On a Property of Rearrangement Invariant Spaces whose Second Köthe Dual is Nonseparable

Mathematical Notes - We study the family of rearrangement invariant spaces E containing subspaces on which the E-norm is equivalent to the L1-norm and a certain geometric characteristic related to...     

EPR and ENDOR study of carbon-mineral sorbents

A character of carbon ordering in carbon mineral systems, such as γ-Al₂O₃ and TiO₂ has been investigated using EPR and ENDOR methods. The experimental data have been interpreted at the assumption that a spatial distribution of paramagnetic centers on the surface of aluminum-oxide is 2-dimensional. The results of ENDOR measurements show that no stable covalent bond is formed between the mineral support surface and coke upon carbonization of aluminum oxide by divinyl. The interaction has mainly the ionic character and is easily affected by water.     

Optimization of Pulsed-DEER Measurements for Gd-Based Labels: Choice of Operational Frequencies, Pulse Durations and Positions, and Temperature

In this work, the experimental conditions and parameters necessary to optimize the long-distance (≥60 Å) double electron–electron resonance (DEER) measurements of biomacromolecules labeled with Gd(III) tags are analyzed. The specific parameters discussed are the temperature, microwave band, the separation between the pumping and observation frequencies, pulse train repetition rate, pulse durations and pulse positioning in the electron paramagnetic resonance spectrum. It was found that: (1) in optimized DEER measurements, the observation pulses have to be applied at the maximum of the electron paramagnetic resonance spectrum; (2) the optimal temperature range for K_a-band measurements is 14–17 K, while in W-band the optimal temperatures are between 6 and 9 K; (iv) W-band is preferable to K_a-band for DEER measurements. Recent achievements and the conditions necessary for short-distance measurements (<15 Å) are also briefly discussed.     

Randomized Operators on {n\times n} Matrices and Applications

Some combinatorial and probabilistic estimates motivated by earlier works due to S. Kwapien and C. Schütt are proved. We study these estimates in the general setting of rearrangement invariant function and sequence spaces and identify the class of function spaces in which such estimates hold. We demonstrate the sharpness of our results and present some applications, one of which is an alternative proof of a familiar Raynaud–Schütt theorem describing symmetric subspaces in \({L_1}\).     

Tripyrrindione as a Redox‐Active Ligand: Palladium(II) Coordination in Three Redox States

The tripyrrin‐1,14‐dione scaffold of urinary pigment uroerythrin coordinates divalent palladium as a planar tridentate ligand. Spectroscopic, structural and computational investigations reveal that the tripyrrindione ligand binds as a dianionic radical, and the resulting complex is stable at room temperature. One‐electron oxidation and reduction reactions do not alter the planar coordination sphere of palladium(II) and lead to the isolation of two additional complexes presenting different redox states of the ligand framework. Unaffected by stability problems common to tripyrrolic fragments, the tripyrrindione ligand offers a robust platform for ligand‐based redox chemistry.     

Vector-valued sums of independent functions in rearrangement invariant spaces

We obtain some relations that describe the behavior of vector-valued Gaussian sums in rearrangement invariant spaces on the square whose character depends on whether the lower Boyd index of the space is trivial or not. Similar results are proven for the general systems of independent identically and symmetrically distributed random variables.     

Determination of the hydration number of gadolinium(III) complexes by high-field pulsed 17O ENDOR spectroscopy.

Pulsed 17O Mims electron-nuclear double resonance (ENDOR) spectroscopy at the W band (95 GHz) and D band (130 GHz) is used for the direct determination of the water coordination number (q) of gadolinium-based magnetic resonance imaging (MRI) contrast agents. Spectra of metal complexes in frozen aqueous solutions at approximately physiological concentrations can be obtained either in the presence or absence of protein targets. This method is an improvement over the 1H ENDOR method described previously, which involved the difference ENDOR spectrum of exchangeable protons from spectra taken in H2O and D2O. In addition to exchangeable water protons, the 1H ENDOR method is also sensitive to other exchangeable protons, and it is shown here that this method can overestimate hydration numbers for complexes with exchangeable protons at GdH distances similar to that of the coordinated water, for example, from NH groups. The 17O method does not suffer from this limitation. 17O ENDOR spectroscopy is applied to Gd(III) complexes containing zero, one, or two inner-sphere water molecules. In addition, 13C and 1H ENDOR studies were performed to assess the extent of methanol coordination, since methanol is used to produce a glass in these experiments. Under the experimental conditions used for the hydration number determination (30 mol % methanol), fewer than 15 % of the coordination sites were found to be occupied by methanol.