Performance of compression/absorption hybrid refrigeration cycle with propane/mineral oil combination

This paper discusses the feasibility of a vapor compression/absorption hybrid refrigeration cycle for energy saving and utilization of waste heat. The cycle employs propane as a natural refrigerant and a refrigeration oil as an absorbent. A prototype of the cycle is constructed, in which a compressor and an absorption unit are combined in series. The performance of the cycle is examined both theoretically and experimentally. Although the solubility of the propane with the oil is not enough as a working pair in the absorption unit, the theoretical calculation shows that the hybrid cycle has a potential to achieve a higher performance in comparison with a simple vapor compression cycle by using the waste heat. In the experiment, the prototype cycle is operated successfully and it is found that an improvement of an absorber is necessary to achieve the good performance close to the theoretical one. The application of an AHE (absorber heat exchanger) can reduce the heat input to a generator. Further examinations on some other combinations of refrigerant/refrigeration oil and additives are desirable.     

Tuning-current splitting network for three-section DBR lasers

A simple current-splitting network for DBR-laser frequency tuning is proposed that distributes a single control current among two tuning sections and can adjust the current distribution without yielding impedance mismatching. The nonlinear characteristics of the tuning sections realise the non-proportional current splitting suitable for continuous tuning; 470 GHz (3.8 nm) tuning range is achieved     

Manipulating the chemical affinity and kinetics of 3D silica particle network via the phase-separation technique

We developed a simple and versatile technique for a particle’s self-organizing-network based on a non-solvent induced micro-phase separation (NIPS). When a good solvent vaporizes from a particle dispersion in a ternary solution including the polymer, good solvent and non-solvent, the suspension is separated into the polymer network and non-solvent phase. If the affinity between the particles and polymer is sufficient enough, the particles are entrapped in the polymer network and particle network can be achieved. To expand this technique to particles with various physical properties, the surface of the particles was identified using the Hansen dispersibility parameter (HDP). From a comparison of the HDP of the unmodified and modified silica, an NH₂ group is suitable for entrapment of the silica by cellulose acetate as the polymer. However, with an increase in number of the silica particles, entrapment of the silica in the polymer was prevented. Control of the phase separation rate by the lowering temperature leaded to entrapment of silica particles in the polymer network. The proposed technique is effective not only for spherical oxide particles, but also for non-oxides, various shapes and structures. Depending on particle characteristics, functional films and bulk materials for thermal insulation, light diffusion, and electro conductivity can be obtained.     

Interphase transfer of tackifier between poly(butadiene) and poly(styrene-co-butadiene)

The interphase transfer behavior of poly(styrene-co-α-methyl styrene), which is known as a tackifier in rubber industry, is investigated using poly(butadiene) rubber (BR) and poly(styrene-co-butadiene) rubber (SBR). The films of pure rubbers and the blends with the tackifier were prepared by a solution-cast method using toluene as a solvent. Two sheets composed of different rubbers, in which the tackifier was mixed at least in one rubber sheet, were piled together and annealed beyond the glass transition temperature T _g of the tackifier. The transfer phenomenon of the tackifier between the sheets was evaluated by the peak shift in the tensile loss modulus E″ curve, ascribed to T _g of the rubbers, which was measured by the dynamic mechanical analysis. Moreover, crystallization temperature of BR was also employed as a measure of the transfer, because the tackifier retards the crystallization of BR. It is found that the tackifier moves from one rubber to another during annealing procedure to reduce severe localization. When the content is the same in each rubber, the tackifier immigrates from BR to SBR, suggesting a better miscibility with SBR. This behavior is attributed to the small difference in the solubility parameter between SBR and the tackifier as compared to that between BR and the tackifier.     

Novel properties of new type conducting and insulating polymers andtheir composites

Novel properties of recently developed conducting and insulating polymers and their composites are discussed. Properties of conducting polymer whose main chains are composed of unsaturated π-bonds depend strongly on the main chain structure, substituent and also molecular dopants. Various applications of conducting polymers such as electroluminescence (EL) elements, electrolyte capacitors, photoconductors, photovoltaic cells, superconductors and insulators at cryogenic temperature, are discussed by taking effects of molecular dopants such as C₆₀ into consideration. A new type of insulating polymer, syndiotactic polypropylene prepared by newly developed metallocene catalysts has been studied and found to exhibit much superior electrical, thermal and mechanical characteristics compared with those of conventional isotactic polypropylene, atactic polypropylene and polyethylene. These excellent characteristics originate from lower crystallinity, smaller spherulites and different crystal lattice than in isotactic polypropylene. Negligible degradation of syndiotactic polypropylene by contact with copper is interpreted in terms of difference of catalysts and suppression of diffusion of copper cation. New types of conducting polymer, insulating polymer composites were prepared. Their conductivity was controlled over more than 10 orders of magnitude by small amounts of a conducting polymer, polypyrrole, which can be interpreted in terms of the percolation model depending on the shape and density of polypyrrole coated insulating polymer particles. Nonlinear current-voltage characteristics were also studied     

Investigation of reacting flow fields in miscible viscous fingering by a novel experimental method

The reacting flow fields in reactive miscible viscous fingering in a Hele‐Shaw cell studied by Nagatsu and Ueda had not been completely elucidated, mainly because one cannot exactly recognize where and when the reaction takes place in the reactive fingering pattern. We developed a novel experimental method that allowed us to identify the reaction region in the fingering pattern employed in the previous studies. The novel method involves switching of the less‐viscous liquid injected in both the nonreactive and reactive experiments. By using the novel method, we succeeded in showing how the reaction region in the fingering pattern was affected by the initial reactant concentrations, the Péclet number, and time. We propose physical models of the reacting flow field in the cell's gap direction that can explain the obtained experimental results. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Electrophoretic deposition of conjugated polymer: Deposition from dilute solution and PEDOT coating effect

It has been shown that the films of a soluble conjugated polymer poly[(9,9-dioctyl-2,7-divinylene fluorenylene)-alt-{2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene}] for electronic devices can be prepared by the electrophoretic deposition with polymer suspensions derived from dilute polymer solutions which are so dilute that the conventional spin-coating technique is not applicable. For example, a 100 nm-thick film can be prepared on an indium-tin-oxide (ITO) electrode from a suspension from solution containing 0.1 g/l of the polymer. The thickness of the polymer film deposited is found to be almost proportional to the concentration of the polymer, and the linearity down to 5.0 × 10^?3 g/l is confirmed. On the other hand, it has been found that coating the ITO electrode with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) salt results in low and nonlinear deposition rate.     

Synthesis and antiallergic activity of dimethyl-2-(phenylcarbamoyl)ethylsulfonium p-toluenesulfonate derivatives

The derivatives of dimethyl-2-(phenylcarbamoyl)ethylsulfonium p-toluenesulfonates were synthesized and evaluated for antiallergic activity. The 2,3-dihydroxyethoxy group was introduced to the phenyl ring from the standpoint of lipophilicity and electronic effects of substituent. The IgE-induced rat passive cutaneous anaphylaxis (PCA) was inhibited by oral administration of several substituted 2-[(4-propoxyphenyl)carbamoyl]ethyldimethylsulfonium p-toluenesulfonate derivatives. Among them (+/-)-2-[N-[4-(3-ethoxy-2-hydroxypropoxy)phenyl]carbamoyl]ethyldimeth ylsulfonium p-toluenesulfonate (1a, IPD-1151T) was found to possess considerable activity in the PCA test, and it was launched as Suplatast tosilate in Japan.