Differential scanning calorimetry (DSC), isothermal stress testing–Fourier transform infrared spectroscopy (IST–FTIR), isothermal stress testing–high-performance liquid chromatography, and powder X-ray diffraction (PDRX) were used as screening techniques for assessing the compatibility of tobramycin with some currently employed ophthalmic excipients. In the first phase of the study, DSC was used as a tool to detect any interaction. The absolute value of the difference between the enthalpy of the pure tobramycin melting peak and that of its melting peak in the different analyzed mixtures was chosen as a parameter of the drug–excipient interaction degree. DSC results demonstrated that benzalkonium chloride, monobasic sodium phosphate, boric acid, edetate disodium, sodium metabisulfite, thimerosal, and potassium sorbate interact with tobramycin. Taking into account these results, it could be suggested that some of the changes observed in the IST–FTIR spectra of binary blends of tobramycin and some of the excipients would account for a possible interaction between the mixture component. In this study, PDRX did not provide much information, since only tobramycin–thimerosal interactions could be detected. DSC and IST–FTIR are suitable and simple methods for the detection of potential incompatibilities between active pharmaceutical ingredient (API) and excipients.
This research aims to investigate the interaction between phytohemagglutinin-L (PHA-L) and sialic acid, which is abundant on the breast cancer cell (MCF-7) surface and displays monosaccharide characteristics, by experimental and computational methods. Experimentally, CdSe/CdS nanoparticles (QDs) were synthesized; PHA-L was conjugated with QDs and labeled with 125I. Radiolabeling yield was found to be 97 ± 1.2 %. Afterwards, in vitro bioaffinities of radiolabeled PHA-L conjugated QDs have been investigated on MCF-7 cells and it has been observed that the cell incorporation increased with time. The results indicated that 125I labeled QD-PHA-L conjugates represent significant affinity on MCF-7 cells. In the second step of the study, the crystal structure of carbohydrate interaction surface of PHA-L was extracted from the crystal structure of PHA-L. The interactions between this surface and sialic acid were calculated by computational tools. These calculations revealed specific interactions between PHA-L and sialic acid. Semi-empirical methods, PM3 and AM1, were used in these calculations. Significant outcomes have been obtained from the experimental and computational studies and these results demonstrated that PHA-L may be an effective agent for imagining MCF-7 cells. 相似文献
Due to the widespread use of acoustic arrays, optimisation techniques for array design, focused on improving array performance, have been widely published. This paper exploits the statistical relation between different measures of sidelobe levels and the spacing of elements in random linear arrays made up of a small number of sensors. This paper defines the methodology to obtain maximum probability functions, associating array geometry and performance. These maximum probability functions allow a pre-selection of those array geometries that are more likely to be associated to specified sidelobe level values. This pre-selection results in a significantly reduced computational burden. 相似文献
The spatial distribution of tiny holes in sheet materials generated by means of electrical discharges is investigated using spatial statistics techniques. It is shown that whereas the holes appear to be randomly distributed according to a Poisson point pattern, there is in fact a small region around each hole in which the generation of a new one is statistically inhibited as a consequence of the lower impedance path offered by the already made hole. The resulting pattern is known in spatial statistics as a point process with a soft-core inhibition potential, which can be characterized using the pair correlation function. 相似文献
We develop a strategy to compute all liftings of a Nichols algebra over a finite dimensional cosemisimple Hopf algebra. We produce them as cocycle deformations of the bosonization of these two. In parallel, we study the shape of any such lifting. 相似文献