Deformation parameter changes in fission mass yields within the systematic statistical scission-point model

The fission fragment mass-yields are evaluated for pre-actinide and actinide isotopes using a systematic statistical scission point model. The total potential energy of the fissioning systems at the scission point is presented in approximate relations as functions of mass numbers,deformation parameters and the temperature of complementary fission fragments. The collective temperature, Tcoll, and the temperature of fission fragments, Ti, are separated and the effect of collective temperature on mass yields results is investigated. The fragment temperature has been calculated with the generalized superfluid model. The sum of deformation parameters of complementary fission fragments has been obtained by fitting the calculated results with the experimental data. To investigate the transitions between symmetric and asymmetric modes mass yields for pre-actinide and heavy actinides are calculated with this model. The transition from asymmetric to symmetric fission is well reproduced using this systematic statistical scission point model. The calculated results are in good agreement with the experimental data with Tcoll= 2 Me V at intermediate excitation energy and with T_(coll)= 1MeV for spontaneous fission.Despite the Langevin model, in the scission point model, a constraint on the deformation parameters of fission fragments has little effect on the results of the mass yield.     

Calculation of X-ray and Auger transition rates, lifetimes, X-ray wavelengths, and fluorescence yields of variously ionized silicon atoms

X-ray and Auger transition rates, X-ray wavelengths, and fluorescence yields are calculated for variously ionized silicon atoms with configurations 1s2s^m2pⁿ, m=0-2, n=1-6. The calculation has been performed using the Hartree-Fock atomic model. Intermediate coupling and configuration interaction have been taken into account. The energies and widths are found to be strongly affected by configuration mixing. The results from the present calculation have been compared with those available in the literature. The theoretical K_α hypersatellite and satellite spectra fall into several well-separated regions, corresponding to each of the possible number of spectator electrons in the 2s and 2p shells. The dependence of radiative rates and fluorescence yields on the number of spectator electrons is also investigated.     

Automated flow-based anion-exchange method for high-throughput isolation and real-time monitoring of RuBisCO in plant extracts

In this work, a miniaturized, completely enclosed multisyringe-flow system is proposed for high-throughput purification of RuBisCO from Triticum aestivum extracts. The automated method capitalizes on the uptake of the target protein at 4 °C onto Q-Sepharose Fast Flow strong anion-exchanger packed in a cylindrical microcolumn (105 × 4 mm) followed by a stepwise ionic-strength gradient elution (0-0.8 mol/L NaCl) to eliminate concomitant extract components and retrieve highly purified RuBisCO. The manifold is furnished downstream with a flow-through diode-array UV/vis spectrophotometer for real-time monitoring of the column effluent at the protein-specific wavelength of 280 nm to detect the elution of RuBisCO. Quantitation of RuBisCO and total soluble proteins in the eluate fractions were undertaken using polyacrylamide gel electrophoresis (PAGE) and the spectrophotometric Bradford assay, respectively. A comprehensive investigation of the effect of distinct concentration gradients on the isolation of RuBisCO and experimental conditions (namely, type of resin, column dimensions and mobile-phase flow rate) upon column capacity and analyte breakthrough was effected. The assembled set-up was aimed to critically ascertain the efficiency of preliminary batchwise pre-treatments of crude plant extracts (viz., polyethylenglycol (PEG) precipitation, ammonium sulphate precipitation and sucrose gradient centrifugation) in terms of RuBisCO purification and absolute recovery prior to automated anion-exchange column separation. Under the optimum physical and chemical conditions, the flow-through column system is able to admit crude plant extracts and gives rise to RuBisCO purification yields better than 75%, which might be increased up to 96 ± 9% with a prior PEG fractionation followed by sucrose gradient step.     

Synthesis, characterization and comparative studies on the photophysical and photochemical properties of metal-free and zinc(II) phthalocyanines with phenyloxyacetic acid functionalities

The synthesis and characterization of new peripherally and non-peripherally tetra-substituted metal-free and zinc(II) phthalocyanines with 2-, 3- and 4-phenyloxyacetic acid functionalities are described for the first time in this study. The new compounds have been characterized by elemental analysis, FT-IR, UV-Vis, MALDI-TOF and ¹H-NMR spectra. Photodegradation, singlet oxygen and fluorescence quantum yields, and fluorescence lifetimes of these compounds are studied in dimethylformamide (DMF). The influence of the substituent position on the phthalocyanine framework (non-peripherally or peripherally), central metal ion (metal-free or zinc) and the position of the COOH group (2-, 3- or 4-position on the phenyloxyacetic acid) on the spectroscopic, photophysical and photochemical properties have been investigated. Non-peripherally zinc(II) phthalocyanines (1b and 2b) and peripherally zinc(II) phthalocyanine (4b) gave good singlet oxygen quantum yields (Φ_Δ) (0.37, 0.39 and 0.38, respectively) which indicate the potential of the complexes as photosensitizers in applications of PDT.     

30MeV/u 40Ar引起的反应中核温度参数的提取

利用同位素产额比方法,提取了30MeV/u ⁴⁰Ar轰击⁵⁸Ni,⁶⁴Ni和¹¹⁵In的反应中中等质量碎片(IMFs:3≤Z≤8)的发射体的核温度参数,给出了“表观”温度与一些物理量的依赖关系以及对边馈(side-feeding)效应的影响进行修正后的温度参数. 并就此进行了简单的讨论.     

Bifurcation in the stable manifold of a chemostat with general polynomial yields

A three‐dimensional chemostat with nth‐ and mth‐order polynomial yields, instead of the particular ones such as A+BS, A+BS², A+BS³, A+BS⁴, A+BS² + CS³, and A+BSⁿ, is proposed. The existence of limit cycles in the two‐dimensional stable manifold, the Hopf bifurcation, and the stability of the periodic solution created by the bifurcation is proved. Copyright © 2009 John Wiley & Sons, Ltd.     

Empirical,Semi-Empirical and Experimental Determination of K X-Ray Fluorescence Parameters of Some Elements in the Atomic Range 21 ≤ Z ≤ 30

In this study, the semi-empirical and empirical calculations of K X-ray intensity ratios, K-shell fluorescence yields, and vacancy transfer probabilities have been performed for 3d transition elements. Also, σ_Kα, σ_Kβ production cross-sections, K_β/K_α intensity ratios, ω_K fluorescence yields, and η_KL vacancy transfer probabilities of 3d transition elements have been measured. The samples were excited by 59.5 keV γ-rays from a ²⁴¹Am annular radioactive source. K X-rays emitted by samples were counted by an Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV.     

Highly Productive Oxidative Biocatalysis in Continuous Flow by Enhancing the Aqueous Equilibrium Solubility of Oxygen

We report a simple, mild, and synthetically clean approach to accelerate the rate of enzymatic oxidation reactions by a factor of up to 100 when compared to conventional batch gas/liquid systems. Biocatalytic decomposition of H₂O₂ is used to produce a soluble source of O₂ directly in reaction media, thereby enabling the concentration of aqueous O₂ to be increased beyond equilibrium solubility under safe and practical conditions. To best exploit this method, a novel flow reactor was developed to maximize productivity (g product L^?1 h^?1). This scalable benchtop method provides a distinct advantage over conventional bio‐oxidation in that no pressurized gas or specialist equipment is employed. The method is general across different oxidase enzymes and compatible with a variety of functional groups. These results culminate in record space‐time yields for bio‐oxidation.     

Photochemical preparation of tricyclic hydroxyketones by transanular cyclization of bridged 4-benzoylcyclohexanones

Summary The bridged 4-benzoyl-cyclohexanones3a–f were synthesized by ,-annelation of cyclic ketones. Irradiation of3a–f revealed a strong dependence of the photochemical behaviour on the ring size and the introduction of a nitrogen atom. Ketones which are able to form 1,6-biradicals (3b,c,e) undergo unselective photolytic decomposition, whereas3a,d,f afforded tricyclic hydroxyketones. The diastereoselectivity of ring closure is remarkably improved by introduction of a protected nitrogen atom (3d,f) in comparison to the carbocyclic diketone3a. Moreover, the N protective group of 4-azatricyclo-4.3.1.0^3,8]decan-7-one (7) could be removed affording the free hydroxy amino ketone8 in good yields. An explanation of the diastereoselective cyclization of3a and of the surprisingly low quantum yield of3d was found by conformational analysis of the corresponding triplet biradicals.

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Photochemische Darstellung tricyclischer Ketone durch transanulare Cyclisierung verbrückter 4-Benzoylcyclohexanone

Zusammenfassung Die verbrückten 4-Benzoyl-cyclohexanone3a–f wurden durch ,-Anellierung cyclischer Ketone synthetisiert. Das photochemische Verhalten von3a–f hängt in starkem Maße von der Ringgröße und von der Einführung eines Stickstoffatoms ab. Ketone, die in der Lage sind, 1,6-Biradikale zu bilden (3b,c,e), unterliegen einer unselektiven photolytischen Zersetzung, während3a,d,f tricyclische Hydroxyketone liefern. Die Diastereoselektivität des Ringschlusses wird durch Einführung eines Stickstoffatoms (3d,f) im Vergleich zum carbocyclischen Analogon3a deutlich gesteigert. Weiterhin gelang es, die N-Schutzgruppe im 4-Azatricyclo-[4.3.1.0^3,8]decan-7-on (7) unter Bildung des freien Hydroxyaminoketons8 in guten Ausbeuten zu entfernen. Eine Erklärung für die diastereoselektive Cyclisierung von3a und für die überraschend geringe Quantenausbeute von3d wurde durch Konformationsanalyse der entsprechenden Triplett-Biradikale gefunden.