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81.
Yasuhiro Takahashi Isao Sumita Hiroyuki Tadokoro 《Journal of Polymer Science.Polymer Physics》1973,11(11):2113-2122
A new crystal modification was found in poly(ethylene oxide) stretched about two-fold after necking at room temperature. An x-ray diffraction analysis indicated that the planar zigzag molecule passes through a triclinic unit cell with parameters α = 4.71 Å, b = 4.44 Å, c (fiber axis) = 7.12 Å, α = 62.8°, β = 93.2°, and γ = 111.4°. The space group is P1 ?Ci1. Packing of the molecule is very similar to that of monoclinic polyethylene. 相似文献
82.
The information processing industry has shifted from the conventional mathematical computation to information management. Interactive use of a system with large data bases is now widespread, and the data base has become one of the key factors central to an overall system design. This, in turn, has prompted the development of new peripheral devices.The paper focuses on developing and analyzing stochastic models for disk storage systems. A general model is developed to describe the sequence of operations required for accessing a record on a disk. The model is then used to analyze how technological and architectural changes affect system performance. As concrete examples, performance comparison of IBM 3330 disk system with IBM 3380 disk system will be conducted. All analytical results are validated via simulation.Supported by the National Science Foundation under Grant No. ECS-8404071. 相似文献
83.
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86.
87.
Estimation of flocculation structure in filled polymer composites by dynamic rheological measurements 总被引:10,自引:0,他引:10
G. Wu S. Asai M. Sumita T. Hattori R. Higuchi J. Washiyama 《Colloid and polymer science》2000,278(3):220-228
The frequency and concentration dependences of the storage modulus (G
′) for carbon black and short-carbon-fiber-filled polymer composites were investigated by means of dynamic rheological measurements.
It was found that G
′ at low frequencies and amplitudes could be used as a sensitive experimental parameter for detecting the flocculation structure
of the ultra-fine-particle-filled polymer composites. Correlation of electrical resistivity of the composites to the relative
storage modulus, G
′
r(=G
′
c/ G
′
p), revealed that the three-dimensional interparticle networks start to construct through the matrix when G
′
r increases to 7 regardless of the composite systems. Quantitative calculations in order to determine the flocculation structure
were carried out by means of the modified Kerner equation. A plot of the calculated value, defined as the floc index A, dependence of electrical resistivity for various systems was found to be a universal curve. Accordingly, we suggest that
A might universally correspond to the flocculation structure of the filler, which is independent of the nature of the filler,
the molecular weight, the chemical composition of the polymer and the temperature at which the measurement is made. This method
is particularly effective for estimating the flocculation structure of ultra-fine-particle-filled polymer composites no matter
whether the filler is conductive or not.
Received: 26 May 1999/Accepted in revised form: 28 September 1999 相似文献
88.
89.
Subhendu Naskar Sumita Naskar Hake M. Figgie William S. Sheldrick Shyamal Kumar Chattopadhyay 《Polyhedron》2010
Two mononuclear zinc(II) complexes, [ZnL1H2Cl]Cl·2H2O (1·Cl·2H2O) and [ZnL2HCl]·H2O (2·H2O) (L1H2 and L2H2 are N,N′-bis(pyridoxylidene)ethylenediamine and N,N′-bis(pyridoxylidene)1,3-propanediamine, respectively) have been synthesized and characterized by elemental analysis, FT-IR, fluorescence spectroscopy, TG–DTA and single crystal X-ray diffraction studies. The Zn(II) ion in complex 1 have a square pyramidal geometry with appreciable distortion towards trigonal bipyramid, whereas in 2 it has a geometry which is near the midpoint of square pyramid and trigonal bipyramid. The zinc atom is coordinated by two imine nitrogens, two phenolic oxygens and one chloride ion. The Zn(II) complexes show emission at 462 nm when excited at their lowest energy absorption at 372 nm. 相似文献
90.
Satish Kumar Shally Chadha Sumita Dham Tanya Hundal Kamal K. Kapoor 《Tetrahedron letters》2012,53(15):1905-1907
A reaction of 2,3-dihydroxynaphthalene with ethyl-2,3-dibromo-3-phenyl-propionate or 1,3-diaryl-2,3-dibromo ketone under basic conditions led to the formation of novel 2,2-disubstituted naphthodioxoles. 相似文献