Tribological Properties and Film Formation Behavior of Thermoreversible Gel Lubricants

The tribological properties of a new and unique thermoreversible gel lubricant (TR gel lube) were investigated. TR gel lube, which includes 10–40% of amide-type gelling agent in base fluid, is able to repeatedly alter or convert phase from gel state to liquid state at the melting point of the gelling agent. High-pressure rheological tests were performed in order to characterize the behavior of base oil and TR gel lube as a function of pressure and temperature. The effect of TR gel lube on ball bearing fatigue life was carried out by systematic tests using thrust ball bearings. The results of L ₁₀ life tests of TR gel lube showed a longer life than the conventional greases. This result was investigated from the oil film formation. It was found that the gelling agent played a key role in the lubricating properties. Some mechanisms such as adsorbed film formation and solid-like formation are proposed.     

Cathodic pulse breakdown of anodic films on aluminium in alkaline silicate electrolyte – Understanding the role of cathodic half-cycle in AC plasma electrolytic oxidation

Sequential anodic and cathodic pulse voltages were applied on anodised Al micro-electrodes in alkaline silicate electrolyte to explore the role of cathodic pulse in AC or bipolar plasma electrolytic oxidation (PEO) process. SEM observation was carried out to observe the sites of anodic and cathodic breakdown and their morphologies. The prior anodic breakdown accelerated the cathodic breakdown at ?50 V, and the acceleration was associated with the preferential cathodic breakdown at the anodic breakdown sites. However, the succeeding anodic breakdown during applying anodic pulse of 420 V for 2 ms was highly suppressed at the cathodic breakdown sites. This would randomise the anodic breakdown sites. Such role may contribute to the formation of rather uniform coatings on aluminium in this electrolyte without large discharge channels when larger cathodic current is applied with respect to the anodic current in AC PEO.     

One-step route to a hybrid TiO2/TixW1?xN nanocomposite by in situ selective carbothermal nitridation

Metal oxide/nitride nanocomposites have many existing and potential applications, e.g. in energy conversion or ammonia synthesis. Here, a hybrid oxide/nitride nanocomposite (anatase/Ti_xW_1−xN) was synthesized by an ammonia-free sol–gel route. Synchrotron x-ray diffraction, complemented with electron microscopy and thermogravimetric analysis, was used to study the structure, composition and mechanism of formation of the nanocomposite. The nanocomposite contained nanoparticles (<5 nm diameter) of two highly intermixed phases. This was found to arise from controlled nucleation and growth of a single oxide intermediate from the gel precursor, followed by phase separation and in situ selective carbothermal nitridation. Depending on the preparation conditions, the composition varied from anatase/Ti_xW_1−xN at low W content to an isostructural mixture of Ti-rich and W-rich Ti_xW_1−xN at high W content. In situ selective carbothermal nitridation offers a facile route to the synthesis of nitride-oxide nanocomposites. This conceptually new approach is a significant advance from previous methods, which generally require ammonolysis of a pre-synthesized oxide.     

Highly dispersed titanium(IV) oxide on α-cellulose surface: An XPS,SEM, and XRD study

Interaction of titanium chloride with a cellulose surface and the decurrent modifications introduced on its morphology were studied by scanning, electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The chemical analysis of the surface was carried by X-ray photoelectron spectroscopy (XPS) and changes in the crystallinity upon chemical treatment was determinded by the X-ray diffraction (XRD) technique. Interaction of titanium with cellulose occurs only at the surface and a decrease of its crystallinity was observed with the amount of metal oxide incorporated into the solid matrix. © 1995 John Wiley & Sons, Inc.     

Role of Phosphate Groups in the Calcium Sensitivity of αs2-Casein

In order to explain the higher calcium sensitivity of α_s2-casein than other casein constituients, properties of α_s2-casein and dephosphorylated α_s2-casein were examined and compared with those of α_s1-casein. α_s2-Casein was more sensitive to calcium than α_s1-casein. Aggregates of calcium α_s1- and α_s2-caseinates were both thoroughly solubilized by 4 M urea. Gel filtration of α_s1-casein and of α_s2-casein in 4 M urea showed the same elution pattern in the presence and absence of 10 mM calcium chloride. Dephosphorylated α_s2-casein was insoluble at neutral pH although dephosphorylated α_s1-casein was soluble. Dephosphorylated α_s2-casein was solubilized by 4 M urea and alkalization to pH 11. The net proton charge, calculated from the primary structure, of dephosphorylated α_s2-casein was very low at pH 7.0, although dephosphorylated α_s1-casein has a considerable number of negative net charges. The calculated isoionic point of dephosphorylated α_s2-casein, which contains one phosphate group, was 6.98. Ester phosphate groups of α_s2-casein play an important role in its solubilization at neutral pH and neutralization of ionized phosphate groups by calcium ion increases hydrophobic interaction, which leads to precipitation.     

New design for the high-performance drive system for DC brushless motor

The dc brushless motor, permanent magnet-type synchronous motor (PM motor), has been used widely in industrial robots, the machine tools for factory, and factory automations. Therefore, it is more desirable to improve the performance of the PM motor variable speed control system. Although only the torque component current is adjusted as the control method for the PM motor, so-called Vector Control, it is expected that the developed characteristics will be added to the PM motor. In this paper, new driving methods for the PM motor and a new design method for the variable speed control system are presented. The new motor driving methods which bring to the PM motor a new driving performance, e.g., a quick transient response or high-efficiency motor driving, can be implemented by controlling not only the torque component current, but also the magnetizing component current. A developed optimal control theory, i.e., the error system technique, is employed for designing the control system. The control law is endowed with a steady robustness against the variation of the system parameters and the ability of compensating the delay time due to the control processing. The effectiveness of the proposed method is confirmed by simulations and experiments.     

Scalability and homogeneity of slot die‐coated metal oxide semiconductor for TFTs

An indium oxide‐based precursor solution has been developed by spin coating method. In order to apply this material to mass production, material, process, and equipment optimizations for slot die coating have been implemented. Slot die coating is a cost‐effective and scalable process and already applied to photoresist materials in the display industry. The indium oxide‐based precursor solution has been coated on bare glasses and thin‐film transistor substrates by a mass production‐type slot die coater. Mobility of over 10 cm²/Vs is achieved for the first time for a large area at an annealing temperature of 350 °C. The homogeneity of the film will be presented.     

Using model uncertainty for robust optimization in approximate inference control

Recently, the optimization-by-inference approach has been proposed as a new means for solving high-dimensional optimization problems quickly. Approximate Inference COntrol (AICO) is one of the most successful and promising methods that implement the optimization-by-inference approach. AICO is able to solve stochastic optimal control problems and has already been successfully used in many applications. However, it is known that the iterative inference of AICO sometimes fails to converge to the optimal solution. To make the optimization more robust, in this paper, we propose to take model uncertainty into account. In AICO, the cost function to be minimized is accurate around a particular state of a given stochastic system, but the accuracy is uncertain in regions far from that state. Because using such an uncertain function is harmful to the convergence, we modify AICO, so that it does not use the function in uncertain regions. Our method is easy to implement and does not add much computational time to the original AICO. Experiments using two different scenarios show that our method substantially improves AICO in terms of the rate at which the algorithm produces convergent results.     

Preparation of copoly(vinyl alcohol–styrenesulfonic acid) resin and its catalytic activity on hydrolysis of carbohydrates. II. Two-step polymerization using tetraethylthiuram disulfide as an initiator

Copoly(vinyl alcohol–styrenesulfonic acid) resin was prepared by a two-step polymerization, consisting of a suspension polymerization of styrene containing divinylbenzene using tetraethylthiuram disulfide as an initiator and a subsequent block copolymerization of vinyl acetate to the crosslinked polystyrene obtained, followed by sulfonation and saponification. Some reaction conditions in the polymerization of styrene were investigated to obtain copolymer containing more vinyl alcohol units. The catalytic activity of the copolymer on the hydrolysis of dextrin was investigated and found to be increased with increasing amount of vinyl alcohol units and with a lowering degree of crosslinking of the copolymer. The maximum acceleration of rate obtained in the presence of the copolymer was about six times that in the presence of Amberlite 120B. Catalytic activity of the copolymer on hydrolysis of sucrose and methyl acetate were also investigated and found to be comparable each other and lower than that for dextrin. The difference between the activities for dextrin and for sucrose and methyl acetate increased with an increasing amount of vinyl alcohol units in the copolymer.     

Hydrolysis of cellulose fiber in the presence of 12-tungstosilicic acid

Hydrolysis of cellulose fiber in the presence of 12-tungstosilicic acid was investigated, and the acid was found to show a higher catalytic activity than did hydrochloric acid at the same concentration of acid, although the ratio of the activities of 12-tungstosilicic acid to hydrochloric acid depended on the concentration. The influence of the ionic strength on the reaction rates was examined, and it was believed that the difference in the ionic strength between 12-tungstosilicic acid and hydrochloric acid at the same concentration of acid was one of reasons for the higher catalytic activity of 12-tungstosilicic acid. From the examinations of change in degree of polymerization of the cellulose fiber with the hydrolysis and adsorption behavior of 12-tungstosilicic acid by the cellulose, fiber, it was found that 12-tungstosilicic acid, in spite of its bulky structure, easily penetrated into the amorphous region of the cellulose fiber, as does hydrochloric acid, and catalyzed the hydrolysis of glucoside bond there.