Approximating geometric bottleneck shortest paths

In a geometric bottleneck shortest path problem, we are given a set S of n points in the plane, and want to answer queries of the following type: given two points p and q of S and a real number L, compute (or approximate) a shortest path between p and q in the subgraph of the complete graph on S consisting of all edges whose lengths are less than or equal to L. We present efficient algorithms for answering several query problems of this type. Our solutions are based on Euclidean minimum spanning trees, spanners, and the Delaunay triangulation. A result of independent interest is the following. For any two points p and q of S, there is a path between p and q in the Delaunay triangulation, whose length is less than or equal to 2π/(3cos(π/6)) times the Euclidean distance |pq| between p and q, and all of whose edges have length at most |pq|.     

A planar model for interacting fermions

One-particle Green function in the paramagnetic phase of a model of interacting fermions is obtained in the planar approximation. The model is zero-dimensional, in that thermal fluctuations are the only source of kinetic energy.     

On the representation of the interaction energy between two polar molecules

Summary An attempt has been made to represent the interaction energy between two polar molecules by using an effective relative orientation of the pair of the colliding molecules. Calculations made for gaseous ammonia show fairly satisfactory results.     

New flavonoid glycosides and other chemical constituents from Clerodendrum phlomidis leaves: isolation and characterisation

Phytochemical investigation of the plant Clerodendrum phlomidis Linn. F. (Lamiaceae) has now led to the isolation of two new flavonoid glycosides (1, 2) together with six known compounds identified as pectolinaringenin (3), pectolinaringenin-7-O-β-d-glucopyranoside (4), 24β-ethylcholesta-5,22E,25-triene-3β-ol (5), 24β-ethylcholesta-5,22E,25-triene-3β-O-β-D-glucopyranoside (6), (2S,3S,4R,10E)-2-[(2′R)-2′-hydroxytetracosanoylamino]-10-octadecene-1,3,4-triol (7) and andrographolide (8) mainly by spectroscopic analysis. Compounds 4 and 6–8 are reported for the first time from C. phlomidis.     

Origins of the Intermediate Spectral Form in M100 Mutants of Photoactive Yellow Protein

Numerous single‐site mutants of photoactive yellow protein (PYP) from Halorhodospira halophila and as well as PYP homologs from other species exhibit a shoulder on the short wavelength side of the absorbance maximum in their dark‐adapted states. The structural basis for the occurrence of this shoulder, called the “intermediate spectral form,” has only been investigated in detail for the Y42F mutation. Here we explore the structural basis for occurrence of the intermediate spectral form in a M121E derivative of a circularly permuted H. halophila PYP (M121E‐cPYP). The M121 site in M121E‐cPYP corresponds to the M100 site in wild‐type H. halophila PYP. High‐resolution NMR measurements with a salt‐tolerant cryoprobe enabled identification of those residues directly affected by increasing concentrations of ammonium chloride, a salt that greatly enhances the fraction of the intermediate spectra form. Residues in the surface loop containing the M121E (M100E) mutation were found to be affected by ammonium chloride as well as a discrete set of residues that link this surface loop to the buried hydroxyl group of the chromophore via a hydrogen bond network. Localized changes in the conformational dynamics of a surface loop can thereby produce structural rearrangements near the buried hydroxyl group chromophore while leaving the large majority of residues in the protein unaffected.     

Synthesis and antimicrobial activity of some novel benzofuran based 1,2,3-triazoles

In the present study, a series of novel {6-[(1H-1,2,3-triazol-4-yl)methoxy]-3-methylbenzofuran-2-yl}(phenyl)methanones (7a–7o) have been synthesized using click chemistry approach. The structures of all newly synthesized compounds were characterized by FT-IR, ¹H and ¹³C NMR, and MASS spectral data. Most of products demonstrated high antimicrobial activity.

     

Force–displacement relationship in micro-metric pantographs: Experiments and numerical simulations

In this paper, we reveal that the mathematical discrete model of Hencky type, introduced in [1], is appropriate for describing the mechanical behavior of micro-metric pantographic elementary modules. This behavior does not differ remarkably from what has been observed for milli-metric modules, as we prove with suitably designed experiments. Therefore, we conclude that the concept of pantographic microstructure seems feasible for micro-metrically architected microstructured (meta)materials as well. These results are particularly indicative of the possibility of fabricating materials that can have an underlying pantographic microstructure at micrometric scale, so that its unique behavior can be exploited in a larger range of technological applications.     

A numerical study of natural convection from a localized heat source in the lower plenum of a fast breeder reactor under failed conditions

A comprehensive numerical study has been done to investigate two-dimensional, steady state, conjugate natural heat convection in the hemi spherical lower plenum of a fast breeder reactor under failed conditions. The continuity, momentum and energy equations are solved over the entire domain, using the corresponding properties for the solid and fluid regions. The control volume approach is employed in order to discretize the governing equations for their numerical solution. A parametric study has been done to study the variation of the velocity vectors and isotherms for different constant temperature of the heat source, simulating different heat generation rates. The actual problem in a nuclear reactor involves a volumetric heat generation in the debris falling over the heat shield plate under failed conditions of the reactor and heat is removed by a decay heat exchanger serving as a sink. In this study we have reduced this transient problem to a quasi-steady problem with a prescribed temperature on the heat shield plate. This makes the problem more tractable. The fluid flow pattern, variation of the temperature along the axis in and around the heat source are presented to show the overall heat transfer characteristics inside the plenum.