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The stability of luminescent materials is a key factor for the practical application in white light-emitting diodes (LEDs). Poor chemical stability of narrow-band green-emitting RbLi(Li3 SiO4 )2 :Eu2+ (RLSO:Eu2+ ) phosphor hinders their further commercialization even if they have excellent stability against thermal quenching. Herein, we propose an efficient protection scheme by combining the surface coating of amorphous Al2 O3 and hydrophobic modification by octadecyltrimethoxysilane (ODTMS) to construct the moisture-resistant dual-shelled RLSO:Eu2+ @Al2 O3 @ODTMS composite. The growth mechanisms of both the Al2 O3 inorganic layer and the silane organic layer on the phosphor surface are investigated. The results remarkably improve the water-stability of this narrow-band green emitter. The evaluation of the white LED by employing this composite as the green component demonstrates that RLSO:Eu2+ @Al2 O3 @ODTMS is a promising candidate for the high-performance display backlights, and this dual-shelled strategy provides an alternative method to improve the moisture-resistant property of humidity-sensitive phosphors.

The good bond between rebar and concrete is an essential prerequisite for the bearing force of reinforced concrete structures. In the simulation method, the concrete heterogeneity and rebar characteristics were taken into account. Considering frictional resistance and the mechanical interlocking between reinforcement and concrete, the paper established meso-scale separate interaction model which researches the nonlinear bonding damage behavior ribbed bar and concrete. Based on the good agreement between the simulation results and the experimental results, the advantages of the mesoscopic mechanical analysis method were discussed first, and the bond slip behavior and failure mechanism of the reinforced concrete interface were studied. Finally, the distribution characteristics of the bond stress of the bar was analyzed. Furthermore, based on the mesoscopic numerical analysis, the influences of the aggregate distribution, thickness of concrete cover, strength of concrete, steel bar diameter and height of rib on the bond failure behavior of reinforced concrete interface are discussed, and some regular knowledge is obtained.

In this study, MoS2-graphene-tourmaline (MoS2-GR-T) composite photocatalyst was successful synthesized via one-step hydrothermal method. Raman spectra revealed that graphene oxide was reduced to graphene. Scanning electron microscopy images showed that MoS2 was dispersed well on graphene. Transmission electron microscope images showed that MoS2 and tourmaline contacted well with graphene. Analysis of UV-visible diffuse reflectance spectra implied that the bandgap energies of MoS2, MoS2-T and MoS2-GR-T samples were 2.01 eV, 1.91 eV and 1.79 eV, respectively. The photocatalytic performances are evidenced under Xenon lamp irradiation utilizing Rhodamine B dye as the model compound. Compared with MoS2 and MoS2-GR, the MoS2-graphene-tourmaline (MoS2-GR-T) composites exhibited the excellent photocatalytic activity for the degradation about irradiating for 60 min were 93.9% under visible-light. The enhanced photocatalytic activity of MoS2-GR-T composite could be attributed to the exposed adsorption-photocatalytic active sties, the improved light adsorption ability and the promoted charge separation efficiency. The introduction of tourmaline reduced the band gap explored by analysis of UV-visible diffuse reflectance spectra. This work demonstrated that the charge efficiency of photocatalysts could be promoted by coupling both metal-free co-catalyst and polar mineral.

Pudendal nerve block (PNB) is one of the common anesthesia methods, which has been widely applied in postoperative analgesia of hemorrhoids in recent years. To analyze the effectiveness and safety of PNB on postoperative analgesia of hemorrhoids, we conducted a systematic review of 7 randomized controlled trials (RCT) searched from PubMed, Embase, Web of Science, the Cochrane Central Register of Controlled Trials (CENTRAL), the China Network Knowledge Infrastructure (CNKI), the Wan Fang Database and Chinese Biomedicine (CBM), which were published before 7th September, 2020, and involved a total of 560 participants. We evaluated the function of PNB in improving outcomes of postoperative analgesia of hemorrhoids. Visual analogue scale (VAS) scores on postoperative 6, 12, 24, 48 h and the first time of defecation were enhanced by the application of PNB. The incidence of urinary retention, the need for analgesics [odds ratio (OR), 0.11; 95% CI, 0.04-0.37; P=0.0003] and the incidence of side effects (OR, 0.12; 95% CI, 0.04-0.39; P=0.004) in patients receiving PNB were lower than those of controls. In addition, there was no significant difference in the incidence of bleeding between groups. PNB could effectively relieve postoperative pain of hemorrhoids and reduce complications without increasing the incidence of side effects. Our results still need to be confirmed by high-quality, multi-center clinical studies.

In this work, N-doped three-dimensional graphene aerogel with different weight of Ag particles (N-GA/Ag) was successfully prepared by a one-step solvothermal method. The characterization proved the successful doping of N and the weaken bonds between N atoms and Ag particles. The scanning electron microscopy images showed that the sizes of Ag particles were 10–50 nm at optimal load. Serving as water treated materials for 4-nitrophenol (4-NP), the N-GA/6Ag composite exhibited that its high catalytic reduction capacity in the presence of NaBH4 reached at 98% within 4 min and the bactericidal performance for E. coli could achieved 100% inactivation rate in 24 h. This work also calculated surface atomic densities of exposed main planes of Ag particles, which were relative to the catalytic performance. The catalytic activity of the {111} crystal planes was lower than that of {100} planes in Ag particles.

A facile method to fabricate reduced graphene oxide (rGO) and Fe3O4 based composites with enhanced microwave absorption property is prepared by adopting multi-layered structure. The optimal effective bandwidth (EB) reaches 8.4 GHz at 5.2 mm, and optimal reflection loss (RL) value achieves −72.7 dB at 4.5 mm. Comparing with the isotropic single-layered composites with no EB at the same condition, there is a distinct improvement of RL values and EB, demonstrating the positive effects of multi-layered structure on the microwave absorption. The highly improved performances mainly ascribe to the extra interfaces and better impedance match. This work remarkably improves the microwave absorption performance of rGO and Fe3O4 based material through structure adjustment. Besides, we establish an effective and facile path for various materials to enhance their microwave absorption properties by adopting multi-layered structure. The prepared composites can be applied in construction material for microwave absorption and military field for stealth.

To explore the nonlinear bond behaviour between ribbed bar and concrete, combined with the characteristics of concrete meso-structure and ribbed bar surface characteristics and considering frictional resistance and the mechanical interlocking between rebar and concrete, a meso-scale model is established. Based on the good agreement between the simulation results and experimental results, the failure mechanism of bond between rebar and concrete is discussed, and the distribution characteristics of bond stress of steel bar are analysed. Furthermore, based on the meso numerical analysis method, the influence of friction coefficient between rebar and concrete on the failure mode of concrete and bond stress-slip curve was discussed, and the proportion of friction component in bond strength is obtained.

To explore the nonlinear bond behavior between ribbed bar and concrete, considering frictional resistance and the mechanical interlocking between rebar and concrete as well as the surface characteristic of crescent ribbed bar, a 3D meso-scale modelling approach is established. Comparisons between the simulation and experimental results indicate that the meso-scale method can provide good predictions of the interface behavior between concrete and deformed steel bar under confinement conditions. The bond failure mechanism and the propagation of internal crack of specimen were clearly studied and revealed based on the 3D simulations. Moreover, the influences of concrete strength gradation, ratio of cover thickness to bar diameter as well as stirrup confinement on bond stress-slip behavior, concrete failure mode and rebar stress were explored. The simulation results indicate that the meso-scale modelling method can well describe the bond failure process at the steel bar/concrete interface. It is found that increasing the concrete strength can delay the internal crack of the specimen and may change the failure mode of the specimen from splitting failure to pull-out failure. As concrete strength increases, the bond strength increases linearly, whereas the peak slip decreases slightly. The shape of bond stress-slip curve and the concrete failure modes are closely associated with the lateral confinements such as concrete cover thickness and the stirrup confinement. When the cover thickness and the stirrup confinement index reach a certain value, the bond failure would no longer be affected. In addition, the strain of stirrups increases continuously, the bond stress provided by stirrups increases first and then decreases.

Corrosion of steel in concrete structures is one of the main causes of structural durability failure. In order to study the rust cracking behavior of the concrete protective layer, a three-dimensional meso-scale model of concrete was established. In the approach, the concrete was regarded as a three-phase composite composed of coarse aggregates, mortar matrix and the interfacial transition zones (ITZs). The non-uniform radial displacement method was used to characterize the mechanical effect of steel rust on the surrounding concretes. The cracking behavior of concrete cover caused by non-uniform corrosion of corner reinforcement was simulated based on the meso-scale method. The rust expansion pressures on the surrounding concretes due to non-uniform corrosion of corner rebar were explored. Moreover, the influences of steel bar diameter, cover thickness and corrosion distribution mode on the cracking of cover concrete were investigated. The simulation results indicate that the non-uniform rust pattern of the steel bar makes rust expansion pressure smaller than the uniform rust. The random distribution of aggregates has little effect on the cracking mode of the concrete protective layer. With the increase of the ratio of the thickness of concrete cover to the diameter of steel bar, the maximum rust expansion pressure of concrete increases. Bar diameter has a negligible influence on the cracking pattern of concrete.

Body: Power transformers and reactors are important devices in power transmission systems. But their cores and windings could produce vibration and acoustic noise by magnetostrictive effect, Maxwell electromagnetic stress and Lorentz force. Noise has become a bad environmental pollution source in some situations, and its vibration and noise reduction has become an urgent problem need to be solved. The shapes, materials, magnetostriction and joints forms of iron cores, the limitations of test, modeling, and experimental measurement of vibration and noise characteristic, are all the difficult reasons to analyze the vibration and acoustic noise of transformers and reactors. 1. The magnetostrictive modeling can be divided into two steps based on the magnetic field force and materials deformation, so the magnetic field force will be fed into the structural finite element with Maxwell electromagnetic force produced on the interface between the iron core and the air to calculate the deformation of the magnetic materials and to make the model more general and consistent. In order to fully verify the correctness of the model in the magnetostrictive analysis, and to ensure the simplicity of test and avoid unnecessary interference factors, the most simple magnetostriction tests will be carried out by using a single closed circle or rectangular electrical steel sheet, as shown in Fig. 1(a). The tests will measure the relationship between magnetostriction and magnetic field of different magnetic materials, different saturations, different sizes and different shapes. 2. The joint is a necessary form for the stacking of large transformer iron cores, and the main joint form is the step jiont at present. The introduction of the joints causes the magnetic force lines to flow through the different laminations and to make the local magnetic field complicated. From simple to complex process is adopted in this paper, and the verification is gradually complicated. Based on the study of a simple sheet with no joint showed in Fig. 1(a)and (e), a sheet with joint will be used to analyze the vibration and modeling calculation, as shown in Fig. 1(b). Maxwell electromagnetic force caused by the the joints and magnetostrictive force due to the magnetostriction of sheet are all actually included in the model. Later, further complicated two or more pieces of sheets are designed up and down on the joint of the simple circle or rectangular sheet, as shown in Fig. 1(c) and (d) to simulate the joints forms in the iron cores of transformers with the magnetic flux transition circulation though the joints. Meanwhile, the separation of the Maxwell electromagnetic force and the magnetostrictive force from the overall analysis can be worked out by using mathematical method, and the separated curve will be given in the end. 3. In order to improve the effect of vibration and acoustic noise deduction sharply, a novel structure design of iron core for power transformer is put forward, with the core and winding position interchange, compared to conventional power transformers, as shown in Fig. 2. Compared with traditional transformers, this structure has many advantages: firstly, the short magnetic circuit reduces the deformation caused by magnetostriction; secondly, the circular ring core does not have joints to avoid the vibration and acoustic noise caused by the joints; thirdly, the radial deformation of circular ring is greatly reduced; the last, the long cantilever structure that causes deformation in the traditional iron core can be eliminated. These advantages together will realize the new low vibration and low acoustic noise transformers. 4. The test prototype of power transformer with laminated core is processed in different stacking modes. The vibration acceleration and displacement of power transformer iron core are measured with high precision laser acceleration sensors, and the modal test is carried out by using Finite Element (FE) software. Based on the comparison between simulation and test data, the effect of vibration and noise reduction is analyzed and established to verify the novel iron core structure design of the power transformers, and to give further reference and guidance to the engineering applications.

Carbon nanotubes (CNTs) have been widely developed for electrochemical energy conversion and storage devices for replacement of high-cost Pt-based catalysts. In this paper, a simple and convenient method is developed for improving the catalytic activity of CNTs in a controlled way. By simple heating treatment in the air, the multi-walled carbon nanotubes (MWCNTs) change with special morphologies, compositions and abundant defects (denoted as h-CNT). Those defects significantly improve the electrocatalytic performances for oxygen reduction reaction (ORR) which proceeds in a nearly four-electron pathway. The heating conditions have important effects on the structures and defect properties of h-CNTs which show a positive correlation between the defect levels and ORR performances. The small amounts of iron residues originated from nanotube growth and nitrogen doping during heating treatment also contribute to some catalytic activity. The inner walls of h-CNT remain intact during heating treatment and provide sufficient conductivity which facilitates charge transport during ORR. The h-CNT electrocatalyst shows better methanol tolerance and long-term durability than commercial Pt/C in alkaline media which makes it an alternative cathode catalyst in fuel cells.

An effective soft template strategy is used for the in situ fabrication of molybdenum-doped mesoporous carbon/graphene composites. As noble-metal-free electrocatalysts for the oxygen reduction reaction in alkaline media, they exhibit excellent catalytic activity through an efficient four-electron-dominant reaction pathway. Observably, compared with commercial Pt/C, they have superior methanol tolerance and long-term stability.

A non-mydriasis optical system for binocular fundus camera has been designed in this paper. It can capture two images of the same fundus retinal region from different angles at the same time, and can be used to achieve three-dimensional reconstruction of fundus. It is composed of imaging system and illumination system. In imaging system, Gullstrand Le Grand eye model is used to simulate normal human eye, and Schematic eye model is used to test the influence of ametropia in human eye on imaging quality. Annular aperture and black dot board are added into illumination system, so that the illumination system can eliminate stray light produced by corneal-reflected light and omentoscopic lens. Simulation results show that MTF of each visual field at the cut-off frequency of 90lp/mm is greater than 0.2, system distortion value is -2.7%, field curvature is less than 0.1 mm, radius of Airy disc is 3.25um. This system has a strong ability of chromatic aberration correction and focusing, and can image clearly for human fundus in which the range of diopters is from -10 D to +6 D(1 D = 1 m

Carbon coated MnO@Mn(3)N(2) core-shell composites (MnO@Mn(3)N(2)/C) were synthesized in a simple approach by calcining MnO(2) nanowires with urea at 800 °C under an ammonia atmosphere. Urea derived carbon nanosheets were partially coated on pure phase MnO@Mn(3)N(2) core-shell composites. Electrochemical measurements reveal that the MnO@Mn(3)N(2)/C displayed high discharge capacities, an excellent high-rate capability and an enhanced cycling performance.

A method for computer-generated hologram (CGH) compression and transmission using a quantum back-propagation neural network (QBPNN) is proposed, with the Fresnel transform technique adopted for image reconstruction of the compressed and transmitted CGH. Experiments of simulation were conducted to compare the reconstructed images from CGHs processed using a QBPNN with those processed using a back-propagation neural network (BPNN) at the optimal learning coefficients. The experimental results show that the method using a QBPNN could produce reconstructed images with a better quality than those obtained using a BPNN despite the use of fewer learning iterations at the same compression ratio.

A facile and straightforward approach is developed for the construction of graphene-based hollow spheres. An electron rich sodium-ammonia solution is used to effectively restore the π-conjugation of graphene. The hollow spheres exhibit excellent electrocatalytic activity towards oxygen reduction without catalyst deactivation.