Deformation and failure characteristics of sandstone under uniaxial compression using distributed fiber optic strain sensing

This paper investigates the deformation and fracture propagation of sandstone specimen under uniaxial compression using the distributed fiber optic strain sensing(DFOSS)technology.It shows that the DFOSS-based circumferential strains are in agreement with the data monitored with the traditional strain gage.The DFOSS successfully scans the full-field view of axial and circumferential strains on the specimen surface.The spatiotemporal strain measurement based on DFOSS manifests crack closure and elastoplastic deformation,detects initialization of microcrack nucleation,and identifies strain localization within the specimen.The DFOSS well observes the effects of rock heterogeneity on rock deformation.The advantage of DFOSS-based strain acquisition includes the high spatiotemporal resolution of signals and the ability of full-surface strain scanning.The introduction to the DFOSS technology yields a better understanding of the rock damage process under uniaxial compression.

High mobility channel estimation method based on improved basis expansion model

In this paper, the problem of high mobility channel estimation in the Long-Term Evolution for Railway (LTE-R) communication system is investigated. By using a Basis Expansion Model (BEM), the channel impulse response is modeled as the sum of several basis functions multiplied by coefficients. By estimating the basis function coefficients, the fast time-varying channel can be approximated. In order to reduce the estimation error resulting from the high frequency basis function, the Generalized Complex Exponential BEM (GCE-BEM) is modified to form an Improved GCE-BEM (IGCE-BEM) by adding a correction coefficient to the basis function. Moreover, an Improved Baseline Tilting (IBT) method is proposed to reduce the Gibbs effect. In addition, linear interpolation, Gauss interpolation, and three-order Hermite interpolation are adopted to obtain the channel impulse response at non pilot locations based on the channel estimation results at pilot positions. The simulation results show that the IGCE-BEM outperforms the CE-BEM and GCE-BEM in terms of the Normalized Mean Squared Error (NMSE). The IB T method is better than the BT method in reducing the Gibbs effect. In addition, combined with the IBT, the IGCE-BEM also has low NMSE under high moving speed and high noise power. The performance of the threeorder Hermite interpolation method is higher than that of the linear interpolation and Gauss interpolation approaches.

Basis expansion model for channel estimation in LTE-R communication system

This paper investigates fast time-varying channel estimation in LTE-R communication systems. The Basis Expansion Model （BEM） is adopted to fit the fast time-varying channel in a high-speed railway com- munication scenario. The channel impulse response is modeled as the sum of basis functions multiplied by different coefficients. The optimal coefficients are obtained by theoretical analysis. Simulation results show that a Generalized Complex-Exponential BEM （GCE-BEM） outperforms a Complex-Exponential BEM （CE-BEM） and a polynomial BEM in terms of Mean Squared Error （MSE）. Besides, the MSE of the CE- BEM decreases gradually as the number of basis functions increases. The GCE-BEM has a satisfactory performance with the serious fading channel.

Dt1 inhibits SWEET-mediated sucrose transport to regulate photoperiod-dependent seed weight in soybean

Soybean is a photoperiod-sensitive short-day crop whose reproductive period and yield are markedly affected by day-length changes.Seed weight is one of the key traits determining the soybean yield;how-ever,the prominent genes that control the final seed weight of soybean and the mechanisms underlying the photoperiod's effect on this trait remain poorly understood.In this study,we identify SwW19 as a major locus controlling soybean seed weight by QTL mapping and determine Dt1,an orthologous gene of Arabidopsis TFL1 that is known to govern the soybean growth habit,as the causal gene of the SW19 locus.We showed that Dt1 is highly expressed in developing seeds and regulates photoperiod-dependent seed weight in soybean.Further analyses revealed that the Dt1 protein physically interacts with the sucrose transporter GmSWEET10a to negatively regulate the import of sucrose from seed coat to the embryo,thus modulating seed weight under long days.However,Dt1 does not function in seed development under short days due to its very low expression.Importantly,we discovered a novel natural allelic variant of Dt1(H4 haplotype)that decouples its pleiotropic effects on seed size and growth habit;i.e.,this variant remains functional in seed development but fails to regulate the stem growth habit of soybean.Collectively,our findings provide new insights into how soybean seed development responds to photoperiod at different latitudes,offering an ideal genetic component for improving soybean's yield by manipulating its seed weightandgrowth habit.

Design and development of a mitochondrial-targeted photosensitizer for two-photon fluorescence imaging and photodynamic therapy

Mitochondria are well-acknowledged as ideal targets for tumor therapy due to their important role in energy supply and cellular signal regulation.Mitochondria-specific photosensitizers have been reported to be critical for inducing cell apoptosis.Two-photon fluorescence imaging provides a new technique for delineating biological structures and activities in deep tissues.Herein,we developed a new aggregation-induced emission(AIE)active photosensitizer by attaching a pyridinium group for mitochondrial target-ing.The rationally designed photosensitizer(TTTP)exhibited excellent photophysical properties,good biocompatibility,reactive oxygen species(ROS)stimulation ability,anticancer efficacy,and two-photon imaging properties.TTTP was highly taken up by cells and accumulated specifically in mitochondria but was selectively cytotoxic to cancer cells.Under light irradiation,the generation of ROS was significantly boosted,leading to actively induced apoptosis.The in vivo tumor photodynamic therapeutic efficacy of TTTP showed significant inhibition of tumor growth.Furthermore,the underlying mechanism of TTTP tu-mor suppression revealed that the apoptosis agonist Bax was markedly up-regulated while the antagonist Bcl-xL was down-regulated.This research provides a potential mitochondrial-targeted phototherapeutic agent for effective therapy and two-photon fluorescence imaging.

基于磷脂膜的界面相互作用研究

磷脂是一类非常重要的生物分子,它是细胞膜的主要组成部分,同时也在诸多生命活动(如细胞激活、代谢维持和激素分泌等)中发挥着不可替代的作用。磷脂种类繁多,且具有自组装能力强、生物相容性好、无细胞毒性、易于获得等一系列优点。作为一种最典型的界面材料,磷脂膜特殊的双层结构及出色的生物学性能引起了科研人员的广泛关注,其能够模拟生物膜结构,有助于研究界面上的分子特征及作用行为。此外,磷脂可被用作生物医学材料,改性磷脂以及磷脂与纳米颗粒的复合物在肿瘤成像技术、药物靶向递送系统等方面具有良好的发展前景,显著促进了新型生物材料的开发与进步。本文先归纳了磷脂的分类,并比较了磷脂在不同基底的吸附行为;之后重点分析了磷脂膜界面的选择性识别功能以及与多肽、酶、蛋白质等生物分子之间的相互作用;最后对基于磷脂膜的生物材料在生物传感、药物研究和成像技术中的应用作出了展望。

FT5a interferes with the Dt1-AP1 feedback loop to control flowering time and shoot determinacy in soybean

Flowering time and stem growth habit determine inflorescence architecture in soybean, which in turn influences seed yield. Dt1, a homolog of Arabidopsis TERMINAL FLOWER 1(TFL1), is a major controller of stem growth habit, but its underlying molecular mechanisms remain unclear.Here, we demonstrate that Dt1 affects node number and plant height, as well as flowering time,in soybean under long-day conditions. The b ZIP transcription factor FDc1 physically interacts with Dt1, and the FDc1-Dt1 complex directly represses the expression of APETALA1(AP1). We propose that FT5 a inhibits Dt1 activity via a competitive interaction with FDc1 and directly upregulates AP1. Moreover, AP1 represses Dt1 expression by directly binding to the Dt1 promoter, suggesting that AP1 and Dt1 form a suppressive regulatory feedback loop to determine the fate of the shoot apical meristem. These findings provide novel insights into the roles of Dt1 and FT5 a in controlling the stem growth habit and flowering time in soybean, which determine the adaptability and grain yield of this important crop.

Rational design of novel ultra-small amorphous Fe_(2)O_(3)nanodots/graphene heterostructures for all-solid-state asymmetric supercapacitors

Constructing graphene-based heterostructures with large interfacial area is an efficient approach to enhance the electrochemical performance of supercapacitors but remains great challenges in their synthesis.Herein,a novel ultra-small amorphous Fe_(2)O_(3)nanodots/graphene heterostructure(a-Fe_(2)O_(3)NDs/RGO)aerogel was facilely synthesized via excessive metal-ion-induced self-assembly and subsequent calcination route using Prussian blue/graphene oxide(PB/GO)composite aerogel as precursors.The deliberately designed a-Fe_(2)O_(3)NDs/RGO heterostructure offers a highly interconnected porous conductive network,large heterostructure interfacial area,and plenty of accessible active sites,greatly facilitating the electron transfer,electrolyte diffusion,and pseudocapacitive reactions.The obtained a-Fe_(2)O_(3)NDs/RGO aerogel could be used as flexible free-standing electrodes after mechanical compression,which exhibited a significantly enhanced specific capacitance of 347.4 F·g^(-1)at 1 A·g^(-1),extraordinary rate capability of 184 F·g^(-1)at 10 A·g^(-1),and decent cycling stability.With the as-prepared a-Fe_(2)O_(3)NDs/RGO as negative electrodes and the Co_(3)O_(4)NDs/RGO as positive electrodes,an all-solid-state asymmetric supercapacitor(a-Fe_(2)O_(3)NDs/RGO//Co_(3)O_(4)NDs/RGO asymmetric supercapacitor(ASC))was assembled,which delivered a high specific capacitance of 69.1 F·g^(-1)at 1 A·g^(-1)and an impressive energy density of 21.6 W·h·k·g^(-1)at 750 W·k·g^(-1),as well as good cycling stability with a capacity retention of 94.3%after 5,000 cycles.This work provides a promising avenue to design high-performance graphene-based composite electrodes and profound inspiration for developing advanced flexible energy-storage devices.

Two-dimensional polymer nanosheets for efficient energy storage and conversion

As a promising graphene analogue,two-dimensional(2D)polymer nanosheets with unique 2D features,diversified topological structures and as well as tunable electronic properties,have received extensive attention in recent years.Here in this review,we summarized the recent research progress in the preparation methods of 2D polymer nanosheets,mainly including interfacial polymerization and solution polymerization.We also discussed the recent research advancements of 2D polymer nanosheets in the fields of energy storage and conversion applications,such as batteries,supercapacitors,electrocatalysis and photocatalysis.Finally,on the basis of their current development,we put forward the existing challenges and some personal perspectives.

Regulating electronic structure of two-dimensional porous Ni/Ni_(3)N nanosheets architecture by Co atomic incorporation boosts alkaline water splitting

Interfacial engineering is a powerful method to improve the bifunctional electrocatalytic performance of pure phase catalysts.While it is expected to further optimize the electronic configuration of heterojunctions to boost the reaction kinetics in hydrogen/oxygen evolution reaction(HER/OER),but remains a challenge.Herein,a novel in situ hybrid heterojunction strategy is developed to construct 2D porous Co-doped Ni/Ni_(3)N heterostructure nanosheets(Co-Ni/Ni_(3)N)by pyrolysis of partially cobalt substituted nickel-zeolitic imidazolate framework(CoNi-ZIF)nanosheets under NH3 atmosphere.A combined experimental and theoretical studies manifest that the hybrid heterostructures can display regulative electronic states and downshift d-band center from the Fermi level,as well as optimize the adsorption energy of reaction intermediates,thus reducing the thermodynamic energy barriers and accelerating the catalytic kinetics.Consequently,benefitting from the optimized electronic configuration,hierarchical hollow nanosheets architecture,and abundant doped heterojunctions,the hybrid Co-Ni/Ni_(3)N heterostructure catalyst exhibits efficient catalytic activity for both HER(60 mV)and OER(322 mV)at 10 mA cm^(-2)in alkaline media,which is 105 and 47 mV lower than that of pure Ni_(3)N,respectively.The electrochemically active surface area of Co-Ni/Ni_(3)N is two times higher than that of Ni3N.Furthermore,the coupled practical water electrolyzer requires a low voltage of 1.575 V to reach 10 mA cm^(-2),and it can be driven by a 1.5 V battery.This work highlights the interface engineering guidance for the rational establishment of hybrid interfaces by electronic modulation of interfacial effect for alkaline water splitting.

Electrochemiluminescence Sensor for Cancer Cell Detection Based on H_(2)O_(2)-Triggered Stimulus Response System

A H_(2)O_(2)-triggered stimulus response electrochemiluminescence(ECL)sensor for sensitive detection of cancer cells using mesoporous silica nanoparticles(MSNs)has been proposed.ECL signal-generating molecules(Ru(phen)32+)were encap-sulated into phenylboronic acid group-functionalized MSNs(PBA-MSNs)porous and capped by polyhydroxy functioned Au nanoparticles(AuNPs)through the interaction of carbohydrate-boronic acid first.Brunauer-Emmett-Teller(BET)and transmission electron microscopy(TEM)were applied to characterize the materials.The proposed controlled release sensing platform shows approximately no leakage from the mesoporrs of MSNs after a long time of storage.Cancer cells are initially incubated with the functionalized MSNs and then treated with ascorbic acid to endogenously produce H_(2)O_(2).Arylboronic esters in the MSNs surface can be oxidized by the produced H_(2)O_(2),causing the releasing of the molecule from MSNs and increased ECL signal.This technique displayed an excellent measurement for the breast cancer cells’sensitive diagnosis with a detection limit of 208 cells/mL.The phenomenon suggests that this sensing platform may be potentially applied for breast cancer sensitive detection in the future.