On the dispersion equation of Love waves in a porous layer

Summary The paper is concerned with the propagation of Love waves in a porous layer over an inhomogeneous half-space due to a point source. The dispersion equation for Love waves in a porous layer has been derived. The effects of porosity and inhomogeneity in the half-space have been shown graphically on the dispersion curves. The theory pointed out by Biot for the porous medium has been applied to solve the problem with the help of Green's function technique.With 4 Figures     

Sulphated polysaccharides from Indian samples of Enteromorpha compressa (Ulvales,Chlorophyta): Isolation and structural features

Heteroglycan and xyloglucan rich fractions were extracted from Indian samples of Enteromorpha compressa in 25% yield by sequential extractions with water and alkali. This heteroglycan is sulfated and has an apparent molecular mass of 55 kDa. Chemical structural analysis of this polysaccharide revealed a branched structure having 1,4- and 1,2,4-linked rhamnose 3-sulphate, 1,4-linked glucose, 1,3- and 1,6- linked galactose, 1,4- and terminally linked glucuronic acid and 1,4-linked xylose partially sulfated on O-2. Chemical and spectroscopic analysis showed that the 4-M KOH extracted hemicellulosic fraction contained an unusual β-(1,4)-linked linear xyloglucan. Enzyme hydrolysis and analysis of the resulting fragments by matrix-assisted laser desorption ionization-time of flight-mass spectrometry (MALDI-TOF-MS) showed that this linear polymer contained partially sulfated Glc₃Xyl₂ or Glc₄Xyl₂ as oligomeric building subunits.     

Degradation profiles of polyester–urethane (hydroxylated polyester/diphenylmethane diisocyanate) and polyester–melamine (hydroxylated polyester/hexamethoxymethylmelamine) coatings: An accelerated weathering study

The successful material performance of coatings depends on the environmental conditions to which they are exposed. The effects of the diol structure and acetoacetylation on the weathering degradation of hydroxylated polyester (HP)/hexamethoxymethylmelamine and HP/diphenylmethane diisocyanate clear coatings were studied. The acetoacetylation of HPs led to better performance for higher application solids than the acetoacetylation of their base counterparts. Weathering degradation profiles were investigated with dynamic mechanical thermal analysis, scanning electron microscopy, and X‐ray photoelectron spectroscopy. The structural variations of the building blocks and acetoacetylation were found to be important for enhancing the stability of coatings at higher application solids. Polyester–urethane coatings were more stable toward weathering than polyester–melamine coatings. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1069–1081, 2005     

Interesting aspects of the analysis of resistivity in Li irradiated Bi-2212

Differently heat treated and 55 MeV Li³⁺ beam irradiated Bi₂Sr₂Ca₁Cu₂O_8+δ (Bi-2212) high temperature superconductors have been studied from the analysis of resistivity in the normal state as well as near the superconducting transition. For all the unirradiated and irradiated samples the so-called linear temperature dependence of the normal state resistivity, in a wide temperature range, can well be understood within the variable range hopping (VRH) conduction scenario. Near and above the bulk superconducting transition, the fluctuation enhanced conductivity (paraconductivity) analysis shows a noteworthy modification of the conduction process due to radiation induced defects.     

GALDS: a complete framework for designing multiclock ASICs and SoCs

A Globally Asynchronous, Locally Synchronous (GALS) system with dynamic voltage and frequency scaling can use the slowest frequency possible to accomplish a task with minimal power consumption. With the mechanism for implementing dynamic voltage scaling at each synchronous domain left up to the designer, our Globally Asynchronous, Locally Dynamic System (GALDS) provides a top-down, system-level means to maximize power reduction in an integrated circuit and facilitate system-on-a-chip (SoC) design. Our solution includes three distinct components: a novel bidirectional asynchronous FIFO to communicate between independently clocked synchronous blocks , an all-digital dynamic clock generator to quickly and glitchlessly switch between frequencies and a digitally controlled oscillator to generate the global fixed frequency clocks required by the all-digital dynamic clock generator. In addition to being capable of reducing power consumption when combined with dynamic voltage scaling, a GALDS design benefits from numerous other advantages such as simplified clock distribution, high performance operation and faster time-to-market through the modular nature of the architecture.     

Mechanical and tribological behavior of alumina and alumina‐CNT reinforced hybrid unsaturated polyester composites

Micro‐ and nano‐scale wear behavior of alumina vis‐á‐vis alumina‐carbon nanotube‐reinforced hybrid composites has been studied. In comparison to the pristine alumina, the alumina‐carbon nanotube hybrid reinforcement resulted in reduced scratch depth and lower frictional coefficient. Addition of carbon nanotube has effectively modified the pristine alumina into a superior wear resistant filler. POLYM. COMPOS., 37:1577–1586, 2016. © 2014 Society of Plastics Engineers     

Dielectric properties of EVA/LDPE TPE system: Effect of nanosilica and controlled irradiation

The pristine nanosilica particles were melt‐blended with a model low‐density polyethylene–ethylene vinyl acetate thermoplastic elastomers (TPE) system by varying the sequence of addition and nanosilica contents. Bis‐[3‐(triethoxysilyl)propyl] tetrasulfide (Si‐69) was used to improve the state of dispersion of nanosilica particles in one of the compositions. The dielectric properties of the TPE systems are influenced remarkably by loadings of silica, variation of sequence of addition of ingredients during mixing, addition of Si‐69, and controlled electron beam irradiation. The effects of interfacial and orientation polarization on the permittivity and the loss tangent were studied by dielectric analyses. These were correlated with the structures of various nanocomposites. An attempt has also been made to support the dielectric results by volume resistivity measurements, measurements of breakdown voltage, and swelling–deswelling kinetic results. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

Investigation on Sodium Benzoate Release from Poly(Butylene Adipate‐Co‐Terephthalate)/Organoclay/Sodium Benzoate Based Nanocomposite Film and Their Antimicrobial Activity

Polymeric nanocomposites embedded with nontoxic antimicrobial agents have recently gained potential industrial significance, mainly for their applicability to preserve food quality and ensure safety. In this study, a poly(butylene adipate‐co‐terephthalate) (PBAT)/organoclay (CMMT) based nanocomposite film doped with sodium benzoate (SB) as antimicrobial agent was prepared by a solution mixing process. A homogenous dispersion of organoclay (cetyltrimethylammonium‐modified montmorillonite [CMMT]) in PBAT matrix was observed by X‐ray diffraction and transmission electron microscopy. PBAT/CMMT nanocomposite film showed higher barrier properties against water and methanol vapor compared to the PBAT film. The release of SB from PBAT and its nanocomposite film was measured and the relevant data were fitted to the Weibull model. The higher values of Weibull's shape factor and scale parameter as corroborated by experimental findings indicated faster rate of SB release from PBAT/CMMT/SB nanocomposite film, when compared to the pristine PBAT film. Bacterial inhibition studies were accomplished against 2 food pathogenic bacteria, Bacillus subtilis and Staphylococcus aureus, by determining the zone of inhibition and corresponding growth profiles. Both bacterial inhibition studies and growth profiles established that PBAT/CMMT/SB demonstrated better antimicrobial activity than PBAT/SB film. Therefore, PBAT/CMMT/SB nanocomposite film can be used for food packaging application as it showed good barrier properties and antimicrobial activity against food pathogenic bacteria.