Two-Photon Fluorescence Lysosomal Bioimaging with a Micelle-Encapsulated Fluorescent Probe

We report two-photon fluorescence microscopy (2PFM) imaging and in vitro cell viability of a new, efficient, lysosome-selective system based on a two-photon absorbing (2PA) fluorescent probe (I) encapsulated in Pluronic® F-127 micelles. Preparation of dye I was accomplished via microwave-assisted synthesis, resulting in improved yields and reduced reaction times. Photophysical characterization revealed notable 2PA efficiency of this probe.     

Evaluation of spin labels for in-cell EPR by analysis of nitroxide reduction in cell extract of Xenopus laevis oocytes

Spin-label electron paramagnetic resonance (SL-EPR) spectroscopy has become a powerful and useful tool for studying structure and dynamics of biomacromolecules. However, utilizing these methods at physiological temperatures for in-cell studies is hampered by reduction of the nitroxide spin labels and thus short half-lives in the cellular environment. Consequently, reduction kinetics of two structurally different nitroxides was investigated in cell extracts of Xenopus laevis oocytes using rapid-scan cw-experiments at X-band. The five member heterocyclic ring nitroxide PCA (3-carboxy-2,2,5,5-tetramethylpyrrolidinyl-1-oxy) under investigation features much higher stability against intracellular reduction than the six member ring analog TOAC (2,2,6,6-tetramethylpiperidine-N-oxyl-4-amino-4-carboxilic acid) and is therefore a suitable spin label type for in-cell EPR. The kinetic data can be described according to the Michaelis–Menten model and thus suggest an enzymatic or enzyme-mediated reduction process.     

Small-molecule-triggered manipulation of DNA three-way junctions

DNA three-way junctions are frequently used in nanoarchitectures. Ligand-dependent designs that provide well-characterized building blocks for structure-switching DNA nanodevices are presented.     

Site‐Selective Late‐Stage Aromatic [18F]Fluorination via Aryl Sulfonium Salts

Site‐selective functionalization of C?H bonds in small complex molecules is a long‐standing challenge in organic chemistry. Herein, we report a broadly applicable and site‐selective aromatic C?H dibenzothiophenylation reaction. The conceptual advantage of this transformation is further demonstrated through the two‐step C?H [¹⁸F]fluorination of a series of marketed small‐molecule drugs.     

Quantum chemical study of the mechanism of the catalytic oxyethylation of ethylene glycol on phosphorus-doped titanium dioxide: The role of the surface phosphoryl and hydroxyl groups of the catalyst

DFT calculations of the oxyethylation pathways of monoethylene glycol (MEG) and diethylene glycol (DEG) were performed on a model fragment of phosphorus-doped titanium dioxide (anatase). It was shown that the surface hydroxyl group of titanium dioxide, whose proton initiates C-O bond cleavage in the ethylene oxide molecule, plays the key role in the activation of the molecule. At the same time, the phosphoryl group -P(OH)₂O activates the reactant molecule R (MEG, DEG, etc.) and carries out the synchronous proton transfer from R to the hydroxyl oxygen atom of titanium dioxide, thus restoring the catalyst structure and closing the catalytic cycle. This restructuring occurs synchronously in one step. The substitution of the catalyst hydroxyl groups by alkoxyl groups can influence oxyethylation occurring via the bimolecular nucleophilic substitution mechanism and can poison the catalyst in some cases.     

Fast factorization of rectangular Vandermonde matrices with Chebyshev nodes

Numerical Algorithms - The polynomial interpolation problem with distinct interpolation points and the polynomial represented in the power basis gives rise to a linear system of equations with a...     

Equation of state for the 3-D Ising model from microscopic level calculations

A new method to derive the equation of state for the 3-D Ising model on a simple cubic lattice with an exponentially decreasing potential is proposed. This equation describes the order parameter of the system as a function of temperature, external field, and microscopic parameters of the system in the critical region. Numerical investigation of this function is performed for the case where the potential parameters correspond to the nearest neighbor interactions.Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 107, No. 2, pp. 288–306, May, 1996.Translated by V. I. Serdobol'skii.     

Order parameters and the free energy of the three-dimensional ising model below the transition temperature

L'vov Branch, Institute of Theoretical Physics, Ukrainian SSR Academy of Sciences. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 79, No. 1, pp. 135–145, April, 1989.     

Solid II–VI Solutions as active media for a laser electron-beam-tube

The properties of laser electron-beam-tube (LEBT) laser elements based on solid solutions of II-VI semiconductor compounds are presented. The fundamental absorption edges of these compounds are investigated. Their radiative properties are analyzed. A correlation is found between the emissivities of solid solutions, the characteristics of their fundamental absorption, and the results of investigations of laser elements based on these compounds. It is shown that Zn_1–xCd_xS and Zn_1–xSe are promising solid solutions for use in LEBT operating at T>80 K, while CdS_1–xSe_x and ZnS_1–xSe_x are promising at T<150 K.P. N. Lebedev Physics Institute. Translated from Preprint No. 145 of the Lebedev Institute of Physics, Academy of Sciences of the USSR, Moscow, 1989.     

Isolated quantum emitters originating from defect centers in a ZnSe/ZnMgSSe heterostructure

On the basis of low-temperature (5 K) microphotoluminescence measurements in a wide ZnSe/ZnMgSSe quantum well, the existence of isolated quantum emitters in this heterostructure is demonstrated. Characteristically, the corresponding emission lines experience stepwise spectral shifts by a few meV on a time scale of 1–10 min. The unconventional properties of the observed emitters are explained by considering the picture of a system with a large dipole moment in the ground state, such as a single donor–acceptor pair or a similar system located near an extended defect.