Stochastic upscaling of heterogeneous materials

We propose a probabilistic strategy to upscale the material spatial variability from fine to coarse scale. To implement this idea in a numerical framework, we consider the coarse-scale as stochastic, i. e. its material properties are considered uncertain and modeled as random variables/fields. Numerical examples are shown to demonstrate the applicability of proposed approach. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

One pot synthesis of imidazo[2,1-b]thiazoles and benzo[d]thiazolo[3,2-a]imidazoles

A series of imidazo[2,1-b]thiazole and benzo[d]thiazolo[3,2-a]imidazole analogues were synthesized by stirring an equimolar mixture of dibenzoylacetylene with imidazole/thiazole derivatives in toluene or acetonitrile at room temperature. The products were generated in good yields and characterized by standard analytical techniques such as IR, ¹H NMR, ¹³C NMR and mass spectrometry. The structure of products 19, 20, 22, 24 and 25 were also unambiguously confirmed by single crystal X-ray analysis.     

One-pot practical method for synthesis of functionalized 4H-chromen-5-one derivatives under catalyst and solvent-free conditions

Abstract

A facile and practical method was described for the synthesis of 4H-chromen-5-ones under catalyst- and solvent-free conditions by one-pot stirring of starting materials at 110?°C. The products were obtained by the reaction between cyclic 1,3-dicarbonyl compounds, aromatic aldehydes and (E)-N-methyl-1-(methylthio)-2-nitroethenamine (NMSM) in short duration with good to excellent yields. This simple and environmentally benign method eliminates the use of expensive, metallic and corrosive catalysts, hazardous organic solvents, and chromatographic separation.     

Curing studies of epoxy resin with nadic endcapped phosphorylated amines

Polyimides have aromatic moieties in the backbone structure which are responsible for their increased thermal stability. If phosphorus is introduced in the main chain structure of polyimides, there is further improvement in the thermal stability. This has been proved by the work carried out in our group. The polyimide having amine termination can be used for crosslinking of epoxy resins.In the present study amine terminated phosphorus containing nadicimide were taken as curing agent for DGEBA resins. The curing characteristics of DGEBA resin were studied by DSC using different amounts of nadic endcapped phosphorylated amines. DSC thermogram showed the heat of polymerization was lower as compared to system cured with aromatic amines.     

Application of copper nanoparticles containing natural compounds in the treatment of bacterial and fungal diseases

The development of nanotechnology has generated different nanoscale-sized materials, with metal-based nanomaterials being some of the most interesting and promising. Thousands of articles in various specialized journals all over the world are dedicated to different metallic nanomaterials. Metallic nanomaterials are being widely researched, with gold-, silver-, iron-, and copper-based materials showing potential in medicine. Studies have demonstrated the effect of copper nanoparticles in medicinal herbs on the prevention, control, and treatment of microbial diseases. Experiments have examined the chemical characterization and assessment of the antioxidant, cytotoxicity, antibacterial, and antifungal activities of copper nanoparticles (Cu NPs) using the aqueous extract of Stachys lavandulifolia Vahl flower. These nanoparticles were characterized by UV–visible spectroscopy, field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy, transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), and X-ray diffraction analysis. TEM and FE-SEM images exhibited a uniform spherical morphology and diameters of 10–25 nm for the biosynthesized nanoparticles. FT-IR results suggested polysaccharides and protein in S. lavandulifolia acted as reducing agents, reducing copper ions to Cu NPs. In vitro biological experiments indicated that Cu NPs have excellent antioxidant potential against 2,2-diphenyl-1-picrylhydrazyl, antifungal effects against Candida krusei, Candida parapsilosis, Candida guilliermondii, Candida glabrata, and Candida albicans, and antibacterial activities against Staphylococcus aureus, Enterococcus faecalis, Staphylococcus saprophyticus, Bacillus subtilis, Streptococcus pneumonia, Escherichia coli O157:H7, Salmonella typhimurium, Listeria monocytogenes, Proteus mirabilis, and Pseudomonas aeruginosa. These nanoparticles did not have cytotoxicity properties against human umbilical vein endothelial cells. These results indicate that the inclusion of S. lavandulifolia extract ameliorates the solubility of Cu NPs, which leads to a remarkable enhancement in fungicidal and bactericidal effects under in vitro conditions.     

Cu(I)-anchored polyvinyl alcohol coated-magnetic nanoparticles as heterogeneous nanocatalyst in Ullmann-type C–N coupling reactions

In this paper, the preparation of a novel magnetic nanocatalyst (Fe₃O₄@PVA/CuCl) is described, which involves coating of polyvinyl alcohol (PVA) onto the surface of Fe₃O₄ nanoparticles and its subsequent coordination with CuCl catalyst. The nanocatalyst was characterized by various analytical methods, including Fourier-transform infrared, X-ray diffraction, inductively coupled plasma spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy, vibrating-sample magnetometry, and EDX elemental mapping. Moreover, the nanocatalyst was efficiently used in the N-arylation of amines via the formation of a carbon–nitrogen bond between the aryl halides and amines by Ullmann-type coupling reactions. The catalyst was sufficiently stable and can be reused for at least seven times in a model Ullmann reaction without remarkable alteration in its catalytic behavior. Heterogeneity of the catalyst was investigated by a hot filtration test.     

Lipase-catalysed one-pot synthesis of thiazole-based Betti bases and their evaluation as potential cholinesterase inhibitors

Research on Chemical Intermediates - A series of 1-[aryl-(thiazol-2-ylamino)-methyl]-naphthalen-2-ol derivatives were synthesized using porcine pancreatic lipase as a catalyst. The major assets of...