A review on graphene oxide (GO)–TiO ₂ nanocomposites with emphasis on the role of GO as a co-catalyst and photocatalyst, providing a synergistic effect as well as multidisciplinary photocatalytic activities in the fields of energy and the environment.

A single crystal of L-prolinium tartrate (LPT), which is an organic non linear optical material, was successfully synthesized and grown using a slow evaporation solution growth technique (SEST). The crystal structure and lattice parameters of the crystal were confirmed by powder X-ray diffraction and it was found that it belongs to the monoclinic crystal system with β = 100.380 and a noncentrosymmetric space group. The presence of strain in the grown ingot was calculated from powder X-ray diffraction measurements. The crystalline perfection was examined by high resolution X-ray diffractometry, which revealed that the crystal contained structural grain boundaries. The optical behavior of the grown specimen was analyzed by photoluminescence (PL) spectroscopy and its time resolved PL decay was calculated. The grown crystal adopted a step wise growth pattern with parallel striations, which was confirmed from the etching technique. Its ferroelectric and piezoelectric properties were also assessed. Its third order non linearity was assessed using an open aperture Z-scan technique. The thermal parameters of the LPT single crystal were calculated using a photopyroelectric technique. The mechanical strength of the single crystal at the micro level was observed by nanoindentation using the Oliver–Pharr method.

Recent trends focuses on the usage of nonlinear optical materials owing to their increasing demand in frontier areas of optical communication and switching applications. In the present work single crystal of L-threoninium picrate, an excellent material for nonlinear optical applications was grown using conventional slow evaporation solution technique to meet the increasing demand of photonics industry. The lattice parameters of the grown crystal were analysed by using powder X-ray diffraction, and it was found that it crystallised in monoclinic system with space group P2₁. The strain in the lattice of the grown crystal was calculated using Hall–Williamson relation. Crystalline perfection of the grown crystal was assessed using high resolution X-ray diffraction technique and observed that quality of crystal was fairly good. Optical transmission analysis and band gap evaluation were performed using UV-Vis spectroscopy. Laser damage threshold value for the crystal was also measured and was found to be higher than most of reported organic single crystals. Optical homogeneity of the crystal and birefringence was evaluated using modified channel spectrum method. Thermal behaviour of the grown specimen was examined by using photopyroelectric technique. Further its various mechanical properties, such as hardness, stiffness, young's modulus, were measured using nanoindentation technique.

This study presents the source apportionment of coarse-mode particulate matter (PM₁₀) extracted by 3 receptor models (PCA/APCS, UNMIX, and PMF) at semi-urban sites of the Indian Himalayan region (IHR) during August 2018–December 2019. In this study, water-soluble inorganic ionic species (WSIIS), water-soluble organic carbon (WSOC), carbon fractions (organic carbon (OC) and elemental carbon (EC)), and trace elements of PM₁₀ were analyzed over the IHR. Nainital (62 ± 39 µg m⁻³) had the highest annual average mass concentration of PM₁₀ (average ± standard deviation at 1 σ), followed by Mohal Kullu (58 ± 32 µg m⁻³) and Darjeeling (54 ± 18 µg m⁻³). The annual total ∑WSIIS concentration order was as follows: Darjeeling (14.02 ± 10.01 µg m⁻³) > Mohal-Kullu (13.75 ± 10.21 µg m⁻³) > Nainital (10.20 ± 6.30 µg m⁻³), contributing to 15–30% of the PM₁₀ mass. The dominant secondary ions (NH₄⁺, SO₄²⁻, and NO₃⁻) suggest that the study sites were strongly influenced by anthropogenic sources from regional and long-range transport. Principal component analysis (PCA) with an absolute principal component score (APCS), UNMIX, and Positive Matrix Factorization (PMF) were used for source identification of PM₁₀ at the study sites of the IHR. All three models showed relatively similar results of source profiles for all study sites except their source number and percentage contribution. Overall, soil dust (SD), secondary aerosols (SAs), combustion (biomass burning (BB) + fossil fuel combustion (FFC): BB+FFC), and vehicular emissions (VEs) are the major sources of PM₁₀ identified by these models at all study sites. Air mass backward trajectories illustrated that PM₁₀, mainly attributed to dust-related aerosols, was transported from the Thar Desert, Indo-Gangetic Plain (IGP), and northwestern region of India (i.e., Punjab and Haryana) and Afghanistan to the IHR. Transported agricultural or residual burning plumes from the IGP and nearby areas significantly contribute to the concentration of carbonaceous aerosols (CAs) at study sites.

An L-arginine 4-nitrophenolate 4-nitrophenol dihydrate (LAPP) single crystal has been grown by adopting a slow evaporation solution growth technique (SEST). The crystal structure and its lattice dimensions along with the space group were confirmed through single crystal X-ray diffraction and it was found that the crystal belongs to a monoclinic crystal system with the space group P2₁. Using Hall–Williamson's equation, the strain present in the single crystal was ascertained. The functional groups of the title compound were identified using heteronuclear correlation methods (HETCOR) and Raman spectroscopy. The optical parameters of the grown single crystal were evaluated using UV-vis-NIR analysis. Thermal parameters like the specific heat, thermal effusivity, thermal diffusivity and conductivity of the LAPP single crystal were computed from the photopyroelectric effect. Furthermore, mechanical stability parameters like the hardness, stiffness and Young's modulus were examined using a nanoindentation technique. The ferroelectric behavior and laser damage threshold were also assessed.

The semi-organic non linear optical single crystal of L-proline cadmium chloride monohydrate was successfully synthesized and the single crystal was grown by a slow evaporation solution growth technique, using double distilled water as the solvent. The lattice dimensions of the grown crystal were examined by powder X-ray diffraction and it was found to belong to the orthorhombic crystal system with a noncentrosymmetric space group. Its crystallinity was assessed by a high resolution X-ray diffraction method and its structural imperfections were recorded using X-ray topography. The presence of functional groups was identified from heteronuclear correlation methods. Its optical behavior was examined by birefringence and photoluminescence and its optical constants were determined from UV-Vis. analysis. Its thermal and third order nonlinear optical properties were characterised by photopyroelectric and Z-scan methods, respectively. The mechanical and ferroelectric behavior was also assessed on the grown single crystal of L-proline cadmium chloride monohydrate.