Comparative typing of <Emphasis Type="Italic">L. delbrueckii</Emphasis> subsp<Emphasis Type="Italic">. bulgaricus</Emphasis> strains using multilocus sequence typing and RAPD–PCR

Comparative typing analysis of 25 Lactobacillus delbrueckii subsp. bulgaricus strains, isolated from traditional yoghurts in Turkey, was performed by RAPD–PCR (randomly amplified polymorphic DNA–PCR) and MLST (multilocus sequence typing). RAPD–PCR analyses were performed using two primers; M13 and 1254. Primer 1254 produced better results than primer M13. The bands produced by primer 1254 were brighter and easier to interpret, and a higher number of bands were produced. In addition, clusters produced by primer 1254 were grouped according to the source of isolation. MLST analysis was performed using three genes, β-gal, pheS and rpoA, and isolates were successfully characterized at strain level. To our knowledge, MLST analyses were used for the first time for strain level discrimination in L. delbrueckii subsp. bulgaricus. It enabled a detailed understanding of L. delbrueckii subsp. bulgaricus strains by using allele and sequence types’ analysis. Both MLST and RAPD allowed for the typing of clusters according to the isolation source, while RAPD provided an increased differentiation. However, by increasing the number of genes analyzed, the discriminatory power of MLST could be increased.     

Head tracked retroreflecting 3D display

In this paper, we describe a single‐user glasses‐free (autostereoscopic) 3D display where images from a pair of picoprojectors are projected on to a retroreflecting screen. Real images of the projector lenses formed at the viewer's eyes produce exit pupils that follow the eye positions by the projectors moving laterally under the control of a head tracker. This provides the viewer with a comfortable degree of head movement. The retroreflecting screen, display hardware, infrared head tracker, and means of stabilizing the image position on the screen are explained. The performance of the display in terms of crosstalk, resolution, image distortion, and other parameters is described. Finally, applications of this display type are suggested.     

Application of response surface methodology and artificial neural network on pyrolysis of safflower seed press cake

In this study, mathematical correlation between the process variables and product yields for pyrolysis of safflower seed press cake (SPC) in fixed-bed reactor was investigated by using the response surface methodology (RSM) and artificial neural networks (ANNs). The RSM results showed that the second-order response model can be used to describe the relationship between the various factors and the response. Several feed-forward fully connected neural networks were investigated and optimal configuration of the ANN model was obtained. The results revealed that the ANN model could be considered as an alternative to RSM and practical modeling technique for the pyrolysis product yields.     

Seasonal variation in drinking water concentrations of disinfection by-products in IZMIR and associated human health risks

Seasonal variation in concentrations of two different disinfection by-product groups, trihalomethanes (THMs) and haloacetonitriles (HANs), was investigated in tap water samples collected from five sampling points (one groundwater and four surface water sources) in Izmir, Turkey. Estimates of previously published carcinogenic and non-carcinogenic risks through oral exposure to THMs were re-evaluated using a probabilistic approach that took the seasonal concentration variation into account. Chloroform, bromoform, dibromochloromethane and dichloroacetonitrile were the most frequently detected compounds. Among these, chloroform was detected with the highest concentrations ranging from 0.03 to 98.4 microg/L. In tap water, at the groundwater supplied sampling point, brominated species, bromoform and dibromoacetonitrile, were detected at the highest levels most probably due to bromide ion intrusion from seawater. The highest total THM and total HAN concentrations were detected in spring while the lowest in summer and fall. The annual average total THM concentration measured at one of the surface water supplied sampling points exceeded the USEPA's limit of 80 microg/L. While all non-carcinogenic risks due to exposure to THMs in Izmir drinking water were negligible, carcinogenic risk levels associated with bromodichloromethane and dibromochloromethane were higher than one in million.     

Monodisperse palladium nanoparticles assembled on graphene oxide with the high catalytic activity and reusability in the dehydrogenation of dimethylamine-borane

Highly effective and stable palladium nanoparticles (Pd NPs) supported on graphene oxide (GO) were synthesized, characterized and applied for dehydrogenation of dimethylamine-borane (DMAB). Monodisperse Pd NPs were synthesized with the ultrasonic reduction method in the presence of oleylamine and GO as support matrices at room temperature. Almost uniformly distributed Pd (0) nanoparticles in size of 3.89 nm were isolated in a reproducible manner by filtering through the reaction mixture. They were characterized by TEM, HRTEM, XRD, Raman, and XPS. It was found that Pd@GO NPs are stable and one of the most active catalysts in the dehydrogenation of DMAB. This catalyst with its turnover frequency of 38.02 h^?1 exhibits one of the good results among all the catalysts prepared in the literature for dehydrogeneration of DMAB. Significant activation parameters of the catalytic dehydrogenation reaction were also calculated, and the activation enthalpy (ΔH^#), activation entropy (ΔS^#) and the apparent activation energy (Ea) were found 16.5 kJ mol^?1, ?179 J mol^?1 K^?1, and 18.6 kJ mol^?1, respectively.     

Comparison of the internet usage levels amongst final year students of faculty of medicine and health colleges in Turkey: According to the gender variable

The use of internet is becoming widespread all over the world including the health sector. Internet has been increasing its importance for individuals in the health sector for purposes of increasing speed and efficiency of surgeries, sharing patients’ data, storing information in the database. The aim of this study is to examine the relationship between a group of medicine faculty and health college students’ level of internet use and their views about the internet with regard to their gender. The final year students of the faculty of medicine and health college at F?rat University constituted the sample of the research. Of 219 final year students, 155 students who were present when the research was conducted constituted the sample of this study. A Likert type questionnaire was used to determine students’ level of internet use. The questionnaire was developed previously by the researcher and the test of its reliability and validity was performed. The study reveals that 14.8% of the students use internet for 2 h or more in a week and 72.9% of students do not use internet in weekdays at all. The findings also showed that 76.1% of the students know the concept of ‘internet’ for more than four years, and 61.9% of the students access to internet from the internet cafes, 48.4% of the students use internet for academic purposes and 63.9% of the students want to set up their web pages on the internet. In the light of research findings, it is thought that internet-based and interactive lesson applications are inevitable education tools for education faculties of medicine and health colleges in the future. According to the findings, female students seem to log into internet less but stay connected more, and students mostly prefer to use internet cafes for internet access. In these cafes, internet is used mainly for academic purposes. It is expected that this study will provide some educational implications that enable effective use of internet in health education and a cooperative learning environment that would allow male and female students to study collaboratively.     

Effect of R600a on tribological behavior of sintered steel under starved lubrication

This paper describes the impact of the isobutane refrigerant on the wear performance of tribopairs at hermetic compressor bearings. The tribological behavior of 100Cr6 steel pin is investigated under starved lubrication condition in air and R600a environments when running against sintered steel which was treated with and without steam. EDS and SEM are carried out on pin and plate samples after wear tests. The results indicate that wear durability is lower for the tests with R600a than those with air. The adverse effect of R600a on wear rate is linked to the change in the viscosity and foaming characteristics of the oil in the presence of R600a as well as the lack of oxides.     

PP纳米复合长丝的结构和电性能

采用小型熔融纺丝机将PP／碳纳米粒子纺成三叶形截面的长丝。然后将此PP／碳纳米粒子复合长丝和纯PP长丝采用就地聚合的方法涂以导电聚合物聚苯胺制成导电长丝．结果表明,涂层长丝的电阻逐渐降低。为降低电阻水平而仍保持结构和机械性能,还需进行进一步的工作。     

Determination of metal contaminations in sea foods from Marmara,Aegean and Mediterranean seas: Twelve fish species

The concentrations of cadmium, cobalt, chromium, copper, iron, manganese, nickel, lead and zinc were determined by ICP-AES in muscles and livers of 12 fish species sampled from the Marmara, Aegean and Mediterranean seas of Turkey. Iron showed the highest levels in examined tissues of all fish species. Following Fe, Zn generally showed the second highest levels. Metal concentrations in edible parts of fish species were 0.02–0.37 mg kg⁻¹ for cadmium, 0.04–0.41 mg kg⁻¹ for cobalt, 0.04–1.75 mg kg⁻¹ for chromium, 0.32–6.48  mg kg⁻¹ for copper, 7.46–40.1 mg kg⁻¹ for iron, 0.10–0.99  mg kg⁻¹ for manganese, 0.02–3.97 mg kg⁻¹ for nickel, 0.33–0.86 mg kg⁻¹ for lead, 4.49–11.2 mg kg⁻¹ for zinc, respectively. All metal concentrations in livers were higher than those in muscles. In some stations, cadmium and chromium concentrations in both muscles and livers, and lead levels in livers of the examined species were higher than permissible safety levels for human uses.     

Purification and Characterization of Polyphenol Oxidase from Akko XIII Loquat (Eriobotrya japonica cv Akko XIII)

Akko XIII is an important loquat variety grown in Turkey. As with many fruits and vegetables, enzymatic browning catalyzed by polyphenol oxidase (PPO) also occurs in loquats. PPO from Akko XIII loquat was extracted and purified through (NH₄)₂SO₄ precipitation, dialysis and ion exchange chromatography. The enzyme showed several peaks with PPO activity on DEAE-Toyopearl 650 M column, of which only two (isoenzyme A and isoenzyme B) were characterized. Assay of activity of the isoenzymes between pH 3.04 and 7.80 using catechol as substrate showed two activity peaks, one at acidic pH and the other at neutral pH. pH optima of isoenzyme A and B were found to be at 7.4 and 4.98, respectively. The Km values of isoenzyme A and B using catechol as substrate were found to be 152.3 mM and 5.4 mM, respectively. They both displayed maximal activity at 30^oC. The two isoenzymes displayed different heat resistance and sensitivity towards various inhibitors.