Microwave-resonance-induced resistivity: evidence of ultrahot surface-state electrons on liquid 3He

Measurements of the dc resistivity of surface-state electrons on liquid helium exposed to microwave radiation are reported. It is shown that the resonant microwave excitation of surface-state electrons is accompanied by a strong increase in their resistivity, which is opposite to the result expected from the previously used two-level model. We show that even a very small fraction of electrons excited to the first excited state and decaying back due to vapor-atom scattering strongly heat the electron system, causing a population of higher subbands. The calculated resistivity change is in good agreement with the observed data.     

Synthesis of nickel nanoparticles supported on hollow samaria-doped ceria particles via the solution-spray plasma technique: Anode catalysts for SOFCs

Aiming at SOFC anode applications, we have synthesized nanometer-sized nickel catalysts supported on hollow spherical particles of samaria-doped ceria (Ni/SDC) by spraying a mixed solution of nickel, samarium, and cerium nitrates into an atmospheric pressure plasma. The as-prepared particles consisted of SDC (average diameter d_SDC = ca. 0.8 µm) and uniformly dispersed nanometer-sized NiO particles. When reduced in H₂ at 800 °C or 1000 °C, Ni nanoparticles (average diameter d_Ni = 34 nm) were found to be embedded uniformly into the SDC surface.     

Kinetic spectrophotometric determination of tetraphenylporphinecobalt(II) based on photochromism of immobilized norbornadiene

The cobalt(II) complex is detected spectrophotometrically by its catalysis of a photochromic isomerism of norbornadiene (NBD). NBD is immobilized on porous glass beads, and is isomerized to quadricyclane (QC) by UV irradiation. The beads are then immersed in a solution containing tetraphenylporphinecobalt(II) [TPPCo(II)], and the QC is converted back to NBD by a catalytic reaction with TPPCo(II). The rate constant, measured spectrophotometrically, is proportional to the concentration of TPPCo(II). The detection limit of TPPCo(II) is 60 μM for a reaction period of 1 h. This spectrophotometric detection can be applied repetitively without any supply of the chemical reagent, as NBD immobilized on the porous glass beads can be re-isomerized to QC by UV irradiation.     

Influence of extraction process on Cs isotope ratios for Fukushima Daiichi nuclear power plant accident-contaminated soil

Journal of Radioanalytical and Nuclear Chemistry - The influence of extraction process on Cs isotope ratios was investigated by thermal ionization mass spectrometry (TIMS) for nitric-acid (HNO3)...     

Atomic force microscopy study on the stability of a surface film formed on a graphite negative electrode at elevated temperatures

The stability at elevated temperatures of a solid electrolyte interphase (SEI) formed on a graphite negative electrode in lithium ion batteries was investigated by storage tests and in situ atomic force microscopy (AFM) observation. When the fully discharged graphite electrode was stored at elevated temperatures, the irreversible capacity in the following cycle increased remarkably. On the other hand, when the electrode was stored at the fully charged state at elevated temperatures, it was severely self-discharged during storage. AFM observation of the SEI layer formed on a model electrode of highly oriented pyrolytic graphite revealed two important facts on the stability of the SEI at elevated temperatures: (i) dissolution and agglomeration of the SEI layer at the discharged state and (ii) serious SEI growth at the charged state. These phenomena well explain the results of the charge and discharge tests. It was also shown that the addition of vinylene carbonate greatly improves the stability of the SEI at elevated temperatures, and gives good charge and discharge performance after storage.     

The Progress of the Gait Impairment and Brain Activation in a Patient with Post-stroke Hemidystonia

Objective: We explore the effects of body weight-supported (BWS) treadmill training, including the change of cortical activation, on a patient with post-stroke hemidystonia. Patient: The patient was a 71-year-old man with left thalamus hemorrhage. His motor symptoms indicated slight impairment. There was no overactive muscle contraction in the supine, sitting, or standing positions. During his gait, the right initial contact was the forefoot, and his right knee showed an extension thrust pattern. These symptoms suggested that he had post-stroke hemidystonia. Methods: The patient performed BWS treadmill training 14 times over 3 weeks. The effects of the BWS training were assessed by a step-length analysis, electromyography and functional magnetic resonance imaging (fMRI). Results: The patient''s nonparetic step length was extended significantly in the Inter-BWS (p<0.001) and Post-BWS (p=0.025) periods compared to the Pre-BWS session. The excessive muscle activity of the right gastrocnemius medialis in the swing phase was decreased at the Inter-BWS, Post-BWS, and follow-up compared to the Pre-BWS session. The peak timing difference of the bilateral tibialis anterior muscle became significant (p<0.05) on the first day of the intervention. The fMRI revealed that the cortical areas activated by the motor task converged through the intervention (p<0.05, family-wise error corrected). Conclusion: These results suggest that there was improvement of the patient''s symptoms of post-stroke hemidystonia due to changes in the brain activity during voluntary movement after BWS intervention. Body weight-supported treadmill training may thus be an effective treatment for patients with poststroke hemidystonia.     

Relationship between oxide-ion conductivity and dielectric relaxation in the Ln2Zr2O7 system having pyrochore-type compositions (Ln=Yb, Y, Gd, Eu, Sm, Nd, La)

Ln₂Zr₂O₇ (Ln=Yb, Y, Gd, Eu, Sm, Nd, La) system changed from fluorite (F)-type to pyrochlore (P)-type phases when the ionic radius ratios, r(Ln³⁺)/r(Zr⁴⁺), were larger than 1.26. The oxide-ion conductivity showed sharp maximum at the vicinity of the phase boundary between the F- and P-type phases. The frequency dependence of dielectric constant () and dielectric loss factor () were successfully explained by the superimposition of Debye-type polarization due to dopant-vacancy associate and electrode-electrolyte interfacial polarization by the numerical calculation. The peak of dielectric loss tangent (tan δ) was ascribed to the dopant-vacancy associate. The ε_r(0) and dielectric constant of the associate (ε_r0) showed also the maximum values at the vicinity of the phase boundary between the F- and P-type phases.     

Water‐Mediated Recognition of Simple Alkyl Chains by Heart‐Type Fatty‐Acid‐Binding Protein

Long‐chain fatty acids (FAs) with low water solubility require fatty‐acid‐binding proteins (FABPs) to transport them from cytoplasm to the mitochondria for energy production. However, the precise mechanism by which these proteins recognize the various lengths of simple alkyl chains of FAs with similar high affinity remains unknown. To address this question, we employed a newly developed calorimetric method for comprehensively evaluating the affinity of FAs, sub‐Angstrom X‐ray crystallography to accurately determine their 3D structure, and energy calculations of the coexisting water molecules using the computer program WaterMap. Our results clearly showed that the heart‐type FABP (FABP3) preferentially incorporates a U‐shaped FA of C10–C18 using a lipid‐compatible water cluster, and excludes longer FAs using a chain‐length‐limiting water cluster. These mechanisms could help us gain a general understanding of how proteins recognize diverse lipids with different chain lengths.     

How do H2 oxidation molecular catalysts assemble onto carbon nanotube electrodes? A crosstalk between electrochemical and multi-physical characterization techniques

Molecular catalysts show powerful catalytic efficiency and unsurpassed selectivity in many reactions of interest. As their implementation in electrocatalytic devices requires their immobilization onto a conductive support, controlling the grafting chemistry and its impact on their distribution at the surface of this support within the catalytic layer is key to enhancing and stabilizing the current they produce. This study focuses on molecular bioinspired nickel catalysts for hydrogen oxidation, bound to carbon nanotubes, a conductive support with high specific area. We couple advanced analysis by transmission electron microscopy (TEM), for direct imaging of the catalyst layer on individual nanotubes, and small angle neutron scattering (SANS), for indirect observation of structural features in a relevant aqueous medium. Low-dose TEM imaging shows a homogeneous, mobile coverage of catalysts, likely as a monolayer coating the nanotubes, while SANS unveils a regular nanostructure in the catalyst distribution on the surface with agglomerates that could be imaged by TEM upon aging. Together, electrochemistry, TEM and SANS analyses allowed drawing an unprecedented and intriguing picture with molecular catalysts evenly distributed at the nanoscale in two different populations required for optimal catalytic performance.

How do efficient hydrogen-oxidation molecular electrocatalysts connect onto their carbon nanotube conductive support? A coupled neutron scattering SANS and STEM electron microscopy study to observe soft active matter organizing on 3D nanosurfaces.