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991.
A regular Ising model with nearest-neighbor interactions ofJ and–J(J>0) on a Cayley tree of coordination number 3 is investigated for the behavior of effective fields in a uniform external field. The effective fields show periodic and also aperiodic structures in the temperature-field plane. At absolute zero temperature, the equations determining effective fields are reduced to a nonlinear, one-dimensional, iterative equation. Arithmetic furcations of period and a screening of the furcations are observed. 相似文献
992.
X-ray mapping using energy dispersive spectroscopy or wavelength dispersive spectroscopy is a very popular characterisation
tool for determining the elemental distribution in materials. Furthermore, quantitative X-ray mapping has become a very powerful
technique enabling reliable quantitative results that can be an order of magnitude better than traditional analysis. Quantitative
X-ray mapping is also far superior to regions of interest X-ray maps where low levels of an element or elemental overlaps
are present.
The one major drawback with X-ray mapping is the time required to obtain a high resolution X-ray map with good statistics
at low levels of concentration. The use of multi-detectors, and just developed dual turret detectors for X-ray mapping, allows
improvement in performance at low levels without compromising quantification quality and precision of traces, even in the
presence of overlaps. However, for quantitative X-ray mapping to work properly, the characteristics of each detector must
be accurately determined so that the final quantification of the individual detectors can be summed. To accomplish this effectively,
the full spectrum at each pixel for each energy dispersive detector should be saved. As a final check for consistency between
detectors, a technique was developed that involves assigning a different red-green-blue colour for each detector for the same
element. By doing this, when we combine the three maps of the same element, we should obtain a grey scale map that indicates
total correlation between the three detectors at the most critical final stage of quantification. To reduce contrast noise
and further improve the quality of quantitative X-ray mapping images, a filter referred to as a “speckle filter” has been
developed that allows the eye to see a more correct elemental concentration relationship. 相似文献
993.
Summary In recent biochemical studies it was demonstrated that residue Asp113 of the-adrenoceptor (-AR) is an indispensable amino acid for the binding of-AR antagonists. Earlier fluorescence studies showed that a tryptophan-rich region of the-AR is involved in the binding of propranolol, the prototype-AR antagonist. Bearing these two biochemical findings in mind, we explored the-AR part containing Asp113, for an energetically favorable antagonist binding site. This was done by performing molecular docking studies with the antagonist propranolol and a specific-AR peptide which included, besides Asp113, two possibly relevant tryptophan residues. In the docking calculations, the propranolol molecule was allowed to vary all its internal torsional angles. The receptor peptide was kept in an-helix conformation, while side chains relevant to ligand binding were flexible to enable optimal adaptations to the ligand's binding conformation. By means of force-field calculations the total energy was minimized, consisting of the intramolecular energies of both ligand and receptor peptide, and the intermolecular energy. We found an antagonist binding site, consisting of amino acids Asp113 and Trp109, which enabled energetically favorable interactions with the receptor-binding groups of propranolol. According to these results, binding involves three main interaction points: (i) a reinforced ionic bond; (ii) a hydrogen bond; and (iii) a hydrophobic/charge transfer interaction. The deduced binding site shows a difference in affinity between the levo- and dextrorotatory isomers of propranolol caused by a difference in ability to form a hydrogen bond, which is in conformity with the experimentally observed stereoselectivity. Moreover, it also provides an explanation for the
1-selectivity ofp-phenyl substituted phenoxypropanolamines like betaxolol. Thep-phenyl substituent of betaxolol was shown to be sterically hindered upon binding to the
2-AR peptide, whereas this hindrance is very likely to be much less with the
1-AR peptide. Finally, the proposed antagonist binding site is discussed in the light of some recent biochemical findings and theories.Abbreviations
-AR
-adrenergic receptor
- cDNA
complementary DNA
- H-bond
hydrogen bond
- VdW
van der Waals
- QSAR
quantitative structure-activity relationship
-
125I-pBABC
p-(bromoacetamido)benzyl-1-[125I]iodocarazol 相似文献
994.
Yutaka Ishigami Fumiyoshi Ishii Young Kook Choi Toshio Kajiuchi 《Colloids and surfaces. B, Biointerfaces》1996,7(5-6):215-220
Fluorescent probes are useful to monitor the polarity and fluidity of microenvironments. Therefore, a new amphiphilic fluorescent probe, the pyrenacylester of Rhamnolipid B, was prepared from biosurfactant (Rhamnolipid B) and pyrene. As a result of its surface activity, this probe was expected to be able to penetrate into various kinds of microdomains such as the environments of organic solvents, emulsions, dispersions, surfaces of biomembranes and polymers. 相似文献
995.
H. Nakayama K. Uchida F. Shinkai T. Shinoda T. Okuyama K. Seta T. Isobe 《Journal of chromatography. A》1996,730(1-2):279-287
A method is presented for the structural characterization of proteins separated by two-dimensional poly-acrylamide gel electrophoresis (2D-PAGE). The method includes separation of a protein mixture by 2D-PAGE, recovery of proteins from the gel spots revealed by copper staining and analysis of the proteins by triple-stage quadrupole mass spectrometry using an electrospray ionization interface (ESI-TSQMS). Prior to the mass spectrometric analysis, the extracted proteins were passed through a small reversed-phase column (10 × 4.0 mm I.D.) to remove salts and gel-derived contaminants and then introduced into the mass spectrometer through a reversed-phase capillary column with 0.25 mm I.D. Application of the method to the analysis of rat cerebellar proteins suggests that the molecular mass could be accurately determined with sub-picomole amounts of protein samples derived from one or two 2D gels. The method was also useful for peptide mapping and determination of amino acid sequences of proteins micro-prepared from the 2D gel. Because 2D-PAGE has an excellent resolving power in protein separation and because capillary LC-ESI-TSQMS provides structural information with very small amounts of samples, the combined system of 2D-PAGE and capillary LC-ESI-TSQMS described here should allow wide applications to molecular studies of genes and proteins, such as identifications of protein spots on 2D gels, confirmation of gene/protein sequences and analysis of post-translational modification of proteins present naturally in tissue/cell extracts or expressed by recombinant DNA techniques. 相似文献
996.
本文研究了一类抽象形式的广义拟变分不等式,并由此推出了关于广义拟变分不等式的某些结果。这些结果是文[1]之定理3,文[2,3]的定理11及文[5]的定理1的改进和推广。 相似文献
997.
随机广义集值隐拟补问题 总被引:1,自引:0,他引:1
引入和研究一类随机广义集值隐拟补问题,构造了一个逼近问题解的随机迭代算法.在一定条件下,我们证明了这类问题解的存在性以及由随机算法所产生的序列的收敛性. 相似文献
998.
In this paper, a general idea of Presic type $L$-fuzzy fixed point results using some weakly contractive conditions in the setting of metric space is initiated. Stability of $L$-fuzzy mappings and associated new concepts are proposed herein to complement their corresponding notions related to crisp multi-valued and single-valued mappings. Illustrative nontrivial examples are provided to support the assertions of our main results. 相似文献
999.
SOME FURTHER GENERALIZATIONS OF KY FAN’S MINIMAX INEQUALITY AND ITS APPLICATIONS TO VARIATIONAL INEQUALITIES 总被引:1,自引:0,他引:1
The purpose of this paper is to introduce the concept of generalized KKM mapping andto obtain some general version of the famous KKM theorem and Ky Fan’s minimaxinequality.As applications,we utilize the results presented in this paper to study the saddlepoint problem and the existence problem of solutions for a class of quasi-variationalinequalities.The results obtained in this paper extend and improve some recent results of[1-6]. 相似文献
1000.
TRANSFEROPENORCLOSEDSETVALUEDMAPPINGANDGENERALIZ-ATIONOFH-KKMTHEOREMWITHAPPLICATIONSLiBing-you(李秉友);SuJia-bao(苏家宝)(Department... 相似文献