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BackgroundIn-silico methods are an integral part of modern drug discovery paradigm. Virtual screening, an in-silico method, is used to refine data models and reduce the chemical space on which wet lab experiments need to be performed. Virtual screening of a ligand data model requires large scale computations, making it a highly time consuming task. This process can be speeded up by implementing parallelized algorithms on a Graphical Processing Unit (GPU).ResultsRandom Forest is a robust classification algorithm that can be employed in the virtual screening. A ligand based virtual screening tool (GPURFSCREEN) that uses random forests on GPU systems has been proposed and evaluated in this paper. This tool produces optimized results at a lower execution time for large bioassay data sets. The quality of results produced by our tool on GPU is same as that on a regular serial environment.ConclusionConsidering the magnitude of data to be screened, the parallelized virtual screening has a significantly lower running time at high throughput. The proposed parallel tool outperforms its serial counterpart by successfully screening billions of molecules in training and prediction phases.

Atomically thin layers of molybdenum disulfide (MoS 2 ) were examined to facilitate electron transport in titanium dioxide (TiO 2 ) nanofiber network for dye sensitized solar cell (DSSC) applications. Raman active modes observed at 382 cm À1 and 406 cm À1 confirmed the presence of atomically thin MoS 2 in TiO 2 and transmission electron microscopic studies showed MoS 2 with a lattice spacing of 3.12 Å . DSSCs using MoS 2 incorporated TiO 2 nanofiber as a photo-anode resulted in 27% enhancement in photo-conversion efficiency (h) than that of the DSSC using only TiO 2 as an electron acceptor. A 26% enhancement in the short circuit current density (J SC ) achieved by incorporating 0.1 weight % of MoS 2 nanoflakes in the bulk of TiO 2 confirmed efficient electron transport achieved by suppressing the probability of electron-hole capture by TiO 2 surface states due to the additional electron transport pathways established by MoS 2 which facilitated the photo-generated electrons to reach the transparent electrode by skipping the TiO 2 surface states. Results suggest that further increase in the quantity of MoS 2 in TiO 2 impedes the electron transport in the bulk as observed with 7% and 38% reduction in h for 0.2 and 0.3 weight % of MoS 2 in TiO 2 . This suggests that the DSSC performance can be increased for an optimum concentration of MoS 2 in TiO 2 by establishing efficient transport pathways towards the transparent electrode.

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High-temperature annealing in tungsten disulfide resulted in heterogeneous WS 2 -WO 3 in which intra-(within WS 2 and WO 3 ) and inter-(between WS 2 and WO 3 ) grain boundaries were observed, which were highly critical for charge transport and recombination. The heterogeneous WS 2 -WO 3 phase was evidenced by observing the coexistence of d-spacing values of 0.26 nm (WS 2 ) and 0.37 nm (WO 3 ) in transmission electron microscopic (TEM) studies. Further systematic high-resolution TEM studies elucidated that intra-grain boundaries separated crystallites within WS 2 and WO 3 , while inter-grain boundaries separated WS 2 from WO 3 . As WS 2 and WO 3 are both n-type, these defects are acceptor-like in the grain boundaries and they actively participate in the capture (trapping) process, which impedes charge transport characteristics in the heterogeneous WS 2 -WO 3 films. Plasma treatment in the heterogeneous WS 2 -WO 3 film, for 60 minutes using argon, energetically modulated the defects in the intra/ inter-grain boundaries, as evidenced from detailed comparative photocurrent characteristics obtained individually in (i) pristine WS 2 , (ii) heterogeneous WS 2 -WO 3 and (iii) Ar plasma-treated heterogeneous WS 2 -WO 3 films under blue and green lasers, along with AM1.5 (1 sun) illumination. Detrimental roles (trapping/de-trapping and scattering) of grain boundary states on photoelectrons were seen to be significantly suppressed under the influence of plasma.