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In this study, the conductive conjugated polyvinyl alcohol (PVA)/graphene (G) composite nanofibers were fabricated by a facile electrospinning successfully. The processing technique demonstrated that the in-situ crosslinking nanofibers were hollow structures by using an ultrasonication treatment for G nanosheets (≈3.5 nm) due to the effect of solution viscosity (PVA-G concentration). Hereby, very few studies have been performed the characterization of the hollow nanofibers by PVA-G processing. The electrical conductivity and specific surface area of composite nanofibers resulted in significant effects on the viscosity of the reaction mixture for the electrospinning process, which can possibly open up the new emerging sensing themes and applications.

In this paper, a bending machine for tuning optical design of LED module is proposed. The tuning is done by changing the bending angles of each package on a given module with the help of automatic control program. Luminous intensity distribution can be controlled by adjusting the light emission path, which in turn can be implemented as changing the bending angles of individual LED packages on the module. The proposed machine is capable of bending packages to specified angles with errors less than 0.1°. Three-dimensional light distribution for bent package LED modules is also studied based on various application scenarios so that each scenario can have diversified luminous intensity distribution resulting in higher uniformity and better luminance quality. The machine has several advantages, including quick bending, high accuracy, and great customizability. These advantages make the machine meet the requirements of automatic mold forming.

Electron diffraction and optical reflectivity have provided the direct confirmation of the existence of layer-by-layer surface transitions from the smectic-A immediately to the crystal-B phase in a liquid-crystal material, without going through an intermediate hexatic phase. The molecular interactions are found to be through retarded van der Waals forces. Our results suggest that a smectic-A film can transform into a crystal-B through three possible scenarios.

Surface freezing transitions in free-standing films of achiral Schiff’s-base liquid crystals 5O.6 and 7O.7 exhibiting tilted hexatic phases have been studied using optical textures. The evolution of textures with temperature in 5O.6 films is qualitatively similar to that reported earlier in FTE1, except that the stripe texture consists of alternating light and dark stripes of unequal widths. No stripe texture is observed in 7O.7.

We have conducted heat-capacity measurements near the smectic-A -smectic-C* phase transition in free-standing films of a chiral liquid-crystal compound. The heat-capacity behavior confirms the evolution of the transition in the interior layers from first to second order as a function of film thickness suggested earlier in tilt angle measurements. The asymmetry in the heat-capacity anomaly exhibits an interesting crossover in thinner films. We also observed the phase transitions leading to the crystallization to the tilted crystal-G phase in these films at lower temperatures. The surface ordering strength in these films is found to be much larger than that in other orthogonal-smectic films, which we speculate is due to the molecular tilt.

We have conducted heat-capacity measurements near the smectic-A -smectic-C* phase transition in free-standing films of a chiral liquid-crystal compound. The heat-capacity behavior confirms the evolution of the transition in the interior layers from first to second order as a function of film thickness suggested earlier in tilt angle measurements. The asymmetry in the heat-capacity anomaly exhibits an interesting crossover in thinner films. We also observed the phase transitions leading to the crystallization to the tilted crystal-G phase in these films at lower temperatures. The surface ordering strength in these films is found to be much larger than that in other orthogonal-smectic films, which we speculate is due to the molecular tilt.

Electron diffraction in freestanding thin films in the crystal-B phase reveals extensive multiple diffraction in films of 14S5 but not of 4O.8, suggesting an important difference in the structural order in these films despite the similarities in their positional correlations found in earlier experiments. The result in a two-layer 14S5 film indicates surprisingly that secondary diffraction can occur in a crystal with only pseudo-long-range positional order.

Electron diffraction and optical reflectivity have provided the direct confirmation of the existence of layer-by-layer surface transitions from the smectic-A immediately to the crystal-B phase in a liquid-crystal material, without going through an intermediate hexatic phase. The molecular interactions are found to be through retarded van der Waals forces. Our results suggest that a smectic-A film can transform into a crystal-B through three possible scenarios.

We have conducted heat-capacity measurements near the smectic-A – smectic-C* phase transition in free-standing films of a chiral liquid-crystal compound. The heat-capacity behavior confirms the evolution of the transition in the interior layers from first to second order as a function of film thickness suggested earlier in tilt angle measurements. The asymmetry in the heat-capacity anomaly exhibits an interesting crossover in thinner films. We also observed the phase transitions leading to the crystallization to the tilted crystal-G in these films at lower temperatures. The surface ordering strength in these films is found to be much larger than that in other smectic films, which we speculate is due to the molecular tilt.

We report for the first time the thermal study near the Sm-C–Sm-I critical point in free-standing thin films of 70.7 compound. The profiles of the Sm-C–Sm-I heat-capacity anomalies are found to exhibit an unexpected crossover behavior with film thickness in reduced dimensions. The data from two-layer films are not consistent with the predictions of two-dimensional melting theory. Our results also provide evidence in support of the recent theory proposed by Defontaines and Prost. Moreover, we confirm the existence of a surface hexatic Sm-L phase in 70.7 films of less than eight layers whose phase sequence is however dramatically different from that observed in the thicker films.

Surface freezing transitions in free-standing films of achiral Schiff's-base liquid crystals 5O.6 and 7O.7 exhibiting tilted hexatic phases have been studied using optical textures. The evolution of textures with temperature in 5O.6 films is qualitatively similar to that reported earlier in the ferphenyl ester FTE1, suggesting the existence of the surface smectic-L phase, except that the stripe texture in 5O.6 consists of alternating light and dark stripes of unequal widths. No stripe texture is observed in 7O.7.