Application of various spectroscopic techniques to characterize the archaeological pottery excavated from Manaveli,Puducherry, India

This paper is focused on a spectroscopic study of some ancient pottery shreds from an archaeological site Manaveli village, Puducherry, India. Analytical characterization using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and differential scanning colorimetric coupled with thermo gravimetric analysis were carried out on red and black ware and red ware recently excavated from the above site. The experimental results of FT-IR and XRD are similar and allowed us to identify the mineralogical composition of pottery samples. In addition, TGA was applied in order to study the dehydration of hydroscopic water and decomposition of carboxyl group in the powdered pottery samples during heating. Moreover, this paper proves that all the above spectroscopic techniques are very useful analytical tool for the examination of ancient pottery, which is also suitable for the identification of its firing temperature and firing atmosphere.     

Hydromagnetic flow of a Cu water nanofluid past a moving wedge with viscous dissipation

A numerical study is performed to investigate the flow and heat transfer at the surface of a permeable wedge immersed in a copper （Cu）-water-based nanofluid in the presence of magnetic field and viscous dissipation using a nanofluid model proposed by Tiwari and Das （Tiwari I K and Das M K 2007 Int. J. HeatMass Transfer 50 2002）. A similarity solution for the transformed governing equation is obtained, and those equations are solved by employing a numerical shooting technique with a fourth-order Runge-Kutta integration scheme. A comparison with previously published work is carried out and shows that they are in good agreement with each other. The effects of velocity ratio parameter ~, solid volume fraction tp, magnetic field M, viscous dissipation Ec, and suction parameter Fw on the fluid flow and heat transfer characteristics are discussed. The unique and dual solutions for self-similar equations of the flow and heat transfer are analyzed numerically. Moreover, the range of the velocity ratio parameter for which the solution exists increases in the presence of magnetic field and suction parameter.     

Slip effects on streamline topologies and their bifurcations for peristaltic flows of a viscous fluid

We discuss the effects of the surface slip on streamline patterns and their bifurcations for the peristaltic transport of a Newtonian fluid. The flow is in a two-dimensional symmetric channel or an axisymmetric tube. An exact expression for the stream function is obtained in the wave frame under the assumptions of long wavelength and low Reynolds number for both cases. For the discussion of the particle path in the wave frame, a system of nonlinear autonomous differential equations is established and the methods of dynamical systems are used to discuss the local bifurcations and their topological changes. Moreover, all types of bifurcations and their topological changes are discussed graphically. Finally, the global bifurcation diagram is used to summarize the bifurcations.     

Heterogeneous immunoassay for soy protein determination using nile blue-doped silica nanoparticles as labels and front-surface long-wavelength fluorimetry

A long-wavelength fluoroimmunoassay for the determination of soy protein is reported for the first time using a conjugate composed of anti-soy protein antibodies bound to nile blue-doped silica nanoparticles (NPs). These NPs have been synthesized by a reverse-micelle microemulsion method and functionalized by using 3-(aminopropyl)triethoxysilane (APS) and 3-(trihydroxysilyl)propyl methylphosphonate (THPMP) to avoid NP aggregation. The tracer has been obtained by linking the functionalized NPs with anti-soy protein antibodies previously oxidised with sodium periodate. The immunoassay has been developed in 96-well microplates using a heterogeneous competitive format with antibody capture. Soy proteins are immobilised onto the wells and bovine serum albumin is added to block the surface, thus minimising non-specific binding. After washing, the microplates can be stored ready to use. At the analysis time, soy protein standards or sample and tracer are added and incubated and, after the corresponding washing and drying steps, the fluorescence is measured onto the solid surface at λ_ex 620 and λ_em 680 nm. The method features a dynamic range of 0.1–10 mg L⁻¹ and a detection limit of 0.05 mg L⁻¹. The precision of the method has been assayed at 0.5 and 5 mg L⁻¹ protein concentrations, obtaining the values of relative standard deviation of 9.6% and 6.1%, respectively. This new immunoassay has been applied to the analysis of food containing soy protein and the results obtained have been compared to those provided by a commercial ELISA kit with no statistically differing results. Also, a recovery study has been performed, providing percentages in the range of 81.5–111.0%.     

Trace Analysis of Methyl Tert‐butyl Ether in Water Samples Using New Ultrasound‐assisted Dispersive Liquid‐liquid Microextraction and Gas Chromatography‐flame Ionization Detection

In this study, simple and efficient ultrasound‐assisted dispersive liquid‐liquid microextraction combined with gas chromatography (GC) was developed for the preconcentration and determination of methyl‐tert‐butyl ether (MTBE) in water samples. One hundred microliters of benzyl alcohol was injected slowly into 10 mL home‐designed centrifuge glass vial containing an aqueous sample with 30% (w/v) of NaCl that was located inside the ultrasonic water bath. The formed emulsion was centrifuged and 2 μL of separated benzyl alcohol was injected into a gas chromatographic system equipped with a flame ionization detector (GC‐FID) for analysis. Several factors influencing the extraction efficiency such as the nature and volume of organic solvent, extraction temperature, ionic strength and centrifugation times were investigated and optimized. Using optimum extraction conditions a detection limit of 0.05 μg L^‐1 and a good linearity (r² = 0.998) in a calibration range of 0.1‐500 μg L^‐1 were achieved. This proposed method was successfully applied to the analysis of MTBE in tap, well and a ground water sam ple contaminated by leaking gasoline from an underground storage tank (LUST) in a gasoline service station.     

Determination of Cadmium and Lead in Human Teeth Samples Using Dispersive Liquid‐liquid Microextraction and Graphite Furnace Atomic Absorption Spectrometry

A new method for the determination of cadmium and lead in human teeth was developed based on dispersive liquid‐liquid microextraction preconcentration and graphite furnace atomic absorption spectrometry determination. In the proposed approach, O,O‐diethyldithiophosphate (DDTP) was used as a chelating agent, and carbon tetrachloride and methanol were selected as extraction and dispersive solvents. Some factors influencing the extraction efficiency of cadmium and lead and their subsequent determination, including extraction and dispersive solvent type and volume, pH of sample solution, concentration of the chelating agent and extraction time, were studied and optimized. Under the optimum conditions, the enrichment factor of 116 and 68 for cadmium and lead were achieved. The detection limit for cadmium and lead was 5.6 and 45 ng L^?1, and the relative standard deviation (R.S.D) was 4.5% and 3.8% (n = 7, c = 1.0 ng mL^?1), respectively. Verification of the accuracy of the method was carried out by analysis of a standard reference material (NIST 1486, bone meal). The method was successfully applied to the determination of trace amount of cadmium and lead in human teeth samples with satisfactory results.     

Indirect Determination of Sulfadiazine by Cloud Point Extraction/Flow Injection‐Flame Atomic Absorption (CPE/FI‐FAAS) Spectrometry

An indirect simple and rapid cloud point extraction is proposed for separation and preconcentration of sulfadiazine and its determination by flow injection‐flame atomic absorption spectroscopy (FI‐FAAS). The sulfadiazine from 35 mL of solution was readily converted to silver sulfadiazine upon addition of silver nitrate (9.7 × 10^‐5 mol/L). Then, Triton X‐114 a non ionic surfactant was added and the solution was heated to 60 °C. At this stage, two separate phases was formed and silver sulfadiazine enters the surfactant rich phase of non‐ionic micelles of Triton X‐114. The surfactant‐rich phase (～50 μL) was then separated and diluted to 300 μL with acidic methanol. The concentration of silver in the surfactant‐rich phase which is proportional to the concentration of sulfadiazine in sample solution was determined by FI‐FAAS. The parameters affecting extraction and separation were optimized. Under the optimum conditions (i.e. pH 2‐10, silver concentration (9.7 × 10 ^‐5 mol/L), Triton X‐114 (0.075% v/v) and temperature 60 °C) a preconcentration factor of 117 and a relative standard deviation of 4.9% at 37 μg L^‐1 of sulfadiazine was obtained. The method was successfully applied to analysis of milk, urine and tablet samples and accuracy was determined by recovery experiments.     

Ultrasonic Scattering by a Spheroidal Suspension Including Dissipative Effects

This study treats the axisymmetric interaction of a plane compressional sound wave with a viscoelastic (viscous) prolate spheroidal particle (droplet) suspended in a boundless viscous fluid medium. The method of eigen‐function expansion along with the novel features of Havriliak‐Negami model for viscoelastic material behavior and the linearized equations of Navier‐Stokes for wave motion in a viscous non‐heat‐conducting compressible fluid are employed to develop a closed form series solution involving Spheroidal harmonics of complex argument. The complications arising due to the non‐orthogonality of angular Spheroidal functions corresponding to different wave numbers as well as problems associated with the appearance of additional angular dependent terms in the boundary conditions are all avoided by expansion of the angular Spheroidal functions in terms of Lengedre functions which are themselves expanded in terms of transcendental functions and subsequent integration, leading to a linear set of independent equations in terms of unknown scattering and transmission coefficients. The presented solution demonstrates that the acoustic characteristics of particulate suspensions are strongly influenced by spheroidicity of particle cross‐section. Limiting case involving an elastic (ideal) spheroidal particle (droplet) in an ideal fluid is considered and fair agreement with available solution is established.     

Ultrasonic Scattering by a Viscoelastic Fiber of Elliptic Cross‐Section Suspended in a Viscous Fluid Medium

This study treats the two‐dimensional interaction of a plane compressional sound wave with a viscoelastic fiber of elliptic cross‐section submerged in a boundless viscous nonheat‐conducting compressible fluid medium. The classical method of eigen‐function expansion along with the novel features of Havriliak‐Negami model for viscoelastic material behavior and the pertinent boundary conditions are used to develop a closed form series solution involving Mathieu and modified Mathieu functions of complex argument. The complications that arise because of the nonorthogonality of angular Mathieu functions corresponding to different wave numbers, as well as problems associated with the appearance of additional angular dependent terms in the boundary conditions, are all avoided by expansion of the angular Mathieu functions in terms of transcendental functions and subsequent integration, leading to a linear set of independent equations in terms of the unknown scattering coefficients. The presented solution demonstrates that acoustic characteristics of fiber suspensions are strongly influenced by cross‐sectional ellipticity of the fibers in addition to the dynamic viscoelastic properties of the fiber material. It also shows that the common rigid circular fiber approximations used to model fiber suspensions can not capture the important resonance and damping effects associated with the highly viscoelastic noncircular fibers. The proposed model is valid for a wide range of cross‐sectional geometries (aspect ratios) and incident wave frequencies where most numerical methods fail. Limiting case involving an elastic elliptic cylinder in an ideal fluid is considered and fair agreement with a recent solution is established.     

Fluorescence quenching method for determination of trace tungsten in environmental samples with dibromohydroxyphenylfluorone

A highly sensitive and selective fluorescence quenching method has been developed for the determination of trace tungsten in environmental samples using dibromohydroxyphenylfluorone (DBHPF) as an emission reagent. In the presence of 0.04?mol/L of sulphuric acid and acetyltrimethylammonium bromide, tungsten(VI) reacts with DBHPF to form a 1?:?3 red complex within 5.0?min. In order for the DBHPF–tungsten(VI) complex to form, the fluorescence intensity of the reagent solution was quenched linearly by adding 0.1 to 1.0?µg of tungsten(VI) in 25?mL of solution. This was measured at 528?nm with excitation at 495?nm. In this work, a standard addition method was investigated and used for sample analysis. The decrease in fluorescence intensity of the reagent solution (ΔF) was linear for 0?～?0.9?µg of tungsten(VI) in 25?mL of solution, and the detection limit (3?s) of the standard addition method was found to be 0.012?ng/mL of tungsten(VI). The effects of various metal and nonmetal ions were studied in detail. The experiments clearly showed that most foreign ions can be tolerated in considerable amounts; in particular, 50-fold Mo(VI), V(V), Zr(VI) and Ti(IV) do not interfere, and the selectivity of the proposed method is better than other previously described methods. Moreover, the method proposed here is very stable and simple, the fluorescence intensity of the solution can remain almost unchanged for 2.0?h at room temperature, and the method has been used successfully to determine tungsten in environmental samples.