Hemocompatibility,cytotoxicity, and genotoxicity of poly(methylmethacrylate)/nanohydroxyapatite nanocomposites synthesized by melt blending method

The aim of this study was to show the hemocompatibility, cytotoxicity, and genotoxicity of nanocomposites that were synthesized with different molecular weights of poly(methyl methacrylate) (PMMA) and different concentrations of nanohydroxyapatite (nHAp). Different techniques to characterize the nanocomposites were used. The cytotoxicity and genotoxic effects of the polymers and nanocomposites on human lymphocytes were determined by acid phosphatase assay, viability test, and comet assay. Moreover, hemocompatibility test was performed. It was found that all of the PMMA/nHAp nanocomposites are highly hemocompatible and biocompatible, none of the nanocomposites showed a cytotoxic effect, and nHAp addition decreased the genotoxicity.     

Dye‐affinity hollow‐fibres and their lysozyme adsorption–desorption characteristics

Dye‐affinity adsorption is increasingly used for protein separation. Hollow‐fibres have advantages as adsorbents in comparison to conventional bead supports because they are not compressible and can eliminate internal diffusion limitations. The aim of this study was to explore in detail the performance of polyamide hollow‐fibres to which Reactive Green HE‐4BD was attached for adsorption of lysozyme. The hollow‐fibre was characterized by scanning electron microscopy. These dye‐carrying hollow‐fibres (26.3 µmol g^?1) were used in the lysozyme adsorption–elution studies. The effect of initial concentration of lysozyme and medium pH on the adsorption efficiency of dye‐attached hollow‐fibres was studied in a batch system. The non‐specific adsorption of lysozyme on the polyamide hollow‐fibres was 1.8 mg g^?1. Reactive Green HE‐4BD attachment significantly increased the lysozyme adsorption up to 41.1 mg g^?1. Langmuir adsorption model was found to be applicable in interpreting lead adsorption by Reactive Green HE‐4BD attached hollow fibres. Significant amount of the adsorbed lysozyme (up to 95%) was eluted in 1 h in the elution medium containing 1.0 M NaSCN at pH 8.0. In order to determine the effects of adsorption conditions on possible conformational changes of lysozyme structure, fluorescence spectrophotometry was employed. We concluded that polyamide dye‐affinity hollow‐fibres can be applied for lysozyme adsorption without causing any significant conformational changes. Repeated adsorption–elution processes showed that these dye‐attached hollow‐fibres are suitable for lysozyme adsorption. © 2001 Society of Chemical Industry     

The adsorption behavior of cesium on poly(N-isopropylacrylamide/itaconic acid) copolymeric hydrogels

In this study, N-isopropylacrylamide/itaconic acid (NIPAAm/IA) hydrogels prepared by irradiating with γ radiation were used in experiments on cesium ion adsorption. The cesium ion adsorption capacity of the hydrogels was investigated as a function of Cs⁺ concentration, pH and temperature. The adsorption behavior of cesium was evaluated by using the radiotracer method. The adsorption isotherm models were applied to the experimental data, and it was seen that Freundlich isotherm explained the adsorption better than Langmuir isotherm. Two simplified kinetic models including pseudo-first-order and pseudo-second-order equation were selected to follow the adsorption processes. The Cs⁺ adsorption could be best described by the pseudo-first-order equation. The thermodynamic parameters including ΔG°, ΔH° and ΔS° for adsorption processes of Cs⁺ on the hydrogel were also calculated, and the negative ΔH° and ΔG° confirmed that the adsorption process was exothermic and spontaneous.     

Comparison of Fatty Acid, Sterol, and Tocol Compositions in Skin and Kernel of Turpentine (Pistacia terebinthus L.) Fruits

Pistacia terebinthus L. is an indigenous plant growing wild in the southern regions of Turkey. Its fruits are used in foods, pharmaceuticals and cosmetics due to its high oil content (ca. 45 g/100 g). In the present study, it was found out that the kernel and the skin parts of the fruit differ significantly (p < 0.05) both in terms of oil content and composition. Regardless of the geographical origin, the most abundant fatty acid was found to be monounsaturated oleic acid, 18:1n-9 whose content was in the range of 51.2–67.5 g/100 g. β-sitosterol is the predominant sterol in kernel and skin of the terebinthus fruits whose content was varying between 97.4 and 219.8 mg/100 g. Concerning different tocols (tocopherols and tocotrienols) detected in the kernel and skin, γ-T was the one with highest concentration (437.2 mg/kg) in kernels, while the most abundant one in skin parts was found to be α-T (348.7 mg/kg). In general the kernel of terebinthus fruits was more concentrated in PUFA, total sterol and tocopherols than skin, however, total tocotrienol content was higher in skin than kernel. On the basis of these findings it can be concluded that both kernel and skin are highly valuable in terms of bioactive compounds, whereas skin with a high amount saturated fatty acids is more suited to applications in cosmetic industry.     

Photocatalytic degradation kinetics of di- and tri-substituted phenolic compounds in aqueous solution by TiO2/UV

In this study, photocatalytic degradation of 2,4,6-trimethylphenol (TMP), 2,4,6-trichlorophenol (TCP), 2,4,6-tribromophenol (TBP), 2,4-dimethylphenol (DMP), 2,4-dichlorophenol (DCP) and 2,4-dibromophenol (DBP) has been studied by TiO₂/UV. Although degraded phenolic compound concentration increased by increasing initial concentration photocatalytic decomposition rates of di- and tri-substituted phenols at 0.1–0.5 mM initial concentrations decreased when the initial concentration increased. The fastest degradation observed for TCP and the slowest for TMP. Photodegradation kinetics of the compounds has been explained in terms of Langmuir–Hinshelwood kinetics model. Degradation rate constants have been observed to be extremely depended on electronegativity of the substituents on phenolic ring. Degradation rate constant and adsorption equilibrium constant of TCP were calculated as k 0.0083 mM min⁻¹ and K 9.03 mM⁻¹. For TBP and TMP the values of k and K were obtained as 0.0040 mM min⁻¹, 19.20 mM⁻¹, and 0.0017 mM min⁻¹, 51.68 mM⁻¹, respectively. Degradation rate constant of DBP was similar as DCP (0.0029 mM min⁻¹ for DBP and 0.0031 mM min⁻¹ for DCP) whereas adsorption equilibrium constants differed (48.40 mM⁻¹ for DBP and 30.52 mM⁻¹ for DCP). K and k of DMP found as 83.68 mM⁻¹ and 0.0019 mM min⁻¹, respectively. The adsorption equilibrium constants in the dark were ranged between 1.11 and 3.28 mM⁻¹ which are lower than those obtained in kinetics. Adsorption constants have inversely proportion with degradation rate constants for all phenolic compounds studied.     

Casting properties of ASTM A128 Gr. E1 steel modified with Mn-alloying and titanium ladle treatment

This work aims to produce a high manganese steel with more refined austenite grains and better wear resistance without sacrificing the toughness and tensile properties by Mn alloying and Ti ladle treatment in comparision to ASTM A128 Gr. E1 steel (1.0C-13Mn) that is mostly used in the mining industry. The 1.0C-17Mn-xTi alloys (x=0, 0.05 and 0.1, in wt.%) were prepared. A relationship was established between the microstructures and mechanical properties of the as-cast and solution annealed alloys. Increasing Ti content increases the stable Ti(CN) phase on and beside the grain boundaries and decreases up to 37% the austenite grain size of the as-cast alloy with 0.10wt.% Ti. Correspondingly, after solution annealed, optimized titanium content (0.05wt.%) results in significant improvements in wear resistance, hardness, elongation, yield and tensile strengths by 44%, 31%, 30%, 8% and 12%, respectively, except 9% decrease in impact toughness compared to ASTM A 128 Gr. E1 steel without modification. These results show that 1.0C-17Mn-0.05Ti alloy can be used for parts exposed to high load wear and applied in conditions where relatively high tensile properties with sufficent ductility is needed.

     

Allochthonous blocks misidentified as the basement: Implication for petroleum exploration in the SW Thrace Basin (Turkey)

The sedimentary sequence of the SW Thrace Basin (NW Turkey) comprises of three major sedimentary packages: a) Cretaceous (Meastrichtien)–Early Eocene package formed as pelagic carbonate, turbidite, shelf and nearshore-fluvial deposits, b) Middle Eocene–Early Oligocene package formed as shallow marine, slope apron and turbidite sediments, c) Middle Miocene–Early Pliocene package formed as alluvial fan-fluvial and nearshore deposits. This basin is structurally complex and its southern margin is represented by a fold-thrust zone. The Westward Propagation of the North Anatolian Fault (WPNAF) intersects the Thrace Basin along its southwestern flank. In the SW Thrace Basin, there are ophiolite and limestone blocks in the sedimentary succession, which previously were interpreted as suture of the Intra-Pontide Ocean, Cretaceous aged Yeniköy Mélange or Olistostromal Unit in the Eocene sediments. In this study these rocks have been defined as allochthonous blocks facies of the Gaziköy Formation aged Middle–Late Eocene.In previous studies the Karaağaç Formation (Early Eocene) was considered to be within oil window and have an average potential for oil and gas generation. According to our data the Karaağaç Formation has a moderate TOC content, is mature and overmature. In the study area, there are potential stratigraphic traps (submarine fans and channels of the Karaağaç and Keşan Formations, fluvial channels of the Fıçıtepe Formation and reefs of the Soğucak Formation), potential fractured tuffs (the Gaziköy Formation) and, potential structural traps related to the folds, thrusts and the WPNAF. Although 17 exploration wells have been drilled in the study area and vicinity, no discovery has yet been made. The cause of this may be that the wells were terminated at depths shallower than potential targets or possibly drilling may have been terminated at the allochthonous block facies of the Gaziköy Formation, which is especially derived from ophiolite mélange and was misidentified as basement.     

Edge-Cut Bounds on Network Coding Rates

Active networks are network architectures with processors that are capable of executing code carried by the packets passing through them. A critical network management concern is the optimization of such networks and tight bounds on their performance serve as useful design benchmarks. A new bound on communication rates is developed that applies to network coding, which is a promising active network application that has processors transmit packets that are general functions, for example a bit-wise XOR, of selected received packets. The bound generalizes an edge-cut bound on routing rates by progressively removing edges from the network graph and checking whether certain strengthened d-separation conditions are satisfied. The bound improves on the cut-set bound and its efficacy is demonstrated by showing that routing is rate-optimal for some commonly cited examples in the networking literature.     

SENDROM: Sensor networks for disaster relief operations management

SENDROM is a new sensor network architecture to manage the rescue operations after large scale disasters. This architecture mainly consists of sensor nodes deployed prior to a disaster and central nodes that can query sensor nodes. Central nodes are stored nearby the emergency operation centers and airports before a disaster. Following a disaster rescue teams are assigned one mobile central node and guided to a region based on the data in the SENDROM database. This paper explains the SENDROM architecture as well as our new task and data dissemination, localization of a detected person, and end-to-end reliable event transfer schemes introduced for SENDROM. Then it evaluates the performance of these schemes analytically and through simulation.     

A Comparison of Various Artificial Intelligence Methods in the Prediction of Bank Failures

The strong relationship between bank failure and economic growth attaches far more importance to the predictability of bank failures. Consequently, numerous statistical prediction models exist in the literature focusing on this particular subject. Besides, artificial intelligence techniques began to attain an increasing level of importance in the literature due to their predictive success. This study distinguishes itself from the similar ones in the sense that it presents a comparison of three different artificial intelligence methods, namely support vector machines (SVMs), radial basis function neural network (RBF-NN) and multilayer perceptrons (MLPs); in addition to subjecting the explanatory variables to principal component analysis (PCA). The extent of this study encompasses 37 privately owned commercial banks (17 failed, 20 non-failed) that were operating in Turkey for the period of 1997–2001. The main conclusions drawn from the study can be summarized as follows: (i) PCA does not appear to be an effective method with respect to the improvement of predictive power; (ii) SVMs and RBF demonstrated similar levels of predictive power; albeit SVMs was found to be the best model in terms of total predictive power; (iii) MLPs method stood out among the SVMs and RBF methods in a negative sense and exhibits the lowest predictive power.