A new approach to amplified telomerase detection with polyvalent oligonucleotide nanoparticle conjugates

We report a new assay for human telomerase activity that relies on polyvalent oligonucleotide nanoparticle conjugates as diagnostic probes and amplification units. Gold nanoparticles functionalized with specific oligonucleotide sequences can efficiently capture telomerase enzymes and subsequently be elongated. Both the elongated and unmodified oligonucleotide sequences are simultaneously measured. The two strands not only serve as internal positive controls for each other but also provide a way of amplifying signal. At high concentrations, both elongated and unmodified strands exhibit measurable responses. At low telomerase concentrations (e.g., from 10 HeLa cells), elongated strands cannot be detected, but the unmodified sequences, which come from the same probe particles, can be detected because their concentration is higher, providing a novel form of amplification. This new assay rivals the sensitivity of the conventional PCR-based method of telomerase detection.     

Very-low-lying electronic states result from n --> pi excitations in open-shell annulenes, annelated with alpha-dicarbonyl groups

UB3LYP/6-31G* calculations find that alpha-dicarbonyl-annelated cyclopentadienyl radical 1 has a sigma ground state, which is formed by excitation of an electron from the in-phase combination of carbonyl lone-pair orbitals into the singly occupied pi orbital. Similarly, tetrakis-annelated cyclooctatetraene 3 is calculated to have very-low-lying singlet and triplet excited states, which result from excitations of electrons from the b1g combination of lone pair orbitals into the empty pi nonbonding MO of the COT ring.     

A comparison of various methods for calculating unimolecular reaction rate constants

A test of the Kassel quantum expressions for unimolecular rate constants and densities of vibrational states is described. Rate constants are calculated for nine reactions previously used in such tests, over a wide range of temperatures and pressures. The Kassel expression using the geometric mean of the molecular vibration frequencies is generally found to give better results than that using the arithmetic mean.     

The effect of curvature on the reflection coeffiecient of layered absorbers

The backscattering solutions for a metallic cylinder and a metallic sphere coated with single and double layers of absorbing material are investigated. In each case, attention is confined to the high-frequency specular return. The formal series solution obeying exact boundary conditions is expanded asymptotically into a Luneberg-Kline series whose first term, geometric optics, would be obtained by using an impedance boundary condition. The second term may be viewed as a correction term which depends upon the coating characteristics and radii of curvature of the body; in the case of the cylinder, its form for the TE polarization component differs from that for the TM polarization component. No practical conditions can be imposed upon the absorbing layers to cause cancellation of second order terms simultaneously for both polarization components. However, it is possible to adjust the flat-plate reflection coefficient of the absorber coat to cancel second order terms for one polarization component. The reflection coefficient will then depend ,upon curvature; for example, the voltage reflection coefficient must be i/(SkQ) for polarization parallel to a cylinder with a thin magnetic absorber coat. Comparison of the sphere solution with the cylinder solution yields information concerning absorbers on a general convex body.     

Isomer Information from Ion Mobility Separation of High-Mannose Glycan Fragments

Extracted arrival time distributions of negative ion CID-derived fragments produced prior to traveling-wave ion mobility separation were evaluated for their ability to provide structural information on N-linked glycans. Fragmentation of high-mannose glycans released from several glycoproteins, including those from viral sources, provided over 50 fragments, many of which gave unique collisional cross-sections and provided additional information used to assign structural isomers. For example, cross-ring fragments arising from cleavage of the reducing terminal GlcNAc residue on Man₈GlcNAc₂ isomers have unique collision cross-sections enabling isomers to be differentiated in mixtures. Specific fragment collision cross-sections enabled identification of glycans, the antennae of which terminated in the antigenic α-galactose residue, and ions defining the composition of the 6-antenna of several of the glycans were also found to have different cross-sections from isomeric ions produced in the same spectra. Potential mechanisms for the formation of the various ions are discussed and the estimated collisional cross-sections are tabulated.

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Graphical Abstract ?

     

Studies in qualitative inorganic analysis. XIX

Summary A procedure for the separation of magnesium in the final (soluble) Group of the systematic qualitative semimicro inorganic analysis scheme is described which uses a solvent extraction technique with 8-hydroxy-quinoline in chloroform. Magnesium is detected in the ignition residue of the extract by means of the Titan yellow test. The method has several advantages over other means for the separation of magnesium in qualitative analysis.

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Zusammenfassung Ein Verfahren für die Abtrennung des Magnesiums von der letzten Gruppe des systematischen anorganischen Halbmikroanalysenganges wird beschrieben. Es beruht auf der Extraktion des Magnesiums mit chloroformischer 8-Hydroxy-chinolinlösung. Der Extraktrückstand wird verglüht und das Magnesium mit Titangelb nachgewiesen. Die Methode hat gegenüber anderen Möglichkeiten zur Abtrennung des Magnesiums in der qualitativen Analyse verschiedene Vorteile.

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Résumé On décrit un procédé de séparation du magnésium dans le groupe final (soluble) du schéma d'analyse minérale qualitative systématique à l'échelle semimicro, utilisant une technique d'extraction par solvant avec l'hydroxy-8 quinoléine dans le chloroforme. On recherche le magnésium dans le résidu de combustion de l'extrait en effectuant l'essai au jaune titane. La méthode présente plusieurs avantages sur les autres procédés de séparation du magnésium en analyse qualitative.

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Part XVIII. Mikrochim. Acta [Wien]1961, 88.

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Dedicated to Prof.A. A. Benedetti-Pichler on the occasion of his 70th birthday.     

Photon structure functions beyond the SUSY threshold

We evolve virtual photon parton densities up to the SUSY threshold and higher using coupled inhomogeneous DGLAP differential equations. Reliable input parameterizations were available from the c-quark threshold. Limited (target photon virtuality) dependence is observed. The difference to the photon structure function is shown to be significant with the introduction of SUSY dependent splitting functions. A negligible difference is observed by letting the gluino mass enter after the squark mass. An effort is made to include the squark threshold effect in such a way that both the renormalization group equations are satisfied and the perturbative calculation is reproduced. Received: 25 August 2000 / Revised version: 1 November 2000 / Published online: 21 December 2000