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1.
Synthesis of melamine based polymer complexes and their thermal degradations and magnetic properties
Şaban Uysal 《Journal of inclusion phenomena and macrocyclic chemistry》2013,76(1-2):223-230
In this study, new polymer Fe(III) and Cr(III) complexes were synthesized. These polymer complexes were characterized by using elemental analysis, FT-IR spectroscopy, MS, thermal analyses and magnetic susceptibility measurement technics. Their thermal degradations were investigated, and co-polymerization was compared to aliphatic polymerization by using 1,2-dibromomethylbenzene and o-phenylenedialdehyde. Finally, metal ratios of the complexes were determined by using atomic absorption spectroscopy. The complexes are distorted octahedral low-spin (S = 1/2) Fe(III) and distorted octahedral (S = 3/2) Cr(III) bridged by COO? and catechol groups. 相似文献
2.
In this experimental study, performance of counter flow type Ranque-Hilsch vortex tubes (RHVT), with a length to diameter
ratio of 10, 15 and 18, were investigated with 2, 4, 6 nozzles. The measure of performance was chosen as the difference between
the temperatures of hot output stream and cold output stream. The performances of RHVTs were experimentally tested by making
use of velocity and temperature measurements of the input and output streams. It was determined that the difference between
the temperatures of these streams, changed between 9 and 56 K. When all the results were assessed, it was concluded that the
best performance was obtained when the ratio of vortex tube’s length to the diameter was 15 and the nozzle number was at least
four, and the inlet pressure was as high as possible. Desired performance could be obtained by controlling the rate of the
hot output stream. 相似文献
3.
A simple extraction and determination method for folic acid (FA) in lentil samples was developed employing capillary electrophoresis. The analysis was performed in a 75 μm ID fused silica capillary using a running buffer of 10 mM sodium borate (10%, v/v, methanol, pH 9) at +18 kV and a detection wavelength at 200 nm. Methylparaben was used as the internal standard. FA signal response was linear in the range between 1.2 × 10?5 and 4.8 × 10?5 M. Limit of detection (inter-day) was determined at 6.12 × 10?7 M (3.3 σs?1). The amount of FA found in green, red and mignon lentils was found to range between 0.408 and 0.742 mg g?1. 相似文献
4.
It has long been known that thiol-terminated molecules self-assemble as commensurate monolayers on Au(111) surfaces. By spreading floating octadecanethiol monolayers on aqueous solutions of chloroauric acid (HAuCl4) and using x rays to reduce the gold ions as well as to probe the structure, we have observed the nucleation of (111)-oriented Au nanoparticles at thiol surfaces. This process may be similar to the formation of biogenic gold by bacteria. The thiol monolayer acts as a "soft template," changing its structure as Au crystals form so that there is a sqrt[3]×sqrt[3] commensurate relationship. 相似文献
5.
Elemental mixtures of Al, Cu, Fe powders with the nominal composition of Al70Cu20Fe10 were mechanically alloyed in a planetary ball mill for 80 h. Subsequent annealing of the as-milled powders were performed
at 600–800°C temperature range for 4 h. Structural characteristics of the mechanically alloyed Al70Cu20Fe10 powders with the milling time and the heat treatment were investigated by X-ray diffraction (XRD), differential scanning
calorimeter (DSC) and differential thermal analysis (DTA). Mechanical alloying of the Al70Cu20Fe10 did not result in the formation of icosahedral quasicrystalline phase (i-phase) and a long time milling resulted in the formation
of β-Al(Cu,Fe) solid solution phase (β-phase). The i-phase was observed only for short-time milled powders after heat treatment above 600°C. The β-phase was one of the major phases in the Al70Cu20Fe10 alloy. The w-Al7Cu2Fe1 phase (w-phase) was obtained only after heat treatment of the short-time milled and unmilled samples. The present investigation
indicated that a suitable technique to obtain a large amount of quasicrystalline powders is to use a combination of short-time
milling and subsequent annealing. 相似文献
6.
7.
S. Aynur Uysal 《Journal of Geometry》1994,51(1-2):167-171
8.
The hydrogenated nanocrystalline silicon (nc-Si:H) thin films were produced by capacitively-coupled plasma enhanced chemical vapor deposition (PECVD) technique at low substrate temperatures (Ts ≈ 40–200 °C). Firstly, for particular growth parameters, the lowest stable Ts was determined to avoid temperature fluctuations during the film deposition. The influence of the Ts on the structural and optical properties of the films was investigated by the Fourier transform infrared (FTIR), UV–visible transmittance/reflectance and X-ray diffraction (XRD) spectroscopies. Also, the films deposited at the center of the PECVD electrode and those around the edge of the PECVD electrode were compared within each deposition cycle. The XRD and UV–visible reflectance analyses reveal the nanocrystalline phase for the films grown at the edge at all Ts and for the center films only at 200 °C. The crystallinity fraction and lateral dark conductivity decrease with lowered Ts. FTIR analyses were used to track the hydrogen content, void fraction and amorphous matrix volume fraction within the films. The optical constants obtained from the UV–visible transmittance spectroscopy were correlated well with the FTIR results. Finally, the optimal Ts was concluded for the application of the produced nc-Si:H in silicon-based thin film devices on plastic substrates. 相似文献
9.
The aim of this study is to obtain further information about the source of proton relaxation in the Mn(II)-human serum albumin
complex. For this purpose, proton relaxation rates in albumin solutions 1/T
1 and 1/T
2 were measured versus increasing amounts of manganese [Mnt]. The fractions of manganese bound to albumin [Mnb] and free manganese [Mnf] were then determined from proton relaxation rate enhancement data. Paramagnetic contributions of bound manganese to the
observed relaxation rates (1/T
1p*)b and (1/T
2p*)b were also determined. Finally, the (1/T
2p*)b/(1/T
1p*)b ratio was used in a derived equation to estimate an effective correlation time τ. Mean τ value of the complex was found to be in the order of 3 ns, while the hydration number of bound manganese q was estimated to be about 4. The 1/τ was found to be the sum of the inverse values of rotational correlation time 1/τ
r, mean residence time of water in hydration spheres of the complex 1/τ
m, and longitudinal electronic relaxation time of manganese 1/τ
s in the complex. In conclusion, the relaxation mechanism in albumin solutions containing Mn(II) can be interpreted through
dipolar and scalar interactions modulated by τ
r, τ
m and τ
s. This analysis enables one to get reasonable figures for the τ
r and q of Mn(II) in albumin solution. 相似文献
10.
Ulku Dilek Uysal Zeineb Aturki Maria Augusta Raggi Salvatore Fanali 《Journal of separation science》2009,32(7):1002-1010
In this paper, the simultaneous separation of several polyphenols such as (+)‐catechin, (–)‐epicatechin, (–)‐epigallocatechin, theophylline, caffeine in green and black teas by capillary electrochromatography (CEC) was developed. Several experimental parameters such as stationary phase type, mobile phase composition, buffer and pH, inner diameter of the columns, sample injection, were evaluated to obtain the complete separation of the analysed compounds. Baseline resolution of the studied polyphenols was achieved within 30 min by using a capillary column (id 100 μm) packed with bidentate C18 particles for 24.5 cm and a mobile phase composed of 5 mM ammonium acetate buffer pH 4 with H2O/ACN (80:20, v/v). The applied voltage and the temperature were set at 30 kV and 20°C. Precision, detection and quantification limits, linearity, and accuracy were investigated. A good linearity (R2 > 0.9992) was achieved over a concentration working range of 2–100 μg/mL for all the analytes. LOD and LOQ were 1 and 2 μg/mL, respectively, for all studied compounds. The CEC method was applied to the analysis of those polyphenols in green and black tea samples after an extraction procedure. Good recovery data from accuracy studies ranged between 90% and 112% for all analytes. 相似文献