Study on degradation reactions in polyethylene terephthalate containing 5‐sulpho isophthalyl moieties

Kinetics of thermal degradation occurring on polyester containing cationic dyeable comonomer units viz. 5‐sulphoisophthalate moieties are studied by measurement of changes in intrinsic viscosity and carboxyl values on the polymer after subjecting the polymer chips to temperatures in the range 275–285°C for different residence times ranging from 5 to 60 min and comparing with the homopolymer. The activation energy values for degradation are estimated from the kinetic data. Mechanical properties of the textured yarns produced from the partially oriented yarns (POY) spun under different residence times are measured. Yarn produced with higher residence time has poor mechanical properties. The SEM images of the POY show presence of particles at the surface of the yarn due to polymer degradation. The size of the particles as seen on the surface increase with increase of retention time. Addition of thermal stabilizer helps in controlling the thermal degradation. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Coatings of PDMS-modified epoxy via urethane linkage: Segmental correlation length,phase morphology,thermomechanical and surface behavior

Modification of an aliphatic epoxy resin with silicone was carried out through urethane route. Hydroxy-terminated polydimethylsiloxane (HTPDMS) was reacted with toluene diisocyanate to form an isocyanate-capped prepolymer. The –NCO group of the prepolymer was further reacted with –OH group of an aliphatic epoxy adipate resin, obtained by reaction of adipic acid with an epoxy resin, to obtain silicone-modified epoxy resin. Silicone-modified epoxy resins containing 15 and 30 wt% of silicone prepolymer have been synthesized by this procedure. TGA analysis of the silicone-modified epoxy resin showed considerable improvement in thermal stability over the unmodified epoxy resin. Modulated differential scanning calorimetry (MDSC) was used to find the segmental correlation length of the silicone-modified polymers. The cured films of silicone-modified resins showed biphasic morphology as evidenced from scanning electron microscopy. Further, the thermomechanical property of the samples was investigated by dynamic mechanical analysis. The surface properties of the silicone-modified matrices were studied by atomic force microscopy and contact angle goniometry. The silicone-modified samples showed considerably lower surface energy, surface roughness and contact angle hysteresis compared to the unmodified resins.     

Evaluation of GABA-chitosan nanoparticle induced cell signaling activation during liver regeneration after partial hepatectomy

Liver damage due to infection, cirrhosis, accidents and diseases lead to destruction of hepatocytes and their regeneration to its original form is important for the proper functioning of the body. Gamma aminobutyric acid (GABA), a neurotransmitter, was coupled with a biopolymer chitosan and the nanosized complexes were made. The morphology was studied by scanning electron microscope and the interaction of GABA with chitosan was analysed by FT-IR spectroscopy. The interaction of GABA-chitosan nanoparticles with hepatocytes were observed by FITC labeled nanoparticles. After partial hepatectomy in male Wistar rats, DNA synthesis was estimated by tritiated thymidine uptake and the activity of thymidine kinase and protein synthesis by tritiated leucine uptake in hepatocytes. There was an increase in tritiated thymidine uptake in partially hepatectomised groups with nanoparticle treatment (GCNP) when compared to partially hepatectomised groups without nanoparticle treatment (PHNT) and with pure GABA treatment (G). Inositol 1,4,5 trisphosphate (IP3) content and gene expression of phospholipase C mRNA and nuclear factor kappa-light-chain-enhancer of activated B (NF-KB) mRNA was decreased for groups G and GCNP with respect to PHNT. Thus our results showed increased hepatocyte regeneration with decreased cell death in group G and more better with GCNP when compared to PHNT.     

GABA and 5-HT chitosan nanoparticles decrease striatal neuronal degeneration and motor deficits during liver injury

The metabolic alterations resulted from hepatic injury and cell loss lead to synaptic defects and neurodegeneration that undoubtedly contribute motor deficits. In the present study, GABA and 5-HT chitosan nanoparticles mediated liver cell proliferation influenced by growth factor and cytokines and neuronal survival in corpus striatum of partially hepatectomised rats was evaluated. Liver cell proliferation was initiated and progressed by the combined effect of increased expression of growth factor, insulin like growth factor-1 and decreased expressions of cytokines, tumor necrosis factor-α and Akt-1. This was confirmed by the extent of incorporation of thymidine analogue, BrdU, in the DNA of rapidly dividing cells. Inappropriate influx of compounds to corpus striatum resulting from incomplete metabolism elevated GABA_B and 5-HT_2A neurotransmissions compared to those treated with nanoparticles. This directly influenced cyclic AMP response element binding protein, glial cell derived neurotrophic factor and brain derived neurotrophic factor in the corpus striatum that facilitate neurogenesis, neuronal survival, development, differentiation and neuroprotection. Motor deficits due to liver injury followed striatal neuronal damage were scored by grid walk and rotarod studies, which confirmed the regain of motor activity by GABA and 5-HT chitosan nanoparticle treatment. The present study revealed the therapeutic significance of GABA and 5-HT chitosan nanoparticles in liver based diseases and related striatal neuronal damage that influenced by GABA and 5-HT.     

Spatial filter based 3D resolution improvement and polarization properties of multiphoton multiple-excitation-spot-optical microscopy

Three-dimensional (3D) resolution improvement in multi-photon multiple-excitation-spot-optical microscopy is proposed. Specially designed spatial filter is employed for improving the overall 3D resolution of the imaging system. An improvement up to a factor of 14.5 and sub-femto liter volume excitation is achieved. The system shows substantial sidelobe reduction (<4%) due to the non-linear intensity dependence of multiphoton process. Polarization effect on x-oriented and freely rotating dipoles shows dramatic change in the field distribution at the focal-plane. The resulting point-spread function has the ability to produce several strongly localized polarization dependent field patterns which may find applications in optical engineering and bioimaging.     

Cross Layer Security MAC Aware Routing Protocol for IoT Networks

Wireless Personal Communications - Proliferation Internet of Things (IoT) devices is increasing security vulnerabilities across the enterprise besides its intrinsic constraints such as processing...     

Sol–gel derived CeO2/α‐Al2O3 bilayer thin film as an anti‐coking barrier and its catalytic coke oxidation performance

A CeO₂/α‐Al₂O₃ bilayer was coated on a high temperature alloy (Incoloy 800H) by sol–gel dip‐coating and was evaluated for its potential as an anticoking barrier and coke oxidation catalyst. The bilayer effectively functioned as a barrier to metal surface catalyzed coking. The film prevented filamentous catalytic coking via blocking surface active metallic sites on the Incoloy substrate. Furthermore, the bilayer reduced the oxidation temperature of pyrolytic coke deposited on the film surface as compared to a bare oxidized Incoloy substrate, mostly owing to the oxidation catalytic activity of the CeO₂ layer. Finally, it is demonstrated that the presence of the α‐Al₂O₃ buffer layer is critically important to the overall performance. Without the α‐Al₂O₃ layer, a CeO₂ layer nearly completely lost both its barrier and oxidation catalytic functions. It is presumed that metallic species migrating from the substrate during high temperature treatments are responsible for the CeO₂ deactivation, likely by blocking catalytic sites on the CeO₂ surface. © 2018 American Institute of Chemical Engineers AIChE J, 64: 4019–4026, 2018