Prediction of heat exchanger performance by the thermal network method (Improvement of an evaporator's performance and restraining air flow bypass by adjusting the refrigerant‐flow path pattern)

This paper presents the influence of latent heat load by changing the relative humidity of air flow distribution in the super‐heated gas region in an evaporator and the effect of the refrigerant flow path pattern. To estimate the influence, we applied the thermal network method that can consider refrigerant quality distribution in the heat exchanger. If the super‐heated gas region spreads to the upper wind row, humid air goes through the heat exchanger without drying, called “air flow bypass.” To suppress this phenomenon and simultaneously obtain the best performance, we chose an optimum path pattern on the basis of this method. As a result, the prediction shows that performance of the evaporator is recovered 5% for a simple 2‐row 2‐path heat exchanger when 40% of the unbalance of air flow rate occurs. © 2010 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20302     

Synthesis and Electrochemical Behavior of Regioisomeric Bismethanofullerene Derivatives

A series of regioisomeric bis-methanofullerenes (diethyl [60]fullerenobisacetate) were prepared by reaction of the sulfonium ylide with C₆₀. Seven stable resultant regioisomers were completely isolated on a preparative HPLC and identified by FT-IR, UV-vis, TOF-MS, and ¹H and ¹³C NMR measurements. The structures of these bisadducts were assigned based on 1) the relationship of the polarities of the regioisomers with the elution order from HPLC; 2) a comparison of their UV-vis spectra with those of corresponding Bingel-Hirsch bisadducts; and 3) the identification of their molecular symmetries by their ¹H and ¹³C NMR spectra. The electrochemical properties of the resultant regioisomeric bismethanofullerene, derivatives were investigated through cyclic voltammetry (CV). The bisadducts exhibited more negative reduction potential than the pristine C₆₀. Trans-2- and cis-3- bisadducts had the least negative potential E¹_1/2 of all the other bisadducts.     

Adhesion and vacuum forming properties of tin-zinc thin films deposited on polyester film substrate

Sn-Zn alloy thin films were deposited on a polyester (PET) film substrate by co-evaporation and evaluated their surface, tensile and adhesion properties with a vacuum forming test and pull test.Relationship between the surface roughness and elemental composition of these thin films was evaluated. The surface roughness decreased with increase of the Sn content.The tensile property was estimated by observations of micro-cracks of the thin films due to a vacuum forming test. Sn-Zn alloy thin film, whose elemental composition is 85:15 (wt%), had high vacuum forming durability.The adhesion strength between the Sn-Zn alloy thin films and PET substrate was measured with a pull test apparatus. The pull strength decreased with increase of the Sn content.     

Development and evaluation of a certificate validation system in mobile environments

We have developed a public key certificate validation system considering the restrictions peculiar to the mobile environment, such as processing the speed and memory capacity of a cellular‐phone terminal, and the network transmission speed. In this paper we derive a theoretical formula showing the performance of a validity check of the public key certificate of the conventional system and of the proposed system, and compare and examine a theoretical value in a mobile environment. Moreover, we evaluate the actual measurement that uses the server and cellular‐phone terminal that we developed. We show that our proposed system based on the certificate validation server (CVS) system is better than the conventional system from the viewpoint of processing speed and transmission speed. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Effects of ultrasonic irradiation on crystallization behavior of tripalmitoylglycerol and cocoa butter

Effects of application of ultrasonic power (20 kHz, 100 W) on the crystallization behavior of tripalmitoylglycerol (PPP) and cocoa butter have been examined in terms of rate of nucleation and polymorphic control. High-purity PPP (>99%) and low-purity PPP (>80%) samples were employed to mimic real fat systems, which usually have higher concentrations of minor components in addition to the main component. For both the high-purity and low-purity PPP, the application of ultrasonic power accelerated the rate of nucleation as measured by induction time for the occurrence of crystals and by the number of crystals nucleated. As for the polymorphic influences, the nucleation of both the β′ and β forms was accelerated by the ultrasound, yet the β′ form nucleation was more accelerated when the low-purity PPP samples were employed. As for cocoa butter, sonication for a short period accelerated the crystallization of Form V. The present results indicate that ultrasound irradiation is an efficient tool for controlling polymorphic crystallization of fats.     

Chemical vapor deposition of boron- and nitrogen-containing graphene thin films

Boron and nitrogen-incorporated graphene thin films were grown on polycrystalline Ni substrates by thermal chemical vapor deposition using separate boron- and nitrogen-containing feedstocks. Boron and nitrogen atoms were incorporated in the film in almost equal amounts and the total content reached ∼28%. The film predominantly consisted of separate graphene and boron nitride domains. Carrier concentration in the graphene domains was estimated to be about 1 × 10⁻³ e/atom (3.8 × 10¹² cm⁻²) from G band shift in Raman spectra.     

Molecular evidence for maternal inheritance of the chloroplast genome in tea,Camellia sinensis (L.) O. Kuntze

BACKGROUND: Tea is the most consumed beverage worldwide after water. Yet very little is known about the genetics of tea in comparison with other crop species. Here we have taken advantage of the polymorphic nature of microsatellite DNA to investigate the mode of chloroplast inheritance in tea, Camellia sinensis (L.) O. Kuntze. This is important for the correct interpretation of phylogeny and introgression data as well as assessing the suitability of chloroplast transformation as a means for transgene containment in tea. RESULTS: The study was based on six Japanese tea cultivars, namely Aj2, CK23, Hatsumomiji, Nka05, Yamanoibuki and Kanayamidori used to generate four informative families. The parental pairs in the crosses differed at a single chlroroplast locus with respect to an imperfect microsatellite repeat of 16 nucleotide bases. In agreement with earlier cytological studies, all 61 progeny displayed a cpDNA profile that was consistent with the maternal inheritance of chloroplasts in tea. CONCLUSIONS: The data generated here provide the first molecular evidence of the plastid inheritance in tea. However, we suggest that additional families and polymorphic markers be screened for increasing the confidence in the observed maternal inheritance of chloroplasts in this important crop species. Copyright © 2011 Society of Chemical Industry     

Phase equilibria in the Co-rich Co-Al-W-Ti quaternary system

We determined phase equilibria in the Co-rich Co-Al-W-Ti quaternary system at a temperature range between 900 °C and 1200 °C with a close attention to the thermodynamic stability of the γ′-Co₃(Al, W, Ti) (L1₂) phase, based on micro-structure observation and electron microprobe analysis on bulk alloy samples heat-treated for periods up to 2000 h. In the quaternary system the single phase field of γ′ extends from the Co-Ti binary edge to a composition of Co-5Al-8.5W-8Ti (in at.%) at 900 °C. At the tip of the single phase field, the γ′ phase is in equilibrium with the γ-Co (A1), Co₂AlTi (L2₁) and Co₃W (D0₁₉) phases. The constructed vertical section of phase diagram between Co-9.4Al-9.6W and Co-16.5Ti indicates that there is a narrow composition range around Co-4.5Al-5.4W-7.5Ti in which the γ single phase field exists at high temperatures above 1200 °C and two-phase of γ+γ′ is thermodynamically stable at low temperatures below 1100 °C.     

Improvement of the photostability for YVO4:Bi,Eu nanoparticles synthesized by the citrate route

YVO₄:Bi³⁺,Eu³⁺ nanophosphor synthesized by the citrate route shows the photobleaching behavior, i.e., the decrease in photoluminescence intensity under the continuous irradiation of excitation light. This photobleaching property is remarkably suppressed by the washing post-treatment combined with centrifugation and the hydrothermal post-treatment. A relation between the fraction of photobleach and the amount of citrate ions coordinating to metallic ions at the surface of nanoparticles verifies that the photobleaching behavior of YVO₄:Bi³⁺,Eu³⁺ nanophosphor originates from the redox reaction between the citrate ions and V⁵⁺ in YVO₄ host crystal. The long-term light fastness test reveals that the hydrothermally treated YVO₄:Bi³⁺,Eu³⁺ nanophosphor has sufficient photostability for practical use over 15 years outside.     

A New Method for Developing the Control Scheme of a CVVF Cycloconverter

This paper introduces a new method for developing the control scheme of phase-controlled cycloconverters. In this method, all the input cosine waves are transformed into a set of parallel lines by means of coordinate transformation. As a result, arguments on the time process of both firing delays and control flows are made much easier than by the conventional method in which all the arguments are made in the time domain. As an application, a CVVF-type noncirculating current cycloconverter is controlled using this method. The results show that the proposed method is useful in pursuing appropriate schemes for Micro-computer-based control.