Isomer-specific product detection of CN radical reactions with ethene and propene by tunable VUV photoionization mass spectrometry

Product detection studies of CN reactions with ethene and propene are conducted at room temperature (4 Torr, 533.3 Pa) using multiplexed time-resolved mass spectrometry with tunable synchrotron photoionization. Photoionization efficiency curves, i.e., the ion signal as a function of photon energy, are used to determine the products and distinguish isomers. Both reactions proceed predominantly via CN addition to the π orbital of the olefin. For CN + ethene, cyanoethene (C₂H₃CN) is detected as the sole product in agreement with recent studies on this reaction. Multiple products are identified for the CN + propene reaction with 75(±15)% of the detected products in the form of cyanoethene from a CH₃ elimination channel and 25(±15)% forming different isomers of C₄H₅N via H elimination. The C₄H₅N comprises 57(±15)% 1-cyanopropene, 43(±15)% 2-cyanopropene and <15% 3-cyanopropene. No evidence of direct H abstraction or indirect HCN formation is detected for either reaction. The results have relevance to the molecular weight growth chemistry on Saturn's largest moon Titan, where the formation of small unsaturated nitriles are proposed to be key steps in the early chemical stages of haze formation.     

Separation of tryptic peptides of native and glycated BSA using open‐tubular CEC with salophene–lanthanide–Zn2+ complex as stationary phase

Open‐tubular CEC (OT‐CEC) with a new stationary phase, salophene–lanthanide–Zn²⁺ complex, has been applied to the separation of tryptic peptides of native BSA and BSA glycated by glucose and ribose. Glycation of proteins (non‐enzymatic modification by sugars) significantly affects their properties and it is of great importance from a physiological point of view. Separation of tryptic peptides of glycated BSA by CZE was poor because of their strong adsorption to the bare fused silica capillary. An improved separation of tryptic peptides of both native and glycated BSA was achieved by OT‐CEC in the fused silica capillary non‐covalently coated with salophene–lanthanide–Zn²⁺ complex, which suppressed the adsorption of peptides to the capillary and via specific interactions with some (glyco)peptides enhanced selectivity of the separation. Significant differences have been found in OT‐CEC analyses of tryptic hydrolysates of native and glycated BSA. In OT‐CEC‐UV profile of tryptic peptides of native BSA, 44 peaks could be resolved, whereas a reduced number of 38 peaks were observed in the profile of tryptic peptides of glucose‐glycated BSA and only 30 peaks were found in the case of ribose‐glycated BSA. The developed OT‐CEC can be potentially used for monitoring of protein glycation.     

Synthesis and Crystal Structures of Two Polymorphs of Trilanthanum Iridium Septaoxide (La<Subscript>3</Subscript>IrO<Subscript>7</Subscript>)

Abstract  

Two polymorphs of trilanthanum iridium septaoxide, La₃IrO₇, were prepared as single crystals using a molten cesium hydroxide flux and were structurally characterized using single-crystal X-ray diffraction. Polymorph A crystallizes in the orthorhombic space group Cmcm with unit cell dimensions of a = 11.2103(3) ?, b = 7.4982(2) ?, and c = 7.6110(2) ?. Polymorph B crystallizes into the monoclinic space group P2₁/n with the unit cell dimensions of a = 8.8512(5) ?, b = 5.7167(3) ?, c = 24.4454(13) ?, and β = 95.542(2)°. The crystal structure of polymorph A is isostructural to the family of compounds with formula Ln₃MO₇ (M = Nb⁵⁺, Mo⁵⁺, Ru⁵⁺, Ta⁵⁺, Re⁵⁺, Os⁵⁺, and Ir⁵⁺) while the crystal structure of polymorph B has no known corollaries.     

On the moments and distribution of discrete Choquet integrals from continuous distributions

We study the moments and the distribution of the discrete Choquet integral when regarded as a real function of a random sample drawn from a continuous distribution. Since the discrete Choquet integral includes weighted arithmetic means, ordered weighted averaging functions, and lattice polynomial functions as particular cases, our results encompass the corresponding results for these aggregation functions. After detailing the results obtained in [J.-L. Marichal, I. Kojadinovic, Distribution functions of linear combinations of lattice polynomials from the uniform distribution, Statistics & Probability Letters 78 (2008) 985–991] in the uniform case, we present results for the standard exponential case, show how approximations of the moments can be obtained for other continuous distributions such as the standard normal, and elaborate on the asymptotic distribution of the Choquet integral. The results presented in this work can be used to improve the interpretation of discrete Choquet integrals when employed as aggregation functions.     

Minimal arithmetic thickness connecting discrete planes

While connected arithmetic discrete lines are entirely characterized, only partial results exist for the more general case of arithmetic discrete hyperplanes. In the present paper, we focus on the three-dimensional case, that is on arithmetic discrete planes. Thanks to arithmetic reductions on a vector , we provide algorithms either to determine whether a given arithmetic discrete plane with as normal vector is connected, or to compute the minimal thickness for which an arithmetic discrete plane with normal vector is connected.     

Seismic collapse capacity spectra for simple structures vulnerable to dynamic instabilities

In this study collapse capacity spectra based on various definitions of the seismic intensity are set in contrast and evaluated. The presented collapse capacities for highly inelastic non-deteriorating single-degree-of-freedom (SDOF) systems, which are vulnerable to the destabilizing effect of gravity loads, are derived for a near-fault set of ground motions with distinct pulse characteristics. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Interplay between degenerate convergence of semigroups and asymptotic analysis: a study of a singularly perturbed abstract telegraph system

Singularly perturbed evolution equations may be analyzed by various techniques. In this paper, we focus on ideas of asymptotic analysis and those akin to the Trotter–Kato approximation theorems. Using as an example an abstract telegraph-type system, we show how these two approaches intertwine and complement each other. The paper also may be seen as a continuation of Kato’s project (in Turbululence and Navier–Stokes Equations Theory. Proc. Conf. Univ. Paris-Sud, Orsay 1975, Lect. Notes Math., Springer, Berlin, vol 565, pp. 104–112, 1976) taking account of recent results. On leave from Lublin University of Technology.     

Density functional study of the O2 binding to [CuI(TPAR)]+ (TPA = tris(2-pyridylmethyl)amine) in THF and EtCN

Density functional theory using the B3LYP hybrid functional has been employed to study the formation of [Cu(II)(TPA(H))(O2-)]+ and [Cu(II)(TPA(MeO))(O2-)]+ (TPA = tris(2-pyridylmethyl)amine) in two different solvents, THF and EtCN. The thermodynamics of solvent coordination as well as that of the overall reactions with O2 has been computed. The formations of [Cu(II)(TPA(H))(O2-)]+ in THF and of [Cu(II)(TPA(MeO))(O2-)]+ in both THF and EtCN are found to be initiated from the [Cu(I)(TPA(R))]+ species, that is, the Cu complex possessing an empty coordination site. In contrast, the formation of [Cu(II)(TPA(H))(O2-)]+ in EtCN is found to be initiated from the [Cu(I)(TPA(H))(EtCN)]+ species, that is, one solvent molecule being coordinated to Cu(I). In general, good agreement is found between theoretical and experimental results. The high accuracy of the B3LYP functional in reproducing experimental thermodynamic data for the present type of transition metal complexes is demonstrated by the fact that the differences between measured and computed thermodynamic parameters (DeltaG degree, DeltaH degrees , and -TDeltaS degree, in most cases are less than 2.0 kcal mol(-1). An attempt was made to investigate the kinetics of the formation of [Cu(II)(TPA(H))(O2-)]+ in THF and EtCN. Computed free energies of activation, DeltaG, are in good agreement with experimental results. However, an analysis of the partitioning of the free energy barriers in enthalpic and entropic contributions indicates that the computationally studied reaction pathway might differ from the one observed experimentally.