High-K volcanism in the Afyon region, western Turkey: from Si-oversaturated to Si-undersaturated volcanism

Volcanic rocks of the Afyon province (eastern part of western Anatolia) make up a multistage potassic and ultrapotassic alkaline series dated from 14 to 12 Ma. The early-stage Si-oversaturated volcanic rocks around the Afyon city and further southward are trachyandesitic volcanic activity (14.23 ± 0.09 Ma). Late-stage Si-undersaturated volcanism in the southernmost part of the Afyon volcanic province took place in three episodes inferred from their stratigraphic relationships and ages. Melilite– leucitites (11.50 ± 0.03 Ma), spotted rachyandesites, tephryphonolites and lamproites (11.91 ± 0.13 Ma) formed in the first episode; trachyandesites in the second episode and finally phonotephrites, phonolite, basaltic trachyandesites and nosean-bearing trachyandesites during the last episode. The parameter Q [normative q-(ne + lc + kls + ol)] of western Anatolia volcanism clearly decreased southward with time becoming zero in the time interval 10–15 Ma. The magmatism experienced a sudden change in the extent of Si saturation after 14 Ma, during late-stage volcanic activity of Afyon volcanic province at around 12 Ma, though there was some coexistence of Si-oversaturated and Si-undersaturated magmas during the whole life of Afyon volcanic province

Archaeogenetic analysis of Neolithic sheep from Anatolia suggests a complex demographic history since domestication

Sheep were among the first domesticated animals, but their demographic history is little understood. Here we analyzed nuclear polymorphism and mitochondrial data (mtDNA) from ancient central and west Anatolian sheep dating from Epipaleolithic to late Neolithic, comparatively with modern-day breeds and central Asian Neolithic/Bronze Age sheep (OBI). Analyzing ancient nuclear data, we found that Anatolian Neolithic sheep (ANS) are genetically closest to present-day European breeds relative to Asian breeds, a conclusion supported by mtDNA haplogroup frequencies. In contrast, OBI showed higher genetic affinity to present-day Asian breeds. These results suggest that the east-west genetic structure observed in present-day breeds had already emerged by 6000 BCE, hinting at multiple sheep domestication episodes or early wild introgression in southwest Asia. Furthermore, we found that ANS are genetically distinct from all modern breeds. Our results suggest that European and Anatolian domestic sheep gene pools have been strongly remolded since the Neolithic

Kinetic, Isotherm and Thermodynamic Analysis on Adsorption of Cr(VI) Ions from Aqueous Solutions by Synthesis and Characterization of Magnetic-Poly(divinylbenzene-vinylimidazole) Microbeads

The magnetic-poly(divinylbenzene-1-vinylimidazole) [m-poly(DVB-VIM)] microbeads (average diameter 53–212 μm) were synthesized and characterized; their use as adsorbent in removal of Cr(VI) ions from aqueous solutions was investigated. The m-poly(DVB-VIM) microbeads were prepared by copolymerizing of divinylbenzene (DVB) with 1-vinylimidazole (VIM). The m-poly(DVB-VIM) microbeads were characterized by N2 adsorption/desorption isotherms, ESR, elemental analysis, scanning electron microscope (SEM) and swelling studies. At fixed solid/solution ratio the various factors affecting adsorption of Cr(VI) ions from aqueous solutions such as pH, initial concentration, contact time and temperature were analyzed. Langmuir, Freundlich and Dubinin–Radushkvich isotherms were used as the model adsorption equilibrium data. Langmuir isotherm model was the most adequate. The pseudo-first-order, pseudo-second-order, Ritch-second-order and intraparticle diffusion models were used to describe the adsorption kinetics. The apparent activation energy was found to be 5.024 kJ mol−1, which is characteristic of a chemically controlled reaction. The experimental data fitted to pseudo-second-order kinetic. The study of temperature effect was quantified by calculating various thermodynamic parameters such as Gibbs free energy, enthalpy and entropy changes. The thermodynamic parameters obtained indicated the endothermic nature of adsorption of Cr(VI) ions. Morever, after the use in adsorption, the m-poly(DVB-VIM) microbeads with paramagnetic property were separeted via the applied magnetic force. The magnetic beads could be desorbed up to about 97% by treating with 1.0 M NaOH. These features make the m-poly(DVB-VIM) microbeads a potential candidate for support of Cr(VI) ions removal under magnetic field

The pyrolytic characteristics and kinetics of agricultural waste, bituminous coal, and their blends

This study investigates the pyrolytic characteristics and kinetics of bituminous coal, vine-trimming waste, and blends of these in varying proportions. The pyrolysis of the bituminous coal and vine-trimming waste was performed at heating rates of 5°C/min, 20°C/min, and 80°C/min under a nitrogen flow rate of 50ml/min from ambient to 1000°C. Different blends containing 10%, 20%, 40%, and 50% vine-trimming waste were prepared and pyrolyzed at a heating rate of 20°C/min and a nitrogen flow rate of 50ml/min from room temperature up to 1000°C. The reaction degrees and kinetic parameters were calculated using the Coats and Redfern kinetic model. The pyrolysis of bituminous coal and vine-trimming waste took place in two stages, and with increasing heating rate there was a decrease in the activation energies. In contrast, the pyrolysis of the blends occurred in two stages. The first stage involves decomposition of vine-trimming waste, and the second one that of bituminous coal. As the proportion of vine-trimming waste in the blend increased, there was a decrease in the activation energy in the first stage and an increase in the second stage. © Taylor & Francis Group, LLC

Observation of phase transition of thermo-responsive poly(NIPA)-PEI block copolymers by STM.

N-isopropylacrylamide (NIPA) homopolymers having carboxylic acid-end groups were synthesized by using mercaptoacetic acid (MAA) as the chain transfer agent. Polymerization was achieved in ethanol using azobisisobutyronitrile (AIBN) as the initiator. Average molecular weight of the homopolymer estimated by titration was 1958. This carboxylic acid-ended poly(NIPA) was then copolymerized with polyethylenimine (PEI, M(W)-2000) using a water soluble carbodiimide (EDAC). With respect to carboxyl-ended poly(NIPA), the block copolymers exhibited a pH dependent-temperature sensitivity and higher LCST values in acidic pH. Scanning tunneling microscopy (STM) images of both the homopolymer and the copolymer were obtained at 25 and 45 degrees C with tip-sample bias voltages of up to 800 mV and tunneling currents approximately 1 nA. These images showed that STM can be used to visualize both the formation of copolymer chains and their structure, and also their stimuli-responsive behavior

In vitro transfection of HeLa cells with temperature sensitive polycationic copolymers

In this study, we investigated different types of polyethyleneimine (PEI) and their block copolymers with N-isopropylacrylamide (NIPA) as temperature-sensitive polycationic non-viral vectors for transfection of HeLa cells in cell culture media. First carboxyl-terminated poly(NIPA) was synthesized and then copolymerized with PEIs branched or linear and with two different molecular weights (2 and 25 kDa). Addition of PEI units to the poly(NIPA) chains increased the LCST values up to body temperature. Zeta potentials of the copolymers were significantly lower than the corresponding PEI homopolymers. A green fluorescent protein expressing plasmid was used as a model. Complexes of this plasmid both with PEIs and their copolymers were formed. The zeta potentials of these complexes were between -3.1 and +21.3. Higher values were observed for the complexes prepared with branched and higher molecular weight PEIs. Copolymerization caused a profound decrease in the positive charges. Particle sizes of the complexes were in the range of 190-1235 nm. Using high polymer/plasmid ratios caused aggregation. The smallest complexes were obtained with the copolymer prepared with branched PEI with 25-kDa molecular weight. Copolymers were able to squeeze plasmid DNA more at the body temperature. Cytotoxicity was observed with PEIs especially with the branched higher molecular weights. Copolymerization reduced the cytotoxicity. The best in vitro DNA uptake efficiency (70%) was achieved with the complex prepared with poly(NIPA)/PEI25B. However, poly(NIPA)/PEI25L was the most successful vector for an effective gene expression without any significant toxicity. © 2004 Elsevier B.V. All rights reserved

Pyrolysis kinetics of Turkish bituminous coals by thermal analysis

Simultaneous thermogravimetry-differential thermal analysis (TG-DTA) was used to study the pyrolysis kinetics of Turkish bituminous coals. Thermogravimetry (TG) and derivative thermogravimetry (DTG) were employed to measure the weight changes and rates of weight loss, which were used for comparison of the thermal behaviour of several coals and calculation of their kinetic parameters. Coal samples were heated in TG-DTA apparatus in an inert atmosphere (100 ml min-1 nitrogen) at a temperature range of 25-1000 °C. The activation energy (Ea) and pre-exponential factor (A) were calculated from the experimental results by using an Arrhenius-type kinetic model. The data indicate that the pyrolysis of coals is a 1-stage process. The decomposition stage (350-700 °C) has a best fit with first-order kinetics with Ea = 65-97 kJ mol-1