Eco-friendly MA3Bi2I9perovskite thin films based ammonia sensor.

Organic-inorganic perovskite halides (OIPH) have emerged as a wonder material with growing interest in sensors detecting various toxic gases. However, lead toxicity represents a potential obstacle, and therefore finding lead-free cost-effective compatible materials for gas sensing applications is essential. In this work, methylammonium bismuth iodide i.e. (CH3NH3)3Bi2I9(MABI) perovskite thin films-based ammonia (NH3) sensor was synthesized using an antisolvent-assisted one-step spin coating method. The MABI sensor shows a linear relationship between the responsivity and concentration of NH3with excellent reversibility, high gas responsivity, and humidity stability. The MABI thin-film sensor exhibits a maximum gas response of 24%, a short response/recovery time i.e. 0.14 s /8.15 s and good reversibility at 6 ppm of NH3. It was observed that MABI thin films based sensors have excellent ambient stability over a couple of months. This work reveals that it is feasible to design high-performance gas sensors based on environmentally-friendly Bi-based OIPH materials.

Validation of analysis of arsenic in water samples using Wagtech Digital Arsenator.

Groundwater, the only source of potable water for millions of people in Bangladesh during dry season, is often contaminated with arsenic (As) above the allowable drinking water limit of 50 µg/L. Testing well water--with arsenic field test kits (FTKs)--and switching to safe-wells can effectively reduce exposure to As. FTKs are low cost, provide fast results, and are commercially available. There are between 10 and 11 million shallow tubewells in Bangladesh. Approximately, 5 million have been tested using FTKs. FTKs with color comparator rely on visual identification for generating qualitative results, which may not be highly reliable at the lower range because human eyes have low sensitivity in this range and sensitivity varies from person to person. The Wagtech Digital Arsenator does not suffer from this limitation and should, in theory, be able to generate quantitative, accurate, and reliable results. The instrument has a linear range of 0-100 µg/L, an accuracy of ± 20% for the 50 µg/L quality control standards, and a detection limit of about 4.4 µg/L. All Arsenators employed in this investigation also displayed high bias for 50 µg/L arsenic standard and were calibrated in order to improve measurement accuracy and reliability. Analyses of 179 raw and 92 treated well waters in the field and in two analytical laboratories were found to be highly correlated with the Spearman rank correlation coefficient of ≥ 0.800, indicating that Arsenator results are perhaps nearly as accurate and reliable as those from analytical laboratories.

Comparative evaluation of two once-a-month contraceptive injections.

Two once-a-month preparations cyclo provera (Depo-medroxy Progesterone Acetate 25 mg and Estradiol Cypionate 5 mg) and HRP-102 (Norethisterone enanthate 50 mg and Estradiol Valerate 5 mg) were tried in two groups of women by random allocation, and their effectiveness, complaints and reasons for discontinuation were studied. A total of 206 women were admitted (104 on cyclo provera and 102 on HRP-102) and studied for one year. There was little difference in the efficacy and side-effects between the two preparations. One pregnancy occurred with HRP-102 giving a pregnancy rate of 1.4%. The overall discontinuation rates at 1 year were 57.6% for cycloprovera and 54.9% for HRP-102. The discontinuation rates for bleeding irregularities, were 21.2% and 21.8% respectively for cycloprovera and HRP-102. Five women discontinued due to lack of bleeding or amenorrhoea. The respective figures were 4 and 1 for cyclo provera and HRP-102. Both products were highly effective and, if introduced in the national Family Planning Programme, they will fulfill an important role (JPMA 39:98, 1989).