Defining syntax-directed translations by tree bimorphisms

We introduce a class of tree bimorphisms that define exactly the translations performed by syntax-directed translation schemata. We also show that these “quasi-alphabetic” tree bimorphisms preserve recognizability, and that their class is closed under composition and inverses.     

Coding Gain Distance Exact Estimation for Space-Time Trellis Coded Modulation

Space-time (ST) trellis coded modulation (TCM) represents a high spectral efficiency technique for multiple antennas transmissions over fading channels. In literature, it was shown that ST-TCM technique offers full diversity when the rank criterion is met. However, “brute force” methods were used in almost all previous work to search for full diversity ST-TCM codes. In the present paper, we aim to derive an exact expression for the minimum coding gain distance (CGD) in the case of full diversity ST-TCM codes with minimum memory size, for two transmit antennas. Therefore, we transpose the ST-TCM design rules into operations over the set of modulo-M integer numbers (Z _M ), between the current trellis state and encoder’s input information symbol value, in order to derive the transmitted M-levels phase shift keying modulated (M-PSK) output values. In this context, a new design method is introduced to control the code’s minimum CGD value of full diversity ST-TCM schemes.     

Eco-friendly flame retardant epoxy nanocomposites based on polyphosphonate and halloysite nanotubes

The preparation of a novel polyphosphonate (PSFR) is described here, starting from phenylphosphonic dichloride and an equimolecular mixture containing equal amounts of two bisphenols, namely 4,4′-dihydroxydiphenyl sulfone and 2-(6-oxido-6H-dibenzo<c,e><1,2>oxaphosphorin-6-yl)-1,4-benzenediol, following the polycondensation reaction in solution. Then, new environmental-friendly nanocomposites having improved flame retardancy have been prepared by incorporating PSFR and halloysite nanotubes (HNTs) into epoxy resin. The effect of PSFR and HNTs contents on the chemical and physical characteristics of epoxy nanocomposites was investigated. The success of the reactions was monitored by infrared spectroscopy (FTIR) while microscopic related techniques (SEM) gave information on the morphology of the products. The thermosets exhibit glass transition temperatures in the range of 62.4–97.1°C and thermal decomposition temperatures in the interval of 296–359°C. The appearance of the char residues obtained by pyrolysis was studied by SEM measurements. The flammability behavior has been studied by microscale combustion calorimetry (MCC) tests. A considerable improvement in the flame retardancy of the thermosets was obtained by simultaneous incorporation of HNTs (10 wt%) and PSFR (equivalent of 1 wt% P) into epoxy resin.     

Some Polyamides,Polyesters, and Polyurethanes Containing AZO Groups

The paper discusses the synthesis of the N,N,′-azobis(formamidopropionic) acid (AFP), along with some characteristics determined from NMR spectrum, differential thermal analysis, and DSC. The behavior of AFP acid—as well as of its analogue, N,N′-azobis(formamidoacetic) acid (AFA)—has been studied in the reaction with aromatic diamine and with bis(glycol)terephthalate, leading to azopolymers of the azopolyamide, or azopolyester, type. On employing N,N′-bis(β-hydroxyethyl) azobis-formamide (HEAF) as the azo bifunctional compound in the reaction with diphenylmethane diisocyanate, a polyurethane possessing azo groups was obtained. The structure of the azopolymers has been spectroscopically confirmed.     

Application of adaptive neuro-fuzzy interference system on biosorption of malachite green using fir (Abies nordmanniana) cones biomass

Removal of malachite green (MG) onto fir (Abies nordmanniana) cones biomass (FCB) as a lingo-cellulosic-based structure material was investigated in the present study. Characterization of FCB was performed using Fourier transform infra red and scanning electron microscobe analyses. Several parameters (biomass dose and particle size, dye concentration, temperature, and pH) were investigated to determine optimal working conditions. Subsequently, FCB yelded a q_e of 2.2?mg/g for 50?g/L FCB, in an MG solution of 110?mg/L, pH 3.3, at a temperature of 21?°C, on a 0.2-0.4?mm fraction powder after 146?h of contact. Adaptive neuro-fuzzy interference system modeling was applied to experimental data and results showed that predicted model fitted experimental data with R² = 0.994. In a nutshell, it can be concluded that FCB shows good potential for treating MG contaminated waters.     

Effect of the surface modification of the synthetic meshes used in the surgical treatment of pelvic organ prolapse on the tissue adhesion and clinical functionality

Stress urinary incontinence and pelvic organ prolapse represent important conditions affecting adult women’s health. Lately, the properties and performance of the polymer materials used in the treatment of pelvic organ prolapse have been improved by modulating from their formula. Materials investigated in our study are polypropylene meshes used by clinicians in surgical treatment of urinary incontinence and utero-vaginal prolapse. In order to make a comparative analysis, we confronted the structure and surface morphology of native synthetic polypropylene meshes with explanted fragments from the same mesh type after clinical use. FTIR investigations revealed little change in structure after implantation, somehow insignificant. Scanning electron microscopy (SEM) demonstrates modification in surface morphology even just by passing through the transobturator passage, whereas after implantation the surface deteriorates. SEM on explanted meshes proves the encapsulation process of the mesh to be more similar to a foreign body reaction rather than to the adhesion and integration of the synthetic mesh into the organism. Histological analysis of the surrounding tissues near explanted mesh was made in some relevant clinical cases, because the tissue response is an important factor in order to evaluate the tissue adhesion at the polypropylene mesh surface. Based on our experiments and clinical experience we’ve designed an adhesion score. It applies to meshes used in pelvic organ prolapse surgery measuring the following important factors: tenacity, extent of adhesion, macroscopic and microscopic aspects and ease of dissection from surrounding tissues.     

Study of the Catalytic Activity–Semiconductive Properties Relationship For BaTiO<Subscript>3</Subscript> and PbTiO<Subscript>3</Subscript> Perovskites,Catalysts for Methane Combustion

Abstract  

The electrical conductivity of barium and lead perovskites used as catalysts for the total oxidation of methane, has been measured under nitrogen, methane–nitrogen mixture, air and methane–air mixture (reaction mixture) at the catalytic reaction temperature. The two compounds appeared to be p-type semiconductors under air with positive holes as the main charge carriers but became n-type when contacted with methane–nitrogen mixture. Their conductivities differ by 1.5 orders of magnitude as n-type semiconductors and by three orders of magnitude when being p-type semiconductors. These results explained the difference in the catalytic activity encountered on the two solids. The alkane activation was proposed to be related in both cases to the p-type semiconducting properties of the solids, likely through hydrogen abstraction by a surface O⁻ species, forming a CH₃^• radical. The overall reaction mechanism on both perovskites can be assimilated to a Mars and van Krevelen mechanism.     

Chemical oxidation of residual carbon from ZnAl2O4 powders prepared by combustion synthesis

The removal of carbon residue from ZnAl₂O₄ nanopowders by annealing at 500–800 °C leads to a decrease of specific surface area from 228.1 m²/g to 47.6 m²/g. At the same time, the average crystallite size increased from 5.1 nm to 14.9 nm. In order to overcome these drawbacks, a new solution for removing the carbon residue has been suggested: chemical oxidation using hydrogen peroxide. In terms of carbon removal, a H₂O₂ treatment for 8 h at 107 °C proved to be equivalent to a heat treatment of 1 h at 600 °C. The benefits of chemical oxidation over thermal oxidation were obvious. The specific surface area was much larger (188.1 m²/g) in the case of the powder treated with H₂O₂. The average crystallite size (5.8 nm) of ZnAl₂O₄ powder treated with H₂O₂ was smaller than the crystallite size (8.2 nm) of the ZnAl₂O₄ powder annealed at 600 °C.