Akhil Kumar Sen

Antimicrobial activity of metal based nanoparticles against microbes associated with diseases in aquaculture.

The emergence of diseases and mortalities in aquaculture and development of antibiotics resistance in aquatic microbes, has renewed a great interest towards alternative methods of prevention and control of diseases. Nanoparticles have enormous potential in controlling human and animal pathogens and have scope of application in aquaculture. The present investigation was carried out to find out suitable nanoparticles having antimicrobial effect against aquatic microbes. Different commercial as well as laboratory synthesized metal and metal oxide nanoparticles were screened for their antimicrobial activities against a wide range of bacterial and fungal agents including certain freshwater cyanobacteria. Among different nanoparticles, synthesized copper oxide (CuO), zinc oxide (ZnO), silver (Ag) and silver doped titanium dioxide (Ag–TiO2) showed broad spectrum antibacterial activity. On the contrary, nanoparticles like Zn and ZnO showed antifungal activity against fungi like Penicillium and Mucor species. Since CuO, ZnO and Ag nanoparticles showed higher antimicrobial activity, they may be explored for aquaculture use.

Different approaches of katira gum formulations for colon targeting.

The objective of the study is to compare the different formulations prepared by using gum, grafted gum and hydrogel of katira as a carrier for colon-specific drug delivery using in vitro methods with and without enzymes. Katira gum is naturally occurring polysaccharides containing mainly l-rhamnose and d-galactose sugar unit and small percent of d-galactouronic acid. Compared to grafted gum and hydrogel, all proportions of katira gum protect the drug from being released completely in the physiological environment of the stomach and small intestine. In vitro release studies in enzymes (Pectinex Ultra SP-L having galactouronidase activity) have demonstrated the susceptibility of katira gum to the colonic bacterial enzyme (galactouronidase activity from Pectinex Ultra SP-L) with a consequent drug release. It illustrates that katira gum, a natural polysaccharide may be suitable as a carrier for colon targeting.

Synthesis and Characterization of Thermoresponsive Terpolymer for Protein Separation

Thermoresponsive hydrogels with fixed molar ratio (25 mol%) N-isopropylacrylamide (NIPAM) and different concentration of N-tertiary butylacrylamide (NTBA) and hydroxyethylacrylamide (HEAA) were synthesized and characterized. Differential scanning calorimetry indicated that the amount of the bound water and the bound water to total water ratio increased with increasing the hydrophobic NTBA in the hydrogel. The kinetic study of the swelling of hydrogels showed that all samples followed the non-Fickian type of diffusion. The separation efficiency of hydrogels having higher content of HEAA were found to be up to 90% at 5°C but it decreases upon raising the temperature up to 30°C.

On the Importance of Purification of Sodium Polystyrene Sulfonate

Ion exchange is commonly employed for purification of sodium polystyrene sulfonate (NaPSS), a molecule widely used as a model polyelectrolyte. However, the present work demonstrates that the ion exchange process itself may introduce some extraneous species into NaPSS samples by two possible mechanisms: (i) chemical transformation of polystyrene sulfonic acid (HPSS), a relatively unstable intermediate formed during ion exchange and (ii) release of small amount of “condensed” acid from cationic resins during the elution of NaPSS molecules. Based on these observations, it is proposed that simple dialysis is adopted as a standard protocol for the purification of primary NaPSS sample.

A New High-Temperature Lithium Para-Toluene Sulfonate (LIPTSA) Salt for Rechargeable Batteries

Lithium para-toluene sulfonate [LIPTSA] was used for lithium rechargeable batteries, with poly(methyl methacrylate) [PMMA] as the base material. Tri block copolymer of PEO-PPO-PEO was used to increase the solubility of lithium salts in PMMA matrix. FTIR, TGA, XRD, impedance spectroscopy, and SEM were used for characterizations and morphological studies. LIPTSA salt is stable up to 375°C. The highest room temperature conductivity obtained was around 5 × 10−4 Scm−1. The SEM picture shows clearly the heterogeneous morphology (salt-rich phases) distributed throughout the PMMA matrix. The XRD picture indicates the presence of crystalline, which increases with an increase in salt concentration.

Homogeneous carboxymethylated orange pulp cellulose: Characterization and evaluation in terms of drug delivery.

The aim of the present study is to develop an environment-friendly method to convert orange pulp wastes to Carboxymethyl cellulose (CMC) by homogeneous substitution. Carboxymethylation of Orange pulp treated with alkaline PEG solutions was investigated and characterized by means of TGA, DSC, XRD and SEM and compared with commercial CMC. The TGA data reveals that shifting of peaks was observed towards lower temperature with increase in monochloroacetic acid (MCA). SEM studies showed greater blending of particulate powder with increasing MCA content. The crystallinity of synthesized CMC was found to be lower than the commercial CMC. Finally, the cellulosic materials were evaluated for the formulation and dissolution studies of prepared tablets. Dissolution release studies shows that synthesized cellulose (CMCOP5, CMCOP8, CMCOP11) release up to 70.1±0.04%, whereas the commercial CMC 78.184±0.07% in 8h respectively and thereby suggests that it may be used in delayed drug delivery and targeting drugs to the colon. The synthesized CMC from orange pulp may be used as substitute for the commercial CMC.

Study of thermal and flame behavior of phosphorus-based silica for epoxy composites

Phosphorous-containing silica was prepared by acid hydrolysis of sodium silicate via a cost-effective sol–gel method. Phosphorus was incorporated during synthesis of silica by adding three different phosphorus compounds namely di-sodium hydrogen orthophosphate, orthophosphoric acid, and hypophosphorous acid. The silica powder was analyzed by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and dynamic light scattering (DLS). FTIR spectrum shows the presence of phosphorous in the samples. SEM picture of phosphorous containing silica is globular whereas pure silica is fluffier. The EDX results indicate the phosphorous incorporation up to 5 wt% atomic weight. TGA analysis shows approximately 15 wt% loss up to 150 °C for oven dried samples and the residue at 700 °C is higher for phosphorous containing samples. DLS results show the particle size for all the samples near 1000 nm. Limiting oxygen index (LOI) and smoke density of the epoxy composite samples was evaluated. The LOI value of the phosphorous containing silica composite material has been slightly improved. But the burning behavior of the samples indicates the sufficient formation of protective char layer and the char analysis of the composite samples shows more bubble structure. This type of foam structure of the char protects the surface from fire propagation.Graphical abstract