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91.
The Hertel-Thirring cell model for unstable systems (of purely attractive particles) is solved in the canonical ensemble for arbitrary dimensions. The differences between the phase transitions found in the canonical and in the microcanonical ensemble are discussed. The cluster phase (with a complete collapse in the ground state) exhibits the nonextensive character of the cell model. The results of the cell model are compared with molecular-dynamics simulations of a one-dimensional model with a rectangular-well pair potential. The simulations support the relevance of the cell model to characterize basic properties of gravitational systems. 相似文献
92.
A discrete model for the estimation of the effect of random voids on the structural properties of a two-dimensional solid is presented. Triangular void cells are used to simulate randomly located micro-cracks.The proposed model is solved using Cell Method, a recent numerical method that allows a direct discrete formulation of balance equations. Both heterogeneities of the structure and stress concentrations due to voids distribution are taken into account by the model. Following an introduction, some aspects of Cell Method for plane elasticity that are relevant for this paper will be briefly recalled and results from simulations in the elastic field will be discussed. Next, the proposed model will be extended to plastic field and more simulations will be presented. Results show that this model can be successfully employed to assess the structural response of a 2D solid with randomly distributed voids. 相似文献
93.
Cell cycle regulates proliferative cell capacity under normal or pathologic conditions, and in general it governs all in vivo/in vitro cell growth and proliferation processes. Mathematical simulation by means of reliable and predictive models represents an important tool to interpret experiment results, to facilitate the definition of the optimal operating conditions for in vitro cultivation, or to predict the effect of a specific drug in normal/pathologic mammalian cells. Along these lines, a novel model of cell cycle progression is proposed in this work. Specifically, it is based on a population balance (PB) approach that allows one to quantitatively describe cell cycle progression through the different phases experienced by each cell of the entire population during its own life. The transition between two consecutive cell cycle phases is simulated by taking advantage of the biochemical kinetic model developed by Gérard and Goldbeter (2009) which involves cyclin-dependent kinases (CDKs) whose regulation is achieved through a variety of mechanisms that include association with cyclins and protein inhibitors, phosphorylation–dephosphorylation, and cyclin synthesis or degradation. This biochemical model properly describes the entire cell cycle of mammalian cells by maintaining a sufficient level of detail useful to identify check point for transition and to estimate phase duration required by PB. Specific examples are discussed to illustrate the ability of the proposed model to simulate the effect of drugs for in vitro trials of interest in oncology, regenerative medicine and tissue engineering. 相似文献
94.
《Comptes Rendus Chimie》2015,18(12):1335-1343
Zinc oxide has attracted wide research interest due to its unique properties. Its band gap width, high refractive index, high electrical conductivity, and high optical transmission in the visible, etc., have made it suitable for a variety of applications, such as gas sensors, varistors, optoelectronic devices, etc. The first part of the paper presents three methods for the synthesis of zinc oxide nanoparticles: sol–gel, polyol, and hydrothermal methods. Then, we report on the characteristics of the powders in terms of structure, composition and morphology as well as of in-vitro testing on cell cultures. The influence of the nanoparticles on cell viability was evaluated by the lactate dehydrogenase method. It turns out that all ZnO powders tested present high cytotoxicity. Also, it is found that the synthesis method significantly influences cell viability, the lowest one being obtained for nanopowders synthesized by the sol–gel method. 相似文献
95.
96.
Xiaojuan Gong Wenjing Lu Man Chin Paau Qin Hu Xin Wu Shaomin Shuang Chuan Dong Martin M.F. Choi 《Analytica chimica acta》2015
A fast and facile approach to synthesize highly nitrogen (N)-doped carbon dots (N-CDs) by microwave-assisted pyrolysis of chitosan, acetic acid and 1,2-ethylenediamine as the carbon source, condensation agent and N-dopant, respectively, is reported. The obtained N-CDs are fully characterized by elemental analysis, transmission electron microscopy, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction pattern, X-ray photoelectron spectroscopy, UV–vis absorption, and photoluminescence spectroscopy. Doping N heteroatoms benefits the generation of N-CDs with stronger fluorescence emission. As the emission of N-CDs is efficiently quenched by Fe3+, the as-prepared N-CDs are employed as a highly sensitive and selective probe for Fe3+ detection. The detection limit can reach as low as 10 ppb, and the linear range is 0.010–1.8 ppm Fe3+. The as-synthesized N-CDs have been successfully applied for cell imaging and detecting Fe3+ in biosystem. 相似文献
97.
Xi Dai Tao Zhang Zhi-Fang Du Xiang-Jian Cao Ming-Yu Chen Sheng-Wen Hu Jun-Ying Miao Bao-Xiang Zhao 《Analytica chimica acta》2015
We have developed the first two-photon colorimetric and ratiometric fluorescent probe, BICO, for the detection of bisulfite (HSO3−) in aqueous solution. The probe contains coumarin and benzimidazole moieties and can detect HSO3− based on the Michael addition reaction with a limit of detection 5.3 × 10−8 M in phosphate-buffered saline solution. The probe was used to detect bisulfite in tap water, sugar and dry white wine. Moreover, test strips were made and used easily. We successfully applied the probe to image living cells, using one-photon fluorescence imaging. BICO overcomes the limitations in sensitivity of previously reported probes and the solvation effect of bisulfite, which demonstrates its excellent value in practical application. 相似文献
98.
交流阻抗法作为一种新型的无标记、全程动态、实时分析方法已在细胞研究中得到了广泛应用。本文综述了基于交流阻抗法进行细胞分析的研究新进展,重点对非法拉第阻抗谱法和法拉第阻抗谱法用于细胞分析的原理及应用进行了总结,主要包括交流阻抗法在细胞形态、细胞生长、细胞增殖、细胞凋亡以及作用于细胞的药效和毒性研究中的应用,并对其发展趋势进行了展望。 相似文献
99.
Researchers have demonstrated that Raman spectroscopy can be used for characterization of tumor cells with excellent spatial resolution. However, performance evaluation of different algorithms in classifying multiclass of Raman spectra has not been reported yet. In this work, we present Raman spectra of nasopharyngeal carcinoma and nasopharyngeal normal cell lines. Combined with student’s t-test and several multivariate approaches, including decision tree, support vector classification, and linear discriminant analysis, our work shows that the relative content of two histological abnormality sensitive bands at 1449 and 1658 cm−1 in tumor cells is significantly different from that of normal cells (p = 0.0132), and can be a biomarker to classify these cells. This difference is confirmed by importance analyses in the decision tree model. Furthermore, performances of statistical methods are compared with one another to explore the ability in classification. Results show that the decision tree can be more capable for classification between tumorous and normal cell lines with sensitivity and specificity of 99.0% and 96.9%, respectively. Findings of this work further support our previous work and indicate that the decision tree performs more robustly in cell classification. Our work will prove helpful to the early diagnosis of nasopharyngeal carcinoma, and will indicate the decision tree to be the primary algorithm in tumor-cell classification. 相似文献
100.
Screening anti‐tumor compounds from Ligusticum wallichii using cell membrane chromatography combined with high‐performance liquid chromatography and mass spectrometry
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Tao Zhang Yuanyuan Ding Hongli An Liuxin Feng Sicen Wang 《Journal of separation science》2015,38(18):3247-3253
Tyrosine 367 Cysteine‐fibroblast growth factor receptor 4 cell membrane chromatography combined with high‐performance liquid chromatography and mass spectrometry was developed. Tyrosine 367 Cysteine‐HEK293 cells were used as the cell membrane stationary phase. The specificity and reproducibility of the cell membrane chromatography was evaluated using 1‐tert‐butyl‐3‐{2‐[4‐(diethylamino)butylamino]‐6‐(3,5‐dimethoxyphenyl)pyrido[2,3‐d]pyrimidin‐7‐yl}urea, nimodipine and dexamethasone acetate. Then, anti‐tumor components acting on Tyrosine 367 Cysteine‐fibroblast growth factor receptor 4 were screened and identified from extracts of Ligusticum wallichii. Components from the extract were retained on the cell membrane chromatographic column. The retained fraction was directly eluted into high‐performance liquid chromatography with mass spectrometry system for separation and identification. Finally, Levistolide A was identified as an active component from Ligusticum wallichii extracts. The 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl‐tetrazolium bromide‐formazan colorimetric assay revealed that Levistolide A inhibits proliferation of overexpressing the mutated receptor cells with dose‐dependent manner. Phosphorylation of fibroblast growth factor receptor 4 was also decrease under Levistolide A treatment. Flex dock simulation verified that Levistolide A could bind with the tyrosine kinase domain of fibroblast growth factor receptor 4. Therefore, Levistolide A screened by the cell membrane chromatography combined with high‐performance liquid chromatography and mass spectrometry can arrest cell growth. In conclusion, the two‐dimensional high‐performance liquid chromatography method can screen and identify potential anti‐tumor ingredients that specifically act on the tyrosine kinase domain of the mutated fibroblast growth factor receptor 4. 相似文献