Upconversion Material-Plasmonic Metal-Semiconductor Ternary Heteronanostructures for Wide-Range Solar-to-Chemical Energy Conversion.

Harvesting full-spectrum solar energy is a critical issue for developing high-performance photocatalysts. Here, we report a hierarchical heteronanostructure consisting of upconverting, plasmonic, and semiconducting materials as a solar-to-chemical energy conversion platform that can exploit a wide range of sunlight (from ultraviolet (UV) to near-infrared). Lanthanide-doped NaYF4 nanorod-spherical Au nanocrystals-TiO2 ternary hybrid nanostructures with a well-controlled configuration and intimate contact between the constituent materials could be synthesized by a wet-chemical method. Notably, the prepared ternary hybrids exhibited high photocatalytic activity for the H2 evolution reaction under simulated solar and near-infrared light irradiation due to their broadband photoresponsivity and strong optical interaction between the constituents. Through systematic studies on the mechanism of energy transfer during the photocatalysis of the ternary hybrids, we revealed that upconverted photon energy from the upconversion domain transfers to the Au and TiO2 domains primarily through the Förster resonance energy transfer process, resulting in enhanced photocatalysis.

Estimating the economic value of ultrafine particle information: a contingent valuation method.

Global concern regarding ultrafine particles (UFPs), which are particulate matter (PM) with a diameter of less than 100 nm, is increasing. These particles are difficult to measure using the current methods because their characteristics are different from those of other air pollutants. Therefore, a new monitoring system is required to obtain accurate UFP information, which will raise the financial burden of the government and people. In this study, we estimated the economic value of UFP information by evaluating the willingness-to-pay (WTP) for the UFP monitoring and reporting system. We used the contingent valuation method (CVM) and the one-and-one-half-bounded dichotomous choice (OOHBDC) spike model. We analyzed how the respondents' socio-economic variables, as well as their cognition level of PM, affected their WTP. Therefore, we collected WTP data of 1040 Korean respondents through an online survey. The estimated mean WTP for building a UFP monitoring and reporting system is KRW 6958.55-7222.55 (USD 6.22-6.45) per household per year. We found that people satisfied with the current air pollutant information, and generally possessing relatively greater knowledge of UFPs, have higher WTP for a UFP monitoring and reporting system. We found that people are willing to pay more than the actual installation and operating costs of current air pollution monitoring systems. If the collected UFP data is disclosed in an easily accessible manner, as is current air pollutant data, it will be possible to secure more public acceptance for expanding the UFP monitoring and reporting system nationwide.

Co-Responses of Soil Organic Carbon Pool and Biogeochemistry to Different Long-Term Fertilization Practices in Paddy Fields.

Long-term application of soil organic amendments (SOA) can improve the formation of soil organic carbon (SOC) pool as well as soil fertility and health of paddy lands. However, the effects of SOA may vary with the input amount and its characteristics. In this work, a descriptive field research was conducted during one cropping season to investigate the responses of various SOC fractions to different long-term fertilization practices in rice fields and their relationships with soil biogeochemical properties and the emission of greenhouse gases (GHG). The field sites included two conventional paddies applied with chemical fertilizer (CF) or CF + rice straw (RS) and six organic agriculture paddies applied with oilseed cake manure (OCM) + wheat straw (WS), cow manure (CM) + WS, or CM + RS. The two paddy soils treated with CM + RS had significantly higher concentrations of recalcitrant to labile C forms, such as loss-on-ignition C (LOIC; 56-73 g kg-1), Walkley-Black C (WBC; 20-25 g kg-1), permanganate oxidizable C (POXC; 835-853 mg kg-1), and microbial biomass carbon (MBC; 133-141 mg kg-1), than soils treated with other SOA. Likewise, long-term application of CM + RS seemed to be the best for regulating soil fertility parameters, such as ammonium (11-141 mg kg-1); phosphate (61-106 mg kg-1); and soluble Ca, K, and Mg (7-10, 0.5-1.2, and 1.9-3.8 mg kg-1, respectively), although the results varied with the location and soil properties of rice fields. Additionally, the two paddy sites had the largest cumulative methane emission (754-762 kg ha-1), seemingly attributed to increased microbial biomass and labile C fractions. The significant correlations of most SOC fractions with soil microbial biomass, trophic factors, and methane emissions were confirmed with multivariate data analysis. It was also possible to infer that long-term SOA application, especially with CM + RS, enhanced interaction in belowground paddy fields, contributing to soil fertility and rice production sustainability. Based on our findings, we suggest the need for analysis of various types of SOC fractions to efficiently manage soil fertility and quality of paddy fields, C sequestration, and GHG emissions.

How Does a Face Mask Impact Speech Perception?

Face masks are mandatory during the COVID-19 pandemic, leading to attenuation of sound energy and loss of visual cues which are important for communication. This study explores how a face mask affects speech performance for individuals with and without hearing loss. Four video recordings (a female speaker with and without a face mask and a male speaker with and without a face mask) were used to examine individuals' speech performance. The participants completed a listen-and-repeat task while watching four types of video recordings. Acoustic characteristics of speech signals based on mask type (no mask, surgical, and N95) were also examined. The availability of visual cues was beneficial for speech understanding-both groups showed significant improvements in speech perception when they were able to see the speaker without the mask. However, when the speakers were wearing the mask, no statistical significance was observed between no visual cues and visual cues conditions. Findings of the study demonstrate that provision of visual cues is beneficial for speech perception for individuals with normal hearing and hearing impairment. This study adds value to the importance of the use of communication strategies during the pandemic where visual information is lost due to the face mask.

Influence of the Noise-Canceling Technology on How We Hear Sounds.

PURPOSE: This study explores the influence of the noise-canceling technology in commercial earphones on sound pressure levels and preferred listening levels in terms of hearing protection. MATERIALS AND METHODS: Thirty individuals completed puretone audiometry and real-ear measurements to assess sound pressure levels at the level of the eardrum with and without the activation of the noise-canceling function. The Knowles Electronics Manikin for Acoustic Research was used to investigate the acoustic characteristics of two environmental sounds (bus and café). Two types of earphones (wireless and wired canal type) were utilized in the study. RESULTS: For both bus and café noises, in the low-frequency range, sound pressure levels were significantly decreased for all types of earphones when the noise-canceling function was turned on. The same results were observed for the whole frequency range. In terms of preferred listening levels, the wireless canal type and wired canal type earphones showed significant reduction in volume levels. CONCLUSION: The findings of the study show that for both low- and whole frequency range, the use of noise-canceling function significantly decreases the sound pressure levels of the signal for all styles of earphones, suggesting a potential of the noise-canceling technology in hearing protection.

Effects of Fine Particulate Matter on Cardiovascular Disease Morbidity: A Study on Seven Metropolitan Cities in South Korea.

Objectives: The primary purpose of this study is to analyze the relationship between the first occurrence of hospitalization for cardiovascular disease (CVD) and particulate matter less than 2.5 µm in diameter (PM2.5) exposure, considering average PM2.5 concentration and the frequency of high PM2.5 concentration simultaneously. Methods: We used large-scale cohort data from seven metropolitan cities in South Korea. We estimated hazard ratios (HRs) and 95% confidence intervals (CIs) using the Cox proportional-hazards model, including annual average PM2.5 and annual hours of PM2.5 concentration exceeding 55.5 µg/m3 (FH55). Results: We found that the risk was elevated by 11.6% (95% CI, 9.7-13.6) for all CVD per 2.9 µg/m3 increase of average PM2.5. In addition, a 94-h increase in FH55 increased the risk of all CVD by 3.8% (95% CI, 2.8-4.7). Regarding stroke, we found that people who were older and had a history of hypertension were more vulnerable to PM2.5 exposure. Conclusion: Based on the findings, we conclude that accurate forecasting, information dissemination, and timely warning of high concentrations of PM2.5 at the national level may reduce the risk of CVD occurrence.

Occult parotid involvement in early-stage squamous cell carcinoma of the external auditory canal.

BACKGROUND: The importance of elective parotidectomy in early-stage squamous cell carcinoma (SCC) of the external auditory canal (EAC) is not well established. METHODS: A retrospective study of 43 patients with early-stage SCC of the EAC who underwent parotidectomy in conjunction with lateral temporal bone resection at three centers. RESULTS: Overall occult parotid involvement (OPI) rate in early-stage SCC of the EAC was 13.9% (6/43). When considering both the anteroposterior position and the bony-cartilaginous position, patients with SCC in both the anterior wall and cartilaginous portion exhibited significantly higher OPI than other locations (37.5% vs. 0%, p = 0.001), with an increase in the OPI predictive value. CONCLUSION: SCC located in either the anterior wall of the EAC or the cartilaginous portion of the EAC or both simultaneously showed a high prevalence of OPI, and elective parotidectomy should be considered in those patients.

Photocatalytic Decomposition of Organic Dyes Using a Rotating Cylinder System.

In this study, a rotating cylinder system was used in the photocatalytic decomposition of organic dyes in aqueous medium for water purification. To this end, the titania nanoparticle dispersion was mixed with an organic dye solution under a rotating inner cylinder at controlled speed. The rate constant was adjusted by changing the speed of rotation to determine the optimal circulating velocity. Since nanoparticle dispersion is a secondary contaminant after wastewater treatment, the titania paste was deposited on the inner surface of the stationary outer cylinder to form a photocatalytic film. During repeated batch-mode operation, the deactivation of the deposited film was analyzed by measuring the rate constant as a function of time. Continuous operation was also used to remove organic dye in the water to study factors affecting the removal efficiency of methylene blue. Higher rotating velocity and slow feed rate facilitated the removal of contaminants via desorption of adsorbed dyes with adequate retention time.

Fabrication of Silica Microspheres Containing TiO2 or Aluminum Zinc Oxide Nanoparticles via Self-Assembly: Application in Water Purification.

In this study, silica micro-particles containing titania (TiO2) or aluminum zinc oxide (AZO) nanopar-ticles were synthesized using emulsion droplets as micro-reactors, for water purification application via photocatalytic decomposition of organic dyes. Towards this end, aqueous silicic acid solution has been emulsified with aqueous dispersion of TiO2 or AZO nanoparticles in a continuous oil phase to form tiny droplets, followed by subsequent self-assembly of the droplets via evaporation. The resulting composite microparticles were controlled to obtain a spherical or porous morphology by adjusting the concentration of the nanoparticle dispersion. As a demonstrative application, the resulting composite micro-particles have been used as photocatalysts for the removal of methylene blue under UV irradiation. In the case of silica microparticles containing AZO nanoparticles, the adsorption of organic pollutants combined with photocatalytic decomposition was found to be effective, and trace amounts of the pollutant remained after the removal process.

Synthesis of Polymeric Nanoparticles by Emulsion Polymerization for Particle Self-Assembly Applications.

Polymeric nanoparticles with sufficient solid concentration could be synthesized by emulsion polymerization without using surfactants. The polymeric nano-colloids with surface functional groups were synthesized to obtain carboxylated polystyrene beads or amidine polystyrene nanoparticles. Sodium styrene sulfonate was also adopted for the synthesis of sulfonated polystyrene nanoparticles less than 50 nm in diameter using KPS as an initiator. The diameter of the carboxylated particles could be controlled by adjusting the reaction parameters such as the amount of monomer, cross-linker, and polymerization temperature. The range of the diameter of the resulting polymeric beads was 100 to 200 nm, which is useful size range for bio-sensing purposes. Amidine polystyrene nanoparticles less than 50 nm could be fabricated using a cationic comonomer, MTC. As an application of the polymeric beads, the porous inorganic particles could be synthesized by colloidal templating using emulsions as micro-reactors.

Synthesis of Macroporous Silica Particles by Continuous Generation of Droplets for Insulating Materials.

We report on the synthesis of porous silica particles by self-assembly routes in a continuous manner for application to thermal insulators. A continuous process was employed to produce tiny droplets containing precursor materials such as silica and organic templates for self-organization to fabricate particles with well defined pores. A rotating cylinder system or a spray drying process was adopted to form emulsions or aerosol droplets as micro-reactors for self-assembly, and the physical properties including the thermal conductivity of the resulting porous particles were compared between the two methods. The porous particles could be coated as a thick film by solution dripping, and the fluorination treatment using a silane coupling agent was performed to produce superhydrophobic surfaces of insulating layers by a lotus effect.

Dispersion Polymerization of Polystyrene Particles Using Alcohol as Reaction Medium.

In this study, monodisperse polystyrene nanospheres were prepared by dispersion polymerization using alcohol as reaction medium to prepare colloidal clusters of the latex beads. Polyvinylpyrrolidone (PVP) and 2-(methacryloyloxy)ethyltrimethylammonium chloride (MTC) were used as dispersion stabilizer and comonomer, respectively. The particle size could be controlled by adjusting the reactant compositions such as the amount of stabilizer, comonomer, and water in the reactant mixture. The size and monodispersity of the polymeric particles could be also controlled by changing the reaction medium with different alcohols other than ethanol or adjusting the polymerization temperature. The synthesized particles could be self-organized inside water-in-oil emulsion droplets by evaporation-driven self-assembly to produce colloidal clusters of the polymeric nanospheres.

Full empirical potential curves for the X(1)Σ(+) and A(1)Π states of CH(+) from a direct-potential-fit analysis.

All available "conventional" absorption/emission spectroscopic data have been combined with photodissociation data and translational spectroscopy data in a global analysis that yields analytic potential energy and Born-Oppenheimer breakdown functions for the X(1)Σ(+) and A(1)Π states of CH(+) and its isotopologues that reproduce all of the data (on average) within their assigned uncertainties. For the ground X(1)Σ(+) state, this fully quantum mechanical "Direct-Potential-Fit" analysis yielded an improved empirical well depth of 𝔇e = 34 362.8(3) cm(-1) and equilibrium bond length of re = 1.128 462 5 (58) Å. For the A(1)Π state, the resulting well depth and equilibrium bond length are 𝔇e = 10 303.7(3) cm(-1) and re = 1.235 896 (14) Å, while the electronic isotope shift from the hydride to the deuteride is ΔTe = - 5.99(±0.08) cm(-1).

Enhanced luminescence of Cu-In-S nanocrystals by surface modification.

We have synthesized highly luminescent Cu-In-S nanocrystals by heating the mixture of metal carboxylates and alkylthiol under inert atmosphere. We modified the surface of CIS nanocrystals with zinc carboxylate and subsequent injection of alkylthiol. As a result of the surface modification, highly luminescent CIS@ZnS core/shell nanocrystals were synthesized. The luminescence quantum yield (QY) of best CIS@ZnS nanocrystals was above 50%, which is more than 10 times higher than the initial QY of CIS nanocrystals before surface modification (QY = 3%). Detailed study on the luminescence mechanism implies that etching of the surface of nanocrystals by dissociated carboxylate group (CH3COO-) and formation of epitaxial shell by Zn with sulfur from alkylthiol efficiently removed the surface defects which are major non-radiative recombination sites in semiconductor nanocrystals. In this study, we developed a novel surface modification route for monodispersed highly luminescent Cu-In-S nanocrystals with less toxic and highly stable precursors.

Bulk synthesis of ordered macroporous silica particles for superhydrophobic coatings.

We report the bulk synthesis of ordered macroporous ceramic particles by the emulsion templating process. Large polystyrene (PS) beads and small silica nanoparticles were assembled simultaneously inside an emulsion, which formed composite structured particles during the evaporation of droplets. Then, by burning out PS beads, macroporous ceramic particle films were produced on substrate. The size of ordered macroporous particles could be controlled by adjusting the emulsification condition for confining emulsions. As well, the pore size could be controlled by changing the diameter of PS beads. The surface of the ordered macroporous particle films was coated with fluorinated molecules, which have shown superhydrophobic property due to multi-scale roughness.

Synthesis of porous carbon balls from spherical colloidal crystal templates.

Spherical inverse opal (IO) porous carbon was produced utilizing silica colloidal crystal spheres as templates. The spherical colloidal crystals were obtained through the self-assembly of monodisperse particles inside an emulsion droplet with confined geometry. The templates were inverted using a carbon precursor, phenol-formaldehyde (PF) resol. We demonstrated a two-step synthesis involving the subsequent infiltration of the PF resol precursor into the spherical colloidal crystal template and a one-step synthesis using a silica colloidal solution containing dissolved PF resol. In the former case, the sizes of the IO carbon balls were controlled by the size of the colloidal crystal templates, and diameters of a few micrometers up to 50 µm were obtained. The average diameter of the macropores created by the silica particles was 230 nm. Moreover, meso-/macroporous IO carbon balls were created using block-copolymer templates in the PF resol. In the one-step synthesis, the concentration of PF resol in the colloidal solution controlled the diameter of the IO carbon balls. IO balls smaller than 3 µm were obtained from the direct addition of 5% PF resol. The one-step synthesis produced rather irregular porous structures reflecting the less ordered crystallization processes inside the spherical colloidal crystals. Nitrogen adsorption and cyclic voltammetry measurements were conducted to measure the specific area and electroactive surface area of the IO carbon balls. The specific area of the mesopores-incorporated IO carbon balls was 1.3 times higher than that of bare IO carbon balls. Accordingly, the meso-/macroporous porous carbon balls exhibited higher electrocatalytic properties than the macroporous carbon balls.

Individual subject classification for Alzheimer's disease based on incremental learning using a spatial frequency representation of cortical thickness data.

Patterns of brain atrophy measured by magnetic resonance structural imaging have been utilized as significant biomarkers for diagnosis of Alzheimer's disease (AD). However, brain atrophy is variable across patients and is non-specific for AD in general. Thus, automatic methods for AD classification require a large number of structural data due to complex and variable patterns of brain atrophy. In this paper, we propose an incremental method for AD classification using cortical thickness data. We represent the cortical thickness data of a subject in terms of their spatial frequency components, employing the manifold harmonic transform. The basis functions for this transform are obtained from the eigenfunctions of the Laplace-Beltrami operator, which are dependent only on the geometry of a cortical surface but not on the cortical thickness defined on it. This facilitates individual subject classification based on incremental learning. In general, methods based on region-wise features poorly reflect the detailed spatial variation of cortical thickness, and those based on vertex-wise features are sensitive to noise. Adopting a vertex-wise cortical thickness representation, our method can still achieve robustness to noise by filtering out high frequency components of the cortical thickness data while reflecting their spatial variation. This compromise leads to high accuracy in AD classification. We utilized MR volumes provided by Alzheimer's Disease Neuroimaging Initiative (ADNI) to validate the performance of the method. Our method discriminated AD patients from Healthy Control (HC) subjects with 82% sensitivity and 93% specificity. It also discriminated Mild Cognitive Impairment (MCI) patients, who converted to AD within 18 months, from non-converted MCI subjects with 63% sensitivity and 76% specificity. Moreover, it showed that the entorhinal cortex was the most discriminative region for classification, which is consistent with previous pathological findings. In comparison with other classification methods, our method demonstrated high classification performance in both categories, which supports the discriminative power of our method in both AD diagnosis and AD prediction.

In-line monitoring and interpretation of an indomethacin anti-solvent crystallization process by near-infrared spectroscopy (NIRS).

PAT (process analytical technology) has been emphasized as one of key elements for the full implementation of QbD (quality-by-design) in the pharmaceutical area. NIRS (near-infrared spectroscopy) has been studied intensively as an in-line/on-line monitoring tool in chemical and biomedical industries. A precise and reliable monitoring of the particle characteristics during crystallization along with a suitable control strategy should be highly encouraged for the conformance to new quality system of pharmaceutical products. In this study, the anti-solvent crystallization process of indomethacin (IMC) was monitored using an in-line NIRS. IMC powders were produced via anti-solvent crystallization using two schemes; 'S-to-A' (solvent-to-antisolvent) and 'A-to-S' (antisolvent-to-solvent). In-line NIR spectra were analyzed by a PCA (principal component analysis) method. Although pure α-form IMC powder was resulted under A-to-S scheme, a mixture of the α-form and γ-form was produced for S-to-A case. By integrating the PCA results with off-line characterization (SEM, XRD, DSC) data, the crystallization process under each scheme was elucidated by three distinct consecutive steps. It was demonstrated that in-line NIRS, combined with PCA, can be very useful to monitor in real time and interpret the anti-solvent crystallization process with respect to the polymorphism and particle size.

A multi-resolution scheme for distortion-minimizing mapping between human subcortical structures based on geodesic construction on Riemannian manifolds.

In this paper, we deal with a subcortical surface registration problem. Subcortical structures including hippocampi and caudates have a small number of salient features such as heads and tails unlike cortical surfaces. Therefore, it is hard, if not impossible, to perform subcortical surface registration with only such features. It is also non-trivial for neuroanatomical experts to select landmarks consistently for subcortical surfaces of different subjects. We therefore present a landmark-free approach for subcortical surface registration by measuring the amount of mesh distortion between subcortical surfaces assuming that the surfaces are represented by meshes. The input meshes can be constructed using any surface modeling tool available in the public domain since our registration method is independent of a surface modeling process. Given the source and target surfaces together with their representing meshes, the vertex positions of the source mesh are iteratively displaced while preserving the underlying surface shape in order to minimize the distortion to the target mesh. By representing each surface mesh as a point on a high-dimensional Riemannian manifold, we define a distance metric on the manifold that measures the amount of distortion from a given source mesh to the target mesh, based on the notion of isometry while penalizing triangle flipping. Under this metric, we reduce the distortion minimization problem to the problem of constructing a geodesic curve from the moving source point to the fixed target point on the manifold while satisfying the shape-preserving constraint. We adopt a multi-resolution framework to solve the problem for distortion-minimizing mapping between the source and target meshes. We validate our registration scheme through several experiments: distance metric comparison, visual validation using real data, robustness test to mesh variations, feature alignment using anatomic landmarks, consistency with previous clinical findings, and comparison with a surface-based registration method, LDDMM-surface.

Facile synthesis of TiO2 inverse opal electrodes for dye-sensitized solar cells.

Engineering of TiO(2) electrode layers is critical to guaranteeing the photoconversion efficiency of dye-sensitized solar cells (DSSCs). Recently, a novel approach has been introduced for producing TiO(2) electrodes using the inverted structures of colloidal crystals. This paper describes a facile route to producing ordered macroporous electrodes from colloidal crystal templates for DSSCs. Using concentrated colloids dispersed in a volatile medium, the colloidal crystal templates were obtained within a few minutes, and the thickness of the template was easily controlled by changing the quantity of colloidal solution deposited. Here, the effects of the structural properties of the inverse opal TiO(2) electrodes on the photovoltaic parameters of DSSCs were investigated. The photovoltaic parameters were measured as a function of pore ordering and electrode film thickness. Moreover, DSSC applications that used either liquid or viscous polymer electrolyte solutions were investigated to reveal the effects of pore size on performance of an inverse opal TiO(2) electrode.