Indirect Measurement of Biologically Important Compounds by Means of X-Ray Microanalysis

 The main objective of our work was to investigate the possibility and usefulness of indirect methods in X-ray microanalysis for the quantification of biologically important compounds. Metallothionein-like proteins (MT-like proteins) from kidney and liver, rich in sulfur were chosen as an indicator of heavy metal presence in cells and their environment. Tissues from goldfish (Carassius auratus gibelio) were sampled after short and prolonged periods of exposure to Co⁺², CrO₄ ⁻², Pb⁺², Cu⁺² and control treatment and prepared for histochemical staining for peroxidated thiolate groups. Commonly used –S–S– bonds dye (Nitro Red) was replaced with iodine atoms and they were quantified at L line by means of X-ray microanalysis combined with SEM. After fish treatments with heavy metal solutions changes in MT-like proteins and in I atom contents were expected. There was statistically significant decrease in MT-like proteins level in kidney after lead treatment (Pb/C = 0.62). In liver a statistically significant increase in MT-like proteins concentration was observed after chromium, cobalt and lead ions treatment in comparison to control animals. The following ratios were noted: 3.04 for Cr/C, 2.18 for Co/C and 2.10 for Pb/C. Our finding indicates that the method of indirect measurement of MT-like proteins in fish and other animal tissues is possible. The concentration of iodine atoms is above their detection level by EDS and their changes are possible to identify. During histochemical procedures it is worth taking into account sample preparation methods which might disturb the quality and quantity of the analysed material.     

Spectroscopic and PM5 semiempirical studies of new hydrazone of gossypol with 3,6-dioxaheptylhydrazine

A new hydrazone of gossypol with 3,6-dioxaheptylhydrazine (GHDO) has been synthesised and its structure has been studied by FT-IR, ¹H NMR, ¹³C NMR as well as PM5 semiempirical methods. All the studies have provided clear evidence of the existence of GHDO in the solution in the N-imine–N-imine tautomeric form. The structure and the spectroscopic behaviour of this tautomer are discussed in details. It is shown the structure of GHDO is strongly stabilised by different types of intramolecular hydrogen bonds. In two of them the oxygen atoms of the oxaalkyl chains are also engaged. The strongest intramolecular hydrogen bond is formed between the O₇H proton and N₁₆ atom from the hydrazone group.     

Flexoelectric deformations of homeotropic nematic layers in the presence of ionic conductivity

Elastic deformations of homeotropic nematic liquid crystal layers subjected to a d.c. electric field were studied numerically in order to find the dependence of threshold voltage on the properties of such a system. A nematic material characterized by a negative sum of flexoelectric coefficients and by a small negative dielectric anisotropy was considered. The flow of ionic current was taken into account. The electric properties are described in terms of a weak electrolyte model. Finite surface anchoring strength was assumed. The director orientation, the electric potential and the ion concentrations were calculated as functions of the coordinate normal to the layer. It was found that the threshold for the deformation depends on the distributions of the ions, governed by the generation constant and by the properties of the electrodes. The effects observed may be interpreted as a consequence of the separation of the ions. When the electrodes have pronounced blocking character, a high and non-uniform electric field, created by the subelectrode ion space charges, causes drastic decrease of the threshold voltage, much below the value U _f valid for the insulating nematic. On the other hand, the electric field gradient arising in the bulk at moderate concentrations has a stabilizing effect and remarkably enhances the threshold above U _f. When the electrodes are conducting there are no significant space charges and the threshold voltage remains close to U _f. These results indicate that phenomena related to the charge transport should be taken into account in the analysis of the elastic deformations of ion-containing flexoelectric nematics.     

On the stationary flows of viscous,incompressible and heat-conducting fluids

We consider a boundary-value problem describing the motion of viscous, incompressible and heat-conducting fluids in a bounded domain in ?³. We admit non-homogeneous boundary conditions, the appearance of exterior forces and heat sources. Our aim is to prove the existence of a solution of the problem in Sobolev spaces.     

HPLC determination of PAHs in mineral oils used as dispersing agents for herbicides

Summary The representative refined mineral oil samples, crude petroleum straightrun distillates, potentially used in the manufacture of crop protection products were analysed by isocratic and gradient high performance liquid chromatography (HPLC) to investigate their trace polycyclic aromatic hydrocarbon (PAH) content. Liquid-liquid extraction followed by size-exclusion column chromatography was employed to isolate the fraction containing PAHs with more than two fused rings. The identity of individual PAHs was confirmed by comparing their UV and fluorimetric detector signals with those recorded from reference standards. The level of extracted PAHs in the oil samples are discussed with respect to their physical and chemical properties.     

ON THE ITERATED ω-RULE

Let Γ_n(φ) be a formula of L_PA (PA = Peano Arithmetic) meaning “there is a proof of φ from PA-axioms, in which ω-rule is iterated no more than n times”. We examine relations over pairs of natural numbers of the kind. (n, k) ≦_H (n', k') iff PA + RFN_n' (H_k') ? RFN_n (H_k). Where H denotes one of the hierarchies ∑ or Π and RFN_n(C) is the scheme of the reflection principle for Γ_n restricted to formulas from the class C(Γ_n(φ) implies “φ is true”, for every φ ∈ C). Our main result is that. (n, k) ≦H (n', k') if n ≦ n' and k ≦ max (k', 2n' + 1).     

A facile synthesis of 1,1-bis(silyl)ethenes

Symmetrical 1,1-bis(silyl)ethenes have been easily prepared via ruthenium complex-catalyzed silylative coupling cyclization of 1,2-bis(dimethylvinylsiloxy)ethane to give 2,2,4,4-tetramethyl-3-methylene-1,5-dioxa-2,4-disilacycloheptane with excellent selectivity and good yield, followed by its reaction with Grignard reagents. The cyclic product can also be effectively transformed into cyclic carbosiloxane, 2,2,4,4,6,6,8,8-octamethyl-3,7-dimethylene-1,5-dioxa-2,4,6,8-tetrasilacyclooctane.     

Electrodeposition of ferrocenoyl peptide disulfides

Using electrodeposition of cyclic and acyclic Fc-peptide disulfides tightly-packed Fc-peptide monolayers were conveniently formed, which exhibit significant differences in their electron transfer kinetics.     

Modified Alternating $$\vec{k}$$–generators

This paper deals with a class of pseudorandom bit generators – modified alternating –generators. This class is constructed similarly to the class of alternating step generators. Three subclasses of are distinguished, namely linear, mixed and nonlinear generators. The main attention is devoted to the subclass of linear and mixed generators generating periodic sequences with maximal period lengths. A necessary and sufficient condition for all sequences generated by the linear generators of to be with maximal period lengths is formulated. Such sequences have good statistical properties, such as distribution of zeroes and ones, and large linear complexity. Two methods of cryptanalysis of the proposed generators are given. Finally, three new classes of modified alternating –generators, designed especially to be more secure, are presented.     

Improving the dielectric constant of Al2O3 by cerium substitution for high-k MIM applications

Process compatible high-k dielectric thin films are one of the key solutions to develop high performance metal–insulator–metal (MIM) structures for future microelectronic devices. Engineered cerium–aluminate (Ce_xAl_2–xO₃) thin films were deposited on titanium nitride metal electrodes by electron-beam co-evaporation of ceria and alumina in a molecular beam deposition chamber. X-ray photoelectron spectroscopy clearly reveals that Ce cations can be stabilized in the 3+ valence state in Ce_xAl_2–xO₃ up to x = 0.7 by accommodation in the alumina host matrix. Higher Ce content was observed to result in cerium dioxide segregation in cerium aluminate matrix, probably due to the chemical tendency of Ce cations to exist rather in the 4+ than in the 3+ state. Electrical characterization of the X-ray amorphous Ce_0.7Al_1.3O₃ films reveals a dielectric constant value of about 11 and leakage current lower than 10^?4 A/cm². No parasitic low-k interface formation between the high-k Ce_0.7Al_1.3O₃ film and the TiN metal electrode is detected.