Synthesis,structure and photocatalytic properties of nanoparticles from a carbon-containing composite based on silicon oxide modified with titanium dioxide

A pulsed plasmochemical method was used to obtain carbon-containing nanocomposites based on silicon oxide modified with titanium dioxide. The material contained a Si_xC_yO_z carrier with an average size of 50–150?nm and a shell of fine particles with an average size of 5–10?nm. The phase composition and morphology of the synthesized composites was studied by X-ray diffraction and transmission electron microscopy. The optical and photocatalytic properties of the nanoparticles from the carbon-based composite based on silicon oxide encapsulated in titanium dioxide were studied. The synthesized composite showed a high photocatalytic activity due to the decomposition of methylene blue under the influence of visible light in the wavelength range of 460–630?nm.     

Bismuth film electrodes for heavy metals determination

Bismuth film electrodes (BiFEs) have a potential to replace toxic mercury used most frequently for determination of heavy metals (Cd, Pb, Zn) by anodic stripping voltammetry. We prepared a graphite disc electrode (0.5 mm in diameter) from a pencil-lead rod and developed a nitrogen doped diamond-like carbon (NDLC) microelectrode array consisting of 50,625 microdiscs with 3 μm in diameter and interelectrode distances of 20 μm on a highly conductive silicon substrate as a support for BiFEs. The disc graphite BiFE was used for simultaneous determination of Pb(II), Cd(II) and Zn(II) by square wave voltammetry (SWV) in an aqueous solution. We found the optimum bismuth-to-metal concentration ratio in the solution to be 20. The dependence of the stripping responses on the concentration of target metals was linear in the range from 1 × 10⁻⁸ to 1.2 × 10⁻⁷ mol/L. Detection limits 2.4 × 10⁻⁹ mol/L for Pb(II), 2.9 × 10⁻⁹ mol/L for Cd(II) and 1.2 × 10⁻⁸ mol/L for Zn(II) were estimated. A bismuth-plated NDLC microelectrode array was used for Pb(II) determination by differential pulse voltammetry (DPV) in an aqueous solution. We found that the stripping current for bismuth-plated NDLC array was linear in the concentration range of Pb(II) from 2 × 10⁻⁸ to 1.2 × 10⁻⁷ mol/L. The detection limit 2.2 × 10⁻⁸ mol/L was estimated from a calibration plot.     

Beyond change management: A multilevel investigation of contextual and personal influences on employees' commitment to change.

The extent to which attitudes toward organizational changes may be affected by contextual (other changes going on) and personal (self-efficacy) factors was investigated with a multilevel design involving 25 different changes. Even after aspects of the change itself were controlled, the interaction between the context and the individual difference explained significant variance in attitudes toward those specific changes. The positive relationship between self-efficacy and commitment to the change was stronger as the amount of simultaneous and overlapping change in the surroundings increased. The implications for research and practice are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

On Two Techniques of Combining Branching and Treewidth

Branch & Reduce and dynamic programming on graphs of bounded treewidth are among the most common and powerful techniques used in the design of moderately exponential time exact algorithms for NP hard problems. In this paper we discuss the efficiency of simple algorithms based on combinations of these techniques. The idea behind these algorithms is very natural: If a parameter like the treewidth of a graph is small, algorithms based on dynamic programming perform well. On the other side, if the treewidth is large, then there must be vertices of high degree in the graph, which is good for branching algorithms. We give several examples of possible combinations of branching and programming which provide the fastest known algorithms for a number of NP hard problems. All our algorithms require non-trivial balancing of these two techniques. In the first approach the algorithm either performs fast branching, or if there is an obstacle for fast branching, this obstacle is used for the construction of a path decomposition of small width for the original graph. Using this approach we give the fastest known algorithms for Minimum Maximal Matching and for counting all 3-colorings of a graph. In the second approach the branching occurs until the algorithm reaches a subproblem with a small number of edges (and here the right choice of the size of subproblems is crucial) and then dynamic programming is applied on these subproblems of small width. We exemplify this approach by giving the fastest known algorithm to count all minimum weighted dominating sets of a graph. We also discuss how similar techniques can be used to design faster parameterized algorithms. A preliminary version of this paper appeared as Branching and Treewidth Based Exact Algorithms in the Proceedings of the 17th International Symposium on Algorithms and Computation (ISAAC 2006) [15]. Additional support by the Research Council of Norway.     

Stoffwechseluntersuchungen mit Essig-, Milch-und Citronens?ure

Zusammenfassung Per os verabreichte Essig-, Milch- und Citronensäure wird innerhalb von 24 Std zum überwiegenden Teil der Endoxydation zugeführt. Nach 60 min werden von den verabreichten Mengen bei Citronensäure 3%, bei Essigsäure 1,5% und bei Milchsäure 0,9% als CO₂ ausgeschieden. Metabolit- und Radioaktivitätsbestimmungen lassen eine nur geringe Retention der genannten Säuren im Tierkörper feststellen.Von oral zugeführter Citronensäure wird innerhalb von 24 Std rund 20 % unverändert durch die Niere ausgeschieden.Es besteht ein wesentlicher Unterschied in der Verwertung der zwei Stereoisomeren der handelsüblichen Milchsäure.d-Milchsäure wird rasch und in hohen Raten ausgeschieden. 14 Std nach der Verabreichung lassen sich bereits 30 % der oral zugeführtend-Milchsäure im Harn unverändert nachweisen. Sowohl im Blut als auch in der Leber wird trotz Überangebotes durch intraportale Verabreichung ein maximaler Grenzwert von 1,8 bzw. 5,5 mol/g im Blut bzw. mol je g Frischgewicht and-Lactat nicht überschritten.l-Lactat wird unter gleichen Bedingungen nicht oder kaum ausgeschieden. In Blut und Leber finden sich nachl-Lactatgaben relativ hohe Gehalte dieses Substrates.Intraportal verabreichtes Lactat, Acetat oder Citrat wird in das Glykogen der Leber eingebaut. Die gemessenen Einbauraten zeigen jedoch nur einen relativ geringen Anteil dieser Verbindungen an der Glykogen-Neubildung. Die maximalen Einbauraten sind bei Lactat 0,3%, bei Acetat 0,08% und bei Citrat 0,17%. Die Verteilung der Radioaktivität in der Glykogen-Glucose nach Pfortaderinfusion von 2-¹⁴C-Acetat, 1- und 2-¹⁴C-Lactat oder 1,5-¹⁴C-Citrat zeigt, daß Acetat und Citrat über die Reaktionsfolgen des Citronensäurecyclus zur Glykogen-Neubildung in der Leber verwertet werden. Als Hauptweg des Glykogeneinbaues von Lactat wird die reduzierende Carboxylierung mit Malat-Enzym (malic enzyme) des aus Laetat gebildeten Pyruvates erkannt. Daneben wird Pyruvat ebenso über den Citronensäurecyclus und die direkte Phosphorylierung mit Hilfe von Pyruvatkinase zu Phosphoenolpyruvat in die gluconeogenetische Reaktionskette eingeschleust.Aus den vorgelegten Ergebnissen werden Schlußfolgerungen für die therapeutische und diätetische Praxis gezogen. Eine in Krankheitsfällen (z. B. Nierenerkrankungen) empfohlene Umstellung von Essig auf Citronensaft ist nach diesen Stoffwechseluntersuchungen nicht gerechtfertigt.Auszug aus der DissertationsschriftF. Medzihradsky, Technische Hochschule München (1965).Die vorliegende Arbeit wurde mit Unterstützung der AIF (Arbeitsgemeinschaft Industrieller Forschungsvereinigungen) und mit Mitteln des Bundeswirtschaftsministeriums durchgeführt, wofür wir auch an dieser Stelle danken.     

Solvent-Induced Formation of Novel Ni(II) Complexes Derived from Bis-Thiosemicarbazone Ligand: An Insight from Experimental and Theoretical Investigations

In this work, we report solvent-induced complexation properties of a new N₂S₂ tetradentate bis-thiosemicarbazone ligand (H₂L^I), prepared by the condensation of 4-phenylthiosemicarbazide with bis-aldehyde, namely 2,2’-(ethane-1,2-diylbis(oxy)dibenzaldehyde, towards nickel(II). Using ethanol as a reaction medium allowed the isolation of a discrete mononuclear homoleptic complex [NiL^I] (1), for which its crystal structure contains three independent molecules, namely 1-I, 1-II, and 1-III, in the asymmetric unit. The doubly deprotonated ligand L^I in the structure of 1 is coordinated in a cis-manner through the azomethine nitrogen atoms and the thiocarbonyl sulfur atoms. The coordination geometry around metal centers in all the three crystallographically independent molecules of 1 is best described as the seesaw structure. Interestingly, using methanol as a reaction medium in the same synthesis allowed for the isolation of a discrete mononuclear homoleptic complex [Ni(L^II)₂] (2), where L^II is a monodeprotonated ligand 2-(2-(2-(2-(dimethoxymethyl)phenoxy)ethoxy)benzylidene)-N-phenylhydrazine-1-carbothioamide (HL^II). The ligand L^II was formed in situ from the reaction of L^I with methanol upon coordination to the metal center under synthetic conditions. In the structure of 2, two ligands L^II are coordinated in a trans-manner through the azomethine nitrogen atom and the thiocarbonyl sulfur atom, also yielding a seesaw coordination geometry around the metal center. The charge and energy decomposition scheme ETS-NOCV allows for the conclusion that both structures are stabilized by a bunch of London dispersion-driven intermolecular interactions, including predominantly N–H∙∙∙S and N–H∙∙∙O hydrogen bonds in 1 and 2, respectively; they are further augmented by less typical C–H∙∙∙X (where X = S, N, O, π), CH∙∙∙HC, π∙∙∙π stacking and the most striking, attractive long-range intermolecular C–H∙∙∙Ni preagostic interactions. The latter are found to be determined by both stabilizing Coulomb forces and an exchange-correlation contribution as revealed by the IQA energy decomposition scheme. Interestingly, the analogous long-range C–H∙∙∙S interactions are characterized by a repulsive Coulomb contribution and the prevailing attractive exchange-correlation constituent. The electron density of the delocalized bonds (EDDB) method shows that the nickel(II) atom shares only ~0.8|e| due to the σ-conjugation with the adjacent in-plane atoms, demonstrating a very weak σ-metalloaromatic character.     

Graph Searching, Elimination Trees, and a Generalization of Bandwidth

The bandwidth minimization problem has a long history and a number of practical applications. In this paper we introduce a natural extension of bandwidth to partially ordered layouts. We consider this extension from three main viewpoints: graph searching, tree decompositions, and elimination orderings. The three graph parameters pathwidth, profile, and bandwidth related to linear layouts can be defined by variants of graph searching using a standard fugitive. Switching to an inert fugitive, the two former parameters are extended to treewidth and fill-in, and our first viewpoint considers the analogous tree-like extension that arises from the bandwidth variant. Bandwidth also has a definition in terms of ordered path decompositions, and our second viewpoint extends this in a natural way to ordered tree decompositions. In showing that both extensions are equivalent we employ the third viewpoint of elimination trees, as used in the field of sparse matrix computations. We call the resulting parameter the treespan of a graph and prove some of its combinatorial and algorithmic properties.     

Observation of Sea Ice Using the 36-GHz Surface Contour Radar

In January 1984, a 36-GHz scanning pencil-beam radar was used at 175-m altitude over ice in the Greenland Sea to produce high-spatial-resolution (3 m by 5 m) topographic and backscattered power maps. Incidence angles from nadir to approximately 300 offnadir were included in the data set. When the radar maps were compared with the ice topography indicated by simultaneous photography and an analysis of the shadows of the ridges cast by the low sun angle (3.5°), it was found that the backscattered power data sharply delineated many of the features observed in the photography. The elevation data were less impressive but still consistent with the general variation of the topography.