Deterministic Formation and Growth of Dendritic Crystals of Attractive Colloids.

Dendrites are ubiquitous crystals produced in supersaturated solutions and supercooled melts, but considerably less is known about their formation and growth kinetics. Here, the key factors are explored that dictate dendrite formation and growth, utilizing experimental colloidal models in which the particles act as molecules with Mie potential. Depletion attraction is employed to colloids and manipulate their strength to control supersaturation.

Auxetic Photonic Patterns with Ultrasensitive Mechanochromism.

Photonic crystals with mechanochromic properties are currently under intensive study to provide intuitive colorimetric detection of strains for various applications. However, the sensitivity of color change to strain is intrinsically limited, as the degree of deformation determines the wavelength shift. To overcome this limitation, auxetic photonic patterns that exhibit ultra-sensitive mechanochromism are designed.

Direct Determination of the Phase Diagram of a Depletion-Mediated Colloidal System.

Depletion is one widely used potential to modulate colloidal interaction because it enables the production of a wide variety of crystalline and glassy phases of spherical and shape-tailored colloids. The attractive depletion potential gives rise to qualitatively new behavior. However, depletion-mediated phase behaviors have never been systematically investigated experimentally regarding pair potentials for aqueous suspensions.

Hydration breaking and chemical ordering in a levitated NaCl solution droplet beyond the metastable zone width limit: evidence for the early stage of two-step nucleation.

For over two decades, NaCl nucleation from a supersaturated aqueous solution has been predicted to occur a two-step nucleation (TSN) mechanism, , two sequential events, the formation of locally dense liquid regions followed by structural ordering. However, the formation of dense liquid regions in the very early stage of TSN has never been experimentally observed. By using a state-of-the-art technique, a combination of electrostatic levitation (ESL) and synchrotron X-ray and Raman scatterings, we find experimental evidence that indicates the formation of dense liquid regions in NaCl bulk solution at an unprecedentedly high level of supersaturation ( = 2.

Association between Irritable Bowel Syndrome and Risk of Osteoporosis in Korean Premenopausal Women.

Objective: The objective of this study is to evaluate irritable bowel syndrome (IBS) as a risk factor for osteoporosis and osteoporotic fracture in Korean women after controlling for basic confounding factors and considering detailed demographic and clinical information.

Subjects And Methods: We performed a nationwide population-based retrospective cohort analysis and matched every IBS case with a non-IBS case at a 1:4 frequency ratio based on age. The population consisted of female patients with data in the Health Insurance Review and Assessment (HIRA) database from 2002 to 2010.

Effect of antimicrobial photodynamic therapy with Chlorella and Curcuma extract on Streptococcus mutans biofilms.

Background: Antimicrobial photodynamic therapy (aPDT) using natural photosensitive agents is an effective method for preventing oral diseases of bacterial origin. The purpose of this study was to evaluate the antimicrobial effect of aPDT, using powdered extracts of Chlorella and Curcuma, on the biofilms of Streptococcus mutans (S. mutans), a bacterium that is known to cause dental caries.

Stiffness of the interface between a colloidal body-centered cubic crystal and its liquid.

Equilibrium interfaces were established between body-centered cubic (BCC) crystals and their liquid using charged colloidal particles in an electric bottle. By measuring a time series of interfacial positions and computing the average power spectrum, their interfacial stiffness was determined according to the capillary fluctuation method. For the (100) and the (114) interfaces, the stiffnesses were 0.

Colloidal assembly in droplets: structures and optical properties.

Colloidal assembly in emulsion drops provides fundamental tools for studying optimum particle arrangement under spherical confinement and practical means for producing photonic microparticles. Recent progress has revealed that energetically favored cluster configurations are different from conventional supraballs, which could enhance optical performance. This paper reviews state-of-the-art emulsion-templated colloidal clusters, and particularly focuses on recently reported novel structures such as icosahedral, decahedral, and single-crystalline face-centered cubic (fcc) clusters.

Real-Time Monitoring of Colloidal Crystallization in Electrostatically-Levitated Drops.

Colloidal crystallization is analogous to the crystallization in bulk atomic systems in various aspects, which has been explored as a model system. However, a real-time probing of the phenomenon still remains challenging. Here, a levitation system for a study of colloidal crystallization is demonstrated.

Clustering Effects of Metabolic Factors and the Risk of Metabolic Syndrome.

Background: Metabolic syndrome is a major risk factor for cardiovascular disease. Clustering of a combination of individual factors that increase the actual rather than the expected prevalence might be helpful in understanding the pathophysiology of metabolic syndrome. The aim of this study was to analyze the most influential factors for metabolic syndrome to assess clustering factors of metabolic syndrome.

Photonic Microcapsules Containing Single-Crystal Colloidal Arrays with Optical Anisotropy.

Colloidal particles with a repulsive interparticle potential spontaneously form crystalline lattices, which are used as a motif for photonic materials. It is difficult to predict the crystal arrangement in spherical volume as lattices are incompatible with a spherical surface. Here, the optimum arrangement of charged colloids is experimentally investigated by encapsulating them in double-emulsion drops.

Coherence and pulse duration characterization of the PAL-XFEL in the hard X-ray regime.

We characterize the spatial and temporal coherence properties of hard X-ray pulses from the Pohang Accelerator Laboratory X-ray Free Electron Laser (PAL-XFEL, Pohang, Korea). The measurement of the single-shot speckle contrast, together with the introduction of corrections considering experimental conditions, allows obtaining an intrinsic degree of transverse coherence of 0.85 ± 0.

Direct observation of crystallization and melting with colloids.

We study the kinetics of crystal growth and melting of two types of colloidal crystals: body-centered cubic (BCC) crystals and face-centered cubic (FCC) crystals. A dielectrophoretic "electric bottle" confines colloids, enabling precise control of the motion of the interface. We track the particle motion, and by introducing a structural order parameter, we measure the jump frequencies of particles to and from the crystal and determine from these the free-energy difference between the phases and the interface mobility.

The relationship between hypertension and sleep duration: an analysis of the fifth Korea National Health and Nutrition Examination Survey (KNHANES V-3).

Introduction: Hypertension is a significant risk factor for cardiovascular disease (CVD). The majority of patients, however, cannot easily maintain a healthy blood pressure. Therefore, lifestyle modifications are important and may include getting enough sleep.

Controlled pixelation of inverse opaline structures towards reflection-mode displays.

Pixelated inverse opals with red, green, and blue colors were prepared by hybridizing convective assembly of colloidal particles and photolithography techniques. The brilliant structural colors, high mechanical stability, and small feature size of the pixels were simultaneously accomplished, thereby providing color reflectors potentially useful for display devices. Moreover, this hybridized method provides a general means to create multi-colored photonic crystals.

The association between 25-hydroxyvitamin D and mammographic density in healthy pre- and postmenopausal women regardless of the menstrual cycle phase: a cross-sectional study.

Vitamin D deficiency is a known risk factor of breast cancer. An association between vitamin D and breast density has been suggested; however, it remains controversial. The aim of this study was to determine the association between serum 25-hydroxyvitamin D [25(OH)D] level and mammographic density.

Microfluidic fabrication of SERS-active microspheres for molecular detection.

In this paper, we demonstrated a microfluidic system for fabricating microspheres with hierarchical surface nanopatterns for molecular detection based on surface-enhanced Raman scattering (SERS). Briefly, a photocurable silica suspension was emulsified into monodisperse droplets using a microfluidic device composed of two coaxial glass capillaries. The silica particles in each droplet protruded through the interface and spontaneously formed a hexagonal array.

Lithographically-featured photonic microparticles of colloidal assemblies.

We have described a new and promising strategy for the fabrication of composite and porous photonic crystal microparticles that combines the self-assembly of colloidal particles with photolithography techniques. We fabricated silica/SU-8 composite microparticles with photonic bandgaps via four steps: (1) deposition of the silica colloidal crystals on the photoresist, (2) embedding of the colloidal crystals in the photoresist, (3) UV exposure through a photomask and subsequent development, and (4) release of the microparticles from the substrate. Embedding was performed above the glass transition temperature (T(g)) of uncrosslinked SU-8.