Composite materials are emerging as a vital entity for the sustainable development of both humans and the environment. Polylactic acid (PLA) has been recognized as a potential polymer candidate with attractive characteristics for applications in both the engineering and medical sectors. Hence, the present article throws lights on the essential physical and mechanical properties of PLA that can be beneficial for the development of composites, biocomposites, films, porous gels, and so on. The article discusses various processes that can be utilized in the fabrication of PLA-based composites. In a later section, we have a detailed discourse on the various composites and nanocomposites-based PLA along with the properties’ comparisons, discussing our investigation on the effects of various fibers, fillers, and nanofillers on the mechanical, thermal, and wear properties of PLA. Lastly, the various applications in which PLA is used extensively are discussed in detail.

In this study, biological synthesis of silver nanoparticles (AgNPs) from supernatant of endophytic fungus Alternaria sp. isolated from the healthy leaves of Raphanus sativus is studied. The synthesized AgNPs are characterized using UV-vis spectroscopy and Fourier transform-infrared spectroscopy (FTIR). The structural analysis is done by powder X-ray diffraction (XRD) method. The stability of AgNPs is studied by dynamic light scattering (DLS) method. The size and shape of AgNPs are observed by transmission electron microscopy (TEM) and atomic force microscopy (AFM) and found to be spherical with an average particles size of 4-30 nm. Further, these AgNPs have been found to be highly toxic against human pathogenic bacteria, suggesting the possibility of using AgNPs as efficient antibacterial agents.

With the growing energy needs, a conscious effort has been made to use non-conventional energy sources to generate clean energy efficiently. Solar energy has always been popular among humanity. Using solar energy in heating applications is one of the most prominent ways to extract solar power. Various developments have been made to augment solar water heating system (SWHS) performance. Each modified design of SWHS has its advantages and disadvantages. Broadly, solar water heaters are categorized into two types: Flat plate solar collectors (FPSCs) and evacuated tube solar collectors (ETSCs). Earlier studies show that evacuated tube SWHS are more efficient than flat plate SWHS. Extensive research is going on the design modification of evacuated tube SWHS to enhance their efficiency. Firstly, the present review article briefly introduced the numerous types of solar collectors and their range of operation. The current work reviews various techniques used for heat transfer enhancement in SWHS, their advantages, and the region of applications. The article concentrates on research involving the usage of energy storage medium, nanomaterials, reflecting surfaces, and hybrid techniques for performance augmentation of ETSCs.