A series of seven-membered ditopic ring-expanded N-heterocyclic carbene (dre-NHC) precursors, bearing sterically demanding and electron-rich aryl groups, were synthesised in moderate yields via the reaction of 1,2,4,5-tetrakis(bromomethyl)benzene with the corresponding N,N′-diarylformamidines in the presence of K2CO3 in acetonitrile under an air atmosphere. All new compounds were characterised by HRMS, NMR spectroscopy, and microanalysis, as well as X-ray crystallography for compound 1c. The development of an efficient catalytic system for the Suzuki-Miyaura coupling reaction of aryl chlorides with various boronic acids was also investigated using the in situ generated dre-NHC ligands. 相似文献
Thin film CdIn2Te4/CdS solar cells were deposited onto the ITO-coated glass substrate by electron beam evaporation (e-beam) technique, and the the effect of annealing on their structural properties is studied. The annealing was performed under nitrogen atmosphere for 1 h. The manufactured solar cells were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray (EDAX) analysis. Crystallite size (D), inter-planer distance (d) and lattice constant (a) values were calculated for the thin film solar cell from XRD data. Annealed samples display well defined XRD patterns with three diffraction peaks. We observed increased peak intensity in the annealed films. EDAX analysis showed that only CdIn2Te4 is present in absorber layer and CdS is found in the window layer, but no impurity atoms are present the structure. It is observed that surface roughness of the annealed films incresed, according to SEM images. The I–V characteristics show that the current is increased for annealed thin films solar cells.
Oxalic acid adsorption from aqueous solution is studied in this work. Multi-walled carbon nanotubes (MWCNT) were used as an adsorbent. The investigated adsorption variables are equilibrium time, initial acid concentration, and temperature. The experimental results were presented using equilibrium isotherm and kinetic models. The used equilibrium models are Langmuir, Freundlich, and Temkin adsorption isotherms. And the kinetic models are Elovich, Lagergren pseudo-first-order and pseudo-second-order kinetic models. The thermodynamics studies were carried out at three different temperatures: 278, 298, and 318 K. Langmuir isotherm was the best fitted equilibrium model for the experimental data. The all applied kinetic models fitted the data suitably. 相似文献
Furo[3,2‐c]pyran‐4‐ones, which possess a natural‐product skeleton, are synthesized via a simple, one‐pot, three‐component reaction of furan‐2,3‐diones with dialkyl acetylenedicarboxylates and Ph3P. 相似文献
A very sensitive and highly specific heterogeneous immunoassay system, based on surface-enhanced Raman scattering (SERS) and
gold nanoparticles, was developed for the detection of bacteria and other pathogens. Two different types of gold nanoparticles
(citrate-stabilized gold nanosphere and hexadecyltrimethylammonium bromide (CTAB)-stabilized gold nanorod particles) were
examined and this immunoassay was applied for the detection of Escherichia coli. Raman labels were constructed by using these spherical and rod-shaped gold nanoparticles which were first coated with 5,5′-dithiobis(2-nitrobenzoic
acid) (DTNB) and subsequently with a molecular recognizer. The working curve was obtained by plotting the intensity of the
SERS signal of the symmetric NO2 stretching of DTNB at 1,333 cm−1 versus the concentration of the E. coli. The analytical performance of gold particles was evaluated via a sandwich immunoassay, and linear calibration graphs were
obtained in the E. coli concentration range of 101–105 cfu/mL with a 60-s accumulation time. The sensitivity of the Raman label fabricated with gold nanorods was more than three
times higher than spherical gold nanoparticles. The selectivity of the developed sensor was examined with Enterobacter aerogenes and Enterobacter dissolvens, which did not produce any significant response. The usefulness of the developed immunoassay to detect E. coli in real water samples was also demonstrated. 相似文献
Tannic acid, a naturally occurring plant polyphenol, is composed of a central glucose molecule derivatized at its hydroxyl groups with one or more galloyl residues. In the present paper, we examines the in vitro radical scavenging and antioxidant capacity of tannic acid by using different in vitro analytical methodologies such as 1,1-diphenyl-2-picryl-hydrazyl free radical (DPPH) scavenging, 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, total antioxidant activity determination by ferric thiocyanate, total reducing ability determination using by Fe3+–Fe2+ transformation method, superoxide anion radical scavenging by riboflavin–methionine-illuminate system, hydrogen peroxide scavenging and ferrous ions (Fe2+) chelating activities. Also, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), α-tocopherol and trolox, a water-soluble analogue of tocopherol, were used as the reference antioxidant radical scavenger compounds.Tannic acid inhibited 97.7% lipid peroxidation of linoleic acid emulsion at 15 μg/mL concentration. On the other hand, the above mentioned standard antioxidants indicated an inhibition of 92.2%, 99.6%, 84.6% and 95.6% on peroxidation of linoleic acid emulsion at 45 μg/mL concentration, respectively. In addition, tannic acid had an effective DPPH scavenging, ABTS+ radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, Fe3+ reducing power and metal chelating on ferrous ions activities. Also, those various antioxidant activities were compared to BHA, BHT, α-tocopherol and trolox as references antioxidant compounds. The present study shows that tannic acid is the effective natural antioxidant component that can be used as food preservative agents or nutraceuticals. 相似文献
Rigorous numerical modeling of optical systems has attracted interest in diverse research areas ranging from biophotonics to photolithography. We report the full-vector electromagnetic numerical simulation of a broadband optical imaging system with partially coherent and unpolarized illumination. The scattering of light from the sample is calculated using the finite-difference time-domain (FDTD) numerical method. Geometrical optics principles are applied to the scattered light to obtain the intensity distribution at the image plane. Multilayered object spaces are also supported by our algorithm. For the first time, numerical FDTD calculations are directly compared to and shown to agree well with broadband experimental microscopy results. 相似文献
We analyze the discrete nonlinear Schrödinger equation with a saturable nonlinearity through the (G′/G)-expansion method to present some improved results. Three types of analytic solutions with arbitrary parameters are constructed; hyperbolic, trigonometric, and rational which have not been explicitly computed before. 相似文献
In recent years, a sufficient condition for determining chaotic behaviours of the non-linear systems has been characterized by the negative Schwarzian derivative (Hac?bekiro?lu et al, Nonlinear Anal.: Real World Appl.10, 1270 (2009)). In this work, the Schwarzian derivative has been calculated for investigating the quantum chaotic transition points in the high-temperature superconducting frame of reference, which is known as a nonlinear dynamical system that displays some macroscopic quantum effects. In our previous works, two quantum chaotic transition points of the critical transition temperature, Tc, and paramagnetic Meissner transition temperature, TPME, have been phenomenologically predicted for the mercury-based high-temperature superconductors (Onba?l? et al, Chaos, Solitons and Fractals42, 1980 (2009); Aslan et al, J. Phys.: Conf. Ser.153, 012002 (2009); Çataltepe, Superconductor (Sciyo Company, India, 2010)). The Tc, at which the one-dimensional global gauge symmetry is spontaneously broken, refers to the second-order phase transition, whereas the TPME, at which time reversal symmetry is broken, indicates the change in the direction of orbital current in the system (Onba?l? et al, Chaos, Solitons and Fractals42, 1980 (2009)). In this context, the chaotic behaviour of the mercury-based high-temperature superconductors has been investigated by means of the Schwarzian derivative of the magnetic moment versus temperature. In all calculations, the Schwarzian derivatives have been found to be negative at both Tc and TPME which are in agreement with the chaotic behaviour of the system. 相似文献