Improved Photo-Detection Using Zigzag TiO2 Nanostructures as an Active Medium.

Zigzag TiO2 nanostructures were fabricated using oblique angle deposition technique. The field emission gun-scanning electron microscope (FEG-SEM) image shows that the TiO2 zigzag nanostructures were ~500 nm in length. Averagely two times enhanced UV-Vis absorption was recorded for zigzag structure compared to perpendicular TiO2 nanowires. The main band transition was observed at ~3.4 eV. The zigzag TiO2 exhibited high turn on voltage (+11 V) than that of nanowire (+2 V) detector under dark which were reduced to +0.2 V and +1.0 V under white light illumination, respectively. A maximum ~6 fold photo-responsivity was observed for the zigzag TiO2 compared with nanowire device at + 1.0 V applied potential. The maximum photo-responsivity of 0.36 A/W at 370 nm was measured for the zigzag TiO2 detector. The TiO2 zigzag detector showed slow response with rise time of 10.2 s and fall time of 10.3 s respectively. The UV (370 nm) to visible (450 nm) wavelength rejection ratio of photo-responsivity was recorded ~4 times for the detector.

Isoniazid accumulation in Mycobacterium smegmatis is modulated by proton motive force-driven and ATP-dependent extrusion systems.

Resistance to isoniazid (INH), a frontline, antituberculosis drug, presents a major problem in the chemotherapy of tuberculosis. Although several targets of INH have been identified, the mechanism of INH resistance remains incompletely understood. This report demonstrates that INH accumulation in Mycobacterium smegmatis is enhanced both upon addition of both a proton motive force (pmf) uncoupler, carbonylcyanide m-chlorophenylhydrazone (CCCP), and upon addition of ortho-vanadate, an inhibitor of ATP-dependent efflux pumps. Both the Deltapsi and DeltapH components of the pmf are likely to be involved as judged by the effects of valinomycin and nigericin, respectively. Reserpine, an inhibitor of the human MDR1 P-glycoprotein, enhances INH accumulation in a manner similar to o-vanadate. Verapamil, a calcium channel blocker, also enhances INH uptake. Taken together, the results provide evidence of the involvement of both pmf- and ATP-dependent extrusion systems in INH efflux in M. smegmatis, making it important to evaluate the role of such systems in INH resistance in pathogenic mycobacteria.

Visual evoked response in different types of amblyopia before and after occlusion therapy.

Visual evoked response (VER) was analysed in control eyes and in different types of amblyopias. A general trend of a non-linear decrease in latency with an improvement of visual acuity has been noted. Individual correlation co-efficients between visual acuity and VER parameters in different types of amblyopias as compared to whole population showed no significant changes. The correlation co-efficient between post-treatment visual acuity and latency reflects a general trend of a non-linear decrease in latency with an improvement of visual acuity.

PIP: The visual evoked response (VER) is the gross electrical signal generated by the occipital cortex as a result of visual stimuli. The present study measured VER in 70 children under 9 years of age from Calcutta, India, with amblyopia in one eye before and after occlusion therapy. The sample included 15 children with anisometropic amblyopia, 25 with strabismic amblyopia, and 10 with stimulus deprivation amblyopia; the remainder were nonamblyopes. A general trend of nonlinear decrease in latency with an improvement of visual acuity was noted. There was no significant difference in the individual correlation coefficients of the 3 amblyopia types compared with controls between visual acuity and VER parameters.