(Color online) (a) Schematic layout of the sample slide, coverslip, yeast cell suspension, and glass fragment. The side where yeast cells adhere is shown in profile (photo). Note that the schematic is not to scale. The scale bar is . (b) Schematic layout of the optical tweezer system. With externally positioned mirrors (EPM) objective entrance aperature (OEA) and galvanometric mirrors
(Color online) Creation of flow around yeast maintained by the optical trap by generating oscillatory displacement with the slide-coverslip-yeast suspension-piezostage system. (a) Here, the adhesion glass surface is the microscope coverslip. The tethered yeast is seen beneath. (b) Laser tweezer experimental geometry. A yeast cell is held from the sample interface using an optical trap. The escape force is measured when the stage velocity increase makes the drag force stronger than the trap. The known drag force gives the corresponding trap force. Note that schematics are not to scale and the thermal probe is not displayed.
(Color online) Schematic layout of the sample slide, coverslip, autoadhesive frame, and yeast cell suspension. The double black arrow represents the displacement of the laser beam, which exerts an optical force on the tethered yeast cell. The type-K thermocouple can measure the in situ temperature of the sample during the experiments. In the experiment, the sample is observed from beneath, through the coverslip (second part of the schematics). (a) The adhesion surface is horizontal. (b) Adhesion occurs at a height from the coverslip. The adhesion surface is vertical and consequently the adhering yeast cell is seen in profile. Note that schematics are not to scale.
(a) Images of a single rotating cultured yeast cell tethered to a glass coverslip for of contact time in a , NaCl solution with laser power. . (b) Images of a single rotating rehydrated yeast cell tethered to a glass coverslip with contact time in a NaCl solution with laser power. . The scale bars are , the curved arrow indicates the direction of trap rotation, and the black cross shows the approximate center of rotation.
(a) Images ( apart) of a single rehydrated yeast cell tethered to a glass fragment with contact time in a , NaCl solution with laser power at from the coverslip. . (b) Images ( apart) of a single rehydrated yeast cell tethered to a glass fragment with of contact time in a NaCl solution with laser power at far from the coverslip. . The scale bar is and the black arrow indicates the direction of the trap.
(a) Response of a trapped bead to a triangular wave input to the microscope stage position. The bead shows a square wave response corresponding to the viscous force and thus to the constant velocity of the medium. (b) Wall effect on drag force in the case of a mean diameter cultured yeast cell vs distance from the glass coverslip [see Happel and Brenner (Ref. 42)].
Force of optical trap (pN) obtained with calibration measurement vs power at the objective end (mW) with (a) rehydrated yeast cells of 5.29 and mean diameters respectively, and (b) cultured yeast cells of 4.7 and mean diameters respectively, . The height of calibration from the coverslip is fixed at .
Surface tension components of the probe liquids used for contact angle measurement (water, glycerol, and diiodomethane).
Contact angles and standard deviation (deg) at room temperature . The contact angles were obtained by measurement of angle between probe liquid (water, glycerol, and diiodomethane) and glass coverslips.
Free surface energy values for the two sides of the coverslips. Contact angles obtained previously (see Table II) were then converted into surface free energy values using the van Oss’ modification of the Young equation [see Ref. 18 and Eq. (1)], which ignored spreading pressure and distinguished Lifshitz–van der Waals and Lewis acid/base surface free energy components.
Bibliographical review concerning irradiation effects on living/nonliving trapped objects.
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