Measurements of transition probabilities for two N I infrared transitions and their application for diagnostics of low temperature plasmas

Spectra emitted from a wall-stabilized arc, running in a gas mixture of helium, argon, nitrogen, oxygen and traces of hydrogen have been studied. Intensities of selected spectral transitions of neutral nitrogen and oxygen have been measured. Applying the Boltzmann plot method and using a reliable set of O I transition probabilities of spectral lines, originating from levels considerably spread in excitation energies, the temperatures of arc plasmas have been determined. Line intensities of two N I infrared transitions, originating from doubly excited terms 3p′ ²F^o and 3p′ ²G have been measured. In order to obtain the corresponding transition probabilities (A_ki) for these lines, intensities of other N I infrared lines, with well known transition probabilities (taken from recently published data by Wiese and Fuhr [W.L. Wiese and J.R. Fuhr, Improved critical compilations of selected atomic transition probabilities for neutral and singly ionized carbon and nitrogen, J. Phys. Chem. Ref. Data 36 (2007) 1287–1345] from National Institute of Standards and Technology — NIST) have been measured. For evaluation of the transition probabilities the temperatures obtained from the above mentioned O I Boltzmann plots have been used. The results agree satisfactorily with older data found in literature. The new A_ki values for transitions involving the doubly excited levels, together with A_ki values taken from the above mentioned NIST source (used for determination of the new A_ki values), are proposed as a convenient set for determining temperatures of plasmas containing nitrogen atoms.     

NO_x分子在[Ag]-MAPO-5(M=Si,Ti)分子筛中的吸附

采用密度泛函理论(DFT)研究了银离子交换的硅磷酸铝([Ag]-SAPO-5)和钛磷酸铝([Ag]-TAPO-5)分子筛结构及其对NOx分子的吸附,获得吸附复合物的平衡几何结构参数和吸附能.结果表明,NOx分子以η1-N模式吸附在[Ag]-SAPO-5和[Ag]-TAPO-5分子筛中的结构更稳定,其吸附作用强度的次序为NO2NON2O.[Ag]-SAPO-5和[Ag]-TAPO-5对NO和NO2分子的活化程度要比N2O大.相比[Ag]-AlMOR,[Ag]-SAPO-5和[Ag]-TAPO-5对NOx分子的活化程度较大.还对[Ag]-SAPO-5和[Ag]-TAPO-5分子筛的抗硫、抗水及抗氧化性能进行了研究和分析.另外,通过自然键轨道(NBO)计算,分析了NOx分子与平衡离子Ag+之间的作用机理.     

Synthesis and Characterization of Energetic Salts of the (C4N122–) Dianion

3, 6‐Bis(tetrazol‐5‐yl)‐1, 2, 4, 5‐tetrazine is a nitrogen‐rich energetic compound readily prepared and a strong dibasic acid. By the reaction with energetic bases such including hydroxylamine, triaminoguanidine, hydrazine, and diaminourea, multiple ionic energetic materials were prepared and characterized for the first time. Both chemical (multinuclear NMR, Infrared, Raman, MS, etc) as well as explosive (Impact, Friction, Static sensitivities) properties are reported. The materials prepared, with the exception of the silver salt, which is a primary explosive, fall into the classification of low‐sensitivity energetic materials due to desensitizing hydration waters. Calculated explosive performances using the EXPLO5 computer code are also reported.     

The [15N]Methacetin Liver Function Test Characterizes Multicomponent Exposure of Children in Industrially Polluted Regions

Abstract

The [¹⁵N]methacetin urine test for assessing disturbances of the cytochrome P₄₅₀-aided oxygenation of xenobiotics in the human liver has been approved in several environmental health studies. A recent longitudinal study of kindergarten children near chemical and mining companies undergoing fundamental restructuring showed high, seasonally fluctuating SO₂ burden which was well correlated with alterations in the mean liver states of the children. At one point the correlation disappeared, together with indications of large amounts of chlorinated compounds overflowing locally at nighttime. This was finally proven by analyzing urine samples from the children for trichloroacetic acid (TCA). Chlorinated ethanes and ethenes—the precursors of TCA—seemed to dominate the air pollution and to affect the hepatic detoxification capacity. We concluded that the methacetin liver function test reflects multicomponent exposure, including acute monopolization by a dominant pollutant for a time.     

Role of hydrogen peroxide in the synthesis of nitrogen heterocycle containing cobalt complexes

The reactions of Co(O₂CCH₃)₂·4H₂O with the sodium salt of p-toluene sulfonic acid (NapTS) and pyridine (py) or 4-methylpyridine (4mepy) in the presence of hydrogen peroxide in methanol led to the formation of [Co(py)₃(H₂O)₃](pTS)₂ or [Co(4mepy)₂(H₂O)₄](pTS)₂·MeOH, respectively. The coordination polymer [{Co(44′bpy)(H₂O)₄}(pTS)₂]_n (4,4′-bipyridine = 44′bpy) was obtained from the reaction of Co(O₂CCH₃)₂·4H₂O with 44′bpy in the presence of NapTS. The reaction of Co(O₂CCH₃)₂·4H₂O, 2,2′-bipyridine (22′bpy) and NapTS with hydrogen peroxide resulted in the formation of the dinuclear complex [Co₂(μ-OH)₂(μ-O₂CCH₃)(O₂CCH₃)₂(22′bpy)₂](pTS). Characterization of these complexes and the role of hydrogen peroxide in these reactions are discussed. Similar reactions with sodium sulfamate gave the mononuclear [Co(22′bpy)₂(O₂CCH₃)]NH₂SO₃·2H₂O complex and [Co₂(μ-OH)₂(μ-O₂CCH₃)(O₂CCH₃)₂(22′bpy)₂](NH₂SO₃).     

Effect of nitrogen-containing groups on enhanced capacitive behaviors of multi-walled carbon nanotubes

In this work, electrochemical properties of surface treated multi-walled carbon nanotubes (MWNTs) are studied in supercapacitors. Nitrogen and oxygen functional groups containing MWNTs are prepared by urea and acidic treatments, respectively. The surface properties of the MWNTs are confirmed by X-ray photoelectron spectroscopy (XPS) and zeta-potential measurements. The textural properties are characterized by N₂ adsorption/desorption isotherm at 77 K using the BET eqaution, BJH method, and HK method. The electrochemical properties of the MWNTs are accumulated by cyclic voltammetry, impedance spectra, and charge-discharge cycling performance in 1 M H₂SO₄ at room temperature. As a result, the functionalized MWNTs lead to an increase in capacitance as compared with pristine MWNTs. It suggests that the pyridinic and pyridinic-N-oxides nitrogen species have effects on the specific capacitance due to the positive charge, and thus an improved electron transfer at high current loads results, the most important functional groups affecting capacitive behaviors.     

Reaction Mechanisms of a Nitrogenase Model. Water and Hydrogen as Reducible Substrates of the Titanocene System

Abstract

Titanocene nitrogen fixation in tetrahydrofuran was significantly affected by traces of water. Water was reduced to hydrogen by titanocene monochloride. In turn, hydrogen was reduced to hydride by titanocene. Analogy with nitrogenase catalysis is discussed.     

Flow synthesis of annulated 5-aryl-substituted pyridines by tandem intramolecular inverse-electron-demand hetero-/retro-Diels–Alder reaction

5-Aryl-substituted annulated pyridines can be accessed directly from the corresponding acetylene substituted pyrimidines through an intramolecular inverse-electron-demand hetero-/retro-Diels–Alder (ihDA/rDA) reaction cascade carried out in continuous flow. Exploiting this new process, a series of cycloalka[c]pyridines that represent useful building blocks for medicinal chemistry were prepared in good to excellent yields with short processing times (<45 min). Importantly, utilizing the ability to superheat solvents in flow permits the replacement of typically employed high boiling solvents (e.g., nitrobenzene or chlorobenzene) with toluene.     

Scattering of e± from N2 in the energy range 1 eV–10 keV

The differential, integrated elastic, inelastic, total, momentum transfer, viscosity, and ionisation cross sections for electron and positron scattering from the homonuclear diatomic nitrogen molecule over an incident energy range of 1?eV–10?keV are calculated using the additivity rule. Dirac partial wave analysis is employed to calculate the cross sections of the constituent atoms of molecules, using a complex optical model potential (OPM). Comparison of our results of the additivity rule with the available experimental data and other theoretical predictions is presented. Our findings produce reasonable results in intermediate and high energies.     

Synthesis and structural characterization of a flexible metal organic framework {[Ni(dpbz)][Ni(CN)4]}n,dpbz = 1,4-bis(4-pyridyl)benzene) with an unusual Ni–N bond

The chartreuse monoclinic Ni-dpbz (Ni(L)[Ni(CN)₄], (L = 1,4-Bis(4-pyridyl)benzene, or dpbz) crystal assumes a pillared structure with layers defined by 2-D Ni[Ni(CN)₄]_n nets and dpbz ligands as pillars, linking between coordinated Ni sites. In addition to the hysteretic adsorption/desorption feature of Ni-dpbz, in half of the parallelepiped-shape space enclosed by the pillars and nets, an additional dpbz ligand was found to link between the open ends of two four-fold Ni sites. This arrangement results in an unusual 5-fold pseudo square-pyramid environment for Ni and a significantly long Ni–N distance of 2.369(4) Å. The presence of disordered dimethyl sulfoxide (DMSO) solvent molecules give rise to the formula of Ni(dpbz)[Ni(CN)₄]·½dpbz·0.44DMSO. Sorption isotherms showed flexible behavior during the adsorption and desorption of CO₂.