Fe/Co alloys for the catalytic chemical vapor deposition synthesis of single- and double-walled carbon nanotubes (CNTs). 1. The CNT-Fe/Co-MgO system

Mg(0.90)Fe(x)Co(y)O (x + y = 0.1) solid solutions were synthesized by the ureic combustion route. Upon reduction at 1000 degrees C in H2-CH4 of these powders, Fe/Co alloy nanoparticles are formed, which are involved in the formation of carbon nanotubes, which are mostly single and double walled, with an average diameter close to 2.5 nm. Characterizations of the materials are performed using 57Fe M?ssbauer spectroscopy and electron microscopy, and a well-established macroscopic method, based on specific-surface-area measurements, was applied to quantify the carbon quality and the nanotubes quantity. A detailed investigation of the Fe/Co alloys' formation and composition is reported. An increasing fraction of Co2+ ions hinders the dissolution of iron in the MgO lattice and favors the formation of MgFe2O4-like particles in the oxide powders. Upon reduction, these particles form alpha-Fe/Co particles with a size and composition (close to Fe(0.50)Co(0.50)) adequate for the increased production of carbon nanotubes. However, larger particles are also produced resulting in the formation of undesirable carbon species. The highest CNT quantity and carbon quality are eventually obtained upon reduction of the iron-free Mg(0.90)Co(0.10)O solid solution, in the absence of clusters of metal ions in the starting material.     

Improvement on Citric Acid Production in Solid-state Fermentation by <Emphasis Type="Italic">Aspergillus niger</Emphasis> LPB BC Mutant Using Citric Pulp

Citric acid (CA) production has been conducted through a careful strain selection, physical–chemical optimization and mutation. The aim of this work was to optimize the physical–chemical conditions of CA production by solid-state fermentation (SSF) using the Aspergillus niger LPB BC strain, which was isolated in our laboratory. The parental and mutant strain showed a good production of CA using citric pulp (CP) as a substrate. The physical–chemical parameters were optimized and the best production was reached at 65% moisture, 30 °C and pH 5.5. The influence of the addition of commercial and alternative sugars, nitrogen sources, salts, and alcohols was also studied. The best results (445.4 g of CA/kg of CP) were obtained with sugarcane molasses and 4% methanol (v/w). The mutagenesis induction of LPB BC was performed with UV irradiation. Eleven mutant strains were tested in SSF where two mutants showed a higher CA production when compared to the parental strain. A. niger LPB B3 produced 537.6 g of CA/kg of CP on the sixth day of fermentation, while A. niger LPB B6 produced 616.5 g of CA/kg of CP on the fourth day of fermentation, representing a 19.5% and 37% gain, respectively.     

多谱线耦合系统辐射束缚问题的理论处理

提出一种处理多荧光谱线耦合系统辐射束缚问题的理论方法．这里的耦合包括激发态间的碰撞传能和当谱线重叠时对荧光的交叉吸收．首先将描述辐射束缚的Ｈｏｌｓｔｅｉｎ方程扩展为适用于描述多个激发能级且包括交叉耦合项的微分积分方程组，并将其纳入矢量、矩阵的形式．然后直接通过算符运算求解，给出按算符展开的级数解式．最后对级数解进行约化，导出一个只用有限项便可对系统行为进行完整描述的、远较简单截断近似优越的结果．还给出了一个双激发能级系统的计算实例     

Implementation of nonsymmetric interior-point methods for linear optimization over sparse matrix cones

We describe an implementation of nonsymmetric interior-point methods for linear cone programs defined by two types of matrix cones: the cone of positive semidefinite matrices with a given chordal sparsity pattern and its dual cone, the cone of chordal sparse matrices that have a positive semidefinite completion. The implementation takes advantage of fast recursive algorithms for evaluating the function values and derivatives of the logarithmic barrier functions for these cones. We present experimental results of two implementations, one of which is based on an augmented system approach, and a comparison with publicly available interior-point solvers for semidefinite programming.     

微波消解ICP-MS测定唐古特乌头中的多种微量元素

采用HNO3-H2O2混合酸体系微波消解及电感耦合等离子体-质谱法,消解唐古特乌头样品,测定其中Mn、Fe、Co、As、Ni、Se、Cu、Zn、V和Cr共10种微量元素。探讨了样品消解的条件,通过加标回收实验,回收率为94.08%—103.50%,验证了分析数据的可靠性。结果表明,该法具有快速、简便、准确度高、能同时分析多元素的优点,结果令人满意。     

Kleinere Laboratoriumsapparate und -Ger?the

Ohne Zusammenfassung     

Selection and Optimization of Bacillus atrophaeus Inoculum Medium and its Effect on Spore Yield and Thermal Resistance

Bacillus atrophaeus's spores are used as biological indicators to monitor sterilization processes and as a Bacillus anthracis surrogate in the development and validation of biosafety methods. The regular use of biological indicators to evaluate the efficiency of sterilization processes is a legal requirement for health services. However, its high cost hinders its widespread use. Aiming at developing a cost-effective inoculum medium, soybean molasses and nutrient-supplemented vinasse were evaluated for their effectiveness in solid-state fermentation (SSF). In biomass production, the results demonstrated that all tested compositions favor growth by providing the nutritional demands of the microorganism. Optimum casein peptone and soybean molasses concentration (1.0%, 2.5%, or 4.0%) was determined by a 2((2-0)) factorial experimental design. The results have showed a positive influence of peptone on biomass production. In order to define peptone final concentration (4.0% or 6.0%), a 2(2) factorial experimental design was used. An optimized medium containing 4.0% soybean molasses and 4.0% casein peptone was similar in performance to a synthetic control medium (tryptone soy broth) in dry-heat thermal-resistant spore production by SSF. An experiment performed under optimum SSF conditions resulted in 1.9 x 10(10) CFU g(-1) dry matter with D (160 degrees C) = 5.2 +/- 0.2 min.     

Preparation and characterization of loess sediment for use as a reference material in the annual radiation dose determination for luminescence dating

Loess sediment was prepared and characterized with well-established K, Th and U contents, and corresponding ⁴⁰K, ²³²Th and ^235,238U activities, intended for use as a reference material in the annual radiation dose determination for luminescence dating. To this purpose, loess was collected in Volkegem, Belgium, and — after drying, pulverizing and homogenizing — characterized via k ₀-INAA and HPGe gamma-ray spectrometry. This led to 12 kg material with a grain size below 50 μm, with established K, Th and U homogeneity, with the ²³²Th and ²³⁸U decay series proven to be in equilibrium, and with the following K, Th and U reference data: K = 16.5±1.5 g·kg⁻¹ (⁴⁰K = 497±45 Bq·kg⁻¹); Th = 10.4±0.6 mg·kg⁻¹ (²³²Th = 42.2±2.5 Bq·kg⁻¹); U = 2.79±0.12 mg·kg⁻¹ (²³⁸U = 34.5±1.5 Bq·kg⁻¹; ²³⁵U = 1.59±0.09 Bq·kg⁻¹; ^235+238U = 36.1±1.7 Bq·kg⁻¹). These data were confirmed via comparison with the results from NaI(Tl) field gamma-ray spectrometry, thick-source ZnS alpha-counting and thick-source GM beta-counting (after converting all data to Gy·ka⁻¹). The reference material is available (as aliquots up to 200 g) from the Ghent Luminescence Laboratory to all interested luminescence dating laboratories upon motivated request.     

肉苁蓉精油化学成分的研究

肉苁蓉 Cistanche Salsa(C.A.Mey.)G.Beak 是列当科 Orobanchaceae 植物肉苁蓉的肉质茎;又名大芸,纵蓉。它分布在北疆地区荒漠戈壁地带,有益肾壮阳,延年益寿等功能,故有“沙漠人参”之称。肉苁蓉是一种常用的中药,新疆地区资源丰富,其精油化学成分在国内外未见报道。为了整理和发掘祖国医药学宝库,我们对其化学成分进行了研究。     

Investigations into the reliability of SAR-OSL equivalent doses obtained for quartz samples displaying dose response curves with more than one component

Fast component dominated quartz single aliquot regenerative dose optically stimulated luminescence (SAR-OSL) dose response curves that display continuing growth at high doses are increasingly reported in literature. This behaviour would result in higher equivalent doses being obtained. Here we document the characteristics of OSL signals from fine (4–11 μm) and coarse (63–90 μm) quartz extracted from Romanian loess that display such behaviour. For very high doses (>1 kGy up to 5–15 kGy) the data could be closely fitted to a double saturating exponential regression model. Nonetheless, the saturation charcteristics of these fine and coarse quartz grains are very different, with average saturation chracteristic doses of D₀₁ ≈ 175 Gy and D₀₂ ≈ 1800 Gy in the case of the fine material, while in the case of the coarse material values of D₀₁ ≈ 55 Gy and D₀₂ ≈ 600 Gy have been obtained. Our results imply a hitherto unexplained mechanism in OSL production at high doses and question the reliability of obtaining SAR-OSL equivalent doses in the high dose region when a second function is needed to describe the dose response.