Inhibition of nuclear protein import by a monoclonal antibody against a novel class of nuclear pore proteins

Nuclear import of proteins is mediated by the nuclear pore complexes in the nuclear envelope and requires the presence of a nuclear localization signal (NLS) on the karyophilic protein. In this paper, we describe studies with a monoclonal antibody, Mab E2, which recognizes a class of nuclear pore proteins of 60-76 kDa with a common phosphorylated epitope on rat nuclear envelopes. The Mab Ea-reactive proteins fractionated with the relatively insoluble pore complex-containing component of the envelope and gave a finely punctate pattern of nuclear staining in immunofluorescence assays. The antibody did not bind to any cytosolic proteins. Mab E2 inhibited the interaction of a simian virus 40 large T antigen NLS peptide with a specific 60-kDa NLS-binding protein from rat nuclear envelopes in photoaffinity labeling experiments. The antibody blocked the nuclear import of NLS-albumin conjugates in an in vitro nuclear transport assay with digitonin-permeabilized cells, but did not affect passive diffusion of a small nonnuclear protein, lysozyme, across the pore. Mab E2 may inhibit protein transport by directly interacting with the 60-kDa NLS-binding protein, thereby blocking signal-mediated nuclear import across the nuclear pore complex. (C) 1994 Academic Press, Inc.

Fast algorithm for data exchange in reconfigurable tree structures

This paper presents a fast algorithm for data exchange in a network of processors organized as a reconfigurable tree structure. For a given data exchange table, the algorithm generates a sequence of tree configurations in which the data exchanges are to be executed. A significant feature of the algorithm is that each exchange is executed in a tree configuration in which the source and destination nodes are adjacent to each other. It has been proved in a theorem that for every pair of nodes in the reconfigurable tree structure, there always exists two and only two configurations in which these two nodes are adjacent to each other. The algorithm utilizes this fact and determines the solution so as to optimize both the number of configurations required and the time to perform the data exchanges. Analysis of the algorithm shows that it has linear time complexity, and provides a large reduction in run-time as compared to a previously proposed algorithm. This is well-confirmed from the experimental results obtained by executing a large number of randomly-generated data exchange tables. Another significant feature of the algorithm is that the bit-size of the routing information code is always two bits, irrespective of the number of nodes in the tree. This not only increases the speed of the algorithm but also results in simpler hardware inside each node.

On the out of phase appearance of large-scale diffuse magnetic field of the sun with respect to sunspots

We assume the large-scale diffuse magnetic field of the Sun to originate from the poloidal component of a dynamo operating at the base of the convection zone, whereas the sunspots are due to the toroidal component. The evolution of the poloidal component is studied to model the poleward migration of the diffuse field seen on the solar surface and the polar reversal at the time of sunspot maxima (Dikpati and Choudhuri 1994, 1995).

SiO Maser Emission and the Intrinsic Properties of Mira Variables

This paper presents observations of SiO maser emission from 161 Mira variables distributed over a wide range of intrinsic parameters like spectral type, bolometric magnitude and amplitude of pulsation. The observations were made at 86.243 GHz, using the 10.4 m millimeter-wave telescope of the Raman Research Institute at Bangalore, India. These are the first observations made using this telescope. From these observations, we have established that the maser emission is restricted to Miras having mean spectral types between M6 and M10. The infrared period-luminosity relation for Mira variables is used to calculate their distances and hence estimate their maser luminosities from the observed fluxes. The maser luminosity is found to be correlated with the bolometric magnitude of the Mira variable. On an H-R diagram, the masing Mira variables are shown to lie in a region distinct from that for the non-masing ones.

Implications of the recent high statistics determination of the pion electromagnetic form factor in the timelike region

The recently evaluated two-pion contribution to the muon g - 2 and the phase of the pion electromagnetic form factor in the elastic region, known from pi pi scattering by Fermi-Watson theorem, are exploited by analytic techniques for finding correlations between the coefficients of the Taylor expansion at t = 0 and the values of the form factor at several points in the spacelike region. We do not use specific parametrizations, and the results are fully independent of the unknown phase in the inelastic region. Using for instance, from recent determinations, < r(pi)(2)> = (0.435 +/- 0.005) fm(2) and F(-1.6 GeV2) = 0.243(-0.014)(+0.022), we obtain the allowed ranges 3.75 GeV-4 less than or similar to c less than or similar to 3.98 GeV-4 and 9.91 GeV-6 less than or similar to d less than or similar to 10.46 GeV-6 for the curvature and the next Taylor coefficient, with a strong correlation between them. We also predict a large region in the complex plane where the form factor cannot have zeros.

Some observations on the ignition of composite solid propellants

Heat-up times derived from studies on the ignition characteristics of a few model composite solid propellants, containing polystyrene, carboxy-terminated polybutadiene, plasticised polyvinyl chloride and polyphenol formaldehyde as binders, show that they are directly proportional to the mass of the sample and inversely proportional to the hear flux. Propellant weight-loss prior to ignition and high pressure ignition temperature data on the propellants, ammonium per chlorate, and binders show that the ignition is governed by the gasification of the binder pyrolysis products. The activation energy for the gasification of the pyrolysed polymer products corresponds to their ignition behaviour suggesting that propellant ignition is controlled by the binder.

Tie lines and activities in the system NiO-MgO-SiO2 at 1373 K

The isothermal section of the phase diagram for the system NiO-MgO-SiO2 at 1373 K is established, The tie lines between (NiXMg1-X)O solid solution with rock salt structure and orthosilicate solid solution (NiYMg1-Y)Si0.5O2 and between orthosilicate and metasilicate (NiZMg1-Z)SiO3 crystalline solutions are determined using electron probe microanalysis (EPMA) and lattice parameter measurement on equilibrated samples, Although the monoxides and orthosilicates of Ni and Mg form a continuous range of solid solutions, the metasilicate phase exists only for 0 < Z < 0.096, The activity of NiO in the rock salt solid solution is determined as a function of composition and temperature in the range of 1023 to 1377 K using a solid state galvanic cell, The Gibbs energy of mixing of the monoxide solid solution can be expressed by a pseudo-subregular solution model: Delta G(ex) = X(1 - X)[(-2430 + 0.925T)X + (-5390 + 1.758T)(1 - X)] J/mol, The thermodynamic data for the rock salt phase are combined with information on interphase partitioning of Ni and Mg to generate the mixing properties for the orthosilicate and the metasilicate solid solutions, The regular solution model describes the orthosilicate and the metasilicate solid solutions at 1373 K within experimental uncertainties, The regular solution parameter Delta G(ex)/Y(1 - Y) is -820 (+/-70) J/mol for the orthosilicate solid solution, The corresponding value for the metasilicate solid solution is -220 (+/-150) J/mol, The derived activities for the orthosilicate solid solution are discussed in relation to the intracrystalline ion exchange equilibrium between M1 and M2 sites. The tie line information, in conjunction with the activity data for orthosilicate and metasilicate solid solutions, is used to calculate the Gibbs energy changes for the intercrystalline ion exchange reactions, Combining this with the known data for NiSi0.5O2, Gibbs energies of formation of MgSi0.5O2, MgSiO3, and metastable NiSiO3 are calculated, The Gibbs energy of formation of NiSiO3, from its component oxides, is equal to 7.67 (+/-0.6) kJ/mol at 1373 K.

Nanocomposite microstructure in a melt spun Al-Cu-Zr alloy

Rapid solidification of a ternary Al-Cu-Zr alloy results in a nanocomposite microstructure. In this study, melt spinning a Al82Cu15Zr3 alloy has resulted in the combined occurrence of, (a) 0.5 mu m sized grains of Al solid solution and (b) fine grains (10-20 nm) of intermetallic Al2Cu (theta) and alpha-Al, along side each other. The larger alpha-Al grains contain nanometric GP zones, with the Zr addition resulting in a grain refinement. In the other type of microstructure Zr promotes simultaneous nucleation of nanosized grains of the two equilibrium phases, Al2Cu and alpha-Al. Both these lead to a very high hardness of similar to 540 VHN for this alloy and can be used as a candidate for a high strength alloy with good ductility at a low strain rate.

Phase evolution and densification of spray pyrolysed ZrO2-Al2O3 powders

Devitrification of spray pyrolysed, amorphous ZrO2-Al2O3 solid solution produces nanocrystalline microstructures (grain sizes 10-20 nm). In this study, spray pyrolysed amorphous ZrO2-40 mol% Al2O3 powder displayed good sinterability during decomposition, after spraying, of the nitrate precursors up to 1023K. Hot pressing of fully pyrolysed, pre-sintered (more than 70% dense) pellets at 923K and 750 MPa produced an amorphous pellet with less than 2% porosity. The results indicate the possibility of producing dense, amorphous pellets that can be heat treated further to produce nanocrystalline microstructures conducive for superplasticity.

Studies of ternary Li2SO4-Li2O-P2O5 glasses

Glasses in a wide range of compositions in the ternary system xLi(2)SO(4-y)Li(2)O-zP(2)O(5) where x ranges from 0 to 30 mol%, y ranges from 35 to 55 mol% and z ranges from 25 to 50 mol% have been prepared and their properties measured using infra-red, Raman, and P-31 magic angle spinning nuclear magnetic resonance spectroscopic techniques. We conclude that a random close packing of phosphate and sulphate ions which also leads to formation of connected voids in the structure is consistent with our data. There is also evidence for formation of condensed sulphate-phosphate species in the liquid which may be retained in the glass structure. (C) 1999 Elsevier Science B.V. All rights reserved.

Calorimetric studies on 2TeO(2)-V2O5 glasses

Glasses of the composition 2TeO(2)-V2O5 were fabricated via the conventional melt-quenching technique. The amorphous and the glassy nature of the as-quenched samples were confirmed by X-ray powder diffraction (XRD) and differential scanning calorimetry (DSC), respectively. The glass transition and crystallization parameters were evaluated under non-isothermal conditions using DSC. X-ray diffraction studies confirmed the presence of partially oriented crystallites in the heat-treated glasses. Kauzmann temperature (lower bound for the kinetically observed glass transition) was deduced from the heating rate dependent glass transition and crystallization temperatures.

Developments in quantum information processing by nuclear magnetic resonance: Use of quadrupolar and dipolar couplings

Use of dipolar and quadrupolar couplings for quantum information processing (QIP) by nuclear magnetic resonance (NMR) is described. In these cases, instead of the individual spins being qubits, the 2(n) energy levels of the spin-system can be treated as an n-qubit system. It is demonstrated that QIP in such systems can be carried out using transition-selective pulses, in (CHCN)-C-3, (CH3CN)-C-13, Li-7 (I = 3/2) and Cs-133 (I = 7/2), oriented in liquid crystals yielding 2 and 3 qubit systems. Creation of pseudopure states, implementation of logic gates and arithmetic operations (half-adder and subtractor) have been carried out in these systems using transition-selective pulses.

Dynamics of crystal size distributions with size-dependent rates

The growth and dissolution dynamics of nonequilibrium crystal size distributions (CSDs) can be determined by solving the governing population balance equations (PBEs) representing reversible addition or dissociation. New PBEs are considered that intrinsically incorporate growth dispersion and yield complete CSDs. We present two approaches to solving the PBEs, a moment method and a numerical scheme. The results of the numerical scheme agree with the moment technique, which can be solved exactly when powers on mass-dependent growth and dissolution rate coefficients are either zero or one. The numerical scheme is more general and can be applied when the powers of the rate coefficients are non-integers or greater than unity. The influence of the size dependent rates on the time variation of the CSDs indicates that as equilibrium is approached, the CSDs become narrow when the exponent on the growth rate is less than the exponent on the dissolution rate. If the exponent on the growth rate is greater than the exponent on the dissolution rate, then the polydispersity continues to broaden. The computation method applies for crystals large enough that interfacial stability issues, such as ripening, can be neglected. (C) 2002 Elsevier Science B.V. All rights reserved.

Crystal and molecular structure of synthetic cholesterol compounds vitamin D3-analogues (I) 24(S)-hydroxy coprastan-3-one & (II) 24(R)-hydroxy coprastan-3-one

The title compound I (24-(S)-Hydroxy Coprastan-3-one) crystallises in orthorhombic space group P2(1)2(1)2(1) with Z = 4. The unit cell dimensions are a = 6.701(2)Angstrom, b = 11.506(8)Angstrom, c = 32.183(4)Angstrom, V = 2481(2)Angstrom (3), D-cal = 1.077 Mg/m(3). The tide compound II (24-(R)-Hydroxy Coprastan-3-one) crystallises in orthorhombic space group P212121 with two molecules per assymetric unit and with Z = 8. The Unit cell dimensions are a = 10.954(2)Angstrom, b = 21.757(6)Angstrom, c = 21.130(7)Angstrom, V = 5035.0(2)Angstrom (3), D-cal = 1.062 Mg/m(3). In compound I and in both the molecules of compound II, the rings A, B & C are in chair conformation and the five membered ring D is in envelope conformation. The priority sequence attached to the chiral carbon C24 has "S" designation in compound I and "R" designation in compound II. The structures are stabilized by C-H . . .O and O-H---O hydrogen bonds.

A comparative study of Pt/CeO2 catalysts for catalytic partial oxidation of methane to syngas for application in fuel cell electric vehicles

In the framework of a project aimed at developing a reliable hydrogen generator for mobile polymer electrolyte fuel cells (PEFCs), particular emphasis has been addressed to the analysis of catalysts able to assure high activity and stability in transient operations (frequent start-up and shut-down cycles). In this paper, the catalytic performance of 1 at.% Pt/ceria samples prepared by coprecipitation, impregnation and combustion, has been evaluated in the partial oxidation of methane. Methane conversion and hydrogen selectivity of 96 and 99%, respectively, associated with high stability during 100h of reaction under operative conditions (start-up and shut-down cycles), have been obtained. (C) 2002 Elsevier Science B.V. All rights reserved.