Sensing Properties of Oxidized Nanostructured Silicon Surface on Vaporized Molecules.

Porous silicon has been intensely studied for the past several decades and its applications were found in photovoltaics, biomedicine, and sensors. An important aspect for sensing devices is their long⁻term stability. One of the more prominent changes that occur with porous silicon as it is exposed to atmosphere is oxidation. In this work we study the influence of oxidation on the sensing properties of porous silicon. Porous silicon layers were prepared by electrochemical etching and oxidized in a tube furnace. We observed that electrical resistance of oxidized samples rises in response to the increasing ambient concentration of organic vapours and ammonia gas. Furthermore, we note the sensitivity is dependent on the oxygen treatment of the porous layer. This indicates that porous silicon has a potential use in sensing of organic vapours and ammonia gas when covered with an oxide layer.

Vitamin D deficiency and possible link with Bony pain and onset of Osteoporosis.

OBJECTIVE: To explore if vitamin D deficiency had a direct correlation with bone pain or if it contributes in any way to the onset of osteoporosis. METHODS: The cross sectional Study was conducted from February to May 2014, presented at Liaquat National Hospital, Karachi, and comprised Orthopaedic outpatients. Who were questioned, examined and counselled, before a questionnaire was filled that included questions about their complaint, and its severity. Several blood test reports were incorporated including serum Vitamin D, to evaluate kidney and liver functions. Dual energy X-ray absorptiometry scans of the lumber and hip regions were also included. Data was collected manually and analysed using SPSS version 16. RESULTS: The mean age of the 65 subjects, was 52.±16 SD years, and 54(83.1%) were overweight with body mass index of 29.7kg/m2. Besides, 61(93.8%) had a positive association of low vitamin D levels as a causative agent for bone pain with mean pain severity index 6±1 SD. On the other hand 25(38.5%) were diagnosed as cases of osteoporosis, and, of them, 21(84%) had low vitamin D levels. CONCLUSIONS: Deficiency of vitamin D was directly related to the intensity of bone pain. Some patients had vitamin D deficiency along with osteoporosis, which may have aggravating effect in this context.