A certain amount of photocurable monomers biphenyl diacrylate and lauryl acrylate was added to liquid crystal (LC) molecules. The LC alignment was stabilized with a certain pretilt angle after a fixed amount of UV exposure under an applied voltage to the LC cell. The pretilt angle of the LC was successfully adjusted over the whole range from 0.8°to 90°continuously by simply increasing the monomer concentration in the LCs. Polymer bumps formed with a rather uniform size around 250 nm in diameter, and chain-like clusters were found on the polymer-coated substrate. The advancing contact angle of water was applied as an index of the surface hydrophobicity. The pretilt angle of the LC monotonically increases along with an increase in the advancing contact angle of water on the polymer-coated substrate. The surface hydrophobicity of the substrate plays an essential role in governing the pretilt angle in the polymer-stabilized LC alignment system.
Anisotropic spreading of liquids and elongated droplet shapes are often encountered on surfaces decorated with a periodic micropattern of linear surface topographies. Numerical calculations and wetting experiments show that the shape evolution of droplets that are slowly growing on a surface with parallel grooves can be grouped into two distinct morphological regimes. In the first regime, the liquid of the growing droplet spreads only into the direction parallel to the grooves. In the second regime, the three-phase contact line advances also perpendicular to the grooves, whereas the growing droplets approach a scale-invariant shape. Here, we demonstrate that shapes of droplets in contact with a large number of linear grooves are identical to the shapes of droplets confined to a plane chemical stripe, where this mapping of shapes is solely based on the knowledge of the cross section of the linear grooves and the material contact angle. The spectrum of interfacial shapes on the chemical stripe can be exploited to predict the particular growth mode and the asymptotic value of the base eccentricity in the limit of droplets covering a large number of grooves. The proposed model shows an excellent agreement with experimentally observed base eccentricities for droplets on grooves of various cross sections. The universality of the model is underlined by the accurate match with available literature data for droplet eccentricities on parallel chemical stripes.
The pretilt angle of liquid crystal (LC) molecules in LC cells was manipulated by adding a mixture of two photocurable monomers, alkyl acrylate and biphenyl diacrylate, into the LCs after the UV treatment. The hexyl acrylate and octadecyl acrylate were applied to examine the alkyl chain length effect on the pretilt angle control under the condition of a fixed concentration of biphenyl diacrylate. The LC alignment was continuously adjusted from homogeneous to homeotropic alignment in the polymer-stabilized LC system by simply increasing the alkyl acrylate concentration in the LCs. At a given molar concentration of alkyl acrylate, the addition of octadecyl acrylate exhibits higher pretilt angle than that of hexyl acrylate. Both the pretilt angle of the LCs and advancing contact angle of water on the inner surfaces of LC cells simultaneously changed due to surface chemical nature and surface roughness. The pretilt angle increases along with an increase in the advancing contact angle. As a consequence, the surface advancing contact angle acts as an index for pretilt angle control.
The objectives of this study were to understand the clinical presentations of febrile young infants with severe bacterial infection (SBI), and to investigate the pathogen variations throughout the vaccine era and after antenatal group B Streptococcus (GBS) screening. All infants < 90 days old with a body temperature of ≥38.0°C and admitted to the emergency department were retrospectively enrolled in our study. SBI was defined as a positive culture of urine, blood, or cerebrospinal fluid. All clinical variables were analyzed and compared between the SBI group and the non-SBI group, to identify the relevant risk factors for SBI in infants with pyrexia. A total of 498 infants were studied, 279 of whom (56%) had SBI. The body temperature at triage was higher in the SBI group, and the difference was highly obvious in the neonatal group. White blood cell count and C-reactive protein levels were both significantly higher in the SBI group ( P < .05), whereas neutrophil percentage and band percentage demonstrated no significant differences. Escherichia coli was the most common pathogen and plasmid-mediated extended-spectrum lactamases were detected in up to 9.1%. GBS was detected in 16 cases of bacteremia (6 cases with concurrent meningitis). The body temperature at triage may provide a clue for differentiating sick babies, especially in the neonatal group. Complete serum analysis is required for infection survey, especially white blood cell and C-reactive protein. Escherichia coli is the most common pathogen, and clinician should raise awareness of drug resistance in some patients. The prevalence of GBS infection in the young infant group remains high after routine antenatal GBS screening
Directional wicking and spreading of liquids can be achieved by regular micro-patterns of specifically designed topographic features that break the reflection symmetry of the underlying pattern. The present study aims to understand the formation and stability of wetting films during the evaporation of volatile liquid drops on surfaces with a micro-pattern of triangular posts arranged in a rectangular lattice. Depending on the density and aspect ratio of the posts, we observe either spherical-cap shaped drops with a mobile three-phase contact line or the formation of circular or angular drops with a pinned three-phase contact line. Drops of the latter class eventually evolve into a liquid film extending to the initial footprint of the drop and a shrinking cap-shaped drop sitting on the film. The drop evolution is controlled by the density and aspect ratio of the posts, while no influence of the orientation of the triangular posts on the contact line mobility becomes evident. Our experiments corroborate previous results of systematic numerical energy minimization, predicting that conditions for a spontaneous retraction of a wicking liquid film depend weakly on the orientation of the film edge relative to the micro-pattern.
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