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61.
The photopeak efficiency, peak to valley ratio and energy resolution of a 3×3×1 mm3 CdTe detector were determined experimentally for 13–1333 keV photon energy by using polyester coated radioisotopes 241Am, 22Na, 54Mn, 57Co, 60Co, 109Cd, 137Cs and 133Ba. The data were analyzed by using PX4 from Amptek. The experimental values were fitted to an analytical function of photon energy, and an agreement was observed for the entire range of the studied energies. The results have shown that the CdTe detector has a high performance due to both the improved charge collection efficiency comparable with that of SI GaAs detectors (Vittone et al., 1999), and the low leakage current. Also, CdTe detector is very attractive for field application as it works at room temperature. 相似文献
62.
Feyza Tatli Demet Uzun Tuğba Tabanlıgil Calam Ayla Balaban Gündüzalp Erdoğan Hasdemir 《Surface and interface analysis : SIA》2019,51(4):475-483
A [(1H-1,2,4-triazole-3-ylimino)methyl]naphthalene-2-ol (TMN-2-ol) film modified platinum (Pt) electrode has been fabricated by the electrochemical oxidation in acetonitrile solution. The modified surface was characterized by electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS). The prepared Pt electrode can be used as a functional interface to sensitive and selective determination of dopamine (DA) in the presence of uric acid (UA) and ascorbic acid (AA) by square wave voltammetry (SWV) method. The limit of detection (LOD) and limit of quantification (LOQ) of DA were 9.25 × 10−8 and 2.78 × 10−7 M, respectively. Linear range of DA was found to be between 3.95 × 10−7 and 4.19 × 10−6 M. 相似文献
63.
Recent observations (Eur. Phys. J. E 9, 135 (2002)) showed that the vitrification process, which sets in during the linear bulk methyl methacrylate (MMA) polymerization carried out below glass transition temperatures, can be modelled by static percolation picture. To generalize this observation for different kind of bulk linear or crosslinked polymers not enough data are present in the literature. To cover partly this deficit we studied the glass transition of MMA and styrene (Sty) crosslinking copolymerization in varying ratios of MMA and Sty. Both the fluorescence intensity I and the lifetime
of pyrene (Py) used as a nanosecond in situ fluoroprobe were monitored during the gelation time. Both I and
increase dramatically as a result of the reduced mobility of the probes trapped in the glassy regions, appearing near the glass transition point. The average size of the glassy regions just below, and the strength of the infinite network formed upon the connection of the glassy regions above the glass transition point
obey power law relations. The data around
were interpreted on the basis of the percolation theory and we observed that the corresponding exponents
and
give static percolation values independent of the polymer composition.Received: 9 July 2004, Published online: 1 October 2004PACS:
64.60.Ak Renormalization-group, fractal, and percolation studies of phase transitions - 64.70.Pf Glass transitions - 82.35.Jk Copolymers, phase transitions, structure 相似文献
64.
Demet Topaloğlu Yazıcı Hayrullah Çetinkaya Musa Şölener Adile Albayrak 《International Journal of Polymer Analysis and Characterization》2017,22(6):483-489
The surface properties of newly synthesized N-methoxy isopropyl acrylamide, N-methoxy isopropyl methacrylamide, cyclo propyl acrylamide, and cyclo propyl methacrylamide polymers were investigated using inverse gas chromatography. The highest dispersive component of the surface energy value was obtained for cyclo propyl methacrylamide at 30°C. The values obtained for all polymers were decreasing with the increasing temperature. The values obtained for the acidic and the basic parameters revealed strong basic characters for the surface of N-methoxy isopropyl methacrylamide and cyclo propyl methacrylamide polymers and weak basic characters for the surface of N-methoxy isopropyl acrylamide and cyclo propyl acrylamide polymers. 相似文献
65.
Four new y-shaped fluorophores of 4- {4,5-[2,2'-Bis(2,4,6-trimethoxyphenyl)vinyl]-1-H-imidazole-2-yl}benzonitrile 1a, 2-phenyl-{4,5-[2,2'-Bis(2,4,6-trimethoxyphenyl)vinyl]-1-H-imidazole} 1b, 2- (9-anthryl)-{4,5-[2,2'-Bis(2,4,6-trimethoxyphenyl)vinyl] }-1-H-imidazole 1c and 2- (4-nitrophenyl) - {4,5-[2,2'-Bis(2,4,6-trimethoxyphenyl)vinyl] -1-H-imidazole 1d which bear an imidazole core, were synthesized for the first time via intermediate 1,6-Bis(2,4,6-trimethoxyphenyl)hexa-1,5-diene-3,4-dion with different aldehydes. The structures of the new derivatives were confirmed by (1)H NMR, (13)C NMR and FT-IR. The optical properties such as absorption and emission maxima, Stokes' shift and quantum yield values were investigated in solvents of toluene, tetrahydrofuran and acetonitrile. The products show intense emission maxima in the range of 440-630?nm. The imidazole derivatives exhibited excellent photostabilities. 相似文献
66.
Polymethylmethacrylate (PMMA) doped by multiwalled carbon nanotube (MWNT) bulk gels were prepared with different amounts of MWNTs varying in the range between 1 and 20 wt%. Free-radical cross-linking copolymerization of PMMA–MWNT composite bulk gels was characterized by the steady-state fluorescence technique. Ethylene glycol dimethacrylate (EGDM) and pyrene (P y ) were introduced as cross linker and fluorescence probe, respectively. Changes in the viscosity of the pregel solutions due to glass formation dramatically increased the P y fluorescent intensities, which were used to study the glass transition of PMMA–MWNT composite gels for various MWNT contents. The fluorescence intensity of P y is proportional to the average size of the glassy regions below and to the strength of the infinite network above the glass transition point. Observations around the glass transition point show that there are three regimes for MWNT concentration in which the gel fraction exponent, β, and the weight average degree of polymerization exponent, γ, differ drastically from percolation results, given in three dimensions as β=0.41 and γ=1.80. 相似文献
67.
A series of N‐(5‐chloro‐2‐hydroxyphenyl)‐(3/4/5‐substituted)‐salicylaldimines ( I – XI ) were synthesized using appropriate synthetic route. Their structures were characterized by FT‐IR, UV‐Visible, ESI‐MS, 1H and 13C NMR spectroscopic techniques and analytical methods. The crystal structure of N‐(5‐chloro‐2‐hydroxyphenyl)‐5‐bromosalicylaldimine ( V ) was determined by X‐ray diffraction at room temperature. Relationship between the melting points and the structures of the compounds was examined. Antimicrobial activity of the compounds was evaluated against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis. Antifungal activities were reported for Candida albicans. Schiff bases showed considerable antimicrobial activity against S. aureus, S. epidermidis and C. albicans. N‐(5‐Chloro‐2‐hydroxyphenyl)‐3‐hydroxy‐salicylaldimine ( II ) has the broadest and highest antimicrobial activity according to the others. 相似文献
68.
Feyza Karasu Demet Karaca Balta Robert Liska Nergis Arsu 《Journal of inclusion phenomena and macrocyclic chemistry》2010,68(1-2):147-153
β-Cyclodextrin (β-CD) was used to complex the monomer, methyl methacrylate (MMA), yielding a water-soluble host/guest complex. Photoinitiated polymerization of β-CD/MMA complex was achieved in the presence of thioxanthone-catechol-O,O′-diacetic acid (TX-Ct), a one component water soluble photoinitiator. Photodecarboxylation of TX-Ct in water seems to be an important reaction mechanism. Therefore, resulting alkyl radicals are able to initiate the polymerization of β-CD/MMA host/guest complex in water. 相似文献
69.
In this study,we aimed to determine the radiation parameters of some potential bioactive compounds.1-Aryl-3-dibenzylamino-propane-1-on hydrochloride type Mannich bases were synthesized via classical conventional heating method.Aryl part was changed as phenyl(C6H5),4-methylphenyl(4-CH3C6H4),4-fluorophenyl(4-FC6H4),4-nitrophenyl(4-NO2C6H4),4-chlorophenyl(4-ClC6H4),4-bromophenyl(4-BrC6H4),and 2-thienyl(C4H3S-2-yl).Mass attenuation coefficient(μm),effective atomic number(Zeff)and effective electron density(Nel)of compounds were determined experimentally and theoretically for at 8.040,8.910,13.40,14.96,17.48,19.61,22.16,24.94,32.19,36.38,44.48,50.38and 59.54keV photon energies by using an HPGe detector with a resolution of 182eV at 5.9keV.Radiation parameters of these compounds which can be anti-cancer drug candidate were given in the tables.The results show that phenyl ring behave like thiophene ring in terms of radiation absorption.It is thought that the results of study may drive allow the development of drug candidate new compounds in medical oncology. 相似文献
70.
Mesut Bilgi Demet Karaca Balta Binnur Aydogan Temel Gokhan Temel 《Journal of polymer science. Part A, Polymer chemistry》2018,56(24):2709-2714
This contribution describes a simple method for preparing polymeric nanoparticles using photodimerization of anthracene moieties on the side chain of terpolymers in dilute regime and transformation of obtained polymeric nanoparticles into pyrene functional nanoparticles via Menschutkin quaternization procedure. Subsequently, pyrene possessing polymeric nanoparticles are attached onto multiwalled carbon nanotube (MWCNT) surfaces by π–π stacking strategy. Gel permeation chromatography, thermal gravimetric analysis, ultraviolet–visible, and fluorescence spectroscopies are used to analyze modified nanoparticles and their precursors. Electron microscopy and dispersion studies show that pyrene-modified polymeric nanoparticles are able to interconnect various CNTs. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2709–2714 相似文献