Steep Maximum Research Articles

Experimental evidence of impurity-band transport in p-type polycrystalline germanium film

Herein, we report on the Hall transport properties of a p-type polycrystalline germanium film, which is grown by the DC magnetron sputtering method. The average grain size of 85 nm is calculated. The resistivity and Hall coefficient of the germanium film were measured at temperatures between 100 K and 350 K. At room temperature (T = 300 K), the resistivity of 1.06 Ω cm, the hole concentration of 7.6 × 1017 cm−3 and mobility of 7.76 cm2V−1s−1 are obtained. The temperature dependence of Hall coefficient presents a steep maximum at a specific temperature (T☆ ≈ 215 K). At the same time, the slope of the log resistivity versus 1/T curve is changed. The unusually results can be well explained by a two-band conduction model, which includes the valence band with a high mobility, and the acceptor impurity band with a much lower mobility. This work gives an evidence for impurity-band conduction in the polycrystalline germanium film.

表面プラズモンを励起した強磁性金属/ 非磁性貴金属積層膜における縦カー効果の飽和および線型成分の増強

Enhancement of the longitudinal Kerr effect by excitation of surface plasmon resonance (SPR) in ferromagnetic Co72Fe8B20/Au stacked films was investigated in a Kretschmann configuration with p-polarized light at 633 nm. We found that (1) it was possible to excite SPR in the bi-layer structure of Co72Fe8B20/Au with the necessity of the Au layer faced to air. We also found that (2) the dependence of the longitudinal Kerr effect on the incident angle indicated that the saturation component of ellipticity was bell-shaped in the hysteresis loop, while the rotation angle had a dispersed-shaped distribution. In contrast, the rotation angle was bell-shaped for the linear component, while the ellipticity had a dispersed-shaped distribution. Moreover, we discovered that (3) the saturation component of the longitudinal Kerr effect in the Co72Fe8B20/Au (20 nm) stacked film had a steep maximum as a function of the thickness of the ferromagnetic layer, and that the strongest resonance occurred at a ferromagnetic layer thickness of 8 nm. In addition, we found that (4) the linear component of the longitudinal Kerr effect was caused by the Faraday effect of the prism and glass substrate, which was extremely enhanced by SPR.

Doppler echocardiographic analysis of diastolic function in dilatative cardiomyopathy for the evaluation of its progression and prognosis

The relationship between left-ventricular diastolic function and the course of the disease was investigated in a prospective study of 61 patients (44 men, 17 women; median age 51 [26-74] years) with dilated cardiomyopathy. The diastolic function was measured by recording the transmitral Doppler flow profile. During a follow-up period of 33 +/- 23 months, 15 patients died (twelve of progressive heart failure, three suddenly without previous heart failure). Cardiac transplantation was performed in four patients. The overall 1-year mortality rate was 14%. A "restrictive" Doppler echocardiographic filling pattern with a steep early-diastolic maximum and a small atrial filling component predominated in the patients who died from progressive heart failure or had a cardiac transplantation because of it. The deceleration of the early diastolic velocity maximum was clearly shorter than in the survivors (111 +/- 32 ms vs 194 +/- 62 ms; P < 0.001). In a Cox proportional hazard model the deceleration time was the best prognosticator, followed by the end diastolic left-ventricular diameter (LVD). The group of patients with a short deceleration time (< or = 140 ms) had a significantly higher 1-year mortality rate (28% [confidence interval 9-47%]) than those in whom it was longer (3% [0-11%]; P < 0.0001). Taking into account LVD it proved possible to identify a prognostically especially unfavourable group with a 1-year mortality rate of 53% (26-80%), characterized by a LVD > 70 mm and a deceleration time < or = 140 ms. Repeated echocardiography in 26 survivors and nine patients who died later or had been operated on showed that the deceleration time did not change significantly in the course of the disease. On the other hand, the systolic function, as measured by the echocardiographically determined shortening fraction, improved in the survivors (from 0.18 +/- 0.07 to 0.22 +/- 0.08; P < 0.05), but not in those who later on died.

Solitary waves on inclined films: their characteristics and the effects on wall shear stress

The properties of solitary waves, developing from inlet disturbances of controlled frequency along an inclined film flow, are systematically studied experimentally and computationally. Time-variations of film height and wall shear stress are measured, using respectively a capacitance probe and an electrodiffusion sensor. Computational data are provided from simulations performed by a Galerkin finite element scheme. The height and spacing of solitary humps, their phase velocity and the wavelength of the preceding capillary ripples are reported as functions of the Reynolds number (10<Re<100) and the inlet frequency (0.5 Hz< f<2.5 Hz). The wall shear stress modulation imposed by the passage of solitary waves is studied experimentally and computationally as a function of Re. Distinct nonlinear characteristics are noted, including a steep maximum and a negative minimum, with the effects intensifying at intermediate Re. All computer predictions are found to be in good quantitative agreement with the experimental data.

Cross section of the 32S(α, p) 35Cl nuclear reaction for sulphur determination

Differential cross sections of the 32S(α, p x ) 35Cl( x = 0, 1, 2, 3) nuclear reactions were measured in the energy range between 6.0 and 12.0 MeV in steps of 10 to 50 keV for laboratory angles of 60°, 90°, 120°, 135°, 157° and 167° using thin sulphur targets. The targets were prepared by sulphur implantation into carbon with a fluence of 5.0 × 10 17 at./cm 2 and a maximum concentration of about 1.5 × 10 17 at./cm 2 in a depth of 50 nm. The location and concentration of the implanted sulphur were determined by RBS. The differential cross sections at 167° exhibit a steep maximum for the α-particle energy of 6.90 MeV. The reaction was used to determine the concentration of sulphur in different materials.

Evidence for Holocene stability of steep slopes, northern Peruvian Andes, based on soils and radiocarbon dates

Summary Radiocarbon dating and soil relationships indicate that landscapes in highaltitude glaciated valleys of the northern Peruvian Andes have been remarkably stable during the Holocene. Radiocarbon dates show that deglaciation was underway by 12 ka, and that slopes and alluvial fans at the bases of slopes were essentially stabilized by at least 8 ka. The soils consist of fine-grained loessial A horizons overlying Bw horizons in gravelly till or alluvial-fan gravel. Following deglaciation, widespread gullying took place in till on the steep (maximum angle: 37°) sideslopes of most valleys; the eroded material was deposited as fans at the bases of the slopes. Loess was then deposited as a fairly uniform blanket across most elements of the landscape. Soil formation began during or following loess deposition, and because soil-profile morphology is sufficiently similar at most sites, soil formation has been a dominant process during much of the Holocene. This remarkable stability, especially for such steep slopes, is attributed to a combination of tight packing of the till, permeability of the capping loess, rapid revegetation following ice retreat, and roots from the present grassland vegetation and possibly former forests.

Investigation of expected location of muonium in normal state in III?V semiconductors and associated muon hyperfine interaction

The location and hyperfine properties of muonium in AlP is investigated by the unrestricted Hartree-Fock cluster procedure. Two minima are found, one at the aluminium tetrahedral interstitial site, and the other at the corresponding phosphorus site. The former is deeper by 0.25 eV and separated from the other minimum by a steep maximum of 0.63 eV in the hexagonal region. Using the calculated electronic wave functions, the muon hyperfine constant, after vibrational averaging, comes out smaller than the value for free muonium, the ratio being 0.93. This value is, however, significantly higher than the experimental results in GaP and GaAs.

Determining Factors for the Product Para/Ortho Ratio and Reaction Rate in the Formation of (Hydroxymethyl)phenols from Phenol and Formaldehyde

Abstract Formations of 2- and 4-(hydroxymethyl)phenols from phenol and formaldehyde in aqueous alkaline solutions were kinetically investigated by the use of HPLC. The para/ortho ratio for the products sigmoidally increased with increasing concentration of sodium hydroxide, whereas the total yield of the (hydroxymethyl)phenols showed a steep maximum at the charged molar ratio unity of sodium hydroxide to phenol. Use of lithium hydroxide and potassium hydroxide, in place of sodium hydroxide, as alkaline catalysts results in almost the same para/ortho ratios. The addition of potassium chloride and magnesium sulfate decreased both the para/ortho ratio and the yield. These results indicate that the reactions proceed via an electrophilic attack of formaldehyde, which is free from the adduct formation with hydroxide ion, at phenolate ion. Electrostatic interactions between the phenoxide oxygen atom of the phenol and the incoming hydroxymethyl residues in the transition state exhibit a predominant role in the determination of the para/ortho ratio.

Thermal diffuse scattering in time-of-flight neutron diffraction

The nature of the thermal diffuse scattering (TDS) from long-wavelength acoustic modes of vibration in a single crystal is examined for time-of-flight neutron diffraction. In the neighbourhood of the Bragg reflections there may be gaps or 'windows' in the energy change of the scattered neutrons, in the wavelengths of both incident and scattered radiation, and in the total time of flight. TDS is forbidden within these windows and rises to a steep maximum at the edges: one maximum is due to phonon emission (Stokes process) and the other to phonon absorption (anti-Stokes). The edges of the windows are determined by the sound velocity in the crystal. The sound velocity is readily derived, without employing energy analysis, by measuring the positions of the edges of the time-of-flight window.

On the design of three-dimensional wind tunnel contractions

A method is given for the calculation of incompressible inviscid flow through non-axisymmetric contracting ducts with rectangular cross-sections. The method is based on a finite difference approximation to Laplace's equation and solved by the method of successive over relaxation. In an attempt to provide practical criteria for the design of such contractions, the flows through a series of contraction shapes were calculated, each shape being based on a pair of matched elliptic arcs. This permitted choice of such parameters as length, local (ie two-dimensional) contraction ratio, position and magnitude of the maximum slope. It was found that reducing the length of the contraction also reduced its effective length, although increasing the effects of overshoot and undershoot. This could be compensated for by designing a contraction with a steep maximum slope which with associated low curvatures at entrance and exit reduced the values of overshoot and undershoot. The axial positions of maximum slope on wall and roof should be the same.The predictions of the numerical method were tested against experiment and, in general, satisfactory comparisons were obtained.

TDS and LEED studies of H 2O adsorption on GaAs(110)

The UHV cleaved (110) face has been exposed to water in the range from 10 L to 2 × 10 4 L. The main TDS peak in H 2O desorption appears at 350 K, independent of coverage. The low desorption energy of 0.7 eV (16 kcal/mol) is reasonable for oxygen atoms bound via the lone pair orbital to As as was earlier derived from UPS measurements. A broad spur between 450 and 600 K may be related to O-Ga bonds. The sticking probability shows values below 10 -4; only near 4.8 × 10 3 L (6 × 10 15 cm -2 s -1 H 2O molecules for 300 s) corresponding to a coverage of about 0.4 monolayes a steep maximum appears. At about one monolayer saturation is observed. Exposures to more than 10 4 L of water quench the intensity of the (10) LEED spot considerably stronger than the intensity of the (11) spot. A comparison of the I( E) curves with existing model calculations suggests that the observed behaviour of the LEED spots is caused by a change in surface structure towards the unrelaxed configuration. The higher sticking coefficient observed near 0.4 monolayers may be connected with this rearrangement of surface atoms.

Regulation of sodium in the shore crabCarcinus maenas, adapted to environments of constant and changing salinities

The activity of Na-K-ATPase was determined in the posterior gills of the shore crabCarcinus maenas during a period following transfer from 35 to 10 ‰ salinity and vice versa at 15 °C. After transfer from high to low salinity, Na-K-ATPase activity increased from 3.2 to 7.0 μmoles Pi mg protein−1 h−1 within a period of 2 to 3 weeks. Transfer of crabs from low to high salinity resulted in reduction of activity from 7.4 to 4.5 μmoles Pi mg protein−1 h−1 within about the same period. The relatively slow response following salinity change indicates that the amounts of Na-K-ATPase in the gills may play a role in hyperionic Na regulation in relatively constant brackish-water environments. Instant responses to salinity result from activation and inhibition of Na-K-ATPase activity by Na. Gill Na-K-ATPase is activated by the Na concentration of the incubation medium to attain a steep maximum at about 75 mM Na, which corresponds to the lowest environmental Na levels tolerated byC. maenas equivalent to a salinity of ca 6 ‰. Activity greatly decreased towards higher Na levels, equivalent to the salinity of normal sea water, at which hyperregulation no longer occurs. Selective addition of either Na or Cl to brackish water of 9 ‰ S resulted in effective hyperregulation of the non-increased ion, and passive distribution between medium and blood of the increased ion. These data indicate that under appropriate conditions the normally coupled transport of Na and Cl may be uncoupled and take place independently of each other.

Postnatal development of some membrane-bound enzymes of rat liver and kidney

1. 1. The development of rat liver acyl-CoA: sn-glycerol-3-phosphate- O-acyltransferase (EC 2.3.1.15) is characterized by an increase and decrease in activity during the neonatal period, followed by a second increase and decrease during the late weaning period. Kidney acyltransferase exhibits a similar peak in activity during the neonatal period before increasing to adult levels of activity during the late weaning period. 2. 2. Nucleosidediphosphatase activity rapidly during the neonatal period and thereafter gradually rises to adult levels in both liver and kidney. The latency of the enzyme increases rapidly after birth and thereafter shows little change with age. The enzyme appears to be more latent in the liver than in the kidney at all ages studied. 3. 3.NADPH-cytochrome c reductase of liver has a single steep maximum and minimum in activity during the neonatal period, before increasing again to adult levels during the late weaning period. The enzume in kidney shows a similar developmental pattern but at much lower levels of specific activity. 4. 4. sn-Glycerol-3-phosphate acyltransferase activity was significantly higher in rough than in smooth membranes throughout the neonatal period of rapid smooth membrane proliferation. This distribution of enzyme activity is unlike that reported by others in phenobarbital-induced smooth membrane proliferation and suggests a major role for rough membranes in phospholipid synthesis during the neonatal period. 5. 5. The qualitative similarity in development in rough and smooth microsomal subfractions for each of these enzymes is in distinct contrast with results previously reported for glucose-6-phosphatase.

Radiosensitivity and recovery of mouse L cells during the cell cycle.

Mouse fibroblasts, subline L-929 F were synchronized by mitotic detachment. The synchronized cell cultures were irradiated with 200 kVp X-rays at different time after mitosis, and age response functions and dose effect curves were determined using the colony test. The cell age in the mitotic cycle was obtained from a computer analysis of flow cytometric DNA histograms. Both intrinsic radiosensitivity 1/D0 and extrapolation number n were found to vary during the cell cycle. The D0 has a maximum value of 176 +/- 1 rad in the middle of G1 phase and minimum of 71 +/- 1 rad at the S/G2 transition, while the extrapolation number is rather constant from the beginning of G1 phase (1.9 +/- 0.1) to the middle of S phase (2.3 +/- 0.1) and reaches a steep maximum of 9.3 +/- 1.1 at S/G2 transition. The values of n in the various phases of cell cycle are compared with the respective values of the recovery factor gamma determined after fractionated irradiation. --Cell survival after a single dose of 616 rad has minima for irradiation at G1/S transition and in early G2 phase; the survival in early G2 being about 40 times smaller than in early G1 phase. Implications for a cell cycle specific therapy are discussed.

15-Hydroxyprostaglandin-Dehydrogenase aus Humanplacenta, l. Isolierung und Charakterisierung

15-Hydroxyprostaglandin dehydrogenase was isolated from human term placenta up to a final purification of 380-fold. A spec. act. of 2000 mU/mg of protein was reached. The preparation was not homogeneous as judged by analytical disc electrophoresis. The enzyme could be stored in the presence of 50% glycerol and 10mM 2-mercaptoethanol without any loss of activity for at least one year. A distinct single protein band stained after discontinuous polyacrylamide gel electrophoresis was shown by enzymatic activity staining to correspond to 15-hydroxyprostaglandin dehydrogenase activity. Thus no evidence for the exitstence of isoenzymes was obtained. The protein in the final preparation steps showed neither alcohol dehydrogenase, NAD reductase, nor NADH oxidase activity, nor enzymatic conversion of prostaglandin or 15-oxoprostaglandin in the absence of NAD and NADH. No spontaneous reactions between NAD and prostaglandin or NADH and 15-oxoprostaglandin were detectable in the absence of the enzyme. Ethanol and glycerol slightly inhibited the reaction. Various buffers (Tris/HC1, potassium phosphate, HEPES, and triethanolamine) and salts (ammonium chloride, ammonium sulfate, potassium chloride, and sodium chloride) had different effects on the reaction rate. The pH profile of the reaction shows a plateau between pH 7.0 and 7.8 and a steep maximum at pH 9.5. A linear Arrhenius plot was obtained for the temperature dependence of the reaction from 20 to 37 degrees C. The molar activation enthalpy of the reaction was calculated to be 13.1 kcal/mole. The molecular weight of 15-hydroxyprostaglandin dehydrogenase was estimated to be 32000 -/+ 3000 by gel filtration on Sephadex G-150 in the presence of 10mM mercaptoethanol.

Magnetic to nonmagnetic transition of cerium impurities in (La, Th) alloys

The initial depression of the superconducting temperature of ( La, Th ) Ce alloys has been measured. It has been found that there is a steep maximum in the initial depression as a function of La concentration in the (La, Th) matrix, This effect is compared with the nonmonotonic behaviour of the critical temperature of La Ce under pressure.

Anharmonic properties of the hexagonal metals, magnesium, zinc and beryllium—II. Thermal expansion

The generalized Gruneisen parameters γ″ = − ∂ log ω ∂ϵ″ and γ′ = − ∂ log ω ∂ϵ′ have been calculated for various normal mode frequencies in magnesium, zinc and beryllium using the model outlined in part I. The temperature dependence of the effective Gruneisen functions \\ ̄ gg ∥(T) and \\ ̄ gg ⊥(T) have been calculated. In magnesium the theoretical curve for \\ ̄ gg ⊥(T) is in good agreement with experiment but the theoretical curve for \\ ̄ gg ∥(T) is about 10 per cent higher than the experimental values over the entire temperature range. In zinc the \\ ̄ gg ∥(T) vs. T curve exhibits a steep maximum at low temperatures. While the shapes of the theoretically calculated lattice Gruneisen functions \\ ̄ gg ∥(T) and \\ ̄ gg ⊥(T) curves are similar to the experimentally observed variation of the total Gruneisen functions, the theoretical values are much higher than the experimental values. The reason for the discrepancy is the extreme sensitivity of the GPs of the low frequency modes corresponding to wave vectors lying on the vertical edge of the Brillouin zone. Perhaps a direct measurement of the pressure dependence of these frequencies in zinc by inelastic scattering of neutrons will provide more reliable values for the anharmonic parameters. The low temperature limit of \\ ̄ gg ∥(T) which depends on the TOE constants of the material does not agree with the value obtained by Barron and Munn in their analysis of the thermal expansion data. Possibly their choice of the electronic Gruneisen parameters is not correct. In beryllium there is no reliable experimental data to make a comparison with the calculated temperature dependence of the lattice Gruneisen functions. The variation of the generalised GPs of the elastic modes with the direction of propagation is illustrated by polar diagrams in the three metals.

Einflu� des Phasenstatus der Vorkulturzellen auf die Ascosporenbildung von Saccharomyces cerevisiae

Cells from three growth phases were examined for their ability to sporulate: cells from a) phase II (first phase of exponential growth with glucose as carbon source), b) phase III (second lag-phase during adaptation to oxidative metabolism), and c) phase IV (second phase of almost exponential growth with ethanol as carbon source). 1. Cells from phase III showed the best sporulation ability because they reached the highest percentage of asci and also of 4-spored asci. 2. Cells of phase II exhibited the highest and those of phase IV the lowest rate of sporulation (Fig. 3). 3. The longer the cells remained in the presporulation medium the more abbreviated was the time in the sporulation culture before the first asci appeared, and this abbreviation was just equal to the time of elongation in the preculture. This clearly demonstrates the different degree of respiratory adaptation. — After transfer to the sporulation medium O2-consumption arose to a steep maximum within the first 10 hours followed by medium values which dropped again rapidly at the onset of ascospore formation (Fig. 4). Only during the time of high and medium O2-consumption there was an increase in dry weight reflecting the assimilation of acetate. In cells of phase II compared with those of phase IV this assimilation of acetate showed the same delay as the onset of sporulation, whereas full capacity of respiration was reached much sooner.

Observation of the Ion Resonance by a rf Probe

An ion resonance that shows a steep maximum in the probe d-c current at the plasma-ion frequency fi = (ne2/ pi M)1/2 is reported. The apparatus for its observation is described. (R.E.U.)

Impurity conduction of cleaned germanium surfaces at low temperatures

The conductivity and Hall effect of cleaned germanium surfaces have been measured in the temperature range between 1.7°K and 300°K. The surface was cleaned by Joule heating at ~ 800–850°C in ultra-high vacuum for ~ 20—30 hr and was then annealed at 650°C for several hours. Results obtained with ~20–40 Ω-cm p-type samples show that the Hall coefficient has a steep maximum at ~ 10–20°K and the resistivity becomes almost flat below this temperature range. This character is similar to that of bulk impurity conduction found by H ung et al., but disappears on exposure to air which causes marked increases in both the Hall coefficient and resistivity at low temperatures. This impurity conduction is attributed to the surface imperfections introduced by the cleaning treatment of the surface. The mobility and concentration of carriers in this surface conduction are estimated.