Emission-based optical carbon dioxide sensing with HPTS in green chemistry reagents: room-temperature ionic liquids

We describe the characterization of a new optical CO₂ sensor based on the change in the fluorescence signal intensity of 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS) in green chemistry reagents—room-temperature ionic liquids (RTILs). As far as we are aware, this is the first time RTILs, 1-methyl-3-butylimidazolium tetrafluoroborate (RTIL-I) and 1-methyl-3-butylimidazolium bromide (RTIL-II), have been used as matrix materials with HPTS in an optical CO₂ sensor. It should be noted that the solubility of CO₂ in water-miscible ionic liquids is approximately 10 to 20 times that in conventional solvents, polymer matrices, or water. The response of the sensor to gaseous and dissolved CO₂ has been evaluated. The luminescence intensity of HPTS at 519 and 521 nm decreased with the increasing concentrations of CO₂ by 90 and 75% in RTIL-I and RTIL-II, respectively. The response times of the sensing reagents were in the range 1–2 min for switching from nitrogen to CO₂, and 7–10 min for switching from CO₂ to nitrogen. The signal changes were fully reversible and no significant hysteresis was observed during the measurements. The stability of HPTS in RTILs was excellent and when stored in the ambient air of the laboratory there was no significant drift in signal intensity after 7 months. Our stability tests are still in progress.      

Quantum Hamilton--Jacobi Approach to Two Dimensional Singular Oscillator

We obtain the solutions of two-dimensional singular oscillator which is known as the quantum Calogero-Sutherland model both in cartesian and parabolic coordinates within the framework of quantum Hamilton Jacobi formalism. Solvability conditions and eigenfunctions are obtained by using the singularity structures of quantum momentum functions under some conditions. New potentials are generated by using the first two states of singular oscillator for parabolic coordinates.     

Modeling of adsorption and ultrasonic desorption of cadmium(II) and zinc(II) on local bentonite

The adsorption and ultrasonic desorption of toxic heavy metal cations (i.e., Cd(II) and Zn(II)) on natural bentonite have been modeled with the aid of a factorial design approach. The ability of untreated bentonite to remove Cd(II) and Zn(II) from aqueous and acidic solutions at different pH values has been studied for different metal concentrations by varying the amount of adsorbent, temperature, stirring speed, and contact time. The same factors, except stirring speed and metal concentration, were applied in desorption study. Ultrasound power was used for desorption instead of stirring speed. A flame atomic absorption spectrometer was used to measure the cadmium and zinc concentration before and after both experimental study. The highest adsorption for Zn and Cd was 99.85 and 96.84%, respectively, and the highest desorption for Zn and Cd obtained was 66.57 and 51.37%, respectively. It is believed that the models obtained for adsorption and desorption may provide a background for detailed mechanism searches and pilot and industrial scale applications.     

Synthesis and GIAO NMR calculations for some new 4,5-dihydro-1H-1,2,4-triazol-5-one derivatives: comparison of theoretical and experimental 1H and 13C chemical shifts

Four novel 3-alkyl(aryl)-4-(4-methoxycarbonylbenzylidenamino)-4,5-dihydro-1H-1,2,4-triazol-5-ones (2) were synthesized by the reactions of 3-alkyl(aryl)-4-amino-4,5-dihydro-1H-1,2,4-triazol-5-ones (1) with methyl 4-formylbenzoate and characterized by elemental analyses and IR, 1H NMR, 13C NMR and UV spectral data. In addition, isotropic 1H and 13C nuclear magnetic shielding constants of 2 were obtained by the gauge-including-atomic-orbital (GIAO) method at the B3LYP density functional level. The geometry of each compound was optimized using the 6-311G basis set.     

Cytotoxicity of Silica Nanoparticles with Transcaucasian Nose-Horned Viper, <Emphasis Type="Italic">Vipera ammodytes transcaucasiana</Emphasis>, Venom on U87MG and SHSY5Y Neuronal Cancer Cells

Highly bioactive compounds of the snake venom make them particular sources for anticancer agent development. They contain very rich peptide-protein structures. Therefore, they are very susceptible to environmental conditions such as temperature, pH, and light. In this study, Vipera ammodytes transcaucasiana venom was encapsulated in PAMAM-G4 dendrimer by sol-gel method in order to prevent degradation of venom contents from the environmental conditions. For this purpose, nanoparticles were prepared by sol-gel methodology and SEM analyses were performed. U87MG and SHSY5Y neuronal cancer cell lines were treated with different concentrations of venom-containing nanoparticles and cytotoxicity was determined by MTT assay. IC₅₀ values of nanoparticles with snake venom were calculated as 37.24 and 44.64 μg/ml for U87MG and SHSY5Y cells, respectively. The IC₅₀ values of nanoparticles with snake venom were calculated as 10.07 and 7.9 μg/ml for U87MG and SHSY5Y cells, respectively. As a result, nanoparticles with V. a. transcaucasiana venom showed remarkably high cytotoxicity. Encapsulation efficiency of nanoparticles with 1 mg/ml snake venom was determined as %67 via BCA? protein analysis. In conclusion, this method is found to be convenient and useful for encapsulating snake venom as well as being suitable for drug delivery systems.     

Determination of Trace Amounts of Copper in Tap Water Samples with a Calix[4]arene Modified Carbon Paste Electrode by Differential Pulse Anodic Stripping Voltammetry

A calix[4]arene modified carbon paste electrode was used for trace determination of copper. The study of the preconcentration of copper as well as the other heavy metal ions at the modified electrode, with subsequent measurement by differential pulse anodic stripping voltammetry (DPASV), indicates the efficient open‐circuit accumulation of the analytes onto the electrode. Many parameters such as the composition of the paste, pH, preconcentration time and stirring rate influence the response of the measurement. The procedure was optimized for copper determination. For a 10‐minute preconcentration time at pH 6.5–7.5, the detection limit (LOD) was 1.1 μg L^?1. The optimized method was successfully applied to the determination of copper in tap water sample by means of standard addition procedure. The copper content of the sample was comparable with the result obtained with AAS method.     

Electrochemical Detection of Epinephrine Based on a Screen-printed Electrode Modified with NiO−ERGO Nanocomposite Film

This study presents a new electrochemical sensor (NiO−ERGO/SPE) for sensitive and selective detection of epinephrine (EPI) on the screen-printed electrode (SPE) which is modified with a nanocomposite film consisting of electrochemically reduced graphene oxide and NiO nanoparticles. After surface functionalization, structural and electrochemical characterization of NiO−ERGO film, DPV signals of NiO−ERGO/SPE towards the oxidation of EPI exhibited a linear correlation in the concentration range of 0.025 μM to 175 μM with a detection limit of 0.015 μM, which reveals NiO−ERGO film is manifested a good electrocatalytic activity for EPI detection compared with the previous reports. The selectivity of NiO−ERGO film was also tested on a very wide scale of possible interferents (ascorbic acid, uric acid, dopamine, lactic acid, phenylalanine, tyrosine, tryptophan, Li⁺, Na⁺, K⁺, Ca²⁺, and Zn²⁺). Moreover, to evaluate the applicability of the proposed sensor for real sample analysis, NiO−ERGO/SPE was successfully utilized for the determination of EPI in pharmaceutical samples.     

Synthesis of boron carbon nitride layers for the adsorption of hazardous basic dye from aqueous solutions

Research on Chemical Intermediates - Many researchers have investigated the usage of carbonaceous materials as adsorbents. In this study, boron carbon nitride (BCN) was synthesized using boric acid...     

Fiber optic pH sensing with long wavelength excitable Schiff bases in the pH range of 7.0-12.0

Most of the fluorescent pH probes work near neutral or acidic regions of the pH scale. In this work, two different fluorescent Schiff bases, chloro phenyl imino propenyl aniline (CPIPA) and nitro phenyl imino propenyl aniline (NPIPA), have been investigated for pH sensing in the alkaline region. Absorption and emission based spectral data, quantum yield, fluorescence lifetime, photostability and acidity constant (pK(a)) of the Schiff bases were determined in conventional solvents and in PVC. The long wavelength excitable immobilized Schiff bases CPIPA (lambda(ex)=556 nm) and NPIPA (lambda(ex)=570 nm) exhibited absorption and emission based optical response to proton in the pH range of 8.0-12.0 and 7.0-12.0, respectively. Response of the CPIPA was fully reversible within the dynamic working range. The response times were between 3-13 min. A relative signal change of 95% and 96% have been achieved for sensor dyes of CPIPA and NPIPA, respectively. The CPIPA displayed better fluorescence quantum yield (varphi(F)=3.7 x 10(-1)) and higher matrix compatibility compared to NPIPA (varphi(F)=1.6 x 10(-1)) in immobilized PVC. The CPIPA and NPIPA exhibited a slight cross sensitivity to the ions of Hg(+) and Fe(3+), respectively.