A field study on serum vitellogenin levels in male Reeves' pond turtles (Chinemys reevesii) from estrogen-contaminated sites and a reference site

To ascertain whether wild male turtles were influenced by environmental estrogens, we examined serum vitellogenin (VTG) levels of male Reeves' pond turtles (Chinemys reevesii) collected from four study sites (A-D) in Kyoto, Japan. Sites A-C, which were impacted by domestic or industrial wastewater and effluents from sewage treatment plants, were chosen as contaminated sites, and site D was intended as a reference site. This contaminated/reference site characterization was confirmed by measuring estrogenic activities of the water samples collected at each site for over a year. Serum VTG levels in the turtles were quantified by an enzyme-linked immunosorbent assay established previously. Estrogenic activities of the water samples were measured using a previously validated yeast two-hybrid assay and expressed as the estradiol-17beta equivalent. Estrogenic activity was observed at high levels at sites A-C, but was almost undetected at site D throughout the sampling period: the mean and range were 0.74 (<0.07-2.1), 0.52 (0.17-1.6), 1.7 (<0.07-7.3), and 0.07 (<0.07-0.62) ng/l at sites A-D, respectively. Significant differences were found only in site D versus sites A, B, and C. Therefore, site D and sites A-C were confirmed to be a reference site and contaminated ones, respectively. Overall, 320 male turtles were captured and examined. The majority of the turtles showed normal VTG values (0.10-0.74 microg/ml). Although only five turtles from sites A-C showed unusually high VTG values (1.1-5.9 microg/ml, nearly one order of magnitude higher than normal values but much lower than values in adult females), there was no significant difference in the incidence of these high values between sites A-C and site D. Moreover, among the five turtles, one turtle was captured again 2 months later, but its VTG value dropped to the normal level. The unusually high VTG values may therefore be transient elevation caused by incidental and/or individually specific agents. Excluding the unusually high values, the mean serum VTG (accompanied with the range) was 0.22 (0.10-0.74), 0.27 (0.11-0.62), 0.27 (0.17-0.68), and 0.23 (0.10-0.57) microg/ml at sites A-D, respectively. There were no significant differences in the mean VTG values among sites A-D. Although it should be clarified how and why the unusually high VTG values occurred at sites A-C, our results suggested that wild male C. reevesii turtles would not be significantly affected by xenobiotic estrogens at environmentally relevant levels in terms of serum VTG elevation.     

Development of ductile green flame retardant poly(lactic acid) composites using hydromagnesite&huntite and bio-based plasticizer

Turning brittle poly(lactic acid) (PLA) to ductile form via plasticizer inclusion is an effective option in the case of processing with high amounts of additives. Additionally, the integration of natural flame retardants to PLA involving bio-based plasticizer enables to use of environmentally friendly composites in conditions where fire resistance performance is required. In the current study, ductile green fire retardant PLA composites were manufactured using hydromagnesite&huntite (HH) as a natural fire retardant additive and acetyl tributyl citrate as a bio-based plasticizer. The influences of plasticizer and HH contents on the fire retardant, thermal and mechanical performances of the composites were explored. According to test results, the limiting oxygen index (LOI) value of PLA reduced from 29.2 to 28.0 and the UL-94 V rating changed from V2 to BC with the addition of 20 wt% plasticizer owing to the reduction in melt viscosity. The peak heat release rate (pHRR) and average heat release rate (avHRR) values increased steadily as the concentration of plasticizer increased due to the formation of a more porous residue structure stemming from the increased transportation rate of gases. In order to produce ductile flame retardant material, the plasticizer content was required to 20 wt% of HH. The highest LOI value (36.2) and UL-94 rating of V0 were achieved with the inclusion of 70 wt% HH in the presence of 20 wt% plasticizer. Improvement in impact resistance and reduction in tensile strength were observed as the added amount of plasticizer increased.     

Dynamic modeling and fuzzy logic control of vibrations of a railway vehicle for different track irregularities

Safe and comfortable transportation of passengers and goods on railways can be achieved by solving the vibration problem. In this study, the dynamic modeling of the full railway vehicle is used to perform vibration analysis in order to observe displacements and accelerations. The full railway vehicle model consists of 54 degrees of freedom which are defined by differential equations. Additionally, wheel–rail contact problem (i.e. creepage factors and hertzian spring stiffness of rails) is analyzed by finite element method. Dynamic modeling and vibration analysis are carried out using Matlab–Simulink software. Using the developed model, the car body vibrations, caused by a lateral and two vertical sinusoidal track irregularities, are controlled by fuzzy logic controllers placed between the car body and bogies. The fuzzy logic algorithm herein is used for realizing the active control of car body vibrations. The simulations of vibration analysis are obtained in time and frequency domains and compared with passive controlled status. The robustness of the designed controller is verified by simulations, carried out for the cases of car body mass variations. The results show the effectiveness of the proposed algorithm.     

Effect of cathodic arc plasma treatment on the properties of WC–Co based hard metals

In this study, ion bombardment in a cathodic arc physical vapor deposition system was applied on WC–Co hard metal surfaces aiming to benefit from the diffusion acceleration effect, and to investigate the role of this effect on the surface composition, morphology and corrosion resistance of the materials. Chromium ions obtained via cathodic arc evaporation were accelerated under low (− 150 V) and high (− 1000 V) bias voltages in order to apply coating–bombardment cycles to sample surfaces. Substrate temperatures were measured by an optical pyrometer during the processes. The treated samples were characterized by scanning electron microscopy (SEM) and X-ray diffractometry (XRD). Temperature measurements showed that the sample temperature could be controlled precisely by adjusting the bias voltage. Temperatures in the range of 750–1200 °C were measured during the treatment depending on the duration of the high bias voltage cycles. XRD analysis showed η phase formation in the near surface regions of all treated samples. The amount of the formed η phase was shown to be dependent on the heating–cooling regime that varied with the applied mode of bias. The corrosion behavior of the samples was investigated by immersing treated and untreated samples in a solution of 5% H₃PO₄ containing 1 g/l Zn^{+ 2} for 24 h at 50 °C. The samples were investigated via SEM observations after immersion. Cathodic arc plasma treated samples showed a better resistance to corrosion in this environment.     

Effect of two ethnic processing technologies on reduction and composition of total and non-glucosidic cyanogens in cassava

The effectiveness of two different processing methods on reduction of total and non-glucosidic cyanogens in cassava was studied in two ethnic groups in Nkhota Kota, Malawi. Cassava cyanogen content was periodically monitored during processing. Total cyanogen reductions of 97.9 ± 0.5% and 82.4 ± 1.0% were obtained upon soaking peeled and unpeeled roots, respectively. The residual cyanogen content (2.6 ± 0.7 mg HCN eq./kg) in flour produced from peeled roots was lower than the FAO/WHO limit (10 mg HCN eq./kg). The flour from the unpeeled method contained twenty times more residual cyanogen levels (53.8 ± 1.8 mg HCN eq./kg dry matter). The peels exhibited four times higher cyanohydrin than the pulp. Inclusion of the peel during processing therefore leads to high retention of cyanogens in the pulp. Clearly, soaking of peeled roots is a more effective method and thus should be promoted among ethnic communities that soak unpeeled roots.     

Various approaches for constructing an ensemble of metamodels using local measures

Metamodels are approximate mathematical models used as surrogates for computationally expensive simulations. Since metamodels are widely used in design space exploration and optimization, there is growing interest in developing techniques to enhance their accuracy. It has been shown that the accuracy of metamodel predictions can be increased by combining individual metamodels in the form of an ensemble. Several efforts were focused on determining the contribution (or weight factor) of a metamodel in the ensemble using global error measures. In addition, prediction variance is also used as a local error measure to determine the weight factors. This paper investigates the efficiency of using local error measures, and also presents the use of the pointwise cross validation error as a local error measure as an alternative to using prediction variance. The effectiveness of ensemble models are tested on several problems with varying dimensionality: five mathematical benchmark problems, two structural mechanics problems and an automobile crash problem. It is found that the spatial ensemble models show better performances than the global ensemble for the low-dimensional problems, while the global ensemble is a more accurate model than the spatial ensembles for the high-dimensional problems. Ensembles based on pointwise cross validation error and prediction variance provide similar accuracy. The ensemble models based on local measures reduce cross validation errors drastically, but their performances are not that impressive in reducing the error evaluated at random test points, because the pointwise cross validation error is not a good surrogate for the error at a point.     

Stills,not full motion,for interactive spatial training: American,Turkish and Taiwanese female pre-service teachers learn spatial visualization

This study investigated how female elementary education pre-service teachers in the United States, Turkey and Taiwan learned spatial skills from structured activities involving discrete, as opposed to continuous, transformations in interactive computer programs, and how these activities transferred to non-related standardized tests of spatial visualization and mental rotation. The study used a pretest, intervention, posttest research design with experimental and comparison groups. The experimental group participated in transformational geometry visualization exercises, once a week for six weeks, for approximately 20 minutes each session. Instruments were standardized measures of spatial visualization and mental rotation; intervention activity worksheets directed the participants through 2D and 3D transformational geometry tasks in computer environments. For Turkish and Taiwanese participants, the experimental group improved significantly more than the control group in spatial visualization, while the American participants showed no such significant improvement.