Chiral nematic liquid crystals--otherwise referred to as cholesteric liquid crystals (CLCs)--are self-organized helical superstructures that find practical application in, for example, thermography, reflective displays, tuneable colour filters and mirrorless lasing. Dynamic, remote and three-dimensional control over the helical axis of CLCs is desirable, but challenging. For example, the orientation of the helical axis relative to the substrate can be changed from perpendicular to parallel by applying an alternating-current electric field, by changing the anchoring conditions of the substrate, or by altering the topography of the substrate's surface; separately, in-plane rotation of the helical axis parallel to the substrate can be driven by a direct-current field. Here we report three-dimensional manipulation of the helical axis of a CLC, together with inversion of its handedness, achieved solely with a light stimulus. We use this technique to carry out light-activated, wide-area, reversible two-dimensional beam steering--previously accomplished using complex integrated systems and optical phased arrays. During the three-dimensional manipulation by light, the helical axis undergoes, in sequence, a reversible transition from perpendicular to parallel, followed by in-plane rotation on the substrate surface. Such reversible manipulation depends on experimental parameters such as cell thickness, surface anchoring condition, and pitch length. Because there is no thermal relaxation, the system can be driven either forwards or backwards from any light-activated intermediate state. We also describe reversible photocontrol between a two-dimensional diffraction state, a one-dimensional diffraction state and a diffraction 'off' state in a bilayer cell.

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166 wileyonlinelibrary.com COMMUNICATION external stimuli, such as electric fi eld and light. A cholesteric grating with a fi eld-controlled period has been demonstrated. [ 8 ] The diffraction angle can be shifted 15° by varying the applied voltage. A reversible optically switchable beam steering device based on an azobenzene-doped CLC grating has been reported recently, [ 9 ] and it was observed that the grating structure can remain more uniform by the optical tuning than that by electrical tuning. However, the optical tuning range was limit to ≈6° only, because the infl uence of the doped azobenzene upon the pitch was fairly fi nite. It is of paramount importance to develop CLC gratings with reversible wide range beam steering capabilities for optical device applications.In conventional spectrometers, a prism or a diffraction grating spatially separates spectral components of light utilizing wavelength dispersion, which can be detected by an array of photodetectors. [ 13 ] Such spectrometers possess the advantages of easy fabrication and operational simplicity. However, for particular biological and medical analyses, e.g., hyperspectral imaging, [ 14 ] the entire spectrum needs to be recorded at every pixel. Thus, it is diffi cult to be achieved by using spatially dispersive elements. Alternatively, diffraction gratings can be implemented in a frequency sequential scanning system by detecting the incidence angle with mechanically scanning to separate a single spectral component on a single detector. However, the system is bulky and needs high mechanical accuracy. Many methods have been proposed to miniaturize grating dispersive spectrometers. [15][16][17][18] The advantage of a wavelength tunable LC spectrometer is that the entire spectrum can be recreated at single pixel. Nonmechanical tuning can also be realized with an applied external stimulus (light, temperature, electric fi eld) which can further improve the minimized system.In this communication, we report an optically tunable beam steering grating based on a high helical twisting power (HTP) light-driven axially chiral molecular switch-doped CLC fi ngerprint texture. The signifi cant differences of their HTPs resulting from confi gurational changes of the chiral molecular switch upon photoisomerization varies the pitch of CLC, [ 19 ] and consequently shifts the diffraction angle of the CLC grating. Based on this property, the beam steering and spectrum scanning technique have been studied and demonstrated. To the best of our knowledge, this is the LC grating with widest reversible beam steering range reported so far. As a consequence, herein its spectrum scanning capability with potential application in spectrometers as a dispersive element has been demonstrated.In this experiment, the commercially available achiral nematic LC E48 (Merck) with a positive dielectric anisotropy Δ ε Liquid crystals (LCs) are unique functional soft materials with remarkable multistimuli responsive attributes. The LCs formed by rod-shaped molecules have become ubiquitous in ...

Background Autism spectrum disorder (ASD) and obesity are serious global public health problems. Studies have shown that ASD children are at a higher risk of obesity than the general population. To investigate the gut microbe characteristics of adults ASD and obese adults, we compared the gut microbiota of adults with ASD to obese adults. Methods The fecal samples were collected from 21 adult patients with ASD and 21 obese adults, and V3–V4 regions of 16S rRNA genes were sequenced by high-throughput DNA sequencing. The gut microbiota of adults with ASD and obese adults was compared. Results We observed the proportion of Firmicutes/Bacteroidetes in ASD was significantly increased, with families Lachnospiraceae and Ruminococcaceae significantly enriched in adult ASD. Eighteen genera, including Lachnospiracea incertae sedis, Ruminococcus, Blautia, and Holdemanella were significantly increased in adult ASD, whereas Megamonas and Fusobacterium were significantly increased in obesity. At the species level, we found six species enriched in ASD and three species enriched in obesity, including Phascolarctobacterium succinatuten producing propionate. Dialister succinatiphilus may be as a biomarker for predicting obesity, as well as Prevotella copri may be a common-owned pathogens of ASD and obesity. Conclusions Some conflicting results have been reported in microbiota studies of ASD, which may be related to age and obesity. Thus, the body mass index should be evaluated before analyzing the gut microbiota of patients with ASD, as obesity is prevalent in these individuals and gut microbiota is severally affected by obesity.

The study examined how executive function (EF) training could improve children's emotional competence (EC). Children (N = 55; M age = 50.64 months) were assigned into two groups, namely the EF training group and the no-training group. The present study attempted to use a 2 (group: EF training VS no-training) × 2 (test time: pretest VS post-test) between-and-within-subjects experimental design to investigate the effect of EF training on the improvement of EC for 4-year-old children. Results showed that, (1) children in EF training group had significantly higher scores on EC than that of no-training group; (2) The change of inhibition control and working memory could significantly predict their variation of EC. These results suggested that the improvement of EC caused by EF training could be linked to the ability of inhibition control and working memory.