Convergence under dynamical thresholds with delays

Necessary and sufficient conditions are obtained for the existence of a globally asymptotically stable equilibrium of a class of delay differential equations modeling the action of a neuron with dynamical threshold effects.     

Oscillatory and asymptotic behaviour of a multiplicative delay logistic equation

Sufficient conditions are obtained for the oscillation of all positive solutions of about the positive equilibrium K and for the global attractivity of the positive equilibrium     

Hydrogen storage capacity of alkali and alkaline earth metal ions doped carbon based materials: A DFT study

The hydrogen storage (H-storage) capacity of alkali (Li⁺, Na⁺ and K⁺) and alkaline earth metal ion (Mg²⁺ and Ca²⁺) doped cubane, cyclohexane and adamantane has been investigated using Density Functional Theory (DFT) based M05-2X functional employing 6-31+G∗∗ basis set. The adsorption of number of H₂ molecules on the metal ion doped complexes depends on ionic radii and charge of the metal ions. Among the 15 complexes investigated in this study, Mg²⁺ ion doped cubane, cyclohexane and adamantane complexes have higher H-storage capacity when compared to other complexes. The calculated binding energy (BE) of 5H₂@Cub-Mg²⁺ complex is 46.85 kcal/mol with binding energy per H₂ molecule (BE/nH₂) of 9.37 kcal/mol. The corresponding gravimetric density of the complexes is 7.3 wt%. In the case of 4H₂@Cyc-Mg²⁺ complex, the BE is 32.19 kcal/mol (BE/nH₂ is 8.05 kcal/mol with 6.9 wt% in gravimetric density). The Adm-Mg²⁺ complexes adsorb 4H₂ molecules with BE of 33.33 kcal/mol, the BE of per H₂ molecule is 8.33 kcal/mol. The corresponding gravimetric density of the complex is around 4.8 wt%, respectively. A new linker modified MOP-9 has been constructed based on the results and their H-storage capacity has also estimated.     

Delay-independent stability in bidirectional associative memorynetworks

It is shown that if the neuronal gains are small compared with the synaptic connection weights, then a bidirectional associative memory network with axonal signal transmission delays converges to the equilibria associated with exogenous inputs to the network. Both discrete and continuously distributed delays are considered; the asymptotic stability is global in the state space of neuronal activations and also is independent of the delays.     

Density functional studies on the hydrogen storage capacity of boranes and alanes based cages

The hydrogen storage (H-storage) capacity of various boranes and alanes have been investigated using density functional theory (DFT) based M05-2X method employing 6–31+G** basis set. The changes in the H-storage capacities of borane and alane upon substitution of antipodal atoms in the cages by C, Si, and N have also been investigated. It is found from the calculations that a maximum of 20 H₂ molecules can be adsorbed on the deltahedron faces of these cages. The maximum gravimetric density has been observed for boranes when compared to alanes. The H-storage capacity of closo-borane dianion [B₁₂H₁₂]²⁻, monocarborane [CB₁₁H₁₂]¹⁻, dicarborane [C₂B₁₀H₁₂], and closo-azaborane [NB₁₁H₁₂] cages is almost similar (∼22 wt.%). Among these cages, B_BB dianion show higher binding energy (BE) and BE per H₂ molecule (BE/nH₂) which are 181.06 and 9.03 kJ/mol, respectively. In the case of alanes, dicarbalane [C₂Al₁₀H₁₂] has maximum H-storage capacity of 11.6 wt.%. Based on these findings, a new MOF with carborane (MOF-5_CC) as linker has been designed. The calculation on the new MOF-5B_CC reveals that it has H-storage capacity of 6.4 wt.% with BE/nH₂ of 3.02 kJ/mol.     

Investigations on hard machining of Impax Hi Hard tool steel

In this paper, experimental investigations are carried out by end milling process on hardened tool steel, Impax Hi Hard (Hardness 55 HRC) a newly developed tool steel material used by tool and die making industries. Experiments are performed with an aim to study performance investigations of machining parameters such as cutting speed, feed, depth of cut and width of cut with consideration of multiple responses viz. volume of material removed, tool wear, tool life and surface finish to evaluate the performance of PVD coated carbide inserts and ball end mill cutters. It has been observed through scanning electron microscope, X-ray diffraction technique (EDX) that chipping and adhesion are active tool wear mechanisms and saw-toothed chips are formed while machining of Impax Hi Hard steel. It is also noticed out that tool life is not enhanced while machining with minimum quantity lubricant than dry machining. From the investigations, it is observed that hard machining can be considered as an alternative to grinding and EDM, traditional methods of machining difficult-to-machine materials i.e. hardened steel with hardness greater than 50 HRC with a scope of improved productivity, increased flexibility, decreased capital expenses and reduced environmental waste.     

RNA‐Templated Concatenation of Triplet Nucleic‐Acid Probe

Template‐directed synthesis offers several distinct benefits over conventional laboratory creation, including unsurpassed reaction rate and selectivity. Although it is central to many biological processes, such an approach has rarely been applied to the in situ synthesis and recognition of biomedically relevant target. Towards this goal, we report the development of a three‐codon nucleic‐acid probe containing a C‐terminal thioester group and an N‐terminal cysteine that is capable of undergoing template‐directed oligomerization in the presence of an RNA target and self‐deactivation in its absence. The work has implications for the development of millamolecular nucleic‐acid probes for targeting RNA‐repeated expansions associated with myotonic dystrophy type 1 and other related neuromuscular and neurodegenerative disorders.     

Time delays and stimulus-dependent pattern formation in periodicenvironments in isolated neurons

The dynamical characteristics of a single isolated Hopfield-type neuron with dissipation and time-delayed self-interaction under periodic stimuli are studied. Sufficient conditions for the heteroassociative stable encoding of periodic external stimuli are obtained. Both discrete and continuously distributed delays are included.