Selective Lithium Adsorption of Silicon Oxide Coated Lithium Aluminum Layered Double Hydroxide Nanocrystals and Their Regeneration.

Silicon oxide-coated lithium aluminum layered double hydroxide (Lix Al2 -LDH@SiO2 ) nanocrystals (NCs) are investigated to selectively separate lithium cations in aqueous lithium resources. We directly synthesized Lix Al2 -LDH NC arrays by oxidation of aluminum foil substrate under a urea and lithium solution. Various lithium salts, including Cl- , CO3 2- , NO3 - , and SO4 2- , were applied in aqueous solution to confirm the anion effect on the captured and released lithium quantity of the Lix Al2 -LDH NCs. In a 5% solution of sulfate ions mix with lithium chloride, the Lix Al2 -LDH NCs separated a larger quantity of lithium than in other anion conditions. To enhance regeneration stability and lithium selectivity, thin layers of SiO2 were coated onto the Lix Al2 -LDH nanostructure arrays for inhibition of nanostructure destruction after desorption of lithium cations in hot water. The Lix Al2 -LDH@SiO2 nanostructures showed enhanced properties for lithium adsorption, including increase of stable regeneration cycles from three to five cycles, and they showed high lithium selectivity in the Mg2+ , Na+ , and K+ cation mixed aqueous resource. Our nanostructured LDH lithium adsorbents would provide a facile and efficient application for cost-efficient and large-scale lithium production.

Formation and Encapsulation of All-Inorganic Lead Halide Perovskites at Room Temperature in Metal-Organic Frameworks.

Improving the stability and tuning the optical properties of semiconducting perovskites are vital for their applications in advanced optoelectronic devices. We present a facile synthetic method for hybrid composites of perovskites and metal-organic frameworks (MOFs). A simple two-step solution-based method without organic surfactants was employed to make all-inorganic lead-halide perovskites (CsPbX3; X = Cl, Br, I, or mixed halide compositions) form directly in the pores of MIL-101 MOF. That is, a polar organic solution of lead halide (PbX2) was impregnated into the MOF pores to give PbX2@MIL-101, which was then subjected to a perovskite-formation reaction with cesium halide (CsX) dissolved in methanol. The compositions of the halogen anions in the perovskites can be modulated with various halide precursors, leading to CsPbX3@MIL-101 composites with X3 = Cl3, Cl2Br, Br2Cl, Br3, Br2I, I2Br, and I3 that exhibit gradual variation of band gap energies and tuned emission wavelengths from 417 to 698 nm.

Core-Shell Structured Cobalt Sulfide/Cobalt Aluminum Hydroxide Nanosheet Arrays for Pseudocapacitor Application.

The direct synthesis of nanostructured electrode materials on three-dimensional substrates is important for their practical application in electrochemical cells without requiring the use of organic additives or binders. In this study, we present a simple two-step process to synthesize a stable core-shell structured cobalt sulfide/cobalt aluminum hydroxide nanosheet (LDH-S) for pseudocapacitor electrode application. The cobalt aluminum layered double hydroxide (CoAl-LDH) nanoplates were synthesized in basic aqueous solution with a kinetically-controlled thickness. Owing to the facile diffusion of electrolytes through the nanoplates, thin CoAl-LDH nanoplates have higher specific capacitance values than thick nanoplates. The as-grown CoAl-LDH nanoplates were transformed into core-shell structured LDH-S nanosheets by a surface modification process in Na2 S aqueous solution. The chemically robust cobalt sulfide (CoS) shell increased the electrochemical stability compared to the sulfide-free CoAl-LDH electrodes. The LDH-S electrodes exhibited high electrochemical performance in terms of specific capacitance and rate capability with a galvanostatic discharge of 1503 F g-1 at a current density of 2 A g-1 and a specific capacitance of 91 % at 50 A g-1 .

Biomechanical Characteristics of Three Baseplate Rotational Arrangement Techniques in Total Knee Arthroplasty.

INTRODUCTION: Several ongoing studies aim to improve the survival rate following total knee arthroplasty (TKA), which is an effective orthopedic surgical approach for patients with severely painful knee joint diseases. Among the studied strategies, baseplate rotational arrangement techniques for TKA components have been suggested but have been the subject of only simple reliability evaluations. Therefore, this study sought to evaluate comparatively three different baseplate rotational arrangement techniques that are commonly used in a clinical context. MATERIALS AND METHODS: Three-dimensional (3D) finite element (FE) models of the proximal tibia with TKA were developed and analyzed considering three baseplate rotational arrangement techniques (anterior cortex line, tibial tuberosity one-third line, and tibial tuberosity end line) for six activities of daily life (ADLs) among patients undergoing TKA. Mechanical tests based on the ASTM F1800 standard to validate the FE models were then performed using a universal testing machine. To evaluate differences in biomechanical characteristics according to baseplate rotational arrangement technique, the strain and peak von Mises stresses (PVMSs) were assessed. RESULTS: The accuracy of the FE models used in this study was high (94.7 ± 5.6%). For the tibial tuberosity one-third line rotational arrangement technique, strains ≤ 50 µstrain (the critical bone damage strain, which may affect bone remodeling) accounted for approximately 2.2%-11.3% and PVMSs within the bone cement ranged from 19.4 to 29.2 MPa, in ADLs with high loading conditions. For the tibial tuberosity end line rotational arrangement, strains ≤ 50 µstrain accounted for approximately 2.3%-13.3% and PVMSs within the bone cement ranged from 13.5 to 26.7 MPa. For anterior cortex line rotational arrangement techniques, strains ≤50 µstrain accounted for approximately 10.6%-16.6% and PVMSs within the bone cement ranged from 11.6 to 21.7 MPa. CONCLUSION: The results show that the most recently developed frontal cortex line rotational alignment technique is the same or better than the other two rotational alignment techniques in terms of biomechanics. This finding can be, however, dependent on the contact characteristics between the baseplate and the proximal tibia. That is, it is indicated that the optimum baseplate rotational arrangement technique in terms of reducing the incidence of TKA mechanical failure can be achieved by adjusting the characteristics of contact between the baseplate and the proximal tibia.

Air-Stable Transparent Silver Iodide-Copper Iodide Heterojunction Diode.

Transparent AgI-CuI heterojunctions with high rectifying diode behavior were prepared via vapor-phase iodization of metal thin films on transparent conducting oxide substrates. At room temperature, Ag and Cu metal thin films were quickly transformed into the transparent and well-crystallized ß-phase of AgI and the γ-phase of CuI, respectively. The AgI and CuI films exhibited n-type and p-type semiconductor properties, respectively, with wide band gaps. The heterojunctions were obtained by applying the CuI film to the AgI film in a sequential iodization process. AgI compounds generally have poor air-stability under light, making them suboptimal for use in electronic applications. Here, we used a CuI top layer to inhibit the photodecomposition of the AgI bottom layer, resulting in an air-stable and smooth AgI-CuI film. We also propose a simple patterning method for the AgI-CuI layer using selective decomposition of AgI without the need for lithography equipment or toxic chemicals. Although there is metal ion exchange between the two layers, each layer has a different chemical composition and crystal structure; therefore, the AgI-CuI heterojunction exhibits pn-diode behavior with a rectifying ratio of 9.4 × 104, which is comparable to that of other transparent pn-diodes. These findings open a new path for electronic application of AgI materials.

Photoresponse of CsPbBr3 and Cs4PbBr6 Perovskite Single Crystals.

High-quality and millimeter-sized perovskite single crystals of CsPbBr3 and Cs4PbBr6 were prepared in organic solvents and studied for correlation between photocurrent generation and photoluminescence (PL) emission. The CsPbBr3 crystals, which have a 3D perovskite structure, showed a highly sensitive photoresponse and poor PL signal. In contrast, Cs4PbBr6 crystals, which have a 0D perovskite structure, exhibited more than 1 order of magnitude higher PL intensity than CsPbBr3, which generated an ultralow photoresponse under illumination. Their contrasting optoelectrical characteristics were attributed to different exciton binding energies, induced by coordination geometry of the [PbBr6]4- octahedron sublattices. This work correlated the local structures of lead in the primitive perovskite and its derivatives to PL spectra as well as photoconductivity.

A predictive model for estimating regional skeletal muscle size by two-point dixon magnetic resonance imaging in healthy Koreans.

This study was undertaken to develop and cross-validate reference and individual predictive models for estimating functional thigh muscle cross-sectional area (TCSA) by 2-point Dixon magnetic resonance imaging (MRI). TCSAs of dominant sides at the mid-thigh level were measured by 2-point Dixon MRI (MRITCSA). Functional MRITCSA were compared with the predictive models in a sample of 92 younger (20-40 years; 28.55±4.87; n=50) and older (>65years; 71.22±4.82; n=42) Koreans. Lean body masses were measured by dual energy X-ray absorptiometry (DXALBM), and thigh isokinetic muscle strengths, extension peak torque at 60°/sec, were measured using a Biodex® dynamometer (BiodexEPT). Multiple regression analysis generated the reference model (R2=0.75 and SEE=1472.63mm2 (8%)) as follows: The reference model: functional TCSA(mm2)=-1230.49+62.81*height+3061.78*gender -2692.57*age+58.91*weight. The individual model (R2=0.80, SEE=1158.34mm2 (7%)) was as follows: The individual model: functional TCSA(mm2)=1631.62+1.76* DXALBM+9.51*BiodexEPT where height is in centimeters; weight is in kilograms; for gender, female=0 and male=1; and for age, age under 40=1 and age over 65=2. PRESS statistics of R2 and SEE were 0.78 and 1382.98mm2 for the reference model, and 0.88 and 979.02mm2 for the individual model. The 2-point Dixon MRI appears to be valid for measuring functional muscle size. Our results suggest that the reference and individual models provide acceptable estimates of functional thigh muscle CSA in healthy Korean adults. Therefore, the models developed in the study could be useful as a research tool to establish indexes for functional muscle composition in healthy Koreans.

Structural, Electrical, and Optical Properties of ZnO Film Used as Buffer Layer for CIGS Thin-Film Solar Cell.

The CuIn(x)Ga(1-x)Se2 (CIGS) using the solution-based fabrication method is attractive for thin film solar cells because of its possibilities for large-area and low-cost production. ZnO films between transparent conductive oxide (TCO) and the CdS films can improve the performances of CIGS thin-film solar cells. In this study, we investigated the characteristics of ZnO film between TCO and CIGS layers in a solar cell (AZO/ZnO/CdS/CIGS/Mo), which were deposited at various thicknesses to investigate the role of the films in CIGS solar cells. It was confirmed that the conversion efficiency of a CIGS solar cell depends on the ZnO film. For a ZnO film thickness of 80 nm, the highest power conversion efficiency that a solar cell achieved was J(sc) of 18.73 mA/cm2.

Passivated ambipolar black phosphorus transistors.

We report the first air-passivated ambipolar BP transistor formed by applying benzyl viologen, which serves as a surface charge transfer donor for BP flakes. The passivated BP devices exhibit excellent stability under both an ambient atmosphere and vacuum; their transistor performance is maintained semi-permanently. Unlike their intrinsic p-type properties, passivated BP devices present advantageous ambipolar properties with much higher electron mobility up to ∼83 cm(2) V(-1) s(-1) from 2-terminal measurement at 300 K, compared to other reported studies on n-type BP transistors. On the basis of the n-type doping effect that originated from benzyl viologen, we also systematically investigated the BP thickness dependence of our devices on electrical properties, in which we found the best electron transport performance to be attained when an ∼10 nm thick BP flake was used.

Nanostructured cobalt hydroxide thin films as high performance pseudocapacitor electrodes by graphene oxide wrapping.

We synthesized binder-free Co(OH)2 nanocrystals on nickel electrodes by the ammonia transfer method in an aqueous solution and kinetically-controlled their thickness and height to enhance the capacitance through the facile diffusion of electrolytes in the nanocrystals. As thinner Co(OH)2 films were developed, the specific capacitance increased up to 1260 F g(-1) at a current density of 10 A g(-1). A thin layer of graphene oxide (GO) was used to wrap the Co(OH)2 nanocrystals to create a pseudocapacitor with high specific capacitance and good cyclic stability. This synthetic strategy enabled us to maximize the electrochemical cell performance, reaching a specific capacitance of 2710 F g(-1) under 10 A g(-1). The GO coating provides an effective method to increase adhesion on the nickel electrodes and to reduce the decomposition of Co(OH)2 during the charge-discharge process under high pH conditions. The prepared GO/Co(OH)2 nanocomposite layers provided not only high electron mobility but also ionic conductivity, especially when operated at a high current density.

Use of the Microsoft Kinect system to characterize balance ability during balance training.

The risk of falling increases significantly in the elderly because of deterioration of the neural musculature regulatory mechanisms. Several studies have investigated methods of preventing falling using real-time systems to evaluate balance; however, it is difficult to monitor the results of such characterizations in real time. Herein, we describe the use of Microsoft's Kinect depth sensor system to evaluate balance in real time. Six healthy male adults (25.5±1.8 years, 173.9±6.4 cm, 71.4±6.5 kg, and 23.6±2.4 kg/m(2)), with normal balance abilities and with no musculoskeletal disorders, were selected to participate in the experiment. Movements of the participants were induced by controlling the base plane of the balance training equipment in various directions. The dynamic motion of the subjects was measured using two Kinect depth sensor systems and a three-dimensional motion capture system with eight infrared cameras. The two systems yielded similar results for changes in the center of body mass (P>0.05) with a large Pearson's correlation coefficient of γ>0.60. The results for the two systems showed similarity in the mean lower-limb joint angle with flexion-extension movements, and these values were highly correlated (hip joint: within approximately 4.6°; knee joint: within approximately 8.4°) (0.40<γ<0.74) (P>0.05). Large differences with a low correlation were, however, observed for the lower-limb joint angle in relation to abduction-adduction and internal-external rotation motion (γ<0.40) (P<0.05). These findings show that clinical and dynamic accuracy can be achieved using the Kinect system in balance training by measuring changes in the center of body mass and flexion-extension movements of the lower limbs, but not abduction-adduction and internal-external rotation.

Synthesis and Nanostructures of Metal Selenide Precursors for Cu(In,Ga)Se2 Thin-Film Solar Cells.

A nanoink solution-based process was developed as a low-costing method for the fabrication of Cu(In,Ga)Se2 (CIGSe) thin-film photovoltaic cells. The sonochemical synthesis of CIGSe nanocrystals of the nanoink through step-by-step mixing of the reactants was investigated. To achieve the ideal stoichiometry of Cu(In0.7 Ga0.3 )Se2 to tune the bandgap and to fabricate high-efficiency photovoltaic cells, the synthetic parameters, the concentration of hydrazine, and the amount used of the gallium precursor were investigated. As the hydrazine concentration increased, gallium loss was observed in the CIGSe product. The gallium content in the reactant mixture strongly affected the metal stoichiometry of the prepared CIGSe nanocrystals. The nanoink solution based fabrication of thin-film photovoltaic cells was also explored, and the resulting device showed a conversion efficiency of 5.17 %.

Fluorescein dye intercalated layered double hydroxides for chemically stabilized photoluminescent indicators on inorganic surfaces.

A new photoactive thin film of layered double hydroxide (LDH) nanocrystals containing fluorescein dyes (LDH-F) has been developed by self-assembly of the LDH nanocrystals and well-controlled intercalation of the dyes in organic media. XRD results and absorption spectra confirmed the highly oriented interlayer arrangement of the dianionic form of the fluorescein dyes in the LDH interlayers, in which the dye molecules were electrostatically immobilized between the positively charged LDH layers with a monolayer packing structure. An intensity weighted average PL lifetime was estimated to be 1.45 ns and fluorescence lifetime imaging microscopy revealed that the individual LDH nanocrystals on the LDH-F film had largely similar lifetimes, which were ascribed to the uniform loading of fluorescein dyes onto the LDH matrix without photoluminescence quenching.

A new mussel-inspired polydopamine phototransistor with high photosensitivity: signal amplification and light-controlled switching properties.

A polydopamine (PDA) thin film with a dense and conformal surface was prepared under optimized deposition conditions using O2 gas as an oxygen source. The PDA-based organic phototransistors exhibited high photosensitivity and photo-controlled switching properties under light illumination.

CuGaS2 hollow spheres from Ga-CuS core-shell nanoparticles.

A liquid gallium emulsion was prepared as a starting material using ultrasound treatment in ethylene glycol. Core-shell particles of Ga@CuS were successfully synthesized by deposition of a CuS layer on gallium droplets through sonochemical deposition of copper ions and thiourea in an alcohol media. The core and shell of Ga@CuS products were composed of amorphous gallium metal and covellite phase CuS, which transformed into chalcopyrite CuGaS2 hollow spheres after sulfurization at 450°C, which was the lowest crystallization temperature. The formation of hollow nanostructures was ascribed to the Kirkendall mechanism, in which liquid gallium particles play an important role as reactive templates. In conclusion, we obtained CuGaS2 hollow spheres with a 430 nm outer diameter and 120 nm shell thickness that had the same crystal structure and electrical properties as bulk CuGaS2.

Locking plate in proximal tibial fracture: a correlation between the coronal alignment of tibia and joint screw angle.

PURPOSE: The purpose of this study is to evaluate the relationship between the angle formed between the proximal most screw through the locking compression plate-proximal lateral tibia (LCP PLT) and the joint line, and to evaluate if this angle can be used intraoperatively as an assessment tool to determine normal alignment of the tibia in the coronal plane. MATERIALS AND METHODS: There are two parts to this study: in the first part, LCP PLT was applied to 30 cadaveric adult tibia. The angle between the joint line and the proximal most screw was measured and termed as the 'joint screw angle' (JSA). In the second part, 56 proximal tibial fractures treated with LCP PLT were retrospectively studied. Two angles were measured on the radiographs, the medial proximal tibial angle (MPTA) and the JSA. Their relationship was analyzed statistically. RESULTS: The average JSA was 1.16 degrees in the anatomical study. Statistical analysis of the clinical study showed that the normal MPTA had a direct correlation with an acceptable JSA. CONCLUSION: We therefore conclude that the JSA can be used intraoperatively to assess the achievement of a normal coronal axis.

A new mussel-inspired polydopamine sensitizer for dye-sensitized solar cells: controlled synthesis and charge transfer.

The efficient electron injection by direct dye-to-TiO(2) charge transfer and strong adhesion of mussel-inspired synthetic polydopamine (PDA) dyes with TiO(2) electrode is demonstrated. Spontaneous self-polymerization of dopamine using dip-coating (DC) and cyclic voltammetry (CV) in basic buffer solution were applied to TiO(2) layers under a nitrogen atmosphere, which offers a facile and reliable synthetic pathway to make the PDA dyes, PDA-DC and PDA-CV, with conformal surface and perform an efficient dye-to-TiO(2) charge transfer. Both synthetic methods led to excellent photovoltaic results and the PDA-DC dye exhibited larger current density and efficiency values than those in the PDA-CV dye. Under simulated AM 1.5 G solar light (100 mW cm(-2)), a PDA-DC dye exhibited a short circuit current density of 5.50 mW cm(-2), corresponding to an overall power conversion efficiency of 1.2 %, which is almost 10 times that of the dopamine dye-sensitized solar cell. The PDA dyes showed strong adhesion with the nanocrystalline TiO(2) electrodes and the interface engineering of a dye-adsorbed TiO(2) surface through the control of the coating methods, reaction times and solution concentration maximized the overall conversion efficiency, resulting in a remarkably high efficiency.

Highly oriented nanoplates of layered double hydroxides as an ultra slow release system.

A novel controlled molecular release based on highly oriented nanoplates of layered double hydroxide was fabricated on indium tin oxide substrates by electrophoretic deposition of exfoliated LDH nanosheets. The LDH particle coating exhibited a superior release performance of the order of hours.