Conformation and local environment dependent conductance of DNA molecules.
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DNA↗
Biomedical subjects
M S Xu
Publications and source records attributed to M S Xu.
Variable-temperature scanning tunneling microscopy and scanning tunneling spectroscopy study on copper phthalocyanine ultrathin films on a Au(111) surface.
Variable-temperature high-resolution scanning tunneling microscopy (STM) images reveal that well-ordered copper phthalocyanine (CuPc) strips can be self-assembled by depositing CuPc molecules on a Au(111) surface. The self-assembled strips are supposed to result from the balance of the intermolecular interaction and the interaction between the molecules and substrate during annealing. The energy band (approximately 1.9-2.1 eV) of CuPc, measured by scanning tunneling spectroscopy (STS), is comparable to the optical band gap (approximately 1.7 eV). Spectroscopic measurements confirm that a dipole layer and/or an effect of image force exist at the CuPc/Au(111) interface.
Crystallization↗
[Induction of callus of Hypericum perforatum L. and qualitative identification of active constituents of its callus].
OBJECTIVE: To induce the callus of H. perforatum and identify hypericin and pseudohypericin of its callus. METHOD: The callus was induced in different culture conditions, and active constituents were determined by HPLC. RESULT AND CONCLUSION: The inductions of callus from different parts were discussed, the induction rate of the leaf axil being the highest. The MS basic medium with 4 micrograms.L-1 2,4-D and 0.2 microgram.L-1 6-BA was the best of all screened media. Hypericin in the callus is determined by HPLC.
Anthracenes↗
Quantitative analysis of Roussin red methyl ester in pickled vegetables.
In a study of the etiological factors in esophageal cancer, Roussin red methyl ester was isolated and identified in pickled vegetables of Linxian County, North China, where there is a high incidence of esophageal cancer. In this paper, a method is described for quantitative analysis of Roussin red methyl ester in pickled vegetables by gas chromatography-high-resolution mass spectrometry single-ion monitoring. The content of Roussin red methyl ester in pickled vegetables from Linxian has been found to be 0.1 to 4.5 mg/kg, and that from Beijing is below 0.005 mg/kg, which is the detection limit of the analytical method used. The marked difference between the contents might be one of the possible reasons for the difference in esophageal cancer incidence between the two regions.
Esophageal Neoplasms↗