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131.
Marzieh Vafaee Mostafa M. Amini Ezzatollah Najafi Omid Sadeghi Vahid Amani 《Journal of Sol-Gel Science and Technology》2012,64(2):411-417
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
132.
We perform wide-field microscopy to investigate the photobleaching of organic fluorophores embedded in the polymeric host PMMA. Our experimental arrangement facilitates the comparison between the ensemble and single molecule data. We characterize the photostability of dye molecules of various families by measuring the ‘bleaching number’, defined as the average number of photons a molecule emits until photobleaching occurs. In particular, we have analysed the dependence of the bleaching number on the presence of oxygen. Surprisingly, we find an improvement of photostability in the presence of oxygen for ionic dyes (DiI, TMR, Rh6G, Alexa 546), suggesting that oxygen quenches the photoactive triplet state, but it only indirectly contributes to photochemistry. In contrast, we observe that photobleaching of the aromatic hydrocarbon is strongly enhanced by oxygen. 相似文献
133.
Mohammad Ali Zolfigol Vahid Khakyzadeh Ahmad Reza Moosavi-Zare Abdolkarim Zare Seyedeh Bahareh Azimi Zhila Asgari Alireza Hasaninejad 《Comptes Rendus Chimie》2012,15(8):719-736
In this work, some novel sulfonic acid functionalized imidazolium salts (SAFIS), as a new category of ionic liquids, are synthesized by eco-friendly and simple procedures, and used as highly efficient and reusable catalysts to promote the following one-pot multicomponent organic transformations under solvent-free conditions: (i) the synthesis of 14-aryl-14H-dibenzo[a,j]xanthenes from β-naphthol (2 eq.) and arylaldehydes (1 eq.), (ii) the preparation of tetrahydrobenzo[a]xanthene-11-ones from β-naphthol, arylaldehydes and dimedone, and (iii) the synthesis of 1,8-dioxo-octahydroxanthenes from dimedone (2 eq.) and aromatic aldehydes (1 eq.). Environmentally benign, simple methodologies, easy workup procedure, clean reaction, short reaction time, high yield and easy preparation of the catalysts are some advantages of this work. 相似文献
134.
In this paper, we consider the main problem of variational calculus when the derivatives are Riemann?CLiouville-type fractional with incommensurate orders in general. As the most general form of the performance index, we consider a fractional integral form for the functional that is to be extremized. In the light of fractional calculus and fractional integration by parts, we express a generalized problem of the calculus of variations, in which the classical problem is a special case. Considering five cases of the problem (fixed, free, and dependent final time and states), we derive a necessary condition which is an extended version of the classical Euler?CLagrange equation. As another important result, we derive the necessary conditions for an optimization problem with piecewise smooth extremals where the fractional derivatives are not necessarily continuous. The latter result is valid only for the integer order for performance index. Finally, we provide some examples to clarify the effectiveness of the proposed theorems. 相似文献
135.
136.
The complex [Pt(5,5′-dmbipy)Cl4] (1) (5,5′-dmbipy is 5,5′-dimethyl-2,2′-bipyridine) was prepared from the reaction of H2PtCl6·6H2O with 5,5′-dimethyl-2,2′-bipyridine in methanol. The same method was employed to make [Pt(6-mbipy)Cl4] (2) (6-mbipy is 6-methyl-2,2′-bipyridine). Both complexes were characterized by elemental analysis, IR, UV–Vis, 1H NMR, 13C NMR and 195Pt NMR spectroscopy. Their solid state structures were determined by the X-ray diffraction method. 相似文献
137.
In this paper, guaranteed cost synchronization (GCS) problem for chaotic dynamic systems with uncertainty in the controller is investigated. Based on the Lyapunov stability theory and LMI (linear matrix inequality) technique, two criteria for the existence of the nonfragile controller for GCS are obtained in terms of LMIs such that the closed-loop error system becomes asymptotically stable and suitable level of performance is guaranteed. Numerical simulation illustrates the feasibility of the proposed control scheme. 相似文献
138.
Dry-Type Cast Resin Distribution Transformers (CRT) is the secondgeneration
of air-cooled distribution transformers where oil is replaced by resin
for electrical insulation. CRT transformers may installed indoor adjacent to or
near residential areas since they are clean and safe comparing to the conventional
transformers. But, as it is obvious, noise discrepancy is intrinsically accompanied
with all types of transformers and is inevitable for CRT transformers too. Minimization
of noise level caused by such these transformers has biological and ergonomic
importance. As it is known the core of transformers is the main source of
the noise generation. In this paper, experimental and numerical investigation is
implemented for a large number of fabricated CRT transformers in IT Co (Iran
Transfo Company) to evaluate the effective geometrical parameters of the core
on the overall sound level of transformers. Noise Level of each sample is measured
according to criteria of IEC60651 and is reported in units of Decibel
(dB). Numerical simulation is done using noncommercial version of ANSYS
Workbench software to extract first six natural frequencies and mode shapes of
CRT cores which is reported in units of Hz. Three novel non-dimensional variables
for geometry of the transformer core are introduced. Both experimental
and numerical results show approximately similar response to these variables.
Correlation between natural frequencies and noise level is evaluated statistically.
Pearson factor shows that there is a robust conjunction between first two natural
frequencies and noise level of CRTs. Results show that noise level decreases as
the two first natural frequencies increases and vice versa, noise level increases
as the two natural frequencies of the core decreases. Finally the noise level
decomposed to two parts. 相似文献
139.
The recently improved finite order BFT Hamiltonian embedding method is applied to the two dimensional chiral bosons in non-commutative space. It is then systematically converted to a first class constraint model. Performing the momentum integrations, the corresponding fully gauge symmetry Lagrangian as well as its partition function in phase space are obtained. 相似文献
140.
In this paper the generalized nonlinear Euler differential equation t2k(tu′)u′′+t(f (u)+k(tu′))u′+g(u) = 0 is considered. Here the functions f (u), g(u) and k(u) sat-isfy smoothness conditions which gu... 相似文献