Rationalizing In Situ Active Repair in Hydrogen Evolution Photocatalysis via Non-Invasive Raman Spectroscopy.

Currently, most photosensitizers and catalysts used in the field of artificial photosynthesis are still based on rare earth metals and should thus be utilized as efficiently and economically as possible. While repair of an inactivated catalyst is a potential mitigation strategy, this remains a challenge. State-of-the-art methods are crucial for characterizing reaction products during photocatalysis and repair, and are currently based on invasive analysis techniques limiting real-time access to the involved mechanisms.

Global scale analysis on the extent of river channel belts.

Rivers form channel belts that encompass the area of the river channel and its associated levees, bars, splays and overbank landforms. The channel belt is critical for understanding the physical river evolution through time, predicting river behavior and management of freshwater resources. To date, there is no global-scale, quantitative study of the extent of river channel belts.

A large octupole magnetic trap for research with atomic hydrogen.

We describe the design and performance of a large magnetic trap for storage and cooling of atomic hydrogen (H). The trap operates in the vacuum space of a dilution refrigerator at a temperature of 1.5 K.

Purely Spatial Quantum Diffusion of H Atoms in Solid H_{2} at Temperatures below 1 K.

We report on a direct measurement of the quantum diffusion of H atoms in solid molecular hydrogen films at T=0.7  K. We obtained a rate of pure spatial diffusion of H atoms in the H_{2} films, D^{d}=5(2)×10^{-17}  cm^{2} s^{-1}, which was 2 orders of magnitude faster than that obtained from H atom recombination, the quantity used in all previous work to characterize the mobility of H atoms in solid H_{2}.

Experimental cell with a Fabry-Pérot resonator tuned in situ for magnetic resonance studies of matrix-isolated radicals at temperatures below 1 K.

We describe the design and construction of an experimental cell for the study of free radicals in macroscopically thick films of solidified molecular and rare gases by 128 GHz Electron Spin Resonance (ESR) at temperatures below 1 K. The ESR resonator has an open Fabry-Pérot design, and its frequency can be tuned in situ by adjusting the spacing between the mirrors. The tuning mechanism consists of a piezo positioner and a stainless-steel edge-welded bellows, which can change the resonator frequency by at least 6 GHz.

Dynamic nuclear polarization and ESR hole burning in As doped silicon.

We present an experimental study of the Dynamic Nuclear Polarization (DNP) of Si nuclei in silicon crystals of natural abundance doped with As in the temperature range 0.1-1 K and in a strong magnetic field of 4.6 T.

Complexes of Glycolic Acid with Nitrogen Isolated in Argon Matrices. I. Structures and Thermal Effects.

Molecular complexes between glycolic acid and nitrogen were studied in a low-temperature argon matrix with FTIR spectroscopy, and supported by MP2 and BLYPD3 calculations. The calculations indicate 11 and 10 stable complex structures at the MP2 and BLYPD3 levels of theories, respectively. However, only one hydrogen-bonded complex structure involving the most stable SSC conformer of glycolic acid was found experimentally, where the nitrogen molecule is bound with the carboxylic OH group of the SSC conformer.

Complexes of Glycolic Acid with Nitrogen Isolated in Argon Matrices. II. Vibrational Overtone Excitations.

Structural changes of glycolic acid (GA) complex with nitrogen induced by selective overtone excitation of the νOH mode were followed in argon matrices using FTIR spectroscopy. For the most stable SSC1 complex present in different trapping sites directly upon deposition site, selective changes in the νOH region were achieved upon near-infrared irradiation. Simultaneously, new conformers of the GA…N complex were formed, giving rise to several sets of bands in the νOH and νC=O regions of the spectra.

Formation of Nuclear-Polarized Phases of H Atoms Embedded in Solid H_{2} Films.

We report on an experimental observation of two phases of hydrogen atoms in solid H_{2} films at temperatures of 0.1-0.8 K, characterized by a large enhancement of the nuclear spin polarization compared to that given by Boltzmann statistics (p=0.

Finnish NGOs promoting health equity in the context of welfare economy.

Health inequality is a national challenge in Finland. The WHO global strategy of Health for All implies that all people should have an equal opportunity to develop and maintain their health through fair and just access to health resources. This article examines the role of Finnish Non-Governmental Organizations (NGO) in strengthening the health equity.

ESR study of atomic hydrogen and tritium in solid T and T:H matrices below 1 K.

We report on the first ESR study of atomic hydrogen and tritium stabilized in solid T and T:H matrices down to 70 mK. The concentrations of T atoms in pure T approached 2 × 10 cm (0.60%) and record-high concentrations of H atoms ∼1 × 10 cm (0.

Tunneling chemical exchange reaction D + HD → D + H in solid HD and D at temperatures below 1 K.

We report on a study of the exchange tunneling reaction D + HD → D + H in a pure solid HD matrix and in a D matrix with a 0.23% HD admixture at temperatures between 130 mK and 1.5 K.

Bose-Einstein condensation of magnons in atomic hydrogen gas.

We report on experimental observation of Bose-Einstein condensation (BEC)-like behavior of quantized electron spin waves (magnons) in a dense gas of spin-polarized atomic hydrogen. The magnons are trapped and controlled with inhomogeneous magnetic fields and described by a Schrödinger-like wave equation, in analogy to the BEC experiments with neutral atoms. We have observed the appearance of a sharp feature in the ESR spectrum displaced from the normal spin wave spectrum.

Dynamic nuclear polarization of high-density atomic hydrogen in solid mixtures of molecular hydrogen isotopes.

We report on magnetic resonance studies of high-density atomic hydrogen and deuterium in solid hydrogen matrices at temperatures below 1 K. Average concentrations of H atoms ≈3×10(19)  cm(-3) are obtained in chemical tunneling reactions of isotope exchange with D atoms. The products of these reactions are closely located pairs of H atoms near D2 molecules with strong exchange interactions.

Experimental cell for molecular beam deposition and magnetic resonance studies of matrix isolated radicals at temperatures below 1 K.

We present the design and performance of an experimental cell constructed for matrix isolation studies of H and D atoms in solid H2/D2 films, which are created by molecular beam deposition at temperatures below 1 K. The sample cell allows sensitive weighing of the films by a quartz microbalance (QM) and their studies by magnetic resonance techniques in a strong magnetic field of 4.6 T.

Potential endocrine disrupting effect of ochratoxin A on human placental 3β-hydroxysteroid dehydrogenase/isomerase in JEG-3 cells at levels relevant to human exposure.

Ochratoxin A (OTA) is a common foodborne mycotoxin. Besides its classical toxicities, it is also associated with the impairment of steroidogenesis in rats. It is hypothesized that OTA may act as an endocrine disruptor by intervening 3β-hydroxysteroid dehydrogenase/isomerase (3β-HSD).

Visible light-driven chemistry of oxalic acid in solid argon, probed by Raman spectroscopy.

High-overtone induced chemistry of oxalic acid (OA) isolated in a low-temperature argon matrix was investigated using Raman spectroscopy. The Raman spectra of three conformers of OA are presented and discussed. Upon excitation of high overtone combination bands by 532 nm irradiation of the lowest energy cTc structure, the isomerization and unimolecular decomposition of OA were observed.

Guiding and trapping of electron spin waves in atomic hydrogen gas.

We present a high magnetic field study of electron spin waves in atomic hydrogen gas compressed to high densities of ∼10(18)  cm(-3) at temperatures ranging from 0.26 to 0.6 K.

Electronic spectroscopy of I(2)-Xe complexes in solid Krypton.

In the present work, we have studied ion-pair states of matrix-isolated I(2) with vacuum-UV absorption and UV-vis-NIR emission, where the matrix environment is systematically changed by mixing Kr with Xe, from pure Kr to a more polarizable Xe host. Particular emphasis is put on low doping levels of Xe that yield a binary complex I(2)-Xe, as verified by coherent anti-Stokes Raman scattering (CARS) measurements. Associated with interaction of I(2) with Xe we can observe strong new absorption in vacuum-UV, redshifted 2400 cm(-1) from the X → D transition of I(2).

Hepatocytes: the powerhouse of biotransformation.

Liver is the most important organ involved in biotransformation of xenobiotics. Within the main organisational unit, the hepatocyte, is an assembly of enzymes commonly classified as phase I and phase II enzymes. The phase I enzymes principally cytochrome P450 catalyse both oxidative and reductive reactions of a bewildering number of xenobiotics.

Photolysis of HCOOH monomer and dimer in solid argon: Raman characterization of in situ formed molecular complexes.

Raman spectroscopy combined with the matrix isolation technique was employed to study the 193-nm photodecomposition products of formic acid in an argon matrix. The Raman-active fundamentals belonging to the CO(2) + H(2) and CO + H(2)O photoproducts were assigned. Also, bands due to Fermi resonance between the stretching vibration (nu(1)) and the overtone of the bending mode (2nu(2)) of CO(2) were identified.

Rapid screening of commercially available herbal products for the inhibition of major human hepatic cytochrome P450 enzymes using the N-in-one cocktail.

Self-administration of complementary products concurrently with conventional medication is increasingly common. The potential for cytochrome P450 (CYP) inhibition requires investigation. The N-in-one assay with ten probe substrates for nine CYPs was used with human liver microsomes to investigate ten products.

Clock shift in high field magnetic resonance of atomic hydrogen.

We have measured electron spin resonance line shifts due to collisions in atomic hydrogen gas compressed to densities approximately 10(18) cm(-3) in a strong magnetic field (4.6 T). The shift in a doubly polarized gas is negligible, in contrast with a mixture of two hyperfine states.

Investigating isomerization reactions in solid state by using simultaneous high overtone pumping and Raman detection.

Formation of the unstable cis-formic acid in solid argon matrix is induced by direct excitation of the 6<--0 transition of the nu(OH) vibration of the trans-formic acid. The experiment utilizes strongly focused laser beam that produces relatively high isomerization rate despite the low cross section of the absorption. Raman spectroscopy in a backscattering geometry is used for detection of the reactants and the products.

Cold collision frequency shift in two-dimensional atomic hydrogen.

We report a measurement of the cold collision frequency shift in atomic hydrogen gas adsorbed on the surface of superfluid (4)He at T approximately < 90 mK. Using two-photon electron and nuclear magnetic resonance in 4.6 T field we separate the resonance line shifts due to the dipolar and exchange interactions, both proportional to surface density sigma.