Showing papers by "Sophia University published in 2006"

A Stand-Alone Hybrid Generation System Combining Solar Photovoltaic and Wind Turbine with Simple Maximum Power Point Tracking Control

Abstract: This paper proposes a hybrid energy system combing solar photovoltaic and wind turbine as a small-scale alternative source of electrical energy where conventional generation is not practical. A simple and cost effective control technique has been proposed for maximum power point tracking from the photovoltaic array and wind turbine under varying climatic conditions without measuring the irradiance of the photovoltaic or the wind speed. The proposed system is attractive owing to its simplicity, ease of control and low cost. A complete description of the proposed hybrid system along with detailed simulation results which ascertain its feasibility are given to demonstrate the availability of the proposed system in this paper. Simulation of the hybrid system under investigation was carried out using PSIM software.

Syntheses of calcium-deficient apatite fibres by a homogeneous precipitation method and their characterizations

Abstract: Calcium-deficient apatite fibres were successfully synthesized by a homogeneous precipitation method using starting solutions with a Ca/P ratio of 1.00–1.67. In the case of the Ca/P ratio of 1.67, the resulting apatite fibre had long-axes of about 60–100 μm and contained 5.2 mass % of carbonate ions. The Ca/P ratio of apatite fibres could be controlled in the range of 1.53–1.68 by changing the Ca/P ratio of the starting solutions from 1.00 to 1.67. The long-axes and the carbonate contents of the resulting calcium-deficient apatite fibres increased with Ca/P ratio of the starting solutions. These apatite fibres were of single crystal and had a preferred orientation in the c -axis direction.

Thermal and optical properties of transparent magnesium oxide ceramics fabricated by post hot-isostatic pressing

Abstract: The transparent magnesium-oxide (MgO) ceramic could be fabricated by a hot-isostatic press (HIP) technique of pressureless-sintered MgO compact, using non-agglomerated MgO powder with the average primary particle size of 57 nm. The relative density and average grain size of MgO compact pressureless-sintered at 1600 °C for 5 h were 96.7% and 10.7 μm, respectively. Owing to the HIPing operation (0.5 h) of pressureless-sintered compact at a temperature between 1500 and 1600 °C, relative densities of the MgO ceramics attained 99.9% or more with light transmission. The average grain size increased from 132 to 199 μm with HIPing temperature from 1500 to 1600 °C. The in-line transmission of the MgO specimen HIPed at 1600 °C for 0.5 h increased from 52 to 55% with increasing wavelength from 500 to 900 nm and corresponded to approximately 65%, compared to that of the MgO single crystal. The thermal conductivity of this MgO specimen attained 53.5 W m −1 K −1 , whereas the thermal diffusivity decreased gradually to reach 0.0416 cm 2 s −1 with increasing test temperature up to 873 K.

Asymmetric fluorination of β-keto esters catalyzed by chiral rare earth perfluorinated organophosphates

Abstract: Novel chiral rare earth metal complexes bearing perfluorinated binaphthyl phosphate ligand RE[( R )-F 8 BNP] 3 (RE = rare earth; F 8 BNP = 5,5′,6,6′,7,7′,8,8′-octafluoro-1,1′-binaphthyl-2,2′-diyl phosphate) have been synthesized and used as a catalyst for the asymmetric electrophilic fluorination reaction of β-keto esters. The use of Sc[( R )-F 8 BNP] 3 catalyst in combination with 1-fluoropyridinium triflate (NFPY–OTf) as a fluorinating agent was found to give the desired α-fluoro-β-keto esters in high chemical yields and enantiomeric excesses (up to 88% ee) under mild conditions.

Pulse-modulated, high-frequency plasma sterilization at atmospheric-pressure

Abstract: We studied atmospheric-pressure glow (APG) plasma excited with pulse-modulated RF at 27.12 MHz, using dielectric barrier electrodes. The antibacterial effect of APG plasma was examined using spore-forming bacteria: Bacillus atrophaeus, Geobacillus stearothermophilus, and the following selected species of bacteria, a mold, and yeast-like fungus: Salmonella enteritidis, Staphylococcus aureus, Candida albicans, and Aspergillus niger. Optimum experimental conditions were sought, to find commonality among several conditions: antibacterial effect, neutral gas temperature, and homogeneity over the electrode surface.

Systematic Studies on Chain Lengths, Halide Species, and Well Thicknesses for Lead Halide Layered Perovskite Thin Films

Abstract: Two-dimensional layered perovskite compounds, (CnH2n+1NH3)2(CH3NH3)m−1PbmX3m+1 (n = 2, 3, 4, 6, and 10; X = Cl, Br, and I; m = 1, 2, and 3) were systematically prepared. The influences of the barri...

Young's double-slit experiment using core-level photoemission from N2: revisiting Cohen–Fano's two-centre interference phenomenon

Abstract: The core-level photoelectron spectra of N2 molecules are observed at high energy resolution, resolving the 1σg and 1σu components as well as the vibrational components in the extended energy region from the threshold up to 1 keV. The σg/σu cross section ratios display modulation as a function of photoelectron momentum due to the two-centre interference, analogous to the classical Young’s double-slit experiment, as predicted by Cohen and Fano a long time ago. The Cohen–Fano interference modulations display different phases depending on the vibrational excitations in the core-ionized state. Extensive ab initio calculations have been performed within the Hartree–Fock and random phase approximations in prolate spheroidal coordinates. The dependence of photoionization amplitudes on the vibrational states was taken into account using the Born–Oppenheimer approximation. The ab initio results are in reasonable agreement with the experimental data. The theoretical analysis allows the modulation to be connected with the onset of transitions to the states of increasing orbital angular momentum which occurs at increasing photon energies. Deviation from the Cohen–Fano formula is found for both the experimental and the ab initio results and is attributed to electron scattering by the neighbouring atom. A new formula for the interference modulation is derived within the framework of the multiple scattering technique. It differs from the classical Cohen–Fano formula by the addition of twice the scattering phase of the photoelectron by the neighbouring atom. We demonstrate that

Huge exchange energy and fine structure of excitons in an organic-inorganic quantum well material

Abstract: Photoluminescence and spin-flip Raman scattering of excitons in an organic-inorganic quantum well material ${({\mathrm{C}}_{4}{\mathrm{H}}_{9}\mathrm{N}{\mathrm{H}}_{3})}_{2}\mathrm{Pb}{\mathrm{Br}}_{4}$ have been investigated at low temperature. The estimated exchange energy of the exciton is greatly enhanced by strong confinement and by image charge effects, and ranges from $28\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}32\phantom{\rule{0.3em}{0ex}}\mathrm{meV}$. These values are one or two orders of magnitude larger than those for quantum wells made from the more usual inorganic materials. The ratio of the oscillator strength of the dipole-allowed exciton to that of the dark (dipole-forbidden) exciton is estimated to be of order 800.

Symmetry-dependent vibrational excitation in N 1s photoionization of N2: experiment and theory

Abstract: We have measured the vibrational structures of the N 1s photoelectron mainline and satellites of the gaseous N2 molecule with the resolution better than 75meV. The gerade and ungerade symmetries of the core-ionized (mainline) states are resolved energetically, and symmetry-dependent angular distributions for the satellite emission allow us to resolve the Σ and Π symmetries of the shake-up (satellite) states. Symmetry-adapted cluster-expansion configuration-interaction calculations of the potential energy curves for the mainline and satellite states along with a Franck-Condon analysis well reproduce the observed vibrational excitation of the bands, illustrating that the theoretical calculations well predict the symmetry-dependent geometry relaxation effects. The energies of both mainline states and satellite states, as well as the splitting between the mainline gerade and ungerade states, are also well reproduced by the calculation: the splitting between the satellite gerade and ungerade states is calculat...

A novel hydroxyapatite fiber mesh as a carrier for recombinant human bone morphogenetic protein-2 enhances bone union in rat posterolateral fusion model.

Abstract: Study Design. An experimental study, in which spinal fusion in rats was conducted using a hydroxyapatite fiber mesh (HAM) as a carrier for recombinant human bone morphogenetic protein (rhBMP)-2. Objectives. To study the usefulness of the HAM as a carrier and seek the possibility of clinical application in spinal fusion. Summary of Background Data. Several biomaterials have been used as a carrier for BMP to achieve spine fusion, however, to our knowledge, the most effective carrier has not been established. Methods. In experiment No. 1, HAMs and the controls (commercially available hydroxyapatite ceramic body), loaded with rhBMP-2, were immersed in phosphate-buffered saline to evaluate the time course of the release of rhBMP-2. In experiment No. 2, posterolateral fusion was conducted in rats using HAM and the control loaded with rhBMP-2. The fusion status was evaluated radiologically and histologically after surgery. Results. In experiment No. 1, HAMs released a larger amount of rhBMP-2 for up to 28 days than the controls (49.5% vs 7.8%). In experiment No. 2, the fusion rate was significantly higher in the HAM group (>80%) than in the control group (20%). Dense new bone formed close to the spine, and the HAMs were markedly absorbed compared with the controls. Conclusion. HAM provided more solid fusion mass than the control, suggesting that HAM is an efficient carrier for BMP.

Evolution of teleostean hatching enzyme genes and their paralogous genes.

Abstract: We isolated genes for hatching enzymes and their paralogs having two cysteine residues at their N-terminal regions in addition to four cysteines conserved in all the astacin family proteases. Genes for such six-cysteine-containing astacin proteases (C6AST) were searched out in the medaka genome database. Five genes for MC6AST1 to 5 were found in addition to embryo-specific hatching enzyme genes. RT-PCR and whole-mount in situ hybridization evidenced that MC6AST1 was expressed in embryos and epidermis of almost all adult tissues examined, while MC6AST2 and 3 were in mesenterium, intestine, and testis. MC6AST4 and 5 were specifically expressed in jaw. In addition, we cloned C6AST cDNA homologs from zebrafish, ayu, and fugu. The MC6AST1 to 5 genes were classified into three groups in the phylogenetic positions, and the expression patterns and hatching enzymes were clearly discriminated from other C6ASTs. Analysis of the exon–intron structures clarified that genes for hatching enzymes MHCE and MAHCE were intron-less, while other MC6AST genes were basically the same as the gene for another hatching enzyme MLCE. In the basal Teleost, the C6AST genes having the ancestral exon–intron structure (nine exon/eight intron structure) first appeared by duplication and chromosomal translocation. Thereafter, maintaining such ancestral exon–intron structure, the LCE gene was newly diversified in Euteleostei, and the MC6AST1 to 5 gene orthologs were duplicated and diversified independently in respective fish lineages. The HCE gene lost all introns in Euteleostei, whereas in the lineage to zebrafish, it was translocated from chromosome to chromosome and lost some of its introns.

The politics of a reviving buddhist temple : State, association, and religion in Southeast China

Abstract: NANPUTUO IS A MAJOR TEMPLE on China’s southeast coast that was shut down during the Cultural Revolution (1966–76) but has since rapidly revived. The temple’s academy for training clergy reopened, an abbot was appointed, a Buddhist philanthropy foundation was established, and the number of clergy grew to 600 persons by 2001. The temple, located in Xiamen city, Fujian province, has also reemerged as a center of religious activity with streams of worshippers and tourists, frequent rituals and ceremonies, and huge crowds on Guanyin’s birthday and other major festivals. It is one of the liveliest, wealthiest, and best-managed Buddhist temples in Han China today (Birnbaum 2003; Luo 1991, 170–182; MacInnis 1989, 135). The temple’s revival is occurring in the context of an increasingly elaborated state system to administer religions. This system reflects the modern idea of “religion” (zongjiao) that entered China in the late nineteenth century as individual belief and the scientific distinction between religion and superstition. The concept started to be reflected in state rules and regulations from the late Qing Dynasty. In the 1950s, the Chinese Communist Party’s (CCP’s) new religion policy recognized five religions— Buddhism, Catholicism, Taoism, Islam, and Protestantism—while actively suppressing other beliefs and rituals that it classified as superstition. During the Cultural

Boost-half-bridge edge resonant soft switching PWM high-frequency inverter for consumer induction heating appliances

Abstract: A novel soft-switching PWM utility frequency AC to high-frequency AC power conversion circuit, incorporating boost-half-bridge inverter topology, which is more suitable and acceptable for cost effective consumer induction heating applications, is presented. The operating principle and the operation modes are described using equivalent circuits with the operating voltage and current waveforms. The operating performances are illustrated and evaluated, including the power regulation and power conversion efficiency against duty cycle characteristics based on the power dissipation as compared with those of the previously developed high-frequency inverter. The practical effectiveness of the power converter is substantially proved, based on experimental results from a practical design example.

Change in the actin cytoskeleton during seismonastic movement of Mimosa pudica.

Abstract: The seismonastic movement of Mimosa pudica is triggered by a sudden loss of turgor pressure. In the present study, we compared the cell cytoskeleton by immunofluorescence analysis before and after movement, and the effects of actin- and microtubule-targeted drugs were examined by injecting them into the cut pulvinus. We found that fragmentation of actin filaments and microtubules occurs during bending, although the actin cytoskeleton, but not the microtubules, was involved in regulation of the movement. Transmission electron microscopy revealed that actin cables became loose after the bending. We injected phosphatase inhibitors into the severed pulvinus to examine the effects of such inhibitors on the actin cytoskeleton. We found that changes in actin isoforms, fragmentation of actin filaments and the bending movement were all inhibited after injection of a tyrosine phosphatase inhibitor. We thus propose that the phosphorylation status of actin at tyrosine residues affects the dynamic reorganization of actin filaments and causes seismonastic movement.

Growth and characterization of InGaN/GaN nanocolumn LED

Abstract: GaN nanocolumn (sometimes called as nanorod, nanowire, and nanopillar) is a columnar single crystalline GaN nano-crystal having small diameter of from tens to hundreds nanometers. In this paper, photoluminescence (PL) study of GaN nanocolumns and InGaN multiple quantum disks (MQDs) embedded in the GaN nanocolumns grown by RF-plasma assisted molecular beam epitaxy are described. The room temperature PL peak intensity of GaN nanocolumns was several hundred times stronger than that of conventional GaN film with dislocation density of 3~5x109 cm-2. Stimulated emission with very low threshold optical power density of 198~290 kW/cm2 was observed for the GaN nanocolumns. InGaN MQDs also showed intense PL emission with peak wavelength of from 436 (blue) to 614 nm (red). GaN nanocolumn based light emitting diodes (LEDs) with InGaN MQD active layer were successfully fabricated on n-type (111) Si substrates. The emission color of the nanocolumn LED was varied from violet to red by changing the growth conditions of InGaN MQD active layer. The full width at half maximum (FWHM) of emission spectrum of the LED emitting around 500 nm taken from whole semi-transparent top electrode area (Φ=500 μm) was 73.5 nm but from small area (Φ=3 μm) was 37.0 nm. This result suggests that emission spectrum of a single InGaN quantum disk have narrower FWHM but large area LED that contains huge number of nanocolumn LEDs have wider FWHM.

Real-time monitoring of the secretory function of cultured adrenal chromaffin cells.

Abstract: A system to discriminate the real-time dynamics of the secretory function in cultured adrenal chromaffin cells, using a cell bed perfusion technique and an amperometric detector, was established. Examination of basal conditions revealed that the electrode potential and flow rate are crucial factors for monitoring precise dynamics of the secretory process. Stimulation of the cells either with acetylcholine (ACh) or with high K+ concentration caused a transient current response. The current responses showed concentration dependence for both stimuli, and also showed a high correlation with the amount of catecholamines (CA) in the respective peak fraction of perfusate. Either prolonged cholinergic stimulation or maintained depolarization produced a transient response, which is not attributable to a depletion of releasable storage of CA as indicated by double-stimulation experiments. Stimulation with high K+ concentration evoked an additional release of CA even after the cellular response to prolonged ACh was inactivated, whereas maintained depolarization with high K+ produced both facilitatory and inhibitory effects on the cell responsiveness to ACh. Most probably the transient natures of the secretory responses to ACh and to high K+ are mediated by different mechanisms. All the results suggest that the direct monitoring is profitable for studies on the regulatory mechanisms of the secretory function.

Hydrophilic modification of expanded polytetrafluoroethylene (ePTFE) by atmospheric pressure glow discharge (APG) treatment

Abstract: ePTFE has been used in biomedical applications such as artificial blood vessels. However, the inherent nature of the highly hydrophobic ePTFE surface retards tissue ingrowth and wound healing. APG plasma treatment was applied to modify ePTFE tubes from being hydrophobic to being hydrophilic with AAc or PAA. The plasma-pretreated ePTFE tubes were immersed in AAc or PAA solution, then treated with helium-APG plasma. The spectra of FTIR–ATR adopted the appearance of an absorption peak ascribed to carbonyl group, and XPS showed reduced F / C and increased O / C. The water contact angles after treatment were decreased. An SEM image showed that the fibrils of ePTFE tubes were interconnected with each other to form assembled bundles of fibrils. These results indicated the formation of an insoluble polymerized AAc or PAA layer on the ePTFE surface. Polymerization of AAc or PAA began occurring on the surface of ePTFE and then continued within porous structures. The surfaces of ePTFE were more effectively modified by PAA than AAc. The outer surface was more hydrophilic than the inner surface. When the outer tube of ePTFE was wrapped with PTFE film and processed using the same experimental method, a markedly enhanced surface modification on the inner surface, especially with the use of AAc, was observed. AAc was easier to polymerize on the surface of the ePTFE tube, as a result, the hydrophilicity of the inner surface was increased.

Idiosyncrasy of nasal sounds in human speaker identification and their acoustic properties

Abstract: 1. Introduction Speech sounds convey not only linguistic or phonological information, but also nonlinguistic information, including the speakers' individualities [1]. It is known that the availability of the speech contents used for speaker identification differs depending on the types of sounds they contain, and it is reported that voiced sonorants, such as vowels and nasals, are most effective for speaker identification by both humans [2–4] and machines [5]. The speaker's individuality contained in speech sounds should have some acoustic correlations and their properties can be measured as acoustic parameters [6]. In this study, we conducted a human speaker identification test, and investigated the differences in the effectiveness of using various Japanese sounds in identifying the speakers. We also analysed the stimuli used in the experiment in order to explain these differences in terms of acoustical distances.

Laser spectroscopy of 7,10 Be + in an online ion trap

Abstract: Radioactive beryllium isotope ions ($^{7}\mathrm{Be}^{+}$ and $^{10}\mathrm{Be}^{+}$) that are provided by a projectile fragment separator with $\ensuremath{\approx}1\phantom{\rule{0.3em}{0ex}}\mathrm{GeV}$ beams, as well as stable isotope ions $(^{9}\mathrm{Be}^{+})$ are stored and laser cooled in an online ion trap. Their absolute transition energies of the $2s\phantom{\rule{0.2em}{0ex}}^{2}S_{1∕2}\ensuremath{\rightarrow}2p\phantom{\rule{0.2em}{0ex}}^{2}P_{3∕2}$ transition were measured with an accuracy of $\ensuremath{\sim}{10}^{\ensuremath{-}8}$. In this way isotope shifts of beryllium ions were obtained and the differential mass polarization parameter $\ensuremath{\kappa}=\ensuremath{-}0.286 41(70)\phantom{\rule{0.3em}{0ex}}\mathrm{a.u.}$ as well as the $2s\phantom{\rule{0.2em}{0ex}}^{2}S\ensuremath{\rightarrow}2p\phantom{\rule{0.2em}{0ex}}^{2}P$ transition energy of an infinitely heavy beryllium ion $h{\ensuremath{ u}}^{\ensuremath{\infty}}=0.145 524 290(42)\phantom{\rule{0.3em}{0ex}}\mathrm{a.u.}$ were determined for the first time.

Electroabsorption modulator using intersubband transitions in GaN-AlGaN-AlN step quantum wells

Abstract: We calculate the high-speed modulation properties of an electroabsorption modulator for lambda=1.55 mum based on Stark shifting an intersubband resonance in GaN-AlGaN-AlN step quantum wells. In a realistic simulation assuming an absorption linewidth Gamma=100 meV we obtain an RC-limited electrical f3dB~60 GHz at an applied voltage swing Vpp=2.8 V. We also show that a small negative effective chirp parameter suitable for standard single-mode fiber is obtained and that the absorption is virtually unsaturable. The waveguide is proposed to be based on the plasma effect in order to simultaneously achieve a strong confinement of the optical mode, a low series resistance, and lattice-matched cladding and core waveguide layers. Extrapolated results reflecting the decisive dependence of the high-speed performance on the intersubband absorption linewidth Gamma are also given. At the assumed linewidth the modulation speed versus signal power ratio is on a par with existing lumped interband modulators based on the quantum confined Stark effect

C1s and O1s photoelectron satellite spectra of CO with symmetry-dependent vibrational excitations

Abstract: The photoelectron shake-up satellite spectra that accompany the C1s and O1s main lines of carbon monoxide have been studied by a combination of high-resolution x-ray photoelectron spectroscopy and accurate ab initio calculations. The symmetry-adapted cluster-expansion configuration-interaction general-R method satisfactorily reproduces the satellite spectra over a wide energy region, and the quantitative assignments are proposed for the 16 and 12 satellite bands for C1s and O1s spectra, respectively. Satellite peaks above the pi(-1)pi(*) transitions are mainly assigned to the Rydberg excitations accompanying the inner-shell ionization. Many shake-up states, which interact strongly with three-electron processes such as pi(-2)pi(*2) and n(-2)pi(*2), are calculated in the low-energy region, while the continuous Rydberg excitations are obtained with small intensities in the higher-energy region. The vibrational structures of low-lying shake-up states have been examined for both C1s and O1s ionizations. The vibrational structures appear in the low-lying C1s satellite states, and the symmetry-dependent angular distributions for the satellite emission have enabled the Sigma and Pi symmetries to be resolved. On the other hand, the potential curves of the low-lying O1s shake-up states are predicted to be weakly bound or repulsive.

Improving syllable identification by a preprocessing method reducing overlap-masking in reverberant environments

Abstract: Overlap-masking degrades speech intelligibility in reverberation [R. H. Bolt and A. D. MacDonald, J. Acoust. Soc. Am. 21(6), 577–580 (1949)]. To reduce the effect of this degradation, steady-state suppression has been proposed as a preprocessing technique [Arai et al., Proc. Autumn Meet. Acoust. Soc. Jpn., 2001; Acoust. Sci. Tech. 23(8), 229–232 (2002)]. This technique automatically suppresses steady-state portions of speech that have more energy but are less crucial for speech perception. The present paper explores the effect of steady-state suppression on syllable identification preceded by /a/ under various reverberant conditions. In each of two perception experiments, stimuli were presented to 22 subjects with normal hearing. The stimuli consisted of mono-syllables in a carrier phrase with and without steady-state suppression and were presented under different reverberant conditions using artificial impulse responses. The results indicate that steady-state suppression statistically improves consonant ...

Vibrationally resolved photoionization of the 1σg and 1σu shells of N2 molecule

Abstract: Theoretical and experimental study of vibrationally resolved partial photoionization cross sections and angular asymmetry parameter β for the 1σg and 1σu shells of N2 molecule in the region of the σ* shape resonance is reported. The measurements were made at the synchrotron radiation facility SPring-8 in Japan. The calculations in the random phase approximation have been performed using the relaxed core Hartree–Fock wavefunctions with the fractional charge of the ion core equal to 0.7. With its help, the role of interchannel coupling between the closely spaced 1σg and 1σu shells was studied. The experiment demonstrates the existence of a correlational maximum in the 1σu shell photoionization cross section induced by the σ* shape resonance in the 1σg shell. This maximum reveals itself even more clearly in the angular asymmetry parameter β for the v' = 0 and v' = 1 vibrational states of the ion. The calculation in the random phase approximation gives a consistent interpretation of the experimental data.

3-D Human Navigation System with Consideration of Neighboring Space Information

Abstract: Human movement such as walking or traveling in a wheelchair involves vertical movement. Previously, we developed a real ubiquitous round-the-clock 3D navigation system for pedestrian point-to-point navigation, in which position detection is driven mainly by dead reckoning with the help of RFID technology. A number of navigation systems have been developed for pedestrians, but few consider dynamic information. The newly proposed "Moudo-Cane" system extends the previously developed system [1] and provides more reliable and convenient guidance throughout the journey, even when GPS information is unavailable, in an attempt to not only provide a universally available navigation system, but also to provide assistance for visually impaired or wheelchair-bound users by taking their preferences into account.

Pressure-Induced Magnetic Quantum Phase Transition in Gapped Spin System KCuCl3

Abstract: Magnetization and neutron elastic scattering measurements under a hydrostatic pressure were performed on KCuCl 3 , which is a three-dimensionally coupled spin dimer system with a gapped ground state It was found that an intradimer interaction decreases with increasing pressure, while the sum of interdimer interactions increases This leads to the shrinkage of spin gap A quantum phase transition from a gapped state to an antiferromagnetic state occurs at P c ≈82 kbar For P > P c , magnetic Bragg reflections were observed at reciprocal lattice points equivalent to those for the lowest magnetic excitation at zero pressure This confirms that the spin gap decreases and closes under applied pressure