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Pulp capping, or placing dental materials directly onto the vital pulp tissues of affected teeth, is a dental procedure that aims to regenerate reparative dentin. Several pulp capping materials are clinically being used, and calcium ion (Ca(2+)) released from these materials is known to mediate reparative dentin formation. ORAI1 is an essential pore subunit of store-operated Ca(2+) entry (SOCE), which is a major Ca(2+) influx pathway in most nonexcitable cells. Here, we evaluated the role of ORAI1 in mediating the odontogenic differentiation and mineralization of dental pulp stem cells (DPSCs). During the odontogenic differentiation of DPSCs, the expression of ORAI1 increased in a time-dependent manner. DPSCs knocked down with ORAI1 shRNA (DPSC/ORAI1sh) or overexpressed with dominant negative mutant ORAI1(E106Q) (DPSC/E106Q) exhibited the inhibition of Ca(2+) influx and suppression of odontogenic differentiation and mineralization as demonstrated by alkaline phosphatase (ALP) activity/staining as well as alizarin red S staining when compared with DPSCs of their respective control groups (DPSC/CTLsh and DPSC/CTL). The gene expression for odontogenic differentiation markers such as osteocalcin, bone sialoprotein, and dentin matrix protein 1 (DMP1) was also suppressed. When DPSC/CTL or DPSC/E106Q cells were subcutaneously transplanted into nude mice, DPSC/CTL cells induced mineralized tissue formation with significant increases in ALP and DMP1 staining in vivo, whereas DPSC/E106Q cells did not. Collectively, our data showed that ORAI1 plays critical roles in the odontogenic differentiation and mineralization of DPSCs by regulating Ca(2+) influx and that ORAI1 may be a therapeutic target to enhance reparative dentin formation.

The effect of field annealing on the magnetic tunnel junctions (MTJs) with an artificial antiferromagnetic layer is investigated. Samples, which were grown under the same condition, are annealed with low (200-Oe) and high (1-kOe) magnetic fields. The rotation of the pinned direction is observed for the sample annealed at high magnetic field without decrease of tunneling magnetoresistance by varying the applied field direction. This result provides a method to adjust the pinned direction of the MTJ, which may be critical in switching a magnetic RAM (MRAM) cell. Index Terms--Artificial anitferromagnetic (AAF) layer, field annealing, magnetic tunnel junction (MTJ), tunneling magnetoresistance (TMR).

A study is conducted on the transition of the anisotropic magnetoresistance of dc magnetron-sputtered Ni80Fe20 permalloy films from negative magnetoresistance to positive magnetoresistance (PMR) with increasing thickness. It is shown that the PMR in the transverse measurement is associated with the canted hysteresis loop peculiar to the stripe domains caused by the perpendicular anisotropy.

From measurements of the current-perpendicular-to-plane magnetoresistance of magnetic multilayers and exchange-biased spin-valves combining the ferromagnetic (F) alloys Co50Fe50 and Co70Fe30 with the nonmagnetic metal Cu, we extract values of the bulk scattering asymmetry, βF, the spin-diffusion length, lsfF, the interface scattering asymmetry, γF/Cu, and twice the enhanced specific resistance, 2ARF/Cu*. The parameters of the two alloys lie within mutual uncertainties of each other. The values of βF∼0.88 are unusually large, those of lsfF∼10 nm are moderate and consistent with values for other F-alloys, and those of 2ARF/Cu*∼0.6 fΩ m2 and γF/Cu∼0.6 are both less than those for Co/Cu. We do not need to include any spin-flipping at the F/Cu interfaces to fit our data. [ABSTRACT FROM AUTHOR]

We fabricated spin light emitting diodes using oxide tunneling barriers between ferromagnetic materials (Ni0.8Fe0.2/Co0.9Fe0.1) and semiconductors (GaAs) and investigated the temperature-dependent carrier lifetime and spin relaxation time of the active GaAs layer. We observed the circular polarization of the free exciton from the electroluminescence spectra due to the spin injection from the ferromagnetic material, whereas the circular polarization of the conduction band to acceptor transition was negligible. From the temperature-dependent carrier lifetime and spin relaxation time of the active GaAs layer, we found that the spin injection efficiency was larger than 25% between 20 and 180 K, where the magnetic field dependence of the spin lifetime was ignored. [ABSTRACT FROM AUTHOR]

Ferromagnetic layer thickness dependence of anisotropic magnetoresistivities in Ta/NiFe(t)/IrMn (10 nm)/Ta has been investigated for t=3, 4, 5, 7, 8, 10, 12, 15, and 20 nm by the method of anisotropic magnetoresistance and planar Hall effect. Our results revealed that the parallel and perpendicular resistivity components performed a varying function with increment in NiFe thickness. Both the resistivities at first were observed to increase when the NiFe thickness increases from 3 to 10 nm; then for the NiFe thicknesses from 10 to 20 nm, the resistivities of NiFe layer decrease as the NiFe thickness increases. However, the anisotropic resistivity change, which is the difference between parallel and perpendicular resistivities, was observed to increase for the whole range of thicknesses when the NiFe thickness increases. The measured quantities were found to be in good agreement with the theoretically estimated parameters using single domain model; thus these behaviors are well explained based on the modern electron theory transition metals. [ABSTRACT FROM AUTHOR]

A magnetization switching method for magnetic random access memory (MRAM), recently proposed by Savtchenko et al. [U.S. Patent No. 6,545,906 (2003)], is known to have an important advantage of a wide window for bit writing over the conventional method based on the asteroid curve, but it has a serious problem of high switching fields. In an effort to solve this problem, the effects of the thickness asymmetry and antiferromagnetic exchange coupling of the synthetic antiferromagnetic free-layer structure on the switching field have been investigated by micromagnetic computer simulation. At conditions relevant to high-density MRAM, magnetization switching in the direct write mode occurs at reasonably low values of word- and bit-line fields (below 100 Oe), combined with a substantially wide window for bit writing. A much wider window is observed in the toggle mode, but the required switching fields are too high, being over 150 Oe. [ABSTRACT FROM AUTHOR]

Magnetic tunnel junction (MTJ) structures were investigated by x-ray photoelectron spectroscopy. The Al layer was overoxidized and the samples were treated by rapid thermal annealing. It was found that the Mn atoms in the exchange-bias layer diffused into the magnetic layer, but did not reach the oxide barrier. Although slightly higher oxygen concentration was observed at the interface between the magnetic layer and the oxide barrier, strong evidence of the oxidized magnetic-layer interface was not found. Our result is consistent with the high tunneling magnetoresistance of MTJs at room temperature. [ABSTRACT FROM AUTHOR]

Top synthetic spin valves with structure Ta/NiFe/CoFe/Cu/CoFe(P1)/Ru/CoFe(P2)/FeMn/Ta on Si (100) substrate with natural oxide were prepared by dc magnetron sputtering system. We have changed only the thickness of the free layer and the thickness difference (P1-P2) in the two ferromagnetic layers separated by Ru, and investigated the effect of magnetic film thickness on the interlayer coupling field in a spin valve with a synthetic antiferromagnet. As the free layer thickness decreased from 70 to 20 Å, the interlayer coupling field was increased due to the magnetostatic coupling (orange peel coupling). In the case of the thickness difference in the pinned layers, the interlayer coupling field agreed with the modified Néel model suggested in the top synthetic spin valve structures. However, in the case of t[sub P1]=t[sub P2], and t[sub P1]=t[sub P2]+5 Å, it was found that the interlayer coupling field could not be explained by the modified Néel ! model. The deviation of the modified Néel model at the dip zone could be due to the large canting of the pinned layers, which depend on applied field and different thickness in synthetic antiferromagnetic structure. The dependence of Cu thickness on the interlayer coupling field was investigated and 10 Oe of the interlayer coupling field was obtained when the Cu thickness is 32 Å. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The effects of an rf substrate bias on the structural and magnetic properties of the CoCrPt/[Cr.sub.75][Ti.sub.25]/CoTi trilayer type longitudinal recording media deposited on glass substrate have been studied. It was found that the coercivity of 30 nm thick CoCrPt films deposited on [Cr.sub.75][Ti.sub.25]/CoTi underlayer was 4000 Oe by a substrate bias of 100 W rf, which is 800 Oe increase than the non-biased case. X-ray diffraction indicated that the rf-bias to substrate improved the Co (1010) and (1120) plane textures of the CoCrPt magnetic layer. From RBS analyses, Pt content of the CoCrPt magnetic layer increased with rf-bias power. In addition to the Pt increase, a better lattice matching between the CoCrPt magnetic layer and the [Cr.sub.75][Ti.sub.25]/CoTi underlayer was obtained through the expansion of the lattice parameter, 'a' and 'c' of Co in the CoCrPt with the substrate bias. These two factors are thought to be the origin of the coercivity increase. Index Terms--CoCrPt, [Cr.sub.75][Ti.sub.25]/CoTi underlayer, crystallographic texture, substrate bias

Magnetic and recording characteristics of CoCrPt thin film media deposited on [Cr.sub.75][Ti.sub.25]/CoTi double underlayers were investigated and compared to those on bare CoTi or Cr underlayer. Higher coercivity and improved SNR property were obtained compared to media that had CoTi or Cr underlayer. Transmission electron microscopy analysis showed that the crystal grain size and grain size distribution in the magnetic layer were reduced when the [Cr.sub.75][Ti.sub.25] double layer was used as underlayer. Furthermore, from the delta-M and magnetic force microscopy analyses, it was found that CoCrPt/[Cr.sub.75][Ti.sub.25]/CoTi triple layered thin films had higher magnetic decoupling of neighboring grains than that of CoCrPt deposited on CoTi or Cr underlayer. Index Terms--Coercivity, SNR, [Cr.sub.75][Ti.sub.25]/CoTi double underlayer, magnetic decoupling.

A magneto-optical spatial light modulator (MOSLM) is a real-time programmable device for modulating the amplitude and/or phase of two-dimensional optical signals at a high speed. Recently, we reported the development of the transmission-type MOSLM (T-MOSLM) based on a one-dimensional magnetophotonic crystal (MPC) with a high driving performance. However, further improvement of the T-MOSLM is required. The structure of the T-MOSLM has low optical efficiency due to weakening of transmittance through electrodes; furthermore, the fabrication of the driving electrodes is a very complicated process. In this study, we suggest a new design of the MPC for a reflection-type MOSLM (R-MOSLM). The idea of a reflection-type MPC (R-MPC) is to replace one of the Bragg mirrors with an aluminum reflection film. The structure is glass/(Ta2O5/SiO2)k/Bi:YIG/Al, where k is the repetition number. The approach of the optimal structure of the R-MPC was done by the calculation of the matrix approach method. In the calculation of the newly designed R-MPC, Kerr rotation of -10° was obtained. This result implied that the performance of the R-MOSLM using the MPC could be highly improved. According to the optimization of the calculation, the R-MPC was fabricated and its Kerr rotation was -2.2°. This means that Kerr rotation was enhanced by using the new design of the reflection-type MPC. In addition, surface reflection was the reason for the low reflectance and deterioration of Kerr rotation. [ABSTRACT FROM AUTHOR]

Thermal stability of a nanostructured trilayer synthetic antiferromagnet is investigated in the Worledge model. No or minimal shape anisotropy effect is predicted from the model due to the simplifying assumption that the self-demagnetizing field is equal to the dipole field. A slight relaxation of the assumption causes a large impact on the thermal stability. In the case that the dipole field is 90% of the demagnetizing field, the energy barrier to spin flop is doubled to 80 kT in a typical ellipsoid cell (212×106 nm2) for high density magnetic random access memory. The thermal stability of half-selected cells in the writing scheme based on the spin flop is also improved by relaxing the assumption over the applied field range relevant to magnetic random access memory applications. [ABSTRACT FROM AUTHOR]

Thin-film-type magneto-optical spatial light modulator has been developed by combining one-dimensional magnetophotonic crystal (MPC) and micropatterned drive lines. The use of MPC is expected to be effective because the apparent Faraday effect, which is directly proportional to pixel contrast, is largely enhanced by the light localization of light in the vicinity of the magnetic defect in magnetophotonic crystal. The magnetophotonic crystal had a multilayer structure of (Ta2O5/SiO2)k/Bi: yttrium iron garnet/(SiO2/Ta2O5)k formed on a glass substrate, where k is the repetition number and one of optimization parameters in this study. The transmittance T decreased with an increase of k, while Faraday rotation θF increased, indicating that the enhancement of light modulation rate would be achieved by optimizing the figure of merit F defined by F≈T sin 2θF. At k=6, the maximum F=8.8 was obtained, which is about 20 times larger than that of single layer structure. [ABSTRACT FROM AUTHOR]

High-risk human papillomavirus (HPV) is a major risk factor for oral and pharyngeal cancers (OPCs), yet the detailed mechanisms by which HPV promotes OPCs are not understood. Forkhead box M1B (FoxM1B) is an oncogene essential for cell cycle progression and tumorigenesis, and it is aberrantly overexpressed in many tumors. We previously showed that FoxM1B was the putative target of an epithelial-specific transcription factor, Grainyhead-like 2 (GRHL2). In the current study, we demonstrate that HPV type 16 (HPV-16) E6 induces FoxM1B in human oral keratinocytes (HOKs) and tonsillar epithelial cells (TECs) in part through GRHL2. FoxM1B was barely detectable in cultured normal human oral keratinocytes (NHOKs) and progressively increased in immortalized HOKs harboring HPV-16 genome (HOK-16B) and tumorigenic HOK-16B/BaP-T cells. Retroviral expression of HPV-16 E6 and/or E7 in NHOKs, TECs, and hypopharyngeal carcinoma cells (FaDu) revealed induction of FoxM1B and GRHL2 by the E6 protein but not E7. Both GRHL2 and FoxM1B were strongly induced in the epidermis of HPV-16 E6 transgenic mice and HPV+ oral squamous cell carcinomas. Ectopic expression of FoxM1B led to acquisition of transformed phenotype in HOK-16B cells. Loss of FoxM1B by lentiviral short hairpin RNA vector or chemical inhibitor led to elimination of tumorigenic characteristics of HOK-16B/BaP-T cells. Luciferase reporter assay revealed that GRHL2 directly bound and regulated the FoxM1B gene promoter activity. Using epithelial-specific Grhl2 conditional knockout mice, we exposed wild-type (WT) and Grhl2 KO mice to 4-nitroquinolin 1-oxide (4-NQO), which led to induction of FoxM1B in the tongue tissues and rampant oral tumor development in the WT mice. However, 4-NQO exposure failed to induce tongue tumors or induction of FoxM1B expression in Grhl2 KO mice. Collectively, these results indicate that HPV-16 induces FoxM1B in part through GRHL2 transcriptional activity and that elevated FoxM1B level is required for oropharyngeal cancer development. [ABSTRACT FROM AUTHOR]

The application of 13C and 15N labeled phytoplankton makes it possible to directly follow the pathway and transfer of food source (cyanobacteria) into consumers (aquatic organisms), in contrast to past studies where only changes in compositions of chlorophyll-a, clearity, and nutrients were taken as the evidence for these processes. To evaluate the effect of biocontrol by aquatic organisms (aquatic plants; Iris pseudoacorus, filter feeder bivalve; Sinanodonta arcaeformis, and Unio douglasiae, macroinvertebrate; Caridina denticulate, carnivore fish; Pseudobagrus fulvidraco, Odontobutis platycephala, planktivore fish; Pseudorasbora parv, and omnivore fish; Misgurmus anguillicaudatus) on large toxigenic cyanobacteria bloom (Microcystis aeruginosa) in the freshwater ecosystem, we conducted a biomanipulation test on in situ ponds using dual stable isotope tracers (13C and 15N). As a filter feeding bivalve, S. arcaeformis could incorporate more toxic cyanobacteria cells than U. douglasiae, demonstrating its larger detoxification capacity. Also, macroinvertebrate (C. denticulate) continuously assimilated to cyanobacteria species in combination with zooplankton and detritus, probably due to detoxification capacity. Indeed, the aquatic plants (I. pseudoacorus) seem to be nutrient uptakes in water column and inhibit to light attenuation, comparing to cyanobacteria species. As a primary consumer of phytoplankton, zooplankton (Copepoda) consumed to small and edible particles which is changed from inedible toxic filamentous cyanobacteria species through the grazing efficiency by aquatic organisms. However, various kinds of fishes hardly feed on toxic cyanobacteria directly. Our result suggests that the native species, like Sinanodonta sp. and C. denticulate, are very useful bio-control organisms on toxic cyanobacteria bloom rather than carnivore, omnivore and planktivore fish. Furthermore, if an aquatic plant that can not only remove nutrients but also provide habitats to aquatic organisms (zooplankton, bivalves and shrimps) is developed, it can help control toxic cyanobacteria blooms. Therefore, it is considered that the development and establishment of habitat of useful organisms is very necessary for water quality improvement. Our biomanipulation technique may provide a key tool for efficient management and restoration of eutrophied reservoirs. [ABSTRACT FROM AUTHOR]

The current-induced magnetization reversal sCIMRd effect in nanosized exchange-biased spin valves sEBSd of IrMn/Co1/Cu/Co2 is investigated. The CIMR is studied at RT. With our EBS structure, the critical current can be lowered to 7.5 × 106 A/cm2, which is rather smaller than that in the conventional simple spin valves sSSd Co1/Cu/Co2. This effect can be attributed to the enhancement of spin transfer efficiency by using antiferromagnetic pinning layer in that structure. However, the absolute change in total resistance of EBS, in comparison to that of SS with similar layer thickness, is not increased, as the nearly unpatterned fixed Co layer is pinned. The results are discussed in terms of current induced spin transfer and current induced thermal activation. [ABSTRACT FROM AUTHOR]

Polymer-bonded composites of a Fe-Co based alloy are fabricated and their magnetic and mechanical properties are characterized. The use of flake-type powders with a thickness of 3-5 μm, instead of conventional spherical powders, is the key to good magnetostrictive properties and this is made possible by suitable design of the alloy (Fe[SUB36]Co[SUB62]Ge[SUB2]) and the development of a pulverization process. The composites exhibit high magnetostriction of 105 ppm measured at an applied field of 4.3 kOe (70 ppm at 1 kOe). Large compressive strength of 42 MPa is also obtained for the composites, indicating solid bonding of flake-type powders by the polymer. [ABSTRACT FROM AUTHOR]

Computer simulation is used to examine the size and relative Co layer thickness dependence of the magnetization flop in magnetic tunnel junctions with the structure NiFe(I)(7.5 nm)/AlO[sub x] (0.7 nm)/Co(I)(y nm)/Ru(0.7 nm)/Co(II)(7-y nm)/FeMn(10 nm). The flop angle, which was obtained at a typical sputtering condition from an energy minimization, increases with the increase of y. The unidirectional pinning reduces the magnetization flop and its effect is greater when the Co thickness difference is smaller due to a larger energy contribution from the pinning term. Magnetoresistance hysteresis loops of "as-sputtered" samples, which were subjected to the magnetization flop, are found to vary significantly with the relative Co layer thickness, the cell size, and the magnitude of the unidirectional pinning. [ABSTRACT FROM AUTHOR]

In order to enhance low field magnetoresistance (LFMR) of bulk manganite materials, two series of composites, La[sub 0.7]Sr[sub 0.3]MnO[sub 3]/SrTiO[sub 3] and La[sub 0.7]Sr[sub 0.3]MnO[sub 3]/SrZrO[sub 3], have been prepared by thermal processing of mixed powders. For both series annealing of pelletized mixtures over certain critical temperature leads to the substantial enhancement of LFMR for compositions close to theoretical percolation threshold. At higher processing temperatures enhanced MR values are observed for composites with higher La[sub 0.7]Sr[sub 0.3]MnO[sub 3] content, while compositions with a lower amount of manganite become insulating. The magnitude of enhanced MR remains almost the same within the same series, but the value of enhancement is substantially different for composites, containing SrTiO[sub 3] and SrZrO[sub 3] (1.5% and 2.5% at H = 100 Oe, respectively). Similar dependencies are observed for coercive field values. Observed shift of the enhancement boundary during thermal processing and significant dependence of SrZrO[sub 3] lattice parameters versus components ratio and composite processing temperatures (1100-1200°C) show at substantial chemical interaction in these composites. [ABSTRACT FROM AUTHOR]

The temperature dependence of tunneling magnetoresistance (TMR) is studied for spin valve type double-barrier tunnel junctions. Normalized TMR values for double-barrier tunnel junctions (DBTJs) and single-barrier junctions (SBTJs) are plotted as functions of temperature and it is found that the DBTJ shows stronger temperature dependence of TMR than the SBTJ. The strong temperature dependence of TMR for the DBTJ is explained in terms of temperature dependence of the spin polarization of the middle magnetic layer and decrease of the spin coherence length with increasing temperature. [ABSTRACT FROM AUTHOR]

Magnetic tunnel junctions (MTJ) were fabricated with high oxygen-plasma power and the effects of annealing on the temperature dependence of tunneling magnetoresistance (TMR) were investigated experimentally. As grown, TMR increases, peaks around 160 K, and decreases with increasing temperature from 80 K to 300 K. When MTJs are annealed, T[sub max], the temperature at which maximum TMR is obtained, decreases as annealing temperature increases to the optimal point. In order to explain the temperature dependence of TMR, the difference of conductance between parallel and antiparallel alignments of magnetizations as a function of temperature is also analyzed. The shifts of T[sub max] due to annealing are described phenomenologically with spin-dependent transfer rates of electrons through the barrier. [ABSTRACT FROM AUTHOR]

Direct pulp capping involves the placement of dental materials directly onto vital pulp tissues after deep caries removal to stimulate the regeneration of reparative dentin. This physical barrier will serve as a "biological seal" between these materials and the pulp tissue. Although numerous direct pulp capping materials are available, the use of small bioactive compounds that can potently stimulate and expedite reparative dentin formation is still underexplored. Here, the authors compared and evaluated the pro-osteogenic and pro-odontogenic effects of 4 small bioactive compounds- phenamil (Phen), purmorphamine (Pur), genistein (Gen), and metformin (Met). The authors found that these compounds at noncytotoxic concentrations induced differentiation and mineralization of preosteoblastic MC3T3-E1 cells and preodontoblastic dental pulp stem cells (DPSCs) in a dose-dependent manner. Among them, Phen consistently and potently induced differentiation and mineralization in vitro. A single treatment with Phen was sufficient to enhance the mineralization potential of DPSCs in vitro. More importantly, Phen-treated DPSCs showed enhanced odontogenic differentiation and mineralization in vivo. Our study suggests that these small bioactive compounds merit further study for their potential clinical use as pulp capping materials. [ABSTRACT FROM AUTHOR]

Presents a study that investigated the effects of texture and interfacial roughness on the exchange anisotropy in nickel compound spin valves. Magnetotransport behavior of the compound; Details on the experiment; Discussion on the results of the study.