Large scale purification of synthesized oligodeoxyribonucleotides by reversed-phase chromatography

Summary A reversed-phase chromatographic column suitable for the purification of chemically synthesized large oligodeoxyribonucleotides (oligo-DNA) was prepared. The specifications of this column are; the selected silica (Toyo Soda silica) with large pore size (at least 150 ) and small particle diameter (5 m desired) should be grafted only with monochloro alkylating reagent of long alkyl chain (sufficiently C₁₈) so that the carbon content of the resultant packing material is 15–16%. Using this column, we could isolate the targeted large oligo-DNA (up to 50mer) in a large scale (75 g per one cycle) from the impurities in the reaction mixture formed during the automated synthesis by the phosphite method.     

Near-field optical imaging of plasmon modes in gold nanorods

We have investigated optical properties of single gold nanorods by using an apertured-type scanning near-field optical microscope. Near-field transmission spectrum of single gold nanorod shows several longitudinal surface plasmon resonances. Transmission images observed at these resonance wavelengths show oscillating pattern along the long axis of the nanorod. The number of oscillation increases with decrement of observing wavelength. These spatial characteristics were well reproduced by calculated local density-of-states maps and were attributed to spatial characteristics of plasmon modes inside the nanorods. Dispersion relation for plasmons in gold nanorods was obtained by plotting the resonance frequencies of the plasmon modes versus the wave vectors obtained from the transmission images.     

Molecular recognition of alpha,beta-unsaturated carbonyl compounds using aluminum tris(2,6-diphenylphenoxide) (ATPH): structural and conformational analysis of ATPH complexes and application to the selective vinylogous aldol reaction

Various alpha,beta-unsaturated carbonyl compounds were coordinated with aluminum tris(2,6-diphenylphenoxide) (ATPH) to give the corresponding Lewis acid-base complexes in a distinctive coordination fashion (selective coordination). ATPH recognizes carbonyl substrates and subsequently orients itself as it forms a stable complex through selective coordination with the carbonyl oxygen. Selective coordination also confers a conformational preference to each carbonyl compound under the steric and electronic influence of ATPH, which enables the vinylogous aldol reaction of alpha,beta-unsaturated carbonyl compounds to give the corresponding gamma-aldol products with different regio- and stereoselectivities.     

Morphological and spectroscopic properties of thin films of self-assembling amphiphilic porphyrins on a hydrophilic surface as revealed by scanning near-field optical microscopy

We fabricated porphyrin thin films on mica surfaces from acidic aqueous solutions of the preorganized H-aggregates of amphiphilic porphyrins by the simple spin-coating method. The morphological and spectroscopic properties of the film were investigated by scanning near-field optical microscopy. The results obtained in this study demonstrate that the preorganized structure in solution can be transferred as a thin film with a thickness of the monolayer level without losing their substantial structure and photophysical properties.     

Cleavage of hydrazine N-N bonds by RuMo3S4 cubane-type clusters

The mixed-metal cubane-type clusters [(Cp*Mo)3(mu3-S)4RuH2(PR3)][PF(6)] [Cp* = eta5-C5Me5; R = Ph (2), Cy (5)] were effective for the N-N bond cleavage of hydrazine and phenylhydrazine via a disproportionation reaction. The ammonia cluster [(C*Mo)3(mu3-S)4Ru(NH3)(PPh3)][PF6] (3) and/or the unprecedented double-cubane-type cluster with bridging nitrogenous ligands [{(Cp*Mo)3(mu3-S)4Ru}2(mu2-NH2)(mu2-NHNH2)][PF6]2 (4) were isolated from the reaction mixtures, and their structures were determined by X-ray diffraction studies.     

Chemical and enzymatic synthesis of neoglycolipids in the presence of cyclodextrins

The efficiency of cyclodextrins (CDs), α-CD, β-CD and γ-CD, for the blotting of hydrophobic substrates to water-soluble polymers and for the synthesis of neoglycolipids using glycosyltransferase is described. CDs did not disturb HPLC purification and did not bring lather. These merits are superior to surfactants commonly used in such a case. The utility of CDs as a novel and efficient supporting material for enzymatic glycosylation is also discussed.     

Molecular adsorption onto metallic quantum wires.

We have studied the adsorption of mercaptopropionic acid, 2,2'-bipyridine, and dopamine onto electrochemically fabricated Cu nanowires. The nanowires are atomically thin with conductance quantized near integer multiples of 2e(2)/h. Upon molecular adsorption, the quantized conductance decreases to a fractional value, due to the scattering of the conduction electrons by the adsorbates. The decrease is as high as 50% for the thinnest nanowires whose conductance is at the lowest quantum step, and smaller for thicker nanowires with conductance at higher quantum steps. The adsorbate-induced conductance changes depend on the binding strengths of the molecules to the nanowires, which are in the order of mercaptopropionic acid, 2,2'-bipyridine, and dopamine, from strongest to weakest. The sensitive dependence of the quantized conductance on molecular adsorption may be used for molecular detection.     

Info-gap robust design with load and model uncertainties

This paper develops a new structural design concept which incorporates uncertainties in both the load and the structural model parameters. Info-gap models of uncertainty are used to represent uncertainty in the power spectral density of the load and in parameters of the vibration model of the structure. It is demonstrated that any design which optimizes functional performance will also minimize the robustness to uncertainty. Since uncertainties are prevalent in many applications, this paper argues that it is necessary to satisfy critical performance requirements (rather than to optimize performance), and to maximize the robustness to uncertainty. The design implications of this robust-satisficing approach are demonstrated with several heuristic structural design examples. It is shown that design preferences depend upon performance requirements: preferences between designs can be reversed when performance requirements change. Also, we show that the info-gap robustness function provides an attractive tool for adjudicating between conflicting objectives in multi-criteria design.     

The Grothendieck group of a quantum projective space bundle

We compute the Grothendieck group of non-commutative analogues of projective space bundles. Our results specialize to give the Grothendieck groups of non-commutative analogues of projective spaces, and specialize to recover the Grothendieck group of a usual projective space bundle over a regular noetherian separated scheme. As an application, we develop an intersection theory for quantum ruled surfaces. S. P. Smith was supported by NSF grants DMS 9701578 and 0070560 Received: March 2006