Study of the reactione + e −→K + K − in the energy range1350 \leqq \sqrt s \leqq 2400 MeV

Thee ⁺ e ^?→K ⁺ K ^? cross section has been measured from about 750 events in the energy interval \(1350 \leqq \sqrt s \leqq 2400 MeV\) with the DM2 detector at DCI. TheK ^± form factor |F _F ^±| cannot be explained by the ρ, ω, ? and ρ′(1600). An additional resonant amplitude at 1650 MeV has to be added as suggested by a previous experiment.     

The construction and evaluation of a high pressure manifold and vessels for a Calvet type microcalorimeter

A Setaram C-80 calorimeter has been modified in order to measure the heat flow of energetic materials at pressures up to 69 MPa. A manifold and sample cells capable of operating at high pressure were designed, constructed and evaluated. This paper will describe, in detail, the high pressure manifold construction, safety assessment and calibration. As well, the results for initial trials with ammonium nitrate (AN), and pentaerythritol tetranitrate (PETN) at various pressures and heating rates will be discussed.     

Reductive monoalkylation of aromatic and aliphatic nitro compounds and the corresponding amines with nitriles

[reaction: see text] A simple, selective, rapid, and efficient procedure for the synthesis of secondary amines from the reductive alkylation of either aliphatic or aromatic nitro compounds and the corresponding amines is reported. Ammonium formate is used as the hydrogen source and Pd/C as the hydrogen transfer catalyst. The reaction is carried out at room temperature. The rate differences for the preferential formation of secondary over tertiary products are due to both steric and electronic factors.     

Radiative decay ofJ/ψ into γ π+ π−

The radiative decayJ/ψ → γ π⁺ π^? has been studied using the 8.6 millionJ/ψ produced in the DM2 experiment at the DCIe ⁺e^? storage rings at Orsay. The π⁺ π^? mass spectrum shows a cleanf ₂ (1270) signal, and the possible presence of two other states at thef ₂ (1720) andf ₄ (2030) masses. For thef ₂ (1270), the branching ratio BR(J/ψ →γf)xBR(f→π⁺ π^?) is measured to be (7.50±0.30±1.12)×10^?4, and the spin analysis prefers theJ=2 assignment, with helicity parametersx=0.83±0.06 andy=0.01±0.06. The existence of higher mass states is discussed.     

Non-planar smoulder propagation governed by diffusion

The steady propagation of a thin smouldering front in a half-spacehas been considered. A suitable coordinate transformation hasallowed the region near the leading edge of the front to beexamined for both a maintained planar surface and with surfacecollapse due to material shrinkage. The change in the oxidizerconcentration for a small increment in the propagation speedfor large time and surface collapse has been determined. Theinfluence of two types of nonlinear diffusion on the shape ofthe smouldering front has been found; other cases can be dealtwith in a similar manner.     

Synthesis of imidazolo analogues of the oxidation-reduction cofactor pyrroloquinoline quinone (PQQ)

Parallel syntheses of 2-hydro-, 2-methyl-, and 2-methoxycarbonylimidazo-7,9-dimethoxycarbonyl analogues of the oxidation-reduction cofactor pyrroloquinoline quinone [4,5-dihydro-4,5-dioxo-1H-pyrrolo[2,3-f]quinoline-2,7,9-tricarboxylic acid] have been developed. The properties of the imidazolo analogues in relation to the corresponding pyrrole analogues will be important in assessing the origins of catalysis and biological activity in the cofactor, which has recently been shown to be a vitamin.     

Electrochemical and Electrocatalytic Properties of Imidazole Analogues of the Redox Cofactor Pyrroloquinoline Quinone

The electrochemical and electrocatalytic properties of two synthetic imidazole analogues of the redox cofactor pyrroloquinoline quinone (PQQ) were evaluated. Cyclic voltammetry measurements as a function of pH indicated that both 4,5‐dihydro‐4,5‐dioxo‐1H‐imidazolo[5,4‐f]quinoline‐7,9‐dicarboxylic acid ( 1 ) and 4,5‐dihydro‐4,5‐dioxo‐2‐methyl‐1H‐imidazolo[5,4‐f]quinoline‐7,9‐dicarboxylic acid ( 2 ) undergo a reversible reduction of the o‐quinone moiety below pH 8 with potentials slightly more positive than those observed for PQQ. Upon incorporation into a polypyrrole membrane on the tip of a glassy carbon electrode, 1 and 2 exhibited electrocatalytic properties sufficient for the indirect amperometric detection of cysteine. The response for cysteine was linear up to 1 mM over a wide pH range. Detection limits (S/N=3) were in the μM range and dependent on the solution pH. Interference from redox active species such as dopamine and uric acid were minimized by the pH‐dependent redox potentials of 1 and 2 and thus the ability to tune the detection potential.     

KMgF3:Ni2+晶体的占位、局部结构、吸收光谱和顺磁g因子的统一解释

利用完全对角化方法和强场耦合方案,采用半自洽场(semi-SCF)自由Ni2+的d轨道模型和Ni2+-6X-(x=F,Cl,Br,I)络合物的μ-κ-α模型研究,建立了含有过渡族金属离子的晶体的局域结构与吸收光谱和顺磁g因子之间的定量关系,对KMgF3:Ni2+晶体的占位、局域结构、吸收光谱和顺磁g因子作出了统一解释,预测了KMgF3:Ni2+晶体的光谱精细结构.所得理论计算结果与实验值符合得很好.     

Photoinduced miniemulsion polymerization

This study describes the radical photopolymerization of acrylate monomers in miniemulsion. Starting from nanosized acrylate droplets (<100 nm) which encapsulate a type I radical photoinitiator (BAPO), UV irradiation led after a few minutes to the formation of polymer nanoparticles of similar size. The present study deals with the kinetics aspects of this reaction and the colloidal properties of the resulting polymer dispersions. Real-time Fourier transform near-infrared spectroscopy in transmission was implemented to follow continuously the fast photopolymerization process. In addition, the spatial resolution of the photoinduced process allowed the online monitoring of the evolution of the miniemulsion size during the UV irradiation through dynamic light scattering.