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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.

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]