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41.
The nanostructure n-ZnO/p-Si heterojunction diode was fabricated by sol–gel method. The structural and morphological properties of the nanostructure ZnO film have been investigated. The X-ray diffraction spectra indicated that the films are of polycrystalline nature. The scanning electron microscopy images indicate that the surface morphology of ZnO film is almost homogeneous and the ZnO film is consisted of the circular formed with coming together of the nanoparticles. The electrical characterization of nanostructure n-ZnO/p-Si heterojunction diode has been investigated by current–voltage characteristics. The ideality factor (n) of the diode was found for different ambient temperatures and the obtained 6.40 value for 296 K is higher than unity due to the interface states between the two semiconductor materials and series resistance. The values of n increased with decreasing ambient temperature. The reverse current of the diode increased with illumination intensity of 100 mW cm−2 and the diode gave a maximum open circuit voltage Voc of 0.19 V and short-circuits current Isc of 8.03 × 10−8 A. 相似文献
42.
Fahrettin Yakuphanoglu Saliha Ilican Mujdat Caglar Yasemin Caglar 《Superlattices and Microstructures》2010
The microstructure, and the electrical and optical properties of undoped zinc oxide (ZnO) and cadmium-doped ZnO (CZO) films deposited by a sol–gel method have been investigated. The films have a polycrystalline structure with hexagonal wurtzite ZnO. Scanning electron microscopy (SEM) images indicated that the films have a wrinkle network with uniform size distributions. The elemental analyses of the CZO films were carried out by energy dispersive X-ray analysis. The fundamental absorption edge changed with doping. The optical band gap of the films decreased with Cd dopant. The optical constants of the films such as refractive index, extinction coefficient and dielectric constants changed with Cd dopant. A two-probe method was used to investigate the electrical properties, and the effect of Cd content on the electrical properties was investigated. The electrical conductivity of the films was improved by incorporation of Cd in the ZnO film. 相似文献
43.
Levetiracetam is one of the new generation anti–epileptic agents (also known as anticonvulsants or antiseizure drugs). Following its approval for marketing in 2000, levetiracetam has been widely used in the treatment of epilepsy due to its broad spectrum effects. One of the advantages of this antiseizure drug is its rapid and complete absorption after oral administration. It has also minimal drug–drug and food interactions, and shows more than 95% bioavailability. The determination of levetiracetam in various samples is carried out using several analytical methods including HPLC–based methods. HPLC–based methods are used for different pharmaceutical analyses and play an important role in drug monitoring during patient follow–ups. This review provides a summary of the HPLC–based methods used in the determination and quantification of levetiracetam in biological fluids and pharmaceutical preparations. 相似文献
44.
Cafer Cakal Jerome P. Ferrance James P. Landers Perihan Caglar 《Analytical and bioanalytical chemistry》2010,398(5):1909-1917
In this study, the first micro-total analysis system (μ-TAS) for catecholamines (dopamine, epinephrine, and norepinephrine)
analysis in which preconcentration, separation, and determination steps were integrated on a microchip was developed. Electrophoresis
microchips in a variety of channel lengths and designs were produced in borofloat glass for the μ-TAS studies. Chambers for
the preparation of monolithic disks were formed in the microchips at the intersection of the injection and separation channels.
Vinyl phenylboronic acid–ethylene glycol dimethacrylate polymers were prepared as monolithic disks in these chambers with
a depth of 0.05 mm and a diameter of 2.1 mm. The microchips could be used more than 50 times if mechanical problems such as
plugging or fracturing did not occur. Adsorption and elution of catecholamines were realized electrokinetically, with catecholamines
determined via laser-induced native fluorescence detection following elution and electrophoretic separation. The most promising
results were obtained with 100 mM phosphate buffer (pH 2) for elution with 25% propanol added to the separation buffer (100 mM
phosphate, pH 3). 相似文献
45.
Seval Aksoy Yasemin Caglar Saliha Ilican Mujdat Caglar 《Superlattices and Microstructures》2011,50(5):470-479
ZnO films were prepared by sol–gel method and deposited onto glass substrates with spin coating system. XRD patterns and FESEM analysis were used to investigate the effect of deposition parameters such as spin speed and molar concentration on the crystallinity and surface morphology of the films. XRD patterns show that ZnO films are polycrystalline with type-wurtzite hexagonal structure. The film which is deposited at 4000 rpm and with 0.5 M sol has the best crystallinity. The FESEM micrographs showed that the surface morphology of the films was not significantly affected from the spin speed. FESEM micrographs showed that the crystallite sizes of 1000, 4000 and 5000 rpm are almost same. But 2000 and 3000 rpm have lower crystallite sizes than the others. Also, the amount of voids in the 1 M was found higher. The effect of spin speed and molar concentration on the optical properties of ZnO films was investigated by PL spectroscopy. The electrical properties of the ZnO films were investigated by using two probe methods in dark. The highest conductivity values were obtained for ZnO films prepared by 4000 spin speed and 0.5 M of concentration. 相似文献
46.
Cafer Cakal Jerome P. Ferrance James P. Landers Perihan Caglar 《Analytica chimica acta》2011,(1):3012
A novel solid phase extraction microchip with a boronic acid functional affinity monolithic disc was developed in this work. Vinyl phenylboronic acid–ethylene glycol dimethacrylate co-polymer monoliths, which have pore sizes up to 20 μm, were investigated for extraction of catecholamines using adsorption and desorption studies in a batch system. Desorption yields of greater than 90% were achieved for catecholamines at pH 3 and below. Monolithic discs were then formed in chambers in borofloat glass microfluidic chips using in situ UV polymerization. Adsorption on the monolithic discs was performed via electrokinetic flow, with catecholamines determined via laser-induced native fluorescence (LINF) detection following electrokinetic elution. Microchips containing the boronic acid functional polymer discs worked well for extraction of catecholamines, providing greater than 100 fold concentration enrichment. This study demonstrated that a solid phase extraction microchip, containing an easily prepared monolith disc, will be useful for boronate affinity extraction of cis-diol containing compounds. 相似文献
47.
ABSTRACT The aniline species incorporated into the acid-activated bentonite matrices leads to the decay of the skeletal stretches centered at 1041 cm?1 and the rise of new features in the phenyl ring frequency region, 1700–1400 cm?1, demonstrates clearly the influence of the acid activation on the Lewis sites necessary for coordination of aniline to bentonite. The exothermic DTA features at 507, 684, and 725°C indicate the release of both the clusters and the decomposed fragments of the aniline-clay composite, and the highly stable carbonaceous residue, respectively. The basal difference by ~1.0 nm and the much smaller surface area (33.8 m2/g) than that of the nonintercalated bentonite (129.2 m2/g) prove the presence of the tilted aniline species between the interlamellar grooves of the bentonite framework. 相似文献
48.
Two New 2-Benzoylbenzoate Metal Complexes with Bapen: Synthesis,Spectroscopic and Crystal Structures
Abstract
Coordination compounds of compositions [Ni(bba)2(bapen)] (1) and [Cu(bba)2(bapen)]0.5H2O (2), where bba = 2-benzoylbenzoate, bapen = N,N′-bis(3-aminopropyl)ethylenediamine, have been prepared. The crystal and molecular structure of (1) and (2) were determined by X-ray analysis. Nickel and copper atoms are six-coordinated by four N atoms of amine and O donor atoms of 2-benzoylbenzoate anions, whereas 0.5 water molecule is situated outside the coordination sphere in (2). The calculated ∆(OCO) values are consistent with presence of monodentate carboxylate. Thermal analysis show that the mass losses of 1 in the temperature ranges 240–343 °C correspond to the decomposition of bba ligands, while the mass losses of 2 in the temperature ranges 105–125 °C correspond to the decomposition of crystal lattice water molecule. 相似文献49.
Imaging or beam-steering systems employing a periodic array of microlenses or micromirrors suffer from diffraction problems resulting from the destructive interference of the beam segments produced by the array. Simple formulas are derived for beam steering with segmented apertures that do not suffer from diffraction problems because of the introduction of a moving linear phase shifter such as a prescan lens before the periodic structure. The technique substantially increases the resolution of imaging systems that employ microlens arrays or micromirror arrays. Theoretical, numerical, and experimental results demonstrating the high-resolution imaging concept using microlens arrays are presented. 相似文献
50.
Christoph Ulbricht Caglar Remzi Becer Andreas Winter Dirk Veldman Ulrich S. Schubert 《Macromolecular rapid communications》2008,29(24):1919-1925
A methacrylate‐functionalized phosphorescent Ir(III)‐complex has been synthesized, characterized, and applied as a monomer in radical copolymerizations. Together with methyl methacrylate, the complex has been copolymerized under free radical polymerization conditions. Aiming for host‐guest‐systems, applicable e.g. in organic light emitting devices (OLEDs), the complex was further copolymerized with a methacrylate‐functionalized carbazole derivative using the atom transfer radical polymerization technique. Applying gel permeation chromatography, in combination with a photodiode array detector, could clearly prove the formation of the copolymers. The optical properties of the photoactive monomers as well as the copolymers were investigated by absorption and emission spectroscopy (in solution). For the carbazole‐copolymer, the emission originates almost exclusively from the complex. This provides evidence of an efficient intrachain energy transfer, which makes the system an interesting candidate for potential OLED applications.