It is known that normal liquid can not be shaped like solid. Here we show that if a water droplet is encapsulated in a monolayer of hydrophobic nanoparticles, it can be deformed and shaped almost arbitrarily when the nanoparticles become jammed. One can use mechanical force, electric field, sound field, et al. to manipulate the droplet, adjusting its shape and the diffusion behavior inside it. The achievement of jamming is attributed to the variation of droplet surface area which decreases the distance between particles and thus their interactions. The enhanced Van der Waals forces among particles hold the jamming state even when the droplet surface is increased by water injection. In this report, we will discuss the physics of these phenomena from both macroscopic and microscopic views.

To improve the hydrophobic properties of polyurethane foams for oil spill cleanup, the polyurethane foams with nitrile groups are modified by grafting with oleophilic octadecylamine. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and optical contact angle measuring device are used to characterize the modified polyurethane foam. The results show that the octadecylamine can be successfully grafted onto the polyurethane foam and improves the foam hydrophobicity. The modified foam exhibits a higher contact angle (146.3+2.8◦) compared to the unmodified foam (121.4+3.2◦). Moreover, the water sorption of the modified foam is 0.11g/g which is much lower than that of the unmodified foam (0.84g/g). On the other hand, the sorption capacity of the modified foam for toluene, gasoline and diesel sorption is increased by 20-40%. Therefore, the polyurethane foams modified by octadecylamine can be effectively used in oil/solvent spill cleanup.

In engineering and our daily life, wrinkles normally appear thin membranes or plates in tension, such as the punching of iron sheets, wrinkling of soybean milk and skins. In this study, the Foppl-von Karman plate theory is adopted to investigate the wrinkling of membrane structures, and the model is simplified as an annular thin plate under the tension action of axi-symmetric loads. At first, the Foppl-von Karman plate equation including geometric nonlinearity is derived according to the principle of least potential energy. Then the finite difference method is used to calculate the wrinkle amplitude and radial displacement of the plate. Moreover, the commercial software Ansys is adapted to perform the numerical simulation. The results show that the reason of wrinkles in the plate is that there are annular compressive stresses in a certain area. This investigation is beneficial to the wrinkling process of plates, shells and membranes. It has also laid the foundation of accurate control, stability and vibration cybernetics of these slender structures.

The fine metal mask (FMM) used for the OLED deposition process was fabricated using an electroforming technique, by which Fe-Ni and Fe-Ni-P Invar alloy were electrodeposited on a patterned cathode and then peeled off from it. The coefficient of thermal expansion in the final product of FMM with a thickness of 7µm approached that of the commercially produced Invar alloy using the metallurgical method. The electroformed FMM consists of nanometer-sized grains ranging between 10 and 15 nm. In the Fe-Ni binary Invar electrodeposit, abnormal grain growth took place in heating beyond 380oC and resulted in the texture change from <100>//ND, the major component in the as-deposited state, to the strong development of <111>//ND. This microstructural change indicates a limit of thermal stability in the practical applications. Fe-Ni-P ternary Invar FMM fabricated by addition of phosphorus in electroforming exhibited higher thermal stability due to different microstructures.

Titanium alloys are still most widely used for biomedical applications. These alloys cannot meet all of the clinical requirements; therefore, various surface modifications have been attempted for improving the specific properties. In this research work nanoporous oxide films were produced on titanium alloys surface using a controlled anodic oxidation treatment. The surface morphology, chemical composition and thickness of the anodically oxidized films on the alloys surface were evaluated. The comparative investigation of untreated titanium alloys surface and porous anodic oxide film growth on titanium alloys was carried out to determine the corrosion and tribocorrosion performances in physiological solution. The in situ electrochemical technique used for investigation of tribo-electrochemical degradation was the open circuit potential (OCP) measurement performed before, during and after sliding tests. The results show that controlled anodic oxidation techniques applied can significantly enhance the corrosion and tribo-electrochemical performances of titanium alloys for biomedical applications.

Metal matrix composites are mostly prepared at high temperature near the melting point of the metal or alloys. In the preparation process, it is inevitable that there are different degrees of matrix and the different degrees of interaction and the interfacial reaction of object and the metal matrix alloy enhancement between the interfacial reaction, dissolution and diffusion, element segregation and fiber, whisker and particle reinforced, the formation of different structures of the interface. Interface structure and properties of metal matrix composites performance plays a decisive role, in-depth study and control the influence regulation of the interface reaction and the performance, and effectively control the structure and properties of the interface is the key to obtain high-performance metal matrix composites. More than thirty years to domestic and foreign scholars in metal matrix composites effective preparation methods, rules of interfacial reactions between metal substrate and enhanced, control interface reaction pathways, interfacial micro effect of structure and the performance of interface structure on the properties of the composites, interface structure and preparation process, the relationship between a lot of research work, has achieved many important results.

Sand is commonly produced along with oil and gas pipe. Elbow and Valve often face with the sand-fluid erosion induced to pipe wall thinning or leaking. To study the main mechanism of elbow erosion wear, solid-liquid two-phase flow circulation pipe tests were conducted with adding the 5 present quartz sand. The tests focused on observing the erosion and wear property of a group of carbon steel patches fixing up the pipe elbow with grouping according to particles size after 2~3 hours. The weight loss method was applied to accounting the erosion rate. And then the scanning electron microscopy was employed to study patches damage morphology. The furrows, indentation and scratch, even the circle pits were found on the most of the patches after the eroding. These were shown that some percent iron oxide existing according to energy dispersive spectrum analysis (EDS). It is obvious that the main damage mechanics not only included cutting, extrusion and secondary impact due to elbow fluid field, but also existed the shock wave causing by bubble collapsed on the patch and coexisted corrosion mechanisms. These mechanisms influence are different in the elbow region which was affected by the particle sizes. The test and numerical analysis show that damage mechanism is controlled by erosion of the outer arch wall of the elbow, while cavitation and corrosion are dominant on the inner arch wall of the elbow.

Y2Ti2O7 nano-particle is now used to strengthen ferritic steels, and the mechanical strength of the strengthened steels depends on the dispersion and microstructure stability of the oxide particles. In this case, it is very important and necessary to understand the thermal stability of the nano-particles. Our group prepared Y2Ti2O7 Nanocrystal with different size and shape by Sol-gel Method, the preparation process was monitored by XRD, FT-IR TG-DTA. High-temperature Melt Solution Calorimetry and FESEM were used to analyze the thermodynamics and morphology of the as-prepared products with different size. All the above obtained results were used to investigate their thermal stability.

As an emerging material with exotic properties, liquid marble holds great potential for such areas as microfluidics, stimuli-responsive sensors, micro-chemical reactors, micro-bioreactors, energy harvesting
devices, and mechanical structures. In this study, we mainly concentrate on the mechanical behaviors, such as elasto-plasticity of liquid marble with the decrease of liquid volume. The contact radius with the substrate and Young¡¯s contact angle of liquid marble are both measured with the change of water volume, and those of a water droplet are compared. The mechanism for the different responses for liquid marble and water droplet is clarified according to the mechanics analysis. Moreover, it is found that liquid marble can behave like an elasto-plastic material when the particle surface density is big enough. Based upon this fact, liquid marble can be sculpted to all kinds of special shapes as expected. These investigations may cast new light on how to engineer multifunctional materials and devices, which are beneficial to microprinting and micromachining.

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