Ultra‐broadband near‐infrared (NIR) luminescent materials are the most important component of NIR light‐emitting devices (LED) and are crucial for their performance in sensing applications. A major ...challenge is to design novel NIR luminescent materials to replace the traditional Cr3+‐doped systems. We report an all‐inorganic bismuth halide perovskite Cs2AgBiCl6 single crystal that achieves efficient broadband NIR emission by introducing Na ions. Experiments and density functional theory (DFT) calculations show that the NIR emission originates from self‐trapped excitons (STE) emission, which can be enhanced by weakening the strong coupling between electrons and phonons. The high photoluminescence quantum efficiency (PLQY) of 51 %, the extensive full width at half maximum (FWHM) of 270 nm and the stability provide advantages as a NIR luminescent material. The single‐crystal‐based NIR LED demonstrated its potential applications in NIR spectral detection as well as night vision.
An all‐inorganic bismuth halide perovskite Cs2AgBiCl6 single crystal achieves efficient broadband NIR emission by introducing Na ions. Experiments and DFT calculations show that the emission originates from self‐trapped excitons emission. The role of Na is to weaken the strong coupling between electrons and phonons and to localize the electron and hole wave functions to enhance this emission.
Yb3+ doped lead‐free double perovskites (DPs) with near‐infrared (NIR)‐emitting have attracted extensive attention due to their wide application prospects. Unfortunately, they still suffer from weak ...NIR emission due to undesirable resonance energy transfer between the sensitizers and Yb3+ ions. Herein, a new effective NIR‐emitting DP is developed by co‐doping Sb3+ and Yb3+ into Cs2AgInCl6. Experiments and theoretical calculations reveal that induced by co‐doping Sb3+ ions, the self‐trapped excitation (STE) emission intensity of Cs2AgInCl6 is greatly enhanced by 240 times, and the STE emission shifts from 600 nm to 660 nm, which contributes to a larger spectral overlap between STE emission and the absorption of Yb3+ ions. As a result, the absolute NIR photoluminescence quantum yield reaches an unprecedented 50% in lead‐free DPs via high‐efficiency STE sensitization (>30%). The excellent optical performance of Cs2AgInCl6: Sb, Yb with high ambient, thermal and light stability makes it suitable for application in night‐vision devices. Moreover, an ingenious dual‐modal optical information encryption based on the combination of visible and NIR fluorescence printing patterns utilizing Cs2AgInCl6: Sb and Cs2AgInCl6: Sb, Yb respectively is successfully demonstrated. This study provides inspiration for designing highly efficient NIR‐emitting Ln3+‐doped DPs and illustrates their great potential in versatile optoelectronic applications.
A new design strategy of Sb3+ ions co‐doping in Cs2AgInCl6:Yb3+ is proposed to expand absorption region to longer wavelengths and effectively enhance the near‐infrared emission of Yb3+ ions. The excellent sensitization efficiency from self‐trapped exciton to Yb3+ ions (>30%) gives Sb3+, Yb3+ co‐doped Cs2AgInCl6 unprecedented near‐infrared emission with a photoluminescence quantum yield of up to 50%.
Compared to solid scintillators and organic liquid scintillators, aqueous‐based liquid scintillators (AbLS) have more superiority in highly flexible scalability, yet are now limited by their low ...light yield (≈100 photons MeV−1). Here, aqueous‐based inorganic colloidal halide perovskites with high photoluminescence quantum yield (PLQY) of three primary color luminescence up to 88.1% (red), 96% (green), and 81.8% (blue) are respectively synthesized, and a new generation of colloidal perovskite‐mediated AbLS (PAbLS) with light yield increased in comparison with the commercial scintillator AbLS is fabricated. This paper exhibits that the excellent PLQY and colloidal dispersion of halide perovskites benefit from poly(ethylene glycol) modification and this modification ensures the vacancy inhibition and formation of defect–free surfaces in an aqueous solution. Moreover, their high luminescent emission can be maintained for 100 days at low temperatures, and such modification also promises the heat‐to‐cold customization of operating temperature even in ice below 0 °C. Finally, depending on the light yield of around 3058 and 8037 photons MeV−1 at room temperature and low temperature, PAbLS with shape/size scalability exhibit their robust radiation hardness (dose rate as high as 23 mGy s−1) and conceptual application potential in high‐energy ray radiation detection from every angle of 360°.
A new generation of perovskite‐mediated aqueous‐based liquid scintillators (PAbLS) with light yield increased in comparison with the commercial scintillator AbLS is fabricated. PAbLS with shape/size scalability exhibit their bright emission (photoluminescence quantum yield > 90%), robust stability (100 days), robust radiation hardness (82.8 Gy), and conceptual potential applied in radiation detection from every angle of 360°.
Water management and nitrogen application are critical factors in wheat grain yield and protein quality. This study aimed to evaluate the effect of irrigation and nitrogen application on the grain ...yield, protein content and amino acid composition of winter wheat. Field experiments were conducted in a split-plot design with three replications in high-yielding land on the North China Plain in 2012/2013, 2013/2014 and 2014/2015. Three irrigation treatments were examined in main plots: no irrigation, irrigation at jointing, and irrigation at jointing plus anthesis, while subplots were assigned to nitrogen treatment at four different rates: 0, 180, 240, 300 kg N ha-1, respectively. The results indicated that irrigation at jointing and at jointing plus anthesis improved grain yield by an average of 12.79 and 18.65% across three cropping seasons, respectively, compared with no irrigation. However, different irrigation treatments had no significant effect on grain protein content in any cropping season. Compared with no N treatment, 180, 240, and 300 kg N ha-1 N application significantly increased grain yield, by 58.66, 61.26 and 63.42% respectively, averaged over three cropping seasons. Grain protein and the total, essential and non-essential amino acid content significantly increased with increasing nitrogen application. Irrigation significantly improved the essential amino acid index (EAAI) and protein-digestibility-corrected amino acid score (PDCAAS) compared with no irrigation; however, N application decreased them by an average of 7.68 and 11.18% across three cropping seasons, respectively. EAAI and PDCAAS were positively correlated, however, they were highly negatively correlated with yield and grain protein content.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Microbial cell factories reinvigorate current industries by producing complex fine chemicals at low costs. Reduced nicotinamide adenine dinucleotide phosphate (NADPH) is the main reducing power to ...drive the biosynthetic pathways in microorganisms. However, insufficient intrinsic NADPH limits the productivity of microorganisms. Here, we report that supplying microorganisms with long‐lived electrons from persistent phosphor mesoporous Al2O3 (meso‐Al2O3) can elevate the NADPH level to facilitate efficient fine chemical production. The defects in meso‐Al2O3 were demonstrated to be highly efficient in prolonging electrons’ lifetime. The long‐lived electrons in meso‐Al2O3 can pass the material–microorganism interface and power the biosynthetic pathways of E. coli to produce jet fuel farnesene. This work represents a reliable strategy to design photo‐biosynthesis systems to improve the productivity of microorganisms with solar energy.
A hybrid photo‐biosynthesis system was constructed for the overproduction of jet fuel farnesene by interfacing engineered E. coli with persistent phosphor mesoporous Al2O3 (meso‐Al2O3). meso‐Al2O3 with rich defects prolonged the lifetime of photo‐excited electrons that were passed to E. coli and improved the farnesene production by a factor of over 100 %.
Development of a solar water splitting device requires design of a low‐cost, efficient, and non‐noble metal compound as alternative to noble metals. For the first time, we showed that CoSe2 can ...function as co‐catalyst in phototoelectrochemical hydrogen production. We designed a heterostructure of p‐Si and marcasite‐type CoSe2 for solar‐driven hydrogen production. CoSe2 successively coupled with p‐Si can act as a superior photocathode in the solar‐driven water splitting reaction. Photocurrents up to 9 mA cm−2 were achieved at 0 V vs. reversible hydrogen electrode. Electrochemical impedance spectroscopy showed that the high photocurrents can be attributed to low charge transfer resistance between the Si and CoSe2 interfaces and that between the CoSe2 and electrolyte interfaces. Our results suggest that this CoSe2 is a promising alternative co‐catalyst for hydrogen evolution.
Heterostructures of semi‐metallic CoSe2 nanorods and p‐Si microwires behave as an efficient photocathode for the solar‐driven hydrogen evolution reaction. Photocurrents as high as 9 mA cm−2 have been achieved at 0 V vs. reversible hydrogen electrode. The high photocurrents can be attributed to low charge transfer resistance between the Si and CoSe2 interfaces and between the CoSe2 and electrolyte interfaces.
Hydraulic fracturing can improve the permeability of coalbed methane (CBM) reservoirs effectively, which is of great significance to the commercial production of CBM. However, the efficiency of ...hydraulic fracturing is affected by multiple factors. The mechanism of fracture initiation, morphology and propagation in CBM reservoirs is not clear and need to be further explored. Hydraulic fracturing experiment is an accurate tool to explore these mechanisms. The quantity of experimental coal rock is large and processing method is complex, so specimen made of similar materials was applied to replace coal rock. The true triaxial hydraulic fracturing experimental apparatus, 3D scanning device for coal rock section were applied to carry out hydraulic fracturing experiment. The results show that the initiation pressure is inversely proportional to the horizontal stress difference (Δσ) and positively related to fracturing fluid injection rate. When vertical stress (σv) is constant, the initiation pressure and fracture width decrease with the increasing of Δσ. Natural fractures can be connected by main fracture when propagates perpendicular to the direction of minimum horizontal stress (σh), then secondary fractures and fracture network form in CBM reservoirs. When two stresses of crustal stress are close and far different from the third one, the fracture morphology and propagation become complex. Influenced by perforations and filtration of fracturing fluid in specimen, fracturing fluid flows to downward easily after comparing horizontal well fracturing with vertical well fracturing. Fracture width increases with the decreasing of elastic modulus, the intensity of fracture is positively related with the elastic modulus of coal rock. The research results can provide theoretical basis and technical support for the efficient development of CBM.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The site-dependent photoluminescence of activators can be regulated by the sintering atmosphere, coexistence conditions, and especially cation codoping, which have been intensively studied for design ...and optimization of optical functional materials. Here, first-principles calculations are performed to determine the regulation of the site occupancy, valence states and optical transitions of Mn activators
codoping in yttrium aluminum garnets (YAGs), which contain three different cation sites. Without any codopants, Mn
dominates in defect concentration and photoluminescence, which can hardly be tuned by the sintering atmosphere or coexistence conditions of YAGs with other competing compounds. With the low formation energy of Ca
, Be
, Mg
, and Sr
codopants and in an oxidation sintering atmosphere, the Fermi energy is lowered and the concentration and luminescence of Mn
are enhanced. Na
and Li
codopants with relatively high formation energy have little influence on tuning the Fermi energy. Then with the low formation energy of Ti
, Si
codopants and in a reducing sintering atmosphere, the Fermi energy is lifted and the luminescence of Mn
and Mn
is enhanced as a result of increased concentrations. The proposed first-principles scheme, with general applicability and encouraging predictive power, provides an effective approach for elucidating the effects of codoping impurities on the design and optimization of optical materials.
Laser sources have been considered to be better light sources compared to traditional lamps or light‐emitting diodes used in projectors, which enables the projector to create images with higher color ...saturation, brightness, and energy efficiency. However, the speckle noise caused by the coherent nature of the laser is a major technology obstacle for laser projection, which severely affects the image quality. To suppress laser speckle, a TiO2‐sapphire composite (TSC) with rough and high reflectivity surface and high thermal conductivity substrate is designed, which reduces the laser speckle by creating spatial diversity. Moreover, combined with a micro motor, the design and fabrication of the TSC rotating wheel are realized, which further reduces the laser speckle by creating time diversity. The experimental results show that the laser speckle contrast can be reduced from 9.0% to 2.2% when placing the TSC rotating wheel in the light path, which is below the speckle perception limit of the human eye (<4%). This new type of laser speckle suppression device is simple to use, low in cost, high in energy utilization, high in thermal conductivity, easy to mass production, and has great application potential in high‐power laser projection.
Extratropical cyclones are responsible for many of the high-impact weather events over the United States, including extreme cold, extreme high wind, and extreme heavy precipitation. In this study, ...impacts from the variations of the cyclone (or storm-track) activity on these extreme events are examined through composites based on map-averaged cyclone activity. Increased cyclone activity enhances the frequency of extreme cold and high wind events over much of the United States, and impacts extreme precipitation around the Ohio River valley. These impacts are largely due to a changing of the tail of the distribution rather than a shifting of the mean. To systematically study these impacts, three singular value decomposition (SVD) analyses have been conducted, each one between the cyclone activity and one kind of extreme event frequency. All three SVD leading modes represent a pattern of overall increase or decrease of storm tracks over the United States. The average of the time series of these leading modes is highly correlated with the observed map-averaged storm track and strongly associated with the Pacific–North America (PNA) pattern and El Niño–Southern Oscillation (ENSO). However, composites based on either the PNA pattern or ENSO do not show as strong impacts as the map-averaged storm track. A second common SVD mode is found that correlates weakly with the North Pacific mode and is likely to be largely due to internal variability. Finally, the potential impacts of projected storm-track change on the frequency of extreme events are examined, indicating that the projected storm-track decrease over North America may give rise to some reduction in the frequency of extreme events.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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