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81.
In this work, we report a comprehensive theoretical investigation of electroactive star shaped pyrrole functionalized triazine monomer with two main goals. First goal of this work is to explore the physical and chemical properties of the monomer, then to investigate correlation between the experimental and the theoretical properties of monomer. The scale factor which is calculated from B3LYP/cc-pVDZ was determined as 0.985 for FT-IR and it is an important and reliable contribution to the literature. It is determined that the most appropriate basis set for this molecule. The other novel objective of this research is to investigate temperature effect on displacement of chlorine atoms in 2,4,6-trichloro-1,3,5-triazine. This method applied for the first time in the literature for triazines is especially crucial to the synthesis of unsymmetrical triazines. 相似文献
82.
The use of highly purified immunoglobulin became among the most powerful adopted strategies in therapeutic trials nowadays. Their role as immunomodulatory and anti-inflammatory agents has widened their scope of use. A novel continuous supermacroporous monolithic cryogels embedded with histidine-epoxy-activated-sepharose beads were synthetized as a new monolithic adsorbents for the separation of immunoglobulin G from human serum. The histidine-epoxy-activated-sepharose beads were embedded into the 2-hydroxyethyl methacrylate (HEMA) cryogels present in frozen aqueous solution inside a plastic syringe. The microstructure morphology of the cryogels was characterized by swelling measurement and scanning electron microscopy. The adsorption of human IgG on the histidine-epoxy-activated-sepharose beads pHEMA cryogels appeared to follow the Langmuir–Freundlich adsorption isotherm model. The maximum IgG adsorption was observed at 4°C and pH 7.4 and was found to be 26.95 mg/g of cryogel which is close to that obtained experimentally (24.49 mg/g). The cryogels were used for several adsorption-desorption cycles without any negligible decrease in their adsorption capacity. 相似文献
83.
Çulfaz PZ Buetehorn S Utiu L Kueppers M Bluemich B Melin T Wessling M Lammertink RG 《Langmuir : the ACS journal of surfaces and colloids》2011,27(5):1643-1652
The fouling behavior of microstructured hollow fibers was investigated in constant flux filtrations of colloidal silica and sodium alginate. It was observed that the fouling resistance increases faster with structured fibers than with round fibers. Reversibility of structured fibers' fouling was similar during silica filtrations and better in sodium alginate filtrations when compared with round fibers. The deposition of two different silica sols on the membranes was observed by NMR imaging. The sols had different particle size and solution ionic strength and showed different deposition behaviors. For the smaller particle-sized sol in deionized solution (Ludox-TMA), there was more deposition within the grooves of the structured fibers and much less on the fins. For the alkali-stabilized sol Bindzil 9950, which had larger particles, the deposition was homogeneous across the surface of the structured fiber, and the thickness of the deposit was similar to that on the round fiber. This difference between the deposition behavior of the two sols is explained by differences in the back diffusion, which creates concentration polarization layers with different resistances. The Ludox sol formed a thick polarization layer with very low resistance. The Bindzil sol formed a slightly thinner polarization layer; however, its resistance was much higher, of similar magnitude as the intrinsic membrane resistance. This high resistance of the polarization layer during the Bindzil sol filtration is considered to lead to quick flow regulation toward equalizing the resistance along the fiber surface. The Ludox particles were trapped at the bottom of the grooves as a result of reduced back diffusion. The fouling behavior in sodium alginate filtrations was explained by considering the size-dependent deposition within the broad alginate size distribution. The better reversibility of fouling in the structured fibers is thought to be the result of a looser deposit within the grooves, which is more easily removed than a compressed deposit on the round fibers. 相似文献
84.
This paper investigates an optimal sequencing and dynamic pricing problem for a two-class queueing system. Using a Markov
Decision Process based model, we obtain structural characterizations of optimal policies. In particular, it is shown that
the optimal pricing policy depends on the entire queue length vector but some monotonicity results prevail as the composition
of this vector changes. A numerical study finds that static pricing policies may have significant suboptimality but simple
dynamic pricing policies perform well in most situations. 相似文献
85.
Gülsev Dilber Mahmut Durmuş Halit Kantekin Volkan Çakır 《Journal of organometallic chemistry》2011,696(15-16):2805-2814
The synthesis and characterization of peripherally tetra-biphenyl-4-yl-methoxy substituted metal-free (4), Ni(II) (5), Cu(II) (6), Zn(II) (7), Co(II) (8) and Pb(II) (9) phthalocyanine derivatives are reported. These new phthalocyanine derivatives show the enhanced solubility in organic solvents and they have been characterized by a combination of IR, 1H NMR, 13C NMR, UV–vis, mass spectral data, elemental analysis and thermal analysis methods (TG/DTA). The photophysical (fluorescence quantum yield and lifetime) and photochemical (singlet oxygen generation and photodegradation quantum yield) properties of tetra-biphenyl-4-yl-methoxy substituted zinc (II) phthalocyanine derivative (7) are also investigated. The fluorescence of this phthalocyanine derivative (7) is effectively quenched by addition of 1,4-benzoquinone (BQ). 相似文献
86.
We present a method to identify the symmetry class of an elasticity tensor whose components are given with respect to an arbitrarily
oriented coordinate system. The method is based on the concept of distance in the space of tensors, and relies on the monoclinic
or transversely isotropic distance function. Since the orientation of a monoclinic or transversely isotropic tensor depends
on two Euler angles only, we can plot the corresponding distance functions on the unit sphere in ℝ3 and observe the symmetry pattern of the plot. In particular, the monoclinic distance function vanishes in the directions
of the normals of the mirror planes, so the number and location of the zeros allows us to identify the symmetry class and
the orientation of the natural coordinate system. Observing the approximate locations of the zeros on the plot, we can constrain
a numerical algorithm for finding the exact orientation of the natural coordinate system. 相似文献
87.
Abstract Three new spectrophotometric methods are described for the determination of lisinopril and hydrochlorothiazide in their binary mixturer: First derivative spectrophotometry ratio spectra derivative and Vierordt's method. The procedures do not require any prior separation. In the derivative spectrophotometry, the dA/dλ values in the first derivative spectra of the mixture were measured at 269.6 nm for lisinopril and at 279.8 nm for hydrochlorothiazide. The calibration graphs were linear in the range 25.56–129.50 μg.ml?1 for lisinopril and 10.60–139.80 μg.ml?1 for hydrochlorothiazide. In ratio spectra derivative spectrophotometry, the calibration graphs for 15.68–129.50 μg.ml?1 lisinopril and for 5.98–139.80 μg.ml?1 hydrochlorothiazide were obtained by measuring the signals at 253.7 nm and 243.6 nm for lisinopril and at 280.1 nm and 270.8 nm for hydrochlorothiazide. In Vierordt's method, A1 1 (1 %, 1 cm) values of lisinopril and hydrochlorothiazide were determined at 259.8 nm and 272.7 nm in the zero-order spectra. The quantity of both compounds were calculated by using the A1 1 (1 %, 1cm) values. The methods were successfully applied to a pharmaceutical formulation for determination of both active compounds. 相似文献
88.
In this study, the effect of ascorbic acid in the electrochemical behavior of copper has been investigated in 3.5 % NaCl solution using potentiodynamic polarization and electrochemical impedance spectroscopy. Current-potential curve and Nyquist diagrams were obtained in different concentrations of ascorbic acid. The surface morphology of copper after its exposure to 3.5 % NaCl solution with and without of ascorbic acid was examined by scanning electron microscopy. The obtained results show that ascorbic acid inhibits corrosion of copper in 3.5 % NaCl solution. The inhibition activity of ascorbic acid increases with a decrease in the concentration of ascorbic acid. 相似文献
89.
Çiğdem Hopa Mahir Alkan Canan Kazak N. Burcu Arslan Raif Kurtaran 《Journal of chemical crystallography》2010,40(2):160-164
Abstract
The dinuclear cadmium(II) complex with 2,6-bis(3,4,5-trimethyl-N-pyrazolyl)pyridine (btmpp) has been synthesized, and characterized by single crystal X-ray diffraction, IR, UV–Vis and TGA–DTA methods. Cd atoms are located in a distorted octahedral environment in the complex. The complex crystalizes in monoclinic space group C 2/c, with unit cell dimensions a = 20.5636(12) Å, b = 14.0167(13) Å, c = 15.6598(11) Å, β = 113.425(5)o, V = 4141.7(5) Å3. There are two intermolecular and a intramolecular hydrogen bonds interactions in crystal. 相似文献90.
Ru(II) complexes of the general formula [RuCl2(′′)(L)] (1: ′N = Nb, L = MeOH; 2: ′N = Nb, L = CH3CN; 3: ′N = Nd, L = CH3CN; 4: ′N = Np, L = CH3CN), [Ru(p‐cymene)(a–b)Cl]Cl (5a: N Na = 2,2′‐bipyridine; 5b: N Nb = 4,4′‐dimethyl–2,2′‐bipyridine), [Ru(′′)(a–b)Cl]Cl (6a: ′N = Nb, a = 2,2′‐bipyridine; 6b: ′N = Nb, b = 4,4′‐dimethyl‐2,2′‐bipyridine; 7a: ′N = Nd, a = 2,2′‐bipyridine; 7b: ′N = Nd, b = 4,4′‐dimethyl‐2,2′‐bipyridine; 8a: ′N = Np, a = 2,2′‐bipyridine; 8b: ′N = Np, b = 4,4′‐dimethyl‐2,2′‐bipyridine) and [Ru(′′)(a)Cl]BF4 (9a: ′N = Nb; a = 2,2′‐bipyridine) were synthesized from the corresponding [RuCl2(p‐cymene)]2 dimer, ′′ and a–b ligands. The compounds were characterized by elemental analysis, IR and NMR. Complex 9a was studied by X‐ray diffraction, confirming its cationic‐mononuclear [RuCl(bb)(a)]+ nature. The synthesized Ru(II) complexes (1–8) were employed as catalysts for the transfer hydrogenation of ketones to secondary alcohols in the presence of KOH using 2‐propanol as a hydrogen source at 82°C. The rates of the transfer hydrogenation reactions strongly depended on the type of and ancillary ligands. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献