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Metabolism is a fundamental process that underlies human health and diseases. Nuclear magnetic resonance (NMR) techniques offer a powerful approach to identify metabolic processes and track the flux of metabolites at the molecular level in living systems. An in vitro study through in-cell NMR tracks metabolites in real time and investigates protein structures and dynamics in a state close to their most natural environment. This technique characterizes metabolites and proteins involved in metabolic pathways in prokaryotic and eukaryotic cells. In vivo magnetic resonance spectroscopy (MRS) enables whole-organism metabolic monitoring by visualizing the spatial distribution of metabolites and targeted proteins. One limitation of these NMR techniques is the sensitivity, for which a possible improved approach is through isotopic enrichment or hyperpolarization methods, including dynamic nuclear polarization (DNP) and parahydrogen-induced polarization (PHIP). DNP involves the transfer of high polarization from electronic spins of radicals to surrounding nuclear spins for signal enhancements, allowing the detection of low-abundance metabolites and real-time monitoring of metabolic activities. PHIP enables the transfer of nuclear spin polarization from parahydrogen to other nuclei for signal enhancements, particularly in proton NMR, and has been applied in studies of enzymatic reactions and cell signaling. This review provides an overview of in-cell NMR, in vivo MRS, and hyperpolarization techniques, highlighting their applications in metabolic studies and discussing challenges and future perspectives. [ABSTRACT FROM AUTHOR]

The parahydrogen-induced polarization technique allows one to significantly enhance the NMR signal. Novel results on the parahydrogen-induced polarization of C2—C3 hydrocarbons using metal complexes are presented. Gaseous propane with the nuclear spin polarization level of at least 0.8% can be produced by bubbling parahydrogen through a solution of propylene and a homogeneous hydrogenation catalyst. Hydrogenation of acetylene with parahydrogen over Wilkinson's catalyst can result in the formation of hyperpolarized ethylene. The shape of the NMR lines indicates that this reaction proceeds as a syn-addition of molecular hydrogen. The reactions of several ethylene complexes of rhodium and platinum with parahydrogen were studied. The [Rh(η2-C2H4)2Cl]2 complex reacts with parahydrogen to form hyperpolarized ethane, whereas [Pt(η2-C2H4)(PPh3)2] converts to the hyperpolarized dihydride complex cis-[Pt(H)2(PPh3)2]. [ABSTRACT FROM AUTHOR]

The beta-detected nuclear magnetic resonance ( β-NMR) in liquid HO has been observed for the first time using a short-lived β-ray emitter N ( I = 1, T =11 ms). A nuclear spin polarized N beam with an energy of about 20 MeV/nucleon was implanted into an enclosed water sample. About 50 % of implanted N ions maintained nuclear polarization and exhibited a β-NMR spectrum. The chemical shift of N in HO relative to N in Pt was deduced to be −(3.6±0.5) × 10 ppm. [ABSTRACT FROM AUTHOR]

The ground-state energy of polarized and unpolarized liquid He is calculated using the variational theory. A variational wave function is constrained to be normalized appropriately by including the three-body terms in the cluster expansion of the two-body radial distribution function. The higher-order terms have been found to be important to obtain an equation of state which is in agreement with experimental data. The saturation density of unpolarized liquid He was found to be 0.267σ, which decreases by enhancing the polarization. For all relevant densities, the ground-state energy of the spin-polarized system is higher than that in the unpolarized case. [ABSTRACT FROM AUTHOR]

Unique atomic structures at the edges of graphenes yield a variety of interesting phenomena. In spite of carbon-based material with only sp bonds, the zigzag-type atomic structure of graphene edges theoretically produces spontaneous spin polarization of electrons due to mutual Coulomb interaction of extremely high electron density of states localizing at the flat energy band. However, spin-based phenomena have been experimentally observed only in defect-related carbon systems. Here, we fabricate honeycomb-like arrays of low-defect hexagonal nanopores (graphene nanomeshes; GNMs) on graphenes, which produce a large amount of pore edges, by using a nonlithographic method (nanoporous alumina templates). We find large-magnitude ferromagnetism arising from polarized electron spins localizing at the zigzag-nanopore edges of monolayer GNMs. Moreover, spin pumping effect depending on GNM structures is found for magnetic fields applied in parallel with the few-layer GNM planes. These promise to be a realization of rare-element free magnets and also novel all-carbon spintronic devices. [ABSTRACT FROM AUTHOR]

The ab initio calculations of the electronic structure and magnetic properties of the (110) interface between CoYZ (Y = Cr or Mn and Z = Al, Si, or Ge) and GaAs are carried out by means of the density functional theory depending on the contact configuration. It is revealed that two of four possible atomic interface configurations have high spin polarization. For CoMnSi/GaAs(110), one of the contacts has almost 100% spin polarization. Calculations of the adhesion energy on the interfaces allow the most stable contacts to be established. [ABSTRACT FROM AUTHOR]

A new method to produce spin-polarized radioactive nuclear beams has been developed, which takes advantage of the low-energy transfer reaction in inverse kinematics. The method provides beam energies of a convenient range so that they may be implanted in a thin stopper, yet allowing the stopper to be spatially separated from the production target. The presence of polarizations of sizes at least $\left|P\right|\sim 0.5 \%$ has been confirmed for a 17N beam obtained from 9Be(18O,17N) reaction at $\theta_{\rm Lab} \sim -1.7\,^{\circ}$ . [ABSTRACT FROM AUTHOR]

The electronic density of states, spin-splittings and atomic magnetic moments of the six-member ring N2C4 cluster with folding configuration in DNA bases have been studied by spin-polarized MS-Xα method. The results showed that there are at least four metastable states near the ground state level -7.01635×10³ eV. Those metastable states found in the calculation are at the levels -7.01626×10³ -7.01616×10³, -7.01606×10³ and -7.01 597×10³ eV, respectively. The electronic structures of those states were found to differ from each other. Therefore, they have different characteristics. The cluster exhibits metal properties and has a weak antiferromagnetism in the ground state, while it shows ferrimagnetism and half-metal properties in the first metastable state. The distribution of the electronic density of states of the six-member ring N2C4 cluster is very similar to that of some diluted magnetic semiconductors near the Fermi surface. [ABSTRACT FROM AUTHOR]

Full one-loop electroweak corrections for an e-e+→tt¯ process associated with sequential t→bμνμ decay are discussed. At the one-loop level, the spin-polarization effects of the initial electron and positron beams are included in the total and differential cross sections. A narrow-width approximation is used to treat the top-quark production and decay while including full spin correlations between them. We observed that the radiative corrections due to the weak interaction have a large polarization dependence on both the total and the differential cross sections. Therefore, experimental observables that depend on angular distributions such as the forward-backward asymmetry of the top-production angle must be treated carefully including radiative corrections. We also observed that the energy distribution of bottom quarks is largely affected by the radiative corrections. [ABSTRACT FROM AUTHOR]