Nonlinear Dynamics - In this article, the effects of the changes in the mass of the floating wind turbine (as a multi-body system) on its nonlinear vertical vibrations are investigated. The... 相似文献
As redox-active based supercapacitors are known as highly desirable next-generation supercapacitor electrodes, the targeted design of two ferrocene-functionalized (Fc(COOH)2) clusters based on coinage metals, [(PPh3)2AgO2CFcCO2Ag(PPh3)2]2 ⋅ 7 CH3OH (SC1: super capacitor) and [(PPh3)3CuO2CFcCO2Cu(PPh3)3] ⋅ 3 CH3OH (SC2), is reported. Both structures are fully characterized by various techniques. The structures are utilized as energy storage electrode materials, giving 130 F g−1 and 210 F g−1 specific capacitance at 1.5 A g−1 in Na2SO4 electrolyte, respectively. The obtained results show that the presence of CuI instead of AgI improves the supercapacitive performance of the cluster. Further, to improve the conductivity, the PSC2 ([(PPh3)2CuO2CFcCO2]∞), a polymeric structure of SC2, was synthesized and used as an energy storage electrode. PSC2 displays high conductivity and gives 455 F g−1 capacitance at 3 A g−1. The PSC2 as a supercapacitor electrode presents a high power density (2416 W kg−1), high energy density (161 Wh kg−1), and long cycle life over 4000 cycles (93 %). These results could lead to the amplification of high-performance supercapacitors in new areas to develop real applications and stimulate the use of the targeted design of coordination polymers without hybridization or compositions with additive materials. 相似文献
This paper addresses modelling the nature of interactions between β-CD and some coumarins including recently reported novel sulphur analogues to form inclusion complexes of appealing medicinal, photochemical and photophysical properties. The binding energy and the total stabilization energy (EONIOM) are used to confirm the most favorable inclusion complex structure. Thermodynamic parameters reveal exothermic inclusion reaction in gas phase. Thermal stability of fluorescent enzyme substrate of coumarin nucleus increases in the order: gas?<?cyclohexane?<?water, indicating better stability in water. Furthermore, molecular characteristics such as optimized geometries, MO’s and electrostatic potential energy map surfaces and energies are reported and correlated with some reactivity indices. Our results validated the experimentally available data reported in the literature. Inclusion complexes of β-CD with coumarins should result in improving its laser efficiency in environmentally benign aqueous medium. 相似文献
A rapid and simple approach for the preconcentration and determination of catechin from pistachio green hull samples has been proposed by surfactant-assisted dispersive liquid–liquid microextraction followed by UV–Vis spectrophotometry (SADLLME/UV–Vis). This method involved the formation of a catechin complex with cetylpyridinium chloride (CPC) as cationic surfactant, and subsequently, DLLME was applied to extract the catechin–CPC complex into chloroform. Different parameters affected the extraction efficiency were optimized by central composite design (CCD) and response surface methodology (RSM). In optimum condition, the calibration curve was linear in the range of 0.4–5 µg mL??1 of catechin with correlation coefficient of 0.9982. The relative standard deviation based on five replicated analyses of 1 µg mL??1 catechin was 1.85%. The proposed method was successfully applied for preconcentration and determination of trace amounts of catechin in pistachio hull samples. 相似文献
The 2‐ethoxy carbonyl methylene thiazol‐4‐one ( 3 ) reacts with acetophenone ( 4 ) to give the ethyl 2‐(4‐oxo‐4,5‐dihydro‐thiazol‐2‐yl)‐3‐phenyl‐2‐butenoate ( 5 ). The reactivity of the latter product towards aromatic aldehydes 6a‐d , cyanomethylene reagents 9a,b , aromatic aldehydes 13a‐d , phenylisothiocyanate ( 16 ), elemental sulfur and aromatic amines ( 20a‐c ) was studied to give arylidene, pyridine, thiophene and anilide derivatives. Some of the newly synthesized derivatives were used to synthesize fused derivatives. The antimicrobial activities of the newly synthesized products were tested in vitro for antimicrobial activity against two bacterial isolates, one saprophytic (Escherichia coli) and the other parasitic (Xanthomonas citri) and for antifungal activity against one saprophytic (Aspergillus fumigatus) and two phytopathogenics (Rhizoctonia solani and Fusarium oxysporum). 相似文献
Charge separation plays a key role in the conversion of solar energy into chemical energy for use in the redox reaction and as well as in the photocatalytic activity. In this study, SrTiO3 particles with different morphologies including irregular, tetrahexahedron, and cube were synthesized by an in situ solvothermal method. The photocatalytic activity of the synthesized nanoparticles was investigated in the photocatalytic decomposition of methylene blue under UV light irradiation. Tetrahexahedron SrTiO3 particles exhibited high decomposition activity (70 %), which is about two times higher than those of the irregular and cubic SrTiO3 particles. The high decomposition activity of tetrahexahedron SrTiO3 particles could be attributed to the improvement of charge separation achieved on different crystal facets. To reach a good charge separation, tetrahexahedron SrTiO3/TiO2 coupled nanoparticles were fabricated by impregnation method. Results showed that coupling tetrahexahedron SrTiO3 with TiO2 could produce efficient charge separation between tetrahexahedron SrTiO3 and TiO2 due to their matched band edges. In order to achieve better charge separation, the tetrahexahedron SrTiO3/90 %TiO2 sample was calcined at different temperatures in the 450–750 °C range. Tetrahexahedron SrTiO3/90 %TiO2 coupled nanoparticles calcined at 650 °C show high photocatalytic activity compared with other samples. The prepared samples were characterized by using various techniques such as X-ray diffraction, scanning electron microscopy, photoluminescence emission spectra, and UV–Vis diffuse reflectance spectroscopy. 相似文献
The emergence and prevalence of
multi-drug-resistant bacterial strains increase the potential for outbreaks of incurable infections. The discovery of novel antibiotics and pharmacological preparations requires the identification of novel bioactive small molecules. A specific, sensitive, and reliable quantification method using high-performance liquid chromatography (HPLC) with UV detection was developed for the determination of total persipeptides (A and B), which are cyclic pentapeptides found in the fermentation broth of Streptomyces zagrosensis UTMC 1154 that exhibit bioactivity against methicillin-resistant Staphylococcus aureus (MRSA). A simple liquid–liquid extraction (LLE) method using butanol was employed to extract persipeptides from the fermentation broth prior to HPLC analysis. The chromatographic separation of persipeptides and the internal standard, virginiamycin, was achieved with a gradient of acetonitrile and water on a C18 reversed-phase analytical column in a 25-min analytical run utilizing a flow rate of 0.8 mL min−1 and detection at 210 nm. The whole assay was validated, and the method presented a linear response range with a regression coefficient of determination R2 of 0.9996 for the quantification of persipeptides in the concentration range of 3.9–250.0 µg mL−1, as well as extraction recoveries ranging from 54.78 ± 9.83 % to 56.45 ± 16.33 %. The bias and the precision of the proposed method were <10 %. The detection and quantification limits for the persipeptides were 27 and 83 µg L−1, respectively.
A chemically modified electrode was constructed for rapid, simple, accurate, selective and highly sensitive simultaneous determination of Cu(II) and Cd(II) using square wave anodic stripping voltammetry. The electrode was prepared by incorporation of SiO2 nanoparticles, coated with a newly synthesized Schiff base, in carbon paste electrode. The limit of detection was found to be 0.28 ng mL?1 and 0.54 ng mL?1 for Cu(II) and Cd(II), respectively. The proposed chemically modified electrode was used for the determination of copper and cadmium in several foodstuffs and water samples. 相似文献
A new lignan glucoside, officinalioside (1), was isolated from n-BuOH fraction of the aerial parts of Borago officinalis L., together with four known compounds: actinidioionoside (2), roseoside (3), crotalionoside C (4) and kaempferol 3-O-β-D-galactopyranoside (5). The structure of the new compound was established by means of spectroscopic and chemical analyses. Compounds 1 and 2 showed a moderate DPPH radical scavenging activity (IC50: 52.6 ± 1.70 and 41.3 ± 0.25 μM, respectively) comparable with that of the standard trolox (16.6 ± 2.2 μM) without any significant cytotoxicity towards human cell line A549 (IC50 > 100 μM). 相似文献