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. Dendrites are predominantly produced under conditions of low supersaturation, where the separation between crystals is large due to slow nucleation. The dendrites do not emerge directly from nuclei. Instead, isotropic grains, initially produced from nuclei, morph into polygons. Arms then sprout from the vertices of these polygons, eventually giving rise to dendrites. Triggering this polygon-to-dendrite transformation requires a high diffusional flux. This necessitates a prolonged diffusion time to maintain a steep concentration gradient in the surrounding environment even after the transformation from circular grains to polygons.

Centrifugation-Mediated Crystal Growth of Attractive Colloids for Band Edge Lasing.

Attractive depletion interactions are utilized to organize colloidal particles into crystalline arrays with high crystallinity through spontaneous phase separation. However, uncontrolled nucleation frequently leads to the formation of crystalline grains with varied crystal orientations, which hampers the optical performance of photonic crystals. Here, colloidal crystals have been engineered with uniform orientation and high surface coverage by applying centrifugal force during the depletion-induced assembly of polystyrene particles. The centrifugal force encourages the particles to move toward the bottom surface, which fosters heterogeneous nucleation and supports rapid crystal growth, yielding densely-packed and uniformly-arranged crystal grains with high reflectivity. This study has observed that the nucleation and crystal growth behavior is significantly influenced by the salt concentration. Based on the pair potentials, the transition boundary has been quantitatively analyzed between fluid and crystal phases and identified the threshold for homogeneous nucleation. Utilizing the high-reflectivity colloidal crystals, band-edge lasing is achieved by dissolving the water-soluble dye into the aqueous suspensions. Upon optical excitation, a lasing emission characterized is observed by a narrow spectral width at the short-wavelength band edge. Notably, the laser wavelength can be adjusted by altering the salt concentration or particle diameter, offering a versatile approach to tuning the optical properties.

Risk factors of menopause after allogeneic hematopoietic cell transplantation in premenopausal adult women.

OBJECTIVES: Allogeneic hematopoietic stem-cell transplantation (HCT) is the only curative option for most hematologic malignancies. However, HSCT can cause early menopause and various complications in premenopausal women. Therefore, we aimed to investigate risk factors predicting early menopause and its clinical implications among survivors post HCT. METHODS: We retrospectively analyzed 30 adult women who had received HCT at premenopausal status between 2015 and 2018. We excluded patients who had received autologous stem cell transplantation, had relapsed, or died of any cause within 2 years of HCT. RESULTS: The median age at HCT was 41.6 years (range, 22-53). Post-HCT menopause was identified in 90% of myeloablative conditioning (MAC) HCT and 55% of reduced-intensity conditioning (RIC) HCT (p = .101). In the multivariate analysis, the post-HCT menopausal risk was 21 times higher in a MAC regimen containing 4 days of busulfan (p = .016) and 9.3 times higher in RIC regimens containing 2-3 days of busulfan (p = .033) than that of non-busulfan-based conditioning regimens. CONCLUSIONS: Higher busulfan dose in conditioning regimens is the most significant risk factor affecting post-HCT early menopause. Considering our data, we need to decide on conditioning regimens and individualized fertility counseling before HCT for premenopausal women.

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. In this work, we implement three distinct phases of fluid, crystal, and glass by adjusting the concentrations of depletant and salt in the aqueous suspension of polystyrene particles. To define the phase boundary between the fluid and crystal, we calculate pair potential with a superposition of van der Waals, electrostatic, and depletion interactions. Two unknown parameters in the pair potential─the concentration of ionic impurities and the ratio of the molar concentration of depletant to osmolarity─are experimentally determined from sets of reflectance spectra. The interparticle spacing in the crystalline phase is extracted from the peak wavelength originating from Bragg diffraction, which corresponds to the interparticle separation at energy minimum in the pair potential. The boundary between the fluid and crystal is well defined with the depth of the energy well of 3kBT. By contrast, the onset of glass formation is better characterized by not the well depth but the assembly rate, which is estimated from the slope of the pair potential from force balance. Glasses are produced as the speed exceeds 300 µm/s. That is, crystals are produced by enthalpy gain overwhelming entropy loss, whereas glasses are kinetically produced due to fast jamming.

Photonic Microbeads Templated by Oil-in-Oil Emulsion Droplets for High Saturation of Structural Colors.

Photonic microbeads containing crystalline colloidal arrays are promising as a key component of structural-color inks for various applications including printings, paintings, and cosmetics. However, structural colors from microbeads usually have low color saturation and the production of the beads requires delicate and time-consuming protocols. Herein, elastic photonic microbeads are designed with enhanced color saturation through facile photocuring of oil-in-oil emulsion droplets. Dispersions of highly-concentrated silica particles in elastomer precursors are microfluidically emulsified into immiscible oil to produce monodisperse droplets. The silica particles spontaneously form crystalline arrays in the entire volume of the droplets due to interparticle repulsion which is unperturbed by the diffusion of the surrounding oil whereas weakened for oil-in-water droplets. The crystalline arrays are permanently stabilized by photopolymerization of the precursor, forming elastic photonic microbeads. The microbeads are transferred into the refractive-index-matched biocompatible oil. The high crystallinity of colloidal arrays increases the reflectivity at stopband and the index matching reduces incoherent scattering at the surface of the microbeads, enhancing color saturation. The colors can be adjusted by mixing two distinctly colored microbeads. Also, low stiffness and high elasticity reduce foreign-body sensation and enhance fluidity, potentially serving as pragmatic structural colorants for photonic inks.

Terahertz radiation from propagating acoustic phonons based on deformation potential coupling.

We report on new THz electromagnetic emission mechanism from deformational coupling of acoustic (AC) phonons with electrons in the propagation medium of non-polar Si. The epicenters of the AC phonon pulses are the surface and interface of a GaP transducer layer whose thickness (d) is varied in nanoscale from 16 to 45 nm. The propagating AC pulses locally modulate the bandgap, which in turn generates a train of electric field pulses, inducing an abrupt drift motion at the depletion edge of Si. The fairly time-delayed THz bursts, centered at different times (t1T H z, t2T H z, and t3T H z), are concurrently emitted only when a series of AC pulses reach the point of the depletion edge of Si, even without any piezoelectricity. The analysis on the observed peak emission amplitudes is consistent with calculations based on the combined effects of mobile charge carrier density and AC-phonon-induced local deformation, which recapitulates the role of deformational potential coupling in THz wave emission in a formulatively distinct manner from piezoelectric counterpart.

Late complications and quality of life assessment for survivors receiving allogeneic hematopoietic stem cell transplantation.

PURPOSE: The survival rates of patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT) have improved. However, HSCT can induce significant long-term complications. Therefore, we investigated the late complications and risk factors for quality of life (QOL) post-HSCT. METHODS: We retrospectively analyzed 67 adult survivors over 2 years after HSCT between 2015 and 2018 at Ulsan University Hospital, Ulsan, Korea. The survey data including FACT-BMT, Hospital Anxiety and Depression Scale, and NCCN Distress Thermometer were collected as patient-reported outcomes using a tablet PC during a routine practice of survivorship clinic. RESULTS: The median age was 46 years. The most common symptom was fatigue (80.6%). Younger age (< 60 years), acute lymphoblastic leukemia (ALL), chronic graft-versus-host disease (GVHD), and immunosuppressant use were significantly associated with worse QOL and depression. Additionally, younger survivors (< 60 years) showed significantly more fatigue and anxiety compared with elderly survivors (≥ 60 years). Female sex was significantly associated with lower physical well-being and higher distress than male sex. CONCLUSION: Younger patients (< 60 years), female, ALL, chronic GVHD, and continuous immunosuppressant use were significant risk factors for worse QOL and depression. Hence, creating a more active survivorship care plan after HSCT, specifically for these patients, is required.

Young Adults Make Rational Sexual Decisions.

We examined risky sexual choice under the lens of rational decision-making. Participants (N = 257) completed a novel sexual-choice task in which they selected from among hypothetical sexual partners varying in physical attractiveness and in the probability that one would contract a sexually transmitted infection (STI) from a one-time sexual encounter with them. We found that nearly all participants evaluated the sexual-choice alternatives in a coherent fashion consistent with utility-based theories of rational choice. In subsequent analyses, we classified participants' responses according to whether their sexual preferences were based on maximizing attractiveness or minimizing the risk of STIs. Finally, we established an association between sexual choice in our task and reported real-world sexual risk-taking.

The Effects of Self-Talk on Shooting Athletes' Motivation.

Self-talk is helpful in motivating shooting athletes and promoting effortful behavior. This study aimed to examine how the degree and intensity of self-talk of shooting athletes during matches affects their actual internal motivation and careers. In particular, the primary objective was to determine the effects of the level and intensity of self-talk on the effort value, fun and interest, tension and anxiety, and competence of intrinsic motivation for different levels of achievement and athletic performance. One hundred seventy participants who were shooting athletes registered with the Korea Shooting Federation (national team, n = 55; high performance team, n = 62; general team, n = 53). The self-talk questionnaire was developed to measure the Test of Performance Strategies (TOPS). The intrinsic motivation scale developed and applicable to sports situations was used to measure the motivation of the shooting athletes. Significant differences were observed using MANOVA as well as the basic statistics of intrinsic motivation by self-talk. The intrinsic motivation self-talk was correlated to effort value, fun and interest, and competence. There was a significant relationship between shooting athletes' self-talk and intrinsic motivation. This study indicated that athletes using self-talk experienced more fun and interest, and they perceived higher effort value and competence. Further, the multiple regression analysis revealed that self-talk affected the intrinsic motivational factors of effort value and fun and interest.

Positional relationship between the pectoralis major and external abdominal oblique muscles for consideration during dual-plane breast augmentation.

During dual plane breast augmentation (DPBA), the costal origin of the pectoralis major (the PM) should be cut to ensure appropriate coverage and positioning of an implant. However, surgeons sometimes make inappropriate planar incisions and insufficient muscular incisions because the external abdominal oblique (the EAO) muscle partially overlaps the lateral portion of the PM. The goal of this study was to clarify the positional relationship between the PM and EAO with the aim of improving the accuracy of implant and muscular incisions during DPBA. Forty sides of 20 embalmed and fresh cadavers were dissected. The midline and midclavicular line (MCL) were used as reference lines for measurements. We clarified the overlapping patterns between the PM and EAO, and measured the distances from the MCL to the borders of those two muscles. The costal part of the PM originated from the 5th (25%), 6th (70%), or 7th rib (5%), respectively. The distances from the MCL to the lateral border of the PM at the 4th, 5th, and 6th ribs were 49.8 mm, 30.5 mm, and 6.3 mm, respectively. In 90% of the specimens, the PM and the EAO overlapped near the MCL. The width of the overlapping portion between the PM and EAO was about 25 mm. This study is one of the first to suggest an innovative approach for explaining the positional relationships between the PM and EAO. Our findings can be useful for surgeons attempting to produce optimal outcomes in DPBA, especially in procedures that involve patients of different races. Clin. Anat. 31:339-346, 2018. © 2018 Wiley Periodicals, Inc.

Regioselective Growth of Colloidal Crystals Induced by Depletion Attraction.

Colloidal crystals display photonic stopbands that generate reflective structural colors. While micropatterning offers significant value for various applications, the resolution is somewhat limited for conventional top-down approaches. In this work, a simple, single-step bottom-up approach is introduced to produce photonic micropatterns through depletion-mediated regioselective growth of colloidal crystals. Lithographically-featured micropatterns with planar surfaces and nano-needle arrays as substrates are employed. Heterogeneous nucleation is drastically suppressed on nano-needle arrays due to minimal particle-to-needles overlap of excluded volumes, while it is promoted on planar surfaces with large particle-to-plane volume overlap, enabling regioselective growth of colloidal crystals. This strategy allows high-resolution micropatterning of colloidal photonic crystals, with a minimum feature size as small as 10 µm. Stopband positions, or structural colors, are controllable through concentration and depletant and salt, as well as particle size. Notably, secondary colors can be created through structural color mixing by simultaneously crystallizing two different particle sizes into their own crystal grains, resulting in two distinct reflectance peaks at controlled wavelengths. The simple and highly reproducible method for regioselective colloidal crystallization provides a general route for designing elaborate photonic micropatterns suitable for various applications.

Realizing molecular pixel system for full-color fluorescence reproduction: RGB-emitting molecular mixture free from energy transfer crosstalk.

A full-color molecular pixel system is realized for the first time using simple mixtures composed of RGB-emitting excited-state intramolecular proton transfer (ESIPT) dyes, each of which has delicately tailored Stokes shift and independent emission capability completely free from energy transfer crosstalk between them. It is demonstrated that the whole range of emission colors enclosed within the RGB color triangle on the CIE 1931 diagram is predictable and conveniently reproducible from the RGB molecular pixels not only in the solution but also in the polymer film. It must be noted that mixing ratios to reproduce the desired color coordinates can be precisely calculated on the basis of additive color theory according to their molecular pixel behavior.

Centrifugation-Assisted Growth of Single-Crystalline Grains in Microcapsules.

Colloidal crystals have been tailored in a format of microspheres to use them as a building block to construct macroscopic photonic surfaces. However, the polycrystalline grains grown from the spherical surface usually exhibit low reflectivity. Although single-crystalline microspheres have been produced, it is difficult to control the crystal orientation. Here, we design spherical microcapsules with density anisotropy that contain single-crystalline grains along the heavy side. The microcapsules spontaneously align to have a heavy side down under the action of gravity and display a bright and uniform reflection color from the entire surface of the grains. Key to the success is the use of gentle centrifugal force to initiate nucleation and grow single-crystalline grains from the heavy side through depletion attraction. The microcapsules have density anisotropy due to the heterogeneity of the shell thickness, which causes them to self-align under centrifugation. At the same time, particles are accumulated on the heavy side, which produces many tiny grains on the heavy side immediately after the centrifugation. With controlled depletion attraction among particles, only a few grains survive during postincubation through Ostwald ripening, and one or a few giant single-crystalline grains are finally produced along the heavy side of each microcapsule.

Structural Color Mixing in Microcapsules through Exclusive Crystallization of Binary and Ternary Colloids.

Colloidal crystals are designed as photonic microparticles for various applications. However, conventional microparticles generally have only one stopband from a single lattice constant, which restricts the range of colors and optical codes available. Here, photonic microcapsules are created that contain two or three distinct crystalline grains, resulting in dual or triple stopbands that offer a wider range of colors through structural color mixing. To produce distinct colloidal crystallites from binary or ternary colloidal mixtures, the interparticle interaction is manipulated using depletion forces in double-emulsion droplets. Aqueous dispersions of binary or ternary colloidal mixtures in the innermost droplet are gently concentrated in the presence of a depletant and salt by imposing hypertonic conditions. Different-sized particles crystallize into their own crystals rather than forming random glassy alloys to minimize free energy. The average size of the crystalline grains can be adjusted with osmotic pressure, and the relative ratio of distinct grains can be controlled with the mixing ratio of particles. The resulting microcapsules with small grains and high surface coverage are almost optically isotropic and exhibit highly-saturated mixed structural colors and multiple reflectance peaks. The mixed color and reflectance spectrum are controllable with the selection of particle sizes and mixing ratios.

Light-enhanced molecular polarity enabling multispectral color-cognitive memristor for neuromorphic visual system.

An optoelectronic synapse having a multispectral color-discriminating ability is an essential prerequisite to emulate the human retina for realizing a neuromorphic visual system. Several studies based on the three-terminal transistor architecture have shown its feasibility; however, its implementation with a two-terminal memristor architecture, advantageous to achieving high integration density as a simple crossbar array for an ultra-high-resolution vision chip, remains a challenge. Furthermore, regardless of the architecture, it requires specific material combinations to exhibit the photo-synaptic functionalities, and thus its integration into various systems is limited. Here, we suggest an approach that can universally introduce a color-discriminating synaptic functionality into a two-terminal memristor irrespective of the kinds of switching medium. This is possible by simply introducing the molecular interlayer with long-lasting photo-enhanced dipoles that can adjust the resistance of the memristor at the light-irradiation. We also propose the molecular design principle that can afford this feature. The optoelectronic synapse array having a color-discriminating functionality is confirmed to improve the inference accuracy of the convolutional neural network for the colorful image recognition tasks through a visual pre-processing. Additionally, the wavelength-dependent optoelectronic synapse can also be leveraged in the design of a light-programmable reservoir computing system.

Strategic emission color tuning of highly fluorescent imidazole-based excited-state intramolecular proton transfer molecules.

Highly fluorescent molecules harnessing the excited state intramolecular proton transfer (ESIPT) process are promising for a new generation of displays and light sources because they can offer very unique and novel optoelectronic properties which are different from those of conventional fluorescent dyes. To realize innovative ESIPT devices comprising full emission colors over the whole visible region, a molecular design strategy for predictable emission color tuning should be established. Here, we have developed a general strategy for a wide-range spectral tuning of imidazole-based ESIPT materials based on three different strategies--introduction of a nodal plane model, extension of effective conjugation length, and modification of heterocyclic rings. A series of nine ESIPT molecules were designed, synthesized and comprehensively investigated for their characteristic emission properties. All these molecules commonly showed no clear and transparent visible range absorption with no absorption color, but showed different colors of intense photoluminescence over broad visible regions from 450 nm (HPI) to 630 nm (HPNO) depending on their molecular structure. With the aid of density functional theory and time-dependent DFT calculations using M06, wB97XD, and B3LYP parameters with the 6-31G(d,p) basis set, these tuned emission bands of nine emitters were assigned from the stabilized excited state conformations that were derived from modified molecular structures.

The Role of the Graphene Oxide (GO) and Reduced Graphene Oxide (RGO) Intermediate Layer in CZTSSe Thin-Film Solar Cells.

Cu2ZnSn(S,Se)4 (CZTSSe) solar cells with low cost and eco-friendly characteristics are attractive as future sources of electricity generation, but low conversion efficiency remains an issue. To improve conversion efficiency, a method of inserting intermediate layers between the CZTSSe absorber film and the Mo back contact is used to suppress the formation of MoSe2 and decomposition of CZTSSe. Among the candidates for the intermediate layer, graphene oxide (GO) and reduced GO have excellent properties, including high-charge mobility and low processing cost. Depending on the type of GO, the solar cell parameters, such as fill factor (FF), were enhanced. Thus, the conversion efficiency of 6.3% was achieved using the chemically reduced GO intermediate layer with significantly improved FF.

Understanding the effect of nonmetallic impurities in regenerated cathode materials for lithium-ion battery recycling by tracking down impurity elements.

The regeneration of cathode materials would be the highest value-added direction in lithium-ion battery (LIB) recycling research. Li[NixMnyCoz]O2 (NMC) is regenerated from actual industrial scale LIB leachate and purified leachate to investigate the precipitation behavior of impurities, which include potentially toxic elements, such as F, Cl, and S. Regenerated precursors from the actual leachate, purified precursors, and a control sample are synthesized using the hydroxide co-precipitation method. Additionally, simulated precursors from simulated leachate are prepared in order to separate the effects of nonmetallic elements from the effects of metallic elements. The structure and electrochemical properties of the regenerated precursors and the corresponding cathode materials are examined. We first detect the presence of a significant amount of nonmetal elements, such as F as well as well-known metal elements, which include Al, Cu, and Fe, in the regenerated NMC. The concept of yield of precipitation (YOP) is introduced to assess the precipitation behavior of each element during the co-precipitation of the precursors. According to the concentration and YOP in the leachate and the precursors, six metal and three nonmetal elements are categorized. This categorization of impurity elements will certainly provide the LIB recycling industry with a valuable quality control guide.

Efficient Photon Extraction in Top-Emission Organic Light-Emitting Devices Based on Ampicillin Microstructures.

The desire to enhance the efficiency of organic light-emitting devices (OLEDs) has driven to the investigation of advanced materials with fascinating properties. In this work, the efficiency of top-emission OLEDs (TEOLEDs) is enhanced by introducing ampicillin microstructures (Amp-MSs) with dual phases (α-/ß-phase) that induce photoluminescence (PL) and electroluminescence (EL). Moreover, Amp-MSs can adjust the charge balance by Fermi level (EF ) alignment, thereby decreasing the leakage current. The decrease in the wave-guided modes can enhance the light outcoupling through optical scattering. The resulting TEOLED demonstrates a record-high external quantum efficiency (EQE) (maximum: 68.7% and average: 63.4% at spectroradiometer; maximum: 44.8% and average: 42.6% at integrating sphere) with a wider color gamut (118%) owing to the redshift of the spectrum by J-aggregation. Deconvolution of the EL intensities is performed to clarify the contribution of Amp-MSs to the device EQE enhancement (optical scattering by Amp-MSs: 17.0%, PL by radiative energy transfer: 9.1%, and EL by J-aggregated excitons: 4.6%). The proposed TEOLED outperforms the existing frameworks in terms of device efficiency.