Materials Science Forum Vol. 842

Abstract: This study aimed for the synthesis of 4-Aryl-2-amino-6-(4-hydroxy coumarin-3-yl) pyridine-3-carbonitriles derivatives 4, suitable for use as antibacterial, anti-oxidant and anti-inflammatory activities via a versatile, readily accessible 3-((2E)-3(aryl)prop-2-enoyl)-2H-chromen-2-one, 3, which was prepared by refluxing 3-acetyl-4-hydroxycoumarin with aromatic aldehydes in chloroform in the presence of a catalytic amount of piperidine. Then the direct reaction of the obtained chalcones 3 with malonitrile in the presence of ammonium acetate in one step gave products 4. Most of the new compound 4 exhibit moderate antibacterial activity against Gram Negative bacterial strains (E. coli, K. pneumonia, S. typhi and S. flexneri). In addition, the compounds 4 were investigated for anti-oxidant activities by super oxide radical, DPPH (2,2-Diphenyl-1-picrylhydrazyl), and hydroxyl radical scavenging assays, where most of the compounds displayed significant antioxidant activities. Furthermore, these 4-Aryl-2-amino-6-(4-hydroxy coumarin-3-yl) pyridine-3-carbonitriles 4 were evaluated for anti-inflammatory activity by indirect haemolytic and lipoxygenase inhibition assays where compounds revealed good activity. The preparation of novel metal-free phthalocyanines and metallophthalocyanine complexes 11 and 12 (MPcs, M = Co, Zn, Cu and Mn), with four peripheral 6-hydroxy-4-methylcoumarin and 6-hydroxycoumarin substituents, were also prepared by cyclotetramerization of compounds 7 and 10 with the corresponding metal salts (Zn(OAc)₂.2H₂O, Co(OAc)₂.4H₂O, CuCl, Mn(OAc)₂.4H₂O) as a template for macrocycle formation in 2-(N,N-dimethylamino)ethanol.The electronic spectra of these compounds exhibit a band of coumarin identity together with characteristic bands of the phthalocyanine core. The new compounds were screened for antibacterial activity. Most of them are active against E. coli and S. aureus. In addition, some novel 3-acetylcoumarin derivatives 17 were prepared in good yields. Their in vitro antioxidant activities were assayed by the quantitative 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity method. In this way, novel coumarin phtalonitriles derivatives 42-44 were synthesized.The synthesis of these coumarin phtalonitriles was resulting from a nucleophilic aromatic substitution reaction between 4-nitrophtalonitrile and coumarins derivatives. The complexing properties of the coumarin derivatives toward alkali metal, alkaline earth metal, some transition metals and some heavy metal cations have been investigated in acetonitrile by means of UV spectrophotometry absorption and conductivity methods. Thus, the stoichiometry of the complexes formed and their stability constants were determined. We report also in this book chapter a sequence of two ruthenium-catalyzed transformations, namely olefin cross metathesis with allylic chloride followed by elimination, which gives a straightforward access to terminal 1,3-dienes from natural products. The structures of all the new obtained compounds were confirmed by elemental analysis, IR, and multinuclear/multidimensional NMR spectroscopy (¹H, ¹³C-NMR, NOESY, HMBC) which allowed assignment of the complete network of proton and carbon atoms).

Abstract: Lead Poisoning is unfamiliar to most of the people although it is still a potent industrial disease. A new explanation for the fall of Rome, based on evidences such as the study of old bones, old Roman recipes and Lead lined pots for brewing poisons esteemed as delicious by the ancient Roman aristocrats, is given. It is concluded that decline and eventual fall of the Roman Empire was a net result of many causes and not the Lead Poisoning alone, as generally believed. It is also a mistaken belief that Lead Poisoning was an occupational hazard. Lead alkyls used in Gasoline are environmental poisons subtly poisoning human populations globally. Inspite of strict regulations for removing most of the lead in gasoline, food cans, glazes, paints and medicines, it will continue to poison the mankind and earth’s biosphere to a significant extent for a long time.

Abstract: The intent of this chapter is to provide a basic overview of recent advances in graphene based hybrid nanostructures including their preparation, properties and potential applications in various field. The development of graphene based functional materials, has shown their tremendous interest in areas of science, engineering and technology. These materials include graphene supported inorganic nanomaterials and films, graphene-metal decorated nanostructures, Core/shell structures of nanocarbon-graphene and graphene doped polymer hybrid nanocomposites etc. They have been prepared by various methods like chemical vapor deposition of hydrocarbon on metal surface, liquid phase exfoliation of graphite, chemical reduction of GO, silver mirror reaction, catalysis, in-situ hydroxylation and sono sol-gel route, respectively. The attractive properties of graphene and their derivatives filled with metal nanoparticles (e.g. Au, Ag, Pd, Pt, Ni, and Cu) have made them ideal templates. Graphene and their derivatives have also been decorated with various semiconductor nanomaterials (e.g. metal oxides and dioxides, metal sulfides). These metal decorated graphene nanostructures can be useful as functional hybrid nanomaterials in electronics, optics, and energy based products like solar cells, fuel cells, Li-ion batteries and supercapacitors, ion exchange and molecular adsorption.

Abstract: Composite solid electrolytes of the molecular formula (1-x) Ag₂SO₄ and x TiO₂ have been prepared by solid state reaction method. The prepared materials were characterized by various techniques such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), thermogravimetric-diffrential thermal analysis (TG-DTA) and scanning electron microscopy (SEM). A sharp increase of conductivity was found in the Arrhenius plot at 693 K due to the β →α phase transition, which is slowed down with the addition of TiO₂ particles. The composition x=0.3 shows the maximum conductivity σ = 12.31 S cm^-1 at 500 °C. The temperature dependent modulus values involve single type of conduction mechanism over the entire range of temperatures. The optical band gap energy for the pure Ag₂SO₄ is found to be 4.79 eV, which has decreased with the amount of TiO₂ contents because of the defects and changes in local lattice symmetry of the composites.

Abstract: Gaur gum/copper oxide (GG/CuO) nanocomposite was synthesized using sol-gel method. GG/CuO nanocomposite was characterized by techniques such as ultraviolet-visible (UV-visible) spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermo gravimetric analysis (TGA/DTA), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS) and transmission electron microscopy (TEM). TEM analysis revealed the size of the GG/CuO nanocomposite particles in the range of 20-50 nm. GG/CuO nanocomposite was used for degradation of malachite green dye under different conditions.The degradation of MG dye was recorded 89% under irradiationtime of 180 min. The antimicrobial activity of GG/CuO was also ascertained against S. aureus. The GG/CuO nanocomposite was non-toxic for the CHO-K1 cells, oral cancer cells KB and rat glioma C6 cells.

Abstract: Utilisation of forest plantation species such as Acacia hybrid has been used in wood-based industry as an alternative to solid wood that was usually attained from natural forest. While, the under-utilised species such as Mangifera sp. is not often been used as raw material for wood products, in this study, laminated veneer lumber (LVL) has been produced from Acacia hybrid and Mangifera sp. The physical and mechanical properties of LVL were determined and compared. For physical testing, the range value of moisture content was 9.41% to 14.56%, Density was 487.90 kg/m³ to 699.10 kg/m³, thickness swelling was between 0.20% to 6.05%, water absorption between 32.71% to 91.25%, and rate of delamination from 0% to 100%. Mangifera sp. LVL has higher moisture content, rate of delamination, and water absorbency. In mechanical testing, it is been found that Acacia hybrid LVL has overall higher strength compared to Mangifera sp. LVL, in terms of static bending strength (MOR and MOE), shear strength, and compression strength. Range of value for MOR was between 10.27 N/mm² to 129.99 N/mm², MOE between 1138 N/mm² to 16472.93 N/mm², shear strength between 0.43 N/mm² to 3.40 N/mm², and compression between 139.45 N/mm² to 6749.74 N/mm². For physical testing, the overall result of p-value for moisture content, water absorption, and delamination were significant at p ≤ 0.05, while density and thickness swelling were not significant at p ≥ 0.05. For overall result, the p-value for static bending strength (MOR and MOE) was significant at p ≤ 0.05 while for shear strength and compression strength were not significant at p ≥ 0.05.

Abstract: Starch was isolated from sweet potato and the process was standardized. It was found that the treatment ‘T₈’ containing (0.25% potassium meta-bisulphite (KMS) and 0.12% citric acid) had shown excellent and promising result so far as residual protein, yield, past clarity and colour of the isolated starch was concerned. Chemical modification of isolate sweet potato starch at 3% and 5% (w/v) levels was carried out by acetylation using vinyl acetate concentration (4 to 10 %) and dual-modification using propylene oxide at a specific level of 7% and adipic acid anhydride (0.05 to 0.12%). Biodegradable films were prepared from the isolated native and modified starches. Glycerol at levels such as (0.25g/g, 0.35g/g, and 0.45g/g) was used as a plasticizer in the film preparation. Thickness of bio-films increased with increase in glycerol and starch concentrations whereas solubility decreased with increase in starch concentration and modification levels. Water and acid solubility of films prepared from native starch were highest which decreased in the acetylated starch films and further decreased in cross-linked starch films. With increase in starch and glycerol concentration tensile and puncture strengths of bio-films increased. Dual-modified starch films had shown higher mechanical strength than acetylated starches. The biodegradability was higher for native bio-films followed by acetylated starch and least for dual-modified films.

Abstract: Treatments in healthcare utilizing implants, grafts, carriers and scaffolds divulge conspicuous and dire need of perfectly complementary materials which opens new vistas for research and other exploration in this field. The vast array and assemblage of various combinations of biomaterials have evinced immaculate promising applications in healthcare sector without excluding the fact that suitability and intricacy of the constructs is equally significant. This manuscript is an attempt to sort out the agglomeration of biomaterials as well as to provide a more explicit manifestation of the eminent giant leaps in the biomedical applications. Shortage of human organs essential for liver transplantation has led to the explorations in the tissue engineering arena. This manuscript specifically highlights most of the pertinent developments in the vicinity of liver tissue engineering utilizing polymers and composites. Tissue engineered products having live cells are less susceptible to immune rejection. Hence, this potent phenomenon which utilizes scaffolds of biomaterials has been discussed here thoroughly.

Abstract: The detection and determination of aflatoxins at nanogram level is important from human health point of view. Aflatoxins exhibit acute toxicity demonstrating teratogenic, mutagenic and carcinogenic effects. Amongst the available aflatoxins, B₁, B₂, G₁, G₂, M₁ and M₂ have been the more frequently analysed aflatoxins by chromatographic, spectroscopic and immuochemical methods. Because of the presence of aflatoxins at trace level in food and feedstuff used for human and animal consumption, new analytical methods have been designed for sensitive and selective detection and quantification of aflatoxins. Each of the employed analytical methods, described herein, such as thin layer chromatography, high performance liquid chromatography, gas chromatography and immunochemical methods, among others, has inherent merits and demerits in aflatoxins analysis. This chapter critically examines each of the analytical methods currently in use in the analysis of aflatoxins. Deviating from the earlier approaches, this chapter focuses on the need of methodologies that have negligible environmental impact. Though most of the existing methods are highly sensitive and reasonably safer to use but still there is the need of development of new green methodologies focusing on the reduction of solvent consumption, replacement of environmentally hazardous solvents with more benign alternatives, miniaturization of instrumentation and solvent-free sample preparation.