Conformational Equilibrium and Potential Energy Functions of the O–H Internal Rotation in the Axial and Equatorial Species of 1‑Methylcyclohexanol

The rotational spectra of four conformers (At, Ag, Et, Eg) of the tertiary alcohol 1-methylcyclohexanol were assigned by pulsed jet Fourier transform microwave spectroscopy. The transitions of two gauche conformers were split in two separated component lines, but it was not possiblefrom the available measured transitionsto accurately determine their vibrational Δ<i>E</i>_0+0‑ ground-state splittings, respectively. In addition, the rotational spectra of the four OD deuterated isotopologues were measured and assigned. For the gauche species of this isotopologue we were able to determine the tunneling splittings, Δ<i>E</i>_0+0‑(Ag, OD) = 15.581(5) GHz and Δ<i>E</i>_0+0‑(Eg, OD) = 18.17(3) GHz, respectively. From these splittings the inversion barriers for Ag and Eg were determined, by using a flexible model, to be <i>B</i>₂(Ag) = 356(10) and <i>B</i>₂(Eg) = 320(10) cm^–1, respectively

Media 2: Ultra-stable and versatile widefield cryo-fluorescence microscope for single-molecule localization with sub-nanometer accuracy

Originally published in Optics Express on 09 February 2015 (oe-23-3-3770

The rotational spectrum of methyl trifluoroacetate

<p>The pulsed supersonic jet expansion microwave spectra of the parent and all three ¹³C mono-substituted isotopologues of methyl trifluoroacetate have been measured in the 6.5–18 GHz range. All observed transitions are split into two component lines, due to the internal rotation of the methyl group. The corresponding barrier has been determined to be <i>V</i> ₃ = 4.379(3) kJ/mol. Structural information has been obtained from the 12 available rotational constants.</p

Site-Selective Dissociation Processes of Cationic Ethanol Conformers: The Role of Hyperconjugation

In present report, we explored hyperconjugation effects on the site- and bond-selective dissociation processes of cationic ethanol conformers by the use of theoretical methods (including configuration optimizations, natural bond orbital (NBO) analysis, and density of states (DOS) calculations, etc.) and the tunable synchrotron vacuum ultraviolet (SVUV) photoionization mass spectrometry. The dissociative mechanism of ethanol cations, in which hyperconjugative interactions and charge-transfer processes were involved, was proposed. The results reveal C_α–H and C–C bonds are selectively weakened, which arise as a result of the hyperconjugative interactions σ_Cα‑H → p in the trans-conformer and σ_C–C → p in gauche-conformer after being ionized. As a result, the selective bond cleavages would occur and different fragments were observed

Additional file 1 of Multi-omics study identifies that PICK1 deficiency causes male infertility by inhibiting vesicle trafficking in Sertoli cells

Supplementary Material

Le Monde

31 mars 18691869/03/31 (N87,A10).Appartient à l’ensemble documentaire : BbLevt

Charge-Driven Fluorescence Blinking in Carbon Nanodots

This study focuses on the mechanism of fluorescence blinking of single carbon nanodots, which is one of their key but less understood properties. The results of our single-particle fluorescence study show that the mechanism of carbon nanodots blinking has remarkable similarities with that of semiconductor quantum dots. In particular, the temporal behavior of carbon nanodot blinking follows a power law both at room and at cryogenic temperatures. Our experimental data suggest that static quenching via Dexter-type electron transfer between surface groups of a nanoparticle plays a major role in the transition of carbon nanodots to off or gray states, whereas the transition back to on states is governed by an electron tunneling from the particle’s core. These findings advance our understanding of the complex mechanism of carbon nanodots emission, which is one of the key steps for their application in fluorescence imaging

Super-Resolution Optical Fluctuation Bio-Imaging with Dual-Color Carbon Nanodots

Success in super-resolution imaging relies on a proper choice of fluorescent probes. Here, we suggest novel easily produced and biocompatible nanoparticlescarbon nanodotsfor super-resolution optical fluctuation bioimaging (SOFI). The particles revealed an intrinsic dual-color fluorescence, which corresponds to two subpopulations of particles of different electric charges. The neutral nanoparticles localize to cellular nuclei suggesting their potential use as an inexpensive, easily produced nucleus-specific label. The single particle study revealed that the carbon nanodots possess a unique hybrid combination of fluorescence properties exhibiting characteristics of both dye molecules and semiconductor nanocrystals. The results suggest that charge trapping and redistribution on the surface of the particles triggers their transitions between emissive and dark states. These findings open up new possibilities for the utilization of carbon nanodots in the various super-resolution microscopy methods based on stochastic optical switching