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排序方式: 共有366条查询结果,搜索用时 31 毫秒
31.
Pınar Şen Fatih Dumludağ Bekir Salih Ali Rıza Özkaya Özer Bekaroğlu 《Synthetic Metals》2011,161(13-14):1245-1254
The new s-triazine-bridged trinuclear Zn(II) and Cu(II) phthalocyanines have been synthesized from the reaction of corresponding anhydrous metal salts, Zn(OAc)2 and CuCl with 4,5-bis(hexylthio)-phthalonitrile and 2,4,6-tris(2-thiophthalonitrile)-s-triazine. The tris phthalonitrile derivative of s-triazine was prepared from the reaction of 4-nitrophthalonitrile and thiocyanuric acid in dry dimethylformamide as solvent using K2CO3 as the base. The same route was applied to prepare the trinuclear Lu(III) phthalocyanine analogue. The conversion of tris phthalonitrile into its isoindoline derivative was accomplished by bubbling ammonia gas through a solution in methanol in the presence of sodium methoxide. The cyclization of two different isoindoline derivatives and 4,5-bis(hexylhthio)-1,2-diiminoisoindoline, with lutetium (III) acetate in dimethylformamide gave trinuclear Lu(III) phthalocyanine. The reaction of this complex with octakis-hexylthio phthalocyanine led to the isolation of tris double-decker Lu(III) phthalocyanine. The structures of the target compounds were confirmed by elemental analysis, UV–vis, IR and MALDI-TOF mass spectroscopies. The d.c. and a.c. conductivities of the phthalocyanine compounds were measured as a function of temperature. The small value of pre-exponential factor suggested the conduction by localized states in the band tails and by localized states near the Fermi level. The temperature dependence of the frequency exponent showed that the conduction in these compounds is due to hopping of charge carriers. The tris double-decker phthalocyanine complex showed well-defined electrochromic behaviour with green-blue and blue-purple colour transitions. 相似文献
32.
Bahadir K Krbaht Bekir Salih Abdurrahman Tanyola 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2002,77(1):70-76
The electrochemical conversion of highly concentrated synthetic phenolic wastewater was studied on carbon electrodes in a batch electrochemical reactor. The effects of reaction temperature, electrolyte concentration, current density and initial phenol concentration on phenol conversion were elucidated. The wastewater was synthetically prepared and used in reactions carried out generally at 25 °C with an initial phenol concentration of 3500 mg dm?3. Although current density increased, phenol conversion% and initial phenol conversion rate did not increase correspondingly above 35 °C and an electrolyte concentration of 90 g dm?3. As the voltage values applied were increased, the increasing current density resulted in fast phenol conversion. Kinetic investigations denoted that overall phenol destruction kinetics was of zero order with an activation energy of 10.9 kJ mol?1. Under appropriate conditions, phenol was completely converted within 15 min for an initial phenol concentration of 98 mg dm?3 while 8 h was required to gain 95% conversion using 4698 mg dm?3. Solid polymeric materials were produced at initial phenol concentrations above 500 mg dm?3 using the appropriate current density. In the reaction medium, only mono‐, di‐ and tri‐substituted chlorophenols were formed and 100% of all species were either oxidised or contributed to the formation of a polymeric structure. Almost all of the phenol loaded to the reactor was converted into non‐passivating polymeric products, denoting a safe and easy method for the separation of phenol. © 2001 Society of Chemical Industry 相似文献
33.
Recent studies have pointed to the heptamethylbenzenium cation as a prominent intermediate in the methanol to hydrocarbons (MTH) reaction. The reactions of the heptamethylbenzenium cation in a H-beta zeolite was studied at 300 °C by feeding its corresponding base (WHSV = 0.4 h?1). The reactant was converted completely into aliphatic products, polymethylbenzenes and coke under the employed conditions. The results testify that the proposed reaction intermediate yields the same product spectrum as methanol. The composition of the material retained in the catalyst micropores after 15 min of reaction was determined by dissolving the catalyst in 15% HF. Polymethylated benzenes (predominantly pentamethylbenzene), dihydro-trimethylnaphthalenes, and hexamethylnaphthalene were the major components. The results also support the idea that the lowest naphthalene derivative is formed from the heptamethylbenzenium cation by a molecular rearrangement. Hence, the heptamethylbenzenium cation is inherently linked to both product formation and catalyst deactivation in the MTH reaction. 相似文献
34.
Polyfuran (PFu), poly(2‐bromoaniline) (P2BrAn), and poly(2‐bromoaniline)/polyfuran (P2BrAn/PFu) composites were synthesized by coupling using various solvents and oxidants. 2‐Bromoaniline (2BrAn) was polymerized using FeCl3 and (NH4)2S2O8 in aqueous HCl medium. PFu was synthesized using FeCl3 and SbCl3 in anhydrous media (CHCl3, CH3CN). Furan was polymerized using both salts in CHCl3 medium, whereas it could be polymerized using only FeCl3 in CH3CN medium. The new electrically conducting composites were prepared by chemical oxidative polymerization using polyfuran synthesized with SbCl3 and poly(2‐bromoaniline). The polymers and composites were characterized using conductivity, magnetic susceptibility, infrared spectra (FTIR), UV‐Vis spectra, thermal analysis (TGA), and scanning electron microscopy (SEM) measurements. It was found that PFu(SbCl3) has the lowest thermal stability. Thus, the thermal stability of PFu was increased by preparing composites. The chemical structures of P2BrAns and composites have been found from UV‐Vis results to contain quinone‐imine units along the polymer chain. Magnetic susceptibility measurements indicated that the polymers and composites were diamagnetic or paramagnetic. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2048–2057, 2005 相似文献
35.
Cancer patients undergoing radiotherapy frequently report fatigue. However, knowledge of the importance of fatigue for these patients and of the factors associated with their fatigue is limited. The aim of the current investigation was to gain more insight into fatigue as related to radiotherapy by answering the following questions. First, how is the experience of fatigue best described? Secondly, to what extent is fatigue related to sociodemographic, medical (including treatment), physical and psychological factors? Finally, is it possible to predict which patients will suffer from fatigue after completion of radiotherapy? Patients with different types of cancer receiving radiotherapy with curative intent (n = 250) were interviewed before and within 2 weeks of completion of radiotherapy. During treatment, patients rated their fatigue at 2-weekly intervals. Results indicate a gradual increase in fatigue over the period of radiotherapy and a decrease after completion of treatment. Fatigue scores obtained after radiotherapy were only slightly, although significantly, higher than pretreatment scores. After treatment, 46% of the patients reported fatigue among the three symptoms that caused them most distress. Significant associations were found between post-treatment fatigue and diagnosis, physical distress, functional disability, quality of sleep, psychological distress and depression. No association was found between fatigue and treatment or personality characteristics. Multivariate regression analysis demonstrated that the intensity of pretreatment fatigue was the best predictor of fatigue after treatment. In view of this finding, a regression analysis was performed to gain more insight into the variables predicting pretreatment fatigue. The degree of functional disability and impaired quality of sleep were found to explain 38% of the variance in fatigue before starting radiotherapy. Fatigue in disease-free patients 9 months after treatment is described in paper (B) in this issue. 相似文献
36.
New methacrylate monomers containing pendant quaternary ammonium moieties based on 1,4‐diazabicyclo‐[2.2.2]‐octane (DABCO) were synthesized. The DABCO group contains either a butyl or a hexyl pendant group comprising the hydrophobic segment of the monomers and one tether group to the methacrylate moiety. The monomers were homopolymerized in water by using 2,2′‐azobis(2‐methylpropionamide) dihydrochloride (V‐50) as an initiator. The monomers and polymers were characterized by elemental analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), FTIR, and 13C‐NMR. The antimicrobial activities of the corresponding small molecules (bis‐quaternary ammonium monocarboxylates) and polymers were investigated against Staphylococcus aureus and Escherichia coli. Although the small molecules did not show any antimicrobial activity, the polymers were moderately effective against both Gram‐positive and Gram‐negative bacteria. The minimum inhibitory concentration (MIC) values of the polymers with butyl and hexyl hydrocarbon chains against S. aureus and E. coli were found to be 250 and 62.5 μg/mL, respectively. The minimum bactericidal concentration (MBC) value for the polymer with the butyl group was higher than 1 mg/mL, whereas the MBC value for the polymer with hexyl group was found to be 62.5 μg/mL. Thus, an increase of the alkyl chain length from 4 to 6 significantly increased the antimicrobial activity of the polymer. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 635–642, 2004 相似文献
37.
Conducting composite films of polyalkylanilines with nylon 6 as the insulating matrix were electrochemically synthesized and characterized. The electrochemical properties of the alkylanilines and their composites were investigated with a cyclic voltammetry technique. The magnetic properties of the polymers and composites were analyzed, and their conducting mechanisms were found to be of bipolaron nature. With Fourier transform infrared spectra, it was clarified that polymerization occurred via the ? NH2 group in a head‐to‐tail mechanism. Through thermogravimetric analyses, the thermal properties of the polymers and their composites were elucidated. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1693–1701, 2003 相似文献
38.
The cu-mn (copper-manganese) system 总被引:1,自引:0,他引:1
N. A. Gokcen 《Journal of Phase Equilibria and Diffusion》1993,14(1):76-83
39.
M Laroche L Costa J Bernard J Puget A Constantin A Cantagrel B Mazières 《Canadian Metallurgical Quarterly》1998,65(6):393-396
Osteonecrosis of the hip classically produces a heterogeneous density in the femoral head, although the bone marrow ischemia extends down to the femoral neck and trochanters. Also, bone insufficiency fractures due to diffuse bone loss have been implicated in the genesis of osteonecrosis. OBJECTIVES: To use dual-energy X-ray absorptiometry to quantify the bone changes produced by osteonecrosis of the hip and to compare bone mineral density values in patients with osteonecrosis of the hip and in controls. METHODS: Bone mineral density was measured at the femoral neck (total femoral neck, Ward's triangle, and trochanter), femoral head and lumbar spine using dual-energy X-ray absorptiometry (DPX, L Lunar) in 22 patients with osteonecrosis of the hip and in 22 age- and sex-matched controls. RESULTS: In the patients with osteonecrosis, bone mineral density on the affected side was higher than on the opposite side at the femoral head (+18%), femoral neck (+7%), and Ward's triangle (+6%) and lower at the trochanter (-4%). These differences were most marked at the more advanced end of the osteonecrosis spectrum. As compared to age-specific normative values, the osteonecrosis patients had moderately decreased bone mineral density values at the lumbar spine (-0.53 +/- 1.1 SD or -6 +/- 1.5%) and at the femoral neck on the normal side (-0.9 +/- 1.4 SD or 12 +/- 1.8%). As compared to the controls, bone mineral density was significantly decreased at Ward's triangle (-25%; P: 0.04) and nonsignificantly decreased at the lumbar spine (-4.7%; P: 0.15) and at the femoral neck (-15%; P: 0.09). 相似文献
40.
The values of sulfur activity in the liquid S-Fe-Co-Ni system were determined from unpublished equilibrium data for H2 +S (in alloy) = H2S. The activity coefficient of sulfur varied from 0.387 to 1.896 and increased with increasing concentrations of Fe and Co.
The published values for the activities in the binary systems Fe-Co, Fe-Ni, and Co-Ni were used to calculate the activities
in the ternary Fe-Co-Ni alloys, and these results were expressed as a function of composition. This function was used with
the activity coefficients of S in the binary metal solvents to express the activity coefficient of S in the ternary metal
solvents as a function of mol fractions of Fe, Co, and Ni. The experimental values for S in Fe-Co-Ni agreed well with the
calculated values based on the binary metal solvents, and this showed that all the activity values were consistent. 相似文献