Natural and anthropogenic radionuclides in the granitic region of Kapidag peninsula, Western Anatolia, Turkey

Naturally occurring radionuclides of terrestrial origin (also called primordial radionuclides) are present in various degrees in all media in the environment. This study represents the reports on the natural and anthropogenic radionuclides in the Kapidag granitic region. For this purpose, activities of radionuclides in soil, beach sands and rocks of the region have been investigated to assess the radiological hazard of the natural radioactivity. The radium equivalent activities, the absorbed dose rates and the external hazard indexes have been calculated, and also in situ gamma dose rates have been measured in the region. The mean activities of (238)U, (232)Th and (40)K with the ranges were determined as 31.1±15.7 (12.1-71.9), 42.5±15.9 (19.7-94.9), 590.3±192.2 (184.7-892.5), in the soil, as 16.5±9.5 (4.9-40.8), 67.1±106.9 (18.5-433.0), 569.2±212.6 (162.0-821.1) in the sand and as 25.4±12.8 (4.8-50.7), 37.8±21.5 (4.5-96.7), and 592.4±285.5 (62.4-1121.6) Bq kg(-1) in the rocks, respectively. It was also observed that the average activities of (137)Cs were ranged 0-27.8 Bq kg(-1) in the soil and 0.6-3.8 Bq kg(-1) in the beach sands. The mean Ra(eq) activities of the rocks, sands and soil were found to be 125.1±59.5, 156.3±157.2 and 137.3±48.8 Bq kg(-1), respectively, lower than the recommended maximum value of 370 Bq kg(-1) with some exceptions. The maximum contributors to the total absorbed gamma dose rates in air were determined as (238)U (45%) for the beach sands, (238)U (40%) for the soil and (40)K (41%) for rocks. The average outdoor gamma dose rates for the soil due to terrestrial and cosmic radiations were found to be 64.6±22.7 and 47.1±9.6 nGy h(-1), respectively, with the total of 111.7±29.5 nGy h(-1) outdoor gamma exposure rate and the annual average effective outdoor gamma dose was calculated as 137±36.2 μSv for the region. The results of the study were discussed with similar studies in close regions and the worldwide averages.     

Assessment of natural radioactivity concentrations and gamma dose rate levels in Kayseri, Turkey

This study assesses the level of background radiation for Kayseri province of Turkey. Natural radionuclide activity concentrations in soil samples were determined using high-resolution gamma spectroscopy. Outdoor gamma dose measurements in air at 1 m above ground level were determined using a portable gamma scintillation detector. The obtained results of uranium and thorium series as well as potassium ((40)K) are discussed. The present data were compared with the data obtained from different areas in Turkey. From the measured gamma-ray spectra, the average activity concentrations were determined for (238)U (range from 3.91 to 794.25 Bq kg(-1)), (232)Th (range from 0.68 to 245.55 Bq kg(-1)) and (40)K (range from 23.68 to 2718.71 Bq kg(-1)). The average activity concentrations of (238)U, (232)Th and (40)K were found to be 35.51, 37.27 and 429.66 Bq kg(-1), respectively, and 11.53 Bq kg(-1) for the fission product (137)Cs. The highest values of (238)U, (232)Th and (40)K concentrations (794.25 Bq kg(-1), 245.55 Bq kg(-1), 2718.71 Bq kg(-1), respectively) were observed in abnormal samples at Hayriye village. The average outdoor gamma dose rate in air at 1 m above the ground was determined as 114.43 nGy h(-1). Using the data obtained in this study, the average annual effective dose for a person living in Kayseri was found to be about 140.34 μSv.     

A novel quinoxaline bearing electroactive monomer: Pyrrole as the donor moiety

A novel electroactive monomer 5,8-di(1H-pyrrol-2-yl)-2,3-di(thiophen-2-yl)quinoxaline (PTQ) was successfully synthesized and its electrochromic properties were reported. Nuclear magnetic resonance (¹H NMR-¹³C NMR) and mass spectroscopy were used to characterize the monomer. The monomer was electrochemically polymerized in the presence of tetrabutylammonium perchlorate (TBAP) as supporting electrolyte in dichloromethane. Monomer reveals relatively low oxidation potential at +0.70 V. Spectroelectrochemical behaviors and switching ability of homopolymer were investigated by UV-vis spectroscopy and cyclic voltammetry. Two π-π* transitions were observed at 400 and 815 nm with a low band gap, 1.0 eV. Polymer possesses 66% optical contrast in the Near IR region, which may be promising in NIR electrochromic device applications.     

A Biomimetic,Copolymeric Membrane for Cell-Stretch Experiments with Pulmonary Epithelial Cells at the Air-Liquid Interface

Chronic respiratory diseases are among the leading causes of death worldwide, but only symptomatic therapies are available for terminal illness. This in part reflects a lack of biomimetic in vitro models that can imitate the complex environment and physiology of the lung. Here, a copolymeric membrane consisting of poly(ε-)caprolactone and gelatin with tunable properties, resembling the main characteristics of the alveolar basement membrane is introduced. The thin bioinspired membrane (≤5 μm) is stretchable (up to 25% linear strain) with appropriate surface wettability and porosity for culturing lung epithelial cells under air–liquid interface conditions. The unique biphasic concept of this membrane provides optimum characteristics for initial cell growth (phase I) and then switch to biomimetic properties for cyclic cell-stretch experiments (phase II). It is showed that physiologic cyclic mechanical stretch improves formation of F-actin cytoskeleton filaments and tight junctions while non-physiologic over-stretch induces cell apoptosis, activates inflammatory response (IL-8), and impairs epithelial barrier integrity. It is also demonstrated that cyclic physiologic stretch can enhance the cellular uptake of nanoparticles. Since this membrane offers considerable advantages over currently used membranes, it may lead the way to more biomimetic in vitro models of the lung for translation of in vitro response studies into clinical outcome.     

Characterization of server performance bottlenecks in distributed interactive simulation environments

Servers running distributed simulation applications need to process a large number of small packets at the network level. This becomes a burden on the server CPUs and exhibits itself as high CPU utilization. In this paper, first, we confirm this phenomenon, then, we utilize performance analyzer tools from major processor vendors to characterize the major sources of CPU usage. In addition, the experiments run on real hardware reveal server bottlenecks within the context of new architectural features such as hyper-threading, hyper-transport and multi-core processors.     

Effect of Aging Time at High Temperature on the Shear Strength of Adhesively Bonded Aluminum Composite Foam Joints

In this study, the shear strength behavior of adhesively bonded joints, made of aluminum composite foams subjected to high-temperature processes, has been investigated. Aluminum composite foam and solid aluminum blocks were used to form single lap joints and as the binder, a methacrylate-based structural adhesive has been selected. Foam-foam and solid-foam joints were formed and cured at room temperature for 24 hours. After curing process, aging at 200 ^oC was performed on the samples for 15, 30, 45, 60 minutes. The aged samples were subjected to lap shear testing for adhesively bonded metals and the influences of aging duration on joint strength and failure type were investigated.

As a result, lower strengths were obtained in all samples that aged under high temperature compared to non-aged samples. After the application of short-term (15-30 min) aging processes on samples, it is observed that they have joint strength values about 50% of the joint strength of non-aged samples. However, strength values of short-term aged joints (15, 30 min) remain higher than the strength values of the foam materials used in the tests. These results show that methacrylate-based adhesives subjected to short-term thermal loads up to 200 °C can be used in constructions.     

Mineral nutrition of wheat,chickpea and lentil as affected by mixed cropping and soil moisture

Interspecific complementary and competitive interactions on yield and N, P, K, Fe, Zn and Mn nutrition of mixed wheat/chickpea and wheat/lentil grown in a glasshouse under normal and drought conditions, and intercropping of wheat/chickpea in the field under rainfed conditions were investigated. The results of the experiments confirmed that drought significantly decreased the growth and mineral nutrition of all plant species. Individual plant dry weights of wheat, chickpea and lentil in the glasshouse experiment, and vegetative shoot dry weight of intercropped wheat in the field experiment were significantly increased by the associated plant species as compared with their monoculture. Even though there were increases in vegetative shoot dry weight of wheat, biological and seed yield of intercropped wheat and chickpea were decreased due to the lower row number in intercropping. However, the calculated LER (Land Equivalent Ratio) was found to be higher than 1.0 for biological and seed yields, showing that intercropping of wheat and chickpea has an advantage over monoculture. In many cases, the drought × cropping system interaction on the nutrient concentrations of plant species was not significant. Results of the glasshouse study showed that P nutrition of wheat was improved by chickpea and lentil, which might result from increases in leaf acid phosphatase in mixed cropping. The release of Fe(III)-complexing compounds from the roots was higher in the sole wheat and mixed culture than that of monocultured chickpea and lentil. This improves Fe nutrition of wheat and chickpea, but those improvements were not significant. However, Zn and Mn concentrations of mixed cropped chickpea were also increased. Under the field conditions, shoot concentration of P, K, Fe, Zn and Mn in wheat were increased by intercropping. Furthermore, the concentrations of Zn and Mn in chickpea were increased by intercropping while N, P and K concentrations were decreased. In addition, the concentrations of N, P, K and Fe for wheat seeds and of Zn and Mn for chickpea were improved by intercropping. It is concluded that interspecific interaction was complementary and generally facilitated the mineral nutrition of wheat and chickpea species grown in mixed culture. Besides giving a yield advantage, intercropping of chickpea and wheat also had a positive effect on seed mineral composition.     

Iterative skew minimization for low swing clocks

This paper presents a new methodology that implements a low swing clock tree. For low power IC design, low swing clock trees are one of the known techniques to lower the overall power dissipation through decreasing the power consumption of the clock network, while trading off the clock skew, local timing (slack) and the variation-tolerance (due to decreased noise margin). In this paper, an iterative skew minimization scheme for low swing clock trees is proposed via in-place buffer sizing considering multiple process corners. The proposed approach can preserve the power savings of the low swing clock tree implementation across multiple process corners. The effect of the decreased clock swing on the local timing is analyzed: The degradation in the timing slack is shown to be insignificant due to bounded clock slew eliminating most of the timing degradation on the clock network or the logic paths induced by decreased clock swing. The experimental results show that the proposed methodology can achieve an average of up to 11% power savings, with a skew degradation of less than 5% compared to the original full-swing clock tree, satisfying a practical skew budget. The proposed scheme is highly practical as it only performs in-place buffer sizing on the original clock tree.     

Linearization of the timing analysis and optimization of level-sensitive digital synchronous circuits

This paper describes a linear programming (LP) problem formulation applicable to the static-timing analysis of large scale synchronous circuits with level-sensitive latches. Specifically, an LP formulation for the clock period minimization problem is developed. In order to minimize the clock period of level-sensitive circuits, the simultaneous effects of time borrowing and nonzero clock skew scheduling are considered. The clock period minimization problem is formulated for both single-phase and multi-phase clocking schemes. The ISCAS'89 benchmark circuits are used to derive experimental results. LP minimization problems for these benchmark circuits are generated using the modified big M (MBM) method and the generated problems are solved using the industrial LP solver CPLEX . The experimental results demonstrate up to 63% improvements in minimum clock period compared to flip-flop based circuits with zero clock skew.