Glass-transition temperature of water

The glass-transition temperature of water (T(g)) has been calculated by use of the Tammann-Hesse viscosity equation with the viscosity equal to 10(13) poise at T(g). The derived value of T(g),162 +/- 1 degrees K, is significantly higher than previous estimates.     

Superconductivity of metallic aluminum antimonide

The high-pressure metallic phase of aluminunm antimnonide is super conducting [critical temperature T(c) (P approximately 125 kilobars) = 2.8 degrees +/-0.2 degrees K]. This transition temperature is significantly lower than the transition temperature of metallic germanium under an equivalent high pressure. A similar result had been previously found for superconducting indiumantimonide in comparison to tin.     

Radio science with voyager 2 at saturn: atmosphere and ionosphere and the masses of mimas, tethys, and iapetus

Voyager 2 radio occultation measurements of Saturn's atmosphere probed to the 1.2-bar pressure level, where the temperature was 143 +/- 6 K and the lapse rate apparently equaled the dry adiabatic value of 0.85 K per kilometer. The tropopause at both mid-latitude occultation locations (36.5 degrees N and 31 degrees S) was at a pressure level of about 70 millibars and a temperature of approximately 82 K. The stratospheric structures were very similar with the temperature rising to about 140 K at the 1-millibar pressure level. The peak electron concentrations sensed were 1.7 x 10(4) and 0.64 x 10(4) per cubic centimeter in the predawn (31 degrees S) and late afternoon (36.5 degrees N) locations. The topside plasma scale heights were about 1000 kilometers for the late afternoon profile, and 260 kilometers for the lower portions and 1100 kilometers for the upper portions of the topside predawn ionosphere. Radio measurements of the masses of Tethys and Iapetus yield (7.55 +/- 0.90) x 10(20) and (18.8 +/- 1.2) x 10(20) kilograms respectively; the Tethys-Mimas resonance theory then provides a derived mass for Afimas of (0.455 +/- 0.054) x 10(20) kilograms. These values for Tethys and Mimas represent major increases from previously accepted ground-based values, and appear to reverse a suggested trend of increasing satellite density with orbital radius in the Saturnian system. Current results suggest the opposite trend, in which the intermediate-sized satellites of Saturn may represent several classes of objects that differ with respect to the relative amounts of water, ammonia, and methane ices incorporated at different temperatures during formation. The anomalously low density of lapetus might then be explained as resulting from a large hydrocarbon content, and its unusually dark surface markings as another manifestation of this same material.     

The Phase Boundary Between agr- and beta-Mg2SiO4 Determined by in Situ X-ray Observation

The stability of Mg(2)SiO(4), a major constituent in the Earth's mantle, has been investigated experimentally by in situ observation with synchrotron radiation. A cubic-type high-pressure apparatus equipped with sintered diamond anvils has been used over pressures of 11 to 15 gigapascals and temperatures of 800 degrees to 1600 degrees C. The phase stability of alpha-Mg(2)SiO(4) and beta-Mg(2)SiO(4) was determined by taking account of the kinetic behavior of transition. The phase boundary between alpha-Mg(2)SiO(4) and beta-Mg(2)SiO(4) is approximated by the linear expression P = (9.3 +/- 0.1) + (0.0036 +/- 0.0002)T where P is pressure in gigapascals and T is temperature in degrees Celsius.     

Pioneer 11 infrared radiometer experiment: the global heat balance of jupiter

Data obtained by the infrared radiometers on the Pioneer 10 and Pioneer 11 spacecraft, over a large range of emission angles, have indicated an effective temperature for Jupiter of 125 degrees +/- 3 degrees K. The implied ratio of planetary thermal emission to solar energy absorbed is 1.9+/-0.2, a value not significantly different from the earth-based estimate of 2.5+/-0.5.     

樱桃砧木吉赛拉组培快繁生产中玻璃化及污染分析

[目的]解决樱桃砧木吉赛拉组培快繁生产中玻璃化苗发生及污染问题.[方法]通过对培养基中激素、蔗糖、琼脂浓度的调节及培养温度的控制,防止玻璃化苗发生;通过培养基中加入杀菌剂,寻求解决组培苗污染.[结果]培养基中细胞分裂素6 - BA的浓度控制在1 mg/L以下、蔗糖浓度40 g/L、琼脂浓度6 g/L左右、培养温度24℃左右,可有效地预防玻璃化苗的发生;在培养基中加入500～1 000 mg/L多菌灵50;可湿性粉剂,可有效防止污染的发生.[结论]在樱桃砧木吉赛拉5号组培快繁中,细胞分裂素6 - BA浓度、蔗糖浓度、琼脂浓度、培养温度对试管苗产生玻璃苗都有一定的影响,其中,细胞分裂素6 - BA浓度、培养温度的影响更为明显.为了防止污染的发生,培养基中添加多菌灵50;可湿性粉剂效果较好.     

芦荟组织培养中试管苗玻璃化的发生与防止

以美国“翠叶”芦荟（A.barbadensis Mill）为试材,研究芦荟组培苗玻璃化的发生与防止措施,结果表明,密封瓶口,高温,高浓度6-BA,高Ca2^ ,K^ 离子浓度会提高玻璃化率,而高浓度的琼脂（11g/L）,50mg/L根皮苷,强的光照（3000Lx）有利于降低玻璃化率。     

Radio science investigations of the saturn system with voyager 1: preliminary results

Voyager 1 radio occultation measurements of Titan's equatorial atmosphere successfully probed to the surface, which is provisionally placed at a radius of 2570 kilometers. Derived scale heights plus other experimental and theoretical results indicate that molecular nitrogen is the predominant atmospheric constituent. The surface pressure and temperature appear to be about 1.6 bars and 93 K, respectively. The main clouds are probably methane ice, although some condensation of nitrogen cannot be ruled out. Solar abundance arguments suggest and the measurements allow large quantities of surface methane near its triple-point temperature, so that the three phases of methane could play roles in the atmosphere and on the surface of Titan similar to those of water on Earth. Radio occultation measurements of Saturn's atmosphere near 75 degrees south latitude reached a maximum pressure of 1.4 bars, where the temperature is about 156 K. The minimum temperature is about 91 K near the 60-millibar pressure level. The measured part of the polar ionosphere of Saturn has a peak electron concentration of 2.3 x 10(4) per cubic centimeter at an altitude of 2500 kilometers above the 1-bar level in the atmosphere, and a plasma scale height at the top of the ionosphere of 560 kilometers. Attenuation of monochromatic radiation at a wavelength of 3.6 centimeters propagating obliquely through Saturn's rings is consistent with traditional values for the normal optical depth of the rings, but the near-forward scattering of this radiation by the rings indicates effective scattering particles with larger than expected diameters of 10, 8, and 2 meters in the A ring, the outer Cassini division, and the C ring, respectively. Preliminary analysis of the radio tracking data yields new values for the masses of Rhea and Titan of 4.4 +/- 0.3 x 10(-6) and 236.64 +/- 0.08 x 10(-6) times the mass of Saturn. Corresponding values for the mean densities of these objects are 1.33 +/- 0.10 and about 1.89 grams per cubic centimeter. The density of Rhea is consistent with a solar-composition mix of anhydrous rock and volatiles, while Titan is apparently enriched in silicates relative to the solar composition.     

Helium isotope effect in solution in water and seawater

The isotope effect in the solution of helium in water from 0 degrees to 40 degrees C has been determined by microgasometric measurements of the solubilities of pure helium-3 and helium4. At 0 degrees C helium-3 is less soluble than helium-4 in both distilled water and sea-water by 1.2 percent. The observed fractionation factor is 0.988+/-0.002 at 0 degrees C and appears to decrease with increasing temperature at the rate of 0.0001 per degree Centigrade, although the existence of this trend is of limited statistical certainty. The measured isotope effect is in agreement with the ratio of helium-3 to helium-4 in surface ocean water reported by Clarke, Beg, and Craig.     

Synthesis and Equation of State of (Mg,Fe) SiO3 Perovskite to Over 100 Gigapascals

Silicate perovskite of composition (Mg(0.88)Fe(0.12)) SiO(3) has been synthesized in a laser-heated diamond-anvil cell to a pressure of 127 gigapascals at temperatures exceeding 2000 K. The perovskite phase was identified and its unit-cell dimensions measured by in situ x-ray diffraction at elevated pressure and room temperature. An analysis of these data yields the first high-precision equation of state for this mineral, with values of the zero-pressure isothermal bulk modulus and its pressure derivative being K(0T) = 266 +/- 6 gigapascals and K'(0T) = 3.9 +/- 0.4. In addition, the orthorhombic distortion of the silicate-perovskite structure away from ideal cubic symmetry remains constant with pressure: the lattice parameter ratios are b/a = 1.032 +/- 0.002 and c/a = 1.444 +/- 0.006. These results, which prove that silicate perovskite is stable to ultrahigh pressures, demonstrate that perovskite can exist throughout the pressure range of the lower mantle and that it is therefore likely to be the most abundant mineral in Earth.     

Venus: lower atmosphere not measured

The common ranges of pressure and temperature of the atmosphere of Venus measured last October establish the connection between the Soviet Venera 4 altitude scale and the United States Mariner V radial scale. But if the Venera 4 measurements extended to the surface, as claimed, this comparison implies a radius of the planet which is about 25 kilometers greater than the radius deduced from Earth-based radar data. This impasse has been resolved in favor of the smaller value by a new determination of the radius which is more direct than the method used in deriving the radar radius, and which involves concurrent ranging from Earth both to Mariner V near encounter and to the surface of Venus. It is concluded that neither spacecraft reported on atmospheric conditions near the level of the mean surface, but extrapolations of the measurements yield surface values for mid-latitudes of 100 atmospheres pressure (within a factor of 1.5) and 700 degrees K temperature (within 100 degrees ), in distinction to the Soviet values of 19+/-2 atmospheres and 544 degrees +/-10 degrees K. The higher values support radiometric and radar data on temperature and atmospheric absorption. It appears that the Soviet probe was not designed to work through such a thick atmosphere. A particularly simple (times two) ambiguity in the Venera 4 altimeter reading suggests itself, since this would bring all other data into excellent agreement and would explain the reason for the supposition that the probe reached the surface.     

Infrared observations of the saturnian system from voyager 2

During the passage of Voyager 2 through the Saturn system, infrared spectral and radiometric data were obtained for Saturn, Titan, Enceladus, Tethys, Iapetus, and the rings. Combined Voyager 1 and Voyager 2 observations of temperatures in the upper troposphere of Saturn indicate a seasonal asymmetry between the northern and southern hemispheres, with superposed small-scale meridional gradients. Comparison of high spatial resolution data from the two hemispheres poleward of 60 degrees latitude suggests an approximate symmetry in the small-scale structure, consistent with the extension of a symmetric system of zonal jets into the polar regions. Longitudinal variations of 1 to 2 K are observed. Disk- averaged infrared spectra of Titan show little change over the 9-month interval between Voyager encounters. By combining Voyager 2 temperature measurements with ground-based geometric albedo determinations, phase integrals of 0.91 +/- 0.13 and 0.89 +/- 0.09 were derived for Tethys and Enceladus, respectively. The subsolar point temperature of dark material on Iapetus must exceed 110 K. Temperatures (and infrared optical depths) for the A and C rings and for the Cassini division are 69 +/- 1 K (0.40 +/- 0.05), 85 +/- 1 K (0.10 +/- 0.03), and 85 +/- 2 K (0.07 +/- 0.04), respectively.     

Infrared speckle observations of io: an eruption in the loki region

Speckle observations of Jupiter's satellite Io at a wavelength of 5 micrometers during July 1984 resolved the disk and showed emission from a hot spot in the Loki region. The hot spot contributed a flux approximately equal to 60 percent of that from the disk. Images reconstructed by means of the Knox-Thompson algorithm showed the spot moving across the disk as the satellite rotated. It was located at 301 degrees +/- 6 degrees west longitude, 10 degrees +/- 6 degrees north latitude, and had a radiance of (2.96 +/- 0.54) x 10(22) ergs sec(-1) cm(-1) sr(-1)/A where A is the area of the spot. For an assumed temperature of 400 K, the area of the source would be 11,400 square kilometers. An active "lava lake" similar to that seen by Voyager may be the source of the infrared emission.     

Anomalous temperature dependence for a partial vapor pressure

In a limited temperature range the partial pressure of gallium subsulfide (Ga(2)S) above gallium sesquisulfide (Ga(2)S(3)) increases when the temperature is decreased. The anomaly in the partial pressure is caused by changes with temperature in the equilibrium compositions of two solid phases that coexist at 1228 degrees +/- 3 degrees K. At this temperature the solids differ in sulfur content by 0.4 atomic percent sulfur.     

不同培养基配方对防止土人参愈伤组织玻璃化作用的研究

[目的]研究不同培养基配方对防止土人参愈伤组织玻璃化的效果。[方法]以MS+6-BA 2.0 mg/L+NAA 0.5 mg/L+蔗糖30g/L为基础培养基(对照组),将其配方作以下分组调整:①6-BA浓度减半;②添加活性炭(1 g/L);③Ca2+加倍;④NH4+减半;⑤采用2,4-D+KT代替6-BA;⑥联合②③④⑤,比较培养基变化对土人参愈伤组织玻璃化率的影响,并观察土人参愈伤组织悬浮培养细胞形态。[结果]与对照组相比,②～④组玻璃化率无显著差异(P>0.05);⑤组玻璃化率降至25%(P<0.05);⑥组玻璃化率降为0,同时⑥组悬浮细胞密度及活性均高于对照组。[结论]最佳培养基为改良MS(Ca2+浓度加倍,NH4+浓度减半)+2,4-D 2.0 mg/L+NAA 2.0 mg/L+KT 0.5 mg/L+活性炭1.0 g/L+蔗糖30 g/L,可在一定程度上防止土人参愈伤组织玻璃化的发生。     

Thermal stratification in the arctic ocean

Fine scale measurements of the vertical temperature profile in an Arctic water column show the presence of several cascaded isothermal layers. Layers between the depths of 300 anid 350 meters range from 2 to 10 meters in thickness, while the temperature change between adjacent layers is approximately 0.026 degrees C. The individual layers are isothermal to within +/- 0.001 degrees C.     

Composition and structure of the martian atmosphere: preliminary results from viking 1

Results from the aeroshell-mounted neutral mass spectrometer on Viking I indicate that the upper atmosphere of Mars is composed mainly of CO(2) with trace quantities of N(2), Ar, O, O(2), and CO. The mixing ratios by volume relative to CO(2) for N(2), Ar, and O(2) are about 0.06, 0.015, and 0.003, respectively, at an altitude near 135 kilometers. Molecular oxygen (O(2)(+)) is a major component of the ionosphere according to results from the retarding potential analyzer. The atmosphere between 140 and 200 kilometers has an average temperature of about 180 degrees +/- 20 degrees K. Atmospheric pressure at the landing site for Viking 1 was 7.3 millibars at an air temperature of 241 degrees K. The descent data are consistent with the view that CO(2) should be the major constituent of the lower martian atmosphere.     

洋桔梗组培苗玻璃化原因及恢复的研究

为了找出能够克服或降低洋桔梗组培苗玻璃化的最适培养条件,以YELLOW和PINK2个洋桔梗品种为试材,研究MS培养基中添加的激素、蔗糖、活性炭及温度对洋桔梗组培苗玻璃化的产生和恢复的影响.结果表明:品种、6-BA、NAA对洋桔梗玻璃化芽的产生均有影响,玻璃化率随6-BA及NAA浓度的增大而升高;适宜浓度的蔗糖对洋桔梗玻璃化芽的恢复有促进作用,但添加0.5 g·L~(-1)的活性炭及15 ℃的低温培养没有明显地促进作用.     

Tunneling Spectroscopy of M3C60 Superconductors: The Energy Gap, Strong Coupling, and Superconductivity

Tunneling spectroscopy has been used to characterize the magnitude and temperature dependence of the superconducting energy gap (triangle up) for K(3)C(60) and Rb(3)C(60). At low temperature the reduced energy gap, 2triangle upkappaT(c) (where T(c) is the transition temperature) has a value of 5.3 +/- 0.2 and 5.2 +/- 0.3 for K(3)C(60) and Rb(3)C(60), respectively. The magnitude of the reduced gap for these materials is significantly larger than the value of 3.53 predicted by Bardeen-Cooper-Schrieffer theory. Hence, these results show that the pair-coupling interaction is strong in the M(3)C(60) superconductors. In addition, measurements of triangle up(T) for both K(3)C(60) and Rb(3)C(60) exhibit a similar mean-field temperature dependence. The characterization of triangle up and triangle up(T) for K(3)C(60) and Rb(3)C(60) provides essential constraints for theories evolving to describe superconductivity in the M(3)C(60) materials.     

水肥耦合对楸树苗木生长和养分状况的影响

目的探究不同水肥条件下楸树苗木生长及养分状况,确定楸树苗木合理水肥管理措施。方法本文以楸树幼苗为试验材料,采用双因素完全随机试验,设置3个水分梯度(30%饱和持水量(FWC)、50%FWC、70%FWC),和4个施肥量(T1(氮0g,磷0g,钾0g)、T2(氮2g,磷1g,钾1.5g)、T3(氮4g,磷2g,钾3g)、T4(氮6g,磷3g,钾4.5g)),通过盆栽试验研究了不同水肥处理对楸树苗木生理生长的影响,并探讨了楸树苗木生长及养分吸收的关系。结果水肥耦合对楸树苗木的形态指标交互作用不显著,苗高、地径、生物量均随水分梯度的增加而降低,在水分梯度为30%FWC时最好;随施肥量的增加呈先增加后降低,均在T3处理达到峰值。苗木养分在T3处理时达到奢养状态,此时苗木的苗高、地径、生物量及养分含量最高,再增加施肥会对苗木产生毒害作用,即苗木养分质量分数还在增加但形态指标和养分含量已开始降低。水肥耦合对楸树苗木养分质量分数和养分含量有一定的交互作用,其养分含量均随施肥量的增加而增加,在T3处理处达到最大;在水分含量为30%FWC时,施肥对楸树苗木有较好的促进作用,T3、30%FWC处理更有利用苗木养分的吸收和利用。结论水分梯度和施肥量对苗木生长和养分状况的作用证实,水肥耦合对苗木的质量有一定的提升,30%的饱和持水量和T3处理(氮4g,磷2g,钾3g)结合对楸树苗木育苗效果最好。