The aza-Michael addition of 1,2,3,6-tetrahydrophthalimide with symmetrical fumaric esters has been performed efficiently in a solvent-free system at 100 °C and using 1,4-diazabicyclo[2.2.2]octane (DABCO) as a base in the presence of tetrabutylammonium bromide (TBAB). The products were obtained in good to high yields within 2.5-7.0 h. This reaction worked well on linear alkyl fumarates and was not effective with nonlinear alkyl fumarates. Although the reaction was also applicable to acrylates such as n-butyl acrylate, methacrylates and crotonates were not suitable Michael acceptors for this reaction. 相似文献
Crystal size distribution as a function of power in ultrasound ablation is simulated by using a theoretical method based on population and radius of bubbles. In this method, population and radius of bubbles are related to ultrasound power and Debye temperature of crystals. The best power for production of crystals with uniform size is obtained from the theory. In addition, it is shown that the population of bubbles effects the radius of the productions and the radius of bubbles influences the population of products. Results from the theory are supported by experimental results. 相似文献
Stability of a functionally graded (FG) micro-beam, based on modified couple stress theory (MCST), subjected to nonlinear electrostatic pressure and thermal changes regarding convection and radiation, is the main purpose of this paper. It is assumed that the functionally graded beam, made of metal and ceramic, follows the volume fraction definition and law of mixtures, and its properties change as an exponential function through its thickness. By changing the ceramic constituent percent of the bottom surface, five different types of the micro-beams are investigated. The static pull-in voltages in presence of temperature changes are obtained by using step-by-step linearization method (SSLM) and, by adapting Runge–Kutta approach, the dynamic pull-in voltages are obtained numerically. Though the temperature distribution through the thickness of FG micro-beam (due to its too small measurement) is considered uniform, owing to the different thermal expansions of layers, temperature changes cause deflection in the micro-beam, and consequently affect pull-in values. Hence the profound effects of different material constituent over the pull-in voltages are illustrated and it is graphically displayed that how in some cases neglecting components of the couple stress leads to inaccurate results. 相似文献
In the past two decades tissue adhesives and sealants have revolutionized bleeding control and wound healing. This paper focuses on existing tissue adhesive design, their structure, functioning mechanism, and their pros and cons in wound management. It also includes the latest advances in the development of new tissue adhesives as well as the emerging applications in regenerative medicine. We expect that this paper will provide insightful discussion on tissue bioadhesive design and lead to innovations for the development of the next generation of tissue bioadhesives and their related biomedical applications.
[140Nd] labeled 5,10,15,20-tetraphenylporphyrin ([140Nd]-TPP) as a tumor–avid complex with a β-emitting radionuclide for evaluating its potential for target tumor therapy is reported. This complex was prepared using freshly prepared [140Nd] NdCl3 (purified by amino functionalized MCM-41 nano resin and commercial cation exchanger resins) and 5,10,15,20-tetraphenylporphyrin (H2TPP).Stability of the complex was investigated in final formulation and human serum for 24 h and the partition coefficient was calculated. The biodistribution of the labeled compound in vital organs of Swiss mice bearing fibro sarcoma tumor was studied using scarification studies and positron emission tomography imaging up to 4 h. 相似文献
The application of molecularly imprinted polymers in the selective adsorption of macromolecules such as proteins by monolithic protein‐imprinted columns requires a macroporous structure, which can be provided by cryogelation at low temperature in which the formation of ice crystals gives a porous structure to the molecularly imprinted polymer. In this study, we applied this technique to synthesize lysozyme‐imprinted polyacrylamide cryogels containing 8% w/v of total monomers and 0.3% w/v of lysozyme. The synthesized cryogel was sponge‐like and elastic with very fast swelling and reshaping properties, showing a swelling ratio of 24.5 ± 3 and gel fraction yield of about 72%. It showed an imprinting effect of 1.58 and a separation factor of 1.37 for cytochrome c as the competing protein. Adsorption studies on the cryogel revealed that it follows the Langmuir isotherm, with a maximum theoretical adsorption capacity of 36.3 mg lysozyme per gram of cryogel. Additionally, it was shown that a salt‐free rebinding solution at low flow rate and pH = 7.0 is favorable for lysozyme rebinding. This kind of monolithic column promises a wide range of application in separation of various biomolecules due to its preparation simplicity, good rebinding characteristics, and macroporosity. 相似文献
A method has been established for simultaneous determination of sodium sulfate, sodium carbonate, and sodium tripolyphosphate in detergent washing powder samples based on attenuated total reflectance Fourier transform IR spectrometry in the mid-IR spectral region (800-1550 cm(-1)). Genetic algorithm (GA) wavelength selection followed by feed forward back-propagation artificial neural network (BP-ANN) was the chemometric approach. Root mean square error of prediction for BP-ANN and GA-BP-ANN was 0.0051 and 0.0048, respectively. The proposed method is simple, with no tedious pretreatment step, for simultaneous determination of the above-mentioned components in commercial washing powder samples. 相似文献
Pharmaceutical pellets are spherical or nearly spherical multi-unit dosage forms designed to optimize pharmacokinetics and pharmacodynamics features of drug release. The distribution of the pharmaceutical ingredients in the layers and core is a very important parameter for appropriate drug release, especially for pellets manufactured by the process of layer gain. Physical aspects of the sample are normally evaluated by Scanning Electron Microscopy (SEM), but it is in many cases unsuitable to provide conclusive chemical information about the distribution of the pharmaceutical ingredients in both layers and core. On the other hand, methods based on spectroscopic imaging can be very promising for this purpose. In this work, a Near-Infrared Chemical Imaging (NIR-CI) method was developed and applied to the analysis of diclophenac sodium pellets. Since all the compounds present in the sample were known in advance, Classical Least Squares (CLS) was used for calculations. The results have shown that the method was capable of providing chemical information about the distribution of the active ingredient and excipients in the core and coating layers and therefore can be complementary to SEM for the pharmaceutical development of pellets. 相似文献