Photo-biodegradation of imidacloprid under blue light-emitting diodes with bacteria and co-metabolic regulation.

Imidacloprid (IMI) is existence in the soil environment with a half-life habitually more than hundred days. This study targets to determine, identify and characterize photo-biodegradation bacteria from neonicotinoids (NEOs) contaminated agricultural field soils. The sub-surface soil had a higher level contamination of NEOs, in specifically greater concentration of IMI (3445.2 ± 0.09 µg/g) and thiacloprid (4084.4 ± 0.09 µg/g) has been found. Three bacteria Ralstonia pickettii (PBMS-2), Bacillus cereus (PBMS-3) and Shinella zoogloeoides (PBMS-4) was identified from soil-free stable enrichment cultures. The biodegradability of IMI (50 mg L-1) by three bacteria under different colors of light-emitting diodes (LEDs) with a constant 12 V power supply was tested and found that the blue-LEDs had greatest efficiency in supporting biodegradation of IMI which is called photo-biodegradation. In specific, the rate of photo-biodegradation of IMI by Ralstonia pickettii (87%), Bacillus cereus (80%) and Shinella zoogloeoides (80%) was measured. Besides this study also tested the effect of aeration (rpm), pH, and temperature on photo-biodegradation of IMI. There were seven intermediate metabolites were measured as biodegradation products of IMI under photo-biodegradation conditions and they are; IMI-urea, IMI-desnitro, 6-chloronicotinic acid, 6-hydroxy nicotinic acid, IMI- aminoguanidine, IMI-nitrosoguanidine and 4,5-hydroxy IMI, these metabolites are may non-toxic to the environment.

Agricultural waste materials enhance protease production by Bacillus subtilis B22 in submerged fermentation under blue light-emitting diodes.

Bacillus bacteria have major utility in large-scale production of industrial enzymes, among which proteases have particular importance. B. subtilis B22, an aerobic and chemotrophic strain, was isolated from kimchi and identified by 16S rRNA gene sequencing. Extracellular protease production was determined in basic medium, with 1% (w/v) casein as substrate, by submerged fermentation at 37 °C under blue, green, red and white light-emitting diodes (LEDs), white fluorescent light and darkness. Fermentation under blue LEDs maximized protease production (110.79 ± 1.8 U/mL at 24 h). Various agricultural waste products enhanced production and groundnut oil cake yielded the most protease (334 ± 1.8 U/mL at 72 h). Activity and stability of the purified protease were optimum at pH 7-10 and 20-60 °C. Activity increased in the presence of Ca2+, Mg2+ and Mn2+, while Fe2+, Zn2+, Co2+ and Cu2+ moderated activity, and Ni2+ and Hg2+ inhibited activity. Activity was high (98%) in the presence of ethylenediaminetetraacetic acid (EDTA) but inhibited by phenylmethanesulfonyl fluoride (PMSF). The protease was unaffected by nonionic surfactants, tolerated an anionic surfactant and oxidizing agents, and was compatible with multiple organic solvents. These properties suggest utility of protease produced by B. subtilis B22 under blue LEDs for industrial applications.

Carbon Dots as a Promising Green Photocatalyst for Free Radical and ATRP-Based Radical Photopolymerization with Blue LEDs.

Carbon dots (CDs) have been used for the first time as a sensitizer to initiate and activate free radical and controlled radical polymerization, respectively, based on an ATRP protocol with blue LEDs. Consideration of diverse heteroatom-doped CDs indicated that N-doped CDs could serve as an effective photocatalyst and photosensitizer in combination with LEDs emitting either at 405 nm or 470 nm. Free radical polymerization was initiated by combining the CDs with an iodonium or sulfonium salt in tri(propylene glycol) diacrylate. Polymerization of methyl methacrylate (MMA) by photo-induced ATRP was achieved with CDs and ethyl α-bromophenylacetate using CuII as catalyst in the ppm range. The polymers obtained showed temporal control, narrower dispersity ≲1.5, and chain-end fidelity. The first-order kinetics and ON/OFF experiments additionally gave evidence of the constant concentration of polymer radicals. No remarkable cytotoxic activity was observed for the CDs, underlining their biocompatibility.

Enhanced amylase production by a Bacillus subtilis strain under blue light-emitting diodes.

A chemotrophic, aerobic bacterial strain, Bacillus subtilis B2, was used to produce amylase by submerged fermentation under different light sources. SDS-PAGE indicated that the 55 kDa enzyme belonged to the α-amylase group. B2 was incubated in basal media with 1% soluble starch (pH 7.0) under blue, green, red, and white light-emitting diodes (LEDs), and white fluorescent light. Fermentation under blue LEDs maximized amylase production (180.59 ± 1.6 U/mL at 24 h). Production at 48 h increased to 310.56 ± 1.6 U/mL with 5% glucose as a simple carbon source and to 300.51 ± 1.7 U/mL with 5% groundnut oil cake as an agricultural waste substrate. Activity and stability of the amylase were greatest at pH 7.0 and 45-55 °C. Na+, Ca2+, Mg2+, Co2+, Ba2+, and K+ increased activity, while Ni2+, Hg2+, Mn2+, Cu2+, Fe3+, and Zn2+ inhibited activity. EDTA, PMSF and DTNB reduced activity by 50% or more, while tetrafluoroethylene and 1,10-phenanthroline reduced activity by 30%. The amylase was highly tolerant of the surfactants, compatible with organic solvents, oxidizing agents and the reducing agents reduced activity. These properties suggest utility of amylase produced by B. subtilis B2 under blue LED-mediated fermentation for industrial applications.

Furans Accessed through Visible-Light-Mediated Oxidative [3+2] Cycloaddition of Enols and Alkynes.

Visible-light-mediated formation of furans though direct oxidative [3+2] cycloaddition of 1,3-diones and alkynes is described. This protocol provides a simple and mild route to poly-substituted furans in moderate-to-good yields. Preliminary mechanistic studies suggest that this reaction likely follows a radical addition/cyclization pathway.

Growth of GaN Layers on Sapphire by Low-Temperature-Deposited Buffer Layers and Realization of p-type GaN by Magesium Doping and Electron Beam Irradiation (Nobel Lecture).

This Review is a personal reflection on the research that led to the development of a method for growing gallium nitride (GaN) on a sapphire substrate. The results paved the way for the development of smart display systems using blue LEDs. The most important work was done in the mid to late 80s. The background to the author's work and the process by which the technology that enables the growth of GaN and the realization of p-type GaN was established are reviewed.

Phosphonic Chloride Assisted Fabrication of Highly Emissive Mixed Halide Perovskite Films in Ambient Air for Blue Light-Emitting Diodes.

Blue perovskite light-emitting diodes (LEDs) have emerged as promising candidates for full-color display and lighting applications. However, the fabrication of blue-emitting perovskite films typically requires an inert environment, leading to increased complexity and cost in the manufacturing process, which is undesirable for applications of perovskite LEDs. Herein, we report a strategy to fabricate bright blue-emitting perovskite films in ambient air by incorporating phosphonic chlorides in a perovskite precursor solution. We used two different phosphonic chlorides, diphenylphosphonic chloride (DPPC) and phenylphosphonic dichloride (PPDC), and comparatively studied their effects on the properties of perovskite films and the blue LEDs. It is found that PPDC possesses a stronger chlorination ability due to higher hydrolysis reactivity; meanwhile, it has a stronger interaction with the perovskite compared to DPPC, resulting in an improved film quality and enhanced blue emission with a photoluminescence quantum yield of 45%, which represents the record value for the air-processed blue perovskite films. Blue perovskite LEDs are fabricated, and the emission wavelengths are effectively tuned by controlling the concentration of phosphonic chlorides. Benefiting from the optimized perovskite films with reduced nonradiative recombination and promoted charge injection and transport, the PPDC-derived blue perovskite LEDs exhibit improved performance with an external quantum efficiency of 3.3% and 1.2% for the 490 and 480 nm emission wavelength, respectively.

Enhancing Emission and Stability in Na-Doped Cs3Cu2I5 Nanocrystals.

Lead-free Cs3Cu2I5 metal halides have garnered significant attention recently due to their non-toxic properties and deep-blue emission. However, their relatively low photoluminescence quantum efficiency and poor stability have limited their applications. In this work, sodium iodide (NaI) is used to facilitate the synthesis of Cs3Cu2I5 nanocrystals (NCs), demonstrating improved photoluminescence intensity, photoluminescence quantum yield, and stability. Systematic optoelectronic characterizations confirm that Na+ is successfully incorporated into the Cs3Cu2I5 lattice without altering its crystal structure. The improved Photoluminescence Quantum Yield (PLQY) and stability are attributed to the strengthened chemical bonding, which effectively suppresses vacancy defects in the lattice. Additionally, light-emitting diodes (LEDs) based on 10% NaI-doped Cs3Cu2I5 NCs were assembled, emitting vibrant blue light with a maximum radiant intensity of 82 lux and Commission Internationale de l'Eclairage (CIE) chromaticity coordinates of (0.15, 0.1). This work opens new possibilities for commercial lighting display applications.

Control of n-Phase Distribution in Quasi Two-Dimensional Perovskite for Efficient Blue Light-Emitting Diodes.

Pure-bromide quasi-2D perovskite (PBQ-2DP) promises high-performance light-emitting diodes (LEDs), while a challenge remains on control over its n-phase distribution for bright true-blue emission. Present work addresses the challenge through exploring the passivation molecule of amino acid with reinforced binding energy, which generates narrow n-phase distribution preferentially at n = 3 with true blue emission at 478 nm. Consequently, a peak external quantum efficiency of 5.52% and a record brightness of 512 cd m-2 are achieved on the PBQ-2DP-based true blue PeLED, these both values located among the top in the records of similar devices. We further reveal that the electron-phonon coupling results in the red-shifted emission in the PBQ-2DP film, suggesting that the view of n-phase distribution dominated true-blue emission in PBQ-2DP needs to be revisited, pointing out a guideline of electron-phonon coupling suppression to relieve the strait of realizing true blue or even deep blue emission in the PBQ-2DP film.

Two-In-One: End-Emitting Blue LED and Self-Powered UV Photodetector based on Single Trapezoidal PIN GaN Microwire for Ambient Light UV Monitoring and Feedback.

With the continuous miniaturization and integration of the semiconductor industry, micro/nanoscale integrated photonics has received extensive attention as a key technology for optical communication, optical storage, and optical interconnection. Here, a two-in-one device is reported with both unidirectional blue light emission and UV photodetection functions based on single trapezoidal PIN GaN microwire. By constructing a Fabry-Perot resonator cavity structure, the end-emitting blue light-emitting diode with a low turn-on voltage (≈0.97 V) and high color purity (full width at half maximum ≈22 nm) is implemented. Furthermore, benefiting from the slow growth rate of the semipolar planes on both sides of the trapezoidal microwire and the high diffuse reflectivity of the patterned substrate, the trapezoidal microwire sides can be used as a high-performance UV photodetector. In self-driven mode, the device exhibits a large responsivity (0.218 A W-1 ), high external quantum efficiency (83.31%) and fast response speed (rise/decay time of 0.48/0.98 ms). Finally, the prepared two-in-one device is successfully integrated into ambient light UV monitoring and feedback system and tested. This work provides a novel strategy to combine luminescence with photodetection, demonstrating high potential for applications, such as on-chip photonic integration, energy-saving communication and ambient light monitoring and feedback system.

Basic Amino Acids Modulated Neutral-pH PEDOT:PSS for Stable Blue Perovskite Light-Emitting Diodes.

State-of-the-art external quantum efficiencies (EQEs) have exceeded 20% for near-infrared, red, and green perovskite light-emitting diodes (PeLEDs) so far. Nevertheless, the cutting-edge blue counterparts demonstrate an inferior device performance, which impedes the commercialization and industrialization of PeLEDs in ultrahigh-definition displays. As the most popular hole transport layer, poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS) bears the acidic and hygroscopic drawbacks, which deteriorates the device efficiency and long-term stability of blue PeLEDs. In this work, the basic amino acids with zwitterionic characteristics are proposed to modulate the pH of PEDOT:PSS, which are arginine, lysine, and histidine. It is found that they play a triple function to the blue perovskite films: modulating the acidity of PEDOT:PSS, controlling the crystalline process, and passivating the defects at the PEDOT:PSS/perovskite interface. As a result, the utilization of neutral PEDOT:PSS leads to a significant enhancement in stability and photoluminescence quantum yield. Eventually, the pure-blue PeLEDs achieve a record EQE of 5.6% with the emission peak at 467 nm. This research proves that the interfacial engineering of hole transport layers is a reliable strategy to enhance the device efficiency and operation stability of blue PeLEDs.

Low-level controllable blue LEDs irradiation enhances human dental pulp stem cells osteogenic differentiation via transient receptor potential vanilloid 1.

Human dental pulp stem cells (hDPSCs) have attracted tremendous attention in tissue regeneration engineering due to their excellent multidirectional differentiation potential. Photobiomodulation (PBM) using low-level light-emitting diodes (LEDs) or lasers has been proved to promote the osteogenesis of mesenchymal stem cells. However, the effect of LEDs on osteogenic differentiation of hDPSCs has little published data. In this work, the effect of blue LEDs with different energy densities of 2, 4, 6, 8, 10 J/cm2 on osteogenic differentiation of hDPSCs was examined by using in vitro ALP staining, ALP activity, mineralization, and real-time PCR. The results showed that compared with the control group, osteogenic differentiation was significantly enhanced in blue LEDs treated groups. As the energy density increased, the level of osteogenesis initially increased and then decreased reaching the highest level at 6 J/cm2. Transient receptor potential vanilloid 1 (TRPV1), a Ca2+ ion channel, was believed to be a potential player in osteogenesis by photobiomodulation. By immunofluorescence assay, calcium influx assay, PCR, and ALP staining, it was shown that blue LEDs irradiation can increase the activity of TRPV1 and intracellular calcium levels similarly to the agonist of TRPV1 capsaicin. Additionally, pretreatment with capsazepine, a selective TRPV1 inhibitor, was able to abrogate the osteogenic effect of blue LEDs. In conclusion, these findings proposed that blue LEDs can promote the osteogenesis of hDPSCs within the appropriate range (4-8 J/cm2) during culture of osteogenic medium, and TRPV1/Ca2+ may be an essential signaling pathway involved in blue LEDs-induced osteogenesis, providing new insights for the use of hDPSCs in tissue regeneration engineering.

Filling Chlorine Vacancy with Bromine: A Two-Step Hot-Injection Approach Achieving Defect-Free Hybrid Halogen Perovskite Nanocrystals.

Mixed-halide (Cl and Br) perovskite nanocrystals (NCs) are of particular interest because they hold great potential for use in high-efficiency blue light-emitting diodes (LEDs). Generally, mixed-halide compounds are obtained by either a one-step synthesis with simultaneous addition of both halide precursors or a postsynthetic anion exchange using the opposite halogen. However, both strategies fail to prevent the formation of deep-level Cl vacancy defects, rendering the photoluminescence quantum yields (PLQYs) typically lower than 30%. Here, by optimizing both thermodynamic and kinetic processes, we devise a two-step hot-injection approach, which simultaneously realizes Cl vacancy filling and efficient anion exchange between Cl- and Br-. Both the identity of Br precursors and their injection temperature are revealed to be critical in transforming those highly defective CsPbCl3 NCs to defect-free CsPb(Cl/Br)3. The optimally synthesized NCs exhibit a saturated blue emission at ∼460 nm with a near-unity PLQY and a narrow emission bandwidth of 18 nm, which represents one of the most efficient blue emitters reported so far. The turn-on voltage of the ensuing LEDs is ∼4.0 V, which is lower than those of most other mixed-halide perovskites. In addition, LEDs exhibit a stable electroluminescence peak at 460 nm under a high bias voltage of 8.0 V. We anticipate that our findings will provide new insights into the materials design strategies for producing high-optoelectronic-quality Cl-containing perovskites.

Thermodynamics-Induced Injection Enhanced Deep-Blue Perovskite Quantum Dot LEDs.

Precisely tuning emission spectra through the component control of mixed halides has been proved to be an efficient method for procuring deep-blue perovskite LEDs (PeLEDs). However, the inferior color instability and lifetime attenuation, originated from vacancy- and trap-mediated mechanisms under an external field, remain an uninterruptedly formidable challenge for the commercial development of PeLEDs. Here, an ultrafast thermodynamics-induced injection enhancement strategy was employed to promote efficient carrier recombination within perovskite quantum dots (QDs), accompanied by less inefficient charge accumulation and trap generation, enabling deep-blue PeLEDs with improved thermal and spectral stability. The resultant PeLEDs feature an external quantum efficiency (EQE) of 3.66%, a max luminance of 2100 cd/m2 at the electroluminescence (EL) of 460 nm, and a halftime of 288 s. This work provides a general platform for promoting the EL performances and a deep insight into unraveling the degradation mechanism of blue PeLEDs.

Phase Control and In Situ Passivation of Quasi-2D Metal Halide Perovskites for Spectrally Stable Blue Light-Emitting Diodes.

The fabrication of efficient and spectrally stable pure-blue perovskite light-emitting diodes (LEDs) has been elusive and remains of great interest. Herein, we incorporate diammonium salts into quasi-2D perovskite precursors for phase control of multiple quantum well structures to yield tunable and efficient emission in the blue region. With detailed characterizations and computational studies, we show that in situ passivation by the diammonium salts effectively modifies the surface energies of quasi-2D phases and inhibits the growth of low-band gap quasi-2D and 3D phases. Such phase control and in situ passivation could afford blue light-emitting perovskite thin films with high photoluminescence quantum efficiencies of, for instance, 75% for the emission peak at 471 nm. Using this perovskite thin film as an emitting layer, spectrally stable pure-blue LEDs with an emission peak at 474 nm and a full width at half-maximum of 26 nm could be fabricated to exhibit a brightness of 290 cd m-2 at 8 V and an external quantum efficiency of 2.17%.

Reducing Architecture Limitations for Efficient Blue Perovskite Light-Emitting Diodes.

Light-emitting diodes utilizing perovskite nanocrystals have generated strong interest in the past several years, with green and red devices showing high efficiencies. Blue devices, however, have lagged significantly behind. Here, it is shown that the device architecture plays a key role in this lag and that NiOx , a transport layer in one of the highest efficiency devices to date, causes a significant reduction in perovskite luminescence lifetime. An alternate transport layer structure which maintains robust nanocrystal emission is proposed. Devices with this architecture show external quantum efficiencies of 0.50% at 469 nm, seven times higher than state-of-the-art devices at that wavelength. Finally, it is demonstrated that this architecture enables efficient devices across the entire blue-green portion of the spectrum. The improvements demonstrated here open the door to efficient blue perovskite light-emitting diodes.

Morphological, Photosynthetic, and Physiological Responses of Rapeseed Leaf to Different Combinations of Red and Blue Lights at the Rosette Stage.

Rapeseed (Brassica napus L.) is sensitive to light quality. The factory production of rapeseed seedlings for vegetable use and for transplanting in the field requires an investigation of the responses of rapeseed to light quality. This study evaluated the responses of the leaf of rapeseed (cv. "Zhongshuang 11") to different ratios of red-photonflux (RPF) and blue-photonflux (BPF) from light emitting diodes (LEDs). The treatments were set as monochromatic lights, including 100R:0B% and 0R:100B%, and compound lights (CLs), including 75R:25B%, 50R:50B%, and 25R:75B%. The total photonflux in all of the treatments was set as 550 µmolm(-2)s(-1). With an increase of BPF, the rapeseed leaves changed from wrinkled blades and down-rolled margins to flat blades and slightly up-rolled margins, and the compact degree of palisade tissue increased. One layer of the cells of palisade tissue was present under 100R:0B%, whereas two layers were present under the other treatments. Compared to 100R:0B%, 0R:100B% enhanced the indexes of leaf thickness, leaf mass per area (LMA), stomatal density, chlorophyll (Chl) content per weight and photosynthetic capacity (P max), and the CLs with high BPF ratios enhanced these indexes. However, the 100R:0B% and CLs with high RPF ratios enhanced the net photosynthetic rate (P n). The leaves under the CLs showed growth vigor, whereas the leaves under 100R:0B% or 0R:100B% were stressed with a low F v/F m (photosynthetic maximum quantum yield) and a high content of [Formula: see text] and H2O2. The top second leaves under 100R:0B% or 0R:100B% showed stress resistance responses with a high activity of antioxidase, but the top third leaves showed irreversible damage and inactivity of antioxidase. Our results showed that the rapeseed leaves grown under 0R:100B% or CLs with a high BPF ratio showed higher ability to utilize high photonflux, while the leaves grown under 100R:0B% or CLs with a low BPF ratio showed higher efficiency in utilizing low photonflux. Under different R:B photonflux ratios, red and blue lights may play mutual roles in P n. When the blue light dominated, the P n showed a B-preference. When the red light dominated, the P n showed an R-preference. Furthermore, CLs were suitable for the P n of rapeseed seedlings.

Efficient and stable white organic light-emitting diodes employing a single emitter.

Using a single tetradentate platinum emitter dubbed Pt7O7, efficient and stable white organic light-emitting diodes are developed. The excimer-based white devices achieve an external quantum efficiency (EQE) of 24.5%, coordinates of (0.37, 0.42) based on the Commission internationale de l'éclairage (CIE) system, and a color rendering index (CRI) of 70. Moreover, devices of Pt7O7 in a stable structure demonstrate operational lifetimes (50% initial luminance) of 36 h at an elevated driving current of 20 mA cm2, which corresponds to over 10,000 h at 100 cd m2.