Molecular Diversity - New selenopheno[2,3-e][1,2,4]triazolo[1,5-c]pyrimidine derivatives have been synthesized via Dimroth rearrangement by cyclocondensation of... 相似文献
Different nanoporous silica materials, MCM-41, MCM-48 and SBA-15, were modified by pyridine and their applications for oral drug delivery system were evaluated. These pyridine functionalized nanoporous silicas were loaded with a water insoluble diorganotin(IV) dichloride complex as an antitumor drug model and its release from them were investigated by changing pH. An efficient pH-responsive carrier system was constructed by coordination of the pyridine group in modified nonoporous materials to tin complex. In vitro, releasing of loaded tin complex was studied in three different kinds of fluids, including a simulated gastric medium and a simulated body fluid. The loading and releasing of the diorganotin(IV) dichloride from various modified nanoporous silicas and also a non-porous silica (SiO2) were investigated, and the results were compared. In addition, the effect of some factors such as pH, time of loading and releasing were investigated through this study. 相似文献
Efforts to prepare ethyl 3-phenyl-4-(trifluoromethyl)isoxazole-5-carboxylate (1) by developing a regioselective 1,3-dipolar cycloaddition between phenyl nitrile oxide and various 4,4,4-trifluoromethyl crotonates are described. The substitution at the C2-position of crotonate dipolarophile 4 significantly influenced the regiochemistry and yield of the cycloaddition. Enol and enol ether-based crotonates underwent regioselective cycloadditions with phenyl nitrile oxide to provide 4-trifluoromethyl isoxazoles in good yields. 相似文献
A new image encryption scheme, based on a total shuffling and parallel encryption algorithm is proposed in this paper. Two
chaotic systems have been used in the encryption algorithm to confuse the relationship between the plain-image and the cipher-image.
To make the encryption procedure more confusing and complex, the plain-image is first divided into 4 sub-images and then the
position of each sub-image is changed pseudo-randomly according to a logistic map. Next, a total shuffling matrix is used
to shuffle the position of pixels in the whole image and then sub-images are encrypted simultaneously in a parallel manner.
The experimental results on USC data base demonstrate that the proposed encryption algorithm has a low time complexity and
has the advantages of large key space and high security. Moreover, the robustness of this locally encryption method is much
more in contrast with other encryption schemes and the distribution of gray values has a random-like behavior in the encrypted
image. 相似文献
Journal of Thermal Analysis and Calorimetry - In recent years, nanofluids have been widely used to improve the performance of various energy systems due to their favourable thermo-physical and... 相似文献
Journal of Thermal Analysis and Calorimetry - Usage of natural gas in an internal combustion engine that has different combustion technologies is considered a possible solution to reduce engine... 相似文献
In this numerical study, laminar flow of water nanofluid/GNP–SDBS (graphene nanoplatelet–sodium dodecylbenzene sulfonate) for 0–0.1% solid nanoparticles mass fraction was investigated for Reynolds numbers of 50–1000 in 3D space via finite volume method. In the newly proposed microchannel design, the cooling fluid is moving in countercurrent in the upper and lower layers of the microchannels, and there are cavities and sinusoidal routes on the solid walls of the microchannel, and the presence of rectangular ribs on the flow centerline along the fluid path enhances mixing for cooling fluid and creates better heat transfer for warm surfaces. The results of this study show that this special design of the microchannel can have a substantial increase in Nusselt number and heat transfer so that in the considered geometry by adding solid nanoparticles mass fraction it is possible to increase average Nusselt number for each Reynolds number by approximately 20%. Also, the mixing of the fluid because of formation of secondary flows has a strong effect on making the temperature distribution uniform in the cooling fluid and solid bed (wall) of the microchannel, especially in the lower layer. The upper layer of the microchannel always has a lower temperature due to indirect contact with heat flux compared with the lower layer. In this study, by increasing Reynolds number and mass fraction of solid nanoparticles the Nusselt number is increased and heat resistance of the lower wall of the microchannel is reduced. Based on the investigation of flow field and heat transfer, the use of the proposed design of the microchannel is recommended for Reynolds number less than 300.
For the first time, the mutual influences of the intramolecular hydrogen bond (IMHB) and cation–π interactions in various complexes of salicylaldehyde, thiosalicylaldehyde and selenosalicylaldehyde with Li+, Na+, K+, Mg2+ and Ca2+ cations were studied. First, the strength of IMHB and cation–π interactions of the mentioned complexes by energetic, geometrical, spectroscopic, topological and molecular orbital parameters was evaluated and compared with the corresponding results of benzene–cation complexes and salicylaldehyde analogues. The results show that the coexistence of IMHB and cation–π interactions increases the IMHB strength and decreases the cation–π interactions. Second, the significance of π–electron delocalisation (π–ED) within the resonance-assisted hydrogen bond (RAHB) unit and aromaticity of benzene ring in the studied complexes were estimated by using the harmonic oscillator model of aromaticity and compared with the respective amounts of references. The results indicated that the mentioned coupling decreases the π–ED of RAHB unit and aromaticity of the benzene ring. In addition, it was found that variations in the strength of the interactions, π–ED and aromaticity, depend on the charge-to-radius ratio of cations. Finally, the effects of replacement of O by S and Se atoms in both of the mentioned cases were explored. 相似文献