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51.
The effects of a proposed combustion technique, named as annular counterflow, on the enhancement of jet diffusion flame blowout limits were investigated by a series of experiments conducted for the present study. Annular counterflow was formed in a concentric annulus, in which fuel jet was ejected from a nozzle and air was sucked into an outer cylinder encompassing the nozzle. Three fuel nozzles and outer cylinders of different sizes were utilized to perform the experiments. Schlieren technique and normal video filming were employed for the visualization of diverse flame morphologies triggered by the said flow. Gas samplings were taken and scrutinized by the use of a gas chromatograph. Results showed that the blowout limits can be enhanced dramatically by an increase in volume flow rates of air‐suction. Mixing enhancement is achieved with frequent and strong outward ejection of fluids from the cold jet when this technique is applied. The blowout limits are further extended when the diameter of outer cylinders becomes smaller and/or that of the fuel nozzle becomes larger. The base widths of lifted flames were found to be narrower in the interim of annular counterflow application. The rates of increase in flame lift‐off heights and base widths along with an increase in fuel flow velocities become sluggish when the volume flow rates of air are increased. The amount of fuel that was sucked into the outer cylinder was found to be negligible and trivial. A model based on annular and coaxial jet was developed to predict the lifted flame base width and blowout limits. The coincidence between the prediction and experimental results unambiguously validates that the momentum of air‐suction dominates the beneficial effect. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
52.
Masao Sugawara Masamitsu Kataoka Kazunori Odashima Yoshio Umezawa 《Thin solid films》1989,180(1-2):129-133
Biomimetic “ion-channel sensors” based on host-guest molecular recognition were constructed by incorporating several kinds of receptor molecules in Langmuir-Blodgett (LB) molecular assemblies deposited directly on glassy carbon electrodes. The receptors used were valinomycin, bis(crown ether)s, macrocyclic polyamine and cyclodextrin polyamine. The binding of charged stimulants (metal ions, inorganic and organic anions) to these receptors induced a marked increase (or decrease) in the ion permeability of the membranes, as detected by cyclic voltammetry using [Fe(CN)6]4- or [Ru(bpy)3]2+ as marker ion. Such a mode of response, corresponding to model “channel opening (or closing)”, can be explained on the basis of the charge-charge interaction involving the stimulant, marker ion and lipid. 相似文献
53.
Minoru Kumakura Isao Kaetsu Kazuhiro Asami Shuichi Suzuki 《Journal of Materials Science》1989,24(5):1809-1813
Porous polymer composite columns having porous structure were prepared by radiation cast-polymerization of hydrophilic monomers at low temperature and their characteristics were studied. The porosity of the polymer increased with decreasing monomer concentration. The elution time of water in the polymer column increased with increasing monomer concentration and with decreasing irradiation temperature. The elution time was dependent on the degree of hydration of the polymer. The polymer with a degree of hydration of 0.2 to 0.4 gave the minimum elution time. The elution time decreased with the addition of porous inorganic substances. 相似文献
54.
Kouichi Asakura Ayuko Iida Ryoichi Kitagata Atsushi Yoshida Shuichi Osanai Akihiro Kuroda 《Journal of surfactants and detergents》2001,4(4):375-378
Adsorption properties of two types of dimethylpolysiloxane backbone derivatives, perfluoroalkyl polyoxyethylenated dimethylpolysiloxane
(FPD) and polyoxyethylenated dimethylpolysiloxane (PD), onto keratin surfaces were investigated. Both polymers are amphiphilic,
since they possess hydrophilic polyoxyethylene groups. FPD contains a perfluoroalkyl group that provides both water-and oil-repellent
properties, whereas PD lacks these groups. Adsorption properties of these polymers onto keratin surfaces are considered a
good index to evaluate these compounds as nonionics used in hair-coating agents, since keratin is a major component of hair.
FPD was more likely to be adsorbed and less likely to be eliminated from the keratin surface than PD. Once FPD had been adsorbed
onto the keratin surface, it was very slowly washed from the surface when it was immersed in stationary water, whereas PD
polymers were quickly washed from the keratin surface. Even in running water, rapid elimination of FPD was not observed. The
strong resistance to loss of FPD after washing with a large quantity of water may be due to the water-repellent nature of
the perfluoroalkyl groups. As a comparison, FPD adsorption onto a glass surface was also investigated. The affinity to the
glass surface was found to be less than to the keratin surface. 相似文献
55.
The elements added diamond-like carbon films (hydrogen, fluorine, and sulfur) fabricated from C2H2:H2, C2H2:CF4 and C2H2:SF6 mixtures were used to compare and study the effects of element contents on the deposition and tribological properties of films prepared by plasma-based ion implantation (PBII). The structure of the films was analyzed by Raman spectroscopy. Hardness and elastic modulus of films were measured by nano-indentation hardness testing. Contact angle and surface energy of films were measured by contact angle measurement. Tribological characteristics of films were performed using a ball-on-disk friction tester. The results indicate that with the increasing element contents, the hardness and elastic modulus, and surface energy of all films decreases, while the surface angle tends to increase. Additionally, H-DLC films at C:H flow rate ratio of 1:4 shows a friction coefficient of 0.08 under ambient air, which are considerable improvement in the tribological properties. This is due to the formation of a transfer films on the interface and high hydrogen contents. For F-DLC films and S-DLC films, does not show a significant decrease in the friction coefficient with the fluorine and sulfur contents under ambient air. The decrease in the friction coefficient is greater under high vacuum than under ambient air. 相似文献
56.
Tanzawa T. Umezawa A. Kuriyama M. Taura T. Banba H. Miyaba T. Shiga H. Takano Y. Atsumi S. 《Solid-State Circuits, IEEE Journal of》2001,36(1):55-63
A low-power wordline voltage generating system is developed for low-voltage flash memories. The limit for the stand-by current including the operation current for the band-gap reference and the stand-by wordline voltage generator is discussed. The system was implemented on a 1.8-V 32-Mb flash memory fabricated with a 0.25-μm flash memory process and achieved with very low stand-by current of 2 μA typically, and high operating frequency of 25 MHz in read operation at 1.8 V. A low-voltage level shifter with high-speed switching is also proposed 相似文献
57.
58.
59.
Water vapor solubility of poly(lactic acid) films modified the surface by vacuum ultraviolet irradiation
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Surface modification of poly(lactic acid) (PLA) film is performed via 172 nm excimer lamp irradiation. Effects on water vapor solubility and physical properties via vacuum ultraviolet (VUV) irradiation are studied systematically. After VUV irradiation, water vapor solubility increases approximately 11–43% in the low‐pressure region and approximately 20–38% in the high‐pressure region as surface hydrophilicity increased. The increase is attributed to hydrogen bonding with the carboxyl groups because of VUV radiation. The modified layer is significantly swelling after water vapor sorption. The hydrophilic layer forms a thickness of 2–3 μm from the irradiated surface via VUV radiation, but no changes are observed inside the irradiated film. Therefore, PLA film solubility after irradiation is enhanced by hydrophilicity and the swelling effect of the surface. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42200. 相似文献
60.
Dr. Naoki Umezawa Yuhei Horai Dr. Yuki Imamura Makoto Kawakubo Mariko Nakahira Dr. Nobuki Kato Akira Muramatsu Prof. Dr. Yuko Yoshikawa Prof. Dr. Kenichi Yoshikawa Prof. Dr. Tsunehiko Higuchi 《Chembiochem : a European journal of chemical biology》2015,16(12):1811-1819
A versatile solid‐phase approach based on peptide chemistry was used to construct four classes of structurally diverse polyamines with modified backbones: linear, partially constrained, branched, and cyclic. Their effects on DNA duplex stability and structure were examined. The polyamines showed distinct activities, thus highlighting the importance of polyamine backbone structure. Interestingly, the rank order of polyamine ability for DNA compaction was different to that for their effects on circular dichroism and melting temperature, thus indicating that these polyamines have distinct effects on secondary and higher‐order structures of DNA. 相似文献