New agitated and thermostatized cell for in situ monitoring of fast reactions by synchrotron SAXS

A thermostatized and agitated sample cell for synchrotron small‐angle X‐ray scattering (SAXS) measurements of liquid samples (homogeneous or heterogeneous) has been developed. The cell is composed of a compact main body with inlet and outlet windows for the beams of light. The volume of the cell is approximately 0.8 ml and the distance between the windows is 5 mm to allow accurate SAXS measurements. The cell is thermostatized by means of a jacket that surrounds the sample holder and it is connected to a thermostatic bath. In addition, the cell has a top and a bottom lid that allow easy cleaning and maintenance without demounting the optical windows. The cell has been used to run SAXS measurements of liquid samples and, for the first time, a mini‐emulsion polymerization reaction has been monitored by SAXS.     

Mechanistic models for pool nucleate boiling heat transfer: input and validation

Correlations for nucleate boiling heat transfer should be improved, or in the long term possibly be replaced, by the development of mechanistic simulations that include the non-uniform spacing and variable characteristics of the nucleation sites and non-linear interactions between the sites. This paper discusses the interactions that should be included in simulations and some lessons from a first attempt to validate a particular simulation against experimental spatio-temporal data for wall temperature. Input data for nucleation site positions and characteristics are a particular problem and the prospects for obtaining this data from measurements that are independent of boiling are discussed.     

Elektronischer Apparat zur Messung der Suszeptibilität von para- und diamagnetischen Stoffen

Zusammenfassung Es wird ein auf der integrierten Gleichung der Kraft, mit der ein unhomogenes Feld auf die Probe einwirkt, beruhender Apparat zur Messung der Suszeptibilität schwach magnetischer Stoffe beschrieben. Die Kraftwirkungen werden in elektrische Wirkungen übergeführt, die elektronisch gemessen werden.     

An attempt to resolve the astrophysical puzzles by postulating scale degree of freedom

If we assume that scale is a degree of freedom which a physical object, such as a galaxy possesses besides translational and rotational degrees of freedom, we are able to incorporate such diverse phenomena as the systematic cosmological red-shifts, anomalous red-shifts, controversals of quasars, and the expansion of Earth into a single theory. At the same time we can consider the proposed existence of active dilatation as a physical realization of conformal transformations. Active conformal transformations transform the rest masses of particles. The objection that this implies a continuous rest mass spectrum which is not observed is avoided by assuming that particles can form bound systems such as nuclei, atoms, crystals, galaxies, etc., only if ‘discrete’ scale relations are established among the constituent particles. Different galaxies can be dilated relative to each other. (Note the analogy with ‘discrete’ positions of atoms in a crystal. Different crystals can be translated arbitrarily each to the other.) An observer in a contracting galaxy experiences that the universe is expanding.     

On uniqueness for a semilinear parabolic system coupled in an equation and a boundary condition

We consider the system

     

Synthesis of new functionalized imidazo[2,1‐b]thiazoles and thiazolo[3,2‐a]pyrimidines

5‐Oxo‐5H‐[1,3]thiazolo[3,2‐a]pyrimidine‐6‐carboxylic acid ( 4 ), and 6‐methylimidazo[2,1‐b]thiazole‐5‐carboxylic acid ( 17 ) were reacted with amines 6a‐i by the reaction with oxalyl chloride and N, N‐di methyl‐formamide as a catalyst into primary and secondary amide derivatives 7‐14 and 19‐22. From compound 24 N,N'‐disubstituted ureas 26, 27 and perhydroimidazo[1,5‐c]thiazole 29 derivatives of imidazo[2,1‐b]thiazole were prepared. By nmr analysis of compound 29 , the existence of two stereoisomers resulting from both optical, due to centre of chirality at C7′a, and conformational isomerism, due to restricted C5? N6′ bond rotation were proved.     

Mechanochemistry for Energy Materials: Impact of High-Energy Milling on Chemical,Electric and Thermal Transport Properties of Chalcopyrite CuFeS2 Nanoparticles

Chalcopyrite CuFeS₂, a semiconductor with applications in chemical sector and energy conversion engineering, was synthetized in a planetary mill from elemental precursors. The synthesis is environmentally friendly, waste-free and inexpensive. The synthesized nano-powders were characterized by XRD, SEM, EDX, BET and UV/Vis techniques, tests of chemical reactivity and, namely, thermoelectric performance of sintered ceramics followed. The crystallite size of ∼13 nm and the strain of ∼17 were calculated for CuFeS₂ powders milled for 60, 120, 180 and 240 min, respectively. The evolution of characteristic band gaps, Eg, and the rate constant of leaching, k, of nano-powders are corroborated by the universal evolution of the parameter S_BET/X (S_BET-specific surface area, X-crystallinity) introduced for complex characterization of mechanochemically activated solids in various fields such as chemical engineering and/or energy conversion. The focus on non-doped semiconducting CuFeS₂ enabled to assess the role of impurities, which critically and often negatively influence the thermoelectric properties.