Exponential stability of a network of elastic and thermoelastic materials

In this paper, we study the stability of a network of some elastic and thermoelastic edges. We establish the exponential decay rate of the whole system. Copyright © 2012 John Wiley & Sons, Ltd.     

Local Near-Beltrami Structure and Depletion of the Nonlinearity in the 3D Navier–Stokes Flows

Journal of Nonlinear Science - Computational simulations of turbulent flows indicate that the regions of low dissipation/enstrophy production feature high degree of local alignment between the...     

Corticonic models of brain mechanisms underlying cognition and intelligence

The concern of this review is brain theory or more specifically, in its first part, a model of the cerebral cortex and the way it: (a) interacts with subcortical regions like the thalamus and the hippocampus to provide higher-level-brain functions that underlie cognition and intelligence, (b) handles and represents dynamical sensory patterns imposed by a constantly changing environment, (c) copes with the enormous number of such patterns encountered in a lifetime by means of dynamic memory that offers an immense number of stimulus-specific attractors for input patterns (stimuli) to select from, (d) selects an attractor through a process of “conjugation” of the input pattern with the dynamics of the thalamo–cortical loop, (e) distinguishes between redundant (structured) and non-redundant (random) inputs that are void of information, (f) can do categorical perception when there is access to vast associative memory laid out in the association cortex with the help of the hippocampus, and (g) makes use of “computation” at the edge of chaos and information driven annealing to achieve all this. Other features and implications of the concepts presented for the design of computational algorithms and machines with brain-like intelligence are also discussed. The material and results presented suggest, that a Parametrically Coupled Logistic Map network (PCLMN) is a minimal model of the thalamo–cortical complex and that marrying such a network to a suitable associative memory with re-entry or feedback forms a useful, albeit, abstract model of a cortical module of the brain that could facilitate building a simple artificial brain.

In the second part of the review, the results of numerical simulations and drawn conclusions in the first part are linked to the most directly relevant works and views of other workers. What emerges is a picture of brain dynamics on the mesoscopic and macroscopic scales that gives a glimpse of the nature of the long sought after brain code underlying intelligence and other higher level brain functions.     

Isolation of quercetin and mandelic acid from <Emphasis Type="Italic">Aesculus indica</Emphasis> fruit and their biological activities

Background

In this study Aesculus indica fruit was subjected to isolation of phytochemicals. Two antioxidants quercetin and Mandelic acid were isolated in pure state. The free radical scavenging and acetyl choline esterase inhibitory potential of the crude extract and sub fractions were also determined.

Results

The antioxidant capacity of crude extract, fractions and isolated compounds were determined by DPPH and ABTS methods. Folin-Ciocalteu reagent method was used to estimate the total phenolic contents and were found to be 78.34?±?0.96, 44.16?±?1.05, 65.45?±?1.29, 37.85?±?1.44 and 50.23?±?2.431 (mg/g of gallic acid) in crude extract, ethyl acetate, chloroform, n-hexane and aqueous fractions respectively. The flavonoid concentration in crude extract, ethyl acetate, chloroform, n-hexane and aqueous fraction were; 85.30?±?1.20, 53.80?±?1.07, 77.50?±?1.12, 26.30?±?1.35 and 37.78?±?1.25 (mg/g of quercetin) respectively. The chloroform fraction was more potent against enzymes, acetyl choline esterase and butyryl choline esterase (IC₅₀?=?85 and 160 μg/ml respectively). The phenolic compounds in the crude extract and fractions were determined using HPLC standard method. Chlorogenic acid, quercetin, phloroglucinol, rutin, mandelic acid and hydroxy benzoic acid were detected at retention times 6.005, 10.062, 22.623, 30.597, 35.490 and 36.211 in crude extract and different fractions. The ethyl acetate fraction was rich in the targeted compounds and was therefore subjected to column isolation. The HPLC chromatogram of isolated compounds showed single peak at specified retention times which confirms their isolation in pure state. The isolated compounds were then characterized by FTIR and NMR spectrophotometric techniques.

Conclusion

The Aesculus indica fruit extracts showed antioxidant and anticholine esterase inhibitory potentials. Two bioactive compounds were isolated in the pure form ethyl acetate fraction. From results it was concluded that the fruit of this plant could be used to minimize oxidative stress caused by reactive oxygen species.

     

Recent trends in electrochemical detection of phosphate in actual waters

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Ab initio calculations of the ground and excited states of the ZrN molecule including spin‐orbit effects

The electronic structures with spin‐orbit effects of the zirconium nitride ZrN molecule are investigated by the methods of multireference single and double configuration interaction. The potential energy curves are calculated along with the spectroscopic constants for the lowest‐lying 34 spin‐orbit states Ω in ZrN. A good agreement is displayed by comparing the calculated spectroscopic constants with those available experimentally. The permanent dipole moments are calculated along with the vibrational energies. New results are obtained in this work for 29 spin‐orbit states and their spectroscopic constants calculated. © 2015 Wiley Periodicals, Inc.