Synthesis and spectroscopic characterization of red-shifted spironaphthoxazine based optical switch probes

Spironaphthoxazine (NISO) is an efficient optical switch probe that has applications in high contrast detection of Förster resonance energy transfer (FRET) using optical lock-in detection (OLID). NISO exists in two distinct states, spiro (SP) and merocyanine (MC), that can be independently controlled by using alternate irradiation with near ultraviolet and visible light. Unfortunately, the SP-state of NISO has an absorption centered at 350 nm, which may lead to phototoxic effects when manipulating the probe within a living cell. To overcome this problem we introduce new, red-shifted amino-substituted NISO probes compared to NISO that undergo an efficient SP to MC transition in response to irradiation by using 405-nm light, which is less damaging to living cells. This study details the synthesis of amino-substituted NISO and their N-hydroxysuccinimide ester and maleimide derivatives and their use in generating covalent attached protein conjugates. This study also presents a characterization of the spectroscopic and optical switching properties of these red-shifted NISO probe in solution.     

Polynuclear Cu(II), Ni(II) and Cd(II) coordination compounds with bis(pyrimidin-2-yl)amine and dicyanamide

In this study the synthesis, crystal structure and characterization of three new transition metal polynuclear compounds with formula [Cu(dipm)(μ-dca)₂]_n(H₂O) (1), [Ni(dipm)(μ-dca)₂]_n(C₂H₆O)_1/2 (2) and [Cd(dipm)(μ-dca)₂]_n (3) (in which dipm = bis(pyrimidin-2-yl)amine and dca = dicyanamide) are reported. The isostructural compounds 1 and 2 contain a double-bridging end-to-end dca unit connecting two metal ions and a single bridging end-to-end dca unit between subsequent metals. Compound 3 exhibits only single bridging end-to-end dca units, oriented in three directions, giving rise to a 3D framework.     

Evidence for helical edge modes in inverted InAs/GaSb quantum wells

We present an experimental study of low temperature electronic transport in the hybridization gap of inverted InAs/GaSb composite quantum wells. An electrostatic gate is used to push the Fermi level into the gap regime, where the conductance as a function of sample length and width is measured. Our analysis shows strong evidence for the existence of helical edge modes proposed by Liu et al [Phys. Rev. Lett. 100, 236601 (2008)]. Edge modes persist in spite of sizable bulk conduction and show only a weak magnetic field dependence-a direct consequence of a gap opening away from the zone center.     

The 2-concavification of a Banach lattice equals the diagonal of the Fremlin tensor square

We investigate the relationship between the diagonal of the Fremlin projective tensor product of a Banach lattice E with itself and the 2-concavification of E.     

Further advances on low-energy lunar impact dynamics

We extend the analysis, started in a previous work [1], concerning the formation of lunar impact craters due to low-energy trajectories. First, we adopt the Circular Restricted Three-Body Problem and consider different choices of initial conditions inside the stable invariant manifold associated with the central invariant one in the neighborhood of the L₂ equilibrium point in the Earth-Moon system. Then we move to the Bicircular Restricted Four-Body Problem to study the effect of the Sun on the distribution of impacts on the Moon’s surface.     

Effect of instrumental particle sizing resolution on the modelling of aerosol radiative parameters

A more realistic estimation of the scattering and hemispheric backscattering coefficients, σ_sp and σ_bsp, and their respective optical cross section, C_sca and C_bk, of aerosol particles is presented on the basis of the exact resolution of the width of the size bins of the particle counter instruments when size distribution measurements are used, and, with the exact optical detector instruments ability. The scattering and hemispheric backscattering cross sections, C_sca and C_bk, of the particles are averaged over the full size bins of the particle counter instrument, while these quantities are usually estimated only on the value of the mean geometric diameter of each size bin. Six instruments, the APS, ASASP-X, DMPS, FSSP-100, ELPI, and SMPS frequently used in particle size distribution measurements are reviewed, for spherical sea-salt particles at a wavelength λ=0.55 μm. The comparison using the conventional geometric mean diameter versus the use of the full size bin leads to large amount of errors for the optical cross section with non-negligible effects on their respective optical coefficients. The maximal accuracy expected for these optical quantities depend on the particle diameter as well as on the channel width of the instruments, and are also function of the angular detector probe used to measure them.