The response of lichen growth to additions of distilled water, rainwater and water from a rock surface

Three lichen species were wetted in the field with distilled water, rainwater or water which had run off a rock surafce, during July 1974 to February 1975. The radial growth rate of Parmelia glabratula ssp. fuliginosa was not influenced by the wetting treatments. The radial growth rate of P. conspersa with the distilled water was greater than the control, rainwater and runoff treatments. The radial growth rate of Physcia orbicularis was lower with rainwater and runoff treatmentss than the control and distilled water treatment. These results may be explained by the effect of wetting on the carbon balance of the lichens and by the influence of water chemistry.

An examination of the calcium and strontium site distribution in bioactive glasses through isomorphic neutron diffraction, X-ray diffraction, EXAFS and multinuclear solid state NMR.

Strontium has been substituted for calcium in the glass series (SiO2)49.46(Na2O)26.38(P2O5)1.07(CaO)23.08x(SrO)x (where x = 0, 11.54, 23.08) to elucidate their underlying atomic-scale structural characteristics as a basis for understanding features related to the bioactivity. These bioactive glasses have been investigated using isomorphic neutron and X-ray diffraction, Sr K-edge EXAFS and solid state 17O, 23Na, 29Si, 31P and 43Ca magic-angle-spinning (MAS) NMR. An effective isomorphic substitution first-order difference function has been applied to the neutron diffraction data, confirming that Ca and Sr behave in a similar manner within the glass network, with residual differences attributed to solely the variation in ionic radius between the two species. The diffraction data provides the first direct experimental evidence of split Ca–O nearest-neighbour correlations in these melt quench bioactive glasses, together with an analogous splitting of the Sr–O correlations; the correlations are attributed to the metal ions correlated either to bridging or to non-bridging oxygen atoms. Triple quantum (3Q) 43Ca MAS NMR corroborates the split Ca–O correlations. Successful simplification of the 2 < r (A) < 3 region via the difference method has also revealed two distinct Na environments. These environments are attributed to sodium correlated either to bridging or to nonbridging oxygen atoms. Complementary multinuclear MAS NMR, Sr K-edge EXAFS and X-ray diffraction data supports the structural model presented. The structural sites present will be intimately related to their release properties in physiological fluids such as plasma and saliva, and hence the bioactivity of the material. Detailed structural knowledge is therefore a prerequisite for optimising material design.

Codon-precise, synthetic, antibody fragment libraries built using automated hexamer codon additions and validated through next generation sequencing

We have previously described ProxiMAX, a technology that enables the fabrication of precise, combinatorial gene libraries via codon-by-codon saturation mutagenesis. ProxiMAX was originally performed using manual, enzymatic transfer of codons via blunt-end ligation. Here we present Colibra™: an automated, proprietary version of ProxiMAX used specifically for antibody library generation, in which double-codon hexamers are transferred during the saturation cycling process. The reduction in process complexity, resulting library quality and an unprecedented saturation of up to 24 contiguous codons are described. Utility of the method is demonstrated via fabrication of complementarity determining regions (CDR) in antibody fragment libraries and next generation sequencing (NGS) analysis of their quality and diversity.

Mathematical Modeling and Simulation of Radial Temperature Profile of Strontium Bromide Lasers

For metal and metal halide vapor lasers excited by high frequency pulsed discharge, the thermal effect mainly caused by the radial temperature distribution is of considerable importance for stable laser operation and improvement of laser output characteristics. A short survey of the obtained analytical and numerical-analytical mathematical models of the temperature profile in a high-powered He-SrBr2 laser is presented. The models are described by the steady-state heat conduction equation with mixed type nonlinear boundary conditions for the arbitrary form of the volume power density. A complete model of radial heat flow between the two tubes is established for precise calculating the inner wall temperature. The models are applied for simulating temperature profiles for newly designed laser. The author’s software prototype LasSim is used for carrying out the mathematical models and simulations.

Low temperature sintering semiconducting barium strontium titanate

Low temperature sintering has become a very important research area in ceramics processing and sintering as a promising process to obtain grain size below 100nm. For electronic ceramics, low temperature sintering is particularly difficult, because not only the required microstructure but also the desired electronic properties should be obtained. In this dissertation, the effect of liquid sintering aids and particle size (micrometer and nanometer) on sintering temperature and Positive Temperature Coefficient Resistivity (PTCR) property are investigated for Ba1-xSrxTiO3 (BST) doped with 0.2-0.3mol% Sb3+ (x = 0.1, 0.2, 0.3, 0.4 and 0.5). Different sintering aids with low melting point are used as sintering aids to decrease the sintering temperature for micrometer size BST particles. Micrometer size and nanometer size Ba1-xSrxTiO 3 (BST) particles are used to demonstrate the particle size effect on the sintering temperature for semiconducting BST. To reduce the sintering temperature, three processes are developed, i.e. 1 using sol-gel nanometer size Sb3+ doped powders with a sintering aid; 2 using micrometer size powders plus a sintering aid; and 3 using nanometer size Sb3+ doped powders with sintering aids. Grain size effect on PTCR characteristics is investigated through comparison between micrometer size powder sintered pellets and nanometer size powder sintered pellets. The former has lower resistivity at temperatures below the Curie temperature (Tc) and high resistivity at temperatures above the Curie temperature (Tc) along with higher ρ max/ρmin ratio (ρmax is the highest resistivity at temperatures above Tc, ρmin is the lowest resistivity at temperatures below Tc), whereas the latter has both higher ρ max and ρmin. Also, ρmax/ρmin is smaller than that of pellets with larger grain size. The reason is that the solid with small grain size has more grain boundaries than the solid with large grain size. The contribution z at room temperature and high temperature and a lower ρmax/ρmin ratio value.

Life cycle of Deccan trap magma chambers: A crystal scale elemental and strontium isotopic investigation

The Deccan Trap basalts are the remnants of a massive series of lava flows that erupted at the K/T boundary and covered 1-2 million km2 of west-central India. This eruptive event is of global interest because of its possible link to the major mass extinction event, and there is much debate about the duration of this massive volcanic event. In contrast to isotopic or paleomagnetic dating methods, I explore an alternative approach to determine the lifecycle of the magma chambers that supplied the lavas, and extend the concept to obtain a tighter constraint on Deccan’s duration. My method relies on extracting time information from elemental and isotopic diffusion across zone boundaries in individual crystals. I determined elemental and Sr-isotopic variations across abnormally large (2-5 cm) plagioclase crystals from the Thalghat and Kashele “Giant Plagioclase Basalts” from the lowermost Jawhar and Igatpuri Formations respectively in the thickest Western Ghats section near Mumbai. I also obtained bulk rock major, trace and rare earth element chemistry of each lava flow from the two formations. Thalghat flows contain only 12% zoned crystals, with 87 Sr/86Sr ratios of 0.7096 in the core and 0.7106 in the rim, separated by a sharp boundary. In contrast, all Kashele crystals have a wider range of 87Sr/86Sr values, with multiple zones. Geochemical modeling of the data suggests that the two types of crystals grew in distinct magmatic environments. Modeling intracrystalline diffusive equilibration between the core and rim of Thalghat crystals led me to obtain a crystal growth rate of 2.03x10-10 cm/s and a residence time of 780 years for the crystals in the magma chamber(s). Employing some assumptions based on field and geochronologic evidence, I extrapolated this residence time to the entire Western Ghats and obtained an estimate of 25,000–35,000 years for the duration of Western Ghats volcanism. This gave an eruptive rate of 30–40 km3/yr, which is much higher than any presently erupting volcano. This result will remain speculative until a similarly detailed analytical-modeling study is performed for the rest of the Western Ghats formations.