Role of magnetic resonance spectroscopy and diffusion-weighted imaging in characterizing intra axial brain tumours

Background: Magnetic Resonance imaging (MRI) is essential for assessing intracranial malignancies, but conventional MRI has limitations in tumour grading and infiltration information. Advanced Magnetic Resonance (MR) sequences, such as diffusion-weighted (DW) and Magnetic Resonance spectroscopy (MRS), can differentiate between low-grade and high-grade tumours, aiding treatment decisions. This study aims to evaluate the efficacy of diffusion-weighted imaging and magnetic resonance spectroscopy in grading intra-axial brain tumours and correlating the results with histopathology. Methods: This retrospective study involved 45 patients over one year at Apollo Hospital. MR imaging included conventional sequences, DW, and MRS with localizers in all three planes. DWI and ADC maps were obtained using specific b-values. Standard mean Apparent Diffusion Coefficient (ADC) values were automatically calculated for intra-lesional and peri-lesional regions. Results: Intralesional ADC values did not significantly differ between high-grade primary tumours (0.4-1 x 10-3 mm2/s, mean 0.7) and metastases (0.4-0.8 x 10-3 mm2/s, mean 0.7). However, peri-lesional ADC values were lower in primary tumours (0.3-1.3 x 10-3 mm2/s, mean 0.8), indicating peri-lesional infiltration, while higher in metastases (1.2-1.6 x 10-3 mm2/s, mean 1.4) due to the absence of peri-lesional infiltration. Additionally, intralesional ADC values showed a significant difference between low-grade tumours (1-2 x 10-3 mm2/s) and high-grade tumours (0.4-1 x 10-3 mm2/s), allowing for their distinction. There were significantly increased Cho/NAA and Cho/Cr ratios in high-grade tumours compared to low-grade tumours. Conclusions: MR spectroscopy and DWI with computation of ADC values can enhance the diagnostic effectiveness of MR imaging in detecting and grading malignant brain tumours

The effect of friction stir processing on mechanical, wear and corrosion characteristics of Cu-AlN-BN surface composite

This research investigates the impact of hybrid particles dispersed onto the surface of a copper matrix using Friction Stir Processing (FSP) on its microstructural, mechanical, and corrosion behavior. The hybrid particles under study consist of equal fractions of Aluminium Nitride (AlN) and Boron Nitride (BN). Microstructural characterization confirms breakdown of grain size due to dynamic recrystallization and presence of particles, along with their effective bonding to copper matrix. Attained results indicated a significant enhancement in hardness, with an increase of up to 3.9 % upon the introduction of particles onto the surface. Moreover, the tensile properties exhibit noticeable improvements in terms of ultimate tensile strength (6.39 %) and yield strength (6.12 %), albeit at the expense of reduced ductility in the copper matrix. Furthermore, the wear rate (decreases up to 22 %) and corrosion rate of the developed composites demonstrate a decreasing trend with the introduction of particles. This improvement can be attributed to the reduction in grain size during the FSP process and the formation of a nitride passive layer facilitated by the reinforced hybrid particles, thereby effectively inhibiting the corrosion rate

Effect of material and machining features in electric discharge machining of 6061Al/rock dust composites

471-480The current research investigates the effect of electric discharge machining (EDM) and material parameters on material removal rate (MRR), tool wear rate (TWR) and surface roughness (Ra) while machining the novel aluminium rock dust composite. Experiments have been performed in Vidyunt EM 150 EDM machine by considering parameters namely discharge current, pulse ON time, pulse OFF time, reinforcement size and level. The composites have been prepared through stir casting method by reinforcing various sizes (10, 20 & 30 µm) of rock dust particles with aluminium 6061 and at different levels (5, 10 & 15%). Since the number of input parameter is more, Taguchi’s design of experiments has been used to reduce the number of trials and grey relational analysis (GRA) technique has been used for optimization. Analysis of variance has been performed to identify the significance of the parameters and it has been found that all the considered parameters have significant effect on response variables. But in the case of multi performance characteristics analysis, only pulse ON time and pulse OFF time have the significance over GRG. Pulse ON time has the highest influence (55.36 %) on the GRG followed by pulse OFF time with 17.6% and rock dust weight % with 7.8%. From the confirmation experiments, it could be well said that the developed regression equations predicts the response parameters with minimal error and the grey relational grade has been improved significantly

Effect of material and machining features in electric discharge machining of 6061Al/rock dust composites

The current research investigates the effect of electric discharge machining (EDM) and material parameters on material removal rate (MRR), tool wear rate (TWR) and surface roughness (Ra) while machining the novel aluminium rock dust composite. Experiments have been performed in Vidyunt EM 150 EDM machine by considering parameters namely discharge current, pulse ON time, pulse OFF time, reinforcement size and level. The composites have been prepared through stir casting method by reinforcing various sizes (10, 20 & 30 μm) of rock dust particles with aluminium 6061 and at different levels (5, 10 & 15%). Since the number of input parameter is more, Taguchi’s design of experiments has been used to reduce the number of trials and grey relational analysis (GRA) technique has been used for optimization. Analysis of variance has been performed to identify the significance of the parameters and it has been found that all the considered parameters have significant effect on response variables. But in the case of multi performance characteristics analysis, only pulse ON time and pulse OFF time have the significance over GRG. Pulse ON time has the highest influence (55.36 %) on the GRG followed by pulse OFF time with 17.6% and rock dust weight % with 7.8%. From the confirmation experiments, it could be well said that the developed regression equations predicts the response parameters with minimal error and the grey relational grade has been improved significantly

CEMENT-CLAY SLURRIES: HYDRATION MECHANISM AND PROPERTIES

Ph.DDOCTOR OF ENGINEERIN

Mechanical, corrosion and wear characteristics of powder metallurgy processed Ti-6Al-4V/B4C metal matrix composites

Titanium alloys are used in aerospace and automotive applications because of its high specific strength, stiffness and good machinability but its wear resistance is inadequate. To eliminate this property lag Boron Carbide (B4C) ceramic particles are reinforced with Ti-6Al-4V through powder metallurgy route (PM). Reinforcement particles are mixed with base alloy for the weight percentage of 0, 5 and 10 so as to analyse the effect of reinforcements on mechanical, corrosion and wear properties. This research outcome corresponds to decreased density, increased hardness and corrosion resistance capability for significant increase in B4C content of the newer composite developed and tested. Applied load signify higher effect on wear performance of the composite specimens followed by B4C addition percentage. Scanning Electron Microscope results reveal that B4C reinforced Ti-6Al-4V composite comprise for higher wear resistance and illustrate mild worn surface when compared to that of unreinforced Ti alloy. Keywords: Ti MMC, Boron carbide, Powder metallurgy, Corrosion, Wea

Effect of rock dust, cenosphere and E-waste glass addition on mechanical, wear and machinability behaviour of Al 6061 hybrid composites

270-282This paper has a propensity to identify low cost and ordinarily available reinforcements besides comparatively reviewing fly ash, bagasse ash, rice husk ash reinforced aluminium composites. This has led to microstructure, mechanical and wear characteristic investigation of newer composite developed through stir casting with cenosphere, rock dust and e-waste cathode ray tube (CRT) panel glass powder. Comparison over experimental results with available reported data of said reinforcements clarifies that newer reinforcements have also yielded equivalent properties. Addition of these newer reinforcements up to 10% increases the tensile strength whereas maximum of 65.12% hardness raise is attained for cenosphere and 63.04% for CRT addition to that of Al 6061 T6. Tensile strength increases up to 9.84% for 15% cenosphere reinforcement, 9.02% for 10% CRT addition. Addition of cenosphere and rock dust up to 15% increases the wear resistance but in the case of CRT powder, wear resistance is high up to 10% and then decreases due to formation of glass globes for further CRT addition. In perspective of the research an admissible increment in wear resistance and machinability of the developed novel hybrid composites is evidenced through scanning electron microscope (SEM) micrographs besides indicating better surface finish while turning