Inelastic dynamic response of R.C. beam column joints by using B.E.M.

A BEM formulation to obtain the inelastic response of R.C. Beam-Column joints subjected to sinusoidal loading along the boundary is presented. The equations of motion are written along with kinematical and constitutive equations. The dynamic reciprocal theorem is presented and the temporal dependence is removed by assuming steady state response.

Primary structure of sesbania mosaic virus coat protein: its implications to the assembly and architecture of the virus

Sesbania mosaic virus (SMV) is a plant virus that infects Sesbania grandiflora plants in Andhra Pradesh, India. The amino acid sequence of the coat protein of SMV was determined using purified peptides generated by cleavage with trypsin, chymotrypsin, V8 protease and clostripain. The 230 residues so far determined were compared to the corresponding residues of southern bean mosaic virus (SBMV), the type member of sobemoviruses. The overall identity between the sequences is 61.7%. The amino terminal 64 residues, which constitute an independent domain (R-domain) known to interact with RNA, are conserved to a lower extent (52.5%). Comparison of the positively charged residues in this domain suggests that the RNA-protein interactions are considerably weaker in SMV. The residues that constitute the major domain of the coat protein, the surface domain (S-domain, residues 65-260), are better conserved (66.5%). The positively charged residues of this domain that face the nucleic acid are well conserved. The longest conserved stretch of residues (131-142) corresponds to the loop involved in intersubunit interactions between subunits related by the quasi 3-fold symmetry. A unique cation binding site located on the quasi 3-fold axis contributes to the stability of SMV. These differences are reflected in the increased stability of the SMV coat protein and its ability to be reconstituted with RNA at pH 7.5. A major epitope was identified using monoclonal antibodies to SMV in the segment 201-223 which contains an exposed helix in the capsid structure. This region is highly conserved between SMV and SBMV (70%) suggesting that it could represent the site of an important function such as vector recognition.

Catalytic current polarographic determination of traces of titanium in water after preconcentration by coflotation

A new method is reported for the determination of trace levels of Ti(IV) in water by coflotation and polargraphy. Ti(IV) is preconcentrated and separated by coflotation using aluminium hydroxide as coprecipitant and sodium oleate as surfactant. Polarographic determination of titanium content in the froth is based on the catalytic wave of Ti(IV) in the presence of chlorate and oxalate. The effect of various cations and anions on the flotation and determination of titanium has been investigated. The method has been applied to estimation of titanium in natural fresh water samples.

Reduction of electric are furnace slags in stainless steelmaking - Part 1 Observations

Simultaneous reduction of iron and chromium oxides from synthetic electric are furnace stainless steelmaking slag in a graphite crucible has been studied. Above the melting point of iron the reduction of iron oxide leads to a carbon saturated Fe-C melt, but below the melting point of iron initially solid iron or iron carbide forms on the crucible surface. Only when a certain number of Fe-C droplets are formed does the reduction of chromium oxide start to form an Fe-Cr-C alloy. The reaction proceeds with pronounced foaming which depends on the basicity, temperature, and iron oxide content of the slag. IS/1352a (C) 1998 The Institute of Materials.

A C-H center dot center dot center dot O hydrogen bond stabilized polypeptide chain reversal motif at the C terminus of helices in proteins

The serendipitous observation of a C-H...O hydrogen bond mediated polypeptide chain reversal in synthetic peptide helices has led to a search for the occurrence of a similar motif in protein structures. From a dataset of 634 proteins, 1304 helices terminating in a Schellman motif have been examined. The C-H...O interaction between the T - 4 (CH)-H-alpha and T + 1 C=O group (C...O 3.5 Angstrom) becomes possible only when the T + 1 residue adopts an extended beta conformation (T is defined as the helix terminating residue adopting an alpha(L) conformation). In all, 111 examples of this chain reversal motif have been identified and the compositional and conformational. preferences at positions T - 4, T, and T + 1 determined. A marked preference for residues like Set, Glu and Gln is observed at T - 4 position with the motif being further stabilized by the formation of a side-chain-backbone O...H-N hydrogen bond involving the side-chain of residue T - 4 and the N-H group of residue T + 3. In as many as 57 examples, the segment following the helix was extended with three to four successive residues in beta conformation. In a majority of these cases, the succeeding beta strand lies approximately antiparallel with the helix, suggesting that the backbone C-H...O interactions may provide a means of registering helices and strands in an antiparallel orientation. Two examples were identified in which extended registry was detected with two sets of C-H...O hydrogen bonds between (T - 4) (CH)-H-alpha...C=O (T + 1) and (T - 8) (CH)-H-alpha...C=O (T + 3). 0 2002 Published by Elsevier Science Ltd.

Variable temperature x-ray crystal structure analysis of a type I langbeinite: Rb2Cd2(SO4)(3)

The structure of a type I langbeinite, Rb2Cd2(SO4)(3), displays three different phases, cubic with a = 10.378(5) Angstrom (space group P2(1)3) at room temperature, monoclinic at 120 K with a = 10.328(3), b = 10.322(3), c = 10.325(3) Angstrom, beta = 89.975(1)degrees (space group P2(1)), and orthorhombic at 85 K with a = 10.319(2), b = 10.321(2), c = 10.320(2) Angstrom (space group P2(1)2(1)2(1)), respectively. Precise single-crystal analyses of these phases indicate that Rb2Cd2(SO4)(3) distorts initially from cubic to monoclinic upon cooling followed by a significant reorientation of the SO4 tetrahedra, resulting in an orthorhombic symmetry upon further cooling. The three structures have been established unequivocally using the same crystal. There is no indication of the formation of an intermediate triclinic phase or any lattice disorder as conjectured in several earlier reports on compounds belonging to the type I langbeinite. The bond valence sum analyses of the coordination around the Rb sites indicate asymmetry in the bond strengths which could be the driving force of the ferroelectric behavior in these materials.

Measurement of Heat Transfer Rate on Backward-Facing Steps at Hypersonic Mach Number

Two backward-facing models with step heights of 2 and 3 mm are used to measure the convective surface heat transfer rates by using platinum thin-film gauges, deposited on Macor inserts. Heat transfer rates have been theoretically calculated along the flat plate portion of a model using the Eckert reference temperature method. The experimentally determined surface heat transfer rate distributions are compared with theoretical and numerical estimations. Experimental heat flux distribution over a flat plate model showed good agreement with the reference temperature method at stagnation enthalpy range of 0.8-2 MJ/kg. Theoretical analysis has been used for downstream of a backward-facing step using Gai's nondimensional analysis. It has been found from the present study that approximately 10 and 8 step heights are required for the flow to reattach for 2 and 3 mm step height backward-facing step models, respectively, at a nominal Mach number of 7.6.

Self-assembly of Ru-4 and Ru-8 assemblies by coordination using organometallic Ru(II)(2) precursors: Synthesis, characterization and properties

Coordination-driven self-assembly of binuclear half-sandwich p-cymene ruthenium(II) complexes [Ru-2(mu-eta(4)-C2O4)(MeOH)(2)(eta(6)-p-cymene)(2)](O3SCF3)(2) (1a) or [Ru-2(mu-eta(4)-N,N'-diphenyloxamidato)(MeOH)(2)(eta(6)-p-cymene)(2)]( O3SCF3)(2) (1b) separately with an imidazole-based tetratopic donor L in methanol affords two tetranuclear metallamacrocycles 2a and 2b, respectively. Conversely, the similar combination of L with 2,5-dihydroxy-1,4-benzoquinonato (dhbq) bridged binuclear complex [Ru-2(mu-eta(C6H2O4)-C-4)(MeOH)(2)(eta(6)-p-cymene)(2)](O3SCF3)(2) (1c) in 1:2 molar ratio resulted in an octanuclear macrocyclic cage 2c. All the self-assembled macrocycles 2a-2c were isolated as their triflate salts in high yields and were characterized fully by multinuclear (H-1, C-13 and F-19) NMR, infrared (IR) and electrospray ionization mass spectrometry (ESIMS). In addition, the molecular structure of macrocycle 2a was established unequivocally by single-crystal X-ray diffraction analysis and adopts a tetranuclear rectangular geometry with the dimensions of 5.53 angstrom x 12.39 angstrom. Furthermore, the photo-and electrochemical properties of these newly synthesized assemblies have been studied by using UV-vis absorption and cyclic voltammetry analysis.

Novel tetranuclear distorted open-cubane copper complex containing oximate bridges: Synthesis, crystal structure, DNA binding and cleavage activity

The synthesis, molecular structure, DNA binding and nuclease activity of Cu4O4 open-cubane tetranuclear copper(II) complex with 3-2-(ethyl amino)ethyl]imino]-2-butanoneoxime (HL) are reported for the first time. The neutral tetranuclear Cu4L4(ClO4)(4)] complex crystallizes in tetragonal space group P (4) over bar2(1)c with the unit cell parameters; a = 13.798(4) angstrom, b = 13.798(4) angstrom, c = 14.119(6) angstrom, V = 2688(16) angstrom(3), Z = 8, R = 0.0636. Symmetrically equivalent copper atoms exhibit a CuN3O3 elongated distorted octahedral coordination environment, with three nitrogen atoms of the L ligand and one oxime-oxygen atom of second L ligand at equatorial positions, one oxime-oxygen atom of the third L ligand and perchlorate oxygen at axial positions. The complex shows quasireversible cyclic voltammetric response at 0.805 V (Delta E-p = 277 mV) at 100 mV s (1) in DMF for the Cu(II)/Cu(I) redox couple. The binding study of the complex with calf-thymus DNA has been investigated using absorption spectrophotometry. The complex shows strong nuclease activity on stranded pBR 322 plasmid DNA in the presence of hydrogen peroxide and marginal nuclease activity in the presence of reducing agent (dithiothreitol). (C) 2012 Elsevier B. V. All rights reserved.

Non-covalent functionalization using lithographically patterned polyelectrolyte multilayers for high-density microarrays

We describe a method to fabricate high-density biological microarrays using lithographic patterning of polyelectrolyte multi layers formed by spin assisted electrostatic layer-by-layer assembly. Proteins or DNA can be immobilized on the polyelectrolyte patterns via electrostatic attachment leading to functional microarrays. As the immobilization is done using electrostatically assembled polyelectrolyte anchor, this process is substrate independent and is fully compatible with a standard semiconductor fabrication process flow. Moreover, the electrostatic assembly of the anchor layer is a fast process with reaction saturation times of the order of a few minutes unlike covalent schemes that typically require hours to reach saturation. The substrate independent nature of this technique is demonstrated by functionalizing glass slides as well as regular transparency sheets using the same procedure. Using a model protein assay, we demonstrate that the non-covalent immobilization scheme described here has competitive performance compared to conventional covalent immobilization schemes described in literature. (C) 2012 Elsevier B.V. All rights reserved.