Certain Aspects Related To Computation By Modified Crack Closure Integral(MCCI)

This paper presents the proper computational approach for the estimation of strain energy release rates by modified crack closure integral (MCCI). In particular, in the estimation of consistent nodal force vectors used in the MCCI expressions for quarter-point singular elements (wherein all the nodal force vectors participate in computation of strain energy release rates by MCCI). The numerical example of a centre crack tension specimen under uniform loading is presented to illustrate the approach.

Efficient Hg and Ag ion detection with luminescent PbS quantum dots grown in poly vinyl alcohol and capped with mercaptoethanol

PbS quantum dots capped with mercaptoethanol (C2H5OSH) have been synthesized in poly vinyl alcohol and used to investigate their photoluminescence (PL) response to various ions such as zinc (Zn), cadmium (Cd), mercury (Hg), silver (Ag), copper (Cu), iron (Fe), manganese (Mn), cobalt (Co), chromium (Cr) and nickel (Ni). The enhancement in the PL intensity was observed with specific ions namely Zn, Cd, Hg and Ag. Among these four ions, the PL response to Hg and Ag even at sub-micro-molar concentrations was quite high, compared to that of Zn and Cd. It was observed that the change in Pb and S molar ratio has profound effect on the sensitivity of these ions. These results indicate that the sensitivity of these QDs could be fine-tuned by controlling the S concentration at the surface. Contrary to the above, Cu quenched the photoluminescence. In Cd based QDs related ion probing, Hg and Cu was found to have quenching properties, however, our PbS QDs have quenching property only for Cu ions. This was attributed to the formation HgS at the surface that has bandgap higher than PbS. Another interesting property of PbS in PVA observed is photo-brightening mechanism due to the curing of the polymer with laser. However, the presence of excess ions at the surface changes its property to photo-darkening/brightening that depends on the direction of carrier transfer mechanism (from QDs to the surface adsorbed metal ions or vice-versa). which is an interesting feature for metal ion detectivity.

L-Arginyl-L-Glutamic Acid Dihydrate, C11h21n5o5.2h2o

M r = 339.35, monoclinic, P2 t, a = 11.028 (2), b=9.583 (2), c= 16.010 (2) A, fl= 96.57 (1) °, U= 1680.85 A 3, Z = 4, D m = 1.37, D x= 1.34 Mg m -3, Cu Ka, 2 = 1.54184 A, p = 0.85 mm -1, F(000)=728, T=300K, R=0.085 for 2845 diffractometer- measured reflections IF o > 3cr(Fo)]. The two molecules in the asymmetric unit have similar conformations except for a static disorder at the C ~ and C ~ positions in one of the glutamic-acid side chains. An interesting feature of the crystal structure is a pair of hydrogen bonds between the guanidinium and ycarboxylate groups of neighbouring molecules. This is the first such specific interaction observed between side chains of arginine and glutamic acid.

Extrapolation and series acceleration procedures: Hard spheres and discs as illustrations

Three new procedures - in the context of estimation of virial coefficients and summation of the partial virial series for hard discs and hard spheres - are proposed. They are based on the parametrised Euler transformation, a novel resummation, identity and the ε-convergence methods respectively. A comparison with other estimates (molecular dynamics, graph theory and empirical methods) reveals satisfactory agreement.

Relation between high-tc superconductivity and structure - a study of la3-xba3+xcu6o14+delta and yba2cu3o7-delta systems

Superconductivity is found in tetragonal La3−x Ba3+x Cu6O14+δ and La, Ba)6−x Sr x Cu6O14+δ even though they do not possess Cu-O chains or the K2NiF4 structure. Resistivity measurements confirm the occurrence of a transformation from chain-superconductivity to sheet-superconductivity in YBa2Cu3O7−δ as δ is varied in the range 0.0–0.5.

Structure of 7-methyl-1(2)a,1(6)a,3(4)a-trihomocubane-1(6)a,3(4)a-dione,star-c12h12o2- a case of enantiomeric and rotational disorder

M r = 188.22, monoclinic, P21/n, a = 6.219 (2), b= 10.508 (2), c=7.339 (1)A, t= 107.64 (2) °, V= 457 ,/k 3, Z = 2, D m - - 1.360 (3), D x = 1.366 (2)Mgm -3, ~,(MoKa) = 0.7107/~, #= 0.053 mm -I, F(000) = 200, T= 293 K. Final R = 5.8% for 614 significant reflections. The molecule, which does not possess a centre of symmetry, occupies a crystallographic centre of symmetry because of the statistical enantiomeric and rotational disorder. Latticeenergy calculations, based on van der Waals attractive and repulsive potentials, clearly show minima at the observed disordered positions.

Focused Prefetching: Performance Oriented Prefetching Based On Commit Stalls

Loads that miss in L1 or L2 caches and waiting for their data at the head of the ROB cause significant slow down in the form of commit stalls. We identify that most of these commit stalls are caused by a small set of loads, referred to as LIMCOS (Loads Incurring Majority of COmmit Stalls). We propose simple history-based classifiers that track commit stalls suffered by loads to help us identify this small set of loads. We study an application of these classifiers to prefetching. The classifiers are used to train the prefetcher to focus on the misses suffered by LIMCOS. This, referred to as focused prefetching, results in a 9.8% gain in IPC over naive GHB based delta correlation prefetcher along with a 20.3% reduction in memory traffic for a set of 17 memory-intensive SPEC2000 benchmarks. Another important impact of focused prefetching is a 61% improvement in the accuracy of prefetches. We demonstrate that the proposed classification criterion performs better than other existing criteria like criticality and delinquent loads. Also we show that the criterion of focusing on commit stalls is robust enough across cache levels and can be applied to any prefetcher without any modifications to the prefetcher.

Comment: Eigenvalue sensitivity method for optimal stabilisation of linear systems

In a letter RauA proposed a new method for designing statefeedback controllers using eigenvalue sensitivity matrices. However, there appears to be a conceptual mistake in the procedure, or else it is unduly restricted in its applicability. In particular the equation — BR~lBTK = A/.I, in which K is a positive-definite symmetric matrix.

Purification and properties of riboflavin-binding protein from the egg white of the duck (Anas platyrhynckos).

Riboflavin-binding protein was purified from the egg white of domestic duck and some of its properties were investigated. The protein was homogeneous by the criteria of gel filtration on Sephadex G-100 and electrophoresis on sodium dodecyl sulphate-polyacrylamide gels, had molecular weight of 36 000 ± 1000 and, unlike the chicken egg white protein (Mr 32 000 ± 2000), was devoid of covalently-bound carbohydrate. It was similar to the chicken riboflavin-binding protein in its behavior on ion-exchange celluloses and affinity to interact with the flavin and its coenzymes, but differed significantly in amino acid composition in that it completely lacked proline and contained less of methionine and arginine. The protein partially cross-reacted with the specific antiserum to chicken riboflavin-binding protein with a spur during immunodiffusion analysis.

3-Amino-1,2,4-triazole is an inhibitor of protein synthesis on mitoribosomes in Neurospora crassa

The effects of the herbicide, 3-amino-1,2,4-triazole, an inhibitor of heme synthesis in rat liver, have been examined in the mold Neurospora crassa. The drug is a potent inhibitor of the growth of the mold and produces biochemical changes identical to those produced by chloramphenicol. 3-Amino-1,2,4-triazole, like chloramphenicol, is a direct and specific inhibitor of protein synthesis on mitoribosomes. A decrease in the levels of mitochondrial proteins which are completely or partly made on mitoribosomes and an accumulation in the levels of mitochondrial proteins of cytosolic origin have been observed. Both drugs depress porphyrin and heme levels, but there is actually an elevation in the levels of δ-aminolevulinate dehydratase, the rate-limiting enzyme of the heme-biosynthetic pathway in Neurospora crassa. In liver the enzyme is present in non-limiting amounts and the levels are depressed under conditions of 3-amino-1,2,4-triazole treatment. In Neurospora crassa the ‘derepression’ of δ-aminolevulinate dehydratase under conditions of 3-amino-1,2,4-triazole or chloramphenicol treatment is only partial because the drugs inhibit protein synthesis on mitoribosomes. It is concluded that an optimal rate of protein synthesis on mitoribosomes is necessary to maintain an adequate rate of heme synthesis.

The structure of 3-(2-methoxyphenyl)-1,1,2,2-cyclopropanetetracarbonitrile

Crystals of C I4HsN40 are monoclinic, space group P21, Unit-cell constants are a = 13.241(4), b = 7.446 (2), c = 6.436 (2)/A, B= 93.23 (2) °. V= 633.5 /A3, Z = 2, Dob s = 1.30 (flotation), Dealt = 1.300 Mg m -3 and #(Cu Ka) = 0.72 mm -1. The structure, solved by direct methods, has been refined to an R value of 3.5% using 1245 intensity measurements. The combined effect of electron-withdrawing and –donating substituents on the geometry of the cyclopropane ring is discussed.

Effect of surface resistance on gas absorption accompanied by a chemical reaction in a gas - liquid contactor

An analysis of gas absorption accompanied by chemical reaction in the presence of interfacial resistance is presented. The analysis indicates that the effect of interfacial resistance on interphase mass transfer is significantly higher in presence of a reaction compared to the pure absorption case. For fixed values of surface resistance and contact time, the difference between the amount of gas transferred across the interface with and without surface resistance increases as the value of reaction velocity increases. For ranges of contact time and surface resistance of practical relevance, the influence of surface resistance is too high to be neglected while designing gas-liquid contactors.

Thermodynamic implication of the special relativistic postulate

Abstract is not available.