Experimental investigation of nano-TiO2/turbine meter oil nanofluid

Journal of Thermal Analysis and Calorimetry - Today, nanoparticles are used as additives because of their unique properties. The aim of the present research is to investigate the effect of the...     

In-Situ Full-Field Strain Measurement at the Sub-grain Scale Using the Scanning Electron Microscope Grid Method

Experimental Techniques - Full-field measurement techniques are invaluable tools for investigating material behavior across length-scales. In the current work, a full-field measurement technique,...     

Sustainable potable water production from conventional solar still during the winter season at Algerian dry areas: energy and exergy analysis

Journal of Thermal Analysis and Calorimetry - The Algeria Sahara suffers from the scarcity of drinking water. Solar distillation is one of the simplest and generally inexpensive techniques to solve...     

Crystal Structures of a New Polymorph of N-tert-butyl-2-thioimidazole,and Its 1,4-Diiodotetrafluorobenzene,Tetraiodoethylene, and Iodine Cocrystals

Journal of Chemical Crystallography - A new polymorph of N-tert-butyl-2-thioimidazole (1), along with its cocrystals with 1,4-diiodotetrafluorobenzene (2), tetraiodoethylene (3), and molecular...     

Determination of alprazolam in serum by adsorptive stripping voltammetry

The surface-active properties of alprazolam at a hanging mercury drop electrode allow their sensitive determination by differential-pulse adsorptive stripping voltammetry. Detection limits are 0.07 ng/ml for accumulation in water (accumulation time 240 s) and 0.3 ng/ml for accumulation in serum extract (accumulation time 30 s). Coefficients of variation at 5 ng/ml (10 determinations) were typically <2%.     

A chance-constrained approach to stochastic line balancing problem

In this paper, chance-constrained 0–1 integer programming models for the stochastic traditional and U-type line balancing (ULB) problem are developed. These models are solved for several test problems that are well known in the literature and the computational results are given. In addition, a goal programming approach is presented in order to increase the system reliability, which is arising from the stochastic case.     

Graphene oxides/multi-walled carbon nanotubes hybrid-modified carbon electrodes for fast and sensitive voltammetric determination of the anticancer drug 5-fluorouracil in spiked human plasma samples

The electrochemical oxidation of anticancer drug 5-fluorouracil (5-FU) at graphene oxides (GOs)/carbon nanotubes (CNTs) nanohybrid-modified screen-printed carbon and glassy carbon electrodes was studied by voltammetric techniques. The modified electrodes showed better performance toward the electro-oxidation and determination of 5-FU compared to CNTs-modified or GOs-modified electrodes. The oxidation peak current obtained at about + 1.156 V (vs. Ag/AgCl) from square wave voltammetry was linearly dependent on the 5-FU concentration in the ranges of 0.05–5 and 5–1200 µM in phosphate buffer solution of pH 7.0. The developed method was applied successfully to the electrochemical sensing of 5-FU in human plasma samples at micro-molar concentration levels with satisfactory results. It is hopeful that the developed method in the future can be used for the simple and fast determination of 5-FU in clinical test and pharmacokinetics.     

Application of 1,4-Diaminoanthraquinone as a New Sensing Material for Fabrication of a Iron(III)-Selective Modified Carbon Paste Electrode

In the present work, a novel sensitive electrochemical potentiometric sensor for sensing Fe³⁺ ions based on 1,4-diaminoanthraquinone (DAQ) as a hydrophobic selector element was prepared to implement as an ion selective carbon paste electrode in the aqueous solutions. The adequate amounts of ionophore (5%), paraffin oil (25%) as a binder, Nanosilica (NS: 0.5%) multi-wall carbon nanotubes (MWCNTs: 1%) as a modifier, and graphite powder (68.5%) as an inert matrix was occupied to form the paste. This new FeCP sensor demonstrated a Nernstian slope of 19.7 ± 0.7 mV per decade over widish linear range between 1.0 × 10^–8 to 1.0 × 10^–2 mol L^–1 at working pH range of 1.9–5.0 in the optimized conditions. The average elapsed time to response of electrode was about ~6 s for concentrations from lower (1.0 × 10^?8 mol L^–1) to higher (1.0 × 10^?2 mol L^–1) of Fe³⁺ ion solution. The selectivity of electrode toward Fe³⁺ ions in comparison with other cations was studied by matched potential method. The making FeCP sensor has been put to use successfully as an indicator electrode in analytical applications such as the potentiometric titration and determination of iron(III) ion in blend of different ions.     

A metal organic framework prepared from benzene-1,3,5-tricarboxylic acid and copper(II), and functionalized with various polysulfides as a sorbent for selective sorption of trace amounts of heavy metal ions

Novel composites were obtained via direct assembly of polysulfides (S_x^2?, X?=?3, 4, 6) on the surface of a metal organic framework (MOF; type benzene-1,3,5-tricarboxylic/Cu(II). They are referred to as S_x-MOFs and were used for highly selective and efficient extraction of ultra-trace amounts of heavy metal ions from aqueous solutions. The structure of the S_x-MOFs was characterized by Raman spectroscopy, FT-IR, X-ray diffraction, and scanning electron microscopy. The Raman spectra of S_x-MOF is similar to the bare MOF and shows the MOFs structure to be well retained after S_x functionalization. The selective interaction of S_x with soft metal ions and the high surface area of MOFs resulted in excellent affinity and selectivity for ions such as Hg(II). The S_x-MOFs of type S₄-MOF had the highest distribution coefficient K_d value (~10⁷) and best extraction recovery (~100%) for Hg(II). The S₄-MOF also has high selectivity in the following order: Hg(II) >?>?Pb(II)?>?Zn(II)?>?Ni(II)?>?Co(II). The binding process of the metals occurs via M–S bonding. The ions were quantified by inductively coupled plasma optical emission spectrometry (ICP-OES). The detection limit for Hg(II) is 0.13 μg L^?1. The S₄-MOF was applied to the extraction of trace metal ions from natural and contaminated waters and data were compared with other sorbets. The results revealed that S₄-MOF is an excellent adsorbent for sorption of heavy metal ions even in the presence of the relatively high concentration of other ions.

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Graphical abstract A composite was synthesized via direct assembly of polysulfides (S_x^2?, X?=?3, 4, 6) on surface of the metal organic framework (S_x-MOF) and was used for selective and efficient extraction of ultra-trace amounts of heavy metal ions from aqueous solutions.

     

A streptavidin linker layer that functions after drying

The ability of streptavidin (SA) to simultaneously bind four biotins is often used in linker layers, where a biotinylated molecule is linked to a biotin-functionalized surface via SA. For biosensor and array applications, it is desirable that the SA linker layer be stable to drying and rehydration. In this study it was observed that a significant decrease in binding capacity of a SA layer occurred when that layer was dried. For this study a SA linker layer was constructed by binding SA to a biotin-containing alkylthiolate monolayer (BAT/OEG) self-assembled onto gold. Its stability after drying was investigated using surface plasmon resonance (SPR). Approximately a quarter of the SA layer was removed from the BAT/OEG surface upon drying and rehydration, suggesting disruption of SA-biotin binding when dry. This resulted in the dried SA layer losing approximately 40% of its biotinylated ferritin (BF) binding capacity. Coating the layer with trehalose before drying was found to inhibit the loss of SA from the BAT/OEG surface. SPR showed that the trehalose-protected SA linker layer retained approximately 91% of its original BF binding capacity after drying and rehydration. Atomic force microscopy, which was used to image individual surface-bound SA and BF molecules, qualitatively confirmed these observations.