Anomalous Lehmann Rotation of Achiral Nematic Liquid Crystal Droplets Trapped under Linearly Polarized Optical Tweezers

Continuous rotation of a cholesteric droplet under the heat gradient was observed by Lehmann in 1900. This phenomenon, the so-called Lehmann effect, consists of unidirectional rotation around the heat flux axis. We investigate this gradient heat effect using infrared laser optical tweezers. By applying single trap linearly polarized optical tweezers onto a radial achiral nematic liquid crystal droplet, trapping of the droplet was performed. However, under a linearly polarized optical trap, instead of stable trapping of the droplet with slightly deformed molecular directors along with a radial hedgehog defect, anomalous continuous rotation of the droplet was observed. Under low power laser trapping, the droplet appeared to rotate clockwise. By continuously increasing the laser power, a stable trap was observed, followed by reverse directional rotation in a higher intensity laser trap. Optical levitation of the droplet in the laser beam caused the heat gradient, and a breaking of the symmetry of the achiral nematic droplet. These two effects together led to the rotation of the droplet under linearly polarized laser trapping, with the sense of rotation depending on laser power.     

Effect of jute fibers on morphological characteristics and properties of thermoplastic starch/biodegradable polyester blend

Cellulose - The current work aims to study the effect of jute fiber (JF) on the characteristics and performance of a thermoplastic starch/poly(lactic acid)/poly(butylene adipate-co-terephthalate)...     

Optical activity produced by layer chirality in bent-core liquid crystals

Large optical activity has recently been observed in chiral smectic liquid crystalline phases formed from achiral bent-core molecules. The origin of the optical activity remains unclear and has been attributed to both a helical superstructure and the layer chirality produced by simultaneous tilt and polar ordering of bent-core mesogens in the B2 phase. Here, we directly demonstrate that layer chirality produces optical activity in the well ordered SmC(A)P(A) subphase.     

Microwave-induced fabrication of copper nanoparticle/carbon nanotubes hybrid material

Copper nanoparticle/multi-walled carbon nanotube (MWCNT) hybrid material could be fabricated by microwave irradiation to a suspension of MWCNTs dispersed in copper precursor with the presence of ethylene glycol. Microscopic and spectroscopic analyses could confirm the uniform dispersion of copper oxide nanoparticles hybridized on the outer surface of MWCNTs. Reduction of Cu²⁺ ions to Cu₂O and Cu nanoparticles was ascribed to functional groups which were generated after the precursor was irradiated by microwave. Sufficient irradiation time of 5 min or longer played an important role to induce the agglomeration of copper oxide nanoparticles on the MWCNT surface.