Abiral Tamang

DNA-Assisted β-phase Nucleation and Alignment of Molecular Dipoles in PVDF Film: A Realization of Self-Poled Bioinspired Flexible Polymer Nanogenerator for Portable Electronic Devices.

A flexible nanogenerator (NG) is fabricated with a poly(vinylidene fluoride) (PVDF) film, where deoxyribonucleic acid (DNA) is the agent for the electroactive β-phase nucleation. Denatured DNA is co-operating to align the molecular -CH2/-CF2 dipoles of PVDF causing piezoelectricity without electrical poling. The NG is capable of harvesting energy from a variety of easily accessible mechanical stress such as human touch, machine vibration, football juggling, and walking. The NG exhibits high piezoelectric energy conversion efficiency facilitating the instant turn-on of several green or blue light-emitting diodes. The generated energy can be used to charge capacitors providing a wide scope for the design of self-powered portable devices.

Bacterial (BKH1) assisted silica nanoparticles from silica rich substrates: A facile and green approach for biotechnological applications

A green technique of silica nanoparticles (SiO2-NPs) formation by using a thermophilic bacterium (BKH1) as biological template is demonstrated here. SiO2-NPs are synthesized from inorganic (magnesium tri-silicate), and organic (tetraethyl orthosilicate) precursor with the help of BKH1 bacteria. BKH1 derived SiO2-NPs are subjected to Atomic Force Microscopy, Transmission Electron Microscopy, and Field Emission Scanning Electron Microscopy equipped with Energy Dispersive X-ray Analyzer to establish nanoparticle morphology. In addition, Infrared Spectroscopy reveals the presence of chemical and functional groups in SiO2-NPs samples and X-ray diffraction, the amorphous nature. The Zeta potential (ζ) reveals substantial stability of bacteria derived SiO2-NPs in the aqueous environment. Presence of two intense luminescence peaks in the UV and visible regions merits the bacteria derived SiO2-NPs for use as an optical probe in biomedical applications. This novel mode of bacteria derived SiO2-NPs formation is eco-friendly and ambient temperature synthesis approach. It avoids the complex protocol of multi-steps synthesis of silica nanoparticles, hence likely to be cost-effective. In-depth translation research is suggested for the synthesis of silica nanoparticles in large quantities using thermophilic BKH1 template.

Genetically-enriched microbe-facilitated self-healing concrete – a sustainable material for a new generation of construction technology

The fundamentals of engineering and structural properties such as mechanical strength, durability, bond strength, and self-healing behaviour of a genetically-enriched microbe-incorporated construction material have been explored in the present study. The alkaliphilic Bacillus subtilis bacterium is able to survive inside the concrete/mortar matrices for an extended period due to its spore forming ability. The bioremediase-like gene of a thermophilic anaerobic bacterium BKH2 (GenBank accession no. KP231522) was thus transferred to the bacillus strain to develop a true self-healing biological agent. Incorporation of the transformed bacterial cells at different concentrations in the bio-concrete/mortar exhibited higher mechanical strengths and improved durability of the samples in comparison to the normal cement–sand mortar/concretes. Microstructural analyses confirmed the formation of a novel gehlenite (Ca2Al2SiO7) phase besides calcite deposition inside the matrices of the transformed Bacillus subtilis-amended cementitious materials. The gradual development of nano rod-shaped gehlenite composite within the bio-mortar matrices was due to the biochemical activity of the bioremediase-like protein expressed within the incorporated bacterial cells. This development significantly increased the true self-healing property as well as enhanced the mechanical strength of the bio-concrete/mortar material which was sustained for a prolonged period. This study demonstrates a new approach towards the enhancement of structural properties and true self-healing activity by genetically-enriched spore-forming Bacillus sp. with advancement towards sustainable and green construction technology.

Anti-microbial efficiency of nano silver–silica modified geopolymer mortar for eco-friendly green construction technology

A silver–silica nano composite based geopolymer mortar has been developed by simple adsorption of silver in a suitable amount of a colloidal silica suspension for anti-bacterial property development. The silver nanoparticles (3–7 nm) were attached on the surface of 20–50 nm sized silica nanoparticles. The silver–silica nano-composite was characterized by Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) and energy dispersive X-ray spectral analysis. Mechanical strength, durability and mechanistic anti-bacterial activity of the silver–silica nano composite modified geopolymer mortar (GMAg–Si) were investigated and compared to nano silica modified geopolymer mortar (GMSi) and control cement mortar (CM). To accesses the anti-microbial efficacy of the samples, 99% mortality for Gram positive and Gram negative bacteria was calculated. Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values were determined from batch cultures. The addition of 6% (w/w) of the silver–silica nano composite in the geopolymer mortar cured at ambient temperature shows substantial improvement in mechanical strength, durability and anti-bacterial property. Reactive Oxygen Species (ROS) generation and cell wall rupture as observed from fluorescence microscopy and Field Emission Scanning Electron Microscopy (FESEM) may be possible reasons behind the anti-bacterial efficacy of silver–silica nano composite modified geopolymer mortar.

Biogenic synthesis of silver nanoparticles from Cassia fistula (Linn.): In vitro assessment of their antioxidant, antimicrobial and cytotoxic activities

The present study reports on biogenic-synthesised silver nanoparticles (AgNPs) derived by treating Ag ions with an extract of Cassia fistula leaf, a popular Indian medicinal plant found in natural habitation. The progress of biogenic synthesis was monitored time to time using a ultraviolet-visible spectroscopy. The effect of phytochemicals present in C. fistula including flavonoids, tannins, phenolic compounds and alkaloids on the homogeneous growth of AgNPs was investigated by Fourier-transform infrared spectroscopy. The dynamic light scattering studies have revealed an average size and surface Zeta potential of the NPs as, -39.5 nm and -21.6 mV, respectively. The potential antibacterial and antifungal activities of the AgNPs were evaluated against Bacillus subtilis, Staphylococcus aureus, Candida kruseii and Trichophyton mentagrophytes. Moreover, their strong antioxidant capability was determined by radical scavenging methods (1,1-diphenyl-2-picryl-hydrazil assay). Furthermore, the AgNPs displayed an effective cytotoxicity against A-431 skin cancer cell line by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, with the inhibitory concentration (IC50) predicted as, 92.2 ± 1.2 μg/ml. The biogenically derived AgNPs could find immense scope as antimicrobial, antioxidant and anticancer agents apart from their potential use in chemical sensors and translational medicine.

Protective Role of Raw-Turmeric Rhizomes Against Nicotine-Induced Complications of Beedi (Indian Cigarette) Workers

Introduction: The unscientific process of beedi (Indian smoking element) production under constant exposure of nicotine dust in India induces serious health disorders to the workers. Beedi produces more tar in smoke than cigarette due to lack of any filtering process. Sometimes active consumption of beedi and other tobacco products makes the users more vulnerable to cancer, respiratory diseases and cardiovascular disorders etc. Objective: The present study was designed to observe the protective effects of raw turmeric rhizomes on health conditions of the beedi workers who were exposed to nicotine dust for 8-10 hours daily for a long duration. Methods: General health checkup, blood glucose levels, lipid profiles and the hemogram profiles etc. of the workers from two beedi factories (Canning of South 24 Parganas District and Bankura of Bankura District, both in West Bengal, India) were conducted before and after the consumption of laboratory processed raw turmeric rhizomes (80 mg/kg body weight/day by chewing) for 8 weeks. Blood samples (5 ml) were collected from all the workers before and after the completion of the study and analyzed for estimation of different parameters. Results: The results showed significant improvement in the general health conditions of the factory workers who consumed raw-turmeric rhizomes. Significant improvement of blood pressure, blood glucose levels and lipid profiles and also improvement of creatinine, serum protein and SGOT/SGPT levels of the treated volunteers were noted. The results also showed improvement in the enzymes levels of SOD, GSH and GPX in the serum of rhizomes consumed workers. Conclusion: It is concluded that turmeric rhizomes are effective in the amelioration of nicotine-induced complications. It would be a better therapeutic supplement for the improvement of health for the workers who are compelled to work under nicotinic dust environment for a long time.

Poly[diaquo(1,10-phenanthroline-κ2N1:N10)(μ2-sulphato-κ2O:O′)copper(II)]: hydrothermal synthesis, crystal structure and magnetic properties

Of late, hydrothermal synthesis has gained much interest in the synthesis of metal–organic hybrid complexes with fascinating architectures and topologies. Product formation in such syntheses often depends on the nature of solvents, counter ions, pH and the ligand geometry. Copper-1,10-phenanthroline, or similar ligand systems, have been very popular in supramolecular chemistry over the years. Hence, a new metal–organic hybrid complex poly[diaquo(1,10-phenanthroline-κ2N1:N10)(μ2-sulphato-κ2O:O′)copper(II)], i.e., [Cu(C12H8N2)(H2O)2(μ-SO4)]n was synthesized by the hydrothermal method. Physico-chemical characterization of the complex was done using FTIR spectroscopy, single crystal X-ray diffraction, TGA, EPR, SQUID and FESEM. Single crystal X-ray diffraction studies revealed it to be three-dimensional with space group I2/c (monoclinic) and the unit cell dimensions are a = 7.0081 (3), b = 13.8198 (7) and c = 14.2897 (8) A; the axial angles are α = 90°, β = 99.282 (5)° and γ = 90°. It features chains in which two successive pairs of Cu(II) ions are connected by SO4 bridges and Cu(II) ions, each coordinated to two H2O molecules and two N-atoms of 1,10-phenanthroline, and the title complex has a distorted octahedral geometry. The alternating polymeric chains are connected through extensive hydrogen bonds between two O-atoms of SO4 bridges from one chain and H atoms of the two coordinated H2O molecules of another chain in the three dimensional architecture. Alternating chains are shifted with respected to each other leading to the formation of zigzag channels within the crystal structure. EPR and SQUID studies revealed the paramagnetic nature of the complex.