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Nicholas Nguyen
Nicholas Nguyen

Liquid Crystals.epub ##HOT##



Liquid crystals (LCs) are anisotropic fluids that combine the long-range order of crystals with the mobility of liquids1,2. This combination of properties has been widely used to create reconfigurable materials that optically report information about their environment, such as changes in electric fields (smart-phone displays) 3 , temperature (thermometers) 4 or mechanical shear 5 , and the arrival of chemical and biological stimuli (sensors)6,7. An unmet need exists, however, for responsive materials that not only report their environment but also transform it through self-regulated chemical interactions. Here we show that a range of stimuli can trigger pulsatile (transient) or continuous release of microcargo (aqueous microdroplets or solid microparticles and their chemical contents) that is trapped initially within LCs. The resulting LC materials self-report and self-regulate their chemical response to targeted physical, chemical and biological events in ways that can be preprogrammed through an interplay of elastic, electrical double-layer, buoyant and shear forces in diverse geometries (such as wells, films and emulsion droplets). These LC materials can carry out complex functions that go beyond the capabilities of conventional materials used for controlled microcargo release, such as optically reporting a stimulus (for example, mechanical shear stresses generated by motile bacteria) and then responding in a self-regulated manner via a feedback loop (for example, to release the minimum amount of biocidal agent required to cause bacterial cell death).




Liquid Crystals.epub



Purpose: To compare the effectiveness of intermittent occlusion therapy (IO therapy) using liquid crystal glasses and continuous occlusion therapy using traditional adhesive patches for treating amblyopia.


Methods: Children 3-8 years of age with previously untreated, moderate, unilateral amblyopia (visual acuity of 20/40 to 20/100 in the amblyopic eye) were enrolled in this randomized controlled trial. Amblyopia was associated with strabismus, anisometropia, or both. All subjects had worn any optimal refractive correction for at least 12 weeks without improvement. Subjects were randomized into two treatment groups: a 4-hour IO therapy group with liquid crystal glasses (Amblyz), set at 30-second opaque/transparent intervals (occluded 50% of wear time), and a 2-hour continuous patching group (occluded 100% of wear time). For each patient, visual acuity was measured using ATS-HOTV before and after 12 weeks of treatment.


Conclusions: In this pilot study, IO therapy with liquid crystal glasses is not inferior to adhesive patching and is a promising alternative treatment for children 3-8 years of age with moderate amblyopia.


The necessity for long-term treatments of chronic diseases has encouraged the development of novel long-acting parenteral formulations intending to improve drug pharmacokinetics and therapeutic efficacy. Lately, one of the novel approaches has been developed based on lipid-based liquid crystals. The lyotropic liquid crystal (LLC) systems consist of amphiphilic molecules and are formed in presence of solvents with the most common types being cubic, hexagonal and lamellar mesophases. LC injectables have been recently developed based on polar lipids that spontaneously form liquid crystal nanoparticles in aqueous tissue environments to create the in-situ long-acting sustained-release depot to provide treatment efficacy over extended periods. In this manuscript, we have consolidated and summarized the various type of liquid crystals, recent formulation advancements, analytical evaluation, and therapeutic application of lyotropic liquid crystals in the field of parenteral sustained release drug delivery.


Bridging soft matter physics, materials science and engineering, polymer-modified liquid crystals are an exciting class of materials. They represent a vibrant field of research, promising advances in display technologies, as well as non-display uses.Describing all aspects of polymer-dispersed and polymer-stabilized liquid crystals, the broad coverage of this book makes it a must-have resource for anyone working in the area. The reader will find expert accounts covering basic concepts, materials synthesis and polymerization techniques, properties of various dispersed and stabilized phases, and critical overviews of their applications.Written by leaders in the field, this book provides a state-of-the-art treatment of the topic. It will be essential reading for graduate students, as well as academic and industrial researchers needing an up-to-date guide to the field.


N2 - The properties of liquid crystals can be modelled using an order parameter which describes the variability of the local orientation of rod-like molecules. Defects in the director field can arise due to external factors such as applied electric or magnetic fields, or the constraining geometry of the cell containing the liquid crystal material. Understanding the formation and dynamics of defects is important in the design and control of liquid crystal devices, and poses significant challenges for numerical modelling. In this paper we consider the numerical solution of a Q-tensor model of a nematic liquid crystal, where defects arise through rapid changes in the Q-tensor over a very small physical region in relation to the dimensions of the liquid crystal device. The efficient solution of the resulting six coupled partial differential equations is achieved using a finite element based adaptive moving mesh approach, where an unstructured triangular mesh is adapted towards high activity regions, including those around defects. Spatial convergence studies are presented using a stationary defect as a model test case, and the adaptive method is shown to be optimally convergent using quadratic triangular finite elements. The full effectiveness of the method is then demonstrated using a challenging two-dimensional dynamic Pi-cell problem involving the creation, movement, and annihilation of defects.


AB - The properties of liquid crystals can be modelled using an order parameter which describes the variability of the local orientation of rod-like molecules. Defects in the director field can arise due to external factors such as applied electric or magnetic fields, or the constraining geometry of the cell containing the liquid crystal material. Understanding the formation and dynamics of defects is important in the design and control of liquid crystal devices, and poses significant challenges for numerical modelling. In this paper we consider the numerical solution of a Q-tensor model of a nematic liquid crystal, where defects arise through rapid changes in the Q-tensor over a very small physical region in relation to the dimensions of the liquid crystal device. The efficient solution of the resulting six coupled partial differential equations is achieved using a finite element based adaptive moving mesh approach, where an unstructured triangular mesh is adapted towards high activity regions, including those around defects. Spatial convergence studies are presented using a stationary defect as a model test case, and the adaptive method is shown to be optimally convergent using quadratic triangular finite elements. The full effectiveness of the method is then demonstrated using a challenging two-dimensional dynamic Pi-cell problem involving the creation, movement, and annihilation of defects.


It may, therefore, be concluded that intermolecular interaction energy calculations are helpful in analyzing the liquid crystallinity in terms of molecular forces. Results favour the nematic behaviour of the system at higher temperatures because the molecules of 4CB are capable of sliding along the long molecular axis with a simultaneous relative orientation of 40. At very high temperatures, an all-round breaking of dispersion forces results and all possible stacking geometries (even perpendicular stacking) are almost equally favoured, which ultimately cause the system to pass on to an isotropic melt state.


Benzyl alcohol (C7H8O, MW 108.14) is an antimicrobial preservative, disinfectant, and solvent. As an antimicrobial preservative, it is commonly used in concentrations up to 2% in pharmaceutical formulations. Benzyl alcohol is a clear, colorless, oily liquid that has a faint, aromatic odor and a sharp, burning taste. It is soluble 1 g in 25 mL of water and is miscible with ethanol.6


Propylene glycol (C3H8O2) occurs as a clear, colorless, viscous, hygroscopic, practically odorless liquid with a sweet taste somewhat resembling glycerin. It is miscible with acetone, chloroform, 95% ethanol, glycerin, and water.10


Purified water is water that is obtained by distillation, ion exchange, reverse osmosis, or some other suitable process. Water has a specific gravity of 0.9971 at room temperature, a melting point of 0C, and a boiling point of 100C. It is miscible with most polar solvents and is chemically stable in all physical states (ice, liquid, and steam).11


Simethicone CH3[Si(CH3)2.O]nSi(CH3)3, dimethyl silicone fluid, poly(dimethylsiloxane) is a fluid silicone that occurs as a clear, colorless, odorless liquid that is insoluble in water, alcohol, acetone, and methyl alcohol.12


Although there are many types of kidney stones, four main types are classified by the material they are made of. Up to 75 percent of all kidney stones are composed primarily of calcium. Stones can also be made up of uric acid (a normal waste product), cystine (a protein building block), or struvite (a phosphate mineral). Stones form when there is more of the compound in the urine than can be dissolved. This imbalance can occur when there is an increased amount of the material in the urine, a reduced amount of liquid urine, or a combination of both.


The production of patterned photonic films on a large scale remains a challenge. Here, we report on a new class of photonic materials that are based on oxetane liquid crystals (LCs). Patterned reflective coatings can be produced from these materials on flexible substrates by using flexographic printing. This industrially relevant process allows for upscaling in future applications. Furthermore, the oxetane LCs used do not require an inert atmosphere for photopolymerization, unlike previously described acrylate systems. We show that the flexographic printing process results in excellent alignment, and that the patterns produced display a high resolution. Additionally, we demonstrate that free-standing photonic reflecting foils can also be produced from these materials. Our new oxetane-based patterned iridescent colored materials have potential application for both esthetic purposes as well as anticounterfeit labels. 041b061a72


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