Numerical prediction of fraction of eutectic phase in Sn−Ag−Cu soldring using the phase-field method

A combination of macroscale solidification simulation and phase-field calculation is employed to predict the volume fraction of the eutectic phase in Sn-4.0 mass% Ag-XCu solder alloys (X=0.5–1.1 mass%). The solidification simulation incorporates the cooling rate in the phase-field simulation. We assume the residual liquid solidifies as eutectic phase when the driving force for the nucleation of Cu₆Sn₅ amounts to a critical value, which is determined based on the experimental data. Though the calculation results depend on the experimental data, the obtained fractions are about 40% for 0.5 mass% Cu and more than 90% for 1.1 mass% Cu alloy, which shows good agreement with the experimental data.     

Preparation of Lanthanum Nickel Oxide-Coated Ni Sheet Anodes and Their Application to Electrolytic Production of (CF3)3N in (CH3)4NF·4.0HF Melt

A new process for electrolytic production of a perfluorinated compound, (CF₃)₃N, using lanthanum nickel oxide-coated Ni sheet anode in the (CH₃)₄NF·4.0HF melt at room temperature, was developed. Thin films of the lanthanum nickel oxides were prepared on Ni sheets by sol-gel coating method using polyvinlylpyrrolidone(PVP). The main components of the thin films were La₂O₃, LaNiO₃, and La₂NiO₄ at 500, 750 and 1000 °C, respectively. The anode performance in the (CH₃)₄NF·4.0HF melt depends greatly on the main component of the thin film, and the LaNiO₃-coated Ni sheet anode gives the best anode performance. The potential of LaNiO₃-coated Ni sheet anode remains constant at 5.9 V during electrolysis at 20 mA·cm⁻² in the (CH₃)4NF·4.0HF melt for 100 h. This is because LaNiO₃ and NiF₃, and/or Ni₂F₅, the latter of which was formed during electrolysis, in the film give a high electronic conductivity to the surface film during electrolysis. The maximum mole fraction of (CF₃)₃N (21.4%) was obtained at 20 mA·cm⁻² in (CH₃)₄NF·4.0HF melt using the LaNiO₃-coated Ni sheet.     

Fabrication of multilevel phase computer-generated hologram elements based on effective medium theory

A conventional method to synthesize diffractive optical elements and computer-generated holograms (CGH's) with high diffraction efficiency relies on an increase of phase levels. To fabricate such a device, one should perform electron-beam (e-beam) lithography with multiple-dose exposures or multiple-step photolithography. Here we describe a one-step method, which is based on the effective medium theory, for the fabrication of a multilevel phase CGH. The phase modulations required in cells of a CGH are constructed by means of dividing these cells into fine (subwavelength) structures. The surface features of these fine structures control their corresponding indices, and their values can be calculated according to the effective medium theory. By proper selection of the fine structures, based on the requirements of the phase modulation of the cells, a CGH with multilevel phases is synthesized when a binary structure is relieved on the dielectric material. Then the CGH can be fabricated by direct e-beam lithography or one-step photolithography through an amplitude mask followed by an ion-etching treatment. The experimental results showed that the reconstructed wave field is in good agreement with that simulated by a computer, indicating the effectiveness of the proposed method.     

Rupture of the aortic arch due to bacterial aortitis--a case report of a patient undergoing successful surgical therapy

A 59-year-old man came to our hospital because of hoarseness and chest pain. On initial examination, a chest roentgenogram showed no abnormality. Three weeks later, while the patient was waiting to undergo a computed tomographic (CT) scan, shock suddenly developed. A chest roentgenogram revealed an extremely wide mediastinal shadow. A CT scan revealed rupture of the aortic arch near the base of the left subclavian artery, although there was no aneurysm. An emergency operation was performed. The ruptured aortic arch was replaced with an artificial graft during cardiopulmonary bypass with selective cerebral perfusion. A diagnosis of infectious aortitis was not made until a pathologist discovered colonies of gram-positive cocci in the resected specimen of the aortic arch. Postoperatively, antibiotics were administered for only four days. The patient is well about two years after the operation. Infectious aortitis had a very low prevalence and rarely involves the thoracic aorta. However, we should be aware of that it may cause aortic rupture even in the absence of aneurysmal dilatation.     

Debugging methods in recursive structured FORTRAN

A version of structured FORTRAN named STAR is introduced. STAR allows recursive subroutines. Implementation problems such as parameter passing by value and local variable stacking are discussed. The major difficulty in the preprocessor approach is debugging. We claim that execution profiles are strong debugging aids, and demonstrate how to debug a STAR program at source language level with the clue in the profiles plus assertion statements. We make use of a quicksort program as an example.     

Surface structures of synthetic diamonds

Diamond crystals of about 2 mm in size were grown by the temperature gradient method using Ni, Ni-Fe alloy and Fe as solvent metals. Several characteristic patterns were seen on the surfaces of the grown diamonds and were found to correspond to the texture of the quenched solvent metals. A vague vein-like pattern appeared when Ni was used. The surface patterns became finer with the increase of the content of Fe in Ni-Fe alloy, and when 70 wt% Fe-30 wt% Ni alloy was used, very fine dendritic patterns were seen on all of the faces of diamond in accordance with the symmetries of the lattice. The patterns are formed by the precipitation of carbon atoms in the space of the dendrites of the solvent metals during the quenching process. Lamellar patterns and etch pits were seen when Fe was used. The patterns are formed when Fe dissolves the diamond surfaces to produce Fe₃C during the quenching process.     

Basic linear systems and their categorical realization theory

In this paper the following problem is considered: Given an unstructured dynamical input-output model, i.e., a time system. If the systems properties like causality, stationarity, linearity, and the finiteness condition are imposed on the system, what will its resulting characteristics? This problem is investigated in order to define a meaningful subclass of time systems and to check whether or not the set of systems properties available from the present systems theory is complete enough to describe systems behavior fruitfully. The class of basic linear systems is introduced as the meaningful subclass of time systems, and their properties and representation theory are discussed in terms of category theory. This research implies that affirmative answers can be obtained for the completeness question.     

Nanoliter-sized liquid dispenser array for multiple biochemical analysis in microfluidic devices

We have developed a microdispenser array made of PDMS, in which a number of nanoliter-sized droplets can be accurately dispensed and mixed with the aid of specific channels under pneumatic pressure. In this system, hydrophobic and narrow channels act as a kind of valve and help structural liquid manipulation. Also, by arranging multiple dispensers in parallel, a single injection of liquid becomes sufficient for the preparation of multiple nanoliter-sized aliquots for different reactions. We designed two kinds of microdevices for multiple liquid dispensing and mixing and evaluated their performance and reproducibility, proving them sufficient for quantitative reactions. As a practical application, biochemical analysis of glucose was performed using enzymatic reactions. This liquid dispensing technology can be widely applied in the field of microscale analysis due to its low consumption, small dead volume of reagents and samples, and ease of operation.