Effect of oxidation of nitride coatings on corrosion properties of Ti-6Al-4V alloy in 0.9% NaCl at 40°C

The corrosion properties of Ti-6Al-4V alloy with oxidized thermodiffusion nitride coatings were investigated in isotonic 0.9% solution of NaCl at temperature of 40°C. It was shown that modification of nitride coatings by oxygen leads to a deterioration of the protective properties of nitrided surface of Ti-6Al-4V alloy. The protective properties of the alloy with nitride coatings modified by oxygen are determined by the composition of formed surface oxynitride film.      

Copper(I) π-complexes with allyl derivatives of heterocyclic compounds: structural survey of their crystal engineering

In this review an exhaustive crystallochemical analysis of copper(I) π-complexes with allyl derivatives of heterocyclic compounds has been performed. Structural genesis of inorganic constituents starting from the simplest units to the most complicated aggregates was considered taking into account the specific role of Cu-(C=C) interaction, the construction of the organic ligands, the basicity and nucleophilic activity of their heteroatoms, as well as olefin Cu(I) π-complex preparation route.      

The first synthesis of 3-deoxyoripavine and its utilization in the preparation of 10-deoxyaporphines and cyprodime

The synthesis of 3-deoxyoripavine (7) was realized as a novel and promising intermediate towards the synthesis of the important class of dopaminergic and/or serotonergic 10-deoxyaporphines and the special pharmacological tool µ opioid antagonist cyprodime. Generally, the preparation of these valuable biologically active compounds was achieved in remarkable yields.      

Effect of hydrothermal treatment on the structure of an aluminosilicate polymer

The effect of hydrothermal treatment on the structure of an aluminosilicate polymer prepared by a polycondensation reaction between silicate and hydroxoaluminate in alkaline aqueous solution was studied. The structural changes were investigated using X-ray diffraction analysis, Fourier-transform infrared spectroscopy, scanning electron microscopy imaging and thermogravimetric analysis. The results indicated that the amorphous aluminosilicate polymer transformed into a crystalline product during the hydrothermal treatment at 145°C. The crystalline phase was identified as a mineral of the zeolite group, most likely phillipsite. This transformation required an alkaline environment during the hydrothermal treatment.      

Dynamic pressure thermal analysis of double-base propellants containing RDX

The thermal decomposition of five double-base propellants modified with RDX was studied by dynamic pressure thermal analysis to determine the effect of RDX content (20–60 wt.%) on performance. All have good stability. Both stability and activation energy increase as RDX increases from 20% to 50% then decrease; 50% RDX performs best. The decomposition mechanism is affected by RDX content and temperature. Increasing temperature induces autocatalysis and accelerates decomposition.      

Investigation of thermal and catalytic degradation of polystyrene waste into styrene monomer over natural volcanic tuff and Florisil catalysts

Thermal and catalytic degradation of polystyrene waste over two different samples of natural volcanic tuff catalyst comparative with Florisil catalyst has been carried out in order to establish the conversion degree into styrene monomer. The polystyrene waste (PS) was subjected to a thermal degradation process in the range of 380–500°C in presence of studied catalysts in a ratio of 1/10 in mass, catalyst/PS. The catalysts were characterized by N₂ adsorption-desorption isotherms (BET), Scanning Electron Microscopy (SEM) and Fourier-transform infrared spectrometry (FTIR). Influences of temperature and type of catalysts on the yields and on the distribution of end-products obtained by thermal and catalytic degradation of polystyrene waste have been studied. The maximum yields of liquid products were obtained at 460°C degradation temperature and were calculated between 83.45% and 90.11%. The liquid products were characterized by gas chromatography mass spectrometry (GC-MS) and FTIR analytical techniques. The GC-MS results showed that the liquid products contained styrene monomer up to 55.62%. The FTIR spectra of liquid products indicated the specific vibration bands of the functional groups of compounds of liquid products. The amounts of styrene monomer obtained were influenced by structural and textural properties of studied catalyst and the contribution on product distribution is discussed.      

Reaction of barbituric acid with organic azides and phosphonium ylides

Amination by organic azides has been carried out to provide aminobarbiturates by fusion of a triazole ring to the 5,6-positions of barbituric acid followed by cleavage and thermal elimination of nitrogen, whereas aza-Wittig reaction gave phosphoranylidene barbituric acid salts.      

Fabrication of superhydrophobic surface of stearic acid grafted zinc by using an aqueous plasma etching technique

A stable superhydrophobic surface of stearic acid grafted zinc was fabricated with two steps, that is, the zinc surface was firstly treated with glow discharge electrolysis plasma (GDEP) and then followed by a grafted reaction of stearic acid onto the treated zinc surface. Results indicated that the wettability of zinc substrate changed from superhydrophily to superhyphodrobicity with a water contact angle (CA) up to 158° and a water sliding angle (SA) less than 5°. The surface morphology and composition were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively.      

AlZn based Co and Ni catalysts for the partial oxidation of bioethanol — influence of different synthesis procedures

The catalytic performance of Co and Ni catalysts on AlZn mixed oxide supports depends on the synthesis procedure used for their preparation. For this study CoAlZn and NiAlZn catalysts were prepared by conventional sol-gel synthesis of the mixed oxide and subsequent impregnation of the support with the transition metal (SG = sol gel method) as well as by a single-step method were a gel is formed based on salts of all components using citric acid as chelating agent (CM = citrate method). The structure and morphology of the catalysts were characterized by nitrogen sorption, XRD and TPR measurements. They showed high activity in the partial oxidation of ethanol at 600–750 °C, but their properties depend on the preparation method. The higher performance of the catalysts prepared by the citrate method, where the transition metal is incorporated into the crystal structure of the support during preparation, is based on a change in morphology and structure, resulting in more active sites exposed on the surface. Compared to the Co catalysts, Ni catalysts showed a higher performance. This might be due to the higher reducibility and the smaller Ni particles size, which allows a better interaction with the support in NiAlZn catalysts.      

Extractants selection for hyphenated electrothermal atomic absorption method

The theoretical approach for extractants selection during hyphenated atomic absorption determination of highly volatile metals (Pb, Cd), hydride- (Sb, Bi) and carbide-forming (Cr) metals using thermodynamic modelling was proposed. The calculated parameter — maximum pyrolysis temperature — can be used for selection of the extractants and chemical modifiers. Using this approach the antimony extract with Brilliant green was modified for which the 1.8-fold sensitivity and 2.6-fold repeatability decreasing while extract sampling in graphite furnace was observed. A chemical modifier — mixture of hydrazine nitrate with the palladium(II) complex with Xylenol orange — was theoretically selected and experimentally tested, which allowed to enhance the maximum pyrolysis temperature on 200°C, to eliminate extract matrix influence. Using this modifier two-fold increasing in sensitivity and 3-fold decreasing in relative standard deviation was achieved while extraction atomic absorption determination.      

Electrical conductances of aqueous sodium trifluoromethanesulfonate from 0 to 450°C and pressures to 250 MPa

The electrical conductances of dilute (0.001 to 0.1 mol-kg^?1) aqueous sodium trifluoromethanesulfonate (NaCF₃SO₃) solutions have been measured from 0 to 450°C and pressures to 250 MPa. The limiting molar conductance $\Lambda _0 $ increases with increasing temperature from 0 to 300°C and decreasing density from 0.8 to 0.3 g-cm^?3. Above 300°C, $\Lambda _0 $ is nearly temperature independent, but increases linearly with decreasing density. The logarithm of the molal association constant of NaCF₃SO₃ calculated at temperatures from 372 to 450°C is represented as a function of temperature (Kelvin) and density of water (g-cm^?3) by $$\log K_m = 0.888 - 330.4/T - (12.83 - 5349/T)\log \rho _w $$ The relative strengths of NaCF₃SO₃ and NaCl are similar within the accuracy of the current measurements over the limited range of temperature and pressure that could be investigated here.     

Copper-cobalt ferrites as catalysts for methanol decomposition

Copper-cobalt ferrites with composition Cu_1?xCo_xFe₂O₄, where x= 0.2 and 0.8 were prepared by thermal treatment of co-precipitated precursor. The obtained materials were characterized by TG-DSC, XRD, Transmission and Conversion Electron Mössbauer spectroscopy and temperature programmed reduction with hydrogen. The catalytic properties of ferrites were tested in methanol decomposition to CO and hydrogen.      

A novel 2-(2-methyl-2-nitrovinyl)-furan ectoparasitic drug: physicochemical characterization and determination of the raw material by gas chromatography mass spectrometry

2-(2-methyl-2-nitrovinyl)-furan (NVF) has recently been synthesized and the pharmaceutical industry interest in this compound has grown due to its antibacterial, fungicidal and anti-ectoparasitic activities. Therefore, the physicochemical characterization of new drug was conducted. In addition, two rapid, simple and suitable GC methods were developed for determination of NVF. Analyses were carried out with an Agilent DB-5ms capillary column (60 m × 0.25 mm i.d., 0.25 µm film thickness). The GC-FID analysis employed splitless mode of injection, oven/injector/detector temperature of 160/230/280°C and nitrogen carrier at the flow of 5.0 mL min^?1. The GC-MS analysis employed splitless mode of injection, helium carrier at the flow of 1.5 mL min^?1, column temperature program with 2 min at 100°C, ramp at 50°C min^?1 to 260°C and injector and detector temperature of 250 and 290°tC, respectively. The MS conditions were ionization voltage, 70 eV; mass range, m/z 40–350; and ion source temperature, 200°C. The analysis time took less than 6 min. The results obtained in the validation of the methods suggest that these methods are economic, precise, accurate and linear over the range of analysis. The methods were successfully employed during the synthesis of NVF in order to ensure the quality of the raw material.      

Magnetic resonance study of carbon encapsulated Ni nanoparticles

Magnetic resonance study of six samples consisting of carbon encapsulated nickel nanoparticles or carbon nanotubes ended with such nickel nanoparticles was carried out at room temperature. Samples of Ni/C were prepared by carburization of nanocrystalline nickel by ethylene (C₂H₄) and methane (CH₄). Hydrocarbons decomposition on nickel nanoparticles was done at temperatures 500, 600 and 700°C. Magnetic resonance spectra of samples designated as CH₄/500, CH₄/600, CH₄/700, C₂H₄/500, C₂H₄/600 and C₂H₄/700 were obtained by Bruker E 500 spectrometer. The integrated intensities of the resonance spectra were correlated with the carburization conditions (temperature, type of hydrocarbon) during samples preparation. A core-shell model of the investigated samples allowed rough estimation of appropriate shell sizes.      

Polymer conjugates with potential biological activity based on new derivatives of 2-mercaptobenzoxazole-synthesis and characterization

New potentially biologically active compounds derived from 2-mercapto-benzoxazole were synthesized and coupled on polymeric support of poly (maleic anhydride-alt-vinyl acetate) for the preparation of polymer-drug conjugates with controlled drug release. All compounds were characterized by elemental and spectroscopy (FT-IR, ¹H-NMR) analysis. The toxicological tests recommend the products for further laboratory screening.      

Hydroconversion of parafine LTP56-H over nickel/Na-mordenite catalysts

Nickel catalysts supported on Na-mordenite were used for paraffin LTP56-H hydroconversion into liquid material as a possible component for engine fuels. The effects of none-catalytic thermal treatment and catalytic conditions-zeolite type and reaction conditions (solvent) on the process of liquefaction of LTP56-H paraffin and physicochemical properties of catalysts were studied. The physicochemical properties of catalytic systems were investigated using XRD, TPR, TPD-NH3 and SEM-EDS methods.      

Syngas production by biogas reforming over the Co-based multicomponent catalysts

The new multicomponent Co-based catalysts with additives of group 8 metal and rare earth elements and supported on alumina have been tested in the dry and steam conversion of a model biogas. The processes were carried out in a flow quartz reactor under the following conditions: atmospheric pressure, a gas hourly space velocity of 1000 h^?1 and temperatures of 300–800°C. The catalysts were characterised using electron microscopy, BET and X-ray analysis. The methane is almost completely converted in the dry reforming of biogas at T≤800°C. Synthesis gas with a ratio of H₂/CO>1.0 is a main product of biogas reforming over the multicomponent catalysts studied. Adding steam in a feed composition increases both the methane conversion and the hydrogen yield at lower temperatures. Almost complete methane conversion occurs at T<750°C in the steam reforming of biogas. The catalysts are highly effective and exhibit stable activity throughout 100 h of continuous testing.      

Physico-chemical properties investigation of softwood surface after treatment with organic anhydride

Wood originating from a softwood species was subjected to chemical treatment by reaction with succinic anhydride in N, N-dimethylformamide at different concentration values. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analysis were used to study changes that occurred on a softwood surface. The extent of chemical treatment on softwood was evaluated by determining the weight percent gain values. Thermal properties of modified softwood and the water absorption were also evaluated. The chemical treatment with succinic anhydride influenced the thermal stability of the softwood samples with increasing anhydride concentration levels.      

Three–step method to determine the eutectic composition of binary and ternary mixtures

A three-step method to determine the eutectic composition of a binary or ternary mixture is introduced. The method consists in creating a temperature–composition diagram, validating the predicted eutectic composition via differential scanning calorimetry and subsequent T-History measurements. To test the three-step method, we use two novel eutectic phase change materials based on \(\mathrm{Zn}(\hbox {NO}_3)_2\cdot 6\mathrm{H}_{2}{\mathrm O}\) and \(\mathrm{NH}_4\mathrm{NO}_3\)   respectively \(\mathrm{Mn}(\hbox {NO}_3)_2\cdot 6\mathrm{H}_{2}{\hbox {O}}\) and \(\mathrm{NH}_4\mathrm{NO}_3\) with equilibrium liquidus temperatures of 12.4 and 3.9  \(\,^{\circ }\mathrm {C}\) respectively with corresponding melting enthalpies of 135 J \(\mathrm{g}^{-1}\) (237 J \(\mathrm{cm}^{-3}\) ) respectively 133 J \(\mathrm{g}^{-1}\) (225 J \(\mathrm{cm}^{-3}\) ). We find eutectic compositions of 75/25 mass% for \(\mathrm{Zn}(\hbox {NO}_3)_2\cdot \mathrm{6H}_{2}{\mathrm{O}}\) and \(\mathrm{NH}_4\mathrm{NO}_3\) and 73/27 mass% for \(\mathrm{Mn}(\hbox {NO}_3)_2\cdot 6\mathrm{H}_{2}{\mathrm{O}}\) and \(\mathrm{NH}_4\mathrm{NO}_3\) . Considering a temperature range of 15 K around the phase change, a maximum storage capacity of about 172 J \(\mathrm{g}^{-1}\) (302 J \(\mathrm{cm}^{-3}\) ) respectively 162 J \(\mathrm{g}^{-1}\) (274 J \(\mathrm{cm}^{-3}\) ) was determined for \(\mathrm{Zn}(\hbox {NO}_3)_2\cdot \mathrm{6H}_{2}{\mathrm{O}}\) and \(\mathrm{NH}_4\mathrm{NO}_3\) respectively \(\mathrm{Mn}(\hbox {NO}_3)_2\cdot \mathrm{6H}_{2}{\mathrm{O}}\) and \(\mathrm{NH}_4\mathrm{NO}_3\) .