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71.
The substrate is shown to induce substantial ordering in diblock copolymer thin films above the bulk order-disorder transition
(ODT) where, thermodynamically, a phase mixed state is favored. Initially, uniform films reorganize to form a hierarchy of
transient surface patterns and stable film thicknesses that depend on the initial film thickness and on the substrate. Self-consistent
field calculations of the free energy of the system for different situations, depending on the relative tendency for the different
block components to be attracted to the substrate and/or free surface, provide an explanation of the formation of the stable
film thicknesses. A continuum picture proposed earlier by Brochard et al.rovides an explanation of the wetting characteristics of this system. In some cases the ordering destabilizes the film so
that dewetting occurs (wetting autophobicity), whereas in other cases the surface ordering results in a kinetic stabilization
of a film that would otherwise dewet.
Received 3 August 2001 and Received in final form 1 November 2001 相似文献
72.
Düffels A Green LG Ley SV Miller AD 《Chemistry (Weinheim an der Bergstrasse, Germany)》2000,6(8):1416-1430
The concise synthesis of five biantennary oligomannose neoglycolipids is presented. Employing a strategy based on the principles of reactivity tuning and orthogonal activation, the oligomannose moieties, isolated from the glycoprotein 63 of the parasite Leishmania mexicana amazonensis, were rapidly assembled taking advantage of common structural motifs found in these N-glycans. Deprotection of all structures was achieved in high yield by hydrogenolysis. The deprotected glycoconjugates were subsequently coupled to a cholesteroldiamine derivative using diethylsquarate as a linker. The resulting neoglycolipids will be used as additives to cationic liposome formulations in the active targeting of liposomes to macrophages. 相似文献
73.
Green MM Park JW Sato T Teramoto A Lifson S Selinger RL Selinger JV 《Angewandte Chemie (International ed. in English)》1999,38(21):3138-3154
Cooperative phenomena, described by one-dimensional statistical physical methods, are observed between the enantiomeric characteristics of monomeric materials and the polymers they produce. The effect of minute energies associated with this amplified chirality, although currently not interpretable, can be easily measured. Nonlinear relationships between enantiomeric excess or enantiomeric content and polymer properties may offer the possibility of developing chiral catalysts and chiral chromatographic materials in which the burden of large enantiomeric excess or content may be considerably alleviated. New approaches to information and sensor technology may become possible. 相似文献
74.
Mark Green M. Draganjac Yanjing Jiang A.W. Cordes 《Journal of chemical crystallography》1999,29(3):273-276
The isolation and characterization of [CpRu(9S3)](O3SCF3), where 9S3 = 1,4,7-trithiacyclononane, is reported. The title compound crystallizes in the orthorhombic space group Pbca: a = 10.2542(18), b = 14.8991(13), c = 22.4832(18) Å, and Z = 8. The Ru atom is sandwiched between the -bound cyclopentadienyl ligand and the 9S3 ligand, bonding to all three of the sulfur atoms in the 9S3. The Ru—S distances are 2.2991(10), 2.2979(11), and 2.3055(10) Å. The C—S distances range from 1.819(4) to 1.852(5) Å in the trithiacyclononane ring. 相似文献
75.
The problem of designing a secure electricity supply network at minimal cost is formulated as a mathematical program. It is also shown how computationally convenient new constraints may be derived and these are added to the original set. The problem is dualized and solved approximately. It is indicated how this approach can be built into a Branch-and-Bound scheme for solving the original design problem, and an illustrative example is given. 相似文献
76.
Sensitive assays have been developed for adenosine 5'-triphosphate, the reduced form of nicotinamide adenine dinucleotide, cholyl glycine and alcohol, with immobilized and co-immobilized preparations of bacterial and firefly luciferase as reagents. With high-speed (ASA 20000) instant photographic film as detector, picomole amounts of the various analytes can be detected rapidly. The simplicity and convenience of the analytical combination of co-immobilized bioluminescent enzymes and photographic film for the detection of light make this an ideal technique for rapid screening tests. 相似文献
77.
78.
79.
Lateralization of filtered clicks 总被引:3,自引:0,他引:3
W A Yost F L Wightman D M Green 《The Journal of the Acoustical Society of America》1971,50(6):1526-1531
80.
Neutron activation analysis has been used to assay the trace elements Co, Fe, Sc, Rb and Zn in pollen and derived sporopollenins.
The method is capable of high precision and avoids the necessity for sample ashing and the introduction of reagent contamination.
Rubidium was completely removed during the chemical isolation of sporopollenins and the remaining elements which survived
chemical treatment were found in reduced amounts. The ratio of Sc: Fe in pollen and in several derived sporopollenins was
found to be approximately constant. Results are discussed with reference to the possibilities of anomalous chemical behaviour
of the elements resulting from irradiation. 相似文献