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ABSTRACT: Among all fuel cells, proton exchange membrane fuel cells (PEMFCs) are appealing energy conversion devices in portable and transportation applications because of their higher efficiency, excellent ability to reduce air pollution, lightweight, generation of less noise due to the absence of mechanical components, quick start-up time and non-involvement in the combustion process. This review article emphasizes the importance of perfluorosulfonic acid (PFSA) polymer-based proton exchange membranes (PEMs) for fuel cell applications and their recent achievements, difficulties, and prospects. The most widely used PEMs for low-temperature PEMFCs are PFSA polymer-based membranes and some non-fluorinated polymers such as sulfonated poly(ether ketone) (SPEEK), sulfonated polysulfone (SPSF), sulfonated polyimide (SPI), and sulfonated polystyrene (SPS). Among these PEMs, PFSA membranes (such as Nafion) are the most often utilized low-temperature PEM for fuel cell applications because of their outstanding chemical, mechanical, and thermal stability with higher proton conductivity under-hydrated conditions. Due to some limitations of PFSA membranes, such as poor conductivity in anhydrous conditions, high manufacturing costs, and degradation of their properties at higher temperatures, research on low-temperature PEM has been shifted to the development of polymer electrolyte composite membranes incorporating various multifunctional organic, inorganic, and hybrid fillers. The PFSA polymer composite membranes show better chemical, thermal, and oxidative stability with higher proton conductivity and fuel cell performance than pristine PFSA membranes. In addition, the PFSA polymer composite membranes maintain proton conductivity and fuel cell performance in low humidity conditions. These findings show that developing suitable PFSA polymer composite membranes could enhance the possibility of commercial applications of PEMFCs.

Employing epoxy polymer and pristine and aromatic amine and hydroxyl functionalized SWCNTs in poly(ether ether ketone) (PEEK), novel polymer nanocomposite models were created. Molecular dynamics (MD) simulations were used to explore the interfacial, mechanical, and structural features of single-walled carbon nanotube (SWCNT) reinforced PEEK/epoxy matrix (BM) systems. We used MD simulation techniques to show how covalently functionalizing SWCNTs and blending PEEK with a polymer containing hydroxy‑functional groups can improve the interfacial and mechanical properties of PEEK nanocomposites. This study showed that –CH2C6H4NH2, –CH2C6H4OH group grafted SWCNT improve the interfacial and mechanical properties of PEEK-based nanocomposites due to the formation of hydrogen bonds between the filler materials and the polymer matrix, as well as better filler dispersion into the polymer matrix. The improvement of properties of polymer nanocomposites depends on the extent of the interaction of nanoparticles with the polymer matrix. Aromatic amine and hydroxyl (-CH2C6H4NH2, and -CH2C6H4OH) functionalization of SWCNTs is required for their high-performance engineering applications. Because epoxy polymer has a great ability to form hydrogen bonds with fictionalized SWCNT, adding 10% epoxy polymer to the BM increased the interfacial strength, elastic modulus, and shear modulus of SWCNT composites. This study provides a novel technique to improve the properties of polymer nanocomposites by covalently functionalizing SWCNTs.

In agricultural soil, cadmium (Cd) pollution compromises soil health, reduces crop yield, and produces Cd-contaminated crops. Bio-based approaches are necessary as an eco-friendly and sustainable solution to mitigate Cd-polluted areas. A heavy metal-resistant rhizobacterial strain (AS10) has been isolated from a heavy metal-defiled rice field. The 16S rDNA sequence and MALDI-TOF MS analyses of ribosomal protein reveal its identity closely similar to Enterobacter cloacae. The strain was found to withstand up to 4000 μg/ml Cd2+, 3312 µg/ml Pb2+ and 1500 µg/ml As3+. The Cd2+ removal efficiency was recorded as high as 72.11% when grown in 4000 μg/ml Cd2+. The strain's Cd-accumulation efficiency was also apprehended by TEM-EDAX followed by XRD-XRF-FTIR analyses. Besides, the strain showed solubilization of inorganic phosphate, ACC deaminase activity, nitrogen fixation and IAA production ability. Added further, the strain, as an efficient bioinoculant, significantly improved rice plant growth at the seedling stage through Cd immobilization. It prevented the surge of stress ethylene and oxidative stress in rice seedlings, resulting in overall plant growth improvement. Hence, the strain AS10 as potent plant growth-promoting rhizobacteria (PGPR) may be beneficial, especially in heavy metal-contaminated crop fields.

Phosphorus is a primary macronutrient required for normal plant health, metabolism and survival. It is present in soil in compound insoluble form for which plant cannot uptake it directly from the soil. Some phosphate solubilizing bacteria possess some important enzymes for phosphate solubilization as well as mineralization. Alkaline (or basic) phosphatase (EC 3.1.3.1) is a type of zinc containing dimeric hydrolase enzyme responsible for removing the phosphate groups from various kinds of molecules including nucleotides, proteins, and alkaloids. Unlike acid phosphatases alkaline phosphatases are most effective in an alkaline environment. Alkaline phosphatases (ALPs) are of immense importance in various agricultural industries including dairy industries for testing successful pasteurization process. In this present study, Pseudomonas aeruginosa phosphatase was selected for a detailed computational investigation to exploit its physicochemical characteristics, structural properties including 3D model, model quality analysis, phylogenetic assessment and functional analysis using a number of available standard bioinformatics tools. The protein having average molecular weight about 51 kDa, was found thermostable and alkaline in nature belonging to metalloenzyme superfamily. Specifically, the thermostable behavior of the protein is suitable for the dairy industry. Moreover, this theoretical overview will help researchers to get an idea about the predicted protein structure and it may also help to design genetically engineered phosphate solubilizing bacteria by designing specific primers.