Stereochemistry,tautomerism, and reactions of acridinyl thiosemicarbazides in the synthesis of 1,3‐thiazolidines

Acridin‐9‐yl hydrazine upon treatment with various isothiocyanates (RNCS, R = methyl, allyl, phenyl, p‐methoxy phenyl, and p‐nitro phenyl) yielded the corresponding thiosemicarbazides with acridine substituted on the carbazide‐type side. The alkyl‐substituted compounds were present in solution as equilibria consisting of the major H‐10, H‐12 tautomer (either E or Z or both about the C₁₃‐N₁₄ bond) and the minor H‐10, SH tautomer (either E or Z or both). The major species for the aromatic‐substituted compounds was the H‐10, H‐12 E tautomer, with the evident minor species being the H‐10, H‐12 Z tautomer. The thiosemicarbazides were each quantitatively converted into the analogous semicarbazides upon treatment with mesitylnitrile oxide wherein all structures were present in solution as the H‐10 tautomers with Z conformation about the C₁₃‐N₁₄ bond. Methylation of the compounds with methyl iodide yielded S‐methylated compounds wherein the Z configuration dominated in each case over the E configuration along the N₁₂‐C₁₃ double bond. Treatment of the thiosemicarbazides with methyl bromoacetate resulted in the formation of 1′,3′‐thiazolidin‐4′‐ones wherein the Z configuration predominated in each case over the E configuration along the N₁₂? C₁₃ double bond. With bromoacetonitrile as the bifunctional electrophile, the initial 1′,3′‐thiazolidin‐4′‐imines that formed spontaneously underwent Dimroth‐type rearrangement to the regiosiomeric 1′,3′‐thiazolidin‐4′‐imines.     

Hyperfinite Dimensional Representations of Spaces and Algebras of Measures

Let X be a locally compact topological space and (X, E, X_ω) be any triple consisting of a hyperfinite set X in a sufficiently saturated nonstandard universe, a monadic equivalence relation E on X, and an E-closed galactic set X_ω ⊆ X, such that all internal subsets of X_ω are relatively compact in the induced topology and X is homeomorphic to the quotient X_ω/E. We will show that each regular complex Borel measure on X can be obtained by pushing down the Loeb measure induced by some internal function . The construction gives rise to an isometric isomorphism of the Banach space M(X) of all regular complex Borel measures on X, normed by total variation, and the quotient , for certain external subspaces of the hyperfinite dimensional Banach space , with the norm ‖f‖₁ = ∑_{x ∈ X} |f(x)|. If additionally X = G is a hyperfinite group, X_ω = G_ω is a galactic subgroup of G, E is the equivalence corresponding to a normal monadic subgroup G₀ of G_ω, and G is isomorphic to the locally compact group G_ω/G₀, then the above Banach space isomorphism preserves the convolution, as well, i.e., M(G) and are isometrically isomorphic as Banach algebras. Research of both authors supported by a grant by VEGA – Scientific Grant Agency of Slovak Republic.     

Optimal Liouville-type Theorems for Noncooperative Elliptic Schrödinger Systems and Applications

We study multi-component elliptic Schrödinger systems arising in nonlinear optics and Bose-Einstein condensation phenomena. We prove new Liouville-type nonexistence theorems, as well as a priori bounds, decay and singularity estimates. This is shown under an optimal Sobolev growth restriction on the nonlinearities, thus improving on recent results of Dancer et al. and of Tavares et al. These systems are of non-cooperative form and hence cannot be tackled by maximum principle methods such as moving planes. Instead we rely on a delicate combination of Rellich-Pohozaev type identities, Sobolev and interpolation inequalities on S ^n-1 and feedback and measure arguments. We also extend our results to a rather general class of gradient-type systems.     

Calculation of rotational barriers in amorphous polymers

The Monte Carlo method was used for generation of amorphous polyethylene configurations on a diamond lattice. Chain building was performed on the tetrahedral lattice of edges 36, 62 and 43 Å with periodic boundary conditions imposed.32 chains were generated, each with a length of 100 CH₂-groups (resulting density = 0.81 g·cm⁻³). Small spherical volumes with a radius of 10 Å were chosen at random from the total volume for the calculation of rotational barriers. The rotating bond was chosen to be close to the center of this sphere. We employed the method of molecular mechanics in order to calculate the rotational barriers. The calculation was made for 578 rotating bonds and the obtained distribution of rotational barriers is approximated by the corresponding Γ-distribution.     

The Last Fortress of Tin's Tyranny – Protodenitration of Nitroalkanes

Protodenitration, a direct reduction of nitroalkanes to corresponding alkanes, already spans two centuries and is enabled by various reagents. This mini-review provides a historical development of the fundamental transformation and highlights the governing position of the Ono-Tanner reaction employing tributyltin hydride. Due to the unchallenged dominance of the toxic tributyltin hydride and environmentally unpopular solvents sharply contrasting with modern ecological trends, the current situation was dubbed “the last fortress of tin's tyranny.”     

Blends of polyvinylalcohol with collagen hydrolysate: properties of water‐soluble blown films

The study is focused on the effect of collagen hydrolysate and glycerol on properties of water‐soluble polyvinylalcohol (PVA) blown films and blends. The experimental design method (DOE) was used in this study. Results from DOE show a strong effect of interactions between the blend components on resulting properties of the films. This fact was confirmed by means of the response surfaces of melting flow index, tensile strength and the content of insoluble fraction. It was concluded that the composition of PVA/CH blend must be precisely specified to avoid the processing complications.     

Microinhomogeneities of Charge Carrier Concentration in GaAs

The tendency towards higher and higher integration of electronic components leads to increased requirements to the quality of the base material. The main requirement is homoneity of sturctural and related electronic and optoelectronic crystal properties of the base material within microscopic (and still decreasing) areas, in correspondence with the specific application. This paper is to present investigations of the correlation between local fluctuations of the charge carrier concentration and the occurrence of growth-related striations in terms of IR absorption.     

Contribution to the Si doping of bridgeman GaAs

GaAs: Si with different doping level was grown by the gradient freeze method. The crystals were characterized by structural, electrical and optical methods concerning especially the dependence of the epd and the compensation degree on the carrier concentration.