Kinetics of Pyrolysis of Date Kernels

The kinetics of pyrolysis of ground date kernels was investigated using thermogravimetric analysis in order to provide the necessary information for proper biochar formation and bioreactor design. Pyrolysis was carried out at heating rates of 5, 10, 15 and 20oC.min-1 in a flow of nitrogen. One main DTG peak was obtained that corresponded to formation of bio-char. A second diffuse peak corresponds to constant rate cracking of the char formed and complete elimination of carbon leaving an ash residue. The composition of biochar was determined using EDX. Four different methods were used to follow up the kinetics of the three steps, namely, the Kissinger, the Flynn-Wall-Ozawa, the Coats-Redfern methods and multi-regression analysis. The activation energy of the main decomposition step was determined and the values obtained using different kinetic models compared. The decomposition step simply followed first order kinetics.

The Millennium Galaxy Catalogue: Galaxy Bimodality

Galaxy bimodality is caused by the bulge-disc nature of galaxies as opposed to two distinct galaxy classes. This is evident in the colour-structure plane which clearly shows that elliptical galaxies (bulge-only) lie in the red compact peak and late-type spiral galaxies (disc-dominated) lie in the blue diffuse peak. Early-type spirals (bulge plus disc systems) sprawl across both peaks. However after bulge-disc decomposition the bulges of early-type spirals lie exclusively in the red compact peak and their discs in the blue diffuse peak (exceptions exist but are rare, e.g., dust reddened edge-on discs and blue pseudo-bulges). Movement between these two peaks is not trivial because whilst switching off star-formation can transform colours from blue to red, modifying the orbits of ~1 billion stars from a planar diffuse structure to a triaxial compact structure is problematic (essentially requiring an equal mass merger). We propose that the most plausible explanation for the dual structure of galaxies is that galaxy formation proceeds in two stages. First an initial collapse phase (forming a centrally concentrated core and black hole), followed by splashback, infall and accretion (forming a planar rotating disc). Dwarf systems coule perhaps follow the same scenario but the lack of low luminosity bulge-disc systems would imply that the two components must rapidly blend to form a single flattened spheroidal system.

Hardness and Modulus Properties in Ion-beam-modified Amorphous Carbon: Temperature and Dose Rate Dependences

Ion implantation into amorphous carbon has been initiated to investigate the possibility of superhard carbon-nitride formation. Studies of implantation-temperature effects by 100 keV N+ or 80 keV C+ ions at 50 μA show a narrow temperature window at approximately −100 °C for the optimum surface hardness and elastic modulus (measured by nanoindentation), both values much higher than those for the unimplanted amorphous carbon. No distinguishable properties are found between nitrogen and self (carbon) implantations. At a dose rate of 5 μA, however, the optimum hardness and modulus are found at a lower implantation temperature, with a broader temperature window. The enhanced strengths are well correlated with the asymmetric diffuse peak at around 1500 cm−1 in Raman spectroscopy, and the increased ratio of sp3- over sp2-bonded carbon sites observed by electron energy loss spectroscopy.

STUDIES ON Ba2.92Na0.57Nd0.91Nb10.17O30.00 WITH TUNGSTEN BRONZE TYPE STRUCTURE

A new semiconducting material of sodium barium rare-earth niobates of the type Ba 2.92 Na 0.57 Nd 0.91 Nb 10.17 O 30.00 (abbreviated as BN NN) was ma de by sin t ering a sample of an appropriate compositional ratio, Ba 3 NaNdNb 10O30. The crystal structure of BNNN has been confirmed to have tungsten bronze type structure with pseudotetragonal symmetry by X-ray diffraction measurements. The Miller indices hkl of BNNN have been assigned, and the lattice parameters were a≈b=17.6332 Å and c=7.8579 Å. Dielectric constant measurement of the sample sintered in air was carried out at temperatures between 80 to 770 K. The dielectric constant vs. temperature relation reveals a diffuse peak at around 240 K, corresponding to the ferroelectric transition temperatures (Tc). The electrical resistivity and Seebeck coefficient measurements of a sample heated in flowing N 2 gas have been carried out at temperatures from 80 to 273 K. These experiments reveal that BNNN is an n-type extrinsic semiconductor.

Occurrence of interstratified glauconite-montmorillonoid pellets, Queen Charlotte Sound, British Columbia

'Glauconite pellets', discovered in the bottom sediments of the Queen Charlotte Sound on the British Columbia continental shelf, consist of interstratified glauconite-montmorillonoid and kaolin. Expansion of the interstratified material to form a broad diffuse peak on glyceration reflects the presence of the montmorillonoid component. Potassium saturation followed by a series of heat treatments produced an asymmetrical 9.94 Å peak. The clay fraction associated with the 'glauconite pellets' was composed of predominantly montmorillonoid with lesser amounts of kaolin and chlorite. These 'glauconite pellets' may be either residual (eroded out of outcrops on the sea floor), relic Pleistocene, or Recent. It is suspected, regardless of the time of formation, that this particular glauconite formed diagenetically from montmorillonoid by adsorption of potassium in interlamellar positions and possibly some substitution of magnesium and iron for aluminum in octahedral positions.