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71.
72.
In this paper, we discuss the relationship between the organic matter, sulphur and phosphate contents of Upper Cretaceous marine carbonates (Karabogaz Formation) in the Adiyaman Petroleum Province of SE Turkey. The results of organic geochemical analyses of core samples obtained from the Karabogaz Formation suggest that phosphate deposition occurred in settings where the water column was oxic to sub-oxic. However, the preservation of organic matter was favoured in anoxic environments. Moreover, the presence of sulphur (especially sulphur incorporated into kerogen) in organic matter-rich layers led to early oil generation. The results of stepwise py-gc analyses are consistent with a model in which, with increasing maturity, S-S and C-S bonds are the first to be eliminated from the macromolecular kerogen structure. Study of the maturity evolution of S-rich kerogen by laboratory pyrolysis implies that marginally mature and/or mature kerogen in the Karabogaz Formation, which may be classified as classic “Type II” kerogen, was most probably Type II/S at lower maturity stages. This enabled oil generation to occur at relatively shallow burial depths and relatively early stages of maturation. It is reasonable to conclude that Type II/S kerogen, overlooked in previous studies, was abundant in TOC-rich intervals in the Karabogaz Formation. Early generation (and expulsion) from Type II/S kerogen may have sourced the sulphur-rich oils in the Adiyaman area oilfields. 相似文献
73.
74.
This paper proposes a new current-mode 5th-order differential type class-AB log-domain elliptic lowpass filter for video frequency
applications. The design is based on the state-space synthesis method. The proposed filter has 5.75 MHz cut-off frequency
with maximum 0.177 dB passband ripple and attenuation greater than 40 dB at 7.88 MHz. Only BJTs and grounded capacitors were
used, and operated with single power supply of 2.5 V. Since the parameters of proposed filter are tunable, it is easy to control
of cut-off frequency. This adjustment is accomplished by changing external currents. SPICE simulations are given to confirm
the theoretical analysis. For this purpose, the filter is simulated by using both idealized BJT models and AT&T CBIC-U2 type
transistors. 相似文献
75.
Fatma Al?kma Cengiz Birlikseven Gulay Gulmez Enis Turhan Eylem Gulce Coker Ugur Topal 《Journal of Superconductivity and Novel Magnetism》2012,25(7):2539-2545
In this study we report on some critical factors affecting the sensitivity of a magnetic field sensor whose working principle is based on a linear DC field dependence of the second harmonic of the AC response in polycrystalline type-II superconductors. DC-fields down to 2?nT in magnitude could be detected by finding optimal conditions. The optimal sensor design was determined by studying superconductor cores having different geometries and coil configurations. The optimal AC-field frequency, which is required for excitation of the specimen, was found to be 50?kHz. The second harmonic signal changes quite linearly with the DC-field up to 0.1?Oe. 相似文献
76.
Ismet Ozturk Serkan Sahan Ugur Sahin Lutfiye Ekici Assoc. Prof. Osman Sagdic 《Journal für Verbraucherschutz und Lebensmittelsicherheit》2010,5(3-4):453-457
In this study, antiradical and antimicrobial activity, total phenolic, mineral and heavy metal content of Morchella conica Pers. were determined in the methanolic extracts of dried M. conica collected from wild-grown edible mushroom in the Mediterranean region from Turkey. Free radical scavenging activity was determined to be 43.72 ± 0.13% DPPH decoloration, however, total phenolic activity to be 20.64 ± 0.33 mg GAE/g dry ext. sample. The antimicrobial activity of the extracts was tested against fourteen microorganism including 12 bacteria and 2 yeasts. It was determined that the mushroom extracts had no effect against the bacteria and yeasts. Antimicrobial effect was determined only against Staphylococcus aureus ATCC 29213. M. conica was determined to contain some heavy metals such as arsenic (As), mercury (Hg), cadmium (Cd), lead (Pb), chromium (Cr) and nickel (Ni) in the concentrations of 0.25, 0.06, 0.20, 1.20, 0.70 and 1.10 (mg/kg dw), respectively. Potassium (K), phosphorus (P) and magnesium (Mg) contents were determined to be 20,400, 13,250, and 1,600 (mg/kg dw), respectively, being higher than those of the other minerals in the M. conica extracts. 相似文献
77.
An in situ steady-state fluorescence (SSF) technique was applied in order to study the dissolution process of polystyrene (PS) latex films. The effect of the molecular weight M w of the PS on the dissolution rate was investigated. The PS chains were copolymerized with (1-pyrene)methyl methacrylate in order to make use of pyrene (P) as a fluorescent probe to monitor the dissolution process. Seven different films were prepared from P-labeled PS latex dispersions with different molecular weights at room temperature. These films were then annealed at 200 °C for 15 min to complete the film formation process before dissolution. The dissolution of PS films in a toluene (70 %)–cyclohexane (30 %) mixture was monitored in real time by watching the change in the fluorescence intensity of P, I P. We used a model that included both case I and case II diffusion kinetics to interpret the results of the dissolution experiments. The relaxation constants k 0 and the dissolution coefficients D d of the polymer chains were measured. Two different dissolution coefficients were obtained, which were attributed to the small and long polymer chains in the film, considering the high polydispersity of the polymer. It was also found that both of the D d values scaled with M w according to the law D d ≈ M ?n . 相似文献
78.
Metin Yurddaskal Eyyup Can Doluel Ugur Kartal Alican Koksalar Erdal Celik 《Journal of Materials Science: Materials in Electronics》2018,29(22):19005-19012
Graphene has ultra-high electrical and thermal conductivity, which makes graphene as the most encouraging fillers for thermally conductive composites. Graphene and/or carbon black filled conductive polymer composite (CPC) films used as heating element are smarter than the traditional heating elements due to less environmental pollution, ease of application on many surfaces and possess the merits of lightweight. In this study, we investigated mainly the production, characterization and industrial application of graphene/carbon black reinforced styrene acrylic copolymer emulsion matrix composite films deposited on polyvinyl chloride for flexible heating element. After that, the films were dried at room temperature for 24 h in air. Structural and surface properties of the CPC films were characterized by X-ray diffraction and scanning electron microscopy. Temperature, time and voltage relation of the produced composite films were investigated. Heating and electrical properties of the CPC films were determined by using a thermal camera and 4-point probe measurement system, respectively. The electrical resistivity of the CPC films decreases from ~?108 to 101 Ω cm with increasing the filler content or using a combination of two fillers. Graphene and carbon black filled conductive polymer composites to be considered as candidates for flexible heating element applications exhibited good electrical and heating properties thanks to synergistic effect of fillers. 相似文献
79.
In this study, the physical and mechanical behaviors of geopolymers prepared by using different amounts of silica fume and calcium hydroxide as binding materials, acidic pumice as fine aggregate and waste aluminium particles as air-entraining agent were investigated. Test results showed that binder types, amount of binders and alkali activator (sodium hydroxide) significantly affected the physical and mechanical behavior of geopolymer specimens. Bulk density, compressive and flexural strength decreased with the higher alkali activator content. Addition of waste aluminium particles led to decrease in bulk density and strength due to the some extent of entrained air. In the case of same alkali activator content, compressive and flexural strength increased with increase in silica fume and calcium hydroxide up to a certain level. 相似文献
80.
Ugur M. Auckland D.W. Varlow B.R. Emin Z. 《Dielectrics and Electrical Insulation, IEEE Transactions on》1997,4(6):763-766
Surface tracking on solid insulators is one of the most severe breakdown mechanisms associated with polymeric materials under long term service conditions. A wide range of relays can detect failure in a transmission line and prevent a total breakdown in the systems, but due to the non-healing characteristics of solid insulators, in most cases it might be too late to save the insulator after tracking initiation and growth. The method described here is employed mainly in detecting several conditions, such as discharges, leakage current, dry conditions, severe damage and tracking initiation. Initially a BPN (back propagation network) type NN (neural network) is trained with different signal types. Due to the nature of NN, which always require similar values of input nodes, the system uses the FFT (fast Fourier transform) of the input signal, which might have high amplitude frequency components other than the fundamental frequency depending an the condition of the surface. The system works on a real time basis and warns the user with the first indication of severe damage on the surface and can protect the insulator from excessive damage 相似文献