Selenoacetamide: Vibrational assignments and normal coordinate analysis

The i.r. spectra of selenoacetamide and its N-deuterated species have been recorded The fundamental frequencies of these compounds have been assigned. Force constants derived for thioacetamide and acetamide were transferred to the present compound and a good agreement with the observed frequencies were achieved. The results are discussed in relation to acetamide and thioacetamide.

Spectral assignments based on the 13C NMR spectra of mixed liquid crystals of opposite diamagnetic anisotropies

The proton-decoupled 13C NMR spectra of mixtures of liquid crystals with opposite diamagnetic anisotropies have been studied in the natural abundance of 13C. A new method to assign the spectral lines to specific carbons in the liquid crystalline phase has been developed. For this purpose, the assignments of lines in the isotropic media are required, and they were obtained from two-dimensional hetero-COSY experiments. From the spectra in the �critical� mixtures where both the orientations of the liquid crystal directors, with the alignments along and perpendicular to the direction of the magnetic field, �coexist,� the 13C chemical-shift anisotropies have been determined, assuming uniaxial symmetry.

H-1, C-13, N-15 assignments of the dimeric regulatory subunit (ilvN) of the E. coli AHAS I

Acetohydroxyacid synthase (AHAS) is an enzyme involved in the biosynthesis of the branched chain amino acids viz, valine, leucine and isoleucine. The activity of this enzyme is regulated through feedback inhibition by the end products of the pathway. Here we report the backbone and side-chain assignments of ilvN, the 22 kDa dimeric regulatory subunit of E. coli AHAS isoenzyme I, in the valine bound form. Detailed analysis of the structure of ilvN and its interactions with the catalytic subunit of E. coli AHAS I will help in understanding the mechanism of activation and regulation of the branched chain amino acid biosynthesis.

An Axiom of Military Law : Applicability of National Criminal Law to Military Personnel and Associated Civilians Abroad

States regularly deploy elements of their armed forces abroad. When that happens, the military personnel concerned largely remain governed by the penal law of the State that they serve. This extraterritorial extension of national criminal law, which has been treated as axiomatic in domestic law and ignored by international law scholarship, is the subject of this dissertation. The first part of the study considers the ambit of national criminal law without any special regard to the armed forces. It explores the historical development of the currently prevailing system of territorial law and looks at the ambit that national legal systems claim today. Turning then to international law, the study debunks the oddly persistent belief that States enjoy a freedom to extend their laws to extraterritorial conduct as they please, and that they are in this respect constrained only by some specific prohibitions in international law. Six arguments historical, empirical, ideological, functional, doctrinal and systemic are advanced to support a contrary view: that States are prohibited from extending the reach of their legal systems abroad, unless they can rely on a permissive principle of international law for doing so. The second part of the study deals specifically with State jurisdiction in a military context, that is to say, as applied to military personnel in the strict sense (service members) and various civilians serving with or accompanying the forces (associated civilians). While the status of armed forces on foreign soil has transformed from one encapsulated in the customary concept of extraterritoriality to a modern regulation of immunities granted by treaties, elements of armed forces located abroad usually do enjoy some degree of insulation from the legal system of the host State. As a corollary, they should generally remain covered by the law of their own State. The extent of this extraterritorial extension of national law is revealed in a comparative review of national legislation, paying particular attention to recent legal reforms in the United States and the United Kingdom two states that have sought to extend the scope of their national law to cover the conduct of military contractor personnel. The principal argument of the dissertation is that applying national criminal law to service members and associated civilians abroad is distinct from other extraterritorial claims of jurisdiction (in particular, the nationality principle or the protective principle of jurisdiction). The service jurisdiction over the armed forces has a distinct aim: ensuring the coherence and indivisibility of the forces and maintaining discipline. Furthermore, the exercise of service jurisdiction seeks to reduce the chances of the State itself becoming internationally liable for the conduct of its service members and associated civilians. Critically, the legal system of the troop-deploying State, by extending its reach abroad, seeks to avoid accountability gaps that might result from immunities from host State law.

An online-implementable differential evolution tuned all-aspect guidance law

This paper proposes a differential evolution based method of improving the performance of conventional guidance laws at high heading errors, without resorting to techniques from optimal control theory, which are complicated and suffer from several limitations. The basic guidance law is augmented with a term that is a polynomial function of the heading error. The values of the coefficients of the polynomial are found by applying the differential evolution algorithm. The results are compared with the basic guidance law, and the all-aspect proportional navigation laws in the literature. A scheme for online implementation of the proposed law for application in practice is also given. (c) 2010 Elsevier Ltd. All rights reserved.

Disulfide Bond Assignments by Mass Spectrometry of Native Natural Peptides: Cysteine Pairing in Disulfide Bonded Conotoxins

The critical, and often most difficult, step in structure elucidation of diverse classes of natural peptides is the determination of correct disulfide pairing between multiple cysteine residues. Here, we present a direct mass spectrometric analytical methodology for the determination of disulfide pairing. Protonated peptides, having multiple disulfide bonds, fragmented under collision induced dissociation (CID) conditions and preferentially cleave along the peptide backbone, with occasional disulfide fragmentation either by C-beta-S bond cleavage through H-alpha abstraction to yield dehydroalanine and cysteinepersulfide, or by S-S bond cleavage through H-beta abstraction to yield the thioaldehyde and cysteine. Further fragmentation of the initial set of product ions (MSn) yields third and fourth generation fragment ions, permitting a distinction between the various possible disulfide bonded structures. This approach is illustrated by establishing cysteine pairing patterns in five conotoxins containing two disulfide bonds. The methodology is extended to the Conus araneosus peptides An 446 and Ar1430, two 14 residue sequences containing 3 disulfide bonds. A distinction between 15 possible disulfide pairing schemes becomes possible using direct mass spectral fragmentation of the native peptides together with fragmentation of enzymatically nicked peptides.

High-resolution methyl edited GFT NMR experiments for protein resonance assignments and structure determination

Three-dimensional (3D) structure determination of proteins is benefitted by long-range distance constraints comprising the methyl groups, which constitute the hydrophobic core of proteins. However, in methyl groups (of Ala, Ile, Leu, Met, Thr and Val) there is a significant overlap of C-13 and H-1 chemical shifts. Such overlap can be resolved using the recently proposed (3,2)D HCCH-COSY, a G-matrix Fourier transform (GFT) NMR based experiment, which facilitates editing of methyl groups into distinct spectral regions by combining their C-13 chemical shifts with that of the neighboring, directly attached, C-13 nucleus. Using this principle, we present three GFT experiments: (a) (4,3)D NOESY-HCCH, (b) (4,3)D H-1-TOCSY-HCCH and (c) (4,3)D C-13-TOCSY-HCCH. These experiments provide unique 4D spectral information rapidly with high sensitivity and resolution for side-chain resonance assignments and NOE analysis of methyl groups. This is exemplified by (4,3)D NOESY-HCCH data acquired for 17.9 kDa non-deuterated cytosolic human J-protein co-chaperone, which provided crucial long-range distance constraints for its 3D structure determination.

Vibrational Spectra and Assignments for the Fundamental Vibrations of Imidazolidine-2-thione and -2-selenone

Infrared spectra of imidazolidine-2-thione (N,N?-ethylenethiourea, ETU) and its N,N?-deuterated (ETU-d2) and S-methylthiouronium iodides have been recorded from 4000 to 30 cm?1. Normal coordinate analyses of ETU and ETU-d2 have been made for all the fundamental frequencies, employing a Urey-Bradley potential function supplemented with valence type constants for the out of plane modes of the planar skeleton. Raman frequencies of ETU from literature have been utilised. The results of the vibrational analyses are discussed in relation to the group frequencies in structurally related molecules and frequency shifts on deuteration and S-methylation. The normal coordinate treatment is also performed for the planar vibrations of imidazolidine-2-selenone (N,N?-ethyleneselenourea, ESU) to propose assignments for ESU and so also to support the assignments of ETU.

Deformation dynamics of SS-316 Between 1023-K TO 1223-K In The Framework of Cottrell-Stokes Law

Kocks' formalism for analysing steady state deformation data for the case where Cottrell-Stokes law is valid is extended to incorporate possible back stresses from solution and/or precipitation hardening, and dependence of pre-exponential factor on the applied stress. A simple graphical procedure for exploiting these equations is demonstrated by analyzing tensile steady state data for a type 316 austentic stainless steel for the temperature range 1023 to 1223 K. In this instance, the computed back stress values turned out to be negative, a physically meaningless result. This shows that for SS 316, deformation in this temperature regime can not be interpreted in terms of a mechanism that obeys Cottrell-Stokes law.

Amino acid selective unlabeling for sequence specific resonance assignments in proteins

Sequence specific resonance assignment constitutes an important step towards high-resolution structure determination of proteins by NMR and is aided by selective identification and assignment of amino acid types. The traditional approach to selective labeling yields only the chemical shifts of the particular amino acid being selected and does not help in establishing a link between adjacent residues along the polypeptide chain, which is important for sequential assignments. An alternative approach is the method of amino acid selective `unlabeling' or reverse labeling, which involves selective unlabeling of specific amino acid types against a uniformly C-13/N-15 labeled background. Based on this method, we present a novel approach for sequential assignments in proteins. The method involves a new NMR experiment named, {(CO)-C-12 (i) -N-15 (i+1)}-filtered HSQC, which aids in linking the H-1(N)/N-15 resonances of the selectively unlabeled residue, i, and its C-terminal neighbor, i + 1, in HN-detected double and triple resonance spectra. This leads to the assignment of a tri-peptide segment from the knowledge of the amino acid types of residues: i - 1, i and i + 1, thereby speeding up the sequential assignment process. The method has the advantage of being relatively inexpensive, applicable to H-2 labeled protein and can be coupled with cell-free synthesis and/or automated assignment approaches. A detailed survey involving unlabeling of different amino acid types individually or in pairs reveals that the proposed approach is also robust to misincorporation of N-14 at undesired sites. Taken together, this study represents the first application of selective unlabeling for sequence specific resonance assignments and opens up new avenues to using this methodology in protein structural studies.

Combined convection in power-law fluids along a nonisothermal vertical plate in a porous medium

The problem of combined convection from vertical surfaces in a porous medium saturated with a power-law type non-Newtonian fluid is investigated. The transformed conservation laws are solved numerically for the case of variable surface heat flux conditions. Results for the details of the velocity and temperature fields as well as the Nusselt number have been presented. The viscosity index ranged from 0.5 to 2.0.

Generalization of Abrams' law

Considering cement based composites as chemically bonded ceramics (CBC) the consequent strength development with age is essentially a constant volume solidification process, such that the hydrated gel particles fill the space resulting in the compatible gel space ratios. Analysis has been done of the extensively used graphical method of mix design (British method of mix design) i.e., the relation between the compressive strength and the free water - cement ratio. By considering the strength (S) at w/c 0.5 (S-0.5) as the reference state to reflect the synergetic effects between constituents of concrete a generalized relationship obtained is of the form {S/S-0.5} = a + b {1/(w/c)}.