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921.
Sonoporation—transient plasma membrane perforation elicited by the interaction of ultrasound waves with microbubbles—has shown great potential for drug delivery and gene therapy. However, the heterogeneity of sonoporation introduces complexities and challenges in the realization of controllable and predictable drug delivery. The aim of this investigation was to understand how non-acoustic parameters (bubble related and bubble-cell interaction parameters) affect sonoporation. Using a customized ultrasound-exposure and fluorescence-imaging platform, we observed sonoporation dynamics at the single-cell level and quantified exogenous molecular uptake levels to characterize the degree of sonoporation. Sonovue microbubbles were introduced to passively regulate microbubble-to-cell distance and number, and bubble size. 1 MHz ultrasound with 10-cycle pulse duration and 0.6 MPa peak negative pressure were applied to trigger the inertial collapse of microbubbles. Our data revealed the impact of non-acoustic parameters on the heterogeneity of sonoporation. (i) The localized collapse of relatively small bubbles (diameter, D < 5.5 μm) led to predictable sonoporation, the degree of which depended on the bubble-to-cell distance (d). No sonoporation was observed when d/D > 1, whereas reversible sonoporation occurred when d/D < 1. (ii) Large bubbles (D > 5.5 μm) exhibited translational movement over large distances, resulting in unpredictable sonoporation. Translation towards the cell surface led to variable reversible sonoporation or irreversible sonoporation, and translation away from the cell caused either no or reversible sonoporation. (iii) The number of bubbles correlated positively with the degree of sonoporation when D < 5.5 μm and d/D < 1. Localized collapse of two to three bubbles mainly resulted in reversible sonoporation, whereas irreversible sonoporation was more likely following the collapse of four or more bubbles. These findings offer useful insight into the relationship between non-acoustic parameters and the degree of sonoporation. 相似文献
922.
The minimum error correction (MEC) model for haplotype reconstruction is efficient only when the error rate in SNP fragments is low. In order to improve reconstruction rate, additional genotype information is added into MEC model as an extension to MEC model. In this paper, we first establish a new mathematical model for haplotype assembly problem with genotype information. Several properties of the mathematical model are proved. Then an iterative local-exhaustive search algorithm is proposed based on the model and its properties. The main idea is to find the optimal pair among 2(l-1) (l denotes the number of heterozygous sites of a genotype) haplotype pairs by performing local exhaustive search for the promising haplotype pair step by step. By experiments and comparison, extensive numerical results on real data and simulated data indicate that our algorithm outperforms the other algorithms in terms of efficiency and robustness. 相似文献
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925.
Jaffar Ali 《Journal of Mathematical Analysis and Applications》2007,335(2):1013-1019
Consider the system
926.
Given a connected edge-regular graph Γ with parameters (v, k, λ) and b 1 = k ? λ ? 1, we prove that in the case k ≥ 3b 1 ?2 either |Γ2(u)|(k?2b 1 + 2) < kb 1 for every vertex u or Γ is a polygon, the edge graph of a trivalent graph without triangles that has diameter greater than 2, the icosahedral graph, the complete multipartite graph K r×2, the 3 × 3-grid, the triangular graph T(m) with m ≤ 7, the Clebsch graph, or the Schläfli graph. 相似文献
927.
The electrochemical behavior of kryptand 222 at the interface between a mercury electrode and an aqueous solution is studied by the impedance spectroscopy, polarography, and cyclic voltammetry methods. It is established that kryptand 222 possesses high surface activity at this interface. Adsorption parameters of kryptand 222 are found on the basis of the model of two parallel capacitors supplemented by the Frumkin isotherm by the regression analysis method. The potential dependences of the differential capacitance (C,E curves), calculated using these parameters satisfactorily agree with experiment. It is shown that the maximum in the C,E curves in the region of negative potentials is caused by catalytic process of hydrogen evolution. 相似文献
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929.
Two-dimensional nitrogen-carbon NMR correlation spectra have been derived by a new reconstruction technique based on standard two-dimensional HMQC and HMBC spectra, and operating with natural 15N and 13C isotopic abundances. Compared with conventional three-dimensional spectroscopy in which 15N and 13C spins must be present in the same molecule, the reconstruction method offers two orders of magnitude improvement in sensitivity. Vitamin B-12 serves as an illustrative example. 相似文献
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