Measurement of interaction force between RGD-peptide and Hela cell surface by optical tweezers

Since RGD peptides (R: arginine; G: glycine; D: aspartic acid) are found to promote cell adhesion, they are modified at numerous materials surface for medical applications such as drug delivery and regenerative medicine. Peptide-cell surface interactions play a key role in the above applications. In this letter, we study the adhesion force between the RGD-coated bead and Hela cell surface by optical tweezes. The adhesion is dominated by the binding of α5β1 and RGD-peptide with higher adhesion probability and stronger adhesion strength compared with the adhesion of bare bead and cell surface. The binding force for a single α5β1 -GRGDSP pair is determined to be 16.8 pN at a loading rate of 1.5 nN/s. The unstressed off-rate is 1.65 × 10-2s-1 and the distance of transition state for the rigid binding model is 3.0 nm.     

Application of subband adaptive filtering techniques to ultrasonic detection in multilayers

The ultrasonic testing for the defects of complete disbond in multi-layered structure with lower acoustic impedance beneath a high acoustic impedance overburden is one of the difficult problems in ultrasonic nondestructive testing field.A model of a multi-layered steel-rubber composite plate is depicted.Because the acoustic impedance of the steel differs far from that of the couplant water and the rubber,the energy of the signal refleccted from the deonded rubber layers is very weak.More over,the flaw echoes are masked by the strong echoes reverberated in the steel plate.It‘s nearly impossible to identify the debonding echoes directly.The subband adaptive filtering method is discussed in the paper,where the subband decomposition is performed by mutual wavelet packets decomposition on the criterion of maximizing the cross-correlation between the signals.The simulations on both synthetic and real signals are presented.The echoes from the delaminated flaw at the depth of 5mm in the rubber from the calculated signal,and echoes from the flaw at the depth of 3mm from the real signal are extracted successfully.     

Symmetrical adhesion of two cylindrical colloids to a tubular membrane

With the full treatment of the Helfrich model we theoretically study the symmetrical adhesion of two cylindrical colloids to a tubular membrane. The adhesion of the rigid cylinders with different radius from the membrane tube surface can produce both shallow wrapping with relatively small wrapping angle and deep wrapping with big wrapping angle. These significant structural behaviors can be obtained by analyzing the system energy. A second order adhesion transition from the desorbed to weakly adhered states is found, and a first order phase transition where the cylindrical colloids undergo an abrupt transition from weakly adhered to strongly adhered states can be obtained as well.     

水飞蓟宾生物粘附微球的制备

建立了水飞蓟宾生物粘附微球的最佳处方。通过单因素考察海藻酸钠浓度、氯化钙浓度、注射器针头规格、干燥方法4个因素对微球性质的影响规律,及L9(34)正交试验确定最佳处方为海藻酸钠浓度1.5%,氯化钙浓度0.1%,针头规格7#,40℃干燥。并对最佳处方制备得到的3批微球进行了外观形态、体外释放度、载药量以及粘附力测定,均符合质量检测要求。该处方制备工艺良好。     

受限空间内油水界面动态特性及粘附行为的荧光原位观测

水污染作为润滑油污染的常见形式,对润滑油本身以及机械系统都有巨大的危害。为了模拟实际非均匀多相系统中的界面行为,本文搭建了高精度点接触实验台来研究传统的不溶相替换问题。将目前静态平行受限空间内油水界面行为的研究推广到动态点接触楔形受限空间内,探究了游离水滴穿过点接触狭缝间毛细油池过程中的界面特性。重点关注固壁润湿性以及固壁的分离运动对整个侵入过程中液滴动态行为的影响。实验发现了铺展系数是决定油水界面融合和分离特性的关键因素,揭示了固壁润湿性和球盘间的相对分离运动会影响游离水滴穿过毛细油池之后的粘附行为。表面张力和液体与壁面之间的粘附功能够解释观测的实验现象。     

罗伊氏乳杆菌NCU801对病原菌的粘附抑制性能

采用选择性平板计数法,考察罗伊氏乳杆菌NCU801活菌悬液、死菌悬液以及发酵上清液对大肠杆菌CMCC44496和金黄色葡萄球菌26003粘附Caco-2细胞的影响。结果表明:在竞争试验、排斥试验和置换试验中,罗伊氏乳杆菌NCU801活菌悬液和死菌悬液均能抑制大肠杆菌和金黄色葡萄球菌的粘附;活菌悬液比死菌悬液抑制效果更显著,其中最显著的是活菌悬液对大肠杆菌排斥抑制粘附,粘附抑制率达到(86.8±4.5)%;而发酵上清液在竞争实验中最显著,其次是置换试验,而在排斥实验中对病原菌无影响,说明发酵上清液中的细菌素能够杀死未粘附和已粘附的病原菌。更多还原     

Surface Anti-bacterial Adhesion Characteristics of TiO_2-coated PMMA

The anti-bacterial adhesion properties of TiO2-coated polymethyl methacrylate （PMMA） surfaces are investigated systematically. In detail, the adhesion of S. aureus （gram positive） and E. coli （gram negative） to TiO2-coated and uncoated PMMA surfaces are performed by the plate counting method. Afterwards, the adhesion free energy of bacteria on both supporting materials is quantified using the thermodynamic approach of Lifshitz van der Waals and acid/base interactions. The superior anti-adhesion capability of TiO2-coated PMMA is demonstrated when compared to native PMMA, both experimentally and theoretically.     

AFM针尖-测试面接触分子动力学研究

针对AFM针尖-测试面的接触问题,利用分子动力学模拟针尖同测试面间的"跳跃粘附"和"颈缩分离"过程;分析接触力同接触间隙的关系及测试面压力分布;发现分离过程滞后粘附过程;得到接触力大小只与接触区域附近少数原子层有关,且接触区域近处原子受压力、远处受拉力的结论;讨论测试面位错半径同接触力和接触间隙的关系.     

小群簇下特异性粘附界面力学性质的统计分析

针对经由特异性分子间发生化学作用,生成粘附分子键群簇而形成的可变形介质间的特异性粘附问题,蒙特卡洛仿真作为有效的研究手段被广泛用来随机模拟界面特异性粘附行为,但当粘附系统分子键数目较小时,粘附系统具有明显的热扰动性质,此时受限于统计方法,现有统计方法难以定量地描述系统的特异性粘附行为。为此,本文基于统计热力学理论,提出了积分统计方法,结果表明无论在稳态还是动态下,基于所提出的积分法统计结果与数值求解结果一致,尤其是针对系统分子键数目较少,粘附系统具有强热扰动性质的情况时,该方法依旧可以精确地反映系统特异性粘附行为。     

Strong Correlation and Anticorrelation via Phase-Dependent Coherent Population Trapping

We present the phase control of photon correlations in a driven four-level system in the double lambda configuration. The strong correlation and the anticorrelation are. obtained when the collective phase of four applied laser fields is varied. The coherent control is based on the phase-dependent coherent population trapping （CPT）. The strong correlation occurs when the system operates near CPT, while the anticorrelation occurs when the system is far away from CPT.