Semiconductor photocatalysis acts as a sustainable green technology to convert solar energy for environmental purification and production of renewable energy. However, the current photocatalysts ...suffer from inefficient photoabsorption, rapid recombination of photogenerated electrons and holes, and inadequate surface reactive sites. Introduction of oxygen vacancies (OVs) in photocatalysts has been demonstrated to be an efficacious strategy to solve these issues and improve photocatalytic efficiency. This review systematically summarizes the recent progress in the oxygen vacant semiconductor photocatalysts. Firstly, the formation and characterizations of OVs in semiconductor photocatalysts are briefly introduced. Then, highlighted are the roles of OVs in the photocatalytic reactions of three types of typical oxygen‐containing semiconductors, including metal oxides (TiO2, ZnO, WO3, W18O49, MoO3, BiO2‐x, SnO2, etc), hydroxides (In(OH)3, Ln(OH)3 (Ln=La, Pr, and Nd), Layered double hydroxides) and oxysalts (bismuth‐based oxysalts and others) photocatalysts. Moreover, the advanced photocatalytic applications of oxygen vacant semiconductor photocatalysts, such as pollutant removal, H2 production, CO2 reduction, N2 fixation and organic synthesis are systematically summarized. Finally, an overview on the current challenges and a prospective on the future of oxygen vacant materials is proposed.
Oxygen vacancies serve as the most effective defect engineering tactic to improve the photoabsorption, charge separation, and surface catalytic capability of photocatalysts. Here, three types of oxygen vacant semiconductors, including metal oxides (TiO2, ZnO, WO3, MoO3, etc), hydroxides (In(OH)3, Ln(OH)3 (Ln=La, Pr, and Nd), layered double hydroxides) and oxysalts (bismuth‐based oxysalts and others) photocatalysts, with diverse photocatalytic applications are summarized.
After a violent earthquake, the supply of medical services may fall short of the rising demand, leading to overcrowding in hospitals, and, consequently, a collapse in the healthcare system. This ...paper takes the emergency care system in Taiwan as the research context, where first-aid hospitals are ranked to three levels, advanced, intermediate, and general, and, currently, emphasizes on a general emergency responsibility hospital. Having limited capacity and capability, a general emergency responsibility hospital treats minor and moderate injuries, from which the majority of earthquake-induced casualties suffer. The purpose of this study is to analyze the impact of this group of earthquake-induced non-urgent patients on the performance of a hospital. A patient flow model was built to represent patients' paths throughout emergency care. Based on the model, discrete event simulation was applied to simulate patients' trajectories and states of a hospital under four seismic scenarios, where patient visits are 1.4, 1.6, 1.9, and 2.3 times the normal number. A healthcare performance index, Crowdedness Index (CI), is proposed to measure crowdedness on a daily basis, which is defined as the ratio of the average waiting time for treatment to the recommended maximal waiting time. Results of simulations rendered the establishment of empirical equations, describing the relation between the maximum CIs and the patient growth ratios. In the most severe case in this study, the maximum CI exceeds 92 and it takes 10 days to recover from the quality drop. This highlights the problem a general emergency responsibility hospital may encounter if no emergency response measure is implemented. Findings are provided pertaining to the predication of a recovery curve and the alarming level of patient increase, which are supportive information for preparedness planning as well as response measure formulation to improve resilience.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The phosphor‐converted light‐emitting diode (PC‐LED) has become an indispensable solid‐state lighting and display technologies in the modern society. Nevertheless, the use of scarce rare‐earth ...elements and the thermal quenching (TQ) behavior are still two most crucial issues yet to be solved. Here, this work successfully demonstrates a highly efficient and thermally stable green emissive MnI2(XanPO) crystals showing a notable photoluminescence quantum yield (PLQY) of 94% and a super TQ resistance from 4 to 623 K. This unprecedented superior thermal stability is attributed to the low electron–phonon coupling and the unique rigid crystal structure of MnI2(XanPO) over the whole temperature range based on the temperature‐dependent photoluminescence (PL) and single crystal X‐ray diffraction (SCXRD) analyses. Considering these appealing properties, green PC‐LEDs with a power efficacy of 102.5 lm W−1, an external quantum efficiency (EQE) of 22.7% and a peak luminance up to 7750 000 cd m−2 are fabricated by integrating MnI2(XanPO) with commercial blue LEDs. Moreover, the applicability of MnI2(XanPO) in both micro‐LEDs and organic light‐emitting diodes (OLEDs) is also demonstrated. In a nutshell, this study uncovers a candidate of highly luminescent and TQ resistant manganese halide suitable for a variety of emission applications.
A highly efficient and thermally stable manganese halide crystal, MnI2(XanPO) is demonstrated. The low electron–phono coupling along with rigid crystal structure contributes to excellent photoluminescent quantum yield of 94% with unprecedented near zero thermal quenching from 4 to 623 K. The crystals find their applications in light emitting diodes and micro light emitting diodes with excellent external quantum efficiency (EQE) up to 22.7% and power efficacy as high as 102.5 lm W−1.
A
bstract
We consider extended scalar sectors of the Standard Model as ultraviolet complete motivations for studying the effective Higgs self-interaction operators of the Standard Model effective ...field theory. We investigate all motivated heavy scalar models which generate the dimension-six effective operator, |
H
|
6
, at tree level and proceed to identify the full set of tree-level dimension-six operators by integrating out the heavy scalars. Of seven models which generate |
H
|
6
at tree level only two, quadruplets of hypercharge
Y
= 3
Y
H
and
Y
=
Y
H
, generate only this operator. Next we perform global fits to constrain relevant Wilson coefficients from the LHC single Higgs measurements as well as the electroweak oblique parameters
S
and
T
. We find that the
T
parameter puts very strong constraints on the Wilson coefficient of the |
H
|
6
operator in the triplet and quadruplet models, while the singlet and doublet models could still have Higgs self-couplings which deviate significantly from the standard model prediction. To determine the extent to which the |
H
|
6
operator could be constrained, we study the di-Higgs signatures at the future 100 TeV collider and explore future sensitivity of this operator. Projected onto the Higgs potential parameters of the extended scalar sectors, with 30 ab
−1
luminosity data we will be able to explore the Higgs potential parameters in all seven models.
As one of the most critical approaches to resolve the energy crisis and environmental concerns, carbon dioxide (CO2) photoreduction into value‐added chemicals and solar fuels (for example, CO, HCOOH, ...CH3OH, CH4) has attracted more and more attention. In nature, photosynthetic organisms effectively convert CO2 and H2O to carbohydrates and oxygen (O2) using sunlight, which has inspired the development of low‐cost, stable, and effective artificial photocatalysts for CO2 photoreduction. Due to their low cost, facile synthesis, excellent light harvesting, multiple exciton generation, feasible charge‐carrier regulation, and abundant surface sites, semiconductor quantum dots (QDs) have recently been identified as one of the most promising materials for establishing highly efficient artificial photosystems. Recent advances in CO2 photoreduction using semiconductor QDs are highlighted. First, the unique photophysical and structural properties of semiconductor QDs, which enable their versatile applications in solar energy conversion, are analyzed. Recent applications of QDs in photocatalytic CO2 reduction are then introduced in three categories: binary II–VI semiconductor QDs (e.g., CdSe, CdS, and ZnSe), ternary I–III–VI semiconductor QDs (e.g., CuInS2 and CuAlS2), and perovskite‐type QDs (e.g., CsPbBr3, CH3NH3PbBr3, and Cs2AgBiBr6). Finally, the challenges and prospects in solar CO2 reduction with QDs in the future are discussed.
Carbon dioxide (CO2) photoreduction is regarded as an attractive pathway to produce value‐added chemicals and fuels. Recent advances in CO2 photoreduction via semiconductor quantum dots (QDs) in three categories are reviewed: II–VI, I–III–VI, and perovskite‐type QDs. Additionally, current challenges and prospects for QD‐photocatalyzed CO2 reduction are discussed.
The use of photovoltaic cells with an organometallic perovskite as the active layer for indoor dim‐light energy harvesting is evaluated. By designing the electron‐transporting materials and ...fabrication processes, the traps in the perovskite active layers and carrier dynamics can be controlled, and efficient devices are demonstrated. The best‐performing small‐area perovskite photovoltaics exhibit a promising high power conversion efficiency up to ≈27.4%, no hysteresis behavior, and an exceptionally low maximum power point voltage variation of ≈0.1 V under fluorescent lamp illumination at 100–1000 lux. The 5.44 cm2 large‐area device also shows a high efficiency of 20.4% and a promising long‐term stability. Compared with the most efficient inorganic and organic solar cells nowadays, the competitive efficiency, low fabrication cost, and low raw material costs make perovskite photovoltaics ideal for indoor light harvesting and as Internet of Things power provider.
Device engineering of perovskite photovoltaics dedicated to indoor dim‐light applications is reported. The trap density in the perovskite layer is effectively eliminated by judiciously controlling the fabrication of the electron‐transporting layers. Small‐area lab cell and 5.44 cm2 large‐area device attain maximum efficiencies up to 27.4% and 20.4% under indoor illumination, respectively.
This study analyses the role of green growth in promoting a sustainable environment. In literature, the empirical and theoretical examination on the role of green growth in carbon dioxide (CO2) ...emissions is missing, especially in combination with other factors, i.e., human capital index, environment-related taxes and development of environment-related technologies. This study investigates the role of environmentally adjusted multifactor productivity growth (i.e. green growth) on CO2 emissions for G7 countries from 1991 to 2017. The study utilizes second generation panel data method(s), i.e. Cross-Sectionally Augmented Auto-regressive Distributive lag (CS-ARDL) model. The outcomes of theoretical and empirical findings indicate that both linear and non-linear term for green growth reduces CO2 emissions. Also, environmental tax, human capital and renewable energy use are found to decrease CO2 emissions. The impact of GDP growth both in short-run and long-run is environment depletion. However, our result supports the theoretical notion that green growth sustains environment quality. We obtained consistent results from panel causality test. Our results may further strengthen the belief of policymakers in developed countries on the promotion of green growth.
Display omitted
•We analyzed the effect of green growth and environmental tax on CO2 emissions.•We applied advanced panel data techniques.•Linear and non-linear term of green growth reduce CO2 emissions.•Environmental tax, renewable energy and human capital improve the environment.
Highly emissive semiconductor nanocrystals, or so‐called quantum dots (QDs) possess a variety of applications from displays and biology labeling, to quantum communication and modern security. Though ...ensembles of QDs have already shown very high photoluminescent quantum yields (PLQYs) and have been widely utilized in current optoelectronic products, QDs that exhibit high absorption cross‐section, high emission intensity, and, most important, nonblinking behavior at single‐dot level have long been desired and not yet realized at room temperature. In this work, infrared‐emissive MAPbI3‐based halide perovskite QDs is demonstrated. These QDs not only show a ≈100% PLQY at the ensemble level but also, surprisingly, at the single‐dot level, display an extra‐large absorption cross‐section up to 1.80 × 10−12 cm2 and non‐blinking single photon emission with a high single photon purity of 95.3%, a unique property that is extremely rare among all types of quantum emitters operated at room temperature. An in‐depth analysis indicates that neither trion formation nor band‐edge carrier trapping is observed in MAPbI3 QDs, resulting in the suppression of intensity blinking and lifetime blinking. Fluence‐dependent transient absorption measurements reveal that the coexistence of non‐blinking behavior and high single photon purity in these perovskite QDs results from a significant repulsive exciton‐exciton interaction, which suppresses the formation of biexciton, and thus greatly reduces photocharging. The robustness of these QDs is confirmed by their excellent stability under continuous 1 h electron irradiation in high‐resolution transmission electron microscope inspection. It is believed that these results mark an important milestone in realizing nonblinking single photon emission in semiconductor QDs.
MAPbI3 perovskite quantum dots demonstrate remarkable robustness under electron irradiation and photon excitation. They exhibit a high near‐infrared emission quantum yield of up to ≈100% and an unprecedented non‐blinking single photon emission at room temperature. These characteristics promise unique potential in the fields of quantum information and bioimaging.
Two-dimensional materials such as graphene are attractive materials for making smaller transistors because they are inherently nanoscale and can carry high currents. However, graphene has no band gap ...and the transistors are "leaky"; that is, they are hard to turn off. Related transition metal dichalcogenides (TMDCs) such as molybdenum sulfide have band gaps. Transistors based on these materials can have high ratios of "on" to "off" currents. However, it is often difficult to make a good voltage-biased (p-n) junction between different TMDC materials. Li et al. succeeded in making p-n heterojunctions between two of these materials, molybdenum sulfide and tungsten selenide. They did this not by stacking the layers, which make a weak junction, but by growing molybdenum sulfide on the edge of a triangle of tungsten selenide with an atomically sharp boundary Science, this issue p. 524 Two-dimensional transition metal dichalcogenides (TMDCs) such as molybdenum sulfide MoS2 and tungsten sulfide WSe2 have potential applications in electronics because they exhibit high on-off current ratios and distinctive electro-optical properties. Spatially connected TMDC lateral heterojunctions are key components for constructing monolayer p-n rectifying diodes, light-emitting diodes, photovoltaic devices, and bipolar junction transistors. However, such structures are not readily prepared via the layer-stacking techniques, and direct growth favors the thermodynamically preferred TMDC alloys. We report the two-step epitaxial growth of lateral WSe2-MoS2 heterojunction, where the edge of WSe2 induces the epitaxial MoS2 growth despite a large lattice mismatch. The epitaxial growth process offers a controllable method to obtain lateral heterojunction with an atomically sharp interface.
We present a complete and independent list of the dimension-nine operator basis in the Standard Model effective field theory by an automatic algorithm based on the amplitude-operator correspondence. ...A complete basis (Y-basis) is first constructed by enumerating the Young tableau of an auxiliary SU(N) group and the gauge groups, with the equation-of-motion and integration-by-part redundancies all removed. In the presence of repeated fields, another basis (P-basis) with explicit flavor symmetries among them is derived from the Y-basis, which further induces a basis of independent monomial operators through a systematic process called desymmetrization. Our form of operators has advantages over the traditional way of presenting operators constrained by flavor relations, in the simplicity of both eliminating flavor redundancies and identifying independent flavor-specified operators. We list the 90456 (560) operators for three (one) generations of fermions, all of which violate baryon number or lepton number conservation; among them we find new violation patterns as ΔB = 2 and ΔL = 3, which only appear at the dimensions d ≥ 9.
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