两种葡萄贮藏期间能量亏损与品质劣变的比较

以"维多利亚"和"红地球"葡萄为材料,通过钙联合涂膜处理,从果实感官品质、果肉组织内在品质、能量水平和果肉组织抗氧化物质含量的角度探讨了0~40 d贮藏期内葡萄组织细胞能量亏损与衰老劣变的变化情况,并对比分析了2个葡萄品种间的差异。结果表明:"红地球"葡萄的腐烂率、膜透性和丙二醛含量低于"维多利亚",但能量水平和抗氧化物花色苷、类黄酮、单宁和总酚含量高于"维多利亚"。相关性分析结果表明:ATP与硬度正相关(R=0.976,P0.01),与膜透性和丙二醛负相关(R=-0.855,-0.859,P0.01),内源抗氧化物质与丙二醛显著负相关(R=-0.771,-0.764,-0.773,-0.708,P0.05)。这表明能量水平和内源性抗氧化物含量对果实衰老劣变有直接影响,"红地球"比"维多利亚"耐贮藏。     

Voyager radio science observations of neptune and triton

The Voyager 2 encounter with the Neptune system included radio science investigations of the masses and densities of Neptune and Triton, the low-order gravitational harmonics of Neptune, the vertical structures of the atmospheres and ionospheres of Neptune and Triton, the composition of the atmosphere of Neptune, and characteristics of ring material. Demanding experimental requirements were met successfully, and study of the large store of collected data has begun. The initial search of the data revealed no detectable effects of ring material with optical depth tau [unknown] 0.01. Preliminary representative results include the following: 1.0243 x 10(26) and 2.141 x 10(22) kilograms for the masses of Neptune and Triton; 1640 and 2054 kilograms per cubic meter for their respective densities; 1355 +/- 7 kilometers, provisionally, for the radius of Triton; and J(2) = 3411 +/- 10(x 10(-6)) and J(4) = -26(+12)(-20)(x10(-6)) for Neptune's gravity field (J>(2) and J(4) are harmonic coefficients of the gravity field). The equatorial and polar radii of Neptune are 24,764 +/- 20 and 24,340 +/- 30 kllometers, respectively, at the 10(5)-pascal (1 bar) pressure level. Neptune's atmosphere was probed to a pressure level of about 5 x 10(5) pascals, and effects of a methane cloud region and probable ammonia absorption below the cloud are evident in the data. Results for the mixing ratios of helium and ammonia are still being investigated; the methane abundance below the clouds is at least 1 percent by volume. Derived temperature-pressure profiles to 1.2 x 10(5) pascals and 78 kelvins (K) show a lapse rate corresponding to "frozen" equilibrium of the para- and ortho-hydrogen states. Neptune's ionosphere exhibits an extended topside at a temperature of 950 +/- 160 K if H(+) is the dominant ion, and narrow ionization layers of the type previously seen at the other three giant planets. Triton has a dense ionosphere with a peak electron concentration of 46 x 10(9) per cubic meter at an altitude of 340 kilometers measured during occultation egress. Its topside plasma temperature is about 80 +/- 16 K if N(2)(+) is the principal ion. The tenuous neutral atmosphere of Triton produced distinct signatures in the occultation data; however, the accuracy of the measurements is limited by uncertainties in the frequency of the spacecraft reference oscillator. Preliminary values for the surface pressure of 1.6 +/- 0.3 pascals and an equivalent isothermal temperature of 48 +/- 5 K are suggested, on the assumption that molecular nitrogen dominates the atmosphere. The radio data may be showing the effects of a thermal inversion near the surface; this and other evidence imply that the Triton atmosphere is controlled by vapor-pressure equilibrium with surface ices, at a temperature of 38 K and a methane mixing ratio of about 10(-4).     

Erratum

In the report "Iron photoreduction and oxidation in an acidic mountain stream" by D. M. McKnight et al. (29 Apr., p. 637), reference 17 [E. L. Madsen, M. D. Morgan, R. E. Good, Limnol. Oceanogr. 31, 382 (1986)] was cited ( p. 638) as indicating "that biological processes are not responsible for light-induced Fe(II) production." This possibility was not addressed by Madsen et al., nor did Madsen et al. use both poisoned and natural streamwater-sediment mixtures to distinguish between biotic and abiotic contributions to iron reduction. In table 1 of the same report, the values in columns two and three were incorrect. They should have been, for sodium, calcium and magnesium, respectively, 2.7 +/- 0.34 mg liter(-1)', 13.0 +/- 0.73 mg liter(-1), and 4.3 +/- 0.24 mg liter(-1).     

Resonant tunneling in the quantum Hall regime: measurement of fractional charge

In experiments on resonant tunneling through a "quantum antidot" (a potential hill) in the quantum Hall (QH) regime, periodic conductance peaks were observed as a function of both magnetic field and back gate voltage. A combination of the two periods constitutes a measurement of the charge of the tunneling particles and implies that charge deficiency on the antidot is quantized in units of the charge of quasi-particles of the surrounding QH condensate. The experimentally determined value of the electron charge e is 1.57 x 10(-19) coulomb = (0.98 +/- 0.03) e for the states v = 1 and v = 2 of the integer QH effect, and the quasi-particle charge is 5.20 x 10(-20) coulomb = (0.325 +/- 0.01)e for the state v = (1/3) of the fractional QH effect.     

Pressure measurement made by the utilization of ruby sharp-line luminescence

A rapid, convenient technique for precision pressure measurement in the diamond-anvil high-pressure cell, which makes use of the sharp-line (R-line) luminescence of ruby, has been developed. The observed shift is -0.77 +/-0.03 reciprocal centimeters per kilobar for R(1) and -0.84+/- 0.03 reciprocal centimeters per kilobar for R(2) to lower energy and is approximately linear in the range studied (to 22 kilobars). Line-broadening has been observed in some instances and has been tentatively identified with nonhydrostatic conditions surrounding the ruby sample.     

行距对晚播冬小麦群体物质积累和水分利用的影响

为研究行距对晚播冬小麦群体物质积累、水分利用的影响,设置行距为12、20、30cm 3个处理,分析不同行距处理的群体物质积累、叶面积指数、水分消耗参数、产量和水分利用效率。结果表明,在晚播限水灌溉条件下,适当缩小行距(12cm)可以增加冬小麦群体叶面积指数,提高群体物质积累和花后物质积累比例;与30cm行距相比,12cm行距能充分利用40~120cm土体内的土壤水分,显著提高产量和水分利用效率(19.8~20.4kg/(hm2·mm))。适当缩小行距至12cm可能是提高晚播冬小麦产量和水分利用效率的有效措施。     

Vitrification temperature of water

The vitrification temperature (T(g)) of water is an elusive quantity because of the great difficulty in supercooling water sufficiently without initiating its crystallization. Water depresses the vitrification temperature of glycerol (184 degrees K) monotonously, and this property has been used for derivation of an estimate of its T(g). The result, 127 degrees +/- 4 degrees K (-146 degrees +/- 4 degrees C), is the temperature below which water presumably exists as a brittle, glassy substance.     

First occurrence of the garnet-ilmenite transition in silicates

Pyrope garnet (Mg(3)Al(2)Si(3)O(12)) has been found to transform to an ilmenite-type phase at a loading pressure between 240 and 250 kilobars and at about 1000 degrees to 1400 degrees C in a diamond-anvil press coupled with laser heating. The lattice parameters for the ilmenite-type phase of (Mg(.75) Al(.25))(Si(.75) Al(.25))O(3) are a(0) = 4.755 +/- 0.002 and c(0) = 13.360 +/- 0.005 angstroms. The zero-pressure volume change associated with the garnet-ilmenite transition is calculated to be -7.1 percent. This result verifies the prediction that pyrope garnet would transform to the ilmenite structure at high pressure first suggested in 1962 by Clark et al. and Ringwood.     

凡纳滨对虾在半集约化土池养殖模式下的生长特性分析

对虾在不同的环境条件和养殖模式下具有不同的生长特性,这是进行对虾高效养殖管理的重要依据之一。为探明半集约化土池养殖模式下凡纳滨对虾(Litopenaeus vannamei)的生长特性,2009年5～8月,在广东省电白县的滩涂土池半集约化养殖区,对两个半集约化养殖土池(P1、P2)的凡纳滨对虾的生长参数(全长、体长和体重)进行了养殖全过程的采样测量和数据分析。结果表明:(1)两个土池养殖的凡纳滨对虾的体长(L)与体重(W)均呈显著的幂函数关系,分别为(P1)W=0.016 L2.8935(R2=0.989,P<0.01)、(P2)W=0.0127 L3.0292(R2=0.9911,P<0.01);其生长拐点分别出现在第124 d和128 d;(2)对虾全长(QL)和体长呈明显的线性关系,分别为(P1)QL=0.8319 L+0.2577(R2=0.9997)、(P2)QL=0.8679 L-0.0434(R2=0.9977);(3)体长、体重的von Bertallanffy生长方程分别为(P1)Lt=17.6955(1-e-0.0095(t-12.2421))、Wt=65.2846(1-e-0.0095(t-12.2421))2.8935,(P2)Lt=16.8567(1-e-0.0104(t-21.1781))、Wt=66.0607(1-e-0.0104(t-21.1781))3.0292。     

妊娠后期不同营养水平对蒙古绵羊胎儿生长发育的影响

 【目的】研究妊娠后期不同营养水平限制饲养母羊对其胎儿生长发育的影响。【方法】选择经同期发情且同期受孕, 在妊娠90 d时健康的蒙古绵羊100只，ME分为0.175MJ•kg-1w0.75•d-1（RG1）、0.33 MJ•kg-1w0.75•d-1（RG2）以及自由采食组(CG)3个营养水平处理组，进行不同营养水平限制饲养。【结果】妊娠后期不同营养水平限饲母羊，严重限制了RG2（P＜0.05）、RG1（P＜0.01）两低营养组羔羊平均初生重及胎儿期平均日增重；限制了RG1组初生羔羊体长（P＜0.01）、胸围（P＜0.01）、肺脏（P＜0.01）、脾脏（P＜0.01）、心脏（P＜0.05）、肝脏（P＜0.05）及皱胃重（P＜0.01）。RG2组的肺脏（P＜0.05）、脾脏重（P＜0.01）表现出与对照组（CG）明显的差异，其它组织器官重尽管都不同程度的表现出降低的趋势，但与对照组差异不显著（P＞0.05）。各组织器官重占体重百分比，两限制组脾脏仍比对照组显著低（P＜0.01）。脑占体重的比例，对照组显著低于RG1组（P＜0.01）。【结论】妊娠后期不同营养水平限制饲养母羊显著影响了胎儿生长及器官发育，而且随着营养水平的降低，受限制的程度也逐步加深。     

Garnet-like structures of high-pressure cadmium germanate and calcium germanate

Crystals of CdGeO(3) grown at a pressure of 65 kilobars are tetragonal and have an ordered, garnet-like crystal structure with cadmium occupying the dodecahedral and octahedral sites, and germanium the octahedral and tetrahedral sites. The crystal structure (a = 12.406 +/- 1 angstroms, c = 12.256 +/- 1 angstroms, and space group 14,/a) has been refined by least-squares analysis to an R (discrepancy index) of 0.073. Two high-pressure phases of CaGeO(3) were synthesized, one isotypic with tetragonal CdGeO(3) (a = 12.514 +/- 3 angstroms, c = 12.358 +/- 3 angstroms), and the other isotypic with perovskite.     

Sodium and potassium activities in normal and "sodium-rich" frog skeletal muscle

In frog sartorius muscles immersed for 2 hours at 26 degrees C in normal Ringer solution, the intrafiber potassium concentration, C(K)(in millimoles per liter), was 123 +/- 2 (mean value plus or minus standard error), and the potassium activity, a(K) (in millimoles per liter), was 90 +/- 1.0. The corresponding sodium concentration and activity were 20 +/- 1 and 6.5 +/- 0.4, respectively. After overnight immersion in K+-free Ringer solution the values were: CK, 97 +/- 2; aK, 81.5 +/- 1.6; CNa, 47 +/- 2; and aNa, 11.2 +/- 0.6. The changes in aK and aNa during storage were not consistent with an exchange between predominantly "free" fiber K+ and external Na+. These results suggest that the Na+ taken up during overnight immersion largely replaced adsorbed or sequestered K+ in the fibers.     

Radiation effects in free-ranging pocket mice, Perognathus parvus, during the breeding season

Captive and free-ranging Great Basin pocket mice, Perognathus parvus, were exposed to ionizing radiation during the breeding season, April-June, in 1971. The values for the median lethal dose (LD(50)) at 30 days plus or minus the standard deviation were 880 +/- 14 rads and 780 +/- 27 rads, respectively, and the slopes of the survivorship curves were significantly different. These differences suggested that there was a synergism between radiation-induced and environmental sources of mortality, since the field data were corrected for natural mortality (5 percent) in the controls.     

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.     

灰霉病菌抗感腐霉利菌株形态和生理生化特性的比较

经紫外线照射、亚硝基胍处理和药剂诱导,分别从灰霉病菌野生敏感菌株XY6-1S获得高抗腐霉利菌株XY6-1R052、XY6-1R140和XY6-1R202,其EC_(50)>100,μg·mL~(-1)、MIC>1 000μg·mL~(-1).在1～4μg·mL~(-1)药剂浓度下,敏感菌株菌丝呈现不同程度的形态异常,甚至细胞壁破损,而抗性菌株菌丝未有明显改变.在含20μg·L~(-1)以上蔗糖或1.25 g·L~(-1)以上NaCl培养基上,抗药菌株菌丝生长明显差于敏感菌株,表明前者比后者对高渗透压敏感.另外,抗药菌株菌丝相对电导率显著高于敏感菌株,显示抗药菌株细胞膜透性明显改变,因而导致电介质渗漏.在含药培养液中,敏感菌株菌丝甘油含量急剧上升,提高904.63%,而抗药菌株菌丝甘油含量仅增加20.54%～44.00%,因此对于高渗环境,敏感菌株具有较好的调节能力.     

Hot plasma environment at jupiter: voyager 2 results

Measurements of the hot (electron and ion energies >/=20 and >/= 28 kiloelectron volts, respectively) plasma environment at Jupiter by the low-energy charged particle (LECP) instrument on Voyager 2 have revealed several new and unusual aspects of the Jovian magnetosphere. The magnetosphere is populated from its outer edge into a distance of at least approximately 30 Jupiter radii (R(J)) by a hot (3 x 10(8) to 5 x 10(8) K) multicomponent plasma consisting primarily of hydrogen, oxygen, and sulfur ions. Outside approximately 30 R(J) the hot plasma exhibits ion densities from approximately 10(-1) to approximately 10(-6) per cubic centimeter and energy densities from approximately 10(-8) to 10(-13) erg per cubic centimeter, suggesting a high beta plasma throughout the region. The plasma is flowing in the corotation direction to the edge of the magnetosphere on the dayside, where it is confined by solar wind pressure, and to a distance of approximately 140 to 160 R(J) on the nightside at approximately 0300 local time. Beyond approximately 150 R(J) the hot plasma flow changes into a "magnetospheric wind" blowing away from Jupiter at an angle of approximately 20 degrees west of the sun-Jupiter line, characterized by a temperature of approximately 3 x 10(8) K (26 kiloelectron volts), velocities ranging from approximately 300 to > 1000 kilometers per second, and composition similar to that observed in the inner magnetosphere. The radial profiles of the ratios of oxygen to helium and sulfur to helium (相似文献   

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.     

Mariner 9 celestial mechanics experiment: gravity field and pole direction of Mars

Analysis of the Mariner 9 radio-tracking data shows that the Martian gravity field is rougher than that of Earth or the moon, and that the accepted direction of Mars's rotation axis is in error by about 0.5 degrees . The new value for the pole direction for the epoch 1971.9, referred to the mean equatorial system of 1950.0, is right ascension alpha= 317.3 degrees +/- 0.3 degrees , declination delta = 52.6 degrees +/- 0.2 degrees . The values found for the coefficients of the low-order harmonics of Mars's gravity field are as follows: J(2)=(1.96+/-0.01)x10(-3), referred to an equatorial radius of 3394 kilometers; C(22) = -(5 +/- 1) x 10(-5); and S(22) = (3 +/- 1) x 10(-5). The value for J(2) is in excellent agreement with the result from, Wilkins' analysis of the observations of Phobos. The other two coefficients imply a value of (2.5 +/- 0.5) x 10(-4) for the fractional difference in the principal equatorial moments of inertia; the axis of the minimum moment passes near 105 degrees W.     

Detection of first-order liquid/liquid phase transitions in yttrium oxide-aluminum oxide melts

We combine small-angle x-ray scattering (SAXS) and wide-angle x-ray scattering (WAXS) with aerodynamic levitation techniques to study in situ phase transitions in the liquid state under contactless conditions. At very high temperatures, yttria-alumina melts show a first-order transition, previously inferred from phase separation in quenched glasses. We show how the transition coincides with a narrow and reversible maximum in SAXS indicative of liquid unmixing on the nanoscale, combined with an abrupt realignment in WAXS features related to reversible shifts in polyhedral packing on the atomic scale. We also observed a rotary action in the suspended supercooled drop driven by repetitive transitions (a polyamorphic rotor) from which the reversible changes in molar volume (1.2 +/- 0.2 cubic centimeters) and entropy (19 +/- 4 joules mole(-1) kelvin(-1)) can be estimated.