Thermal conductivity-based hydrogen in argon detector (HAD): Design, development of instrumentation, and performance evaluation.

The Hydrogen in Argon Detectors (HADs) working on the principle of thermal conductivity difference between argon (reference) and argon + H2 (sample) in the cover gas of a sodium-cooled fast breeder reactor using the Wheatstone bridge circuit. The output of HAD is very sensitive to the gas flow rate and to the variation in ambient temperature. The RMSnoise of current was brought within ±1 µA by a constant current source across the bridge. The temperature correction factor fed in the processor brought down the RMSnoise in the HAD signal within ±2.4 mV than the uncorrected one having RMSnoise of ±230 mV. The filtered noise of HAD facilitates enhancing the detection limit of HAD down to 30 ppm (3σ) of hydrogen in argon.

Design and development of heater control circuit without temperature sensor for monitoring hydrogen in argon.

A thin film based tin oxide sensor is developed to monitor low levels of hydrogen (concentration ranging from 5 to 75 ppm) in the cover gas plenum of the fast breeder test reactor. The heater and the sensor patterns are integrated on a miniature alumina substrate, and necessary electrical leads are incorporated into it. For proper functioning of the sensor, the heater has to be maintained at a constant temperature of 350 °C. This paper gives an outline of the electronics developed to measure the sensor signal and to control the heater temperature. The major challenge in this work is that there was no provision for embedding a temperature sensor on the heater surface due to physical constraints. This constrained the maintenance of a constant heater temperature for the proper functioning of the sensor. This led us to develop and demonstrate a heater control circuit without a temperature sensor to maintain a fixed temperature for monitoring hydrogen in argon, and electronics for the above-mentioned circuitry is discussed.

Stability and synchronization analysis of inertial memristive neural networks with time delays.

This paper is concerned with the problem of stability and pinning synchronization of a class of inertial memristive neural networks with time delay. In contrast to general inertial neural networks, inertial memristive neural networks is applied to exhibit the synchronization and stability behaviors due to the physical properties of memristors and the differential inclusion theory. By choosing an appropriate variable transmission, the original system can be transformed into first order differential equations. Then, several sufficient conditions for the stability of inertial memristive neural networks by using matrix measure and Halanay inequality are derived. These obtained criteria are capable of reducing computational burden in the theoretical part. In addition, the evaluation is done on pinning synchronization for an array of linearly coupled inertial memristive neural networks, to derive the condition using matrix measure strategy. Finally, the two numerical simulations are presented to show the effectiveness of acquired theoretical results.

Development of a semi-adiabatic isoperibol solution calorimeter.

A semi-adiabatic isoperibol solution calorimeter has been indigenously developed. The measurement system comprises modules for sensitive temperature measurement probe, signal processing, data collection, and joule calibration. The sensitivity of the temperature measurement module was enhanced by using a sensitive thermistor coupled with a lock-in amplifier based signal processor. A microcontroller coordinates the operation and control of these modules. The latter in turn is controlled through personal computer (PC) based custom made software developed with LabView. An innovative summing amplifier concept was used to cancel out the base resistance of the thermistor. The latter was placed in the dewar. The temperature calibration was carried out with a standard platinum resistance (PT100) sensor coupled with an 8½ digit multimeter. The water equivalent of this calorimeter was determined by using electrical calibration with the joule calibrator. The experimentally measured values of the quantum of heat were validated by measuring heats of dissolution of pure KCl (for endotherm) and tris (hydroxyl methyl) amino-methane (for exotherm). The uncertainity in the measurements was found to be within ±3%.

Orogastric Lavage: A Lifesaving Procedure Now Forgotten

Orogastric lavage has been performed since 200 years ago for intoxicated patients. Due to the risk that outweighs benefits it has fallen out of favour for the last decade. A teenage girl presented to Emergency Department with history of ingestion of a bottle of pesticide within the time frame before gastric emptying. The girl was resuscitated, intubated and orogastric lavage was performed. Fifty cc of the toxic substance was siphoned and antidote of the toxin was administered. She was admitted to the Intensive Care Unit, subsequently recovered and discharge five days later. Definitive airway management, proper technique, correct selection of patients and adequate monitoring are paramount to the success of orogastric lavage.

Reverse-Namaskar: a new sign in Ehlers-Danlos syndrome: a family pedigree study of four generations.

Ehlers-Danlos Syndrome (EDS) is a rare group of inheritable connective tissue disorder of defective collagen. Skin, joints and blood vessels are most commonly affected. Clinical signs such as Gorlin sign and Metenier sign have been described in this syndrome. We report another new clinical sign called 'Reverse-Namaskar' sign as an important clinical finding in EDS, based on the family pedigree study of the proband.

Congenital erythropoietic porphyria associated with ventricular septal defect.

A case of congenital erythropoietic porphyria associated with ventricular septal defect in a 6-year-old girl is reported.

Pagetoid melanoma.

A case of pagetoid melanoma is reported for its unusual site, larger size and presence of suprabasal lacunae in the histopathological study.

Unilateral Darier's disease.

A 60-year old house-wife presented with mildly pruritic, over crusted, greasy, follicular and non-follicular papules over the forehead, retroauricular region and abdomen on the right side. There were numerous discrete hypopigmented macules scattered over the mammary region, abdomen, thigh and leg on the right side. Histopathological study of one of the papules over the forearems showed features of acrokeratosis verruciformis of Hopf.

Tuberous sclerosis with interesting features.

A case of tuberous sclerosis with intracranial calcification, retinal phakoma and premature canities is reported for its interesting features.

A study of palmar dermatoglyphics and palmar freckles.

A study of palmar dermatoglyphics in genodermatoses was conducted in 219 probands and 100 control subjects by standard ink and roller method, during the period 1977-81 at Government General Hospital, Madras. A study of palmar dermatoglyphics in 20 probands with definite clinical and histopathological evidence of Neurofibromatosis revealed an increased incidence of ulnar loop pattern over the finger tips in both sexes. This digital pattern was not found to be of statistical significance, but a statistically significant reduction in the mean a-b ridge count was observed in female cases. An increased incidence of palmar freckles (60%) was observed as a serendipity while taking the palm prints. Some of the palmar freckles with tiny palpable underlying nodules on histopathological study revealed miniature neurofibroma in the dermis. This serendipity has been recorded as an important clinical sign of neurofibromatosis by the author in her thesis submitted for Doctorate degree in 1981.

Ainhum in supernumery fingers.

A case of ainhum occuring in supernumery fingers bilateraly in a thirteen year old girl is presented.

Adenoid Squamous Cell Carcinoma.

Adenoid squamous cell carcinoma occurred on the sole, an area not exposed to sunlight and devoid of pilosebaceous structure. Histopathologically, it showed atypical squamous cells, horn pearls, large alveolar spaces with papillary projections and acantholytic cells.