Developmental changes in the histological structure of the testes, and testosterone profiles in male guinea fowls (Numida meleagris)

Owing to the paucity of information on the reproductive biology of guinea fowls, a study involving a total of 66 males was conducted, and documented the developmental changes in histological structure of the testes of guinea cocks from hatching until adulthood. Changes in testosterone synthesis during sexual development were also determined. Age-related changes were analysed using univariate analysis for completely randomised design and means separated using Tukey's test/Kruskal-Wallis test and medians separated by Mann-Whitney U test. Total germ cell population per testis and testicular histological morphometric parameters increased significantly (p < 0.0001) from 12 weeks of age (WOA), and stabilized between 20 and 24 WOA. Peripheral testosterone concentrations increased gradually from 4 WOA, and peaked at 20 WOA. Correlations among all the testicular morphometric parameters were positive and highly significant (p < 0.01). Similarly, significant (p < 0.05) positive correlations existed between testicular weight and testicular sperm production, tubular diameter, Sertoli cell population, tubular length and peripheral testosterone concentration. Testicular sperm production was positively correlated with meiotic index (p < 0.01) and round spermatids population (p < 0.05). The correlations between peripheral testosterone concentrations, tubular diameter and Sertoli efficiency were also significant (p < 0.05) and positive. Testicular morphometric parameters stabilized between 20 and 24 WOA, while peripheral testosterone concentrations showed two patterns of secretion, initial and final phases of increasing and decreasing testosterone secretions, respectively, and may be implicated in the development of histological structures of the testes and spermatogenesis. [Abstract copyright: Copyright © 2017 Elsevier Inc. All rights reserved.

Dehydration-Induced Loss of Corrosion Protection Properties in Chromate Conversion Coatings on Aluminum Alloy 2024-T3

It is well known that chromate conversion coatings (CCCs) exhibit a prompt loss in corrosion resistance when exposed to moderately elevated temperatures (60-100°C). They also suffer a gradual loss in corrosion resistance due to ambient temperature exposure. To better understand the origins of losses in corrosion resistance, CCCs were formed on 99.99% Al, 1100 Al [Al-1.0(Fe, Si, Cu)], and 2024-T3 (Al-4.4Cu-1.5Mg-0.6Mn), exposed to elevated and ambient temperature exposures for various lengths of time, and characterized using several different methods. The Cr(VI):total Cr ratio in CCCs was estimated by analysis of data derived from X-ray absorption spectroscopy. Corrosion resistance was measured by electrochemical impedance spectroscopy. The evolution of shrinkage cracking was examined by environmental scanning electron microscopy. Cr(VI) leaching experiments were also carried out to characterize the effect of thermal exposure on Cr(VI) release. Thermal analysis and X-ray diffraction were conducted to characterize the temperature-dependent changes in CCCs. Results show that CCCs degrade in several distinct steps over the temperature range of 20 to 500°C. Our findings support the longstanding notion that dehydration is the root cause for losses in corrosion resistance due to aging at ambient and low temperatures (<150°C). Extended X-ray fine structure measurements indicate a shortening in Cr(III)-Cr(III) nearest neighbor distances upon dehydration. This is interpreted as a consolidation in the Cr(OH)_3 backbone of the CCC which leads to shrinkage cracking and immobilization of Cr(VI). This finding is important because it links older observations of the effects of aging and heating on CCCs to newer interpretations of CCC formation based on inorganic polymerization. Overall, these results reveal CCCs to be highly dynamic coatings with corrosion resistance properties that vary considerably in both the short term and long term

Formation of Chromate Conversion Coatings on Aluminum and Its Alloys

In situ X-ray adsorption near-edge structure (XANES) has been used to investigate the formation of chromate conversion coatings on pure Al, commercial Al alloys (AA 1100, AA2024, and AA7075), and a series of binary Al–Cu alloys. The method employed cells designed to determine the growth of the total chromium [Cr(total)] and hexavalent chromate [Cr(VI)] in the chromate conversion coating (CCC) as a function of exposure time to a chromate solution. Three sets of data were obtained, where (i) the Al was exposed to only a limited amount of solution; (ii) the chromate solution was excluded after short periods of repeated exposures to the solution; and (iii) the Al was exposed continuously to the chromate solution. All the results showed a very rapid initial growth within the first seconds, followed by a continued increase in thickness for exposures up to 1 h. Measurements with Al–Cu binary alloys demonstrated that the difference observed in AA2024 and AA1100 may not be due to Cu alloying. The proportion of Cr(VI) in the coatings becomes approximately constant after 180 s of exposure for all the specimens examined, even though the coatings continued to grow

Deployment characterization of a floatable tidal energy converter on a tidal channel, Ria Formosa, Portugal

This paper presents the results of a pilot experiment with an existing tidal energy converter (TEC), Evopod 1 kW floatable prototype, in a real test case scenario (Faro Channel, Ria Formosa, Portugal). A baseline marine geophysical, hydrodynamic and ecological study based on the experience collected on the test site is presented. The collected data was used to validate a hydro-morphodynamic model, allowing the selection of the installation area based on both operational and environmental constraints. Operational results related to the description of power generation capacity, energy capture area and proportion of energy flux are presented and discussed, including the failures occurring during the experimental setup. The data is now available to the scientific community and to TEC industry developers, enhancing the operational knowledge of TEC technology concerning efficiency, environmental effects, and interactions (i.e. device/environment). The results can be used by developers on the licensing process, on overcoming the commercial deployment barriers, on offering extra assurance and confidence to investors, who traditionally have seen environmental concerns as a barrier, and on providing the foundations whereupon similar deployment areas can be considered around the world for marine tidal energy extraction.Acknowledgements The paper is a contribution to the SCORE project, funded by the Portuguese Foundation for Science and Technology (FCT e PTDC/ AAG-TEC/1710/2014). Andre Pacheco was supported by the Portu- guese Foundation for Science and Technology under the Portuguese Researchers' Programme 2014 entitled “Exploring new concepts for extracting energy from tides” (IF/00286/2014/CP1234). Eduardo GGorbena has received funding for the OpTiCA project from the ~ Marie Skłodowska-Curie Actions of the European Union's H2020- MSCA-IF-EF-RI-2016/under REA grant agreement n [748747]. The authors would like to thank to the Portuguese Maritime Authorities and Sofareia SA for their help on the deployment.info:eu-repo/semantics/publishedVersio

The Effect of Control Strategy on Tidal Stream Turbine Performance in Laboratory and Field Experiments

The first aim of the research presented here is to examine the effect of turbine control by comparing a passive open-loop control strategy with a constant rotational speed proportional–integral–derivative (PID) feedback loop control applied to the same experimental turbine. The second aim is to evaluate the effect of unsteady inflow on turbine performance by comparing results from a towing-tank, in the absence of turbulence, with results from the identical machine in a tidal test site. The results will also inform the reader of: (i) the challenges of testing tidal turbines in unsteady tidal flow conditions in comparison to the controlled laboratory environment; (ii) calibration of acoustic Doppler flow measurement instruments; (iii) characterising the inflow to a turbine and identifying the uncertainties from unsteady inflow conditions by adaptation of the International Electrotechnical Commission technical specification (IEC TS): 62600-200. The research shows that maintaining a constant rotational speed with a control strategy yields a 13.7% higher peak power performance curve in the unsteady flow environment, in comparison to an open-loop control strategy. The research also shows an 8.0% higher peak power performance in the lab compared to the field, demonstrating the effect of unsteady flow conditions on power performance. The research highlights the importance of a tidal turbines control strategy when designing experiments

5 year retrospective follow-up of new cases of Charcot neuroarthropathy - A single centre experience

Background: Few data describe the natural history of Charcot neuroarthropathy treated with a total contact plaster cast (TCC). Methods: A 5 year retrospective analysis of 50 patients presenting with an acute CN, Assessing time to clinical resolution into appropriate footwear and assessing if initial immobilisation device influenced resolution time. Results: During the study period 42 patients (84%) of patients went into remission, 2 died during their treatment, 4 had major amputations, in 2 patients treatment was ongoing. 36 patients were treated with combination offloading devices, 6 were treated with one modality only. Median time to resolution for patients initially treated with a TCC was not significantly shorter than for those treated with a removable below knee boot. 34.9% required re-casting due to clinical deterioration in the removable device. Conclusions: More precise measures of resolution of CN are needed to assess the impact of initial treatment modality on time to resolution

Increased osteoclastic activity in acute Charcot’s osteoarthopathy: the role of receptor activator of nuclear factor-kappaB ligand

Aims/hypothesis Our aims were to compare osteoclastic activity between patients with acute Charcot’s osteoarthropathy and diabetic and healthy controls, and to determine the effect of the receptor activator of nuclear factor-kappaB ligand (RANKL) and its decoy receptor osteoprotegerin (OPG). Methods Peripheral blood monocytes isolated from nine diabetic Charcot patients, eight diabetic control and eight healthy control participants were cultured in the presence of macrophage-colony stimulating factor (M-CSF) alone, M-CSF and RANKL, and also M-CSF and RANKL with excess concentrations of OPG. Osteoclast formation was assessed by expression of tartrate-resistant acid phosphatase on glass coverslips and resorption on dentine slices. Results In cultures with M-CSF, there was a significant increase in osteoclast formation in Charcot patients compared with healthy and diabetic control participants (p = 0.008). A significant increase in bone resorption was also seen in the former, compared with healthy and diabetic control participants (p &lt; 0.0001). The addition of RANKL to the cultures with M-CSF led to marked increase in osteoclastic resorption in Charcot (from 0.264 ± 0.06% to 41.6 ± 8.1%, p &lt; 0.0001) and diabetic control (0.000 ± 0.00% to 14.2 ± 16.5%, p &lt; 0.0001) patients, and also in healthy control participants (0.004 ± 0.01% to 10.5 ± 1.9%, p &lt; 0.0001). Although the addition of OPG to cultures with M-CSF and RANKL led to a marked reduction of resorption in Charcot patients (41.6 ± 8.1% to 5.9 ± 2.4%, p = 0.001), this suppression was not as complete as in diabetic control patients (14.2 ± 16.5% to 0.45 ± 0.31%, p = 0.001) and in healthy control participants (from 10.5 ± 1.9% to 0.00 ± 0.00%, p &lt; 0.0001). Conclusions/interpretation These results indicate that RANKL-mediated osteoclastic resorption occurs in acute Charcot’s osteoarthropathy. However, the incomplete inhibition of RANKL after addition of OPG also suggests the existence of a RANKL-independent pathway

Experimental evaluation of the wake characteristics of cross flow turbine arrays

One key factor in the exploitation of tidal energy is the study of interactions of turbines when working in tidal turbine farms. The Momentum Reversal and Lift (MRL) turbine is a novel cross flow turbine. The three blades rotate around a common central horizontal axis which is parallel to their own axis and perpendicular to the flow. The novelty of the MRL turbine is that it relies on the combination of both lift and momentum reversal (drag) for energy extraction. Scaled MRL turbine models of 0.164 m in diameter were used to characterise the flow in three different tidal array settings. Detailed maps of axial velocity profiles and velocity deficits downstream of the turbine are presented, enabling the visualisation of characteristic flow patterns. The results show that the MRL generates lower velocity deficits and turbulence intensities in the near wake than those associated with horizontal axis turbines. The downstream wake was not completely symmetrical which was related to the geometry of the device but also due to the flow developed in the flume. Amongst the three array configurations studied, a fence of turbines with the lowest separation provided the highest power output