99mTc-Labelled Compounds Prepared with Ti(III) as Reducing Agent

In preparation of ^99mTc-labelled compounds it is possible to use TiCl₃ instead, of SnCl₂; in most cases, however, this substitution changes the biodistribution parameters. The preparations have then a slower blood clearence, being cumulated in bones in larger amounts; bone diagnostics (HEDSPA and pyrophosphate) are opposite cases. This fact makes itself felt in ^99mTc-Ti-gluconate which, in its turn, loses the character of kidney agent cumulating, in a marked way, in bones. From diagnostic point of view, the ^99mTc-Ti-labelled compounds possess, in most cases, worse parameters as compared with those prepared by means of tin dichloride. Preparation of technetium-labelled compounds requires inert nitrogen atmosphere. Time stability of these preparations within 24 hours is good a whole.     

Magnetic properties and temperature stability of a molybdenum-doped finemet-type alloy

The influence of nanocrystallization conditions on the structure, magnetic properties, and temperature stability of nanocrystalline magnetically soft Fe_73.5Cu₁Nb_1.5Mo_1.5Si_13.5B₉ alloy is studied. It is found that preliminary low-temperature annealing exerts an influence on subsequent nanocrystallization of the alloy. In addition, preannealing followed by nanocrystallization considerably improves the magnetic properties of the alloy. It is shown that the magnetic properties of the material can be controlled by varying the frequency of a magnetic field used for thermal treatment causing nanocrystallization. It is established that the magnetic properties of nanocrystalline Fe_73.5Cu₁Nb_1.5Mo_1.5Si_13.5B₉ alloy offer a high temperature stability.     

Physical and Bioengineering Properties of Polyvinyl Alcohol Lens-Shaped Particles Versus Spherical Polyelectrolyte Complex Microcapsules as Immobilisation Matrices for a Whole-Cell Baeyer–Villiger Monooxygenase

Direct comparison of key physical and chemical-engineering properties of two representative matrices for multipurpose immobilisations was performed for the first time. Polyvinyl alcohol lens-shaped particles LentiKats® and polyelectrolyte complex microcapsules were characterised by advanced techniques with respect to the size distribution of the particles, their inner morphology as revealed by fluorescent probe staining, mechanical resistance, size-exclusion properties, determination of effective diffusion coefficient and environmental scanning electron microscope imaging. While spherical polyelectrolyte complex microcapsules composed of a rigid semipermeable membrane and a liquid core are almost uniform in shape and size (diameter of 0.82 mm; RSD?=?5.6 %), lens-shaped LentiKats® are characterised by wider size distribution (diameter of 3.65 mm; RSD?=?10.3 % and height of 0.341 mm; RSD?=?32.3 %) and showed the same porous structure throughout their whole volume at the mesoscopic (micrometre) level. Despite differences in their inner structure and surface properties, the pore diameter of?～?2.75 nm for regular polyelectrolyte complex microcapsules and?～?1.89 nm for LentiKats® were similar. These results were used for mathematical modelling, which provided the estimates of the effective diffusion coefficient of sucrose. This value was 1.67?×?10^?10 m² s^?1 for polyelectrolyte complex microcapsules and 0.36?×?10^?10 m² s^?1 for LentiKats®. Recombinant cells Escherichia coli-overexpressing enzyme cyclopentanone monooxygenase were immobilised in polyelectrolyte complex microcapsules and LentiKats® for comparison of their operational stability using model Baeyer–Villiger oxidation of (±)-cis-bicyclo [3.2.0] hept-2-en-6-one to regioisomeric lactones as important chiral synthons for potential pharmaceuticals. Both immobilisation matrices rendered high operational stability for whole-cell biocatalyst with no reduction in the biooxidation rate over 18 repeated reaction cycles.     

Single-Atom Catalysis in Organic Synthesis

Single-atom catalysts hold the potential to significantly impact the chemical sector, pushing the boundaries of catalysis in new, uncharted directions. These materials, featuring isolated metal species ligated on solid supports, can exist in many coordination environments, all of which have shown important functions in specific transformations. Their emergence has also provided exciting opportunities for mimicking metalloenzymes and bridging the gap between homogeneous and heterogeneous catalysis. This Review outlines the impressive progress made in recent years regarding the use of single-atom catalysts in organic synthesis. We also illustrate potential knowledge gaps in the search for more sustainable, earth-abundant single-atom catalysts for synthetic applications.     

Hydration of hydrogentungstate anions at different ph conditions: a car-parrinello molecular dynamics study

Standard density functional theory calculations with a continuous model of solvation as well as Car-Parrinello molecular dynamics simulations with explicit solvent molecules are carried out to analyze the effect of the pH of the solution on the coordination sphere of the W (VI) ion. Both methodologies agree in predicting an expansion of the coordination sphere of the W (VI) ion upon a decrease in the pH. Continuous solvation models, however, are unable to predict as stable some structural isomers of a hydrated hydrogentungstate anion and tungstic acid.     

Electrochemical behavior of phthaloyl peroxide in aqueous media

The electrochemical behavior of phthaloyl peroxide C₈H₄O₄ on an Au disk electrode in a 0.05 M aqueous solution of Na₂SO₄ was studied by cyclic voltammetry (CVA). It demonstrated a high activity in cathodic reduction with the formation of an irreversible peak on the CVA curve at E =–0.81 V. Additionally, during the anodic oxidation of C₈H₄O₄, the surface of the Au electrode became passivated by compounds which prevented its oxidation during the registration of repeated cycles. Apparently, these compounds are surface complexes of phthaloyl peroxide with a gold cation.     

Detection and investigation of delayed extensive air showers with <Emphasis Type="Italic">N</Emphasis><Subscript><Emphasis Type="Italic">e</Emphasis></Subscript> > 5 × 10<Superscript>6</Superscript>

Delayed extensive air showers with N _e > 5 × 10⁶ are detected. The detection of such events indicates the existence of new processes for energies above 10¹⁶ eV.     

Analysis of the method for studying the zenith-angle EAS distribution

The methodical problems related to analysis of the zenith-angle distribution of extensive air showers with N _e > 10⁷ particles are discussed. The effect of the array geometry on the angle measurement error is considered. Possible distortions of angular distribution due to errors have been calculated. The presence of excess showers detected at large zenith angles is shown.