The influence of anilino-substituted salicylanilide on the physicomechanical properties of ultraviolet-aged natural rubber

The effect of nine derivatives of salicylanilides on the elastic properties of ultraviolet-aged natural rubber have been investigated. The results are compared with similar blends without additives and also with reference samples containing phenyl salicylate. The compounds showed variable effects, but both o-Cl and p-OCH₃ derivatives showed remarkable effects. They both help in the thermal crosslinking. Also, natural rubber samples containing these derivatives showed remarkable stability in tensile stress, elongation, and swelling.     

In-vitro evaluation of sustained-release dyphylline tablets

Dyphylline tablets were prepared by direct compression of mixtures of the drug, emcompress and different ratios of hydroxypropyl methylcellulose (HPMC) or cellulose acetate phthalate (CAP). Physical properties of the prepared tablets and the drug release in 0.1 N HC1 and phosphate buffer, pH 7.4 were investigated.

All tablets were found to satisfy the USP requirements regarding content, weight uniformity and friability. Hardness was greatly enhanced and thickness was slightly increased by increasing the polymer ratio in tablet formulations. Disintegration time of the dyphylline tablets was delayed by the presence of either HPMC or CAP and there was a direct relationship between the polymer ratio and the disintegration time. Considerable retardation in the rate and extent of drug release from the prepared tablets in both dissolution liquids was observed. As the polymer ratio increased in the tablet formulations, the drug release was significantly inhibited.     

Reactive processing and properties of nickel aluminide–carbon nanotube composites

This paper for the first time investigates combustion synthesis of 3Ni-Al–carbon nanotube (CNT) powder compacts simultaneously under two modes of ignition (electrically activated reaction synthesis (EARS) and electrically ignited self-propagating high-temperature synthesis (EISHS)), using a novel setup. The resulting phases, microstructure, porosity, and hardness were investigated and discussed. An increase in CNT (0–3 vol.%) content led to an increase in product porosity and microstructural inhomogeneity. This was seen most dramatically in the EISHS mode compared to the EARS. The increased pore content in EISHS regions resulted in lower hardness values. However, in regions of the compact that experienced EARS, an increase in CNT content led to an increase in microhardness, in spite of the higher porosity levels. The latter result highlights the important benefit of adding CNTs to nickel aluminides.

     

A free-front tracking algorithm for a control-volume-based Hele–Shaw method

With free surface flow problems the position of the free front at a particular time step needs to be predicted. When simulating the flow of hot molten polymer in injection moulds this position is essential for the prediction of the position of the weld lines on the final product. Weld lines are important in that they indicate positions of diminished strength and spoil the aesthetics of the product. A code using a finite volume approach on the thin gap Hele–Shaw flow equations to simulate the filling stage of the injection moulding process has been developed which requires a suitable algorithm for the free-front tracking. The Volume of Fluid (VOF) method was implemented in this study for the tracking of the free front. The discretization and various formulations of the VOF equation are presented as well as the results obtained. The impact on the existing equations is also investigated as well as the development of a packing routine that is used to eliminate the diffusive nature of the VOF equation. © 1998 John Wiley & Sons, Ltd.     

Chitosan/MCM‐41 nanocomposites for efficient beryllium separation

Chitosan nanoparticles (Ch NPs) with individual particles 10–30 nm in size and average aggregate sizes of 240 nm were prepared via ionic gelation. Ordered mesoporous Mobil Composition of Matter No. 41 (MCM‐41) with a surface area of 1590 m²/g was prepared via a sol–gel method. The nanocomposites were prepared via the in situ dispersion of MCM‐41 in chitosan followed by ionic gelation with a multivalent anion to produce MCM‐41‐impregnated Ch NPs or via the mixture of dispersed MCM‐41 with preprepared Ch NPs to produce Ch NPs supported on MCM‐41. The beryllium‐uptake efficiency was studied with different pH values, contact times, and initial Be(II) concentrations. The maximum achieved uptake efficiencies of the nanocomposites (95% and 96%) were superior to that of MCM‐41 (38%) and higher than that of Ch NPs (90%). The nanocomposite formulas facilitated post‐treatment separation while maintaining a high beryllium‐uptake efficiency. The Be(II)‐uptake process for all of the materials followed the pseudo‐second‐order kinetic model and both the Langmuir and Freundlich isotherms. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46040.     

Reactions with 5-Aminobenzothiophene and 5-aminobenzothiadiazole

Both 5-aminobenzothiophene and 5-aminobenz-1,2,3-thiadiazole condense readily with 2,4-dinitrochlorobenzene to give dinitroanilino derivatives which provide after partial reduction the aminonitroanilino derivatives. Treatment of these o-diamines with the proper reagents affords triazole and imidazole derivatives. Oxidation of 4-arylazo-5-aminobenzothiophene or benz-1,2,3-thiadiazole yields the corresponding triazole derivatives.     

Achieving ultra-high electromagnetic wave absorption by anchoring Co0.33Ni0.33Mn0.33Fe2O4 nanoparticles on graphene sheets using microwave-assisted polyol method

The Co_0.33Ni_0.33Mn_0.33Fe₂O₄/graphene nanocomposite for electromagnetic wave absorption was successfully synthesized from metal chlorides solutions and graphite powder by a simple and rapid microwave-assisted polyol method via anchoring the Co_0.33Ni_0.33Mn_0.33Fe₂O₄ nanoparticles on the layered graphene sheets. The Fe³⁺, Co²⁺, Ni²⁺ and Mn²⁺ ions in the solutions were attracted by graphene oxide obtained from graphite and converted to the precursors Fe(OH)₃, Co(OH)₂, Ni(OH)₂, and Mn(OH)₂ under slightly alkaline conditions. After the transformations of the precursors to Co-Ni-Mn ferrites and conversion of graphene oxide to graphene under microwave irradiation at 170?°C in just 25?min, the Co_0.33Ni_0.33Mn_0.33Fe₂O₄/graphene nanocomposite was prepared. The composition and structure of the nanocomposite were characterized by X-ray diffraction (XRD), inductive coupled plasma emission spectroscopy (ICP), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy (RS), transmission electron microscopy (TEM), etc. It was found that with the filling ratio of only 20?wt% and the thickness of 2.3?mm, the nanocomposite showed an ultra-wide effective absorption bandwidth (less than ?10?dB) of 8.48?GHz (from 9.52 to 18.00?GHz) with the minimum reflection loss of ??24.29?dB. Compared to pure graphene sheets, Co_0.33Ni_0.33Mn_0.33Fe₂O₄ nanoparticles and the counterparts reported in literature, the nanocomposite exhibited much better electromagnetic wave absorption, mainly attributed to strong wave attenuation, as a result of synergistic effects of dielectric loss, conductive loss and magnetic loss, and to good impedance matching. In view of its thin thickness, light weight and outstanding electromagnetic wave absorption property, the nanocomposite could be used as a very promising electromagnetic wave absorber.     

TRANSFORMATION OF n-OCTANE INTO AROMATIC HYDROCARBON OVER ZSM-S ZEOLITES

ABSTRACT

Conversion of n- octane over ZSM-5 zeolites are greatly enhanced by incorporation of 0.35 wt. % Fe, Zn, Zr metals. Hydroconversion rates were conducted at temperature range of 350-500 C, W/F of 14.8 g of catalyst / g. mole of feed / h, and hydrogen / feed = 5:1 (mole : mole). The product selectivity with total conversion was examined at the temperature range under study. The catalyst Zr / H25 M-5 gave the highest selectivity towards aromatization and production of xylenes.     

SOLIDS DISTRIBUTION IN A BATCH BUBBLE COLUMN

This paper presents some new experimental data for axial solid distribution in batch slurry reactors. The effects of liquid and solid properties on the solid dispersion behavior in 0.076 m and 0.305 m diameter slurry bubble columns are outlined. The effects of gas distributor, column internals and particle size distribution on the solids concentation profiles are also examined. Critical gas velocity for complete suspension of solids are measured and compared with those predicted from the available literature correlations. It is shown that when the particles are completely suspended, the Peclet number obtained from the sedimentation-dispersion model depends very significantly on the assumed boundary conditions. The effect of gas velocity on the particle Peclet number depends on the nature of the liquid-solid system.