Radioactivity concentrations and dose assessment in surface soil samples from east and south of Marmara region, Turkey

The activity concentrations of 137Cs, 40K, 232Th, 238U and 226Ra were measured in surface soil samples from East and South of Marmara region, Turkey. The physico-chemical parameters (organic matter, CaCO3 contents and pH-value) of the soil samples were determined in the samples collected from 100 sampling stations. The average activity concentrations of 137Cs, 40K, 232Th, 238U and 226Ra were found to be 27.46+/-21.84, 442.51+/-189.85, 26.63+/-15.90, 21.77+/-12.08 and 22.45+/-13.31 Bq kg(-1), respectively. The mean value of total annual external gamma radiation dose equivalent for the natural radionuclides was calculated to be 54.86 microSv. The current data were compared with those found in the other locations of Turkey and different countries.     

Techno-economical evaluation of electrocoagulation for the textile wastewater using different electrode connections

The bench scale of an electrocoagulation (EC) unit requires a detailed study discerning the effects of continuous variables such as pH, current density and operating time, and type variables such as electrode material and connection mode. This paper presents the results of the treatment of a textile wastewater by EC process. Two electrode materials, aluminum and iron, were connected in three modes namely, monopolar-parallel (MP-P), monopolar-serial (MP-S), and bipolar-serial (BP-S). COD and turbidity removals were selected as performance criteria. For a high COD removal, acidic medium is preferable for both electrode materials. For a high turbidity removal, acidic medium is preferable for aluminum, and neutral medium for iron. High current density is favorable for both removals in the case of iron. In the aluminum case, the current density exhibits a pronounced effect on COD removal, depending strongly on the connection mode, but it has a negligible effect on the turbidity removal. MP-P with iron or MP-S with aluminum electrode are suitable configurations in regard with the overall process performance. Moreover, process economy is as important as removal efficiencies during the process evaluation task. Various direct and indirect cost items including electrical, sacrificial electrodes, labor, sludge handling, maintenance and depreciation costs have been considered in the calculation of the total cost. The results show that MP-P mode is the most cost-effective for both electrode types. Both electrodes show similar results in reducing COD and turbidity, but iron is preferred as a low cost material. Finally, a comparative study showed that EC was faster and more economic; consumed less material and produced less sludge, and pH of the medium was more stabilized than chemical coagulation (CC) for similar COD and turbidity removal levels. For CC, FeCl(3) was the preferable salt in view of its techno-economic performance. On the other hand, iron was the preferred electrode material in EC with MP-P system in experimental conditions such as, 30 Am(-2) of current density and 15 min of time, the treatment cost was $ 0.245 m(-3). Consequently, the operating cost of CC was 3.2 times as high as the operating cost of EC.     

Fatigue Performance of CFRP Strengthened RC Beams under Environmental Conditioning and Sustained Load

Carbon fiber-reinforced polymers (CFRPs) have become increasingly important in recent years in bridge rehabilitation. Significant research has been done on the static behavior of CFRP-strengthened reinforced concrete (RC) structures; however, the fatigue behavior of such structures with interface defects subjected to harsh environmental conditions still needs to be investigated. Hence, an experimental program has been carried out to investigate the fatigue behavior, under a load range, which generates service load stress levels, of RC beams strengthened with CFRP fabrics. The effect of aggressive environments was studied by subjecting the test members to freeze–thaw, extreme temperature, ultraviolet light exposure, and relative humidity cycles. All beams survived 2 million fatigue cycles without showing significant bond degradation between composite and substrate. However, significant flexural stiffness degradation was observed in the conditioned specimens. The presence of defects also affected specimen stiffness; however, limited growth in defect size was observed due to fatigue cycling.     

Kinetic and isotherm studies of Cu(II) biosorption onto valonia tannin resin

The biosorption of Cu(II) from aqueous solutions by valonia tannin resin was investigated as a function of particle size, initial pH, contact time and initial metal ion concentration. The aim of this study was to understand the mechanisms that govern copper removal and find a suitable equilibrium isotherm and kinetic model for the copper removal in a batch reactor. The experimental isotherm data were analysed using the Langmuir, Freundlich and Temkin equations. The equilibrium data fit well in the Langmuir isotherm. The experimental data were analysed using four sorption kinetic models - the pseudo-first- and second-order equations, the Elovich and the intraparticle diffusion model equation - to determine the best fit equation for the biosorption of copper ions onto valonia tannin resin. Results show that the pseudo-second-order equation provides the best correlation for the biosorption process, whereas the Elovich equation also fits the experimental data well.     

The Inhibition Effect of (E)-2-Hydroxy-5-(2-benzylidene) Aminobenzoic Acid on Corrosion behaviour of Mild Steel in 1.0 M HCl Solution

Protection of Metals and Physical Chemistry of Surfaces - It has recently been synthesized a Schiff base (E)-2-hydroxy-5-(2-benzylidene) aminobenzoic acid and characterized by FTIR, UV–vis...     

一种维吾尔语句子相似度算法的研究

基于实例的机器翻译是一种重要的机器翻译技术,句子相似度的衡量是基于实例机器翻译研究中最重要的一个内容。对于基于实例的维吾尔语机器翻译研究,维吾尔语句子相似度衡量的准确性,直接影响到最后翻译结果的输出。提出了一种维吾尔语句子相似度的计算方法,采用的基于词形特征的粗选算法、散列单词倒排索引能够有效提高算法的查找速度,快速从语料库中筛选出候选句子集合;多策略精选算法中采用基于维吾尔语词频的单词区分度算法、连续单词序列抽取算法,可以有效衡量两个维吾尔语句子的相似程度,实验结果证明算法是有效的。     

Electrical characteristics of Al/(GO:PTCDA)/p-type Si structure under dark and light illumination: photovoltaic properties at 40 mW cm−2

Journal of Materials Science: Materials in Electronics - In this study, the illumination dependence of current–voltage (I–V) and capacitance–voltage (C–V) characteristics of...     

Evaluation of steelmaking slag for CO2 fixation by leaching-carbonation process

Steelmaking slag is a good alternative material for the fixation of CO₂ gas as precipitated calcium carbonate (PCC) that are of used in many industrial applications such as paint, plastic, medical and so on. Therefore, the experimental conditions for production of PCC from steelmaking slag produced in Iskenderun Steelmaking Industry were determined via indirect carbonation process. At first, the influences of acid concentration, liquid-to-solid (L/S) ratio, particle size, reaction time and temperature on the dissolution of Ca from steelmaking slag were investigated, respectively. We determined that all parameters had strong effects on the dissolution of Ca from steelmaking slag except for the reaction time. Also, the effects of Na/CH₃COO ratio, CO₂ flow rate, reaction temperature and time on the precipitation of Ca ions as PCC particles were investigated. The properties of PCC were determined using chemical, SEM, XRD and particle size analyses. Furthermore, non-reacted CO₂ left from the carbonation reactor was stored in the lab-scale gasometer tank for the re-use in that process.