STRUCTURAL CHARACTERIZATION OF ARABIAN HEAVY CRUDE OIL RESIDUE

The residue (370°C+) from Arabian Heavy Crude Oil was separated into four fractions, asphaltenes, resins, aromatcis and saturates. The four fractions were found to be free of artifacts and analytically significant in themselves. Each fraction was further characterized by elemental analysis, infrared spectroscopy, n.m.r. spectroscopy and mass spectroscopy. The aromatics are the major constituent of the residue and the ratio of asphaltenes, resins, aromatics and saturates is about 2:3:8:3. The strucutral characterization study led to the conclusion that asphaltene fraction is maximum hydrogen deficient followed by resins, aromatics and saturates thus suggesting larger degree of ring condensation in the structure of asphaltenes than resins and aromatics.     

Pollen morphology and its taxonomic potential in some selected taxa of Caesalpiniaceae observed under light microscopy and scanning electron microscopy

Pollen micromorphology is not only used to check the functional and structural evolution in plants but also to solve the taxonomic problem related to the classification of plants. Therefore, keeping in view the significance of pollen traits, selected taxa of the subfamily Caesalpiniaceae was collected from different geographical regions of Pakistan. The species were then analyzed under both light microscopy and scanning electron microscopy techniques to investigate the importance of micromorphological characters of pollen in the identification and classification of species. Great variation was recorded in equatorial shape, surface ornamentation, tectum, polar diameter, equatorial diameter, and exine thickness. However, little variation was observed in pollen type, polar shape, and fertility of pollen. The equatorial shape of five types was observed: prolate, prolate-spheroidal, spheroidal-subprolate, subspheroidal-prolate, and subspheroidal. Four types of surface ornamentation, psilate, granulate, clavate, and perforate, were recorded. Tectum of five types, intactate, reticulate regulate, medium reticulate, tactate, and striate, was observed. Sexine was thicker than nexine in all studied species. The largest polar diameter was observed in Caesalpinia pulcherrima 64.1 μm while the smallest in Parkinsonia aculeata 26.1 μm. The largest equatorial diameter was found in C. pulcherrima of 70.25 μm whereas the smallest in P. aculeata 27.57 μm. All the pollens analyzed were tricolporate. All studied species have a fertility ratio of more than 90%. A taxonomic key was developed to show the variation in pollen features and delimit species for the correct identification. In conclusion, the pollen traits were found useful to define species boundaries at various taxonomic ranks and will strengthen the taxonomy of this subfamily. Besides, this study also explored the palynological traits and their implication in the taxonomy of the subfamily Caesalpiniaceae.     

Effects of gating design on structural and mechanical properties of high manganese steel by optimizing casting process parameters

Journal of Mechanical Science and Technology - The impacts of gating design and riser system on structure-property relationship of high manganese steel specimens produced by CO2 sand molding...     

Fabrication of low friction bronze–graphite nano-composite coatings

This paper addresses the fabrication of bronze–nano-graphite coatings containing 30 nm sized graphite particles. Addition of Poly Vinyl Pyrrolidone (PVP) and dispersing the suspension by ultrasound was utilized to stabilize the electroplating solution. Pulsed current electrodeposition was used and the deposits were characterized in terms of graphite content, particle dispersion in coating and morphology. The wear behavior of the coating was compared to bronze–micro-graphite coatings prepared with the same experimental conditions. The present coating showed improved wear resistance in comparison to bronze–micro-graphite coatings at the same graphite content.     

CHANGES IN ASPHALT CHEMISTRY AND DURABILITY DURING OXIDATION AND POLYMER MODIFICATION

The Gulf Countries' environmental conditions are very severe. The temperature zoning study indicate that more than half of Gulf areas experience a maximum seven consecutive days pavement temperature of 76°C (Al-Abdul Wahhab et al., 1997). This has resulted in damage to the road networks in the form of cracking, rutting and deformation. Polymer modification of asphalt is required to increase the resistance to permanent deformation at relatively high temperatures without adversely affecting the properties of the asphalts at low temperature. In this work chemical and performance-related properties of fresh, oxidized, and polymer modified asphalts were evaluated. The physical properties and performance characteristics of asphalts were found to depend on the chemical composition of asphalt. The interactions of polar functionalities actually present or formed during oxidative aging or due to polymer modification, influence the viscosity and related flow properties. The changes in composition of fresh, oxidized and polymer-modified asphalts can be clearly identified from Infrared spectroscopy. NMR spectroscopy enables detailed information about the Carbon-and-hydrogen-types and average molecular/structural parameters of asphalt without separating it into different components.     

The transversal imager: a photonic neurochip with programmablesynaptic weights

A photonic neural processor implemented in NMOS/CCD integrated circuit technology is described. The processor performs outer-product processing utilizing optical input of the synaptic weights and electrical input of the state vector, or, visa versa. The performance of the 32-neuron, 1024-synapse processor is presented.     

Family B DNA polymerase from a hyperthermophilic archaeon Pyrobaculum calidifontis: cloning, characterization and PCR application

The 2352 bp gene coding for 783 amino acid family B DNA polymerase from Pyrobaculum calidifontis was cloned and expressed in Escherichia coli. Expression of the gene resulted in the production of Pca-Pol in soluble fraction. After heat denaturation of the host proteins, the Pca-Pol was further purified by ion exchange and hydrophobic interaction chromatographies. Activity gel analysis showed the presence of a catalytically active polypeptide of about 90 kDa. The mass of the protein, determined by Matrix-Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry was found to be 89,156 Da. The isoelectric point of the enzyme was found to be 6.13. The optimal pH and magnesium ion concentration for the enzyme activity were 8.5 and 4mM, respectively. Unlike other commercially available DNA polymerases the enzyme activity of Pca-Pol was inhibited by monovalent cations such as ammonium and potassium. The half-life of the polymerase at 95 °C and 100 °C was 4.5h and 0.5h, respectively. The enzyme possessed 3'→5' exonuclease activity and was able to amplify, under suitable conditions, up to 7.5 kb DNA fragments by polymerase chain reaction which makes it a potential candidate for amplification of long DNA fragments.     

Seroconversion of a trivalent measles, mumps, and rubella vaccine in children aged 9 and 15 months

The serological response to MMR vaccine was evaluated in 109 9-month-old infants having no history of measles vaccination, and in 98 15-month-old children who had received monocomponent measles immunisation at 9 months. The combined vaccine contained Schwarz, Urabe Am9, and Wistar RA 27/3 live attenuated virus strains. Preimmunisation antibody levels were extremely low for the 9-month-old children, indicating that maternally-transmitted antibodies do not persist at this age. In the case of mumps, preimmunisation antibody levels were significantly higher in the 15-month-old than in the 9-month-old group. A difference between groups in terms of postimmunisation antibody titres was observed only for rubella, with titres being significantly higher in the older group. Seroconversion rates were high in both groups and no serious events attributable to vaccination were observed. The MMR vaccine can thus be administered to children as young as 9 months of age. Evidence for the efficacy of a two-dose schedule, i.e. at 9 and 15 months, is presented.     

Tomographic microwave diversity image reconstruction employingunitary compression

Data compression through a unitary transform is utilized in tomographic microwave diversity image reconstruction in order to reduce the dimensionality and to extract the features in the data space. The unitary compression is derived by minimizing the mean-square error (MSE) and the unitary transform is made of eigenvectors of the data's covariance, regarded as a Karhunen-Loeve transform. Tomographic microwave frequency-swept imaging was developed using a unique target-derived reference technique to access the three dimensional Fourier space of the scatterer and an image reconstruction algorithm based on the projection slice theorem. It is shown that centimeter resolution of a complex object can be preserved even when half of the data set is compressed and that the reconstructed image remains identifiable by a human observer even when 2/3 of the data set is compressed