6 research outputs found
Gas Sensing Studies of an n-n Hetero-Junction Array Based on SnO2 and ZnO Composites
A composite metal oxide semiconductor (MOS) sensor array based on tin dioxide (SNO2) and zinc oxide (ZnO) has been fabricated using a straight forward mechanical mixing method. The array was characterized using X-ray photoelectron spectroscopy, scanning electron microscopy, Raman spectroscopy and X-ray diffraction. The array was evaluated against a number of environmentally important reducing and oxidizing gases across a range of operating temperatures (300–500 °C). The highest response achieved was against 100 ppm ethanol by the 50 wt% ZnO–50 wt% SnO2 device, which exhibited a response of 109.1, a 4.5-fold increase with respect to the pure SnO2 counterpart (which displayed a response of 24.4) and a 12.3-fold enhancement with respect to the pure ZnO counterpart (which was associated with a response of 8.9), towards the same concentration of the analyte. Cross sensitivity studies were also carried out against a variety of reducing gases at an operating temperature of 300 °C. The sensors array showed selectivity towards ethanol. The enhanced behaviour of the mixed oxide materials was influenced by junction effects, composition, the packing structure and the device microstructure. The results show that it is possible to tune the sensitivity and selectivity of a composite sensor, through a simple change in the composition of the composite
Gas Sensing Studies of an n-n Hetero-Junction Array Based on SnO2 and ZnO Composites
A composite metal oxide semiconductor (MOS) sensor array based on tin dioxide (SNO2) and zinc oxide (ZnO) has been fabricated using a straight forward mechanical mixing method. The array was characterized using X-ray photoelectron spectroscopy, scanning electron microscopy, Raman spectroscopy and X-ray diffraction. The array was evaluated against a number of environmentally important reducing and oxidizing gases across a range of operating temperatures (300–500 °C). The highest response achieved was against 100 ppm ethanol by the 50 wt% ZnO–50 wt% SnO2 device, which exhibited a response of 109.1, a 4.5-fold increase with respect to the pure SnO2 counterpart (which displayed a response of 24.4) and a 12.3-fold enhancement with respect to the pure ZnO counterpart (which was associated with a response of 8.9), towards the same concentration of the analyte. Cross sensitivity studies were also carried out against a variety of reducing gases at an operating temperature of 300 °C. The sensors array showed selectivity towards ethanol. The enhanced behaviour of the mixed oxide materials was influenced by junction effects, composition, the packing structure and the device microstructure. The results show that it is possible to tune the sensitivity and selectivity of a composite sensor, through a simple change in the composition of the composite
Methyl-Thiazoles: A Novel Mode of Inhibition with the Potential to Develop Novel Inhibitors Targeting InhA in Mycobacterium tuberculosis
InhA
is a well validated Mycobacterium tuberculosis (Mtb) target as evidenced by the clinical success of isoniazid.
Translating enzyme inhibition to bacterial cidality by targeting the
fatty acid substrate site of InhA remains a daunting challenge. The
recent disclosure of a methyl-thiazole series demonstrates that bacterial
cidality can be achieved with potent enzyme inhibition and appropriate
physicochemical properties. In this study, we report the molecular
mode of action of a lead methyl-thiazole, along with analogues with
improved CYP inhibition profile. We have identified a novel mechanism
of InhA inhibition characterized by a hitherto unreported “Y158-out”
inhibitor-bound conformation of the protein that accommodates a neutrally
charged “warhead”. An additional novel hydrophilic interaction
with protein residue M98 allows the incorporation of favorable physicochemical
properties for cellular activity. Notably, the methyl-thiazole prefers
the NADH-bound form of the enzyme with a <i>K</i><sub>d</sub> of ∼13.7 nM, as against the NAD<sup>+</sup>-bound form of
the enzyme