Effect Of NH Research Articles

The weak bases NH3 and trimethylamine inhibit the medium and slow afterhyperpolarizations in rat CA1 pyramidal neurons

The weak bases NH(3) and trimethylamine (TMeA), applied externally, are widely used to investigate the effects of increasing intracellular pH (pH(i)) on neuronal function. However, potential effects of the compounds independent from increases in pH(i) are not usually considered. In whole-cell patch-clamp recordings from rat CA1 pyramidal neurons, bath application of 1-40 mM NH(4)Cl or TMeA HCl reduced resting membrane potential and input resistance, inhibited the medium and slow afterhyperpolarizations (AHPs) and their respective underlying currents, mI(ahp) and sI(ahp), and led to the development of depolarizing current-evoked burst firing. Examined in the presence of 1 microM TTX and 5 mM TEA with 10 mM Hepes in the recording pipette, NH(3) and TMeA increased pH(i) and the magnitudes of depolarization-evoked intracellular [Ca(2+)] transients, Ca(2+)-dependent depolarizing potentials, and inward Ca(2+) currents but reduced the slow AHP and sI(ahp). When internal H(+) buffering power was raised by including 100 mM tricine in the patch pipette, the effects of NH(3) and TMeA to increase pH(i) and augment Ca(2+) influx were attenuated whereas the reductions in the slow AHP and sI(ahp) (as well as membrane potential and input resistance) were maintained. The findings indicate that increases in pH(i) contribute to the increases in Ca(2+) influx observed in the presence of NH(3) and TMeA but not to the reductions in membrane potential, input resistance or the magnitudes of AHPs. The results have implications for the interpretation of data from experiments in which pH(i) is manipulated by the external application of NH(3) or TMeA.

Apical ammonium inhibition of cAMP-stimulated secretion in T84 cells is bicarbonate dependent

Normal human colonic luminal (NH(4)(+)) concentration ([NH(4)(+)]) ranges from approximately 10 to 100 mM. However, the nature of the effects of NH(4)(+) on transport, as well as NH(4)(+) transport itself, in colonic epithelium is poorly understood. We elucidate here the effects of apical NH(4)(+) on cAMP-stimulated Cl(-) secretion in colonic T84 cells. In HEPES-buffered solutions, 10 mM apical NH(4)(+) had no significant effect on cAMP-stimulated current. In contrast, 10 mM apical NH(4)(+) reduced current within 5 min to 61 +/- 4% in the presence of 25 mM HCO(3)(-). Current inhibition was not simply due to an increase in extracellular K(+)-like cations, in that the current magnitude was 95 +/- 5% with 10 mM apical K(+) and 46 +/- 3% with 10 mM apical NH(4)(+) relative to that with 5 mM apical K(+). We previously demonstrated that inhibition of Cl(-) secretion by basolateral NH(4)(+) occurs in HCO(3)(-)-free conditions and exhibits anomalous mole fraction behavior. In contrast, apical NH(4)(+) inhibition of current in HCO(3)(-) buffer did not show anomalous mole fraction behavior and followed the absolute [NH(4)(+)] in K(+)-NH(4)(+) mixtures, where K(+) concentration + [NH(4)(+)] = 10 mM. The apical NH(4)(+) inhibitory effect was not prevented by 100 microM methazolamide, suggesting no role for apical carbonic anhydrase. However, apical NH(4)(+) inhibition of current was prevented by 10 min of pretreatment of the apical surface with 500 microM DIDS, 100 microM 4,4'-dinitrostilbene-2,2'-disulfonic acid (DNDS), or 25 microM niflumic acid, suggesting a role for NH(4)(+) action through an apical anion exchanger. mRNA and protein for the apical anion exchangers SLC26A3 [downregulated in adenoma (DRA)] and SLC26A6 [putative anion transporter (PAT1)] were detected in T84 cells by RT-PCR and Northern and Western blots. DRA and PAT1 appear to associate with CFTR in the apical membrane. We conclude that the HCO(3)(-) dependence of apical NH(4)(+) inhibition of secretion is due to the action of NH(4)(+) on an apical anion exchanger.

Effect of NH 3 gas on the electrical properties of single-walled carbon nanotube bundles

This study deals with the fabrication of sensors from single-walled carbon nanotubes (SWNTs) of 1.2 nm in diameters by a screen-printing method. These sensors have been exposed to ammonia (NH 3) gas at room temperature with nitrogen as the carrier gas. It was found that the electrical properties of SWNTs alter with temperature or the adsorption of ammonia gas. The SWNT is very sensitive to NH 3 gas. It can detect NH 3 in as low as concentration of 5 ppm. The sensitivity increases with increasing concentration. A saturation state is established at a concentration of ∼40 ppm, and the sensitivity of the sensor continues to increase in conjunction with an increase in concentration levels. Both the heating and increasing flux rates of carrier gas are used to improve gas desorption. The adsorption mechanism of gaseous molecules on SWNT bundle is discussed.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry protocol for monitoring the progress of enzymatic 13C/ 15N-labeled DNA syntheses

We demonstrate that a simple matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry protocol provides a rapid and accurate method for monitoring the stage and completeness of enzymatic DNA syntheses. A crucial step of these syntheses is to quench the reaction at the desired nucleotide length. This is especially important when expensive, e.g., 13C/ 15N-labeled DNA segments, are synthesized for multinuclear magnetic resonance purposes to reveal detailed structural information. The analyses of three templates for a human telomeric 22-mer, a wild type, and a mutant human c-MYC promoter (18- and 22-mer) DNA and their reactions with the 3′–5′ exo − Klenow fragment of DNA polymerase I demonstrate the usefulness of our protocol. Small amounts of samples (ca. 1–2 μl each) were taken from the reaction mixtures at different times and analyzed promptly by MALDI-TOF, applying our successive on-plate desalting method that eliminates the insensitivity of the MALDI technique at high salt content. The progress of the reaction was detected by monitoring the relative intensity ratios of ions corresponding to the desired products and the primer–template complexes. The effectiveness of NH 3 cleavage leading to final products was also followed by MALDI-TOF in successful enzymatic reactions.

The effects of NH 4+ and NO 3− on growth, resource allocation and nitrogen uptake kinetics of Phragmites australis and Glyceria maxima

The effects of NH 4 + or NO 3 − on growth, resource allocation and nitrogen (N) uptake kinetics of two common helophytes Phragmites australis (Cav.) Trin. ex Steudel and Glyceria maxima (Hartm.) Holmb. were studied in semi steady-state hydroponic cultures. At a steady-state nitrogen availability of 34 μM the growth rate of Phragmites was not affected by the N form (mean RGR = 35.4 mg g −1 d −1), whereas the growth rate of Glyceria was 16% higher in NH 4 +-N cultures than in NO 3 −-N cultures (mean = 66.7 and 57.4 mg g −1 d −1 of NH 4 + and NO 3 − treated plants, respectively). Phragmites and Glyceria had higher S/R ratio in NH 4 + cultures than in NO 3 − cultures, 123.5 and 129.7%, respectively. Species differed in the nitrogen utilisation. In Glyceria, the relative tissue N content was higher than in Phragmites and was increased in NH 4 + treated plants by 16%. The tissue NH 4 + concentration (mean = 1.6 μmol g fresh wt −1) was not affected by N treatment, whereas NO 3 − contents were higher in NO 3 − (mean = 1.5 μmol g fresh wt −1) than in NH 4 + (mean = 0.4 μmol g fresh wt −1) treated plants. In Phragmites, NH 4 + (mean = 1.6 μmol g fresh wt −1) and NO 3 − (mean = 0.2 μmol g fresh wt −1) contents were not affected by the N regime. Species did not differ in NH 4 + (mean = 56.5 μmol g −1 root dry wt h −1) and NO 3 − (mean = 34.5 μmol g −1 root dry wt h −1) maximum uptake rates ( V max), and V max for NH 4 + uptake was not affected by N treatment. The uptake rate of NO 3 − was low in NH 4 + treated plants, and an induction phase for NO 3 − was observed in NH 4 + treated Phragmites but not in Glyceria. Phragmites had low K m (mean = 4.5 μM) and high affinity (10.3 l g −1 root dry wt h −1) for both ions compared to Glyceria ( K m = 6.3 μM, affinity = 8.0 l g −1 root dry wt h −1). The results showed different plasticity of Phragmites and Glyceria toward N source. The positive response to NH 4 +-N source may participates in the observed success of Glyceria at NH 4 + rich sites, although other factors have to be considered. Higher plasticity of Phragmites toward low nutrient availability may favour this species at oligotrophic sites.

Synthesis and thermal behavior of the dawsonite-type solid solution K 1− x(NH 4) xAl(OH) 2CO 3

This paper reported the hydrothermal synthesis and thermal behavior of a novel kind of dawsonite-type solid solution K 1− x (NH 4) x Al(OH) 2CO 3 ( x = 0.2–0.93). The effects of NH 4 +/K + molar ratio in the starting reactants and the hydrothermal reaction time on the composition of K 1− x (NH 4) x Al(OH) 2CO 3 were investigated. In addition, the influence of the composition on the thermal stability of the solid solution was studied by DTA/TG analyses. It was indicated that compound K 0.44(NH 4) 0.56Al(OH) 2CO 3 ( x = 0.56) is the most thermally stable one among all the dawsonite type solid solutions. Furthermore, K-β-Al 2O 3, a solid state K + ion conductor was prepared by calcining K 0.19(NH 4) 0.81Al(OH) 2CO 3 at 1250 °C.

Effect of NH 4+/NO 3− availability on nitrate reductase activity and nitrogen accumulation in wetland helophytes Phragmites australis and Glyceria maxima

The effect of NH 4 +/NO 3 − availability on nitrate reductase (NR) activity in Phragmites australis and Glyceria maxima was studied in sand and water cultures with the goal to characterise the relationship between NR activity and NO 3 − availability in the rhizosphere and to describe the extent to which NH 4 + suppresses the utilization of NO 3 − in wetland plants. The NR activity data showed that both wetland helophytes are able to utilize NO 3 −. This finding was further supported by sufficient growth observed under the strict NO 3 − nutrition. The distribution of NR activity within plant tissues differed between species. Phragmites was proved to be preferential leaf NO 3 − reducer with high NR activity in leaves (NR max > 6.5 μmol NO 2 − g dry wt −1 h −1) under all N treatments, and therefore Phragmites seems to be good indicator of NO 3 − availability in flooded sediment. In the case of Glyceria the contribution of roots to plant NO 3 − reduction was higher, especially in sand culture. Glyceria also tended to accumulate NO 3 − in non-reduced form, showing generally lower leaf NR activity levels. Thus, the NR activity does not necessarily correspond with plant ability to take up NO 3 − and grow under NO 3 −-N source. Moreover, the species differed significantly in the content of compounds interfering with NR activity estimation. Glyceria, but not Phragmites, contained cyanogenic glycosides releasing cyanide, the potent NR inhibitor. It clearly shows that the use of NR activity as a marker of NO 3 − utilization in individual plant species is impossible without the precise method optimisation.

Effect of ammonium chloride and dietary phosphorus in the azotaemic rat. I. Renal function and biochemical changes.

Both dietary phosphorus restriction and the ingestion of ammonium chloride (NH(4)Cl) given to rats on a high-phosphorus diet have been shown to preserve renal function in the azotaemic rat. Parathyroidectomy also has been reported to preserve renal function and, in addition, to prevent kidney hypertrophy in the remnant kidney model. Our goals were (i) to evaluate in azotaemic rats the effect of dietary phosphorus on renal function in a shorter time frame than previously studied and (ii) to determine whether NH(4)Cl administration (a) enhances the renoprotective effect of dietary phosphorus restriction and (b) improves renal function in the absence of parathyroid hormone (PTH). High (H; 1.2%), normal (N; 0.6%) and low (L; <0.05%) phosphorus diets (PD) were given for 30 days to 5/6 nephrectomized rats. In each dietary group, one-half of the rats were given NH(4)Cl in the drinking water. The six groups were HPD + NH(4)Cl, HPD, NPD + NH(4)Cl, NPD, LPD + NH(4)Cl and LPD. The effect of NH(4)Cl administration was also evaluated in 5/6 nephrectomized, parathyroidectomized (PTX) rats on NPD. In each of the three dietary phosphorus groups, creatinine and urea clearances were greater (P<0.01) in rats receiving NH(4)Cl. Neither creatinine nor urea clearance was reduced by high dietary phosphorus. Urine calcium excretion was greatest in the LPD group and was increased (P < or = 0.001) in all three groups by NH(4)Cl ingestion. An inverse correlation was present between plasma calcium and phosphorus in the parathyroid intact (r = -0.79, P<0.001) and PTX groups (r = -0.46, P = 0.02). In PTX rats, NH(4)Cl ingestion increased (P < or = 0.01) creatinine and urea clearances and both an increasing plasma calcium concentration (r = 0.67, P<0.001) and urine calcium excretion (r = 0.73, P<0.001) increased urine phosphorus excretion. At 30 days of renal failure (i) NH(4)Cl ingestion increased creatinine and urea clearances, irrespective of dietary phosphorus; (ii) high urine calcium excretion, induced by dietary phosphorus restriction and NH(4)Cl ingestion, did not adversely affect renal function; (iii) high dietary phosphorus did not decrease renal function; (iv) the absence of PTH did not preserve renal function or prevent NH(4)Cl from improving renal function; and (v) both an increasing plasma calcium concentration and urine calcium excretion resulted in an increase in urine phosphorus excretion in PTX rats.

The effects of ammonia on the growth of large-scale patterned aligned carbon nanotubes using thermal chemical vapor deposition method

A systematic study on the effects of NH 3 on the growth of carbon nanotubes in atmospheric thermal-CVD was undertaken. Large-scale patterned aligned CNTs were prepared by thermal-CVD method in temperature of 900 °C. The effects of NH 3 on the growth stage were investigated. Patterned Ni-catalyst of thickness 10 nm was prepared by optical lithography and e-gun evaporation on p-Si(100) substrates lift-off process. Following a heating process, the CNTs were then grown at 900 °C by thermal-CVD method using argon (Ar), NH 3 and methane (CH 4) as the diluting, reactive and carbon source gases, respectively. In the experimental results, aligned CNTs could be synthesized with mixing ratio of CH 4/NH 3 larger or less than 1 varying the fraction of Ar dilution. The role of NH 3 was considered to enhance the catalyst activity by preventing it from being passivated. Furthermore, vertically aligned free-standing CNTs were observed at low CNT density when dealing the introduction of NH 3; meanwhile, a transition of growth characteristics from spaghetti-like to vertically-aligned was observed when the growth condition was switched from low NH 3 to high NH 3 ratio. Without Ar dilution, high NH 3 flow relative to CH 4 seemed to hamper the CNT growth as well as the degree of straightness and vertical alignment. A kinetics-based growth mechanism, either on carbon supply limited kinetics or on carbon diffusion limited kinetics, in combination with the proposed role of NH 3, can successfully explain the effect of NH 3 in different experimental conditions. Furthermore, the base growth mode was observed on all process conditions of thermal CVD in this work, and a model based on the effect of surface radius of curvature of catalyst particles on the surface energy based on broken bond model was adopted to explain the formation of bamboo-like structure and the correlation between the spacing of cone-shaped graphite and its straightness.

EIS study of the effect of high levels of NH 3 on the deformation of polyester-coated galvanised steel at different relative humidities

The effect of NH 3 on the deformation of polyester-coated galvanised steel at different relative humidities (RHs) was investigated using electrochemical impedance spectroscopy. Measurements were performed on specimens which had been tested in accelerated gaseous corrosion test. For this purpose the samples were subjected to NH 3 gas for 16 and 24 days in atmospheric test cells with adjusted RH from 60 to 100%. Subsequently, the impedance response of the coated material was measured and evaluated. The results indicated that the coating performance varies with RH. At lower RH, remarkably, the coating remained effectively intact with the coating resistance varying inversely with RH. This work is relevant to the application of such organic-coated products adjacent to some plant flues were high levels of NH 3 occur in association with high humidity.

Physiological and growth responses of the montane bryophyte Racomitrium lanuginosum to atmospheric nitrogen deposition.

• The effects of nitrogen (N) deposition on the moss Racomitrium lanuginosum within montane heath in Scotland were investigated over 5yr. • Permanent field plots were sprayed with KNO3 or NH4 Cl solutions, at doses equivalent to 10 and 40kgNha-1 yr-1 , in 3-6 applications each summer. • Racomitrium growth and cover were severely reduced by N addition, whilst the proportion of dead shoots greatly increased. N dose decreased inducibility of shoot nitrate reductase activity (NRA), suggesting that N saturation of Racomitrium occurred, and caused an increase in potassium leakage. At high dosage, effects of NH4 + were more detrimental than NO3 - . • Physiological responses to N indicate that the habitat's critical load (CL) is exceeded by addition of 10kgNha-1 yr-1 . The differential toxicity of the two forms of N suggests that predominant ion type in deposition should be taken into consideration when CLs are set. In contrast to tissue N, NRA correlated well with shoot growth, and may thus be a useful biological indicator of moss condition.

Effect of NH3 thermal treatment on an atomic layer deposited on tungsten films and formation of W–B–N

The effect of ammonia (NH3) ambient annealing on a tungsten (W) film deposited by atomic layer deposition at temperatures ranging from 400–700 °C is discussed. The as-deposited film contains approximately 20 at. % of boron which is chemical bound to W (W–B) having a resistivity of 128 μΩ cm. The film has an amorphous structure, which does not transform into crystalline phase during annealing. As a result of annealing in NH3 ambient, a tungsten ternary phase (W–B–N) forms at the surface; its binding configuration depends on the annealing temperature. Below 500 °C, nitrogen is chemically bonded to tungsten (W–N) while maintaining a W–B bond. Above 600 °C, nitrogen-rich W–B–N forms, in which nitrogen atoms have chemical binding with boron (B–N) and tungsten (W–N). It was found that a film annealed at higher temperatures has a resistivity of 107 μΩ cm, and thermal desorption of boron and nitrogen containing species is not observed during the thermal process. In addition, tungsten oxide formed at the surface during exposure to air is reduced during the NH3 annealing process. X-ray photoelectron spectroscopy, x-ray diffraction, transmission electron microscopy, and thermal desorption spectroscopy were used for film characterization.

Density control of carbon nanotubes using NH 3 plasma treatment of Ni catalyst layer

The effect of NH 3 plasma pre-treatment on the growth characteristics of CNTs was investigated. We observed that NH 3 plasma pre-treatment etched and conglomerated Ni catalyst film, resulting in the formation of Ni nanoparticles. The aligned CNTs from the Ni nanoparticles were grown by plasma enhanced chemical vapor deposition (PECVD). As Ni film thickness decreased from 300 to 30 Å, the size of Ni nanoparticles decreased about from 140 to 90 nm and the average diameter of CNTs became smaller. As the NH 3 plasma power was increased, the density of Ni nanoparticles was decreased, leading to the decrease in the density of CNTs.

Role of Ammonium Hydrate in the Endometrium/Myometrium

1 Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv, Ukraine. Correspondence should be addressed to H. V. Danylovych (e-mail: kinet@biochem.kiev.ua). We studied the possibility of production of ammonium hydrate (NH 3 ) in the endometrium and its effect on the Са/Н exchange in the plasma membrane of myometrial cells. Stroma cells of the endometrium and a suspension of intact myocytes were obtained from porcine and rat utera, respectively, using standard techniques. The АМР-deaminase activity was measured according to the characteristic maximum of ІМР absorption in UV light, while the amount of NH 3 was measured by staining using TNBS with subsequent colorimetry of the product. The concentration of cytosolic Саand intracellular рН in myocytes were measured using the fluorescent probes Fura-2AM and BCECFAM, respectively. It was found that in the suspension of stroma cells the activity of the main enzyme responsible for NH 3 biosynthesis, AMP deaminase, measured in the presence of 0.2% Triton-Х100 and 1.5 М KCl, is 53 ± ± 2 μmol ІМР/mg protein per 1 h. The basal production of NH 3 released to the extracellular medium in the cell suspension was equal, on average, to 9.5 ± ± 2.5 nmol/mg protein per 25 min. This production considerably increased after stimulation of the cells with 1 μM acetylcholine and was effectively suppressed by a relatively specific inhibitor of AMP deaminase, fluoride ions. When 0.1 mM NH 3 was added to the suspension of myometrical myocytes, the рН of the myoplasm increased from 6.7 in the control to 8.1 due to alkalization of the extracellular space by NH 4 . This increase was partially inhibited by inhibitors of the Н and K channels, 4-aminopyridine and tetraetylammonium. NH 3 induced alkalization of the extracellular space resulted in a signifi cant increase of acetylcholine (0.1 mM)-stimulated Са entry into myocytes. This process was completely suppressed by 1.0 mM Cd and 1.0 nМ nifedipine, which was indicative of a channel activity-mediated increase in the membrane permeability. Introduction of 0.05% 2,4-dinitrophenole, a protonophore, provided a dramatic drop in the effect of NH 3 , while an inhibitor of the Na/Н exchanger, amyloride (0.1 mM), signifi cantly increased this effect. Our fi ndings allow us to suppose that AMP deaminase plays a role in the production of NH 3 by stroma endometrium cells upon acetylcholine stimulation. NH 3 is released into the extracellular space and, diffusing from the endometrium, can infl uence transport processes in the plasmalemma of uteral myocytes. A solution of NH 3 , when added to the suspension of myocytes, initiates a signifi cant increase in the рН value in the extracellular space and, consequently, an increase in the proton gradient on the membrane and intensifi cation of the transmembrane Н release from the myoplasm. The rates of these processes are signifi cantly higher than that of NH 3 entry into the cell because the permeability of the membrane for Н is four orders of magnitude greater that that for NH 3 . Analysis of our results shows that the liganddirected passive Са transport can be intensifi ed by dispersion of a transmembrane proton gradient, which exists on the plasma membrane of myocytes due to cytosolic oxidative processes and can increase due to the production of NH 3 in the endometrium. The role of NH 3 , which diffuses from the endometrium, in the regulation of functional activity of the uterus needs further investigation, but even now we can suppose that NH 3 molecules (or NH 4 ions) can play the role of a paracrine regulator in the endometrium-myometrium system.

Effects of soil amendments on germination and emergence of downy brome (Bromus tectorum) and Hilaria jamesii

Downy brome is an introduced Mediterranean annual grass that now dominates millions of hectares of western U.S. rangelands. The presence of this grass has eliminated many native species and accelerated wildfire cycles. The objective of this study was to identify soil additives that allowed germination but inhibited emergence of downy brome, while not affecting germination or emergence of the native perennial grass Hilaria jamesii. On the basis of data from previous studies, we focused on additives that altered the availability of soil nitrogen (N), phosphorus (P), and potassium (K). Most water-soluble treatments inhibited downy brome germination and emergence. We attribute the inhibitory effects of these treatments to excessive salinity and ion-specific effects of the additives themselves. An exception to this was oxalic acid, which showed no effect. Most water-insoluble treatments had no effect in soils with high P but did have an effect in soils with low P. Zeolite was effective regardless of P level, probably due to the high amounts of Na+ it added to the soil solution. Most treatments at higher concentrations resulted in lower downy brome emergence rates in soils currently dominated by downy brome than in uninvaded (but theoretically invadable) Hilaria soils. This difference is possibly attributable to inherent differences in labile soil P. In Stipa soils, where Stipa spp. grow, but which are generally considered to be uninvadable by downy brome, additions of high amounts of N resulted in lower emergence. This may have been an effect of NH4+ interference with uptake of K or other cations or toxicity of high N. We also saw a positive relationship between downy brome emergence and pH in Stipa soils. Hilaria development parameters were not as susceptible to the treatments, regardless of concentration, as downy brome. Our results suggest that there are additions that may be effective management tools for inhibiting downy brome in calcareous soils, including (1) high salt applications, (2) K-reducing additions (e.g., Mg), and (3) P-reducing additions.

Effect of NH 3 and thickness of catalyst on growth of carbon nanotubes using thermal chemical vapor deposition

The growth behavior of carbon nanotubes synthesized from C 2H 2 using thermal chemical vapor deposition method has been investigated. The formation of catalytic cobalt nanoparticles was much enhanced when using NH 3 as the environment gas, whereas NH 3 introduced during nanotubes growth does not play a key role in growing the vertically aligned nanotubes. The role of NH 3 is to obtain the high density of nucleation sites for nanotube growth by inhibiting amorphous carbon generation in the initial stage of synthesis. We found unexpected behavior in terms of the length and growth time during nanotube growth. The length of the nanotubes is inversely proportional to the size of nanoparticle just in the initial stages of growth and thick catalyst.

H2O-catalyzed formation of O3in the self-reaction of HO2: a computational study on the effect of nH2O (n = 1–3)

The effect of nH2O (n = 1–3) on the association energies of H2O complexes and on the barriers for the formation of O3 in the self-reaction of HO2 reaction has been investigated by ab initio molecular orbital calculations at the modified Gaussian-2 (G2M) level of theory. The results show that H2O can affect the complex and O3 formation processes: the more H2O molecules participating in the reaction, the higher stability of the association complexes and the greater the lowering of the O3 elimination barrier becomes. For the isomers of the reactions, more hydrogen bonds being formed in the complexes enhances their stabilities. A preliminary kinetic calculation shows that below room temperature, H2O may enhance the formation of O3 noticeably.

New synthesis of 9-methanesulfonyl-1,2,3,9a-tetrahydro- and 1,2,3,4-tetrahydrocarbazoles from N-methanesulfonyl-2-(cyclohex-1-enyl)aniline

The reaction of N-methanesulfonyl-2-(cyclohex-1-en-1-yl)aniline with Br 2 in the presence of NaHCO 3 in MeCN results in N -methanesulfonyl-2-(6-bromocyclohex-1-en-1-yl)aniline, which was cyclised to 9-methanesulfonyl-1,2,3,4-tetrahydrocarbazole, and the effect of NH 3 leads to 9-methanesulfonyl-1,2,3,9a-tetrahydrocarbazole. The reaction of the latter with molecular bromine in the presence of pyridine results in 1-(9-methanesulfonyl-1,2,3,4-tetrahydro-4-carbazolyl)pyridinium bromide in a good yield.

The Effect of NH[sub 3] Plasma Treatment on the Electroless Copper Deposition on TaN[sub x] (x = 0=1) Diffusion Barriers

The effect of NH 3 plasma treatment of the surface of the TaN x barrier films on electroless copper deposition on TaN x films was investigated to enhance the quality of electroless Cu with the low electrical resistivity of TaN x barrier films. Electrical resistivities of TaN x barrier films were increased by less than 10% by plasma treatment. Auger electron spectroscopy depth profiles results showed that only a small fraction of the TaN x layer depth was affected by the plasma treatment. Field-emission scanning electron microscope micrographs of palladium activated TaN x films showed the number density of palladium nuclei on TaN x barriers was remarkably increased by the NH 3 plasma treatment. Electroless copper deposition on TaN x barriers was improved significantly by the NH 3 plasma treatment without a large increase in electrical resistivity.

Spatio-kinetic variation of methane oxidizing bacteria in paddy soil at mid-tillering: effect of N-fertilizers

Laboratory experiments were conducted to evaluate the variation ofpopulation size of methanotrophs (MOB) and CH4 oxidation pattern inflooded rice soils sampled at three spatial points (rhizosphere, bulk and baresoils). Rhizosphere soil had higher MOB population size (301.1 ×105 cells g−1 dry soil) than bulk(37.2× 105 cells g−1 dry soil) andbare soil (19.1 × 105 cells g−1dry soil). The population size of MOB followed a decreasing trend with respectto fertilizer (urea ≤ NH4NO3 ≤ NH4Cl≤ control). The result indicated that rhizosphere soil presented thestrongestCH4 oxidation activities, as shown by the highest values of the twokinetic parameters (K m(app) andV max). K m andV max increased significantly from bare to bulkto rhizosphere soil in control and fertilized soil and ranged from 6.2 to 133.2μg g−1 dry soil and from 0.03 to 0.41μg h−1 g−1 dry soil,respectively. The differences in K m andV max among the three soils (rhizosphere, bulkand bare) in this study could be due to differential species composition ofmethanotrophic community and/or to conditioning of MOB under different soilmicroenvironments. The present study has demonstrated a competitive inhibition effectof NH4 +-N on CH4 oxidation.