From nanocorals to nanorods to nanoflowers nanoarchitecture for efficient dye-sensitized solar cells at relatively low film thickness: All Hydrothermal Process.

Simple and low temperature hydrothermal process is employed to synthesize exotic nanostructures of TiO2. The nanostructures are obtained merely by changing the nature of the precursors and processing parameters. The chloride and isopropoxide salts of titanium are used to grow high quality thin films comprising anatase nanocorals, rutile nanorods and rutile nanoflowers respectively. A novel route of addition of room temperature ionic liquid (RTIL) is used to synthesize hitherto unexplored nano-morphologies. The Bronsted Acidic Ionic Liquid [BAIL] 0.01 M, 1: 3-ethoxycarbonylethyl-1-methyl-imidazolium chloride [CMIM][HSO4] RTIL directed growth of TiO2 flowers with bunch of aligned nanorods are obtained. The structural, optical and morphological properties of hydrothermally grown TiO2 samples are studied with the different characterization techniques. The influence of these exotic nano-morphologies on the performance of dye sensitized solar cells (DSSCs) is investigated in detail. It is found that [CMIM][HSO4] can facilitate the formation of novel nanoflower morphology with uniform, dense, and collectively aligned in regular petal like oriented TiO2 nanorods and hence improves the dye adsorption and the photovoltaic performance of DSSCs, typically in short-circuit photocurrent and power conversion efficiency. A best power conversion efficiency of 6.63% has been achieved on a DSSC based on nanoflowers (TNF) film obtained from a [CMIM][HSO4] solution.

PbS quantum dot sensitized anatase TiO2 nanocorals for quantum dot-sensitized solar cell applications.

Lead sulphide (PbS) quantum dot (QD) sensitized anatase TiO(2) nanocorals (TNC) were synthesized by SILAR and hydrothermal techniques. The TNC, PbS and PbS-TNC samples were characterized by optical absorption, XRD, FT-IR, FESEM and XPS. The results show that PbS QDs are coated on the TNCs, the optical absorption is found to be enhanced and the band edge is shifted to ~693 nm as compared with plain TNCs at 340 nm. The PbS-TNC sample exhibits an improved photoelectrochemical performance with a maximum short circuit current (J(sc)) of 3.84 mA cm(-2). The photocurrent density was found to be enhanced 2 fold, as compared with those of the bare PbS photoelectrode. The total power conversion efficiency of the PbS-TNC electrodes is 1.23%.

Porous silicon: a resourceful material for nanotechnology.

Nanostructured materials possess better tunability of their properties by varying their crystallite size compared to their bulk counterparts. These properties have opened up new avenues for fabricating highly sensitive, miniaturized and cost effective devices. Some of the drawbacks of these materials can be overcome by band gap engineering and/or making composites or core shell structures. Porous silicon obtained by electrochemical etching of polished silicon is a versatile material for nanotechnology applications due to its tunable pore size, porosity, thermal and mechanical properties, optical and electrical properties, biocompatibility, biodegradability, and most importantly, compatibility with microelectronics. This article gives an overall view of the various applications of porous silicon in nanotechnology.

Nocardia asteroides keratitis in south India.

PURPOSE: To determine the risk factors, microbiological features, clinical features and other epidemiological characteristics of Nocardia keratitis seen at a tertiary eye care centre in south India. METHODS: We evaluated 31 patients with Nocardia keratitis seen over two years, from September 1999 to September 2001. Corneal scrapings were subjected to microscopy and culture using standard protocols. RESULTS: Out of 2184 corneal ulcers cultured, 31(1.42%) were found to be Nocardia asteroides. All 31(100%) were detected correctly by 10% potassium hydroxide wet mount preparation. The highest percentage of isolates was susceptible to gentamicin(100%) followed by ciprofloxacin(93.55%). Twenty four (77.42%) patients were from rural areas; 22(70.97%) were agricultural workers; 29(93.55%) had history of trauma; 2(6.45%) had previous ocular surgery; 28(90.32%) had ocular injury with soil and sand; and 22(70.97%) had ocular injury while working in the agricultural fields. Ten (32.26%) patients presented at our institute between 15 to 35 days of onset of illness, 26(83.87%) had previous medical treatment, and 15(48.39%) patients had used traditional eye medicines. The average age of the patients was 46.16 years, with a range of 11 to 75 years. No seasonal variation was observed. CONCLUSIONS: A high index of suspicion of Nocardia infection should exist in patients with a history of trauma to the eye by soil or sand. The organisms are sensitive to commonly used topical ocular antibiotics.