Measurement of Some Thermodynamic and Acoustic Properties of Binary Solutions of N,N-Dimethylformamide with 1-Alkanols at 30°C and Comparison with Theories

Densities, and ultrasonic velocities, uof binary mixtures of N,N-dimethylformamide (DMF) + methanol, + ethanol, + 1-propanol, + 1-butanol, + 1-pentanol, and + 1-hexanol have been measured at 30°C. The ultrasonic velocities have been compared with values calculated from the free-length theory ( FLT) due to Jacobson and collision-factor theory ( CFT) due to Schaaffs. The measured data are used to compute adiabatic compressibility (k _s), deviation in adiabatic compressibility (k _s), intermolecular free length (L _f), molar volume (V _m), and available volume (V _a). The excess molar volume ( V _m ^E) and excess free length (L _f ^E) are also evaluated. For all systems, these results were satisfactorily correlated by the Redlich–Kister polynomial. These parameters are used to discuss dissociation of the self-associated 1-alkanol molecules and the formation of aggregates between unlike molecules through C=O...H–O hydrogen bonding.     

Some thermodynamic processes of anthracite–carbon dioxide mixture in supercritical fluid state

In the context of the development of the catalyst regeneration procedure via supercritical fluid CO₂ extraction, some thermodynamic properties of the anthracene–carbon dioxide mixture in supercritical fluid state have been studied. Data on anthracene solubility in pure and modified (dimethyl sulfoxide, 5 wt %) supercritical carbon dioxide (SC–CO₂), the heat capacity of anthracene and its mixtures with carbon dioxide, and the heat of solution of anthracene in SC–CO₂ are presented. Anthracene solubility in SC–CO₂ is described satisfactorily using the Peng–Robinson equation of state.     

Stripping Voltammetry of Cerium(IIl) with a Chemically Modified Carbon Paste Electrode Containing Functionalized Nanoporous Silica Gel

This research introduces the design of an adsorptive stripping voltammetric method for the cerium(III) determination at a carbon paste electrode, chemically modified with dipyridyl‐functionalized nanoporous silica gel (DPNSG‐CPE). The electroanalytical procedure comprised two steps: the Ce(III) chemical accumulation at ?200 mV followed by the electrochemical detection of the Ce(III)/dipyridyl complex, using anodic stripping voltammetry. The factors, influencing the adsorptive stripping performance, were optimized including the modifier quantity in the paste, the electrolyte concentrations, the solution pH and the accumulation potential or time. The resulting electrode demonstrated a linear response over a wide range of Ce(III) concentration (1.0–28 ng mL^?1). The precision for seven determinations of 4 and 10 ng mL^?1 Ce(III) was 3.2% and 2.5% (relative standard deviation), respectively. The prepared electrode was used for the cerium determination in real samples and very good recovery results were obtained.     

A NEW APPLICATION OF N-BROMOSACCHARIN AS A SELECTIVE AND EFFICIENT OXIDATIVE REAGENT FOR REGENERATION OF CARBONYL COMPOUNDS FROM OXIMES

A new method for the direct conversion of various oximes into aldehydes and ketones by treatment with N-bromosaccharin is described. N-bromosaccharin can be used for an effective, selective and mild oxidizing agent for the regeneration of carbonyl compounds from oximes in good yield.     

Numerical modeling of baffle location effects on the flow pattern of primary sedimentation tanks

Computational fluid dynamics (CFD) is used extensively by engineers to model and analyze complex issues related to hydraulic design, planning studies for future generating stations, civil maintenance and supply efficiency. In order to find the optimal position of a baffle in a rectangular primary sedimentation tank, computational investigations are performed. Also laboratory experiments are conducted to verify the numerical results and the measured velocity fields which were by Acoustic Doppler Velocimeter (ADV) are used. The GMRES algorithm as a pressure solver was used in the computational modeling. The results of computational investigations performed in the present study indicate that the favorable flow field (uniform in the settling zone) would be enhanced for the case that the baffle position provide small circulation regions volume and dissipate the kinetic energy in the tank. Also results show that the GMRES algorithm can obtain the good agreement between the results of numerical models and experimental tests.     

Speckle noise reduction by division and digital processing of a hologram

One of the common problems in classical and digital holography is presence of speckle in reconstructed images. Some methods have been predicted for speckle reduction. Speckle has a statistical distribution in size and intensity. Thus complete elimination of them is impossible. But, one can use this statistical characters to reduce its effects.In this paper a method is proposed for reduction of speckle effect by recording a hologram and then dividing it to several sub-holograms. Each sub-hologram is used to produce an image. Final image is constructed by superposition of these images. The final image has a smaller amount of speckle noise. Experimental results verify effectiveness of this technique.     

Fe3O4@SiO2—CPTMS—Guanidine—SO3H-catalyzed One-Pot Multicomponent Synthesis of Polysubstituted Pyrrole Derivatives under Solvent-Free Conditions

Russian Journal of Organic Chemistry - A highly efficient procedure for the one-pot synthesis of polysubstituted pyrrole derivatives by the reaction between of aniline derivatives, β-diketones...     

Sensitive,Fast, Solution‐Processed Ultraviolet Detectors Based on Passivated Zinc Oxide Nanorods

Solution‐processed ultraviolet photodetectors based on passivated and unpassivated zinc oxide (ZnO) nanorods, in which the ZnO nanoparticles are synthesized by a hydrothermal method, are demonstrated and characterized. Photoconductive photodetectors fabricated using simple solution processing have recently been shown to exhibit high gains and outstanding sensitivities. One ostensible disadvantage of exploiting photoconductive gain is that the temporal response is limited by the release of carriers from trap states. Herein, specific chemical species are introduced onto the surfaces of ZnO nanoparticles to produce desired trap states with a carefully selected lifetime. Compared with conventional photodetectors based on ZnO nanoparticles, the proposed UV photodetectors have much higher photoresponses and faster response times in the UV region. The photoconductive gain of the fabricated photodetectors varies from 26.83 to 2.32×10² for passivated samples, which indicates high gain. The best temporal response for the fabricated detectors is 34 ms rise time and 132 ms decay time for ZnO nanoparticles passivated by hexamethylenetetramine.