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The coordination of small molecules and ions at the sixth position of ferric myoglobins (Mb) from the heart muscle of two species of shark,Lamna ditropis (LD) andPrionace glauca (PG), was studied in frozen solution by electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) spectroscopy. The results were compared with those of horse heart Mb (EQMb). From our preliminary studies of the absorption spectra and partial amino acid sequences of PGMb and LDMb, we expected PGMb to have glutamine (Gln E7) in place of the distal His E7 that is highly conserved in most animals and present in LDMb. Here, we have used proton ENDOR to show that a water molecule coordinates to the ferric ion in both LDMb and PGMb at pH 6.3. The observed proton hyperfine coupling constant of the coordinating water molecule of PGMb is smaller than those of LDMb and EQMb, which suggests weaker coordination of the water molecule in PGMb, consistent with the absent distal His (E7). Coordination of several exogenous ligands at the distal site was examined by EPR. PGMb showed a coordination behavior different from that of LDMb and EQMb for 1-methylimidazole, 4-methylimidazole and SCN−, suggesting that its distal site is less sterically hindered. On the basis of the ENDOR and EPR results, we assigned the distal residues of PGMb and LDMb as Gln and His, respectively.

We study current-induced magnetization switching properties of a magnetic tunnel junction with junction diameter of 19 nm and resistance-area product of 6 Ωμm2 in the nanosecond regime with and without in-plane magnetic field. At zero field, for both parallel (P)-to-anti-parallel (AP) and AP-to-P switchings, the probability of switching PSW approaches unity with the increase of pulse voltage duration τP. However, under in-plane magnetic field, PSW for P-to-AP switching starts to saturate at a value lower than unity with increasing τP, while AP-to-P switching remains the same as in the absence of in-plane magnetic field. This in-plane field dependence of PSW can be partially explained by the influence of electric-field modulation of magnetic anisotropy.

It is widely believed that depletion force causes formation of colloidal crystal or flocculation in the stable colloidal suspension mixed with nonadsorbing polymers. This force works between a colloidal particle and plane, which can be regarded as a sphere with infinite radius. We report a novel technique that enables us to measure the depletion force working between a colloidal particle and a glass surface using laser radiation pressure. We found that the observed force almost coincides with the predicted one. {copyright} {ital 1997} {ital The American Physical Society}

Polycrystalline 10 μm thick W foil has been used as a reflection type moderator for the remission of slow positrons in a high intensity slow positron beam system using a cyclotron which produces various kinds of positron sources. The stability of the moderation efficiency has been reviewed in different annealing conditions and gas environment for the practical usage. The moderation efficiency of W foil (2.0 x 10 4 ) starts to be saturated above an in-situ annealing temperature of 2100 °C. Gas treatment with O 2 and H 2 has not been effective for the improvement of the moderation efficiency of W foil. In addition the efficiency has been degraded by 18% of the initial efficiency after the moderator was exposed to air for 12 h and the efficiently recovered after re-annealing at 2100 °C.

We investigated whether long-term infusion of kallikrein would attenuate renal injury in salt-induced hypertension in Dahl salt-sensitive rats. A subdepressor dose of purified rat urinary kallikrein (700 ng/d IV) was infused by osmotic minipump for 4 weeks in male Dahl salt-sensitive rats fed a high salt (2% NaCl) diet. This dose did not affect the time-dependent elevation of blood pressure; however, urinary protein excretion was significantly decreased, and glomerular filtration rate was increased. These beneficial effects were reflected morphologically by an attenuation of glomerulosclerotic lesions and tubular injury seen in the hypertensive Dahl salt-sensitive rats. Kallikrein infusion increased urinary excretion of bradykinin and stimulated excretion of cyclic GMP, suggesting that the kallikrein-kinin-prostaglandin and nitric oxide axes were enhanced by rat urinary kallikrein infusion. The alterations induced by kallikrein infusion were potentiated by the concomitant administration of the angiotensin-converting enzyme inhibitor alacepril. These studies indicated that long-term replacement with rat tissue kallikrein attenuates renal injury in hypertensive Dahl salt-sensitive rats.

The relationship between growth processes and strain relaxation has been investigated on Si1−xGex (0≤x≤1) films grown on (100)Si‐(2×1) surfaces by gas source molecular beam epitaxy using Si2H6 and GeH4. It has been found that the critical film thicknesses for the formation of an (8×2) superstructure, {811}‐faceted islands, and {311}‐faceted islands in the growth process have been found to obey power laws of xn with exponents (n) of approximately −2, −3, and −3 in the range of 0.25≤x≤1.0, respectively. This result indicates that the relaxation of the film strain energy brings about a change into faceted structures and occurs at two steps of {811} and {311} faceting with the film growth. It has been also clarified that the incorporation ratio of Si and Ge atoms into the films is determined by the rate constant ratio of the dissociative adsorption of the hydride compounds, the value of which is six for the Si2H6/GeH4 system.

Growth processes in the initial stage of Ge films on (311)Si substrate surfaces by gas source molecular beam epitaxy using GeH4 have been studied by in-situ observations of reflection high-energy electron diffraction and by replica electron microscopy. It has been found that clean (311)Si surfaces have a (3 × 2) superstructure at substrate temperatures below 500°C and a (3 × 1) superstructure at 600°C. The growth mode of Ge films is of Stranski-Krastanov type and at the final step of two-dimensional (2D) growth a (1 × 2) structure is formed on both the (311)Si−(3 × 2) and −(3 × 1) surfaces. However, a c(4 × 2) structure is observed at the initial stage of growth only below 500°C. At the island growth step, Ge faceted islands have an ordinary shape below 400°C and a long rectangular shape parallel to [ 2 33] above 500°C. The growth behavior of the 2D domains is considered to be connected with the atomic arrangement and the bonding configuration of (311)Si surfaces.

The growth process in the initial stage of growth of Ge films oa Si(111) substrates by gas-source molecular beam epitaxy using GeH4 has been studied by in situ reflection high-energy electron diffraction observations. It has been found that the growth process changes remarkably near 450°C, and that the growth rate of Ge films on Si(111) is one-hundredth as large as that on Si(100). At the first step of growth, δ-7 × 7 and 1 × 1 structures are observed at substrate temperatures below 450°C and, on the other hand, they are not observed above 450°C. In spite of the difference in the first step between the two temperature ranges, Ge films with a 5 × 5 superstructure are finally grown, however, the growth kinetics of the 5 × 5 domains differ between the two temperature ranges. It is considered that the formation of the δ-7 × 7 and 1 × 1 structures and the difference of the growth kinetics are due to the adsorption of hydrogen atoms decomposed from GeH4 molecules.

We examined the effect of cGMP on Na+/Ca2+ exchange in rat aortic smooth muscle cells (VSMCs) in primary culture. The intracellular Ca2+ concentration [( Ca2+]i) was raised by adding ionomycin to VSMCs incubated at high extracellular pH (pH0) (pH0 = 8.8) and high extracellular Mg2+ (Mg2+0) (Mg2+0 = 20 mM), conditions that inhibit activity of the sarcolemmal Ca2+ pump. 45Ca2+ efflux observed under these conditions was mostly extracellular Na+ (Na+0)-dependent and thus presumably catalyzed by the Na+/Ca2+ exchanger. Brief treatment of VSMCs with 8-bromo-cGMP or atrial natriuretic peptide increased this Na+0-dependent 45Ca2+ efflux by about 50%. The 8-bromo-cGMP treatment did not significantly influence total cell Na+, membrane potential, and cell pH. Conversely, when VSMCs were loaded with Na+ and then exposed to a Na+0-free medium, the rate of 45Ca2+ uptake into VSMCs increased as cell Na+ increased. Prior treatment of VSMCs with 8-bromo-cGMP accelerated 45Ca2+ uptake by up to 60% without influencing Na+ loading itself. Treatment of VSMCs with 25 microM 2,5-di-(tert-butyl)-1,4-benzohydroquinone, an inhibitor of the sarcoplasmic reticulum Ca(2+)-ATPase, induced a transient elevation of [Ca2+]i. 8-Bromo-cGMP stimulated the rate of recovery phase of this Ca2+ transient measured in the high pHo/high Mg2+o medium. All these results indicate that cGMP stimulates Na+/Ca2+ exchange in VSMCs.

We have measured the reflection and luminescence spectra of synthetic two-dimensional semiconductor crystals of H3N(CH2)6NH3PbI4 for E∥〈010〉 and E∥〈100〉 polarizations at low temperatures. There appear two absorption bands related to excitons with polarization vectors parallel and oblique to the inorganic layer. From the temperature dependence of the free exciton luminescence intensity, the exciton binding energy is obtained as 0.33 eV, the value of which is consistent with the energy distance between the n=1 and n=2 exciton absorption bands. This very large binding energy is characteristic of layered perovskite crystals.

An ordered structure with the double periodicity in a 〈111〉 direction has been found by in situ reflection high‐energy electron diffraction observation in the initial stage of Ge films grown on (100)Si and (811)Si substrate surfaces by GeH4 gas source molecular beam epitaxy. The ordered structure is formed on {111} planes parallel to the side planes of 〈011〉 steps on {811} facets of Ge growing islands on both substrates. The formation is observed at substrate temperatures of 300–700 °C and is considered to result from solid phase reactions at the interfaces during growth.

Endothelial cell monolayer, which lines the inner surface of the blood vessel, plays an important role in controlling the vascular permeability to a wide variety of solutes to be exchanged between blood and tissues. At the same time, this endothelial monolayer is an unique tissue that ceaselessly is exposed to fluid mechanical stimuli caused by the blood flow. Consequently, the physiological functions of vascular endothelial cells must be discussed taking into consideration numerous factors related to their environment as a whole. Such factors include not only the soluble humoral factors but also mechanical stimuli as fluid-imposed shear stress or cyclic stretch of the vessel wall.

X-ray diffraction, magnetization, and Mossbauer effect are measured for Mn1–yFey alloys produced by vapor quenching. The single α-Mn-type phase extends for 0 ≧ y 0.5 are ferromagnetic with small saturation magnetic moments and their thermomagnetic curve displays a field-cooling effect. Moreover, the Mossbauer spectrum for y > 0.5 shows a hyperfine field higher than 50 kOe. These results indicate micromagnetism in these α-Mn-type alloys. Rontgenbeugung, Magnetisierung und Mosbauereffekt werden fur aus dem Dampf abgeschreckte Mn1–yFey-Legierungen gemessen. Die isolierte α-Mn-Phase erstreckt sich von 0 ≦ y 0,5 ferromagnetisch mit kleinen magnetischen Sattigungsfeldern sind und ihre thermomagnetische Kurve einen Feldkuhlungseffekt zeigt. Daruberhinaus zeigt das Mosbauerspektrum fur y > 0,5 ein Hyperfeinfeld von groser als 50 kOe. Diese Ergebnisse zeigen Mikromagnetismus in diesen α-Mn Legierungen.

The preparation and properties of direct current electroluminescent (dc EL) materials using manganese-activated ZnS powders for a flat-panel TV display are described. The firing process, the copper coating process, and the ferming process have been investigated. Suitable powder phosphors for the display panel contain 0.1-0.5 wt % manganese and 0.25-0.35 wt % copper coated on the ZnS powder surface. Although the powder-type dc EL still has low luminous efficiency, the light output can be increased to a useful level by exciting the panel with voltage pulses of high peak power. The crosstalk effect in the display panel can also be suppressed, since the brightness is very nonlinear with respect to the applied voltage. The sealing of the panel with silicone oil is effective in lengthening the life of the panel. An experimental dc EL panel with a 13-in diagonal and 50 176 picture elements has been fabricated, capable of reproducing broadcast TV images. These images have a highlight brightness of 10 fL, a contrast ratio of 20:1, a limiting resolution of about 150 TV lines in both horizontal and vertical directions, and a gray-scale capability of 16 steps.

Page 915: Yoshida, F., and N. Ohshima, “Diffusivity of oxygen in blood serum.” The sentence near the end of the first paragraph of the introduction (p. 915) should read; “The values of diffusivity of oxygen in serum at 25 C ranged from 1.63 to 2.21 x 1O–5 cm2/sec depending on the thickness of the layer.”