Lipase from a Brazilian StrainPenicillium citrinum Cultured in a Simple and Inexpensive Medium st]Heat-Denaturation, Kinetics, and pH Stability

This work is a study of lipase production by a Brazilian strain ofPenicillium citrinum using an inexpensive and simple medium without organic nitrogen sources and of some important industrial properties, including thermostability in relation to ionic strength. The maximal lipase activity (1585 U/L) was obtained whenPenicillium citrinum was cultured on 0.75% ammonium sulfate complemented with minerals salts instead of yeast extract. Although this activity was about 55% lower than that produced in medium with yeast extract (2850 U/L), the specific activity (7.8 U/mg proteins) was higher than that obtained with the yeast extract (4.9 U/mg proteins). The morphology of fungus changed totally, with yeast extract there are smooth, solid, and spherical pellets whereas on ammonium sulfate there are small “hairy” pellets uniformly suspended in the medium. The effect of ferrous (Fe⁺⁺) ions was carried out using medium MA with and without Fe⁺⁺ ions. Lipase production byPenicillium citrinum in medium MA requires Fe⁺⁺ ions, the absence of which caused a decreased of about 50% in the specific activity (3.5 U/mg proteins). The utilization of commercial, locally available oils as carbon sources, such as soybean oil (236 U/L) and corn oil (74 U/L) resulted in lower activity compared to olive oil, showing that lipase production byPenicillium citrinum is specifically induced by olive oil. Potassium concentration in the medium can effects the production of lipase (1 mM (1585 U/L), 10 mM (1290 U/L), and 30 mM (1238 U/L), 50 mM (195 U/L), and 100 mM (2 U/L). The crude culture filtered was susceptable to thermal deactivation. It was stable at pH 6.0, but was not stable at the optimum pH (8.0-8.5) at 50 mM. At the low ionic concentration (1-25 mM) this lipase was stable at low pH (3.5-4.0). The activation energy was 22.4 ±2.2 Kcal. mol 1.     

The ratio of K-capture to positon emission in the decay of 120Sb: Experiment and theory disagree

Recent review papers have indicated that experimental K.-capture to positon emission ratios in allowed decays disagree with theory especially for high-Z nuclei. The experimental error has never been sufficiently small to verify this with certainty. The K-capture to positon emission ratio, , in ¹²⁰Sb has been measured with an uncertainty of about 3% and found to lie about 16% lower than the most recent theoretical predictions.     

锌掺杂半导体材料的共振电离质谱分析

本文简要地描述了激光共振电离质谱的实验装置和测量方法,给出了用共振电离质谱方法对锌掺杂化合物半导体材料进行分析的光谱和质谱图,并估计了用这种方法进行痕量分析可能达到的检测限.     

Trace Element Analysis in Compound Semiconductor Material by Resonant Laser Ablation/Ionization Mass Spectrometry

The trace element Zn in the Zn-doped multi-layer ш - V group compound semiconductor was detected by means of Resonant Laser Ablation/lomzation(RLA). A detection limit of 2. 5 X 10¹⁷ atoms/cm³ (about 5 ppm) has been estimated. The mass spectra and the optical resonant ionization spectrum around 214 nm are given in this paper.     

Nuclear physics merely using a light source

The interaction of ultra-intense focused laser beams with solid targets is a new field of research resulting in the production of exotic plasma conditions similar to the conditions which exist in the interior of some stellar objects. The lasers generate very high energy electrons and ions which can subsequently produce gamma-rays, positrons, neutrons and pions. The results obtained from these studies have major implications to fundamental plasma physics and high energy accelerator physics as well as important technological potential for the production of compact sources of neutrons, positrons and isotopes.     

Interference of chlorofluorocarbon (CFC)‐containing inhalers with measurements of volatile compounds using selected ion flow tube mass spectrometry

Selected ion flow tube mass spectrometry (SIFT-MS) is a sensitive technique capable of measuring volatile compounds (VCs) in complex gas mixtures in real time; it is now being applied to breath analysis. We investigated the effect of inhalers containing chlorofluorocarbons (CFCs) on the detection and measurement of haloamines in human breath. SIFT-MS mass scans (MS) and selected ion monitoring (SIM) scans were performed on three healthy non-smoking volunteers before and after inhalation of the following medications: Combivent™ metered-dose inhaler (MDI) (CFC-containing); Ventolin™ MDI (CFC-free); Atrovent™ MDI (CFC-free), Beclazone™ MDI (CFC-containing); Duolin™ nebuliser. In addition, the duration of the persistence of the mass/charge ratios was measured for 20 h. Inhalers containing CFCs generated large peaks at m/z 85, 87, 101, 103 and 105 in vitro and in vivo, consistent with the predicted product ions of CFCs 12, 114 and 11. No such peaks were seen with Duolin™ via nebuliser, or CFC-free MDIs. We conclude that measurement of VCs, such as haloamines, with product ions of similar m/z values to the ions found for CFCs would be significantly affected by the presence of CFCs in inhalers. This issue needs to be accounted for prior to the measurement of VCs in breath in people using inhalers containing CFCs. Copyright © 2009 John Wiley & Sons, Ltd.     

A vision for laser induced particle acceleration and applications

High intensity lasers interacting with solid and gas targets can produce energetic beams of electrons, protons, heavy ions, photons and neutrons. There is the potential for producing “table top” sources of radiation for many different applications.     

Ascorbic acid determination in biological fluids using ascorbate oxidase immobilized on alkylamine glass beads in a flow injection potentiometric system

A flow injection method was developed aimed at the determination of ascorbic acid in biological fluids, particularly fruit juices. The enzyme ascorbic oxidoreductase (EC 1.10.3.3), extracted fromCucurbita maxima, was immobilized onto alkylamine glass beads using glutaral-dehyde as a bifunctional agent. The ascorbic acid concentration was related to oxygen saturation. Fall in oxygen concentration, as a result of ascorbic acid oxidation, was detected by a low cost, homemade oxygen electrode. The calibration graph was linear over the range 0.05 to 3.00 mM (RSD 1%), the maximum number of samples that could be analysed was 90/h. The immobilized enzyme retained its initial activity for 2 mo with more than 600 assays.     

Photon echo without a free induction decay in a double-Λ system

We have characterized a novel photon-echo pulse sequence for a double-Λ-type energy level system where the input and rephasing transitions are different from the applied π pulses. We show that, despite having imperfect π-pulses associated with large coherent emission due to free induction decay (FID), the noise added in the echo mode is only 0.2 ± 0.1 photons per shot, compared to 4 × 10? photons in the FID modes. Using this echo pulse sequence in the "rephased amplified spontaneous emission" (RASE) scheme [Phys. Rev. A 81, 012301 (2010)] will allow for generation of entangled photon pairs that are in different frequency, temporal, and potentially spatial modes to any bright driving fields. The coherence and efficiency properties of this sequence were characterized in a Pr(3+):Y?SiO? crystal.