Water 2H and 17O spin relaxation is used to study water dynamics in the hydration layers of two small peptides, globular proteins living cells microorganisms. The dynamical heterogeneity characterized by performing measurements over a wide temperature range, extending deeply into supercooled regime, or covering frequency range. Protein can be described power-law distribution rotational correlation times with an exponent close 2. This comprises fraction protein-specific sites, where rotation...

Structural dynamics in liquid water slow down dramatically the supercooled regime. To shed further light on origin of this super-Arrhenius temperature dependence, we report high-precision 17O and 2H NMR relaxation data for H2O D2O, respectively, to 37 K below equilibrium freezing point. With aid molecular (MD) simulations, provide a detailed analysis rotational motions probed by experiments. The NMR-derived correlation time τR is integral function (TCF) that, after subpicosecond librational...

Unlike most ordered molecular systems, globular proteins exhibit a temperature of maximum stability, implying that the structure can be disrupted by cooling. This cold denaturation phenomenon is usually linked to temperature-dependent hydrophobic driving force for protein folding. Yet, despite key role played protein−water interactions, hydration changes during have not been investigated experimentally. Here, we use water−17O spin relaxation monitor dynamics BPTI, ubiquitin, apomyoglobin,...

The dynamics of the imidazolium based room temperature ionic liquid Bmim Tf2N was investigated by means nuclear magnetic resonance relaxation dispersion (NMRD) and pulsed field gradient (NMR-PFG) diffusion experiments on bulk in a wide range temperatures. Relaxation properties were determined for anions cations individually, giving evidence heterogeneities liquid. relevant NMR mechanisms are inter- intramolecular dipolar interactions between molecular ions reflecting translational rotational...

The film formation of poly(vinyl alcohol) different molecular weights from concentrated solution has been observed in real time by means low-field nuclear magnetic resonance (NMR) methods. drying films was followed with a depth resolution 50 μm up to the final typically 300 thickness, and mobility determined spatial analyzing NMR relaxation times (T2, T1) behavior. A gradient dynamics T1 data during evaporation process an intermediate when shrinkage rate decreases significantly; T2 indicates...

We study the static and dynamic properties of a cyclic Rouse chain modified by inclusion an effective, spherically symmetric, attracting potential entropic nature , is position vector ring center mass, segment with number n, Boltzmann constant multiplied on absolute temperature, parameter potential, square which inverse to strength potential. It shown that very weak potentials N Kuhn segments in polymer ring, b length segment, lead dramatic compression whose radius inertia becomes much...

Structural features and dynamical behaviour of the copper(ii) bis-complexes with glycine, d-alanine, d-valine, l-serine, l-aspartic acid, l-glutamic l-lysine, l-proline, sarcosine were studied by combined EPR NMR relaxation methods. The cis trans isomers unambiguously assigned characterized data. It was found that addition a salt background has an influence on cis-trans isomer equilibrium in favour formation isomer. By comparison NMRD, DFT computations, structural data it shown only one...

We present a detailed study of electron/nuclear interaction in specific crude oil by continuous-wave and pulsed EPR, electron–nuclear double resonance (ENDOR) at W-band (94 GHz), fast field-cycling dynamic nuclear polarization (FFC-DNP) X-band. A perceptible non-Overhauser (solid) effect is found room temperature as result the transfer from intrinsic "free" radicals to 1H nuclei with different dynamics. On basis analysis longitudinal relaxation times, three dynamical components described...

Dynamic nuclear polarization is a versatile approach to increasing the sensitivity of NMR measurements and achieved by any four different mechanisms which dominate for either liquids or solids, depending on temperature radical density. In this work, we unequivocally demonstrate first time coexistence, at comparable magnitude, several mechanisms, namely Overhauser effect, solid cross-effect/thermal mixing in viscous ionic liquid ambient temperatures.

Abstract The molecular dynamics of the room‐temperature ionic liquid 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide (Bmim Tf2N) confined in porous glass is studied by nuclear magnetic resonance (NMR) relaxometry and diffusometry compared with bulk over a wide temperature range. reorientation processes for anions cations alike are found to be significantly affected presence interface at high temperatures. In this respect, behaves similarly polar liquids where proton NMR...

The presence of paramagnetic species such as vanadyl complexes (VO2+) and free carbon radicals in petroleum disperse systems (PDSs) crude oil, bitumen, or kerogen causes significant interest studying the structure PDS, high-molecular weight components, their effects on physical chemical properties PDS products by magnetic resonance techniques. However, lack detailed studies keeps exact structure, aggregation mechanism, interaction with complex composites still disputable. In this...

Gelatin solutions were prepared in D2O. The drying process of cast was followed with a single-sided nuclear magnetic resonance (NMR) scanner until complete solidification occurred. Spin−spin relaxation times (T2) measured at different layers microscopic resolution and correlated the during film formation. Additionally, evaporation gelatin solution observed optically from reduction sample thickness, revealing that macroscopic level, rate is not uniform throughout experiment. A crossover...

Abstract The thermo‐oxidative degradation behavior of high‐density polyethylene (HDPE) was investigated during oven aging at 100°C. 1 H low‐field solid‐state nuclear magnetic resonance (NMR) used to characterize the behaviors molecular chains and changes in phase content HDPE aging. NMR free induction decays (FIDs) were fitted by three components corresponding crystalline phase, interphase, amorphous respectively. prolongation led a progressive increase expense other two phases. A slight...

Hyperpolarization techniques, such as Overhauser dynamic nuclear polarization (DNP), can provide a dramatic increase in the signal obtained from magnetic resonance experiments and may therefore enable new applications where sensitivity is limiting factor. In this contribution, studies of 1H 19F enhancements at 345 mT are presented for three different aromatic solvents with TEMPO radical range concentrations. Furthermore, relaxation dispersion measurements same solutions analyzed, showing...

The segmental dynamics in molten linear polymers is studied by the NMR method of modulated gradient spin-echo, which directly probes a spectrum molecular velocity autocorrelation function. Diffusion spectra mono-disperse poly(isoprene-1.4) with different masses, measured frequency range 0.1–10 kHz at temperature , have form similar to Rouse chain dynamics, implicates tube-Rouse motion as dominant dynamic process this range. scaling center-of-mass diffusion coefficient, given from fitting...

Determining the dynamics of adsorbed liquids on nanoporous materials is crucial for a detailed understanding interactions and processes solid-liquid interface in many porous systems. Knowledge influence presence paramagnetic species surface or within matrices essential fundamental studies industrial such as catalysts. Magnetic resonance methods, electron (EPR), nuclear magnetic (NMR) dynamic polarization (DNP), are powerful tools to address these questions quantify dynamics, electron-nuclear...

Nuclear magnetic spin-lattice relaxation experiments have been performed in partially filled porous glasses with wetting and nonwetting fluids. The frequency dependence of the rate Vycor (4 nm pores) VitraPOR #5 (1 μm silica was studied as a function filling degree aid field-cycling NMR relaxometry. species primary interest were water (“polar”) cyclohexane (“nonpolar”). Spin-lattice examined range from 1 kHz to 400 MHz relaxometer an ordinary spectrometer. Three different mobility states...

The confinement of polymer melts in nanoscopic pores leads to chain dynamics significantly different from bulk behaviour. This so-called 'corset effect' occurs both above and below the critical molecular mass induces dynamic features as predicted for reptation. confined-to-bulk crossover is treated analytically on basis general thermodynamic relations connected fluctuation number particles (Kuhn segments) a given volume. Bulk behaviour shown occur only if pore diameter complies with limit...

Frequency-dependent NMR relaxation studies have been carried out on water (polar) and cyclohexane (nonpolar) molecules confined inside porous ceramics containing variable amounts of iron oxide (III). The were prepared by compression powders mixed with followed thermal treatment. pore size distribution was estimated using a technique based diffusion in internal fields that exposed narrow macropore sizes an average dimension independent content. dispersion curves obtained at room temperature...