Pure Nitric Oxide Research Articles

Air-Stable P-Doping in Record High-Performance Monolayer WSe2 Devices

We demonstrate that a pure nitric oxide treatment at elevated temperatures provides a stable p-doping for monolayer WSe2. This approach allows achieving record high hole current densities of ~300 μA/μm and low contact resistances of ~950 Ω∙μm, while preserving the transistor on/off current ratio >2×106. This scalable pathway significantly improves the performance of p-type WSe2 transistors, opening new opportunities for advancing 2D integration.

Impact of nitridation on the active near-interface traps in gate oxides on 4H-SiC

In this paper we have implemented a recently proposed direct-measurement technique to characterize near-interface oxide traps (NITs) in SiC MOS capacitors with gate oxides obtained by four different processes. This measurement technique enables characterization of NITs with energy levels above the bottom of the conduction band, which are active in the accumulation mode of MOS capacitors on N-type SiC and in the strong inversion of N-channel MOSFETs. The measurements revealed that annealing in nitric oxide of thermally grown oxides in dry oxygen removes NITs that are further away from the SiC surface, but it leaves a defect with energy levels located between 0.13 eV and 0.23 eV above the bottom of conduction band. The oxides grown in pure nitric oxide exhibit NITs with energy levels above 0.2 eV. The measurements also show that low-temperature oxide deposition and subsequent annealing in nitric oxide resulted in the lowest density of NITs.

A Stability-Indicating HPLC Method for the Determination of Nitrosylcobalamin (NO-Cbl), a Novel Vitamin B12 Analog.

Nitrosylcobalamin (NO-Cbl), a novel vitamin B12 analog and anti-tumor agent, functions as a biologic 'Trojan horse', utilizing the vitamin B12 transcobalamin II transport protein and cell surface receptor to specifically target cancer cells. a stability-indicating HPLC method was developed for the detection of NO-Cbl during forced degradation studies. This method utilized an ascentis® RP-amide (150 mm × 4.6 mm, 5 μm) column at 35 °C with a mobile phase (1.0 mL min-1) combining a gradient of methanol and an acetate buffer at pH 6.0. Detection wavelengths of 450 and 254 nm were used to detect corrin and non-corrin-based products, respectively. NO-Cbl, synthesized from hydroxocobalamin and pure nitric oxide gas, was subjected to degradative stress conditions including oxidation, hydrolysis and thermal and radiant energy challenge. The method was validated by assessing linearity, accuracy, precision, detection and quantitation limits and robustness. The method was applied successfully for purity assessment of synthesized NO-Cbl and for the determination of NO-Cbl during kinetic studies in aqueous solution and in solid-state degradation assessments. This HPLC method is suitable for the separation of cobalamins in aqueous and methanolic solutions, for routine detection of NO-Cbl and for purity assessment of synthesized NO-Cbl. additionally, this method has potential application in identification and monitoring of diseases involving altered nitric oxide homeostasis where vitamin B12 therapy is utilized to scavenge excess nitric oxide, subsequently resulting in the in vivo production of NO-Cbl.

Use of ultra pure nitric oxide generated by the reduction of nitrogen dioxide to reverse pulmonary hypertension in hypoxemic swine

Inhaled nitric oxide (NO) has the capacity to selectively dilate pulmonary blood vessels, and thus enhance the matching of ventilation and perfusion, improve oxygenation and decrease pulmonary hypertension. However, existing approaches for the administration of inhaled NO are associated with the co-delivery of potentially toxic concentrations of nitrogen dioxide (NO2) due to the oxidation of NO in oxygen rich environments. We tested the ability of a novel methodology for generating highly purified NO through the reduction of NO2 by ascorbic acid to reverse pulmonary hypertension. In vitro testing demonstrated that the NO output of the novel device is ultrapure and free of NO2. An in vivo hypoxemic swine model of pulmonary hypertension was used to examine the dose response to NO in terms of pulmonary pressures and pulmonary vascular resistance. Pulmonary hypertension was induced by lowering inspired oxygen to 15% prior to treatment with inhaled ultra purified NO (1, 5, 20, and 80PPM). Hypoxemia increased mean pulmonary artery pressures and pulmonary vascular resistance. Inhaled ultra purified NO doses (down to 1PPM) show a marked reduction of hypoxemia-induced pulmonary vascular resistance. These experiments demonstrate a simple and robust method to generate purified inhaled NO that is devoid of NO2 and capable of reversing hypoxemia induced pulmonary hypertension.

Neutrophil-mediated formation of carcinogenic N-nitroso compounds in an in vitro model for intestinal inflammation

In order to study neutrophil-mediated formation of carcinogenic N-nitroso compounds as a mechanism of inflammation-related colon carcinogenesis, we designed an in vitro model for intestinal inflammation, consisting of a coincubation system with human colon cells (Caco-2 cells) and activated human neutrophils (PMN), as important immunoreactive cells. We investigated whether nitrosamines and nitrosamides could be formed upon addition of dimethylamine, morpholine and methylurea to the coincubations as nitrosatable precursors, which are known to produce carcinogenic N-nitroso compounds. Incubations of pure nitric oxide with dimethylamine and morpholine showed that NO-mediated formation of nitrosodimethylamine and nitrosomorpholine is possible under the incubation conditions. During the coincubations of activated PMN and Caco-2 cells, 0.34 nmol nitrite/10 6 PMN was produced. Dose-dependent formation of NMOR was observed in this PMN/Caco-2 system; addition of 5 mM morpholine resulted in a significantly increased NMOR formation of 4.2 nM. However, no detectable NDMA and methylnitrosourea were formed in this coincubation system. These results suggest that activated human neutrophils are able to synthesize carcinogenic N-nitrosamines, e.g. NMOR, which implies a risk of colon carcinogenesis during chronic inflammation. However, the observed relatively low level of nitrosation suggests that also other risk factors are contributing to the association between chronic inflammation and colon cancer risk.

Nature and Reactivity of the Active Species Formed After NO Adsorption and NO + O2Coadsorption on an Fe-Containing zeolite

Reactivity of the NO adspecies on Fe-ZSM-11 was studied by FTIR in situ. The effect of Fe content and the oxidation state of Fe in the samples were correlated with the catalytic activity. The relation between the adsorbed species, the Bronsted sites and catalytic activity in the SCR of NOx to N2 was also investigated. Moreover, FTIR allowed us to identify the active sites and the adsorption complexes present in FeMFI. Samples prepared by the sol–gel method with different Fe content displaying vastly different activity and selectivity in the reduction of NO to N2 with isobutane in excess of O2. Thus, in contact with pure nitric oxide, NO ions, mononitrosyl groups, nitro groups and nitrate ions have been identified. Fen+ active sites are the most probable centers for NO oxidation to NO2 and its further conversion to adsorbed nitro groups and nitrate ions, steps that are crucial for NO reduction. The concerted action of Fen+ and H+ sites of the catalysts over the NO conversion to N2 and isobutane conversion was analyzed.

The influence of vapor phase cleaning on the composition and the surface roughness of rapid thermal oxides and nitrided oxides

In this paper, the influence of various pre-oxidation cleanings on the Si/SiO2 interface and the oxide surface roughness is investigated. Different types of Vapor Phase Cleanings (VPC) are performed in an integrated STEAG AST cluster module and are compared to a standard wet cleaning process. The VPC uses Anhydrous Hydrogen Fluoride (AHF) and additional ozone cleaning. Directly after the cleaning, oxidation in pure oxygen (O2) is carried out in an integrated STEAG AST Rapid Thermal Processing (RTP) cluster module. Nitrided oxides are formed by annealing in pure nitric oxide (NO) gas directly after the oxidation. The nitrogen incorporation and distribution in the oxide is investigated using secondary ion mass spectroscopy (SIMS). The nitrogen concentration at the Si/SiO2 interface depends on the time and/or temperature of the NO annealing. For a 900°C annealing, the nitrogen incorporation varies from 0.5 at.% for a 5 s anneal to 2.5 at.% for a 60 s anneal. The nitrogen concentration of the oxides can be correlated with the different types of precleaning sequences which seems to be an effect of the different fluorine contents obtained after various cleaning procedures. The surface roughness of oxide layers formed after different pre-cleaning sequences is analyzed by Atomic Force Microscopy (AFM). A decrease in surface roughness is measured for oxidation performed at higher temperature. and for rapid thermal oxides produced after a cleaning procedure using AHF and ozone.

Electron beam-assisted formation of silicon oxynitride layers (3.5 nm) on silicon at moderate temperatures using NO gas: growth kinetics and mechanisms

Exposure to low pressures, P NO, of pure nitric oxide gas (1 × 10 −6 mbar ⩽ P NO ⩽ 1 × 10 −4 mbar) on a clean Si(1 0 0) surface at moderate temperatures T (room temperature (RT) to 600°C) leads to the formation of a 0.5 nm thick oxynitride passivating layer. Under low-energy electron beam irradiation (primary energy=250 eV, electron current density=1.25 mA cm −2) film growth occurs, independent of the temperature in the investigated range. A maximum thickness of about 3.5 nm can be obtained at 600°C and at RT. We show that the oxynitride films formed are, in fact, oxide films with an SiO x N y interfacial layer with the silicon substrate. The higher the temperature the larger the nitrogen content in the interfacial region without, practically, any increase in film thickness. A model for growth kinetics of these films in a nitric oxide environment is proposed. The reacting species are assumed to be O − and NO − ions which move in an electric field, acting as a driving force. The model assumes that the oxide growth is limited by time-dependent interface reaction of nitrogen at oxidation growth sites and by a thermally activated electron-stimulated desorption process of oxygen.

The protein inhibitor of neuronal nitric oxide synthase (PIN): characterization of its action on pure nitric oxide synthases

Neuronal NO synthase (nNOS) was discovered recently to interact specifically with the protein PIN (protein inhibitor of nNOS) [Jaffrey, S.R. and Snyder, S.H. (1996) Science 274, 774–777]. We have studied the effects on pure NOS enzymes of the same GST-tagged PIN used in the original paper. Unexpectedly, all NOS isoenzymes were inhibited. The IC 50 for nNOS was 18±6 μM GST-PIN with 63 nM nNOS after 30 min at 37°C. Uncoupled NADPH oxidation was inhibited similarly, whereas cytochrome c reductase activity, the K M for l-arginine, and dimerization were unaffected. We reconsider the physiological role of PIN in the light of these results.

Molecular design of biologically active biodegradable polymers for biomedical applications

AbstractThe objective of this research is to synthesize synthetic biodegradable polymers that would have biological functions similar to nitric oxide. Polyglycolide (PGA) was the synthetic biodegradable polymer and 4‐amino‐2,2,6,6‐tetramethylpiperidine‐1‐oxy (Tempamine) was chosen as the source of nitroxyl radicals. Tempamine nitroxyl radicals were chemically incorporated into the carboxylic acid chain ends of PGA macromolecules via amide linkage. The kinetics of in vitro hydrolytic release of Tempamine nitroxyl radicals from the host PGA in buffered media at 37 °C was studied. Tempamine nitroxyl radicals were released into the media via cleavage of either ester linkages in the PGA segments or/and the amide linkage between Tempamine and the PGA segments. The duration of hydrolysis would determine the type of degradation products that were different in the segmental length of the PGA component. A preliminary in vitro cell culture study of this new generation of biologically active biodegradable polymers indicated that it was able to retard the proliferation of smooth muscle cells as pure nitric oxide does.

Effect of exogenous nitric oxide and superoxide on interleukin-8 from human polymorphonuclear leucocytes

Patients with acute inflammatory lung injury are commonly treated with inhaled nitric oxide. Nitric oxide has profound immunoregulatory effects. Increased concentrations of the cytokine interleukin-8 (IL-8) in bronchoalveolar lavage fluid has been associated with disease severity. We have investigated the effects of a nitric oxide donor and a combined nitric oxide-superoxide donor on lipopolysaccharide-mediated accumulation of IL-8 from cultured human neutrophils. Interleukin-8 was measured in culture supernatant after 20 h using enzyme immunoassay. The combined nitric oxide-superoxide donor, 3-morpholinosydnonimine (SIN-1), dose-dependently decreased lipopolysaccharide-mediated IL-8 accumulation (P < 0.01). SIN-1 also decreased IL-8 accumulation from unstimulated neutrophils (P < 0.001). In contrast, the pure nitric oxide donor, 1,2,3,4-oxatriazolium 5-amino chloride (GEA-3162), increased stimulated IL-8 accumulation (P < 0.01) and also increased IL-8 accumulation in unstimulated cells (P < 0.002). Nitric oxide and superoxide have profound effects on IL-8. These results have important implications for the treatment of patients with acute lung injury with inhaled nitric oxide.

Reactions of nitric oxide and nitrogen dioxide with functionalised alkenes and dienes †

Pure nitric oxide does not add to alkenes containing acceptor or donor substituents, or to conjugated dienes, to afford β-nitrosoalkyl radicals. EPR spectra show that reactions are initiated by NO2 addition to carbon–carbon double bonds to produce β-nitroalkyl radicals which combine with nitric oxide to yield β-nitro-nitroso-compounds. The latter trap other radicals to afford mixtures of aminoxyl radicals and, where possible, the nitroso-compounds tautomerise to oximes which oxidise to iminoxyl radicals. EPR spectra obtained on reaction of NO–NO2 mixtures with 2,5-dimethylhexa-2,4-diene have shown the presence of a di-tert-alkylaminoxyl plus a tert,sec-dialkylaminoxyl, providing good support for this mechanism. Product analyses have established that 2-oxo-4-methylpent-3-ene and 1-acetylcyclohexene undergo extensive oxidative degradation. For enol ethers, reaction with NO–NO2 leads to hydrolysis giving the corresponding carbonyl compound and alcohol, followed by ketal and ester formation.

Nitric oxide prevents human platelet adhesion to fiber membranes in whole blood.

During cardiopulmonary bypass or long-term extracorporeal life support, foreign surface induced platelet deposition in the oxygenator causes deterioration of gas exchange. In this study, the authors evaluated the effectiveness of nitric oxide (NO) in reducing the adhesion of platelets in whole blood to the surface of hollow fiber membranes. For this purpose, a test chamber was designed consisting of a gas exchanger with ten mitsubishi multi-layered composite hollow fibers (MHF: 257 mm OD; 203 mm ID; 70 mm length) and a polypropylene tube (16 mm OD; 100 mm length). Pure N2 (control) or nitric oxide (NO) (100 ppm, 200 ppm in N2) were delivered into the test chamber previously filled with 13 ml human whole blood. Platelet counts and platelet factor 4 (PF4), as a measure of platelet activation, were measured before and after either 1 or 2 hr of testing, and fibers were observed under scanning electron microscopic study (SEM) after each experiment. In the control and 100 ppm NO groups, platelet counts decreased and the level of PF4 increased during the 1 hr period. In the 200 ppm NO group, almost no platelet deposition could be observed on the surface of fibers under SEM. In conclusion, NO flow through hollow fiber membranes can markedly reduce platelet adhesion. Additional quantitative studies should define the optimal concentration for this effect and determine if this finding could improve oxygenator function, especially under conditions of long-term support.

Degradation of oxynitride gate dielectric reliability due to boron diffusion

In this letter, we report on the impact of the suppression of boron diffusion via nitridation of SiO2 on gate oxide integrity and device reliability. SiO2 subjected to rapid thermal nitridation in pure nitric oxide (NO) is used to fabricate thin oxynitride gate dielectrics. Both n+ polycrystalline silicon (polysilicon) gated n-MOS (metal–oxide semiconductor) and p+-polysilicon gated p-MOS devices were subjected to anneals of different times to study the effect of dopant diffusion on gate oxide integrity. As expected, an advanced oxynitride gate dielectric will effectively alleviate the boron-penetration-induced flatband voltage instability in p+-polysilicon gated p-MOS capacitors due to the superior diffusion barrier properties. However, such improvements are observed in conjunction with some degradation of the oxide reliability due to the boron-blocking/accumulation inside the gate dielectric. Results show that even though the oxide quality is slightly degraded for NO-nitrided SiO2 with p+-polysilicon gates, p-MOSFETs (metal–oxide semiconductor field effect transistors) with these dielectrics still show improved interface stability as compared to conventional SiO2 due to the reduced boron penetration into the Si/SiO2 interface and underlying channel region.

Nitric oxide inhibition of human sperm motility

To determine the effect of nitric oxide (NO) on sperm motility in vitro. Normal human sperm separated by centrifugation through a discontinuous Percoll gradient and subsequent swim-up were incubated for up to 24 hours with NO donors, with and without the known NO quencher hemoglobin, as well as with agents that raise intracellular cyclic 3',5'-guanosine monophosphate (cGMP). Sperm respiration was determined by a tetrazolium-formazan spectrophotometric assay. Andrology laboratory. Absolute sperm motility and respiration. Sperm incubated with the NO donors 1 mM nitroprusside, 100 to 125 microM 3-morpholinosydnonimine, and 25 to 125 microM pure nitric oxide gas dissolved in buffer were inhibited in motility in a dose-dependent fashion. The inhibition could be reversed by the NO quencher hemoglobin. Agents that raise cellular cGMP (dibutyryl cGMP or 8-bromo-cGMP) did not inhibit motility. Nitric oxide inhibited sperm respiration, as measured by the tetrazolium-formazan assay. Nitric oxide reduces sperm motility, possibly by a mechanism involving inhibition of cellular respiration independent of an elevation of intracellular cGMP. Nitric oxide elaborated in the female or male genital tract in vivo could adversely influence sperm function and fertility.

Electrical properties and reliability of MOSFET's with rapid thermal NO-nitrided SiO/sub 2/ gate dielectrics

This paper reports on the performance and hot carrier reliability of N- and P-channel MOSFET's with oxynitride gate dielectrics fabricated by rapid thermal nitridation (RTN) of thermally grown SiO/sub 2/ in pure nitric oxide (NO) ambient. It is found that current drivability of N-channel MOSFET's increases with NO-nitridation of SiO/sub 2/. A significant enhancement in high field electron mobility is also observed with increasing NO-nitridation. P-channel MOSFET's with NO-nitrided SiO/sub 2/ gates show somewhat lower current drivability and hole mobility compared to SiO/sub 2/ for both low- and high-V/sub g/. Both N- and P-channel MOSFET's with NO-nitrided oxides show excellent immunity to channel hot carrier degradation. The improvement in hot-carrier reliability is attributed to the efficient incorporation of nitrogen in the dielectric through NO-nitridation. A 1000/spl deg/C, short 10-second NO-anneal was found to be the optimum nitridation condition since, compared to control oxide devices, these devices showed comparable electron and hole mobility but significantly enhanced hot-carrier immunity.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Nitric oxide implication in the control of neurosecretion by chromaffin cells.

In this work, we have studied the effects of pure nitric oxide (NO) on the regulation of catecholamine (CA) secretion by chromaffin cells, as well as the possible presence of its synthesizing enzyme L-arginine:NO synthase (NOS) in these cells. Our results show that NO produces a large stimulation of basal CA secretion. This effect was calcium- and concentration-dependent (EC50 = 64 +/- 8 microM) and was not due to nonspecific damage of the tissue by NO. NO also modulates the CA secretion evoked by nicotine in a dose-dependent manner. Although it has a stimulatory effect on the CA secretion evoked by low doses of nicotine (< 3 microM; EC50 = 16 +/- 3 microM), it produces a dose-dependent inhibition of the CA secretion induced by high doses of nicotine (> or = 30 microM; IC50 = 52 +/- 6 microM). The mechanism by which NO modulates CA secretion seems to be through the increase in the cyclic GMP levels, because there was a close correlation between the CA secretion and the cyclic GMP levels. The presence of a specific activity of NOS in chromaffin cells has been demonstrated by two independent methods: release of [14C]citrulline from [14C]arginine and formation of an NO-hemoglobin complex. NOS activity was about 0.5 pmol/min/mg of protein. It was calcium- and mainly calmodulin-dependent and could be specifically blocked by the NOS inhibitor N-methyl-L-arginine. These results suggest that NO could be an important intracellular messenger in the regulation of neurosecretion in chromaffin cells.

The effect of preadsorbed sulfur on nitric oxide reduction on porous platinum black electrodes

Sulfur can be deposited on porous platinum black gas diffusion cathodes to influence the course of the electrogenerative reduction of nitric oxide. Polarization (performance) curves and reactor selectivity data are compared for untreated cathodes and those treated with reduced SO 2. Pure and dilute nitric oxide cathode feeds were used. With pure nitric oxide, the limiting current corresponding to nitrous oxide production was reduced 65% by preadsorbed sulfur. With dilute nitric oxide the two limiting currents observed were only slightly decreased by sulfur deposition. With both feeds adsorbed sulfur affects product distribution at low cell potentials so that hydroxylamine production is favored. The surface of the platinum black electrodes was characterized by hydrogen adsorption, and sulfur coverages on treated electrodes were determined by cyclic voltammetry in a separate three-electrode cell. The results from electrogenerative reduction are discussed in terms of steric and mechanistic consequences of sulfur coverages.

The decomposition of nitric oxide on a heated platinum wire

The catalytic rate of decomposition of pure nitric oxide on platinum (2NO → N 2 + O 2) was measured employing the batch, hot-wire technique at wire temperatures in the range 900–1200°C and at total pressures from 400–2260 torr. Chemisorbed oxygen is known to inhibit the rate of this reaction but very little surface oxygen is present at these elevated temperatures and thus an effectively clean platinum surface was realized. Also the experiments were limited to low conversions and thus low oxygen partial pressures ( P O 2 → O 2), again minimizing the likelihood of oxygen inhibition. A Rideal—Eley type rate expression: − r (moles NO reached/cm 2 . sec) = k 2 P 2 NO/(1 + K 1 P O 2 + K 2 P NO) describes quite well the dependence of the measured rate of the NO partial pressure on P NO. In contrast the data are not fit well by a Langmuir—Hinshelwood type rate-expression, similar to that above except for a unimolecular term P NO in the numerator. Owing to the large values of P NO and low conversions used in the present study with P O 2 → O, the study focused on the kinetics with respect to NO itself. For the above Rideal—Eley mechanism: k 2 ≊ 4·63 × 10 −4 exp (−8,600/ RT) mol/cm 2 . atm 2 . sec and K 2 ≊ 3 · 5 × 10 −2 exp (11,300/ RT) atm −1.

Microwave multiple-pulse breakdown in nitric oxide

The minimum value of the peak RMS electric field for the TE11 mode resulting in the breakdown of pure nitric oxide has been measured in the pressure range 0·5-10 Torr. The microwave frequency was 9·361 GHz. For each pressure selected, the breakdown formation time τ was found as a function of the electric field. For all breakdown formation times, the minimum breakdown field occured at a pressure of 3-4 Torr, the pulse repetition frequency and pulse length being 100 pps and 4·7 ms respectively.