A structural approach to calculate physical properties of pure organic substances: The critical temperature,critical volume and related properties

A new approach based on computation of the molecular surface interactions (MSI) to estimate several physical properties of pure organic substances is described. MSI are derived from molecular structural data and consist of total molecular surface area, electrostatic molecular surface interactions, and a hydrogen bonding term. This new approach estimates the critical temperature and the molar critical volume of pure organic substances with molecular weights in the range of 40–500 a.u‥ In addition, the following properties can be calculated: the critical pressure, the boiling temperature, the molar volume in liquid state at normal pressure and temperature. The method can be used to predict physical properties of compounds having flexible or rigid, symmetric or asymmetric, polar or nonpolar molecular structures, and compounds with or without hydrogen bonding groups.     

New PP/PLA/cellulose composites: effect of cellulose functionalization on accelerated weathering behavior (accelerated weathering behavior of new PP/PLA/cellulose composites)

Polylactic acid (PLA) was used as partial replacement for conventional thermoplastic matrix, new composites comprising cellulose, polypropylene (PP), and PLA being realized. In order to obtain a compatible interface between cellulosic pulp and polymeric matrix, two chemical modifications of cellulose with stearoyl chloride and toluene di‐isocyanate (TDI) were performed, structural changes being evidenced by X‐ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The composite materials were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, dynamic scanning calorimetry, impact, tensile and melt rheological tests, surface tension, and dynamic vapor sorption. Because promising results for impact strength and Young modulus were recorded when replacing 15% of PP with PLA in blends of PP with the same cellulosic pulp load, the aim of our study was to assess the behavior to accelerate weathering of composites comprising PP, cellulosic pulp, and PLA. Although the slight decrease in the mechanical properties was recorded after accelerated weathering, the use of functionalized cellulose successfully prevented the deterioration of surface materials, especially for composite comprising stearoyl chloride treated cellulose pulp. Copyright © 2015 John Wiley & Sons, Ltd.     

Simultaneous thermal and contraction/expansion analyses of cast iron solidification process

Journal of Thermal Analysis and Calorimetry - Simultaneous thermal and contraction/expansion analysis of hypoeutectic grey (lamellar graphite) and ductile (nodular graphite) cast irons...     

Thermal analysis of Romanian ancient ceramics

The present work is focused on thermoanalytical investigations as thermogravimetric analysis (TG) and derivative thermal analysis (DTG), applied for the characterization of some samples collected from archaeological sites (Brasov and Trofeum Traiani) located in different regions of Romania. New informations derived about ceramic technologies concerning raw materials and binding materials (mineralogical components) have been obtained. All these experimental results have been correlated with related techniques as X-ray diffraction (XRD), energy-dispersive X-ray fluorescence (EDXRF) and inductively coupled plasma—atomic emission spectrometry (ICP-AES). By progressive heating in static air atmosphere and in the temperature range of 20–800 °C, all investigated materials exhibit three main successive processes, associated with the dehydration and thermo-oxidative degradations. The rate of the first thermooxidative process, temperatures corresponding to the maximum rate of the second thermooxidative process and shrinkage temperature were associated with the damage of the investigated materials due to environmental impact. Heating also affects the contact between the fine-sized clay matrix and mineral clast fragments, appearing in reaction rims, sometimes showing newly formed phases. The temperature at which ancient ceramics and pottery were fired varies over a wide range (600–800 °C) depending on the type of clay used, although firing temperatures not above 30–400 °C have also been suggested. Clay minerals, as the main material for production of ceramics and pottery, show some characteristic reactions (dehydroxylation, decomposition, transformation) in the course of firing (heating effects) and several thermoanalytical criteria can be used for reconstruction of former production conditions.     

Electrochemical and microgravimetric studies of poly[3,4-ethylenedioxythiophene]-tyrosinase biocomposite material electrodeposited onto gold electrodes by a sinusoidal voltages method

The electrodeposition of poly(3,4-ethylenedioxythiophene)-tyrosinase (PEDOT-Ty) biocomposite material onto gold electrode has been achieved by means of a sinusoidal voltages (SV) method. The SV method consists in the superimposition of a sinusoidal voltage (sin wave) with fixed frequency and amplitude onto a d.c. potential. The influence of electrochemical parameters like frequency and amplitude of SV signal, d.c. potential value, deposition time, on the electrodeposition process has been investigated. The biocomposite material has been prepared as a thin layer onto quartz crystals coated with gold. The frequency change of the quartz crystal during the electrodeposition of the biocomposite material was recorded simultaneously with the measured current response. The morphology of the deposited PEDOT-Ty coatings was investigated by scanning electron microscopy. The electrochemical behavior of the biocomposite material in aqueous solution was studied by cyclic voltammetry and electrochemical impedance spectroscopy. The use of d.c. potential value of 0.6 V revealed the contribution of the SV component to the electrodeposition process. The PEDOT-Ty modified electrode was used as an electrochemical biosensor in the voltammetric determination of dopamine in the presence of hydroquinone. The analytical performances of the prepared biosensors were also investigated.     

Characteristics of polyurethane-based sustained release membranes for drug delivery

This paper is focused on the preparation and physicochemical characterization of two poly(ester ether urethane)s with rifampicin in their matrix and different molar concentrations of urethane groups. The polyurethanes with rifampicin were processed as asymmetrical microporous membranes by a phase inversion method and characterized by attenuated total reflection — Fourier transform infrared (ATR-FTIR) spectroscopy and differential scanning calorimetry (DSC). The influence of the surface morphology in the release of drug compounds was analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle, and water uptake. The release of rifampicin depends on the molar concentration of urethane groups and also on the surface morphology of the polyurethane membranes. The antibacterial activity was evaluated with S. Epidermidis RP 62 A and P. Aeruginosa ATCC 1544. Finally, the biocompatibility of the polyurethane membranes was studied with human dermal fibroblasts (HDF) to evaluate the potential biomedical applications.      

Influence of velocity profile on calibration function of Lorentz force flowmeter

A Lorentz force flowmeter is a noncontact electromagnetic flow-measuring device based on exposing a flowing electrically conducting liquid to a magnetic field and measuring the force acting on the magnet system. The measured Lorentz force is proportional to the flow rate via a calibration coefficient which depends on the velocity distribution and magnetic field in liquid. In this paper, the influence of different velocity profiles on the calibration coefficient is investigated by using numerical simulations. The Lorentz forces are computed for laminar flows in closed and open rectangular channels, and the results are compared with the simplified case of a solid conductor moving at a constant velocity. The numerical computations demonstrate that calibration coefficients for solid bodies are always higher than for liquid metals. Moreover, it can be found that for some parameters the solid-body calibration coefficient is almost twice as high as for a liquid metal. These differences are explained by analyzing the patterns of the induced eddy currents and the spatial distributions of the Lorentz force density. The result provides a first step for evaluating the influence of the laminar velocity profiles on the calibration function of a Lorentz force flowmeter.     

Benzofurobenzthiazole: VI—1H- und 13C-NMR-Spektren von 2-Aminobenzofuro[2,3-f] benzthiazol und 2-Aminobenzofuro[2,3-e]benzthiazol im Vergleich mit Dibenzofuran und 2-Aminobenzthiazol

Cyclization of 3-dibenzofurylthiourea under the conditions of the Hugershoff reaction gives the linear structure 1. ¹H n.m.r. and ¹³C n.m.r. spectra of the two isomeric aminobenzofurobenzothiazoles (1 and 3), recorded at 220 MHz, 60 MHz and 22,62 MHz respectively, were used as aids for the structure determination. The magnetic parameters were obtained partly by first-order analysis and partly by simulation of spectra using LAOCOON 3. The assignments were made by comparing the chemical shifts and coupling constants with those of the parent compounds dibenzofuran (4a) and 2-aminobenzothiazole (5c). In so far as the assignments of ¹H n.m.r. and ¹³C n.m.r. frequencies of the parent compounds themselves were unknown or supported by analogy only, they have been determined using experimental criteria such as deuterium substitution and investigation of changes in chemical shifts caused by derivation.