Stability of titanium nickelide rods loaded in the mode of martensite inelasticity

The work discusses experimental studies of stability and load capacity of titanium nickelide rods in the case of their isothermal loading by compression at the temperature of the martensite state. The experimental data are compared with the solution of the stability problem obtained within in the framework of the model of non-linear deformation of alloys with shape memory given phase and structural transformations. It has been established that the best estimate for critical forces is provided by the solution described in the concept of ??general additional structural transition.??     

Singular solitons in optical metamaterials by ansatz method and simplest equation approach

This paper derives singular 1-soliton solution for optical metamaterials. There are two integration approaches that obtains the solution. These are the ansatz approach and the simplest equation approach. The second method also leads to an additional set of solutions that emerge as a by-product. These are topological soliton, rational solution and singular periodic solution. The constraint conditions for the existence of these solutions are also exhibited. The numerical simulation of a topological 1-soliton solution is also exhibited.     

Fabrication of luminescent silver doped PbS nanowires in polymer

We report here fabrication of silver (0 to 1.76 mol%) doped PbS nanowires (radius r approximately 1.75 nm) in polymer by a simple wet chemical process. An X-ray photoelectron spectroscopy study clearly confirms the possibility of silver (Ag) doping in PbS nanowires. Both absorption and photoluminescence spectra reveal very strong quantum confinement effect in PbS nanowires as expected for a r/Bohr radius ratio approximately 0.0972 nm. Visible excitonic emission is observed at room temperature in the photoluminescence spectra of undoped and silver doped PbS nanowires in polymer. The excitonic emission is appreciably blue-shifted when doped by silver (1.76 mol%) indicating strong modification of the electronic states by magnetic silver ions. While Ag2+ centers at the substitutional lattice site show an emission band around 525 nm, Ag0 at the interstitial site act as nonradiative recombination centers. Effect of silver doping on the luminescence intensity is also discussed.     

Self‐aggregation behavior of amphiphilic polyaspartamide derivatives containing cholesterol moieties

Biodegradable amphiphilic copolymers were successfully synthesized by the conjugation of various densities of hydrophobic biocompatible cholesterol (Chol) moieties onto poly(2‐hydroxyethyl aspartamide) and poly(N‐isopropylaminoethyl‐co‐2‐hydroxyethyl aspartamide). These were obtained from polysuccinimde, the thermal polycondensation product of L‐aspartic acid, via a ring‐opening reaction with multifunctional pendant groups, including ethanolamine and N‐isopropylethylenediamine (NIPEDA). Copolymers containing 5–30 mol % Chol showed self‐aggregation behavior in aqueous solution, as evidenced by the dynamic light scattering measurement of their particle size distribution. The average particle size of these copolymers increased linearly with increasing Chol content. Moreover, the presence of secondary amine groups in the poly(2‐hydroxyethyl aspartamide)–NIPEDA system made the conjugation more efficient; however, these also seemed to accelerate the degradation of the copolymers in an aqueous medium. The degradation behavior and pH dependence of the particle size of these copolymers in aqueous solution were also examined. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Synthesis and charge carrier mobility of a solution-processable conjugated copolymer based on cyclopenta[c]thiophene

A new polymer comprising alternate thiophene and didodecyloxymethyl substituted cyclopenta[c]thiophene unit, PDCPTT, was synthesized by the Stille coupling reaction and characterized by ¹H NMR, GPC, TGA, DSC, XRD, UV-vis absorption spectroscopy, photoluminescence spectroscopy and cyclic voltammetry. The copolymer is readily soluble in tetrahydrofuran, chloroform and toluene at ambient conditions and exhibits good thermal stability as it does not exhibit noteworthy weight loss until ∼300 °C under nitrogen. This polymer possesses a broad absorption band ranging at 400-650 nm (with an optical band gap of 1.90 eV). The DFT calculation predicts the polymer to be planar and the calculated band gap is only 0.17 eV higher than the experimentally determined band gap. Didodecyloxymethyl-3,4-cyclopentane substitution on alternate thiophene in a polythiophene, hitherto unexplored, showed an effective polymer based field effect transport characteristics; exhibiting hole mobility ≈1.4 × 10⁻² cm² V⁻¹ s⁻¹.     

A study on sliding and erosive wear behaviour of atmospheric plasma sprayed conventional and nanostructured alumina coatings

Alumina coatings on stainless steel substrate (SS304) were deposited by using atmospheric plasma spray technique with a feed stock of manually granulated and sieved nano Al₂O₃ powder. The hardness, sliding, and erosive wear of the nanostructured alumina coatings (NC) were investigated and compared with that of conventional alumina coatings (CC). Pin-on disc type sliding wear test on the alumina coatings (NC and CC) was performed with load varying from 30 N to 80 N at a sliding speed of 0.5 m/s. Pot type slurry erosion test of the coatings was conducted for different concentrations of Al₂O₃ and a mixture of Al₂O₃ and SiO₂ slurry. The microstructural features of both NC and CC of alumina were characterized by using FE-SEM/EDS and SEM analysis to substantiate the failure of coatings due to wear. Wear and erosion resistance of nano alumina coating is better than the conventional alumina coating as observed in the present work. The bimodal structure of NC contributes for the enhanced wear resistance. The high fracture toughness of NC is due to suppression of cracks by partially melted particles in the coatings.     

Protective Effect of Membrane-Free Stem Cells against Lipopolysaccharide and Interferon-Gamma-Stimulated Inflammatory Responses in RAW 264.7 Macrophages

Recently, adipose-derived stem cells (ADSCs) are considered to be ideal for application in cell therapy or tissue regeneration, mainly due to their wide availability and easy access. In this study, we examined the anti-inflammatory effects of membrane-free stem cell extract (MFSC-Ex) derived from ADSCs against lipopolysaccharide (LPS)/interferon-gamma (IFN-γ) on RAW 264.7 macrophage cells. Exposure of RAW macrophages to LPS and IFN-γ stimuli induced high levels of nitric oxide (NO), cyclooxygenase-2 (COX-2), and prostaglandin E₂ (PGE₂) production. However, pretreatment with MFSC-Ex inhibited LPS/IFN-γ-induced these pro-inflammatory mediators. To clarify the molecular mechanisms underlying the anti-inflammatory property of MFSC-Ex, we analyzed nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinases (MAPKs) protein expressions by Western blotting. Our study showed that treatment of MFSC-Ex significantly down-regulated inducible nitric oxide synthase (iNOS) and COX-2 protein expressions. Furthermore, phosphorylation of extracellular signal-regulated kinase (ERK) and p38 was also blocked by treatment with MFSC-Ex, indicating that inhibitory effect of MFSC-Ex on MAPK signaling cascade may attribute to inactivation of NF-κB. From these findings, we suggest that MFSC-Ex exert anti-inflammatory activities, which suppressed LPS/IFN-γ-induced production of NO, COX-2 and PGE₂ by regulation of NF-κB and MAPK signaling pathway in RAW 264.7 macrophages. In conclusion, MFSC-Ex might provide a new therapeutic opportunity to treatment of inflammatory-related diseases.     

A differential medium for the isolation of Kluyveromyces marxianus and Kluyveromyces lactis from dairy products

A selective and differential solid medium, called Kluyveromyces Differential Medium (KDM), is described for the isolation of Kluyveromyces marxianus and K. lactis from dairy products. Its discriminative potential is based on the detection of the enzyme beta-galactosidase, in the absence of lactose. Of the more than 95 strains tested, including yeasts, bacteria, and filamentous fungus, only the strains of K. marxianus and K. lactis produced blue colonies on the medium due to the presence of X-Gal/ IPTG. The bacterial strains were not able to grow in KDM. On this basis, the medium was very satisfactory when testing naturally or experimentally contaminated dairy food products. When quality assessment tests were performed, optimal values of productivity (growth and color) and selectivity were obtained for K. marxianus and K. lactis.     

Multicarrier spread spectrum watermarking for secure error concealment in fading channel

This paper proposes a novel multicarrier spread spectrum (SS) watermarking scheme for the application of image error concealment using multicarrier-code division multiple access (MC-CDMA) with binary phase shift keying (BPSK) transmission in Rayleigh fading channel. The goal is achieved by embedding important information (image digest) which is extracted from the original image itself, and is used to introduce sufficient redundancy in the transmitted image. Half-toning technique is applied to obtain image digest from its low-resolution version. At the decoder side, data demodulation as well as watermark decoding are done using minimum mean square error combining (MMSEC) strategy. The extracted image digest is used to correct the damaged regions. The integration of SS watermarking with the existing SS modulation not only simplifies the design but also offers significant performance improvement for error concealment in fading channel. Authorized users having the knowledge of code patterns for SS watermarking can only perform the error concealment operation and the method is secured. Experimental results duly support the effectiveness of the proposed scheme.