Nematic-isotropic phase transitions in thin slabs of liquid crystals with topological defect arrays.

We study the nematic-to-isotropic phase transitions in thin slabs of nematic liquid crystals with photopatterned director fields of topological defect arrays at constant heating rates and show that the transition kinetics is significantly impacted by both the heating rate and the topological strengths of these defects. Specifically, with ±1/2 defect arrays, the isotropic domains emerge from the defect cores when the heating rate is high, while from random places when the heating rate is low. With ±1 defect arrays, the isotropic domains always emerge from the defect cores regardless of the heating rate. Furthermore, the isotropic domains show significant movements at slow heating rates, and the total area of the isotropic domains grows with the temperature T following a simple power law (T - T')γ, where the exponent γ is approximately 1 in most cases and is 2/3 for the ±1 defect arrays at low heating rates when the isotropic domains are pinned on the defect cores. We attribute this phenomenon to an interplay between the surface tension and bulk free energy.

Adaptations for gas exchange enabled the elongation of lepidopteran proboscises.

The extensive biodiversification of butterflies and moths (Lepidoptera) is partly attributed to their unique mouthparts (proboscis [Pr]) that can span in length from less than 1 mm to over 280 mm in Darwin's sphinx moths. Lepidoptera, similar to other insects, are believed to inhale and exhale respiratory gases only through valve-like spiracles on their thorax and abdomen, making gas exchange through the narrow tracheae (Tr) challenging for the elongated Pr. How Lepidoptera overcome distance effects for gas transport to the Pr is an open question that is important to understanding how the Pr elongated over evolutionary time. Here, we show with scanning electron microscopy and X-ray imaging that distance effects on gas exchange are overcome by previously unreported micropores on the Pr surface and by superhydrophobic Tr that prevent water loss and entry. We find that the density of micropores decreases monotonically along the Pr length with the maxima proportional to the Pr length and that micropore diameters produce a Knudsen number at the boundary between the slip and transition flow regimes. By numerical estimation, we further show that the respiratory gas exchange for the Pr predominantly occurs via diffusion through the micropores. These adaptations are key innovations vital to Pr elongation, which likely facilitated lepidopteran biodiversification and the radiation of angiosperms by coevolutionary processes.

Optical Imaging and High-Accuracy Quantification of Intracellular Iron Contents.

Precise quantification of intracellular iron contents is important to biomedical applications of magnetic nanoparticles. Current approaches for iron quantification rely on specialized instruments while most only yield iron quantities averaged over plenty of cells. Here, a simple and robust approach, combining digital optical microscopy with the Beer-Lambert's law, that allows for imaging stainable iron distribution in individual cells and the quantification of stainable iron contents with an unprecedented accuracy of femtogram per pixel, is presented. It is further shown that this approach enables studying of the internalization and reduction dynamics of super-paramagnetic iron oxide nanoparticles (SPIONs) by stem cells in single cell level.

Topology control of human fibroblast cells monolayer by liquid crystal elastomer.

Eukaryotic cells in living tissues form dynamic patterns with spatially varying orientational order that affects important physiological processes such as apoptosis and cell migration. The challenge is how to impart a predesigned map of orientational order onto a growing tissue. Here, we demonstrate an approach to produce cell monolayers of human dermal fibroblasts with predesigned orientational patterns and topological defects using a photoaligned liquid crystal elastomer (LCE) that swells anisotropically in an aqueous medium. The patterns inscribed into the LCE are replicated by the tissue monolayer and cause a strong spatial variation of cells phenotype, their surface density, and number density fluctuations. Unbinding dynamics of defect pairs intrinsic to active matter is suppressed by anisotropic surface anchoring allowing the estimation of the elastic characteristics of the tissues. The demonstrated patterned LCE approach has potential to control the collective behavior of cells in living tissues, cell differentiation, and tissue morphogenesis.

Thermophoresis of colloids in nematic liquid crystal.

Thermophoresis, or the directional motion of colloidal particles in liquids driven by a temperature gradient, is of both fundamental interest and practical use. In this work we explore the thermophoresis of colloids suspended in nematic liquid crystals (LCs). We observe that the motion of these colloids is fundamentally different from that in isotropic systems as a result of elastic distortions in the director fields caused by the colloidal inclusions. In the case of a sufficiently large local temperature and gradient, the elastic energy drives negative thermophoresis of immersed particles, which has a strongly nonlinear dependence on temperature. We develop a theory that incorporates elastic energy minimization into the traditional thermophoretic formulation and demonstrated a good agreement with experimental observations. We also examine the temperature dependence of the effective viscosity of the colloids and highlight the large magnitude of the Soret coefficient (|ST| > 5000), which results from the inherent enhancement in thermophoresis due to elastophoretic considerations and suppression of Brownian diffusion in LC media.

Influence of treating parameters on thermomechanical properties of recycled epoxy-acid vitrimers.

Vitrimers have the characteristics of shape-reforming and surface-welding, and have the same excellent mechanical properties as thermosets; so vitrimers hold the promise of a broad alternative to traditional plastics. Since their initial introduction in 2011, vitrimers have been applied to many unique applications such as reworkable composites and liquid crystal elastomer actuators. A series of experiments have investigated the effects of reprocessing conditions (such as temperature, time, and pressure) on recycled materials. However, the effect of particle size on the mechanical properties of recycled materials has not been reported. In this paper, we conducted an experimental study on the recovery of epoxy-acid vitrimers of different particle sizes. Epoxy-acid vitrimer powders with different particle size distributions were prepared and characterized. The effects of particle size on the mechanical properties of regenerated epoxy-acid vitrimers were investigated by dynamic mechanical analysis and uniaxial tensile tests. In addition, other processing parameters such as temperature, time, and pressure are discussed, as well as their interaction with particle size. This study helped to refine the vitrimer reprocessing condition parameter toolbox, providing experimental support for the easy and reliable control of the kinetics of the bond exchange reaction.

Discovery and application of traditional Chinese medicine efficacy markers based on systematic traditional Chinese medicine / 中国中药杂志

The quality marker(Q-marker) of traditional Chinese medicine(TCM) is a new concept of TCM quality control proposed in recent years. It is a hot issue in the research of modern Chinese medicine. The TCM efficacy is a high-level summary of the TCM therapeutic effect under the guidance of TCM theory. On this basis, it is of considerable significance to explore the TCM efficacy marker for the TCM modernization. However, the traditional research strategy based on the single herb and decoction piece in macro TCM level, or the drug research strategy based on the biological effect of the targets, is quite different from the characteristics of multiple components of TCM, as well as the weak and low-selective effect of Chinese medicine ingredients on targets. Therefore, how to select representative ingredients to characterize the TCM overall efficacy is a problematic point in establishing TCM efficacy markers. In this paper, the concept and method of Q-marker were introduced into the study of Chinese medicine efficacy. The research method for systematic TCM was used to systematically discuss the connotation of TCM efficacy markers, the principles of discovery and determination, common research ideas and techniques by taking the representative research results as an example. This study provides new ideas for the research and discovery of TCM efficacy markers.

Study on components efficacy of Salviae Miltiorrhizae Radix et Rhizoma based on systematic traditional Chinese medicine / 中国中药杂志

This paper aimed to establish efficacy systems of tanshinones and salvianolic acids, two representative substances in Salviae Miltiorrhizae Radix et Rhizoma by using literature mining and biological network construction, based on systematic traditional Chinese medicine theory. The systematic study on the efficacy of traditional Chinese medicine was carried out from the basic unit, the structure and relationship between the basic units, the boundary of the research object and the function of the system, so as to explain the overall efficacy of the two kinds of components at the molecular level. Firstly, we collected the elements of the efficacy systems of these two kinds of components by literature mining, and defined their boundaries based on biological processes. After that, the structure of the efficacy systems was clarified according to the relationship in the KEGG database. Finally, the function of the efficacy systems was analyzed from the level of pharmacology, pharmacodynamics, and efficacy, revealing the scientific connotation of traditional Chinese medicine efficacy system. The results showed that there were 201 targets(elements), 12 target sets(boundary), and 12 pathway networks(structure) in salvianolic acids' efficacy system. Meanwhile, there were 189 targets(elements), 11 target sets(boundary), and 11 pathway networks(structure) in tanshinones' efficacy system. The results suggested that the functions of salvia-nolic acids' and tanshinones' efficacy systems were different in pharmacology and pharmacodynamics from aspects of elements, boundary, relationship and structure, but they were same in functional level as both of them could promote blood circulation, remove blood stasis, clear away heart-fire, relieve restlessness, and soothe the nerves. Based on systematic traditional Chinese medicine, we constructed the efficacy system of two representative components in Salviae Miltiorrhizae Radix et Rhizoma in this paper, elucidated the overall efficacy and builded the bridge between reductionism and holism in traditional Chinese medicine.

Study on efficacy markers of heat-clearing and detoxifying effect of Lonicerae Japonicae Flos based on systematic traditional Chinese medicine / 中国中药杂志

Lonicerae Japonicae Flos has a long history of heat-clearing and detoxifying effect. The description of its efficacy in Chinese Pharmacopoeia of past dynasties is relatively stable, and it is an excellent carrier for the study of efficacy markers. Guided by the theory of systematic traditional Chinese medicine, heat-clearing and detoxifying effect efficacy system of Lonicerae Japonicae Flos was taken as an example in this study to clarify the elements(active ingredients) of Lonicerae Japonicae Flos in heat-clearing and detoxifying efficacy system, determine the boundary(signal pathway), establish the structure(system dynamics model), identify the system functions corresponding to pharmacology, efficacy and effects(heat-clearing and detoxifying effect), and explore the application of system dynamics model in the discovery of efficacy markers of traditional Chinese medicine. In this paper, the dynamic models of interleukin 1(IL-1) and interleukin 6(IL-6) in vivo were established to predict the expression of related factors in IL-1 and IL-6 signaling pathways of different components and their combinations in Lonicerae Japonicae Flos by dynamic network, so as to find the effective markers of heat-clearing and detoxification of Lonicerae Japonicae Flos. The results showed that the lower the concentration of chlorogenic acid, the higher the inhibition rate of Jun N-terminal kinase(JNK) at downstream of IL-1 by the combination of chlorogenic acid and linalool; the higher the concentration of luteolin in IL-6 pathway, the higher the inhibition rate of C-reactive protein(CRP) at downstream of IL-6 by the combination of chlorogenic acid and luteolin. It revealed that the potential efficacy markers of Lonicerae Japonicae Flos in heat-clearing and detoxifying effect based on IL-1 signaling pathway were chlorogenic acid and linalool, and the potential efficacy markers of Lonicerae Japonicae Flos in heat-clearing and detoxifying effect based on IL-6 signaling pathway were chlorogenic acid and luteolin. This study provided methodological guidance for the discovery of efficacy markers of traditional Chinese medicine.

Controlled Placement of Microparticles at the Water-Liquid Crystal Elastomer Interface.

Controlled placement of microparticles is of prime importance in production of microscale superstructures. In this work, we demonstrate the remote control of microparticle placement using a photoactivated surface profile of a liquid crystal elastomer (LCE) coating. We employ light-responsive LCEs with preimposed patterns of molecular orientation (director) in the plane of coating. Upon UV illumination, these in-plane director distortions translate into deterministic topographic change of the LCE coating. Microparticles placed at the interface between the LCE coating and water, guided by gravity, gather at the bottom of photoinduced troughs. The effect is reversible: when the substrates are irradiated with visible light, the coatings become flat and the microparticle arrays disorganize again. The proposed noncontact manipulation of particles by photoactivated LCEs may be useful in development of drug delivery or tissue engineering applications.

Low f-Number Diffraction-Limited Pancharatnam-Berry Microlenses Enabled by Plasmonic Photopatterning of Liquid Crystal Polymers.

Microlenses are desired by a wide range of industrial applications while it is always challenging to make them with diffraction-limited quality. Here, it is shown that high-quality microlenses based on Pancharatnam-Berry (PB) phases can be made with liquid crystal polymers by using a plasmonic photopatterning technique. Based on the generalized Snell's law for the PB phases, PB microlenses with a range of focal lengths and f-numbers are designed and fabricated and their point-spread functions and ability to image micrometer-sized particles are carefully characterized. The results show that these PB microlenses with f-number down to 2 are all diffraction-limited. The capability of arraying these PB microlenses with 100% filling factor with a step-and-flash approach is further demonstrated.

Nature-effect relationship research of traditional Chinese medicine for promoting blood circulation and removing blood stasis based on nature combination / 中国中药杂志

The efficacy of traditional Chinese medicine is the therapeutic effect of the drug on the body. The nature of traditional Chinese medicine is a further generalization of the effect of efficacy,and there is an intrinsic relationship between efficacy and nature of traditional Chinese medicine. In this study,the nature-effect relationship is found on the whole level,through the research mode of " nature combination-targets of traditional Chinese medicine-modules of protein interaction network-efficiency". The results showed that the warm-pungent-liver protein interaction network mainly participated in lipid catabolic process,blood coagulation,platelet activation,heme oxidation,platelet degranulation,apoptotic process,acute inflammatory response to exert the effect of anti-tumor,antithrombotic,anti-myocardial ischemia and anti-inflammatory.

Author Correction: Liquid crystal elastomer coatings with programmed response of surface profile.

The original version of this Article contained errors in Figs. 1a, 2a, 3a, and 4b, in which the units on the scale bars incorrectly read 'µm' rather than the correct 'nm.' This has been corrected in both the PDF and HTML versions of the Article.

Liquid crystal elastomer coatings with programmed response of surface profile.

Stimuli-responsive liquid crystal elastomers with molecular orientation coupled to rubber-like elasticity show a great potential as elements in soft robotics, sensing, and transport systems. The orientational order defines their mechanical response to external stimuli, such as thermally activated muscle-like contraction. Here we demonstrate a dynamic thermal control of the surface topography of an elastomer prepared as a coating with a pattern of in-plane molecular orientation. The inscribed pattern determines whether the coating develops elevations, depressions, or in-plane deformations when the temperature changes. The deterministic dependence of the out-of-plane dynamic profile on the in-plane orientation is explained by activation forces. These forces are caused by stretching-contraction of the polymer networks and by spatially varying molecular orientation. The activation force concept brings the responsive liquid crystal elastomers into the domain of active matter. The demonstrated relationship can be used to design coatings with functionalities that mimic biological tissues such as skin.

The Ingestion of Fluorescent, Magnetic Nanoparticles for Determining Fluid-uptake Abilities in Insects.

Fluid-feeding insects ingest a variety of liquids, which are present in the environment as pools, films, or confined to small pores. Studies of liquid acquisition require assessing mouthpart structure and function relationships; however, fluid uptake mechanisms are historically inferred from observations of structural architecture, sometimes unaccompanied with experimental evidence. Here, we report a novel method for assessing fluid-uptake abilities with butterflies (Lepidoptera) and flies (Diptera) using small amounts of liquids. Insects are fed with a 20% sucrose solution mixed with fluorescent, magnetic nanoparticles from filter papers of specific pore sizes. The crop (internal structure used for storing fluids) is removed from the insect and placed on a confocal microscope. A magnet is waved by the crop to determine the presence of nanoparticles, which indicate if the insects are able to ingest fluids. This methodology is used to reveal a widespread feeding mechanism (capillary action and liquid bridge formation) that is potentially shared among Lepidoptera and Diptera when feeding from porous surfaces. In addition, this method can be used for studies of feeding mechanisms among a variety of fluid-feeding insects, including those important in disease transmission and biomimetics, and potentially other studies that involve nano- or micro-sized conduits where liquid transport requires verification.

The effect of cupping therapy for low back pain: A meta-analysis based on existing randomized controlled trials.

BACKGROUND: LBP is one of the most common symptoms with high prevalence throughout the world. Conflicting conclusions exist in RCTs on cupping for LBP. OBJECTIVE: To assess the effects and safety of cupping for the patients with LBP. METHODS: Pubmed, Cochrane Library databases, and Embase database were electronically researched. RCTs reporting the cupping for the patients with LBP were included. The meta-analysis was conducted using Review Manager software (version 5.3, Nordic Cochrane Centre). The primary outcome was VAS scores. The secondary outcomes included ODI scores, MPPI scores and complications. RESULTS: Six RCTs were included in this synthesized analysis. The results showed that cupping therapy was superior to the control management with respect to VAS scores (SMD: -0.73, [95% CI: -1.42 to -0.04]; P= 0.04), and ODI scores (SMD: -3.64, [95% CI: -5.85 to -1.42]; P= 0.001). There was no statistical significant difference as regard to MPPI scores. No serious adverse event was reported in the included studies. CONCLUSIONS: Cupping therapy can significantly decrease the VAS scores and ODI scores for patients with LBP compared to the control management. High heterogeneity and risk of bias existing in studies limit the authenticity of the findings.

Patterning of Lyotropic Chromonic Liquid Crystals by Photoalignment with Photonic Metamasks.

Controlling supramolecular self-assembly in water-based solutions is an important problem of interdisciplinary character that impacts the development of many functional materials and systems. Significant progress in aqueous self-assembly and templating has been demonstrated by using lyotropic chromonic liquid crystals (LCLCs) as these materials show spontaneous orientational order caused by unidirectional stacking of plank-like molecules into elongated aggregates. In this work, it is demonstrated that the alignment direction of chromonic assemblies can be patterned into complex spatially-varying structures with very high micrometer-scale precision. The approach uses photoalignment with light beams that exhibit a spatially-varying direction of light polarization. The state of polarization is imprinted into a layer of photosensitive dye that is protected against dissolution into the LCLC by a liquid crystalline polymer layer. The demonstrated level of control over the spatial orientation of LCLC opens opportunities for engineering materials and devices for optical and biological applications.

Mouthpart conduit sizes of fluid-feeding insects determine the ability to feed from pores.

Fluid-feeding insects, such as butterflies, moths and flies (20% of all animal species), are faced with the common selection pressure of having to remove and feed on trace amounts of fluids from porous surfaces. Insects able to acquire fluids that are confined to pores during drought conditions would have an adaptive advantage and increased fitness over other individuals. Here, we performed feeding trials using solutions with magnetic nanoparticles to show that butterflies and flies have mouthparts adapted to pull liquids from porous surfaces using capillary action as the governing principle. In addition, the ability to feed on the liquids collected from pores depends on a relationship between the diameter of the mouthpart conduits and substrate pore size diameter; insects with mouthpart conduit diameters larger than the pores cannot successfully feed, thus there is a limiting substrate pore size from which each species can acquire liquids for fluid uptake. Given that natural selection independently favoured mouthpart architectures that support these methods of fluid uptake (Diptera and Lepidoptera share a common ancestor 280 Ma that had chewing mouthparts), we suggest that the convergence of this mechanism advocates this as an optimal strategy for pulling trace amounts of fluids from porous surfaces.

Controlling placement of nonspherical (boomerang) colloids in nematic cells with photopatterned director.

Placing colloidal particles in predesigned sites represents a major challenge of the current state-of-the-art colloidal science. Nematic liquid crystals with spatially varying director patterns represent a promising approach to achieve a well-controlled placement of colloidal particles thanks to the elastic forces between the particles and the surrounding landscape of molecular orientation. Here we demonstrate how the spatially varying director field can be used to control placement of non-spherical particles of boomerang shape. The boomerang colloids create director distortions of a dipolar symmetry. When a boomerang particle is placed in a periodic splay-bend director pattern, it migrates towards the region of a maximum bend. The behavior is contrasted to that one of spherical particles with normal surface anchoring, which also produce dipolar director distortions, but prefer to compartmentalize into the regions with a maximum splay. The splay-bend periodic landscape thus allows one to spatially separate these two types of particles. By exploring overdamped dynamics of the colloids, we determine elastic driving forces responsible for the preferential placement. Control of colloidal locations through patterned molecular orientation can be explored for future applications in microfluidic, lab on a chip, sensing and sorting devices.

Command of active matter by topological defects and patterns.

Self-propelled bacteria are marvels of nature with a potential to power dynamic materials and microsystems of the future. The challenge lies in commanding their chaotic behavior. By dispersing swimming Bacillus subtilis in a liquid crystalline environment with spatially varying orientation of the anisotropy axis, we demonstrate control over the distribution of bacterial concentration, as well as the geometry and polarity of their trajectories. Bacteria recognize subtle differences in liquid crystal deformations, engaging in bipolar swimming in regions of pure splay and bend but switching to unipolar swimming in mixed splay-bend regions. They differentiate topological defects, heading toward defects of positive topological charge and avoiding negative charges. Sensitivity of bacteria to preimposed orientational patterns represents a previously unknown facet of the interplay between hydrodynamics and topology of active matter.