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A model based on a cluster of four atoms has been used to obtain higher-order conditional probabilities that describe the atomic correlations in Al–In, Ag–In and In–Sb liquid alloys. Using the value of the ordering energy obtained from the model, some thermodynamic quantities such as Gibbs energy of mixing and concentration-concentration fluctuations in the long wavelength limit were calculated for these alloys. Our study of the energetics of these liquid alloys reveals that while In–Sb and Ag–In are both chemically ordered or heterocoordinated systems, Al–In is a segregating system. Furthermore, the degree of order in liquid In–Sb alloys is higher than that in liquid Ag–In alloys.

The Lebowitz’s solution of the direct correlation function for binary mixtures with a square well attractive tail has been used to model the structure factors of Cu–Si and Ni–Si molten alloys. The computed total structure factors compare favourably with experiment. Results from structural studies indicate a need for a study of ordering phenomena in the system. This has been done by evaluating the long wavelength limit of the concentration-concentration fluctuations Scc(0).

A model based on the existence of self-associates has been used to compute bulk thermodynamic properties of Bi –Cd, In –Pb, and Ni – Pd binary liquid alloys. Also, a statistical mechanics model has been employed to calculate the surface properties of these three alloys. Our study reveals that the degree of phase separation increases in the order Bi –Cd, In–Pb and Ni –Pd. Essentially, we find that Bi –Cd, like Au–Bi and Bi –Sb alloys, does not belong exclusively to the class of either segregating systems or to the short-range ordered alloys.

AbstractWe introduce and discussarecent type of fibrewise topological spaces, namely fibrewise soft bitopological spaces. Also, we introduce the concepts of fibrewise closed soft bitopological spaces, fibrewise open soft bitopological spaces, fibrewise locally sliceable soft bitopological spaces and fibrewise locally sectionable soft bitopological spaces. Furthermore, we state and prove several propositions concerning these concepts.

Sensitization to major histocompatibility complex (MHC) alloantigens is critical in transplantation rejection. The mechanism of sensitization to minor histocompatibility antigens (Mi-HAg) has not been thoroughly explored. We used a mouse model of allosensitization to Mi-HAg to study the Mi-HAg sensitization barrier in bone marrow transplantation (BMT). AKR mice were sensitized with MHC congenic Mi-HAg disparate B10.BR skin grafts. Adaptive humoral (B-cells) and cellular (T cells) responses to Mi-HAg are elicited. In subsequent BMT, only 20 of sensitized mice engrafted, while 100 of unsensitized mice did. In vivocytotoxicity assays showed that Mi-HAg sensitized AKR mice eliminated CFSE labeled donor splenocytes significantly more rapidly than naïve AKR mice but less rapidly than MHC-sensitized recipients. Sera from Mi-HAg sensitized mice also reacted with cells from other mouse strains, suggesting that Mi-HAg peptides were broadly shared between mouse strains. The production of anti-donor-Mi-HAg antibodies was totally prevented in mice treated with anti-CD154 during skin grafting, suggesting a critical role for the CD154:CD40 pathway in B-cell reactivity to Mi-HAg. Moreover, anti-CD154 treatment promoted BM engraftment to 100 in recipients previously sensitized to donor Mi-HAg. Taken together, Mi-HAg sensitization poses a significant barrier in BMT and can be overcome with CD154:CD40 costimulatory blockade.

We investigate the effects of temperature and density on the single-particle and many-particle coefficients as well as on the structures of homogenous systems in which the particles are assumed to interact via a continuous soft sphere potential in the microcanonical ensemble. The pair distribution function and therefore the structures of the systems studied are affected by temperature close to and above the melting point through migrations of atoms from the first shell in the pair distribution function.

Abstract: The structures and autocorrelation functions of Al and Mg in the liquid state are investigated through the pair distribution functiong(r), the diffusion coefficients as well as the shear viscosity via the Green-Kubo and Einstein relations. From the structure and the Enskog relation we determined the frequency of collisions of atoms in the first shell ofg(r) in the systems. We also discovered that the packing fraction of Lennard-Jones liquids should be approximately half the reduced density value. This approximation is accurate to within 99%. The temperature dependence of the pair distribution function and the atomic mean square displacement are investigated by performing simulations at various experimental temperatures and corresponding densities. The structures of the systems are affected by temperature via movements of atoms in the first minimum ofg(r). The Lennard-Jones model shows that density dependence of the shear viscosity is in agreement with what is expected of simple liquids in the range of investigated temperatures and densities. In the gas limit, the Stoke-Einstein relationDη =K BT /2πσ is grossly overestimated by Lennard-Jones model. This could not be attributed to deficiencies in the model, as other investigators using first principle method could not obtain the gas limit of the Stoke-Einstein relation.

The solution of the Percus-Yevick (PY) equation for a binary mixture with a square well potential as a perturbation has been applied to the study of the Pb-Bi molten alloy system. The partial structure factors in the long wavelength limit is calculated and used to evaluate the long wavelength limit of the concentration-concentration fluctuations Scc(0). This has in turn been used to obtain the Warren-Cowley short range order parameter α1 and the chemical diffusion D. The calculations indicate compound forming tendencies in Pb-Bi molten alloys with greater magnitude at low atomic fraction of Bismuth.

Transmission of human immunodeficiency virus (HIV) in North America and Europe occurs most commonly through the rectal mucosa during homosexual intercourse. The simian immunodeficiency virus (SIV) macaque model has been used to investigate rectal immunization. The vaccine used was a recombinant SIV gag p27 expressed as hybrid Ty virus-like particles (Ty-VLP). Sequential ororectal (OR) mucosal immunization was compared with i.m. immunization. Whereas both routes of immunization induced serum IgA and IgG p27 antibodies, only OR immunization induced rectal secretory IgA antibodies. Specific CD4+ T-cell proliferative responses to stimulation with p27 were found after i.m. immunization only in the blood and spleen, but after OR immunization they were found in the internal iliac and inferior mesenteric lymph nodes in addition to the blood and spleen. T-cell epitope mapping of the proliferative responses of short-term cell lines (STCLs) grown from peripheral blood or lymphoid cells revealed a major epitope within the polypeptide 121-150 after either route of immunization. Two minor T-cell epitopes were found within peptide 41-80 in STCLs from splenic and circulating cells. B-cell epitope mapping of serum or biliary IgA and IgG antibodies revealed two overlapping or adjacent immunodominant epitopes to the T-cell epitopes within the polypeptides 121-170 and 51-90. The results suggest that rectal augmented by oral immunization with a recombinant particulate antigen in nonhuman primates elicits secretory IgA and to a lesser extent IgG responses in the draining lymph nodes and the rectal mucosa, whereas systemic immunization targets predominantly splenic and circulating T- and B-cell responses. These findings may have important implications in the strategy of designing vaccines in prevention of homosexual transmission of HIV infection.

The differential heating between land and sea is incorporated into the theory of atmospheric tides. This involves the representation of the land and sea distribution by a set of Fourier series.

Human immunodeficiency virus (HIV) can be transmitted through infected seminal fluid or vaginal or rectal secretions during heterosexual or homosexual intercourse. To prevent mucosal transmission and spread to the regional lymph nodes, an effective vaccine may need to stimulate immune responses at the genitourinary mucosa. In this study, we have developed a mucosal model of genital immunization in male rhesus macaques, by topical urethral immunization with recombinant simian immunodeficiency virus p27gag, expressed as a hybrid Ty virus-like particle (Ty-VLP) and covalently linked to cholera toxin B subunit. This treatment was augmented by oral immunization with the same vaccine but with added killed cholera vibrios. Polymeric secretory immunoglobulin A (sIgA) and IgG antibodies to p27 were induced in urethral secretions, urine, and seminal fluid. This raises the possibility that the antibodies may function as a primary mucosal defense barrier against SIV (HIV) infection. The regional lymph nodes which constitute the genital-associated lymphoid tissue contained p27-specific CD4+ proliferative and helper T cells for antibody synthesis by B cells, which may function as a secondary immune barrier to infection. Blood and splenic lymphocytes also showed p27-sensitized CD4+ T cells and B cells in addition to serum IgG and IgA p27-specific antibodies; this constitutes a third level of immunity against dissemination of the virus. A comparison of genito-oral with recto-oral and intramuscular routes of immunization suggests that only genito-oral immunization elicits specific sIgA and IgG antibodies in the urine, urethra, and seminal fluid. Both genito-oral and recto-oral immunizations induced T-cell and B-cell immune responses in regional lymph nodes, with preferential IgA antibody synthesis. The mucosal route of immunization may prevent not only virus transmission through the genital mucosa but also dissemination and latency of the virus in the draining lymph nodes.

An experimental study of turbulent water flow through abrupt contractions was carried out in order to determine the detailed flow field. Wall static pressure measurements enabled the calculation of pressure loss coefficients for a range of contraction area ratios from 0.13 to 0.67 over a Reynolds number range of 40000–200000. The effect of variations in contraction sharpness was also established. Measurements of mean velocities and turbulence intensities were made using a two-component laser Doppler anemometer for one area ratio of 0.332 to establish the detailed flow features.

Using barium, for which results that compare favourably with experiment have been obtained, the effect on the lattice dynamical model parameters of a body centred cubic metal of explicitly imposing the crystal equilibrium condition on various ion-ion coupling schemes when used with the modified electron-ion interaction scheme of Bhatia has been studied. When the equilibrium condition is not used, the calculated model parameters lose their physical significance with the result that at equilibrium, the sum of the ionic and electronic pressures is not zero. This inconsistency is removed when the equilibrium condition is explicitly imposed on the models. It is not meaningful to compare the two results with and without the equilibrium condition imposed, not only because the imposition of the equilibrium condition reduces the number of independent parameters of the models by one, but also because the results apply to different states of the crystal. Also the comparison of calculated model parameters and measured quantities such as phonon frequencies make sense only when both are determined for the same state of the crystal. This condition is satisfied only when the equilibrium condition, which has unfortunately been ignored in most lattice dynamical studies, is explicitly imposed on lattice dynamical models.

A phenomenological model which combines the axially symmetric ion-ion interaction with the electron-ion interaction scheme of Bhatia has been successfully used to calculate the phonon dispersion curves of bcc Ba. In particular, when the elastic constants determined by Mizukiet alare used as input data, the model successfully reproduces the anomalous feature of the dispersion curves measured by them. On the other hand, when the elastic constants determined by Buchenauet alare used, the model produces a cross over of the longitudinal and transverse branches in the [100] direction, a feature not established in their measurements. Thus the features of the dispersion curves in the [100] direction which is due to the hybridization of thesanddstates are evident in the measured elastic constants and are consistent with the values of C12-C44.

The computed values of the temperature dependent electrical resistivity is presented for the alkaline earth metals Ca, Sr and Ba. Numerical values of the mean free paths obtained using a finite mean free path approach is also reported. The structure factor has been evaluated using experimental values for the phonon spectra while local model potentials were used for the form factors. Our numerical results compare favourably with experiments.

We have calculated, in an empirical form, the temperature variation of the thermopower of alkali metals in the 50–300 K region and at their melting points using the finite mean free path correction to the Ziman formulation as suggested by Ferraz and March. The structure factor was evaluated using the phenomenological models of Sharma-Joshi and Krebbs. Three different types of form factors were used in order to give a comparative test of the applied theories. Our results agree to a considerable extent with available experimental results. Finally, we give a brief discussion of some of the factors that could affect the thermopower of the metals investigated.

Bifunctional ligands, viz., α-, β-, and γ-ketophosphonic acids, wherein a carbonyl group is systematically separated from a phosphoryl group with methylene moieties, have been immobilized on cross-linked polystyrene beads via the Arbusov and Perkow reactions. Studies with Eu(III), Cu(II), Pb(II), Cd(II), Co(II), and Ag(I) in various acid solutions show that under conditions where coordination is the dominant mode of metal ion sorption, the α-ketophosphonate complexes greater levels of metal ions than the β-ketophosphonate and both complex far greater levels of ions than the γ-ketophosphonate. The latter performs in a manner comparable to the monofunctional phosphonic acid resin. The results are consistent with intra-ligand cooperation being an important factor in the design of polymer-supported reagents for the complexation of high levels of metal ions.

We present the results of calculations of the structure factorS(q) of some liquid 3dtransition metals using the self consistent hybridized mean spherical approximation (HMSA) integral equation. The local pseudopotential used is composed of the empty core model and a part that takes care of s-d mixing through an inverse scattering approach to model the interionic pair potential. The results presented are in very good agreement with experiment for most of the systems investigated near freezing, as well as for the noble metals Cu, Ag and Au, thus, confirming the reliability of the pseudopotential in the present integral equation scheme.

Laboratory studies were conducted, using a millet grain bait, to estimate the minimum concentration of 4-aminopyridine (4-AP) needed to produce abnormal behaviour and distress calls in house sparrows (Passer domesticus L.). Three concentrations (0.50, 0.75 and 1.0%) were tested and three doses (6, 18 and 30 mg) were administered by forcing birds to eat one, three or five treated grains. There were differences among the three concentrations in time from dosing to first distress call and in abnormal behaviour, but not in the duration and number of distress calls. At each concentration different doses had different effects. Males emitted more and higher pitched distress calls than did females. It is concluded that concentrations of 0.75 and 1.0% could be effective in reducing damage to cereal crops by house sparrows in Pakistan. The calculated LD50 was 5.9 mg/kg (4.5-7.7 mg/kg, 95% confidence limits).