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61.
Dielectric properties and ac electrical conductivity (σ
ac
) of Au/PVA(Co, Zn acetate)/n-Si and Au/PVA(Ni, Zn acetate)/n-Si Schottky diodes (SDs) have been investigated in dark and
under illumination by using experimental capacitance-voltage (C-V) and conductance-voltage (G/ω-V) measurements at 1 MHz and room temperature. Experimental results indicate that the change in dielectric constant (ɛ′), dielectric loss (ɛ″), loss tangent (tanδ), the real (M′) and imaginary (M″) parts of electric modulus and ac electrical conductivity (σ
ac
) with illumination were found to change linearly with illumination level (P). On the other hand, the ɛ′, ɛ″, tanδ and σ
ac
vs P have positive slope while the M′ and M″ vs P have negative slope. Such behavior of dielectric properties and σ
ac
can be attributed to illumination induced electron-hole pairs under illumination effect in the depletion region of SDs. The
obtained results under illumination suggest that these devices can be used as a sensor in optical applications. 相似文献
62.
Functional changes in digestive enzyme activities of meagre (Argyrosomus regius; Asso, 1801) during early ontogeny 总被引:1,自引:0,他引:1
Cüneyt Suzer H. Okan Kamacı Deniz Çoban Şükrü Yıldırım Kürşat Fırat Şahin Saka 《Fish physiology and biochemistry》2013,39(4):967-977
The ontogenesis of main pancreatic and intestinal enzymes was investigated in the recent promising Mediterranean candidate species of meagre, Argyrosomus regius, during larval development until 40 days after hatching (DAH). The green-water technique was carried out for larval rearing. Whole-body homogenates were used for enzymatic analysis in larvae younger than 15 DAH; after this date, older larvae were dissected into two segments as pancreatic and intestinal segment. Trypsin was detected as early as hatching and sharply increased concurrently with age and exogenous feeding 15 DAH, but constant decline was observed until the end of experiment. Amylase was determined at 2 DAH and sharply increased 10 DAH. Then, slight decreases were found between 10 and 15 DAH, and then slow alterations were continued until the end of the experiment. Lipase was firstly measured on day 3; then, sudden decline was observed between 20 and 25 DAH. After this date, slow fluctuations were maintained until the end of the experiment. Pepsin was firstly assayed 15 DAH related to gastric gland secretion and sharply increased 30 DAH. Then, it slowly varied until end of the experiment. Enzymes of brush border membranes, alkaline phosphatase and aminopeptidase N showed similar pattern on specific activities during the first 10 days. Thereafter, while specific activity of alkaline phosphatase slightly decreased 15 and fluctuated until 20 DAH, aminopeptidase N activity slowly increased 20 DAH. Then, activity of alkaline phosphatase and aminopeptidase N constantly increased 30 DAH, indicating maturation of the intestinal digestive process, and also, these activities continued to slowly increase until the end of the experiment. The specific activity of cytosolic peptidase, leucine–alanine peptidase, smoothly increased on day 8, then fluctuated until 15 DAH. After this date, in contrast to enzymes of brush border membranes, it sharply decreased 25 DAH and continued to gradually decline until the end of the experiment. These converse expressions were indicative of a maturation of enterocytes and the transition of an adult mode of digestion. 相似文献
63.
We add a political culture dimension to the debate over the politics of food. Central to food politics is the cultural granting of authenticity, experienced
through the conjuring of relational presences of authorship. These presences derive from the faces and the places of relationality, what we term the ghosts of taste, by which food narratives articulate claims of the authorship of food by people and environments, and thus claim of authenticity.
In this paper, we trace the often-conflicting presences of authenticating ghosts in food along a prominent axis of current
debate: the local versus the global. The three cases outlined here—Greek food, Thousand Island dressing, and wild rice—illustrate
the recovery and suppression of the lingering spirits of both local and global faces and places in what we taste, and show
the mutually interdependent consequence of culture and economics in food politics. 相似文献
64.
Serhat Türkmen Orhan Tufan Eroldoğan Hatice Asuman Yılmaz Abdüllatif Ölçülü Gül Ayten Kiriş Inan Zeynep Erçen Nazmi Tekelioğlu 《Aquaculture Research》2012,43(11):1643-1650
The compensatory growth response of the European sea bass (Dicentrarchus labrax) that faced cycling starvation and restricted ration was assessed. Juveniles (10.5 g) were stocked into 15 tanks at a density of 25 fish per tank. Five different feeding regimes were tested on triplicate groups of fish: CSatiation: control fed for 60 days without deprivation, CRestricted: 25% restricted feeding, S‐R: 1 day starvation then 4 days CRestricted feeding, R‐F: 1 day CRestricted feeding then 4 days CSatiation feeding, and, finally, S‐F: 1 day starvation then 4 days CSatiation feeding. The specific growth rate of fish in the CSatiation (2.5 ± 0.06% day?1), S‐F (2.5 ± 0.11% day?1) and R‐F (2.4 ± 0.18% day?1) were significantly higher than that of CRestricted (2.2 ± 0.05% day?1) or S‐R (2.0 ± 0.01% day?1). Fish in S‐F group were able to achieve catching up with the CSatiation. There was no significant difference in feed conversion rates but R‐F and S‐F consumed approximately 34% more feed than CSatiation following the first re‐feeding day. Although, the highest lipid content was observed in CSatiation (14.4%), S‐R (33.3% dry matter) had the highest water content compared with the CSatiation and CRestricted (37.8% and 36.9% dry matter respectively). In conclusion, it may be concluded that sea bass has rapid response to cycling starvation/re‐feeding and that a 25% restricted feeding ratio is insufficient to invoke a compensatory growth response in sea bass. 相似文献
65.
Ferbal Özkan-Yılmaz Arzu Özlüer-Hunt Suna Gül Gündüz Mehmet Berköz Serap Yalın 《Fish physiology and biochemistry》2014,40(2):355-363
In this study was evaluated potential protective effect of organic selenium (Se) on heavy metal stress induced by lead (Pb) in Cyprinus carpio. For this reason, C. carpio was exposed to sublethal concentration of Pb (1.5 mg/L Pb(NO3)2) for 14 days. The fish were fed a basal (control; measured 0.55 mg/kg Se) diet or a basal diet supplemented with 2.50 mg/kg (measured 2.92 mg/kg Se) organic Se (Sel-Plex®) during the experiment period. The variations in glutathione peroxidase (GSH-Px), glutathione S-transferase (GST) activities, and levels of reduced glutathione (GSH) with malondialdehyde (MDA) in liver and brain tissues of C. carpio were investigated in experimental groups. GSH levels in liver and brain tissues were significantly decreased by exposure to Pb. GST activity was significantly increased (p < 0.05) in liver tissue, but decreased in brain of treated fish by exposure to Pb. Also, GSH-Px activity was significantly increased in liver tissue, but decreased in brain of Pb-treated fish. Levels of MDA were increased in liver and brain of Pb-treated fish. The organic Se treatment for Pb-intoxicated animals improved activities of GSH-Px, GST and levels of MDA within normal limits. Supplemented Se could be able to improve Pb-induced oxidative stress by decreasing lipid peroxidation and regulating antioxidant defense system in tissues. 相似文献
66.
The aim of the present study was to determine the effect of various cryoprotectants on post-thaw sperm quality and fertilizing capacity of cryopreserved scaly carp (Cyprinus carpio) semen. The present study focused on freezing of scaly carp sperm utilizing a practical and inexpensive protocol for aquaculture. Semen was diluted with Kurokura’s extender composing 3.6 g/l NaCl, 10 g/l KCl, 0.22 g/l CaCl2, 0.08 g/l MgCl2 and 0.2 g/l NaHCO3. The extender contained three different cryoprotectants (DMSO, DMA and egg yolk) at ratios of 5, 10 and 15 %. Semen was placed into 0.25-ml straws and exposed to liquid nitrogen vapor (?120 °C) using an insulated box with an adjustable tray for 10 min and then plunged into liquid nitrogen (?196 °C) tank. The thawing process was performed in a water bath at 40 °C for 10 s. The results indicated that type of cryoprotectants and their concentrations are rather effective in scaly carp sperm cryopreservation on post-thaw sperm quality, while they are very important in order to obtain high fertilization rates. The highest fertilization rate was determined as 96.4 ± 0.15 % with 15 % egg yolk, while the highest hatching rate was determined as 99.3 ± 0.80 with 15 % DMA. In conclusion, the applied cryopreservation method for scaly carp sperm is suitable to fertilize high amounts of eggs. 相似文献
67.
Emel Alkan Fatih Kapukıran Elif Öztürk Er Dotse Selali Chormey Seyfullah Keyf Nizamettin Özdoğan Sezgin Bakırdere 《Water, air, and soil pollution》2018,229(9):298
The potential risk of pesticides to cause harm to humans and other organisms even at trace levels calls for sensitive and accurate analytical techniques for their simultaneous qualitative and quantitative determinations. In this study, a sensitive binary dispersive liquid-liquid microextraction (B-DLLME) strategy was developed for the simultaneous determination of phorate and oxyfluorfen by gas chromatography mass spectrometry after extraction/preconcentration from aqueous solution. An experimental design was used to optimize parameters of the B-DLLME method to obtain maximum outcome. Under the optimum conditions of B-DLLME, the limit of detection (LOD) for phorate and oxyfluorfen were found to be 0.41 μg L?1 and 0.54 μg L?1, respectively. The detection limits correlate to about 37 and 73 folds enhancement in detection powers when compared to direct GC-MS determination of phorate and oxyfluorfen, respectively. In order to find out the applicability of developed method to real samples, recovery tests were performed for 20 μg L?1 of phorate and oxyfluorfen spiked in well water samples. Percent recovery values were found to be 94.5% for phorate and 101.9% for oxyfluorfen. 相似文献
68.
Bülent Öztürk 《Fibers and Polymers》2010,11(3):464-473
This research work was concerned with the evaluation of the effect of fibre content on the mechanical properties of composites.
Composites were fabricated using jute/phenol formaldehyde (PF), rockwool/PF, and jute/rockwool hybrid PF with varying fibre
loadings. Jute and rockwool fibre reinforced PF composites were fabricated with varying fibre loadings (16, 25, 34, 42, 50,
and 60 vol.%). The jute/rockwool hybrid PF composites were manufactured at various ratios of jute/rockwool fibres such as
1:0, 0.92:0.08, 0.82:0.18, 0.70:0.30, 0.54:0.46, 0.28:0.72, and 0:1. Total fibre content of the hybrid composites was 42 vol.%.
The results showed that tensile strength of the composite increased with increasing fibre content up to 42 vol.% over which
it decreased for jute and rockwool fibre reinforced PF composites. Flexural strength of the composite was noted to peak at
a fibre loading of 42 vol.% for jute/PF composites, and 34 vol.% for rockwool/PF composites. Impact strength of jute/PF composites
increased with increasing fibre loading but that of rockwool/PF composites decreased at higher (>34 vol.%) fibre loadings.
Tensile, flexural, and impact strengths of jute/PF composites were found to be higher than those of rockwool/PF composites.
The maximum hardness values were obtained 42 vol.% for jute/PF composite, and 34 vol.% for rockwool/PF composite. Further
increase in fibre loading adversely affected the hardness of both composites. For jute/rockwool hybrid PF composites, tensile
and impact strengths decreased with increasing rockwool fibre loading. The maximum flexural strength of jute/rockwool hybrid
PF composites was obtained at a 0.82:0.18 jute/rockwool fibre ratio while maximum hardness was observed at a 0.28:0.72 jute/rockwool
fibre ratio. The fractured surfaces of the composites were analysed using scanning electron microscope in order to have an
insight into the failure mechanism and fibre/matrix interface adhesion. 相似文献
69.
The aim of this study was to identify methicillin‐resistant Staphylococcus aureus (MRSA) strains gathered from 2002 to 2006 from milk samples in Aydin region in Turkey. Among 93 S. aureus strains isolated from bovine milk with mastitis, 16 were resistant to methicillin. Methicillin‐resistant S. aureus strains were studied further for their staphylococcal cassette chromosome mec (SCCmec) types, pulsotypes, spa and MLST types, antimicrobial susceptibilities, mechanisms of resistance and presence of Panton–Valentine leucocidin (PVL) toxin gene. The MRSA strains were multi‐drug resistant. The susceptibility rates to antimicrobials tested were 0%, 0%, 0%, 0%, 6.25%, 16.25% and 56.25% for erythromycin, clindamycin, chloramphenicol, gentamicin, tetracyclin, ciprofloxacin and vancomycin, respectively. All tetracycline and gentamicin resistant strains carried tet(M) and aac(6)‐aph(2) gene, respectively. Among macrolide‐resistant isolates, nine had erm(A), and seven had both erm(A) and erm(B) genes. The molecular characterization by pulsed‐field gel electrophoresis showed presence of three pulsotypes with their variants. The pulsotype B strains were type IV with SCCmec typing, and representative of pulsotype B was t190 by spa typing and ST8 by MLST typing. The strains with pulsotype A and C were SCCmec III, and representative of these pulsotypes was t030 by spa typing. The MLST type of pulsotype A was ST239 and pulsotype C was one allele variant of ST239. None of the isolates harboured the PVL gene. Presence of hospital‐related MRSA strains may indicate transmission of these strains between human and animals. In case of clonal spread beside the infected animals’ treatment of MRSA carrier, farm workers should also be considered. Hygienic measures and rational antibiotic use may avoid resistance selection, clonal dissemination of resistant strains and decrease losses because of mastitis in dairy herds. 相似文献
70.