By direct calculation of rotation matrices of SO(3),we show how certain specific sequence of eight consecutiverotations of digital angles can yield a tilting of a facet mirror.We also design a detailed program specifi...By direct calculation of rotation matrices of SO(3),we show how certain specific sequence of eight consecutiverotations of digital angles can yield a tilting of a facet mirror.We also design a detailed program specifically to tiltan array of mirrors from planar orientation to the required focusing orientation.We describe how to use the 8-step torealize the focusing of the mirror array.We have found,in our designed program,an important feature of row-sharingduring the rotations for the columns and similarly the column-sharing during the rotations for the row.This feature cansave a lot of operating time during the actual realization of the mechanical movements.展开更多
In this paper, evaporation of sessile water droplets containing fluorescent polystyrene （PS） microparticles on polydimethylsiloxane （PDMS） surfaces with different curing ratios was studied experimentally using las...In this paper, evaporation of sessile water droplets containing fluorescent polystyrene （PS） microparticles on polydimethylsiloxane （PDMS） surfaces with different curing ratios was studied experimentally using laser confocal microscopy. At the beginning, there were some microparticles located at the contact line and some microparticles moved towards the line. Due to contact angle hysteresis, at first both the contact line and the microparticles were pinned. With the depinning contact line, the microparticles moved together spontaneously. Using the software Image J, the location of contact lines at different time were acquired and the circle centers and radii of the contact lines were obtained via the least square method. Then the average distance of two neighbor contact lines at a certain time interval was obtained to characterize the motion of the contact line. Fitting the distance-time curve at the depinning contact line stage with polynomials and differentiating the polynomials with time, we obtained the velocity and acceleration of both the contact line and the microparticles located at the line. The velocity and the maximum acceleration were, respectively, of the orders of 1 p.m/s and 20-200 nm/s2, indicating that the motion of the microparticles located at the depinning contact line was quasi-static. Finally, we presented a theoretical model to describe the quasi-static process, which may help in understanding both self-pinning and depinning of microparticles.展开更多
Rotational motion of fluorophores chemically attached to polystyrene chain-ends in ultra-thin films on solid substrates was studied by single-molecule fluorescence de-focus microscopy.The collective feature of the rot...Rotational motion of fluorophores chemically attached to polystyrene chain-ends in ultra-thin films on solid substrates was studied by single-molecule fluorescence de-focus microscopy.The collective feature of the rotational motion was found and evidenced by the sharp change of the population of fluorophores undergoing rotational motion within a very narrow temperature range(named as the changing temperature,T c).The T c value was found to depend on film thickness and interfacial chemistry and the variation of the T c value is also dependent on the molecular weight of the polymer.The results demonstrate that the spatial confinement effect enhances the segmental mobility near the polymer chain-ends while the interfacial attraction restricts the segmental motion inside the thin film.展开更多
文摘By direct calculation of rotation matrices of SO(3),we show how certain specific sequence of eight consecutiverotations of digital angles can yield a tilting of a facet mirror.We also design a detailed program specifically to tiltan array of mirrors from planar orientation to the required focusing orientation.We describe how to use the 8-step torealize the focusing of the mirror array.We have found,in our designed program,an important feature of row-sharingduring the rotations for the columns and similarly the column-sharing during the rotations for the row.This feature cansave a lot of operating time during the actual realization of the mechanical movements.
基金supported by the National Natural Science Foundation of China(Grant Nos.11572114,11572335,and U1562105)the Opening Fund of State Key Laboratory of Nonlinear Mechanics(LNM)+1 种基金the CAS Strategic Priority Research Program(Grant No.XDB22040403)and the CAS Key Research Program of Frontier Sciences(Grant No.QYZDJ-SSW-JSC019)
文摘In this paper, evaporation of sessile water droplets containing fluorescent polystyrene （PS） microparticles on polydimethylsiloxane （PDMS） surfaces with different curing ratios was studied experimentally using laser confocal microscopy. At the beginning, there were some microparticles located at the contact line and some microparticles moved towards the line. Due to contact angle hysteresis, at first both the contact line and the microparticles were pinned. With the depinning contact line, the microparticles moved together spontaneously. Using the software Image J, the location of contact lines at different time were acquired and the circle centers and radii of the contact lines were obtained via the least square method. Then the average distance of two neighbor contact lines at a certain time interval was obtained to characterize the motion of the contact line. Fitting the distance-time curve at the depinning contact line stage with polynomials and differentiating the polynomials with time, we obtained the velocity and acceleration of both the contact line and the microparticles located at the line. The velocity and the maximum acceleration were, respectively, of the orders of 1 p.m/s and 20-200 nm/s2, indicating that the motion of the microparticles located at the depinning contact line was quasi-static. Finally, we presented a theoretical model to describe the quasi-static process, which may help in understanding both self-pinning and depinning of microparticles.
基金supported by the National Basic Research Program of China(2012CB821500)the National Natural Science Foundation of China(20925416)
文摘Rotational motion of fluorophores chemically attached to polystyrene chain-ends in ultra-thin films on solid substrates was studied by single-molecule fluorescence de-focus microscopy.The collective feature of the rotational motion was found and evidenced by the sharp change of the population of fluorophores undergoing rotational motion within a very narrow temperature range(named as the changing temperature,T c).The T c value was found to depend on film thickness and interfacial chemistry and the variation of the T c value is also dependent on the molecular weight of the polymer.The results demonstrate that the spatial confinement effect enhances the segmental mobility near the polymer chain-ends while the interfacial attraction restricts the segmental motion inside the thin film.
