Investigation of an Impedimetric LaSrMnO3-Au/Y2O3-ZrO2-Al2O3 Composite NOx Sensor.

Composite NOx sensors were fabricated by combining partially and fully stabilized yttria-doped zirconia with alumina forming a composite electrolyte, Y2O3-ZrO2-Al2O3, and strontium-doped lanthanum manganese oxide mixed with gold to form the composite sensing electrode, La0.8 Sr0.2MnO3-Au. A surface chemistry analysis of the composite sensor was conducted to interpret defects and the structural phases present at the Y2O3-ZrO2-Al2O3 electrolyte, as well as the charge conduction mechanism at the LaSrMnO3-Au electrode surface. Based on the surface chemistry analysis, ionic and electronic transport properties, and microstructural features of sensor components, the working principle was described for NOx sensing at the composite sensor. The role of the composite materials on the NOx sensing response, cross-sensitivity to O2, H2O, CO, CO2, and CH4, and the response/recovery rates relative to sensor accuracy were characterized by operating the composite NOx sensors via the impedimetric method. The composite sensors were operated at temperatures ranging from 575 to 675 °C in dry and humidified gas environments with NO and NO2 concentrations varying from 0 to 100 ppm, where the balance gas was N2. It was found that the microstructure of the composite NOx sensor electrolyte and sensing electrode had a significant effect on interfacial reactions at the triple phase boundary, as well as the density of active sites for oxygen reactions. Overall, the composite NOx sensor microstructure enabled a high NOx sensing response, along with low cross-sensitivity to O2, CO, CO2, and CH4, and promoted NO detection down to 2 ppm.

Incidence of the Hb E [ß26(B8)Glu→Lys, GAG>AAG] variant in Totos, one of the smallest primitive tribes in the world.

Toto is one of the smallest tribes in the world. This primitive sub Himalayan, endogamous tribe lives in a small, isolated village called Totopara in the Jalpaiguri district of West Bengal in India. The tribal communities of West Bengal are vulnerable to various genetic disorders such as ß-thalassemia (ß-thal). We have studied 443 Totos to define their Hb E [ß26(B8)Glu→Lys, GAG>AAG] status. Awareness and screening camps have been organized in various parts of Totopara during the last 2 years. We collected 3 mL peripheral blood from each individual aseptically on which to use the naked eye single tube red cell osmotic fragility test (NESTROFT); complete hemogram and high performance liquid chromatography (HPLC) were done to detect their carrier status. The Hb E variant had been found to be prevalent among the Totos. To confirm the codon 26 (GAG>AAG) mutation in the ß-globin gene, amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) was performed. Restriction fragment length polymorphism (RFLP)-PCR was carried out with 44 Hb E alleles to construct the haplotype(s) of the Totos. Our extensive studies have revealed that 49.21% of Totos are Hb E heterozygotes and 19.19% Totos are Hb E homozygotes. The most prevalent haplotype linked with the codon 26 mutation in the Totos is [+ - - - - -] (HincII 5'ϵ, HindIII (G)γ, HindIII (A)γ, HincII 5'ψß, HincII 3'ψß and HinfI 3'ß). Consanguineous marriages have resulted in a significant increase of the percentages of heterozygotes and homozygotes of Hb E in the Totos. Genetic counseling is essential and important to prevent the spread of this mutation and hence to save them from having any kind of clinically significant hemoglobinopathy in the future.