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.     

Water-Soluble Products of Photooxidative Destruction of the Bisretinoid A2E Cause Proteins Modification in the Dark

Aging of the retina is accompanied by a sharp increase in the content of lipofuscin granules and bisretinoid A2E in the cells of the retinal pigment epithelium (RPE) of the human eye. It is known that A2E can have a toxic effect on RPE cells. However, the specific mechanisms of the toxic effect of A2E are poorly understood. We investigated the effect of the products of photooxidative destruction of A2E on the modification of bovine serum albumin (BSA) and hemoglobin from bovine erythrocytes. A2E was irradiated with a blue light-emitting diode (LED) source (450 nm) or full visible light (400–700 nm) of a halogen lamp, and the resulting water-soluble products of photooxidative destruction were investigated for the content of carbonyl compounds by mass spectrometry and reaction with thiobarbituric acid. It has been shown that water-soluble products formed during A2E photooxidation and containing carbonyl compounds cause modification of serum albumin and hemoglobin, measured by an increase in fluorescence intensity at 440–455 nm. The antiglycation agent aminoguanidine inhibited the process of modification of proteins. It is assumed that water-soluble carbonyl products formed as a result of A2E photodestruction led to the formation of modified proteins, activation of the inflammation process, and, as a consequence, to the progression of various senile eye pathologies.     

Glycosylation of Receptor Binding Domain of SARS-CoV-2 S-Protein Influences on Binding to Immobilized DNA Aptamers

Nucleic acid aptamers specific to S-protein and its receptor binding domain (RBD) of SARS-CoV-2 (severe acute respiratory syndrome-related coronavirus 2) virions are of high interest as potential inhibitors of viral infection and recognizing elements in biosensors. Development of specific therapy and biosensors is complicated by an emergence of new viral strains bearing amino acid substitutions and probable differences in glycosylation sites. Here, we studied affinity of a set of aptamers to two Wuhan-type RBD of S-protein expressed in Chinese hamster ovary cell line and Pichia pastoris that differ in glycosylation patterns. The expression system for the RBD protein has significant effects, both on values of dissociation constants and relative efficacy of the aptamer binding. We propose glycosylation of the RBD as the main force for observed differences. Moreover, affinity of a several aptamers was affected by a site of biotinylation. Thus, the robustness of modified aptamers toward new virus variants should be carefully tested.     

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.     

MgWO4–A new crystal scintillator

Magnesium tungstate (MgWO₄) crystals of ~1 cm³ volume were obtained for the first time using a flux growth technique. The crystal was subjected to comprehensive characterisation that included room-temperature measurements of the transmittance, X-ray luminescence spectra, afterglow under X-ray excitation, relative photoelectron output, energy resolution, non-proportionality of scintillation response to γ-quanta, response to α-particles, and pulse shape for γ-quanta and α-particles. The light output and decay kinetics of MgWO₄ were studied over the temperature range 7–305 K. Under X-ray excitation the crystal exhibits an intense luminescence band peaking at a wavelength of 470 nm; the intensity of afterglow after 20 ms is 0.035%. An energy resolution of 9.1% for 662 keV γ-quanta of ¹³⁷Cs was measured with a small (≈0.9 g) sample of the MgWO₄ crystal. The photoelectron output of the MgWO₄ crystal scintillator is 35% that of CdWO₄ and 27% that of NaI(Tl). The detector showed pulse-shape discrimination ability in measurements with α-particles and γ-quanta, which enabled us to assess the radioactive contamination of the scintillator. The results of these studies demonstrate the prospect of this material for a variety of scintillation applications, including rare event searches.     

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.     

Ultrapurification of archaeological lead

Based on purification efficiency calculations for lead distillation, we developed a combined process for the ultrapurification of archaeological lead. We obtained pilot amounts of high-purity archaeological lead and PbO with the following contents of detrimental impurities: U, <2 ppb; Th, <1 ppb; Ni, Cu, Fe, Si, Ti, Mg, Al, Mn, Cr, V, Co, < 0.1 ppm; K, Ca, Zn, Cd, Ag, Sb, < 1 ppm. Lead of such purity can be used in low-background experiments as a protective shield material and in the growth of low-background PbWO₄ and PbMoO₄ scintillator crystals. From an isotope ratio, we were able to identify the origin of the archaeological lead.