A system of Markov processes with random lifetimes

Summary Let E be a locally compact Hausdorff space with a countable base, and suppose {x_n} is a countable collection of points in E. Particles enter E at the site x _n according to a Poisson process N _n (t). Upon entrance to E, a typical particle moves through the space, independently of all other particles, according to the transition law of a Markov process, until its death, which occurs at some random time D. We prove several limit theorems for various functional of this infinite particle system. In particular, laws of large numbers, and central limit theorems are proved for occupation times of relatively compact Borel sets.Supported in part by Arizona State University Grant-in-Aid     

Isospin-forbidden particle decays in light nuclei: (I). T = 32 levels of 9Be, 9B

Absolute branching ratios have been measured for the isospin-forbidden nucleon decays of the lowest $\text{T =}\text{3}\text{2}$ levels of ⁹Be and ⁹B to the ground state and first excited state of ⁸Be. The $\text{T =}\text{3}\text{2}$ levels were populated by the ⁷Li(³He, n) and ⁷Li(³He, p) reactions. The subsequent decay products were observed in coincidence with the neutrons or protons, detected at 0°. Branching ratios of 0.028 ± 0.021 and 0.50 ± 0.11 were determined for the neutron decays of the 14.39 MeV, $\text{T =}\text{3}\text{2}$ level of ⁹Be to the ground state and 2.9 MeV, 2⁺ first excited state of ⁸Be, respectively. Branching ratios of 0.11 ± 0.04 and 0.33 ± 0.09 were determined for the analogous proton decays of the ⁹B, 14.67 MeV $\text{T =}\text{3}\text{2}$ level. The similarity of the decay properties of these analogue levels is in contrast to the large asymmetries observed for $\text{T =}\text{3}\text{2}$ levels in other A = 4N + 1 light nuclei.     

The acoustic calls of blue whales off California with gender data

The acoustic calls of blue whales off California are described with visual observations of behavior and with acoustic tracking. Acoustic call data with corresponding position tracks are analyzed for five calling blue whales during one 100-min time period. Three of the five animals produced type A-B calls while two produced another call type which we refer to as type D. One of the animals producing the A-B call type was identified as male. Pauses in call production corresponded to visually observed breathing intervals. There was no apparent coordination between the calling whales. The average call source level was calculated to be 186 dB re: 1 muPa at 1 m over the 10-110-Hz band for the type B calls. On two separate days, female blue whales were observed to be silent during respective monitoring periods of 20 min and 1 h.     

Evidence for highly charged ion Coulomb crystallization in multicomponent strongly coupled plasmas

Multicomponent non-neutral ion plasmas in a Penning trap consisting of Be(+) and highly charged Xe ions, having different mass-to-charge ratios than Be(+), are cooled to form strongly coupled plasmas by applying a laser-based collisional cooling scheme. The temperature of the plasma was determined from a Doppler broadened transition in Be(+). For the Xe ions, which are centrifugally separated from the Be, the Coulomb coupling parameter was estimated to be approximately 1000. Molecular dynamics simulations of the ion mixture show ordered structures, indicating crystallization of the Xe.     

Characterization and catalytic behavior of EDTA modified silica nanosprings (NS)-supported cobalt catalyst for Fischer-Tropsch CO-hydrogenation

The effect of ethylene diamine tetraacetic acid(EDTA) modification on the physico-chemical properties and catalytic performance of silica nanosprings(NS) supported cobalt(Co) catalyst was investigated in the conversion of syngas(H~(2+) CO) to hydrocarbons by Fischer-Tropsch synthesis(FTS). The unmodified Co/NS and modified Co/NS-EDTA catalysts were synthesized via an impregnation method. The prepared Co/NS and Co/NS-EDTA catalysts were characterized before the FTS reaction by BET surface area,X-ray diffraction(XRD),transmission electron microscopy(TEM),temperature programmed reduction(TPR),X-ray photoelectron spectroscopy(XPS),differential thermal analysis(DTA) and thermogravimetric analysis(TGA) in order to find correlations between physico-chemical properties of catalysts and catalytic performance. FTS was carried out in a quartz fixedbed microreactor(H_2/CO of 2 ∶1,230 ℃ and atmospheric pressure) and the products trapped and analyzed by GC-TCD and GC-MS to determine CO conversion and reaction selectivity. The experimental results indicated that the modified Co/NS-EDTA catalyst displayed a more-dispersed phase of Co_3O_4 nanoparticles(10.9%) and the Co_3O_4 average crystallite size was about 12.4 nm. The EDTA modified catalyst showed relatively higher CO conversion(70.3%) and selectivity toward C_(6-18)(JP-8,Jet A and diesel) than the Co/NS catalyst(C_(6-14))(JP-4).     

Novel tricyclic diamines 1. Synthesis of 1,4-diazaisotwistane and 1,4-diazahomoisotwistane as constrained 3-aminoquinuclidine isosteres

Synthesis of the novel tricyclic diamines 1,4-diazaisotwistane and 1,4-diazahomoisotwistane are described. These compact tricyclic cores have one tertiary and one secondary amine and may serve as ring-constrained isosteres of 3-aminoquinuclidine. Both tricycles were prepared by a similar strategy involving saturation of an appropriately substituted aromatic azaindole, functionalization and intramolecular alkylation.     

Fast Hydrocarbon Oxidation by a High‐Valent Nickel–Fluoride Complex

In the search for highly reactive oxidants we have identified high‐valent metal–fluorides as a potential potent oxidant. The high‐valent Ni–F complex [Ni^III(F)(L)] ( 2 , L=N,N′‐(2,6‐dimethylphenyl)‐2,6‐pyridinedicarboxamidate) was prepared from [Ni^II(F)(L)]^? ( 1 ) by oxidation with selectfluor. Complexes 1 and 2 were characterized by using ¹H/¹⁹F NMR, UV‐vis, and EPR spectroscopies, mass spectrometry, and X‐ray crystallography. Complex 2 was found to be a highly reactive oxidant in the oxidation of hydrocarbons. Kinetic data and products analysis demonstrate a hydrogen atom transfer mechanism of oxidation. The rate constant determined for the oxidation of 9,10‐dihydroanthracene (k₂=29 m ^?1 s^?1) compared favorably with the most reactive high‐valent metallo‐oxidants. Complex 2 displayed reaction rates 2000–4500‐fold enhanced with respect to [Ni^III(Cl)(L)] and also displayed high kinetic isotope effect values. Oxidative hydrocarbon and phosphine fluorination was achieved. Our results provide an interesting direction in designing catalysts for hydrocarbon oxidation and fluorination