Dinuclear Ruthenium(II) Complexes as Two‐Photon,Time‐Resolved Emission Microscopy Probes for Cellular DNA

The first transition‐metal complex‐based two‐photon absorbing luminescence lifetime probes for cellular DNA are presented. This allows cell imaging of DNA free from endogenous fluorophores and potentially facilitates deep tissue imaging. In this initial study, ruthenium(II) luminophores are used as phosphorescent lifetime imaging microscopy (PLIM) probes for nuclear DNA in both live and fixed cells. The DNA‐bound probes display characteristic emission lifetimes of more than 160 ns, while shorter‐lived cytoplasmic emission is also observed. These timescales are orders of magnitude longer than conventional FLIM, leading to previously unattainable levels of sensitivity, and autofluorescence‐free imaging.     

Dinuclear Ruthenium(II) Complexes as Two‐Photon,Time‐Resolved Emission Microscopy Probes for Cellular DNA

The first transition‐metal complex‐based two‐photon absorbing luminescence lifetime probes for cellular DNA are presented. This allows cell imaging of DNA free from endogenous fluorophores and potentially facilitates deep tissue imaging. In this initial study, ruthenium(II) luminophores are used as phosphorescent lifetime imaging microscopy (PLIM) probes for nuclear DNA in both live and fixed cells. The DNA‐bound probes display characteristic emission lifetimes of more than 160 ns, while shorter‐lived cytoplasmic emission is also observed. These timescales are orders of magnitude longer than conventional FLIM, leading to previously unattainable levels of sensitivity, and autofluorescence‐free imaging.     

Phospha-S-triazines. VIII. Chloro-substituted diphospha-S-triazines

1,3-Bis(phenylchlorophospha)-5-perfluoroalkyl-2,4,6- triazine and the corresponding perfluoroalkylether analogue were synthesized by interaction of equimolar amounts of the respective amidines and imido-diphenyl-diphosphinic acid pentachloride. With additional quantities of amidine, 1,3-bis(phenylperfluoro-$\text{n}$-octanoylamidinophospha)-5-perfluoro- $\text{n}$-heptyl-2,4,6-triazine was obtained. The replacement of the chloro- by azido-groups in 1,3-bis(phenylchlorophospha)-5- perfluoro-$\text{n}$-heptyl-2,4,6-triazine proceeded readily. The mass spectral breakdown patterns of the chloro- and the amidino- substituted compounds were directly comparable to those of the bis(diphenylphospha)-s-triazines.     

Asymptotic analysis of (3, 2, 1)‐shell sort

We analyze the (3, 2, 1)‐Shell Sort algorithm under the usual random permutation model. © 2002 Wiley Periodicals, Inc. Random Struct. Alg., 21: 59–75, 2002     

Grain sizes, surface areas, and porosities of vapor-deposited H2O ices used to simulate planetary icy surfaces

Mean grain sizes and specific surface areas (SSAs) of ice substrates formed by vapor deposition at low temperatures are of importance in simulating external surfaces of icy satellites in the solar system. Environmental scanning electron microscopy (ESEM) was used to obtain granule sizes and to observe the phase of ice granules prepared on borosilicate, silicon, and metallic plates. Ices prepared at a temperature lower than 140 K appear to be amorphous, and their granule sizes are typically submicrometer. At slightly warmer temperatures, near 180-200 K, ice films are composed of either hexagonal or cubic granules with sizes up to a few micrometers. When briefly annealed to even warmer temperatures, ice granule sizes approach approximately 10 microm. SSAs of ice substrates were determined from BET (Brunauer, Emmett, and Teller) analysis of gas adsorption isotherms in the temperature range from 83.5 to 261 K. SSAs decrease drastically from 102 m2/g at 83.5 K to 0.87 m2/g at 150 K and further decrease slowly to 0.22 m2/g at 261 K, suggesting that the transition from amorphous to crystalline forms occurs at approximately 150 K. The overall decrease in SSAs is primarily due to metamorphism and sintering. These results are comparable to recent field and laboratory measurements. Possible implications for theoretical models of icy satellites of outer planets using remote sensing techniques are also discussed.     

Ito versus stratonovich revisited

It is shown that a digital simulation of a noise induced phase transition using an algorithm consistent with the Ito stochastic calculus is in agreement with the predictions of that theory, whereas experiments with an analogue simulator yield measured results in agreement with the predictions of the Stratonovich theory.     

Trace determination of platinum-I. A catalytic method using pulse polarography

Experimental conditions are given for the development of a well-defined catalytic polarographic wave for PT(II) after chelation with ethylenediamine. Direct-current polarographic studies of the wave characteristics indicate that it is of the catalytic hydrogen type, sensitive to pH changes, temperature, and electrode characteristics. By differential pulse polarography a single, sharp peak at -1.62 V is obtained, allowing trace determination of Pt(II) in the range 0.01-1.0 ppm with a linear calibration and a detection limit of 0.003 ppm. The catalytic wave is shown to suffer little interference from other platinum-group metals at 1:1 concentration ratio to Pt, except for Rh(III).     

A critical evaluation of fluorometric methods for determination of selenium in plant materials with 2,3-diaminonaphthalene

The published methods for fluorometric determination of Se in plants are reviewed, with particular attention to those using 2,3-diaminonaphthalene as the fluorometric reagent. Two steps in the analysis are shown to be critical: the final stages of the digestion and the complete conversion of the Se to Se(IV). A modified experimental procedure is given.