Dielectric relaxation phenomena of rigid polar liquid molecules under giga hertz electric field

The dielectric relaxation phenomena of rigid polar liquid molecules chloral and ethyltrichloroacetate (j) in benzene, n-hexane and n-heptane (i) under 4.2, 9.8 and 24.6 GHz electric fields at 30°C are studied to show the possible existence of double relaxation times τ ₂ and τ ₁ for rotations of the whole and the flexible parts of molecules. The probability of showing double relaxation is more in aliphatic solvents indicating their nonrigidity. The symmetric and asymmetric distribution parameters γ and δ are obtained from X _ij ^′ /X _0ij and X _ij ^″ /X _0ij and w _j →0 where X _ij ^′ and X _ij ^″ are real and imaginary parts of the complex orientational susceptibility X _i ^* and X _0ij is the low frequency susceptibility which is real. X _ij ’s are involved with the measured dielectric relative permittivities ε _ij ^′ , ε _in ^″ , ε _0ij and ε _∞ij of solutions. The theoretical weighted contributions c ₁ and c ₂ towards dielectric dispersions by Fröhlich’s method are compared with the experimental ones obtained from the graphical variation of X _ij ^′ /X _0ij and X _ij ^″ /X _0ij with weight fractions w _j ’s at w _j → 0. The measured dipole moments μ ₂ and μ ₁ of the whole and the flexible part of a polar molecule in terms of the linear coefficients β’s of X _ij ^′ ’s with w _j ’s and the estimated τ ₂ and τ ₁ reveal their associations with aliphatic solvents. The theoretical dipole moments μ _theo’s from the available bond angles and bond moments of the substituent polar groups of the molecules with the estimated μ’s suggest the mesomeric, inductive and electromeric effects in them under GHz electric field.     

A highly potent and selective PKCalpha inhibitor generated via combinatorial modification of a peptide scaffold

A potent and highly selective inhibitor of protein kinase C alpha has been generated via the combinatorial modification of a consensus sequence peptide. The inhibitor displays a Ki of 800 pM versus variable peptide substrate and good selectivity versus other members of the PKC family, including PKCbeta (385-fold), PKCgamma (580-fold), PKCdelta (2730-fold), PKCepsilon (600-fold), PKCeta (1310-fold), PKCtheta (1210-fold), PKCiota (940-fold), and PKCzeta (640-fold). The parallel synthesis strategy employed is easily automated and straightforward to implement.     

Benzofuran-derived cyclic beta-amino acid scaffold for building a diverse set of flavonoid-like probes and the discovery of a cell motility inhibitor

We report here a practical, enantioselective synthesis of benzofuran-derived, cyclic trans-beta-amino acid scaffold. In two cases, tricyclic derivatives having six- and eight-membered unsaturated lactams were obtained from this versatile scaffold. To explore the biological applications, these compounds were subjected to cell-based assays, using NIH3T3 mouse cells to examine their potency as cell motility inhibitors and identified 18 as a potent cell motility inhibitor (IC50 approximately 40 microM in chamber cell migration assay).     

Controlled trapping of single particle states on a periodic substrate by deterministic stubbing

A periodic array of atomic sites, described within a tight binding formalism is shown to be capable of trapping electronic states as it grows in size and gets stubbed by an ‘atom’ or an ‘atomic’ clusters from a side in a deterministic way. We prescribe a method based on a real space renormalization group method, that unravels a subtle correlation between the positions of the side coupled atoms and the energy eigenvalues for which the incoming particle finally gets trapped. We discuss how, in such conditions, the periodic backbone gets transformed into an array of infinite quantum wells in the thermodynamic limit. We present a case here, where the wells have a hierarchically distribution of widths, hosting standing wave solutions in the thermodynamic limit.     

String theory in five dimensional cosmological models

A study on string theory has been done in five dimensional flat space-time. Barotropic equation of state andp-string model are discussed. Also a polynomial relation between the two scale factors is assumed. In some special cases the solution reduces to generalized Kasner metric. Further diminision of extra dimension with the evolution of universe is exhibited. A detailed study of phase-space analysis is done for geometric string model.     

Forced thickness vibrations of a thermopiezoelectric layer of monoclinic symmetry

In the present paper, the generalized dynamical theory of thermoelasticity is employed to study the thickness vibrations of a thermopiezoelectric layer of monoclinic symmetry. The vibrations in the layer are generated owing to the application of an alternating potential and temperature difference to the faces of the layer which are assumed to be coated with infinitesimally thin electrodes. Variations of the piezoelectric potential, particle displacement and temperature with the distance along the thickness direction have been determined.I am grateful to Dr. A. K. Pal of Jadavpur University for his kind help in the preparation of this paper. I am also thankful to the referee for his valuable comments in improving the paper.     

New modifications in 15 UD pelletron at nuclear science centre

The 15 UD pelletron at NSC has been operational and performed well during the last 11 years. There have been major modifications performed for upgradation of pelletron system over this period. Major upgradations which have been implemented are new resistor network system for voltage gradient, doublet to singlet unit conversion for accelerator units, turbopump based gas stripper system etc. In addition accelerator mass spectroscopy program has also been started. A new multi-cathode source, Wien filter etc. have been procured and will be added soon in the system. An overview of the most significant upgradations undertaken and other activities for the system are being reported in the present paper.     

Outerplanar and Planar Oriented Cliques

The clique number of an undirected graph G is the maximum order of a complete subgraph of G and is a well‐known lower bound for the chromatic number of G. Every proper k‐coloring of G may be viewed as a homomorphism (an edge‐preserving vertex mapping) of G to the complete graph of order k. By considering homomorphisms of oriented graphs (digraphs without cycles of length at most 2), we get a natural notion of (oriented) colorings and oriented chromatic number of oriented graphs. An oriented clique is then an oriented graph whose number of vertices and oriented chromatic number coincide. However, the structure of oriented cliques is much less understood than in the undirected case. In this article, we study the structure of outerplanar and planar oriented cliques. We first provide a list of 11 graphs and prove that an outerplanar graph can be oriented as an oriented clique if and only if it contains one of these graphs as a spanning subgraph. Klostermeyer and MacGillivray conjectured that the order of a planar oriented clique is at most 15, which was later proved by Sen. We show that any planar oriented clique on 15 vertices must contain a particular oriented graph as a spanning subgraph, thus reproving the above conjecture. We also provide tight upper bounds for the order of planar oriented cliques of girth k for all .     

Provably secure dynamic identity-based three-factor password authentication scheme using extended chaotic maps

With the aim of guaranteeing secure communication through public networks, three-factor password authentication (TF-PWA) scheme plays a key role in many internet applications. Since in TF-PWA scheme, the communicating entities can mutually authenticate each other and generate a shared session key, which will be used for secure exchange of messages in succeeding communication among them. As a result, the TF-PWA schemes gain enormous consideration in recent years. More recently, due to light-weight features of the extended chaotic map, it is also extensively applied in designing of public key encryption, key agreement, image encryption, S-box, hash function, digital signature, password authentication, etc. The aim of this paper was to design a dynamic identity-based three-factor password authentication scheme using extended chaotic map (ECM-TF-PWA) in the random oracle model. The proposed scheme is provably secure based on the intractability assumption of chaotic map-based Diffie–Hellman problem. The informal security analysis gives the evidence that our scheme protects all attacks and provides functionality attributes that are needed in a three-factor authentication system. Besides, the performance discussion shows that our scheme performs better than others in respect of computation and communication cost.