1,725 research outputs found

    Chemistry and Toxicology of Sulphur Mustard- A Review

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    Bis (2-chloroethyl) sulphide commonly known as sulphur mustard (SM) is highly reactive bifunctional compound, documented as antimitotic, mutagenic, carcinogenic, teratogenic and cytotoxic agent. It is a powerful vesicant and has been employed as a chemical warfare agent. Skin, eyes and respiratory tract are the principal target organs and the deoxyribose nucleic acid (DNA) is the most important molecular target of SM toxicity. There is no specific antidote for SM injury .Treatment to SM toxicity is symptomatic

    Approximation Algorithms for Connected Maximum Cut and Related Problems

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    An instance of the Connected Maximum Cut problem consists of an undirected graph G = (V, E) and the goal is to find a subset of vertices S ⊆\subseteq V that maximizes the number of edges in the cut \delta(S) such that the induced graph G[S] is connected. We present the first non-trivial \Omega(1/log n) approximation algorithm for the connected maximum cut problem in general graphs using novel techniques. We then extend our algorithm to an edge weighted case and obtain a poly-logarithmic approximation algorithm. Interestingly, in stark contrast to the classical max-cut problem, we show that the connected maximum cut problem remains NP-hard even on unweighted, planar graphs. On the positive side, we obtain a polynomial time approximation scheme for the connected maximum cut problem on planar graphs and more generally on graphs with bounded genus.Comment: 17 pages, Conference version to appear in ESA 201

    Elementary Quantum Mechanics in a Space-time Lattice

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    Studies of quantum fields and gravity suggest the existence of a minimal length, such as Planck length \cite{Floratos,Kempf}. It is natural to ask how the existence of a minimal length may modify the results in elementary quantum mechanics (QM) problems familiar to us \cite{Gasiorowicz}. In this paper we address a simple problem from elementary non-relativistic quantum mechanics, called "particle in a box", where the usual continuum (1+1)-space-time is supplanted by a space-time lattice. Our lattice consists of a grid of λ0×τ0\lambda_0 \times \tau_0 rectangles, where λ0\lambda_0, the lattice parameter, is a fundamental length (say Planck length) and, we take τ0\tau_0 to be equal to λ0/c\lambda_0/c. The corresponding Schrodinger equation becomes a difference equation, the solution of which yields the qq-eigenfunctions and qq-eigenvalues of the energy operator as a function of λ0\lambda_0 . The qq-eigenfunctions form an orthonormal set and both qq-eigenfunctions and qq-eigenvalues reduce to continuum solutions as λ0→0. \lambda_0 \rightarrow 0 . The corrections to eigenvalues because of the assumed lattice is shown to be O(λ02).O(\lambda_0^2). We then compute the uncertainties in position and momentum, Δx,Δp\Delta x, \Delta p for the box problem and study the consequent modification of Heisenberg uncertainty relation due to the assumption of space-time lattice, in contrast to modifications suggested by other investigations such as \cite{Floratos}

    Generalized symmetric nonextensive thermostatistics and q-modified structures

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    We formulate a convenient generalization of the q-expectation value, based on the analogy of the symmetric quantum groups and q-calculus, and show that the q->q^{-1} symmetric nonextensive entropy preserves all of the mathematical structure of thermodynamics just as in the case of non-symmetric Tsallis statistics. Basic properties and analogies with quantum groups are discussed.Comment: 9 pages, 1 figure. To appear in Mod. Phys. Lett.

    Pressure-induced amorphization and polyamorphism in one-dimensional single crystal TiO2 nanomaterials

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    The structural phase transitions of single crystal TiO2-B nanoribbons were investigated in-situ at high-pressure using the synchrotron X-ray diffraction and the Raman scattering. Our results have shown a pressure-induced amorphization (PIA) occurred in TiO2-B nanoribbons upon compression, resulting in a high density amorphous (HDA) form related to the baddeleyite structure. Upon decompression, the HDA form transforms to a low density amorphous (LDA) form while the samples still maintain their pristine nanoribbon shape. HRTEM imaging reveals that the LDA phase has an {\alpha}-PbO2 structure with short range order. We propose a homogeneous nucleation mechanism to explain the pressure-induced amorphous phase transitions in the TiO2-B nanoribbons. Our study demonstrates for the first time that PIA and polyamorphism occurred in the one-dimensional (1D) TiO2 nanomaterials and provides a new method for preparing 1D amorphous nanomaterials from crystalline nanomaterials.Comment: 4 figure

    Generalized thermodynamics of q-deformed bosons and fermions

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    We study the thermostatistics of q-deformed bosons and fermions obeying the symmetric algebra and show that it can be built on the formalism of q-calculus. The entire structure of thermodynamics is preserved if ordinary derivatives are replaced by an appropriate Jackson derivative. In this framework, we derive the most important thermodynamic functions describing the q-boson and q-fermion ideal gases in the thermodynamic limit. We also investigate the semi-classical limit and the low temperature regime and demonstrate that the nature of the q-deformation gives rise to pure quantum statistical effects stronger than undeformed boson and fermion particles.Comment: 8 pages, Physical Review E in pres

    LP-Based Approximation Algorithms for Facility Location in Buy-at-Bulk Network Design

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    Abstract We study problems that integrate buy-at-bulk network design into the classical (connected) facility location problem. In such problems, we need to open facilities, build a routing network, and route every client demand to an open facility. Furthermore, capacities of the edges can be purchased in discrete units from K different cable types with costs that satisfy economies of scale. We extend the linear programming frame-work of Talwar [IPCO 2002] for the single-source buy-at-bulk problem to these variants and prove integrality gap upper bounds for both facility location and connected facility location buy-at-bulk problems. For the unconnected variant we prove an integrality gap bound of O(K), and for the connected version, we get an improved bound of O(1).

    Multiple molecular forms of human lactoferrin. Identification of a class of lactoferrins that possess ribonuclease activity and lack iron-binding capacity

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    Lactoferrin (Lf), the major iron-binding component of milk, also a major constituent of the specific granules of neutrophils involved in antimicrobial activity and a glycoprotein thought to play a role in regulatory functions in the hematopoietic system as well as other physiologic activities, is shown to occur in three isoforms. One, Lf-alpha, binds iron; the other two, Lf-beta and Lf-gamma, express potent RNase activity, but do not bind iron. The three isoforms are very similar or identical in Mr, pI, partial proteolytic peptide patterns, NH2-terminal amino acid sequence, and reactivity with mAbs and polyclonal antisera against the RNase and Lf, respectively. The finding of structurally similar but enzymatically distinct forms of Lf may be related to the diverse functions of the molecule

    Mechanism of haematotoxicity induced by phenylhydrazine: a review

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    This work was carried out to show the effects of phenylhydrazine (PHZ) induced anaemic condition. Anaemic condition is defined as reduction in red blood cells (RBC) than normal number of red blood cells. The anti-anaemic activity can be studied using the changes in haematological parameters (PCV, RBC & Haemoglobin) influenced by PHZ [(40mg/kg p.o.)] in rats. PHZ, a potent chemical that causes different effects on different tissues at several levels. Administration of PHZ causes haemolytic anaemia, genotoxic effects and rose in iron absorption in spleen, liver and duodenum & causes change in iron metabolism. PHZ acts by activating immune response which triggers phagocytosis and also interfere with the binding of erythropoietin (EPO) receptors and further JAK-STAT pathway. PHZ also causes genotoxic effect by forming single strand DNA damage. In view of lipid peroxidation along with the formation of Thiobarbituric acid (TBA)-reactive malonyldialdehyde, it is recommend that PHZ induces anaemia as an outcome of peroxidation of  RBC membrane lipids and this effect may be a upshot of the autoxidation of the drug and the interaction of membrane lipids and oxygen radical

    Haematological Studies in High Altitude Natives at Plains and on Return to High Altitude

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    Haematologic studies were carried out in 20 high altitude natives during two months stay at plains (200 m) and on their return to an altitude of 3,500 m. Haemoglobin, erythrocyte count, haematocrit and reticulocyte count decreased rapidly on arrival to plains and attained minimum level by the end of fourth week. All these parameters increased rapidly on return to high altitude and were found to attain maximum values by 23rd day on return to high altitude. Mean cell volume and mean cell haemoglobin showed significant increase at altitude. Blood volume and red cell mass increased significantly at altitude. It is concluded that the high altitude natives of Ladakh were well adapted to hypoxic environment due to normocythaemic hypervolemia
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