Dibromo(pyridoxal semicarbazone‐κ3N1,O3,O3′)copper(II)

The title compound, di­bromo(3‐hydroxy‐5‐hydroxy­methyl‐2‐methyl‐4‐pyridine­carbox­aldehyde semicarbazone‐κ³N¹,O³,O^3′)copper(II), [CuBr₂(C₉H₁₂N₄O₃)], consists of discrete complex units with the tridentate pyridoxal semicarbazone ligand as a zwitterion in an almost planar configuration. The Cu^II ions are in a distorted square‐pyramidal coordination, with the equatorial Br atom at a distance of 2.4017 (6) Å and the apical Br atom at a distance of 2.6860 (6) Å.     

Statistical evaluation of methods for quantifying gene expression by autoradiography in histological sections

Background  

In situ hybridisation (ISH) combined with autoradiography is a standard method of measuring the amount of gene expression in histological sections, but the methods used to quantify gene expression in the resulting digital images vary greatly between studies and can potentially give conflicting results.     

Simplex space-time meshes in compressible flow simulations

Employing simplex space-time meshes enlarges the scope of compressible flow simulations. The simultaneous discretization of space and time with simplex elements extends the flexibility of unstructured meshes from space to time. In this work, we adapt a finite element formulation for compressible flows to simplex space-time meshes. The method obtained allows, for example, flow simulation on spatial domains that change topology with time. We demonstrate this with the two-dimensional simulation of compressible flow in a valve that fully closes and opens again. Furthermore, simplex space-time meshes facilitate local temporal refinement. A three-dimensional transient simulation of blow-by past piston rings is run in parallel on 120 cores. The timings point out savings of computation time gained from local temporal refinement in four-dimensional space-time meshes.     

Convergence of Non-stationary Parallel Multisplitting Methods for Hermitian Positive Definite Matrices

Non-stationary multisplitting algorithms for the solution of linear systems are studied. Convergence of these algorithms is analyzed when the coefficient matrix of the linear system is hermitian positive definite. Asynchronous versions of these algorithms are considered and their convergence investigated.

     

Comprehensive Evaluation of Antioxidant Activity of Ribes berry Fruit Species: A Chemometric Approach

Currant fruit extracts were characterized by (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity, 2,2-azinobis-3 ethyl benzothiazoline-6-sulfonic acid cation decolorization activity, total reducing power, cupric ion reducing antioxidant power, and ferric ion reducing antioxidant power (FRAP) assays to evaluate their antioxidant activity. All five antioxidant assays revealed the highest antioxidant activity to be present for the black currants. The highest concentrations of phenolics were present in the black currants (1690?±?10?mg gallic acid equivalents (GAE)/100?g fresh weight), while the lowest value was obtained in the white currants (579?±?5?mg GAE/100?g fresh weight). The correlation between the total phenolic content and antioxidant activity assays was evaluated using regression analysis. A significant positive correlation was obtained between the total phenols and the cupric ion reducing antioxidant power (r?=?0.97, p?r?=?0.93, p?相似文献   

Hypepontine,a new quaternary alkaloid with antimicrobial properties

Abstract

New isoquinoline alkaloid hypepontine (1) together with a five known compounds, were identified in Hypecoum ponticum Velen, the partial synonym of Hypecoum procumbens L. The structure of the new substance was elucidated based on spectroscopic evidence. The tertiary and quaternary alkaloid mixtures as well as the isolated alkaloids were evaluated for their antibacterial and antifungal activity. The result revealed that the crude alkaloid mixture containing quaternary isoquinoline alkaloids showed potent antifungal and antibacterial activity.     

AlFe-pillared clay catalyst for phenol oxidation in water solution

Catalytic wet peroxide oxidation of phenol over AlFe-pillared montmorillonites, with different iron contents, was carried out at room temperature, in a glass batch reactor, under constant airflow and halogen lamp light. At lower concentration (0.5 mg phenol/100 cm³ water) a phenol conversion of 100% was achieved independently of the iron content in pillared clay catalyst. However, at higher phenol concentration (5.0 mg phenol/100 cm³ water) retardation of the catalyst activity was observed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Efficient plasma and bubble generation underwater by an optimized laser excitation and its application for liquid analyses by laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy (LIBS) measurements were performed on bulk water solutions by applying a double-pulse excitation from a Q-Switched (QS) Nd:YAG laser emitting at 1064 nm. In order to optimize the LIBS signal, laser pulse energies were varied through changing of the QS trigger delays with respect to the flash-lamp trigger. We had noted that reduction of the first pulse energy from 92 mJ to 72 mJ drastically improves the signal, although the second pulse energy was also lowered from 214 mJ to 144 mJ. With lower pulse energies, limit of detection (LOD) for Mg in pure water was reduced for one order of magnitude (34 ppb instead of 210 ppb). In order to explain such a phenomenon, we studied the dynamics of the gas bubble generated after the first laser pulse through measurements of the HeNe laser light scattered on the bubble. The influence of laser energy on underwater bubble and plasma formation and corresponding plasma emission intensity were also studied by photographic technique. From the results obtained, we conclude that the optimal first pulse energy should be kept close to the plasma elongation threshold, in our case about 65 mJ, where the gas bubble has its maximum lateral expansion and the secondary plasma is still well-localized. The importance of a multi-pulse sequence on the LIBS signal was also analyzed, where the pulse sequence after the first QS aperture was produced by operating the laser close to the lasing threshold, with the consequent generation of relaxation oscillations. Low-energy multi-pulses might keep the bubble expansion large prior to the probing pulse, but preventing the formation of secondary weak plasmas in multiple sites, which reduces the LIBS signal. The short interval between the pre-pulses and the probing pulse is another reason for the observed LIBS signal enhancement.     

A review on speciation of iodine-129 in the environmental and biological samples

As a long-lived beta-emitting radioisotope of iodine, ¹²⁹I is produced both naturally and as a result of human nuclear activities. At present time, the main part of ¹²⁹I in the environment originates from the human nuclear activity, especially the releases from the spent nuclear fuel reprocessing plants, the ¹²⁹I/¹²⁷I ratios have being reached to values of 10⁻¹⁰ to 10⁻⁴ in the environment from 10⁻¹² in the pre-nuclear era. In this article, we review the occurrence, sources, inventory, and concentration level of ¹²⁹I in environment and the method for speciation analysis of ¹²⁹I in the environment. Measurement techniques for the determination of ¹²⁹I are presented and compared. An overview of applications of ¹²⁹I speciation in various scientific disciplines such as radiation protection, waste depository, and environmental sciences is given. In addition, the bioavailability and radiation toxicity (dose to thyroid) of ¹²⁹I are discussed.