The simple radiochemical determination of 90Sr in environmental solid samples by solvent extraction

Determination of ⁹⁰Sr in environmental solid samples is a challenging task because of the presence of so many other radionuclides in samples of interest. This problem was dealt with by radiochemical separation of strontium followed by yttrium separation and Cerenkov counting of the high-energy ??-particle emissions of ⁹⁰Y in order to quantitate ⁹⁰Sr. In this work, an improved method is described for the determination of ⁹⁰Sr in soil samples, through the separation of the daughter ⁹⁰Y at equilibrium. The procedure is based on the HDEHP solvent extraction in combination with liquid scintillation spectrometry (LSS). A low background Quantulus has been optimized for low level counting of Cerenkov radiation emitted by the hard ??-emitter ⁹⁰Y. The analytical quality of the method has been checked by analyzing IAEA Soil-375 reference materials. The analytical method has also been successfully applied to the determination of ⁹⁰Sr for moss-soil samples in inter-laboratory exercises through IAEA??s ALMERA network. The chemical recovery for ⁹⁰Y extraction ranged from 80 to 85% and the counting efficiency was 73% in the window 25?C400 keV.     

Interaction of Mitomycin C with DNA Immobilized onto Single‐walled Carbon Nanotube/Polymer Modified Pencil Graphite Electrode

The electrochemical investigation of the interaction between the anticancer drug mitomycin C (MC) and DNA was described using a single‐walled carbon nanotube (SWCNT)/poly(vinylferrocenium) (PVF⁺) modified pencil graphite electrode (PGE). The electrochemical oxidation signals of guanine were monitored before and after the interaction between MC and DNA by using differential pulse voltammetry. The effects of DNA and MC concentration and MC interaction time were examined based on the electrode response. Cyclic voltammetry and electrochemical impedance spectroscopy were used for the characterization of SWCNT/PVF⁺ modified and PVF⁺ modified PGEs. The detection limit corresponded to 625 ng/mL for MC using calf thymus double‐stranded DNA immobilized SWCNT/PVF⁺ modified PGE.     

Treatment of opium alkaloid containing wastewater in sequencing batch reactor (SBR)—Effect of gamma irradiation

Aerobic biological treatment of opium alkaloid containing wastewater as well as the effect of gamma irradiation as pre-treatment was investigated. Biodegradability of raw wastewater was assessed in aerobic batch reactors and was found highly biodegradable (83–90% degradation). The effect of irradiation (40 and 140 kGy) on biodegradability was also evaluated in terms of BOD₅/COD values and results revealed that irradiation imparted no further enhancement in the biodegradability. Despite the highly biodegradable nature of wastewater, further experiments in sequencing batch reactors (SBR) revealed that the treatment operation was not possible due to sludge settleability problem observed beyond an influent COD value of 2000 mg dm^?3. Possible reasons for this problem were investigated, and the high molecular weight, large size and aromatic structure of the organic pollutants present in wastewater was thought to contribute to poor settleability. Initial efforts to solve this problem by modifying the operational conditions, such as SRT reduction, failed. However, further operational modifications including addition of phosphate buffer cured the settleability problem and influent COD was increased up to 5000 mg dm^?3. Significant COD removal efficiencies (>70%) were obtained in both SBRs fed with original and irradiated wastewaters (by 40 kGy). However, pre-irradiated wastewater provided complete thebain removal and a better settling sludge, which was thought due to degradation of complex structure by radiation application. Degradation of the structure was observed by GC/MS analyses and enhancement in filterability tests.     

Fluorescent chemosensor for Ag(I) based on amplified fluorescence quenching of a new phthalocyanine bearing derivative of benzofuran

A fluorescent chemosensor for Ag(I) as a new family of peripherally functionalized zinc-phthalocyanine, 2(3),9(10),16(17),23(24)-tetrakis-{6-(-benzofuran-2-carboxylate)-hexylthio} phthalocyaninatozinc(II) {Zn[Pc(β-S(CH₂)₆OCOBz-furan)₄], (ZnPcBzF), (3), which was derivated from 6-(3,4-dicyanophenylthio)-hexyl–2-benzofuranate (BzF), (2), has been synthesized and fully characterized by elemental analysis, FT-IR, ¹H and ¹³C NMR, MS (ESI and Maldi-TOF). An optical silver ion (Ag(I)) sensor based on the fluorescence quenching of benzofuran moiety and ZnPc core was developed. Both absorbance and fluorescence spectra of ZnPcBzF, (3) exhibit distinct changes in visible region in response to treatment with Ag(I) ion in solution. Such properties make compound ZnPcBzF, (3) intriguing candidates for incorporation into the transducer layer in optically based chemical sensors.     

Synthesis and liquid crystal properties of phthalocyanine bearing a star polytetrahydrofuran moiety

A new polymeric ligand, 6-(3,4-dicyanophenylthio)-hexyl-2-polytetrahydrofuranacetate (2) and its liquid crystalline polymeric phthalocyanine, 2,9,16,23-tetrakis-{6-(polytetrahydrofuran-2-carboxylate)-hexylthio-phthalocyaninatocobalt(II) (3), {Co[Pc(S-C₆H₁₃OCO-poly-THF)₄]}(CoPcLC) have been synthesized. The ligand and the phthalocyanine, bearing polytetrahydrofuran moieties (poly-THF), were characterized using elemental analysis, FTIR, ¹H and ¹³C NMR, and UV–Vis techniques. CoPcLC (3) promotes a greater interaction between the mesogens, resulting in solution aggregations together with a red-shift in the Q-band in the presence of the soft Ag⁺ ion. The dielectric anisotropy and phase transition temperature values of CoPcLC doped with 4-cyano-4′-n-pentylbiphenyl (5CB) were found to be 7.17 and 40.5 °C, respectively. The dielectrical anisotropy behaviour of the liquid crystals changes from the positive to the negative type. The current–voltage characteristics of the liquid crystals show a non-linear behaviour.     

The Effects of Different Doses of ROCK Inhibitor,Antifreeze Protein III,and Boron Added to Semen Extender on Semen Freezeability of Ankara Bucks

In the presented study, the effects of ROCK inhibitor Y-27632, antifreeze protein III, and boron at two different doses were investigated on the spermatological parameters of Ankara buck semen after freeze–thawing. Ejaculates were collected from bucks using an electroejaculator during the breeding season. The ejaculates that showed appropriate characteristics were pooled and used in the dilution and freezing of semen. The extender groups were formed by adding two different doses of three different additives (ROCK inhibitor Y-27632, 5 and 20 µM; antifreeze protein III, 1 and 4 µg/mL; boron, 0.25 and 1 mM) to the control extender. The semen was diluted with the different extenders at 35–37 °C and loaded into straws. Sperm samples frozen in liquid nitrogen vapors, following equilibration, were stored in liquid nitrogen. It was observed that extender supplementation improved post-thaw motility of Ankara buck semen after freeze–thawing. Differences were significant (p < 0.01) for 5 and 10 µM doses of ROCK inhibitor (71.82% and 74.04 % motility), as well as for 0.25 and 1 mM doses of boron (76.36% and 72.08% motility), compared to the control group (66.15% motility). With respect to the evaluation of acrosomal integrity and mitochondrial activity after freeze–thawing, although supplementation provided protection at all doses, the efficacy was not statistically significant (p > 0.05). It was observed that DNA damage was improved by antifreeze protein III at 1 µg/mL (1.23% ± 0.23%) and by boron at all doses (0.25 mM: 1.83% and 1 mM: 1.18%) compared to the control group (3.37%) (p < 0.01), following the thawing process. In the present study, it was determined that some additives added to the extender provided significant improvements in buck spermatozoa motility and DNA damage after thawing.     

Muscle skin temperature responses for hamstring and quadriceps to aerobic and anaerobic test conditions in Turkish Olympic Sailing Athletes

Olympic class sailing is a competitive sport and requires several abilities. An understanding of the responses to aerobic and anaerobic loading will be useful for assessing the training programs, protective strategies and possibility of injuries. Therefore, the aim of this study is to determine lower extremity main muscles skin temperature responses to aerobic and anaerobic test conditions in Turkish Olympic Sailing Athletes. Eighteen sailing athletes were assessed during preseasonal assessment period. Temperatures of quadriceps and hamstring muscle groups were evaluated bilaterally during rest and after Wingate Treadmill tests. Wingate test was accepted as an indicator of anaerobic performance and Treadmill test as an aerobic performance. Infrared thermography was performed to assess the skin temperature at anterior and posterior parts of thigh for both legs. In the triplicate comparison, the temperature changes between the rest, aerobic test and anaerobic test conditions were significant (p?<?0.05). In the analysis to determine the difference between the compared groups; for both muscle groups, temperature change after anaerobic performance was not significant; in contrast to this result the change in muscle temperature after aerobic performance was significant (p?<?0.05). Energetic—metabolic activity of major muscle groups of lower extremities during aerobic and anaerobic performance are important for injury prevention, treatment, rehabilitation and return to play. Present study shows that aerobic performance or activities requires higher energetic-metabolic activity.

     

Analysis of glass transition and relaxation processes of low molecular weight polystyrene-b-polyisoprene diblock copolymers

The objective of this study is to analyze the glass transition temperature and relaxation processes of low molecular weight polystyrene-block-polyisoprene diblock copolymers with different compositions, synthesized via anionic polymerization. Thermal properties were investigated by differential scanning calorimetry and dynamic-mechanical thermal analysis, while the morphologies at room temperature were investigated by transmission electron microscopy and small-angle X-ray scattering. The χN values indicate that the diblock copolymers lie near the weak segregation regime. Three different experimental techniques were applied to determine the dynamic properties, i.e., linear viscoelastic shear oscillations, creep recovery experiments, and dielectric spectroscopy. The rheological experiments were performed above the order–disorder transition temperature where the diblock copolymers behave like a Maxwell fluid. Our results indicate that the presence of the polyisoprene segments strongly influences the monomeric friction coefficient and the tendency to form entanglements above the order–disorder temperature. Consequently, the zero-shear rate viscosity of a diblock copolymer is much lower than the zero-shear rate viscosity of the neat polystyrene block (the polystyrene precursor of the polymerization procedure). Dielectric spectroscopy enables the analysis of relaxation processes below the glass transition of the polystyrene microphase. Frequency sweeps indicate the dynamic glass transition of the polyisoprene blocks, which are partly mixed with the polystyrene blocks, which are always the majority component in the block copolymers of this study.     

Correlation of gas permeation and free volume in new and used high free volume thin film composite membranes

Polymeric gas separation membranes frequently undergo the phenomenon of aging, that is, performance parameters like permeability decrease with storage or usage time. Here, we report on a new approach of reducing aging by incorporation of functionalized multiwalled carbon nanotubes into a polymer of intrinsic microporosity. Free volume and permeability measurements clearly show a reduced aging with incorporation of the carbon nantubes. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 213–217