An ultrahigh vacuum scanning Kelvin probe force microscope (UHV SKPM) utilizing the gradient of electrostatic force, was developed based on an ultrahigh vacuum noncontact atomic force microscope (NC-AFM) capable of atomic level imaging, and used for simultaneous observation of contact potential difference (CPD) and NC-AFM images. CPD images of a Si(111) surface with Au deposited, clearly showed the potential difference in phases between 7×7 and 5×2 structures. When Ag was deposited as a submonolayer on the Si(111) 7×7 reconstructed surface, the atomic level lateral resolution was observed in CPD images as well as in NC-AFM topographic images.

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Unlike ultrahigh vacuum (UHV) scanning tunneling microscopy (STM), the effectiveness of UHV in UHV atomic force microscopy (AFM) has not been verified. Intensive interaction between tip and sample in UHV often damages the sample surface in the contact mode. Although noncontact (NC) AFM is effective in protecting the sample surface, it has failed to provide atomic-level resolution. We used a stiff silicon cantilever ( ∼40 N/m) capable of STM imaging, and succeeded in obtaining the first atomic-resolution images of Si(111)7×7 reconstruction in NC AFM at a tip-sample distance almost equal to that for STM imaging.

To our knowledge the present paper shows for the first time the kinetic parameters of all the three starch branching enzyme (BE) isozymes, BEI, BEIIa and BEIIb, from rice with both amylopectin and synthetic amylose as glucan substrate. The activities of these BE isozymes with a linear glucan amylose decreased with a decrease in the molar size of amylose, and no activities of BEIIa and BEIIb were found when the degree of polymerization (DP) of amylose was lower than at least 80, whereas BEI had an activity with amylose of a DP higher than approximately 50. Detailed analyses of debranched products from BE reactions revealed the distinct chain length preferences of the individual BE isozymes. BEIIb almost exclusively transferred chains of DP7 and DP6 while BEIIa formed a wide range of short chains of DP6 to around DP15 from outer chains of amylopectin and amylose. On the other hand, BEI formed a variety of short chains and intermediate chains of a DP

Light and small-angle X-ray scattering, sedimentation equilibrium, viscosity, circular dichroism, and infrared absorption measurements have been made on 1,4-dioxane (DIOX) and 2-ethoxyethanol (2EE) solutions of seven amylose tris(phenylcarbamate) samples ranging in molecular weight from 2 Â 10 4 to 3 Â 10 6 . Analyses of gyration radius, scattering function, and intrinsic viscosity data in terms of the wormlike chain model yield Kuhn segment lengths of 22 AE 2 nm and 16 AE 2 nm in DIOX and 2EE, respectively, and a contour length per residue of 0:33 AE 0:02 nm in both, showing that the amylose derivative chain has high stiffness and a contour length slightly shorter than the known value 0.37-0.40 nm for amylosetriesters in the crystalline state. These results are consistent with the intramolecular hydrogen bonding between the C=O and NH groups of the neighbor repeating units detected by infrared absorption and also with the locally regular (or helical) conformation indicated by circular dichroism.