In this work the nonaxial ordering and spin relaxation of PD-Tempone spin probe in several liquid crystalline solvents exhibiting smectic A and B phases were studied utilizing methods previously employed by Polnaszek and Freed for the study of nematic liquid crystals. The results reported here for the isotropic and nematic phases are generally in accord with those obtained previously. An analysis of isotropic hyperfine shifts, changes in the ordering tensor, and anomalous relaxation behavior in the smectic phases suggest a model in which the PD-tempone probes are partially expelled from the dipolar region of the liquid crystalline molecules toward the more flexible hydrocarbon end chains as a result of the packing of the smetic layers, and concomitantly the probes increasingly experience a slowly relaxing local structure (SRLS) in a cavity-like location. Differences in observations from different types of smectic liquid crystals are interpreted in terms of their differing structures based on X-ray studies. It is shown that the angular dependent line widths in the smectic phases are significantly affected by the size and shape of the sample. These inhomogeneous broadening effects are discussed in detail in terms of static distortions of the smectic layering induced by wall effects and magnetic-field induced torques, and are in reasonable agreement with predictions of a simple model. The residual homogeneous widths are discussed in terms of combined models of anisotropic rotation and anisotropic viscosity as well as associated SRLS models. For the former case, the problem of defining the rotational diffusion tensor, which must be time dependent in any axis system, is discussed in some detail.

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Lattice parameters of rutile and anatase were determined from 30" to 6 5 0 T and from 28O to 712OC, respectively, using a high-temperature powder camera. These data were used to evaluate the coefficients of thermal expansion of rutile and anatase. The temperature dependence of the coefficients, aI, and parallel and perpendicular to the principal axis, respectively, are represented by the equations:Rutile: a , , = 8.816 X The relative magnitudes of the coefficients of thermal expansion of these polymorphs are explained in terms of the interionic distances.

Habitual chewing of pan masala/gutkha is associated with earlier presentation of oral submucous fibrosis than betelquid use. Factors which may be responsible for these differences are the tobacco content, the absence of the betel leaf and its carotenes and the much higher dry weight of pan masala/gutkha.

This study describes the relative effect on the permanent magnet characteristics viz. remanence (Br), intrinsic coercivity (Hci), Curie temperature (TC), and rectangularity of the intrinsic demagnetization curve, when Al, Cu, Ga, and Nb are added individually to NdFeB. Each elemental addition causes significant improvement in Hci but the level of improvement differs from one additive element to the other. The addition of Nb is favored over other elements for realizing maximum enhancement in Hci and rectangularity of the demagnetization curve. The microstructural features of the sintered samples of NdFeB with elemental addition show the formation of a new phase, in addition to the phases (φ,η, and Nd-rich) generally found in the ternary sample. The factors influencing the permanent magnet characteristics of sintered samples are the distribution of the Nd-rich phase in the intergranular region, the size and distribution of the minor phases at the grain junctions, the formation and distribution of new phases due to alloying addition, and the solubility of the dopant element in various phases coexisting in the sample.

A study is reported of the ESR line shapes in the slow-tumbling region for a cholestane (CSL) spin probe in nematic phase V solution. The line shapes are analyzed in terms of the Polnaszek, Bruno, Freed theory for spectra from slowly tumbling probes in ordered fluids. Rather good agreement with experiment is obtained from the slower motional spectra (rR > 5 X 10"9 s where rR is the rotational correlation time) utilizing a single term ordering potential. For these slow-motional spectra, effects of proton inhomogeneous broadening are relatively small. It is shown in this study on CSL that for rR > 10™9 s a motional-narrowing theory will lead to erroneous predictions for rR and ordering that become more serious as rR increases. The previous application of motional-narrowing theory by other workers to this probe is discussed in this light. The effects of various other factors upon the spectral simulations are discussed. In particular, it is shown that the spectra for this highly ordered probe should not be very sensitive to various aspects of model dependence of the reorientational motion as discussed in part I nor to effects from director fluctuations. Also the slower tumbling spectra are rather insensitive to anisotropy in tr (but the anisotropy may be determined from the faster motional spectra).Nevertheless, contributions from these effects could modify somewhat the values of rR and ordering that are obtained. The slow tumbling spectra are also insensitive to the angle of tilt of the nitroxide magnetic-tensor principal axis system in the x~y plane with respect to the molecular orientational axes. Our results show that the tilt angle of the magnetic z axis should not be very different from 0°.

The mutual interactions of measles vaccine and vitamin A dose when administered simultaneously to 9 month old infants are explored in this study. One hundred healthy infants of 9 months of age received EZ strain of measles vaccine in the routine immunization clinic along with either 100,000 IU of vitamin A or a placebo orally. Blood samples were collected before and 4 weeks after intervention. They were coded and analysed for serum retinol and Hemagglutination Inhibition (HI) antibodies to measles. Ninety five per cent of the infants were seronegative to measles prior to vaccination with a seroconversion rate of 63% in the control group and a significantly higher percent of 83.7% in the experimental group (P < 0.01). Seroconversion was not related to initial serum retinol levels in either of the groups. 42% of infants had serum retinol levels less than 20 ug/dl before administration of the vaccine and both the groups showed improvement in vitamin A status following intervention, the increase being significant in the experimental group (from 22.4 +/- 1.32 to 26.0 +/- 1.07; P < 0.05). The results indicate that majority of the infants at 9 months of age were seronegative to measles. Seroconversion to measles vaccine in the routine immunization clinics was low. Simultaneous administration of vitamin A and measles vaccine had beneficial effects on vitamin A status as well as seroconversion rates to the vaccine in 9 months old infants.