Mechanical Properties of Breast Cancer Cell Membrane Studied with Optical Tweezers

Membrane tethers are extracted from breast cancer cells using a force generated by an optical trap. It is experimentally obtained that the radius of tether is about 0.1μm and the static tether force is about 8.5 pN. Calculations based on the experimental measurements give a bending modulus for the tether of 1.35 x 10^-19 N.m and a surface membrane tension of 6.76 x 10^-6 N/m in the breast cancer cell. The treatment with cytochalasin D results in the decreasing bending modulus and decreasing apparent surface tension. When the membrane protein caveolin is over-expressed, similar cases occur in bending modulus and apparent surface tension. In addition, the viscous resistance coefficient of the membrane is calculated to be 1.15pN.s/μm according to the dynamic tether forces obtained under different pulling velocities.     

函数的图象与性质

函数的图象与性质是函数部分的主要内容，在高中数学竞赛中应用广泛．本讲主要研究函数图象变换及应用，利用函数的单调性、奇偶性、周期性解决竞赛中的问题．     

等差数列、等比数列的一个新的性质

结论1 已知等差数列{an}，r，s，t是互不相等的正整数，则有（r-s）at＋（s—t）a，＋（t—r）as=0．     

离心率为2的双曲线的性质

1．问题的提出 在2007年高三复习中笔者选用了温州市高三适应性测试数学试卷，其中解答题17题是这样的：如图（图略），设A（-2，0），B（2，0），直线l：X=1，点C在直线l上，动点P在直线BC上，且满足→AP·→AC=0．     

Optical and Electronic Properties of InGaN／GaN Multi—Quantum—Wells Near—Ultraviolet Lighting—Emitting—Diodes Grown by Low—Pressure Metalorganic Vapour Phase Epitaxy

The near-ultraviolet lighting-emitting-diodes (UV-LEDs) with the InGaN/GaN multi-quantum-well (MQW) structure were grown by low-pressure metalorganic vapour phase epitaxy. The double crystal x-ray diffraction revealed a distinct second-order satellite peak. The near-ultraviolet InGaN/GaN MQW LEDs have been successfully fabricated to emit at 401.2nm with narrow FWHM of 14.3nm and the forward voltage of 3.6 V at 20 mA injection current at room temperature. With increasing forward current from l 0 mA to 50 mA, the redshift of the peak wavelength was observed due to the band-gap narrowing caused by heat generation.     

不具有性质(wa)的拓扑空间

设（X，T）是拓扑空间，如果对于任意的开覆盖u和任意的稠密子集D存在X的离散子集F∪→D使得St(F,u)=∪{U∈u:U∩F≠φ}=X，则称（X，T）具有性质（wa)，每一正规空间都具有性质（wa)。M.V.Matveev举例说明了T1空间可以不具有性质(wa)，本文证明了存在很多Hausdorff空间不具有性质（wa)，且进一步举例说明了Tychonoff空间可以不具有性质（wa)，这些结果回答了Matveev的问题。     

关于四面体的一个性质

四面体是空间里较为简单的几何体 ,笔者通过将它与三角形的有关性质进行类比 ,得到一个有价值的结论 .定理　四面体Ａ -ＢＣＤ中 ,Ｅ ,Ｆ ,Ｇ ,Ｈ分别在棱ＡＢ ,ＢＣ ,ＣＤ ,ＤＡ上 ,且 ＡＥＥＢ =λ1,ＢＦＦＣ =λ2 ,ＣＧＧＤ =λ3,ＤＨＨＡ =λ4 .则内接四面体ＥＦＧＨ的体积ＶＥＦＧＨ =｜λ1·λ2 ·λ3·λ4 -1｜(1 +λ1) (1 +λ2 ) (1 +λ3) (1 +λ4 ) ＶＡＢＣＤ证明　如图 1 ,连结ＥＤ ,ＢＧ ,得四棱锥Ｅ -ＦＢＤＧ ,Ｇ-ＥＢＤＨ ,在△ＣＢＤ ,△ＡＢＤ中 ,ＳＣＦＧＳＣＢＤ =ＣＦ·ＣＧＣＢ·ＣＤ =11 +λ2 · λ31 +λ3=λ3(1 +λ…     

迈克尔逊干涉仪性能的恢复

迈克尔逊干涉仪性能的恢复陶纯匡（重庆大学应用物理系，６３００４４）迈克尔逊干涉仪是精密的光学仪器，其性能的下降包括两个方面：一是光学性能的下降；二是机械性能的下降．要使迈克尔逊于涉仪（以下简称迈氏？涉仪）的综合性能得以恢复也必须从这两方面着手．几年来...