Improved charge transfer by size-dependent plasmonic Au on C_3N_4 for efficient photocatalytic oxidation of RhB and CO_2 reduction

A series of Au/g-C3N4(Au/CN)nanocomposites were successfully prepared,where g-C3N4 nanosheets(CN NSs)served as a substrate for the growth of different sized Au nanoparticles(Au NPs)using the constant temperature bath-reduction method.The effect of Au NP size on electron transfer efficiency between the interfaces of the nanocomposite was studied.The three-dimensional finite-difference time-domain results revealed that larger Au NPs showed increased strength of the localized surface plasmon resonance effect.An increased number of high-energy electrons were available for transfer from Au NPs to CN under the visible light irradiation,inhibiting electron transfer from CN to Au NPs.Photoelectrochemical performance analysis showed that smaller Au NPs exhibited higher separation efficiency of the electron-hole pairs photo-generated with reasonable distribution density.These results are favorable for the improvement of photocatalytic performance.Compared to other nanocomposites,the 3-Au/CN sample(prepared using 3 mL HAuCl4 solution)with reasonable distribution density and small Au NPs exhibited the best photodegradation activity(92.66%)of RhB in 30 min under the visible light irradiation and photoreduction performance of CO2 to CO and CH4 with yields of 77.5 and 38.5μmol/g,respectively,in 8 h under UV light irradiation.Considering the experimental results in the context of the literature,a corresponding size-dependent photocatalytic mechanism was proposed.

Fast electron transfer and enhanced visible light photocatalytic activity by using poly-o-phenylenediamine modified AgCl/g-C_3N_4 nanosheets

Exfoliation of bulk graphitic carbon nitride(g‐C3N4)into two‐dimensional(2D)nanosheets is one of the effective strategies to improve its photocatalytic properties so that the 2D g‐C3N4 nanosheets(CN)have larger specific surface areas and more reaction sites.In addition,poly‐o‐phenylenediamine(PoPD)can improve the electrical conductivity and photocatalytic activity of semiconductor materials.Here,the novel efficient composite PoPD/AgCl/g‐C3N4 nanosheets was first synthesized by a precipitation reaction and the photoinitiated polymerization approach.The obtained photocatalysts have larger specific surface areas and could achieve better visible‐light response.However,silver chloride(AgCl)is susceptible to agglomeration and photocorrosion.The PoPD/AgCl/CN composite exhibits an extremely high photocurrent density,which is three times that of CN.Obviously enhanced photocatalytic activities of PoPD/AgCl/g‐C3N4 are revealed through the photodegradation of tetracycline.The stability of PoPD/AgCl/CN is demonstrated based on four cycles of experiments that reveal that the degradation rate only decreases slightly.Furthermore,.O2^-and h+are the main active species,which are confirmed through a trapping experiment and ESR spin‐trap technique.Therefore,the prepared PoPD/AgCl/CN can be considered as a stable photocatalyst,in which PoPD is added as a charge carrier and acts a photosensitive protective layer on the surface of the AgCl particles.This provides a new technology for preparing highly stable composite photocatalysts that can effectively deal with environmental issues.

Dynamic evolution in mechanical characteristics of complex supporting structures during large section tunnel construction

The shallow tunnelling method(STM)often uses temporary supports to divide large section tunnels into several closed or semiclosed sections so as to share the upper load.The complex support system composed of primary and temporary supports can ensure safety during tunnel construction.Based on the large section tunnel of Beijing Subway Line 12,the mechanical characteristics of support system by the double-side-drift method(DSDM)during excavation and demolition were analyzed through numerical simulation and monitoring.The study showed that the middle cave excavation was the most critical stage of the DSDM,during which the load on the supporting structure increased significantly.The temporary vertical support bore most of the new load during middle cave excavation.During the demolition stage,the load was redistributed,which caused arch settlement and section convergence.The removal of the temporary vertical support exerted the greatest impact in this process.The lateral temporary inverted arch changed from axial compression to axial tension after the middle and lower caves were excavated.Based on the mechanical characteristics of the support system,some engineering suggestions were proposed for large section tunnel construction.These research results can provide reference for the design and construction of similar large section tunnels.

Polyimide covalent organic frameworks as efficient solid-state Li^(+) electrolytes

Covalent organic frameworks(COFs) are attractive porous crystalline materials with extremely high stability, easy functionalization, and open channels, which are expected to be unique ion conductors/transporters in lithium ion batteries(LIBs). Despite recent advances, low ion conductivity and low transference number, resulting in low charging/discharging rate, low energy density, and short battery life, are the main issues that limit their direct application as solid electrolytes in LIBs. Here, we designed and synthesized a novel polyimide COF, namely, TAPA-PDI-COF, with abundant C=O groups, which has been successfully employed as high-performance solid electrolytes by doping TAPA-PDI-COF and succinonitrile(SN). Both the well-defined nanochannels of COFs and SN confined in the well-aligned channels restricted the free migration of anions, while C=O on COFs and CN groups of SN enhanced Li^(+) transport, thus achieving a high ion conductivity of 0.102 m S cm^(-1)at 80 °C and a high lithium-ion transference number of 0.855 at room temperature. According to density functional theory(DFT)calculations, Li-ion migration mainly adopted in-plane transport rather than the axial pathway, which may be due to the shorter hopping distances in the planar pathway. The results suggest an effective strategy for the design and development of all-solidstate ionic conductors for achieving high-performance LIBs.

Mesoporous molecular sieve confined phase change materials with high absorption,enhanced thermal conductivity,and cooling energy charging/discharging capacity

The biggest challenge for organic phase change materials(PCMs)used in cold energy storage is to maintain high heat storage capacity while reducing the leakage risk of PCMs during the phase transition process.This is crucial for expanding their applications in the more demanding cold storage field.In this study,novel formstable low-temperature composite PCMs are prepared with mesoporous materials,namely SBA-15 and CMK-3(which are prepared using the template method),as supporting matrices and dodecane as the PCM.Owing to the combined effects of capillary forces within mesoporous materials and interactions among dodecane molecules,both dodecane/SBA-15 and dodecane/CMK-3 exhibit outstanding shape stability and thermal cycling stability even after 200 heating/cooling cycles.In comparison to those of dodecane/SBA-15,dodecane/CMK-3 exhibits superior cold storage performance and higher thermal conductivity.Specifically,the phase transition temperature of dodecane/CMK-3 is-8.81℃ with a latent heat of 122.4 J·g^(-1).Additionally,it has a thermal conductivity of 1.21 W·m^(-1)·K^(-1),which is 9.45 times that of dodecane alone.All these highlight its significant potential for applications in the area of cold energy storage.

Highly elastic energy storage device based on intrinsically super-stretchable polymer lithium-ion conductor with high conductivity

Stretchable power sources,especially stretchable lithium-ion batteries(LIBs),have attracted increasing attention due to their enormous prospects for powering flexible/wearable electronics.Despite recent advances,it is still challenging to develop ultra-stretchable LIBs that can withstand large deformation.In particular,stretchable LIBs require an elastic electrolyte as a basic component,while the conductivity of most elastic electrolytes drops sharply during deformation,especially during large deformations.This is why highly stretchable LIBs have not yet been realized until now.As a proof of concept,a super-stretchable LIB with strain up to 1200%is created based on an intrinsically super-stretchable polymer electrolyte as the lithium-ion conductor.The super-stretchable conductive system is constructed by an effective diblock copolymerization strategy via photocuring of vinyl functionalized 2-ureido-4-pyrimidone(VFUpy),an acrylic monomer containing succinonitrile and a lithium salt,achieving high ionic conductivity(3.5×10^(-4)mS cm^(-1)at room temperature(RT))and large deformation(the strain can reach 4560%).The acrylic elastomer containing Li-ion conductive domains can strongly increase the compatibility between the neighboring elastic networks,resulting in high ionic conductivity under ultra-large deformation,while VFUpy increases elasticity modulus(over three times)and electrochemical stability(voltage window reaches 5.3 V)of the prepared polymer conductor.At a strain of up to 1200%,the resulting stretchable LIBs are still sufficient to power LEDs.This study sheds light on the design and development of high-performance intrinsically super-stretchable materials for the advancement of highly elastic energy storage devices for powering flexible/wearable electronics that can endure large deformation.

Cytidine Mediated AuAg Nanoclusters as Bright Fluorescent Probe for Tumor Imaging in vivo

Noble metal clusters is an emerging class of fluorescent probes, avoiding most of the drawbacks of common fluorescent compounds, and they are simple to prepare and have good water solubility, good biocompatibility and excellent fluorescence properties. In this study, we have explored the synthesis of the cytidine mediated gold-silver nanoclusters （AuAg NCs） and applied it for both in vitro cellular imaging and tumor in vivo detection. Experimental results show that the as-prepared AuAg NCs can be used as a sensitive fluorescent probe for cancer cells/tissue de- tection. Especially, it is evident that under the relevant light irradiation with the wavelength of 488 nm, obviously bright fluorescence signal could be readily detected from focus location of inoculating tumor mouse, implying its possible application for the effective in vivo tumor bioimaging.

Optimal control of a nonlinear state-dependent impulsive system in fed-batch process

Optimal control technique is crucial to improve the yield of microbial fermentation production.In this paper,we propose a nonlinear control system with state-dependent impulses,where the impulsive volume of feeding glycerol and the critical concentration of glycerol for occurring impulse are the control variables,to formulate 1,3-propanediol(1,3-PD)fed-batch production process.We also discuss a quantity of important properties for this control system.Then,we analyze the sensitivity of system state with respect to the kinetic parameters.We further propose a constrained optimal control model governed by the control system with state-dependent impulses.The existence of the optimal impulsive controls is established.For solving this problem,we utilize an exact penalty method to transform the problem into an optimization problem with only box constraints.Moreover,an improved differential evolution method is developed to seek the optimal impulsive strategy.Finally,numerical simulation results demonstrate that,by using the optimal impulsive strategies,final 1,3-PD concentration is considerably increased under the nominal parameter values and disturbances of kinetic parameters have significant effects on the optimal final 1,3-PD yield.

The uncoupled microbial fed-batch fermentation optimization based on state-dependent switched system

In the actual microbial fermentation process,excessive or insufficient substrate can produce inhibitory effects on cells growth.The artificial substrate feeding rules by past experiences have great blindness to keep substrate concentration in a given appropriate range.This paper considers that alkali feed depends on pH value of the solution and glycerol feed depends on glycerol concentration of the solution in the uncoupled microbial fed-hatch fermentation process,and establishes a state-dependent switched system in which the flow rates of glycerol and alkali,the number of mode switches,the mode sequence and the switching times are prior unknown.To maximize the yield of target product 1,3-Propanediol(1,3-PD),we formulate a switching optimal control problem with the flow rates of glycerol and alkali,the number of mode switches,the mode sequence and the switching times as decision variables,which is a mixed-integer dynamic programming problem.For solving the mixed-integer dynamic programming problem,the control parametrization technique,the time scaling transformation and the embedded system technology are used to obtain an approximate parameter optimization problem.By using a parallel optimization algorithm,we obtain the optimal control strategies.Under the obtained optimal control strategies,the 1,3-PD yield at the terminal time is increased significantly compared with the previous results.

半乳糖凝集素家族基因在肝细胞癌中的表达和预后价值分析

目的:半乳糖凝集素(Galectins,LGALS)是聚糖蛋白之一,含有一个或多个保守的β-半乳糖苷糖识别结构域,在炎症、感染、癌症等疾病中起重要作用.本研究旨在评估肝细胞癌(Liver hepatocellular carcinoma,LIHC)中半乳糖凝集素家族基因作为治疗靶点和预后标志物的能力,为临床诊疗奠定基础.方法:应用Oncomine、UALCAN、GEPIA、cBioPortal、DAVID和TRRUST数据库来探究半乳糖凝集素家族基因在肝细胞癌中的作用.通过Western Blot和RT-qPCR实验进一步验证半乳糖凝集素家族基因在肝细胞癌中的表达水平.结果:LGALS1/2/3/4/8/9在肝细胞癌中高表达,其中LGALS3/7/14的mRNA表达与患者的肿瘤临床分期显著相关,LGALS1/2/3与LIHC患者的预后相关.此外,差异表达的半乳糖凝集素家族基因的功能主要与破骨细胞分化等有关.PTTG1/JUN、RUNX1、RUNX2/POU2F1/HDAC3可能是LGALS1/3/4/9的转录因子.最后,采用人肝细胞癌细胞和组织样本,通过Western Blot和RT-qPCR实验验证LGALS1/2的生信结果,发现LGALS1/2在肝细胞癌中高表达.结论:半乳糖凝集素家族基因的异常表达与肝细胞癌的进展以及预后有关.本研究有望为肝细胞癌的预后判断和个性化治疗策略选择提供新的思路.

An effective global learning framework for hyperspectral image classification based on encoder-decoder architecture

Most deep learning methods in hyperspectral image(HSI)classification use local learning methods,where overlapping areas between pixels can lead to spatial redundancy and higher computational cost.This paper proposes an efficient global learning(EGL)framework for HSI classification.The EGL framework was composed of universal global random stratification(UGSS)sampling strategy and a classification model BrsNet.The UGSS sampling strategy was used to solve the problem of insufficient gradient variance resulted from limited training samples.To fully extract and explore the most distinguishing feature representation,we used the modified linear bottleneck structure with spectral attention as a part of the BrsNet network to extract spectral spatial information.As a type of spectral attention,the shuffle spectral attention module screened important spectral features from the rich spectral information of HSI to improve the classification accuracy of the model.Meanwhile,we also designed a double branch structure in BrsNet that extracted more abundant spatial information from local and global perspectives to increase the performance of our classification framework.Experiments were conducted on three famous datasets,IP,PU,and SA.Compared with other classification methods,our proposed method produced competitive results in training time,while having a greater advantage in test time.