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151.
The actions of exogenous arachidonic acid on the performance of the isolated and perfused systemic heart of Octopus vulgaris (collected in the Bay of Naples in 1992), and the potential of this heart for eicosanoid synthesis are described. Arachidonic acid induces positive chronotropic and inotropic effects. The positive inotropic effect is apparent only at the lowest concentration used (10–7
M) and in the paced heart preparations, in which a negative relationship between stroke volume and heart rate has been demonstrated. Using 10–5
M arachidonate, which induces the greatest chronotropic effect, a reduction of inotropism is evident which is due to the above negative relationship between stroke volume and heart rate. These effects are scarcely affected by the cyclooxygenase and lipoxygenase inhibitors, indomethacin (IM) and nordihydroguaiaretic acid (NDGA), respectively. On the coronary system of this heart arachidonic acid displays a potent vasoconstrictory action (ca. 100 percent increase of coronary resistance). This effect is potentiated by IM and reduced by NDGA. 14C-arachidonate is metabolized by the octopus ventricle homogenate into the lipoxygenase products (assayed as hydroxy acids) more actively than into cyclooxygenase products (prostanoids: PGE2, PGD2, PGF2 and 6-keto-PGF1). On the other hand, the Ca-ionophore A23187 enhances the production of cyclooxygenase metabolites much more than of lipoxygenase metabolites. 相似文献
152.
In this paper we propose a robust algorithm to evaluate solute transport in open-channel networks with transient storage under
an unsteady flow regime. In the proposed approach, through the integration of junction equations into the model and solving
them explicitly, the analysis of solute transport problems in open-channel networks is simplified significantly. Furthermore,
when coupled with a transient hydrodynamic open-channel network model for flow simulation, the proposed model can be utilized
in the solution of solute transport problems under unsteady flow regimes. In the proposed model, the governing equations are
written in a conservative form and are solved using a fractional-step algorithm, which is based on a relaxation and central
difference scheme. The proposed algorithm is robust and accurate even for advection dominant cases. A pure advection with
discontinuities, a field application and solute transport in an open-channel network in an unsteady flow regime are included,
to demonstrate the performance of the proposed algorithm. 相似文献
153.
Concentrations and gas/particle partitioning of PCBs in Chicago 总被引:8,自引:0,他引:8
Tasdemir Y Vardar N Odabasi M Holsen TM 《Environmental pollution (Barking, Essex : 1987)》2004,131(1):35-44
Thirty seven air samples were collected in Chicago, IL from June to October 1995 and analyzed for gas and particle concentrations of polychlorinated biphenyls (PCBs). Lower molecular weight (MW) PCBs dominated the samples and on average 95% of the Sigma50PCB concentration (gas+particulate) was in the vapor phase. Sigma50PCB concentrations were classified based on prevailing winds (lake and land). The Sigma50PCB concentration varied between 0.42 and 5.21 ng/m3 (1.80+/-1.70 ng/m3) for lake and 0.53 and 8.31 ng/m3 (2.41+/-2.15 ng/m3) for land wind directions. Back trajectory analyses suggested that SW of Chicago can be an important local or regional source sector for PCBs. Partitioning between gas and particulate phases was modeled using the Junge-Pankow model. The measured particle phase concentrations for low MW PCBs were lower than those predicted by the model while the opposite was observed for high MW PCBs. Plots of gas/particle partition coefficient (log Kp) vs. subcooled liquid vapor pressure (log pL(0)) had reasonable correlations for individual samples but the slope varied among the samples. Samples that originated from over the lake had higher slopes than samples that originated from over the land. 相似文献
154.
Shahabuddin Memon Ezgi Akceylan Begum Sap Mustafa Tabakci D. Max Roundhill Mustafa Yilmaz 《Journal of Polymers and the Environment》2003,11(2):67-74
Three newly synthesized polymer supported calix[4]arene ionophores (7–9) were synthesized, and their ion binding properties toward selected alkali (Li+, Na+, K+, Cs+) and transition metal (Hg2+, Ni2+, Cu2+, Co2+, Cd2+, and Pb2+) cations were investigated. It has been observed that these ionophores are not selective toward a particular metal cation but show better ion binding property as compared to monomeric calixarene derivatives (2 and 6). Ionophore 6 and its supported polymer were also employed in dichromate anion extraction experiments. The polymeric ionophore (9) was found an effective extractant for dichromate anion even at pH 7. 相似文献
155.
Ahmet Aygün Mustafa Kemal Uslu Süleyman Polat 《Journal of Polymers and the Environment》2017,25(4):1163-1174
Firstly, foam trays were produced from glyoxal cross-linked wheat, potato and corn starches and their mixtures. The most suitable starch type for starch-based foam tray production was selected according to the level of water absorption, density, surface and cross-section micrographs of the foam trays. It was decided that a wheat and potato starch blend was the most suitable starch source for producing the foam trays because they have the lowest water absorption percentage (25.5 ± 0.7%), low density (0.17 ± 0.01 g/cm3) and a smooth surface. Potato–wheat starch foam trays with fibres were produced by adding wheat and wood fibres. Unlike wood fibres addition, wheat fibres significantly decreased the percentage of water absorption (16.63 ± 1.2%) and density (0.115 ± 0.013 g/cm3) of the tray. Also, the trays including wheat fibre had a lighter colour than the wheat–potato starch tray. To further reduce water absorption of the tray, the trays were made by adding two different types of lipids (beeswax or shortening and three different types of filler materials—kaolin, montmorillonite or zinc oxide nanoparticles). According to the level of water absorption of the trays, it was decided that shortening and zinc oxide nanoparticles, in addition to kaolin, were respectively the most suitable lipid and filler materials. The foam trays were produced by adding these supplementary materials. The addition of shortening slightly, zinc oxide nanoparticles moderately and kaolin greatly increased the density of the wheat potato starch tray including fibre. However, the percent of water absorption of the trays containing wheat fibre + shortening or wheat fibre + shortening + zinc oxide nanoparticles decreased 6.4 ± 0.01 and 5.9 ± 0.3%, respectively. 相似文献
156.
This study investigated the ability of fungi isolated from highly contaminated soil to biodegrade polycyclic aromatic hydrocarbon (PAH) compounds, as well as the effect of several parameters on the biodegradation ability of these fungi. The isolated fungi were identified using ITS rDNA sequencing and tested using 2,6‐dichlorophinolendophenol to determine their preliminary ability to degrade crude oil. The top‐performing fungi, Aspergillus flavus and Aspergillus fumigatus, were selected to test their ability to biodegrade PAH compounds as single isolates. After 15 days of incubation, A. flavus degraded 82.7% of the total PAH compounds, with the complete degradation of six compounds, whereas A. fumigatus degraded 68.9% of the total PAHs, with four aromatic compounds completely degraded. We also tested whether different temperatures, pH, and nitrogen sources influenced the growth of A. flavus and the degradation rate. The degradation process was optimal at a temperature of 30°C, pH of 5.5, and with nitrogen in the form of yeast extract. Finally, the ability of the fungal candidate, A. flavus, to degrade PAH compounds under these optimum conditions was studied. The results showed that 95.87% of the total PAHs, including 11 aromatic compounds, were completely degraded after 15 days of incubation. This suggests that A. flavus is a potential microorganism for the degradation of PAH compounds in aqueous cultures. 相似文献
157.
A study to assess the level of organochlorine pesticides (OCPs) and bisphenol A (BPA) in edible marine biota collected from coastal waters of Malaysia was conducted using GC-MS and SPE extraction. An analytical method was developed and validated to measure the level of 15 OCPs and BPA simultaneously from five selected marine species. It was observed that some samples had low levels of p,p′-DDE, p,p′-DDT and p,p′- DDD ranging from 0.50 ng g−1 to 22.49 ng g−1 dry weight (d.w) but significantly elevated level of endosulfan I was detected in a stingray sample at 2880 ng g−1 d.w. BPA was detected in 31 out of 57 samples with concentration ranging from below quantification level (LOQ: 3 ng g−1) to 729 ng g−1 d.w. The presence of OCPs is most likely from past use although there is also indication of illegal use in recent times. The study also reveals that BPA is more widely distributed in coastal species caught off the coast of the most developed state. The potential health risk from dietary intakes of OCPs and BPA from the analysed fish species was negligible. 相似文献
158.
Mustafa Sahin Selahattin Incecik S. Topcu Ahmet Yildirim 《Journal of the Air & Waste Management Association (1995)》2013,63(7):972-982
ABSTRACT This paper presents a detailed analysis of the meteorological conditions that are associated with strong air pollution episodes in Ankara, Turkey. Based on climatological and air quality data [SO2 and TSP (total suspended par-ticulates)] obtained for the winter months during 19891994, the analysis showed that the presence of weak atmospheric pressure gradients and warm air advection were the most important factors leading to high SO2 and TSP concentrations. In addition, the onset of the high air pollution episodes was generally associated with a trend toward negative vorticity at the 850-hPa level. 相似文献
159.
Necati Kayaalp Mustafa Evren Ersahin Hale Ozgun Ismail Koyuncu Cumali Kinaci 《Environmental science and pollution research international》2010,17(9):1547-1552
Background, aim, and scope
Chemical oxygen demand (COD) is used as a discharge standard parameter in wastewater treatment plant design, environmental modelling and many other applications. Chloride interference is an important problem of COD measurement for wastewaters containing low organic matter and high chloride concentrations. In case of chloride concentrations up to 2,000 mg/L, mercury sulphate addition at a ratio of 10:1 (HgSO4:Cl−) can adequately mask the interference. When chloride concentration exceeds 2,000 mg/L, this ratio becomes ineffective to hinder the interference. At this point, it is proposed to use a greater and constant ratio of mercury sulphate addition. However, this application sometimes results in extra mercury sulphate addition which is not necessary. Even in some cases, greater addition of mercury sulphate alone is not a solution to erroneous measurement results. The purpose of the study is to determine optimum HgSO4:Cl− ratios according to the chloride concentrations of the samples and to show the importance of the strength of the digestion solution for the correct determination of the COD parameter. 相似文献160.
Bal R Türk G Tuzcu M Yilmaz O Kuloglu T Gundogdu R Gür S Agca A Ulas M Cambay Z Tuzcu Z Gencoglu H Guvenc M Ozsahin AD Kocaman N Aslan A Etem E 《Journal of environmental science and health. Part. B》2012,47(5):434-444
In the current study it was aimed to investigate the toxicity of low doses of imidacloprid (IMI) on the reproductive organ systems of adult male rats. The treatment groups received 0.5 (IMI-0.5), 2 (IMI-2) or 8 mg IMI/kg body weight by oral gavage (IMI-8) for three months. The deterioration in sperm motility in IMI-8 group and epidydimal sperm concentration in IMI-2 and IMI-8 groups and abnormality in sperm morphology in IMI-8 were significant. The levels of testosterone (T) and GSH decreased significantly in group IMI-8 compared to the control group. Upon treatment with IMI, apoptotic index increased significantly only in germ cells of the seminiferous tubules of IMI-8 group when compared to control. Fragmentation was striking in the seminal DNA from the IMI-8 group, but it was much less obvious in the IMI-2 one. IMI exposure resulted in elevation of all fatty acids analyzed, but the increases were significant only in stearic, oleic, linoleic and arachidonic acids. The ratios of 20:4/20:3 and 20:4/18:2 were decreased and 16:1n-9/16:0 ratio was increased. In conclusion, the present animal experiments revealed that the treatment with IMI at NOAEL dose-levels caused deterioration in sperm parameters, decreased T level, increased apoptosis of germ cells, seminal DNA fragmentation, the depletion of antioxidants and change in disturbance of fatty acid composition. All these changes indicate the suppression of testicular function. 相似文献