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Aim: Measurement of B-type natriuretic peptide (BNP) is widely used as a diagnostic and risk assessment tool for cardiovascular disease. Recent studies have demonstrated that BNP-32 and its precursor proBNP circulate in the blood stream, and that most commercial BNP immunoassays measure both forms. However, recombinant or synthetic BNP-32 is used as the standard for those BNP immunoassays. This gap between clinical samples and the standard might be a potential source of variation in BNP measurements among assays. The purpose of this study is to validate a more suitable calibrator for BNP immunoassays. Methods: External BNP calibrators containing both BNP-32 and glycosylated proBNP were prepared at two concentration levels. Target BNP concentrations of the low and high levels were 40 and 160 pg/mL, respectively. And to reflect clinical samples, the molar ratios of BNP-32 to glycosylated proBNP in these concentration levels were adjusted to 50:50 and 25:75, respectively. BNP concentrations of plasma samples along with the external BNP calibrators were measured at two commercial labs and using an automated analyzer MI02 Shionogi® BNP (MI02). These samples and the calibrators were also measured using an immunoradiometric assay (IRMA) as a standard assay procedure. Concentrations of the plasma samples measured at the labs or using the MI02 were adjusted according to a comparison of the measured concentrations of the external BNP calibrators with the IRMA. Results: After measured concentrations of the plasma samples were adjusted using the external BNP calibrators, the correlation between each measurement and the IRMA was improved. The range of the slopes according to Passing-Bablok regression analysis narrowed from 0.628 - 0.955 to 0.911 - 1.005. Conclusions: Our data suggests that a mixture of BNP-32 and glycosylated proBNP at different ratios by concentration level is suitable for calibration to minimize variations in BNP measurements among immunoassays.

Our previous research showed that aliphatic amines were put in order of high reactivity as “ethylamine > ammonia > t-butylamine > diethylamine” on the aromatic nucleophilic substitution of 1-dimetylamino-2,4-bis(trifluoroacetyl)-naphthalene 1 in acetonitrile. The DFT calculation study (B3LYP/6-31G* with solvation model) for the reactions of 1 with above four amines rationally explained the difference of each amines reactivity based on the energies of their Meisenheimer complexes 3 which are assumed to formed as the reaction intermediates in the course of the reaction giving the corresponding N-N exchange products 2. Intramolecular hydrogen bond between amino proton in 1-amino group and carbonyl oxygen in 2-trifluoroacetyl group stabilizes Meisenheimer complexes 3 effectively, and accelerates the substitution reaction from 1 to 2. Our calculation results also predicted that the above order of amines is also true if less polar toluene is used as a solvent instead of acetonitrile even though more enhanced conditions are required.

We study spin states of edge modified nanographene molecules with rectangular and triangular shapes by first principle calculations using density functional theory (DFT) and Hartree–Fock (HF) methods with Moller–Plesset (MP) correlation energy correction at different levels. Anthracene (C 14 H 10 ) and phenalenyl (C 13 H 9 ), which contain three benzene rings combined in two different ways, can be considered as fragments of a graphene sheet. Carbon-based ferromagnetic materials are of great interest both in fundamental science and technological potential in organic spintronics devices. We show that non-magnetic rectangular molecules such as C 14 H 10 can become ferromagnetic with high-spin state as the ground state by dihydrogenization of one of the zigzag edges, while triangular molecules such as C 13 H 9 become ferromagnetic with high-spin state by dehydrogenization of one of the zigzag edges.

] which keeping bare (radical) carbons on one side zigzag edge, whereas mono hydrogenated carbons on another side. Optimizing atomic configuration, self-consistent calculation demonstrated that a total energy of the highest spin state is more stable than that of the lower one, which origin comes from the exchange coupling between carbons. This analysis suggested a capability of designing magnetic data track utilizing such asymmetric graphene ribbon. In order to increase areal magnetization density, bi-layer and quadric layer model were analyzed. Detailed calculation resulted that also the highest spin state is the most stable one. Increasing layer numbers is an effective way to enhance strong magnetism.

The multiple spin states of zigzag edge modified graphene molecules were analyzed to study the possibility of carbon based magnetic materials by using first principles density functional theory to select suitable elements for modification. Radical carbon modified C64H17 and dihydrogenated carbon C64H27 demonstrated that the highest spin state is most stable, which arises from the tetrahedral molecular orbital configuration in two up-spins at the zigzag edge. In contrast, oxygen modified C59O5H17 exhibited the lowest spin state to be most stable due to the cancellation of four spins at the oxygen site. Boron modified C59B5H22 had no π-orbit at the boron site, which meant the lowest spin state was most stable, whereas, C59N5H22 had two π-electrons, where spins cancelled each other out to yield the lowest stable spin state. Silicon modified C59Si5H27 and phosphorous modified C59P5H22 had a curved molecular geometry due to large atom insertion at the zigzag site, which also brought about a complex spin distribution. Radical carbon and dihydrogenated carbon modification were identified as promising candidates for designing carbon based magnetic materials.

We propose analysis of multiple spin states in radical carbon zigzag edge graphene-like molecules. Calculations based on density function theory (DFT) revealed that the highest spin state was most stable in every radical carbon edge asymmetric molecule. A typical C64H17 molecule has five unpaired electrons, which creates three possible molecular spin states of Sz=1/2, 3/2, and 5/2. The Sz=5/2 state was the most stable among these states. Such DFT results coincided with a simple magnetic counting rule to give a localized spin of Sz=+2/2 to one radical carbon site, whereas it gave Sz=-1/2 at the nearest carbon and +1/2 at the second nearest. A total molecular spin of Sz was obtained by using the simple sum of those numbers. Radical carbon zigzag edge nano-graphene is a promising candidate for designing new materials with strong magnetism. In addition, we studied oxygen-substituted zigzag edges occupied by four electrons. These four spins canceled each other out in two tetrahedral orbits, which led to weak molecular magnetism.

Several experiments have recently found room-temperature ferromagnetism in graphite-like carbon based materials. This paper offers a model explaining such ferromagnetism by using an asymmetric nano-graphene. Our first typical model is C48H24 graphene molecule, which has three dihydrogenated (-CH2) zigzag edges. There are several multiple spin states competing for stable minimum energy in the same atomic topology. Both molecular orbital and density function theory methods indicate that the quartet state(S=3/2) is more stable than that of doublet (S=1/2), which means that larger saturation magnetization will be achieved. We also enhanced this molecule to an infinite length ribbon having many (-CH2) edges. Similar results were obtained where the highest spin state was more stable than lower spin state. In contrast, a nitrogen substituted (-NH) molecule C45N3H21 demonstrated opposite results. that is, the lowest spin state(S=1/2) is more stable than that of highest one(S=3/2), which arises from the slight change in atom position., 6 pages, 7 figures

Using ab initio calculations, we find high stability of octahedral Mo6S8 clusters, which can further be condensed to form Mo3nS3n+2 (n, an integer) nanowires. These linear structures are energetically more favorable compared with other closed-packed polyhedral isomers of Mo-S clusters. The octahedral units in nanowires are stabilized by strong Mo-Mo interactions and p-d hybridization between Mo 4d and S 2p orbitals. There is a free electron-like band that crosses the Fermi energy in infinite nanowires and leads to their metallic character. Iodine doping acts as electron donor and can be used to tailor the electronic conductivity. For Mo12S8I4 nanowires, both electrons and holes are found to contribute to conduction. These nanowires are energetically more favorable than the experimentally obtained Mo12S6I12 nanowires.

Using first-principles calculations with ultrasoft pseudopotential formalism and the generalized gradient approximation for the exchange-correlation functional, we study the stability of MonSm (n =1-6 and m ranging from n to 3n) clusters and obtain the optimal stoichiometry for each n corresponding to the magic cluster. It is found that in this size range, the lowest-energy structures favor a core of metal atoms, which is covered by sulfur. In particular, we observe that for Mo6S14 isolated clusters, a 3D structure is significantly lower in energy as compared to platelet structures found recently on Au (111) surface. The composition ratio between S and Mo in the magic clusters is less than 2 for n=3 and greater than 2 for n

Using first principles calculations within the generalized gradient approximation, the structural stability of compound Mo-S clusters at subnanometer level is discussed based on results obtained for various Mo5Sn isomers with n ¼ 5{15. The symmetrical Mo-S bonds generally lead to higher stability, while the formation of S-S bond and the observation of magnetism in these clusters lower the structural stability. Mo5Sn isomers with n ¼ 6, 8, and 11 are found to be most stable. The addition of sulfur atoms is quite favorable in the edge capped square pyramid and face capped trigonal bipyramid isomers. [doi:10.2320/matertrans.48.658]

Current-driven magnetic domain wall (DW) motion has been extensively studied not only theoretically, but also experimentally. The DW motion is induced by spin-transfer torque, that is, the transfer of spin angular momentum from conduction electrons to localized electrons. The velocity of DW motion is proportional to the spin polarization [P a = (σ ↑ − σ ↓ )/(σ ↑ + σ ↓ )] of electrical conductivity (σ) and its direction is the same as electron current when P σ > 0. The reverse DW motion is thus expected in ferromagnetic materials with negative spin polarization (P σ σ material and a negative P σ material, are of fundamental interest. We have paid a lot of attention to ferromagnetic Fe 4 N epitaxial films for application to spintronics devices because it is theoretically expected to have a large negative spin polarization (P σ = −1.0).2 Very recently, we confirmed its negative spin polarization by experiment.3,4

Atomic structures of Mo n O 2 n , n = 1–6 clusters are studied using first principles calculations and are compared with those obtained for Mo n S 2 n clusters. The lowest energy isomers of Mo n O 2 n differ significantly from those of Mo n S 2 n for n > 3. Oxygen atoms favor to bind with two Mo atoms, while S atoms are bonded with three Mo atoms. However, the clustering of Mo atoms is generally favored xin both cases due to the partially occupied d-orbitals. The lowest energy isomers of Mo n O 2 n have larger HOMO–LUMO gaps than the values for Mo n S 2 n clusters and for n = 1 and 4 the clusters are magnetic.

We have fabricated a new layered structure, named "U-mag," for perpendicular magnetic recording media, in terms of stacked films including a very thin (2 nm) ferromagnetic (Co) intermediate layer and lattice spacing control layers. The formed medium having a 100-nm soft magnetic underlayer with high coercivity over 6 kOe and sufficient nucleation field (-1.5 kOe) shows higher signal-to-noise ratio (SNR) than a medium with a conventional Ru underlayer. The detailed microstructures of the U-mag medium were also revealed by a transmission electron microscope with an energy dispersive spectrometer. A double Co intermediate layer gave a significant improvement in the SNR compared to a single Co layer.

The present study examined the effect of melatonin on prostaglandin E2-induced pro-inflammatory cytokine production in human gingival fibroblasts. Human gingival fibroblasts were cultured in melatonin in the presence/absence of prostaglandin E2 for 1h. The levels of mRNA for IL-1β, IL-8 and osteoprotegerin/osteoclastogenesis inhibitory factor were quantitatively evaluated by reverse transcriptase-PCR using a LightCycler method. While melatonin did not significantly alter the levels of osteoprotegerin/osteoclastogenesis inhibitory factor mRNA, either in the presence or absence of prostaglandin E2, it markedly decreased the levels of prostaglandin E2-stimulated IL-1β and IL-8 mRNA. These results suggest that melatonin has the potency to reduce the production of pro-inflammatory cytokines from prostaglandin E2-activated human gingival fibroblasts in the inflamed periodontal tissues and may act as a new potent drug for the treatment for periodontal disease.

Thermally assisted or hybrid magnetic recording system is expected to be a data storage device with high areal density beyond 1 Tb/in2. Several features of the hybrid recording are treated, such as high resolution recording capability by sharp thermal gradient, and pico-second order high-speed magnetization reversal. Since the hybrid recording solves the head field limit problem, the high magnetic anisotropy (Ku) materials with order of 107 erg/cm3 are used for the hybrid recording media. We discuss the candidates of the high Ku materials, FePt and CoPt L10 ordered alloy, Tb-Fe-Co amorphous, and Co/Pd multilayer thin films.

With consideration to the Curie-Weiss law, we investigate magnetization reversal beyond the Curie temperature, from theoretical to experimental. This paper outlines a theoretical model in accordance with the Curie-Weiss law and also presents a new criterion for the shape stability of recorded domains using magneto-optical recording or hybrid recording. Fairly good agreement was obtained between the theoretical and experimental investigations.

This study examined the modulating effect of PGE2 on LPS-induced IL-8 production by human gingival fibroblasts in vitro. The expression of IL-8 mRNA, after stimulation with PGE2, was determined by RT-PCR. IL-8 production by HGFs was shown to be related to the time of incubation and the dose of LPS. A slight increase in IL-8 levels was observed when cells were exposed to PGE2 alone compared to controls. When HGFs were pre-stimulated with PGE2 and then exposed to LPS, IL-8 production was increased 2-3 fold compared to non-treated cells. Herbimycin A completely abolished the secretion of IL-8. These results indicate that PGE2 can modulate cytokine secretion from HGFs and increase IL-8 production from cells exposed to LPS. IL-8 production induced by LPS was dependent on the tyrosine phosphorylation pathway.