412 research outputs found
Comparison of muscular tissue concentration of heavy metals in Sharpnose stinger (Himantura gerrardi) and Bigeye scade (Selar crumenophthalmus) of the Persian Gulf
We assessed concentration of heavy metals (Cu, Fe, Hg and Zn) in the muscular tissue of benthic species Himantura gerrardi and pelagic species Selar crumenophthalmus caught from the Persian Gulf during winter 2008. After biometrical measurements, the muscle tissues of 51 randomly selected samples were separated from 86 stations. Specimens were digested using the wet method and the concentrations of Cu, Fe and Zn were determined using Atomic Absorption Spectrophotometer (flame method) and also concentration of mercury was determined using Mercury Analyzer device. The mean concentration of heavy metals in muscle tissues of Himantura gerrardi were as follows: Fe: 74.78; Hg: 0.77; Zn: 875.99 and Cu: 3.5. However, these values for muscle tissues of Selar crumenophthalmus were: Fe: 25.07; Hg: 0.20; Cu: Zn: 15.54 and Zn: 2.31kg/g dry weight. Results showed that concentration of the selected heavy metals in H. gerrardi, were significantly higher than Selar crumenophthalmus (P <0.05)
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Mechanisms of airfoil noise near stall conditions
The focus of this paper is on investigating the noise produced by an airfoil at high angles of attack over a range of Reynolds number
Re≈2×10⁵–4×10⁵. The objective is not modeling this source of noise but rather understanding the mechanisms of generation for surface pressure fluctuations, due to a separated boundary layer, that are then scattered by the trailing edge. To this aim, we use simultaneous noise and surface pressure measurement in addition to velocimetric measurements by means of hot wire anemometry and time-resolved particle image velocimetry. Three possible mechanisms for the so-called “separation-stall noise” have been identified in addition to a clear link between far-field noise, surface pressure, and velocity fields in the noise generation
Corn Stover Availability and Collection Efficiency Using Typical Hay Equipment
Corn stover has been identified as a potential feedstock for the production of fermentable sugars and thermochemical processes. The availability and efficiency of typical hay equipment for collecting corn stover has not been well quantified. Corn stover was collected for two years on a central Kentucky farm near Louisville. Six different harvesting treatments, using traditional hay equipment, were used to harvest corn stover. A rotary mower, rotary scythe (flail-type mower with windrow-forming shields), parallel bar rake, and a round baler were utilized. The average stover moisture content prior to grain harvest was above 40%, and field drying was required before baling. All treatments were analyzed for collection efficiency and corn stover yield. The stover collection yields varied from 1.93 to 5.34 dry t/ha, with collection efficiencies (ratio of stover collected to the total above-ground stover excluding grain) between 32.1% and 94.5%. The most promising collection strategy was disengaging the straw chopper and spreader to produce a windrow behind the combine. This windrow could then be baled in a separate operation that resulted in a collection efficiency of 74.1%
Comparison of prevalence of metabolic syndrome between idiopathic and secondary deep vein thrombosis
Background- The association of the metabolic syndrome with idiopathic or secondary deep vein thrombosis (DVT) remains uncertain. In addition, the relevance of the different features of the metabolic syndrome as an independent or pivotal risk factor for DVT is controversial. We aimed to evaluate the prevalence of the metabolic syndrome in patients with idiopathic or secondary DVT and also compare the prevalence of the different components of this syndrome in the two clinical etiological conditions of DVT. Methods- In a cross-sectional study, 115 consecutive patients with a recent objective diagnosis of DVT (idiopathic in 87 patients and secondary to a known risk factor in 28 patients) who were referred to Rajaei Heart Center between April 2009 and January 2010 were enrolled in the study. In all the patients, DVT was diagnosed by means of compression Doppler ultrasonography. The metabolic syndrome was defined according to the ATP III recommendations. Results- Overall prevalence of the metabolic syndrome in the study participants was 9.6, and the prevalence of the metabolic syndrome in patients with idiopathic or secondary DVT was 9.2 and 10.7, respectively, which was not different between them. Relative to the presence of the different numbers of the metabolic syndrome features, no difference was found between the groups with idiopathic or secondary DVT. The presence of no feature was found in 6.9 and 7.1, the presence of one feature was seen in 51.7 and 42.9, and the presence of two features was found in 32.2 and 39.3, respectively. Conclusion- Regardless of the etiology of DVT, the overall prevalence of the metabolic syndrome in our DVT subjects ranged from 9.2 to 10.7, and this prevalence was independent of the etiology (idiopathic or secondary) of DVT
The Effects of Different Concentrations and Combinations of Growth Regulators on the Callus Formation of Potato (Solanum tubrosum) Explants
Abstract: The main objective of the present study was to investigate the effects of different concentrations of plant growth regulators and their combinations on callus induction of potato (Solanum tuberosum L.). The explants of potato tuber were cultured on Modified Murashige and Skoog medium which was supplemented with different concentrations of 2,4-Dichlorophenoxy acetic acid (2,4-D), "-naphthalene Acetic Acid (NAA), Benzyl Adenine (BA), 2,4-D in combinations with BA and NAA in combination with BA for callus induction. The Concentration of sucrose was 3% W/V level and the pH of the media was adjusted to 5.7 before the addition of agar 8% W/V. The explants were first dissected out aseptically and then inoculated to the media (with various levels of hormones), then incubated at 27±2ºC in the culture room. Among the treatments 2, 4-D at different concentrations produced different degree of callus but comparatively a massive amount of callus was formed on MS medium supplemented with 2, 4-D alone at 3.0 mg/L. Also NAA and BA with different concentrations produced considerable degrees of callus but the degree of callus was best at higher concentrations of NAA and BA. 2, 4-D in combination with BA at 2.0 mg/L both produced considerable amount of callus. In case of NAA in combination with BA the degree of callus formation was best at concentration 1.0 mg/L each. So according to the above findings it was concluded that 2, 4-D is the best option for induction of callus among the other hormones used in the study
Convergence results for cyclic-orbital contraction in a more generalized setting with application
In the realm of double-controlled metric-type spaces, we investigated obtaining fixed points using the application of cyclic orbital contractive conditions. Diverging from conventional approaches utilized in standard metric spaces, our technique took a unique route due to the unique features of our structure. We demonstrated the significance of our outcomes through exemplary cases, clarifying the breadth of our results through comprehensive investigations. Significantly, our work not only improved and broadened earlier findings in the literature, but also offered unique notions that were discussed in our explanatory notes. Towards the end of our inquiry, we used insights obtained from previous discoveries to develop a second-order differential equation. This equation was an effective tool for dealing with the second class of Fredholm integral problems. In conclusion, this investigation extended our examination of double-controlled metric type spaces by providing new insights on fixed point theory, expanding on prior debates and building a substantial road towards solving a class of integral equations
First-principles modeling of the polycyclic aromatic hydrocarbons reduction
Density functional theory modelling of the reduction of realistic
nanographene molecules (C42H18, C48H18 and C60H24) by molecular hydrogen
evidences for the presence of limits in the hydrogenation process. These limits
caused the contentions between three-fold symmetry of polycyclic aromatic
hydrocarbon molecules and two-fold symmetry of adsorbed hydrogen pairs.
Increase of the binding energy between nanographenes during reduction is also
discussed as possible cause of the experimentally observed limited
hydrogenation of studied nanographenes.Comment: 18 pages, 7 figures, accepted to J. Phys. Chem.
Intensive Care Unit Admission Parameters Improve the Accuracy of Operative Mortality Predictive Models in Cardiac Surgery
BACKGROUND: Operative mortality risk in cardiac surgery is usually assessed using preoperative risk models. However, intraoperative factors may change the risk profile of the patients, and parameters at the admission in the intensive care unit may be relevant in determining the operative mortality. This study investigates the association between a number of parameters at the admission in the intensive care unit and the operative mortality, and verifies the hypothesis that including these parameters into the preoperative risk models may increase the accuracy of prediction of the operative mortality. METHODOLOGY: 929 adult patients who underwent cardiac surgery were admitted to the study. The preoperative risk profile was assessed using the logistic EuroSCORE and the ACEF score. A number of parameters recorded at the admission in the intensive care unit were explored for univariate and multivariable association with the operative mortality. PRINCIPAL FINDINGS: A heart rate higher than 120 beats per minute and a blood lactate value higher than 4 mmol/L at the admission in the intensive care unit were independent predictors of operative mortality, with odds ratio of 6.7 and 13.4 respectively. Including these parameters into the logistic EuroSCORE and the ACEF score increased their accuracy (area under the curve 0.85 to 0.88 for the logistic EuroSCORE and 0.81 to 0.86 for the ACEF score). CONCLUSIONS: A double-stage assessment of operative mortality risk provides a higher accuracy of the prediction. Elevated blood lactates and tachycardia reflect a condition of inadequate cardiac output. Their inclusion in the assessment of the severity of the clinical conditions after cardiac surgery may offer a useful tool to introduce more sophisticated hemodynamic monitoring techniques. Comparison between the predicted operative mortality risk before and after the operation may offer an assessment of the operative performance
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Optimization of leading-edge undulation of a NACA 65(12)-10 aerofoil for noise reduction and aerodynamic enhancement
Leading-edge undulations or tubercles of humpback whale flippers have been known as one of biomimetic technologies adaptable to flow control of aerofoils, particularly at post stall conditions. These leading-edge undulations are also known to reduce noise resulting from an interaction with on-coming turbulence. We have recently carried out a parametric study of a NACA 65(12)-10 aerofoil with a view to optimise the amplitude and the wavelength of leading-edge undulations for noise reduction and aerodynamic enhancement. A 3x3 test matrix composing of three amplitudes (h = 3%, 6% and 12% chord) and three wavelengths (? = 10%, 20% and 30% chord) was used in the investigation, where lift, drag and noise were measured at the Reynolds number of 105. In this test, a turbulence-generating grid was installed at the inlet of the test section to increase the turbulence level in the freestream and to promote transition to turbulence near the leading edge of aerofoils without a need for a trip device. Within the test matrix considered, we found that the best improvement in CL,max is given with the greatest wavelength and amplitude, whereas the maximum noise reduction is obtained with the small wavelength and the large amplitude
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