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Determining the correlation between the size of a single quantum dot (QD) and its photoluminescence (PL) properties is a challenging task. In the study, we determine the size of each QD by measuring its absorption cross section, which allows for accurate investigation of size-dependent PL blinking mechanisms and volume scaling of the biexciton Auger recombination at the single-particle level. A significant correlation between the blinking mechanism and QD size is observed under low excitation conditions. When the QD size is smaller than their Bohr diameter, single CsPbI3 perovskite QDs tend to exhibit BC-blinking, whereas they tend to exhibit Auger-blinking when the QD size exceeds their Bohr diameter. In addition, by extracting bright-state photons from the PL intensity trajectories, the effects of QD charging and surface defects on the biexcitons are effectively reduced. This allows for a more accurate measurement of the volume scaling of biexciton Auger recombination in weakly confined CsPbI3 perovskite QDs at the single-dot level, revealing a superlinear volume scaling (τXX,Auger ∝ σ1.96). [ABSTRACT FROM AUTHOR]

Poly-aluminium chloride (PAC) sludge is a waste product created during drinking water treatment, usually generated in large quantities and typically landfilled. More attention must be directed to environmental-friendly management and economically sustainable of Al-based sludge. In this work, a low-cost and environmental-friendly adsorbent prepared by sodium alginate coated PAC sludge (SPS) was investigated for fluoride removal. Basic preparing parameters including heating temperature (200–800°C), sodium alginate concentration (0.5–5 wt%), particle size (1–2 mm, 2–3 mm, 3–4 mm) and operating parameters including dosage (1–14 g/L), solution pH (4–11), temperature (10–35°C), co-existing anions (NO3−, Cl−, SO42-, PO43-) were examined to evaluate the optimum defluoridation capacity. The prepared SPS adsorbents reached a high removal efficiency of 95.6% with initial fluoride concentration of 10 mg/L, dose of 8 g/L, contact time of 24 h, pH value of 7 and temperature of 10°C. The kinetic study indicated that fluoride adsorption followed the pseudo-second-order kinetics well (R2 = 0.9942), and adsorption isotherms can be well described by Freundlich model (R2 = 0.9952). Thermodynamic studies showed the fluoride adsorption was spontaneous and exothermic. The elements and functional groups of SPS adsorbents were analysed by using EDS and FTIR, respectively. The adsorption mechanism involved physisorption, ligand-exchange and electrostatic attraction. According to N2 adsorption–desorption isotherm, the SPS was mesoporous material which facilitated the adsorption of fluoride ions. Also, aluminium presented in form of Al-OH in SPS adsorbents had significant contribution in fluoride adsorption. The concentration of the residual aluminium ions was 4.48 × 10−3 mg/L which is lower than the China Drinking Water Standard. The encouraging results of this preliminary study indicated that SPS is an environmental-friendly and cost-effective treatment option for groundwater with fluoride pollution. [ABSTRACT FROM AUTHOR]

From birth to adulthood, the mammalian heart grows primarily through increasing cardiomyocyte (CM) size, which is known as maturational hypertrophic growth. The Hippo-YAP signaling pathway is well known for regulating heart development and regeneration, but its roles in CM maturational hypertrophy have not been clearly addressed. Vestigial-like 4 (VGLL4) is a crucial component of the Hippo-YAP pathway, and it functions as a suppressor of YAP/TAZ, the terminal transcriptional effectors of this signaling pathway. To develop an in vitro model for studying CM maturational hypertrophy, we compared the biological effects of T3 (triiodothyronine), Dex (dexamethasone), and T3/Dex in cultured neonatal rat ventricular myocytes (NRVMs). The T3/Dex combination treatment stimulated greater maturational hypertrophy than either the T3 or Dex single treatment. Using T3/Dex treatment of NRVMs as an in vitro model, we found that activation of VGLL4 suppressed CM maturational hypertrophy. In the postnatal heart, activation of VGLL4 suppressed heart growth, impaired heart function, and decreased CM size. On the molecular level, activation of VGLL4 inhibited the PI3K-AKT pathway, and disrupting VGLL4 and TEAD interaction abolished this inhibition. In conclusion, our data suggest that VGLL4 suppresses CM maturational hypertrophy by inhibiting the YAP/TAZ-TEAD complex and its downstream activation of the PI3K-AKT pathway. [ABSTRACT FROM AUTHOR]

Anaerobic ammonia oxidation process has the advantages of energy and cost reduction, therefore, it has been considered as one of the main alternatives to conventional biological denitrification process in recent years. Biochar has been applied in the anammox process for nitrogen removal efficiency. But, due to its extracellular electron transfer capacity and abundance of redox-specific functional groups, which served as extracellular electron acceptor to anaerobically oxidize NH4+ is still controversy. In this study, the anaerobic ammonia oxidation was investigated when biochar was used as electron acceptor in the wastewater. According to the optimal process variables determined in the batch tests, when the influent NH4+-N concentration in the anaerobic ammonia oxidation reaction was 30–50 mg/L and the biochar dosing was at 10 g/L, it showed some promotion in the long-term experiments. The anaerobic ammonia oxidation process with biochar as the electron acceptor reached more than 60% NH4+-N removal efficiency in the system, and the ΔNO3--N/ΔNH4+-N ratio reached 0.19 which tended to the theoretical value. After 20 days, the voltage in the system keeps fluctuating about 4 mV, indicated that the functional bacteria using biochar as the electron acceptor gradually dominated the system. In addition, the abundance of norank_f__norank_o__SBR1031 in the Chloroflexi phylum has increased significantly at 29.92%, while the abundance of the major genus Candidatus_Kuenenia in AnAOB has decreased slightly at 11.47%. [ABSTRACT FROM AUTHOR]

Acclimatization of short-cut denitrifying polyphosphate accumulating organisms (SDPAOs), metabolic mechanism, and operating parameters were analyzed to investigate the performance of the anaerobic/anoxic sequencing batch reactor (A2SBR) process. The high-throughput sequencing technology was employed to explore the microbial community structures of activated sludge systems. The experimental results illustrated that SDPAOs were successfully enriched with three-phase inoculation for 36 days. The removal rates of TP and NO2−-N were 93.22% and 91.36%, respectively, under the optimal parameters of a pH of 7.5, an SRT of 26 days, a temperature of 24 ℃ and a COD of 200.00 mg·L−1 using acetate as the carbon source. In the anaerobic stage, 82.20% external carbon source was converted into 88.78 mg·g−1 PHB, and the removal rate of NO2−-N in the anoxic stage was characterized by ΔNO2−-N/ΔPHB, anoxic ΔP/ΔPHBeffective was 0.289, which was higher than anaerobic ΔP/ΔCODeffective of 0.203. Ignavibacterium and Povalibacter with significant phosphorus removal ability were the dominant bacterial genera. The nitrogen and phosphorus removal could be realized simultaneously in an anaerobic/anoxic sequencing batch reactor. Therefore, this study provided an important understanding of the removal of nitrogen and phosphorus from low-carbon nitrogen wastewater. [ABSTRACT FROM AUTHOR]

Germanium diselenide (GeSe2) has recently emerged as a promising material for high‐performance optoelectronic devices due to its high absorption coefficient, wide direct bandgap, and anisotropic electronic properties. For the future applications, it is necessary to understand the dynamic evolution of carriers with ultrafast response. In this work, the transient absorption spectroscopy measurements are performed to study the anisotropic dynamic evolution of GeSe2 under the polarized photoexcitation. It is find that the dynamics exhibit linear dichroism and show a significant Auger recombination process when the photoexcitation is perpendicular to the b‐axis of GeSe2. Using first‐principle and transition dipole moment calculations, it is confirmed that the more carrier localization at Γ point along the Γ‐X (perpendicular to the b‐axis) and increase the Auger recombination. In addition, the Auger recombination coefficient ≈ 1.1×10−31 cm6 s−1 is determined and demonstrated that the defect‐assisted indirect Auger recombination plays a key role in the carrier relaxation process. Through time‐resolved transient absorption spectra, it is further revealed that the ultrafast dynamical evolution of excited state absorption peaks under polarized photoexcitation. These results have implications for improving the quantum efficiency of high‐field polarization‐sensitive optoelectronics. [ABSTRACT FROM AUTHOR]

Pharmaceutical residues can cause serious water pollution problems, harm human health and destroy the ecological balance. FeSO4·7H2O optimisation of the earthed atomising corona discharge (Fe-EACD) process was used to dispose of pharmaceutical wastewater in this research. Experiments were analyzed by VI characteristic curves to optimise the electrode distance (20–50 mm) and wire electrode diameter (0.3–0.5 mm). The effects of discharging voltage (7–12 kV), time (0–54 min) and FeSO4 dosage (0.2–1.2 g/L) were investigated using the response surface methodology (RSM). According to the RSM results, the best removal efficiency of COD (89.6%) was detected at the optimal discharging voltage of 12 kV, time of 42 min and Fe2+ concentration of 0.4 g/L. The Fe-EACD process could work efficiently with BOD5/COD ratio moving to 0.49 in an acid environment. The kinetic analysis and mechanism study suggested that the Fe-EACD process was demonstrated well by the pseudo-first-order based on the correlation coefficient (R2). Active •OH producing in the EACD process is responsible for the COD removal and the FeSO4·7H2O as a catalyst can promote the formation of active hydroxyl. In other words, EACD with Fe2+ optimisation was an economic and feasible process for pharmaceutical wastewater treatment. [ABSTRACT FROM AUTHOR]

BackgroundThe protection of secondary neutrons in the complex secondary radiation of the 100~250 MeV proton therapy room has always been the focus of shielding design. Currently, iron plates embedded in concrete are often used to reduce neutron transmission, but this will cause significant neutron reflection (toward the patient). And neutrons have a high radiation weighting factor which may cause harmful effects on patients.PurposeThe study aims to investigate the reflection distribution of secondary neutrons in the proton therapy room and its impact on patients.MethodsFirst of all, a simple model of the proton therapy room was established, and Monte Carlo program FLUKA was used to calculate the effects of the secondary neutron reflection from different directions and at different embedding positions of the iron shield in the 245 MeV proton therapy room. Then, under the three irradiation modes of AP (Antero-posterior), PA (Posterior-anterior) and LAT (Lateral), the effective dose of the patient was calculated according to the energy of the reflected neutrons reaching the position of the patient whilst the neutron external radiation dose conversion coefficient given in report of ICPR (International Commission on Radiological Protection) Publication 116 was used.ResultsThe simulation results show that the main shielding wall contributes more than 95% to the reflection distribution of the secondary neutrons in the treatment room. The radiation dose level outside the treatment room is the lowest when the embedded depth of the iron plate in the wall is 0 (the iron plate is exposed in the room), but highest effective dose rates caused by reflected neutrons are 1.99 μSv‧s-1, 1.37 μSv‧s-1 and 1.00 μSv‧s-1, respectively, under the three irradiation modes of AP, PA and LAT. With the increase of embedding depth of iron plate, the effective dose rate of reflected neutron decreased gradually, but the decreasing trend becomes slower and slower.ConclusionsThe structure of the main shielding wall of the treatment room and the embedded position of the iron plate have a significant impact on the reflected secondary neutron energy spectrum and the patient's radiation health. This feature needs to be considered in the shielding design of the proton therapy room.

Supersymmetry (SUSY) laser array with superpartner structure can suppress excess modes to achieve high‐intensity and high‐coherent radiation. Compared with complex superpartner, using parity time (PT) symmetry broken to manipulate SUSY laser arrays is a more flexible approach. Herein, based on ultrathin perovskite single crystal, a SUSY laser array is constructed without superpartner, but with auxiliary gain–loss structure. PT symmetry broken with high‐order exceptional point (EP) is realized in the visible spectral range. It intrinsically avoids superpartner field mismatch and improves side mode suppression ratio 8.8–12 dB for single‐mode lasing. Furthermore, variations in EP‐order enable the transition from single‐mode to dual‐mode or tri‐mode radiation and retain amplified radiation characteristics. In addition, these SUSY laser arrays with the high‐order EP have the potential to be small‐volume optical sensor devices. The new design combining SUSY and PT symmetry broken presents its potential in micro‐nanophotonic devices with the benefit of small size, flexibility in spectral control, expandability, simplicity, and multifunctionality feature. [ABSTRACT FROM AUTHOR]

This study proposed an AO-SBR (Anaerobic Aerobic Sequencing Batch Reactor) combined with iron-carbon micro-electrolysis (ICME) particles system for sewage treatment at low temperature and explored the dephosphorisation mechanism and microbial community structure. The experimental results illustrated that ICME particles contributed to phosphorus removal, metabolic mechanism of poly-phosphorus accumulating organism (PAO) and microbial community structure in the AO-SBR system. The optimal treatment effect was achieved under the conditions of pH 7, DO 3.0 mg/L and particle dosage of 2.6 g Fe-C/g MLSS, and the removal rates of COD, TP, NH4+-N and TN reached 80.56%, 91.46%, 69.42% and 57.57%. The proportion of phosphorus accumulating organisms (PAOs) increased from 4.54% in the SBR system to 10.89% in the ICME-SBR system at 10°C. Additionally, the metabolic rate of PAOs was promoted, and the activities of DHA and ETS both reached the maximum value of 13.34 and 102.88 μg·mg−1VSS·h−1. These results suggest that the ICME particles could improve the performance of activated sludge under low-temperature conditions. This technology provides a new way for upgrading the performance of sewage treatment in the cold area. [ABSTRACT FROM AUTHOR]

Materials with multiple nonlinear-optical responses have been investigated widely in recent years. Here, we report a hybrid system with both giant multiphoton absorption (MPA) and efficient third harmonic generation (THG) excited by near-infrared femtosecond laser pulses. The hybrid material consists of both CsPbBr3 quantum dots and metal–organic framework microparticles. The two-, three-, four-, and five-photon absorption cross-sections of the hybrid material are three orders of magnitude greater than those of CsPbBr3 micro-crystals. The effective χ(3) values are three orders of magnitude greater than those of α-quartz. Our findings demonstrate a new avenue to realize photo-stable, high-order MPA, and THG in microparticles synthesized using a cost-effective method. [ABSTRACT FROM AUTHOR]

Low‐symmetry 2D materials have received tremendous attention due to their anisotropic optical, electrical, and mechanical properties and viable candidates for polarized photodetectors, anisotropic field‐effect transistors, and nanomechanical systems. Here, an interesting low‐symmetry 2D material (GaPS4) is reported and its in‐plane anisotropic structure, optical, and mechanical properties are investigated. The polarized Raman and absorption spectra prove the sensitivity of GaPS4 to crystalline orientation and linear dichroism. The experimental results of azimuth‐dependent reflectance difference microscopy can visually reveal the in‐plane optical anisotropy of GaPS4 flakes. Moreover, an interesting pressurized bubble method is designed to verify the anisotropic mechanical properties of GaPS4 flakes and saddle‐like bubble devices of GaPS4 are successfully fabricated. The saddle‐like bubble devices exhibit visual anisotropic deflection variations along the orthogonal direction. Kelvin probe force microscope enables the direct identifying of the surface potential distribution of bubble devices under strain. Interest would be excited in the anisotropic optical and mechanical properties and relevant device applications of low‐symmetry 2D materials. [ABSTRACT FROM AUTHOR]

The trivalent outer shell of boron renders this element electron‐poor but chemically rich, exhibiting more than one dozen allotropes. Its 2D polymorph has been recently synthesized on metal substrates under ultrahigh vacuum and has attracted intense interest. However, probing its properties ex situ has been challenging due to the quality degradation—surface oxidation—that occurs upon exposure to ambient environments. Herein, this surface chemistry is investigated in regard to the air stability of ultrathin boron flakes on metals prepared by atmospheric‐pressure chemical vapor deposition. The characteristic Volmer–Weber growth is recognized by the stacking of polygon‐shaped, thin flakes as isolated islands. Significantly, the metal‐catalyzed, ultrafast gasification of boron flakes at room temperature, exemplified by the complete, spontaneous vanishment of 200 nm‐thick boron islands in 3 h is observed. A two‐step mechanism, first oxygen‐involved surface oxidation and then subsequent reactions with water forming a highly volatile boric acid layer, is unambiguously revealed by combined surface characterizations. The catalysis by metal substrates, corroborated by theoretical calculations, is attributed as the crucial cause of the unprecedented gasification. The concept of oxygen‐free growth is thereby proposed for air‐sensitive material growth by introducing in situ oxygen scavengers. These findings significantly expand the fundamental understanding of the surface chemistry of boron and pave the way for the chemical vapor deposition growth of hydrophobic materials. [ABSTRACT FROM AUTHOR]

Nano zirconia/zeolite molecular sieve was synthesized by using sodium alginate and FeCl3 as cross-linking agents to produce a bead type adsorbent (Fe@nano ZrO2/ZMS) with improved usability and applicability for nitrate removal. Optimal preparation parameters via mass ratio of nano ZrO2 to ZMS and FeCl3 concentration were determined by batch tests. Best adsorption performance was determined by varying operational adsorption parameters, such as dose (1.0–8.0 g/L), solution pH (3.0–10.0) and co-existing ions (K+, Mg2+, Ca2+, NH4+, Cl−, F−, SO42−, HCO3−). The effect of contact time (10–100 min) and the kinetics of adsorption process were studied using pseudo-first-order, pseudo-second-order, Power and Elovich models starting from different initial concentrations of NO3– ions (20, 30, 50 mg/L, respectively). The Langmuir, Freundlich, Sips and Temkin adsorption models were utilized to describe the equilibrium isotherms. Influence of solution temperature (10–40 °C) and thermodynamics results indicated adsorption was an exothermic and spontaneous process. Maximum removal efficiency of 79.8% occurred at 10 °C which was in line with the actual groundwater temperature. The structural properties were tested by SEM, BET, BJH and N2 adsorption–desorption isotherm. Adsorption mechanism of elements and functional groups on Fe@nano ZrO2/ZMS were studied by EDS, XRD and FTIR. The proposed adsorption mechanism included mostly hydrogen bonding, electrostatic attractions, and ion exchange. After 5 times repeated regeneration by 0.5 mol/L NaHCO3 solution, the beads still showed higher nitrate removal ability. The results showed that Fe@nano ZrO2/ZMS beads can be considered a potentially efficient adsorbent for the removal of nitrate ions from water. [ABSTRACT FROM AUTHOR]