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31.
Thin films were deposited onto porous substrates by plasma polymerization using three kinds of organosilicic compounds, tetramethylsilane (TMS), hexamethyldisiloxane (M2), and octamethylcyclotetrasiloxane (D4). Those composite membranes showed different characteristics of gas permeability. When D4 was plasma-deposited onto a porous substrate, the composites membrane showed the highest oxygen permeability and the lowest oxygen-to-nitrogen permeability ratio. The composite membrane prepared from TMS showed the permeability characteristics opposite to the membrane obtained from D4. Infrared spectrum of the polymer from D4 resembles that of dimethylpolysiloxane. The plasma polymers from TMS and M2 showed different profiles in Si? O absorption bands in the range 1100–1000 cm-1 or in absorption bands of SiCH3 groups in the range 850–750 cm-1 from respective monomers. X-ray photoelectron spectroscopic observation indicated that all the plasma polymers contained more than two species of Si atom with different oxidation states. The greater part of Si atoms in plasma polymers took the same oxidation states in corresponding monomer. The gas permeability characteristics were closely related to the oxidation states of Si atom in the plasma polymers. 相似文献
32.
Osamu Nakagawa Haruo Shimamoto Tetsuya Ueda Kou Shimomura Tsutomu Hata Toru Tachikawa Jiro Fukushima Toshinobu Banjo Isamu Yamamoto 《Journal of Electronic Materials》1989,18(5):633-643
As electronic devices become more highly integrated, the demand for small, high pin count packages has been increasing. We
have developed two new types of IC packages in response to this demand. One is an ultra thin small outline package (TSOP)
which has been reduced in size from the standard SOP and the other, which uses Tape Automated Bonding (TAB) technology, is
a super thin, high pin count TAB in cap (T.I.C.) package. In this paper, we present these packages and their features along
with the technologies used to improve package reliability and TAB. Thin packages are vulnerable to high humidity exposure,
especially after heat shock.1 The following items were therefore investigated in order to improve humidity resistance: (1)
The molding compound thermal stress, (2) Water absorption into the molding compound and its effect on package cracking during
solder dipping, (3) Chip attach pad area and its affect on package cracking, (4) Adhesion between molding resin and chip attach
pad and its affect on humidity resistance. With the improvements made as a result of these investigations, the reliability
of the new thin packages is similar to that of the standard thicker plastic packages. 相似文献
33.
Sintered spheres(made of glass beads) were simply produced with a definite diameter, with a precision of ±0·5 mm in diameter, for a wide range of sintered angles (0-27°). The experimental values of the porosity of the sintered spheres were consistent with the calculated results for the coordination number N ≠ 8. The residual equilibrium saturation, as one of the basic physical properties of sintered glass beads was investigated experimentally and theoretically, resulting in the presence of a distribution in the angle of pendular ring. 相似文献
34.
Preirradiation grafting of α,β,β-trifluorostyrene onto poly(ethylene–tetrafluoroethylene) film was studied. The trapped radicals formed upon irradiation were able to induce graft polymerization under appropriate conditions. The influences of the grafting conditions were analyzed kinetically. The grafting rate dependency on the preirradiation dose was found to be of order 0.3, and the monomer concentrations, 1.0. The overall activation energies for this grafting were calculated to be 6.2 × 104 and 9.3 × 103 J/mol below and above 50°C. The grafting rate was found to be independent of the film thickness, which ranged from 25 to 100 μm. 相似文献
35.
Sphinganine‐Like Biogenesis of (E)‐1‐Nitropentadec‐1‐ene in Termite Soldiers of the Genus Prorhinotermes 下载免费PDF全文
Dr. Anna Jirošová Dr. Pavel Majer Andrej Jančařík Klára Dolejšová Dr. Richard Tykva Dr. Jan Šobotník Dr. Pavel Jiroš Dr. Robert Hanus 《Chembiochem : a European journal of chemical biology》2014,15(4):533-536
In 1974, (E)‐1‐nitropentadec‐1‐ene, a strong lipophilic contact poison of soldiers of the termite genus Prorhinotermes, was the first‐described insect‐produced nitro compound. However, its biosynthesis remained unknown. In the present study, we tested the hypothesis that (E)‐1‐nitropentadec‐1‐ene biosynthesis originates with condensation of amino acids with tetradecanoic acid. By using in vivo experiments with radiolabeled and deuterium‐labeled putative precursors, we show that (E)‐1‐nitropentadec‐1‐ene is synthesized by the soldiers from glycine or L ‐serine and tetradecanoic acid. We propose and discuss three possible biosynthetic pathways. 相似文献
36.
Studies of proton-conductive polymer membranes are vital for the future development of high-performance polymer electrolyte membrane fuel cells (PEM-FC). In particular, a method for inhibiting the volatility of water in the polymer matrix at high temperatures is a crucial issue, directly related to the operation of PEM-FC system. In this study, we focus on polymer composite membranes, which consist of commercial Nafion and mesoporous silica (MPSi) as novel inorganic additives, and investigate an improvement in the total proton conductivities and the good electrochemical stability at high temperatures. MPSi, which can be synthesized with pore sizes from 1 to 10 nm, has a wide range of potential applications because of its extraordinary properties, such as extremely large surface area, flawless surface condition and well-regulated porous structure. We found that the Nafion composites filled with MPSi have approximately 1.5 times higher proton conductivities (more than 0.1 S cm−1 at 80 °C and 95%RH) than pure Nafion and can display good temperature performance relative to pure Nafion and the particle SiO2 composite. Moreover, the conductivity of Nafion/sulfonated MPSi was the highest (0.094 S cm−1) at 40 °C and 95%RH. These are probably due to the large surface area of MPSi, which can increase the water adsorption in Nafion matrix. 相似文献
37.
38.
The synthesis and properties of oligodeoxynucleotides (ODNs) containing 2'- O -(trifluoromethyl)adenosine (2) are described. 2'- O -(Trifluoromethyl)adenosine (2) or N 6-(benzoyl)-2'- O -(trifluoromethyl)adenosine (6) was obtained in 22 or 32% yield by treating 2'- O -[(methylthio)thiocarbonyl]-3',5'- O -(1,1,3, 3-tetraisopropyldisiloxane-1,3-diyl)(TIPDS)adenosine (4) or N 6, N 6-(dibenzoyl)-2'- O -[(methylthio)thiocarbonyl]-3',5'- O -(TIPDS)-adenosine (5), respectively, with pyridinium poly-(hydrogen fluoride) in the presence of 1,3-dibromo-5,5-dimethylhydantoin. Nucleoside 2 was incorporated into DNA hexadecamers. ODNs that contained 2 reduced the thermal stability of duplexes with their complementary DNAs but increased the thermal stability of duplexes with their complementary RNAs. Furthermore, ODNs containing 2 were slightly more resistant to snake venom phosphodiesterase than an unmodified ODN. 相似文献
39.
The maximum liquid phase penetration and evaporation behavior was investigated by using simultaneous measurement for mie-scattered light images and shadowgraph ones. The objective of this study was to analyze effect of variant parameters and fuel properties on evaporation behavior, and to investigate liquid phase penetration for the single- and multi-component fuels. The experiments were conducted in a constant-volume vessel with optical access. Fuel was injected into the vessel with electronically controlled common rail injector. It was observed that: liquid phase length is influenced by fuel properties. High-boiling point fuel within the multi-component fuel controls liquid phase length. 相似文献
40.
This paper considers a standby-redundant system consisting of 2 systems, in which one is main and the other is its standby-redundant system. These systems also consist of 2 subsystems connected in series.A feature of this system is that the system has 2 switching devices connecting subsystems, in addition to one connecting main and standby systems, in order to utilize surviving subsystem. In this consideration it is assumed that all the units are repairable.We shall obtain the system reliability, the mean time to system failure, the steady state availability, and examine numerically the effects of this model to the usual one without particular switching devices. 相似文献