重叠系数对电弧增材制造Al-Mg合金的结构和力学性能的影响

本文研究了直接电弧生长制备Al-Mg合金厚壁样品的结构特征和力学性能。由于该制备方法具有高生产率和低成本的优点,在近几十年来得到了特别的关注。该工艺的高生产率使电弧增材制造适用于生产大壁厚的材料。通过改变重叠系数,可以实现厚壁零件的准确成形,并得到指定的尺寸。重叠系数的变化导致材料尺寸、形态以及金属间化合物分布的变化,并影响其力学行为。本文考虑了不同重叠系数下晶粒结构形成的特征,金属间化合物成分及厚壁材料力学性能。发现样品中有两种金属间化合物Mg2Si和Al6(Fe,Mn),它们的大小和形态随重叠系数的变化而改变,从而导致材料力学性能的各向异性。当重叠系数为0.4时,其抗拉强度、屈服强度和伸长率均达到最高值,分别为319 MPa,150 MPa和16.1%。

Stromal and Tumor Glioma-derived Cells with Similar Characteristics Have Differences in α-Smooth Muscle Actin Expression and Localization

Gliomas are solid brain tumors composed of tumor cells and recruited heterogenic stromal components.The study of the interactions between the perivascular niche and its surrounding cells is of great value in unraveling mechanisms of drug resistance in malignant gliomas.In this study,we isolated the stromal diploid cell population from oligodendroglioma and a mixed population of tumor aneuploid and stromal diploid cells from astrocytoma specimens.The stromal cells expressed neural stem/progenitor and mesenchymal markers showing the same discordant phenotype that is typical for glioma cells.Moreover,some of the stromal cells expressed CD133.For the first time,we demonstrated that this type of stromal cells had the typical myofibroblastic phenotype as theα-SMA+cells formedα-SMA fibers and exhibited the specific function to deposit extracellular matrix(ECM)proteins at least in vitro.Immunofluorescent analysis showed diffuse or focalα-SMA staining in the cytoplasm of the astrocytoma-derived,A172,T98G,and U251MG glioma cells.We could suggest thatα-SMA may be one of the main molecules,bearing protective functions.Possible mechanisms and consequences ofα-SMA disruptions in gliomas are discussed.

Example-based dynamic façade design using the façade daylighting performance improvement(FDPI)indicator

It remains challenging to conduct an efficient dynamic façade design.In this article authors try to address this issue introducing the façade daylighting performance improvement(FDPI)indicator aimed to evaluate the performance of a dynamic(adaptive)façade from its daylighting performance point of view.To illustrate the FDPI application the authors introduced the preliminary dynamic façade concept for an office building located in Tel Aviv(Hot-summer Mediterranean Climate Csa)with further shape modification based on the daylighting performance analysis compared to the three alternatives representative of different typologies of dynamic façades.Al Bahr,One Ocean and The University of Southern Denmark façade systems were simulated under the same weather and building conditions of the preliminary dynamic façade concept and were considered as a benchmark for the study.The final dynamic façade concept elaborated by the authors in the preliminary comparative workflow showed noticeable daylight performance improvement with respect to the case studies comparative scenarios.The FDPI metric allowed to estimate a daylighting performance improvement of 43%of the final dynamic façade concept over the case study dynamic façade that showed the best performance in the daylighting simulations.

Corrosion and passive film characteristics of 3D-printed NiTi shape memory alloys in artificial saliva

Electrochemical tests and surface analysis were applied to study the corrosion behavior and passive film characteristics of three-dimensional-printed NiTi shape memory alloys fabricated by laser-powder bed fusion(LPBF) in artificial saliva at 37.C. The passivity of L-PBF NiTi shows to be influenced by the process parameters and resulting morphological and physicochemical surface properties. The results show that the defects at the surface of L-PBF Ni Ti can promote the passivation rate in the early stages of exposure but a slowly formed passive film shows the best corrosion protection. The thickness of the passive film is positively correlated with its corrosion protective performance. The L-PBF NiTi alloy prepared at a linear energy density of 0.2 J·m^(-1) and volumetric energy density of 56 J·mm^(-3) shows the least defects and best corrosion protection. An outer Ti-rich and inner Ni-rich dense passive film could be also obtained showing higher corrosion resistance.

Interfacial engineering of heterostructured carbon-supported molybdenum cobalt sulfides for efficient overall water splitting

Constructing hetero-structured catalyst is promising but still challenging to achieve overall water splitting for hydrogen production with high efficiency.Herein,we developed a sulfide-based MoS_(2)/Co_(l-x)S@C hetero-structure for highly efficient electrochemical hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).The carbon derived from the filter paper acts as a conducting carrier to ensure adequate exposure of the active sites guaranteed with improved catalytic stability.The unique hierarchical nano-sheets facilitate the charge and ion transfer by shortening the diffusion path during electro-catalysis.Meanwhile,the robust hetero-interfaces in MoS_(2)/Co_(1-x)S@C can expose rich electrochemical active sites and facilitate the charge transfer,which further cooperates synergistically toward electro-catalytic reactions.Consequently,the optimal MoS_(2)/Co_(1-x)S@C hetero-structures present small over-potentials toward HER(135 mV@10 mA·cm^(-2))and OER(230 mV@10 mA·cm^(-2)).The MoS_(2)/Co_(1-x)S@C electrolyzer requires an ultralow voltage of 1.6 V at the current density of 10 mA·cm^(-2)with excellent durability,outperforming the state-of-the-art electro-catalysts.This work sheds light on the design of the hetero-structured catalysts with interfacial engineering toward large-scale water splitting.