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排序方式: 共有151条查询结果,搜索用时 31 毫秒
81.
Three novel polymers incorporating Schiff bases,derived from condensation reactions of poly(acrylamide) with 5- chloro-2-hydroxybenzaldehyde,5-bromo-2-hydroxybenzaldehyde and 5-methyl-2-hydroxybenzaldehyde,have been synthesized,and their Cu(Ⅱ) and Ni(Ⅱ) complexes have been prepared.The ~1H-NMR signals of the—CH=N—and—NH_2 groups have been utilized to determine the relative abundances of Schiff base and acrylamide groups in the polymers containing Schiff bases.Poly(acrylamide) incorporating Schiff bases a... 相似文献
82.
Acrylamide concentrations in grilled foodstuffs of Turkish kitchen by high performance liquid chromatography-mass spectrometry 总被引:3,自引:0,他引:3
Olcay Kaplan Gokce Kaya Cemile Ozcan Muharrem Ince Mehmet Yaman 《Microchemical Journal》2009,93(2):173-179
For over ten years, there has been a considerable interest in determination of acrylamide in foodstuffs. It was known that both protein-rich and carbohydrates-rich foods cooked at high-temperatures can cause acrylamide formation. However, carbohydrates-rich foods such as potato chips and biscuit samples have been the common studied foods compared with protein-rich foods such as meat samples.In this study, determination of acrylamide in these two group foods was examined using HPLC-MS. For this purpose, firstly, the parameters that are thought to affect the response in the HPLC-MS analysis were optimized. The optimized conditions were found to be 0.3 ml min− 1 for flow rate of mobile phase, 40 µl for injection volume, 5 °C for column temperature and 70 V for fragmentor potential. The optimized method was applied for the determination of acrylamide levels in Turkish foodstuffs including grilled meat and chicken samples, potato chips, coffee and biscuit. The obtained concentrations for all studied foods were in the range of 20–250 µg kg− 1. The results showed that acrylamide concentrations highly varied depending on the kind of food samples. 相似文献
83.
This study was focused on the photocatalytic activity of polyaniline (Pani)/iron doped titanium dioxide (Fe–TiO2) composites for the degradation of methylene blue as a model dye. TiO2 nanoparticles were doped with iron ions (Fe) using the wet impregnation method and the doped nanoparticles were further combined with Pani via an in situ polymerization method. For comparison purposes, Pani composites were also synthesized in the presence undoped TiO2. The photocatalyst and the composites were characterized by standard analytical techniques such as FTIR, XRD, SEM, EDX and UV–Vis spectroscopies. Fe–TiO2 and its composites exhibited enhanced photocatalytic activity under ultraviolet light irradiation. Improved photocatalytic activity of Fe–TiO2 was attributed to the dopant Fe ions hindering the recombination of the photoinduced charge carriers. Pani/Fe–TiO2 composite with 30?wt.% of TiO2 nanoparticles achieved 28% dye removal and the discoloration rate of methylene blue for the sample was 0.0025?min?1. FTIR, XRD, SEM, EDX and UV–Vis spectroscopies supported the idea that Fe ions integrated into TiO2 crystal structure and Pani composites were successfully synthesized in the presence of the photocatalyst nanoparticles. The novelty of this study was to investigate the photocatalytic activity of Pani composites, containing iron doped TiO2 and to compare their results with that of Pani/TiO2. 相似文献
84.
Ozcan Yalcinkaya Harun Ciftci Cigdem Er Caliskan Ozge Kalender Ali Rehber Turker 《光谱学与光谱分析》2018,38(4):1283-1289
Hybrid nanomaterials have attracted considerable interest in environmental science, analytical chemistry and atomic spectroscopy. In the present study, a column solid phase extractioo procedure was developed for the separation and preconcentration of indium in various matrixes by using hybrid nanomaterial B2O3/ZrO2 (HNMBZ). Various experimental and analytical parameters such as sample solution pH, sample solution volume, flow rate of sample solution and eluent, volume and concentration of eluent aod amount of HNMBZ, effect of common matrix ions and capacity of sorbent were investigated. The adsorbed metal ions on HNMBZ were eluted with 6 mL of 1 mol·L-1 HNO3 solutions and their concentrations were determined by high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS). Under the optimized conditions, detection limits for indium for 3 pixels and 5 pixels were found as 0.20 and 0.16 μg·L-1, respectively. The accuracy of the procedure was checked by spiked water samples. The developed procedure was successfully applied to real samples for the separation and determination of indium. 相似文献
85.
A novel and rapid laser ablation method for the fabrication of diffractive optical elements (DOE) in ZnSe that takes advantage of the relatively low intensity damage threshold of the material is presented. The structures were characterized in terms of their shape and diffraction efficiency at normal incidence under 10.6 μm radiation for TE and TM polarizations. Sample surface polishing as well as the possible effect of the melted zone and structural modification of the material around the ablated region on the power transmission capability of the grating are also discussed. 相似文献
86.
This paper presents an innovative method of measuring and assessing financial performance for hospitals using data envelopment analysis (DEA). A 6% national sample of acute care hospitals was used to compare conventional ratio analysis with the financial performance index (FPI), an aggregate measure of financial performance, developed in this study. The results showed that FPI has captured what various financial ratios indicate independently. The development of a FPI across many financial ratios eases the comparison of an individual hospital with its peers. Development and uses of a FPI can also be applied to other industries. 相似文献
87.
Continuous loop averaging deconvolution (CLAD) is a new general mathematical theory and method developed to deconvolve overlapping auditory evoked responses obtained at high stimulation rates. Using CLAD, arbitrary stimulus sequences are generated and averaged responses deconvolved. Until now, only a few special stimulus series such as maximum length sequences (MLS) and Legendre sequences (LGS) were capable of performing this task. A CLAD computer algorithm is developed and implemented in an evoked potential averaging system. Computer simulations are used to verify the theory and methodology. Auditory brainstem responses (ABR) and middle latency responses (MLR) are acquired from subjects with normal hearing at high stimulation rates to validate and show the feasibility of the CLAD technique. 相似文献
88.
The A/B ring synthon 13, previously converted into daunomycinone(6) by Keay and Rodrigo,6 has been prepared in seven steps and 38% overall yield using benzamide directed ortho metalation strategy. Significant steps are: the incorporation of a four-carbon Grignard unit (10) into 9, dibal reduction of 11, and intramolecular aldol condensation of the resulting product 12 to give the dihydronaphthalene 13. 相似文献
89.
This study aimed to evaluate the photocatalytic activities of poly(methyl methacrylate) (PMMA)/titanium dioxide (TiO2) nanofiber mat. TiO2 nanoparticles in crystal phase were first prepared by sol-gel process and then PMMA/TiO2 nanofiber mat was prepared through electrospinning. The composite (PMMA/TiO2) nanofiber mat was compared with that of pure PMMA nanofiber mat through performing FTIR and UV-Vis spectroscopy, scanning electron microscopy, thermogravimetric analysis, weight loss and water contact angle measurements. The photocatalytic activity of PMMA/TiO2 nanofiber mat was evaluated by investigating both the photocatalytic decomposition of a model dye, methylene blue, and photocatalytic degradation of the composite nanofiber mat in the ambient air under ultraviolet light irradiation. 相似文献
90.
Cemile Ozcan Ulviye Kanburoglu Cebi Mehmet Ali Gurbuz Selcuk Ozer 《Chromatographia》2017,80(6):941-950
Sunflower agriculture is an important subsector that plays a key role in the economy of Turkey, contributing 1.38 million tonnes. The aim of this study is to investigate the levels of imidazolinone (IMI) group herbicides in Thrace Region, Turkey. In particular, we aimed to determine the residue levels of imazamox, a herbicide used in sunflower production in Thrace Region, in soil, different parts of plant, and seed. Five herbicides were identified in sunflower samples using solid–liquid extraction with gas chromatography–electrospray ionization mass spectrometry (GC–EI–MS) on single-quadruple instruments in selected ion monitoring (SIM) mode. The optimized conditions were found to be mobile-phase flow rate of 1 mL min?1 and injection volume of 3 μL in programmed temperature vaporization (PTV) solvent vent mode. The recovery of imazamox, imazaquin, imazethapyr, imazapyr, and imazapic from sunflower plant and soil was 89 and 99, 104 and 105, 92 and 93, 96 and 92, and 99 and 96%, respectively. 相似文献