S14G-humanin restored cellular homeostasis disturbed by amyloid-beta protein

Humanin is a potential therapeutic agent for Alzheimer’s disease, and its derivative, S14G-humanin, is 1 000-fold stronger in its neuroprotective effect against Alzheimer’s disease-relevant insults. Alt-hough effective, the detailed molecular mechanism through which S14G-humanin exerts its effects remains unclear. Data from this study showed that fibril ar amyloid-beta 40 disturbed cel ular ho-meostasis through the cel membrane, increasing intracel ular calcium, generating reactive oxygen species, and decreasing the mitochondrial membrane potential. S14G-humanin restored these re-sponses. The results suggested that S14G-humanin blocked the effects of amyloid-beta 40 on the neuronal cel membrane, and restored the disturbed cel ular homeostasis, thereby exerting a neuroprotective effect on hippocampal neurons.

Vapour–Liquid Equilibrium for N,N-Dimethylformamide + Benzene + Thiophene via Gibbs Ensemble Molecular Simulation

The selection and design of an optimal solvent for extractive distillation require reliable vapour-liquid phase equilibrium data and knowledge of extraction mechanisms.Compared with time-consuming experiments,molecular simulation presents great potential in research on the properties of fluids.Therefore,in this work,Gibbs ensemble Monte Carlo was applied to successfully predict the vapour-liquid phase equilibrium data of binary and ternary systems containing benzene,thiophene and N,Ndimethylformamide(DMF) at P=101.3 kPa.The explicit hydrogen version of the transferable potentials for phase equilibria potential model was chosen for benzene and thiophene,whereas the OPLS potential model was selected for DMF.The predicted phase diagrams were compared with experimental data and the UNIQUAC thermodynamic model.A good agreement was obtained,which corroborated the validity of the potential models.In addition,the extraction mechanism was explored by radial distribution function(RDF) of the liquid-phase structure.The RDFs showed that thiophene and benzene shared a similar liquidphase structure because of the intermolecular interaction.The distinct difference between the RDFs of DMF/benzene and those of DMF/thiophene is that the oxygen atom of DMF is more associated with hydrogen atoms of thiophene than that of benzene,which may be responsible for the extraction effect of DMF.

Review of permeability evolution model for fractured porous media

The ability to capture permeability of fractured porous media plays a significant role in several engineering applications, including reservoir, mining, petroleum and geotechnical engineering. In order to solve fluid flow and coupled flow-deformation problems encountered in these engineering applications,both empirical and theoretical models had been proposed in the past few decades. Some of them are simple but still work in certain circumstances; others are complex but also need some modifications to be applicable. Thus, the understanding of state-of-the-art permeability evolution model would help researchers and engineers solve engineering problems through an appropriate approach. This paper summarizes permeability evolution models proposed by earlier and recent researchers with emphasis on their characteristics and limitations.

Sandwich-like Heterochromophore Metallo-Supramolecules Based on Dense Chromophore Arrangements with Energy and Chirality Transfer Properties

Multichromophoric architectures with wellorganized chromophoric arrangements are of vital importance to gain insights into interchromophoric interactions.Herein,we report a novel heteroleptic self-assembly strategy and construct three achiral and one chiral sandwich-like heterochromophore complexes(Zn_(4)L^(G)L^(A-C)_(2)and Zn_(4)L_(G)L^(D)_(2)).Possible dynamic products,including homoleptic oligomers and isomers,are eliminated,producing achiral complexes with exceptional purity.Isomers are observed in chiral complexes due to the flexible geometry of LD.Perfectly aligned chromophore arrangements with precise spacing and orientations are evidenced by single-crystal X-ray diffraction.The distinct segments in the ligands lead to different interchromophoric interactions.Impressively,energy transfer and tunable emission,including white-light emission,are achieved for Zn_(4)L^(G)L^(A)_(2)and Zn_(4)L^(G)L^(B)_(2).In addition,chirality transfer is observed for Zn_(4)L_(G)L^(D)_(2),due to conformational restriction from chiral LD,leading to chiral rotational conformations of tetraphenylethylene moiety in LG.

信息技术教师流失现象的形成机理——一项扎根理论研究

中小学信息技术教师一直以来没有得到足够关注,人员流失现象比较严重。为了探寻流失问题的根源,以多名中小学信息技术教师为研究对象,采用扎根理论的路径展开了深入研究。研究结果表明,流失过程中的信息技术教师面临一个普遍的生存困境,即杂事缠身。在其影响下,信息技术教师的职责与现实之间形成了一条非常明显的裂缝,他们由此在实务工作中发展出四种典型的行为策略,并最终一步一步走向流失。进一步的理论解读表明,信息技术教师杂事缠身并最终走向离职的根本原因在于信息技术的工具性本质及人们的运用观念或文化的滞后性,同时也是他们基于利益交换进行身份协商的必然结果。

An online data driven actor-critic-disturbance guidance law for missile-target interception with input constraints

In this article,we develop an online robust actor-critic-disturbance guidance law for a missile-target interception system with limited normal acceleration capability.Firstly,the missiletarget engagement is formulated as a zero-sum pursuit-evasion game problem.The key is to seek the saddle point solution of the Hamilton Jacobi Isaacs(HJI)equation,which is generally intractable due to the nonlinearity of the problem.Then,based on the universal approximation capability of Neural Networks(NNs),we construct the critic NN,the actor NN and the disturbance NN,respectively.The Bellman error is adjusted by the normalized-least square method.The proposed scheme is proved to be Uniformly Ultimately Bounded(UUB)stable by Lyapunov method.Finally,the effectiveness and robustness of the developed method are illustrated through numerical simulations against different types of non-stationary targets and initial conditions.

Stability analysis on tunnels with karst caves using the distinct lattice spring model

The effects of karst caves on tunnel stability were numerically investigated using the distinct lattice spring model(DLSM).The DLSM was validated by investigating the mechanical behavior of Brazilian discs with various sizes of central circular holes.Then,the effects of karst cave on U-shaped tunnel were investigated under various karst caves positions(top,bottom,and right side of the tunnel),tunnelcave distances(0.5-4 times the radius of the tunnel arc),and cave shapes(circular,rectangular flat,and rectangular vertical caves).The failure processes of the tunnel under those various conditions were analyzed and both the failure process and the final failure patterns of the tunnel were discussed.Numerical simulation demonstrated that karst caves around the tunnel could weaken the stability of the tunnel,indicating tunnel-cave distance effects.The closer the cave to the tunnel,the weaker the tunnel under loading.This effect was not significant when the tunnel-cave distance(d)was larger than three times the tunnel arc radius(R).In addition,the final failure pattern of the tunnel and its surrounding rock mass were dependent on both the position and the size of the cave.The larger the cave,the weaker the tunnel and its surrounding rock mass.Furthermore,compared with those cases with top and bottom caves,the tunnel with a right side cave had more impacts on tunnel stability.The main research finding could help engineers carry out stability analysis on tunnels in karst areas and take effective measures to enhance tunnel stability.

Rerouting end-face-TIR capable rays to significantly increase evanescent wave signal power

The critical findings associated with end-face total internal reflection （TIR） phenomemon we proved before are reported. In particular, these findings reveal that the end-face-TIR capable rays experience enormous mode mixing when encountering a roughened end face. As a result, 94% of the overall detectable power is contributed by this effect. With a smooth fiber end face, this figure is mere 52%. We interpret the mechanism behind these unusual phenomena and its significance for the performance enhancement of fiber optic evanescent wave sensor.