Statistics of S-matrix poles in few-channel chaotic scattering: Crossover from isolated to overlapping resonances

We derive an explicit expression for the distribution of resonance widths in a chaotic quantum system coupled to continua via M equivalent open channels. It describes a crossover from the χ ² distribution (regime of isolated resonances) to a broad, power-law-like distribution typical for the regime of overlapping resonances. The first moment is found to reproduce exactly the Moldauer-Simonius relation between the mean resonance width and the transmission coefficient. Pis’ma Zh. éksp. Teor. Fiz. 63, No. 12, 970–973 (25 June 1996) Petersburg Nuclear Physics Institute, 188350, Gatchina, St. Petersburg District, Russia Published in English in the original Russian journal. Edited by Steve Torstveit.     

Ab-initio calculation of the heat of formation in the metallic transition metal monoxides

In order to understand the cohesive properties of transition metal monoxides the ground state energies of the transition metal T, the monoxide TO and oxygen atom 0 involved in the reaction $\text{M}\text{+}\text{1}\text{2}\text{(}\text{0}{}_2\text{) ?}\text{M O}\text{+ Δ}\text{H}$ have been calculated for metallic TiO and VO following the density functional method in the augmented spherical wave approximation. The evaluated values of ΔH compare very well with those obtained experimentally.     

电感耦合等离子体原子发射光谱法测定钛酸钡纳米粉体中7种杂质元素

钛酸钡纳米粉体样品用盐酸溶解,在所得样品溶液中用电感耦合等离子体原子发射光谱法测定了以氧化物存在于样品中的7种杂质元素(包括镁、锶、钾、钠、铝、硅及铁),对测定的光谱条件进行了试验并优化达到上述各元素的测定上限为0.1%(质量分数).测得方法的检出限(3S/b)为(单位μg·L-1):2.0(铝),1.0(铁),20.0(钾),0.2(镁),4.0(钠),3.0(硅)及0.5(锶).应用此方法分析了两件实样,所得结果的相对标准偏差(n=6)小于等于2.0%,对其中4种杂质元素(镁、钾、钠和锶)同时用HG/T 3587-1999标准中的方法作分析校核,所得结果与此方法结果一致.     

Palladium(0)-catalyzed synthesis of chiral ene-allenes using alkenyl trifluoroborates

Enantioenriched allenes serve as chiral transfer reagents, making them attractive synthetic targets. Herein, the synthesis of enantioenriched allenes utilizing a Pd(0)-catalyzed cross-coupling reaction of propargylic carbonates and phosphates with alkenyl trifluoroborates is reported. Di-, tri-, and tetrasubstituted allenes were synthesized in moderate to high optical yields. Several racemic allenes possessing various functional groups were also synthesized.     

On a quadratic first integral for the charged particle orbits in the charged Kerr solution

Associated with the charged Kerr solution of the Einstein gravitational field equation there is a Killing tensor of valence two. The Killing tensor, which is related to the angular momentum of the field source, is shown to yield a quadratic first integral of the equation of the motion for charged test particles.The research reported herein has been supported in part by the National Science Foundation, grants GP-8868, GP-20023, and GU-1598; the Air Force Office of Scientific Research, grant 903-67; the National Aeronautics and Space Administration, grant 44-004-001; and the Westinghouse Corporation.     

Characterization of a sealed Americium–Beryllium (AmBe) source by inductively coupled plasma mass spectrometry

Two Americium–Beryllium neutron sources were dismantled, sampled (sub-sampled) and analyzed via inductively coupled plasma mass spectrometry (ICP-MS). Characteristics such as “age” since purification, actinide content, trace metal content and inter and intra source composition were determined. The “age” since purification of the two sources was determined to be 25.0 and 25.4 years, respectively. The systematic uncertainties in the “age” determination were ±4% 2σ. The amount and isotopic composition of U and Pu varied substantially between the sub-samples of Source 2 (n = 8). This may be due to the physical means of sub-sampling or the way the source was manufactured. Source 1 was much more consistent in terms of content and isotopic composition (n = 3 sub-samples). The Be–Am ratio varied greatly between the two sources. Source 1 had an Am–Be ratio of 6.3 ± 52% (1σ). Source 2 had an Am–Be ratio of 9.81 ± 3.5% (1σ). In addition, the trace element content between the samples varied greatly. Significant differences were determined between Sources 1 and 2 for Sc, Sr, Y, Zr, Mo, Ba and W.