Fast matrix transposition computer implementation

Eklundh's (1972) algorithm to transpose a large matrix stored on an external device such as a disc has been programmed and tested. A simple description of computer implementation is given in this note.

Proton spin lattice relaxation in lithium ammonium sulphate LiNH4SO4

Lithium ammonium sulphate (LAS) undergoes a phase transition at TC1=459.5K from a paraelectric phase (phase I) to a ferroelectric phase (phase II) and again at TC2=283K to a polar ferroelastic phase (phase III). Proton spin lattice relaxation time measured at 10 MHz in powdered LAS in the temperature range 480 to 77K shows discontinuous changes at the two transitions.

Approximate solutions of Fredholm integral equations of the second kind

This note is concerned with the problem of determining approximate solutions of Fredholm integral equations of the second kind. Approximating the solution of a given integral equation by means of a polynomial, an over-determined system of linear algebraic equations is obtained involving the unknown coefficients, which is finally solved by using the least-squares method. Several examples are examined in detail. (c) 2009 Elsevier Inc. All rights reserved.

Structure of 2',3'-O-Isopropylidene-5'-O-tosyluridine, C19H22N 2Oas

M r = 438.45, trigonal, P32, a = b = 13.385 (4), c = 9.900 (5) A,, V = 1536.0 A 3, Z = 3, D x = 1.42, D m = 1.42 Mg m -3, 2(Cu Ka) = 1.5418 A,,g(CuKa) = .800mm -], T=290K, F(000)=690, R=6.0% for 1222 unique reflections with F o>_2o(Fo). This is the first 2',3'-O-isopropylidene pyrimidine nucleoside with the base in a syn orientation with respect to the ribose [Xcy= 116.0(7)°]. The ribose has a C(3')-endo conformation with the phase angle of pseudorotation P = 16.36 (2) °. The dioxolane ring assumes an envelope conformation with 0(2') displaced from the best four-atom plane by 0.50 (1) k. The crystal structure is possibly stabilized by a bifurcated hydrogen bond between N(3) and the 0(2) and 0(4) atoms of screw-related molecules.

Algorithms for Constructing Hierarchical Graphs

An algorithm is described for developing a hierarchy among a set of elements having certain precedence relations. This algorithm, which is based on tracing a path through the graph, is easily implemented by a computer.

Algorithms for Constructing Hierarchical Graphs

An algorithm is described for developing a hierarchy among a set of elements having certain precedence relations. This algorithm, which is based on tracing a path through the graph, is easily implemented by a computer.

Application of molecular orbital theory to the interpretation of x-ray absorption spectra of platinum complexes

X-ray LIII-absorption edges of platinum in nine octahedral complexes have been recorded using a bent crystal spectrograph. The edge features of the discontinuities have been interpreted with the help of qualitative molecular orbital diagrams. A correlation between the energy separation of the first two absorption maxima and the spectrochemical series of the ligands has been arrived at.

CsrA interacting small RNAs in Haemophilus spp genomes: a theoretical analysis

The csrA is a carbon storage regulator gene that encodes a protein with multiple RNA interaction sites. Bacterial non-coding small RNAs like csrB, csrC and their counterparts in diverse bacterial genus are identified to control the regulatory activities of CsrA and its orthologs. An attempt has been made in this study to identify 'novel' non-coding small RNAs that are involved in the regulatory activities of csrA gene. All CsrA-interacting small RNAs are computationally fingerprinted to have multiple occurrence of 7-nucleotide CsrA interacting repeats [CAGGA(U/A/C)G] along with a 18-nucleotide upstream binding site. However, in several of the genomes like Haemophilus spp, the upstream binding site is not identified. The current methodology overcomes this difficulty by identifying small RNA-specific orphan transcriptional units within the intergenic regions of the genome. The results could identify all known CsrA-interacting small RNAs in E. coli, Vibrio cholerae and Pseudomonas aeruginosa genomes and additionally has picked six new possible CsrA-interacting small RNA regions in E. coli. Our computational analysis indicates that known rygD and rprA sRNAs in E. coli could possibly interact with CsrA proteins. The study is extended to three of the Haemophilus genomes that could identify seven new possible CsrA interacting small RNAs.

High field electrical switching behavior of Ge10Se90-xTlx glasses

Electrical Switching Studies on bulk Ge10Se90-xTlx ( 15 <= x <= 34) glasses have been undertaken to examine the type of switching, composition and thickness dependence of switching voltages. Unlike Ge-Se-Tl thin films which exhibit memory switching, the bulk Ge10Se90-xTlx glasses are found to exhibit threshold type switching with fluctuations seen in their current-voltage (I-V) characteristics. Further, it is observed that the switching voltages (V-T) of Ge10Se90-xTlx glasses decrease with the increase in the Tl concentration. An effort has been made to understand the observed composition dependence on the basis of nature of bonding of Tl atoms and a decrease in the chemical disorder with composition. In addition. the network connectivity and metallicity factors also contribute for the observed decrease in the switching voltages of Ge10Se90-xTlx glasses with Tl addition. It is also interesting to note that the composition dependence of switching voltages of Ge10Se90-xTlx glasses exhibit a small Cusp around the composition x = 22. which is understood on the basis of a thermally reversing window in this system in the composition range 22 <= x <= 30. The thickness dependence of switching voltages has been found to provide an insight about the type of switching mechanism involved in these samples. (C) 2009 Elsevier B.V. All rights reserved

Enantiospecific synthesis of thaps-8-en-5-ol via stereospecific intramolecular chirality transfer

Enantiospecific synthesis of thaps-8-en-5-ol, comprising of the carbon framework of a small group of sesquiterpenes containing three contiguous quaternary carbon atoms has been described. (R)-Carvone has been employed as the chiral starting material and a combination of intramolecular alkyation and Criegec fragmentation have been employed for intramolecular stereospecific transfer of the chirality. An intramolecular diazoketone cyclopropanation and regioselective cyclopropane ring cleavage reactions have been employed for the creation of the three requisite contiguous quaternary carbon atoms.

The vibration of cantilever bridges.

The natural frequencies of symmetrical double cantilever bridges are studied. Determinantal frequency equations are derived for the symmetric and the antisymmetric modes of vibration. They are solved numerically on a computer by the bisection method for the frequency parameter. The values of the frequency parameter for the first four modes are presented. Typical mode shapes are also presented.

Hydrolytic reactions of tetrasulphur tetranitride in a homogeneous medium

The hydrolytic reactions of tetrasulphur tetranitride are studied in a homogeneous medium. Alkaline hydrolysis gives sulphite, thiosulphate, sulphate and sulphide whereas the products in acid hydrolysis are mainly sulphur dioxide, elemental sulphur and hydrogen sulphide, with traces of polythionates. Under optimum conditions, tetrasulphur tetranitride reacts with sulphite consuming 2 moles of sulphite per mole of sulphur nitride to give 2 moles of trithionate. The reaction of sulphur nitride with thiosulphuric acid gives pentathionate and tetrathionate.

Diphenyl sulphox1de complexes of thorium(IV)

Thorium(IV) is known to form high coordination-number complexes. An attempt has therefore been made to determine the effect of anions on the coordination complexes of diphenyl sulphoxide (DPSO) with thorium(IV). The complexes formed have the formulae [Th(DPSO)6](ClO4)4, [Th(DPSO)4Cl4], [Th(DPSO)4Br4], [Th(DPSO)6I2]I2, [Th(DPSO)4(NCS)4]and [Th(DPSO)3(NO3)4]. In all the complexes, DPSO is coordinated to the metal ion through its oxygen. The electrical conductances in nitrobenzene and in nitromethane, and ebullioscopic molecular weights in acetonitrile, show that the perchlorate and iodide complexes behave as 1:4 and 1:2 electrolytes, respectively; while the other complexes are monomeric and non-electrolytes. The infrared spectra of the solid complexes indicate the ionic nature of the perchlorate, the bidentate nature of the nitrate and the coordination of the thiocyanate through its nitrogen. [Th(DPSO)4Cl4], [Th(DPSO)4Br4]and [Th-(DPSO)3 (NO3)4]decompose endothermically while [Th(DPSO)6](ClO4)4 and [Th(DPSO)4(NCS)4]decompose exothermically, both in air and in nitrogen. The perchlorate complex has octahedral symmetry around the thorium, the halo- and the thiocyanato complexes are 8-coordinate, probably with square antiprismatic structures, while the nitrate complex is 11-coordinate

A unified model for auxiliary switch commutated DC-DC converters

A novel ZVS auxiliary switch commutated variation for all DGDC converter topologies has been proposed in 2006. With proper designation of the circuit variables (throw current I and the pole voltage V), all these converters are seen to be governed by an identical set of equations. With idealized switches, the steady-state performance is obtainable in an analytical form. The conversion ratio of the converter topologies is obtained. A generalized equivalent circuit emerges for all these converters from the steady-state conversion ratio. It also provides a dynamic model as well. With these generalized steady-state equivalent circuits, small signal analysis of these converters may be carried out readily. It enables one to use the familiar state space averaged results of the standard PWM DGDC converters for the resonant counterparts. Th dc and ac models reveals that dc and low frequency behaviour of the proposed family of converters is similiar to that of its PWM parent