Search

In the field of cryopreservation, recrystallization during rewarming is a significant factor leading to cryo-injury, causing ice crystal-induced mechanical injury to biological samples. Currently, methods, such as adding ice recrystallization inhibiting agents and increasing warming rates, have been adopted to reduce recrystallization injury. These methods also greatly increase the potential toxicity risk and engineering difficulty of cryopreservation. Accumulating research has progressively demonstrated that application of an electromagnetic field during cryopreservation can influence the preservation efficacy. However, the mechanism of action of the electric field has remained a subject of ongoing debate. We observed the recrystallization phenomenon of cryoprotectant solutions under a polarized light microscope and discovered promising experimental results. The electric field strength did not exhibit a discernible impact on the ice crystal size, while electric field frequency exerted a more significant impact. We found that at specific frequencies, the ice crystal size and growing rate were significantly affected during annealing. Compared to no electric field, an alternating electric field with a voltage of 10 V and a frequency of 5 × 104 Hz increased the recrystallization areas of a 15% (w/v) propylene glycol solution by 57%. And an alternating electric field with a voltage of 3 V and a frequency of 5 × 108 Hz decreased the recrystallization area of a 0.9% (w/v) NaCl aqueous solution by 9.9%. Different types of cryoprotectants exhibit varying responses to alternating electric fields frequency. These findings prompt us to reevaluate the role and mechanism of alternating electric fields in the cryopreservation of biological materials. [ABSTRACT FROM AUTHOR]

Magnetization reversal in GdFeCo by circularly polarized light is shown to occur at the femtosecond time scale. In contrast to the well-known laser-assisted magnetization reversal based on the laser heating, we here demonstrate that this femtosecond all-optical magnetization reversal is more efficient at lower temperatures. Both of these findings make all-optical recording on rare-earth transition metal alloys a promising technique for stable magnetic storage with high data rates. [ABSTRACT FROM AUTHOR]

The authors reported the plasmonic control of semiconductor laser polarization by means of metallic gratings and subwavelength apertures patterned on the laser emission facet. An integrated plasmonic polarizer can project the polarization of a semiconductor laser onto other directions. By designing a facet with two orthogonal grating-aperture structures, a polarization state consisting of a superposition of a linearly and right-circularly polarized light was demonstrated in a quantum cascade laser; a first step toward a circularly polarized laser. [ABSTRACT FROM AUTHOR]

Converse and direct piezoelectric coefficients (d33C and d33D) of (001)-cut Pb(Mg1/3Nb2/3)0.70Ti0.30O3 (PMN-30%PT) single crystals have been investigated as a function of poling electric (E) field. E-field-dependent domain structures were observed by using a polarizing microscope. Both d33C and d33D exhibit a rapid increase at E=1–2 kV/cm and reach maxima at E=2.5–4 kV/cm. This study suggests that polarization rotation from rhombohedral to monoclinic MA phases plays an important role while the high piezoelectric response builds up. Overpoling phenomenon evidenced by a sudden reduction in piezoelectric coefficient with increasing field is very sensitive to Ti content. [ABSTRACT FROM AUTHOR]

Stress in single and periodic shallow-trench-isolated Si structures was examined by 364 nm excitation confocal resonance Raman microscopy, laser penetration being restricted to the near-surface region. Using a 1.3 numerical aperture microobjective lens with a theoretical ∼140 nm spatial resolution, the authors show that the configuration with both incident and scattered lights polarized parallel to each other and perpendicular to Si stripes is favorable for stress detection in the middle of the stripes, suppressing contributions from their edges. The stresses located in different areas of the structures were identified and analyzed. [ABSTRACT FROM AUTHOR]

Spin filter devices based on resonant tunneling antisymmetrical magnetic-barrier structures are proposed and the spin-polarization properties are described. These devices can be realized by depositing one or two ferromagnetic stripes with perpendicular magnetization on top of two-dimensional electron gas. It is remarkable that the spin-filter efficiency of the transmission probability and the conductance through these devices could be reached completely (∼100%) in resonance, and that constant voltage applied to the metallic stripe of the systems could tune the spin polarization. These interesting features may lead to a practical voltage controlled spin filter. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

A sequence of field-induced phase transformations was observed by means of a polarizing microscope on a (111)-cut single crystal Pb(Mg[sub 1/3]Nb[sub 2/3])[sub 0.67]Ti[sub 0.33]O[sub 3] at room temperature with an electric field applied along the [111] direction. As electric field increases, polarizations of the rhombohedral R domains whose polar directions are not along [111] rotate first toward a tetragonal T phase associated with 90° domain walls. Then the crystal gradually reaches total optical extinction for all polarizer angles at 12 kV/cm, indicating a single [111] rhombohedral R[sub 111] domain with polarization aligned with the electric field. These field-induced phase transformations are irreversible and proceed most likely through M[sub A]-type monoclinic distortions, i.e., R→M[sub A]→T→M[sub A]→R[sub 111]. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Recently, the first direct optical observation of vertical Bloch lines using a laser scanning microscope has been reported (A. Thiaville, L. Arnaud, F. Boileau, and G. Sauron, EMMA Conference, Salford, Great Britain, 1987, paper AD-19). Here we describe a different way of direct observation that uses a polarizing light microscope. This method has the advantage of lower thermal disturbance of the domain structure and the ability of real-time observation. To obtain one-sided dark-field illumination, the incoming light beam is coupled into the garnet film by means of a glass microprism. On examining the Bi-containing film, the Bloch lines can be directly observed through the eyepiece of the microscope. Movement of Bloch lines caused by in-plane field pulses, and also by asymmetric bias field pulses, is observed. [ABSTRACT FROM AUTHOR]

Examines the use of nonlinear magneto-optical microscopy and linear polarizing microscope in magnetic domain studies of magnetic garnet films. Rotation of the incoming light linear polarization; Removal of spot-profile inhomogeneity in the image intensity; Information on magnetic structure from the second harmonic light.