Magneto-resistance of NiFe nanowire with zigzag shape

The anisotropic magneto-resistance (AMR) contributions of a zigzag-shaped NiFe wire were investigated. The magneto-resistance (MR) behaviors in different magnetic-field directions clearly reflect the angular relationships between the directions of the current and magnetic moment in the subdivisions. The resistance in remanence after magnetization along 0° in respect to the longer direction of zigzag was larger than that along 90°. Assumed that the difference appears due to the AMR contribution in the domain wall trapped at the corner, the MR ratio was estimated to be 1.2%, which is in good agreement with the AMR of the NiFe film. We clearly showed that the domain-wall resistance originates in the AMR.     

Evaluation of bandgap energy and carrier density of InN nanocolumns

We have measured the optical properties of wurtzite InN nanocolumns and film by photoluminescence (PL) measurements at temperatures from 5 to 300 K and analyzed the PL spectra by fitting with the free-electron recombination bound (FERB) model. For the top-linked InN nanocolumns, we observed strong PL intensity compared to the InN film sample. The PL spectra were asymmetrical with low-energy tails and a red-shift of the PL peak energy position was observed with increasing temperature. However, for the separated InN nanocolumns, we observed weak PL intensity and symmetrical PL spectra. Analyzing the spectra shape of the top-linked InN nanocolumns at 5 K using the FERB model, we evaluated the intrinsic bandgap energy and carrier density of InN nanocolumns to be 0.69 eV and 2.5×10¹⁷ cm⁻³, respectively.     

H double-quantum filtered MR imaging of joints tissues: bound water specific imaging of tendons, ligaments and cartilage

The ¹H double-quantum filtered (DQF) NMR and DQF MRI is applied to the joint tissues of rabbits for selective visualization of tendons, menisci and articular cartilage. The ¹H DQF NMR selectively filters double-quantum coherence arising from the ¹H dipolar interaction of the “bound” water in these tissues. The double-quantum creation time dependency of the DQF signal intensity is determined by the molecular environment of the “bound” water. Therefore, each tissue has a unique creation time at which the DQF signal reaches its maximum intensity, τ_max (Achilles tendon: 0.46 ± 0.02 ms, patella: 0.55 ± 0.8 ms, anterior cruciate ligament: 0.60 ± 0.05 ms, meniscus: 0.78 ± 0.02 ms, skin: 0.81 ± 0.07 ms). We have presented the creation-time-contrasted DQF images of the meniscus, patella, foot, and knee joint. Compared with conventional T₂*-weighted gradient-echo (GRE) MR images, tendons, ligaments, menisci, and articular cartilage were more clearly seen in the DQF MR images. All these tissues were distinctly discriminated from each other by their creation times. DQF MR images of foot and knee joints can selectively demonstrated tendons, ligaments, and cartilage, which make it easier to understand the complicated anatomic structure of joints. Because the DQF NMR signal intensity and τ_max are sensitive to the order structure of the “bound” water, it might be possible to introduce the creation-time dependent-contrast of ¹H DQF MR images as a new tool for analyzing the changes in the ordered structure of the tissue.     

Electronic processes in NO dimerization on Ag and Cu clusters: DFT and MRMP2 studies

Experimentally observed NO dimerization on Cu and Ag surfaces is surprising because binding energy of NO dimer is very small in gas phase. MRMP2, MP2 to MP4, CCSD(T), and DFT studies of NO dimerization on Ag₂ and Cu₂ clusters disclosed that the CCSD(T) method could be applied to this reaction on Ag₂ and Cu₂ unlike NO dimerization in gas phase which exhibits significantly large nondynamical electron correlation effect. Charge-transfer (CT) from Ag₂ and Cu₂ to NO moieties plays important role in N N bond formation between two NO molecules. This CT considerably decreases nondynamical correlation effect. Also, the DFT method could be applied to this NO dimerization, if appropriate DFT functional is used; all pure functionals examined here and most of the hybrid functionals underestimated the activation barrier (E_a), while only ωB97X provided E_a similar to CCSD(T)-calculated value. NO dimerization on similar Cu₂ and Cu₅ needs moderately larger E_a than those on Ag₂ and Ag₅, because frontier orbital participating in the CT exists at lower energy in Cu₂ and Cu₅ than in Ag₂ and Ag₅. The E_a decreases in the order Ag₂ >> Ag₃₈ > Ag₇ ∼ Ag₅ and the reaction energy (ΔE) is positive (endothermic) in Ag₂ but significantly negative in Ag₃₈, Ag₇, and Ag₅, indicating that various Ag clusters could be effective for NO dimerization except for Ag₂. The decreasing order of E_a and increasing order of exothermicity are attributed to increasing order of the frontier orbital energy of Ag₂ < Ag₃₈ < Ag₇ ∼ Ag₅. © 2018 Wiley Periodicals, Inc.     

Size-Exclusion Effect and Protein Repellency of Concentrated Polymer Brushes Prepared by Surface-Initiated Living Radical Polymerization

The adsorption of proteins on poly(2-hydroxyethyl methacrylate) (PHEMA) brushes was systematically investigated from the viewpoint of the size-exclusion effect of the concentrated brushes. By use of surface-initiated atom transfer radical polymerization, well-defined, concentrated PHEMA brushes were successfully grafted on the inner surface of the silica monolithic column with meso pores of ca. 80 nm as well as a silicon wafer and a quartz crystal microbalance (QCM) chip. By eluting low-polydispersity pullulans with different molecular weight through the modified monolithic column, the concentrated PHEMA brush was characterized and demonstrated to sharply exclude solute molecules with the critical molecular size (size-exclusion limit) comparable to the distance between the nearest-neighboring graft points d. The elution behaviors of proteins with different sizes were studied with this PHEMA-grafted column: the protein sufficiently larger than the critical size was perfectly excluded from the brush layer and separated only in the size-exclusion mode by the meso pores without affinity interaction with the brush surface. Then, the irreversible adsorption of proteins on PHEMA brushes was investigated using QCM by varying graft densities (σ = 0.007, 0.06, and 0.7 chains/nm²) and protein sizes (effective diameter = 2–13 nm). A good correlation between the protein size and the graft density was observed: proteins larger than d caused no significant irreversible adsorption on the PHEMA brushes. Thus, we experimentally substantiated the postulated size-exclusion effect of the concentrated brushes and confirmed that this effect plays an important role for suppressing protein adsorption.     

Observation of intermediate bands feeding the positive-parity yrast band in 155Gd

High-spin states of ¹⁵⁵Gd were populated by using the ¹⁵⁴Sm(α,3nγ)¹⁵⁵Gd reaction at E _α= 33 MeV. γ-γ coincidence, E _γ singles, excitation function, and the DCO ratios were measured. we have identified three intermediate bands with ΔI= 2 feeding the positive yrast band. The bands are interpreted as such candidate bands that are mixed with the negative-parity ground state band. This observation can provide a plausible explanation for unusually large population of the positive-parity yrast band observed in a recent Coulomb excitation. Received: 2 November 1999     

Most stable metallic phase of the mixed-valence MMX-chain, Pt2(dtp)4I (dtp = C2H5CS2-), in purely d-electronic conductors based on the transition-metal complex

The electrical resistivity and X-ray oscillation photograph measurements for an MMX-chain complex, Pt2(dtp)4I (dtp = C2H5CS2-), under high pressure were performed. We observed the most stable metallic phase (TMI = 70 K, under 2.2 GPa) in the 1-D purely d-electronic conductors and pressure-induced metal-insulator transition including the structural phase transition at 3.0 GPa.     

First enantioselective synthesis of (-)- and (+)-virgatusin, tetra-substituted tetrahydrofuran lignan

The first highly enantioselective syntheses of tetra-substituted tetrahydrofuran lignan, (-)- and (+)-virgatusin, were achieved. Hemiacetal was stereoselectively obtained from Evans's syn-aldol product as a single isomer. This hemiacetal was converted to (-)-virgatusin via hydrogenolysis. (+)-Virgatusin was also synthesized through the same process. The enantiomeric excess of the both enantiomers was determined as more than 99% ee.