Fluorogenic Protein Probes with Red and Near-Infrared Emission for Genetically Targeted Imaging**

Fluorogenic probes are important tools to image proteins with high contrast and no wash protocols. In this work, we rationally designed and synthesized a small set of four protein fluorogens with red or near-infrared emission. The fluorophores were characterized in the presence of albumin as a model protein environment and exhibited good fluorogenicity and brightness (fluorescence quantum yield up to 36 %). Once conjugated to a haloalkane ligand, the probes reacted with the protein self-labeling tag HaloTag with a high fluorescence enhancement (up to 156-fold). The spectroscopic properties of the fluorogens and their reaction with HaloTag were investigated experimentally in vitro and with the help of molecular dynamics. The two most promising probes, one in the red and one in the near-infrared range, were finally applied to image the nucleus or actin in live-cell and in wash-free conditions using fluorogenic and chemogenetic targeting of HaloTag fusion proteins.     

Study of polycarbonate–bismuth nitrate composite for shielding against gamma radiation

Journal of Radioanalytical and Nuclear Chemistry - Polycarbonate (PC) loaded with different filler levels equal to 0.1, 0.2, 0.3, 0.5, 0.75, 1.0, 2.5, 3.5 and 5.0 wt% (weight percent) of...     

Similarities in photon and ion emissions induced by sputtering

It is now well known that the photon and ion emissions which result from the sputtering of metals by ion bombardment depend strongly on the surface composition. Recently R. Kelly and C.B. Kerkdijk, and G. Blaise and M. Bernheim, reported respectively on the intensification of both emissions produced by the adsorption of oxygen on a metal surface (this intensification corresponds to the so-called chemical effect). Their experiments were carried out approximately under the same sputtering conditions. Photon and ion yields were studied as a function of oxygen pressure and primary current density. A comparison of the results reveals some similarities in the behaviour of the two emissions. Our purpose is to underline these similarities and their consequences concerning the processes which give rise to photon and ion emissions.     

Optimization of structural topology in the high-porosity regime

We propose a new approach to topology optimization, based on the use of “single-scale laminates” as structural components. The method is well-founded, because in the high porosity limit these structures achieve maximal stiffness and minimal weight. The method is useful, because the Hooke's law of a single-scale laminate has a simple, explicit formula which scales linearly with weight. And it is interesting, because the selection of relatively simple, manufacturable designs can be addressed using linear or quadratic programming. Our contributions are two-fold: (a) we establish the foundation of this approach, by defining single-scale laminates and giving self-contained proofs of their optimality in the high-porosity limit; and (b) we explore two numerical applications—minimizing weight with a constraint on the Hooke's law, and imposing continuity on a spatially varying microstructure.     

Alkaloids from the stem bark of Turraeanthus africanus (Meliaceae)

Fractionation of the methanol extract of the stem bark of Turraeanthus africanus led to the isolation of two new alkaloids designated turraeanthin A and B, together with two known alkaloids. The structures of the new alkaloids were elucidated by means of spectroscopic analysis and characterized as 10-O-demethyl-17-O-methyl isoarnottianamide and 11-demethoxyl-12-methoxyl oxynitidine respectively.     

Theoretical interpretation of the line shape of crystalline adipic acid

A general quantum theoretical approach of the upsilon(X-H) IR line shape of cyclic dimers of weakly H-bonded species in the crystal state is proposed. In this model, the adiabatic approximation (allowing to separate the high-frequency motion from the slow one of the H-bond bridge) is performed for each separate H-bond bridge of the dimer and a strong nonadiabatic correction is introduced into the model via the resonant exchange between the fast-mode excited states of the two moieties. Quantum indirect damping and Fermi resonances are taken into account. The present model reduces satisfactorily to many models in the literature dealing with more special situations. It has been applied to the cyclic dimers of adipic acid in the crystal phase. It correctly fits the experimental line shape of the hydrogenated compound and predicts satisfactorily the evolution in the line shapes with temperature and the change in the line shape with isotopic substitution.     

Oscillatory Singularities in Bianchi Models with Magnetic Fields

An idea which has been around in general relativity for more than 40  years is that in the approach to a big bang singularity solutions of the Einstein equations can be approximated by the Kasner map, which describes a succession of Kasner epochs. This is already a highly non-trivial statement in the spatially homogeneous case. There the Einstein equations reduce to ordinary differential equations and it becomes a statement that the solutions of the Einstein equations can be approximated by heteroclinic chains of the corresponding dynamical system. For a long time, progress on proving a statement of this kind rigorously was very slow but recently there has been new progress in this area, particularly in the case of the vacuum Einstein equations. In this paper we generalize some of these results to cases where the Einstein equations are coupled to matter fields, focussing on the example of a dynamical system arising from the Einstein–Maxwell equations with symmetry of Bianchi type VI₀. It turns out that this requires new techniques since certain eigenvalues are in a less favourable configuration than in the vacuum case. The difficulties which arise in that case are overcome by using the fact that the dynamical system of interest is of geometrical origin and thus has useful invariant manifolds.     

Experimental investigation of radiation transmission through a water spray

Radiation attenuation by a water spray is experimentally investigated. Spectral transmissivity measurements are performed between 1000 and with an experimental device involving a Fourier transform spectrometer. The spray is produced by a so-called Tee-Jet 400 067 nozzle for water pressure between 1.5 and 6 bar. Key features like mean attenuation levels due to absorption and scattering by droplets and complex absorption pattern by water vapor are identified. Known effect of attenuation modification when increasing the water pressure is observed. A simulation is also performed to evaluate a numerical code developed in a companion study. The achieved agreement demonstrates the ability of the simulation to describe the radiation attenuation by the spray.     

Isotopieverschiebungskonstanten von Th,U, Pu und Am

The isotope shifts of unperturbed electron configurations have been determined from isotope shift measurements in the spectra of Th, U, Pu, and Am. The screening of the 7s electron charge density at the nucleus by 6d, 7s, and 7p electrons is discussed. It turns out that the same screening factors as for the 6s electron in lighter elements can be used. The screening of the 7s electron charge density at the nucleus by one 5f electron amounts to about 25%: [δT(f ⁿ s)?δT(f ⁿ )]/[δT(f ⁿ }s)?δ(f ^n} )]=0.7₅. The charge density at the nucleus due to the filleds (andp _1/2) shells is considerabely screened by anf electron. The isotope shiftδT(f^n}-1 d ^m +2)?δT(f ⁿ d ^m ) produced by this effect is of the same order of magnitude as the isotope shiftδT(f ⁿ d ^m s)-δT(f ⁿ d ^m ) due to ans electron. The experimental isotope shift constants are found to be:Β C _exp(Th²³⁰–Th²³²)=880±120;Β C _exp(U²³³–U²³⁵)=1000±180;Β C _exp(U²³⁴–U²³⁶)=1070±200;Β C _exp(U²³⁶–U²³⁸)=1080±180;Β C _exp(Pu²³⁸–Pu²⁴⁰)=1200±120;Β C _exp(Pu²³⁹–Pu²⁴¹)=1060±100;Β C _exp(Pu²⁴⁰–Pu242)=900 ±90;Β C _exp(Am²⁴¹–Am²⁴³)=890±50 [10^?3cm^?1]. The ratiosΒ C _exp/C _th are discussed.     

Charge-induced fragmentation of sodium clusters

The fission of highly charged sodium clusters with fissilities X>1 is studied by ab initio molecular dynamics. Na4+24 is found to undergo predominantly sequential Na+3 emission on a time scale of 1 ps, while Na(Q+)(24) ( 5< or =Q< or =8) undergoes multifragmentation on a time scale > or =0.1 ps, with Na+ increasingly the dominant fragment as Q increases. All singly charged fragments Na(+)(n) up to size n = 6 are observed. The observed fragment spectrum is, within statistical error, independent of the temperature T of the parent cluster for T< or =1500 K. These findings are consistent with and explain recent trends observed experimentally.