Polarized emission of Cs3Cu2I5 nanowires embedded in nanopores of an anodic aluminum oxide template.

Due to the intrinsic polarized emission property, polarized emissive materials with anisotropic nanostructures are expected to be potential substitutes for polarizers. Herein, by the template-assisted strategy, well-aligned lead-free metal halide Cs3Cu2I5 nanowire (NW) arrays are fabricated by evaporating the precursor ink in the anodic aluminum oxide (AAO) for polarized emission. The Cs3Cu2I5/AAO composite film emits highly polarized light with a degree of polarization (DOP) of 0.50. Furthermore, by changing the molar ratio of CsI/CuI, the stability of Cs3Cu2I5 precursor inks is improved. Finally, an ultraviolet (UV) light-emitting diode (LED) is adopted to pump the composite film to achieve a blue LED device. The reported Cs3Cu2I5/AAO composite film with highly polarized light emissions will have great potential for polarized emission applications such as liquid crystal display backlights, waveguides, and lasers.

Defective core-shell NiCo2S4/MnO2 nanocomposites for high performance solid-state hybrid supercapacitors.

The roles of oxygen vacancies to enhance the electrochemical performance were not clearly explained in comprehensive research. Herein, the vertically oriented NiCo2S4/MnO2 core-shell nanocomposites are in situ grown on the nickel foam (NF) surface and activated by oxygen vacancy engineering via a chemical reduction method. The scanning electron microscope (SEM) and transmission electron microscope (TEM) results show the shell-MnO2 is well coated on the core-NiCo2S4. The hierarchical core-shell nanostructures synergistically increase conductivity and provide rich faradaic redox chemical reactions. Moreover, the density functional theory (DFT) calculations further indicate that the electronic properties and structure properties in NiCo2S4/MnO2 electrode of reduction for 60 min (NiCo2S4/MnO2-60) are effectively adjusted by introducing oxygen vacancies. Impressively, the NiCo2S4/MnO2-60 electrode delivers substantially appreciable areal capacity of 2.13 mAh·cm-2 couple with superior rate capability. The as-prepared high-performance electrode material can assemble into solid-state hybrid supercapacitor. The fabricated NiCo2S4/MnO2-60//AC device exhibits an exceptional energy density of 43.16 Wh·kg-1 at a power density of 384.21 W·kg-1 and satisfactory cyclic stability of 92.1 % at current density of 10 mA·cm-2 after 10,000 cycles. In general, the work demonstrates the significance of NiCo2S4/MnO2-60 as a highly redox active electrode material for future practical application in supercapacitors.

Open-Spaced Ridged Hydrogel Scaffolds Containing TiO2-Self-Assembled Monolayer of Phosphonates Promote Regeneration and Recovery Following Spinal Cord Injury.

The spinal cord has a poor ability to regenerate after an injury, which may be due to cell loss, cyst formation, inflammation, and scarring. A promising approach to treating a spinal cord injury (SCI) is the use of biomaterials. We have developed a novel hydrogel scaffold fabricated from oligo(poly(ethylene glycol) fumarate) (OPF) as a 0.08 mm thick sheet containing polymer ridges and a cell-attractive surface on the other side. When the cells are cultured on OPF via chemical patterning, the cells attach, align, and deposit ECM along the direction of the pattern. Animals implanted with the rolled scaffold sheets had greater hindlimb recovery compared to that of the multichannel scaffold control, which is likely due to the greater number of axons growing across it. The immune cell number (microglia or hemopoietic cells: 50-120 cells/mm2 in all conditions), scarring (5-10% in all conditions), and ECM deposits (Laminin or Fibronectin: approximately 10-20% in all conditions) were equal in all conditions. Overall, the results suggest that the scaffold sheets promote axon outgrowth that can be guided across the scaffold, thereby promoting hindlimb recovery. This study provides a hydrogel scaffold construct that can be used in vitro for cell characterization or in vivo for future neuroprosthetics, devices, or cell and ECM delivery.

Dynamic change in Siglec-15 expression in peritumoral macrophages confers an immunosuppressive microenvironment and poor outcome in glioma.

Background: Sialic acid-binding immunoglobulin-like lectin-15 (Siglec-15) was reported to be a novel immune checkpoint molecule comparable to programmed cell death 1 ligand 1 (PD-L1). However, its expression profile and immunosuppressive mechanisms in the glioma tumor microenvironment have not yet been fully explored. Objectives: To identify the expression profile and potential function of Siglec-15 in glioma tumor microenvironment. Methods: We investigated Siglec-15 and PD-L1 expression in tumor tissues from 60 human glioma patients and GL261 tumor models. Next, Siglec-15 knockout macrophages and mice were used to elucidate the immunosuppressive mechanism of Siglec-15 impacting macrophage function. Results: Our results demonstrated that high levels of Siglec-15 in tumor tissues was positively correlated with poor survival in glioma patients. Siglec-15 was predominantly expressed on peritumoral CD68+ tumor-associated macrophages, which accumulated to the highest level in grade II glioma and then declined as grade increased. The Siglec-15 expression pattern was mutually exclusive with that of PD-L1 in glioma tissues, and the number of Siglec-15+PD-L1- samples (n = 45) was greater than the number of Siglec-15-PD-L1+ samples (n = 4). The dynamic change in and tissue localization of Siglec-15 expression were confirmed in GL261 tumor models. Importantly, after Siglec15 gene knockout, macrophages exhibited enhanced capacities for phagocytosis, antigen cross-presentation and initiation of antigen-specific CD8+ T-lymphocyte responses. Conclusion: Our findings suggested that Siglec-15 could be a valuable prognostic factor and potential target for glioma patients. In addition, our data first identified dynamic changes in Siglec-15 expression and distribution in human glioma tissues, indicating that the timing of Siglec-15 blockade is critical to achieve an effective combination with other immune checkpoint inhibitors in clinical practice.

The Translesional Spinal Network and Its Reorganization after Spinal Cord Injury.

Evidence from preclinical and clinical research suggest that neuromodulation technologies can facilitate the sublesional spinal networks, isolated from supraspinal commands after spinal cord injury (SCI), by reestablishing the levels of excitability and enabling descending motor signals via residual connections. Herein, we evaluate available evidence that sublesional and supralesional spinal circuits could form a translesional spinal network after SCI. We further discuss evidence of translesional network reorganization after SCI in the presence of sensory inputs during motor training. In this review, we evaluate potential mechanisms that underlie translesional circuitry reorganization during neuromodulation and rehabilitation in order to enable motor functions after SCI. We discuss the potential of neuromodulation technologies to engage various components that comprise the translesional network, their functional recovery after SCI, and the implications of the concept of translesional network in development of future neuromodulation, rehabilitation, and neuroprosthetics technologies.

Newly regenerated axons via scaffolds promote sub-lesional reorganization and motor recovery with epidural electrical stimulation.

Here, we report the effect of newly regenerated axons via scaffolds on reorganization of spinal circuitry and restoration of motor functions with epidural electrical stimulation (EES). Motor recovery was evaluated for 7 weeks after spinal transection and following implantation with scaffolds seeded with neurotrophin producing Schwann cell and with rapamycin microspheres. Combined treatment with scaffolds and EES-enabled stepping led to functional improvement compared to groups with scaffold or EES, although, the number of axons across scaffolds was not different between groups. Re-transection through the scaffold at week 6 reduced EES-enabled stepping, still demonstrating better performance compared to the other groups. Greater synaptic reorganization in the presence of regenerated axons was found in group with combined therapy. These findings suggest that newly regenerated axons through cell-containing scaffolds with EES-enabled motor training reorganize the sub-lesional circuitry improving motor recovery, demonstrating that neuroregenerative and neuromodulatory therapies cumulatively enhancing motor function after complete SCI.

Complementary Fourier Single-Pixel Imaging.

Single-pixel imaging, with the advantages of a wide spectrum, beyond-visual-field imaging, and robustness to light scattering, has attracted increasing attention in recent years. Fourier single-pixel imaging (FSI) can reconstruct sharp images under sub-Nyquist sampling. However, the conventional FSI has difficulty balancing imaging quality and efficiency. To overcome this issue, we proposed a novel approach called complementary Fourier single-pixel imaging (CFSI) to reduce the number of measurements while retaining its robustness. The complementary nature of Fourier patterns based on a four-step phase-shift algorithm is combined with the complementary nature of a digital micromirror device. CFSI only requires two phase-shifted patterns to obtain one Fourier spectral value. Four light intensity values are obtained by loading the two patterns, and the spectral value is calculated through differential measurement, which has good robustness to noise. The proposed method is verified by simulations and experiments compared with FSI based on two-, three-, and four-step phase shift algorithms. CFSI performed better than the other methods under the condition that the best imaging quality of CFSI is not reached. The reported technique provides an alternative approach to realize real-time and high-quality imaging.

Defective Ag-In-S/ZnS quantum dots: an oxygen-derived free radical scavenger for mitigating macrophage inflammation.

Oxidative stress plays an important role in the development of inflammatory diseases including allergy, heart disease, diabetes and cancer. Nanomaterial-mediated antioxidant therapy is regarded as a promising strategy to treat oxidative stress-mediated inflammation. Herein, defective Ag-In-S/ZnS quantum dots (AIS/ZnS QDs) with oxygen-derived radical-scavenging capabilities are developed. Owing to their intrinsic defects and abundant surface functional groups, these quantum dots exhibit excellent oxygen-derived free radical removal efficiency in vitro. In macrophages, AIS/ZnS QDs can eliminate intracellular excessive ROS stimulated by either H2O2 or lipopolysaccharide (LPS), thus can effectively protect macrophages against ROS-induced oxidative injury. Moreover, in the model of LPS-triggered macrophage inflammation, they exhibit benign anti-inflammatory ability by inhibiting the expression of related proinflammatory cytokines (e.g., TNF-α and IL-6). These findings indicate that AIS/ZnS QDs hold great potential for the treatment of ROS-related inflammatory disorders.

Defining Spatial Relationships Between Spinal Cord Axons and Blood Vessels in Hydrogel Scaffolds.

Positively charged oligo(poly(ethylene glycol) fumarate) (OPF+) hydrogel scaffolds, implanted into a complete transection spinal cord injury (SCI), facilitate a permissive regenerative environment and provide a platform for controlled observation of repair mechanisms. Axonal regeneration after SCI is critically dependent upon nutrients and oxygen from a newly formed blood supply. Our objective was to investigate fundamental characteristics of revascularization in association with the ingrowth of axons into hydrogel scaffolds, thereby defining spatial relationships between axons and the neovasculature. A novel combination of stereologic estimates and precision image analysis techniques quantitate neurovascular regeneration in rats. Multichannel hydrogel scaffolds containing Matrigel-only (MG), Schwann cells (SCs), or SCs with rapamycin-eluting poly(lactic co-glycolic acid) microspheres (RAPA) were implanted for 6 weeks following complete spinal cord transection. Image analysis of 72 scaffold channels identified a total of 2494 myelinated and 4173 unmyelinated axons at 10 µm circumferential intervals centered around 708 individual blood vessel profiles. Blood vessel number, density, volume, diameter, intervessel distances, total vessel surface and cross-sectional areas, and radial diffusion distances were compared. Axon number and density, blood vessel surface area, and vessel cross-sectional areas in the SC group exceeded that in the MG and RAPA groups. Individual axons were concentrated within a concentric radius of 200-250 µm from blood vessel walls, in Gaussian distributions, which identified a peak axonal number (Mean Peak Amplitude) corresponding to defined distances (Mean Peak Distance) from each vessel, the highest concentrations of axons were relatively excluded from a 25-30 µm zone immediately adjacent to the vessel, and from vessel distances >150 µm. Higher axonal densities correlated with smaller vessel cross-sectional areas. A statistical spatial algorithm was used to generate cumulative distribution F- and G-functions of axonal distribution in the reference channel space. Axons located around blood vessels were definitively organized as clusters and were not randomly distributed. A scoring system stratifies 5 direct measurements and 12 derivative parameters influencing regeneration outcomes. By providing methods to quantify the axonal-vessel relationships, these results may refine spinal cord tissue engineering strategies to optimize the regeneration of complete neurovascular bundles in their relevant spatial relationships after SCI. Impact statement Vascular disruption and impaired neovascularization contribute critically to the poor regenerative capacity of the spinal cord after injury. In this study, hydrogel scaffolds provide a detailed model system to investigate the regeneration of spinal cord axons as they directly associate with individual blood vessels, using novel methods to define their spatial relationships and the physiologic implications of that organization. These results refine future tissue engineering strategies for spinal cord repair to optimize the re-development of complete neurovascular bundles in their relevant spatial architectures.

Mn2+/Mn4+ co-doped LaM1-xAl11-yO19 (M = Mg, Zn) luminescent materials: electronic structure, energy transfer and optical thermometric properties.

Dual-emitting manganese ion doped LaM1-xAl11-yO19 (M = Mg, Zn) phosphors were prepared by substituting Zn2+/Mg2+ with Mn2+ and replacing Al3+ with Mn4+. The LaM1-xAl11-yO19:xMn2+,yMn4+ phosphors show a narrow green emission band of the Mn2+ ions at 514 nm and a red emission band of the Mn4+ ions at 677 nm. In addition, the thermal stability of luminescence shows that the response of Mn2+ and Mn4+ to the temperature is obviously different in LaMAl11O19, implying the potential of the prepared phosphors as optical thermometers. The decay lifetime of Mn4+ was changed with temperature due to the different fluorescence intensity ratios of Mn2+ and Mn4+, and a dual-mode optical temperature-sensing mechanism was studied in the temperature range of -50-200 °C. The maximum relative sensitivities (Sr) are calculated as 3.22 and 3.13% K-1, respectively. The unique optical thermometric features demonstrate the application potential of LaMAl11O19:Mn2+,Mn4+ in optical thermometry.

Early and sustained improvements in motor function in rats after infusion of allogeneic umbilical cord-derived mesenchymal stem cells following spinal cord injury.

STUDY DESIGN: Animal study. OBJECTIVES: Umbilical cord-derived mesenchymal stem cells (UC-MSCs) have recently been shown to hold great therapeutic potential for spinal cord injury (SCI). However, majority of the studies have been done using human cells transplanted into the rat with immunosuppression; this may not represent the outcomes that occur in humans. Herein, we present the therapeutic effect of using rat UC-MSCs (rUC-MSC) without immunosuppression in a rat model of SCI. SETTING: Mayo Clinic, Rochester, MN, USA. METHODS: Twelve female rats were randomly divided into two groups, control, and rUC-MSC group, and then subjected to a T9 moderate contusion SCI. Next, 2 × 106 rUC-MSCs or ringer-lactate solution were injected through the tail vein at 7 days post injury. Rats were assessed for 14 weeks by an open-field Basso, Beattie, and Bresnahan (BBB) motor score as well as postmortem quantification of axonal sparing/regeneration, cavity volume, and glial scar. RESULTS: Animals treated with rUC-MSCs were found to have early and sustained motor improvement (BBB score of 14.6 ± 1.9 compared to 10.1 ± 1.7 in the control group) at 14 weeks post injury (mean difference: 4.55, 95% CI: 2.04 to 7.06; p value < 0.001). Total cavity volume in the injury epicenter was significantly reduced in the rUC-MSC group; control: 33.0% ± 2.1, rUC-MSC: 25.3% ± 3.8 (mean difference: -7.7% (95% CI: -12.3 to -2.98); p value < 0.05). In addition, spinal cords from rats treated with rUC-MSCs were found to have a significantly greater number of myelinated axons, decreased astrogliosis, and reduced glial scar formation compared to control rats. CONCLUSIONS: Our study indicates that intravenous injection of allogenic UC-MSCs without immunosuppression exert beneficial effects in subacute SCI and thus could be a useful therapy to improve the functional capacity among patients with SCI.

Growth of CdS nanotubes and their strong optical microcavity effects.

Nanotubes are often formed by the folding of one-layer or multilayer compounds under microscopic catalytic growth conditions. Here, CdS nanotubes with tunable wall sizes and optical microcavities were prepared via a simple thermal evaporation co-deposition technique with Sn metal nanowire templating and ejection. Compared to core-shell Sn/CdS nanowires, which have poor microcavity quality, the hollow/CdS nanotubes have a higher quality factor (Q) that can reach approximately 400 in the spectral range of 550-800 nm when excited by a continuous-wave 405 nm laser. This high Q factor leads to low-threshold lasing and line-width narrowing due to the mode selection, which are important in many fields, including lasers, sensors, communications, and optical storage. A theoretical mode analysis of the hollow/CdS nanotubes with different thicknesses addressed their microcavity mode confinement and enhancements. This technique provides a new way to prepare semiconductor nanotubes for new photonic devices and photoelectric applications.

Combinatorial tissue engineering partially restores function after spinal cord injury.

Hydrogel scaffolds provide a beneficial microenvironment in transected rat spinal cord. A combinatorial biomaterials-based strategy provided a microenvironment that facilitated regeneration while reducing foreign body reaction to the three-dimensional spinal cord construct. We used poly lactic-co-glycolic acid microspheres to provide sustained release of rapamycin from Schwann cell (SC)-loaded, positively charged oligo-polyethylene glycol fumarate scaffolds. The biological activity and dose-release characteristics of rapamycin from microspheres alone and from microspheres embedded in the scaffold were determined in vitro. Three dose formulations of rapamycin were compared with controls in 53 rats. We observed a dose-dependent reduction in the fibrotic reaction to the scaffold and improved functional recovery over 6 weeks. Recovery was replicated in a second cohort of 28 animals that included retransection injury. Immunohistochemical and stereological analysis demonstrated that blood vessel number, surface area, vessel diameter, basement membrane collagen, and microvessel phenotype within the regenerated tissue was dependent on the presence of SCs and rapamycin. TRITC-dextran injection demonstrated enhanced perfusion into scaffold channels. Rapamycin also increased the number of descending regenerated axons, as assessed by Fast Blue retrograde axonal tracing. These results demonstrate that normalization of the neovasculature was associated with enhanced axonal regeneration and improved function after spinal cord transection.

One-step synthesis of nail-like Mn-doped CdS/CdBr2 hetero-nanostructures for potential lasing application.

Nanoscale heterostructures, which incorporate two or more materials such as core-shell nanocrystals, core-crown nanoplates, or seeded nanorods, allow better control of the optical, electrical and magnetic properties that are inaccessible in single component nanostructure, yet their variety and controlled growth are still challenging. Here, a nail-like Mn-doped CdS/CdBr2 hetero-nanostructure, which has a hexagonal plate on top of a nanowire, is firstly fabricated by a simple one-step thermal evaporation process. According to the characterization results, its growth mechanism could be obtained, in which the manganese bromide precursor plays a critical role in the formation of such nail morphology. The amplified spontaneous emission of the 'nanonail' is achieved at a low threshold at room temperature, which come from the local and dense exciton scattering due to their interactions excited by fs pulse. These interesting nail-like heterostructures may provide promising templates for constructing high-performance optoelectronic devices.

From Large-Scale Synthesis to Lighting Device Applications of Ternary I-III-VI Semiconductor Nanocrystals: Inspiring Greener Material Emitters.

Quantum dots with fabulous size-dependent and color-tunable emissions remained as one of the most exciting inventories in nanomaterials for the last 3 decades. Even though a large number of such dot nanocrystals were developed, CdSe still remained as unbeatable and highly trusted lighting nanocrystals. Beyond these, the ternary I-III-VI family of nanocrystals emerged as the most widely accepted greener materials with efficient emissions tunable in visible as well as NIR spectral windows. These bring the high possibility of their implementation as lighting materials acceptable to the community and also to the environment. Keeping these in mind, in this Perspective, the latest developments of ternary I-III-VI nanocrystals from their large-scale synthesis to device applications are presented. Incorporating ZnS, tuning the composition, mixing with other nanocrystals, and doping with Mn ions, light-emitting devices of single color as well as for generating white light emissions are also discussed. In addition, the future prospects of these materials in lighting applications are also proposed.

GDNF Schwann cells in hydrogel scaffolds promote regional axon regeneration, remyelination and functional improvement after spinal cord transection in rats.

Positively-charged oligo[poly(ethylene glycol)fumarate] (OPF+ ) is a biodegradable hydrogel used for spinal cord injury repair. We compared scaffolds containing primary Schwann cells (SCs) to scaffolds delivering SCs genetically modified to secrete high concentrations of glial cell-derived neurotrophic factor (GDNF). Multichannel OPF+ scaffolds loaded with SCs or GDNF-SCs were implanted into transected rat spinal cords for 4 weeks. GDNF-SCs promoted regeneration of more axons into OPF+ scaffolds (2773.0 ± 396.0) than primary SC OPF+ scaffolds (1666.0 ± 352.2) (p = 0.0491). This increase was most significant in central and ventral-midline channels of the scaffold. Axonal remyelination was quantitated by stereologic analysis. Increased myelination of regenerating axons was observed in the GDNF-SC group. Myelinating cell and axon complexes were formed by host SCs and not by implanted cells or host oligodendrocytes. Fast Blue retrograde tracing studies determined the rostral-caudal directionality of axonal growth. The number of neurons that projected axons rostrally through the GDNF-SC scaffolds was higher (7929 ± 1670) than in animals with SC OPF+ scaffolds (1069 ± 241.5) (p < 0.0001). The majority of ascending axons were derived from neurons located more than 15 mm from the scaffold-cord interface, and were identified to be lumbosacral intraspinal motor neurons. Transected animals with GDNF-SC OPF+ scaffolds partially recovered locomotor function at weeks 3 and 4 following surgery. Copyright © 2017 John Wiley & Sons, Ltd.

Top-Down Fabrication of Stable Methylammonium Lead Halide Perovskite Nanocrystals by Employing a Mixture of Ligands as Coordinating Solvents.

A top-down method is demonstrated for the fabrication of CH3 NH3 PbBr3 and CH3 NH3 PbI3 perovskite nanocrystals, employing a mixture of ligands oleic acid and oleylamine as coordinating solvents. This approach avoids the use of any polar solvents, skips multiple reaction steps by employing a simple ultrasonic treatment of the perovskite precursors, and yields rather monodisperse blue-, green-, and red-emitting methylammonium lead halide nanocrystals with a high photoluminescence quantum yield (up to 72 % for the green-emitting nanocrystals) and remarkably improved stability. After discussing all relevant reaction parameters, the green-emitting CH3 NH3 PbBr3 nanocrystals are employed as a component of down-conversion white-light-emitting devices.

Synthesis, optical properties and applications of light-emitting copper nanoclusters.

Metal nanoclusters (NCs) containing a few to a few hundreds of atoms bridge the gap between nanoparticles and molecular compounds. The last decade evidenced impressive developments of noble metal NCs such as Au and Ag. Copper is an earth abundant, inexpensive metal from the same group of the periodic table, which is increasingly coming into focus for NC research. This review specifically addresses wet chemical synthesis methods, optical properties and some emerging applications of Cu NCs. As surface protecting templates/ligands play an important role in the stability and properties of Cu NCs, we classified the synthetic methods by the nature of the capping agents. The optical properties of Cu NCs are discussed from the point of view of the effects of the metal core, surface ligands and environment (solvents and aggregation) on the emission of the clusters. Applications of luminescent Cu NCs in biological imaging and light emitting devices are considered.

Mesoporous Aluminum Hydroxide Synthesized by a Single-Source Precursor-Decomposition Approach as a High-Quantum-Yield Blue Phosphor for UV-Pumped White-Light-Emitting Diodes.

Strongly emissive (photoluminescence quantum yield up to 65%), thermally stable aluminum hydroxide blue phosphors are synthesized by a single-source precursor-decomposition approach. Blue-emitting UV-pumped light-emitting diodes (LEDs) based on the aluminum hydroxide phosphor reach luminous efficiency of 27.5 lm W-1 , while UV-white-LEDs integrating blue-emitting aluminum hydroxide and red-emitting CuInS2 nanocrystals achieve high color-rendering-index values of 94.3 and luminous efficiency of 23.5 lm W-1 .

Stretchable and Thermally Stable Dual Emission Composite Films of On-Purpose Aggregated Copper Nanoclusters in Carboxylated Polyurethane for Remote White Light-Emitting Devices.

Stretchable, mechanically stable films with thermally stable dual emission peaked in the blue and orange spectral range are fabricated by condensation and aging of carboxylated polyurethane in the presence of on-purpose aggregated copper nanoclusters. The aggregation of copper clusters leads to the enhancement of their emission in the orange, while polyurethane matrix contributes with the blue emission band, with an overall photoluminescence quantum yield of the films as high as 18%. Composite Cu nanoclusters/polyurethane films are sufficiently transparent over the visible spectral range and are absorbing in the UV range; more than 90% of their emission intensity is preserved after 10 times of cycle of stretch and recovery, as well as aging of up to 10 h at 90 °C, making them useful for optoelectronic devices. Remote white light-emitting devices (LEDs) have been fabricated by placing a down-conversion layer of composite Cu nanoclusters/polyurethane film separated through a silicone resin spacer from the UV LED chip, with Commission Internationale de l'Eclairage color coordinates of (0.34, 0.29), and a high color rendering index of 87.