“从天而降的”Vertu移动亭

Vertu移动亭是MAD事务所创始人马岩松先生及主持建筑师党群,携其中外设计团队共同打造的一个极富个性的移动亭建筑。移动建筑概念原型是希望创造一个从天而降并坠至展场的物件而来,并且进一步透过此般充满冲击力的物件来影响与改变参展著对于空间还有时间上的体验。Vertu移动亭的形体发展源于自然界中如爆炸,碎裂,扭曲等物理性力量的观察与研究所并发的概念。一个布满尖锐碎     

Combined numerical/experimental investigation of particle diameter and interphase effects on coefficient of thermal expansion and young's modulus of SiO2/epoxy nanocomposites

A combined numerical/experimental approach is used to study the effects of the particle/matrix interphase on the coefficient of thermal expansion (CTE) and Young's modulus of SiO₂/epoxy nanocomposites having nanoparticle reinforcements of different sizes. Our experiments showed that the composite CTE decreases and composite Young's modulus increases with decreasing nanoparticle diameter at the same volume fraction, but our finite element (FE) model predictions did not match the expected trends when the interphase was not accounted for. The new models include an interphase region around the nanoparticle which results in an “effective particle volume fraction” that is larger than the actual particle volume fraction. The results from the models are compared with the experimental results and the new models are accurately fitted to the experimental results using the interphase thickness as a curve‐fitting parameter. We believe that this is the first published report on the use of combined numerical/experimental investigations of both elastic stiffness and thermal expansion characteristics to demonstrate the existence of a particle size‐dependent “effective particle volume fraction” due to the particle/matrix interphase region in a nanoparticle‐reinforced composite. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers     

Highly scalable nanoparticle–polymer composite fiber via wet spinning

Magnetic nanoparticles have continued to gather the interest of researchers due to the unique physical properties of materials found at this size scale. Herein, the production of composite magnetic fibers composed of iron oxide nanoparticles suspended in alginate is described. These materials were produced via wet spinning of a sodium alginate solution into a bath of an aqueous solution of calcium chloride. The magnetic fibers were found to have similar mechanical properties to normal alginate fibers, and exhibited superparamagnetic behavior when subjected to an external DC magnetic field. In addition, the particle loaded fibers demonstrated the potential to produce significant amounts of heat when exposed to an AC magnetic field, suggesting these new materials could be applicable to a variety of applications including magnetic hyperthermia. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1975–1980, 2013     

Multiscale Fatigue Life Prediction for Composite Panels

Fatigue life prediction capabilities have been incorporated into the HyperSizer Composite Analysis and Structural Sizing Software. The fatigue damage model is introduced at the fiber/matrix constituent scale through HyperSizer’s coupling with NASA’s MAC/GMC micromechanics software. This enables prediction of the micro scale damage progression throughout stiffened and sandwich panels as a function of cycles leading ultimately to simulated panel failure. The fatigue model implementation uses a cycle jumping technique such that, rather than applying a specified number of additional cycles, a specified local damage increment is specified and the number of additional cycles to reach this damage increment is calculated. In this way, the effect of stress redistribution due to damage-induced stiffness change is captured, but the fatigue simulations remain computationally efficient. The model is compared to experimental fatigue life data for two composite facesheet/foam core sandwich panels, demonstrating very good agreement.     

Semi-Empirical Molecular Modeling of Ionic Liquid Tribology: Ionic Liquid–Hydroxylated Silicon Surface Interactions

The interactions between selected ionic liquids and modified silicon surfaces are modeled in this article using semi-empirical methods. The modeled ionic liquids include a series of ionic liquids consisting of imidazolium derivatives with Cl^? as the anion interacting with hydroxylated silicon wafers. A second series consists of symmetrical and asymmetrical dicationic imidazolium derivatives with PF₆ ^? or BF₄ ^? as the anion interacting with hydroxylated single crystal silicon wafers. The tribological properties of these ionic liquids and their interactions with silicon surfaces are modeled using a rolling hydroxylated silicon surface. The ionic liquids are allowed to form a complex with this surface, and the enthalpies of complex formation are seen to correlate with the tribological properties of the ionic liquids.     

Microstructure and Creep Behavior of High-Pressure Die-Cast Magnesium Alloy AE44

The microstructure and creep behavior of a high-pressure die-cast AE44 (Mg-4Al-4RE) alloy have been studied. The creep properties were evaluated at 423?K and 448?K (150?°C and 175?°C) under stresses in the range 90 to 110?MPa. The microstructures before and after creep were examined by transmission electron microscopy (TEM). After creep, AE44 exhibits anomalously high stress exponents (n ?= 67 at 423?K [150?°C] and n ?= 41 at 448?K [175?°C]) and stress-dependant activation energies ranging from 221 to 286?kJ/mol. The dislocation substructure developed during creep is characterized by extensive nonbasal slip and isolated but well-defined subgrain boundaries. It is shown that the anomalously high stress exponents cannot be rationalized by the threshold stress approach that is commonly adopted in analyzing the creep behavior of dispersion-strengthened alloys or metal matrix composites. A comparison in creep resistance is also made between AE44 and AE42 (Mg-4Al-2RE).     

Discovery of N-Aryloxypropylbenzylamines as Voltage-Gated Sodium Channel NaV1.2-Subtype-Selective Inhibitors

We previously reported that a lipophilic N-(4′-hydroxy-3′,5′-di-tert-butylbenzyl) derivative ( 1 ) of the voltage-gated sodium channel blocker mexiletine, was a more potent sodium channel blocker in vitro and in vivo. We demonstrate that replacing the chiral methylethylene linker between the amine and di-tert-butylphenol with an achiral 1,3-propylene linker (to give ( 2 )) maintains potency in vitro. We synthesized 25 analogues bearing the 1,3-propylene linker and found that minor structural changes resulted in pronounced changes in state dependence of blocking human Na_V1.2 and 1.6 channels by high-throughput patch-clamp analysis. Compared to mexiletine, compounds 1 and 2 are highly selective Na_V1.2 inhibitors and >500 times less potent in inhibiting Na_V1.6 channels. On the other hand, a derivative (compound 4 ) bearing 2,6-dimethoxy groups in place of the 2,6-dimethyl groups found in mexiletine was found to be the most potent inhibitor, but is nonselective against both channels in the tonic, frequency-dependent and inactivated states. In a kindled mouse model of refractory epilepsy, compound 2 inhibited seizures induced by 6 Hz 44 mA electrical stimulation with an IC₅₀ value of 49.9±1.6 mg kg⁻¹. As established sodium channel blockers do not suppress seizures in this mouse model, this indicates that 2 could be a promising candidate for treating pharmaco-resistant epilepsy.     

An Investigation into the Nature of the Oxide Layer Formed on Kovar (Fe–29Ni–17Co) Wires Following Oxidation in Air at 700 and 800 °C

This work provides new insight and evidence that challenges and extends the accepted view of the oxidation behaviour of Kovar (ASTM-15). Specimens of 2 mm diameter Kovar wire were oxidised in air at 700 or 800 °C for 10 min. The resulting oxide layers were analysed by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy, scanning transmission electron microscopy and Raman spectroscopy. Oxide layers of approximately 2 and 4 µm thickness were formed at 700 and 800 °C, respectively. These were found to contain iron, cobalt and traces of nickel. The combination of analysis techniques revealed that the oxide contains Fe₂O₃ in addition to (Fe, Co, Ni)₃O₄, a spinel oxide, in contrast to the combinations of Fe₃O₄, Fe₂O₃ and FeO that are typically reported. The oxide layer was found to be complex, consisting of multiple layers with different compositions, which is overlooked in the existing literature.