Axisymmetric deformation of a short magneto-strictive current-carrying cylinder

The title-problem has been reduced to that of solving a Fredholm integral equation of the second kind. One end of the cylinder is assumed to be fixed, while the cylinder is deformed by an axial current. The vertical displacement on the upper flat end of the cylinder has been determined from an iterative solution of the Fredholm equation valid for large values of the length. The radial displacement of the curved boundary has also been determined at the middle of the cylinder, by using the iterative solution.

Tributyltin chloride-sodium cyanoborohydride mediated tandem radical cyclisation-reductive demethoxylation sequence

Reaction of the bromoketals 3, 7a-g and 11 with tri-n-butyltin chloride and sodium cyanoborohydride in the presence of a catalytic amount of AIBN furnished the ethers 5, 8a-g and 13 via a tandem sequence comprising of a radical cyclisation reaction and tri-n-butylhalostannane and sodium cyanoborohydride mediated reductive demethoxylation of the resulting cyclic ketals.

Primary structure of a Thomsen-Friedenreich-antigen-specific lectin, jacalin [Artocarpus integrifolia (jack fruit) agglutinin]. Evidence for the presence of an internal repeat

Jacalin [Artocarpus integrifolia (jack fruit) agglutinin] is made up of two types of chains, heavy and light, with M(r) values of 16,200 +/- 1200 and 2090 +/- 300 respectively (on the basis of gel-permeation chromatography under denaturing conditions). Its complete amino acid sequence was determined by manual degradation using a 4-dimethylaminoazobenzene 4'-isothiocyanate double-coupling method. Peptide fragments for sequence analysis were obtained by chemical cleavages of the heavy chain with CNBr, hydroxylamine hydrochloride and iodosobenzoic acid and enzymic cleavage with Staphylococcus aureus proteinase. The peptides were purified by a combination gel-permeation and reverse-phase chromatography. The light chains, being only 20 residues long, could be sequenced without fragmentation. Amino acid analyses and carboxypeptidase-Y-digestion C-terminal analyses of the subunits provided supportive evidence for their sequence. Computer-assisted alignment of the jacalin heavy-chain sequence failed to show sequence similarity to that of any lectin for which the complete sequence is known. Analyses of the sequence showed the presence of an internal repeat spanning residues 7-64 and 76-130. The internal repeat was found to be statistically significant.

Triplet repeat polymorphism & fragile X syndrome in the Indian context

Mental retardation due to fragile X syndrome is one of the genetic disorders caused by tripler repeat expansion, CGG repeat involved in this disease is known to exhibit polymorphism even among normal individuals. Here we describe the development of suitable probes for detection of polymorphism in CGG repeat at FMR1 locus as well as the diagnosis of fragile X syndrome. Using these methods polymorphism at the FMR1 locus has been examined in 161 individuals. Ninety eight patients with unclassified mental retardation were examined, of whom 7 were found to have the expanded (CGG) allele at the FMR1 locus, The hybridization pattern for two patients has been presented as representative data.

Convenient Synthesis of Ferrocene Conjugates Mediated by Benzyltriethylammonium Tetrathiomolybdate in a Multi-Step Tandem Process

The synthesis of a wide range of ferrocene-derived sulfur-linked mono- and disubstituted Michael adducts and conjugates mediated by benzyltriethylammonium tetrathiomolybdate (1) in a tandem process is reported. New route to access acryloylferrocene (4) and 1,1'-diacryloylferrocene (5) is discussed. Conjugation of amino acids to ferrocene is established via their N and C termini and also via side chains employing conjugate addition as key step to furnish mono-and divalent conjugates. This methodology has also been extended to access several ferrocene-carbohydrate conjugates. The electrochemical behavior of some selected ferrocene conjugates was studied by cyclic voltammetry.

Characterization of the restriction enzyme-like endonuclease encoded by the Entamoeba histolytica non-long terminal repeat retrotransposon EhLINE1

The genome of the human pathogen Entamoeba histolytica, a primitive protist, contains non-long terminal repeat retrotransposable elements called EhLINEs. These encode reverse transcriptase and endonuclease required for retrotransposition. The endonuclease shows sequence similarity with bacterial restriction endonucleases. Here we report the salient enzymatic features of one such endonuclease. The kinetics of an EhLINE1-encoded endonuclease catalyzed reaction, determined under steady-state and single-turnover conditions, revealed a significant burst phase followed by a slower steady-state phase, indicating that release of product could be the slower step in this reaction. For circular supercoiled DNA the K-m was 2.6 x 10-8 m and the k(cat) was 1.6 x 10-2 sec-1. For linear E. histolytica DNA substrate the K-m and k(cat) values were 1.3 x 10-8 m and 2.2 x 10-4 sec-1 respectively. Single-turnover reaction kinetics suggested a noncooperative mode of hydrolysis. The enzyme behaved as a monomer. While Mg2+ was required for activity, 60% activity was seen with Mn2+ and none with other divalent metal ions. Substitution of PDX12-14D (a metal-binding motif) with PAX(12-14)D caused local conformational change in the protein tertiary structure, which could contribute to reduced enzyme activity in the mutated protein. The protein underwent conformational change upon the addition of DNA, which is consistent with the known behavior of restriction endonucleases. The similarities with bacterial restriction endonucleases suggest that the EhLINE1-encoded endonuclease was possibly acquired from bacteria through horizontal gene transfer. The loss of strict sequence specificity for nicking may have been subsequently selected to facilitate spread of the retrotransposon to intergenic regions of the E. histolytica genome.

Distress call-induced gene expression in the brain of the Indian short-nosed fruit bat, Cynopterus sphinx

Individuals in distress emit audible vocalizations to either warn or inform conspecifics. The Indian short-nosed fruit bat, Cynopterus sphinx, emits distress calls soon after becoming entangled in mist nets, which appear to attract conspecifics. Phase I of these distress calls is longer and louder, and includes a secondary peak, compared to phase II. Activity-dependent expression of egr-1 was examined in free-ranging C. sphinx following the emissions and responses to a distress call. We found that the level of expression of egr-1 was higher in bats that emitted a distress call, in adults that responded, and in pups than in silent bats. Up-regulated cDNA was amplified to identify the target gene (TOE1) of the protein Egr-1. The observed expression pattern Toe1 was similar to that of egr-1. These findings suggest that the neuronal activity related to recognition of a distress call and an auditory feedback mechanism induces the expression of Egr-1. Co-expression of egr-1 with Toe1 may play a role in initial triggering of the genetic mechanism that could be involved in the consolidation or stabilization of distress call memories.

Structure formation in short designed peptides probed by proteolytic cleavage

The formation of local structure, in short peptides has been probed by examining cleavage patterns and rates of proteolysis of designed sequences with a high tendency to form β-hairpin structures. Three model sequences which bear fluorescence donor and acceptor groups have been investigated: Dab-Gaba-Lys-Pro-Leu-Gly-Lys-Val-Xxx-Yyy-Glu-Val-Ala-Ala-Cys-Lys-NH2 ï EDANS Xxx-Yyy: Peptide 1=DPro-LPro, Peptide 2=DPro-Gly, Peptide 3=Leu-Ala Fluorescence resonance energy transfer (FRET) provides a convenient probe for peptide cleavage. MALDI mass spectrometry has been used to probe sites of cleavage and CD spectroscopy to access the overall backbone conformation using analog sequences, which lack strongly absorbing donor and acceptor groups. The proteases trypsin, subtilisin, collagenase, elastase, proteinase K and thermolysin were used for proteolysis and the rates of cleavage determined. Peptide 3 is the most susceptible to cleavage by all the enzymes except thermolysin, which cleaves all three peptides at comparable rates. Peptides 1 and 2 are completely resistant to the action of trypsin, suggesting that β-turn formation acts as a deterrent to proteolytic cleavage.

Multiple conformational states in crystals and in solution in alpha gamma hybrid peptides. Fragility of the C-12 helix in short sequences

The conformational properties of foldamers generated from alpha gamma hybrid peptide sequences have been probed in the model sequence Boc-Aib-Gpn-Aib-Gpn-NHMe. The choice of alpha-aminoisobutyryl (Aib) and gabapentin (Gpn) residues greatly restricts sterically accessible coil formational space. This model sequence was anticipated to be a short segment of the alpha gamma C-12 helix, stabilized by three successive 4 -> 1 hydrogen bonds, corresponding to a backbone-expanded analogue of the alpha polypeptide 3(10)-helix. Unexpectedly, three distinct crystalline polymorphs were characterized in the solid state by X-ray diffraction. In one form, two successive C-12 hydrogen bonds were obtained at the N-terminus, while a novel C-17 hydrogen-bonded gamma alpha gamma turn was observed at the C-terminus. In the other two polymorphs, isolated C-9 and C-7 hydrogen-bonded turns were observed at Gpn (2) and Gpn (4). Isolated C-12 and C-9 turns were also crystallographically established in the peptides Boc-Aib-Gpn-Aib-OMe and Boc-Gpn-Aib-NHMe, respectively. Selective line broadening of NH resonances and the observation of medium range NH(i)<-> NH(i+2) NOEs established the presence of conformational heterogeneity for the tetrapeptide in CDCl3 solution. The NMR results are consistent with the limited population of the continuous C-12 helix conformation. Lengthening of the (alpha gamma)(n) sequences in the nonapeptides Boc-Aib-Gpn-Aib-Gpn-Aib-Gpn-Aib-Gpn-Xxx (Xxx = Aib, Leu) resulted in the observation of all of the sequential NOEs characteristic of an alpha gamma C-12 helix. These results establish that conformational fragility is manifested in short hybrid alpha gamma sequences despite the choice of conformationally constrained residues, while stable helices are formed on chain extension.

Design of rectangular reinforced concrete slabs supported on all the sides with a short discontinuous edge

Bending moment coefficients for the design of rectangular reinforced concrete panels supported on four sides with a short discontinuous edge are derived using the strip theory. The moment fields resulting from the use of proposed coefficients are examined in terms of the moment volume for possible savings in reinforcement and compared with other codified procedures. The strip coefficients averaged over the corresponding sides of the panel, besides resulting in considerable savings in reinforcement, are found to be identical with the coefficients predicted by simple yield line theory using an orthotropic layout of reinforcement.

Synthesis based on cyclohexadienes. Part 34. A tandem cationic rearrangement-ene cyclisation route to 2-pupukeanone

A new strategy for the construction of the isotwistane skeleton is reported from easily available cyclohexadienes, which involves a one-pot cationic skeletal rearrangement and ene cyclisation of a bicyclo[2.2.2]octenone derivative and a cationic rearrangement of a tricyclo[5.3.0.0(4,8)]decane to a [4.3.1.0(3,7)]decane skeleton as the key steps in the synthesis of 2-pupukeanone.

Effect of insertion of buffer-strip on the response of carbon-epoxy system in short beam tests

dThe work looks at the response to three-point loading of carbon-epoxy (CF-EP) composites with inserted buffer strip (BS) material. Short beam Shear tests were performed to study the load-deflection response as well as fracture features through macroscopy on the CF-EP system containing the interleaved PTFE-coated fabric material. Significant differences were noticed in the response of the CF-EP system to the bending process consequent to the architectural modification. It was inferred that introduction of small amounts of less adherent layers of material at specific locations causes a decrement in the load carrying capability. Further the number and the ease with which interface separation occurs is found to depend on the extent to which the inserted layer is present in either single or multiple layer positions.

Analysis of short interproton distances in proline peptides as a guide in the interpretation of nuclear overhauser effects

The conformational dependence of interproton distances in model proline peptides has been investigated in order to facilitate interpretation of the results of Nuclear Overhauser Effect (NOE) studies on such peptides. For this purpose two model systems, namely, Ac-Pro-NHMe and Ac-Pro-X-NHMe have been chosen and used. In the former, short interproton distances detectable in NOE experiments permit a clear distinction between conformations with Pro ψ = -300 (helical region) and those in which ψ is around 1200 (polyproline region). For the latter, the variation of distances between the protons of methyl amide and the Pro ring have been studied by superimposing on the Ramachandran map in the (φ3, ψ3) plane. The results show that β-turns and non-β-turn conformations can be readily distinguished from NOE data and such long range NOEs should be detectable for specific non-β-turn conformations. NOEs involving Cβ and Cγ protons are particularly sensitive to the state of pyrrolidine ring puckering.

Enantiodiscrimination and extraction of short and long range homo- and hetero-nuclear residual dipolar couplings by a spin selective correlation experiment

A two dimensional correlation experiment for the measurement of short and long range homo- and hetero- nuclear residual dipolar couplings (RDCs) from the broad and featureless proton NMR spectra including C-13 satellites is proposed. The method employs a single natural abundant C-13 spin as a spy nucleus to probe all the coupled protons and permits the determination of RDCs of negligible strengths. The technique has been demonstrated for the study of organic chiral molecules aligned in chiral liquid crystal, where additional challenge is to unravel the overlapped spectrum of enantiomers. The significant advantage of the method is demonstrated in better chiral discrimination using homonuclear RDCs as additional parameters. (C) 2010 Elsevier B.V. All rights reserved.