Effects of grassland vegetation roots on soil infiltration rate in Xiazangtan super large scale landslide distribution area in the upper reaches of the Yellow River,China

In order to study the infiltration characteristics of grassland soil in the super large scale landslides distribution area in the upper reaches of the Yellow River,this study selected the Xiazangtan super large scale distribution area in Jianzha County as the study area.Through experiments and numerical simulations,plant roots characteristics,soil physical properties and infiltration characteristics of naturally grazed grassland and enclosed grassland with different slope directions were compared and analyzed,and the influence of rainfall on seepage field and stability of the two grassland slopes were discussed.The results show that the highest soil moisture infiltration capacity(FIR)is found on the shady slope of the enclosed grassland(2.25),followed by the sunny slope of the enclosed grassland(1.23)and the shady slope of the naturally grazed grassland(-0.87).Correlation analysis show that soil water content,root dry weight density,total soil porosity,number of forks and root length are positively correlated with infiltration rate(P<0.05),whereas soil dry density is negatively correlated with infiltration rate(P<0.05).The results of stepwise regression analyses show that soil water content,total soil porosity,root length and number of forks are the main factors affecting soil infiltration capacity.And the ability of roots to increase soil infiltration by improving soil properties is higher than the effect of roots itself.After 60 min of simulated rainfall,the safety factors of the shady slopes of naturally grazed grassland and enclosed grassland are reduced by 29.56%and 19.63%,respectively,comparing to those before rainfall.Therefore,in this study,the roots play a crucial role in regulating soil infiltration and enhance slope stability by increasing soil water content,soil total porosity and shear strength while decreasing soil dry density.The results of this study provide theoretical evidence and practical guidance for the effective prevention and control of secondary geological disasters such as soil erosion and shallow landslide on the slope of river banks in the study area by using plant ecological measures.

黄芩汤通过调控内质网应激减轻小鼠溃疡性结肠炎

目的观察黄芩汤对小鼠溃疡性结肠炎(UC)细胞凋亡的影响并探讨其作用机制。方法将雄性Balb/c小鼠随机分为:正常组、模型组、美沙拉嗪组(5-ASA,200 mg/kg)、黄芩汤低、中、高剂量组(HQDL,2.275 g/kg;HQDM,4.55 g/kg;HQDH,9.1 g/kg),8只/组。各组自由饮食,除正常组自由饮用无菌水外,其余各组小鼠自由饮用3%DSS溶液,持续7d以建立UC模型。取结肠组织采用HE、AB-PAS和TUNEL染色分别观察结肠损伤和细胞凋亡情况,采用ELISA法检测炎症因子表达变化;采用Western blotting、免疫组化和qRT-PCR法分别检测肠道化学屏障、机械屏障、内质网应激等相关指标的蛋白或基因表达变化。结果与模型组相比,黄芩汤干预下的UC小鼠,DAI评分和宏观评分下降(P<0.01),TUNEL染色荧光强度下降(P<0.01)。促炎因子IL-6、TNF-α、IL-1β、IL-8表达减少(P<0.01),MUC2和TFF3的基因表达升高(P<0.05),Claudin-1、Occludin和E-cadherin的蛋白表达升高(P<0.05),GRP78、CHOP和Caspase-12的基因和蛋白表达下降(P<0.01)、PERK、eIF2α和IRE1α的磷酸化表达降低(P<0.05),Bcl-2/Bax蛋白表达比例升高(P<0.01)和Caspase-3的蛋白表达降低(P<0.01)。结论黄芩汤能够抑制UC小鼠的细胞凋亡反应并改善肠道屏障功能,其机制可能与PERK和IRE1α信号通路介导的内质网应激有关。

习近平关于少年儿童工作重要论述的思想内涵和时代要求

习近平关于少年儿童工作重要论述以深邃的思想洞察发展了马克思主义儿童观,突出政治性,富有时代性、科学性、系统性,强调了少先队工作的根本政治任务,指出了少年儿童成长成才的正确路径,提出了少年儿童工作的具体方法,指导少年儿童工作改革取得了一系列重要成果,明确了新时代建设什么样的少先队、怎么样建设少先队这个根本问题,是新时代做好少先队和少年儿童工作的行动指南。

Middle–Upper Ordovician(Darriwilian–Early Katian) Positive Carbon Isotope Excursions in the Northern Tarim Basin, Northwest China: Implications for Stratigraphic Correlation and Paleoclimate

Three positive carbon isotope excursions are reported from Middle-Upper Ordovician in Tahe oil-gas field, northern Tarim Basin. Based on conodont biostratigraphy, the Middle Darriwilian Isotope Carbon Excursion（MDICE） and the Guttenberg Carbon Isotope Excursion（GICE） are identified from Darriwilian to Early Katian by the aid of whole-rock carbon isotope data from two well cores. Positive excursion within conodont Pygodus anserinus zone is developed in Early Sandbian, and the fluctuation range is no less than MDICE. Because the range of this excursion in the generalized global carbon isotope curve is short, previous studies paid little attention to it, and named Early Sandbian Isotope Carbon Excursion（ESICE） in this paper. Furthermore, these positive excursions are not directly related to sea level fluctuations and the MDICE and GICE identified in northern Tarim can be globally correlated to that in southern China, North America, South America, and Europe. The Saergan Fm. source rocks of Middle-Upper Ordovician in Kalpin Dawangou outcrop are in accord with the geologic time of MDICE and ESICE, and GICE have strong ties to the source rock of Lianglitag Fm. in basin. Abundant organic carbon burial is an important factor in genesis of positive isotope carbon excursions. Positive oxygen isotope excursion, conodont fauna turnover, decreased conodont total diversity, and the change of sedimentary facies indicated that dramatic changes of paleoceanographic environment of Early-Middle Ordovician in Tarim Basin started from the end of Darriwillian, and an obvious icehouse climate of Late Ordovician occurred in ESICE.

High efficiently harvesting visible light and vibration energy in(1−x)AgNbO_(3)-xLiTaO_(3) solid solution around antiferroelectric-ferroelectric phase boundary for dye degradation

Simultaneously employing light and vibration energy by piezoelectric material to realize environmental remediation is an advanced oxidation method.Silver niobate(AgNbO_(3))is a visible light driven photocatalyst for the removal of organic pollutants.However,the high recombination rate of photo-generated electrons and holes suppresses its photocatalytic activity.Piezoelectric potential excited by vibration can facilitate the separation of light induced charges.Unfortunately,AgNbO_(3) is an antiferroelectric.In this work,distinct photo-/vibration-bi-catalysis has been achieved in ferroelectric(1−x)AgNbO_(3)-xLiTaO_(3) solid solution.The results show that ~96% Rhodamine B(RhB)can be decomposed under the bi-excitation of ultrasound and visible light within 120 min with 0.95AgNbO_(3)-0.05LiTaO_(3) catalyst.The synergy effect from efficient visible light excitation and enhanced separation of the photo-induced charges from the electric field by the mechanical strain results in the distinct decomposition performance of catalysts.

Synergy of lead vacancies and morphotropic phase boundary to promote high piezoelectricity and temperature stability of PBZTN ceramics

The flourishing development of emerging electromechanical applications has stimulated an urgent demand for ferroelectric ceramics with high piezoelectric properties and broad temperature usage range.However,it remains a challenge to simultaneously obtain good piezoelectricity and reliable temperature stability in lead zirconate titanate(PZT)-based piezoelectric ceramics.To solve this issue,a synergetic strategy was proposed to introduce lead vacancies through niobium doping and construct morphotropic phase boundary(MPB).In this work,Pb_(0.905)Ba_(0.085)(V Pb″)_(0.01)[(Zr_(x)Ti_(1-x))_(0.98)Nb_(0.02)]O_(3)(PBZTN-x)material system was designed.Good comprehensive properties(d_(33)=864 pC/N,k_(p)=84%,T_(C)=201℃)and excellent temperature stability(less than 10%variation of electrical properties from 20℃ to 160℃)were obtained in PBZTN-0.540 ceramics.Good piezoelectricity can be attributed to high extrinsic contribution(domain wall motion)induced by Pb^(2+)vacancies and the existence of nano-domains emerged at MPB,while excellent temperature stability is mainly attributed to the minimized local stress in the lattice and the stable domain structure.

Metal-organic framework nanofilm enhances serum metabolic profiles for diagnosis and subtype of cardiovascular disease

Cardiovascular disease(CVD)is a global health problem and is thought to be responsible for almost half of all deaths in the world.Nevertheless,currently available diagnostic methods for CVD are strongly depended on clinical observation and monitoring,which commonly result in false diagnosis.Herein,an attractive strategy of a metal-organic framework(MOF)nanofilm-based laser desorption/ionization mass spectrometry(LDI-MS)was developed for enhancing serum metabolic profiling,which could provide precise diagnosis and molecular subtyping of CVD.The porous MOF nanofilm fabricated on indium-tin oxide(ITO)glass possessed enhanced ionization efficiency and size-exclusion effect,which endowed it as substrate with high sensitivity and selectivity for serum metabolites.Furthermore,the MOF nanofilm with uniform surface and high orientation provided high-quality and high-reproducibility serum metabolic profiles(SMPs)without any tedious pretreatment.Further analysis of extracted serum metabolic fingerprints could successfully distinguish patients with CVD from healthy controls and also differentiate two major subtypes of CVD.This work not only extends the application of MOF nanofilm as an attractive MS probe,but also provide an alternative way for precise diagnosis of CVD in molecular level.

Copper(Ⅱ) ions-immobilized virus-like hollow covalent organic frameworks for highly efficient capture and sensitive analysis of amyloid beta-peptide 1–42 by MALDI-MS

Amyloid beta-peptide 1-42(Aβ1-42)is one of the biomarkers of Alzheimer's disease,and its selective capture and quantitative detection are important for diagnosis and treatment of Alzheimer's disease.Herein,copper(Ⅱ)ions-immobilized virus-like hollow covalent organic frameworks(V-HCOFs@Cu^(2+))were synthesized by a facile approach.The as-prepared V-HCOFs@Cu^(2+)showed unique morphology,ultra-high specific surface(2552 m^(2)/g),uniform mesoporous structure(3.2 nm),superior chemical stability and abundant binding sites.Based on these excellent properties,the V-HCOFs@Cu^(2+)could be adopted as an ideal enrichment probe for highly efficient capture of Aβ1-42,exhibiting high adsorption capacity(320 mg/g),and fast adsorption equilibration time(3 min).In addition,an attractive approach of the V-HCOFs@Cu^(2+)-based matrix-assisted laser desorption/ionization mass spectrometry(MALDI-MS)was developed for the rapid screening and quantitative analysis of Aβ1-42 in human serum by using C-peptide as an internal standard,which exhibited low limit of detection(LOD,0.2 fmol/μL),and satisfactory recovery.This work provides an alternative solution for enrichment of biomarkers and also offers the potential applications of COFs in clinical analysis.

Translationally controlled tumor protein: the mediator promoting cancer invasion and migration and its potential clinical prospects

Translationally controlled tumor protein(TCTP) is a highly conserved multifunctional protein localized in the cytoplasm and nucleus of eukaryotic cells. It is secreted through exosomes and its degradation is associated with the ubiquitin-proteasome system(UPS), heat shock protein 27(Hsp27), and chaperone-mediated autophagy(CMA). Its structure contains three α-helices and eleven β-strands, and features a helical hairpin as its hallmark. TCTP shows a remarkable similarity to the methionine-R-sulfoxide reductase B(Msr B) and mammalian suppressor of Sec4(Mss4/Dss4) protein families, which exerts guanine nucleotide exchange factor(GEF) activity on small guanosine triphosphatase(GTPase) proteins, suggesting that some functions of TCTP may at least depend on its GEF action. Indeed, TCTP exerts GEF activity on Ras homolog enriched in brain(Rheb) to boost the growth and proliferation of Drosophila cells. TCTP also enhances the expression of cell division control protein 42 homolog(Cdc42) to promote cancer cell invasion and migration. Moreover, TCTP regulates cytoskeleton organization by interacting with actin microfilament(MF) and microtubule(MT) proteins and inducing the epithelial-mesenchymal transition(EMT) process. In essence, TCTP promotes cancer cell movement. It is usually highly expressed in cancerous tissues and thus reduces patient survival;meanwhile, drugs can target TCTP to reduce this effect. In this review, we summarize the mechanisms of TCTP in promoting cancer invasion and migration, and describe the current inhibitory strategy to target TCTP in cancerous diseases.

Predesigned covalent organic framework with sulfur coordination: Anchoring Au nanoparticles for sensitive colorimetric detection of Hg(Ⅱ)

Targeted construction of new covalent organic frameworks(COFs)with specific purposes and rationalities to build colorimetric assay platform for environmental pollutant monitoring have attracted increasing interest.However,it is still challenging due to lack of available coordination sites inside COFs pores and only a slight bonding ability for anchoring metal.In this work,a two-dimensional(2D)COFs(termed as Tz-COF)with high crystallinity,excellent chemical stability,and abundant sulfur coordination in its skeletons was synthesized and used for the confined growth of Au NPs.It was found that the Au NPs showed significant dispersibility for the support of Tz-COF.The proposed Tz-COF@Au NPs possessed outstanding Hg^(2+)-activated peroxidase-like activity benefited from physicochemical properties of gold amalgam and synergistic effect between COFs and Au NPs to oxidize chromogenic substrate.Based on highly efficient activity and distinctive color evolution,the strategy for detecting Hg^(2+)was developed and successfully applied to determine the content of Hg^(2+)in real environmental samples.This work manifests that a potential strategy to establish a colorimetric assay platform for environmental pollutant monitoring based on the targeted manufacturing of novel COFs with specific functions.

Thiophene-based covalent organic frameworks for highly efficient iodine capture

Development of adsorbent materials for highly efficient iodine capture is high demand from the perspective of ecological environment and human health. Herein, the two kinds of thiophene-based covalent organic frameworks(COFs) with different morphologies were synthesized by solvothermal reaction using thieno[3,2-b]thiophene-2,5-dicarbaldehyde(TT) as the aldehyde monomer and tri(4-aminophenyl)benzene(PB) or tris(4-aminophenyl)amine(PA) as the amino monomer(denoted as PB-TT COF and PA-TT COF) and the as-prepared two heteroatoms-rich COFs possessed many excellent properties,including high thermal stability and abundant binding sites. Among them, PB-TT COF exhibited ultra-high iodine uptake up to 5.97 g/g in vapor, surpassing most of adsorbents previously reported, which was ascribed to its high specific surface(1305.3 m2/g). Interestingly, PA-TT COF with low specific surface(48.6m2/g) showed good adsorption ability for iodine in cyclohexane solution with uptake value of 750 mg/g,which was 2.38 times higher than that obtained with PB-TT COF due to its unique sheet-like morphology.Besides, the two COFs possessed good reusability, high selectivity and iodine retention ability. Based on experimental results, the adsorption mechanisms of both COFs were studied, revealing that iodine was captured by the physical-chemical adsorption. Furthermore, the both COFs showed excellent adsorption ability in real radioactive seawater treated safely, demonstrating their great potential in real environment.

Critical state to achieve a giant electric field-induced strain with a low hysteresis in relaxor piezoelectric ceramics

Due to the extrinsic contribution of domain wall motions to electro-strains,the incompatibility of the large electro-strain with a low hysteresis in piezoelectric ceramics is a stumbling block for designing high-performance piezoelectrical actuators.Herein,we report a critical state in relaxor ferroelectric systems enables to enhance the electro-strain and to reduce the hysteresis simultaneously.A room temperature ergodic relaxor state dominated by nanodomains with different local symmetries can be obtained by introducing Bi(Zn_(1/2)Ti_(1/2))TiO_(3) into 0.73 Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.27PbTiO_(3) matrix.Like the morphotropic phase boundary(MPB)in ferroelectrics,the coexistence of different local symmetries is capable of facilitating the transition from the ergodic relaxor state to the ferroelectric under the applied field due to the ease of polarization rotation,thereby leading to a giant electro-stain(0.24%)under an electric field of 50 kV/cm.Furthermore,the field-induced ferroelectric state with the long-range ferroelectric order can spontaneously reverse back to the initial ergodic relaxor state during unloading the electric field,which contributes to a low hysteresis(15.4%).The present work not only introduces a solid solution system with excellent electro-strain properties but also affords a guidance for manipulating the electro-strain behavior by modulating phase structures and domain configurations of piezoelectric ceramics.

Large electromechanical strain at high temperatures of novel <001> textured BiFeGaO3-BaTiO3 based ceramics

BiFeGaO3-BaTiO3(BFG-BT)based ceramics with a large piezoelectric coefficient are potential high performance lead-free piezoelectric compounds.In this work,textured and random BFG-BT ceramics were realized by the solid state reaction method with and without BaTiO3(BT)templates.Textured ceramics were obtained by a reactive templated grain growth(RTGG)method leading to a high-temperature electromechanical strain of S=0.27%at 40 kV/cm and to an effective piezoelectric coefficient(d33*)up to 685 pm/V at 180℃.The easy movement of oriented domains enhanced the electromechanical strain under an applied electric field in textured sample(Lotgering factor f=66.3%).Structural investigations reveal that the proportion and degree of distortion of BFG-BT rhombohedral phase(R3c)reached its maximum in textured ceramics,resulting in large ferrodistortive displacements under electric fields.In addition,the dense nanodomains with low domain wall energies,inferred from the high-resolution transmission electron microscope(HR-TEM)observations,contribute to the extra displacement of the textured sample under an applied electric field.In textured ceramics,the remnant polarization was stable(about 17μC/cm2)from room temperature to 180℃,contributing to the stable ferroelectric property at high temperatures.Through the introduction of BT templates,high-density nanodomains were formed and the Burns temperature was enhanced in textured ceramics.The electromechanical strain,polarization and dielectric behavior were correlated to the textured or random forms of the BFG-BT based ceramics.

Relaxor ferroelectric properties of 85PZN–15BT transparent ceramic at low temperatures

Dielectric,hysteresis(P–E)loops and TSDC properties of transparent 85PZN–15BT ceramic over
150–150℃ were investigated.The sample was found to exhibit a strong relaxor behavior and a relatively small remanent polarization.TSDC studies showed that there existed an electric field-dependent peak in the p versus T.Such interesting features were attributed to the electric field-induced transition and coexistence of polar nanoregion,long-range ordered polar region and nonpolarizable BZN-rich region.

Unusual local electric field concentration in multilayer ceramic capacitors

Local electric-field around multitype pores(dielectric pore,interface pore,electrode pore)in multilayer ceramic capacitors(MLCCs)was investigated using Kelvin probe force microscopy combined with the finite element simulation to understand the effect of pores on the electric reliability of MLCCs.Electricfield is found to be concentrated significantly in the vicinity of these pores and the strength of the local electric-field is 1.5e5.0 times of the nominal strength.Unexpectedly,the concentration degree of the pores in the inner electrode is much higher than that in the dielectrics and dielectric-electrode interfaces.Meanwhile,geometry orientations are found to have a remarkable influence on the local electric field strength.The pores act as an insulation degradation precursor via local electric,thermal center,and oxygen vacancies accumulation center.Such unusual local electric field concentration of multitype pores can provide new insights into the understanding of insulation degradation evolution,processing tailoring and design optimization for MLCCs.