Search

Although traditional nuclear magnetic resonance (NMR) spectroscopy is essential for investigating the structures and dynamics of biomolecules, it is impeded by low sensitivity, particularly under physiological conditions. Hyperpolarization techniques, which considerably amplify NMR signal intensity, have emerged as novel solutions in this field. Among the various hyperpolarization techniques and applications, hyperpolarized water obtained using dissolution dynamic nuclear polarization has been extensively used for the study of biomolecules. This review details the findings of NMR studies involving hyperpolarized water and its potential for biomolecular studies, with applications spanning from revealing molecular interactions under challenging experimental conditions to facilitating real-time NMR applications during structural changes in biomolecules. Further studies are required to thoroughly understand polarization transfer from hyperpolarized water, propelling this field toward unprecedented possibilities and providing biological insights. [ABSTRACT FROM AUTHOR]

This study introduces a novel and versatile method for synthesizing honeycomb‐structured silicon carbide (SiC). The innovative approach utilizes a sucrose solution as the carbon source and nonporous silica spheres, which serve both as silicon precursors and templates, allowing for precise control over pore sizes. Notably, the process is characterized by its cost‐effectiveness, eco‐friendliness, and the utilization of milder conditions attributed to magnesiothermic reduction. The tunable pore sizes achieved through adjustments in the size of silica particles offer a versatile platform for customizing SiC materials to meet specific application requirements. Beyond its customizable nature, the method reduces the environmental footprint of SiC synthesis by utilizing eco‐friendly materials. Its combined attributes of accessibility, sustainability, and performance optimization underscore its potential for driving advancements in SiC‐based applications across various industrial and scientific domains. [ABSTRACT FROM AUTHOR]

This study demonstrated the potential of 50 nm PEGylated Si NPs for high-resolution in vivo29Si MR imaging, emphasizing their biocompatibility and water dispersibility. The acquisition of in vivo Si MR images using the lowest reported dose after subcutaneous and intraperitoneal administration opens new avenues for future 29Si MR studies. [ABSTRACT FROM AUTHOR]

To comply with stringent CO2 regulations, enhanced thermal efficiency has been prioritized in internal combustion engine development; however, this has strongly driven the development of engines with operating conditions more prone to knock. Current knock sensors have its limitations to decompose knock signal by degradation so that it required a cross-referencing signal. In addition, knock control intervention is currently preceded by the occurrence of the knock, leading to decrease in thermal efficiency by retarding spark timing. In the present work, a novel prediction model for knock propensity (incidence) is presented, aiming to enable active control of knock or autoignition, and to support conventional knock sensor for cross-referencing by facilitating virtual knock sensor. A zero-dimensional model-based prediction of the in-cylinder pressure is demonstrated to prevent using in-cylinder pressure transducer, along with other incorporated predictive sub-models for the residual gas fraction, heat loss, burn duration, and heat release rate. Ignition delay correlation and Livengood-Wu relation are used to predict the onset of knock, and a burn point-based criterion is newly proposed for application in stochastic modeling for determining the knock propensity. The predicted knock propensity from the combined holistic model shows a remarkable agreement with experimental results. [ABSTRACT FROM AUTHOR]

The embedding of radicals at different locations within core@shell silica nanoparticles contributes to enhanced polarization capability and can be self-polarized without adding external radicals. With grafting the radical source homogenously inside of the nanoparticles, a significant 29Si hyperpolarization signal enhancement of 49.4 was obtained. [ABSTRACT FROM AUTHOR]

Emerging techniques for hyperpolarization of nuclear spins, foremost dynamic nuclear polarization (DNP), lend unprecedented sensitivity to nuclear magnetic resonance spectroscopy. Sufficient signal can be obtained from a single scan, and reactions even far from equilibrium can be studied in real-time. When following the progress of a reaction by nuclear magnetic resonance, however, spin relaxation occurs concomitantly with the reaction to alter resonance line intensities. Here, we present a model for accounting for spin-relaxation in such reactions studied by hyperpolarized NMR. The model takes into account auto- and cross-relaxation in dipole-dipole coupled spin systems and is therefore applicable to NMR of hyperpolarized protons, the most abundant NMR-active nuclei. Applied to the Diels--Alder reaction of 1,4-dipheneylbutadiene (DPBD) with 4-phenyl-1,2,4-triazole-3,5-dione (PTD), reaction rates could be obtained accurately and reproducibly. Additional parameters available from the same experiment include relaxation rates of the reaction product, which may yield further information about the molecular properties of the product. The method presented is also compatible with an experiment where a single spin in the reactant is labeled in its spin-state by a selective radio frequency pulse for subsequent tracking through the reaction, allowing the unambiguous identification of its position in the product molecule. In this case, the chemical shift specificity of high-resolution NMR can allow for the simultaneous determination of reaction rates and mechanistic information in one experiment. 10.1021/ac101670n