Research on corrugated multi‐louvered fins under dehumidification

To enhance automotive evaporator wet‐fin performances, the main task is to promote the draining of condensed water. An accurate and convenient apparatus estimating the fin performances has been developed. Through the measurement of corrugated multi‐louvered fin performances and the visualization of condensed water draining by this apparatus, it was clarified that fin geometries, surface coating, and evaporator installation strongly contributed to the efficiency of draining and fin performances. © 2001 Scripta Technica, Heat Trans Asian Res, 30(5): 383–393, 2001     

Mixed powder coating film using thermoplastic polyester and its alkaline resistance

To improve alkaline resistance, a newly mixed powder coating film using thermoplastic polyethylene terephthalate (PET) was investigated. Two kinds of polyvinyl butyral (PVB) and two kinds of polyamide (PA) were chosen as the secondary polymer. The melting temperatures (T _ms) of these materials were lower than that of primary PET polymer so the mixed powder coating was able to form a dual phase film through a fluidized bed coating process. Microscope and Fourier transform infrared spectroscopy (FTIR) observations revealed that the dual phase structure was indeed successfully formed and there was a secondary layer over the entire surface area of the film. This mixed powder coating film significantly enhanced the alkaline resistance to an environment filled with NaOH solution at 40°C in which a secondary material would be effective in protecting the film. With regard to both alkaline resistance and film formability, PET/PVB was superior to the PET/PA mixture.     

Annealing effect on temperature coefficient of resistivity in La1−xSrxMnO3 ceramics

We investigated annealing effects of La_1?xSr_xMnO₃ (x = 0–0.6) on electrical resistivity and the temperature coefficient of resistivity (TCR). The annealed samples’ resistivity was lower than those of non-annealed samples. For example, annealing changed the resistivity of x = 0.3 at 25 °C from 4.50 × 10^?5 to 3.71 × 10^?5 Ω m. Remarkable difference in TCR was observed after annealing, for x = 0.3, 0.45, and 0.5. For x = 0.3, the TCR after annealing was 4000 ppm/°C, which was 1250 ppm/°C greater than that before annealing. We investigated (1) crystal phase, (2) Mn average valence, (3) Mott insulator–metal transition temperature, and (4) microstructure. The microstructure was remarkably varied for annealed x = 0.3 and 0.5. The average grain size of the x = 0.3 increased from 1.60 up to 2.38 μm. Results show that annealing affects resistivity and TCR because of grain growth during annealing.     

Partial nickel plating using organic gel electrolyte

A partial nickel plating method was developed by using the organic gel electrolyte. The gel electrolyte was made from polyvinylchloride as a gelling agent and tetrahydrofuran as an organic solvent. The suitable conditions for nickel plating were investigated by the measurements of polarization curve and electrochemical impedance. The pattern electroplating using thin layer of gel electrolyte was carried out on the copper substrate. The substrate surface could be plated by nickel with high uniformity and sharp edge line. The present method will be widely used for the surface patterning without masking.     

A Novel Sodium Silicate Fluoride Solution and a H2 Gas Formed by a Reaction Between Si and an Aqueous Solution of NaOH and NaF

Oxidation of Si in an alkali solution has attracted much attention to produce hydrogen gas from Si wastes. It was found that hydrogen gas was generated from Si in NaOH and NaF solution with more than 10 times reaction rate than in the NaOH solution. The reaction by-product was a sodium silicate fluoride, Na _{x + z} Si _y O_{2 y + x /2}F _z solution, and it proved to transform to a glass foam by boiling. The Raman spectrum suggested that the silicon and oxygen atoms in the silicate anions were arranged in a sheet-like structure. This may affect the behavior to form the glass foam.     

A bag carrier for continuous intravenous hyperalimentation

We designed a new bag-carrier device system for continuous intravenous hyperalimentation. The patient carries it on his shoulder and can both walk up and down stairs and go out. The use of this device is simple and easy, and was found to increase the patient's opportunity to engage in physical activity.     

Oxygen Diffusion in Single- and Poly-Crystalline Zinc Oxides

¹⁸O diffusion coefficients were measured in zinc oxide ceramics using a secondary ion mass spectrometer. The results are interpreted as indicating extrinsic behavior. The values of the lattice diffusion coefficients with higher valence dopants compared with zinc ions are greater than lower valence dopant such as lithium ions. Using the data at deeper depth, the grain boundary diffusivity of oxide ions was also evaluated. Although the lattice diffusion coefficients varied by two orders of magnitude, the products of grain boundary width and grain boundary diffusion coefficient were less sensitive to the type of dopants.     

Ru(0) complex catalyzed polyaddition New synthesis of poly(alkylenebenzoxazole) and poly(alkylenebenzimidazole)

Summary The reactions of α,ω-diyne, HC≡C(CH₂)_mC≡CH (m = 6 and 8), with 3,3'-diaminobenzidine and with 3,3'-diamino-4,4'-dihydroxybiphenyl in the presence of RU₃(CO)₁₂-PPh₃ catalyst give the corresponding poly(alkylenebenzoxazole)s and poly(alkylenebenzimidazole)s, respectively. The former polymers obtained from the equimolar reaction of the monomers are partly soluble in polar organic solvents such as DMF, DMSO, and NMP, while the poly(benzimidazole)s are soluble in these solvents. GPC measurement shows the molecular weights of the polymers, M _n of 4.8−14.1×10³ and M _w of 6.4−19.7×10³. Received: 24 November 1998/Revised version: 21 December 1998/Accepted: 24 December 1998     

Carbon nanofibers with radially oriented channels

An easy templateless method to synthesize porous carbon nanofibers (CNFs) having radially-oriented mesopores is reported, using selective gasification with nano-sized catalyst particles and hydrogen as the gasification reagent. The gasification generated pores whose size corresponds to that of the catalyst particle used for the drilling. The pores were formed along the graphitic layers, reflecting the structural alignment in the CNFs. The pore size and structure can be controlled by selection of catalyst and gasification conditions.