A Generic Technique for Coating Doped Sol-Gel Films onto the Inside of Tubes for Use as Colorimetric Sensors

Sol-gel thin films have been doped with bromophenol blue and eriochrome cyanine RC for measuring pH and Cu⁺⁺ in solution respectively. The films were coated inside glass tubes by a novel method. Films doped with bromophenol blue responded to pH changes from pH 3 to 8. They were stable to variations in temperature from 20°C to 40°C. The sensing films have been subjected to leaching studies in different pH buffer solutions. Copper ions in solution have been measured to a minimum concentration of 0.6 ppm by eriochrome immobilised in sol-gel films. The interferences of other metal ions were also studied. Doped sol-gel films coated onto the inside of test tubes offer a simple, none-invasive, reusable and fast optical chemical sensing technique for the measurement of colour by spectroscopy or colorimetry.     

Comparison of thermal degradation products from real municipal waste plastic and model mixed plastics

The thermal degradation of real municipal waste plastic (MWP) obtained from Sapporo, Japan and model mixed plastics was carried out at 430 °C in atmospheric pressure by batch operation. The chlorinated hydrocarbons found in PE/PP/PS/PVC [poly(ethylene)/poly(propylene)/poly(styrene)/poly(vinyl chloride)] degradation liquid products were also observed in PE/PP/PS/PVC/PET (poly(ethylene terephalate)) and MWP degradation liquid products. The presence of PET in MWP produced the additional chlorinated hydrocarbons, which are similar to the chlorinated hydrocarbons observed during the PE/PP/PS/PVC/PET degradation liquid products. In addition, the presence of PET facilitated the formation of more organic chlorine content in liquid products and drastic decrease in the formation of inorganic chlorine content.     

Chemical synthesis of zinc oxide nanorods for enhanced hydrogen gas sensing

Zinc oxide(ZnO) nanorods are prepared using equimolar solution of zinc nitrate((Zn(NO3)2) and hexamethylenetetramine(C6H12N4) by the hydrothermal technique at 80 C for 12 h. Epitaxial growth is explored by X-ray diffraction(XRD) patterns, revealing that the ZnO nanorods have a hexagonal(wurtzite) structure. Absorption spectra of ZnO are measured by UV–visible spectrometer. The surface morphology is investigated by field emission scanning electron microscopy(FESEM). The synthesized ZnO nanorods are used for detecting the 150 C hydrogen gas with a concentration over 1000 ppm. The obtained results show a reversible response. The influence of operating temperature on hydrogen gas detecting characteristic of ZnO nanorods is also investigated.     

Investigation of the optimal annealing temperature for the enhanced thermoelectric properties of MOCVD-grown ZnO films

In this study, we demonstrate the optimization of the annealing temperature for enhanced thermoelectric properties of ZnO. Thin films of ZnO are grown on a sapphire substrate using the metal organic chemical Vapor Deposition (MOCVD) technique. The grown films are annealed in an oxygen environment at 600–1000°C, with a step of 100°C for one hour. Seebeck measurements at room temperature revealed that the Seebeck coefficient of the sample that was not annealed was 152 μV/K, having a carrier concentration of N _D ~ 1.46 × 10¹⁸ cm^–3. The Seebeck coefficient of the annealed films increased from 212 to 415 μV/K up to 900°C and then decreased at 1000°C. The power factor is calculated and found to have an increasing trend with the annealing temperature. This observation is explained by the theory of Johnson and Lark–Horovitz that thermoelectric properties are enhanced by improving the structure of ZnO thin films. The Hall measurements and PL data strongly justify the proposed argument.     

First Principles Investigation of Fluorine Based Strontium Series of Perovskites

Density functional theory is used to explore structural, elastic, and mechanical properties of SrLiF₃, SrNaF₃, SrKF₃ and SrRbF₃ fluoroperovskite compounds by means of an ab-initio Full Potential-Linearized Augmented Plane Wave (FP-LAPW) method. Several lattice parameters are employed to obtain accurate equilibrium volume (V_o). The resultant quantities include ground state energy, elastic constants, shear modulus, bulk modulus, young's modulus, cauchy's pressure, poisson's ratio, shear constant, ratio of elastic anisotropy factor, kleinman's parameter, melting temperature, and lame's coefficient. The calculated structural parameters via DFT as well as analytical methods are found to be consistent with experimental findings. Chemical bonding is used to investigate corresponding chemical trends which authenticate combination of covalent-ionic behavior. Furthermore electron density plots as well as elastic and mechanical properties are reported for the first time which reveals that fluorine based strontium series of perovskites are mechanically stable and posses weak resistance towards shear deformation as compared to resistance towards unidirectional compression while brittleness and ionic behavior is dominated in them which decreases from SrLiF₃ to SrRbF₃. Calculated cauchy's pressure, poisson's ratio and B/G ratio also proves ionic nature in these compounds. The present methodology represents an effective and influential approach to calculate the whole set of elastic and mechanical parameters which would support to understand various physical phenomena and empower device engineers for implementing these materials in numerous applications.     

Numerical approach for stagnation point flow of Sutterby fluid impinging to Cattaneo–Christov heat flux model

This paper presents a comprehensive modelling and simulation study on the optimum parameters that control the distortion and noise of semiconductor lasers (SLs) subject to multichannel modulation for use in analog cable television (CATV) fibre links. The study is based on numerical integration of the rate equation model of the semiconductor laser. The parameters comprise the modulation index per channel (m / ch), number of loaded channels (N) and fibre length \((L_{F})\). The signal distortions include the composite second-order (CSO) and composite triple beat (CTB) distortions. The noise is assessed in terms of the relative intensity noise (RIN) and carrier-to-noise ratio (CNR). In order to achieve acceptable CNR values for SL, m / ch should be less than 7.5 and 2% when loading 12 and 80 channels, respectively. For the CATV fibre link with \(L_{F} = 10 \hbox { km}\), the increase in the number of channels from 12 to 80 corresponds to lowering the optimum value of m / ch from 7 to 1%. The increase of \(L_{F}\) to 50 km limits the optimum value of m / ch between 1.4 and 1%, which corresponds to loading between 12 and 17 channels only.     

Room Temperature Ferromagnetism in Ga1-xHoxN (x=0.0 and 0.05) Diluted Magnetic Semiconductor Thin Films

Holmium doped GaN diluted magnetic semiconductor thin films have been prepared by thermal evaporation technique and subsequent ammonia annealing. X-ray diffraction mea-surements reveal all peaks belong to the purely hexagonal wurtzite structure. Surface mor-phology and composition analysis were carried out by scanning electron microscopy and energy dispersive spectroscopy respectively. The room temperature ferromagnetic proper-ties of Ga_1-xHo_xN(x=0.0, 0.05) films were analyzed using vibrating sample magnetometer at room temperature. Magnetic measurements showed that the undoped films (i.e. GaN) exhibited diamagnetic behavior, while the Ho-doped (Ga_0.95Ho_0.05N) film exhibited a ferro-magnetic behavior.     

Kinetics and mechanism of the cleavage of n-methoxyphthalimide (NMPT) in the presence of buffers of tris (hydroxymethyl)amino methane (tris) and 1,4-diazabicyclo[2.2.2]octane (DABCO)

The magnitude of hydroxide ion-catalyzed second-order rate constant (k_OH) for hydrolysis of N-methoxyphthalimide (NMPT) supports the conclusion that the rate law for pH-independent hydrolysis of N-hydroxyphthalimide (NHPTH) is rate = k_OH[HO^-][SH] where SH represents nonionized NHPTH. The second-order rate constants for the reactions of NMPT with DABCO and Tris are (59.7 ± 6.9) x 10^-3 and (11.9 ± 2.3) x 10^-4 M^-1 s^-1, respectively. This revised version was published online in June 2006 with corrections to the Cover Date.     

Structure determination of ramosine, a guaianolide, by NMR spectroscopy

Ramosine, a new sesquiterpene lactone, was isolated from the chloroform fraction of Amberboa ramosa and the structure was assigned as 4beta-(hydroxymethyl)-3beta,4alpha-dihydroxy-8alpha-[(S)-3-hydroxy-2-ethylenepropionyloxy]-1alphaH, 5alphaH,6betaH,7alphaH,11betaH,11alpha-methylguaia-10(14)-en-6, 12-olide by extensive NMR studies.     

Spinneret geometry modulates the mechanical properties of man-made cellulose fibers

Cellulose - The production of cellulose-based textile fibers with high toughness is vital for extending the longevity and thus developing a sustainable textile industry by reducing the global...