Strategy to Achieve a Pure Red/Green/Blue-Emitting Upconversion Luminescence for Full-Color Displays.

Multicolor tunable upconversion nanoparticles (UCNPs) have garnered attention owing to their diverse applications such as displays, imaging, and security. Typically, achieving multicolor emission from UCNPs requires complicated core/multishell nanostructures comprising a core with at least five shells. Here, we propose a strategy to achieve bright and orthogonal red (R), green (G), and blue (B) upconversion (UC) luminescence without synthesizing complicated core/quintuple-shell or core/sextuple-shell nanostructures. For achieving bright and orthogonal RGB triprimary color UC luminescence, orthogonal bicolor-emitting core/shell-structured UCNPs are synthesized and blended. Orthogonal RB, RG, and GB luminescence are achieved through photon blocking. The combination of two orthogonal bicolor-emitting UCNPs exhibits pure RGB UC luminescence and full-color tunability via manipulation of excitation laser conditions. Furthermore, we present color displays achieved with transparent UCNP-polymer composites utilizing three distinct near-infrared light wavelengths, implying that the proposed strategy for attaining RGB UC luminescence may facilitate advancements in the development of full-color volumetric displays.

Photonic control of ligand nanospacing in self-assembly regulates stem cell fate.

Extracellular matrix (ECM) undergoes dynamic inflation that dynamically changes ligand nanospacing but has not been explored. Here we utilize ECM-mimicking photocontrolled supramolecular ligand-tunable Azo+ self-assembly composed of azobenzene derivatives (Azo+) stacked via cation-π interactions and stabilized with RGD ligand-bearing poly(acrylic acid). Near-infrared-upconverted-ultraviolet light induces cis-Azo+-mediated inflation that suppresses cation-π interactions, thereby inflating liganded self-assembly. This inflation increases nanospacing of "closely nanospaced" ligands from 1.8 nm to 2.6 nm and the surface area of liganded self-assembly that facilitate stem cell adhesion, mechanosensing, and differentiation both in vitro and in vivo, including the release of loaded molecules by destabilizing water bridges and hydrogen bonds between the Azo+ molecules and loaded molecules. Conversely, visible light induces trans-Azo+ formation that facilitates cation-π interactions, thereby deflating self-assembly with "closely nanospaced" ligands that inhibits stem cell adhesion, mechanosensing, and differentiation. In stark contrast, when ligand nanospacing increases from 8.7 nm to 12.2 nm via the inflation of self-assembly, the surface area of "distantly nanospaced" ligands increases, thereby suppressing stem cell adhesion, mechanosensing, and differentiation. Long-term in vivo stability of self-assembly via real-time tracking and upconversion are verified. This tuning of ligand nanospacing can unravel dynamic ligand-cell interactions for stem cell-regulated tissue regeneration.

Defect Engineering of Metal Halide Perovskite Nanocrystals via Spontaneous Diffusion of Ag Nanocrystals.

Perovskite nanocrystals (NCs) have emerged as a promising building block for the fabrication of optic-/optoelectronic-/electronic devices owing to their superior characteristics, such as high absorption coefficient, rapid ion mobilities, and tunable energy levels. However, their low structural stability and poor surface passivation have restricted their application to next-generation devices. Herein, a drug delivery system (DDS)-inspired post-treatment strategy is reported for improving their structural stability by doping of Ag into CsPbBr3 (CPB) perovskite NCs; delivery to damaged sites can promote their structural recovery slowly and uniformly, averting the permanent loss of their intrinsic characteristics. Ag NCs are designed through surface-chemistry tuning and structural engineering to enable their circulation in CPB NC dispersions, followed by their delivery to the CPB NC surface, defect-site recovery, and defect prevention. The perovskite-structure healing process through the DDS-type process (with Ag NCs as the drug) is analyzed by a combination of theoretical calculations (with density functional theory) and experimental analyses. The proposed DDS-inspired healing strategy significantly enhances the optical properties and stability of perovskite NCs, enabling the fabrication of white light-emitting diodes.

Metatarsal sliding osteotomy is effective without altering plantar pressure in Morton's neuroma: Retrospective case series.

BACKGROUND: Various operative methods for the treatment of Morton's neuroma have been discussed, and osteotomy of the metatarsal bone has been reported recently. However, there has been no report of pedobarographic changes after metatarsal osteotomy. Pedobarographic changes of other metatarsal area after the surgery may cause transfer metatarsalgia, and thorough analysis of the pedobarographic data should be performed peri-operatively. The purpose of this study is to investigate the post-operative pedobarographic changes of sliding osteotomy of the 3rd metatarsal bone for treating Morton's neuroma. METHODS: Forty patients (45 feet) who underwent metatarsal sliding osteotomy of the 3rd metatarsal bone for treating Morton's neuroma from November 2013 to December 2021 were retrospectively reviewed. Proximal sliding osteotomy was performed at the proximal 3rd metatarsal bone through dorsal approach. Clinical outcomes were evaluated with American Orthopaedic Foot and Ankle Society Lesser Metatarsophalangeal Interphalangeal Scale (AOFAS LMIS), Foot Function Index (FFI), and Visual Analogue Scale (VAS). Plain radiograph and pedobarogram were performed to evaluate the radiologic and pedobarographic outcomes. RESULTS: AOFAS score was improved from 52.8 ± 9.0 (18-62) to 88.8 ± 9.8 (78-100) and FFI was improved from 61.8 ± 4.9 (50-70) to 32.2 ± 5.1 (23-42) on average. The 3rd metatarsal bone was shortened by 3.1 ± 0.8 mm and dorsally shifted by 1.5 ± 0.4 mm after the surgery. Plantar intermetatarsal distances between 2nd and 3rd and 3rd and 4th metatarsal heads were significantly increased post-operatively. Average forefoot pressure and maximum pressure of the 2nd to 4th metatarsal head were not significantly changed between pre-operatively and post-operatively. CONCLUSION: Proximal metatarsal sliding osteotomy of the 3rd metatarsal bone shows a satisfactory result in both clinical and pedobarographical evaluations. It could be an effective treatment of permanent indirect decompression of Morton's neuroma with avoiding recurred neuroma, adhesion of tissue, paresthesia, and transfer metatarsalgia.

Intense Near-Infrared Light-Emitting NaYF4:Nd,Yb-Based Nanophosphors for Luminescent Solar Concentrators.

In this study, we synthesized NaYF4-based downshifting nanophosphors (DSNPs), and fabricated DSNP-polydimethylsiloxane (PDMS) composites. Nd3+ ions were doped into the core and shell to increase absorbance at 800 nm. Yb3+ ions were co-doped into the core to achieve intense near-infrared (NIR) luminescence. To further enhance the NIR luminescence, NaYF4:Nd,Yb/NaYF4:Nd/NaYF4 core/shell/shell (C/S/S) DSNPs were synthesized. The C/S/S DSNPs showed a 3.0-fold enhanced NIR emission at 978 nm compared with core DSNPs under 800 nm NIR light. The synthesized C/S/S DSNPs showed high thermal stability and photostability against the irradiation with ultraviolet light and NIR light. Moreover, for application as luminescent solar concentrators (LSCs), C/S/S DSNPs were incorporated into the PDMS polymer, and the DSNP-PDMS composite containing 0.25 wt% of C/S/S DSNP was fabricated. The DSNP-PDMS composite showed high transparency (average transmittance = 79.4% for the visible spectral range of 380-750 nm). This result demonstrates the applicability of the DSNP-PDMS composite in transparent photovoltaic modules.

Elemental-Migration-Assisted Full-Color-Tunable Upconversion Nanoparticles for Video-Rate Three-Dimensional Volumetric Displays.

Herein, we demonstrate video-rate color three-dimensional (3D) volumetric displays using elemental-migration-assisted full-color-tunable upconversion nanoparticles (UCNPs). In the heavily doped NaErF4:Tm-based core@multishell UCNPs, erbium migration was observed. By tailoring this migration through adjustment of the intermediate shell thickness between the core and the sensitizer-doped second shell, red-green orthogonal upconversion luminescence (UCL) was achieved. Furthermore, highly efficient red-green-blue orthogonal UCL and full-color tunability were achieved in the UCNPs through a combination of elemental-migration-assisted color tuning and selective photon blocking. Finally, 3D volumetric displays were fabricated using a UCNP-polydimethylsiloxane composite. More specifically, 3D color images were created and motion pictures based on the expansion, rotation, and up/down movement of the displayed images were realized in the display matrix. Overall, our study provides new insights into upconversion color tuning and the achievement of motion pictures in the UCNP-polydimethylsiloxane composite is expected to accelerate the further development of solid-state full-color 3D volumetric displays.

Performance Enhancement in Powder-Fabricated Cu2(ZnSn)Se4 Solar Cell by Roll Compression.

Despite the improved conversion efficiency of Cu2(ZnSn)Se4 (CZTSe) solar cells, their roll-to-roll fabrication nonetheless leads to low performance. The selenization time and temperature are typically considered major parameters for a powder-based CZTSe film; meanwhile, the importance of the densification during the roll-to-roll process is often overlooked. The densification process is related to the porosity of the light-absorbing layer, where high porosity lowers cell performance. In this study, we fabricated a dense CZTSe absorber layer as a method of controlling the compression of a powder precursor (Cu1.7(Zn1.2Sn1.0)S4.0 (CZTS)) during the roll-press process. The increased particle packing density of the CZTS layer was crucial in sintering the powder layer into a dense film and preventing severe selenization of the Mo back electrode. The pressed absorber layer of the CZTSe solar cell exhibited a more uniform chemical composition determined using dynamic secondary ion mass spectrometry (SIMS). Under the AM 1.5G illumination condition, the power conversion efficiency of the pressed solar cell was 6.82%, while the unpressed one was 4.90%.

Environmentally friendly, highly efficient, and large stokes shift-emitting ZnSe:Mn2+/ZnS core/shell quantum dots for luminescent solar concentrators.

In this study, heavy-metal-free orange light-emitting ZnSe:Mn2+/ZnS doped-core/shell (d-C/S) quantum dots (QDs) were synthesized using a nucleation doping strategy. To synthesize high quality d-C/S QDs with high photoluminescence (PL) quantum yield (QY), the Mn2+ concentration was optimized. The resulting ZnSe:Mn2+(5%)/ZnS d-C/S QDs showed a high PL QY of 83.3%. The optical properties of the synthesized QDs were characterized by absorption and PL spectroscopy. Their structural and compositional properties were studied by X-ray diffraction, transmission electron microscopy, and energy dispersive X-ray spectroscopy. After doping Mn2+ into a ZnSe core, the ZnSe:Mn2+/ZnS d-C/S QDs showed a large Stokes shift of 170 nm. The ZnSe:Mn2+/ZnS d-C/S QDs were embedded in a poly(lauryl methacrylate) (PLMA) polymer matrix and the ZnSe:Mn2+/ZnS-based polymer film was fabricated. The fabricated ZnSe:Mn2+/ZnS-PLMA film was highly transparent in the visible spectral region (transmittance > 83.8% for λ ≥ 450 nm) and it exhibited bright orange light under air mass (AM) 1.5G illumination using a solar simulator. The optical path-dependent PL measurement of the ZnSe:Mn2+/ZnS-PLMA film showed no PL band shift and minimal PL decrease under variation of excitation position. These results indicate that the highly efficient and large Stokes shift-emitting ZnSe:Mn2+/ZnS QDs are promising for application to luminescent solar concentrators.

Photoswitchable Microgels for Dynamic Macrophage Modulation.

Dynamic manipulation of supramolecular self-assembled structures is achieved irreversibly or under non-physiological conditions, thereby limiting their biomedical, environmental, and catalysis applicability. In this study, microgels composed of azobenzene derivatives stacked via π-cation and π-π interactions are developed that are electrostatically stabilized with Arg-Gly-Asp (RGD)-bearing anionic polymers. Lateral swelling of RGD-bearing microgels occurs via cis-azobenzene formation mediated by near-infrared-light-upconverted ultraviolet light, which disrupts intermolecular interactions on the visible-light-absorbing upconversion-nanoparticle-coated materials. Real-time imaging and molecular dynamics simulations demonstrate the deswelling of RGD-bearing microgels via visible-light-mediated trans-azobenzene formation. Near-infrared light can induce in situ swelling of RGD-bearing microgels to increase RGD availability and trigger release of loaded interleukin-4, which facilitates the adhesion structure assembly linked with pro-regenerative polarization of host macrophages. In contrast, visible light can induce deswelling of RGD-bearing microgels to decrease RGD availability that suppresses macrophage adhesion that yields pro-inflammatory polarization. These microgels exhibit high stability and non-toxicity. Versatile use of ligands and protein delivery can offer cytocompatible and photoswitchable manipulability of diverse host cells.

Iatrogenic second transfer metatarsalgia and the first metatarsal shortening and elevation after Scarf osteotomy.

BACKGROUND: Transfer metatarsalgia is a potential complication of hallux valgus surgery. This study aimed to investigate the shortened first metatarsal length and elevation and to compare groups with and without second transfer metatarsalgia after Scarf osteotomy. METHODS: The first metatarsal length of 123 feet was measured via the Maestro's method using the metatarsal axial length and the relative second metatarsal protrusion to the first metatarsal. Metatarsal elevation was measured using the first metatarsal angle. RESULTS: Second transfer metatarsalgia occurred after Scarf osteotomy in 11 (8.9%) feet. When baseline characteristics were considered in propensity score matching, the 11 feet were compared with the 33 feet in the control group. The group with transfer metatarsalgia showed a more shortened first metatarsal axial length (-4.1 ± 1.8 mm vs. -2.5 ± 2.2 mm, p = 0.032), a significantly longer relative second metatarsal protrusion (+5.8 ± 2.6 mm vs. +1.2 ± 2.6 mm, p < 0.001), and a significantly lower first metatarsal angle (18.1 ± 4.3° vs. 21.5 ± 4.0°, p = 0.012) than the control group postoperatively. CONCLUSIONS: To avoid iatrogenic transfer metatarsalgia, first metatarsal length shortening should be minimized to at least less than 4.0 mm. Furthermore, the metatarsal parabola should be retained.

A Super-Boosted Hybrid Plasmonic Upconversion Process for Photodetection at 1550 nm Wavelength.

A super-boosted hybrid plasmonic upconversion (UC) architecture comprising a hierarchical plasmonic upconversion (HPU) film and a polymeric microlens array (MLA) film is proposed for efficient photodetection at a wavelength of 1550 nm. Plasmonic metasurfaces and Au core-satellite nanoassembly (CSNA) films can strongly induce a more effective plasmonic effect by providing numerous hot spots in an intense local electromagnetic field up to wavelengths exceeding 1550 nm. Hence, significant UC emission enhancement is realized via the amplified plasmonic coupling of an HPU film comprising an Au CSNA and UC nanoparticles. Furthermore, an MLA polymer film is synergistically coupled with the HPU film, thereby focusing the incident near-infrared light in the micrometer region, including the plasmonic nanostructure area. Consequently, the plasmonic effect super-boosted by microfocusing the incident light, significantly lowers the detectable power limit of a device, resulting in superior sensitivity and responsivity at weak excitation powers. Finally, a triple-cation perovskite-based photodetector coupled with the hybrid plasmonic UC film exhibits the excellent values of responsivity and detectivity of 9.80 A W-1 and 8.22 × 1012 Jones at a weak power density of ≈0.03 mW cm-2 , respectively, demonstrating that the device performance is enhanced by more than 104 magnitudes over a reference sample.

Orthogonal R/G/B Upconversion Luminescence-based Full-Color Tunable Upconversion Nanophosphors for Transparent Displays.

Here, excitation orthogonalized red/green/blue upconversion luminescence (UCL)-based full-color tunable rare-earth (RE) ion-doped upconversion nanophosphors (UCNPs) are reported. The LiREF4-based core/sextuple-shell (C/6S) UCNPs are synthesized, and they consist of a blue-emitting core, green-emitting inner shell, and red-emitting outer shell, with inert intermediate and outermost shells. The synthesized C/6S UCNPs emit blue, green, and red light under 980, 800, and 1532 nm, respectively. Importantly, by combining incident near-infrared (NIR) light with various wavelengths (800, 980, and 1532 nm), full-color UCL including blue, cyan, green, yellow, orange, red, purple, and white UCL is achieved from the single C/6S UCNP composition. The color gamut obtained from the C/6S UCNPs shows 101.6% of the sRGB standard color gamut. Furthermore, transparent C/6S UCNP-polydimethylsiloxane (PDMS) composite is prepared. Full-color display realized in the transparent C/6S UCNP-PDMS composite indicates the feasibility of constructing the C/6S UCNP-based three-dimensional volumetric displays with wide color gamut.

Bright Blue, Green, and Red Luminescence from Dye-Sensitized Core@Shell Upconversion Nanophosphors under 800 nm Near-Infrared Light.

In this study, Li-based blue- and green-emitting core@shell (C@S) upconversion nanophosphors (UCNPs) and NaGdF4-based red-emitting C@S UCNPs were synthesized, and IR-808 dyes were conjugated with the C@S UCNPs to enhance upconversion (UC) luminescence. The surface of the as-synthesized C@S UCNPs, which was originally capped with oleic acid, was modified with BF4- to conjugate the IR-808 dye having a carboxyl functional group to the surface of the UCNPs. After the conjugation with IR-808 dyes, absorbance of the UCNPs was significantly increased. As a result, dye-sensitized blue (B)-, green (G)-, and red (R)-emitting UCNPs exhibited 87-fold, 10.8-fold, and 110-fold enhanced UC luminescence compared with B-, G-, and R-emitting Nd3+-doped C@S UCNPs under 800 nm near-infrared (NIR) light excitation, respectively. Consequently, dye-sensitized UCNPs exhibiting strong UC luminescence under 800 nm NIR light excitation have high applicability in a variety of biological applications.

Facile synthesis of sub-10 nm-sized bright red-emitting upconversion nanophosphors via tetrahedral YOF:Yb,Er seed-mediated growth.

Ultrasmall and uniform tetrahedral-shaped YOF:Yb,Er upconversion nanophosphors (UCNs) are synthesized and sub-10 nm YOF:Yb,Er/YOF core/shell UCNs are formed via YOF:Yb,Er seed-mediated synthesis. The ultrasmall YOF:Yb,Er/YOF core/shell UCNs realize intense red emission under near infrared light (λex = 980 nm).

Intense upconversion red emission from Gd-doped NaErF4:Tm-based core/shell/shell nanocrystals under 980 and 800 nm near infrared light excitations.

Bright and single band red-emitting NaErF4:Tm,Gd-based upconversion nanophosphors (UCNPs) were successfully synthesized by the formation of a core/intermediate shell/active shell structure. The NaErF4:Tm,Gd/NaYF4:Ca,Yb/NaYF4:Nd,Yb core/shell/shell UCNPs exhibit intense red light under both 980 and 800 nm near infrared light excitations.

Intense Red-Emitting Upconversion Nanophosphors (800 nm-Driven) with a Core/Double-Shell Structure for Dual-Modal Upconversion Luminescence and Magnetic Resonance in Vivo Imaging Applications.

In this study, intense single-band red-emitting upconversion nanophosphors (UCNPs) excited with 800 nm near-infrared (NIR) light are reported. When a NaYF4:Nd,Yb active-shell is formed on the 12.7 nm sized NaGdF4:Yb,Ho,Ce UCNP core, the core/shell (C/S) UCNPs show tunable emission from green to red, depending on the Ce3+ concentration under excitation with 800 nm NIR light. Ce3+-doped C/S UCNPs (30 mol %) exhibit single-band red emission peaking at 644 nm via a 5F5 → 5I8 transition of Ho3+. A high Nd3+ concentration in the shell results in strong absorption at around 800 nm NIR light, even though the shell thickness is not large, and small-sized C/S UCNPs (16.3 nm) emit bright red light under 800 nm excitation. The formation of a thin NaGdF4 shell on the C/S UCNPs further enhances the upconversion (UC) luminescence and sub-20 nm sized core/double-shell (C/D-S) UCNPs exhibit 2.8 times stronger UC luminescence compared with C/S UCNPs. Owing to the strong UC luminescence intensity and Gd3+ ions on the surface of nanocrystals, they can be applied as a UC luminescence imaging agent and a T1 contrast agent for magnetic resonance (MR) imaging. In vivo UC luminescence and high-contrast MR images are successfully obtained by utilizing the red-emitting C/D-S UCNPs.

Comparison of outcomes of osteosynthesis in type II accessory navicular by variable fixation methods.

BACKGROUND: To compare the outcomes of fixation methods for osteosynthesis of a type II symptomatic accessory navicular between screw and tension band wiring. METHODS: Forty-four patients (mean age, 29.2 years; range, 13-54 years; 21 males and 23 females) who had undergone operative treatment after failed conservative treatment were chosen for the study between 2007 and 2014. The patients were divided into two groups by the method of osteosynthesis: group 1 (screw) and group 2 (tension band wiring). Pre and postoperative evaluations were performed, using the midfoot scale from the American Orthopaedic Foot and Ankle Society (AOFAS), a visual analog scale, time to return to social activities, and plain radiography. RESULTS: The AOFAS midfoot and visual analog scale scores of both groups were improved at the last postoperative follow-up. The time to return to social activities was 12.3 weeks in the screw group and 11.9 weeks in the tension band wiring group (p=0.394). A broken screw was observed in one case in the screw group and a broken k-wire was detected in two cases in the tension band wiring group. Nonunion was observed in two cases in each group. CONCLUSION: The tension band wiring technique could be another treatment choice of osteosynthesis for fixation of the accessory navicular bone. LEVEL OF EVIDENCE: Level III, Retrospective Case Control Study.

Controlled Synthesis of CuInS2/ZnS Nanocubes and Their Sensitive Photoluminescence Response toward Hydrogen Peroxide.

We synthesized uniform CuInS2/ZnS nanocubes by adjusting reaction parameters at the ZnS growth stage. Higher temperature and zinc concentration were shown to drive resultant crystals to have cubic morphology, which could be ascribed to the facet-dependent ligand dynamics on the crystal surface and concomitantly preferred directions of crystal growth. It was found that these nanocubes exhibit sensitive responses, as of photoluminescence quenching, toward hydrogen peroxide, compared to pyramid-shaped nanocrystals. The origin of quenching was further analyzed to be the oxidation of thiolate ligands that leaves the quenching center on the surface. It was noted that the quenched photoluminescence could be fully recovered by introducing additional ligand molecules into the system. Being adopted in the shape-controlled crystal growth, the ligand-to-crystal interaction was shown to still govern the interfacial reaction, the oxidation by hydrogen peroxide, of faceted crystals in our system. It turns out that the reactivity at the crystal surface depends on the exposed facets, especially induced by shape control, and the weak ligand-binding nature of the nanocube renders it vulnerable to the surface reaction.

Solution-Processed CuInS2-Based White QD-LEDs with Mixed Active Layer Architecture.

Colloidal quantum dots (QDs) are attractive candidates for future lighting technology. However, in contrast to display applications, the realization of balanced white lighting devices remains conceptually challenging. Here, we demonstrate two-component white light-emitting QD-LEDs with high color rendering indices (CRI) up to 78. The implementation of orange CuInS2/ZnS (CIS/ZnS) QDs with a broad emission and high quantum yield together with blue ZnCdSe/ZnS QDs in a mixed approach allowed white light emission with low blue QD content. The devices reveal only a small color drift in a wide operation voltage range. The correlated color temperature (CCT) could be adjusted between 2200 and 7200 K (from warm white to cold white) by changing the volume ratio between orange and blue QDs (1:0.5 and 1:2).