[en] The development of suitable methodology described in this paper for twelve different VOCs or tropospheric interest is based on target compound analysis. Their characterization by GLC from more volatile to less volatile hydrocarbons adsorbed on charcoal with subsequent desorption in xylene solvent in described. The chromatography of this group of volatile organic compounds with detection limit sample injection volume and chromatographic performance of the packed column is critically discussed for urban air samples of Aberdeen City (UK), pumped sampling on charcoal was used with subsequent desorption into xylene. The only problem is the volume of solvent required in routine analysis, usually of the order of the milliliter, sine only a micro-litter of extracts is injected into the GLC, which reduces the sensitivity of the method compared to that of thermal desorption

[en] Objective of this thesis was the synthesis of the nano whiskers of aluminum ammonium carbonate hydroxide (AACH) from the mixture of aluminum nitrate and urea with different content levels of urea by hydrothermal process. The AACH precursor of nano alumina whiskers is added into zirconia powder along with CTAB and ethanol to obtain fine precipitates ready for calcining at 650 C. Fine powder of zirconia with alumina whiskers is compacted to form pellets of 5 mm diameter. Sintering of pellets has been performed at 1500 C in open atmosphere. Fabrication of sintered pellets is being done by using uniaxial press under 5 ton loads. The addition of alumina whiskers resulted better mechanical properties like compactness, hardness and flexural strength etc. The influence of urea composition upon the growth of alumina whisker has been revealed by FE-SEM. Low content of urea at 6 gm. to 8 gm. formed urchin like morphology of AACH whiskers, while at higher level 12 gm. of urea independent whiskers obtained. In second stage the varying amount of urea in aluminum nitrate was performed and calcined at different temperatures 80, 100, 200, 300, 400 degree C to reveal the effect on the pure AACH whiskers morphologies. Different characterization like SEM is used for structure morphologies, XRD used for determining of type of structure, FTIR technique used for the study of nature of functional groups, and impedance spectroscopy applied for electrical properties measurements. XRD pattern show the presence of a-alumina, FTIR tells about the missing peaks and absence of functional group due to increases in the temperature and SEM analysis of fractured surface of sintered pellets done for revealing structure morphology. Fracture study of nuclear fuel has also done by SEM analysis in this work to study cause of peeling off flakes at the outer edge of sintered UO₂ pellets. (author)

[en] The drift velocity of particles undergoing E vector x B vector rotation in a collisional plasma is investigated by test wave technique and Langmuir probe. The velocity determined by probe is corrected by including effect of cylindrical geometry and finite Larmor radius effect. From the B dependence of the corrected velocity and the drift velocity determined by test wave, the ion-neutral collision cross section is determined which is found to be in disagreement with the value given by the current data. This disagreement is attributed to an inappropriate collision cross section at low energy at which small angle scattering events are frequent. It is proposed that in events in which there is a loss of particle drift velocity, we should use the so-called ''slowing down cross section'' sigmasub(s') rather than the total cross section. (auth.)

[en] We study the spin-flavor conversion of active as well as sterile neutrons bar (nu/sub e/ - nu/sub mu/, bar nu/sub e/ - nu/sub s/, etc.) in the magnetic fields of collapsing stars and the early Universe. In collapsing stars, for the neutrino mass squared difference delta m/sup 2/ approx(10 /sup -10/) eV/sup 2/ these conversions take place in almost isotopically neutral region of the star, where the effective matter density for active neutrino conversions is suppressed up to 3-4 orders of magnitude. This suppression is shown to increase the sensitivity of the neutrino burst studies to the magnetic moment of neutrino mu by 1.5 - 2 orders of magnitude and for realistic magnetic field the observable effects may exist for mu approx (2-3)x 10/sup -14/ mu /sub B/. The experimental signatures of the spin-flavor conversions between active to active and active to sterile neutrinos are discussed. In particular, in the case of direct mass hierarchy, the spin-flip effects result in a variety of modifications of the V/sub e/ spectrum for both types of conversions. Taking this into account, we estimate the upper bounds on mu B from the SN 1987 A data. In the isotopically neutral region the effects of possible twist of the magnetic field on the way of neutrinos can be important, including distortion in the neutrino energy spectra and further increasing the sensitivity to mu B. However, if the total rotation angle is restricted by delta phi < pi, the absolute change of probabilities is small. In particular, for neutrino conversions, it enhances the effect thus relaxing the resonant delta m/sup 2/ values to achieve the same average conversion probability as without primordial field twist. Next, we study the effects of resonant (nu/sub e/ - nu/sub mu/) spin-flavor conversions of reheated neutrinos. We estimate the effect to be less than 1% (i.e., delta Y < or approx. 1.26 x 10/sup -3/. We point out that these conversions may occur for mu as small mu approx 10 /sup -20/ mu B in a primordial magnetic field of electroweak origin. The effects of resonant spin-flavor as well as flavor conversions n relic neutrino energy spectra are discussed. (Orig./A.B.)

[en] Eileen sand covers about (8%) of Bahrain Island, and is concentrated in the western and southwestern regions of the Island as a thin s rip between the western coast and the cap rock, forming a distinguished ge morphologic feature on the Island. In the last few years, the area have suffered from sand from sand drifts which affected some of the important places in Bahrain as Al-Reen Wildlife sanctuary, alerting the spread of dentifrice's processes in new parts of the Island. The results showed that Al-Areen sand is composed mainly of quarts (68%) with lesser amounts of carbonates (15%) gypsum (12%), and heavy minerals. The compassion of Al-Areen sand with the surface sediments and rock exposure sin Bahrain, revealed that these sands have been drifting throughout the Quatenary period from the northwestern part of the Arabian peninsula peninsula by the northern wind (Shamal), prevailing at that time, transporting the quartzitic sand southeasted toward Bahrain. The influx of quartzitic sand to Bahrain was eliminated about 7000 year B.P. due to the ecstatic change of sea level in the Arabian Gulf which formed a natural water counter between Bahrain and the Arabian peninsula. Accordingly the sand drifts in Al-Areen Widife sanctuary is a result of diffraction's affecting the Island of Bahrain, this requires further studies to combat it. . (author). 25 refs., 5 figs. 2 tab

[en] This report describes experimental reactor physics measure ments at PARR using the in-core neutron detectors. Rhodium self powered neutron detectors (SPND) were used in the PARR core and several measurements were made aimed at detector calibration, response time determination and neutron flux measurements. The detectors were calibrated at low power using gold foils and full power by the thermal channel. Based on this calibration it was observed that the detector response remains almost linear throughout the power range. The self powered detectors were used for on-line determination of absolute neutron flux in the core as well as the spatial distribution of neutron flux or reactor power. The experimental, axial and horizontal flux mapping results at certain locations in the core are presented. The total response time of rhodium detector was experimentally determined to be about 5 minutes, which agree well with the theoretical results. Because of longer response time of SPND of the detectors it is not possible to use them in the reactor protection system. (author). 10 figs

[en] Rotational frequency of a plasma cylinder immersed in a uniform magnetic field and an axisymmetric radial electric field which is proportional to radial distance from the axis is determined by a single particle model without collisions. The effects of the centrifugal and the Corioli's forces are taken into account which lead to final expressions of the rotational frequency and the effective magnetic field as seen by the particles in the rotating plasma cylinder with correction terms which are proportional to the radial electric field. (auth.)

[en] In the present work, we have theoretically interpreted the phonon conductivity of Gallium Ares enide (GaAs) between 2 and 800k using an expression for the phonon relaxation rate previously derived by Du bey, taking into account four types of scattering mechanisms viz. boundary, point defect, three-phonon and four-phonon scattering.The temperature exponent m, which depends on temperature, is determined for both class I and class II events. Excellent quantitative agreement with the experimental data is achieved using adjustable parameters. At low temperatures, the phonon N- processes play a dominating role in phonon conductivity while at high temperatures, it is mainly due to three-phonon U-processes. On the other hand, the major contribution to the phonon conductivity comes from the transverse phonon. (authors). 30 refs., 4 figs., 2 tabs

[en] Energy levels in ⁶⁴Cu have been studied from ⁶²Ni (3He,p)⁶⁴Cu reaction at an incident energy of 18 MeV. The proton spectra were obtained at six angles ranging from 5degC to 50degC at an interval of 7.5degC. A total of one hundred and two levels have been observed upto an excitation of 5.192 MeV with an energy resolution of +- 20 KeV. (author)

[en] The drive to improve performance of coatings as protection against corrosion for automotive, aerospace and oil and gas industries is a never-ending story. Surface preparation is the most important single factor when a substrate surface e.g. steel is to be protected with a coating. This implies an extremely accurate and reliable characterisation of the substrate-surface prior to coating process and the investigation of polymeric coating materials. In order to have a durable adhesive bonding between the polymeric coating materials and the substrate i.e. to ensure prolonged life time and fewer maintenance intervals of coated products, a pre-treatment of the substrate is required in many cases. Sand blasting, corona /plasma pre.treatment of the substrate and the use of coupling agents like organo silanes are well accepted recent methods. Advanced surface analytical techniques like ESCA and TOFSIMS are proving to be extremely helpful in the chemical characterisation of the substrate surface. Contamination e.g. fat residues, tensides etc. on the substrate is one of the most serious enemies of adhesive bonding and the above mentioned techniques are playing a vital role in combating the enemy. Modern thermal analytical methods have made tremendous contribution to the development and quality control of high-performance polymeric coatings. MDSC, DMA and DETA are proving to be very useful tools for the characterisation of high-performance coating materials. An in-depth understanding of the structure-property relationship of these materials, predominantly epoxy and polyurethane coating systems, is a pre-requisite for their successful application and subsequent Quality Control. (author)