Flame-retardant Cotton Fabric Through Graft Copolymerisation

In an attempt to impart flame-retarding properties to the cotton fabric, post-graftingphosphorylation reactions on grafted cotton fabric were carried out. Photochemical graftcopolymerisation of 4-vinyl pyridine (4-VP) onto cotton fabric using benzophenone asphotosensitiser was carried out. Maximum percentage of grafting Pg, (18.50 %) was obtainedunder optimum  conditions; irradiation time 75 min, 0.5 ml of  benzophenone,  [4-VP]=748.71 x10-2 mole/l and 5 ml of water in the reaction mixture. Aliphatic alcohols of varying chain lengthdecreased percentage of grafting. The pendant pyridine rings of the 4-VP grafted cotton fabricwere converted to pyridinium chloride followed by the reaction with acrylamide to give 2-amido-ethylpyridiniumchloride. This was subjected to phosphorylation reaction with PCl3/petroleumether. The phosphorylated grafted cotton fabric burns only in the presence of flame with veryslow propagation of the flame (only 3.8 cm2) was found to burn of the total area of 147 cm2 with0.12 g of the ash content. Characterisation of gray cotton fabric and modified cotton fabric wascarried out by FTIR, thermogravimetric analysis, crease recovery, and moisture absorption studies

Propagation of Rayleigh waves in non-homogeneous orthotropic elastic media under the effect of magnetic field

The influence of magnetic field on the propagation of Rayleigh waves in an inhomogeneous, orthotropic elastic solid medium has been discussed. The method of separation of variable is used to find the frequency equation of the surface waves. The obtained dispersion equations are in agreement with the classical results when magnetic field and non-homogeneity are neglected   Keywords: Inhomogeneity, Orthotropic elastic solid,   field, Magnetic field

Engineered atherosclerosis-specific zinc ferrite nanocomplex-based MRI contrast agents

BACKGROUND: Cardiovascular diseases are the most prevalent cause of morbidity and mortality affecting millions of people globally. The most effective way to counter cardiovascular complications is early diagnosis and the safest non-invasive diagnostic approach is magnetic resonance imaging (MRI). In this study, superparamagnetic ferrite nanoparticles doped with zinc, exhibiting highly enhanced saturation magnetization and T2 and computed tomography (CT) contrast were synthesized. These nanoparticles have been strategically engineered using bovine lactoferrin (Lf), polyethylene glycol (PEG), and heat shock protein (Hsp)-70 antibody specifically targeting atherosclerosis with potential therapeutic value. The nanocomplexes were further validated in vitro to assess their cytotoxicity, internalization efficiency, effects on cellular proliferation and were assessed for MRI as well as X-ray CT in ex vivo Psammomys obesus rat model. RESULTS: Optimized zinc doped ferrite nanoparticles (Zn0.4Fe2.6O4) with enhanced value of maximum saturation magnetization value on 108.4 emu/g and an average diameter of 24 ± 2 nm were successfully synthesized. Successfully incorporation with bovine lactoferrin, PEG and Hsp-70 (70 kDa) antibody led to synthesis of spherical nanocomplexes (size 224.8 nm, PDI 0.398). A significantly higher enhancement in T2 (p < 0.05, 1.22-fold) and slightly higher T1 (1.09-fold) and CT (1.08-fold) contrast compared to commercial ferrite nanoparticles was observed. The nanocomplexes exhibited effective cellular internalization within 2 h in both THP-1 and Jurkat cells. MRI scans of contrast agent injected animal revealed significant arterial narrowing and a significantly higher T2 (p < 0.05, 1.71-fold) contrast in adult animals when compared to juvenile and control animals. The excised heart and aorta agar phantoms exhibited weak MRI contrast enhancement in juvenile animal but significant contrast enhancement in adult animal specifically at the aortic arch, descending thoracic aorta and iliac bifurcation region with X-ray CT scan. Histological investigation of the contrast agent injected aorta and heart confirmed site target-specific accumulation at the atherosclerotic aortic arch and descending thoracic aorta of the adult animal with severely damaged intima full of ruptured microatheromas. CONCLUSION: Overall, the study demonstrates the strategic development of nanocomplex based bimodal MRI and CT contrast agents and its validation on Psammomys obesus for atherosclerosis diagnostics

Designing artificial electron transfer pathways in dioxygen-activating metalloenzymes

This thesis describes efforts to introduce new redox reactivity into two classes of dioxygen-activating enzymes. First, I investigated modified cytochrome c peroxidase (CcP). Here, a series of Trp residues were introduced between the heme active site and the surface of the enzyme to serve as a hole transfer wire. The addition of two mutations (A193W and Y229W) introduced new oxidation chemistry to CcP, as evaluated using aromatic substrate oxidation assays. This enzyme is a functional model for lignin peroxidase enzymes and provides a strong foundation for the development of new protein-based oxidation catalysts. Second, we investigated cyanobacterial aldehyde deformylating oxygenase (cAdo) enzymes. Here, we characterized and investigated three Ru-cAdo models. To provide the four electrons required for catalysis, we introduced a Ru-tris(diimine) photosensitizer to solvent exposed cysteine residues. Through NMR and GC-MS, we gained an insight into the catalytic activity of Ru-cAdo. This work highlights the nature of protein based electron transfer and points toward other underlying factors that dictate catalytic efficiency

Development of flame retardant cotton fabric through grafting and post- grafting reactions

312-318Low energy UV radiation induced graft copolymerization of methacrylamide (MAAm) onto cotton fabric has been carried out using benzophenone as photosensitizer to introduce functionalities that can react with phosphorus containing compounds to impart flame retardancy. The flammability behaviour of the grey cotton, cotton-g-poly (MAAm) and phosphorylated cotton–g-poly(MAAm) fabrics has been studied on a manual flammability tester. Maximum percentage of grafting (116.1%) is achieved at 75min irradiation time; 176.47x10⁻² moles/L [MAAm]; 5 mL photosensitizer; and 3 mL reaction medium. The grey cotton and cotton-g-poly (MAAm) fabrics react with phosphorous trichloride and diethylphosphite to introduce phosphorous element, thus imparting flame retardancy. Phosphorylated grafted fabric shows improved flame retardant behaviour in comparison to grafted fabric, which is better than the grey fabric. All the fabric samples have been characterized by FTIR, thermogravimetric analysis and crease recovery behaviour