Synthesis and characterizations of poly(ether)/poly(phenol)s including azomethine coupled benzothiazole side chains: the effect of reaction conditions on the structure,optical, electrochemical,electrical and thermal properties

A new Schiff base, 4-((6-ethoxybenzothiazole-2-ylimino)methyl)benzene-1,2-diol (3,4-HBAEBT) was synthesized by the condensation reaction of 3,4-dihydroxybenzaldehyde (3,4-HBA) and 2-amino-6-ethoxybenzothiazole. The Schiff base, then, was converted to its polymer derivatives by oxidative polycondensation reaction in both organic (P-1) and aqueous alkaline medium (P-2). Spectral observations indicated different structural properties for each polymerization condition. Organic and aqueous alkaline medium produced poly(ether) and poly(phenol) structures, respectively. The obtained polymers were separately studied with respect to optical, electrochemical, electrical and thermal properties. With exception of thermal degradation behaviors, the other investigated properties as well as morphological characteristics of both polymers were considerably different. In the fluorescence measurements a solvatochromic effect was recorded and the emission colors of the polymers could be changed as turquoise-green by solvent change.     

Uncertainty Analysis of Four-Terminal-Pair Capacitance Characterization up 30 MHz

The Impedance Group Laboratories of National Metrology Institute of Turkey previously developed a new method for the characterization of Agilent 16380A-type four-terminal-pair air dielectric capacitance standards ranged from 1 to 1,000 pF up to 30 MHz. This method is based on obtaining all resonance frequencies of standard capacitors using a vector network analyzer in order to calculate inductive residual parameters of the standards. As a continuation of the study, this paper gives a detailed uncertainty analysis for the method.     

Prioritization methodology of dangerous substances for water quality monitoring with scarce data

Monitoring and control of dangerous substances discharged into receiving waters have attracted more attention lately. Since it is not possible to analyze every single substance, a prioritization methodology is needed for the selection of those to be monitored. Existing well-developed models require significant amount of data for reliable outcomes. This paper presents a methodology to prioritize the dangerous substances having adverse effects on freshwaters in Turkey, where data are scarce. Such a methodology will also serve as a solid model for other countries with limited background data. The adopted methodology enabled the elimination of chemicals to generate a candidate list composed of 608 substances among more than 5000 substances. Further screening and prioritization were conducted using different assessment methods (i.e., Total Hazard Value, Total Impact Value, Combined Monitoring-based, and Modelling-based Priority Setting) to obtain a proposed Final Candidate Specific Pollutants List of 150 dangerous substances. The proposed Candidate National Pollutant List of Turkey was established by combining 45 priority pollutants of the European Union with a list of candidate specific pollutants. According to the outcomes of this study, monitoring and controlling of 195 dangerous substances in freshwaters are recommended. Further detailed studies should be conducted in order to observe the actual levels of these dangerous substances in freshwaters followed by a review of the monitoring list accordingly. Moreover, further revisions might be required in the proposed list due to some possible versatile conditions in terms of sampling points (i.e., change in the location of industries).     

Using Circular Conduits in Ozone Injection

Dissolved oxygen is the amount of oxygen dissolved in water corresponding to an important water quality parameter in rivers, streams, and lakes. Hydraulic structures can increase dissolved oxygen levels by creating turbulent conditions where small air bubbles are carried into the bulk of the flow. A gated conduit is a hydraulic structure that can be used efficiently in aeration and oxygen transfer. The subatmospheric pressure between the upstream and downstream of the gate is the reason for the air injection. Ozone is an unstable gas comprised of three oxygen atoms, and it can be used for water treatment. Ozone is thermodynamically unstable and spontaneously reverts back into oxygen. Ozone has been widely accepted as an effective disinfectant and a chemical oxidant. In this study a series of experiments was conducted to determine the ozone injection performance of circular conduits. Results showed that circular conduits are very effective for ozone injection.     

Photoinduced electron transfer mechanism between green fluorescent protein molecules and metal oxide nanoparticles

Green fluorescent protein (GFP) molecules are attached to titanium dioxide and cadmium oxide nanoparticles via sol–gel method and fluorescence dynamics of such a protein–metal oxide assembly is investigated with a conventional time correlated single photon counting technique. As compared to free fluorescent protein molecules, time-resolved experiments show that the fluorescence lifetime of GFP molecules bound to these metal oxide nanoparticles gets shortened dramatically. Such a decrease in the lifetime is measured to be 22 and 43 percent for cadmium oxide and titanium dioxide respectively, which is due to photoinduced electron transfer mechanism caused by the interaction of GFP molecules (donor) and metal oxide nanoparticles (acceptor). Our results yield electron transfer rates of 3.139×10⁸ s⁻¹ and 1.182×10⁸ s⁻¹ from the GFP molecules to titanium dioxide and cadmium oxide nanoparticles, respectively. The electron transfer rates show a marked decrease with increasing driving force energy. This effect represents a clear example of the Marcus inverted region electron transfer process.     

Ring Opening of Epoxidized Soybean Oil with Compounds Containing Two Different Functional Groups

Epoxidized vegetable oils are desirable chemicals due to their eco‐friendly characteristics and their being a major source of many green products. Ring opening is one of the ways to convert these epoxidized oils to some new intermediates. The use of mono‐functional amines, alcohols, acid anhydrides and thioethers for epoxy ring opening has been reported in the literature. In this study, thioglycolic acid (TGA) bearing thiol and carboxylic acid as two different functional groups and methyl ester of thioglycolic acid (TGAME) were used. Currently, there is no reported literature describing epoxy ring opening using chemicals bearing two different functional groups simultaneously. In this way, two new polyols were synthesized, one with TGA (polyol 1) and one with TGAME (polyol 2). FTIR and ¹H‐ and ¹³C‐NMR spectroscopy confirmed that the ring was opened by the carboxylic acid group of TGA, and the thiol group was not involved in the ring opening whereas the ring was opened by the thiol group in the case of TGAME.