Tara Singh

1,3,4-Thiadiazoles as potential EP additives — a tribological evaluation using a four-ball test

Abstract This paper reports a comparative study of the wear-reducing efficiency and extreme pressure properties of 0.5% ( w v ) admixtures of paraffin oil and 2-amino-5-arylamino-1,3,4-thiadiazole additives and a commercial sulphur-phosphorus additive in a four-ball test. 2-Amino-5-p-Cl-phenylamino-1,3,4-thiadiazole additive shows excellent EP properties as is evident from the surface smoothness of SEM micrographs. The tribochemistry of the wear-scar surface has been investigated by the auger electron spectroscopy (AES) technique.

Evaluation of 2, 4-Dithiomalonamides as Extreme Pressure Additives in the Four-Ball Test

Four-ball tests using 12.7 mm diameter steel bearing balls were conducted to evaluate the load-carrying and extreme pressure properties of admixtures of paraffin oil with 1, 5-diaryl-2, 4-dithiomalonamides and a sulphur-phosphorus commercial additive (0.5 per cent wt/vol.). 1, 5-Di-p-methoxyphenyl-2, 4-dithiomalonamide exhibiting wear scar diameter and friction coefficient values of 0.58 mm and 0.058 at 100 kgf (ISL) and 2.18 mm and 0.077 at 500 kgf as compared to the values of 2.05 mm and 0.022 at 56 kgf (ISL) and 2.73 mm and 0.43 at 100 kgf for paraffin oil appeared to be most effective. The surface topography of the wear scars were examined by scanning electron microscope.

Verbal episodic memory in young hypothyroid patients

Context: Hypothyroidism affects cognitive functions especially memory. However, most of the previous studies have generally evaluated older hypothyroid patients and sample size of these studies varied in terms of age range. Aims: To see whether hypothyroidism affects memory in young patients. Settings and Design: The sample consisted of 11 hypothyroid patients with an age of 18–49 and 8 healthy controls matched on age and education. Subjects and Methods: Verbal episodic memory was assessed using Hindi adaptation of Rey-Auditory Verbal Learning Test. Statistical Analysis Used: An independent t-test was used to see the difference between mean performance of the patient group and healthy control on memory measures. Results: Results indicated nonsignificant difference between verbal episodic memory of patient group and healthy controls. Conclusions: On the basis of these findings, it was concluded that hypothyroidism may not affect younger patients in terms of episodic verbal memory the same way as it does in the older patients.