Preliminary studies on the surface layer of starch

Characterization of the surface layer of starch powder, originated from potato or maize, was carried out applying various experimental techniques: Fourier-transformed infrared internal reflection spectroscopy (FTIR-IRS), inverse gas chromatography (IGC) and scanning electron microscopy (SEM). The main kinds of starch were studied as potential fillers for rubber and results discussed in terms of factors requiring modification to improve starch miscibility and activity towards rubber. Starch of high amylopectine content shows surface enrichment with amylose what makes crystallinity of the surface layer higher than in bulk of the material. Particles of the both kinds of starch have very smooth surface (morphological index, I_m = 0.995), highly resistant to its geometrical development. Dispersive component of the surface energy of starch was found to be similar to that of low energy polymers (γ_s^d = 32.5 mJ/m² at 23°C) and its surface to be of electron-donor character.     

Electronic Nose Differentiation between Quercus robur Acorns Infected by Pathogenic Oomycetes Phytophthora plurivora and Pythium intermedium

Identification of the presence of pathogenic oomycetes in infected plant material proved possible using an electronic nose, giving hope for a tool to assist nurseries and quarantine services. Previously, species of Phytophthora plurivora and Pythium intermedium have been successfully distinguished in germinated acorns of English oak Quercus robur L. Chemical compound analyses performed by HS-SPME/GC-MS (Headspace Solid-Phase Microextraction/Gas Chromatography–Mass Spectrometry) revealed the presence of volatile antifungal molecules produced by oak seedlings belonging to terpenes and alkanes. Compounds characteristic only of Phytophthora plurivora or Pythium intermedium were also found. Methylcarveol occurred when germinated acorns were infected with Pythium, while neophytadiene (isomer 2 and 3) occurred only when infected with Phytophthora. Moreover, isopentanol was found in acorns infected with Phytophthora, while in control, isopentyl vinyl ether was not observed anywhere else. Among the numerous volatile compounds, isopentanol only occurred in acorns infected with Phytophthora and methylcarveol in acorns infected with Pythium.     

On a Unique Ergodicity of Some Markov Processes

It is proved that the sufficient condition for the uniqueness of an invariant measure for Markov processes with the strong asymptotic Feller property formulated by Hairer and Mattingly (Ann Math 164(3):993–1032, 2006) entails the existence of at most one invariant measure for e-processes as well. Some application to time-homogeneous Markov processes associated with a nonlinear heat equation driven by an impulsive noise is also given.     

The Effect of Stationary Phase Type and Mobile Phase pH on the Separation of Some Catecholamines

JPC – Journal of Planar Chromatography – Modern TLC - The catecholamines are very important in the control and regulation of a variety of functions acting as neurotransmitters in both...     

Application of DTA/DSC and dilatometry for optimization of Ba–Ce–Y–P–Si–O glass phase for composite protonic conductors based on BaCe<Subscript>0.9</Subscript>Y<Subscript>0.1</Subscript>O<Subscript>3−<Emphasis Type="Italic">δ</Emphasis></Subscript>

The aim of this work was to determine the influence of chemical composition on thermal and electrical properties of selected glass from the BaO–CeO₂–Y₂O₃–P₂O₅–SiO₂ system. Properties of the investigated glasses were optimized in terms of glass-BaCe_0.9Y_0.1O₃ composite protonic conductor preparation. Three types of glasses with different P₂O₅/SiO₂ ratio were prepared and investigated. The DSC and XRD measurements indicated limited tendency to crystallization of obtained glasses up to T = 1023 K. The dilatometry measurements led to determination of the thermal expansion coefficients (TEC) and the softening point. It was found that obtained glasses soften in temperature range of 903–923 K, depending on the composition which is advantageous from the viewpoint of further preparation and formation of the composite material. The Electrochemical Impedance Spectroscopy measurements done as a function of temperature and gas atmosphere allowed to determine the activation energy of the electrical conductivity. Observed fluctuations of the activation energy with gas atmosphere suggest the possible role of the protonic defects in total conductivity. Based on the obtained results it can be stated that proposed glass system may be considered as the modifying phase for improvement of BaCe_0.9Y_0.1O₃-based materials.     

Design,synthesis, structure elucidation and in vitro antiviral and antimicrobial evaluation

In this study, we described the synthesis of the derivatives of thiosemicarbazide, dicarboximide, 1,2,4-triazole-5-thione and 4-oxo-1,3-thiazolidine. Two different dicarboxylic acid anhydrides reacted with 4-substituted-3-thiosemicarbazide, and derivatives of thiosemicarbazide and dicarboximide were obtained. Next, cyclization reaction of dicarboximide derivatives in alkaline media was used to prepare 1,2,4-triazole-5-thione. The 4-oxo-1,3-thiazolidine was synthesized by the reaction of dicarboximide with ethyl bromoacetate. All obtained derivatives were analysed by ¹H and ¹³C NMR spectra, and for one compound, the X-ray crystallography was done. Antimicrobial, antiviral and in vitro evaluations of cytotoxicity were examined. According to the preliminary antiviral screening, compounds 3 and 4 presented the antiviral activity against HSV-1 and CVB3. Additionally, compound 3 shows selective in vitro toxic effect against human epithelial cells FaDu, without affecting normal animal cell line (Vero). The same derivatives 3 and 4 also displayed a wide spectrum of antimicrobial activity against reference microorganisms and indicated both antibacterial and antifungal potential activities.     

On the prime model property

Assume is superstable, is a formula over , is countable and is countable and . We investigate models in assuming has the prime model property. We prove some corollaries on the number of models in . We show an example of an -stable and with having exactly 3 models.

     

Polycondensation Products of Phloroglucine with Difunctional Aliphatic Amines

The known reaction of condensation of a strong amine with phloroglucine under quite mild conditions was the starting point for synthesis of a new series of macromolecular resins not previously dèscribed. Phloroglucine has been condensed with a series of nine aliphatic diamines in aqueous solution under atmospheric pressure. The resins obtained are dark powders, which can be molded under increased pressure in the temperature range of 175–310°C. The thermal, mechanical, chemical, and electrical properties of the new resins have been examined and their structure confirmed. Some properties of resins can be calculated by means of approximate mathematical formulas.     

Influence of alkaline earth oxides on thermal stability of oxyfluoride glass

A new type of glass from the Na₂O–MeO–Al₂O₃–SiO₂–LaF₃ system where MeO = MgO, CaO, BaO and SrO has been studied. The aim of the investigation was to determine, by means of thermal techniques (DTA and DSC), the influence of alkaline earth ions additions on its thermal stability and the ability of LaF₃ phase to crystallization. The effect of LaF₃ crystallization was analyzed in connection with glass composition expressed by the Al₂O₃/(MeO + Na₂O + 3La₂F₆) ratio varying from 0.4 to 0.8 for the alkaline earth admixtures. The compositions of the glasses have been designed so as to make it possible to define the effect of the charge of the ion modifiers (Na⁺, Me²⁺, La³⁺) on the alumina position in the framework of the glass. Two series of glasses were obtained with a different F⁻ content. The formation of LaF₃ depends directly on the strength of the network and can be control by the Al₂O₃/modifiers ratio as well as the content of fluorine ions. Generally, it can be stated that transparent glass-ceramic with nanocrystallization of LaF₃ can be obtained for Al₂O₃/(Na₂O + MeO + 3La₂F₆) ≤0.6 in the examined glasses. The more the ionicity of the alkaline earth ions the greater the tendency for the crystallization of Me₂LaF₇ and MeF₂. In the glass structure the substitution of oxygen ions by F⁻ ions facilitated the crystallization of LaF₃. Simultaneously, it influenced the thermal stability of the aluminosilicate network and induced the crystallization of appropriate silicates during the heat treatment.     

Effect of Er<Subscript>2</Subscript>O<Subscript>3</Subscript> on thermal stability of oxyfluoride glass

Glasses have been synthesized in the system SiO₂–Al₂O₃–Na₂O–AlF₃–LaF₃–Er₂O₃. A base glass (in mol% 67SiO₂–9Al₂O₃–20Na₂O–Al₂F₆–3La₂F₆) was modified by 0.5, 0.75, 1, 1.25, 1.5, 2 and 5 mol% Er₂O₃, respectively. Glasses were prepared by conventional fusion method from 20 g batches. The glass transition temperature (T _g), the jump-like changes of the specific heat (ΔC _p) accompanying the glass transition and the enthalpy of crystallization (ΔH) were calculated. DTA measurements clearly reveal that the increase of the Er₂O₃ content in the glass changes the effects of crystallization and diminishes the thermal stability of the glassy network. In the same time the changes in the transition temperature are observed. The formation of NaLaF₄ and Na_1.45La_9.31(SiO₄)₆(F_0.9O_1.1) as a main phase was confirmed. The diminishing of the thermal stability was connected with erbium which incorporated into Na_1.45La_9.31(SiO₄)₆(F_0.9O_1.1) structure.