Gecko-inspired carbon nanotube-based self-cleaning adhesives

The design of reversible adhesives requires both stickiness and the ability to remain clean from dust and other contaminants. Inspired by gecko feet, we demonstrate the self-cleaning ability of carbon nanotube-based flexible gecko tapes.     

Optical studies of electrochemically synthesized CdS nanowires

In this paper, electrochemical fabrication and characterization of CdS nanowires having diameter 100 and 200 nm is reported. Nano-channels in anodic alumina membrane were utilized as template. Morphological study of nanowires was made using Scanning electron microscopy (SEM). UV–visible absorption and laser induced time resolved photoluminescence (PL) spectroscopy were used for optical characterization. UV–visible absorption depicts that, there is slight increase in band gap of nanowires with decrease in diameter of nanowires. PL measurements indicate emission band peak of 435 and 420 nm in case of 200 and 100 nm wires respectively. These studies are very important regarding the synthesis and optoelectronic applications of CdS nanowires.     

Moduli of ordered polymer composites prepared by colloidal crystallization of nano- and micro-SiO2 spheres in crosslinked methacrylate resins

The extraordinary mechanical performance of nanomaterials found in nature has been attributed to the ordered arrangement of the components. Here, nano- and mico-composites containing either ordered or disordered arrangement of the spheres were compared. The nano- and micro-composites were formed using 19–45 vol% silica in crosslinked resins of triethylene glycol dimethacrylate (TEGDMA) and methyl methacrylate (MMA), in weight ratios TEGDMA/MMA of 100/0, 80/20 or 60/40. The silica nanoparticles, with sizes of 250, 500 and 1000 nm diameter, were silanated with methacryloxypropyl trimethoxysilane (MPS), MPS-SiO₂, to promote bonding to the resin. The ordered nano- or micro-composites were obtained by colloidal crystallization and formed face-centered cubic arrays. Disorder was achieved by mixing two particle sizes or by addition of a coinitiator, dimethylaminoethyl methacrylate (DMAEMA). Ordered nano- or micro-composites had moduli 30% higher than similar composites in which disordered was introduced by mixing two size spheres, at the same loading, for all resin compositions. The greatest improvement occurred at the highest packing density of the spheres, 45 vol%. When disorder was introduced by addition of DMAEMA, the mechanical properties of the ordered and disordered composites were similar, since local but not long-range regions of order was also achieved in the latter case.     

Variability of Nonionellina labradorica Dawson in Surface Sediments from Kongsfjorden,West Spitsbergen

Kongsfjorden is a fjord in Spitsbergen (Svalbard archipelago) that lies adjacent to both Arctic and Atlantic water masses and is therefore a suitable site to understand the effects of climate change on ecosystems. To decipher the effect of the lateral advection of transformed Atlantic water (TAW) within the fjord, spatial variations of foraminiferal tests, their test size variations and stable isotopic composition (δ13C and δ18O) in the surface sediments were studied. Total organic carbon and textural analyses were also carried out. The dominant benthic foraminifera included Nonionellina labradorica, Elphidium excavatum, Cassidulina reniforme, Quinqueloculina stalkeri and Islandiella islandica. Nonionellina labradorica was the predominant species in the outer fjord, whereas Elphidium excavatum and Cassidulina reniforme were dominant in the inner fjord. Total organic carbon and the test size of Nonionellina labradorica within the fjord were highly correlated (r = 0.97) and both showed a decreasing trend towards the inner fjord. Based on the distribution and abundance of Nonionellina labradorica as well as temperature profiles, we suggest that there was little or no major change in the lateral advection of TAW within the fjord in the immediate past.     

The C-Terminal Region of G72 Increases d-Amino Acid Oxidase Activity

The schizophrenia-related protein G72 plays a unique role in the regulation of d-amino acid oxidase (DAO) in great apes. Several psychiatric diseases, including schizophrenia and bipolar disorder, are linked to overexpression of DAO and G72. Whether G72 plays a positive or negative regulatory role in DAO activity, however, has been controversial. Exploring the molecular basis of the relationship between G72 and DAO is thus important to understand how G72 regulates DAO activity. We performed yeast two-hybrid experiments and determined enzymatic activity to identify potential sites in G72 involved in binding DAO. Our results demonstrate that residues 123–153 and 138–153 in the long isoform of G72 bind to DAO and enhance its activity by 22% and 32%, respectively. A docking exercise indicated that these G72 peptides can interact with loops in DAO that abut the entrance of the tunnel that substrate and cofactor must traverse to reach the active site. We propose that a unique gating mechanism underlies the ability of G72 to increase the activity of DAO. Because upregulation of DAO activity decreases d-serine levels, which may lead to psychiatric abnormalities, our results suggest a molecular mechanism involving interaction between DAO and the C-terminal region of G72 that can regulate N-methyl-d-aspartate receptor-mediated neurotransmission.     

A sensing behavior synergistic liquid–liquid extraction and spectrophotometric determination of nickel(II) by using 1-(2ˊ,4ˊ-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol: Analysis of foundry and electroless nickel plating waste water

We report the sensing behavior of liquid–liquid extraction of nickel(II), which has been selectively determined from contaminated water samples by a simple UV-visible spectrophotometer. The method is based on synergistic extraction of nickel(II) by 1-(2ˊ,4ˊ-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol [2ˊ,4ˊ-dinitro APTPT] with pyridine. Nickel(II) reacts with 2ˊ,4ˊ-dinitro APTPT and forms a green-colored complex at pH 9.2. In addition, the Ni(II) ions were detected with the naked eye with the ligand. The absorbance of the coloured complex was measured at 660 nm and the colored complex is stable for more than 48 h even in the presence of other competing ions. The system obeyed Beer’s law in the concentration range of 5–50 μg mL^?1 of nickel(II) and the optimum range evaluated by Ringbom’s plot method is 10–40 μg mL^?1 with an excellent linearity and a correlation coefficient of 0.999. The molar absorptivity and Sandell’s sensitivity of the extractive species were found to be 1.64 × 10³ dm³ mol^?1 cm^?1 and 0.0585 μg cm^?2 in the presence of pyridine, and 7.4 × 10² dm³ mol^?1 cm^?1 and 0.78 μg cm^?2 in the absence of pyridine, respectively. The composition of nickel(II)-2ˊ,4ˊ-dinitro APTPT-pyridine was established by the slope ratio method, the mole ratio method and Job’s method of continuous variation. It was found that the metal:ligand:synergent (M:L:Sy) ratio is 1:2:2. To assess the precision and accuracy of the developed method, determinations were carried out at n = 5. The relative standard deviation of all measurements does not exceed 0.16%. Excellent selectivity was found towards the Ni(II) ion due to a specific complex formation between the Ni(II) ion and the organic ligand. In the extraction of Ni(II), several affecting factors, including the solution pH, ligand concentration, equilibrium time, initial Ni(II) ion concentration and foreign ions, were investigated and the applicability of the method was checked by the analysis of synthetic mixtures and alloys. The developed method was successfully used for the determination of nickel(II) from waste water effluents from the foundry region and the nickel plating industry (Kolhapur city). The results obtained by the developed method were also confirmed by AAS. We claimed from this study that Ni(II) could be successfully determined by the spectrophotometric method developed in the current work. The present work is obviously much simpler than the conventional method comprising multistep processes.     

Positron annihilation and other experimental studies on polycarbonate/MPDMAPP nanocomposite

The composite films of polycarbonate (PC) filled with 1‐(4‐methylphenyl)‐3‐(4‐N,N‐dimethylaminophenyl)‐2‐propen‐1‐one (MPDMAPP) were prepared by solution casting. The FT‐IR results of the prepared films confirmed the hydrophobic and dipole‐dipole interaction between PC and MPDMAPP, which is a major driving force for the formation of charge transfer complex (CTC). UV–Vis absorption spectra showed three peaks and the optical band gap E_g for pure PC is 4.31 eV which decreased to 4.1 eV after 15 wt % doping. The fluorescence spectral results show a strong emission and quenching in the wavelength region 510 to 550 nm for 408 nm excitation due to increase in amorphousness, which is observed in X‐ray diffraction (XRD) results. The decrease in ortho‐positronium (o‐Ps) lifetime τ₃ and corresponding intensity I₃ from positron annihilation lifetime spectroscopy (PALS) and the S‐parameter from Doppler broadening measurements show both inhibition and quenching of Ps formation in the PC/MPDMAPP composite due to the presence of dimethylamino N(CH₃)₂ group. The mechanical properties such as Young's modulus, tensile strength, and stiffness increase with doping concentration and confirmed that the composite films are mechanically stable. The growth of nanostructures of MPDMAPP within PC films is studied with SEM and TEM images and confirms the uniform dispersion and interaction between the functional groups of PC and MPDMAPP. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42053.     

Microwave‐assisted chemical synthesis of conducting polyindole: Study of electrical property using Schottky junction

A facile and rapid enhanced microwave‐assisted route for one‐pot synthesis has been developed to polymerize indole moiety using two different oxidizing agents for 60 s exposure at 30 ± 1°C. As‐synthesized conducting polyindoles, obtained by varying the synthesis process and oxidant, have been well characterized by various techniques. UV–vis, FT‐IR, and NMR have been used for their structural analysis while gel permeation chromatography, thermogravimetric analysis, and conductivity measurement to evaluate their enhanced properties and to perform a comparative study. Morphological texture of polyindole synthesized via different techniques has studied by scanning electron microscopy analysis. PIn synthesized by KIO₃ (microwave synthesis) exhibit interconnecting texture which may be due to high level of supersaturation of solution under the influence of microwave irradiation. Thereafter, electrical property of spin‐coated thin film of polyindole is examined using four probe method and Al metal/semiconducting material Schottky junction. Microwave‐assisted polymer shows better performance for Schottky devices due to difference in charge transport, morphological texture, and distribution of M_n. The PIn synthesized via microwave irradiation with better charge transport across the metal/polymer interfaces shows the potential of this technique for synthesis of such polymers with enhanced electronic properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42192.     

Node connectivity and arc connectivity of a fuzzy graph

The fuzzy graph approach is more powerful in cluster analysis than the usual graph - theoretic approach due to its ability to handle the strengths of arcs effectively. The concept of node-strength sequence is introduced and is studied in a complete fuzzy graph. Two new connectivity parameters in fuzzy graphs namely, fuzzy node connectivity (κ) and fuzzy arc connectivity (κ^′) are introduced and obtained the fuzzy analogue of Whitney’s theorem. Fuzzy node cut, fuzzy arc cut and fuzzy bond are defined. Fuzzy bond is a special type of a fuzzy bridge. It is proved that at least one of the end nodes of a fuzzy bond is a fuzzy cutnode. It is shown that κ=κ^′ for a fuzzy tree and it is the minimum of the strengths of its strong arcs. The relationships of the new parameters with already existing vertex and edge connectivity parameters are studied and is shown that the value of all these parameters are equal in a compete fuzzy graph. Also a new clustering technique based on fuzzy arc connectivity is introduced.