Micro-mechanical and tribological behavior of Al/SiC/B4C/CNT hybrid nanocomposite.

The aluminum nanocomposite is fabricated through squeeze stir casting method where CNT, SiC/B4C powder has been used as a reinforcement in an aluminum matrix. Squeeze action in stir casting opted due to proper reinforcement of 2 vol% of CNT in the matrix. The boron carbide and silicon carbide have been added by 8 and 12 vol% in the matrix. Uniform distribution of reinforcement and phase analysis has been shown by scanning electron microscopy (SEM) and XRD analysis. The formation of intermetallic compounds like Al3BC and Al4C3, dislocation forests, and the interaction of the reinforcement with the matrix are all confirmed by transmission electron microscopy (TEM). The micro-mechanical behavior of aluminum nanocomposites was investigated using nano indentation. The nano hardness, Vickers hardness, and Young's modulus of 12 vol% B4C compared with 12 vol% of SiC are increased by 12%, 23%, and 16%, respectively, and the same trend has been observed for the 8 vol% B4C reinforced composite. The model analysis for Young's modulus has been done and the experimental value for the modulus of elasticity of the composite are validated and not find such differences significantly. The surface topography was determined, furrow scratches and wear scars, and it was discovered that B4C reinforced composites have reduced stripping pits inside the wear marks, as well as lower wear width and depth. Wear analysis is essential because abrasive encounters result in substantial damage owing to larger pits and bigger wear scars.

Transcranial Doppler sonography evaluation in patients with vasospasm following subarachnoid haemorrhage.

Transcranial Doppler (TCD) sonography is emerging as a new ultrasonography technology to look at the interaction between the brain parenchyma and perfusion during cerebrovascular accident. Before TCD sonography the vasospasm following subarachnoid haemorrhage could only be diagnosed either clinically or by invasive method ie, angiography. TCD has been proved as a wonderful non-invasive, repeatable, beat-by-beat, non-expensive technique for detection and follow-up of vasospasm after subarachnoid haemorrhage. In the present series 12 patients suspected to have vasospasm after subarachnoid haemorrhage were confirmed and monitored with the help of TCD. Most of the patients were clinically presented with increasing headache and altered sensorium. It is noticed that vasospasm following subarachnoid haemorrhage has a typical course, which has increasing trend after 4th day of subarachnoid haemorrhage and declining trend after 14th day onwards. Six out of 12 patients were in moderate grade of vasospasm, 2 out of 12 were in severe grade and 4 out of 12 were mild grade of severity.

A retrospective study of multiple interbody grafting and long segment strut grafting following multilevel anterior cervical decompression.

A retrospective study of 201 patients who underwent multilevel anterior cervical decompression and fusion by multiple interbody grafting and long segment strut grafting without plate fixation was conducted from January 1991 to December 2001. Previous studies have reported lower fusion rates for anterior cervical decompressions reconstructed with multiple interbody grafts as opposed to a single long strut graft. Our aim was a retrospective study of two fusion techniques with reference to radiological and clinical outcomes in patients operated by the senior author. Of 132 patients who underwent strut grafting, 124 achieved solid fusion (93.9%), whereas 48 of 69 patients who underwent multiple interbody grafting (69.6%) achieved solid fusion. There were five cases of graft displacement or extrusion among strut-grafted patients and one among patients with interbody grafts. More 'good' and 'excellent' clinical outcomes were found among patients who underwent strut grafting (87.1 v. 81.1%). Patients with pseudoarthrosis had significantly poorer clinical outcomes. Therefore, corpectomy or vertebrectomy and strut grafting should be considered after multilevel anterior cervical decompression to increase the likelihood of successful fusion and to improve clinical outcome.

Percutaneous vertebroplasty: an experience of 31 procedures.

A prospective study of 31 percutaneous vertebroplasty procedures (PVP) in 22 patients treated during January 2000 to December 2001 is presented. PVP was performed using polymethylmethacrylate (PMMA) to treat vertebral collapse due to osteoporosis and vertebral metastasis, to obtain analgesia and spinal stabilization. We analyze the efficacy and complications related to the procedure. PVP is a safe, effective and a daycare surgery. It can be performed under local anesthesia and has minimal and manageable complications.

Measurement of temperature using speckle shearing interferometry.

A laser speckle shearing interferometric technique is used for measuring the temperature profile inside a gaseous flame. The experimental results are compared with the values obtained by a thermocouple and also by speckle photography. Good agreement is seen among the temperatures measured by speckle shearing interferometry, speckle photography, and the thermocouple. Speckle shearing interferometry is easier to implement than speckle photography. This is because in speckle shearing interferometry the accurate positions of the fringes can be known without point-by-point analysis and correction for the halo effect.