Supercritical fluid chromatography with redox chemiluminescence detection

Summary The new selective and sensitive redox chemiluminescence detector (RCD), originally developed for gas chromatography, has been successfully interfaced with a capillary column supercritical fluid chromatograph. Interfacing the SFC-RCD was accomplished simply through utilization of the redox reaction chamber presently used for both capillary and packed column GC. The feasibility of this new separation-detection scheme was demonstrated with SFC chromatograms of antioxidant isomers and some compounds of biological relevance. Mobile phase compatibility and signal quenching are also discussed.

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Chromatographie mit überkritischen fluiden phasen unter Verwendung der Redox-Chemiluminescenz-Detektion

     

The first rhodaboratrane: [RhCl(PPh3){B(mt)3}](Rh-->B)(mt = methimazolyl)

The reaction of [Rh(C6H5)Cl2(PPh3)2] with Na[HB(mt)3](mt = methimazolyl) provides [RhCl(PPh3){B(mt)3}](Rh-->B) the first authentic example of a compound with a rhodium-boron dative bond.     

Impacts of professional development focused on teaching engineering applications of mathematics and science

With the recent national emphasis on preparing children for future careers in science, technology, engineering, and mathematics, K-12 teachers are being called upon to include engineering in their instruction. This study explores the impacts of a summer professional development (PD) program focused on the engineering applications of mathematics and science on in-service K-12 teachers' (a) personal engineering efficacy, (b) engineering teaching efficacy, and (c) perceived barriers to teaching engineering. This quantitative study revealed that a single engineering-focused PD could increase teachers' personal engineering efficacy and engineering teaching efficacy and reduce particular perceived barriers to teaching engineering. No differences existed in pre- to post workshop assessment scores based on grade level taught, gender, or years of teaching experiences. However, pre- to post workshop assessment differences existed between participants depending on the discipline they taught and wether or not they had previously used engineering activities in their classrooms. These findings suggest that a single engineering PD can have significant impacts on in-service teachers' personal engineering efficacy, engineering teaching efficacy, and perceived barriers to teaching engineering, but a one-size-fits-all approach to such PD is not equally effective for all participants.     

Determination of the three-dimensional orientation of single molecules

A simple method for real-time determination of the full three-dimensional orientation of the emission dipole of single molecules is presented. Introduction of a pi phase step in the back focal plane of the collector lens breaks the inherent symmetry, allowing the longitudinal dipole component to be measured. Experimental tolerances and the consequence of a nonzero bandwidth emission spectrum are also discussed. The scheme also allows for the longitudinal component of an electric field to be found experimentally.     

A Continuous-Wave Ho：YA103 Laser with Output 8.5 W Pumped by a 1.91μm Laser at Room Temperature

A cw high efficient Ho：YAI03 laser pumped by 1.91 μm diode-pumped Tm：YLF laser at room temperature is realized. The maximum output power reaches 8.5 W when the incident pump power is 15.6 W. The slope efficiency is 63.7%, and the Tm：YLF to Ho：YAP optical conversion efficiency is 54.5%. The laser wavelength is 2118.3nm when the transmission of output coupler is 30%. The beam quality factor is M2 -1.39 measured by the traveling knife-edge method.     

Enhanced nanoparticle detection with liquid droplet resonators

Whispering gallery mode particle sensing experiments are commonly performed with solid resonators, whereby the sensing volume is limited to the weak evanescent tail of the mode near the resonator surface. In this work we discuss in detail the sensitivity enhancements achievable in liquid droplet resonators wherein the stronger internal fields and convenient means of particle delivery can be exploited. Asymptotic formulae are derived for the relative resonance shift, line broadening and mode splitting of TE and TM modes in liquid droplet resonators. As a corollary the relative fraction of internal and external mode energy follows, which is shown to govern achievable sensitivity enhancements of solute concentration measurements in droplet sensors. Experimental measurements of nanoparticle concentration based on whispering gallery mode resonance broadening are also presented.     

What do gas-rich galaxies actually tell us about modified Newtonian dynamics?

It has recently been claimed that measurements of the baryonic Tully-Fisher relation (BTFR), a power-law relationship between the observed baryonic masses and outer rotation velocities of galaxies, support the predictions of modified Newtonian dynamics for the slope and scatter in the relation, while challenging the cold dark matter (CDM) paradigm. We investigate these claims, and find that (1)?the scatter in the data used to determine the BTFR is in conflict with observational uncertainties on the data, (2)?these data do not make strong distinctions regarding the best-fit BTFR parameters, (3)?the literature contains a wide variety of measurements of the BTFR, many of which are discrepant with the recent results, and (4)?the claimed CDM "prediction" for the BTFR is a gross oversimplification of the complex galaxy-scale physics involved. We conclude that the BTFR is currently untrustworthy as a test of CDM.     

Corrigendum to “Complex contact Lie groups and generalized complex Heisenberg groups” [Differential Geom. Appl. 24 (2006) 443-446]

We restate and prove the main theorem of the paper “Complex contact Lie groups and generalized complex Heisenberg groups”.