized in the anatase phase after heating at about 400 deg. C for 2 h in an argon atmosphere. The photocatalytic activity of the TiO 2 nanotubes was evaluated through the degradation of methyl orange (MO) and by investigating their bactericidal effect. Optimum photocatalysis of MO was achieved at a kinetic rate constant of 10 -3 min -1 . Furthermore, cell viability rapidly decreased on UV illumination and complete killing was achieved at 60 min in the presence of TiO 2 nanotubes. For biomedical applications, the cellular activity on TiO 2 nanotubes was determined using PA6 cells. Higher cellular activities were achieved using the anatase phase of 85-nm-diameter nanotubes than the amorphous phase. Photoelectrochemical hydrogen generation was investigated using nanotube photoanodes in 1 M potassium hydroxide (KOH) containing 1 wt% EG and xenon lamp. The maximum photocurrent density was 0.55 mA/cm 2 . These findings demonstrate that TiO 2 nanotubes are promising for use in multifunctional applications.

  10. Potassium Intake, Bioavailability, Hypertension, and Glucose Control

    Directory of Open Access Journals (Sweden)

    Michael S. Stone


    Full Text Available Potassium is an essential nutrient. It is the most abundant cation in intracellular fluid where it plays a key role in maintaining cell function. The gradient of potassium across the cell membrane determines cellular membrane potential, which is maintained in large part by the ubiquitous ion channel the sodium-potassium (Na+-K+ ATPase pump. Approximately 90% of potassium consumed (60–100 mEq is lost in the urine, with the other 10% excreted in the stool, and a very small amount lost in sweat. Little is known about the bioavailability of potassium, especially from dietary sources. Less is understood on how bioavailability may affect health outcomes. Hypertension (HTN is the leading cause of cardiovascular disease (CVD and a major financial burden ($50.6 billion to the US public health system, and has a significant impact on all-cause morbidity and mortality worldwide. The relationship between increased potassium supplementation and a decrease in HTN is relatively well understood, but the effect of increased potassium intake from dietary sources on blood pressure overall is less clear. In addition, treatment options for hypertensive individuals (e.g., thiazide diuretics may further compound chronic disease risk via impairments in potassium utilization and glucose control. Understanding potassium bioavailability from various sources may help to reveal how specific compounds and tissues influence potassium movement, and further the understanding of its role in health.

  11. Evaluation of the potassium adsorption capacity of a potassium adsorption filter during rapid blood transfusion. (United States)

    Matsuura, H; Akatsuka, Y; Muramatsu, C; Isogai, S; Sugiura, Y; Arakawa, S; Murayama, M; Kurahashi, M; Takasuga, H; Oshige, T; Yuba, T; Mizuta, S; Emi, N


    The concentration of extracellular potassium in red blood cell concentrates (RCCs) increases during storage, leading to risk of hyperkalemia. A potassium adsorption filter (PAF) can eliminate the potassium at normal blood transfusion. This study aimed to investigate the potassium adsorption capacity of a PAF during rapid blood transfusion. We tested several different potassium concentrations under a rapid transfusion condition using a pressure bag. The adsorption rates of the 70-mEq/l model were 76·8%. The PAF showed good potassium adsorption capacity, suggesting that this filter may provide a convenient method to prevent hyperkalemia during rapid blood transfusion. © 2015 International Society of Blood Transfusion.

  12. Adhered Supported Carbon Nanotubes

    International Nuclear Information System (INIS)

    Johnson, Dale F.; Craft, Benjamin J.; Jaffe, Stephen M.


    Carbon nanotubes (NTs) in excess of 200 μm long are grown by catalytic pyrolysis of hydrocarbon vapors. The nanotubes grow continuously without the typical extinction due to catalyst encapsulation. A woven metal mesh supports the nanotubes creating a metal supported nanotube (MSNT) structure. The 140 μm wide mesh openings are completely filled by 70 nm diameter multiwalled nanotubes (MWNTs). The MWNTs are straight, uniform and highly crystalline. Their wall thickness is about 10 nm (30 graphite layers). The adherent NTs are not removed from the support in a Scotch tape pull test. A 12.5 cm 2 capacitor made from two MSNT structures immersed in 1 M KCl has a capacitance of 0.35 F and an equivalent series resistance of 0.18 Ω. Water flows through the MSNT at a flow velocity of 1 cm/min with a pressure drop of 15 inches of water. With the support removed, the MWNTs naturally form a carbon nanocomposite (CNC) paper with a specific area of 80 m 2 /gm, a bulk density of 0.21 g/cm 3 , an open pore fraction of 0.81, and a resistivity of 0.16 Ω-cm

  13. Carbon nanotubes as liquid crystals. (United States)

    Zhang, Shanju; Kumar, Satish


    Carbon nanotubes are the best of known materials with a combination of excellent mechanical, electronic, and thermal properties. To fully exploit individual nanotube properties for various applications, the grand challenge is to fabricate macroscopic ordered nanotube assemblies. Liquid-crystalline behavior of the nanotubes provides a unique opportunity toward reaching this challenge. In this Review, the recent developments in this area are critically reviewed by discussing the strategies for fabricating liquid-crystalline phases, addressing the solution properties of liquid-crystalline suspensions, and exploiting the practical techniques of liquid-crystal routes to prepare macroscopic nanotube fibers and films.

  14. Potassium (United States)

    ... confusion listlessness tingling, prickling, burning, tight, or pulling sensation of arms, hands, legs, or feet heaviness or weakness of legs cold, pale, gray skin stomach pain unusual stomach bulging ...

  15. Potassium. (United States)

    Halperin, M L; Kamel, K S


    In a logical, stepwise approach to patients presenting with hypokalaemia or hyperkalaemia the clinician must first recognise circumstances in which the dyskalaemia represents a clinical emergency because therapy then takes precedence over diagnosis. If a dyskalaemia has been present for a long time, there is an abnormal renal handling of K+. The next step to analyse is the rate of excretion of K+ and, if necessary, its two components (urine flow rate and K+ concentration in the cortical collecting duct [CCD]) analysed independently. If the K+ concentration in the CCD is not in the expected range, its basis should be defined at the ion-channel level in the CCD from clinical information that can be used to deduce the relative rates of reabsorption of Na+ and Cl- in the CCD. This analysis provides the basis for diagnosis and may indicate where non-emergency therapy should then be directed.

  16. Carbon Nanotubes for Supercapacitor

    Directory of Open Access Journals (Sweden)

    Li Jianyi


    Full Text Available Abstract As an electrical energy storage device, supercapacitor finds attractive applications in consumer electronic products and alternative power source due to its higher energy density, fast discharge/charge time, low level of heating, safety, long-term operation stability, and no disposable parts. This work reviews the recent development of supercapacitor based on carbon nanotubes (CNTs and their composites. The purpose is to give a comprehensive understanding of the advantages and disadvantages of carbon nanotubes-related supercapacitor materials and to find ways for the improvement in the performance of supercapacitor. We first discussed the effects of physical and chemical properties of pure carbon nanotubes, including size, purity, defect, shape, functionalization, and annealing, on the supercapacitance. The composites, including CNTs/oxide and CNTs/polymer, were further discussed to enhance the supercapacitance and keep the stability of the supercapacitor by optimally engineering the composition, particle size, and coverage.

  17. Inward-rectifying potassium channelopathies: new insights into disorders of sodium and potassium homeostasis. (United States)

    Cheng, Chih-Jen; Sung, Chih-Chien; Huang, Chou-Long; Lin, Shih-Hua


    Inward-rectifying potassium (Kir) channels allow more inward than outward potassium flux when channels are open in mammalian cells. At physiological resting membrane potentials, however, they predominantly mediate outward potassium flux and play important roles in regulating the resting membrane potential in diverse cell types and potassium secretion in the kidneys. Mutations of Kir channels cause human hereditary diseases collectively called Kir channelopathies, many of which are characterized by disorders of sodium and potassium homeostasis. Studies on these genetic Kir channelopathies have shed light on novel pathophysiological mechanisms, including renal sodium and potassium handling, potassium shifting in skeletal muscles, and aldosterone production in the adrenal glands. Here, we review several recent advances in Kir channels and their clinical implications in sodium and potassium homeostasis.

  18. Nanotechnology with Carbon Nanotubes: Mechanics, Chemistry, and Electronics (United States)

    Srivastava, Deepak


    This viewgraph presentation reviews the Nanotechnology of carbon nanotubes. The contents include: 1) Nanomechanics examples; 2) Experimental validation of nanotubes in composites; 3) Anisotropic plastic collapse; 4) Spatio-temporal scales, yielding single-wall nanotubes; 5) Side-wall functionalization of nanotubes; 6) multi-wall Y junction carbon nanotubes; 7) Molecular electronics with Nanotube junctions; 8) Single-wall carbon nanotube junctions; welding; 9) biomimetic dendritic neurons: Carbon nanotube, nanotube electronics (basics), and nanotube junctions for Devices,

  19. Carbon Nanotube Solar Cells


    Klinger, Colin; Patel, Yogeshwari; Postma, Henk W. Ch.


    We present proof-of-concept all-carbon solar cells. They are made of a photoactive side of predominantly semiconducting nanotubes for photoconversion and a counter electrode made of a natural mixture of carbon nanotubes or graphite, connected by a liquid electrolyte through a redox reaction. The cells do not require rare source materials such as In or Pt, nor high-grade semiconductor processing equipment, do not rely on dye for photoconversion and therefore do not bleach, and are easy to fabr...

  20. Nanostructured polypyrrole: enhancement in thermoelectric figure of merit through suppression of thermal conductivity (United States)

    Misra, Shantanu; Bharti, Meetu; Singh, Ajay; Debnath, A. K.; Aswal, D. K.; Hayakawa, Y.


    Semi-crystalline polypyrrole (PPy) nanotubes were synthesized through a chemical polymerization route using methyl orange-ferric chloride (MO-FeCl3) as a template for growth. The thermoelectric properties of these PPy nanotubes have been studied in the temperature range 300-380 K after treatment with various dopants such as hydrochloric acid (HCl), p-toluene-sulphonic acid monohydrate (ToS), and tetrabutyl ammonium hexaflurophosphate (PF6). It has been observed that these dopants affect the electrical and thermal transport properties of PPy nanotubes in different ways. The temperature dependence of electrical resistivity suggests that pure PPy and ToS-doped PPy nanotubes exhibit a critical regime of metal-to-insulator transition, and doping with HCl drives them into the metallic regime. In contrast, PF6 doping of PPy nanotubes carries them into the insulating regime and these samples exhibited the highest figure of merit of ~3.4  ×  10‒3 at 380 K, which was 240% higher than the value obtained in the case of pristine PPy nanotubes. Strongly repressed thermal conductivity along with moderately high Seebeck coefficient and electrical conductivity have been found to be responsible for the high figure of merit observed in PF6-doped PPy nanotubes. The suppression of thermal conductivity in PF6-doped PPy nanotubes is attributed to the scattering of the spectrum of phonons via hierarchical length-scale defect structures present in the sample.

  1. Continuous carbon nanotube reinforced composites. (United States)

    Ci, L; Suhr, J; Pushparaj, V; Zhang, X; Ajayan, P M


    Carbon nanotubes are considered short fibers, and polymer composites with nanotube fillers are always analogues of random, short fiber composites. The real structural carbon fiber composites, on the other hand, always contain carbon fiber reinforcements where fibers run continuously through the composite matrix. With the recent optimization in aligned nanotube growth, samples of nanotubes in macroscopic lengths have become available, and this allows the creation of composites that are similar to the continuous fiber composites with individual nanotubes running continuously through the composite body. This allows the proper utilization of the extreme high modulus and strength predicted for nanotubes in structural composites. Here, we fabricate such continuous nanotube polymer composites with continuous nanotube reinforcements and report that under compressive loadings, the nanotube composites can generate more than an order of magnitude improvement in the longitudinal modulus (up to 3,300%) as well as damping capability (up to 2,100%). It is also observed that composites with a random distribution of nanotubes of same length and similar filler fraction provide three times less effective reinforcement in composites.

  2. Spectroelectrochemistry of Carbon Nanotubes

    Czech Academy of Sciences Publication Activity Database

    Kavan, Ladislav; Dunsch, L.


    Roč. 12, č. 1 (2011), s. 47-55 ISSN 1439-4235 R&D Projects: GA MŠk LC510; GA AV ČR IAA400400804; GA AV ČR KAN200100801 Institutional research plan: CEZ:AV0Z40400503 Keywords : electrochemistry * nanotubes * photoluminiscence Subject RIV: CG - Electrochemistry Impact factor: 3.412, year: 2011

  3. Erythrocyte potassium and glutathione polymorphism determination ...

    African Journals Online (AJOL)


    This research is aimed at determining the erythrocyte potassium and glutathione polymorphisms and also to identify the relationship among the various blood parameters in Saanen x Malta crossbred goat raised in Turkey. The allele gene frequencies of KH and KL associated with the potassium concentration.

  4. Erythrocyte potassium and glutathione polymorphism determination ...

    African Journals Online (AJOL)

    This research is aimed at determining the erythrocyte potassium and glutathione polymorphisms and also to identify the relationship among the various blood parameters in Saanen x Malta crossbred goat raised in Turkey. The allele gene frequencies of KH and KL associated with the potassium concentration were ...

  5. Thanatochemistry: Study of synovial fluid potassium | Tumram ...

    African Journals Online (AJOL)

    The purpose of this paper is to test previously developed regression formulae for estimating death interval based on synovial fluid potassium and to assess its reliability in estimating death interval. Synovial fluid potassium was measured on a sample of 308 individuals. Death interval was regressed on synovial fluid ...

  6. Genetics Home Reference: potassium-aggravated myotonia (United States)

    ... eating potassium-rich foods such as bananas and potatoes. Stiffness occurs in skeletal muscles throughout the body. Potassium-aggravated myotonia ranges in severity from mild episodes of muscle stiffness to severe, disabling disease with frequent attacks. Unlike some other forms of ...

  7. Potassium doped MWCNTs for hydrogen storage enhancement

    International Nuclear Information System (INIS)

    Adabi Qomi, S.; Gashtasebi, M.; Khoshnevisan, B.


    Here we have used potassium doped MWCNTs for enhancement of hydrogen storage process. XRD and SEM images have confirmed the doping of potassium. For studying the storage process a hydrogenic battery set up has been used. In the battery the working electrode has been made of the silver foam deposited by the doped MWCNTs electrophoretically.

  8. 21 CFR 582.1613 - Potassium bicarbonate. (United States)


    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Potassium bicarbonate. 582.1613 Section 582.1613 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE General Purpose Food Additives § 582.1613 Potassium bicarbonate. (a)...

  9. Effect of potassium on micromorphological and chemical ...

    African Journals Online (AJOL)

    It was observed that epidermal and mesophyl cells were more turgid, uniform, flaccid, symmetrical and structurally improved with potassium application. Larger number of starch grains was observed in plant leaves grown without potassium application while in leaves supplied with K their number decreased. Thickness of the ...

  10. Erythrocyte potassium and glutathione polymorphism determination ...

    African Journals Online (AJOL)



    Jun 13, 2011 ... erythrocyte and hematocrit values (Igbokwe et al., 1998). This study aims to detect the genetic makeup of. Saanen x Malta crossbred goat depending on the gluta- thione and potassium types in erythrocyte and also to find if the association between erythrocyte potassium and some of the blood parameters ...

  11. 75 FR 51112 - Potassium Permanganate From China (United States)


    ... COMMISSION Potassium Permanganate From China AGENCY: United States International Trade Commission. ACTION... from China. SUMMARY: The Commission hereby gives notice of the scheduling of an expedited review... whether revocation of the antidumping duty order on potassium permanganate from China would be likely to...

  12. Extracellular potassium inhibits Kv7.1 potassium channels by stabilizing an inactivated state

    DEFF Research Database (Denmark)

    Larsen, Anders Peter; Steffensen, Annette Buur; Grunnet, Morten


    Kv7.1 (KCNQ1) channels are regulators of several physiological processes including vasodilatation, repolarization of cardiomyocytes, and control of secretory processes. A number of Kv7.1 pore mutants are sensitive to extracellular potassium. We hypothesized that extracellular potassium also...... modulates wild-type Kv7.1 channels. The Kv7.1 currents were measured in Xenopus laevis oocytes at different concentrations of extracellular potassium (1-50 mM). As extracellular potassium was elevated, Kv7.1 currents were reduced significantly more than expected from theoretical calculations based...... on the Goldman-Hodgkin-Katz flux equation. Potassium inhibited the steady-state current with an IC(50) of 6.0 ± 0.2 mM. Analysis of tail-currents showed that potassium increased the fraction of channels in the inactivated state. Similarly, the recovery from inactivation was slowed by potassium, suggesting...

  13. Soldering of Nanotubes onto Microelectrodes

    DEFF Research Database (Denmark)

    Madsen, Dorte Nørgaard; Mølhave, Kristian; Mateiu, Ramona Valentina


    Suspended bridges of individual multiwalled carbon nanotubes were fabricated inside a scanning electron microscope by soldering the nanotube onto microelectrodes with highly conducting gold-carbon material. By the decomposition of organometallic vapor with the electron beam, metal-containing solder...... bonds were formed at the intersection of the nanotube and the electrodes. Current-voltage curves indicated metallic conduction of the nanotubes, with resistances in the range of 9-29 kOmega. Bridges made entirely of the soldering material exhibited resistances on the order of 100 Omega, and the solder...

  14. Continuum theory for nanotube piezoelectricity. (United States)

    Michalski, P J; Sai, Na; Mele, E J


    We develop and solve a continuum theory for the piezoelectric response of one-dimensional nanotubes and nanowires, and apply the theory to study electromechanical effects in boron-nitride nanotubes. We find that the polarization of a nanotube depends on its aspect ratio, and a dimensionless constant specifying the ratio of the strengths of the elastic and electrostatic interactions. The solutions of the model as these two parameters are varied are discussed. The theory is applied to estimate the electric potential induced along the length of a boron-nitride nanotube in response to a uniaxial stress.

  15. Carbon Nanotubes for Space Applications (United States)

    Meyyappan, Meyya


    The potential of nanotube technology for NASA missions is significant and is properly recognized by NASA management. Ames has done much pioneering research in the last five years on carbon nanotube growth, characterization, atomic force microscopy, sensor development and computational nanotechnology. NASA Johnson Space Center has focused on laser ablation production of nanotubes and composites development. These in-house efforts, along with strategic collaboration with academia and industry, are geared towards meeting the agency's mission requirements. This viewgraph presentation (including an explanation for each slide) outlines the research focus for Ames nanotechnology, including details on carbon nanotubes' properties, applications, and synthesis.

  16. Subchronic immunotoxicity and screening of reproductive toxicity and developmental immunotoxicity following single instillation of HIPCO-single-walled carbon nanotubes: purity-based comparison. (United States)

    Park, Eun-Jung; Choi, Je; Kim, Jae-Ho; Lee, Byoung-Seok; Yoon, Cheolho; Jeong, Uiseok; Kim, Younghun


    Impurity has been suggested as an important factor determining toxicity following exposure to single-walled carbon nanotubes (SWCNTs). In this study, we first compared immunotoxicity based on iron content on day 90 after a single intratracheal instillation of SWCNTs in male and female mice. The inflammatory responses were generally stronger in mice exposed to acid-purified (P)-SWCNTs compared to raw (R)-SWCNTs. In addition, both R- and P-SWCNTs induced Th1-polarized immune responses with apoptotic death of BAL cells and systemically impaired the function of antigen-presenting cells (APC). We also screened reproductive and developmental toxicity by cohabitating male and female mice on day 14 after instillation. Interestingly, the pregnancy rate rapidly decreased following exposure to both types of SWCNTs, especially R-SWCNTs. In addition, we investigated developmental immunotoxicity of the offspring on day 28 after exposure to both types of SWCNTs. Their hematological changes were clearer relative to those of the parents and a significant decrease in the alkaline phosphatase and potassium levels was observed in mice of both sexes exposed to the higher dose of R- and P-SWCNTs. In conclusion, we suggest that SWCNTs may induce Th1-polarized immune responses accompanied by suppression of APC function on day 90 after a single instillation without significant iron content dependance. In addition, the consecutive exposure of SWCNTs to the subsequent generation may exacerbate metabolic and hematological disturbance. Furthermore, our results underscore the need to clarify the reproductive and developmental health effects of SWCNTs.

  17. Conductance of Sidewall-Functionalized Carbon Nanotubes: Universal Dependence on Adsorption Sites

    DEFF Research Database (Denmark)

    García-Lastra, J.M.; Thygesen, Kristian Sommer; Strange, Mikkel


    We use density functional theory to study the effect of molecular adsorbates on the conductance of metallic carbon nanotubes (CNT). The five molecules considered (NO2, NH2, H, COOH, OH) lead to very similar scattering of the electrons. The adsorption of a single molecule suppresses one of the two...

  18. VKCDB: Voltage-gated potassium channel database

    Directory of Open Access Journals (Sweden)

    Gallin Warren J


    Full Text Available Abstract Background The family of voltage-gated potassium channels comprises a functionally diverse group of membrane proteins. They help maintain and regulate the potassium ion-based component of the membrane potential and are thus central to many critical physiological processes. VKCDB (Voltage-gated potassium [K] Channel DataBase is a database of structural and functional data on these channels. It is designed as a resource for research on the molecular basis of voltage-gated potassium channel function. Description Voltage-gated potassium channel sequences were identified by using BLASTP to search GENBANK and SWISSPROT. Annotations for all voltage-gated potassium channels were selectively parsed and integrated into VKCDB. Electrophysiological and pharmacological data for the channels were collected from published journal articles. Transmembrane domain predictions by TMHMM and PHD are included for each VKCDB entry. Multiple sequence alignments of conserved domains of channels of the four Kv families and the KCNQ family are also included. Currently VKCDB contains 346 channel entries. It can be browsed and searched using a set of functionally relevant categories. Protein sequences can also be searched using a local BLAST engine. Conclusions VKCDB is a resource for comparative studies of voltage-gated potassium channels. The methods used to construct VKCDB are general; they can be used to create specialized databases for other protein families. VKCDB is accessible at

  19. Carbon Nanotube Materials for Substrate Enhanced Control of Catalytic Activity

    Energy Technology Data Exchange (ETDEWEB)

    Heben, M.; Dillon, A. C.; Engtrakul, C.; Lee, S.-H.; Kelley, R. D.; Kini, A. M.


    Carbon SWNTs are attractive materials for supporting electrocatalysts. The properties of SWNTs are highly tunable and controlled by the nanotube's circumferential periodicity and their surface chemistry. These unique characteristics suggest that architectures constructed from these types of carbon support materials would exhibit interesting and useful properties. Here, we expect that the structure of the carbon nanotube support will play a major role in stabilizing metal electrocatalysts under extreme operating conditions and suppress both catalyst and support degradation. Furthermore, the chemical modification of the carbon nanotube surfaces can be expected to alter the interface between the catalyst and support, thus, enhancing the activity and utilization of the electrocatalysts. We plan to incorporate discrete reaction sites into the carbon nanotube lattice to create intimate electrical contacts with the catalyst particles to increase the metal catalyst activity and utilization. The work involves materials synthesis, design of electrode architectures on the nanoscale, control of the electronic, ionic, and mass fluxes, and use of advanced optical spectroscopy techniques.

  20. Serum potassium concentrations: Importance of normokalaemia. (United States)

    Heras, Manuel; Fernández-Reyes, María José


    Abnormalities in potassium concentrations are associated with morbidity and mortality. In recent years it has been considered that small variations in serum potassium concentrations within normal intervals may also be associated with mortality. Strategies for achieving normokalaemia include dietary measures, limiting the use of potassium retaining drugs, and use of conventional cation exchange resins (calcium/sodium polystyrene sulfonate) and/or the new non-absorbed cation exchange polymer (patiromer). Copyright © 2017 Elsevier España, S.L.U. All rights reserved.

  1. X-ray absorption in atomic potassium

    International Nuclear Information System (INIS)

    Gomilsek, Jana Padeznik; Kodre, Alojz; Arcon, Iztok; Nemanic, Vincenc


    A new high-temperature absorption cell for potassium vapor is described. X-ray absorption coefficient of atomic potassium is determined in the energy interval of 600 eV above the K edge where thresholds for simultaneous excitations of 1s and outer electrons, down to [1s2p] excitation, appear. The result represents also the atomic absorption background for XAFS (X-ray absorption fine structure) structure analysis. The K ionization energy in the potassium vapor is determined and compared with theoretical data and with the value for the metal

  2. Effect of Potassium Channel Modulators on Morphine Withdrawal in Mice

    Directory of Open Access Journals (Sweden)

    Vikas Seth


    Full Text Available The present study was conducted to investigate the effect of potassium channel openers and blockers on morphine withdrawal syndrome. Mice were rendered dependent on morphine by subcutaneous injection of morphine; four hours later, withdrawal was induced by using an opioid antagonist, naloxone. Mice were observed for 30 minutes for the withdrawal signs ie, the characteristic jumping, hyperactivity, urination and diarrhea. ATP-dependent potassium (K + ATP channel modulators were injected intraperitoneally (i.p. 30 minutes before the naloxone. It was found that a K + ATP channel opener, minoxidil (12.5–50 mg/kg i.p., suppressed the morphine withdrawal significantly. On the other hand, the K + ATP channel blocker glibenclamide (12.5–50 mg/kg i.p. caused a significant facilitation of the withdrawal. Glibenclamide was also found to abolish the minoxidil's inhibitory effect on morphine withdrawal. The study concludes that K + ATP channels play an important role in the genesis of morphine withdrawal and K + ATP channel openers could be useful in the management of opioid withdrawal. As morphine opens K + ATP channels in neurons, the channel openers possibly act by mimicking the effects of morphine on neuronal K + currents.

  3. Tunneling nanotubes provide a unique conduit for intercellular transfer of cellular contents in human malignant pleural mesothelioma.

    Directory of Open Access Journals (Sweden)

    Emil Lou

    Full Text Available Tunneling nanotubes are long, non-adherent F-actin-based cytoplasmic extensions which connect proximal or distant cells and facilitate intercellular transfer. The identification of nanotubes has been limited to cell lines, and their role in cancer remains unclear. We detected tunneling nanotubes in mesothelioma cell lines and primary human mesothelioma cells. Using a low serum, hyperglycemic, acidic growth medium, we stimulated nanotube formation and bidirectional transfer of vesicles, proteins, and mitochondria between cells. Notably, nanotubes developed between malignant cells or between normal mesothelial cells, but not between malignant and normal cells. Immunofluorescent staining revealed their actin-based assembly and structure. Metformin and an mTor inhibitor, Everolimus, effectively suppressed nanotube formation. Confocal microscopy with 3-dimensional reconstructions of sectioned surgical specimens demonstrated for the first time the presence of nanotubes in human mesothelioma and lung adenocarcinoma tumor specimens. We provide the first evidence of tunneling nanotubes in human primary tumors and cancer cells and propose that these structures play an important role in cancer cell pathogenesis and invasion.

  4. Carbon nanotube network varactor

    International Nuclear Information System (INIS)

    Generalov, A A; Anoshkin, I V; Lioubtchenko, D V; Räisänen, A V; Erdmanis, M; Ovchinnikov, V; Nasibulin, A G


    Microelectromechanical system (MEMS) varactors based on a freestanding layer of single-walled carbon nanotube (SWCNT) films were designed, fabricated and tested. The freestanding SWCNT film was employed as a movable upper patch in the parallel plate capacitor of the MEMS. The measurements of the SWCNT varactors show very high tunability, nearly 100%, of the capacitance with a low actuation voltage of 10 V. The functionality of the varactor is improved by implementing a flexible nanocellulose aerogel filling. (paper)

  5. Carbon nanotube-polymer composite actuators (United States)

    Gennett, Thomas [Denver, CO; Raffaelle, Ryne P [Honeoye Falls, NY; Landi, Brian J [Rochester, NY; Heben, Michael J [Denver, CO


    The present invention discloses a carbon nanotube (SWNT)-polymer composite actuator and method to make such actuator. A series of uniform composites was prepared by dispersing purified single wall nanotubes with varying weight percents into a polymer matrix, followed by solution casting. The resulting nanotube-polymer composite was then successfully used to form a nanotube polymer actuator.

  6. Magnetic nanotubes for drug delivery (United States)

    Ramasamy, Mouli; Kumar, Prashanth S.; Varadan, Vijay K.


    Magnetic nanotubes hold the potential for neuroscience applications because of their capability to deliver chemicals or biomolecules and the feasibility of controlling the orientation or movement of these magnetic nanotubes by an external magnetic field thus facilitating directed growth of neurites. Therefore, we sought to investigate the effects of laminin treated magnetic nanotubes and external alternating magnetic fields on the growth of dorsal root ganglion (DRG) neurons in cell culture. Magnetic nanotubes were synthesized by a hydrothermal method and characterized to confirm their hollow structure, the hematite and maghemite phases, and the magnetic properties. DRG neurons were cultured in the presence of magnetic nanotubes under alternating magnetic fields. Electron microscopy showed a close interaction between magnetic nanotubes and the growing neurites Phase contrast microscopy revealed live growing neurons suggesting that the combination of the presence of magnetic nanotubes and the alternating magnetic field were tolerated by DRG neurons. The synergistic effect, from both laminin treated magnetic nanotubes and the applied magnetic fields on survival, growth and electrical activity of the DRG neurons are currently being investigated.

  7. 21 CFR 184.1639 - Potassium lactate. (United States)


    ... HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of.... No. 996-31-6) is the potassium salt of lactic acid. It is a hydroscopic, white, odorless solid and is...

  8. Qualitative Carbohydrate Analysis using Alkaline Potassium ...

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 21; Issue 3. Qualitative Carbohydrate Analysis using Alkaline Potassium Ferricyanide. Sangeeta Pandita Saral Baweja. Classroom Volume 21 Issue 3 March 2016 pp 285-288 ...

  9. 21 CFR 181.34 - Sodium nitrite and potassium nitrite. (United States)


    ... fixatives and preservative agents, with or without sodium or potassium nitrate, in the curing of red meat... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium nitrite and potassium nitrite. 181.34...-Sanctioned Food Ingredients § 181.34 Sodium nitrite and potassium nitrite. Sodium nitrite and potassium...

  10. Potassium chloride production by microcline chlorination

    Energy Technology Data Exchange (ETDEWEB)

    Orosco, Pablo, E-mail: [Instituto de Investigaciones en Tecnología Química (INTEQUI), Chacabuco y Pedernera, San Luis (Argentina); Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, San Luis (Argentina); Ruiz, María del Carmen [Instituto de Investigaciones en Tecnología Química (INTEQUI), Chacabuco y Pedernera, San Luis (Argentina)


    Highlights: • Use of chlorination for the KCl production. • The reagents used were microcline, hydromagnesite and chlorine. • Isothermal and non-isothermal assays were performed in Cl{sub 2}–N{sub 2} mixture. • The chlorination generated KCl at 700 °C. • The chlorination products promote KCl formation. - Abstract: The potassium chloride is one of the most important fertilizers used in agriculture. The current demand of this salt makes interesting the study of potassium chloride production from unconventional potassium resources. In this work the potassium chloride production by chlorination of microcline was investigated. The starting reagents were microcline, hydromagnesite and chlorine. Non-isothermal and isothermal chlorination assays were carried out in a thermogravimetric device adapted to work in corrosive atmospheres. The temperature effect on potassium extraction and the phase transformations produced during chlorination of microcline were studied. The reagents and reaction products were analyzed by X-ray fluorescence (XRF) and X-ray diffraction (XRD). The experimental results indicated that by chlorination of microcline an important extraction of potassium in the temperature range from 800 to 900 °C was produced. Moreover, at 800 °C the forsterite, enstatite and magnesium aluminate spinel phases were generated.

  11. Physical removal of metallic carbon nanotubes from nanotube network devices using a thermal and fluidic process

    International Nuclear Information System (INIS)

    Ford, Alexandra C; Shaughnessy, Michael; Wong, Bryan M; Kane, Alexander A; Krafcik, Karen L; Léonard, François; Kuznetsov, Oleksandr V; Billups, W Edward; Hauge, Robert H


    Electronic and optoelectronic devices based on thin films of carbon nanotubes are currently limited by the presence of metallic nanotubes. Here we present a novel approach based on nanotube alkyl functionalization to physically remove the metallic nanotubes from such network devices. The process relies on preferential thermal desorption of the alkyls from the semiconducting nanotubes and the subsequent dissolution and selective removal of the metallic nanotubes in chloroform. The approach is versatile and is applied to devices post-fabrication. (paper)

  12. Carbon Nanotubes and Modern Nanoagriculture

    KAUST Repository

    Serag, Maged F.


    Since their discovery, carbon nanotubes have been prominent members of the nanomaterial family. Owing to their extraordinary physical, chemical, and mechanical properties, carbon nanotubes have been proven to be a useful tool in the field of plant science. They were frequently perceived to bring about valuable biotechnological and agricultural applications that still remain beyond experimental realization. An increasing number of studies have demonstrated the ability of carbon nanotubes to traverse different plant cell barriers. These studies, also, assessed the toxicity and environmental impacts of these nanomaterials. The knowledge provided by these studies is of practical and fundamental importance for diverse applications including intracellular labeling and imaging, genetic transformation, and for enhancing our knowledge of plant cell biology. Although different types of nanoparticles have been found to activate physiological processes in plants, carbon nanotubes received particular interest. Following addition to germination medium, carbon nanotubes enhanced root growth and elongation of some plants such as onion, cucumber and rye-grass. They, also, modulated the expression of some genes that are essential for cell division and plant development. In addition, multi-walled carbon nanotubes were evidenced to penetrate thick seed coats, stimulate germination, and to enhance growth of young tomato seedlings. Multi-walled carbon nanotubes can penetrate deeply into the root system and further distribute into the leaves and the fruits. In recent studies, carbon nanotubes were reported to be chemically entrapped into the structure of plant tracheary elements. This should activate studies in the fields of plant defense and wood engineering. Although, all of these effects on plant physiology and plant developmental biology have not been fully understood, the valuable findings promises more research activity in the near future toward complete scientific understanding of

  13. Transverse thermal magnetoresistance of potassium

    International Nuclear Information System (INIS)

    Newrock, R.S.; Maxfield, B.W.


    Results are presented of extensive thermal magnetoresistance measurements on single-crystal and polycrystalline specimens of potassium having residual resistance ratios (RRR) ranging from 1100 to 5300. Measurements were made between 2 and 9 0 K for magnetic fields up to 1.8 T. The observed thermal magnetoresistance cannot be understood on the basis of either semiclassical theories or from the electrical magnetoresistance and the Wiedemann-Franz law. A number of relationships are observed between the thermal and electrical magnetoresistances, many of which are not immediately obvious when comparing direct experimental observations. The thermal magnetoresistance W(T,H) is given reasonably well by W(T,H)T = W(T,0)T + AH + BH 2 , where both A and B are temperature-dependent coefficients. Results show that A = A 0 + A 1 T 3 , while B(T) cannot be expressed as any simple power law. A 0 is dependent on the RRR, while A 1 is independent of the RRR. Two relationships are found between corresponding coefficients in the electrical and thermal magnetoresistance: (i) the Wiedmann--Franz law relates A 0 to the Kohler slope of the electrical magnetoresistance and (ii) the temperature-dependent portions of the electrical and thermal Kohler slopes are both proportional to the electron--phonon scattering contribution to the corresponding zero-field resistance. The latter provides evidence that inelastic scattering is very important in determining the temperature-dependent linear magnetoresistances. Part, but by no means all, of the quadratic thermal resistance is accounted for by lattice thermal conduction. It is concluded that at least a portion of the anomalous electrical and thermal magnetoresistances is due to intrinsic causes and not inhomogeneities or other macroscopic defects

  14. Growth hormone suppression test (United States)

    ... page: // Growth hormone suppression test To use the sharing features on this page, please enable JavaScript. The growth hormone suppression test determines whether growth hormone production is ...

  15. Effect of polacrilin potassium as disintegrant on bioavailability of diclofenac potassium in tablets : a technical note. (United States)

    Bele, Mrudula H; Derle, Diliprao V


    Polacrilin potassium is an ion exchange resin used in oral pharmaceutical formulations as a tablet disintegrant. It is a weakly acidic cation exchange resin. Chemically, it is a partial potassium salt of a copolymer of methacrylic acid with divinyl benzene. It ionizes to an anionic polymer chain and potassium cations. It was hypothesized that polacrilin potassium may be able to improve the permeability of anionic drugs according to the Donnan membrane phenomenon. The effect of polacrilin potassium on the permeability of diclofenac potassium, used as a model anionic drug, was tested in vitro using diffusion cells and in vivo by monitoring serum levels in rats. The amount of drug permeated across a dialysis membrane in vitro was significantly more in the presence of polacrilin potassium. Significant improvement was found in the extent of drug absorption in vivo. It could be concluded that polacrilin potassium may be used as a high-functionality excipient for improving the bioavailability of anionic drugs having poor gastrointestinal permeability.

  16. Functionalized boron nitride nanotubes (United States)

    Sainsbury, Toby; Ikuno, Takashi; Zettl, Alexander K


    A plasma treatment has been used to modify the surface of BNNTs. In one example, the surface of the BNNT has been modified using ammonia plasma to include amine functional groups. Amine functionalization allows BNNTs to be soluble in chloroform, which had not been possible previously. Further functionalization of amine-functionalized BNNTs with thiol-terminated organic molecules has also been demonstrated. Gold nanoparticles have been self-assembled at the surface of both amine- and thiol-functionalized boron nitride Nanotubes (BNNTs) in solution. This approach constitutes a basis for the preparation of highly functionalized BNNTs and for their utilization as nanoscale templates for assembly and integration with other nanoscale materials.

  17. Magnetic-Field Dependence of Tunnel Couplings in Carbon Nanotube Quantum Dots

    DEFF Research Database (Denmark)

    Grove-Rasmussen, Kasper; Grap, S.; Paaske, Jens


    By means of sequential and cotunneling spectroscopy, we study the tunnel couplings between metallic leads and individual levels in a carbon nanotube quantum dot. The levels are ordered in shells consisting of two doublets with strong- and weak-tunnel couplings, leading to gate-dependent level...... renormalization. By comparison to a one- and two-shell model, this is shown to be a consequence of disorder-induced valley mixing in the nanotube. Moreover, a parallel magnetic field is shown to reduce this mixing and thus suppress the effects of tunnel renormalization....

  18. Sorption mechanisms of perfluorinated compounds on carbon nanotubes

    International Nuclear Information System (INIS)

    Deng Shubo; Zhang Qiaoying; Nie Yao; Wei Haoran; Wang Bin; Huang Jun; Yu Gang; Xing Baoshan


    Sorption of perfluorinated compounds (PFCs) on carbon nanotubes (CNTs) is critical for understanding their subsequent transport and fate in aqueous environments, but the sorption mechanisms remain largely unknown. In this study, the sorption of six PFCs on CNTs increased with increasing C-F chain length when they had a same functional group, and the CNTs with hydroxyl and carboxyl groups had much lower adsorbed amount than the pristine CNTs, indicating that hydrophobic interaction dominated the sorption of PFCs on the CNTs. Electrostatic repulsion suppressed the sorption of PFCs on the CNTs, resulting in the lower sorption with increasing pH. Hydrogen bonding interaction was negligible. The hydrophobic C-F chains can be closely adsorbed on the CNTs surface in parallel to the axis or along the curvature, making it impossible to form micelles on the CNT surface, leading to the lower sorption than other adsorbents. Highlights: ► Sorption capacities of PFOA on different CNTs are less than that on activated carbon and resins. ► Hydrophobic interaction is principally involved in the sorption of PFCs on CNTs. ► Electrostatic repulsion suppresses the sorption of PFCs on CNTs. - Hydrophobic interaction dominated the sorption of perfluorinated compounds on carbon nanotubes, while electrostatic repulsion suppressed their sorption.

  19. Tunable synthesis of copper nanotubes

    International Nuclear Information System (INIS)

    Kaniukov, E; Yakimchuk, D; Kozlovsky, A; Shlimas, D; Zdorovets, M; Kadyrzhanov, K


    Simple method of tunable synthesis of copper nanotubes based on template synthesis was developed. A comprehensive study of the structural, morphological and electrical characteristics of the obtained nanostructures was carried out. Characterization of structural features was made by methods of scanning electron microscopy, energy dispersive spectroscopy and X-ray diffractometry analysis. Evaluation of wall thickness is made by methods of gas permeability. Electrical conductivity of nanotubes was define in the study of their current-voltage characteristics. The possibility to control of copper nanotubes physical properties by variation of the deposition parameters was shown. (paper)

  20. Multiscale Modeling with Carbon Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Maiti, A


    Technologically important nanomaterials come in all shapes and sizes. They can range from small molecules to complex composites and mixtures. Depending upon the spatial dimensions of the system and properties under investigation computer modeling of such materials can range from equilibrium and nonequilibrium Quantum Mechanics, to force-field-based Molecular Mechanics and kinetic Monte Carlo, to Mesoscale simulation of evolving morphology, to Finite-Element computation of physical properties. This brief review illustrates some of the above modeling techniques through a number of recent applications with carbon nanotubes: nano electromechanical sensors (NEMS), chemical sensors, metal-nanotube contacts, and polymer-nanotube composites.

  1. Role of ATP sensitive potassium channel in extracellular potassium accumulation and cardiac arrhythmias during myocardial ischaemia. (United States)

    Billman, G E


    Extracellular potassium rises rapidly during myocardial ischaemia, correlating with the onset of ventricular arrhythmias. The extracellular accumulation of potassium can induce abnormalities in both impulse conduction and impulse generation. Inhomogeneities of potassium conductance will elicit regional differences in action potential duration and repolarisation. The resulting spatial dispersion of refractory period will allow for fragmentation of impulse conduction on ensuing beats, the formation of irregular reentrant pathways and ventricular fibrillation. In a similar manner, the spread of injury current from the ischaemic tissue to surrounding normal tissue can trigger extrasystoles (depolarisation induced automaticity). It has been hypothesised that the activation of the ATP sensitive potassium channel contributes significantly to reductions in action potential duration and increases in extracellular potassium accumulation during myocardial ischaemia. ATP sensitive potassium channel antagonists prevent ischaemically induced reductions in action potential duration and the dispersion of refractory period but may induce oscillatory afterpotentials under some conditions (for example, calcium overload). In contrast, potassium channel agonists enhance the dispersion of refractory period ischaemia, which promotes the formation of re-entrant arrhythmias. The pharmacological modulation of the ATP sensitive potassium channels could therefore offer a novel approach for the management of cardiac arrhythmias in patients with ischaemic heart disease. In general, channel antagonists prevent ventricular fibrillation, while high (hypotensive) doses of channel agonists can induce malignant arrhythmias during ischaemia in animal models. However, recent evidence also suggests that potassium channel agonists may promote a better preservation of myocardial mechanical performance during reperfusion while ATP sensitive potassium channel antagonists exacerbate mechanical depression

  2. Potassium adsorption in soil cultivated with sugarcane. (United States)

    Freitas, Joycyely M A S; Netto, André M; Corrêa, Marcus M; Xavier, Bruno T L; Assis, Fernando X DE


    Vinasse is a byproduct of the process of distillation of sugarcane juice for the manufacture of sugar and alcohol. Because it is rich in nutrients, mainly potassium (K), is used as fertilizer and applied via fertigation, without concerning for the fate of this compound in the soil. Thus, the objective of the study was to evaluate the interactions of the potassium ion (K+), applied via vinasse in a soil representative of the sugarcane zone of the State of Pernambuco using adsorption isotherms. The methodology was based on physical, chemical and soil mineralogical characterization, as well as equilibrium batch tests, where the experimental curves were fitted by Langmuir and Freundlich isotherm models. The results allowed to infer that the Freundlich model showed better fit of the curve in both forms: linear and non-linear (direct fit); the non-linear model was selected due to the values ​​of coefficient of determination (R²). The interaction between potassium and soil occurred mainly with organic matter and the presence of soil kaolinite, because they showed negative ions on the external surface, thereby promoting potassium adsorption. Soil potassium adsorption capacity was higher for the first layer (0-20 cm) and decreased along the depth profile.

  3. Studies of Carbon Nanotubes (United States)

    Caneba, Gerard T.


    The fellowship experience for this summer for 2004 pertains to carbon nanotube coatings for various space-related applications. They involve the following projects: (a) EMI protection films from HiPco-polymers, and (b) Thermal protection nanosilica materials. EMI protection films are targeted to be eventually applied onto casings of laptop computers. These coatings are composites of electrically-conductive SWNTs and compatible polymers. The substrate polymer will be polycarbonate, since computer housings are typically made of carbon composites of this type of polymer. A new experimental copolymer was used last year to generate electrically-conductive and thermal films with HiPco at 50/50 wt/wt composition. This will be one of the possible formulations. Reference films will be base polycarbonate and neat HiPco onto polycarbonate films. Other coating materials that will be tried will be based on HiPco composites with commercial enamels (polyurethane, acrylic, polyester), which could be compatible with the polycarbonate substrate. Nanosilica fibers are planned for possible use as thermal protection tiles on the shuttle orbiter. Right now, microscale silica is used. Going to the nanoscale will increase the surface-volume-per-unit-area of radiative heat dissipation. Nanoscale carbon fibers/nanotubes can be used as templates for the generation of nanosilica. A sol-gel operation is employed for this purpose.


    Energy Technology Data Exchange (ETDEWEB)

    Alsobrook, A. N.; Hobbs, D. T.


    This report presents a summary of testing the affinity of titanosilicates (TSP), germanium-substituted titanosilicates (Ge-TSP) and multiwall carbon nanotubes (MWCNT) for lanthanide ions in dilute nitric acid solution. The K-TSP ion exchanger exhibited the highest affinity for lanthanides in dilute nitric acid solutions. The Ge-TSP ion exchanger shows promise as a material with high affinity, but additional tests are needed to confirm the preliminary results. The MWCNT exhibited much lower affinities than the K-TSP in dilute nitric acid solutions. However, the MWCNT are much more chemically stable to concentrated nitric acid solutions and, therefore, may candidates for ion exchange in more concentrated nitric acid solutions. This technical report serves as the deliverable documenting completion of the FY13 research milestone, M4FT-13SR0303061 – measure actinide and lanthanide distribution values in nitric acid solutions with sodium and potassium titanosilicate materials.

  5. Potassium permanganate ingestion as a suicide attempt

    Directory of Open Access Journals (Sweden)

    Tuba Cimilli Ozturk


    Full Text Available Potassium permanganate is a highly corrosive, water-soluble oxidizing antiseptic. A 68- year-old female patient was admitted to our Emergency Department after ingestion of 3 tablets of 250 mg potassium permanganate as a suicide attempt. The physical exam revealed brown stained lesions in the oropharynx. Emergency endoscopy was performed by the gastroenterologist after the third hour of ingestion. Emergency endoscopy revealed multiple superficial (Grade I-II lesions on the esophagus and cardia, which were considered secondary to the caustic substance. The mainstay in the treatment of potassium permanganate is supportive and the immediate priority is to secure the airway. Emergency endoscopy is an important tool used to evaluate the location and severity of injury to the esophagus, stomach and duodenum after caustic ingestion. Patients with signs and symptoms of intentional ingestion should undergo endoscopy within 12 to 24 h to define the extent of the disease.

  6. Noble-Metal Chalcogenide Nanotubes

    Directory of Open Access Journals (Sweden)

    Nourdine Zibouche


    Full Text Available We explore the stability and the electronic properties of hypothetical noble-metal chalcogenide nanotubes PtS2, PtSe2, PdS2 and PdSe2 by means of density functional theory calculations. Our findings show that the strain energy decreases inverse quadratically with the tube diameter, as is typical for other nanotubes. Moreover, the strain energy is independent of the tube chirality and converges towards the same value for large diameters. The band-structure calculations show that all noble-metal chalcogenide nanotubes are indirect band gap semiconductors. The corresponding band gaps increase with the nanotube diameter rapidly approaching the respective pristine 2D monolayer limit.

  7. Proposal of Carbon Nanotube Inductors

    National Research Council Canada - National Science Library

    Tsubaki, K; Nakajima, Y; Hanajiri, T; Yamaguchi, H


    The inductors made of carbon Nanotube (CNT) have been proposed. Though the fabrication of the proposed inductor is still challenging and has many problems, merits of the proposed inductor are following...

  8. Atomistic simulations of nanotube fracture (United States)

    Belytschko, T.; Xiao, S. P.; Schatz, G. C.; Ruoff, R. S.


    The fracture of carbon nanotubes is studied by molecular mechanics simulations. The fracture behavior is found to be almost independent of the separation energy and to depend primarily on the inflection point in the interatomic potential. The fracture strain of a zigzag nanotube is predicted to be between 10% and 15%, which compares reasonably well with experimental results. The predicted range of fracture stresses is 65-93 GPa and is markedly higher than observed. The computed fracture strengths of chiral and armchair nanotubes are above these values. Various plausible small-scale defects do not suffice to bring the failure stresses into agreement with available experimental results. As in the experiments, the fracture of carbon nanotubes is predicted to be brittle.

  9. Method for producing carbon nanotubes (United States)

    Phillips, Jonathan [Santa Fe, NM; Perry, William L [Jemez Springs, NM; Chen, Chun-Ku [Albuquerque, NM


    Method for producing carbon nanotubes. Carbon nanotubes were prepared using a low power, atmospheric pressure, microwave-generated plasma torch system. After generating carbon monoxide microwave plasma, a flow of carbon monoxide was directed first through a bed of metal particles/glass beads and then along the outer surface of a ceramic tube located in the plasma. As a flow of argon was introduced into the plasma through the ceramic tube, ropes of entangled carbon nanotubes, attached to the surface of the tube, were produced. Of these, longer ropes formed on the surface portion of the tube located in the center of the plasma. Transmission electron micrographs of individual nanotubes revealed that many were single-walled.

  10. Quantum transport in carbon nanotubes

    DEFF Research Database (Denmark)

    Laird, Edward A.; Kuemmeth, Ferdinand; Steele, Gary A.


    Carbon nanotubes are a versatile material in which many aspects of condensed matter physics come together. Recent discoveries, enabled by sophisticated fabrication, have uncovered new phenomena that completely change our understanding of transport in these devices, especially the role of the spin...... blockade. This can be exploited to read out spin and valley qubits, and to measure the decay of these states through coupling to nuclear spins and phonons. A second unique property of carbon nanotubes is that the combination of valley freedom and electron-electron interactions in one dimension strongly...... and valley degrees of freedom. This review describes the modern understanding of transport through nanotube devices. Unlike conventional semiconductors, electrons in nanotubes have two angular momentum quantum numbers, arising from spin and from valley freedom. We focus on the interplay between the two...

  11. Gold(I)-Alkanethiolate Nanotubes

    KAUST Repository

    Zhang, Yu Xin


    (Figure Presented) A solution approach to assembling Au(I) - alkanethiolates into nanotube structures at room temperature is presented, in which Au(I) cations and alkanethiolate ligands are coordinated into thin platelet forms that then evolve into an open tubular configuration (see figure). The organic-inorganic hybrid nature of the nanotubes, their ability to be modified, and their high stability make them of interest for practical applications. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA.

  12. Selective functionalization of carbon nanotubes (United States)

    Strano, Michael S. (Inventor); Usrey, Monica (Inventor); Barone, Paul (Inventor); Dyke, Christopher A. (Inventor); Tour, James M. (Inventor); Kittrell, W. Carter (Inventor); Hauge, Robert H. (Inventor); Smalley, Richard E. (Inventor)


    The present invention is directed toward methods of selectively functionalizing carbon nanotubes of a specific type or range of types, based on their electronic properties, using diazonium chemistry. The present invention is also directed toward methods of separating carbon nanotubes into populations of specific types or range(s) of types via selective functionalization and electrophoresis, and also to the novel compositions generated by such separations.

  13. Carbon nanotubes for coherent spintronics

    DEFF Research Database (Denmark)

    Kuemmeth, Ferdinand; Churchill, H O H; Herring, P K


    Carbon nanotubes bridge the molecular and crystalline quantum worlds, and their extraordinary electronic, mechanical and optical properties have attracted enormous attention from a broad scientific community. We review the basic principles of fabricating spin-electronic devices based on individual......, electrically-gated carbon nanotubes, and present experimental efforts to understand their electronic and nuclear spin degrees of freedom, which in the future may enable quantum applications....

  14. Synthesis and characterization of titania nanotubes by anodizing of titanium in fluoride containing electrolytes (United States)

    Ahmad, Akhlaq; Haq, Ehsan Ul; Akhtar, Waseem; Arshad, Muhammad; Ahmad, Zubair


    Titania nanotubular structure was prepared by anodizing titanium metal in the fluoride containing electrolytes and studied for hydrogen reduction using photo electrochemical cell. Potentiodynamic scan was performed before actual anodizing to optimize the anodizing conditions. The morphology of the TiO2 nanotubes was investigated by SEM and the presence of TiO2 nanotubes was confirmed. Raman spectroscopy was done to confirm the different phases present. Hydrogen generation capability was revealed by electrochemical testing in three-electrode system in dark and in visible light at 200 W power using Gamry Potentiostat. The corrosion potential of TiO2 nanotubes produced was found to be more active side in potassium hydroxide solution under visible light than in the dark condition. Cathodic polarization behavior of specimens in the presence of light showed more activity towards hydrogen generation than in dark condition. In comparison, the hydrogen generation capability of specimen anodized in 2H15 electrolyte was higher than specimens anodized in other electrolytes. Electrochemical impedance spectroscopy was used to study the charge transfer resistance of the nanotubes produced. The results showed that TiO2 nanotubular structure is a promising material for photoelectrochemical cell. Low-charge transfer resistance also depicts that it can be efficiently used to harvest solar energy.

  15. Defect-enhanced Rashba spin-polarized currents in carbon nanotubes (United States)

    Santos, Hernán; Chico, Leonor; Alvarellos, J. E.; Latgé, A.


    The production of spin-polarized currents in pristine carbon nanotubes with Rashba spin-orbit interactions has been shown to be very sensitive to the symmetry of the tubes and the geometry of the setup. Here we analyze the role of defects on the spin quantum conductances of metallic carbon nanotubes due to an external electric field. We show that localized defects, such as adsorbed hydrogen atoms or pentagon-heptagon pairs, increase the Rashba spin-polarized current. Moreover, this enhancement takes place for energies closer to the Fermi energy as compared to the response of pristine tubes. Such increments can be even larger when several equally spaced defects are introduced into the system. We explore different arrangements of defects, showing that for certain geometries there are flips of the spin-polarized current and even transport suppression. Our results indicate that spin valve devices at the nanoscale may be achieved via defect engineering in carbon nanotubes.

  16. Probing Photosensitization by Functionalized Carbon Nanotubes (United States)

    Carbon nanotubes (CNTs) photosensitize the production of reactive oxygen species that can damage organisms by biomembrane oxidation or mediate CNTs' environmental transformations. The photosensitized nature of derivatized carbon nanotubes from various synthetic methods, and thus ...

  17. Oligomer functionalized nanotubes and composites formed therewith (United States)

    Zettl, Alexander K; Sainsbury, Toby; Frechet, Jean M.J.


    Disclosed herein is a sequential functionalization methodology for the covalent modification of nanotubes with between one and four repeat units of a polymer. Covalent attachment of oligomer units to the surface of nanotubes results in oligomer units forming an organic sheath around the nanotubes, polymer-functionalized-nanotubes (P-NTs). P-NTs possess chemical functionality identical to that of the functionalizing polymer, and thus provide nanoscale scaffolds which may be readily dispersed within a monomer solution and participate in the polymerization reaction to form a polymer-nanotube/polymer composite. Formation of polymer in the presence of P-NTs leads to a uniform dispersion of nanotubes within the polymer matrix, in contrast to aggregated masses of nanotubes in the case of pristine-NTs. The covalent attachment of oligomeric units to the surface of nanotubes represents the formation of a functional nanoscale building block which can be readily dispersed and integrated within the polymer to form a novel composite material.

  18. Polymer nanotube nanocomposites: synthesis, properties, and applications

    National Research Council Canada - National Science Library

    Mittal, Vikas


    ... in these commercially important areas of polymer technology. It sums up recent advances in nanotube composite synthesis technology, provides basic introduction to polymer nanotubes nanocomposite technology for the readers new to this field, provides valuable...

  19. Carbon nanotube biconvex microcavities

    Energy Technology Data Exchange (ETDEWEB)

    Butt, Haider, E-mail:; Ahmed, Rajib [Nanotechnology Laboratory, School of Mechanical Engineering, University of Birmingham, Birmingham B15 2TT (United Kingdom); Yetisen, Ali K.; Yun, Seok Hyun [Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, 50 Blossom Street, Boston, Massachusetts 02114 (United States); Dai, Qing [National Center for Nanoscience and Technology, Beijing 100190 (China)


    Developing highly efficient microcavities with predictive narrow-band resonance frequencies using the least amount of material will allow the applications in nonlinear photonic devices. We have developed a microcavity array that comprised multi-walled carbon nanotubes (MWCNT) organized in a biconvex pattern. The finite element model allowed designing microcavity arrays with predictive transmission properties and assessing the effects of the microarray geometry. The microcavity array demonstrated negative index and produced high Q factors. 2–3 μm tall MWCNTs were patterned as biconvex microcavities, which were separated by 10 μm in an array. The microcavity was iridescent and had optical control over the diffracted elliptical patterns with a far-field pattern, whose properties were predicted by the model. It is anticipated that the MWCNT biconvex microcavities will have implications for the development of highly efficient lenses, metamaterial antennas, and photonic circuits.

  20. Carbon Nanotube Biosensors

    Directory of Open Access Journals (Sweden)

    Carmen-Mihaela eTilmaciu


    Full Text Available Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular Carbon Nanotubes (CNTs can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we will describe their structural and physical properties, discuss functionalization and cellular uptake, biocompatibility and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers.

  1. Carbon Nanotube Biosensors (United States)

    Tilmaciu, Carmen-Mihaela; Morris, May


    Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular Carbon Nanotubes (CNTs) can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we will describe their structural and physical properties, discuss functionalization and cellular uptake, biocompatibility and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers.

  2. Carbon Nanotube Electron Gun (United States)

    Nguyen, Cattien V. (Inventor); Ribaya, Bryan P. (Inventor)


    An electron gun, an electron source for an electron gun, an extractor for an electron gun, and a respective method for producing the electron gun, the electron source and the extractor are disclosed. Embodiments provide an electron source utilizing a carbon nanotube (CNT) bonded to a substrate for increased stability, reliability, and durability. An extractor with an aperture in a conductive material is used to extract electrons from the electron source, where the aperture may substantially align with the CNT of the electron source when the extractor and electron source are mated to form the electron gun. The electron source and extractor may have alignment features for aligning the electron source and the extractor, thereby bringing the aperture and CNT into substantial alignment when assembled. The alignment features may provide and maintain this alignment during operation to improve the field emission characteristics and overall system stability of the electron gun.

  3. Carbon nanotube biosensors (United States)

    Tîlmaciu, Carmen-Mihaela; Morris, May C.


    Nanomaterials possess unique features which make them particularly attractive for biosensing applications. In particular, carbon nanotubes (CNTs) can serve as scaffolds for immobilization of biomolecules at their surface, and combine several exceptional physical, chemical, electrical, and optical characteristics properties which make them one of the best suited materials for the transduction of signals associated with the recognition of analytes, metabolites, or disease biomarkers. Here we provide a comprehensive review on these carbon nanostructures, in which we describe their structural and physical properties, functionalization and cellular uptake, biocompatibility, and toxicity issues. We further review historical developments in the field of biosensors, and describe the different types of biosensors which have been developed over time, with specific focus on CNT-conjugates engineered for biosensing applications, and in particular detection of cancer biomarkers. PMID:26579509

  4. Extracting metals with carbon nanotubes: environmental possibilities


    Alguacil, Francisco José; Cerpa Naranjo, Arisbel; Lado Touriño, María Isabel; López, Félix A.


    This paper presents a review of the environmental possibilities of using carbon nanotubes (CNTs) for extracting metals, taken into account the characteristics of carbon nanotubes to be used as adsorbents and the influence of different factors on the adsorption processes, among them: kind of carbon nanotubes used as adsorbent, particle size, pH of solutions and diameter and length of carbon nanotubes. Also, some images of transmission electron microscopy (TEM), atomic force micr...

  5. Electronics with carbon nanotubes

    International Nuclear Information System (INIS)

    Avouris, P.


    From mobile phones and laptops to Xboxes and iPods, it is difficult to think of any aspect of modern life that has not been touched by developments in electronics, computing and communications over the last few decades. Many of these technological advances have arisen from our ability to create ever smaller electronic devices, in particular silicon-based field effect transistors (FETs), which has led to denser, faster and less power-hungry circuits. The problem is that this device miniaturization, or 'scaling', cannot continue forever. Fundamental scientific and technological limitations exist that will make it impossible to build better performing silicon devices below a certain size. This potential show-stopper has inspired a worldwide effort to develop alternative device technologies based on 1D materials or those that exploit the spin, as well as the charge, of electrons. One promising and, in principle, simpler approach is to maintain the operating concept of today's silicon-based FETs but to replace a key component of the device - the semiconducting silicon channel - with 1D nanostructures that have much more versatile electrical-transport properties. Among the different 1D materials that have been developed, those with the most desirable properties are 'single-walled' carbon nanotubes, which were first created in 1993 by Sumio Ijima at the NEC Fundamental Research Laboratory in Tsukuba, Japan, and by Donald Bethune of IBM's Almaden Research Center in California. These materials are hollow tubes made from rolled up sheets of carbon just one atom thick, otherwise known as graphene. In the March issue of Physics World, Phaedon Avouris discusses some of the many properties and applications of carbon nanotubes, which he describes as an 'engineer's dream' because of their exceptionally high strength and heat conduction. (U.K.)

  6. 21 CFR 862.1600 - Potassium test system. (United States)


    ... potassium in serum, plasma, and urine. Measurements obtained by this device are used to monitor electrolyte balance in the diagnosis and treatment of diseases conditions characterized by low or high blood potassium levels. (b) Classification. Class II. ...

  7. Potassium load from blood transfusion in dialysis patients. (United States)

    Malament, I B; Uhlman, W; Eisinger, R P


    When a transfusion of packed red blood cells is given, the net potassium load results from lysis of some cells and absorption of potassium by surviving cells. Potassium load was calculated which results from administration of 1 unit (200 cc.) of packed RBC and also that resulting from administration of sufficient packed cells to yield 200 cc. of surviving RBC. Although the acute load of potassium due to cell lysis increases as blood is stored for longer periods, the absorption of potassium by surviving cells also increases. Thus, net potassium load may be least if blood is stored for about one week. Hence the acute potassium load and the net potassium burden a patient receives from a transfusion can be considered when transfusion therapy is selected.

  8. Altered potassium homeostasis in Crohn's disease

    International Nuclear Information System (INIS)

    Schober, O.; Hundeshagen, H.; Bosaller, C.; Lehr, L.


    The total body potassium (TBK), serum potassium, and the number of red blood cell ouabain-binding sites was studied in 94 patients with Crohn's diease. TBK was measured by counting the endogenous 40 K in a whole body counter. TBK was 87%+-13% in 94 patients was Crohn's disease, while in control subjects, it was 97%+-12% (n=24). This significant reduction in TBK was accompanied by normal serum potassium levels (4.4+-0.5 mM). TBK was significantly correlated with the Crohn's disease activity index (r=0.79, n=113, P 3 H-ouabain showed a significant increse in the number of Na-K pumps in Crohn's disease (396+-65, n=27) compared with the control group. 290+-45 (n=24). These results support the suggestion that changes in TBK may regulate the synthesis of Na-K pump molecules. The total body potassium depletion and the need for a preoperative nutritional support in Crohn's disease are discussed. (orig.)

  9. Acute Renal Failure following Accidental Potassium Bromate ...

    African Journals Online (AJOL)

    Accidental poisoning is common in children. Potassium bromate is a commonly used additive and raising agent in many edibles particularly bread, a staple food worldwide, yet its accidental poisoning has hitherto, not been documented in Nigeria. We report an unusual case of acute renal failure following accidental ...

  10. Effect Of Virkon Disinfectant Brand Of Potassium ...

    African Journals Online (AJOL)

    In the Nigerian market are many brands of disinfectants with varying efficacy against bacteria, fungi and viruses. Recently Virkon brand of potassium monoperoxysulphate (Antec, UK) was introduced. The Kelsey -Sykes test was carried out to determine the efficacy of Virkon against standard bacterial strains and ...

  11. The Ketogenic Diet and Potassium Channel Function (United States)


    observation is not reversed by the KD which to some extent supports our initial hypothesis. 15. SUBJECT TERMS Epilepsy , Ketogenic Diet , Seizure Disorder... ketogenic diet (KD), which is used to treat epilepsy (primarily in children) exerts a positive effect on seizure activity by regulating neuronal... Epilepsy , Ketogenic Diet , Seizure Disorder, Potassium Channels, Neurophysiology 3. Overall Project Summary: To determine the impact of KD on

  12. 21 CFR 182.3616 - Potassium bisulfite. (United States)


    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium bisulfite. 182.3616 Section 182.3616 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Chemical Preservatives § 182.3616...

  13. 21 CFR 582.3616 - Potassium bisulfite. (United States)


    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Potassium bisulfite. 582.3616 Section 582.3616 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Chemical Preservatives § 582...

  14. 21 CFR 582.3640 - Potassium sorbate. (United States)


    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Potassium sorbate. 582.3640 Section 582.3640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Chemical Preservatives § 582...

  15. 21 CFR 182.3640 - Potassium sorbate. (United States)


    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium sorbate. 182.3640 Section 182.3640 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Chemical Preservatives § 182.3640...

  16. 21 CFR 182.3637 - Potassium metabisulfite. (United States)


    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium metabisulfite. 182.3637 Section 182.3637 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Chemical Preservatives § 182...

  17. 21 CFR 582.3637 - Potassium metabisulfite. (United States)


    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Potassium metabisulfite. 582.3637 Section 582.3637 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Chemical Preservatives § 582...

  18. 21 CFR 184.1634 - Potassium iodide. (United States)


    ... HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of.... 7681-11-0) is the potassium salt of hydriodic acid. It occurs naturally in sea water and in salt... supplement as defined in § 170.3(o)(20) of this chapter. (d) The ingredient is used in table salt in...


    African Journals Online (AJOL)


    An alternative rationale for corn N fertilizer recommendations. J. Prod. Agric. 7: 243-249. Vanotti, M. B. and Bundy, L. G. 1994b. Corn nitrogen recommendations based on yield response data. J. Prod. Agric. 7: 249-256. Wild, A. A. 1971. The potassium status of soils in the savanna zone of Nigeria. Expl. Agric. 7: 257-270. 87.

  20. Nutritional potassium requirement for laying Japanese quails

    Directory of Open Access Journals (Sweden)

    Fernando Guilherme Perazzo Costa


    Full Text Available The objective of this study was to evaluate the potassium requirement for laying Japanese quails. Two hundred and forty quails were distributed in a randomized block design, with five treatments and six replicates, with eight birds each. The treatments consisted of a basal diet deficient in potassium (K (2.50 g/kg, supplemented with potassium carbonate, to replace the inert, to reach levels of 2.50, 3.50, 4.50, 5.50 and 6.50 (g/kg of K in the diet. There was a quadratic effect of K levels on feed intake, egg production, egg mass and feed conversion per egg mass and per egg dozen, estimating the requirements of 4.26, 4.41, 4.38, 4.43 and 4.48 (g/kg of K diet, respectively. There was no significant effect on the levels of K in the diet on egg weight, albumen weight, percentage of yolk or shell and yolk color. However, yolk and shell weights reduced and the albumen percentage increased linearly with increasing levels of K in the diet. Despite the reduction of shell weight, the increased levels of K did not influence the specific gravity and shell thickness. The use of 4.41 g/kg of potassium is recommended in the diet for laying Japanese quails.

  1. Potassium ferrate treatment of RFETS' contaminated groundwater

    International Nuclear Information System (INIS)


    The potassium ferrate treatment study of Rocky Flats Environmental Technology Site (RFETS) groundwater was performed under the Sitewide Treatability Studies Program (STSP). This study was undertaken to determine the effectiveness of potassium ferrate in a water treatment system to remove the contaminants of concern (COCS) from groundwater at the RFETS. Potassium ferrate is a simple salt where the iron is in the plus six valence state. It is the iron at the plus six valence state (Fe +6 ) that makes it an unique water treatment chemical, especially in waters where the pH is greater than seven. In basic solutions where the solubility of the oxides/hydroxides of many of the COCs is low, solids are formed as the pH is raised. By using ferrate these solids are agglomerated so they can be effectively removed by sedimentation in conventional water treatment equipment. The objective of this study was to determine the quality of water after treatment with potassium ferrate and to determine if the Colorado Water Quality Control Commission (CWQCC) discharge limits for the COCs listed in Table 1.0-1 could be met. Radionuclides in the groundwater were of special concern

  2. Effect of potassium on micromorphological and chemical ...

    African Journals Online (AJOL)



    Aug 4, 2009 ... Euglena gracilis together with a monogram for the determination of chlorophyll concentration. Planta, 78: 200-207. Liang DY, Xu MD, Wang S, Chen PS, Lin FQ, Wen RT, Zhang YJ. (1992). Effects of potassium application on nutrient uptake and dry matter accumulation in cotton. Scientia Agricultura Sinica ...

  3. The existence of the potassium dioxodifluorobromate

    International Nuclear Information System (INIS)

    Tantot, Georges; Bougon, Roland


    The reaction of liquid bromine pentafluoride with potassium bromate allows the formation of an oxyfluorinated complex ion of bromine V: the dioxodifluorobromate ion BrO 2 F 2 - . From Raman spectroscopy data this ion has a structure related to those of the chlorine and iodine corresponding ions [fr

  4. 186 183 Potassium Bromate Content of Bread

    African Journals Online (AJOL)


    Dec 2, 2008 ... nutritional quality of bread. This leads to degradation of vitamin A, B1, B2 , E and niacin. Results obtained from in-vivo and in-vitro mutagenic studies show that potassium bromate is a potential cancer initiator. In humans, acute intoxication of this substance leads to renal failure and loss of hearing (Sai et al., ...

  5. 21 CFR 184.1613 - Potassium bicarbonate. (United States)


    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Potassium bicarbonate. 184.1613 Section 184.1613 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) DIRECT FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE Listing of Specific Substances Affirmed as GRAS §...

  6. Effect of potassium on micromorphological and chemical ...

    African Journals Online (AJOL)



    Aug 4, 2009 ... African Journal of Biotechnology Vol. 8 (15), pp. 3511-3518, 4 August, ... P2O5/kg soil to all the pots, while potassium (K) was applied at three levels; control (no K), 100 and 200 mg K2O/kg soil. ... Key words: Cotton, mesophyl cells, starch grains, protein, seed cotton yield, K applicatiion. INTRODUCTION.

  7. doped cadmium potassium phosphate hexahydrate: A substitutional ...

    Indian Academy of Sciences (India)

    Single crystal EPR studies of VO(II)-doped cadmium potassium phosphate hexahydrate (CPPH) have been carried out at room temperature. The angular variation spectra in the three orthogonal planes indicate that the paramagnetic impurity has entered the lattice only substitutionally in place of Cd(II). Spin Hamiltonian ...

  8. Synthesis and Immobilization of Pt Nanoparticles on Amino-Functionalized Halloysite Nanotubes toward Highly Active Catalysts

    Directory of Open Access Journals (Sweden)

    Tingting Yang


    Full Text Available A simple and effective method for the preparation of platinum nanoparticles (Pt NPs grown on amino-func‐ tionalized halloysite nanotubes (HNTs was developed. The nanostructures were synthesized through the func‐ tionalization of the HNTs, followed by an in situ approach to generate Pt NPs with diameter of approximately 1.5 nm within the entire HNTs. The synthesis process, composition and morphology of the nanostructures were characterized. The results suggest PtNPs/NH2-HNTs nanostructures with ultrafine PtNPs were successfully synthesized by green chemically-reducing H2PtCl6 without the use of surfactant. The nanostructures exhibit promising catalytic properties for reducing potassium hexacyanoferrate(III to potassium hexacyanoferrate(II. The presented experiment for novel PtNPs/NH2-HNTs nanostructures is quite simple and environmentally benign, permitting it as a potential application in the future field of catalysts.

  9. Dispersions of Carbon nanotubes in Polymer Matrices (United States)

    Wise, Kristopher Eric (Inventor); Park, Cheol (Inventor); Siochi, Emilie J. (Inventor); Harrison, Joycelyn S. (Inventor); Lillehei, Peter T. (Inventor); Lowther, Sharon E. (Inventor)


    Dispersions of carbon nanotubes exhibiting long term stability are based on a polymer matrix having moieties therein which are capable of a donor-acceptor complexation with carbon nanotubes. The carbon nanotubes are introduced into the polymer matrix and separated therein by standard means. Nanocomposites produced from these dispersions are useful in the fabrication of structures, e.g., lightweight aerospace structures.

  10. Synthesis of carbon nanotubes bridging metal electrodes

    International Nuclear Information System (INIS)

    Kotlar, M.; Vojs, M.; Marton, M.; Vesel, M.; Redhammer, R.


    In our work we demonstrate growth of carbon nanotubes that can conductively bridge the metal electrodes. The role of different catalysts was examined. Interdigitated metal electrodes are made from copper and we are using bimetal Al/Ni as catalyst for growth of carbon nanotubes. We are using this catalyst composition for growth of the single-walled carbon nanotube network. (authors)

  11. Potassium and thallium uptake in dog myocardium. (United States)

    Bassingthwaighte, J B; Winkler, B; King, R B


    We sought to ascertain the rates and mechanisms of uptake of markers for regional myocardial blood flows. The rates of exchange of potassium and thallium across capillary walls and cell membranes in isolated blood-perfused dog hearts were estimated from multiple indicator dilution curves recorded for 131I-albumin, 42K and 201Tl from the coronary sinus outflow following injection into arterial inflow. Analysis involved fitting the observed dilution curves with a model composed of a capillary-interstitial fluid-cell exchange region and nonexchanging larger vessels. Capillary permeability surface products (PSc) for potassium and thallium were similar, 0.82 +/- 0.33 (mean +/- s.d., n = 19) and 0.87 +/- 0.32 ml min-1 g-1 (n = 24) with a ratio for simultaneous pairs of 1.02 +/- 0.27 (n = 19). For the myocardial cells, PSpc averaged 3.7 +/- 3.1 ml min-1 g-1 (n = 19) for K+ and 9.5 +/- 3.9 (n = 24) for Tl+; the ratio of potassium to thallium averaged 0.40 +/- 0.19 (n = 18), thereby omitting a single high value for potassium. This high cellular influx for thallium is interpreted as due to its passage through ionic channels for both Na+ and K+. The high permeabilities and large volumes of distribution make thallium and potassium among the best ionic deposition markers for regional flow. Their utility for this purpose is compromised by significant capillary barrier limitation retarding uptake; so regional flow is underestimated modestly in high-flow regions particularly.

  12. Determinants of renal potassium excretion in critically ill patients : The role of insulin therapy

    NARCIS (Netherlands)

    Hoekstra, Miriam; Yeh, Lu; Oude Lansink, Annemieke; Vogelzang, Mathijs; Stegeman, Coen A.; Rodgers, Michael G. G.; van der Horst, Iwan C. C.; Wietasch, Gotz; Zijlstra, Felix; Nijsten, Maarten W. N.

    Objectives: Insulin administration lowers plasma potassium concentration by augmenting intracellular uptake of potassium. The effect of insulin administration on renal potassium excretion is unclear. Some studies suggest that insulin has an antikaliuretic effect although plasma potassium levels were

  13. 21 CFR 182.1129 - Aluminum potassium sulfate. (United States)


    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Aluminum potassium sulfate. 182.1129 Section 182.1129 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Food Substances § 182.1129 Aluminum potassium sulfate. (a) Product. Aluminum potassium sulfate. (b...

  14. 21 CFR 582.1129 - Aluminum potassium sulfate. (United States)


    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Aluminum potassium sulfate. 582.1129 Section 582.1129 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... Additives § 582.1129 Aluminum potassium sulfate. (a) Product. Aluminum potassium sulfate. (b) Conditions of...

  15. 40 CFR 721.10031 - Lithium potassium titanium oxide. (United States)


    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Lithium potassium titanium oxide. 721... Substances § 721.10031 Lithium potassium titanium oxide. (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified as lithium potassium titanium oxide (PMN P-02...

  16. A novel potassium deficiency-induced stimulon in Anabaena torulosa

    Indian Academy of Sciences (India)


    torulosa and of nine proteins in Escherichia coli. These were termed potassium deficiency-induced proteins or. PDPs and constitute hitherto unknown potassium deficiency–induced stimulons. Potassium deficiency also enhanced the synthesis of certain osmotic stress-induced proteins. Addition of K+ repressed the ...

  17. 21 CFR 181.33 - Sodium nitrate and potassium nitrate. (United States)


    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Sodium nitrate and potassium nitrate. 181.33...-Sanctioned Food Ingredients § 181.33 Sodium nitrate and potassium nitrate. Sodium nitrate and potassium nitrate are subject to prior sanctions issued by the U.S. Department of Agriculture for use as sources of...

  18. Relationship between potassium intake and radiocesium retention in the reindeer

    International Nuclear Information System (INIS)

    Holleman, D.F.; Luick, J.R.


    The effect of dietary potassium on radiocesium retention was studied in reindeer fed winter diets of lichens. Potassium added to the diet markedly decreased radiocesium retention; this suggests that seasonal changes in cesium retention observed earlier in reindeer might be caused largely by nutritional factors. Data indicate that a 20-fold increase in dietary potassium results in a 2-fold decrease in radiocesium retention

  19. Multiwall carbon nanotube Josephson junctions with niobium contacts

    Energy Technology Data Exchange (ETDEWEB)

    Pallecchi, Emiliano


    The main goal of this thesis is the investigation of dissipationless supercurrent in multiwall carbon nanotubes embedded in a controlled environment. The experimental observation of a dissipationless supercurrent in gated carbon nanotubes remains challenging because of its extreme sensitivity to the environment and to noise fluctuations. We address these issues by choosing niobium as a superconductor and by designing an optimized on chip electromagnetic environment. The environment is meant to reduce the suppression of the supercurrent and allows to disentangle the effects of thermal fluctuations from the intrinsic behavior of the junction. This is crucial for the extraction of the value critical current from the measured data. When the transparency of the contacts is high enough we observed a fully developed supercurrent and we found that it depends on the gate voltage in a resonant manner. In average the critical current increases when the gate is tuned more negative, reflecting the increase of the transparency of the contacts, while the resonant behavior is due to quantum interference effects. We measured the temperature dependence of the switching current and we analyzed the data with an extended RCSJ model that allow to extract the critical current from the experimental data. The measured critical currents are very high with respect to previous reports on gated devices. At positive gate voltage the contacts transparency is lowered and Coulomb blockade is observed. This allows to use Coulomb blockade measurements to further characterize the nanotube and to study the physics of a quantum dot coupled to superconducting leads. The last part of this thesis is dedicated to the measurements of a carbon nanotube Josephson junction in the Coulomb blockade regime. (orig.)

  20. Multiwall carbon nanotube Josephson junctions with niobium contacts

    International Nuclear Information System (INIS)

    Pallecchi, Emiliano


    The main goal of this thesis is the investigation of dissipationless supercurrent in multiwall carbon nanotubes embedded in a controlled environment. The experimental observation of a dissipationless supercurrent in gated carbon nanotubes remains challenging because of its extreme sensitivity to the environment and to noise fluctuations. We address these issues by choosing niobium as a superconductor and by designing an optimized on chip electromagnetic environment. The environment is meant to reduce the suppression of the supercurrent and allows to disentangle the effects of thermal fluctuations from the intrinsic behavior of the junction. This is crucial for the extraction of the value critical current from the measured data. When the transparency of the contacts is high enough we observed a fully developed supercurrent and we found that it depends on the gate voltage in a resonant manner. In average the critical current increases when the gate is tuned more negative, reflecting the increase of the transparency of the contacts, while the resonant behavior is due to quantum interference effects. We measured the temperature dependence of the switching current and we analyzed the data with an extended RCSJ model that allow to extract the critical current from the experimental data. The measured critical currents are very high with respect to previous reports on gated devices. At positive gate voltage the contacts transparency is lowered and Coulomb blockade is observed. This allows to use Coulomb blockade measurements to further characterize the nanotube and to study the physics of a quantum dot coupled to superconducting leads. The last part of this thesis is dedicated to the measurements of a carbon nanotube Josephson junction in the Coulomb blockade regime. (orig.)

  1. Theoretical properties of carbon nanotubes

    International Nuclear Information System (INIS)

    Palser, A.H.


    Carbon nanotubes are invariably terminated with hemi-fullerene caps. In order to investigate the effect of these caps on the electronic structure, a method is developed to enumerate every hemi-fullerene cap which is commensurate with a given nanotube body. This algorithm is then applied to nanotubes for which I + m ≤ 25. The results of this algorithm are then used to study the effects of caps with different symmetries on the electronic structure of metallic and semi-conducting nanotubes within the Hueckel model. It is found that caps can cause localised and resonance states, although the likelihood of localised states occurring in capped metallic nanotubes is shown to be small. In addition, caps induce a non-uniform charge distribution, in which negative charge tends to accumulate on pentagon vertices. The thesis ends by describing two new density matrix methods for performing linear-scaling electronic-structure calculations within the independent electron approximation. Example calculations demonstrate that these methods provide efficient and robust ways of performing linear-scaling calculations, either grand canonically (at a fixed chemical potential) or canonically (at a fixed electron count). (author)

  2. EDITORIAL: Focus on Carbon Nanotubes (United States)


    The study of carbon nanotubes, since their discovery by Iijima in 1991, has become a full research field with significant contributions from all areas of research in solid-state and molecular physics and also from chemistry. This Focus Issue in New Journal of Physics reflects this active research, and presents articles detailing significant advances in the production of carbon nanotubes, the study of their mechanical and vibrational properties, electronic properties and optical transitions, and electrical and transport properties. Fundamental research, both theoretical and experimental, represents part of this progress. The potential applications of nanotubes will rely on the progress made in understanding their fundamental physics and chemistry, as presented here. We believe this Focus Issue will be an excellent guide for both beginners and experts in the research field of carbon nanotubes. It has been a great pleasure to edit the many excellent contributions from Europe, Japan, and the US, as well from a number of other countries, and to witness the remarkable effort put into the manuscripts by the contributors. We thank all the authors and referees involved in the process. In particular, we would like to express our gratitude to Alexander Bradshaw, who invited us put together this Focus Issue, and to Tim Smith and the New Journal of Physics staff for their extremely efficient handling of the manuscripts. Focus on Carbon Nanotubes Contents Transport theory of carbon nanotube Y junctions R Egger, B Trauzettel, S Chen and F Siano The tubular conical helix of graphitic boron nitride F F Xu, Y Bando and D Golberg Formation pathways for single-wall carbon nanotube multiterminal junctions Inna Ponomareva, Leonid A Chernozatonskii, Antonis N Andriotis and Madhu Menon Synthesis and manipulation of carbon nanotubes J W Seo, E Couteau, P Umek, K Hernadi, P Marcoux, B Lukic, Cs Mikó, M Milas, R Gaál and L Forró Transitional behaviour in the transformation from active end

  3. Energy conversion efficiency in nanotube optoelectronics.

    Energy Technology Data Exchange (ETDEWEB)

    Leonard, Francois Leonard; Stewart, Derek A.


    We present theoretical performance estimates for nanotube optoelectronic devices under bias. Current-voltage characteristics of illuminated nanotube p-n junctions are calculated using a self-consistent nonequilibrium Green's function approach. Energy conversion rates reaching tens of percent are predicted for incident photon energies near the band gap energy. In addition, the energy conversion rate increases as the diameter of the nanotube is reduced, even though the quantum efficiency shows little dependence on nanotube radius. These results indicate that the quantum efficiency is not a limiting factor for use of nanotubes in optoelectronics.

  4. Pressure suppression device

    International Nuclear Information System (INIS)

    Ichiki, Tadaharu; Funahashi, Toshihiro.


    Purpose: To provide a structure which permits the absorption of shocks and vibratory load produced on the floor of a pressure suppression chamber due to nitrogen gas or the like discharged into pool water in the pressure suppression chamber at the time of a loss-of-coolant accident. Constitution: A pressure suppression chamber accommodating pool water is comprised of a bottom wall and side walls constructed of concrete on the inner side of a liner. By providing concrete on the bottom surface and side wall surfaces of a pressure suppression chamber, it is possible to prevent non-condensing gas and steam exhausted from the vent duct and exhaust duct of a main vapor escapement safety valve exhaust duct from exerting impact forces and vibratory forces upon the bottom and side surfaces of the pressure suppression chamber. (Horiuchi, T.)

  5. Effects of cisplatin on potassium currents in CT26 cells

    Directory of Open Access Journals (Sweden)

    Naveen Sharma


    Conclusion: Potassium currents were detected in CT26 cells and the currents were reduced by the application of tetraethylammonium (TEA chloride, iberiotoxin, a big conductance calcium-activated potassium channel blocker and barium. The potassium currents were enhanced to 192< by the application of cisplatin (0.5 mM. Moreover, the increase of potassium currents by cisplatin was further inhibited by the application of TEA confirming the action of cisplatin on potassium channels. In addition, relative current induced by cisplatin in CT26 cells was bit larger than in normal IEC-6 cells.

  6. All carbon nanotubes are not created equal

    International Nuclear Information System (INIS)

    Geohegan, David B.; Puretzky, Alexander A.; Rouleau, Christopher M.


    This chapter presents the various factors that enter into consideration when choosing the source of carbon nanotubes for a specific application. Carbon nanotubes are giant molecules made of pure carbon. They have captured the imagination of the scientific community by the unique structure that provides superior physical, chemical, and electrical properties. However, a surprisingly wide disparity exists between the intrinsic properties determined under ideal conditions and the properties that carbon nanotubes exhibit in real world situations. The lack of uniformity in carbon nanotube properties is likely to be the main obstacle holding back the development of carbon nanotube applications. This tutorial addresses the nonuniformity of carbon nanotube properties from the synthesis standpoint. This synthesis-related nonuniformity is on top of the intrinsic chirality distribution that gives the ∼1:2 ratio of metallic to semiconducting nanotubes. From the standpoint of carbon bonding chemistry the variation in the quality and reproducibility of carbon nanotube materials is not unexpected. It is an intrinsic feature that is related to the metastability of carbon structures. The extent to which this effect is manifested in carbon nanotube formation is governed by the type and the kinetics of the carbon nanotube synthesis reaction. Addressing this variation is critical if nanotubes are to live up to the potential already demonstrated by their phenomenal physical properties.

  7. Multistability in a neuron model with extracellular potassium dynamics (United States)

    Wu, Xing-Xing; Shuai, J. W.


    Experiments show a primary role of extracellular potassium concentrations in neuronal hyperexcitability and in the generation of epileptiform bursting and depolarization blocks without synaptic mechanisms. We adopt a physiologically relevant hippocampal CA1 neuron model in a zero-calcium condition to better understand the function of extracellular potassium in neuronal seizurelike activities. The model neuron is surrounded by interstitial space in which potassium ions are able to accumulate. Potassium currents, Na+-K+ pumps, glial buffering, and ion diffusion are regulatory mechanisms of extracellular potassium. We also consider a reduced model with a fixed potassium concentration. The bifurcation structure and spiking frequency of the two models are studied. We show that, besides hyperexcitability and bursting pattern modulation, the potassium dynamics can induce not only bistability but also tristability of different firing patterns. Our results reveal the emergence of the complex behavior of multistability due to the dynamical [K+]o modulation on neuronal activities.

  8. Potassium tetracyanidoaurate(III monohydrate: a redetermination

    Directory of Open Access Journals (Sweden)

    Nobuyuki Matsushita


    Full Text Available The structure of the title metal complex salt, K[Au(CN4]·H2O, has been redetermined using X-ray diffraction data at 173 K in order to improve the precision. The previous determination was based on neutron diffraction data [Bertinotti & Bertinotti (1970. Acta Cryst. B26, 422–428]. The title compound crystallizes in the space group P212121 with one potassium cation, one [Au(CN4]− anion and one water molecule in the asymmetric unit. The AuIII atom lies on a general position and has an almost square-planar coordination sphere defined by four cyanide ligands. Interactions between the potassium cation and N atoms of the complex anion, as well as O—H...N hydrogen bonds, lead to the formation of a three-dimensional framework structure.

  9. Mechanics of carbon nanotube scission under sonication. (United States)

    Stegen, J


    As-produced carbon nanotubes come in bundles that must be exfoliated for practical applications in nanocomposites. Sonication not only causes the exfoliation of nanotube bundles but also unwanted scission. An understanding of how precisely sonication induces the scission and exfoliation of nanotubes will help maximising the degree of exfoliation while minimising scission. We present a theoretical study of the mechanics of carbon nanotube scission under sonicaton, based on the accepted view that it is caused by strong gradients in the fluid velocity near a transiently collapsing bubble. We calculate the length-dependent scission rate by taking the actual movement of the nanotube during the collapse of a bubble into account, allowing for the prediction of the temporal evolution of the length distribution of the nanotubes. We show that the dependence of the scission rate on the sonication settings and the nanotube properties results in non-universal, experiment-dependent scission kinetics potentially explaining the variety in experimentally observed scission kinetics. The non-universality arises from the dependence of the maximum strain rate of the fluid experienced by a nanotube on its length. The maximum strain rate that a nanotube experiences increases with decreasing distance to the bubble. As short nanotubes are dragged along more easily by the fluid flow they experience a higher maximum strain rate than longer nanotubes. This dependence of the maximum strain rate on nanotube length affects the scaling of tensile strength with terminal length. We find that the terminal length scales with tensile strength to the power of 1/1.16 instead of with an exponent of 1/2 as found when nanotube motion is neglected. Finally, we show that the mechanism we propose responsible for scission can also explain the exfoliation of carbon nanotube bundles.

  10. [About the history chemistry and potassium iodide]. (United States)

    Fournier, Josette


    Louis Melsen was born at Louvain, he spent four years in Paris, working in Dumas's laboratory. Four letters from Melsens to Chevreul, since 1951 to 1880, are commented on. Two letters relate to Van Helmont and common interest of the two scientists in history of sciences. The others recall Melsens's proposal that potassium iodide can cure and prevent lead and mercury poisoning, and Chevreul's researches about colours seeing.

  11. CMOS Integrated Carbon Nanotube Sensor

    International Nuclear Information System (INIS)

    Perez, M. S.; Lerner, B.; Boselli, A.; Lamagna, A.; Obregon, P. D. Pareja; Julian, P. M.; Mandolesi, P. S.; Buffa, F. A.


    Recently carbon nanotubes (CNTs) have been gaining their importance as sensors for gases, temperature and chemicals. Advances in fabrication processes simplify the formation of CNT sensor on silicon substrate. We have integrated single wall carbon nanotubes (SWCNTs) with complementary metal oxide semiconductor process (CMOS) to produce a chip sensor system. The sensor prototype was designed and fabricated using a 0.30 um CMOS process. The main advantage is that the device has a voltage amplifier so the electrical measure can be taken and amplified inside the sensor. When the conductance of the SWCNTs varies in response to media changes, this is observed as a variation in the output tension accordingly.

  12. A novel potassium channel in photosynthetic cyanobacteria.

    Directory of Open Access Journals (Sweden)

    Manuela Zanetti

    Full Text Available Elucidation of the structure-function relationship of a small number of prokaryotic ion channels characterized so far greatly contributed to our knowledge on basic mechanisms of ion conduction. We identified a new potassium channel (SynK in the genome of the cyanobacterium Synechocystis sp. PCC6803, a photosynthetic model organism. SynK, when expressed in a K(+-uptake-system deficient E. coli strain, was able to recover growth of these organisms. The protein functions as a potassium selective ion channel when expressed in Chinese hamster ovary cells. The location of SynK in cyanobacteria in both thylakoid and plasmamembranes was revealed by immunogold electron microscopy and Western blotting of isolated membrane fractions. SynK seems to be conserved during evolution, giving rise to a TPK (two-pore K(+ channel family member which is shown here to be located in the thylakoid membrane of Arabidopsis. Our work characterizes a novel cyanobacterial potassium channel and indicates the molecular nature of the first higher plant thylakoid cation channel, opening the way to functional studies.

  13. Carbon nanotubes and methods of making carbon nanotubes

    KAUST Repository

    Basset, Jean-Marie


    Embodiments of the present disclosure provide for methods that can be used to produce carbon nanotubes (hereinafter CNT) having an inner diameter about 5-55 nm, methods of tuning the inner diameter of CNTs (e.g., by adjusting reaction pressure), CNTs having an inner diameter of greater than 20 nm or more, and the like.

  14. Modified carbon nanotubes and methods of forming carbon nanotubes (United States)

    Heintz, Amy M.; Risser, Steven; Elhard, Joel D.; Moore, Bryon P.; Liu, Tao; Vijayendran, Bhima R.


    In this invention, processes which can be used to achieve stable doped carbon nanotubes are disclosed. Preferred CNT structures and morphologies for achieving maximum doping effects are also described. Dopant formulations and methods for achieving doping of a broad distribution of tube types are also described.

  15. Electroluminescence et radiation thermique dans les nanotubes de carbone (United States)

    Adam, Elyse

    We present here a spectroscopic study of the light emission properties of different nanotube devices with the aim to clarify the different mechanisms leading to the light emission. The first study consists of taking measurements from a thick (˜ 450 nm) macroscopic suspended carbon nanotube film connected between two electrodes. A significant increase of the temperature is expected when voltage is applied since thermal dissipation by the substrate is suppressed for this configuration. In imaging mode, we observed that infrared light is emitted from the entire area of the film instead of being localized. This observation demonstrates that the light emission arise from thermal emission. Spectra measured on this device all present a smooth response, characteristic of that of a blackbody. As expected for a pure thermal source, the results fit well the Planck formula. Because the Planck formula is temperature dependant, it became possible to extract a lower limit of the temperature of the film as a function of voltage. The temperature increases more or less from 350K to 600K when the voltage increases from 0.1V to 1.6V. The second study is made using a sub-monolayer network of carbon nanotubes interconnected together to form a semiconducting layer. The large number of tube-tube junctions in the networks limits the current and prevents the temperature to rise significantly at higher bias. The intimate contact between the network and the substrate also prevent the temperature of the film to increase significantly due to a good thermalizaton. Hence, electroluminescence from excitonic recombination is expected to be dominant over heat radiation for this type of devices. First, spatial resolution measurements on long channel network devices shows that the light-emitting zone is always located near the minority charge injector contact. This result demonstrates that light emission arises from electroluminescence in network from a bipolar current. Thermal emission can therefore

  16. Menstrual suppression for adolescents. (United States)

    Altshuler, Anna Lea; Hillard, Paula J Adams


    The purpose of this review is to highlight the recent literature and emerging data describing clinical situations in which menstrual suppression may improve symptoms and quality of life for adolescents. A variety of conditions occurring frequently in adolescents and young adults, including heavy menstrual bleeding, and dysmenorrhea as well as gynecologic conditions such as endometriosis and pelvic pain, can safely be improved or alleviated with appropriate menstrual management. Recent publications have highlighted the efficacy and benefit of extended cycle or continuous combined oral contraceptives, the levonorgestrel intrauterine device, and progestin therapies for a variety of medical conditions. This review places menstrual suppression in an historical context, summarizes methods of hormonal therapy that can suppress menses, and reviews clinical conditions for which menstrual suppression may be helpful.

  17. Cryogenic Acoustic Suppression Testing (United States)

    National Aeronautics and Space Administration — A proof-of-concept method utilizing a cryogenic fluid for acoustic suppression in rocket engine testing environments will be demonstrated. It is hypothesized that...

  18. Race, Serum Potassium, and Associations With ESRD and Mortality. (United States)

    Chen, Yan; Sang, Yingying; Ballew, Shoshana H; Tin, Adrienne; Chang, Alex R; Matsushita, Kunihiro; Coresh, Josef; Kalantar-Zadeh, Kamyar; Molnar, Miklos Z; Grams, Morgan E


    Recent studies suggest that potassium levels may differ by race. The basis for these differences and whether associations between potassium levels and adverse outcomes differ by race are unknown. Observational study. Associations between race and potassium level and the interaction of race and potassium level with outcomes were investigated in the Racial and Cardiovascular Risk Anomalies in Chronic Kidney Disease (RCAV) Study, a cohort of US veterans (N=2,662,462). Associations between African ancestry and potassium level were investigated in African Americans in the Atherosclerosis Risk in Communities (ARIC) Study (N=3,450). Race (African American vs non-African American and percent African ancestry) for cross-sectional analysis; serum potassium level for longitudinal analysis. Potassium level for cross-sectional analysis; mortality and end-stage renal disease for longitudinal analysis. The RCAV cohort was 18% African American (N=470,985). Potassium levels on average were 0.162mmol/L lower in African Americans compared with non-African Americans, with differences persisting after adjustment for demographics, comorbid conditions, and potassium-altering medication use. In the ARIC Study, higher African ancestry was related to lower potassium levels (-0.027mmol/L per each 10% African ancestry). In both race groups, higher and lower potassium levels were associated with mortality. Compared to potassium level of 4.2mmol/L, mortality risk associated with lower potassium levels was lower in African Americans versus non-African Americans, whereas mortality risk associated with higher levels was slightly greater. Risk relationships between potassium and end-stage renal disease were weaker, with no difference by race. No data for potassium intake. African Americans had slightly lower serum potassium levels than non-African Americans. Consistent associations between potassium levels and percent African ancestry may suggest a genetic component to these differences. Higher and

  19. Emerging Carbon Nanotube Electronic Circuits, Modeling, and Performance


    Xu, Yao; Srivastava, Ashok; Sharma, Ashwani K.


    Current transport and dynamic models of carbon nanotube field-effect transistors are presented. A model of single-walled carbon nanotube as interconnect is also presented and extended in modeling of single-walled carbon nanotube bundles. These models are applied in studying the performances of circuits such as the complementary carbon nanotube inverter pair and carbon nanotube as interconnect. Cadence/Spectre simulations show that carbon nanotube field-effect transistor circuits can operate a...

  20. Sodium fire suppression

    International Nuclear Information System (INIS)

    Malet, J.C.


    Ignition and combustion studies have provided valuable data and guidelines for sodium fire suppression research. The primary necessity is to isolate the oxidant from the fuel, rather than to attempt to cool the sodium below its ignition temperature. Work along these lines has led to the development of smothering tank systems and a dry extinguishing powder. Based on the results obtained, the implementation of these techniques is discussed with regard to sodium fire suppression in the Super-Phenix reactor. (author)

  1. Effects of extracellular potassium diffusion on electrically coupled neuron networks (United States)

    Wu, Xing-Xing; Shuai, Jianwei


    Potassium accumulation and diffusion during neuronal epileptiform activity have been observed experimentally, and potassium lateral diffusion has been suggested to play an important role in nonsynaptic neuron networks. We adopt a hippocampal CA1 pyramidal neuron network in a zero-calcium condition to better understand the influence of extracellular potassium dynamics on the stimulus-induced activity. The potassium concentration in the interstitial space for each neuron is regulated by potassium currents, Na+-K+ pumps, glial buffering, and ion diffusion. In addition to potassium diffusion, nearby neurons are also coupled through gap junctions. Our results reveal that the latency of the first spike responding to stimulus monotonically decreases with increasing gap-junction conductance but is insensitive to potassium diffusive coupling. The duration of network oscillations shows a bell-like shape with increasing potassium diffusive coupling at weak gap-junction coupling. For modest electrical coupling, there is an optimal K+ diffusion strength, at which the flow of potassium ions among the network neurons appropriately modulates interstitial potassium concentrations in a degree that provides the most favorable environment for the generation and continuance of the action potential waves in the network.

  2. Proapoptotic Role of Potassium Ions in Liver Cells

    Directory of Open Access Journals (Sweden)

    Zhenglin Xia


    Full Text Available Potassium channels are transmembrane proteins that selectively promote the infiltration of potassium ions. The significance of these channels for tumor biology has become obvious. However, the effects of potassium ions on the tumor or normal cells have seldom been studied. To address this problem, we studied the biological effects of L02 and HepG2 cells with ectogenous potassium ions. Cell proliferation, cell cycle, and apoptosis rate were analyzed. Our results indicated that potassium ions inhibited proliferation of L02 and HepG2 cells and promoted their apoptosis. Potassium ions induced apoptosis through regulating Bcl-2 family members and depolarized the mitochondrial membrane, especially for HepG2 cell. These biological effects were associated with channel protein HERG. By facilitating expression of channel protein HERG, potassium ions may prevent it from being shunted to procancerous pathways by inducing apoptosis. These results demonstrated that potassium ions may be a key regulator of liver cell function. Thus, our findings suggest that potassium ions could inhibit tumorigenesis through inducing apoptosis of hepatoma cells by upregulating potassium ions transport channel proteins HERG and VDAC1.

  3. Nickel oxide nanotube synthesis using multiwalled carbon nanotubes as sacrificial templates for supercapacitor application. (United States)

    Abdalla, Ahmed M; Sahu, Rakesh P; Wallar, Cameron J; Chen, Ri; Zhitomirsky, Igor; Puri, Ishwar K


    A novel approach for the fabrication of nickel oxide nanotubes based on multiwalled carbon nanotubes as a sacrificial template is described. Electroless deposition is employed to deposit nickel onto carbon nanotubes. The subsequent annealing of the product in the presence of air oxidizes nickel to nickel oxide, and carbon is released as gaseous carbon dioxide, leaving behind nickel oxide nanotubes. Electron microscopy and elemental mapping confirm the formation of nickel oxide nanotubes. New chelating polyelectrolytes are used as dispersing agents to achieve high colloidal stability for both the nickel-coated carbon nanotubes and the nickel oxide nanotubes. A gravimetric specific capacitance of 245.3 F g -1 and  an areal capacitance of 3.28 F cm -2 at a scan rate of 2 mV s -1 is achieved, with an electrode fabricated using nickel oxide nanotubes as the active element with a mass loading of 24.1 mg cm -2 .

  4. Effects of cisplatin on potassium currents in CT26 cells. (United States)

    Sharma, Naveen; Bhattarai, Janardhan Prasad; Kim, Sun Young; Hwang, Pyoung Han; Kim, Min Sun; Han, Seong Kyu


    Cisplatin, a platinum-based drug, is an important weapon against many types of cancer. It is well-known that cisplatin induces apoptosis. Potassium channel plays very important role in several signaling pathways. To investigate the possibility that potassium channels also have a role in the cellular response to cisplatin, we examined the effect of cisplatin on the activity of potassium channels on CT26 cell, the colon carcinoma cell line. The cells were cultured in DMEM, supplemented with 10experiment with more than two groups. Potassium currents were detected in CT26 cells and the currents were reduced by the application of tetraethylammonium (TEA) chloride, iberiotoxin, a big conductance calcium-activated potassium channel blocker and barium. The potassium currents were enhanced to 192cisplatin (0.5 mM). Moreover, the increase of potassium currents by cisplatin was further inhibited by the application of TEA confirming the action of cisplatin on potassium channels. In addition, relative current induced by cisplatin in CT26 cells was bit larger than in normal IEC-6 cells. Potassium currents were detected in CT26 cells and the currents were reduced by the application of tetraethylammonium (TEA) chloride, iberiotoxin, a big conductance calcium-activated potassium channel blocker and barium. The potassium currents were enhanced to 192cisplatin (0.5 mM). Moreover, the increase of potassium currents by cisplatin was further inhibited by the application of TEA confirming the action of cisplatin on potassium channels. In addition, relative current induced by cisplatin in CT26 cells was bit larger than in normal IEC-6 cells.

  5. Quantum transport in carbon nanotubes

    NARCIS (Netherlands)

    Laird, E.A.; Kuemmeth, F.; Steele, G.A.; Grove-Rasmussen, K.; Nygard, J.; Flensberg, K.; Kouwenhoven, L.P.


    Carbon nanotubes are a versatile material in which many aspects of condensed matter physics come together. Recent discoveries have uncovered new phenomena that completely change our understanding of transport in these devices, especially the role of the spin and valley degrees of freedom. This

  6. Carbon nanotube-chalcogenide composite

    Czech Academy of Sciences Publication Activity Database

    Stehlík, Š.; Orava, J.; Kohoutek, T.; Wágner, T.; Frumar, M.; Zima, Vítězslav; Hara, T.; Matsui, Y.; Ueda, K.; Pumera, M.


    Roč. 183, č. 1 (2010), s. 144-149 ISSN 0022-4596 R&D Projects: GA ČR GA203/08/0208 Institutional research plan: CEZ:AV0Z40500505 Keywords : carbon nanotube s * chalcogenide glasses * composites Subject RIV: CA - Inorganic Chemistry Impact factor: 2.261, year: 2010

  7. Platinum-carbon nanotube interaction

    NARCIS (Netherlands)

    Bittencourt, C.; Hecq, M.; Felten, A.; Pireaux, J. J.; Ghijsen, J.; Felicissimo, M. P.; Rudolf, P.; Drube, W.; Ke, X.; Van Tendeloo, G.


    The interaction between evaporated Pt and pristine or oxygen-plasma-treated multiwall carbon nanotubes (CNTs) is investigated. Pt is found to nucleate at defect sites, whether initially present or introduced by oxygen plasma treatment. The plasma treatment induces a uniform dispersion of Pt

  8. Method for synthesizing carbon nanotubes (United States)

    Fan, Hongyou


    A method for preparing a precursor solution for synthesis of carbon nanomaterials, where a polar solvent is added to at least one block copolymer and at least one carbohydrate compound, and the precursor solution is processed using a self-assembly process and subsequent heating to form nanoporous carbon films, porous carbon nanotubes, and porous carbon nanoparticles.

  9. Polypyrrole nanotubes: mechanism of formation

    Czech Academy of Sciences Publication Activity Database

    Kopecká, J.; Kopecký, D.; Vrňata, M.; Fitl, P.; Stejskal, Jaroslav; Trchová, Miroslava; Bober, Patrycja; Morávková, Zuzana; Prokeš, J.; Sapurina, I.


    Roč. 4, č. 4 (2014), s. 1551-1558 ISSN 2046-2069 R&D Projects: GA ČR(CZ) GA13-08944S Institutional support: RVO:61389013 Keywords : conducting polymer * polypyrrole * nanotubes Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.840, year: 2014

  10. Synthesis of PbI(2) single-layered inorganic nanotubes encapsulated within carbon nanotubes. (United States)

    Cabana, Laura; Ballesteros, Belén; Batista, Eudar; Magén, César; Arenal, Raúl; Oró-Solé, Judith; Rurali, Riccardo; Tobias, Gerard


    The template assisted growth of single-layered inorganic nanotubes is reported. Single-crystalline lead iodide single-layered nanotubes have been prepared using the inner cavities of carbon nanotubes as hosting templates. The diameter of the resulting inorganic nanotubes is merely dependent on the diameter of the host. This facile method is highly versatile opening up new horizons in the preparation of single-layered nanostructures. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Selective suppression of the slow-inactivating potassium currents by nootropics in molluscan neurons. (United States)

    Bukanova, Julia V; Solntseva, Elena I; Skrebitsky, Vladimir G


    The role of the voltage-gated K+ channels in the effect of some nootropics was investigated. Earlier, the multiple effect of high concentrations of two nootropics, piracetam and its peptide analogue GVS-111 [Seredenin et al. (1995), US Patent No. 5,439,930], on Ca2+ and K+ currents of molluscan neurons was shown [Solntseva et al. (1997), General Pharmacology 29, 85-89]. In the present work, we describe the selective effect of low concentrations of these nootropics as well as vinpocetine on certain types of K+ current. The experiments were performed on isolated neurons of the land snail Helix pomatia using a two-microelectrode voltage-clamp method. The inward voltage-gated Ca2+ current (ICa) and three subtypes of the outward voltage-gated K+ current were recorded: Ca2+-dependent K+ current (IK(Ca)), delayed rectifying current (IKD), and fast-inactivating K+ current (IA). It has been found that I Ca was not changed in the presence of 30 microM vinpocetine, 100 microM piracetam or 10 nM GVS-111, while slow-inactivating, TEA-sensitive IK(Ca) and IKD were inhibited (IK(Ca) more strongly than IKD). In contrast, the fast-inactivating, 4-AP-sensitive K+ current (IA) was not diminished by low concentrations of piracetam and GVS-111, while vinpocetine even augmented it. A possible role of slow-inactivating subtypes of the K+ channels in the development of different forms of dementia is discussed.

  12. Facile Synthesis of Ternary Boron Carbonitride Nanotubes

    Directory of Open Access Journals (Sweden)

    Luo Lijie


    Full Text Available Abstract In this study, a novel and facile approach for the synthesis of ternary boron carbonitride (B–C–N nanotubes was reported. Growth occurred by heating simple starting materials of boron powder, zinc oxide powder, and ethanol absolute at 1150 °C under a mixture gas flow of nitrogen and hydrogen. As substrate, commercial stainless steel foil with a typical thickness of 0.05 mm played an additional role of catalyst during the growth of nanotubes. The nanotubes were characterized by SEM, TEM, EDX, and EELS. The results indicate that the synthesized B–C–N nanotubes exhibit a bamboo-like morphology and B, C, and N elements are homogeneously distributed in the nanotubes. A catalyzed vapor–liquid–solid (VLS mechanism was proposed for the growth of the nanotubes.

  13. Telescopic nanotube device for hot nanolithography (United States)

    Popescu, Adrian; Woods, Lilia M


    A device for maintaining a constant tip-surface distance for producing nanolithography patterns on a surface using a telescopic nanotube for hot nanolithography. An outer nanotube is attached to an AFM cantilever opposite a support end. An inner nanotube is telescopically disposed within the outer nanotube. The tip of the inner nanotube is heated to a sufficiently high temperature and brought in the vicinity of the surface. Heat is transmitted to the surface for thermal imprinting. Because the inner tube moves telescopically along the outer nanotube axis, a tip-surface distance is maintained constant due to the vdW force interaction, which in turn eliminates the need of an active feedback loop.

  14. Transport diffusion in deformed carbon nanotubes (United States)

    Feng, Jiamei; Chen, Peirong; Zheng, Dongqin; Zhong, Weirong


    Using non-equilibrium molecular dynamics and Monte Carlo methods, we have studied the transport diffusion of gas in deformed carbon nanotubes. Perfect carbon nanotube and various deformed carbon nanotubes are modeled as transport channels. It is found that the transport diffusion coefficient of gas does not change in twisted carbon nanotubes, but changes in XY-distortion, Z-distortion and local defect carbon nanotubes comparing with that of the perfect carbon nanotube. Furthermore, the change of transport diffusion coefficient is found to be associated with the deformation factor. The relationship between transport diffusion coefficient and temperature is also discussed in this paper. Our results may contribute to understanding the mechanism of molecular transport in nano-channel.

  15. Dielectrophoretic assembly of carbon nanotube devices

    DEFF Research Database (Denmark)

    Dimaki, Maria

    The purpose of this project has been to assemble single-walled carbon nanotubes on electrodes at the tip of a biocompatible cantilever and use these for chemical species sensing in air and liquid, for example in order to measure the local activity from ion channels in the cell membrane....... The electrical resistance of carbon nanotubes has been shown to be extremely sensitive to gas molecules. Dielectrophoresis is a method capable of quickly attracting nanotubes on microelectrodes by using an electric field, thus enabling nanotube integration in microsystems. Dielectrophoresis offers also...... the potential of distinguishing between nanotubes of different electrical properties, which is very important for the optimisation of the properties of the carbon nanotube sensors. Various cantilever and planar structures were designed, fabricated and tested both with multi-walled and single-walled carbon...

  16. Sound velocity in potassium hydroxide aqueous solution

    International Nuclear Information System (INIS)

    Tsapuryan, Kh.D.; Aleksandrov, A.A.; Kochetkov, A.I.


    Measurements of ultrasonic velocities in potassium hydroxide aqueous solutions are carried out within the frames of studies on improvement of water chemistry in NPP cooling systems. Method of echo pulses superposition with acoustic path length of 41.447 mm is used for measurements. The measurements are performed at 2.6 MHz frequency. Complex temperature dependence of ultrasonic velocity is determined. Ultrasonic velocity dependence on pressure is close to linear one. The formula for calculation of thermodynamic properties of the studied solutions on the basis of experimental data obtained is proposed

  17. Terahertz birefringence of potassium niobate crystals (United States)

    Antsygin, V. D.; Mamrashev, A. A.; Nikolaev, N. A.


    We present terahertz optical properties (refractive indices and absorption coefficients) of potassium niobate crystals measured by time-domain spectroscopy in the range of 0.2-2.0 THz. We observe average refractive indices nx = 5.25, ny = 4.8, nz = 5.9 for corresponding optical axes X, Y, Z with the large birefringence of Δn = nz - ny = 1.1. We report rising absorption coefficient at higher frequencies (α ∼ 50 cm-1 at 1 THz for all three axes) while the dichroism is not pronounced. Somewhat higher absorption compared to the previous results could be attributed to some polydomain structure remaining in the crystal.

  18. Cefadroxil iodometric determination by potassium hydrogenperoxomonosulfate reaction

    Directory of Open Access Journals (Sweden)

    Юлія Юріївна Сердюкова


    Full Text Available Aim. Simple methods of oxidimetric determination of β-lactam antibiotic cefadroxil in pure powder and in capsules, that are based on S-oxidation reactions by potassium hydrogenperoxomonosulphate acid in weak acid medium to S- oxide with following iodometric quantitative determination of the oxydator reagent excess were developed.Materials and methods. A triple potassium salt of caroate acid, 2KHSO5•KHSO4•K2SO4 (commercial «Oxone®» DuPont, production was used as oxidizing agent.Results. By the results of reaction kinetics using iodometric titration it was determined that redox reaction between cefadroxil and potassium hydrogenperoxomonosulfate is quantified and a stoichiometric: 1 mol of cefadroxil is per 1 mol of potassium hydrogen. Quantitative oxidation of Sulfur atom was finished in the time that is less than 1 min. The mean recovery of the main substance in the cefadroxil pure substance was 97.76%, RSD=1.33 % (δ=1.31 %, 1 mL of the standard 0.0200 mol L-1 sodium tiosulphate solution corresponds to 0.003634 g of sodium cefadroxil (C16H17N3O5S which should be 95–102 % in the pure anhydrous substance. The mean recovery of medical preparation “Cefadroxil”, 500 mg is 100.06 %, RSD=0.96 % (δ=1.01 %, which should be 92.5–107.5 %, in anhydrous preparation. The limit detection is С=0.05 mg mL-1. The advantages of the proposed procedure are the ability to assay cefadroxil by the biologically active part of the molecule (alicyclic and tiomethyl sulfur, good recovery and the accuracy of results.Conclusions. The obtained validation data meet the requirements of the State Pharmacopoeia of Ukraine, which indicates the possibility of its introduction in the practice of analytical laboratories analysis, or application during the stepwise control process or manufacturing of drugs quality control during equipment washing

  19. Natural potassium as a teaching material

    International Nuclear Information System (INIS)

    Akatsu, Eiko


    An experience of an educational experiment is presented with results and discussion. It was performed in the introductory course of nuclear energy in the Nuclear Education Center of Japan Atomic Energy Research Institute. Purpose of the experiment is understanding disintegration rate (Bq, radioactivity or λN) through measurement of low radioactivity of natural potassium. It was accomplished through calculation of the radioactivity of a measuring known sample and counting efficiency during measurement. The students in the training course had great variety and most students did not have preliminary knowledge. But they said in the questionnaire having almost understood the experiment; and some students enjoyed it. (author)

  20. Amorphous Carbon-Boron Nitride Nanotube Hybrids (United States)

    Kim, Jae Woo (Inventor); Siochi, Emilie J. (Inventor); Wise, Kristopher E. (Inventor); Lin, Yi (Inventor); Connell, John (Inventor)


    A method for joining or repairing boron nitride nanotubes (BNNTs). In joining BNNTs, the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures. In repairing BNNTs, the damaged site of the nanotube structure is modified with amorphous carbon deposited by controlled electron beam irradiation to form well bonded hybrid a-C/BNNT structures at the damage site.

  1. Method of making carbon nanotube composite materials (United States)

    O'Bryan, Gregory; Skinner, Jack L; Vance, Andrew; Yang, Elaine Lai; Zifer, Thomas


    The present invention is a method of making a composite polymeric material by dissolving a vinyl thermoplastic polymer, un-functionalized carbon nanotubes and hydroxylated carbon nanotubes and optionally additives in a solvent to make a solution and removing at least a portion of the solvent after casting onto a substrate to make thin films. The material has enhanced conductivity properties due to the blending of the un-functionalized and hydroxylated carbon nanotubes.

  2. Ordered metal nanotube arrays fabricated by PVD. (United States)

    Marquez, F; Morant, C; Campo, T; Sanz, J M; Elizalde, E


    In this work we report a simple method to fabricate ordered arrays of metal nanotubes. This method is based on the deposition of a metal by PVD onto an anodized aluminum oxide (AAO) template. The dimensions of the synthesized nanotubes depend both on the AAO template and on the deposited metal. In fact, it is observed that the aspect ratios of the nanotubes clearly depend significantly on the metal, ranging from 0.6 (Fe) to at least 3 (Zr).

  3. Functional Materials based on Carbon Nanotubes


    Jung, Adrian Thomas


    Carbon nanotubes, no matter if they are single-walled or multi-walled, are an integral component in the vastly growing field of nanotechnology. Since their discovery by TEM and the invention of numerous large-scale production techniques, nanotubes are close to making their way into industrial products. Although many properties and modification processes are still under intensive research, the first real-market applications for carbon nanotubes have already been presented. However, if function...

  4. Carbon nanotubes as heat dissipaters in microelectronics

    DEFF Research Database (Denmark)

    Pérez Paz, Alejandro; García-Lastra, Juan María; Markussen, Troels


    We review our recent modelling work of carbon nanotubes as potential candidates for heat dissipation in microelectronics cooling. In the first part, we analyze the impact of nanotube defects on their thermal transport properties. In the second part, we investigate the loss of thermal properties...... of nanotubes in presence of an interface with various substances, including air and water. Comparison with previous works is established whenever is possible....

  5. Effects of cisplatin on potassium currents in CT26 cells


    Naveen Sharma; Janardhan Prasad Bhattarai; Sun Young Kim; Pyoung Han Hwang; Min Sun Kim; Seong Kyu Han


    Aims: Cisplatin, a platinum-based drug, is an important weapon against many types of cancer. It is well-known that cisplatin induces apoptosis. Potassium channel plays very important role in several signaling pathways. To investigate the possibility that potassium channels also have a role in the cellular response to cisplatin, we examined the effect of cisplatin on the activity of potassium channels on CT26 cell, the colon carcinoma cell line. Materials and Methods: The cells were culture...

  6. Modeling removal of accumulated potassium from T-tubules by inward rectifier potassium channels

    NARCIS (Netherlands)

    Wallinga, W.; Vliek, M.; Wienk, E.D.; Alberink, M.J.; Ypey, D.L.; Ypey, D.L.


    The membrane models of Cannon et al. (1993) and Alberink et al. (1995) for mammalian skeletal muscle fibers are based upon Hodgkin-Huxley descriptions of sodium, potassium delayed rectifier and leak conductances and the capacitive current taking into account fast inactivation of sodium channels. Now

  7. Poisoning of vanadia based SCR catalysts by potassium:influence of catalyst composition and potassium mobility

    DEFF Research Database (Denmark)

    Olsen, Brian Kjærgaard; Kügler, Frauke; Jensen, Anker Degn


    exposure temperatures slowdown the deactivation. K2SO4 causes a lower rate of deactivation compared to KCl. This may be related to a faster transfer of potassium from the solid KCl matrix to the catalyst, however, it cannot be ruled out toalso be caused by a significantly larger particle size of the K2SO4...

  8. Enhanced dispersion stability and mobility of carboxyl-functionalized carbon nanotubes in aqueous solutions through strong hydrogen bonds

    International Nuclear Information System (INIS)

    Bahk, Yeon Kyoung; He, Xu; Gitsis, Emmanouil; Kuo, Yu-Ying; Kim, Nayoung; Wang, Jing


    Dispersion of carbon nanotubes has been heavily studied due to its importance for their technical applications, toxic effects, and environmental impacts. Common electrolytes, such as sodium chloride and potassium chloride, promote agglomeration of nanoparticles in aqueous solutions. On the contrary, we discovered that acetic electrolytes enhanced the dispersion of multi-walled carbon nanotubes (MWCNTs) with carboxyl functional group through the strong hydrogen bond, which was confirmed by UV–Vis spectrometry, dispersion observations and aerosolization-quantification method. When concentrations of acetate electrolytes such as ammonium acetate (CH 3 CO 2 NH 4 ) and sodium acetate (CH 3 CO 2 Na) were lower than 0.03 mol per liter, MWCNT suspensions showed better dispersion and had higher mobility in porous media. The effects by the acetic environment are also applicable to other nanoparticles with the carboxyl functional group, which was demonstrated with polystyrene latex particles as an example

  9. Potassium Chloride Versus Voltage Clamp Contractures in Ventricular Muscle (United States)

    Morad, M.; Reeck, S.; Rao, M.


    In frog ventricle, developed tension was markedly larger in response to depolarization caused by a voltage clamp step than to depolarization induced by high concentrations of potassium chloride. Measurement of extracellular potassium activity at the surface and at the depth of muscle during the development of contractures showed that the diffusion of potassium is much slower than the spread of depolarization through the cross section of muscle. These two observations suggest that competition between the depolarizing and the negative inotropic effects of an increase in the extracellular potassium ion concentration may determine the time course and magnitude of contractile tension in heart muscle.

  10. Quantum conductance of carbon nanotube peapods

    International Nuclear Information System (INIS)

    Yoon, Young-Gui; Mazzoni, Mario S.C.; Louie, Steven G.


    We present a first-principles study of the quantum conductance of hybrid nanotube systems consisting of single-walled carbon nanotubes (SWCNTs) encapsulating either an isolated single C60 molecule or a chain of C60 molecules (nanotube peapods). The calculations show a rather weak bonding interaction between the fullerenes and the SWCNTs. The conductance of a (10,10) SWCNT with a single C60 molecule is virtually unaffected at the Fermi level, but exhibits quantized resonant reductions at the molecular levels. The nanotube peapod arrangement gives rise to high density of states for the fullerene highest occupied molecular orbital and lowest unoccupied molecular orbital bands

  11. Study of Carbon Nanotube-Substrate Interaction

    Directory of Open Access Journals (Sweden)

    Jaqueline S. Soares


    Full Text Available Environmental effects are very important in nanoscience and nanotechnology. This work reviews the importance of the substrate in single-wall carbon nanotube properties. Contact with a substrate can modify the nanotube properties, and such interactions have been broadly studied as either a negative aspect or a solution for developing carbon nanotube-based nanotechnologies. This paper discusses both theoretical and experimental studies where the interaction between the carbon nanotubes and the substrate affects the structural, electronic, and vibrational properties of the tubes.

  12. Thermal conductivity of deformed carbon nanotubes (United States)

    Zhong, Wei-Rong; Zhang, Mao-Ping; Zheng, Dong-Qin; Ai, Bao-Quan


    We investigate the thermal conductivity of four types of deformed carbon nanotubes by using the nonequilibrium molecular dynamics method. It is reported that various deformations have different influences on the thermal properties of carbon nanotubes. For bending carbon nanotubes, the thermal conductivity is independent of the bending angle. However, the thermal conductivity increases lightly with xy-distortion and decreases rapidly with z-distortion. The thermal conductivity does not change with the screw ratio before the breaking of carbon nanotubes, but it decreases sharply after the critical screw ratio.

  13. Carbon nanotube coatings as chemical absorbers (United States)

    Tillotson, Thomas M.; Andresen, Brian D.; Alcaraz, Armando


    Airborne or aqueous organic compound collection using carbon nanotubes. Exposure of carbon nanotube-coated disks to controlled atmospheres of chemical warefare (CW)-related compounds provide superior extraction and retention efficiencies compared to commercially available airborne organic compound collectors. For example, the carbon nanotube-coated collectors were four (4) times more efficient toward concentrating dimethylmethyl-phosphonate (DMMP), a CW surrogate, than Carboxen, the optimized carbonized polymer for CW-related vapor collections. In addition to DMMP, the carbon nanotube-coated material possesses high collection efficiencies for the CW-related compounds diisopropylaminoethanol (DIEA), and diisopropylmethylphosphonate (DIMP).

  14. Coulomb drag in multiwall armchair carbon nanotubes

    DEFF Research Database (Denmark)

    Lunde, A.M.; Jauho, Antti-Pekka


    We calculate the transresistivity rho(21) between two concentric armchair nanotubes in a diffusive multiwall carbon nanotube as a function of temperature T and Fermi level epsilon(F). We approximate the tight-binding band structure by two crossing bands with a linear dispersion near the Fermi...... surface. The cylindrical geometry of the nanotubes and the different parities of the Bloch states are accounted for in the evaluation of the effective Coulomb interaction between charges in the concentric nanotubes. We find a broad peak in rho(21) as a function of temperature at roughly T similar to 0.4T...

  15. Pressure suppression device

    International Nuclear Information System (INIS)

    Mizumachi, Wataru; Fukuda, Akira; Kitaguchi, Hidemi; Shimizu, Toshiaki.


    Object: To relieve and absorb impact wave vibrations caused by steam and non-condensed gases releasing into the pressure suppression chamber at the time of an accident. Structure: The reactor container is filled with inert gases. A safety valve attached main steam pipe is provided to permit the excessive steam to escape, the valve being communicated with the pressure suppression chamber through an exhaust pipe. In the pressure suppression chamber, a doughnut-like cylindrical outer wall is filled at its bottom with pool water to condense the high temperature vapor released through the exhaust pipe. A head portion of a vent tube which leads the exhaust pipe is positioned at the top, and a down comer and an exhaust vent tube are locked by means of steady rests. At the bottom is mounted a pressure adsorber device which adsorbs a pressure from the pool water. (Kamimura, M.)

  16. Thyroxin hormone suppression treatment

    International Nuclear Information System (INIS)

    Samuel, A.M.


    One of the important modalities of treatment of thyroid cancer (TC) after surgery is the administration of thyroxin as an adjuvant treatment. The analysis supports the theory that thyroid suppression plays an important role in patient management. 300 μg of thyroxin, as this is an adequate dose for suppression is given. Ideally the dose should be tailored by testing s-TSH levels. However, since a large number of the patients come from out station cities and villages this is impractical. We therefore depend on clinical criteria of hyperthyroid symptoms and adjust the dose. Very few patients need such adjustment

  17. Application of Nanoparticles/Nanowires and Carbon Nanotubes for Breast Cancer Research

    National Research Council Canada - National Science Library

    Panchapakesan, Balaji


    .... Variety of techniques such as fabrication of single wall carbon nanotubes, functionalization of nanotubes with antibodies, interaction of cells with antibodies on nanotube surfaces, and finally cell...

  18. Poly(ethylene oxide) Crystallization in Single Walled Carbon Nanotube Based Nanocomposites: Kinetics and Structural Consequences

    Energy Technology Data Exchange (ETDEWEB)

    T Chatterjee; A Lorenzo; R Krishnamoorti


    The overall isothermal crystallization behavior of poly(ethylene oxide) (PEO) in single walled carbon nanotube (SWNT) based nanocomposites is studied with a focus on growth kinetics and morphological evolution of PEO using differential scanning calorimetry and in-situ small angle x-ray scattering measurements respectively. The characteristic time for crystallization of PEO increases due to the presence of lithium dodecyl sulfate (LDS) stabilized carbon nanotubes. Further, analysis of crystallization data using the Lauritzen-Hoffman regime theory of crystal growth shows the PEO chains stiffen in presence of LDS with an increased energy barrier associated with the nucleation and crystal growth, and the nanotubes further act as a barrier to chain transport or enhance the efficacy of the LDS action. The energy penalty and diffusional barrier to chain transport in the nanocomposites disrupt the crystalline PEO helical conformation. This destabilization leads to preferential growth of local nuclei resulting in formation of thinner crystal lamellae and suggests that the crystallization kinetics is strongly affected by the nucleation and crystal growth events. This study is particularly interesting considering the suppression of the PEO crystallinity in presence of small fraction of Lithium ion based surfactant and carbon nanotubes.

  19. Mechanics of filled carbon nanotubes

    KAUST Repository

    Monteiro, A.O.


    The benefits of filling carbon nanotubes (CNTs) with assorted molecular and crystalline substances have been investigated for the past two decades. Amongst the study of new structural phases, defects, chemical reactions and varied types of host-guest interactions, there is one fundamental characterisation aspect of these systems that continues to be overlooked: the mechanical behaviour of filled CNTs. In contrast to their empty counterparts, the mechanics of filled CNTs is a subject where reports appear far and apart, this despite being key to the application of these materials in technological devices. In the following paragraphs, we review the work that has been carried out up to the present on the mechanics of filled CNTs. The studies discussed range from experimental resonant frequency essays performed within electron microscopes to modelling, via molecular dynamics, of three-point bending of nanotubes filled with gases. (C) 2014 Elsevier B.V. All rights reserved.

  20. Novel "Elements" of Immune Suppression within the Tumor Microenvironment. (United States)

    Gurusamy, Devikala; Clever, David; Eil, Robert; Restifo, Nicholas P


    Adaptive evolution has prompted immune cells to use a wide variety of inhibitory signals, many of which are usurped by tumor cells to evade immune surveillance. Although tumor immunologists often focus on genes and proteins as mediators of immune function, here we highlight two elements from the periodic table-oxygen and potassium-that suppress the immune system in previously unappreciated ways. While both are key to the maintenance of T-cell function and tissue homeostasis, they are exploited by tumors to suppress immuno-surveillance and promote metastatic spread. We discuss the temporal and spatial roles of these elements within the tumor microenvironment and explore possible therapeutic interventions for effective and promising anticancer therapies. Cancer Immunol Res; 5(6); 426-33. ©2017 AACR . ©2017 American Association for Cancer Research.

  1. Carbon Nanotube Field Emission Arrays (United States)


    CVD) and thermal chemical vapor deposition (T-CVD), are developed. The physical properties of the resulting CNTs are analyzed using Raman...MWCNTs) [1]. In the ensuing years the characterization of unique and phenomenal mechanical, electrical, thermal , and chemical properties of CNTs has...rediscovered or introduced carbon nanotubes to the scientific community as a by-product of an electric arc discharge method of synthesizing C60 fullerenes [1

  2. Underwater Acoustic Carbon Nanotube Thermophone (United States)


    electrically connected to the transducer cable. A silicon sealant material is used to for attachment points on the thermophone. BRIEF DESCRIPTION OF...300 degrees Celsius) rated silicon sealant material 62 is used to for attachment points on the thermophone 10. [0030] Advantages and features of...of a cable is soldered to the carbon nanotube material chip at electrodes of the material chip. A high temperature rated silicon sealant is used for attachment points on the thermophone.

  3. Plasma suppression of beamstrahlung

    International Nuclear Information System (INIS)

    Whittum, D.H.; Sessler, A.M.; Stewart, J.J.; Yu, S.S.


    We investigate the use of a plasma at the interaction point of two colliding beams to suppress beamsstrahlung and related phenomena. We derive conditions for good current cancellation via plasma return currents and report on numerical simulations conducted to confirm our analytic results. 10 refs., 5 figs., 4 tabs

  4. Superconducting characteristics of 4-Å carbon nanotube-zeolite composite

    KAUST Repository

    Lortz, Rolf W.


    We have fabricated nanocomposites consisting of 4-A carbon nanotubes embedded in the 0.7-nm pores of aluminophosphate- five (AFI) zeolite that display a superconducting specific heat transition at 15 K. MicroRaman spectra of the samples show strong and spatially uniform radial breathing mode (RBM) signals at 510 cm-1 and 550 cm-1, characteristic of the (4,2) and (5,0) nanotubes, respectively. The specific heat transition is suppressed at >2T, with a temperature dependence characteristic of finite-size effects. Comparison with theory shows the behavior to be consistent with that of a type II BCS superconductor, characterized by a coherence length of 14 ± 2 nm and a magnetic penetration length of 1.5 ± 0.7 μm. Four probe and differential resistance measurements have also indicated a superconducting transition initiating at 15 K, but the magnetoresistance data indicate the superconducting network to be inhomogeneous, with a component being susceptible to magnetic fields below 3 T and other parts capable of withstanding a magnetic field of 5Tor beyond.

  5. Oriented nanotube electrodes for lithium ion batteries and supercapacitors (United States)

    Frank, Arthur J.; Zhu, Kai; Wang, Qing


    An electrode having an oriented array of multiple nanotubes is disclosed. Individual nanotubes have a lengthwise inner pore defined by interior tube walls which extends at least partially through the length of the nanotube. The nanotubes of the array may be oriented according to any identifiable pattern. Also disclosed is a device featuring an electrode and methods of fabrication.

  6. Hydrogen storage in carbon nanotubes. (United States)

    Hirscher, M; Becher, M


    The article gives a comprehensive overview of hydrogen storage in carbon nanostructures, including experimental results and theoretical calculations. Soon after the discovery of carbon nanotubes in 1991, different research groups succeeded in filling carbon nanotubes with some elements, and, therefore, the question arose of filling carbon nanotubes with hydrogen by possibly using new effects such as nano-capillarity. Subsequently, very promising experiments claiming high hydrogen storage capacities in different carbon nanostructures initiated enormous research activity. Hydrogen storage capacities have been reported that exceed the benchmark for automotive application of 6.5 wt% set by the U.S. Department of Energy. However, the experimental data obtained with different methods for various carbon nanostructures show an extreme scatter. Classical calculations based on physisorption of hydrogen molecules could not explain the high storage capacities measured at ambient temperature, and, assuming chemisorption of hydrogen atoms, hydrogen release requires temperatures too high for technical applications. Up to now, only a few calculations and experiments indicate the possibility of an intermediate binding energy. Recently, serious doubt has arisen in relation to several key experiments, causing considerable controversy. Furthermore, high hydrogen storage capacities measured for carbon nanofibers did not survive cross-checking in different laboratories. Therefore, in light of today's knowledge, it is becoming less likely that at moderate pressures around room temperature carbon nanostructures can store the amount of hydrogen required for automotive applications.

  7. Iron-Doped Carbon Aerogels: Novel Porous Substrates for Direct Growth of Carbon Nanotubes (United States)

    Steiner, S. A.; Baumann, T. F.; Kong, J.; Satcher, J. H.; Dresselhaus, M. S.


    We present the synthesis and characterization of Fe-doped carbon aerogels (CAs) and demonstrate the ability to grow carbon nanotubes directly on monoliths of these materials to afford novel carbon aerogel-carbon nanotube composites. Preparation of the Fe-doped CAs begins with the sol-gel polymerization of the potassium salt of 2,4-dihydroxybenzoic acid with formaldehyde, affording K{sup +}-doped gels that can then be converted to Fe{sup 2+}- or Fe{sup 3+}-doped gels through an ion exchange process, dried with supercritical CO{sub 2} and subsequently carbonized under an inert atmosphere. Analysis of the Fe-doped CAs by TEM, XRD and XPS revealed that the doped iron species are reduced during carbonization to form metallic iron and iron carbide nanoparticles. The sizes and chemical composition of the reduced Fe species were related to pyrolysis temperature as well as the type of iron salt used in the ion exchange process. Raman spectroscopy and XRD analysis further reveal that, despite the presence of the Fe species, the CA framework is not significantly graphitized during pyrolysis. The Fe-doped CAs were subsequently placed in a thermal CVD reactor and exposed to a mixture of CH{sub 4} (1000 sccm), H{sub 2} (500 sccm), and C{sub 2}H{sub 4} (20 sccm) at temperatures ranging from 600 to 800 C for 10 minutes, resulting in direct growth of carbon nanotubes on the aerogel monoliths. Carbon nanotubes grown by this method appear to be multiwalled ({approx}25 nm in diameter and up to 4 mm long) and grow through a tip-growth mechanism that pushes catalytic iron particles out of the aerogel framework. The highest yield of CNTs were grown on Fe-doped CAs pyrolyzed at 800 C treated at CVD temperatures of 700 C.

  8. Iron-Doped Carbon Aerogels: Novel Porous Substrates for Direct Growth of Carbon Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Steiner, S A; Baumann, T F; Kong, J; Satcher, J H; Dresselhaus, M S


    We present the synthesis and characterization of Fe-doped carbon aerogels (CAs) and demonstrate the ability to grow carbon nanotubes directly on monoliths of these materials to afford novel carbon aerogel-carbon nanotube composites. Preparation of the Fe-doped CAs begins with the sol-gel polymerization of the potassium salt of 2,4-dihydroxybenzoic acid with formaldehyde, affording K{sup +}-doped gels that can then be converted to Fe{sup 2+}- or Fe{sup 3+}-doped gels through an ion exchange process, dried with supercritical CO{sub 2} and subsequently carbonized under an inert atmosphere. Analysis of the Fe-doped CAs by TEM, XRD and XPS revealed that the doped iron species are reduced during carbonization to form metallic iron and iron carbide nanoparticles. The sizes and chemical composition of the reduced Fe species were related to pyrolysis temperature as well as the type of iron salt used in the ion exchange process. Raman spectroscopy and XRD analysis further reveal that, despite the presence of the Fe species, the CA framework is not significantly graphitized during pyrolysis. The Fe-doped CAs were subsequently placed in a thermal CVD reactor and exposed to a mixture of CH{sub 4} (1000 sccm), H{sub 2} (500 sccm), and C{sub 2}H{sub 4} (20 sccm) at temperatures ranging from 600 to 800 C for 10 minutes, resulting in direct growth of carbon nanotubes on the aerogel monoliths. Carbon nanotubes grown by this method appear to be multiwalled ({approx}25 nm in diameter and up to 4 mm long) and grow through a tip-growth mechanism that pushes catalytic iron particles out of the aerogel framework. The highest yield of CNTs were grown on Fe-doped CAs pyrolyzed at 800 C treated at CVD temperatures of 700 C.

  9. Acute toxicity studies of potassium permanganate in Swiss albino mice

    African Journals Online (AJOL)

    Acute toxicity study of potassium permanganate was carried out in Swiss albino mice. Potassium permanganate was administered at dose rate of 0.0, 500, 1000, 1500, 2000, 2500, 3000 and 3500mg/kg body weight to groups 1, 2, 3, 4, 5, 6, 7 and 8, ten per group for LD50 determination. The dead animals were posted for ...

  10. Spectroscopy of erbium-doped potassium double tungstate waveguides

    NARCIS (Netherlands)

    Vázquez-Córdova, Sergio A.; Aravazhi, Shanmugam; Grivas, Christos; Heuer, Alexander M.; Kränkel, Christian; Yong, Yean Sheng; García-Blanco, Sonia M.; Herek, Jennifer L.; Pollnau, Markus


    We report the spectroscopy of crystalline waveguide amplifiers operating in the telecom C-band. Thin films of erbiumdoped gadolinium lutetium potassium double tungstate, KGdxLuyEr1-x-y (WO4)2, are grown by liquid-phase epitaxy onto undoped potassium yttrium double tungstate (KYW) substrates and

  11. Potassium Bromate Content of Bread Produced in Sokoto Metropolis ...

    African Journals Online (AJOL)

    Fifteen different bread samples were randomly collected from various local bakeries located in Sokoto metropolis. The samples were analysed for presence and quantity of potassium bromate. All the samples were analysed using the redox titrimetric method for the detection of potassium bromate. All the samples contained ...

  12. Effect of Metformin on Potassium-adapted and Non- adapted ...

    African Journals Online (AJOL)

    Purpose: To assess the effects of potassium adaptation on some biochemical parameters in diabetic rats treated with metformin. Methods: Diabetes was induced via intraperitoneal administration of streptozotocin in potassium- adapted and non-adapted rats and, then metformin (350 mg/kg) was administered orally.

  13. Crystal structure of the sodium-potassium pump

    DEFF Research Database (Denmark)

    Morth, J Preben; Pedersen, Bjørn Panyella; Toustrup-Jensen, Mads S


    The Na+,K+-ATPase generates electrochemical gradients for sodium and potassium that are vital to animal cells, exchanging three sodium ions for two potassium ions across the plasma membrane during each cycle of ATP hydrolysis. Here we present the X-ray crystal structure at 3.5 A resolution...

  14. The Effect Of Potassium Bromate On Some Haematological ...

    African Journals Online (AJOL)

    Summary: Potassium bromate used widely in foods has been associated with various complications in humans. However there is paucity of literature on adverse effects on haematological parameters. Thus we decided to carry out an experimental study to determine the effects of potassium bromate on some blood indices ...

  15. Evaluation of in vitro antifungal activity of potassium bicarbonate on ...

    African Journals Online (AJOL)

    The effect of increased concentrations of potassium bicarbonate (KHCO3) as a possible alternative to synthetic fungicides for controlling Rhizoctonia solani AG 4 HG-I and Sclerotinia sclerotiorum was evaluated in vitro, in this study. In addition, the effect of potassium bicarbonate on Trichoderma sp., a natural antagonist on ...

  16. Extractability of Potassium from Some Organic Manures in Aqueous ...

    African Journals Online (AJOL)

    The effect of pH, time and concentration on the extractability of potassium from five types of organic manures (cow dung, local chickens, duck and commercial chickens, faeces on bedded and unbedded floor) were studied. Experiments were conducted in water at 40oC. Cumulative extraction curves of potassium resulting ...

  17. Relationship between serum total magnesium and serum potassium ...

    African Journals Online (AJOL)


    Jun 2, 2016 ... Aim: To determine the relationship between serum total magnesium and potassium levels in adult patients requiring an emergency ..... and in-hospital mortality in critically ill patients and a before-after analysis on the impact of computer- assisted potassium control. Crit Care [Internet]. 2015;19(1):1–11.

  18. Sodium and potassium concentrations in floral nectars in relation to ...

    African Journals Online (AJOL)

    Sodium and potassium concentrations have been measured in nectar from a variety of flowering plants visited by honey bees (Apis mellifera capensis). In 18 plant species the mean sodium concentration was 9,8 ± 1,4 mmol (± S.E.), and the mean potassium concentration was 18,7 ± 4,3 mmol. These results are compared ...

  19. Potassium bromate content and some other attributes of selected ...

    African Journals Online (AJOL)

    There is no report on potassium bromate in bread sold in Abeokuta, the capital city of Ogun State. Objective: The study examined commercial brands of wheat flour and bread samples in Odeda Local Government for the presence of potassium bromate, along with some physical, functional, chemical and sensory properties.

  20. Thermal decomposition of potassium bis-oxalatodiaqua-indate (III ...

    Indian Academy of Sciences (India)

    2] 3H2O. Thermal decomposition studies show that the compound decomposes first to the anhydrous potassium indium oxalate and then to the final mixture of the oxides through formation of potassium carbonate and indium (III) oxide as ...

  1. the effect of potassium bromate on some haematological parameters ...

    African Journals Online (AJOL)

    Daniel Owu

    At the kidney, the potassium bromate induces renal oxidative stress which is known to cause renal failure, methaemoglobinaemia and kidney cancer (De. Angelo et al 1988, Parsons and Chipman. 2000).There has not been much reports on the effect of potassium bromate on haematological indices, thus this research was ...

  2. Thermal decomposition of potassium bis-oxalatodiaqua- indate(III ...

    Indian Academy of Sciences (India)


    )2]⋅3H2O. Thermal decomposition studies show that the compound decomposes first to the anhydrous potassium indium oxalate and then to the final mixture of the oxides through formation of potassium carbonate and indium (III) oxide as ...

  3. Potassium cycling and losses in grassland systems : a review

    NARCIS (Netherlands)

    Kayser, M; Isselstein, J

    Cycling of potassium in grassland systems has received relatively little attention in research and practice in recent years. Balanced nutrient systems require consideration of nutrients other than nitrogen (N). Potassium (K) is needed in large amounts and is closely related to N nutrition. In

  4. Sodium and potassium concentrations in floral nectars in relation to ...

    African Journals Online (AJOL)


    Aug 3, 1989 ... Sodium and potassium concentrations have been measured in nectar from a variety of flowering plants visited by honey bees fApis me/litera capensis). In 18 plant species the mean sodium concentration was 9,8 ± 1,4 mmol (± S.E.), and the mean potassium concentration was 18,7 ± 4,3 mmol.

  5. The role of potassium ion in muscle glycogenolysis and glycolysis. (United States)

    Olerud, J E; Pryor, W H; Eason, R L; Carroll, H W


    We have presented evidence that in an in vitro system, glycogenolysis and glycolysis function normally at potassium levels far below those observed in muscle cell water of severely deficient dogs. We suggest that a functional impairment of glycogenolysis or glycolysis is unlikely to be a mechanism by which potassium deficiency leads to rhabdomyolysis.

  6. 40 CFR 721.10021 - Magnesium potassium titanium oxide. (United States)


    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Magnesium potassium titanium oxide... Specific Chemical Substances § 721.10021 Magnesium potassium titanium oxide. (a) Chemical substance and... titanium oxide (PMN P-01-764; CAS No. 39290-90-9) is subject to reporting under this section for the...

  7. Potassium bromate content of some baked breads sold in Kano ...

    African Journals Online (AJOL)

    Background: Potassium bromate is an additive used by some bakers to make the bread rise rapidly, create a good texture in the finished product and to give bulkiness to the dough. Objective: The main objective of this work was to assess the potassium bromate residues of some baked breads sold in some selected local ...

  8. Evaluation of in vitro antifungal activity of potassium bicarbonate on ...

    African Journals Online (AJOL)



    Aug 10, 2011 ... The effect of increased concentrations of potassium bicarbonate (KHCO3) as a possible alternative to synthetic fungicides for controlling Rhizoctonia solani AG 4 HG-I and Sclerotinia sclerotiorum was evaluated in vitro, in this study. In addition, the effect of potassium bicarbonate on Trichoderma sp., a.

  9. Determination and comparison of vitamin C, calcium and potassium ...

    African Journals Online (AJOL)

    Vitamin C content was determined by 2,6-dichloroindophenol titrimetric method while calcium and potassium were determined by atomic absorption spectroscopy. Results from the study showed inconsistent pattern with respect to vitamin C, calcium and potassium contents in the conventionally and organically grown ...

  10. Top-dressing of Potassium Fertilizers on Safflower

    Directory of Open Access Journals (Sweden)

    Neginsadat Amir Khalili


    Full Text Available To determine the effects of potassium foliar application (with two levels, use and non-use from potassium sulphate source and top-dressing application of potassium fertilizer (with two levels, use and non-use from potassium chloride source on number of seeds per capitulum, number of side branch per plant, seed yield, seed oil content, oil yield, seed to coat ratio, plant height and shoot dry weight in three safflower, genotypes including KW.2, Padideh and Goldasht a factorial experiment based on the randomized complete block design (RCBD with three replications, was conducted during 2013 growing season at the Agricultural Research Center of Semnan province (Shahroud. Results showed that the highest average of number of seeds per capitulum (28.70, number of side branch per plant (17.83 and seed to coat ratio (1.47 were found in KW.2 genotype. The highest seed yield (2627.7 kg/ha and oil yield (1350.5 kg/ha were found from potassium sulphate foliar application in Padideh and KW.2 genotypes respectively. The interaction effect of genotype × potassium foliar application was significant for seed and oil yields. In conclusion, it was determined that potassium sulphate foliar application has better impacts on seed and oil yield of safflower genotypes than potassium top-dressing application.

  11. High frequency conductivity of hot electrons in carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Amekpewu, M., E-mail: [Department of Applied Physics, University for Development Studies, Navrongo (Ghana); Mensah, S.Y. [Department of Physics, College of Agriculture and Natural Sciences, U.C.C. (Ghana); Musah, R. [Department of Applied Physics, University for Development Studies, Navrongo (Ghana); Mensah, N.G. [Department of Mathematics, College of Agriculture and Natural Sciences, U.C.C. (Ghana); Abukari, S.S.; Dompreh, K.A. [Department of Physics, College of Agriculture and Natural Sciences, U.C.C. (Ghana)


    High frequency conductivity of hot electrons in undoped single walled achiral Carbon Nanotubes (CNTs) under the influence of ac–dc driven fields was considered. We investigated semi-classically Boltzmann's transport equation with and without the presence of the hot electrons’ source by deriving the current densities in CNTs. Plots of the normalized current density versus frequency of ac-field revealed an increase in both the minimum and maximum peaks of normalized current density at lower frequencies as a result of a strong injection of hot electrons. The applied ac-field plays a twofold role of suppressing the space-charge instability in CNTs and simultaneously pumping an energy for lower frequency generation and amplification of THz radiations. These have enormous promising applications in very different areas of science and technology.

  12. Radiation Protection Using Single-Wall Carbon Nanotube Derivatives (United States)

    Tour, James M.; Lu, Meng; Lucente-Schultz, Rebecca; Leonard, Ashley; Doyle, Condell Dewayne; Kosynkin, Dimitry V.; Price, Brandi Katherine


    This invention is a means of radiation protection, or cellular oxidative stress mitigation, via a sequence of quenching radical species using nano-engineered scaffolds, specifically single-wall carbon nanotubes (SWNTs) and their derivatives. The material can be used as a means of radiation protection by reducing the number of free radicals within, or nearby, organelles, cells, tissue, organs, or living organisms, thereby reducing the risk of damage to DNA and other cellular components (i.e., RNA, mitochondria, membranes, etc.) that can lead to chronic and/or acute pathologies, including but not limited to cancer, cardiovascular disease, immuno-suppression, and disorders of the central nervous system. In addition, this innovation could be used as a prophylactic or antidote for accidental radiation exposure, during high-altitude or space travel where exposure to radiation is anticipated, or to protect from exposure from deliberate terrorist or wartime use of radiation- containing weapons.

  13. Carbon Nanotubes Facilitate Oxidation of Cysteine Residues of Proteins. (United States)

    Hirano, Atsushi; Kameda, Tomoshi; Wada, Momoyo; Tanaka, Takeshi; Kataura, Hiromichi


    The adsorption of proteins onto nanoparticles such as carbon nanotubes (CNTs) governs the early stages of nanoparticle uptake into biological systems. Previous studies regarding these adsorption processes have primarily focused on the physical interactions between proteins and nanoparticles. In this study, using reduced lysozyme and intact human serum albumin in aqueous solutions, we demonstrated that CNTs interact chemically with proteins. The CNTs induce the oxidation of cysteine residues of the proteins, which is accounted for by charge transfer from the sulfhydryl groups of the cysteine residues to the CNTs. The redox reaction simultaneously suppresses the intermolecular association of proteins via disulfide bonds. These results suggest that CNTs can affect the folding and oxidation degree of proteins in biological systems such as blood and cytosol.

  14. Method for nano-pumping using carbon nanotubes (United States)

    Insepov, Zeke [Darien, IL; Hassanein, Ahmed [Bolingbrook, IL


    The present invention relates generally to the field of nanotechnology, carbon nanotubes and, more specifically, to a method and system for nano-pumping media through carbon nanotubes. One preferred embodiment of the invention generally comprises: method for nano-pumping, comprising the following steps: providing one or more media; providing one or more carbon nanotubes, the one or more nanotubes having a first end and a second end, wherein said first end of one or more nanotubes is in contact with the media; and creating surface waves on the carbon nanotubes, wherein at least a portion of the media is pumped through the nanotube.

  15. Interaction of multiwalled carbon nanotube produces structural ...

    African Journals Online (AJOL)

    Abstract. Multiwalled carbon nanotube (MWCNT) has been found to produce structural changes in Calf Thymus-DNA (CT-DNA). The interaction or binding of the multi-walled carbon nanotubes (MWCNT) was investigated in order to discover if it brings about any significant changes of the DNA double helix using CD spectra ...

  16. Nanotubes based on monolayer blue phosphorus

    KAUST Repository

    Montes Muñoz, Enrique


    We demonstrate structural stability of monolayer zigzag and armchair blue phosphorus nanotubes by means of molecular dynamics simulations. The vibrational spectrum and electronic band structure are determined and analyzed as functions of the tube diameter and axial strain. The nanotubes are found to be semiconductors with a sensitive indirect band gap that allows flexible tuning.

  17. Electronic properties of magnetically doped nanotubes

    Indian Academy of Sciences (India)


    Electronic properties of magnetically doped nanotubes. KEIVAN ESFARJANI*, Z CHEN† and Y KAWAZOE†. Sharif Institute of Technology, and Institute for Physics and Mathematics, Tehran, Iran. †Institute for Materials Research, Tohoku University, Sendai, Japan. Abstract. Effect of doping of carbon nanotubes by magnetic ...

  18. Nanoscratch technique for aligning multiwalled carbon nanotubes ...

    Indian Academy of Sciences (India)

    to align a MWCNT, as well as the energy required to align a gram of nanotubes, has been estimated. The method demonstrated represents an economical approach for large-scale synthesis of aligned MWCNTs at low costs. Keywords. Carbon nanotube; arc discharge; characterization; alignment; nanoscratch. 1.

  19. Is thallium-201 of use in the measurement of total exchangeable potassium in man? (United States)

    MacKay, A; Davies, D L; Horton, P W


    Simultaneous measurements of exchangeable potassium were made in seven normal male subjects using potassium-43 and thallium-201. Exchangeable potassium values obtained using the 'thallium-201 space' were unreliable.

  20. Electron impact study of potassium hydroxide (United States)

    Vuskovic, L.; Trajmar, S.


    An attempt is made to measure the sum of the elastic, rotational and vibrational scattering of electrons by KOH at low impact energies (5 to 20 eV) at angles from 10 to 120 deg. Energy loss spectra taken in the 0 to 18 eV range using an electron impact spectrometer are used to identify the species contributing to electric scattering. At temperatures between 300 and 500 C, only inelastic spectral features belonging to water are detected, while at temperatures from 500 to 800 C strong atomic K lines, indicative of molecular dissociation, and H2 energy loss features become prominent. No features attributable to KOH, the KOH dimer, O2 or potassium oxides were observed, due to the effects of the dissociation products, and it is concluded that another technique will have to be developed in order to measure electron scattering by KOH.

  1. High dose potassium-nitrate chemical dosimeter

    International Nuclear Information System (INIS)

    Dorda de Cancio, E.M.; Munoz, S.S.


    This dosimeter is used to control 10 kGY-order doses (1 Mrad). Nitrate suffers a radiolitic reduction phenomena, which is related to the given dose. The method to use potassium nitrate as dosimeter is described, as well as effects of the temperature of irradiation, pH, nitrate concentration and post-irradiation stability. Nitrate powder was irradiated at a Semi-Industrial Plant, at Centro Atomico Ezeiza, and also in a Gammacell-220 irradiator. The dose rates used were 2,60 and 1,80 KGY/hour, and the given doses varied between 1,0 and 150 KGY. The uncertainty was +-3% in all the range. (author) [es

  2. Potassium bromide, KBr/ ε: New Force Field (United States)

    Fuentes-Azcatl, Raúl; Barbosa, Marcia C.


    We propose a new force field for the Potassium Bromide, the KBr/ ε. The crystal density and structure, as well as, the density, the viscosity and the dielectric constant of the solution in water were computed and compared with the experiments and other atomistic models. Next, the transferability of the KBr/ ε and of the NaCl/ ε models is verified by creating the KCl/ ε and the NaBr/ ε models. The strategy was to employ the same parameters obtained for the NaCl/ ε and for the KBr/ ε force fields for the building up of the KCl/ ε and the NaBr/ ε models . The thermodynamic and dynamic properties of these two new models were compared with the experimental

  3. The formation mechanism of chiral carbon nanotubes (United States)

    Liu, Jing; Liu, Liren; Lu, Junzhe; Zhu, Hengjiang


    The nuclei and the formation mechanism of chiral carbon nanotubes, namely, single-, double-, and triple-walled carbon nanotubes are simulated by the first principle density functional theory. The formation mechanism from nuclei to corresponding infinitely long carbon nanotubes occurs spirally and via absorbing carbon atoms layer by layer. Carbon atoms at the open end are metastable state compared with ones in the tube wall or the closed end, which indicate the growth point of chiral carbon nanotubes is located at the open end. Growth of outer layer tubular clusters takes precedence over the inner layer in the process of forming multi-walled nuclear structures. Because of the ratio of carbon atoms at the open end to all carbon atoms decreases, the stability of the tubular clusters increases with their length. The infinitely long carbon nanotubes are obtained by executing periodic boundary conditions depend on corresponding nuclear structures.

  4. Continuum modeling of boron nitride nanotubes

    International Nuclear Information System (INIS)

    Song, J; Wu, J; Hwang, K C; Huang, Y


    Boron nitride nanotubes display unique properties and have many potential applications. A finite-deformation shell theory is developed for boron nitride nanotubes directly from the interatomic potential to account for the effect of bending and curvature. Its constitutive relation accounts for the nonlinear, multi-body atomistic interactions, and therefore can model the important effect of tube chirality and radius. The theory is then used to determine whether a single-wall boron nitride nanotube can be modeled as a linear elastic isotropic shell. Instabilities of boron nitride nanotubes under different loadings (e.g., tension, compression, and torsion) are also studied. It is shown that the tension instability of boron nitride nanotubes is material instability, while the compression and torsion instabilities are structural instabilities.

  5. Electron impact excitation of potassium and sodium

    International Nuclear Information System (INIS)

    Phelps, J.O. III.


    Absolute electron-impact optical excitation functions of 24 transitions of the sharp, principal, diffuse and fundamental series of potassium have been measured in the impact energy range 0 to 400 eV. The determination of the target atom number density was made by measuring the transmissions of potassium resonance radiation from a fluorescence cell upon passage through the collision chamber. Direct excitation cross section of 14 states (5S, 6S, 7S, 8S, 4P, 5P, 6P, 7P, 3D, 5D, 6D, 5F, 6F, and 7F) have been determined from the measured optical excitation cross sections with the aid of radiative transition probabilities taken from the literature. These direct cross section results are compared with theoretical calculations based upon the Born approximation and the multi-state close-couplng approximation. Measurements were also made of the polarization of resolved components of the 4P-4S and 3D-4P doublets, and from these results the direct excitation functions of the separate orbital magnetic substates of the 3P state have been determined. This work has been extended to sodium, yielding measurements of optical excitation functions of 26 transitions of the sharp, principal, diffuse, fundamental, and nP-4S series in the energy range 0 to 150 eV. From these measurements, direct excitation functions of 14 states (4S, 5S, 6S, 7S, 3P, 4P, 5P, 6P, 3D, 4D, 5D, 6D, 6F, and 7F) have been determined. These are compared with theoretical results based on the Born approximation and the close-coupling method. Polarization measurements were made for several sharp, principal, and diffuse doublets, and this data is applied to determine the magnetic substate direct substate direct excitation functions for the 3P state

  6. Bulk Cutting of Carbon Nanotubes Using Electron Beam Irradiation (United States)

    Ziegler, Kirk J. (Inventor); Rauwald, Urs (Inventor); Hauge, Robert H. (Inventor); Schmidt, Howard K. (Inventor); Smalley, Richard E. (Inventor); Kittrell, W. Carter (Inventor); Gu, Zhenning (Inventor)


    According to some embodiments, the present invention provides a method for attaining short carbon nanotubes utilizing electron beam irradiation, for example, of a carbon nanotube sample. The sample may be pretreated, for example by oxonation. The pretreatment may introduce defects to the sidewalls of the nanotubes. The method is shown to produces nanotubes with a distribution of lengths, with the majority of lengths shorter than 100 tun. Further, the median length of the nanotubes is between about 20 nm and about 100 nm.

  7. Schottky barriers at metal-finite semiconducting carbon nanotube interfaces


    Xue, Yongqiang; Ratner, Mark A.


    Electronic properties of metal-finite semiconducting carbon nanotube interfaces are studied as a function of the nanotube length using a self-consistent tight-binding theory. We find that the shape of the potential barrier depends on the long-range tail of the charge transfer, leading to an injection barrier thickness comparable to half of the nanotube length until the nanotube reaches the bulk limit. The conductance of the nanotube junction shows a transition from tunneling to thermally-acti...

  8. Radiation Protection Using Carbon Nanotube Derivatives (United States)

    Conyers, Jodie L., Jr.; Moore, Valerie C.; Casscells, S. Ward


    BHA and BHT are well-known food preservatives that are excellent radical scavengers. These compounds, attached to single-walled carbon nanotubes (SWNTs), could serve as excellent radical traps. The amino-BHT groups can be associated with SWNTs that have carbolyxic acid groups via acid-base association or via covalent association. The material can be used as a means of radiation protection or cellular stress mitigation via a sequence of quenching radical species using nano-engineered scaffolds of SWNTs and their derivatives. It works by reducing the number of free radicals within or nearby a cell, tissue, organ, or living organism. This reduces the risk of damage to DNA and other cellular components that can lead to chronic and/or acute pathologies, including (but not limited to) cancer, cardiovascular disease, immuno-suppression, and disorders of the central nervous system. These derivatives can show an unusually high scavenging ability, which could prove efficacious in protecting living systems from radical-induced decay. This technique could be used to protect healthy cells in a living biological system from the effects of radiation therapy. It could also be used as a prophylactic or antidote for radiation exposure due to accidental, terrorist, or wartime use of radiation- containing weapons; high-altitude or space travel (where radiation exposure is generally higher than desired); or in any scenario where exposure to radiation is expected or anticipated. This invention s ultimate use will be dependent on the utility in an overall biological system where many levels of toxicity have to be evaluated. This can only be assessed at a later stage. In vitro toxicity will first be assessed, followed by in vivo non-mammalian screening in zebra fish for toxicity and therapeutic efficacy.

  9. Investigation on optical absorption properties of ion irradiated single walled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Vishalli,, E-mail:; Dharamvir, Keya, E-mail: [Department of Physics, Panjab University, Chandigarh (India); Kaur, Ramneek; Raina, K. K. [Materials Research Laboratory, School of Physics and Materials Science, Thapar University, Patiala (India); Avasthi, D. K. [Materials Science Group, Inter University Accelerator Centre, ArunaAsaf Ali Marg, NewDelhi (India); Jeet, Kiran [Electron Microscopy and Nanoscience laboratory, Punjab Agriculture University, Ludhiana (India)


    In the present study change in the optical absorption properties of single walled carbon nanotubes (SWCNTs) under nickel ion (60 MeV) irradiation at various fluences has been investigated. Langmuir Blodgett technique is used to deposit SWCNT thin film of uniform thickness. AFM analysis shows a network of interconnected bundles of nanotubes. UV-Vis-NIR absorption spectra indicate that the sample mainly contain SWCNTs of semiconducting nature. It has been found in absorption spectra that there is decrease in the intensity of the characteristic SWCNT peaks with increase in fluence. At fluence value 1×10{sup 14} ions/cm{sup 2} there is almost complete suppression of the characteristic SWCNTs peaks.The decrease in the optical absorption with increase in fluence is due to the increase in the disorder in the system which leads to the decrease in optically active states.

  10. Linear current fluctuations in the power-law region of metallic carbon nanotubes (United States)

    Talukdar, D.; Yotprayoonsak, P.; Herranen, O.; Ahlskog, M.


    We study low-frequency noise in a non-Ohmic region of metallic single walled and multiwalled carbon nanotubes. The generalized relative noise appears to be independent of applied bias in the power-law regime of the tubes and in agreement with theoretical predictions. Beyond the power-law regime the suppression of conductance due to scattering with optical phonons is accompanied by a reduction of relative noise by an order of magnitude. Mobility fluctuations in the tubes due to optical phonon scattering cause the unexpected reduction in the relative noise magnitude which is modeled using a modified mobility fluctuation picture. The findings have important implications for metallic nanotubes being used as interconnects in nanoelectronic devices.

  11. J/Ψ suppression

    International Nuclear Information System (INIS)

    Giubellino, P.; Abreu, M.C.; Alessandro, B.; Alexa, C.; Arnaldi, R.; Astruc, J.; Atayan, M.; Baglin, C.; Baldit, A.; Bedjidian, M.; Bellaiche, F.; Beole, S.; Boldea, V.; Bordalo, P.; Bussiere, A.; Capony, V.; Casagrande, L.; Castor, J.; Chambon, T.; Chaurand, B.; Chevrot, I.; Cheynis, B.; Chiavassa, E.; Cicalo, C.; Comets, M.P.; Constantinescu, S.; Cruz, J.; De Falco, A.; De Marco, N.; Dellacasa, G.; Devaux, A.; Dita, S.; Drapier, O.; Espagnon, B.; Fargeix, J.; Filippov, S.N.; Fleuret, F.; Force, P.; Gallio, M.; Gavrilov, Y.K.; Gerschel, C.; Giubellino, P.; Golubeva, M.B.; Gonin, M.; Grigorian, A.A.; Grossiord, J.Y.; Guber, F.F.; Guichard, A.; Gulkaninan, H.; Hakobyan, R.; Haroutunian, R.; Idzik, M.; Jouan, D.; Karavitcheva, T.L.; Kluberg, L.; Kurepin, A.B.; Le Bornec, Y.; Lourenco, C.; Mac Cormick, M.; Macciotta, P.; Marzari-Chiesa, A.; Masera, M.; Masoni, A.; Mehrabyan, S.; Mourgues, S.; Musso, A.; Ohlsson-Malek, F.; Petiau, P.; Piccotti, A.; Pizzi, J.R.; Prado da Silva, W.L.; Puddu, G.; Quintans, C.; Racca, C.; Ramello, L.; Ramos, S.; Rato-Mendes, P.; Riccati, L.; Romana, A.; Sartori, S.; Saturnini, P.; Scomparin, E.; Serci, S.; Shahoyan, R.; Silva, S.; Soave, C.; Sonderegger, P.; Tarrago, X.; Temnikov, P.; Topilskaya, N.S.; Usai, G.; Vale, C.; Vercellin, E.; Willis, N.


    The cross section for J/Ψ production in Pb-Pb interactions at 158 GeV per nucleon is measured at the CERN SPS by the NA50 experiment. The final results from the 1995 run are presented here together with preliminary ones from the high-statistics 1996 run. An anomalous J/Ψ suppression is observed in Pb-Pb collisions as compared to extrapolations of the previous results obtained by the NA38 experiment with proton and lighter ion beams. The results of the two runs are in good agreement. The results from the 1996 run allow the study of the onset of the anomalous suppression within the same set of data, showing evidence of a sharp change of behaviour around a value of neutral transverse energy, as measured by our electromagnetic calorimeter, of about 50 GeV

  12. Removal of Ozone by Carbon Nanotubes/Quartz Fiber Film. (United States)

    Yang, Shen; Nie, Jingqi; Wei, Fei; Yang, Xudong


    Ozone is recognized as a harmful gaseous pollutant, which can lead to severe human health problems. In this study, carbon nanotubes (CNTs) were tested as a new approach for ozone removal. The CNTs/quartz fiber film was fabricated through growth of CNTs upon pure quartz fiber using chemical vapor deposition method. Ozone conversion efficiency of the CNTs/quartz fiber film was tested for 10 h and compared with that of quartz film, activated carbon (AC), and a potassium iodide (KI) solution under the same conditions. The pressure resistance of these materials under different airflow rates was also measured. The results showed that the CNTs/quartz fiber film had better ozone conversion efficiency but also higher pressure resistance than AC and the KI solution of the same weight. The ozone removal performance of the CNTs/quartz fiber film was comparable with AC at 20 times more weight. The CNTs played a dominant role in ozone removal by the CNTs/quartz fiber film. Its high ozone conversion efficiency, lightweight and free-standing properties make the CNTs/quartz fiber film applicable to ozone removal. Further investigation should be focused on reducing pressure resistance and studying the CNT mechanism for removing ozone.

  13. Use of potassium-42 in the study of kidney functioning

    International Nuclear Information System (INIS)

    Morel, F.; Guinnebault, M.


    Following an intravenous injection of potassium-42 as indicator, an analysis of the specific activity vs. time curve in arterial plasma, in venous plasma efferent from the kidney, in urine and in various regions of the kidney of rabbits reveals that: 1) The turnover rate of potassium in the cortex cells (proximal and distal convoluted tubes) is very large, being limited only by renal blood flow. 2) The turnover rate of potassium in deep regions (Henle loops and collector tubules) is much smaller. 3) Potassium in the urine comes from cells of the convoluted tubes and not from cells of Henle loops, collector ducts, or glomerular filtrate. 4) Any potassium filtered at the level of the glomerules would be entirely reabsorbed at the level of the proximal tube, while total potassium in the urine results from a process of excretion by cells of the distal tube. These results are comparable with the assumption that the movement of potassium between interstitial medium and convoluted tube cells results from entirely passive processes. (author) [fr

  14. Use of Functionalized Carbon Nanotubes for Covalent Attachment of Nanotubes to Silicon (United States)

    Tour, James M.; Dyke, Christopher A.; Maya, Francisco; Stewart, Michael P.; Chen, Bo; Flatt, Austen K.


    The purpose of the invention is to covalently attach functionalized carbon nanotubes to silicon. This step allows for the introduction of carbon nanotubes onto all manner of silicon surfaces, and thereby introduction of carbon nano - tubes covalently into silicon-based devices, onto silicon particles, and onto silicon surfaces. Single-walled carbon nanotubes (SWNTs) dispersed as individuals in surfactant were functionalized. The nano - tube was first treated with 4-t-butylbenzenediazonium tetrafluoroborate to give increased solubility to the carbon nanotube; the second group attached to the sidewall of the nanotube has a silyl-protected terminal alkyne that is de-protected in situ. This gives a soluble carbon nanotube that has functional groups appended to the sidewall that can be attached covalently to silicon. This reaction was monitored by UV/vis/NJR to assure direct covalent functionalization.

  15. Helical polycarbodiimide cloaking of carbon nanotubes enables inter-nanotube exciton energy transfer modulation. (United States)

    Budhathoki-Uprety, Januka; Jena, Prakrit V; Roxbury, Daniel; Heller, Daniel A


    The use of single-walled carbon nanotubes (SWCNTs) as near-infrared optical probes and sensors require the ability to simultaneously modulate nanotube fluorescence and functionally derivatize the nanotube surface using noncovalent methods. We synthesized a small library of polycarbodiimides to noncovalently encapsulate SWCNTs with a diverse set of functional coatings, enabling their suspension in aqueous solution. These polymers, known to adopt helical conformations, exhibited ordered surface coverage on the nanotubes and allowed systematic modulation of nanotube optical properties, producing up to 12-fold differences in photoluminescence efficiency. Polymer cloaking of the fluorescent nanotubes facilitated the first instance of controllable and reversible internanotube exciton energy transfer, allowing kinetic measurements of dynamic self-assembly and disassembly.

  16. Delivery of small interfering RNAs in human cervical cancer cells by polyethylenimine-functionalized carbon nanotubes (United States)

    Huang, Yuan-Pin; Lin, I.-Jou; Chen, Chih-Chen; Hsu, Yi-Chiang; Chang, Chi-Chang; Lee, Mon-Juan


    Carbon nanotubes are capable of penetrating the cell membrane and are widely considered as potential carriers for gene or drug delivery. Because the C-C and C=C bonds in carbon nanotubes are nonpolar, functionalization is required for carbon nanotubes to interact with genes or drugs as well as to improve their biocompatibility. In this study, polyethylenimine (PEI)-functionalized single-wall (PEI-NH-SWNTs) and multiwall carbon nanotubes (PEI-NH-MWNTs) were produced by direct amination method. PEI functionalization increased the positive charge on the surface of SWNTs and MWNTs, allowing carbon nanotubes to interact electrostatically with the negatively charged small interfering RNAs (siRNAs) and to serve as nonviral gene delivery reagents. PEI-NH-MWNTs and PEI-NH-SWNTs had a better solubility in water than pristine carbon nanotubes, and further removal of large aggregates by centrifugation produced a stable suspension of reduced particle size and improved homogeneity and dispersity. The amount of grafted PEI estimated by thermogravimetric analysis was 5.08% ( w/ w) and 5.28% ( w/ w) for PEI-NH-SWNTs and PEI-NH-MWNTs, respectively. For the assessment of cytotoxicity, various concentrations of PEI-NH-SWNTs and PEI-NH-MWNTs were incubated with human cervical cancer cells, HeLa-S3, for 48 h. PEI-NH-SWNTs and PEI-NH-MWNTs induced cell deaths in a dose-dependent manner but were less cytotoxic compared to pure PEI. As determined by electrophoretic mobility shift assay, siRNAs directed against glyceraldehyde-3-phosphate dehydrogenase (siGAPDH) were completely associated with PEI-NH-SWNTs or PEI-NH-MWNTs at a PEI-NH-SWNT/siGAPDH or PEI-NH-MWNT/siGAPDH mass ratio of 80:1 or 160:1, respectively. Furthermore, PEI-NH-SWNTs and PEI-NH-MWNTs successfully delivered siGAPDH into HeLa-S3 cells at PEI-NH-SWNT/siGAPDH and PEI-NH-MWNT/siGAPDH mass ratios of 1:1 to 20:1, resulting in suppression of the mRNA level of GAPDH to an extent similar to that of DharmaFECT, a common transfection

  17. Potassium Silicate Foliar Fertilizer Grade from Geothermal Sludge and Pyrophyllite

    Directory of Open Access Journals (Sweden)

    Muljani Srie


    Full Text Available Potassium silicate fertilizer grade were successfully produced by direct fusion of silica (SiO2 and potasium (KOH and K2CO3 in furnaces at temperatures up to melting point of mixture. The geothermal sludge (98% SiO2 and the pyrophyllite (95% SiO2 were used as silica sources. The purposes of the study was to synthesise potassium silicate fertilizer grade having solids concentrations in the range of 31-37% K2O, and silica in the range of 48-54% SiO2. The weight ratio of silicon dioxide/potasium solid being 1:1 to 5:1. Silica from geothermal sludge is amorphous, whereas pyrophylite is crystalline phase. The results showed that the amount of raw materials needed to get the appropriate molar ratio of potassium silicate fertilizer grade are different, as well as the fusion temperature of the furnace. Potassium silicate prepared from potassium hydroxide and geothermal sludge produced a low molar ratio (2.5: 1 to 3: 1. The potassium required quite small (4:1 in weight ratio, and on a fusion temperature of about 900 °C. Meanwhile, the potassium silicate prepared from pyrophyllite produced a high molar ratio (1.4 - 9.4 and on a fusion temperature of about 1350 °C, so that potassium needed large enough to meet the required molar ratio for the fertilizer grade. The product potassium silicate solid is amorphous with a little trace of crystalline.

  18. Microinjection study on potassium transport of rat kidney

    International Nuclear Information System (INIS)

    Miyamoto, Makoto


    Wister rate were divided into the following four groups. (A) control group (B) high-potassium diet group (C) low-potassium diet group (D) nephron population reduction (N.P.R.) group. Microinjection of the artificial solutions containing both 86 Rb and 3 H-inulin were performed into the proximal and distal convoluted tubules as well as cortical peritubular capillaries in rats undergoing mannitol diuresis. Excretory patterns of these substances were analyzed in successive urine samples. 3 H-inulin is entirely recovered in the urine of the experimental kidney following the injection into the proximal and distal tubules. 86 Rb is an adequate tracer for potassium and is absorbed into the potassium pool from either proximal tubular injections or peritubular capillaries. 86 Rb excreted with a time course similar to that of 3 H-inulin is termed as 'direct recovery' and that excreted more slowly, 'delayed recovery'. The 86 Rb recoveries which were obtained after proximal injections were independent of the injection site and averaged 9%. Secretion of 86 Rb into the urine was stimulate during enhanced K secretion and decreased during reduced K secretion along the distal nephron. Distal tubular injections gave 100% direct recovery in control, high-K diet, and N.P.R. rats. It was apparent that the 86 Rb recovery was significantly reduced, although not delayed, in animals deprived of dietary potassium for several weeks. At the collecting duct, the extensive net potassium reabsorption is observed in potassium depleted rats, whereas K absorption might be reduced or even secretion is seemingly taking place in potassium loading rats. In conclution, distal convolution and collecting duct play the major role in the regulation of urinary potassium excretion. (auth.)

  19. Effects of Long-term Fertilization on Potassium Fixation Capacity in Brown Soil (United States)

    Li, Na; Guo, Chunlei; Wang, Yue; Gao, Tianyi; Yang, Jinfeng; Han, Xiaori


    This study concentrated on the research of features of fixation. The objective of this study was to provide theoretical foundation of rational application of potassium fertilizer along with improving fertilizer availability ratio. A 32 years long-term experiment was conducted to evaluate the effects of fertilizer application on potassium changes and the factors affecting K fixation on brown soil by simulation in laboratory. When the concentration of exogenous potassium was in range of 400∼4000 mg·kg-1, potassium fixation capacity increased along with the rise of concentration of exogenous potassium, whereas K fixation rate reduced; Compared with no-potassium fertilizer, application of potassium fertilizer and organic fertilizer reduced soil potassium fixation capacity. Potassium rate and fixation-release of potassium character in soil should be taken into comprehensive consideration for rational fertilization to maintain or improve soil fertility for increasing potassium fertilizers efficiency in agriculture.

  20. Decorating Mg/Fe oxide nanotubes with nitrogen-doped carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Cao Yong, E-mail: [Institute of Environment and Municipal Engineering, North China Institute of Water Conservancy and Hydroelectric Power, Zhengzhou 450011 (China); Jiao Qingze, E-mail: [School of Chemical Engineering and the Environment, Beijing Institute of Technology, Beijing 100081 (China); Zhao Yun [School of Chemical Engineering and the Environment, Beijing Institute of Technology, Beijing 100081 (China); Dong Yingchao [Materials and Surface Science Institute (MSSI), University of Limerick, Limerick (Ireland)


    Graphical abstract: Highlights: > Mg/Fe oxide nanotubes arrayed parallel to each other were prepared by an AAO template method. > The Mg/Fe oxide nanotubes decorated with CN{sub x} were realized by CVD of ethylenediamine on the outer surface of oxide nanotubes. > The magnetic properties of Mg/Fe oxide nanotubes were highly improved after being decorated. - Abstract: Mg/Fe oxide nanotubes decorated with nitrogen-doped carbon nanotubes (CN{sub x}) were fabricated by catalytic chemical vapor deposition of ethylenediamine on the outer surface of oxide nanotubes. Mg/Fe oxide nanotubes were prepared using a 3:1 molar precursor solution of Mg(NO{sub 3}){sub 2} and Fe(NO{sub 3}){sub 3} and anodic aluminum oxide as the substrate. The obtained samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer (VSM). The XRD pattern shows that the oxide nanotubes are made up of MgO and Fe{sub 2}O{sub 3}. TEM and SEM observations indicate the oxide nanotubes are arrayed roughly parallel to each other, and the outer surface of oxide nanotubes are decorated with CN{sub x}. XPS results show the nitrogen-doped level in CN{sub x} is about 7.3 at.%. Magnetic measurements with VSM demonstrate the saturated magnetization, remanence and coercivity of oxide nanotubes are obvious improved after being decorated with CN{sub x}.

  1. Intractable hyperkalemia due to nicorandil induced potassium channel syndrome

    Directory of Open Access Journals (Sweden)

    Vivek Chowdhry


    Full Text Available Nicorandil is a commonly used antianginal agent, which has both nitrate-like and ATP-sensitive potassium (K ATP channel activator properties. Activation of potassium channels by nicorandil causes expulsion of potassium ions into the extracellular space leading to membrane hyperpolarization, closure of voltage-gated calcium channels and finally vasodilatation. However, on the other hand, being an activator of K ATP channel, it can expel K + ions out of the cells and can cause hyperkalemia. Here, we report a case of nicorandil induced hyperkalemia unresponsive to medical treatment in a patient with diabetic nephropathy.

  2. Carbon nanotube growth density control (United States)

    Delzeit, Lance D. (Inventor); Schipper, John F. (Inventor)


    Method and system for combined coarse scale control and fine scale control of growth density of a carbon nanotube (CNT) array on a substrate, using a selected electrical field adjacent to a substrate surface for coarse scale density control (by one or more orders of magnitude) and a selected CNT growth temperature range for fine scale density control (by multiplicative factors of less than an order of magnitude) of CNT growth density. Two spaced apart regions on a substrate may have different CNT growth densities and/or may use different feed gases for CNT growth.

  3. Coated carbon nanotube array electrodes (United States)

    Ren, Zhifeng [Newton, MA; Wen, Jian [Newton, MA; Chen, Jinghua [Chestnut Hill, MA; Huang, Zhongping [Belmont, MA; Wang, Dezhi [Wellesley, MA


    The present invention provides conductive carbon nanotube (CNT) electrode materials comprising aligned CNT substrates coated with an electrically conducting polymer, and the fabrication of electrodes for use in high performance electrical energy storage devices. In particular, the present invention provides conductive CNTs electrode material whose electrical properties render them especially suitable for use in high efficiency rechargeable batteries. The present invention also provides methods for obtaining surface modified conductive CNT electrode materials comprising an array of individual linear, aligned CNTs having a uniform surface coating of an electrically conductive polymer such as polypyrrole, and their use in electrical energy storage devices.

  4. Effects of Divalent Cations on Outward Potassium Currents in Leech Retzius Nerve Cells

    Directory of Open Access Journals (Sweden)

    Jovanovic Zorica


    Full Text Available The present study examines the effects of divalent metals, cadmium (Cd2+ and manganese (Mn2+, on the outward potassium currents of Retzius cells in the hirudinid leeches Haemopis sanguisuga using conventional two-microelectrode voltageclamp techniques. The outward potassium current is activated by depolarization and plays an important role in determining both the neuronal excitability and action potential duration. A strong inhibition of the fast current and a clear reduction in the late currents of the outward current with 1 mM Cd2+ were obtained, which indicated that both components are sensitive to this metal. Complete blockage of the fast and partial reduction of the slow outward currents was observed after adding 1 mM Mn2+ to the extracellular fluid. These data show that the outward K+ current in leech Retzius nerve cells comprises at least two components: a voltage-dependent K+ current and a Ca2+- activated K+ current. These observations also indicate that Cd2+ is more eff ective than Mn2+ in blocking ion fl ow through these channels and that suppressing Ca2+-activated K+ outward currents can prolong the action potential in nerve cells.

  5. A Small Potassium Current in AgRP/NPY Neurons Regulates Feeding Behavior and Energy Metabolism

    Directory of Open Access Journals (Sweden)

    Yanlin He


    Full Text Available Neurons that co-express agouti-related peptide (AgRP and neuropeptide Y (NPY are indispensable for normal feeding behavior. Firing activities of AgRP/NPY neurons are dynamically regulated by energy status and coordinate appropriate feeding behavior to meet nutritional demands. However, intrinsic mechanisms that regulate AgRP/NPY neural activities during the fed-to-fasted transition are not fully understood. We found that AgRP/NPY neurons in satiated mice express high levels of the small-conductance calcium-activated potassium channel 3 (SK3 and are inhibited by SK3-mediated potassium currents; on the other hand, food deprivation suppresses SK3 expression in AgRP/NPY neurons, and the decreased SK3-mediated currents contribute to fasting-induced activation of these neurons. Genetic mutation of SK3 specifically in AgRP/NPY neurons leads to increased sensitivity to diet-induced obesity, associated with chronic hyperphagia and decreased energy expenditure. Our results identify SK3 as a key intrinsic mediator that coordinates nutritional status with AgRP/NPY neural activities and animals’ feeding behavior and energy metabolism.

  6. Higher Potassium Concentration in Shoots Reduces Gray Mold in Sweet Basil. (United States)

    Yermiyahu, Uri; Israeli, Lior; David, Dalia Rav; Faingold, Inna; Elad, Yigal


    Nutritional elements can affect plant susceptibility to plant pathogens, including Botrytis cinerea. We tested the effect of potassium (K) fertilization on gray mold in sweet basil grown in pots, containers, and soil. Increased K in the irrigation water and in the sweet basil tissue resulted in an exponential decrease in gray mold severity. Potassium supplied to plants by foliar application resulted in a significant decrease in gray mold in plants grown with a low rate of K fertigation. Lower K fertigation resulted in a significant increase in B. cinerea infection under semi-commercial conditions. Gray mold severity in harvested shoots was significantly negatively correlated with K concentration in the irrigation solution, revealing resistance to B. cinerea infection as a result of high K concentration in sweet basil tissue. Gray mold was reduced following K foliar application of the plants. In general, there was no synergy between the fertigation and foliar spray treatments. Proper K fertilization can replace some of the required chemical fungicide treatments and it may be integrated into gray mold management for improved disease suppression.

  7. Ionizing Radiation Effects in Ni Nanotubes (United States)

    Shlimas, D.; Kozlovsky, A.; Shumskaya, A.; Kaniukov, E.; Ibragimova, M.; Zdorovets, M.; Kadyrzhanov, K.


    Polycrystalline nickel nanotubes with diameter of 380 nm and wall thickness 95 nm were synthesized by electrochemical method using PET track-etched membranes with thickness of 12 μm. A comprehensive study of the structural, morphological and electrical characteristics of Ni nanotubes irradiated with C+13 ions with energy 1.75 MeV/nucleon and fluence ranging from 109 to 5 × 1011 cm-2 was carried out. The ability of modification of structural parameters such as lattice parameter and the average size of crystallites and conductivity of Ni nanotubes by irradiation was shown.

  8. Carbon nanotube fiber spun from wetted ribbon (United States)

    Zhu, Yuntian T; Arendt, Paul; Zhang, Xiefei; Li, Qingwen; Fu, Lei; Zheng, Lianxi


    A fiber of carbon nanotubes was prepared by a wet-spinning method involving drawing carbon nanotubes away from a substantially aligned, supported array of carbon nanotubes to form a ribbon, wetting the ribbon with a liquid, and spinning a fiber from the wetted ribbon. The liquid can be a polymer solution and after forming the fiber, the polymer can be cured. The resulting fiber has a higher tensile strength and higher conductivity compared to dry-spun fibers and to wet-spun fibers prepared by other methods.

  9. Liquid surface model for carbon nanotube energetics

    DEFF Research Database (Denmark)

    Solov'yov, Ilia; Mathew, Maneesh; Solov'yov, Andrey V.


    In the present paper we developed a model for calculating the energy of single-wall carbon nanotubes of arbitrary chirality. This model, which we call as the liquid surface model, predicts the energy of a nanotube with relative error less than 1% once its chirality and the total number of atoms a...... the calculated energies we determine the elastic properties of the single-wall carbon nanotubes (Young modulus, curvature constant) and perform a comparison with available experimental measurements and earlier theoretical predictions....

  10. Methods for producing reinforced carbon nanotubes (United States)

    Ren, Zhifen [Newton, MA; Wen, Jian Guo [Newton, MA; Lao, Jing Y [Chestnut Hill, MA; Li, Wenzhi [Brookline, MA


    Methods for producing reinforced carbon nanotubes having a plurality of microparticulate carbide or oxide materials formed substantially on the surface of such reinforced carbon nanotubes composite materials are disclosed. In particular, the present invention provides reinforced carbon nanotubes (CNTs) having a plurality of boron carbide nanolumps formed substantially on a surface of the reinforced CNTs that provide a reinforcing effect on CNTs, enabling their use as effective reinforcing fillers for matrix materials to give high-strength composites. The present invention also provides methods for producing such carbide reinforced CNTs.

  11. Carbon nanotubes: Synthesis, characterization, and applications (United States)

    Deck, Christian Peter

    Carbon nanotubes (CNTs) possess exceptional material properties, making them desirable for use in a variety of applications. In this work, CNTs were grown using two distinct catalytic chemical vapor deposition (CVD) procedures, floating catalyst CVD and thermal CVD, which differed in the method of catalyst introduction. Reaction conditions were optimized to synthesize nanotubes with desired characteristics, and the effects of varying growth parameters were studied. These parameters included gas composition, temperature, reaction duration, and catalyst and substrate material. The CNT products were then examined using several approaches. For each CVD method, nanotube growth rates were determined and the formation and termination mechanisms were investigated. The effects of reaction parameters on nanotube diameters and morphology were also explored to identify means of controlling these important properties. In addition to investigating the effects of different growth parameters, the material properties of nanotubes were also studied. The floating catalyst CVD method produced thick mats of nanotubes, and the mechanical response of these samples was examined using in-situ compression and tension testing. These results indicated that mat structure is composed of discontinuous nanotubes, and a time-dependent response was also observed. In addition, the electrical resistance of bulk CNT samples was found to increase for tubes grown with higher catalyst concentrations and with bamboo morphologies. The properties of nanotubes synthesized using thermal CVD were also examined. Mechanical testing was performed using the same in-situ compression approach developed for floating catalyst CVD samples. A second characterization method was devised, where an optical approach was used to measure the deflection of patterned nanotubes exposed to an applied fluid flow. This response was also simulated, and comparisons with the experimental data were used to determine the flexural

  12. How to suppress obsessive thoughts. (United States)

    Rassin, Eric; Diepstraten, Philip


    Thought suppression (i.e. consciously trying to avoid certain thoughts from entering consciousness) has been argued to be an inadequate strategy in case of unwanted intrusions. That is, thought suppression seems to result in more rather than less intrusions. Although this experimental finding has been explained in terms of failing attempts to distract oneself from the target thought, the White Bear Suppression Inventory (WBSI; a scale that measures chronic thought suppression tendencies) does not address the means by which respondents try to suppress unwanted thoughts. To examine which strategies of mental control people use to suppress unwanted thoughts, obsessive-compulsive disorder patients (N=47) completed the WBSI, the Thought Control Questionnaire, and two measures of psychopathology. Results suggest that the crucial mechanism in thought suppression may not be distraction, but self-punishment.

  13. Potassium Capture by Kaolin, Part 1: KOH

    DEFF Research Database (Denmark)

    Wang, Guoliang; Jensen, Peter Arendt; Wu, Hao


    The reaction of gaseous KOH with kaolin and mullite powder under suspension-fired conditions was studied by entrained flow reactor (EFR) experiments. A water-based slurry containing kaolin/mullite and KOH was fed into the reactor and the reacted solid samples were analyzed to quantify the K...... 1100°C, but lower conversion was observed at 800 and 900 °C. Crystalline kaliophilite (KAlSiO4) was formed at higher temperatures (1300 and 1450 °C), whereas, amorphous K-aluminosilicate was formed at lower temperatures. Coarse kaolin (D50 = 13.48 μm) captured KOH less effectively than normal (D50 = 5.......47 μm) and fine(D50 = 3.51 μm) kaolin powder at1100 and 1300 °C. The difference was less significant at 900°C. Mullite generated from kaolin captured KOH less effectively than kaolin at temperatures below 1100 °C. However, at 1300 and1450 °C, the amount of potassium captured by mullite became comparable...

  14. Control of potassium excretion: a Paleolithic perspective. (United States)

    Halperin, Mitchell L; Cheema-Dhadli, Surinder; Lin, Shih-Hua; Kamel, Kamel S


    Regulation of potassium (K) excretion was examined in an experimental setting that reflects the dietary conditions for humans in Paleolithic times (high, episodic intake of K with organic anions; low intake of NaCl), because this is when major control mechanisms were likely to have developed. The major control of K secretion in this setting is to regulate the number of luminal K channels in the cortical collecting duct. Following a KCl load, the K concentration in the medullary interstitial compartment rose; the likely source of this medullary K was its absorption by the H/K-ATPase in the inner medullary collecting duct. As a result of the higher medullary K concentration, the absorption of Na and Cl was inhibited in the loop of Henle, and this led to an increased distal delivery of a sufficient quantity of Na to raise K excretion markedly, while avoiding a large natriuresis. In addition, because K in the diet was accompanied by 'future' bicarbonate, a role for bicarbonate in the control of K secretion via 'selecting' whether aldosterone would be a NaCl-conserving or a kaliuretic hormone is discussed. This way of examining the control of K excretion provides new insights into clinical disorders with an abnormal plasma K concentration secondary to altered K excretion, and also into the pathophysiology of calcium-containing kidney stones.

  15. Potassium permanganate for mercury vapor environmental control (United States)

    Kuivinen, D. E.


    Potassium permanganate (KMnO4) was evaluated for application in removing mercury vapor from exhaust air systems. The KMnO4 may be used in water solution with a liquid spray scrubber system or as a solid adsorber bed material when impregnated onto a zeolite. Air samples contaminated with as much as 112 mg/cu m of mercury were scrubbed to 0.06mg/cum with the KMnO4-impregnated zeolite (molecular sieve material). The water spray solution of permanganate was also found to be as effective as the impregnated zeolite. The KMnO4-impregnated zeolite was applied as a solid adsorber material to (1) a hardware decontamination system, (2) a model incinerator, and (3) a high vacuum chamber for ion engine testing with mercury as the propellant. A liquid scrubber system was also applied in an incinerator system. Based on the results of these experiments, it is concluded that the use of KMnO4 can be an effective method for controlling noxious mercury vapor.

  16. Incommensurate lattice modulations in Potassium Vanadate (United States)

    Chakoumakos, Bryan; Banerjee, Arnab; Mark, Lumsden; Cao, Huibo; Kim, Jong-Woo; Hoffman, Christina; Wang, Xiaoping

    Potassium Vanadate (K2V3O8) is an S = 1/2 2D square lattice antiferromagnet that shows spin reorientation indicating a strong coupling between the magnetism and its dielectric properties with a promise of rich physics that promises multiferroicity. These tangible physical properties are strongly tied through a spin-lattice coupling to the underlying lattice and superlattice behavior. It has a superlattice (SL) onsetting below Tc = 115 K with an approximate [3 x 3 x 2] modulation. Here we present our recent experiments at TOPAZ beamline at SNS which for the first time proves conclusively that the lattice modulations are incommensurate, with an in-plane Q of 0.315. We will also show our attempts to refine the data using JANA which requires a redefinition of the lattice, as well as the temperature and Q dependence of the superlattice modulation measured using neutrons at HFIR and synchrotron x-rays at APS. Our results are not only relevant for the ongoing search of multifunctional behavior in K2V3O8 but also generally for the superlattice modulations observed in a large family of fresnoites. Work performed at ORNL and ANL is supported by U.S. Dept. of Energy, Office of Basic Energy Sciences and Office of User Facilities Division.

  17. Discovery of potassium salts deposits in colombia

    International Nuclear Information System (INIS)

    Gonzalez Oviedo Leopoldo; Espinosa Baquero Armando


    The first potassium salts ores found in Colombia are presented and described; they are located in the Santander province, in La Mesa de los Santos area, between Los Santos village and the rio Chicamocha Canyon. From a geological point of view, the mineralization is associated to the sediments of the Paja Formation, Early Cretaceous in age, and is located near the base of the formation. In the study area the main structure is the Villanueva syncline which involves, from bottom to top, Los Santos, Rosablanca, Paja, Tablazo and Simiti formations.The mineralization consists of small veins where the main mineral is singenite (K 2 Ca[SO4] 2- H 2 O) with small amounts of carbonates and accidental minerals. In the host rock, minerals like langbeinite (K 2 Mg 2 [SO4] 3) andrinneite (K 3 Na[Fe,Cl] 6) are present; they show that the rock was formed in an evaporitic environment and that detailed studies of that sequence may lead to the discovery of other mineralizations of economic interest.

  18. Implementation and evaluation of a nurse-centered computerized potassium regulation protocol in the intensive care unit - a before and after analysis

    NARCIS (Netherlands)

    Hoekstra, Miriam; Vogelzang, Mathijs; Drost, Jose T.; Janse, Marcel; Loef, Bert G.; van der Horst, Iwan C. C.; Zijlstra, Felix; Nijsten, Maarten W. N.


    Background: Potassium disorders can cause major complications and must be avoided in critically ill patients. Regulation of potassium in the intensive care unit (ICU) requires potassium administration with frequent blood potassium measurements and subsequent adjustments of the amount of potassium

  19. Potassium-phosphorus relationships in cotton (gossypium hirsutum L.) as affected by potassium nutrition

    International Nuclear Information System (INIS)

    Makhdum, M.I.; Ashraf, M.


    Field studies were undertaken to determine the interrelationship between potassium (K+) concentration in various organs of plant and phosphorus (P) content as influenced by K-nutrition in cotton. The experiment was conducted on Miani soil series silt loam and classified as Calcaric Cambisols, fine silty, mixed Hyperthermic Fluventic Haplocambids. The treatments consisted .of (a) four cotton (Gossypium hirsutum L.) cultivars (CI.M-448, CIM-IIOO, Karishma, S-12); and (b) four potassium fertilizer doses (0, 62.5, 125.0, 250.0 kg K ha-l). The design of experiment was split plot (main: cultivars, sub-plot: K-doses). The plant samples were collected at five stages of growth, i.e., first flower bud., first flower, peak flowering, first boll split and maturity. The various parts of plants were analyzed for phosphorus and potassium concentration at various stages of growth. Phosphorus concentration in leaves, stems, burs, seed and lint decreased with concurrent increase in K-doses. Crop maintained 0.22% phosphorus concentration in leaf tissues at first flower bud and dropped to 0.11% at maturity. Cultivars differed greatly amongst themselves in terms of maintaining P content in their different parts. Averaged across K-doses, cv. CIM-448 maintained the highest P content in all parts than other cultivars. There was a negative and significant correlation co-efficient between K and P concentration in various parts of the plant. The study demonstrated antagonistic interaction between K+ and P in cotton plant under irrigated conditions. (author)

  20. Efficiency of Nanotube Surface-Treated Dental Implants Loaded with Doxycycline on Growth Reduction of Porphyromonas gingivalis. (United States)

    Ferreira, Cimara Fortes; Babu, Jegdish; Hamlekhan, Azhang; Patel, Sweetu; Shokuhfar, Tolou

    The prevalence of peri-implant infection in patients with dental implants has been shown to range from 28% to 56%. A nanotube-modified implant surface can deliver antibiotics locally and suppress periodontal pathogenic bacterial growth. The aim of this study was to evaluate the deliverability of antibiotics via a nanotube-modified implant. Dental implants with a nanotube surface were fabricated and loaded with doxycycline. Afterward, each dental implant with a nanotube surface was placed into 2-mL tubes, removed from solution, and placed in a fresh solution daily for 28 days. Experimental samples from 1, 2, 4, 16, 24, and 28 days were used for this evaluation. The concentration of doxycycline was measured using spectrophotometric analysis at 273-nm absorbance. The antibacterial effect of doxycycline was evaluated by supplementing Porphyromonas gingivalis (P gingivalis) growth media with the solution collected from the dental implants at the aforementioned time intervals for a period of 48 hours under anaerobic conditions. A bacterial viability assay was used to evaluate P gingivalis growth at 550-nm absorbance. Doxycycline concentration varied from 0.33 to 1.22 μg/mL from day 1 to day 28, respectively. A bacterial viability assay showed the highest P gingivalis growth at day 1 (2 nm) and the lowest at day 4 (0.17 nm), with a gradual reduction from day 1 to day 4 of approximately 87.5%. The subsequent growth pattern was maintained and slightly increased from baseline in approximately 48.3% from day 1 to day 24. The final P gingivalis growth measured at day 28 was 29.4% less than the baseline growth. P gingivalis growth was suppressed in media supplemented with solution collected from dental implants with a nanotube surface loaded with doxycycline during a 28-day time interval.

  1. Multiwall carbon nanotube microcavity arrays

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Rajib; Butt, Haider, E-mail: [Nanotechnology Laboratory, School of Mechanical Engineering, University of Birmingham, Birmingham B15 2TT (United Kingdom); Rifat, Ahmmed A. [Integrated Lightwave Research Group, Department of Electrical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603 (Malaysia); Yetisen, Ali K.; Yun, Seok Hyun [Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, 65 Landsdowne Street, Cambridge, Massachusetts 02139 (United States); Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Dai, Qing [National Center for Nanoscience and Technology, Beijing 100190 (China)


    Periodic highly dense multi-wall carbon nanotube (MWCNT) arrays can act as photonic materials exhibiting band gaps in the visible regime and beyond terahertz range. MWCNT arrays in square arrangement for nanoscale lattice constants can be configured as a microcavity with predictable resonance frequencies. Here, computational analyses of compact square microcavities (≈0.8 × 0.8 μm{sup 2}) in MWCNT arrays were demonstrated to obtain enhanced quality factors (≈170–180) and narrow-band resonance peaks. Cavity resonances were rationally designed and optimized (nanotube geometry and cavity size) with finite element method. Series (1 × 2 and 1 × 3) and parallel (2 × 1 and 3 × 1) combinations of microcavities were modeled and resonance modes were analyzed. Higher order MWCNT microcavities showed enhanced resonance modes, which were red shifted with increasing Q-factors. Parallel microcavity geometries were also optimized to obtain narrow-band tunable filtering in low-loss communication windows (810, 1336, and 1558 nm). Compact series and parallel MWCNT microcavity arrays may have applications in optical filters and miniaturized optical communication devices.

  2. Hydrogen Storage in Carbon Nanotubes (United States)

    Gilbert, Joseph; Gilbert, Matthew; Naab, Fabian; Savage, Lauren; Holland, Wayne; Duggan, Jerome; McDaniel, Floyd


    Hydrogen as a fuel source is an attractive, relatively clean alternative to fossil fuels. However, a major limitation in its use for the application of automobiles has been the requirement for an efficient hydrogen storage medium. Current hydrogen storage systems are: physical storage in high pressure tanks, metal hydride, and gas-on-solid absorption. However, these methods do not fulfill the Department of Energy's targeted requirements for a usable hydrogen storage capacity of 6.5 wt.%, operation near ambient temperature and pressure, quick extraction and refueling, reliability and reusability.Reports showing high capacity hydrogen storage in single-walled carbon nanotubes originally prompted great excitement in the field, but further research has shown conflicting results. Results for carbon nanostructures have ranged from less than 1 wt.% to 70 wt.%. The wide range of adsorption found in previous experiments results from the difficulty in measuring hydrogen in objects just nanometers in size. Most previous experiments relied on weight analysis and residual gas analysis to determine the amount of hydrogen being adsorbed by the CNTs. These differing results encouraged us to perform our own analysis on single-walled (SWNTs), double-walled (DWNTs), and multi-walled carbon nanotubes (MWNTs), as well as carbon fiber. We chose to utilize direct measurement of hydrogen in the materials using elastic recoil detection analysis (ERDA). This work was supported by the National Science Foundation's Research Experience for Undergraduates and the University of North Texas.

  3. Carbon nanotube woven textile photodetector (United States)

    Zubair, Ahmed; Wang, Xuan; Mirri, Francesca; Tsentalovich, Dmitri E.; Fujimura, Naoki; Suzuki, Daichi; Soundarapandian, Karuppasamy P.; Kawano, Yukio; Pasquali, Matteo; Kono, Junichiro


    The increasing interest in mobile and wearable technology demands the enhancement of functionality of clothing through incorporation of sophisticated architectures of multifunctional materials. Flexible electronic and photonic devices based on organic materials have made impressive progress over the past decade, but higher performance, simpler fabrication, and most importantly, compatibility with woven technology are desired. Here we report on the development of a weaved, substrateless, and polarization-sensitive photodetector based on doping-engineered fibers of highly aligned carbon nanotubes. This room-temperature-operating, self-powered detector responds to radiation in an ultrabroad spectral range, from the ultraviolet to the terahertz, through the photothermoelectric effect, with a low noise-equivalent power (a few nW/Hz 1 /2) throughout the range and with a Z T -factor value that is twice as large as that of previously reported carbon nanotube-based photothermoelectric photodetectors. Particularly, we fabricated a ˜1 -m-long device consisting of tens of p+-p- junctions and weaved it into a shirt. This device demonstrated a collective photoresponse of the series-connected junctions under global illumination. The performance of the device did not show any sign of deterioration through 200 bending tests with a bending radius smaller than 100 μ m as well as standard washing and ironing cycles. This unconventional photodetector will find applications in wearable technology that require detection of electromagnetic radiation.

  4. Intracellular mediators of potassium-induced aldosterone secretion

    International Nuclear Information System (INIS)

    Ganguly, A.; Chiou, S.; Davis, J.S.


    We have investigated the intracellular messengers of potassium in eliciting aldosterone secretion in calf adrenal glomerulosa cells since there were unresolved issues relating to the role of phosphoinositides, cAMP and protein kinases. We observed no evidence of hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP 2 ) in 3 H-inositol labeled alf adrenal cells or increase of cAMP in response to potassium. Addition of calcium channel blocker, nitrendipine after stimulating adrenal glomerulosa cells with potassium, markedly inhibited aldosterone secretion. A calmodulin inhibitor (W-7) produced greater reduction of aldosterone secretion than an inhibitor of protein kinase C (H-7). These results suggest that a rise in cytosolic free calcium concentration through voltage-dependent calcium channel and calmodulin are the critical determinants of aldosterone secretion stimulated by potassium

  5. Potassium Ferrate: A Novel Chemical Warfare Agent Decontaminant

    National Research Council Canada - National Science Library

    Greene, Russell; von Fahnestock, F. M; Monzyk, Bruce


    ..., and/or unsatisfactory CWA destruction efficiencies. Potassium ferrate (K2FeO4) addresses all of these issues through its high oxidation potential, stable shelf life, and benign reduced state, namely iron oxide...

  6. Inhibition of large conductance calcium-dependent potassium ...

    African Journals Online (AJOL)

    conductance, calcium and voltage- dependent potassium (BKCa) channels thereby promoting vasoconstriction. Our results show that the Rho-kinase inhibitor, Y-27632, induced concentration-dependent relaxation in rat mesenteric artery.


    Directory of Open Access Journals (Sweden)

    Ana Lúcia Hanisch2


    the highest number of blossom-end rot fruits. It can be concluded that the lowest fertilizer doses in each fertilizer (silicon, nitrogen and potassium result in the highest yield of adequate tomato fruits for processing.

  8. Effects of different cavity‑disinfectants and potassium titanyl ...

    African Journals Online (AJOL)

    disinfectants and potassium titanyl phosphate (KTP) laser on microtensile bond strength to primary dentin. Chlorhexidine (CHX), propolis (PRO), ozonated water (OW), gaseous ozone (OG) and KTP laser were used for this purpose. Methodology: ...

  9. Molecular dynamics simulation of polyacrylamides in potassium montmorillonite clay hydrates

    International Nuclear Information System (INIS)

    Zhang Junfang; Rivero, Mayela; Choi, S K


    We present molecular dynamics simulation results for polyacrylamide in potassium montmorillonite clay-aqueous systems. Interlayer molecular structure and dynamics properties are investigated. The number density profile, radial distribution function, root-mean-square deviation (RMSD), mean-square displacement (MSD) and diffusion coefficient are reported. The calculations are conducted in constant NVT ensembles, at T = 300 K and with layer spacing of 40 A. Our simulation results showed that polyacrylamides had little impact on the structure of interlayer water. Density profiles and radial distribution function indicated that hydration shells were formed. In the presence of polyacrylamides more potassium counterions move close to the clay surface while water molecules move away, indicating that potassium counterions are hydrated to a lesser extent than the system in which no polyacrylamides were added. The diffusion coefficients for potassium and water decreased when polyacrylamides were added

  10. Molecular dynamics simulation of polyacrylamides in potassium montmorillonite clay hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Junfang [CSIRO Petroleum Resources, Ian Wark Laboratory, Bayview Avenue, Clayton, Victoria 3168 (Australia); Rivero, Mayela [CSIRO Petroleum, PO Box 1130, Bentley, Western Australia, 6102 (Australia); Choi, S K [CSIRO Petroleum Resources, Ian Wark Laboratory, Bayview Avenue, Clayton, Victoria 3168 (Australia)


    We present molecular dynamics simulation results for polyacrylamide in potassium montmorillonite clay-aqueous systems. Interlayer molecular structure and dynamics properties are investigated. The number density profile, radial distribution function, root-mean-square deviation (RMSD), mean-square displacement (MSD) and diffusion coefficient are reported. The calculations are conducted in constant NVT ensembles, at T = 300 K and with layer spacing of 40 A. Our simulation results showed that polyacrylamides had little impact on the structure of interlayer water. Density profiles and radial distribution function indicated that hydration shells were formed. In the presence of polyacrylamides more potassium counterions move close to the clay surface while water molecules move away, indicating that potassium counterions are hydrated to a lesser extent than the system in which no polyacrylamides were added. The diffusion coefficients for potassium and water decreased when polyacrylamides were added.

  11. Unihemispheric burst suppression

    Directory of Open Access Journals (Sweden)

    Edward C. Mader Jr.


    Full Text Available Burst suppression (BS consists of bursts of high-voltage slow and sharp wave activity alternating with periods of background suppression in the electroencephalogram (EEG. When induced by deep anesthesia or encephalopathy, BS is bihemispheric and is often viewed as a non-epileptic phenomenon. In contrast, unihemispheric BS is rare and its clinical significance is poorly understood. We describe here two cases of unihemispheric BS. The first patient is a 56-year-old woman with a left temporoparietal tumor who presented in convulsive status epilepticus. EEG showed left hemispheric BS after clinical seizure termination with lorazepam and propofol. The second patient is a 39-year-old woman with multiple medical problems and a vague history of seizures. After abdominal surgery, she experienced a convulsive seizure prompting treatment with propofol. Her EEG also showed left hemispheric BS. In both cases, increasing the propofol infusion rate resulted in disappearance of unihemispheric BS and clinical improvement. The prevailing view that typical bihemispheric BS is non-epileptic should not be extrapolated automatically to unihemispheric BS. The fact that unihemispheric BS was associated with clinical seizure and resolved with propofol suggests that, in both cases, an epileptic mechanism was responsible for unihemispheric BS.

  12. Multiwalled carbon nanotubes-sulfur composites with enhanced electrochemical performance for lithium/sulfur batteries

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Xin Zhou; Jin, Bo, E-mail:; Xin, Pei Ming; Wang, Huan Huan


    Multiwalled carbon nanotubes-sulfur (MWCNTs-S) composites were synthesized by chemical activation of MWCNTs and capillarity between sulfur and MWCNTs. The MWCNTs activated by potassium hydroxide (denoted as K-MWCNTs) were used as conductive additive. The as-prepared K-MWCNTs-S composites can display excellent cycle stability and rate capability with the initial discharge capacity of 741 mAh g⁻¹ and capacity retention of 80% after 50 cycles compared to pure S. The improvement in the electrochemical performance for K-MWCNTs-S composites is attributed to the interstitial structure of the MWCNTs resulted from the strong chemical etching, which can facilitate the insertion and extraction of Li ions and more better percolation of the electrolyte, and also ascribed to enhanced electronic conductivity of K-MWCNTs-S composites. It is indicated that the K-MWCNTs-S composites can be used as the cathode materials for lithium–sulfur batteries.

  13. Nafion Titania Nanotubes Nanocomposite Electrolytes for High-Temperature Direct Methanol Fuel Cells

    Directory of Open Access Journals (Sweden)

    Nonhlanhla Precious Cele


    Full Text Available Nafion-based nanocomposite membranes containing various amounts of titania nanotubes (TNTs as an inorganic filler have been prepared using melt-mixing method and have been investigated for proton exchange membrane applications. The one-dimensional TNTs have been prepared from potassium hydroxide using hydrothermal route and conventional heating. Nafion R1100 in a protonated form was used, and TNT contents were in a range of 0.5–2.0 wt%. The acid-treated composite membranes, at lowest inorganic additive content, exhibited improved properties in terms of thermal stability and methanol (MeOH permeability. The best performing nanocomposite was the membrane containing only 0.5 wt% TNTs showing ionic conductivity value of 7.2×10-2 S·cm-1 at 26°C and 100% of relative humidity.

  14. Changes in plasma potassium concentration during carbon dioxide pneumoperitoneum

    DEFF Research Database (Denmark)

    Perner, A; Bugge, K; Lyng, K M


    Hyperkalaemia with ECG changes had been noted during prolonged carbon dioxide pneumoperitoneum in pigs. We have compared plasma potassium concentrations during surgery in 11 patients allocated randomly to undergo either laparoscopic or open appendectomy and in another 17 patients allocated randomly...... to either carbon dioxide pneumoperitoneum or abdominal wall lifting for laparoscopic colectomy. Despite an increasing metabolic acidosis, prolonged carbon dioxide pneumoperitoneum resulted in only a slight increase in plasma potassium concentrations, which was both statistically and clinically insignificant...

  15. Optimizing potassium ferrate for textile wastewater treatment by RSM

    Directory of Open Access Journals (Sweden)

    Maryam Moradnia


    Full Text Available Background: Application of potassium ferrate is a chemical oxidation approach used for water and wastewater treatment. The aim of this study is to apply central composite design (CCD and response surface methodology (RSM to optimize potassium ferrate consumption in the treatment of wastewater from carpet industries. Methods: Samples in this experimental study were collected from wastewater, originating from a carpet factory. Wastewater sampling was carried out monthly for a period of two seasons. Ferrate oxidation experiments were conducted by means of a conventional jar-test apparatus. The time and speed for mixing were set with an automatic controller. Parameters of study were measured based on given methodologies in Standard method for examining water and wastewater. CCD and RSM were applied to optimize the operating variables including potassium ferrate dosage and pH. Results: Results showed that potassium ferrate concentration (A, pH (B, their interactions (AB and quadratic effects (A2 and B2 were significant in the removal of COD, turbidity, color and TSS from carpet industries effluents. At an optimum point (COD: 160 mg/L of potassium ferrate and pH 4, turbidity: 165 mg/L of potassium ferrate and pH 4, color and TSS: pH 4.5 and 150 mg/L of potassium ferrate removal efficiencies for COD, turbidity, color and TSS were 86, 86, 87 and 89%, respectively. Conclusion: Potassium ferrate has a significant impact on pollutants decomposition and the removal of color from wastewater produced in carpet industries. This process can be employed for the pretreatment or post treatment of wastewaters containing refractory organic pollutants. CCD and RSM are suitable tools for experimental design.

  16. Defoliation height and potassium fertilization of Mulato II grass

    Directory of Open Access Journals (Sweden)

    Carlos Eduardo Avelino Cabral


    Full Text Available A pot trial in greenhouse conditions was carried out to identify at which defoliation height Mulato II grass (Urochloa hibrida cv. Mulato II should be managed and to determine whether potassium fertilization is necessary in soil with high potassium content. The experiment was carried out in a greenhouse in a randomized block design with six treatments and five replications. Treatments consisted of a 3 × 2 factorial arrangement, with three defoliation heights (50, 65, and 80 cm and with or without potassium maintenance fertilization. The production characteristics and chemical composition of the forage plant were evaluated. There was no interaction effect between defoliation height and fertilization with or without potassium on any of the analyzed variables, except for mineral content in Mulato II grass. The tillers and leaves number, shoot dry matter, leaf+sheath, root system, and residue were influenced by defoliation heights and potassium fertilization, except for the leaf blades and root dry matter, leaf blade/stem+sheath ratio, and leaves number, which were not influenced by potassium fertilization. Higher shoot dry matter was observed at the heights of 65 and 80 cm; however, comparing these two heights, leaf + sheath dry matter was lower at 65 cm. Regarding the grass’s chemical composition, there was an increase in neutral and acid detergent fiber and indigestible neutral detergent fiber contents as the defoliation height increased, which resulted in lower production of potentially digestible dry matter, which can compromise the potential use of the forage by animals. Among evaluated treatments, Mulato II grass defoliation is recommended for a maximum height of 65 cm. Potassium fertilization increases the yield and the potentially digestible dry matter content of Mulato II grass, even when cultivated in soil with high potassium content.

  17. Evaluating status change of soil potassium from path model.

    Directory of Open Access Journals (Sweden)

    Wenming He

    Full Text Available The purpose of this study is to determine critical environmental parameters of soil K availability and to quantify those contributors by using a proposed path model. In this study, plot experiments were designed into different treatments, and soil samples were collected and further analyzed in laboratory to investigate soil properties influence on soil potassium forms (water soluble K, exchangeable K, non-exchangeable K. Furthermore, path analysis based on proposed path model was carried out to evaluate the relationship between potassium forms and soil properties. Research findings were achieved as followings. Firstly, key direct factors were soil S, ratio of sodium-potassium (Na/K, the chemical index of alteration (CIA, Soil Organic Matter in soil solution (SOM, Na and total nitrogen in soil solution (TN, and key indirect factors were Carbonate (CO3, Mg, pH, Na, S, and SOM. Secondly, path model can effectively determine direction and quantities of potassium status changes between Exchangeable potassium (eK, Non-exchangeable potassium (neK and water-soluble potassium (wsK under influences of specific environmental parameters. In reversible equilibrium state of [Formula: see text], K balance state was inclined to be moved into β and χ directions in treatments of potassium shortage. However in reversible equilibrium of [Formula: see text], K balance state was inclined to be moved into θ and λ directions in treatments of water shortage. Results showed that the proposed path model was able to quantitatively disclose moving direction of K status and quantify its equilibrium threshold. It provided a theoretical and practical basis for scientific and effective fertilization in agricultural plants growth.

  18. Relationship between Pore Occupancy and Gating in BK Potassium Channels


    Piskorowski, Rebecca A.; Aldrich, Richard W.


    Permeant ions can have significant effects on ion channel conformational changes. To further understand the relationship between ion occupancy and gating conformational changes, we have studied macroscopic and single-channel gating of BK potassium channels with different permeant monovalent cations. While the slopes of the conductance?voltage curve were reduced with respect to potassium for all permeant ions, BK channels required stronger depolarization to open only when thallium was the perm...

  19. Complement activation cascade triggered by PEG-PL engineered nanomedicines and carbon nanotubes: The challenges ahead

    DEFF Research Database (Denmark)

    Moghimi, S.M.; Andersen, Alina Joukainen; Hashemi, S.H.


    reactions to certain PEG-PL engineered nanomedicines in both experimental animals and man. These reactions are classified as pseudoallergy and may be associated with cardiopulmonary disturbance and other related symptoms of anaphylaxis. Recent studies suggest that complement activation may be a contributing......, but not a rate limiting factor, in eliciting hypersensitivity reactions to such nanomedicines in sensitive individuals. This is rather surprising since PEGylated structures are generally assumed to suppress protein adsorption and blood opsonization events including complement. Here, we examine the molecular...... basis of complement activation by PEG-PL engineered nanomedicines and carbon nanotubes and discuss the challenges ahead....

  20. BX CY NZ nanotubes and nanoparticles (United States)

    Cohen, Marvin Lou; Zettl, Alexander Karlwalter


    The invention provides crystalline nanoscale particles and tubes made from a variety of stoichiometries of B.sub.x C.sub.y N.sub.z where x, y, and z indicate a relative amount of each element compared to the others and where no more than one of x, y, or z are zero for a single stoichiometry. The nanotubes and nanoparticles are useful as miniature electronic components, such as wires, coils, schotky barriers, diodes, etc. The nanotubes and nanoparticles are also useful as coating that will protect an item from detection by electromagnetic monitoring techniques like radar. The nanotubes and nanoparticles are additionally useful for their mechanical properties, being comparable in strength and stiffness to the best graphite fibers or carbon nanotubes. The inventive nanoparticles are useful in lubricants and composites.

  1. Epoxy-based carbon nanotubes reinforced composites

    CSIR Research Space (South Africa)

    Kesavan Pillai, Sreejarani


    Full Text Available developed strategy offering promising results is to reinforce epoxy matrices with nano-sized organic and inorganic particles such as carbon nanotubes (CNTs), carbon nanofibres (CNFs), nanoclays, metal oxide nanoparticles, etc. and make new materials...

  2. Enhanced Carbon Nanotube Ultracapacitors, Phase I (United States)

    National Aeronautics and Space Administration — The proposed innovation utilizes carbon nanotubes (CNTs) coated with pseudo-capacitive MnO2 material as nano-composite electrode and ionic electrolyte for the...

  3. Carbon Nanotube Infused Launch Vehicle Structures (United States)

    National Aeronautics and Space Administration — For the past 5 years Orbital ATK has been investing in, prototyping, and testing carbon nanotube infused composite structures to evaluate their impact on launch...

  4. Janus cyclic peptide-polymer nanotubes (United States)

    Danial, Maarten; My-Nhi Tran, Carmen; Young, Philip G.; Perrier, Sébastien; Jolliffe, Katrina A.


    Self-assembled nanotubular structures have numerous potential applications but these are limited by a lack of control over size and functionality. Controlling these features at the molecular level may allow realization of the potential of such structures. Here we report a new generation of self-assembled cyclic peptide-polymer nanotubes with dual functionality in the form of either a Janus or mixed polymeric corona. A ‘relay’ synthetic strategy is used to prepare nanotubes with a demixing or mixing polymeric corona. Nanotube structure is assessed in solution using 1H-1H nuclear Overhauser effect spectroscopy NMR, and in bulk using differential scanning calorimetry. The Janus nanotubes form artificial pores in model phospholipid bilayers. These molecules provide a viable pathway for the development of intriguing nanotubular structures with dual functionality via a demixing or a mixing polymeric corona and may provide new avenues for the creation of synthetic transmembrane protein channel mimics.

  5. Nitrogen in highly crystalline carbon nanotubes

    International Nuclear Information System (INIS)

    Ducati, C; Koziol, K; Stavrinadis, A; Friedrichs, S; Windle, A H; Midgley, P A


    Multiwall carbon nanotubes (MWCNTs) with an unprecedented degree of internal order were synthesised by chemical vapour deposition (CVD) adding a nitrogen-containing compound to the hydrocarbon feedstock. Ferrocene was used as the metal catalyst precursor. The remarkable crystallinity of these nanotubes lies both in the isochirality and in the crystallographic register of their walls, as demonstrated by electron diffraction and high resolution electron microscopy experiments. High resolution transmission electron microscopy analysis shows that the walls of the nanotubes consist of truncated stacked cones, instead of perfect cylinders, with a range of apex angles that appears to be related to the nitrogen concentration in the synthesis process. The structure of armchair, zigzag and chiral nanotubes is modelled and discussed in terms of density of topological defects, providing an interesting comparison with our microscopy experiments. A growth mechanism based on the interplay of base- and tip-growth is proposed to account for our experimental observations

  6. Liquid crystalline order of carbon nanotubes (United States)

    Georgiev, Georgi; Ahlawat, Aditya; Mulkern, Brian; Doyle, Robert; Mongeau, Jennifer; Ogilvie, Alex


    Topological defects formed during phase transitions in liquid crystals provide a direct proof of the standard Cosmological model and are direct links to the Early Universe. On the other hand in Nanotechnology, carbon nanotubes can be manipulated and oriented directly by changing the liquid crystalline state of the nanotubes, in combination with organic liquid crystals. Currently there are no nano-assemblers, which makes the liquid crystal state of the nanotubes, one of the few ways of controlling them. We show the design of a fast and efficient polarized light ellipsometric system (a new modification of previous optical systems) that can provide fast quantitative real time measurements in two dimensions of the formation of topological defects in liquid crystals during phase transitions in lab settings. Our aim is to provide fundamental information about the formation of optically anisotropic structures in liquid crystals and the orientation of carbon nanotubes in electric field.

  7. Carbon nanotube polymer composition and devices (United States)

    Liu, Gao [Oakland, CA; Johnson, Stephen [Richmond, CA; Kerr, John B [Oakland, CA; Minor, Andrew M [El Cerrito, CA; Mao, Samuel S [Castro Valley, CA


    A thin film device and compound having an anode, a cathode, and at least one light emitting layer between the anode and cathode, the at least one light emitting layer having at least one carbon nanotube and a conductive polymer.

  8. Carbon nanotube heat-exchange systems (United States)

    Hendricks, Terry Joseph; Heben, Michael J.


    A carbon nanotube heat-exchange system (10) and method for producing the same. One embodiment of the carbon nanotube heat-exchange system (10) comprises a microchannel structure (24) having an inlet end (30) and an outlet end (32), the inlet end (30) providing a cooling fluid into the microchannel structure (24) and the outlet end (32) discharging the cooling fluid from the microchannel structure (24). At least one flow path (28) is defined in the microchannel structure (24), fluidically connecting the inlet end (30) to the outlet end (32) of the microchannel structure (24). A carbon nanotube structure (26) is provided in thermal contact with the microchannel structure (24), the carbon nanotube structure (26) receiving heat from the cooling fluid in the microchannel structure (24) and dissipating the heat into an external medium (19).

  9. Carbon Nanotube Tower-Based Supercapacitor (United States)

    Meyyappan, Meyya (Inventor)


    A supercapacitor system, including (i) first and second, spaced apart planar collectors, (ii) first and second arrays of multi-wall carbon nanotube (MWCNT) towers or single wall carbon nanotube (SWCNT) towers, serving as electrodes, that extend between the first and second collectors where the nanotube towers are grown directly on the collector surfaces without deposition of a catalyst and without deposition of a binder material on the collector surfaces, and (iii) a porous separator module having a transverse area that is substantially the same as the transverse area of at least one electrode, where (iv) at least one nanotube tower is functionalized to permit or encourage the tower to behave as a hydrophilic structure, with increased surface wettability.

  10. Cylindrical-shaped nanotube field effect transistor

    KAUST Repository

    Hussain, Muhammad Mustafa


    A cylindrical-shaped nanotube FET may be manufactured on silicon (Si) substrates as a ring etched into a gate stack and filled with semiconductor material. An inner gate electrode couples to a region of the gate stack inside the inner circumference of the ring. An outer gate electrode couples to a region of the gate stack outside the outer circumference of the ring. The multi-gate cylindrical-shaped nanotube FET operates in volume inversion for ring widths below 15 nanometers. The cylindrical-shaped nanotube FET demonstrates better short channel effect (SCE) mitigation and higher performance (I.sub.on/ than conventional transistor devices. The cylindrical-shaped nanotube FET may also be manufactured with higher yields and cheaper costs than conventional transistors.

  11. Carbon nanotubes dispersed polymer nanocomposites: mechanical ...

    Indian Academy of Sciences (India)

    Keywords. Carbon nanotubes; nanocomposite; Young's modulus; breakdown strength; dielectric constant; thermal conductivity. 1. Introduction. The polymer composite has material characteristics use- ful for diverse applications such as capacitors and acoustic emission sensors. The nanoscaled fillers are dispersed in po-.

  12. Carbon Nano-Tube (CNT) Reinforced COPV (United States)

    National Aeronautics and Space Administration — Reduce the structural mass of future aerospace vehicles through the development of ultra lightweight materials and structures through the use of: Carbon nanotube...

  13. Thermophoresis of water droplets inside carbon nanotubes

    DEFF Research Database (Denmark)

    Zambrano, Harvey; Walther, Jens Honore; Oyarzua, Elton


    Carbon Nanotubes(CNTs) offer unique possibilities as fluid conduits with applications ranging from lab on a chip devices to encapsulation media for drug delivery. CNTs feature high mechanical strength, chemical and thermalstability and biocompatibility therefore they are promising candidates...

  14. A Thermal Model for Carbon Nanotube Interconnects

    Directory of Open Access Journals (Sweden)

    Clay Mayberry


    Full Text Available In this work, we have studied Joule heating in carbon nanotube based very large scale integration (VLSI interconnects and incorporated Joule heating influenced scattering in our previously developed current transport model. The theoretical model explains breakdown in carbon nanotube resistance which limits the current density. We have also studied scattering parameters of carbon nanotube (CNT interconnects and compared with the earlier work. For 1 µm length single-wall carbon nanotube, 3 dB frequency in S12 parameter reduces to ~120 GHz from 1 THz considering Joule heating. It has been found that bias voltage has little effect on scattering parameters, while length has very strong effect on scattering parameters.

  15. Parathyroid hormone impairs extrarenal potassium tolerance in the rat

    International Nuclear Information System (INIS)

    Sugarman, A.; Kahn, T.


    The effect of parathyroid hormone (PTH) on the extrarenal disposition of an acute potassium load was examined in acutely nephrectomized rats infused with KCl alone or in combination with PTH, with serial monitoring of plasma potassium every 10 min. The rise in plasma potassium concentration (ΔPK) in the PTH group was higher than control. PTH was then administered along with KCl to two groups of nephrectomized and acutely thyroparathyroidectomized (TPTX) rats in doses of 1 and 0.25 U · kg -1 · min -1 for 90 min. ΔPK with PTH in both groups was higher than TPTX control. The two higher doses of PTH resulted in a decrease in mean arterial pressure from their respective controls. A similar reduction in arterial pressure in three groups of nephrectomized rats by administration of hydralazine or nitroprusside or by acute blood loss did not change ΔPK subsequent to potassium infusion from that in control rats. Furthermore, the lowest dose of PTH did not lower arterial pressure from its respective control. Therefore, hypotension is not a cause for the PTH-induced potassium intolerance. Serum levels of insulin, aldosterone, catecholamines, calcium, plasma HCO 3 concentration, and pH were not different in PTH-infused vs. respective control rats. These data suggest that PTH impairs extrarenal potassium disposal in the rat. The effect of PTH may relate to enhanced calcium entry into cells

  16. Potassium Organic Salts as Burn Additives in Cigarettes

    Directory of Open Access Journals (Sweden)

    Liu C


    Full Text Available Three potassium salts of organic acids, namely malate, citrate and tartrate, have been sprayed onto flue-cured blend tobacco and subsequently tested for their performance as burn additives in cigarettes. In one experiment where potassium malate was added to vary the final tobacco potassium from ca. 3.1% to 8.3% (wet weight, an almost linearly reduction in puff temperature was measured. This was accompanied by a gradual increase in the cigarette's pressure drop. In another set of experiments where the final tobacco potassium contents were increased to ca. 5.1%, the three potassium salts showed almost equal reduction in the mainstream nicotine-free-dry-particulate-matter (NFDPM at 32-35%, nicotine at 25-32% and carbon monoxide at 24-35%. Puff number showed ca. 23% increase with malate, 13% with citrate and almost unchanged for tartrate. Evidence of melting and coating by potassium malate was discovered in cigarette ash by scanning electron microscopy (SEM. This contributed to a noticeable change in ash morphology: small ash particles appeared to be coated and more tightly bonded together by the melt. This phenomenon was thought to be able to restrict the airflow during puffing, hence causing the measured increase in pressure drop, and the reductions in puff temperature, NFDPM, nicotine and carbon monoxide.

  17. Potassium-doped n-type bilayer graphene (United States)

    Yamada, Takatoshi; Okigawa, Yuki; Hasegawa, Masataka


    Potassium-doped n-type bilayer graphene was obtained. Chemical vapor deposited bilayer and single layer graphene on copper (Cu) foils were used. After etching of Cu foils, graphene was dipped in potassium hydroxide aqueous solutions to dope potassium. Graphene on silicon oxide was characterized by X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDX), and Raman spectroscopy. Both XPS and EDX spectra indicated potassium incorporation into the bilayer graphene via intercalation between the graphene sheets. The downward shift of the 2D peak position of bilayer graphene after the potassium hydroxide (KOH) treatment was confirmed in Raman spectra, indicating that the KOH-treated bilayer graphene was doped with electrons. Electrical properties were measured using Hall bar structures. The Dirac points of bilayer graphene were shifted from positive to negative by the KOH treatment, indicating that the KOH-treated bilayer graphene was n-type conduction. For single layer graphene after the KOH treatment, although electron doping was confirmed from Raman spectra, the peak of potassium in the X-ray photoelectron spectroscopy (XPS) spectrum was not detected. The Dirac points of single layer graphene with and without the KOH treatment showed positive.

  18. Variable Potassium Concentrations: Which Is Right and Which Is Wrong? (United States)

    Theparee, Talent; Benirschke, Robert C; Lee, Hong-Kee


    Reverse pseudohyperkalemia is a term used to describe in vitro, falsely elevated potassium concentrations in plasma specimens that occur in association with extreme leukocytosis and are commonly associated with hematologic malignant neoplasms. Tumor lysis syndrome is an in vivo lysis of tumor cells that leads to elevated levels of potassium, uric acid, phosphate, and lactate dehydrogenase, as well as decreased calcium concentrations. Herein, we report a case of a 66-year-old Caucasian man with stage IV mantle-cell lymphoma who has elevated levels of potassium, uric acid, and phosphorus, as well as a white blood cell (WBC) count greater than 100,000 cells per mm3. The patient initially was diagnosed as having tumor lysis syndrome. His subsequent potassium concentrations in whole blood remained elevated even after hemodialysis; however, his serum potassium concentrations were decreased. The patient then was diagnosed accurately as having reverse pseudohyperkalemia, and accurate potassium measurements were obtained via serum specimens. © American Society for Clinical Pathology, 2017. All rights reserved. For permissions, please e-mail:

  19. The relationship between serum potassium, potassium variability and in-hospital mortality in critically ill patients and a before-after analysis on the impact of computer-assisted potassium control

    NARCIS (Netherlands)

    Hessels, Lara; Hoekstra, Miriam; Mijzen, Lisa J.; Vogelzang, Mathijs; Dieperink, Wim; Oude Lansink, Annemieke; Nijsten, Maarten W.


    Introduction: The relationship between potassium regulation and outcome is not known. Our first aim in the present study was to determine the relationship between potassium level and variability in (ICU) stay and outcome. The second aim was to evaluate the impact of a computer-assisted potassium

  20. Electrochemical biosensing based on polypyrrole/titania nanotube hybrid

    International Nuclear Information System (INIS)

    Xie, Yibing; Zhao, Ye


    The glucose oxidase (GOD) modified polypyrrole/titania nanotube enzyme electrode is fabricated for electrochemical biosensing application. The titania nanotube array is grown directly on a titanium substrate through an anodic oxidation process. A thin film of polypyrrole is coated onto titania nanotube array to form polypyrrole/titania nanotube hybrid through a normal pulse voltammetry process. GOD-polypyrrole/titania nanotube enzyme electrode is prepared by the covalent immobilization of GOD onto polypyrrole/titania nanotube hybrid via the cross-linker of glutaraldehyde. The morphology and microstructure of nanotube electrodes are characterized by field emission scanning electron microscopy and Fourier transform infrared analysis. The biosensing properties of this nanotube enzyme electrode have been investigated by means of cyclic voltammetry and chronoamperometry. The hydrophilic polypyrrole/titania nanotube hybrid provides highly accessible nanochannels for GOD encapsulation, presenting good enzymatic affinity. As-formed GOD-polypyrrole/titania nanotube enzyme electrode well conducts bioelectrocatalytic oxidation of glucose, exhibiting a good biosensing performance with a high sensitivity, low detection limit and wide linear detection range. - Graphical abstract: The schematic diagram presents the fabrication of glucose oxidase modified polypyrrole/titania (GOD-PPy/TiO 2 ) nanotube enzyme electrode for biosensing application. - Highlights: • Hydrophilic polypyrrole/titania nanotube hybrid is well used as biosensing substrate. • Polypyrrole promotes GOD immobilization on titania nanotubes via glutaraldehyde. • GOD-polypyrrole/titania enzyme electrode shows good bioelectrocatalytic reactivity

  1. Multiwalled Carbon Nanotubes Reinforced Polypropylene Composite Material

    Directory of Open Access Journals (Sweden)

    Juan Li


    Full Text Available Polypropylene (PP composites reinforced with multiwalled carbon nanotubes (MWNTs were prepared by using twin screw extruder. The experimental results showed that with the increasing amount of MWNTs the elongation at break decreased whereas the tensile strength, bending strength, and impact strength increased. By using scanning electron microscope (SEM, we find that the hydroxyl-modified carbon nanotube has better dispersion performance in PP and better mechanical properties.

  2. Carbon nanotube temperature and pressure sensors (United States)

    Ivanov, Ilia N; Geohegan, David Bruce


    The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

  3. Controlled Deposition and Alignment of Carbon Nanotubes (United States)

    Smits, Jan M. (Inventor); Wincheski, Russell A. (Inventor); Patry, JoAnne L. (Inventor); Watkins, Anthony Neal (Inventor); Jordan, Jeffrey D. (Inventor)


    A carbon nanotube (CNT) attraction material is deposited on a substrate in the gap region between two electrodes on the substrate. An electric potential is applied to the two electrodes. The CNT attraction material is wetted with a solution defined by a carrier liquid having carbon nanotubes (CNTs) suspended therein. A portion of the CNTs align with the electric field and adhere to the CNT attraction material. The carrier liquid and any CNTs not adhered to the CNT attraction material are then removed.

  4. Carbon nanotube temperature and pressure sensors

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Ilia N.; Geohegan, David B.


    The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

  5. Attophysics of Thermal Phenomena in Carbon Nanotubes


    Kozlowski, Miroslaw; Marciak-Kozlowska, Janina


    In this paper heat transport in carbon nanotubes is investigated. When the dimension of the structure is of the order of the de Broglie wave length transport phenomena must be analysed by quantum mechanics. In this paper we derived the Dirac type thermal equation .The solution of the equation for the temperature fields for electrons can either be damped or can oscillate depending on the dynamics of the scattering. Key words: Carbon nanotubes, ultrashort laser pulses, Dirac thermal equation, t...

  6. Carbon nanotube temperature and pressure sensors

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Ilia N.; Geohegan, David B.


    The present invention, in one embodiment, provides a method of measuring pressure or temperature using a sensor including a sensor element composed of a plurality of carbon nanotubes. In one example, the resistance of the plurality of carbon nanotubes is measured in response to the application of temperature or pressure. The changes in resistance are then recorded and correlated to temperature or pressure. In one embodiment, the present invention provides for independent measurement of pressure or temperature using the sensors disclosed herein.

  7. Ocular Injury due to Potassium Permanganate Granules

    Directory of Open Access Journals (Sweden)

    Chareenun Chirapapaisan


    Full Text Available Purpose: We report a rare case of ocular injury due to potassium permanganate (KMnO4 granules in a child. Methods: This is a retrospective case report. Results: A 2-year-old boy was transferred to our emergency room with severe pain in his right eye, inflamed eyelids, and brownish stains on his fingers. Chemical injury was suspected. Copious eye irrigation was immediately performed. Diffuse brownish splotches were then observed at the inferior bulbar conjunctiva. Otherwise, systemic organs were intact. Complete eye exam under general anesthesia revealed a 5-mm epithelial defect at the central cornea, along with generalized conjunctival injection and limbal ischemia, inferiorly. Multiple semi-dissolved granules of KMnO4 trapped in the inferior fornix were identified. The chemical particles were gradually washed out and removed; however, the brownish stains remained. The patient received preservative-free steroid, antibiotic eye drops, and lubricants as regular management for mild to moderate degree of ocular burn. Pseudomembrane developed early and transformed into symblepharon within a few days after the injury. Membrane adhesion was lysed, and more aggressive medications were then substituted. Commercial amniotic membrane (PROKERA® was also applied to promote wound healing and to prevent recurrence of symblepharon. The ocular surface was eventually restored, and corneal transparency was preserved. Conclusion: Ocular injury with the granular form of KMnO4 is rare. Its toxicity is comparable to concentrated KMnO4 solution. However, the dissolved particles that had been absorbed in the stained conjunctiva were continuously released and damaged the ocular surface more than we primarily anticipated. Awareness of this condition and prompt management yield a good treatment outcome.

  8. Printing nanotube/nanowire for flexible microsystems (United States)

    Tortorich, Ryan P.; Choi, Jin-Woo


    Printing has become an emerging manufacturing technology for mechanics, electronics, and consumer products. Additionally, both nanotubes and nanowires have recently been used as materials for sensors and electrodes due to their unique electrical and mechanical properties. Printed electrodes and conductive traces particularly offer versatility of fabricating low-cost, disposable, and flexible electrical devices and microsystems. While various printing methods such as screen printing have been conventional methods for printing conductive traces and electrodes, inkjet printing has recently attracted great attention due to its unique advantages including no template requirement, rapid printing at low cost, on-demand printing capability, and precise control of the printed material. Computer generated conductive traces or electrode patterns can simply be printed on a thin film substrate with proper conductive ink consisting of nanotubes or nanowires. However, in order to develop nanotube or nanowire ink, there are a few challenges that need to be addressed. The most difficult obstacle to overcome is that of nanotube/nanowire dispersion within a solution. Other challenges include adjusting surface tension and controlling viscosity of the ink as well as treating the surface of the printing substrate. In an attempt to pave the way for nanomaterial inkjet printing, we present a method for preparing carbon nanotube ink as well as its printing technique. A fully printed electrochemical sensor using inkjet-printed carbon nanotube electrodes is also demonstrated as an example of the possibilities for this technology.

  9. Carbon Nanotube-Based Synthetic Gecko Tapes (United States)

    Dhinojwala, Ali


    Wall-climbing geckos have unique ability to attach to different surfaces without the use of any viscoelastic glues. On coming in contact with any surface, the micron-size gecko foot-hairs deform, enabling molecular contact over large areas, thus translating weak van der Waals (vdW) interactions into enormous shear forces. We will present our recent results on the development of synthetic gecko tape using aligned carbon nanotubes to mimic the keratin hairs found on gecko feet. The patterned carbon nanotube-based gecko tape can support a shear stress (36 N/cm^2) nearly four times higher than the gecko foot and sticks to a variety of surfaces, including Teflon. Both the micron-size setae (replicated by nanotube bundles) and nanometer-size spatulas (individual nanotubes) are necessary to achieve macroscopic shear adhesion and to translate the weak vdW interactions into high shear forces. The carbon nanotube based tape offers an excellent synthetic option as a dry conductive reversible adhesive in microelectronics, robotics and space applications. The mechanism behind these large shear forces and self-cleaning properties of these carbon nanotube based synthetic gecko tapes will be discussed. This work was performed in collaboration with graduate students Liehui Ge, and Sunny Sethi, and collaborators from RPI; Lijie Ci and Professor Pulickel Ajayan.

  10. Polymerization initated at sidewalls of carbon nanotubes (United States)

    Tour, James M. (Inventor); Hudson, Jared L. (Inventor); Krishnamoorti, Ramanan (Inventor); Yurekli, Koray (Inventor); Mitchell, Cynthia A. (Inventor)


    The present invention is directed to aryl halide (such as aryl bromide) functionalized carbon nanotubes that can be utilized in anionic polymerization processes to form polymer-carbon nanotube materials with improved dispersion ability in polymer matrices. In this process the aryl halide is reacted with an alkyllithium species or is reacted with a metal to replace the aryl-bromine bond with an aryl-lithium or aryl-metal bond, respectively. It has further been discovered that other functionalized carbon nanotubes, after deprotonation with a deprotonation agent, can similarly be utilized in anionic polymerization processes to form polymer-carbon nanotube materials. Additionally or alternatively, a ring opening polymerization process can be performed. The resultant materials can be used by themselves due to their enhanced strength and reinforcement ability when compared to their unbound polymer analogs. Additionally, these materials can also be blended with pre-formed polymers to establish compatibility and enhanced dispersion of nanotubes in otherwise hard to disperse matrices resulting in significantly improved material properties. The resultant polymer-carbon nanotube materials can also be used in drug delivery processes due to their improved dispersion ability and biodegradability, and can also be used for scaffolding to promote cellular growth of tissue.

  11. Thermal expansion producing easier formation of a black phosphorus nanotube from nanoribbon on carbon nanotube (United States)

    Cao, Jing; Cai, Kun


    As a novel one-dimensional material having excellent electrical properties, a black phosphorus (BP) nanotube has wide potential applications in nanodevices. A BP nanotube has not yet, however, been discovered in experiments or fabricated via chemical synthesis. In this study, the feasibility of forming a nanotube from a parallelogram nanoribbon upon a carbon nanotube (CNT) at different temperatures is discussed through the use of molecular dynamics simulations. Results obtained demonstrate that an ideal BP nanotube from the same nanoribbon can be obtained via self-assembly on a CNT at 50 K or lower temperature. At temperatures between 50-100 K, the BP nanotube formed from a single ribbon has defects at both ends. When the temperature is higher than 100 K, it is difficult to obtain a BP nanotube of high quality. It is discovered that when the ribbon can only wind upon the same CNT at low temperature, it may form into an ideal nanotube by increasing the temperature of the system. The reason is that the BP ribbon has a higher thermal expansion than the CNT under the same temperature difference.

  12. Nanotube structures, methods of making nanotube structures, and methods of accessing intracellular space (United States)

    VanDersarl, Jules J.; Xu, Alexander M.; Melosh, Nicholas A.; Tayebi, Noureddine


    In accordance with the purpose(s) of the present disclosure, as embodied and broadly described herein, embodiments of the present disclosure, in one aspect, relate to methods of making a structure including nanotubes, a structure including nanotubes, methods of delivering a fluid to a cell, methods of removing a fluid to a cell, methods of accessing intracellular space, and the like.

  13. Suppression of sympathetic detonation (United States)

    Foster, J. C., Jr.; Gunger, M. E.; Craig, B. G.; Parsons, G. H.


    There are two basic approaches to suppression of sympathetic detonation. Minimizing the shock sensitivity of the explosive to long duration pressure will obviously reduce interround separation distances. However, given that the explosive sensitivity is fixed, then much can be gained through the use of simple barriers placed between the rounds. Researchers devised calculational methods for predicting shock transmission; experimental methods have been developed to characterize explosive shock sensitivity and observe the response of acceptors to barriers. It was shown that both EAK and tritonal can be initiated to detonation with relatively low pressure shocks of long durations. It was also shown that to be an effective barrier between the donor and acceptor, the material must attenuate shock and defect fragments. Future actions will concentrate on refining the design of barriers to minimize weight, volume, and cost.

  14. Ketone deprotonation mediated by mono- and heterobimetallic alkali and alkaline earth metal amide bases: structural characterization of potassium, calcium, and mixed potassium-calcium enolates. (United States)

    He, Xuyang; Noll, Bruce C; Beatty, Alicia; Mulvey, Robert E; Henderson, Kenneth W


    Potassium, calcium, and mixed potassium-calcium amide combinations have been shown to be efficient reagents in enolization reactions, and a set of representative intermediate mono- and heterobimetallic enolates have been successfully isolated and crystallographically characterized.

  15. General hypothesis and shell model for the synthesis of semiconductor nanotubes, including carbon nanotubes (United States)

    Mohammad, S. Noor


    Semiconductor nanotubes, including carbon nanotubes, have vast potential for new technology development. The fundamental physics and growth kinetics of these nanotubes are still obscured. Various models developed to elucidate the growth suffer from limited applicability. An in-depth investigation of the fundamentals of nanotube growth has, therefore, been carried out. For this investigation, various features of nanotube growth, and the role of the foreign element catalytic agent (FECA) in this growth, have been considered. Observed growth anomalies have been analyzed. Based on this analysis, a new shell model and a general hypothesis have been proposed for the growth. The essential element of the shell model is the seed generated from segregation during growth. The seed structure has been defined, and the formation of droplet from this seed has been described. A modified definition of the droplet exhibiting adhesive properties has also been presented. Various characteristics of the droplet, required for alignment and organization of atoms into tubular forms, have been discussed. Employing the shell model, plausible scenarios for the formation of carbon nanotubes, and the variation in the characteristics of these carbon nanotubes have been articulated. The experimental evidences, for example, for the formation of shell around a core, dipole characteristics of the seed, and the existence of nanopores in the seed, have been presented. They appear to justify the validity of the proposed model. The diversities of nanotube characteristics, fundamentals underlying the creation of bamboo-shaped carbon nanotubes, and the impurity generation on the surface of carbon nanotubes have been elucidated. The catalytic action of FECA on growth has been quantified. The applicability of the proposed model to the nanotube growth by a variety of mechanisms has been elaborated. These mechanisms include the vapor-liquid-solid mechanism, the oxide-assisted growth mechanism, the self

  16. Growth of ZnO nanotube arrays and nanotube based piezoelectric nanogenerators

    KAUST Repository

    Xi, Yi


    We present a systematic study of the growth of hexagonal ZnO nanotube arrays using a solution chemical method by varying the growth temperature (<100 °C), time and solution concentration. A piezoelectric nanogenerator using the as-grown ZnO nanotube arrays has been demonstrated for the first time. The nanogenerator gives an output voltage up to 35 mV. The detailed profile of the observed electric output is understood based on the calculated piezoelectric potential in the nanotube with consideration of the Schottky contact formed between the metal tip and the nanotube; and the mechanism agrees with that proposed for nanowire based nanogenerator. Our study shows that ZnO nanotubes can also be used for harvesting mechanical energy. © 2009 The Royal Society of Chemistry.

  17. Release characteristics of selected carbon nanotube polymer composites (United States)

    Multi-walled carbon nanotubes (MWCNTs) are commonly used in polymer formulations to improve strength, conductivity, and other attributes. A developing concern is the potential for carbon nanotube polymer nanocomposites to release nanoparticles into the environment as the polymer ...

  18. A Review: Carbon Nanotube-Based Piezoresistive Strain Sensors

    Directory of Open Access Journals (Sweden)

    Waris Obitayo


    Full Text Available The use of carbon nanotubes for piezoresistive strain sensors has acquired significant attention due to its unique electromechanical properties. In this comprehensive review paper, we discussed some important aspects of carbon nanotubes for strain sensing at both the nanoscale and macroscale. Carbon nanotubes undergo changes in their band structures when subjected to mechanical deformations. This phenomenon makes them applicable for strain sensing applications. This paper signifies the type of carbon nanotubes best suitable for piezoresistive strain sensors. The electrical resistivities of carbon nanotube thin film increase linearly with strain, making it an ideal material for a piezoresistive strain sensor. Carbon nanotube composite films, which are usually fabricated by mixing small amounts of single-walled or multiwalled carbon nanotubes with selected polymers, have shown promising characteristics of piezoresistive strain sensors. Studies also show that carbon nanotubes display a stable and predictable voltage response as a function of temperature.

  19. Methods for Gas Sensing with Single-Walled Carbon Nanotubes (United States)

    Kaul, Anupama B. (Inventor)


    Methods for gas sensing with single-walled carbon nanotubes are described. The methods comprise biasing at least one carbon nanotube and exposing to a gas environment to detect variation in temperature as an electrical response.

  20. Applications of Nanotubes in Electronic and Nanomechanical Devices

    National Research Council Canada - National Science Library

    Tomanek, David


    ... as their potential for energy storage. Our research helps to better understand nanotube properties in case of chemically and structurally modified nanotubes consisting of carbon and boron nitride, including multi-wall systems and peapods...

  1. Defect complexes in carbon and boron nitride nanotubes

    CSIR Research Space (South Africa)

    Mashapa, MG


    Full Text Available The effect of defect complexes on the stability, structural and electronic properties of single-walled carbon nanotubes and boron nitride nanotubes is investigated using the ab initio pseudopotential density functional method implemented...

  2. Carbon nanotubes attenuate cancer and improve healing (United States)

    Wailes, Elizabeth Marguerite

    Breast cancer is the most common cancer in American women and the second largest cause of their cancer mortality. Resection of the primary tumor can greatly improve the prognosis, but if any of the cancerous cells remain, the patient is still at risk. This work investigates the ability of high aspect ratio nanoparticles to both heal injured tissue and attenuate cancer cells' aggression. To assess different particles' utility, carbon nanoparticles were evaluated in a fibroblast and collagen gel model of wound contraction, then polymeric nanoparticles were synthesized and tested similarly. The carbon particles, multi-walled nanotubes (MWNT) in particular, performed the best, strongly inhibiting pathological wound contraction, increasing cell viability, and decreasing reactive oxygen species. Later, carbon nanoparticle coatings with or without collagen were tested with breast cancer cells to assess adhesion, migration, and E-cadherin expression of the cells. The collagen-MWNT coatings were able to increase cancer cell adhesion to their substrate, decrease migration, increase E-cadherin expression, and also increase autophagy. The coatings effected all these changes without increasing proliferation of the cancer cells or affecting non-tumorigenic breast cells. To examine how these two sets of results might act together, co-cultures were then created with both fibroblasts and cancer cells in collagen gels with or without MWNT. The cells' movement and matrix metalloproteinase (MMP) expression were measured to gauge the cells' interaction in that environment, as fibroblasts can encourage or suppress metastasis depending on their behavior. The MWNT were able to decrease cancer cell movement, particularly their invasion into the gel, and selectively promote cancer cell death without harming the non-tumorigenic cells. They also decreased MMP expression. Finally, early in vivo work was undertaken to determine how the collagen-nanoparticle gels are able to control cancer in

  3. Carbon Nanotube Tape Vibrating Gyroscope (United States)

    Tucker, Dennis Stephen (Inventor)


    A vibrating gyroscope includes a piezoelectric strip having length and width dimensions. The piezoelectric strip includes a piezoelectric material and carbon nanotubes (CNTs) substantially aligned and polled along the strip's length dimension. A spindle having an axis of rotation is coupled to the piezoelectric strip. The axis of rotation is parallel to the strip's width dimension. A first capacitance sensor is mechanically coupled to the spindle for rotation therewith. The first capacitance sensor is positioned at one of the strip's opposing ends and is spaced apart from one of the strip's opposing faces. A second capacitance sensor is mechanically coupled to the spindle for rotation therewith. The second capacitance sensor is positioned at another of the strip's opposing ends and is spaced apart from another of the strip's opposing faces. A voltage source applies an AC voltage to the piezoelectric strip.

  4. Carbon nanotubes based vacuum gauge (United States)

    Rudyk, N. N.; Il’in, O. I.; Il’ina, M. V.; Fedotov, A. A.; Klimin, V. S.; Ageev, O. A.


    We have created an ionization type Vacuum gauge with sensor element based on an array of vertically aligned carbon nanotubes. Obtained asymmetrical current-voltage characteristics at different voltage polarity on the electrode with the CNTs. It was found that when applying a negative potential on an electrode with the CNTs, the current in the gap is higher than at a positive potential. In the pressure range of 1 ÷ 103 Torr vacuum gauge sensitivity was 6 mV/Torr (at a current of 4.5·10-5 A) and in the range of 10-5 ÷ 1 Torr was 10 mV/Torr (at a current of 1.3·10-5 A). It is shown that the energy efficiency of vacuum gauge can be increased in the case where electrode with CNT operates as an emitter of electrons.

  5. Functionalized carbon nanotubes: biomedical applications (United States)

    Vardharajula, Sandhya; Ali, Sk Z; Tiwari, Pooja M; Eroğlu, Erdal; Vig, Komal; Dennis, Vida A; Singh, Shree R


    Carbon nanotubes (CNTs) are emerging as novel nanomaterials for various biomedical applications. CNTs can be used to deliver a variety of therapeutic agents, including biomolecules, to the target disease sites. In addition, their unparalleled optical and electrical properties make them excellent candidates for bioimaging and other biomedical applications. However, the high cytotoxicity of CNTs limits their use in humans and many biological systems. The biocompatibility and low cytotoxicity of CNTs are attributed to size, dose, duration, testing systems, and surface functionalization. The functionalization of CNTs improves their solubility and biocompatibility and alters their cellular interaction pathways, resulting in much-reduced cytotoxic effects. Functionalized CNTs are promising novel materials for a variety of biomedical applications. These potential applications are particularly enhanced by their ability to penetrate biological membranes with relatively low cytotoxicity. This review is directed towards the overview of CNTs and their functionalization for biomedical applications with minimal cytotoxicity. PMID:23091380

  6. Evaluating the effect of potassium on cellulose pyrolysis reaction kinetics

    International Nuclear Information System (INIS)

    Trendewicz, Anna; Evans, Robert; Dutta, Abhijit; Sykes, Robert; Carpenter, Daniel; Braun, Robert


    This paper proposes modifications to an existing cellulose pyrolysis mechanism in order to include the effect of potassium on product yields and composition. The changes in activation energies and pre-exponential factors due to potassium were evaluated based on the experimental data collected from pyrolysis of cellulose samples treated with different levels of potassium (0–1% mass fraction). The experiments were performed in a pyrolysis reactor coupled to a molecular beam mass spectrometer (MBMS). Principal component analysis (PCA) performed on the collected data revealed that cellulose pyrolysis products could be divided into two groups: anhydrosugars and other fragmentation products (hydroxyacetaldehyde, 5-hydroxymethylfurfural, acetyl compounds). Multivariate curve resolution (MCR) was used to extract the time resolved concentration score profiles of principal components. Kinetic tests revealed that potassium apparently inhibits the formation of anhydrosugars and catalyzes char formation. Therefore, the oil yield predicted at 500 ° C decreased from 87.9% from cellulose to 54.0% from cellulose with 0.5% mass fraction potassium treatment. The decrease in oil yield was accompanied by increased yield of char and gases produced via a catalyzed dehydration reaction. The predicted char and gas yield from cellulose were 3.7% and 8.4%, respectively. Introducing 0.5% mass fraction potassium treatment resulted in an increase of char yield to 12.1% and gas yield to 33.9%. The validation of the cellulose pyrolysis mechanism with experimental data from a fluidized-bed reactor, after this correction for potassium, showed good agreement with our results, with differences in product yields of up to 5%

  7. Influence of Potassium on Sapric Peat under Different Environmental Conditions (United States)

    Tajuddin, Syafik Akmal Mohd; Rahman, Junita Abdul; Rahim, Nor Haakmal Abd; Saphira Radin Mohamed, Radin Maya; Saeed Abduh Algheethi, Adel Ali, Dr


    Potassium is mainly present in soil in the natural form known as the K-bearing mineral. Potassium is also available in fertilizer as a supplement to plants and can be categorized as macronutrient. The application of potassium improves the texture and structure of the soil beside to improves plant growth. The main objective of this study was to determine the concentration of potassium in sapric peat under different conditions. Physical model was used as a mechanism for the analysis of the experimental data using a soil column as an equipment to produce water leaching. In this investigation, there were four outlets in the soil column which were prepared from the top of the column to the bottom with the purpose of identifying the concentration of potassium for each soil level. The water leaching of each outlet was tested using atomic absorption spectroscopy (AAS). The results obtained showed that the highest concentrations of potassium for flush condition at outlet 4 was 13.58 ppm. Similarly, sapric under rainwater condition recorded the highest value of 13.32 and 12.34 ppm respectively at outlet 4 for wet and dry condition. However, the difference in Sapric, rainwater and fertilizer category showed that the highest value for the wet condition was achieved at outlet 2 with 13.99 ppm while highest value of 14.82 ppm was obtained for the dry condition at the outlet 3. It was concluded that the outlets in the soil column gave a detailed analysis of the concentration of potassium in the soil which was influenced by the environmental conditions.

  8. Methods Reduce Cost, Enhance Quality of Nanotubes (United States)


    For all the challenges posed by the microgravity conditions of space, weight is actually one of the more significant problems NASA faces in the development of the next generation of U.S. space vehicles. For the Agency s Constellation Program, engineers at NASA centers are designing and testing new vessels as safe, practical, and cost-effective means of space travel following the eventual retirement of the space shuttle. Program components like the Orion Crew Exploration Vehicle, intended to carry astronauts to the International Space Station and the Moon, must be designed to specific weight requirements to manage fuel consumption and match launch rocket capabilities; Orion s gross liftoff weight target is about 63,789 pounds. Future space vehicles will require even greater attention to lightweight construction to help conserve fuel for long-range missions to Mars and beyond. In order to reduce spacecraft weight without sacrificing structural integrity, NASA is pursuing the development of materials that promise to revolutionize not only spacecraft construction, but also a host of potential applications on Earth. Single-walled carbon nanotubes are one material of particular interest. These tubular, single-layer carbon molecules - 100,000 of them braided together would be no thicker than a human hair - display a range of remarkable characteristics. Possessing greater tensile strength than steel at a fraction of the weight, the nanotubes are efficient heat conductors with metallic or semiconductor electrical properties depending on their diameter and chirality (the pattern of each nanotube s hexagonal lattice structure). All of these properties make the nanotubes an appealing material for spacecraft construction, with the potential for nanotube composites to reduce spacecraft weight by 50 percent or more. The nanotubes may also feature in a number of other space exploration applications, including life support, energy storage, and sensor technologies. NASA s various

  9. Selective Functionalization of Carbon Nanotubes: Part II (United States)

    Meyyappan, Meyya; Khare, Bishun


    An alternative method of low-temperature plasma functionalization of carbon nanotubes provides for the simultaneous attachment of molecular groups of multiple (typically two or three) different species or different mixtures of species to carbon nanotubes at different locations within the same apparatus. This method is based on similar principles, and involves the use of mostly the same basic apparatus, as those of the methods described in "Low-Temperature Plasma Functionalization of Carbon Nanotubes" (ARC-14661-1), NASA Tech Briefs, Vol. 28, No. 5 (May 2004), page 45. The figure schematically depicts the basic apparatus used in the aforementioned method, with emphasis on features that distinguish the present alternative method from the other. In this method, one exploits the fact that the composition of the deposition plasma changes as the plasma flows from its source in the precursor chamber toward the nanotubes in the target chamber. As a result, carbon nanotubes mounted in the target chamber at different flow distances (d1, d2, d3 . . .) from the precursor chamber become functionalized with different species or different mixtures of species. In one series of experiments to demonstrate this method, N2 was used as the precursor gas. After the functionalization process, the carbon nanotubes from three different positions in the target chamber were examined by Fourier-transform infrared spectroscopy to identify the molecular groups that had become attached. On carbon nanotubes from d1 = 1 cm, the attached molecular groups were found to be predominantly C-N and C=N. On carbon nanotubes from d2 = 2.5 cm, the attached molecular groups were found to be predominantly C-(NH)2 and/or C=NH2. (The H2 was believed to originate as residual hydrogen present in the nanotubes.) On carbon nanotubes from d3 = 7 cm no functionalization could be detected - perhaps, it was conjectured, because this distance is downstream of the plasma source, all of the free ions and free radicals of

  10. Gas transport in aluminosilicate nanotubes by diffusion NMR


    Dvoyashkin, Muslim; Wood, Ryan; Bowers, Clifford R.; Yucelen, Ipek; Nair, Sankar; Katihar, Aakanksha; Vasenkov, Sergey


    Diffusion of tetrafluoromethane in aluminosilicate nanotubes was studied by means of 13C pulsed field gradient (PFG) NMR at 297 K. The measured data allow the estimation of the diffusivity of tetrafluoromethane inside the nanotubes as well as the diffusivity for these molecules undergoing fast exchange between many nanotubes. The results support the assumption about the one-dimensional nature of the tetrafluoromethane diffusion inside nanotubes.

  11. Synthesis of silver impregnated carbon nanotubes and cyclodextrin ...

    African Journals Online (AJOL)

    Synthesis of silver impregnated carbon nanotubes and cyclodextrin polyurethanes for the disinfection of water. L.P Lukhele, R Krause, B Mamba, M Momba. Abstract. Silver impregnated carbon nanotubes and cyclodextrin polymers were synthesised by first functionalising carbon nanotubes in a mixture of nitric and ...

  12. Filled and empty states of carbon nanotubes in water: Dependence ...

    Indian Academy of Sciences (India)

    Filled and empty states of carbon nanotubes in water: Dependence on nanotube diameter, wall thickness and dispersion interactions. Malay Rana ... The thickness of the nanotube wall, however, is found to have only minor effects on the density profiles, hydrogen bond network and the wetting characteristics. This indicates ...

  13. On Young's modulus of multi-walled carbon nanotubes

    Indian Academy of Sciences (India)


    ssion electron microscopy of carbon nanotube/aluminum nanocomposites is given to calculate approximately the. Young's modulus of multi-walled carbon nanotubes. 2. Experimental. Multi-walled carbon nanotubes (MWCNTs) were synthe- sized by arc discharge technique with 20 V d.c. and 100 amps current. The CNT/Al ...

  14. Effect of aligned carbon nanotubes on electrical conductivity ...

    Indian Academy of Sciences (India)

    continuing networks while direct current electric field only prevented agglomeration of the carbon nanotubes in the polycarbonate matrix and created relatively uniform distribution of nanotubes in the matrix. Keywords. Carbon nanotube; nanocomposite; electrical effect; magnetic effect. 1. Introduction. To reinforce materials ...

  15. Method for synthesis of titanium dioxide nanotubes using ionic liquids (United States)

    Qu, Jun; Luo, Huimin; Dai, Sheng


    The invention is directed to a method for producing titanium dioxide nanotubes, the method comprising anodizing titanium metal in contact with an electrolytic medium containing an ionic liquid. The invention is also directed to the resulting titanium dioxide nanotubes, as well as devices incorporating the nanotubes, such as photovoltaic devices, hydrogen generation devices, and hydrogen detection devices.

  16. Mechanics of Carbon Nanotubes and their Polymer Composites (United States)

    Wei, Chenyu; Cho, K. J.; Srivastava, Deepak; Tang, Harry (Technical Monitor)


    Contents include the folloving: carbon nanotube (CNT): structures, application of carbon nanotubes, simulation method, Elastic properties of carbon nanotubes, yield strain of CNT, yielding under tensile stress, yielding: strain-rate and temperature dependence, yield strain under tension, yielding at realistic conditions, nano fibers, polymer CNT composite, force field, density dependency on temperature, diffusion coefficients, young modulus, and conclusions.

  17. Synthesis of single wall carbon nanotubes from a lamellar type ...

    Indian Academy of Sciences (India)


    These nanotubes are applicable to store more hydrogen. Keywords. AlPO4-L; single wall carbon nanotubes. 1. Introduction. Carbon nanotubes (Iijima 1991) are nano-scale structures formed by self assembly. They possess excellent chemical and physical properties (Rodney and Donald 1995; Chen et al 1998) that make ...

  18. Metallic/semiconducting ratio of carbon nanotubes in a bundle ...

    Indian Academy of Sciences (India)

    Iijima and Ichihashi [1], much efforts have been devoted to improve the methods of nanotube production, and significant progress has been made to narrow the diame- ter distribution of nanotubes produced by different catalysts and growth processes. [2]. The symmetry and electronic properties of carbon nanotubes depend ...

  19. Immobilization of redox mediators on functionalized carbon nanotube

    Indian Academy of Sciences (India)

    Chemical functionalization of single-walled carbon nanotubes with redox mediators, namely, toluidine blue and thionin have been carried out and the performance of graphite electrode modified with functionalized carbon nanotubes is described. Mechanical immobilization of functionalized single-walled nanotube (SWNT) ...

  20. Production and Characterization of Carbon Nanotubes and Nanotube-Based Composites (United States)

    Nikolaev, Pavel; Arepalli, Sivaram; Holmes, William; Gorelik, Olga; Files, Brad; Scott, Carl; Santos, Beatrice; Mayeaux, Brian; Victor, Joe


    The Nobel Prize winning discovery of the Buckuball (C60) in 1985 at Rice University by a group including Dr. Richard Smalley led to the whole new class of carbon allotropes including fullerenes and nanotubes. Especially interesting from many viewpoints are single-walled carbon nanotubes, which structurally are like a single graphitic sheet wrapped around a cylinder and capped at the ends. This cylinders have diameter as small as 0.5 - 2 nm (1/100,000th the diameter of a human hair) and are as long as 0.1 - 1 mm. Nanotubes are really individual molecules and believed to be defect-free, leading to high tensile strength despite their low density. Additionally, these fibers exhibit electrical conductivity as high as copper, thermal conductivity as high as diamond, strength 100 times higher than steel at one-sixth the weight, and high strain to failure. Thus it is believed that developments in the field of nanotechnology will lead to stronger and lighter composite materials for next generation spacecraft. Lack of a bulk method of production is the primary reason nanotubes are not used widely today. Toward this goal JSC nanotube team is exploring three distinct production techniques: laser ablation, arc discharge and chemical vapor deposition (CVD, in collaboration with Rice University). In laser ablation technique high-power laser impinges on the piece of carbon containing small amount of catalyst, and nanotubes self-assemble from the resulting carbon vapor. In arc generator similar vapor is created in arc discharge between carbon electrodes with catalyst. In CVD method nanotubes grow at much lower temperature on small catalyst particles from carbon-containing feedstock gas (methane or carbon monoxide). As of now, laser ablation produces cleanest material, but mass yield is rather small. Arc discharge produces grams of material, but purity is low. CVD technique is still in baby steps, but preliminary results look promising, as well as perspective of scaling the process

  1. Carbon nanotube ecotoxicity in amphibians: assessment of multiwalled carbon nanotubes and comparison with double-walled carbon nanotubes. (United States)

    Mouchet, Florence; Landois, Perine; Puech, Pascal; Pinelli, Eric; Flahaut, Emmanuel; Gauthier, Laury


    The potential impact of industrial multiwalled carbon nanotubes (MWNTs) was investigated under normalized laboratory conditions according to the International Standard micronucleus assay ISO 21427-1 for 12 days of half-static exposure to 0.1, 1, 10 and 50 mg/l of MWNTs in water. Three different end points were carried out for 12 days of exposure: mortality, growth inhibition and micronuclei induction in erythrocytes of the circulating blood of larvae. Raman spectroscopy analysis was used to study the presence of carbon nanotubes in the biological samples. Considering the high diversity of carbon nanotubes according to their different characteristics, MWNTs were analyzed in Xenopus larvae, comparatively to double-walled carbon nanotubes used in a previous study in similar conditions. Growth inhibition in larvae exposed to 50 mg/l of MWNTs was evidenced; however, no genetoxicity (micronucleus assay) was noticed, at any concentration. Carbon nanotube localization in the larvae leads to different possible hypothesis of mechanisms explaining toxicity in Xenopus.

  2. An Alternative to Thought Suppression? (United States)

    Boice, Robert


    Comments on the original article, "Setting free the bears: Escape from thought suppression," by D. M. Wegner (see record 2011-25622-008). While Wegner supposed that we might have to learn to live with bad thoughts, the present author discusses the use of imagination and guided imagery as an alternative to forced thought suppression.

  3. Urinary potassium to urinary potassium plus sodium ratio can accurately identify hypovolemia in nephrotic syndrome: a provisional study. (United States)

    Keenswijk, Werner; Ilias, Mohamad Ikram; Raes, Ann; Donckerwolcke, Raymond; Walle, Johan Vande


    There is evidence pointing to a decrease of the glomerular filtration rate (GFR) in a subgroup of nephrotic children, likely secondary to hypovolemia. The aim of this study is to validate the use of urinary potassium to the sum of potassium plus sodium ratio (UK/UK+UNa) as an indicator of hypovolemia in nephrotic syndrome, enabling detection of those patients who will benefit from albumin infusion. We prospectively studied 44 nephrotic children and compared different parameters to a control group (36 children). Renal perfusion and glomerular permeability were assessed by measuring clearance of para-aminohippurate and inulin. Vaso-active hormones and urinary sodium and potassium were also measured. Subjects were grouped into low, normal, and high GFR groups. In the low GFR group, significantly lower renal plasma flow (p = 0.01), filtration fraction (p = 0.01), and higher UK/UK+UNa (p = 0.03) ratio were noted. In addition, non-significant higher plasma renin activity (p = 0.11) and aldosteron (p = 0.09) were also seen in the low GFR group. A subgroup of patients in nephrotic syndrome has a decrease in glomerular filtration, apparently related to hypovolemia which likely can be detected by a urinary potassium to potassium plus sodium ratio > 0.5-0.6 suggesting benefit of albumin infusion in this subgroup. What is Known: • Volume status can be difficult to assess based on clinical parameters in nephrotic syndrome, and albumin infusion can be associated with development of pulmonary edema and fluid overload in these patients. What is New: • Urinary potassium to the sum of urinary potassium plus sodium ratio can accurately detect hypovolemia in nephrotic syndrome and thus identify those children who would probably respond to albumin infusion.

  4. Nano zero-valent iron impregnated on titanium dioxide nanotube array film for both oxidation and reduction of methyl orange. (United States)

    Yun, Dong-Min; Cho, Hyun-Hee; Jang, Jun-Won; Park, Jae-Woo


    Here, we demonstrated that nano zero-valent iron (nZVI) impregnated onto self-organized TiO(2) nanotube thin films exhibits both oxidation and reduction capacities in addition to the possible electron transfer from TiO(2) to nZVI. The TiO(2) nanotubes were synthesized by anodization of titanium foil in a two-electrode system. Amorphous TiO(2) (amTiO(2)) nanotubes were annealed at 450 °C for 1 h to produce crystalline TiO(2) (crTiO(2)) nanotubes. The nZVI particles were immobilized on the TiO(2) array film by direct borohydride reduction. Field emission scanning electron microscopy (FE-SEM) analysis of the crystalline TiO(2) nanotube with nZVI (nZVI/crTiO(2)) indicated that the nZVI particles with a mean particle diameter of 28.38 ± 11.81 nm were uniformly distributed onto entire crTiO(2) nanotube surface with a mean pore diameter of 75.24 ± 17.66 nm and a mean length of 40.07 μm. Environmental applicability of our proposed nZVI/TiO(2) nanotube thin films was tested for methyl orange (MO) degradation in the aqueous system with and without oxygen. Since oxygen could facilitate the nZVI oxidation and inhibit electron transfer from crTiO(2) to nZVI surface, MO degradation by nZVI/crTiO(2) in the presence of oxygen was significantly suppressed whereas nZVI/crTiO(2) in the absence of oxygen enhanced MO degradation. MO degradation rate by each sample without oxygen were in following order: nZVI/crTiO(2) (k(obs) = 0.311 min(-1)) > nZVI/amTiO(2) (k(obs) = 0.164 min(-1)) > crTiO(2) (k(obs) = 0.068 min(-1)). This result can be explained with a synergistic effect of the significant reduction by highly-dispersed nZVI particles on TiO(2) nanotubes as well as the electron transfer from the conduction band of crTiO(2) to the nZVI on the crTiO(2) for the degradation of MO. Copyright © 2013 Elsevier Ltd. All rights reserved.

  5. Soil salinity and yield of mango fertigated with potassium sources

    Directory of Open Access Journals (Sweden)

    Marcio A. Carneiro

    Full Text Available ABSTRACT Irrigated fruit crops have an important role in the economic and social aspects in the region of the Sub-middle São Francisco River Valley. Thus, the aim of this study was to evaluate soil salinity and the productive aspects of the mango crop, cv. Tommy Atkins, fertigated with doses of potassium chloride (KCl and potassium sulfate (K2SO4 during two crop cycles (from January to March 2014 and from January to March 2015. The experiment was carried out in a strip-split-plot design and five potassium doses (50, 75, 100, 125 and 150% of the recommended dose as plots and two potassium sources (KCl and K2SO4 as subplots, with four replicates. Soil electrical conductivity (EC, exchangeable sodium (Na+ and potassium (K+ contents and pH were evaluated. In addition, the number of commercial fruits and yield were determined. The fertilization with KCl resulted in higher soil EC compared with K2SO4 fertigation. Soil Na+ and K+ contents increased with increasing doses of fertilizers. K2SO4 was more efficient for the production per plant and yield than KCl. Thus, under the conditions of this study, the K2SO4 dose of 174.24 g plant-1 (24.89 kg ha-1 or 96.8% of recommendation, spacing of 10 x 7 m was recommended for a yield of 23.1 t ha-1 of mango fruits, cv. Tommy Atkins.

  6. Unidirectional potassium fluxes in renal distal tubule: effects of chloride and barium

    International Nuclear Information System (INIS)

    Ellison, D.H.; Velazquez, H.; Wright, F.S.


    Low luminal concentrations of chloride stimulate net potassium secretion by the renal distal tubule, independent of changes in transepithelial voltage. These effects are not prevented by the luminal application of the potassium channel blocking agent barium. Because net potassium secretion comprises secretory and absorptive components, we sought to evaluate the effects of chloride and barium on unidirectional potassium fluxes in the renal distal tubule. In vivo microperfusion methods were used in anesthetized Sprague-Dawley rats. Perfusion solutions contained either 42 K or 86 Rb as tracers for potassium. Tracer efflux coefficients, indicating apparent potassium permeability, were similar when measured using either isotope. Net potassium flux was determined as the difference between perfusion and collected rate, and unidirectional absorptive potassium flux was calculated as the product of the mean luminal potassium concentration and the tracer efflux coefficient. During perfusion with a solution that resembled fluid normally arriving at the early distal tubule, the absorptive potassium flux was approximately 25% of the unidirectional secretory flux. Reducing lumen chloride concentration increased net potassium secretion, because blood-to-lumen potassium flux increased from 61 +/- 12.7 to 96 +/- 14.6 pmol/min. Barium reduced both absorptive and secretory fluxes but did not prevent the stimulation of net potassium secretion that occurs when luminal chloride concentration is reduced. Apparent potassium permeability during perfusion with a solution that resembled fluid normally arriving at the early distal tubule was 800 nm/s when corrected for voltage

  7. Mesoscale mechanics of twisting carbon nanotube yarns. (United States)

    Mirzaeifar, Reza; Qin, Zhao; Buehler, Markus J


    Fabricating continuous macroscopic carbon nanotube (CNT) yarns with mechanical properties close to individual CNTs remains a major challenge. Spinning CNT fibers and ribbons for enhancing the weak interactions between the nanotubes is a simple and efficient method for fabricating high-strength and tough continuous yarns. Here we investigate the mesoscale mechanics of twisting CNT yarns using full atomistic and coarse grained molecular dynamics simulations, considering concurrent mechanisms at multiple length-scales. To investigate the mechanical response of such a complex structure without losing insights into the molecular mechanism, we applied a multiscale strategy. The full atomistic results are used for training a coarse grained model for studying larger systems consisting of several CNTs. The mesoscopic model parameters are updated as a function of the twist angle, based on the full atomistic results, in order to incorporate the atomistic scale deformation mechanisms in larger scale simulations. By bridging across two length scales, our model is capable of accurately predicting the mechanical behavior of twisted yarns while the atomistic level deformations in individual nanotubes are integrated into the model by updating the parameters. Our results focused on studying a bundle of close packed nanotubes provide novel mechanistic insights into the spinning of CNTs. Our simulations reveal how twisting a bundle of CNTs improves the shear interaction between the nanotubes up to a certain level due to increasing the interaction surface. Furthermore, twisting the bundle weakens the intertube interactions due to excessive deformation in the cross sections of individual CNTs in the bundle.

  8. Chemical reactions confined within carbon nanotubes. (United States)

    Miners, Scott A; Rance, Graham A; Khlobystov, Andrei N


    In this critical review, we survey the wide range of chemical reactions that have been confined within carbon nanotubes, particularly emphasising how the pairwise interactions between the catalysts, reactants, transition states and products of a particular molecular transformation with the host nanotube can be used to control the yields and distributions of products of chemical reactions. We demonstrate that nanoscale confinement within carbon nanotubes enables the control of catalyst activity, morphology and stability, influences the local concentration of reactants and products thus affecting equilibria, rates and selectivity, pre-arranges the reactants for desired reactions and alters the relative stability of isomeric products. We critically evaluate the relative advantages and disadvantages of the confinement of chemical reactions inside carbon nanotubes from a chemical perspective and describe how further developments in the controlled synthesis of carbon nanotubes and the incorporation of multifunctionality are essential for the development of this ever-expanding field, ultimately leading to the effective control of the pathways of chemical reactions through the rational design of multi-functional carbon nanoreactors.

  9. Radionuclides incorporation in activated natural nanotubes

    International Nuclear Information System (INIS)

    Silva, Jose Parra


    Natural palygorskite nanotubes show suitable physical and chemical properties and characteristics to be use as potential nanosorbent and immobilization matrix for the concentration and solidification of radionuclides present in nuclear wastes. In the development process of materials with sorption properties for the incorporation and subsequent immobilization of radionuclides, the most important steps are related with the generation of active sites simultaneously to the increase of the specific surface area and suitable heat treatment to producing the structural folding. This study evaluated the determining parameters and conditions for the activation process of the natural palygorskite nanotubes aiming at the sorption of radionuclides in the nanotubes structure and subsequent evaluation of the parameters involve in the structural folding by heat treatments. The optimized results about the maximum sorption capacity of nickel in activated natural nanotubes show that these structures are apt and suitable for incorporation of radionuclides similar to nickel. By this study is verified that the optimization of the acid activation process is fundamental to improve the sorption capacities for specifics radionuclides by activated natural nanotubes. Acid activation condition optimized maintaining structural integrity was able to remove around 33.3 wt.% of magnesium cations, equivalent to 6.30·10 -4 g·mol -1 , increasing in 42.8% the specific surface area and incorporating the same molar concentration of nickel present in the liquid radioactive waste at 80 min. (author)

  10. Test Requirements and Conceptual Design for a Potassium Test Loop to Support an Advanced Potassium Rankine Cycle Power Conversion Systems

    Energy Technology Data Exchange (ETDEWEB)

    Yoder, JR.G.L.


    Parameters for continuing the design and specification of an experimental potassium test loop are identified in this report. Design and construction of a potassium test loop is part of the Phase II effort of the project ''Technology Development Program for an Advanced Potassium Rankine Power Conversion System''. This program is supported by the National Aeronautics and Space Administration. Design features for the potassium test loop and its instrumentation system, specific test articles, and engineered barriers for ensuring worker safety and protection of the environment are described along with safety and environmental protection requirements to be used during the design process. Information presented in the first portion of this report formed the basis to initiate the design phase of the program; however, the report is a living document that can be changed as necessary during the design process, reflecting modifications as additional design details are developed. Some portions of the report have parameters identified as ''to be determined'' (TBD), reflecting the early stage of the overall process. In cases where specific design values are presently unknown, the report attempts to document the quantities that remain to be defined in order to complete the design of the potassium test loop and supporting equipment.

  11. Carbon nanotube based stationary phases for microchip chromatography

    DEFF Research Database (Denmark)

    Mogensen, Klaus Bo; Kutter, Jörg Peter


    The objective of this article is to provide an overview and critical evaluation of the use of carbon nanotubes and related carbon-based nanomaterials for microchip chromatography. The unique properties of carbon nanotubes, such as a very high surface area and intriguing adsorptive behaviour, have...... integrated, tailor-made nanotube columns by means of catalytic growth of the nanotubes inside the fluidic channels. An evaluation of the different implementations of carbon nanotubes and related carbon-based nanomaterials for microfluidic chromatography devices is given in terms of separation performance...

  12. Shear Flow Induced Alignment of Carbon Nanotubes in Natural Rubber

    Directory of Open Access Journals (Sweden)

    Yan He


    Full Text Available A new procedure for the fabrication of natural rubber composite with aligned carbon nanotubes is provided in this study. The two-step approach is based on (i the preparation of mixture latex of natural rubber, multiwalled carbon nanotubes, and other components and (ii the orientation of carbon nanotubes by a flow field. Rubber composite sheets filled with variable volume fraction of aligned carbon nanotubes were fabricated and then confirmed by transmission electron microscopy and Raman spectroscopy studies. An obvious increase in thermal conductivity has been obtained after the alignment of carbon nanotubes. The dynamic mechanical analysis was carried out in a tear mode for the composite.

  13. Geckolike high shear strength by carbon nanotube fiber adhesives (United States)

    Maeno, Y.; Nakayama, Y.


    Carbon nanotube adhesives can adhere strongly to surfaces as a gecko does. The number of carbon nanotube layers is an important determinant of the contact area for adhesion. Balancing the catalyst ratio and buffer layer used for chemical vapor deposition processing controls the number of carbon nanotube layers and their distribution. The features of carbon nanotubes determine the shear strength of adhesion. Carbon nanotubes with a broad distribution of layers exhibit enhanced shear strength with equivalent adhesive capability to that of a natural Tokay Gecko (Gekko gecko)

  14. Symmetry Properties of Single-Walled BC2N Nanotubes

    Directory of Open Access Journals (Sweden)

    Lin Jianyi


    Full Text Available Abstract The symmetry properties of the single-walled BC2N nanotubes were investigated. All the BC2N nanotubes possess nonsymmorphic line groups. In contrast with the carbon and boron nitride nanotubes, armchair and zigzag BC2N nanotubes belong to different line groups, depending on the index n (even or odd and the vector chosen. The number of Raman- active phonon modes is almost twice that of the infrared-active phonon modes for all kinds of BC2N nanotubes.

  15. Nanomechanics of Individual Carbon Nanotubes from Pyrolytically Grown Arrays (United States)

    Gao, Ruiping; Wang, Zhong L.; Bai, Zhigang; de Heer, Walter A.; Dai, Liming; Gao, Mei


    The bending modulus of individual carbon nanotubes from aligned arrays grown by pyrolysis was measured by in situ electromechanical resonance in transmission electron microscopy (TEM). The bending modulus of nanotubes with point defects was ~30 GPa and that of nanotubes with volume defect was 2-3 GPa. The time-decay constant of nanotube resonance in a vacuum of 10-4 Torr was ~85 μs. A femtogram nanobalance was demonstrated based on nanotube resonance; it has the potential for measuring the mass of chain-structured large molecules. The in situ TEM provides a powerful approach towards nanomechanics of fiberlike nanomaterials with well-characterized defect structures.

  16. Radiation Doses to Hanford Workers from Natural Potassium-40

    International Nuclear Information System (INIS)

    Strom, Daniel J.; Lynch, Timothy P.; Weier, Dennis R.


    The chemical element potassium is an essential mineral in people and is subject to homeostatic regulation. Natural potassium comprises three isotopes, 39K, 40K, and 41K. Potassium-40 is radioactive, with a half life of 1.248 billion years. In most transitions, it emits a ?- particle with a maximum energy of 0.560 MeV, and sometimes a gamma photon of 1.461 MeV. Because it is ubiquitous, 40K produces radiation dose to all human beings. This report contains the results of new measurements of 40K in 248 adult females and 2,037 adult males performed at the Department of Energy Hanford Site in 2006 and 2007. Potassium concentrations diminish with age, are generally lower in women than in men, and decrease with body mass index (BMI). The average annual effective dose from 40K in the body is 0.149 mSv y?1 for men and 0.123 mSv y?1 women respectively. Averaged over both men and women, the average effective dose per year is 0.136 mSv y?1. Calculated effective doses range from 0.069 to 0.243 mSv y?1 for adult males, and 0.067 to 0.203 mSv y?1 for adult females, a roughly three-fold variation for each gender. The need for dosimetric phantoms with a greater variety of BMI values should be investigated. From our data, it cannot be determined whether the potassium concentration in muscle in people with large BMI values differs from that in people with small BMI values. Similarly, it would be important to know the potassium concentration in other soft tissues, since much of the radiation dose is due to beta radiation, in which the source and target tissues are the same. These uncertainties should be evaluated to determine their consequences for dosimetry

  17. Optogenetic techniques for the study of native potassium channels

    Directory of Open Access Journals (Sweden)

    Guillaume Eric Sandoz


    Full Text Available Optogenetic tools were originally designed to target specific neurons for remote control of their activity by light and have largely been built around opsin-based channels and pumps. These naturally photosensitive opsins are microbial in origin and are unable to mimic the properties of native neuronal receptors and channels. Over the last 8 years, photoswitchable-tethered ligands (PTLs have enabled fast and reversible control of mammalian ion channels, allowing optical control of neuronal activity. One such PTL, MAQ, contains a maleimide (M to tether the molecule to a genetically engineered cysteine, a photoisomerizable azobenzene (A linker and a pore-blocking quaternary ammonium group (Q. MAQ was originally used to photo-control SPARK, an engineered light-gated potassium channel derived from Shaker. Potassium channel photo-block by MAQ has recently been extended to a diverse set of mammalian potassium channels including channels in the voltage-gated and K2P families. Photoswitchable potassium channels, which maintain native properties, pave the way for the optical control of specific aspects of neuronal function and for high precision probing of a specific channel’s physiological functions. To extend optical control to natively expressed channels, without overexpression, one possibility is to develop a knock-in mouse in which the wild type channel gene is replaced by its light-gated version. Alternatively, the recently developed photoswitchable-conditional-subunit technique (PCS provides photocontrol of the channel of interest by molecular replacement of wild type complexes. Finally, photochromic ligands (PCLs also allow photocontrol of potassium channels without genetic manipulation using soluble compounds. In this review we discuss different techniques for optical control of native potassium channels and their associated advantages and disadvantages.

  18. Preparation of aligned nanotube membranes for water and gas separation applications (United States)

    Lulevich, Valentin; Bakajin, Olgica; Klare, Jennifer E.; Noy, Aleksandr


    Fabrication methods for selective membranes that include aligned nanotubes can advantageously include a mechanical polishing step. The nanotubes have their ends closed off during the step of infiltrating a polymer precursor around the nanotubes. This prevents polymer precursor from flowing into the nanotubes. The polishing step is performed after the polymer matrix is formed, and can open up the ends of the nanotubes.

  19. Carbon nanotube suspensions, dispersions, & composites (United States)

    Simmons, Trevor John

    Carbon Nanotubes (CNTs) are amazing structures that hold the potential to revolutionize many areas of scientific research. CNTs can be behave both as semiconductors and metals, can be grown in highly ordered arrays and patterns or in random orientation, and can be comprised of one graphene cylinder (single wall nanotube, SWNT) or several concentric graphene cylinders (multi-wall nanotube, MWNT). Although these structures are usually only a few nanometers wide, they can be grown up to centimeter lengths, and in massive quantities. CNTs can be produced in a variety of processes ranging from repeated combustion of organic material such as dried grass, arc-discharge with graphite electrodes, laser ablation of a graphitic target, to sophisticated chemical vapor deposition (CVD) techniques. CNTs are stronger than steel but lighter than aluminum, and can be more conductive than copper or semiconducting like silicon. This variety of properties has been matched by the wide variety of applications that have been developed for CNTs. Many of these applications have been limited by the inability of researchers to tame these structures, and incorporating CNTs into existing technologies can be exceedingly difficult and prohibitively expensive. It is therefore the aim of the current study to develop strategies for the solution processing and deposition of CNTs and CNT-composites, which will enable the use of CNTs in existing and emerging technologies. CNTs are not easily suspended in polar solvents and are extremely hydrophobic materials, which has limited much of the solution processing to organic solvents, which also cannot afford high quality dispersions of CNTs. The current study has developed a variety of aqueous CNT solutions that employ surfactants, water-soluble polymers, or both to create suspensions of CNTs. These CNT 'ink' solutions were deposited with a variety of techniques that have afforded many interesting structures, both randomly oriented as well as highly

  20. Potassium Permanganate as an Alternative for Gold Mining Wastewater Treatment (United States)

    Ordiales, M.; Fernández, D.; Verdeja, L. F.; Sancho, J.


    The feasibility of using potassium permanganate as a reagent for cyanide oxidation in wastewater was experimentally studied. Both artificial and production wastewater from two different gold mines were tested. The experiments had three goals: determine the optimum reagent concentration and reaction time required to achieve total cyanide removal, obtain knowledge of the reaction kinetics, and improve the management of the amount of reagent. The results indicate that potassium permanganate is an effective and reliable oxidizing agent for the removal of cyanide from gold mining wastewater.

  1. Microstructural characterization of single-crystalline potassium hollandite nanowires

    International Nuclear Information System (INIS)

    Xu, C.Y.; Zhen, L.; Zhang, Q.; Tang, J.; Qin, L.-C.


    Single-crystalline potassium hollandite KTi 8 O 16.5 nanowires were synthesized by the molten salt method at 800 deg. C. Scanning electron microscopy observation shows that the nanowires are with octagonal cross-sections, and combined analyses of transmission electron microscopy and the electron diffraction results show that the terminated planes are angled 90 or 60 degrees to the growth direction, [001] crystallography direction. Ordering of the potassium cations in the tunnels was revealed by electron diffraction. The mechanism of one-dimensional growth of the nanowires was attributed to the oriented attachment mechanism

  2. Body potassium measurement using Phoswich based lung monitor

    International Nuclear Information System (INIS)

    Manohari, M.; Deepu, R.; Arun, B.; Mathiyarasu, R.; Jose, M.T.; Venkatraman, B.


    Phoswich based lung monitor enabled with the feature of high energy photon measurement is effectively utilised to measure body potassium of radiation workers reported for lung monitoring at RSD, IGCAR. The Phoswich systems, kept inside the low background steel room in an optimum counting geometry, has resulted in a higher efficiency value and lesser MDA for 40 K compared to whole body counters (4 inch x 3 inch NaI(Tl) - scanning geometry) due to increased counting time and reduced background in steel room. This paper discusses about calibration, body potassium measurement, its correlation with parameters like gender and the results obtained

  3. Preparation of potassium tantalum fluoride from tantalum hydroxide

    International Nuclear Information System (INIS)

    Silva, F.T. da; Espinola, A.; Dutra, A.J.B.


    Potassium tantalum fluoride (K 2 TaF 7 ) is an intermediary product in the processing of tantaliferous materials; it is the basic raw material for both reduction processes in use presently: reduction by metallic sodium and electrolysis in molten halides. It is normally obtained from a fluorotantalic acid solution to which potassium ions are added the precipitation of white acicular crystals of K 2 TaF 7 . The conditions for precipitation and recrystallization were studied, and crystal characterization were done by scanning electron microscopy, X-ray diffraction and thermogravimetric and thermodifferential analyses. (Author) [pt

  4. Changes in plasma potassium concentration during carbon dioxide pneumoperitoneum

    DEFF Research Database (Denmark)

    Perner, A; Bugge, K; Lyng, K M


    Hyperkalaemia with ECG changes had been noted during prolonged carbon dioxide pneumoperitoneum in pigs. We have compared plasma potassium concentrations during surgery in 11 patients allocated randomly to undergo either laparoscopic or open appendectomy and in another 17 patients allocated randomly...... to either carbon dioxide pneumoperitoneum or abdominal wall lifting for laparoscopic colectomy. Despite an increasing metabolic acidosis, prolonged carbon dioxide pneumoperitoneum resulted in only a slight increase in plasma potassium concentrations, which was both statistically and clinically insignificant....... Thus hyperkalaemia is unlikely to develop in patients with normal renal function undergoing carbon dioxide pneumoperitoneum for laparoscopic surgery....

  5. Preparation and Aromatic Hydrocarbon Removal Performance of Potassium Ferrate

    Directory of Open Access Journals (Sweden)

    Wei Guan


    Full Text Available This experiment adopts the hypochlorite oxidation method to constantly synthesize potassium ferrate. Under the condition of micropolluted source water pH and on the basis of naphthalene, phenanthrene, and pyrene as research objects, the effects of different systems to remove aromatic hydrocarbons were studied. Various oxidation systems to remove phenanthrene intermediate are analyzed and the detailed mechanisms for removal of phenanthrene are discussed. The study found that the main intermediate of potassium ferrate system to transform phenanthrene is 9,10-phenanthraquinone and its area percentage reached 82.66%; that is, 9,10-phenanthraquinone is the key entity to remove phenanthrene.

  6. Synthesis of Carbon Nanotubes Using Sol Gel Route (United States)

    Abdel-Fattah, Tarek


    Since 1990, carbon nanotubes were discovered and they have been the object of intense scientific study ever since. A carbon nanotube is a honeycomb lattice rolled into a cylinder. The diameter of a carbon nanotube is of nanometer size and the length is in the range of micrometer. Many of the extraordinary properties attributed to nanotubes, such as tensile strength and thermal stability, have inspired predictions of microscopic robots, dent-resistant car bodies and earthquake-resistant buildings. The first products to use nanotubes were electrical. Some General Motors cars already include plastic parts to which nanotubes were added; such plastic can be electrified during painting so that the paint will stick more readily. Two nanotube-based lighting and display products are well on their way to market. In the long term, perhaps the most valuable applications will take further advantage of nanotubes' unique electronic properties. Carbon nanotubes can in principle play the same role as silicon does in electronic circuits, but at a molecular scale where silicon and other standard semiconductors cease to work. There are several routes to synthesize carbon nanotubes; laser vaporization, carbon arc and vapor growth. We have applied a different route using sol gel chemistry to obtain carbon nanotubes. This work is patent-pending.

  7. Carbon nanotube network-silicon oxide non-volatile switches. (United States)

    Liao, Albert D; Araujo, Paulo T; Xu, Runjie; Dresselhaus, Mildred S


    The integration of carbon nanotubes with silicon is important for their incorporation into next-generation nano-electronics. Here we demonstrate a non-volatile switch that utilizes carbon nanotube networks to electrically contact a conductive nanocrystal silicon filament in silicon dioxide. We form this device by biasing a nanotube network until it physically breaks in vacuum, creating the conductive silicon filament connected across a small nano-gap. From Raman spectroscopy, we observe coalescence of nanotubes during breakdown, which stabilizes the system to form very small gaps in the network~15 nm. We report that carbon nanotubes themselves are involved in switching the device to a high resistive state. Calculations reveal that this switching event occurs at ~600 °C, the temperature associated with the oxidation of nanotubes. Therefore, we propose that, in switching to a resistive state, the nanotube oxidizes by extracting oxygen from the substrate.

  8. Potassium transport across guinea pig distal colon

    International Nuclear Information System (INIS)

    Rechkemmer, G.; Halm, D.R.; Frizzell, R.A.


    Active absorption and secretion of K was studied by measuring bidirectional 42 K fluxes across short-circuited guinea pig distal colon. Tissues were pretreated with mucosal (m) and serosal (s) indomethacin (1 μM) and amiloride (0.1 mM, m) to suppress spontaneous, electrogenic Cl secretion and Na absorption. Under these conditions, the short-circuit current (I/sub sc/) was 0.4 μeq/cm 2 h while electroneutral K absorption was 2.8 μeq/cm 2 h. Epinephrine (5 μM, s) stimulated electrogenic K secretion, reducing net K absorption to 1.3 μeq/cm 2 h. Bumetanide (0.1 mM, s) abolished this K secretion and restored K absorption to control values, suggesting mechanistic similarities between K and Cl secretion. K absorption was inhibited 40% by the gastric H/K ATPase inhibitor, omeprazole (0.1 mM, m), and was abolished by ouabain (0.1 mM, m). Neutral K absorption does not appear to be mediated by an apical membrane Na/K pump since: the effect of mucosal ouabain on K absorption does not require the presence of mucosal or serosal Na, unidirectional Na fluxes are not influenced by mucosal ouabain, and K absorption is not affected when Na absorption is abolished by amiloride. Net K transport is determined by the balance between electroneutral K absorption and electrogenic K secretion. The ouabain sensitivity of K absorption suggests that colonic H/K ATPase differs from its gastric counterpart

  9. Menstrual suppression in the adolescent. (United States)

    Kantartzis, Kelly L; Sucato, Gina S


    Menstrual suppression, the use of contraceptive methods to eliminate or decrease the frequency of menses, is often prescribed for adolescents to treat menstrual disorders or to accommodate patient preference. For young women using hormonal contraceptives, there is no medical indication for menstruation to occur monthly, and various hormonal contraceptives can be used to decrease the frequency of menstruation with different side effect profiles and rates of amenorrhea. This article reviews the different modalities for menstrual suppression, common conditions in adolescents which may improve with menstrual suppression, and strategies for managing common side effects. Copyright © 2013 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.

  10. Carbon Nanotubes and Chronic Granulomatous Disease

    Directory of Open Access Journals (Sweden)

    Barbara P. Barna


    Full Text Available Use of nanomaterials in manufactured consumer products is a rapidly expanding industry and potential toxicities are just beginning to be explored. Combustion-generated multiwall carbon nanotubes (MWCNT or nanoparticles are ubiquitous in non-manufacturing environments and detectable in vapors from diesel fuel, methane, propane, and natural gas. In experimental animal models, carbon nanotubes have been shown to induce granulomas or other inflammatory changes. Evidence suggesting potential involvement of carbon nanomaterials in human granulomatous disease, has been gathered from analyses of dusts generated in the World Trade Center disaster combined with epidemiological data showing a subsequent increase in granulomatous disease of first responders. In this review we will discuss evidence for similarities in the pathophysiology of carbon nanotube-induced pulmonary disease in experimental animals with that of the human granulomatous disease, sarcoidosis.

  11. Detection of gas atoms with carbon nanotubes (United States)

    Arash, B.; Wang, Q.


    Owning to their unparalleled sensitivity resolution, nanomechanical resonators have excellent capabilities in design of nano-sensors for gas detection. The current challenge is to develop new designs of the resonators for differentiating distinct gas atoms with a recognizably high sensitivity. In this work, the characteristics of impulse wave propagation in carbon nanotube-based sensors are investigated using molecular dynamics simulations to provide a new method for detection of noble gases. A sensitivity index based on wave velocity shifts in a single-walled carbon nanotube, induced by surrounding gas atoms, is defined to explore the efficiency of the nano-sensor. The simulation results indicate that the nano-sensor is able to differentiate distinct noble gases at the same environmental temperature and pressure. The inertia and the strengthening effects by the gases on wave characteristics of carbon nanotubes are particularly discussed, and a continuum mechanics shell model is developed to interpret the effects.

  12. Batch fabrication of nanotubes suspended between microelectrodes

    DEFF Research Database (Denmark)

    Mateiu, Ramona Valentina; Stöckli, T.; Knapp, H. F.


    We report a fabrication method, which uses standard UV-lithography to pattern the catalyst for the chemical vapour deposition(CVD) of suspended double clamped single walled carbon nanotubes. By using an aqueous solution of Fe(NO3)3 the patterning of the catalyst material onto microelectrodes can...... to the regions of maximum electric field, enabling accurate positioning of a nanotube by controlling the shape of the microelectrodes. The CNT bridges are deflected tens of nm when a DC voltage is applied between the nanotube and a gate microelectrode indicating that the clamping through the catalyst particles...... is not only mechanically stable but also electrical conducting. This method could be used to fabricate nanoelectromechanical systems based on suspended double clamped CNTs depending only on photolithography and standard Cleanroom processes....

  13. Boron Nitride Nanotube: Synthesis and Applications (United States)

    Tiano, Amanda L.; Park, Cheol; Lee, Joseph W.; Luong, Hoa H.; Gibbons, Luke J.; Chu, Sang-Hyon; Applin, Samantha I.; Gnoffo, Peter; Lowther, Sharon; Kim, Hyun Jung; hide


    Scientists have predicted that carbon's immediate neighbors on the periodic chart, boron and nitrogen, may also form perfect nanotubes, since the advent of carbon nanotubes (CNTs) in 1991. First proposed then synthesized by researchers at UC Berkeley in the mid 1990's, the boron nitride nanotube (BNNT) has proven very difficult to make until now. Herein we provide an update on a catalyst-free method for synthesizing highly crystalline, small diameter BNNTs with a high aspect ratio using a high power laser under a high pressure and high temperature environment first discovered jointly by NASA/NIA JSA. Progress in purification methods, dispersion studies, BNNT mat and composite formation, and modeling and diagnostics will also be presented. The white BNNTs offer extraordinary properties including neutron radiation shielding, piezoelectricity, thermal oxidative stability (> 800 C in air), mechanical strength, and toughness. The characteristics of the novel BNNTs and BNNT polymer composites and their potential applications are discussed.

  14. Photothermoelectric Effect in Suspended Semiconducting Carbon Nanotubes (United States)

    Aspitarte, Lee; Deborde, Tristan; Sharf, Tal; Kevek, Josh; Minot, Ethan


    We have performed scanning photocurrent microscopy measurements of field-effect transistors (FETs) made from individual suspended carbon nanotubes (CNTs).Photocurrent generation in individual carbon nanotube based devices has been previously attributed the photovoltaic effect, in contrast to graphene based devices which are dominated by the photothermoelectric effect. In this work, we present the first measurements of strong photothermoelectric currents in individual suspended carbon nanotube field-effect transistors. In certain electrostatic doping regimes light induced temperature gradients lead to significant thermoelectric currents which oppose and overwhelm the photovoltaic contribution. Our measurements give new insight into the tunable and spatially inhomogeneous Seebeck coefficient of electrostatically-gated CNTs and demonstrate a new mechanism for optimizing CNT-based photodetectors and energy harvesting devices.

  15. Silicon Carbide Nanotube Oxidation at High Temperatures (United States)

    Ahlborg, Nadia; Zhu, Dongming


    Silicon Carbide Nanotubes (SiCNTs) have high mechanical strength and also have many potential functional applications. In this study, SiCNTs were investigated for use in strengthening high temperature silicate and oxide materials for high performance ceramic nanocomposites and environmental barrier coating bond coats. The high · temperature oxidation behavior of the nanotubes was of particular interest. The SiCNTs were synthesized by a direct reactive conversion process of multiwall carbon nanotubes and silicon at high temperature. Thermogravimetric analysis (TGA) was used to study the oxidation kinetics of SiCNTs at temperatures ranging from 800degC to1300degC. The specific oxidation mechanisms were also investigated.

  16. Nanotube Dispersions Made With Charged Surfactant (United States)

    Kuper, Cynthia; Kuzma, Mike


    Dispersions (including monodispersions) of nanotubes in water at relatively high concentrations have been formulated as prototypes of reagents for use in making fibers, films, and membranes based on single-walled carbon nanotubes (SWNTs). Other than water, the ingredients of a dispersion of this type include one or more charged surfactant(s) and carbon nanotubes derived from the HiPco(TradeMark) (or equivalent) process. Among reagents known to be made from HiPco(TradeMark)(or equivalent) SWNTs, these are the most concentrated and are expected to be usable in processing of bulk structures and materials. Test data indicate that small bundles of SWNTs and single SWNTs at concentrations up to 1.1 weight percent have been present in water plus surfactant. This development is expected to contribute to the growth of an industry based on applied carbon nanotechnology. There are expected to be commercial applications in aerospace, avionics, sporting goods, automotive products, biotechnology, and medicine.

  17. Optical trapping of carbon nanotubes and graphene

    Directory of Open Access Journals (Sweden)

    S. Vasi


    Full Text Available We study optical trapping of nanotubes and graphene. We extract the distribution of both centre-of-mass and angular fluctuations from three-dimensional tracking of these optically trapped carbon nanostructures. The optical force and torque constants are measured from auto and cross-correlation of the tracking signals. We demonstrate that nanotubes enable nanometer spatial, and femto-Newton force resolution in photonic force microscopy by accurately measuring the radiation pressure in a double frequency optical tweezers. Finally, we integrate optical trapping with Raman and photoluminescence spectroscopy demonstrating the use of a Raman and photoluminescence tweezers by investigating the spectroscopy of nanotubes and graphene flakes in solution. Experimental results are compared with calculations based on electromagnetic scattering theory.

  18. Detection of gas atoms with carbon nanotubes (United States)

    Arash, B.; Wang, Q.


    Owning to their unparalleled sensitivity resolution, nanomechanical resonators have excellent capabilities in design of nano-sensors for gas detection. The current challenge is to develop new designs of the resonators for differentiating distinct gas atoms with a recognizably high sensitivity. In this work, the characteristics of impulse wave propagation in carbon nanotube-based sensors are investigated using molecular dynamics simulations to provide a new method for detection of noble gases. A sensitivity index based on wave velocity shifts in a single-walled carbon nanotube, induced by surrounding gas atoms, is defined to explore the efficiency of the nano-sensor. The simulation results indicate that the nano-sensor is able to differentiate distinct noble gases at the same environmental temperature and pressure. The inertia and the strengthening effects by the gases on wave characteristics of carbon nanotubes are particularly discussed, and a continuum mechanics shell model is developed to interpret the effects.

  19. Nanotube Production Devices Expand Research Capabilities (United States)


    In order for the Hubble Space Telescope to take incredible, never-seen-before shots of celestial bodies and then send them back to Earth, the spacecraft needs power. While in orbit, Hubble cannot plug into an electrical outlet or stop at a store for some batteries. One of the ways NASA supplies power aboard a spacecraft is by harnessing energy from the most powerful entity in the solar system: the Sun. Since the 1960s, photovoltaic technology, or technology that converts sunlight into electricity, has been instrumental in the exploration of space. To build upon existing photovoltaic technology, NASA s Glenn Research Center has worked on a variety of innovative designs and materials to incorporate into photovoltaic cells, the building blocks of solar power systems. One of these materials is the carbon nanotube - a tiny structure about 50,000 times finer than the average human hair, with notably high electrical and thermal conductivity and an extreme amount of mechanical strength. Such properties give carbon nanotubes great potential to enhance the reliability of power generation and storage devices in space and on Earth. Dennis J. Flood, the branch chief of the photovoltaic division at Glenn in the 1990s, was looking into using carbon nanotubes to improve the efficiency of solar cells when he ran into a major roadblock - high-quality carbon nanotubes were not readily available. To address this problem, one of the chemists in Flood s group came up with a process and system for growing them. A senior chemist at Glenn, Aloysius F. Hepp, devised an injection chemical vapor deposition process using a specific organometallic catalyst in a two-zone furnace. Hepp's group found the unique process produced high-quality carbon nanotubes with less than 5 percent metal impurity. In addition, the process was more efficient than existing techniques, as it eliminated pre-patterning of the substrate used for growing the nanotubes, a timely and cost-prohibitive step.

  20. Carbon nanotube oscillators for applications as nanothermometers

    International Nuclear Information System (INIS)

    Rahmat, Fainida; Thamwattana, Ngamta; Hill, James M


    Nanostructures such as carbon nanotubes have a broad range of potential applications such as nanomotors, nano-oscillators and electromechanical nanothermometers, and a proper understanding of the molecular interaction between nanostructures is fundamentally important for these applications. In this paper, we determine the molecular interaction potential of interacting carbon nanotubes for two configurations. The first is a shuttle configuration involving a short outer tube sliding on a fixed inner tube, and the second involves a telescopic configuration for which an inner tube moves both in the region between two outer tubes and through the tubes themselves. For the first configuration we examine two cases of semi-infinite and finite inner carbon nanotubes. We employ the continuum approximation and the 6-12 Lennard-Jones potential for non-bonded molecules to determine the molecular interaction potential and the resulting van der Waals force, and we evaluate the resulting surface integrals numerically. We also investigate the acceptance condition and suction energy for the first configuration. Our results show that for the shuttle configuration with a semi-infinite inner tube, the suction energy is maximum when the difference between the outer and inner tubes radii is approximately 3.4 A, which is the ideal inter-wall spacing between graphene sheets. For the finite inner tube, the potential energy is dependent on both the inner and outer tube lengths as well as on the inter-wall spacing. In terms of the oscillating frequency, the critical issue is the length of the moving outer tube, and the shorter the length, the higher the frequency. Further, for the telescopic configuration with two semi-infinite outer nanotubes of different radii, we find that the interaction energy also depends on the difference of the tube radii. For two outer nanotubes of equal radii we observe that the shorter the distance between the two outer nanotubes, the higher the magnitude of the

  1. Voltage dependent potassium channel remodeling in murine intestinal smooth muscle hypertrophy induced by partial obstruction. (United States)

    Liu, Dong-Hai; Huang, Xu; Guo, Xin; Meng, Xiang-Min; Wu, Yi-Song; Lu, Hong-Li; Zhang, Chun-Mei; Kim, Young-chul; Xu, Wen-Xie


    Partial obstruction of the small intestine causes obvious hypertrophy of smooth muscle cells and motility disorder in the bowel proximate to the obstruction. To identify electric remodeling of hypertrophic smooth muscles in partially obstructed murine small intestine, the patch-clamp and intracellular microelectrode recording methods were used to identify the possible electric remodeling and Western blot, immunofluorescence and immunoprecipitation were utilized to examine the channel protein expression and phosphorylation level changes in this research. After 14 days of obstruction, partial obstruction caused obvious smooth muscle hypertrophy in the proximally located intestine. The slow waves of intestinal smooth muscles in the dilated region were significantly suppressed, their amplitude and frequency were reduced, whilst the resting membrane potentials were depolarized compared with normal and sham animals. The current density of voltage dependent potassium channel (KV) was significantly decreased in the hypertrophic smooth muscle cells and the voltage sensitivity of KV activation was altered. The sensitivity of KV currents (IKV) to TEA, a nonselective potassium channel blocker, increased significantly, but the sensitivity of IKv to 4-AP, a KV blocker, stays the same. The protein levels of KV4.3 and KV2.2 were up-regulated in the hypertrophic smooth muscle cell membrane. The serine and threonine phosphorylation levels of KV4.3 and KV2.2 were significantly increased in the hypertrophic smooth muscle cells. Thus this study represents the first identification of KV channel remodeling in murine small intestinal smooth muscle hypertrophy induced by partial obstruction. The enhanced phosphorylations of KV4.3 and KV2.2 may be involved in this process.

  2. Voltage dependent potassium channel remodeling in murine intestinal smooth muscle hypertrophy induced by partial obstruction.

    Directory of Open Access Journals (Sweden)

    Dong-Hai Liu

    Full Text Available Partial obstruction of the small intestine causes obvious hypertrophy of smooth muscle cells and motility disorder in the bowel proximate to the obstruction. To identify electric remodeling of hypertrophic smooth muscles in partially obstructed murine small intestine, the patch-clamp and intracellular microelectrode recording methods were used to identify the possible electric remodeling and Western blot, immunofluorescence and immunoprecipitation were utilized to examine the channel protein expression and phosphorylation level changes in this research. After 14 days of obstruction, partial obstruction caused obvious smooth muscle hypertrophy in the proximally located intestine. The slow waves of intestinal smooth muscles in the dilated region were significantly suppressed, their amplitude and frequency were reduced, whilst the resting membrane potentials were depolarized compared with normal and sham animals. The current density of voltage dependent potassium channel (KV was significantly decreased in the hypertrophic smooth muscle cells and the voltage sensitivity of KV activation was altered. The sensitivity of KV currents (IKV to TEA, a nonselective potassium channel blocker, increased significantly, but the sensitivity of IKv to 4-AP, a KV blocker, stays the same. The protein levels of KV4.3 and KV2.2 were up-regulated in the hypertrophic smooth muscle cell membrane. The serine and threonine phosphorylation levels of KV4.3 and KV2.2 were significantly increased in the hypertrophic smooth muscle cells. Thus this study represents the first identification of KV channel remodeling in murine small intestinal smooth muscle hypertrophy induced by partial obstruction. The enhanced phosphorylations of KV4.3 and KV2.2 may be involved in this process.

  3. Thermal Transport in Carbon Nanotubes (United States)

    Christman, Jeremy; Moore, Andrew; Khatun, Mahfuza


    Recent advances in nanostructure technology have made it possible to create small devices at the nanoscale. Carbon nanotubes (CNT's) are among the most exciting building blocks of nanotechnology. Their versatility and extremely desirable properties for electronic and other devices have driven intense research and development efforts in recent years. A review of electrical and thermal conduction of the structures will be presented. The theoretical investigation is mainly based on molecular dynamics. Green Kubo relation is used for the study of thermal conductivity. Results include kinetic energy, potential energy, heat flux autocorrelation function, and heat conduction of various CNT structures. Most of the computation and simulation has been conducted on the Beowulf cluster at Ball State University. Various software packages and tools such as Visual Molecular Dynamics (VMD), Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS), and NanoHUB, the open online resource at Purdue University have been used for the research. The work has been supported by the Indiana Academy of Science Research Fund, 2010-2011.

  4. Carbon nanotube fiber terahertz polarizer

    Energy Technology Data Exchange (ETDEWEB)

    Zubair, Ahmed [Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005 (United States); Tsentalovich, Dmitri E.; Young, Colin C. [Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005 (United States); Heimbeck, Martin S. [Charles M. Bowden Laboratory, Aviation & Missile Research, Development, and Engineering Center (AMRDEC), Redstone Arsenal, Alabama 35898 (United States); Everitt, Henry O. [Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005 (United States); Charles M. Bowden Laboratory, Aviation & Missile Research, Development, and Engineering Center (AMRDEC), Redstone Arsenal, Alabama 35898 (United States); Pasquali, Matteo [Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005 (United States); Department of Chemistry, Rice University, Houston, Texas 77005 (United States); Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005 (United States); Kono, Junichiro, E-mail: [Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005 (United States); Department of Materials Science and NanoEngineering, Rice University, Houston, Texas 77005 (United States); Department of Physics and Astronomy, Rice University, Houston, Texas 77005 (United States)


    Conventional, commercially available terahertz (THz) polarizers are made of uniformly and precisely spaced metallic wires. They are fragile and expensive, with performance characteristics highly reliant on wire diameters and spacings. Here, we report a simple and highly error-tolerant method for fabricating a freestanding THz polarizer with nearly ideal performance, reliant on the intrinsically one-dimensional character of conduction electrons in well-aligned carbon nanotubes (CNTs). The polarizer was constructed on a mechanical frame over which we manually wound acid-doped CNT fibers with ultrahigh electrical conductivity. We demonstrated that the polarizer has an extinction ratio of ∼−30 dB with a low insertion loss (<0.5 dB) throughout a frequency range of 0.2–1.1 THz. In addition, we used a THz ellipsometer to measure the Müller matrix of the CNT-fiber polarizer and found comparable attenuation to a commercial metallic wire-grid polarizer. Furthermore, based on the classical theory of light transmission through an array of metallic wires, we demonstrated the most striking difference between the CNT-fiber and metallic wire-grid polarizers: the latter fails to work in the zero-spacing limit, where it acts as a simple mirror, while the former continues to work as an excellent polarizer even in that limit due to the one-dimensional conductivity of individual CNTs.

  5. Elastomer Reinforced with Carbon Nanotubes (United States)

    Hudson, Jared L.; Krishnamoorti, Ramanan


    Elastomers are reinforced with functionalized, single-walled carbon nanotubes (SWNTs) giving them high-breaking strain levels and low densities. Cross-linked elastomers are prepared using amine-terminated, poly(dimethylsiloxane) (PDMS), with an average molecular weight of 5,000 daltons, and a functionalized SWNT. Cross-link densities, estimated on the basis of swelling data in toluene (a dispersing solvent) indicated that the polymer underwent cross-linking at the ends of the chains. This thermally initiated cross-linking was found to occur only in the presence of the aryl alcohol functionalized SWNTs. The cross-link could have been via a hydrogen-bonding mechanism between the amine and the free hydroxyl group, or via attack of the amine on the ester linage to form an amide. Tensile properties examined at room temperature indicate a three-fold increase in the tensile modulus of the elastomer, with rupture and failure of the elastomer occurring at a strain of 6.5.

  6. Nanobody-Displaying Flagellar Nanotubes. (United States)

    Klein, Ágnes; Kovács, Mátyás; Muskotál, Adél; Jankovics, Hajnalka; Tóth, Balázs; Pósfai, Mihály; Vonderviszt, Ferenc


    In this work we addressed the problem how to fabricate self-assembling tubular nanostructures displaying target recognition functionalities. Bacterial flagellar filaments, composed of thousands of flagellin subunits, were used as scaffolds to display single-domain antibodies (nanobodies) on their surface. As a representative example, an anti-GFP nanobody was successfully inserted into the middle part of flagellin replacing the hypervariable surface-exposed D3 domain. A novel procedure was developed to select appropriate linkers required for functional internal insertion. Linkers of various lengths and conformational properties were chosen from a linker database and they were randomly attached to both ends of an anti-GFP nanobody to facilitate insertion. Functional fusion constructs capable of forming filaments on the surface of flagellin-deficient host cells were selected by magnetic microparticles covered by target GFP molecules and appropriate linkers were identified. TEM studies revealed that short filaments of 2-900 nm were formed on the cell surface. ITC and fluorescent measurements demonstrated that the fusion protein exhibited high binding affinity towards GFP. Our approach allows the development of functionalized flagellar nanotubes against a variety of important target molecules offering potential applications in biosensorics and bio-nanotechnology.

  7. Agglomeration defects on irradiated carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Cássio Stein Moura


    Full Text Available Aligned carbon nanotubes (CNT were irradiated in the longitudinal and perpendicular directions, with low energy carbon and helium ions in order to observe the formation of defects in the atomic structure. Analysis through Raman spectroscopy and scanning electron microscopy indicated bundle rupture and ion track formation on nanotube bundles. Aligned CNT presented a kind of defect comprising ravine formation and tube agglomeration on top of the substrate. The latter structure is possibly caused by static charge accumulation induced by the incoming ions. Fluence plays a role on the short range order. Higher fluence irradiation transforms CNT into amorphous carbon nanowires.

  8. Electrical device fabrication from nanotube formations (United States)

    Nicholas, Nolan Walker; Kittrell, W. Carter; Kim, Myung Jong; Schmidt, Howard K.


    A method for forming nanotube electrical devices, arrays of nanotube electrical devices, and device structures and arrays of device structures formed by the methods. Various methods of the present invention allow creation of semiconducting and/or conducting devices from readily grown SWNT carpets rather than requiring the preparation of a patterned growth channel and takes advantage of the self-controlling nature of these carpet heights to ensure a known and controlled channel length for reliable electronic properties as compared to the prior methods.

  9. Laser ablative synthesis of carbon nanotubes (United States)

    Smith, Michael W.; Jordan, Kevin; Park, Cheol


    An improved method for the production of single walled carbon nanotubes that utilizes an RF-induction heated side-pumped synthesis chamber for the production of such. Such a method, while capable of producing large volumes of carbon nanotubes, concurrently permits the use of a simplified apparatus that allows for greatly reduced heat up and cool down times and flexible flowpaths that can be readily modified for production efficiency optimization. The method of the present invention utilizes a free electron laser operating at high average and peak fluence to illuminate a rotating and translating graphite/catalyst target to obtain high yields of SWNTs without the use of a vacuum chamber.

  10. Carbon Nanotubes for Space Photovoltaic Applications (United States)

    Efstathiadis, Harry; Haldar, Pradeep; Landi, Brian J.; Denno, Patrick L.; DiLeo, Roberta A.; VanDerveer, William; Raffaelle, Ryne P.


    Carbon nanotubes (CNTs) can be envisioned as an individual graphene sheet rolled into a seamless cylinder (single-walled, SWNT), or concentric sheets as in the case of a multi-walled carbon nanotube (MWNT) (1). The role-up vector will determine the hexagonal arrangement and "chirality" of the graphene sheet, which will establish the nanotube to be metallic or semiconducting. The optoelectronic properties will depend directly on this chiral angle and the diameter of the SWNT, with semiconductor types exhibiting a band gap energy (2). Characteristic of MWNTs are the concentric graphene layers spaced 0.34 nm apart, with diameters from 10-200 nm and lengths up to hundreds of microns (2). In the case of SWNTs, the diameters range from 0.4 - 2 nm and lengths have been reported up to 1.5 cm (3). SWNTs have the distinguishable property of "bundling" together due to van der Waal's attractions to form "ropes." A comparison of these different structural types is shown in Figure 1. The use of SWNTS in space photovoltaic (PV) applications is attractive for a variety of reasons. Carbon nanotubes as a class of materials exhibit unprecedented optical, electrical, mechanical properties, with the added benefit of being nanoscale in size which fosters ideal interaction in nanomaterial-based devices like polymeric solar cells. The optical bandgap of semiconducting SWNTs can be varied from approx. 0.4 - 1.5 eV, with this property being inversely proportional to the nanotube diameter. Recent work at GE Global Research has shown where a single nanotube device can behave as an "ideal" pn diode (5). The SWNT was bridged over a SiO2 channel between Mo contacts and exhibited an ideality factor of 1, based on a fit of the current-voltage data using the diode equation. The measured PV efficiency under a 0.8 eV monochromatic illumination showed a power conversion efficiency of 0.2 %. However, the projected efficiency of these junctions is estimated to be > 5 %, especially when one considers the

  11. Carbon nanotubes as anti-bacterial agents. (United States)

    Mocan, Teodora; Matea, Cristian T; Pop, Teodora; Mosteanu, Ofelia; Buzoianu, Anca Dana; Suciu, Soimita; Puia, Cosmin; Zdrehus, Claudiu; Iancu, Cornel; Mocan, Lucian


    Multidrug-resistant bacterial infections that have evolved via natural selection have increased alarmingly at a global level. Thus, there is a strong need for the development of novel antibiotics for the treatment of these infections. Functionalized carbon nanotubes through their unique properties hold great promise in the fight against multidrug-resistant bacterial infections. This new family of nanovectors for therapeutic delivery proved to be innovative and efficient for the transport and cellular translocation of therapeutic molecules. The current review examines the latest progress in the antibacterial activity of carbon nanotubes and their composites.

  12. Compton suppression gamma ray spectrometry

    International Nuclear Information System (INIS)

    Landsberger, S.; Iskander, F.Y.; Niset, M.; Heydorn, K.


    In the past decade there have been many studies to use Compton suppression methods in routine neutron activation analysis as well as in the traditional role of low level gamma ray counting of environmental samples. On a separate path there have been many new PC based software packages that have been developed to enhance photopeak fitting. Although the newer PC based algorithms have had significant improvements, they still suffer from being effectively used in weak gamma ray lines in natural samples or in neutron activated samples that have very high Compton backgrounds. We have completed a series of experiments to show the usefulness of Compton suppression. As well we have shown the pitfalls when using Compton suppression methods for high counting deadtimes as in the case of neutron activated samples. We have also investigated if counting statistics are the same both suppressed and normal modes. Results are presented in four separate experiments. (author)

  13. Kv7 potassium channel activation with ICA-105665 reduces photoparoxysmal EEG responses in patients with epilepsy (United States)

    Kasteleijn-Nolst Trenité, Dorotheé G A; Biton, Victor; French, Jacqueline A; Abou-Khalil, Bassel; Rosenfeld, William E; Diventura, Bree; Moore, Elizabeth L; Hetherington, Seth V; Rigdon, Greg C


    Purpose To assess the effects of ICA-105665, an agonist of neuronal Kv7 potassium channels, on epileptiform EEG discharges, evoked by intermittent photic stimulation (IPS), the so-called photoparoxysmal responses (PPRs) in patients with epilepsy. Methods Male and female patients aged 18–60 years with reproducible PPRs were eligible for enrollment. The study was conducted as a single-blind, single-dose, multiple-cohort study. Four patients were enrolled in each of the first three cohorts. Six patients were enrolled in the fourth cohort and one patient was enrolled in the fifth cohort. PPR responses to 14 IPS frequencies (steps) were used to determine the standard photosensitivity range (SPR) following placebo on day 1 and ICA-105665 on day 2. The SPR was quantified for three eye conditions (eyes closing, eyes closed, and eyes open), and the most sensitive condition was used for assessment of efficacy. A partial response was defined as a reduction in the SPR of at least three units at three separate time points following ICA-105665 compared to the same time points following placebo with no time points with more than three units of increase. Complete suppression was defined by no PPRs in any eye condition at one or more time points. Key Findings Six individual patients participated in the first three cohorts (100, 200, and 400 mg). Six patients participated in the fourth cohort (500 mg), and one patient participated in the fifth cohort (600 mg). Decreases in SPR occurred in one patient at 100 mg, two patients receiving 400 mg ICA-105665 (complete abolishment of SPR occurred in one patient at 400 mg), and in four of six patients receiving 500 mg. The most common adverse events (AEs) were those related to the nervous system, and dizziness appeared to be the first emerging AE. The single patient in the 600 mg cohort developed a brief generalized seizure within 1 h of dosing, leading to the discontinuation of additional patients at this dose, per the

  14. Thyroid suppression test with dextrothyroxine

    International Nuclear Information System (INIS)

    Rosenthal, D.; Fridman, J.; Ribeiro, H.B.


    The classic thyroid suppression test with triiodothyronine (l-T 3 ) has been shown to be efficient as an auxiliary method in the diagnosis of thyroid diseases, but should not be performed on elderly patients or on those with heart disease or a tendency to tachycardia. Since these subjects seem able to support a short period of dextro-thyronine (d-T 4 ) feeding, we compared the effect of d-T 4 and l-T 3 on the 24 hours thyroid uptake in euthyroid and hyperthyroid subjects. After basal radio-iodine uptake determination, 99 patients without hyperthyroidism and 27 with Graves' disease were randomly divided in 2 groups; one received 100μg of l-T 3 per day and the other 4 mg of d-T 4 per day, both groups being treated for a period of 10 days. At the end of this suppression period the 24 hours radio-iodine uptake was measured again and the percentual suppression index (S.I.) calculated. Since the comparison of the two groups showed no difference between the suppressive effect of l-T 3 and d-T 4 in euthyroid subjects, while dextro-thyronine, as levo-triiodothyronine, did not suppress the 24 hours uptake of hyperthyroid patients, l-T 3 or d-T 4 can be used interchangeably to test thyroid suppressibility. In the euthyroid subjects the normal range for the post-suppression uptake was 0-17.1% and for the suppression index 54,7.100% [pt

  15. In vivo Treg suppression assays. (United States)

    Workman, Creg J; Collison, Lauren W; Bettini, Maria; Pillai, Meenu R; Rehg, Jerold E; Vignali, Dario A A


    To fully examine the functionality of a regulatory T cell (T(reg)) population, one needs to assess their ability to suppress in a variety of in vivo models. We describe five in vivo models that examine the suppressive capacity of T(regs) upon different target cell types. The advantages and disadvantages of each model including resources, time, and technical expertise required to execute each model are also described.

  16. In Vivo Treg Suppression Assays


    Workman, Creg J.; Collison, Lauren W.; Bettini, Maria; Pillai, Meenu R.; Rehg, Jerold E.; Vignali, Dario A.A.


    To fully examine the functionality of a regulatory T cell (Treg) population, one needs to assess their ability to suppress in a variety of in vivo models. We describe five in vivo models that examine the suppressive capacity of Tregs upon different target cell types. The advantages and disadvantages of each model includ ing resources, time, and technical expertise required to execute each model are also described.

  17. Palytoxin and the sodium/potassium pump—phosphorylation and potassium interaction (United States)

    Rodrigues, Antônio M.; Infantosi, Antonio F. C.; de Almeida, Antônio-Carlos G.


    We proposed a reaction model for investigating interactions between K+ and the palytoxin-sodium-potassium (PTX-Na+/K+) pump complex under conditions where enzyme phosphorylation may occur. The model is composed of (i) the Albers-Post model for Na+/K+-ATPase, describing Na+ and K+ pumping; (ii) the reaction model proposed for Na+/K+-ATPase interactions with its ligands (Na+, K+, ATP, ADP and P) and with PTX. A mathematical model derived for representing the reactions was used to simulate experimental studies of the PTX-induced current, in different concentrations for the pump ligands. The simulations allow interpretation of the simultaneous action of Na+/K+-ATPase phosphorylation and K+ on the PTX-induced channels. The results suggest that (i) phosphorylation increases the PTX toxic effect, increasing its affinity and reducing the K+ occlusion rate, and (ii) K+ causes channel blockage, increases the toxin dissociation rate and impedes the induced channel phosphorylation, implying reduction of the PTX toxic effect.

  18. Relationship of soil potassium forms with maize potassium contents in soils derived from different parent materials

    Directory of Open Access Journals (Sweden)

    Rashid Mehmood Butt


    Full Text Available Understanding of soil potassium (K dynamics is essential for sustainable crop production. Bioavailability of K depends on forms and distribution within the soil profile. The objectives of this research were to determine which soil K forms control the maize (Zea mays K contents and compare the extracting capability of sodium tetraphenylborate (NaTPB with ammonium acetate (NH4OAc method. Nine soils representing three different parent materials, i.e. loess, sandstone and shale were sampled at three surface genetic horizons. Within each parent material, three soils at varying level of development were selected. Besides basic soil parameters, K was fractioned into water soluble K, exchangeable K, non-exchangeable K, and NaTPB-extracted K. The maize was sown in pots having 2 kg soil from each genetic horizon. Crop was harvested at seven weeks and plant was analysed for K contents. Results show that NaTPB-extracted K gave best correlation as compared to NH4OAc method. This conveys that a non-exchangeable K portion that becomes available to plants can be better estimated by NaTPB method than NH4OAc extraction.

  19. Palytoxin and the sodium/potassium pump—phosphorylation and potassium interaction

    International Nuclear Information System (INIS)

    Rodrigues, Antônio M; De Almeida, Antônio-Carlos G; Infantosi, Antonio F C


    We proposed a reaction model for investigating interactions between K + and the palytoxin–sodium–potassium (PTX–Na + /K + ) pump complex under conditions where enzyme phosphorylation may occur. The model is composed of (i) the Albers–Post model for Na + /K + –ATPase, describing Na + and K + pumping; (ii) the reaction model proposed for Na + /K + –ATPase interactions with its ligands (Na + , K + , ATP, ADP and P) and with PTX. A mathematical model derived for representing the reactions was used to simulate experimental studies of the PTX-induced current, in different concentrations for the pump ligands. The simulations allow interpretation of the simultaneous action of Na + /K + –ATPase phosphorylation and K + on the PTX-induced channels. The results suggest that (i) phosphorylation increases the PTX toxic effect, increasing its affinity and reducing the K + occlusion rate, and (ii) K + causes channel blockage, increases the toxin dissociation rate and impedes the induced channel phosphorylation, implying reduction of the PTX toxic effect

  20. Urinary potassium excretion, renal ammoniagenesis, and risk of graft failure and mortality in renal transplant recipients

    NARCIS (Netherlands)

    Eisenga, Michele F.; Kieneker, Lyanne M.; Soedamah-Muthu, Sabita S.; van den Berg, Else; Deetman, Petronella E.; Navis, Gerjan J.; Gans, Reinold O. B.; Gaillard, Carlo A. J. M.; Bakker, Stephan J. L.; Joosten, Michel M.


    Background: Renal transplant recipients (RTRs) have commonly been urged to limit their potassium intake during renal insufficiency and may adhere to this principle after transplantation. Importantly, in experimental animal models, low dietary potassium intake induces kidney injury through

  1. Effect of osmolarity on potassium transport in isolated cerebral microvessels

    International Nuclear Information System (INIS)

    Lin, J.D.


    Potassium transport in microvessels isolated from rat brain by a technique involving density gradient centrifugation was studied in HEPES buffer solutions of varying osmolarity from 200 to 420 mosmols, containing different concentration of sodium chloride, choline chloride, or sodium nitrate. The flux of 86 Rb into and out of the endothelial cells was estimated. Potassium influx was very sensitive to the osmolarity of the medium. Ouabain-insensitive K-component was reduced in hypotonic medium and was increased in medium made hypertonic with sodium chloride or mannitol. Choline chloride replacement caused a large reduction in K influx. Potassium influx was significant decrease when nitrate is substituted for chloride ion in isotonic and hypertonic media, whereas a slight decrease was found in hypotonic medium. The decrease of K influx in the ion-replacement medium is due to a decrement of the ouabain-insensitive component. Potassium efflux was unchanged in hypotonic medium but was somewhat reduced in hypertonic medium. The marked effect of medium osmolarity of K fluxes suggests that these fluxes may be responsible for the volume regulatory K movements. The possible mechanism of changes of K flux under anisotonic media is also discussed

  2. Effect of potassium simplex optimization medium (KSOM) and ...

    African Journals Online (AJOL)

    In this study, we produced cloned transgenic dairy goat based on dairy goat ear skin fibroblast as donor cells for nuclear transfer (NT), which were modified by ... culture medium, potassium simplex optimization medium (KSOM) and tissue culture medium (TCM 199), or different classification of NT embryos (48 h after fusion).

  3. Late termination of pregnancy by intracardiac potassium chloride ...

    African Journals Online (AJOL)

    Objectives. To report our experience with intracardiac potassium chloride (KCl) injection as a method of feticide for severe congenital abnormalities beyond 24 weeksf gestation. Method. A retrospective chart review. Patient demographics and types of fetal anomalies were analysed according to the groups that accepted

  4. Measurement of refractive index of biaxial potassium titanyl ...

    Indian Academy of Sciences (India)

    The paper reports the measurement of refractive indices and anisotropic absorption coefficients of biaxial potassium titanyl phosphate (KTP) crystal in the form of thin plate using reflection ellipsometry technique. This experiment is designed in the Graduate Optics Laboratory of the Addis Ababa University and He–Ne laser ...

  5. Evaluation of human muscle in vivo by potassium radiometric measuring

    International Nuclear Information System (INIS)

    Sousa, Wanderson de P.


    Potassium is an essential element to the human metabolism and is present in all living cells, mainly in the striated muscular fibers. K-40 is one of the natural potassium isotopes with mass percentage of 0,0118% . This isotope emits beta particle and gamma rays with 1460 keV. The energy of K-40 photon and its uniform distribution within the human body allows its in vivo measurement. The objective of this study is to optimize this technique and evaluate the possibility of its medical application in order to quantify muscle increase during recovering procedures. Subjects of both sexes measured until this moment were divided into two groups. Subjects of Group 1 do not exercise routinely and subjects of Group 2 does. In Group 1 the average potassium mass, muscle mass and potassium concentration were (101±16)g of K, (20±3)kg of muscle and (1,3±0,3)g of K/kg of body mass, respectively, while in Group 2 average values were (125±38)g of K, (25±8)kg of muscle and (1,7±0,2)g of K/kg of body mass. The comparison between average values shows a clear difference, which allows to correlate a higher K mass with routine body activity. The technique has shown enough sensitivity for this application. (author)

  6. Effects of potassium deficiency, drought and weevils on banana ...

    African Journals Online (AJOL)


    Effects of potassium deficiency, drought and weevils on banana yield and economic performance in Mbarara, Uganda. S.H. Okech, P.J.A. van Asten*, C.S. Gold1and H. Ssali2. International Institute of Tropical Agriculture, P.O. Box 7878, Kampala, Uganda. 1Kawanda Agricultural Research Institute, P.O. Box 7065, Kampala, ...

  7. Determination and comparison of vitamin C, calcium and potassium ...

    African Journals Online (AJOL)



    Aug 18, 2008 ... from local supermarkets within Central Coast, New South Wales in Australia from late March to early. April 2007. ... calcium and potassium contents showed significant differences in all the samples with the trend of higher values for ... determination was done on the same day of purchase to counteract.

  8. Heat transfer to sodium--potassium alloy in pool boiling

    International Nuclear Information System (INIS)

    Subbotin, V.I.; Sorokin, D.N.; Kudryavtsev, A.P.; Brigutsa, V.I.


    Results of an experimental investigation of superheating, heat transfer, and critical heat fluxes for the sodium-potassium alloy of the eutectic composition (78 wt percent K), as well as the dependence of the critical heat flux on the component concentration, are presented. (U.S.)

  9. Characterization of verdete rock as a potential source of potassium

    Directory of Open Access Journals (Sweden)

    Wedisson Oliveira Santos


    Full Text Available Potassium is a nutrient found at low levels in Brazilian soils, requiring large inputs of fertilizers to achieve satisfactory crop yields. Brazil has high external dependence and limited reserves of soluble K mineral, which is traditionally exploited for the production of fertilizers. On the other hand, it is common the occurrence in the country of potassium-rich silicate minerals which are not commercially exploited. This study aimed to characterize mineralogically and chemically samples of verdete rock separated into size fractions and evaluate its potential as potassium fertilizer. The mineral composition of verdete rock is based on glauconite, quartz and feldspar. The total K2O content in verdete rock ranged from 5.18 to 9.0 dag/kg. The K content extracted in water or 2% citric acid was 2.4% below the total of K, indicating low reactivity of verdete rock and limitations for direct use as K source. The processes of physical fractionation and sedimentation in water are inefficient to promote the concentration of K in the different verdete rock fractions. The total K content in some samples are considerable and may enable the use of this rock as raw material for production of more reactive potassium fertilizers.

  10. Effects of potassium behaviour in soils on crop absorption | Lin ...

    African Journals Online (AJOL)

    Potassium (K) is one of the three major elements that play important roles in plants, such as maintaining turgor of cells, promoting activation of enzymes, and improving efficiency of photosynthesis. The types of K in soil may affect the plant absorption of K. K in soils includes K minerals, K in layered silicates (clay minerals), ...

  11. Synthesis of glycoluril catalyzed by potassium hydroxide under ultrasound irradiation. (United States)

    Li, Ji-Tai; Liu, Xiao-Ru; Sun, Ming-Xuan


    Synthesis of the glycolurils catalyzed by potassium hydroxide was carried out in 17-75% yield at 40 degrees C in EtOH under ultrasound irradiation. Compared to the method using stirring, the main advantage of the present procedure is milder conditions and shorter reaction time.

  12. Relationship between serum total magnesium and serum potassium ...

    African Journals Online (AJOL)

    Relationship between serum total magnesium and serum potassium in emergency surgical patients in a tertiary hospital in Ghana. Robert Djagbletey, Brenda Phillips, Frank Boni, Christian Owoo, Ebenezer Owusu-Darkwa, Papa Kobina Gyakye deGraft-Johnson, Alfred E. Yawson ...

  13. Effect of osmolarity on potassium transport in isolated cerebral microvessels

    Energy Technology Data Exchange (ETDEWEB)

    Lin, J.D.


    Potassium transport in microvessels isolated from rat brain by a technique involving density gradient centrifugation was studied in HEPES buffer solutions of varying osmolarity from 200 to 420 mosmols, containing different concentration of sodium chloride, choline chloride, or sodium nitrate. The flux of /sup 86/Rb into and out of the endothelial cells was estimated. Potassium influx was very sensitive to the osmolarity of the medium. Ouabain-insensitive K-component was reduced in hypotonic medium and was increased in medium made hypertonic with sodium chloride or mannitol. Choline chloride replacement caused a large reduction in K influx. Potassium influx was significant decrease when nitrate is substituted for chloride ion in isotonic and hypertonic media, whereas a slight decrease was found in hypotonic medium. The decrease of K influx in the ion-replacement medium is due to a decrement of the ouabain-insensitive component. Potassium efflux was unchanged in hypotonic medium but was somewhat reduced in hypertonic medium. The marked effect of medium osmolarity of K fluxes suggests that these fluxes may be responsible for the volume regulatory K movements. The possible mechanism of changes of K flux under anisotonic media is also discussed.

  14. Photoinduced Effects in EPR Spectra of Copper Doped Potassium Tantalate

    Czech Academy of Sciences Publication Activity Database

    Badalyan, A. G.; Azzoni, C. B.; Galinetto, P.; Mozzati, M. C.; Jastrabík, Lubomír; Rosa, Jan; Hrabovský, Miroslav; Syrnikov, P. P.; Trepakov, Vladimír

    514-516, - (2006), s. 138-141 ISSN 0255-5476 R&D Projects: GA AV ČR KJB1010301 Institutional research plan: CEZ:AV0Z10100521; CEZ:AV0Z10100520 Keywords : EPR * potassium tantalate * copper impurity * UV illumination effects Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.399, year: 2005

  15. Transmission spectra study of sulfate substituted potassium dihydrogen phosphate

    KAUST Repository



    Potassium dihydrogen phosphate (KDP) crystals with different amounts of sulfate concentration were grown and the transmittance spectrum was studied. A crystal with high sulfate replacement density exhibits heavy absorption property in the ultraviolet region which confirms and agrees well with former results. © 2013 Astro Ltd.

  16. Yield response of soybeans to levels of nitrogen and potassium ...

    African Journals Online (AJOL)

    A field trail was conducted at the University of Uyo Teaching and Research Farm in a high rainfall area of South eastern Nigeria to assess the yield response soybeans [ Glycine max (L.) Merrill ] to different levels of nitrogen and potassium fertilizers. The results showed that the number of pods/ plant, threshing percentage ...

  17. Histopathologic effect of potassium bromate on the kidney of adult ...

    African Journals Online (AJOL)

    Objective: We aimed to demonstrate the histopathologic effects of potassium bromate (KBrO ) on the kidney tissues of rats following 3 short-term and long-term exposures. Method: Twenty young wistar rats of weights 180-250g were divided into three groups. The control group A was sub-divided into two groups of three rats ...

  18. Syntheses, characterization and crystal structures of potassium and ...

    Indian Academy of Sciences (India)

    Syntheses, characterization and crystal structures of potassium and barium complexes of a Schiff base ligand with different anions. Bhavesh Parmar Kamal Kumar Bisht Pratyush Maiti Parimal Paul Eringathodi Suresh. Special issue on Chemical Crystallography Volume 126 Issue 5 September 2014 pp 1373-1384 ...

  19. Luminescence from potassium feldspars stimulated by infrared and green light

    DEFF Research Database (Denmark)

    Duller, G.A.T.; Bøtter-Jensen, L.


    A series of experiments are reported which investigate stimulated luminescence from potassium feldspar. The aim is to provide a basic phenomenological description of the response of the material to stimulation by heat, infrared radiation (875 DELTA 80 nm) and a green light wavelength band from 5 15...

  20. Response of Cassava Variety TMS/98/0505 to Potassium ...

    African Journals Online (AJOL)

    Two field experiments were used to study the response of a low cyanide cassava variety TMS/98/0505 to potassium fertilizer and time of harvest in a tropical ultisol in south eastern Nigeria in 2005/06 and 2006/07. In each year, a split plot design was adopted for the experiment with treatments arranged in a randomized ...