Development of Maximum Bubble Pressure Method for Surface Tension Measurement of High Viscosity Molten Silicate

A surface tension measurement method based on the maximum bubble pressure (MBP) method was developed in order to precisely determine the surface tension of molten silicates in this study. Specifically, the influence of viscosity on surface tension measurements was quantified, and the criteria for accurate measurement were investigated. It was found that the MBP apparently increased with an increase in viscosity. This was because extra pressure was required for the flowing liquid inside the capillary due to viscous resistance. It was also expected that the extra pressure would decrease by decreasing the fluid velocity. For silicone oil with a viscosity of \(1000\,\hbox {mPa}{\cdot }\hbox {s}\), the error on the MBP could be decreased to +1.7 % by increasing the bubble detachment time to \(300\,\hbox {s}\). However, the error was still over 1 % even when the bubble detachment time was increased to \(600\,\hbox {s}\). Therefore, a true value of the MBP was determined by using a curve-fitting technique with a simple relaxation function, and that was succeeded for silicone oil at \(1000\,\hbox {mPa}{\cdot } \hbox {s}\) of viscosity. Furthermore, for silicone oil with a viscosity as high as \(10\,000\,\hbox {mPa}{\cdot }\hbox {s}\), the apparent MBP approached a true value by interrupting the gas introduction during the pressure rising period and by re-introducing the gas at a slow flow rate. Based on the fundamental investigation at room temperature, the surface tension of the \(\hbox {SiO}_{2}\)–40 \(\hbox {mol}\%\hbox {Na}_{2}\hbox {O}\) and \(\hbox {SiO}_{2}\)–50 \(\hbox {mol}\%\hbox {Na}_{2}\hbox {O}\) melts was determined at a high temperature. The obtained value was slightly lower than the literature values, which might be due to the influence of viscosity on surface tension measurements being removed in this study.     

Self‐Healing Micellar Ion Gels Based on Multiple Hydrogen Bonding

Ion gels, composed of macromolecular networks filled by ionic liquids (ILs), are promising candidate soft solid electrolytes for use in wearable/flexible electronic devices. In this context, the introduction of a self‐healing function would significantly improve the long‐term durability of ion gels subject to mechanical loading. Nevertheless, compared to hydrogels and organogels, the self‐healing of ion gels has barely investigated been because of there being insufficient understanding of the interactions between polymers and ILs. Herein, a new class of supramolecular micellar ion gel composed of a diblock copolymer and a hydrophobic IL, which exhibits self‐healing at room temperature, is presented. The diblock copolymer has an IL‐phobic block and a hydrogen‐bonding block with hydrogen‐bond‐accepting and donating units. By combining the IL and the diblock copolymer, micellar ion gels are prepared in which the IL phobic blocks form a jammed micelle core, whereas coronal chains interact with each other via multiple hydrogen bonds. These hydrogen bonds between the coronal chains in the IL endow the ion gel with a high level of mechanical strength as well as rapid self‐healing at room temperature without the need for any external stimuli such as light or elevated temperatures.     

Autonomic healing and welding by interdiffusion of dangling chains in a weak gel

Entanglement couplings of dangling chains in a weak gel are found to be applicable to the design of a self‐repairing polymer. It is confirmed that a cleavage applied using a razor blade is healed at room temperature without any manual intervention. Further, the healing efficiency is improved when the molecular weight of a prepolymer, which affects the length of dangling chains, is high. Because the healing occurs by interdiffusion of dangling chains, the relation between ambient temperature and glass transition temperature determines the time required for healing. In other words, a soft rubbery material whose glass transition temperature is lower than room temperature shows immediate healing. A weak gel whose tensile modulus is 100 MPa at room temperature, i.e. a leather‐like material, shows healing even at room temperature in a relatively short time (ca 2 h). Finally, when a weak gel shows crystallinity, healing occurs at a temperature above the melting point. Because the material has a permanent network structure, it will not show macroscopic flow even after exposure to high temperature. Copyright © 2011 Society of Chemical Industry     

Characterization of cellular motions through direct observation of individual cells at early stage in anchorage-dependent culture

In the monolayer culture of murine fibroblasts, the characterization of cellular motions was performed by morphological observation using a tool consisting of an optical assembly connected to a computer-aided image analysis system. This tool enabled the estimation of the projected area of the cells with sufficient accuracy, being able to follow the serial behavior of the cells on the culture surface. Trypsinization was chosen as an external factor for altering the state of the cells, and the rate of cell spreading (r(S)) and time of first cell division (t1) were evaluated by subjecting the cells to trypsin treatment for t(T)=3 and 15 min. During culture of the cells treated for t(T)=3 min, the r(S) values of individual cells exhibited a broad variation, ranging from 41 to 321 microm2/h, and the average r(S) was 165+/-78 microm2/h , which was 1.5 times larger than that of the cells treated for t(T)=15 min. On the contrary, the average t1 of the cells treated for t(T)=3 min was 9.5 h which was 60% reduced as compared with that of the cells treated for t (T)=15 min. The prolonged time of trypsin treatment was considered to induce the decrease in r(S) and delay of the first cell division due to the requirement for the recovery from cell surface damage caused by trypsinization. The logarithmic plots of r(S) and t1 were found to have an inverse relation regardless of the state of the individual cells.     

First-principles molecular-dynamics calculations on chemical reactions and atomic structures induced by H radical impinging onto Si(001)2 x 1:H surface

Chemical reactions between hydrogen terminated Si(001)2 x 1 surface and impinging H radical are investigated by means of first-principles molecular-dynamics simulations. Reaction probabilities of abstraction of surface terminating H atom with H2 formation, adsorption onto Si surface and reflection of impinging H atom are analyzed with respect to the kinetic energy of incident H radical. The probabilities of abstraction and adsorption turn out to be ranging from 0.81 to 0.58 and from 0.19 to 0.42, respectively, while that of reflection almost zero. As initial kinetic energy of the impinging atom increases, the reaction probability of abstraction decreases and that of absorption increases. Metastable H-absorbed atomic configurations are also derived by optimizing the structures obtained in the impinging dynamics calculations. They are candidates of the so-called reservoir site which is a key to understand the unity hydrogen coverage observed after an exposure to gaseous H atom ambient despite existing residual vacant sites due to abstraction.     

Condensation and Collapse of Vapor Bubbles Injected in Subcooled Pool

We focus on condensation and collapse processes of vapor bubble(s) in a subcooled pool. We generate the vapor in the vapor generator and inject it/them to form vapor bubble(s) at a designated temperature into the liquid at a designated degree of subcooling. In order to evaluate the effect of induced flow around the condensing/collapsing vapor bubble, two different boundary conditions are employed; that is, the vapor is injected through the orifice and the tube. We also focus on interaction between/among the condensing/collapsing vapor bubbles laterally injected to the pool. Through this system we try to simulate an interaction between the vapor bubble and the subcooled bulk in a complex boiling phenomenon, especially that known as MEB (microbubble emission boiling) in which a higher heat flux than critical heat flux (CHF) accompanying with emission of micrometer-scale bubbles from the heated surface against the gravity is realized under a rather high subcooled condition.     

Styryl silsesquioxane photoresist

There is a substantial need for photopattern‐able, heat resistant, and transparent materials that are applicable to electronic devices, such as imaging or display elements. Styryl silsesquioxane based photoresist forms thin micro patterns after i‐line exposure and alkaline development, and the resulting transparent film shows remarkable heat resistance. Radicals generated from a photoinitiator induce polymerization of styryl functionality in the photoresist film to form the micropatterns. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41459.