Design expressions for the in-plane shear capacity of confined masonry shear walls containing squat panels

In-plane shear capacity formulation of reinforced masonry is commonly conceived as the sum of the capacities of three parameters, viz, the masonry, the reinforcement, and the precompression. The term “masonry” incorporates the aspect ratio of the wall without any regard to the aspect ratio of the panels inscribed (and hence confined) by the vertical and the horizontal reinforced grout cores. This paper proposes design expressions in which the aspect ratio of such panels is explicitly included. For this purpose, the grouted confining cores are regarded as a grid of confining elements within which the panels are positioned. These confined masonry panels are then considered as building blocks for multi-bay, multi-storied confined masonry shear walls and analyzed using an experimentally validated macroscopic finite-element model. Results of the analyzes of 161 confined masonry walls containing panels of height to length ratio less than 1.0 have been regressed to formulate design expressions. These expressions have been first validated using independent test data sets and then compared with the existing equations in some selected international design standards. The concept of including the unreinforced masonry panel aspect ratio as an additional term in the design expression for partially grouted/confined masonry shear walls is recommended based on the conclusions from this paper.

A New Class Of Photo-Cross-Linkable Side-Chain Liquid Crystalline Polymers Containing Bis(Benzylidene)Cyclohexanone Units

This paper reports a new class of photo-cross-linkable side chain liquid crystalline polymers (PSCLCPs) based on the bis(benzylidene)cyclohexanone unit, which functions as both a mesogen and a photoactive center. Polymers with the bis(benzylidene)cyclohexanone unit and varying spacer length have been synthesized. Copolymers of bis(benzylidene)cyclohexanone containing monomer and cholesterol benzoate containing monomer with different compositions have also been prepared. All these polymers have been structurally characterized by spectroscopic techniques. Thermal transitions were studied by DSC, and mesophases were identified by polarized light optical microscopy (POM). The intermediate compounds OH-x, the monomers SCLCM-x, and the corresponding polymers PSCLCP-x, which are essentially based on bis(benzylidene)cyclohexanone, all show a nematic mesophase. Transition temperatures were observed to decrease with increasing spacer length. The copolymers with varying compositions exhibit a cholesteric mesophase, and the transition temperatures increase with the cholesteric benzoate units in the copolymer. Photolysis of the low molecular weight liquid crystalline bis(benzylidene)-cyclohexanone compound reveals that there are two kinds of photoreactions in these systems: the EZ photoisomerization and 2 pi + 2 pi addition. The EZ photoisomerization in the LC phase disrupts the parallel stacking of the mesogens, resulting in the transition from the LC phase to the isotropic phase. The photoreaction involving the 2 pi + 2 pi addition of the bis(benzylidene)cyclohexanone units in the polymer results in the cross-linking of the chains. The liquid crystalline induced circular dichroism (LCICD) studies of the cholesterol benzoate copolymers revealed that the cholesteric supramolecular order remains even after the photo-cross-linking.

An asymmetric homodinuclear complex containing the mu-x-oxobis(mu-x-carboxylato)diruthenium(III) core: X-ray structure of [Ru20(o2ec6H4-p-OMe)3(en) (PPh3)2] (C104)" 3CHC13

Asymmetric tri-bridged diruthenium(III) complexes, [Ru2O(O(2)CR)(3)(en) (PPh(3))(2)](ClO4) (R = C6H4-p-X: X = OMe (1a), Me (1b); en=1,2-diaminoethane), were prepared and structurally characterized. Complex 1a 3CHCl(3), crystallizes in the triclinic space group P (1) over bar with a = 14.029(5), b = 14.205(5), c = 20.610(6) Angstrom, alpha= 107.26(3), beta = 101.84(3), gamma= 97.57(3)degrees, V= 3756(2) Angstrom(3) and Z = 2. The complex has an {Ru-2(mu-O)(mu-O(2)CR)(2)(2+)} core and exhibits [O4PRu(mu-O)RuPO2N2](+) coordination environments for the metal centers. The novel structural feature is the asymmetric arrangement of ligands at the terminal sites of the core which shows an Ru... Ru separation of 3.226(3) Angstrom and an Ru-O-Ru angle of 119.2(5)degrees. An intense visible band observed near 570 nm is assigned to a charge transfer transition involving the d pi-Ru(III) and p pi-mu-O Orbitals. Cyclic voltammetry of the complexes displays a reversible Ru-2(III,III) reversible arrow Ru-2(III,IV) couple near 0.8 V (versus SCE) in MeCN-0.1 M TBAP.

Synthesis of macrocyclic diacyl/dialkyl glycerols containing disulfide tether and studies of their effects upon incorporation in DPPC membranes. Implications in the design of phospholipase A(2) modulators

A general method for the preparation of novel disulfide-tethered macrocyclic diacylglycerols (DAGs) has been described. Overall synthesis involved stepwise protection, acylation, and deprotection to yield the bis(omega-bromoacyl) glycerols. In the crucial macrocyclization step, a unique reagent, benzyltriethylammonium tetrathiomolybdate (BTAT), has been used to convert individual bis(omega-bromoacyl) glycerols to their respective macrocyclic disulfides. DAG 6, which had ether linkages between hydrocarbon chains and the glycerol backbone, was also synthesized from an appropriate precursor using a similar protocol. One of the DAGs (DAG 5) had a carbon-carbon tether instead of a disulfide one and was synthesized using modified Glaser coupling. Preparation of alpha-disulfide-tethered DAG (DAG 4) required an alternative method, as treatment of the bisbromo precursor with BTAT gave a mixture of several compounds from which separation of the target molecule was cumbersome. To avoid this problem, the bisbromide was converted to its corresponding dithiocyanate, which on further treatment with BTAT yielded the desired DAG (DAG 4) in good yield. Upon treatment with the reducing agent dithiothreitol (DTT), the DAGs that contain a disulfide tether could be quantitatively converted to their "open-chain" thiol analogues. These macrocyclic DAGs and their reduced "open-chain" analogues have been incorporated in DPPC vesicles to study their effect on model membranes. Upon incorporation of DAG 1 in DPPC vesicles, formation of new isotropic phases was observed by P-31 NMR, These isotropic phases disappeared completely on opening the macrocyclic ring by a reducing agent. The thermotropic properties of DPPC bilayers having DAGs (1-6) incorporated at various concentrations were studied by differential scanning calorimetry. Incorporation of DAGs in general reduced the cooperativity unit (CU) of the vesicles. Similar experiments with reduced "open-chain" DAGs incorporated in a DPPC bilayer indicated a recovery of CU with respect to their macrocyclic "disulfide" counterparts. The effect of inclusion of these DAGs on the activity of phospholipase A(2) (PLA(2)) was studied in vitro. Incorporation of DAC 1 in DPPC membranes potentiated both bee venom and cobra venom PLA(2) activities.

Phase conversions in calcium manganites with changing Ca/Mn ratios and their influence on the electrical transport properties

The phase-interconversions between the spinel-, brownmillerite-, defect rocksalt and perovskite-type structures have been investigated by way of (i) introducing deficiency in A-sites in CaxMn2-xO3 (0.05 <= x <= 1) i.e., by varying Ca/Mn ratio from 0.025 to 1 and (ii) nonstoichiometric CaMnO3-delta (CMO) with 0.02 <= delta <= 1. The temperature dependence of resistivity (rho-T) have been investigated on nonstoichiometric CaMnO3-delta (undoped) as well as the CMO substituted with donor impurities such as La3+, Y3+, Bi3+ or acceptor such as Na1+ ion at the Ca-site. The rho-T characteristics of nonstoichiometric CaMnO3-delta is strongly influenced by oxygen deficiency, which controls the concentration of Mn3+ ions and, in turn, affects the resistivity, rho. The results indicated that the substitution of aliovalent impurities at Ca-site in CaMnO3 has similar effects as of CaMnO3-delta ( undoped) annealed in atmospheres of varying partial pressures whereby electron or hole concentration can be altered, yet the doped samples can be processed in air or atmospheres of higher P-O2. The charge transport mechanisms of nonstoichiometric CaMnO3-delta as against the donor or acceptor doped CaMnO3 (sintered in air, P-O2 similar to 0.2 atm) have been predicted. The rho (T) curves of both donor doped CaMnO3 as well as non-stoichiometric CaMnO3-delta, is predictable by the small polaron hopping (SPH) model, which changes to the variable range hopping (VRH) at low temperatures whereas the acceptor doped CaMnO3 exhibited an activated semiconducting hopping ( ASH) throughout the measured range of temperature (10-500 K).

Hardness of a surface containing uniformly spaced pyramidal asperities

Pyramidal asperities of different apical angle were machined on a flat copper surface. Hardness was estimated from the load-displacement graphs obtained by pressing a spherical rigid indenter onto the asperities. The variation of hardness with apical angle and pitch was recorded with a view to contributing to the development of a general framework for relating measured hardness to the surface roughness.

Interaction of Co, Mn, Mg and AI with d(GCGTACGC): a spectroscopic study

Spectroscopic study on the interactions of trace elements Co, Mn, Mg and Al with d(GCGTACGC) indicated the following: Al and Mg did not alter T-m values. Mn enhanced T-m at lower concentration and decreased it at higher concentrations. Interestingly Co at higher concentration elevated the T-m. These studies also showed lower concentrations of Mn displaced EtBr, whereas Al could displace it at higher ionic strength. Mg and Co displaced EtBr fluorescence at moderate concentrations. The binding constant values and CD spectra clearly indicated strong binding of these elements to DNA.

Synthesis of novel disulfide containing macrocyclic diacylglycerols

New diacylglycerols (2-4) containing intramolecular disulfide linkages between pendant acyl chains were synthesized. Due to the differences in the location of disulfide units, the present method allows synthesis of macrocycles that vary in sizes. Copyright.

Novel Functionalised Troger's Bases: Synthesis of a New Class of Troger's Base Analogues Containing Dicarboxyl Functionality

The synthesis of three new Troger's base analogues, each functionalized with two carboxyl groups, is described. Copyright.

Simultaneous Electrodeposition of MnO2 and Mn(OH)(2) for Supercapacitor Studies

Among the various Mn compounds, both MnO2 and Mn(OH)2 are electrochemically active in supercapacitor studies. MnO2 and Mn(OH)2 are simultaneously deposited, through a one-pot method, on the anode and cathode, respectively, of a galvanostatic electrolysis cell consisting of aqueous Mn(NO3)2 electrolyte. MnO2 and Mn(OH)2 coated stainless steel (SS) electrodes are found to exhibit a capacitive behavior with a high specific capacitance. MnO2/SS and Mn(OH)2/SS electrodes are used as the negative and positive electrodes, respectively, in assembling nonsymmetrical capacitors and testing. The results indicate that both Mn-based electrodes prepared simultaneously in a single electrolysis possess interesting electrochemical properties for supercapacitor application.

Three-dimensional 3d-4f heterometallic polymers containing both azide and carboxylate as co-ligands

The hydrothermal reaction of Ln(NO3)(3), Ni(NO3)(2), NaN3, and isonicotinic acid (L) yielded two novel 3-D coordination frameworks (1 and 2) of general formula [Ni(2)Ln(L)(5)(N-3)(2)(H2O)(3)] center dot 2H(2)O (Ln = Pr(III) for 1 and Nd(III) for 2), containing Ni-Pr or Ni-Nd hybrid extended three-dimensional networks containing both azido and carboxylate as co-ligands. Both the compounds are found to be isostructural and crystallize in monoclinic system having P2(1)/n space group. Here the lanthanide ions are found to be nonacoordinated. Both bidentate and monodentate modes of binding of the carboxylate with the lanthanides have been observed in the above complexes. Variable temperature magnetic studies of the above two complexes have been investigated in the temperature range 2-300 K which showed dominant antiferromagnetic interaction in both the cases and these experimental results are analyzed with the theoretical models. (c) 2008 Elsevier B.V. All rights reserved.

Relative Stabilities of Layered Perovskite and Pyrochlore Structures in Transition Metal-Oxides Containing Trivalent Bismuth

In order to investigate the factors determining the relative stabilities of layered perovskite and pyrochlore structures of transition metal oxides containing trivalent bismuth, several ternary and quaternary oxides have been investigated. While d0 cations stabilize the layered perovskite structure, cations containing partially-filled d orbitals (which suppress ferroelectric distortion of MO6 octahedra) seem to favor pyrochlore-related structures. Thus, the vanadium analogue of the layered perovskite Bi4Ti3O12 cannot be prepared; instead the composition consists of a mixture of pyrochlore-type Bi1.33V2O6, Bi2O3, and Bi metal. The distortion of Bi1.33V2O6 to orthorhombic symmetry is probably due to an ordering of anion vacancies in the pyrochlore structure. None of the other pyrochlores investigated, Bi2NbCrO7, Bi2NbFeO7, TlBiM2O7 (M = Nb, Ta), shows evidence for cation ordering in the X-Ray diffraction patterns, as indeed established by structure refinement of TlBiNb2O7.

A Method for the Deposition of Transparent Conducting Thin-Films of Tin Oxide

A modified method has been developed for the deposition of transparent semiconducting thin films of tin oxide, involving the chemical vapour phase oxidation of tin iodide. These films show sheet resistances greater than 100 Ω/□ and an average optical transmission in the visible range exceeding 80%. The method avoids uncontrolled contamination, resulting in better reproducibility of the films. The films showed direct and indirect transitions and the possibility of an indirect forbidden transition. X-ray diffraction studies reveal that the films are polycrystalline. The low mobility values of the films have been attributed to the grain boundary scattering effect.