Bio-accumulation of metals on reef associated organisms of Lakshadweep Archipelago

Tissue samples of marine organisms from the coastal waters of Agatti Island were subjected to analysis of metals (cadmium, cobalt, copper, iron, magnesium, manganese, nickel, lead and zinc), using Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES) for the assessment of the present condition of the Island ecosystem and compiling the baseline data for future monitoring, with respect of metal accumulation of marine organisms. Tissue samples of fish, shellfish and seaweed revealed that the metals have different levels of accumulation viz. Cd = 0.08-0.14, Co = 0.01-0.02, Cu = 0.16-0.98, Fe = 3.19-5.3, Mg = 86.73-152.45, Mn = 0.17-0.55, Ni = 0.06-0.26, Pb = 0.11-0.46 and Zn = 3.26-14.2 μg g⁻¹ dry wt. Metal concentrations were more in shellfish and less in finfish. Concentrations of toxic metals such as Cd, Co, Ni and Pb were well below the permissible limits proposed by the World Health Organization.     

Infiltration-Growth Processing of NdBa2Cu3O7-delta Superconductor

NdBa₂Cu₃O_7-delta (Nd-123) superconductor has been processed to obtain a highly textured microstructure with micrometer-sized spherical Nd₄Ba₂Cu₂O₁₀ (Nd-422) inclusions through a process that involves the infiltration of liquid phases into a shaped preform followed by its slow cooling through the peritectic formation temperature of Nd-123. The process was carried out in high-purity argon (maximum of 4 ppm of oxygen) to reduce the formation of low- T _c solid solutions. A major advantage of the process is that it minimizes the possibility of Nd-422 coarsening in the liquid. The result is a very uniform distribution of nearly spherical Nd-422 inclusions with 80% of the particles having a diameter less than 1 µm, in the highly textured Nd-123 matrix. Since the present process eliminates shrinkage and large hollows within the interior of the samples, it can enable the fabrication of 3-dimensional complex-shaped objects with good dimensional tolerance and high J _c for applications. The critical current densities in the Nd-123/Nd-422 composites have been measured and the values obtained are discussed in the context of the microstructure of the material.     

Development of hydroxyapatite nanoparticles reinforced chlorinated acrylonitrile butadiene rubber/chlorinated ethylene propylene diene monomer rubber blends

Hydroxyapatite nanoparticles (HA) reinforced polymer blend based on chlorinated nitrile rubber (Cl-NBR) and chlorinated ethylene propylene diene monomer rubber (Cl-EPDM) were prepared. Resulting blend composites were analyzed with regard to their rheometric processing, crystallinity, glass transition temperature (T_g), mechanical properties, oil resistance, AC conductivity, and transport behavior. The decrease in optimum cure time with the addition of HA is more advantageous for the development of products from these blend nanocomposites. The XRD, FTIR, and SEM confirmed the attachment and uniform dispersion of HA nanoparticles in the Cl-NBR/Cl-EPDM blend. The good compatibility between polymer blend and nanoparticles was also deduced by the formation of spherically shaped HA particles in the blend matrix determined by TEM analysis. DSC analysis showed an increase in T_g of the blend with the filler loading. The addition of HA particles to the blend produced a remarkable increase in tensile and tear strength, hardness, AC conductivity, abrasion, and oil resistance. The diffusion of blend composites was decreased with an increase in penetrant size. The diffusion mechanism was found to follow an anomalous trend. Among the blend composites, the sample with 7 phr of HA not only showed good oil and solvent resistance but also a remarkable increase in AC conductivity and mechanical properties.     

Factors influencing rheological characteristics of silver thick film paste and its correlation to multilayer ceramic processing

The rheological properties of silver thick film paste are influenced by the particle size, morphology of silver particles and by the nature of the filler. Rheological properties in-turn influence the multilayer processing parameters and properties. Silver particles, synthesised with gum Arabic (Ag/GA) as the dispersant resulted in agglomerated particles with irregular morphology. Ag/GA-based thick film paste exhibited thixotropic characteristics. Silver powder synthesised with polyvinyl alcohol (Ag/PVA) as the dispersant resulted in well-dispersed, spherical, free-flowing powder with narrow particle size distribution and exhibited pseudoplastic behaviour. The rheological characteristics of Ag/GA-based thick film paste are not influenced by the filler addition. Influence of filler addition is distinctly noted in the rheological characteristics of Ag/PVA-based thick film paste. The homogeneous mixing of Ag/PVA particles with filler and reproducible rheological characteristics of the corresponding thick film paste resulted in excellent printability with good edge-definition and repeatable properties.     

Effect of neodymium‐doped titanium dioxide nanoparticles on the structural,mechanical, and electrical properties of poly(butyl methacrylate) nanocomposites

Nanocomposites based on neodymium‐doped titanium dioxide (Nd‐TiO₂)/poly(n‐butyl methacrylate) (PBMA) have been prepared by an in situ polymerization of butyl methacrylate monomer with varying concentrations of Nd‐TiO₂ nanoparticles. The resulting nanocomposites have been analyzed by ultraviolet (UV)–Visible spectroscopy, Fourier‐transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscope (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis, and impedance analyzer (TGA). The results of UV and FTIR spectroscopy have indicated the interaction of nanoparticles with the PBMA matrix. Spherically shaped nanoparticles with an average size of 10–25 nm have been revealed in the TEM and their homogeneous dispersion, and interaction of polymer matrix has been confirmed by SEM and XRD studies. The thermal stability and glass transition temperature of the composites were significantly enhanced by the addition of nanoparticles. The AC conductivity and dielectric properties of nanocomposites have been found to be higher than pure PBMA, and the maximum electrical properties have been observed for 7 wt% composite. The reinforcing nature of the nanoparticles in PBMA has been reflected in the improvement in tensile strength measurements. The result indicated that the tensile strength of nanocomposites have greatly enhanced by the addition of Nd‐TiO₂ nanoparticles whereas the elongation at break decreases with the loading of nanofillers. To understand the mechanism of reinforcement, tensile strength values have been correlated with various theoretical modeling. The research has been found to be promising in the development of novel materials with enhanced tensile strength, dielectric constant, and thermal properties, which may find potential applications in energy storage and nanoelectronic devices. J. VINYL ADDIT. TECHNOL., 25:9–18, 2019. © 2018 Society of Plastics Engineers     

Coral spawn and bathymetric slicks in Synthetic Aperture Radar (SAR) data from the Timor Sea,north‐west Australia

Annular‐ to crescent‐shaped low backscatter SAR slicks over carbonate reefs and shoals in the Timor Sea that exhibit ‘feathering’, and within the coral spawning period for the region, are interpreted to be caused by a coral spawn event. This represents the first time that such an event has been interpreted through satellite remote sensing. Additionally, ocean current data and detailed swath bathymetry of the sea floor to the south‐east of the coral spawn slicks suggest that elongate repeating slicks in this area are related to current flow over submarine channels. Assessment of these slicks in association with ancillary data, such as bathymetry, current velocities, weather, and timing of SAR acquisition allow a more robust interpretation of their origins. Through differentiating coral spawn and bathymetric slicks from oil and other biological slicks in shallow carbonate systems, such as the Timor Sea, petroleum and environmental assessments for these areas can be improved.     

Arginine-rich coconut kernel diet influences nitric oxide synthase activity in alloxandiabetic rats

BACKGROUND: Coconut kernel protein (CKP) has been reported to contain significant amounts of L ‐arginine. Its potential effect on glucose homeostasis, possibly through the nitric oxide synthase (NO) pathway, was therefore investigated in alloxan‐induced diabetic rats. Diabetes was induced by a single intraperitoneal dose of alloxan (150 mg kg^?1 body weight). Experimental rats were grouped as follows: Group I, normal control; Group II, diabetic control; Group III, diabetic + CKP; Group IV, diabetic + L ‐arginine; Group V, diabetic + L ‐arginine + L ‐N^G‐Nitroarginine methyl ester (L ‐NAME). Purified CKP isolated from dried coconut kernel and L ‐arginine was administered to rats along with a semi‐synthetic diet for 45 days. L ‐NAME (0.5 mg kg^?1 body weight) was given to Group V animals. After the experimental period, serum glucose, insulin, activities of liver nitric oxide synthase and arginase, liver glycogen levels and histopathology of the pancreas were evaluated. RESULTS: Serum glucose, insulin and antioxidant enzyme activities and liver glycogen levels were found to be restored to basal levels in CKP‐fed rats. Decreased arginase and increased nitric oxide synthase (NOS) activities were found in CKP‐ and arginine‐fed rats. L ‐NAME treatment showed a partial effect on these parameters. Histopathology revealed that CKP and L ‐arginine feeding reduced the diabetes‐related pancreatic damage in treated rats compared to the diabetic control. CONCLUSION: The results observed in this study indicate that the potential antidiabetic activity of CKP may be through an arginine‐NO pathway leading to pancreatic beta cell regeneration. Copyright © 2012 Society of Chemical Industry     

Facile synthesis,characterization and material properties of a novel poly(vinyl cinnamate)/ nickel oxide nanocomposite

A poly(vinyl cinnamate) (PVCin) composite was synthesized by a simple one step in situ polymerization of vinyl cinnamate with nickel oxide (NiO) nanoparticles. The structural, morphological and thermal properties of the nanocomposite were characterized using Fourier transform (FT)‐Raman, FT infrared (FTIR) and UV spectroscopies, X‐ray diffraction (XRD), high‐resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), differential scanning calorimetry and vibrating sample magnetometry (VSM) measurements. FT‐Raman, FTIR and UV spectroscopy results revealed the characteristic absorption and shifts of peaks of the polymer matrix, the shifts being attributed to the interaction of NiO nanoparticles with the polymer chains. The structural and morphological analysis using XRD, HRTEM and FESEM showed the uniform arrangement of nanoparticles within the polymer chains. VSM showed the ferromagnetic nature of the composite with an increasing saturation of magnetism. The glass transition temperature (T_g) of the composite was higher than that of pure PVCin and T_g of the composite increased with increasing nanoparticle content. The electrical resistivity of the nanocomposite was studied from AC and DC conductivity measurements. AC and dielectric properties were markedly enhanced in the whole range of frequency due to the presence of NiO nanoparticles. DC conductivity of the nanocomposite was much higher than that of PVCin and the conductivity of the nanocomposite increased with increasing content of NiO nanoparticles. © 2016 Society of Chemical Industry     

In Situ Synthesis,Characterization and Conductivity of Copper Sulphide/Polypyrrole/Polyvinyl Alcohol Blend Nanocomposite

This work focused on the preparation, characterization and conductivity studies of copper sulphide nanoparticle incorporated polypyrrole (PPy)/polyvinyl alcohol (PVA) blend by in situ chemical oxidative polymerization. The blend nanocomposites were examined by FTIR, SEM, XRD, TGA and electrical studies. The complexation of CuS with the polymer was confirmed by FTIR. The surface observed in the SEM image clarifies the uniformity in morphology. The XRD pattern reveals that the nanoparticle incorporated PPy and their blend showed a crystalline nature. TGA and conductivity studies indicated that the blend nanocomposites attain better thermal stability and conductivity than original polypyrrole and PPy/PVA blend.