Knowledge and understanding of land use and water quality nexus is an important precursor for assessing the human-water interactions and sustainable freshwater management. In this study, the land use/cover change (LUCC) and water quality assessment with respect to drinking and irrigational purposes were carried out in Phewa Lake, Nepal. A total of 20 water samples were collected during the winter and summer seasons in 2017 and were analysed for major hydrochemical variables. The water quality index of Phewa Lake was found to be 5.15 and 2.57 during the winter and summer, respectively, indicating the suitability of water for drinking purposes. The results revealed that the electrical conductivity, sodium percentage, and sodium adsorption ratio were found to be 38.80 µS/cm, 16.99, and 0.10, respectively in the summer and 85.06 µS/cm, 14.68, and 0.15, respectively in the winter. Similarly, permeability index, Kelly’s ratio, magnesium hazard, cation ratio of soil structural stability, and Wilcox diagram exhibited that the water was suitable for irrigation in both seasons with relatively better quality in the summer. The dynamic pattern of LUCC in the Phewa watershed exhibited an increase in the spatial extent of forest, shrub-land, grassland, and built-up area, whereas decreasing trend of agricultural land, barren land, and water bodies. Irrespective of the seasonality, the LUCC-water quality nexus showed elevated concentrations in the proximity of the urban settlements. The present study could be helpful for the restoration of water quality by sustainable land-use practices in the Himalayan region.

Securing water to satisfy the needs of humans and the ecosystem is one of the prime issues worldwide. This study aims to characterize the hydrochemical properties and water quality of Phewa Lake, Nepal. The mean pH and DO were found to be 7.98 and 6.08 mg/L, respectively. The ionic dominancy of water follows the order of Ca2+>Na+>K+>Mg2+, and HCO3−>SO42−>Cl−>NO3−. The Piper plot characterizes the Ca-HCO3 type of water facies, and the Gibbs diagram indicates the rock weathering as a major controlling mechanism. The high ratios of (Ca2+ + Mg2+)/TZ+, (Ca2+ + Mg2+)/(Na++ K+), Ca2+/Na+, and HCO3− /Na+, i.e., 0.84, 5.33, 6.48, and 5.36, respectively also confirmed the dominancy of carbonate weathering. The drinking and irrigational indices revealed that the lake water was relatively better in monsoon compared to the pre-monsoon season. The study provides new insights on hydrochemical characteristics which contribute to the sustainable management of Ramsar-listed lakes in the Himalayas.

A triazole, 2-(4-amino-5-mercapto-4H-1,2,4-triazol-3-yl)phenol, has been prepared from 2-hydroxybenzoic acid by routine multi-step chemical synthesis. It was then used in synthesizing two different Schiff base ligands (L1 and L2). Their respective oxovanadium (IV) complexes (ML1 and ML2) were consequently synthesized and characterized by different experimental techniques like elemental analysis, FTIR spectroscopy, UV-Visible spectroscopy, and EPR spectrometry. The cyclic voltammetry measurements showed the electrochemically stable nature of the complexes. The powder X-ray diffraction patterns revealed the presence of monoclinic crystals with particle sizes of ca. 15-17 nm for both complexes. DFT calculations were performed for the determination of geometrical models, energetic stability, electronic properties, spectral features, and reactivity of the synthesized ligands and complexes. The spectral characterization of the complexes suggests a square-pyramidal geometry around VO (IV)group and was supported by computational results derived from the proposed models. This work shows that computational calculation along with experimental characterization provides better insights into new chemical compounds and their properties that could be performed in parallel as a regular tool.

Nanotechnology is the most emerging field in the area of different scientific research. Various methods of synthesis of nanoparticles are available. The wet chemical synthesis method is applicable in the extraction of silica nanoparticles from Rice Husk Ash (RHA). Rice husk is a form of waste product from the rice milling industries which is produced in an abundance amount in and around the country. Rice husk which is generally left on the field as a waste contains 60% silica content and can be economically viable raw materials for the extraction of silica [1-2]. Initially, Rice husk was burnt to obtain its ash. Then, a simple bottom-up approach, the sol-gel method was applied, and fine powder silica in the nanoscopic range was extracted. After extraction of it, internal arrangement and average particle size were recognized by XRD while molecular components and structure present in silica were identified by FTIR. The obtained silica was then used in making of ceramics matrix nanocomposites (particularly silica-sand cement block), and its mechanical properties were identified by compressive strength test using Instron testing machine which was found to be increased in comparing with the compressive strength of ceramics composite (Sand cement block) prepared in the same ratio and same size of mold as that of ceramics matrix nanocomposites. The ceramics matrix nanocomposites acquiring higher mechanical strength than Ceramics composite occurred due to the incorporation of Silica nanoparticles.

Agricultural waste-based cellulose fibers have gained significant interest for a myriad of applications. Grewia optiva (G. optiva), a plant species, has been widely used for feeding animals, and the small branches’ bark is used for making rope. Herein, we have extracted cellulose fibers from the bark of G. optiva species via chemical treatments (including an alkaline treatment and bleaching). The gravimetric analysis revealed that the bark of G. Optiva contains cellulose (63.13%), hemicellulose (13.52%), lignin (15.13%), and wax (2.8%). Cellulose microfibre (CMF) has been synthesized from raw fibre via chemical treatment methods. The obtained cellulose fibers were crosslinked and employed as the matrix to encapsulate the bioactive plant extracts derived from the root of Catharanthus roseus (C. roseus). The microscopic images, XRD, FTIR, and antibacterial/antioxidant activity confirmed the encapsulation of natural extracts in the cellulose microfiber. The microscopic images revealed that the encapsulation of the natural extracts slightly increased the fiber’s diameter. The XRD pattern showed that the extracted cellulose microfiber had an average crystalline size of 2.53 nm with a crystalline index of 30.4% compared to the crystalline size of 2.49 nm with a crystalline index of 27.99% for the plant extract incorporated membrane. The water uptake efficiency of the synthesized membrane increased up to 250%. The antimicrobial activity of the composite (the CMF-E membrane) was studied via the zone inhibition against gram-positive and gram-negative bacteria, and the result indicated high antibacterial activity. This work highlighted G. optiva-derived cellulose microfiber as an optimum substrate for antimicrobial scaffolds. In addition, this paper first reports the antimicrobial/antioxidant behavior of the composite membrane of the C. roseus extract blended in the G. optiva microfiber. This work revealed the potential applications of CMF-E membranes for wound healing scaffolds.