Studies on the applicability of artificial neural network (ANN) in emulsion liquid membranes

An artificial neural network (ANN) model of emulsion liquid membrane (ELM) process is proposed in the present study which is able to predict solute concentration in feed during extraction operation and ultimate % extraction at different initial solute concentration in feed phase, internal reagent concentration, treat ratio, volume fraction of internal aqueous phase in emulsion and time. Because of the complexity in generalization of the phenomenon of ELM process by any mathematical model, the neural network proves to be a very promising method for the purpose of process simulation. The network uses the back-propagation algorithm (BPA) for evaluating the connection strengths representing the correlations between inputs (initial solute concentration in feed phase, internal reagent concentration, treat ratio, volume fraction of internal aqueous phase in emulsion and time) and outputs (solute concentration in feed during extraction operation and % extraction). The network employed in the present study uses five input nodes corresponding to the operating variables and two output nodes corresponding to the measurement of the performance of the network (solute concentration in feed during extraction and % extraction). Batch experiments are performed for separation of nickel(II) from aqueous sulphate solution of initial concentration in the 200–100 mg/l ranges. The network employed in the present study uses two hidden layers of optimum number of nodes being thirty and twenty. A leaning rate of 0.3 and momentum factor of 0.4 is used. The model predicted results in good agreement with the experimental data and the average deviations for all the cases are found to be well within ±10%.     

Correlation energy contribution to the ammonia inversion barrier

Diagrammatic many-body double-perturbation theory is used to study the correlation contribution to the inversion barrier in ammonia. With a one-center solution as the zero-order function, the perturbation energy diagrams are shown to be of three types: Hartree-Fock diagrams (geometry dependent), atom-like correlation diagrams (geometry independent) and non-atom-like correlation diagrams (geometry dependent). Only the third class of diagrams enter into the correlation correction to the barrier. These diagrams, which appear first in third order, contribute a small fraction (1%) of the total correlation energy. We estimate from them that the correlation energy contribution to the barrier is small (less than 10% of the total barrier), although the bond length dependence of the correlation correction is such that it is difficult to obtain an exact value for it.     

Effect of plasticizer concentration on the hysteresis,tear strength and stress-relaxation characteristics of black-loaded rubber vulcanizate

The effect of plasticizer concentration on the stress softening, tear strength and stress relaxation of black loaded bromobutyl rubber vulcanizate has been investigated. The stress softening in the rubber vulcanizate, an energy dissipative process at higher strain, may be explained primarily by changes that take place in the rubber phase of the filled vulcanizate. Increased plasticizer concentration leads to decrease in the equilibrium hysteresis. A quantitative relationship between energy density and hysteresis has been derived, which is applicable at and below the elongation at break. Increase in plasticizer concentration results in decrease in the effective diameter of the tip of the tear, which in turn decreases the tear strength. Rate of relaxation decreases with increase in the plasticizer concentration in the carbon-black-filled vulcanizate.     

Interaction of 2-(arylazo)phenols with rhodium. Usual coordination vs. C-H and C-C activation

Reaction of 2-(2′-hydroxyphenylazo)phenol with [Rh(PPh₃)₃Cl] in refluxing benzene in presence of triethylamine afforded a red complex in which the ligand is coordinated to rhodium as a tridentate O,N,O-donor. However, similar reaction of [Rh(PPh₃)₃Cl] with 2-(2′-carboxyphenylazo)-4-methylphenol yielded two complexes, viz. a blue one and a green one. In both the complexes the ligand is coordinated as C,N,O-donor. However, in the blue complex orthometallation takes place from the ortho-carbon atom, which bears -COOH group via decarboxylation and in green one orthometallation occurs from the other ortho-carbon. Structures of all the three complexes were determined by X-ray crystallography. In all the three complexes rhodium is sharing the equatorial plane with the tridentate ligand and a chloride, and the two triphenylphosphines are axially disposed. All of the complexes show intense MLCT transitions in the visible region. Cyclic voltammetry on these complexes shows a Rh(III)-Rh(IV) oxidation on the positive side of SCE and a reduction of the coordinated azophenolate ligand on the negative side.     

Complexometric determination of magnesium in nodular cast iron and alloyed cast iron roll samples

A complexometric method for the determination of magnesium in nodular cast iron, alloyed cast iron and roll samples has been developed. The bulk of the iron is removed by ether extraction and the phosphate as zirconium phosphate. The other elements are removed by extraction with dithiocarbamate into chloroform. Magnesium is then titrated with EDTA at pH 10, with Eriochrome Black T as indicator. Calcium interferes, but is very rarely present in such cast iron samples.     

Dynamical merging of Dirac points in the periodically driven Kitaev honeycomb model

We study the effect of a half wave rectified sinusoidal electromagnetic (EM) wave on the Kitaev honeycomb model with an additional magneto-electric coupling term arising due to induced polarization of the bonds. Within the framework of Floquet analysis, we show that merging of a pair of Dirac points in the gapless region of the Kitaev model leading to a semi-Dirac spectrum is indeed possible by externally varying the amplitude and the phase of the EM field.     

Pentaindenocorannulene: Properties,Assemblies, and C60 Complex

Pentaindenocorannulene (C₅₀H₂₀ , 1 ), a deep bowl polynuclear aromatic hydrocarbon, accepts 4 electrons, crystallizes in columnar bowl‐in‐bowl assemblies and forms a nested C₆₀@ 1 ₂ complex. Spectra, structures and computations are presented.     

Introduction of d‐Glutamate at a Critical Residue of Aβ42 Stabilizes a Prefibrillary Aggregate with Enhanced Toxicity

The amyloid beta peptide 42 (Aβ42) is an aggregation‐prone peptide that plays a pivotal role in Alzheimer′s disease. We report that a subtle perturbation to the peptide through a single chirality change at glutamate 22 leads to a pronounced delay in the β‐sheet adoption of the peptide. This was accompanied by an attenuated propensity of the peptide to form fibrils, which was correlated with changes at the level of the fibrillary architecture. Strikingly, the incorporation of d ‐glutamate was found to stabilize a soluble, ordered macromolecular assembly with enhanced cytotoxicity to PC12 cells, highlighting the importance of advanced prefibrillary Aβ aggregates in neurotoxicity.     

Pentaindenocorannulene: Properties,Assemblies, and C60 Complex

Pentaindenocorannulene (C₅₀H₂₀ , 1 ), a deep bowl polynuclear aromatic hydrocarbon, accepts 4 electrons, crystallizes in columnar bowl‐in‐bowl assemblies and forms a nested C₆₀@ 1 ₂ complex. Spectra, structures and computations are presented.     

Initial Carbon–Carbon Bond Formation during the Early Stages of the Methanol‐to‐Olefin Process Proven by Zeolite‐Trapped Acetate and Methyl Acetate

Methanol‐to‐olefin (MTO) catalysis is a very active field of research because there is a wide variety of sometimes conflicting mechanistic proposals. An example is the ongoing discussion on the initial C?C bond formation from methanol during the induction period of the MTO process. By employing a combination of solid‐state NMR spectroscopy with UV/Vis diffuse reflectance spectroscopy and mass spectrometry on an active H‐SAPO‐34 catalyst, we provide spectroscopic evidence for the formation of surface acetate and methyl acetate, as well as dimethoxymethane during the MTO process. As a consequence, new insights in the formation of the first C?C bond are provided, suggesting a direct mechanism may be operative, at least in the early stages of the MTO reaction.