Predictions and measurements of sound transmission through a periodic array of elastic shells in air

Analytical and numerical approaches have been made to the problems of (a) propagation through a doubly periodic array of elastic shells in air, (b) scattering by a single elastic shell in air, and (c) scattering by a finite periodic array of elastic shells in air. Using the Rayleigh identity and the Kirchhoff-Love approximations, a relationship is found between the elastic material parameters and the size of the bandgap below the first Bragg frequency, which results from the axisymmetric resonance of the shells in an array. Predictions and laboratory data confirm that use of a suitably "soft" non-vulcanized rubber results in substantial insertion loss peaks related to the resonances of the shells. Inclusion of viscoelasticity is found to improve the correspondence between predictions and data. In addition the possible influences of inhomogeneity due to the manufacturing of the elastic shells (i.e., the effects of gluing sheet edges together) and of departures from circular cylindrical cross-sections are considered by means of numerical methods.     

An efficient synthesis of ferrocenyl imidazo[1,2-a]pyridines

Abstract  

An efficient and simple synthesis of ferrocenyl 3-aminoimidazo[1,2-a]pyridines by the three-component reaction of ferrocenecarboxaldehyde, isocyanides, and 2-aminopyridines in the presence of a catalytic amount of InCl₃ in ethanol at room temperature is reported.     

Zinc and copper oxide nanoparticles decrease synaptosomal glutamate uptake: an in vitro study

Nanoparticles (NPs) are considered as an important environmental risk factor for cognitive impairments and neurodegenerative disorders. Recent evidences have reported a glutamatergic system response against air-borne NPs. Zinc and copper oxides (ZnO and CuO) NPs are the most common metal oxide NPs in industries. The effects of these NPs on hippocampal voltage-dependent ion channels and spatial cognition have been previously studied. However, there is a lack of evidence regarding the effects of ZnO and CuO NPs on glutamatergic synapse neurotransmission in central nervous system. In the present study, the effects of ZnO and CuO NPs on glutamate (Glu) release and uptake have been investigated in isolated nerve terminals (synaptosomes). Our findings have shown that, even in high doses of ZnO and CuO NPs, no significant effect on Glu release is observed. However, a decrease has been observed in uptake of Glu. Hence, ZnO and CuO NPs can be considered as hazardous agents inducing neurodegenerative disorders through Glu excitotoxicity.     

Electrospray ionization tandem mass spectrometry of the star‐shaped propoxylated diethylenetriamine polyols

The collision‐induced dissociation of the protonated five‐arm star propoxylated diethylenetriamine polyols was studied under electrospray conditions. Two product ion series were detected because of the cleavage of the C? N bonds in the initiator moiety. No backbone fragmentation of the polyether chains was observed, which allowed to explore the initiation and side‐chain propagation process of the oligomers. On the basis of MS/MS spectra, it is probable that the rate of the initiation is larger than that of the chain propagation. The propylene oxide repeat units attach to the five arms with approximately the same probability. Furthermore, it was found that the collision energy necessary to obtain 50% fragmentation (CE₅₀) was linearly dependent on the molecular weight of the polyols. Copyright © 2015 John Wiley & Sons, Ltd.     

Isolation and Characterization of Zygomycetes Fungi from Tempe for Ethanol Production and Biomass Applications

Mixed fungal cultures used for making tempe, a fermented soy bean food, were screened for biomass conversion. Thirty-two zygomycetes strains from two tempe cultures were isolated and identified as Rhizopus, Mucor, Rhizomucor, and Absidia species based upon morphology. The dry weight biomass of these strains contained 49% to 63% protein and 10?C24% chitosan. The strains with the best growth performance were selected and registered at Culture Collection of Gothenburg University as Rhizomucor CCUG 61146 and Rhizomucor CCUG 61147. These strains were able to grow both aerobically and micro-aerobically. Their ethanol yields were 0.38?C0.47, 0.19?C0.22, and 0.31?C0.38?g/g on glucose, xylose, and a mix sugars consisting of cellobiose, glucose, xylose, arabinose, galactose, and mannose, respectively. The biomass yield of the strains varied between 65 and 140?mg dry weight/g glucose.     

Synthesis and characterization of nickel sulfide nanoparticles via cyclic microwave radiation

In current study, nanoparticles of NiS were synthesized by applying microwave radiation. The effect of concentration of sulfur source, reaction time, and power of microwave irradiation on the treatment process was investigated. The morphology, structure, and composition of the as-synthesized nanostructures have been confirmed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Optical properties of as-prepared sample were investigated by photoluminescence spectroscopy; the emission peak is at 555.04 nm and shows the blue shift.     

Acoustic insertion loss due to two dimensional periodic arrays of circular cylinders parallel to a nearby surface

The acoustical performances of regular arrays of cylindrical elements, with their axes aligned and parallel to a ground plane, have been investigated through predictions and laboratory experiments. Semi-analytical predictions based on multiple scattering theory and numerical simulations based on a boundary element formulation have been made. Measurements have been made in an anechoic chamber using arrays of (a) cylindrical acoustically-rigid scatterers (PVC pipes) and (b) thin elastic shells. Insertion loss (IL) spectra due to the arrays have been measured without and with ground planes for several receiver heights. Data and predictions have been compared. The minima in the excess attenuation spectrum i.e., attenuation maxima due to the ground alone resulting from destructive interference between direct and ground-reflected sound waves, tend to have an adverse influence on the band gaps (BG) related to a periodic array in the free field when these two effects coincide. On the other hand, the presence of rigid ground may result in an IL for an array near the ground similar to or, in the case of the first BG, greater than that resulting from a double array, equivalent to the original array plus its ground plane mirror image, in the free field.     

Cufe2O4 Nanoparticles: A Magnetically Retrievable Catalyst for Green Synthesis of Novel 2-(3-(Dicyanomethyl)-2-Oxoindolin-3-Ylthio)Acetic Acids

Abstract

A highly efficient and green method for the synthesis of new 2-(3-(dicyanomethyl)-2-oxoindolin-3-ylthio)acetic acids is described using magnetically recoverable and reusable CuFe₂O₄ nanoparticles. A wide variety of aryl isatylidene malononitrils underwent Micheal addition with thioacids to afford novel 2-(3-(dicyanomethyl)-2-oxoindolin-3-ylthio)acetic acids in good to excellent yields. The reaction protocol is operationally simple and mild. Moreover, water as solvent makes the reaction procedure eco-friendly and economically viable. All products were characterized by NMR and IR spectroscopies.     

Integrated Process for Ethanol,Biogas, and Edible Filamentous Fungi-Based Animal Feed Production from Dilute Phosphoric Acid-Pretreated Wheat Straw

Integration of wheat straw for a biorefinery-based energy generation process by producing ethanol and biogas together with the production of high-protein fungal biomass (suitable for feed application) was the main focus of the present study. An edible ascomycete fungal strain Neurospora intermedia was used for the ethanol fermentation and subsequent biomass production from dilute phosphoric acid (0.7 to 1.2% w/v) pretreated wheat straw. At optimum pretreatment conditions, an ethanol yield of 84 to 90% of the theoretical maximum, based on glucan content of substrate straw, was observed from fungal fermentation post the enzymatic hydrolysis process. The biogas production from the pretreated straw slurry showed an improved methane yield potential up to 162% increase, as compared to that of the untreated straw. Additional biogas production, using the syrup, a waste stream obtained post the ethanol fermentation, resulted in a combined total energy output of 15.8 MJ/kg wheat straw. Moreover, using thin stillage (a waste stream from the first-generation wheat-based ethanol process) as a co-substrate to the biogas process resulted in an additional increase by about 14 to 27% in the total energy output as compared to using only wheat straw-based substrates.

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