环氧灌浆材料增韧增渗改性研究进展

环氧灌浆材料已被广泛用于基建工程中混凝土结构的防渗堵漏和加固补强,但自身存在的脆性大、环境扰动适应性差、对微细裂纹渗透能力偏弱等缺陷,成为当下限制其深入推广的瓶颈之一。文中概述了近年来环氧灌浆料增韧、增渗的最新进展,重点关注了稀释剂、增韧聚合物、无机粒子与浆液间的物理共混,以及有机小分子、聚合物改性等方式对材料韧性、渗透性的优化效果、作用机理等,并就当前研究中的主要问题与挑战进行了探讨。

Laparoscopic vs open extended right hemicolectomy for colon cancer

AIM:To evaluate the feasibility,safety,and oncologic outcomes of laparoscopic extended right hemicolectomy(LERH)for colon cancer.METHODS:Since its establishment in 2009,the Southern Chinese Laparoscopic Colorectal Surgical Study(SCLCSS)group has been dedicated to promoting patients’quality of life through minimally invasive surgery.The multicenter database was launched by combining existing datasets from members of the SCLCSS group.The study enrolled 220 consecutive patients who were recorded in the multicenter retrospective database and underwent either LERH(n=119)or open extended right hemicolectomy(OERH)(n=101)for colon cancer.Clinical characteristics,surgical outcomes,and oncologic outcomes were compared between the two groups.RESULTS:There were no significant differences in terms of age,gender,body mass index(BMI),history of previous abdominal surgery,tumor location,and tumor stage between the two groups.The blood loss was lower in the LERH group than in the OERH group[100(100-200)mL vs 150(100-200)mL,P<0.0001].The LERH group was associated with earlier first flatus(2.7±1.0 d vs 3.2±0.9 d,P<0.0001)and resumption of liquid diet(3.6±1.0 d vs 4.2±1.0 d,P<0.0001)compared to the OERH group.The postoperative hospital stay was significantly shorter in the LERH group(11.4±4.7 d vs 12.8±5.6 d,P=0.009)than in the OERH group.The complication rate was 11.8%and17.6%in the LERH and OERH groups,respectively(P=0.215).Both 3-year overall survival[LERH(92.0%)vs OERH(84.4%),P=0.209]and 3-year disease-free survival[LERH(84.6%)vs OERH(76.6%),P=0.191]were comparable between the two groups.CONCLUSION:LERH with D3 lymphadenectomy for colon cancer is a technically feasible and safe procedure,yielding comparable short-term oncologic outcomes to those of open surgery.

X-ray focusing using an x-ray lens composed of multi-square polycapillary slices

A new type of x-ray lens composed of multi-square polycapillary slices(ASPXRL)used in focusing parallel x-ray beam was presented in this paper.Compared with conventional x-ray polycapillary lens,ASPXRL can provide smaller and brighter focus.The effects of the manufacturing imperfections on focusing quality of ASPXRL were evaluated with the values of transmission efficiency and discussed.It is suggested that ASPXRL has application prospects as a condenser lens for x-ray microscopy and flux collectors for x-ray analytical instruments.

Incorporation sodium ions into monodisperse lead-free double perovskite Cs_(2)AgBiCl_(6) nanocrystals to improve optical properties

Lead-free double perovskite nanocrystals(NCs)have emerged as a promising candidate in the optical field,owing to their non-toxic,good moist heat and chemical stability.However,their poor optical properties limited their application.To improve the optical properties of lead-free double perovskite NCs,metal ion doping or alloying had been suggested as a promising strategy.Here,we prepared monodisperse,uniformly sized,cubic morphology of Cs_(2)AgBiCl_(6)NCs with different Na^(+)incorporation amounts via a simple hot-injection method.The Na^(+)incorporation broke the parity-forbidden transition by reducing the inversion symmetry of the electron wave function at the Ag site,which changed the parity of the self-trapped exciton wave function and thus allowed radiative recombination.As a result,the photoluminescence quantum yield(PLQY)of Na^(+)-alloyed Cs_(2)AgBiCl_(6)NCs(12.1%)was higher than that of Cs_(2)AgBiCl_(6)NCs(2.4%),and the exciton lifetime of Na^(+)-alloyed Cs_(2)AgBiCl_(6)NCs increased to 36.98 ns from 17.58 ns for Cs_(2)AgBiCl_(6)NCs.By adjusting the amount of Na^(+)incorporation,the band gap of Cs_(2)AgBiCl_(6)NCs can be significantly tuned from~2.90 eV to~3.50 eV.Furthermore,the temperature-dependent photoluminescence spectra indicated that the Na^(+)-alloyed Cs_(2)AgBiCl_(6)NCs possessed higher longitudinal optical phonon energy and exciton binding energy compared to Cs_(2)AgBiCl_(6)NCs.This suggested that there were strong exciton-phonon interactions during exciton recombination,a reduced probability of non-radiative processes,and excellent thermal stability.It offers a promising strategy for improving the optical properties of lead-free double perovskite NCs,and have the potential to replace traditional lead halide perovskite NCs in future optoelectronic applications.

CATase-immobilized hydrogel platform molded by photo-enzyme coupling polymerization for effectively preventing postoperative abdominal adhesion

Redox homeostasis,which is regulated by enzymes acting as regulatory valves,is crucial for maintaining the proper functioning of biomolecules and a stable microenvironment for physiological processes by modulating the homeostasis of reactive oxygen species(ROS).Antioxidant enzymes in biocatalysis are used in the prevention or treatment of oxidative stress-related disease by counteracting the harmful effects of ROS.However,designing a system that can efficiently immobilize antioxidant enzymes with high catalytic activity and stability is still challenging.Bioinspired by photo-biocatalysis,a novel and effective catalase(CATase)-immobilized hydrogel platform has been developed by the proposed photo-enzymatic coupled radical polymerization strategy of the visible light coupling with the porphyrin-centered CATase.The higher catalytic stability and activity can therefore be achieved due to the preferential polymerization of CATase-immobilized hydrogel platform with a favorable three-dimensional network of enhanced coupling efficacy between light and enzymes.The mechanisms of free radical-initiated polymerization as well as the antioxidant cycle in the photo-CATase coupling system have been explored.Intriguingly,the CATase-immobilized hydrogel platform affords an unprecedented antioxidant ability to scavenge ROS and provide an effective cellular protection mechanism against external oxidative stress.Additionally,the CATase-immobilized hydrogel platform can effectively prevent peritoneal adhesion by reducing the expression of inflammatory cytokines.Therefore,the novel CATase-immobilized hydrogel platform is a potential candidate for physical barriers that effectively prevent postoperative adhesion formation,offering a new anti-adhesion strategy for clinical applications.

Modulating the photoelectrons of g-C3N4 via coupling MgTi2O5 as appropriate platform for visible-light-driven photocatalytic solar energy conversion

Graphitic carbon nitride (g-C3N4) has become an attractive visible-light-responsive photocatalyst because of its semiconductor polymer compositions and easy-modulated band structure. However, the bulk g-C3N4 photocatalyst has the low separation efficiency of photogenerated carriers and unsatisfied surface catalytic performance, which leads to poor photocatalytic performance. As for this, MgTi2O5 with high chemical stability, wide band gap and negative conduction band was used as a suitable platform for coupling with g-C3N4 to enhance charge separation and promoted the photoactivity. Different from common approaches, here, we propose an innovative method to construct g-C3N4/MgTi2O5 nanocomposites featuring “0 + 1 >1" magnification effect to improve g-C3N4 photocatalytic performance under visible light irradiation. Additionally, compositing metal oxides of MgTi2O5 with g-C3N4 has proven to be a proper strategy to accelerate surface catalytic reactions in g-C3N4, and the photoinduced carriers were modulated to maintain thermodynamic equilibrium, which convincingly promotes the photocatalytic activity. The photocatalytic performance of the nanocomposites was measured by hydrogen production and CO2 reduction under visible light. The developed g-C3N4/MgTi2O5 nanocomposites with a 5 wt.% MgTi2O5 exhibits the highest H2 and CO yield under visible light and excellent stability compare to the other MgTi2O5 contents in composites. According to surface photo-voltage spectra, electrochemical CO2 reduction, photoluminescence, etc. The superior performance can be related to an enhanced electron lifetime, the promoted charge transfer and the increased electronic separation property of g-C3N4. Our work provides an approach to overcome the defect of pure g-C3N4, which accesses to composite with the second component matched well.

Confinement and antenna effect for ultrasmall Y_(2)O_(3):Eu^(3+) nanocrystals supported by MOF with enhanced near-UV light absorption thereby enhanced luminescence and excellently multifunctional applications

A novel host-guest luminous system with enhanced near-UV light absorption thereby enhanced luminescence are designed based on the synergism of quantum confinement,spatial confinement,and antenna effect,where ultrasmall Y_(2)O_(3):Eu^(3+)nanocrystals are fixed inside MOF(Eu/Y-BTC)as supporting structure.The Eu/Y-BTC not only limits the size and leads to lattice distortion of Y_(2)O_(3):Eu^(3+)nanocrystals and controls the distance between nanocrystals,but also promotes the light absorption and emission.The significantly red-shifted and broadened charge transfer band of Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)leads to the excellent applications of Y_(2)O_(3):Eu^(3+)in white light-emitting diodes(LEDs).Our results show that white light with superior color quality(CRI>90)and extremely high luminous efficacy(an LER of 335 lm/W)could be achieved using Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)as red phosphor.The Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)also improves the photoelectric performance of dye-sensitized solar cells(DSSCs),not only because Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)has a large specific surface area and the adsorption amount of the dye is increased,but also because the valence band position of Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)is 2.41 eV,which can provide an additional energy level between the TiO2 and dye,promoting electron transfer.For these advantageous features,the multifunctional Y_(2)O_(3):Eu^(3+)/(Eu/Y-BTC)composite product will open new avenues in white LEDs and DSSCs.

Interface flux reconstruction method based on optimized weight essentially non-oscillatory scheme

Aimed at the computational aeroacoustics multi-scale problem of complex configurations discretized with multi-size mesh, the flux reconstruction method based on modified Weight Essentially Non-Oscillatory（WENO） scheme is proposed at the interfaces of multi-block grids.With the idea of Dispersion-Relation-Preserving（DRP） scheme, different weight coefficients are obtained by optimization, so that it is in WENO schemes with various characteristics of dispersion and dissipation. On the basis, hybrid flux vector splitting method is utilized to intelligently judge the amplitude of the gap between grid interfaces. After the simulation and analysis of 1D convection equation with different initial conditions, modified WENO scheme is proved to be able to independently distinguish the gap amplitude and generate corresponding dissipation according to the grid resolution. Using the idea of flux reconstruction at grid interfaces, modified WENO scheme with increasing dissipation is applied at grid points, while DRP scheme with low dispersion and dissipation is applied at the inner part of grids. Moreover, Gauss impulse spread and periodic point sound source flow among three cylinders with multi-scale grids are carried out. The results show that the flux reconstruction method at grid interfaces is capable of dealing with Computational Aero Acoustics（CAA） multi-scale problems.

Electrospinning Janus Type CoO_(x)/C Nanofibers as Electrocatalysts for Oxygen Reduction Reaction

Nanofibers with unique structures and multiple components have attracted more and more attention,which could combine multi-functions in one entity.Janus-type biphasic nanofibers with unique structure can be quickly obtained by electrospinning technology.We produced CoO_(x)/C nanofibers with Janus structure by self-made side-by-side electrospinning spinneret,combined with electrospinning technology and heat treatment.CoO_(x)/C nanofibers had a large amount of graphitic carbon distributed on one half of the Janus nanofiber,and CoO_(x)/C nanoparticles were embedded in the other half of the Janus nanofiber and distributed uniformly.CoO_(x)/C acted as ORR catalysis,and graphitic carbon,pridinc-N and CoO_(x) in CoO_(x)/C had a synergistic effect on their catalytic activity.The results confirmed that CoO_(x)/C was dominated by four-electron pathway under alkaline conditions,and the Tafel slope was lower than that of commercial Pt/C catalysts.The preparation method of this work is simple and easy,the structure is controllable,and the composition is adjustable,which provides a feasible way for preparing Janus structure nanofibers with different functions.

A thermodynamic potential for barium zirconate titanate solid solutions

Barium zirconate titanate[Ba(ZrxTi_(1−x))O_(3)]solid solutions are promising lead-free ferroelectric materials that have received substantial interest.Thermodynamic analysis based on phenomenological Landau–Devonshire theory is a powerful method for theoretical investigation of ferroelectric materials,but cannot be applied to Ba(ZrxTi1−x)O3 because there is no thermodynamic potential.In this paper,a thermodynamic potential for Ba(ZrxTi_(1−x))O_(3)(0≤x≤0.3)solid solutions is constructed,and then a thermodynamic analysis carried out.The results accurately reproduce known phase structures and their transition temperatures,with good agreement with experimentally measured polarization,dielectric,and piezoelectric constants.It is found that Ba(ZrxTi_(1−x))O_(3) solid solutions at room temperature have three phase boundaries,including a tetragonal–orthorhombic phase boundary at x=0.013,an orthorhombic–rhombohedral phase boundary at x=0.0798,and a rhombohedral–paraelectric phase boundary at x=0.2135.The results also indicate that the chemical composition-induced ferroelectric–paraelectric phase boundary has superior electromechanical properties,suggesting a new way to enhance electromechanical coupling in Ba(ZrxTi_(1−x))O_(3) solid solutions.

One-dimension carbon self-doping g-C3N4 nanotubes： Synthesis and application in dye-sensitized solar cells

One-dimensional carbon self-doping g-C3N4 nanotubes （CNT） with abundant communicating pores were synthesized via thermal polymerization of saturated or supersaturated urea inside the framework of a melamine sponge for the first time. A - 16% improvement in photoelectric conversion efficiency （η） is observed for the devices fabricated with a binary hybrid composite of the obtained CNT and TiO2 compared to pure TiO2 device. The result of EIS analysis reveals that the interfacial resistance of the TiO2-dye｜ I3^-/I- electrolyte interface of TiO2-CNT composite cell is much lower than that of pure TiO2 cell. In addition, the TiOa-CNT composite cell exhibits longer electron recombination time, shorter electron transport time, and higher charge collection efficiency than those of pure TiO2 cell. Systematic investigations reveal that the CNT boosts the light harvesting ability of the photovoltaic devices by enhancing not only the visible light absorption but also the charge separation and transfer.

Synthesis of pure phase Mg1.2Ti1.8O5 and MgTiO3 nanocrystals for photocatalytic hydrogen production

Synthesis of pure phase Mg1.2Ti1.8O5 and MgTiO3 nanocrystals has proven to be challenging. Here, pure phase Mg1.2Ti1.8O5 and MgTiO3 nanocrystals were prepared. Furthermore, a new magnesium titanate, Mg1.2Ti1.8O5, was synthesized via a solution-based route for the first time. As hydrogen evolution photocatalysts, both pure phase Mg1.2TiLsO5 and MgTiO3 nanocrystals exhibit excellent hydrogen production efficiency. In comparison with pure MgTiO3 nanocrystals, the asprepared Mg1.2Ti1.8O5 nanocrystals exhibited four times as much photocatalytic hydrogen production activity, up to 40 μmol.h-1 Photoelectrochemical analysis, including linear sweep voltammetry, transient photocurrent measurement, electrochemical impedance spectroscopy, and construction of Mott-Schottky plots, demonstrated that the enhanced photocatalytic activity was attributed to the large surface area, fast photoelectron transfer, higher carrier density, and efficient charge separation of the Mg1.2Ti1.8O5 nanocrystals.

Multi‑color Tunable and White Circularly Polarized Luminescent Composite Nanofibers Electrospun from Chiral Helical Polymer

Circularly polarized luminescence(CPL)-active nanomaterials have attracted tremendous attention.However,it is still a big challenge to conveniently fabricate multi-color and white CPL-active nanomaterials on a large scale.Herein,a simple and scalable approach to achieve the above goals is presented.Multicolor CPL-active nanofibers are fabricated from chiral helical substituted polyacetylene,achiral fluorescent dyes and polyacrylonitrile via uniaxial electrospinning;the highest luminescence dissymmetry factor(glum)of the resulting nanofibers can reach 10^(−2).Furthermore,white CPL-active nanofibers are obtained by coaxial electrospinning,in which the resulting core-shell structure has excellent adjustability and can be utilized to physically isolate different fluorescent dyes to reduce energy transfer efficiency;therefore,stable white CPL emissions can be achieved with high g_(lum) values up to 10^(−3).Notably,the prepared white-emission CPL nanofibrous films show bright white circularly polarized light when coated on UV chips,demonstrating their future application in constructing low-cost and flexible light-emitting devices such as circularly polarized light-emitting diodes.

Hexagonal FeS nanosheets with high-energy （001） facets： Counter electrode materials superior to platinum for dye-sensitized solar cells

The catalytic activity of materials is highly dependent on their composition and surface structure, especially the density of low-coordinated surface atoms. In this work, we have prepared two-dimensional hexagonal FeS with high-energy （001） facets （FeS-HE-001） via a solution-phase chemical method. Nanosheets （NSs） with exposed high-energy planes usually possess better reaction activity, so FeS-HE-001 was used as a counter electrode （CE） material for dye-sensitized solar ceils （DSSCs）. FeS-HE-001 achieved an average power conversion efficiency （PCE） of 8.88% （with the PCE of champion cells being 9.10%）, which was almost 1.15 times higher than that of the Pt-based DSSCs （7.73%） measured in parallel. Cyclic voltammetry and Tafel polarization measurements revealed the excellent electrocatalytic activities of FeS-HE-001 towards the I-3/I- redox reaction. This can be attributed to the promotion of photoelectron transfer, which was measured by electrochemical impedance spectroscopy and scanning Kelvin probe, and the strong I-3 adsorption and reduction activities, which were investigated using first-principles calculations. The presence of high-energy （001） facets in the NSs was an important factor for improving the catalytic reduction of I-3. We believe that our method is a promising way for the design and synthesis of advanced CE materials for energy harvesting.

Entire process of surface discharge of GIS disc-spacers under constant AC voltage

Surface contamination on the disc-spacers is one of the main threats to the safe operation of gas insulated switchgear(GIS)insulation.The authors’research has confirmed the phenomena of intermittent discharge of such defects under AC constant voltage and concluded that long-intermittent discharge may be the cause of sudden flashover failure of GIS.To explore the characteristics of the process from the partial discharge(PD)inception to the breakdown of surface discharge under constant AC voltage,a 126 kV GIS test platform was built and long-term uninterrupted detection was carried out in this study.By processing the discharge data of the entire process,distribution characteristics of phase-resolved PD and N-V spectra and the trend of discharge repetition rate,discharge amplitude(maximum,mean,standard deviation)and discharge time interval(maximum,mean,standard deviation)were obtained.The results indicate that:there are two typical stages in the entire process of surface discharge under constant voltage and both discharge characteristics and risk of breakdown of those two stages are different obviously.Furthermore,based on the electro-chemical aging theory and space charge effects,the long-intermittent characteristics of solid insulation discharge are explained.

模拟多酶的自组装纳米凝胶构建及其生物响应性级联催化诱导成像

多酶复合物嵌合的自组装基质结构是生命体必要的组成部分.受此启发,本工作基于原位酰胺化反应诱导质子化过程,在纳米界面上自组装二赖氨酸配位铁(Fe(Lys)_(2))功能多肽单元,设计、构建了金属配合物基的超分子纳米凝胶(SiO_(2)@MCSGs)材料.由于其高度分散的Fe(Lys)_(2)活性中心类似于天然基质相关多酶复合物的高密度和纳米隔室化结构,纳米凝胶模拟酶材料显示出优异的催化效率.SiO_(2)@MCSGs同时呈现出超氧化物歧化酶(SOD)活性和过氧化物酶(POD)活性,且与游离Fe(Lys)_(2)分子相比显示超活性性能.负载底物2,2’-叠氮双-(3-乙基苯并噻唑啉-6-磺酸盐)(ABTS)后,SiO_(2)@MCSGsABTS可以通过SOD模拟酶性能将肿瘤微环境中的O^(-)_(2)·迅速转化为H2O_(2)中间体,然后基于POD模拟活性级联催化氧化ABTS实现高效的肿瘤光声成像(PA).具有多酶催化性能的MCSGs材料显示出对病理区响应性酶催化成像研究的巨大潜力.

Engineering surface oxygen vacancy of mesoporous CeO_(2) nanosheets assembled microspheres for boosting solar-driven photocatalytic performance

Surface oxygen vacancy defects of mesoporous CeO_(2)nanosheets assembled microspheres(D-CeO_(2))are engineered by polymer precipitation,hydrothermal and surface hydrogenation strategies.The resultant D-CeO_(2)with a main pore diameter of 9.3 nm has a large specific surface area(~102.3 m^(2)/g)and high thermal stability.The mesoporous nanosheets assembled microsphere structure prevents the nanosheets from aggregation,which is beneficial to effective mass transfer and shortens the migration distance of charge carriers.After surface hydrogenation,the photoresponse extends to long wavelength region,combing with the band gap from 2.63 eV reduced to 2.39 eV.Under AM 1.5 G radiation,the photocatalytic degradation rate of tetracycline(TC)can be up to 99.99%,which is three times as high as that of pristine CeO_(2)microspheres.The excellent solar-driven photocatalytic performance can be attributed to the efficient surface oxygen vacancy engineering and the mesoporous nanosheets assembled microsphere structure,which narrows the band gap,shortens the migration distance of carriers,promotes the spatial separation of photogenerated electron-hole pairs and favors mass transfer.The strategy provides new insights for fabricating other high-efficient oxide photocatalysts.

经自然腔道取标本手术(NOSES)治疗胃癌的国际共识(2019)

At present,natural orifice specimen extraction surgery(NOSES)has attracted more and more attention worldwide,because of its great advantages including minimal cutaneous trauma and post-operative pain,fast post-operative recovery,short hospital stay,and positive psychological impact.However,NOSES for the treatment of gastric cancer(GC)is still in its infancy,and there is great potential to improve its theoretical system and clinical practice.Especially,several key points including oncological outcomes,bacteriological concerns,indication selection,and standardized surgical procedures are raised with this innovative technique.Therefore,it is necessary to achieve an international consensus to regulate the implementation of GC-NOSES,which is of great significance for healthy and orderly development of NOSES worldwide.