The role of cranial CT in the investigation of meningitis

More patients with meningitis are undergoing CT and the number of inappropriate requests are increasing. There are few abnormal CT scans presenting a contraindication for lumbar puncture and the majority of these patients usually have clinical signs to suggest raised intracranial pressure

Silicide Identification in Rta-Processed Ti Salicide by Analytical Electron Microscopy

Titanium suicides have low resistivity, low contact resistance, and are widely used as interconnects in electronic devices. The most desirable structure is the C54 variant of titanium disilicide (TiSi2). It is typically formed during thermal annealing by a polymorphic transformation from the C49 TiSi2 structure. The C49 to C54 transformation has been studied extensively and there has been substantial effort to devise ways in which to lower the temperature associated with this transformation. This research uses high-resolution imaging (HREM), convergent-beam diffraction (CBED), and energy-dispersive X-ray microanalysis (EDS) to study the development of suicide morphology in response to rapid thermal annealing (RTA). Two sets of specimens have been studied: (i) 32nm Ti thin films on undoped single-crystal Si substrates [Ti/Si] and (ii) 32nm Ti films separated from an undoped single-crystal Si substrate by a 0.12nm thick Mo interlayer [Ti/Mo/Si]. This paper shows structures formed after RTA at a ramp rate 3 °C/sec to 750 °C with a hold of 1 sec</jats:p

Effect of Deposition Conditions on Intrinsic Stress, Phase Transformation and Stress Relaxation in Tantalum Thin Films

AbstractWe demonstrate that the high temperature polymorphic tantalum phase transition from the tetragonal beta phase to the cubic alpha phase causes complete stress relaxation and a large decrease in the resistance of tantalum thin films. 100 nm beta tantalum thin films were deposited onto thermally oxidized &lt;100&gt; silicon wafers by dc magnetron sputtering with argon. In situ stress and resistance at temperature were measured during temperature-ramped annealing in purified He. Upon heating, films that were initially compressively stressed showed increasing compressive stress due to thermo-elastic deformation from 25 to 550°C, slight stress relief due to plastic deformation from 550 to 700°C and complete stress relief due to the beta to alpha phase transformation at approximately 700–800°C. Incomplete compressive stress relaxation was observed at high temperatures if the film was initially deposited in the alpha phase or if the beta phase did not completely transform into alpha by 800°C. This incomplete beta to alpha phase transition was most commonly observed on samples that had radio frequency substrate bias greater than -100 V. We conclude that the main stress relief mechanism for tantalum thin films is the beta to alpha phase transformation that occurs at 700 to 800°C.</jats:p

Kinetics of Intermetallic Formation in Free Standing Cu/Mg Multilayer Thin Films

ABSTRACTDifferential scanning calorimetry (DSC) has been used to study the temperatures, kinetics and phase formation mechanisms in Cu/Mg multilayer thin films. When the Cu:Mg layer thickness ratio was 1:4, CuMg2 was the only phase that formed. Cu/Mg films with a layer thickness ratio of 1:1 first form CuMg2 at 215°C with an activation energy of 1.0 ± 0.04 eV and then Cu2Mg at 380°C with an activation energy of 0.73 ± 0.04 eV. The temperatures at which the two phases form decrease as the layer thicknesses decrease due to the shorter reaction times needed in thinner films. The constant scan rate DSC data from films with a layer thickness ratio of 1:1 show three exothermic peaks. The first peak is extremely sharp and results from the formation of isolated nuclei of CuMg2 at the Cu/Mg interface. The formation of CuMg2 is thus shown to be nucleation controlled. The second peak is a growth peak due to the heat released during the growth of CuMg2. The third peak corresponds to the formation and growth of Cu2Mg.</jats:p

Ground Water Monitoring in Areas Used for the Infiltration of Effluents from Chemical Industries

In 1984, in Taubaté County, Brazil, a study was carried out to identify the groundwater pollution due to land disposal of chemical industrial wastewater. After characterization of the wastes, some analytical parameters were selected for a monitoring programme: TOC, COD and electrical conductivity. This programme was started after a network of 39 monitoring wells was installed. The water level was determined monthly and four times a year samples from the groundwater were collected for chemical analysis. The data were interpreted by a computer program (SYMAP) which produced hydrochemical and isopotential maps. The interpretation of these maps shows groundwater pollution due to wastewater infiltration and the limit of the pollution plume was the adjoining stream. In addition to determining the horizontal trend of pollution into the aquifer, research is necessary to verify vertical pollution, in order to evaluate the degree the aquifer has been compromised.</jats:p