Effect of age and breeding season on the developmental capacity of oocytes from unstimulated and follicle-stimulating hormone-stimulated rhesus monkeys

Effects of age and season on the developmental capacity of oocytes from unstimulated and FSH-stimulated rhesus monkeys were examined, Immature cumulus-oocyte complexes were matured in vitro in modified CMRL-1066 medium containing 20% bovine calf serum and

Effects of rhFSH regimen and time interval on ovarian responses to repeated stimulation cycles in rhesus monkeys during a physiologic breeding season

We studied the effects of repeated stimulation by recombinant human FSH (rhFSH) at various time intervals during a physiologic breeding season in rhesus monkeys. Ovarian recovery and responses were assessed by ultrasonography, serum steroid concentrations

Diurnal time budget of the Black-necked Crane during the breeding season

From 26 March to 2 August 2003, both the time budget and the diurnal rhythm of behavior of breeding Black-necked Cranes (Grus nigricollis) were studied at Ruoergai Wetlands National Natural Reserve, Sichuan Province, China. The breeding season was divided

Alternative cold response modes in Chlorella (Chlorophyta, Trebouxiophyceae) from Antarctica

Chlorella was known to show enhanced antifreeze capability after cold hardening. We isolated Chlorella strains NJ-7 and NJ-18, which display alternative cold response modes from rock surfaces in Antarctica. On the basis of 18S ribosomal (rRNA) sequences, NJ-7 is an Antarctic type of Chlorella vulgaris; NJ-18 is also a 'true' Chlorella species but differs from any previously reported species in structure. NJ-7 partially retained the enhancing effects of low temperature cultivation on freeze tolerance, which correlates with an increase of C18:3-fatty acid content and up-regulation of two antifreeze protein genes. NJ-18, however, showed stable freeze tolerance regardless of the precultivation temperature. We propose that cold response modes vary widely in Chlorella and that the adaptation of C. vulgaris to Antarctica may serve as a model system for the evolution of antifreeze mechanisms in a single species of photosynthetic microorganism.

Field emission enhancement by the quantum structure in an ultrathin multilayer planar cold cathode

Field electron emission (FE) from an ultrathin multilayer planar cold cathode (UMPC) including a quantum well structure has been both experimentally and theoretically investigated. We found that by tuning the energy levels of UMPC, the FE characteristic can be evidently improved, which is unexplained by conventional FE mechanism. FE emission mechanism, dependent on the quantum structure effect, which supplies a favorable location of electron emission and enhances tunneling ability, has been presented to expound the notable amelioration. An approximate formula, brought forward, can predict the quantum FE enhancement, in which the theoretical prediction is close to the experimental result. (C) 2008 American Institute of Physics.

Amorphous silicon nanoparticles in compound films grown on cold substrates for high-efficiency photoluminescence

Silicon nanoparticles have been fabricated in both oxide and nitride matrices by using plasma-enhanced chemical vapour deposition, for which a low substrate temperature down to 50 degreesC turns out to be most favourable. High-rate deposition onto such a cold substrate results in the formation of nanoscaled silicon particles, which have revealed an amorphous nature under transmission electron microscope (TEM) examination. The particle size can be readily controlled below 3.0 nm, and the number density amounts to over 10(12) cm(-2), as calculated from the TEM micrographs. Strong photoluminescence in the whole visible light range has been observed in the as-deposited Si-in-SiOx and Si-in-SiNx thin films. Without altering the size or structure of the particles, a post-annealing at 300 degreesC for 2 min raised the photoluminescence efficiency to a level comparable to the achievements with nanocrystalline Si-in-SiO2 samples prepared at high temperature. This low-temperature procedure for fabricating light-emitting silicon structures opens up the possibility of manufacturing integrated silicon-based optoelectronics.

Growth of SiGe Films by Cold-wall UHV/CVD Using GeH_4 and Si_2H_6

国家自然科学基金,国家863计划

Splitting the Fast and Slow Motions in Molecular Dynamics Simulations Based on the Change of Cold Potential Well Bottom

The atomic motion is coupled by the fast and slow components due to the high frequency vibration of atoms and the low frequency deformation of atomic lattice, respectively. A two-step approximate method was presented to determine the atomic slow motion. The first step is based on the change of the location of the cold potential well bottom and the second step is based on the average of the appropriate slow velocities of the surrounding atoms. The simple tensions of one-dimensional atoms and two-dimensional atoms were performed with the full molecular dynamics simulations. The conjugate gradient method was employed to determine the corresponding location of cold potential well bottom. Results show that our two-step approximate method is appropriate to determine the atomic slow motion under the low strain rate loading. This splitting method may be helpful to develop more efficient molecular modeling methods and simulations pertinent to realistic loading conditions of materials.

岷江干旱河谷三种蔷薇植物繁殖更新研究

繁殖更新是植物生活史的重要阶段，在退化生态系统中，植物繁殖更新能力往往较差，是植被恢复的限制环节，因而也成为恢复研究重点和核心。本研究选择岷江干旱河谷广泛分布的三种蔷薇：多苞蔷薇（R. multibracteata）、黄蔷薇（R. hugonis）和川滇蔷薇（R. soulieana）为研究对象，通过野外调查，在查明其生长、繁殖更新状况的基础上，采用控制和模拟实验，对种子和幼苗阶段进行了深入研究，综合分析更新潜力，并提出相对应的促进更新和植被恢复措施。主要结论如下： 1）三种蔷薇在岷江干旱河谷广泛分布，生长和繁殖状况良好，结实量大。各生长指标：株高、基径和冠幅，繁殖指标：结实数量、重量和单果重量都具有显著的空间差异性。基径对多苞蔷薇结实量影响最大；而冠幅对黄蔷薇结实量影响最大。海拔和纬度是对蔷薇生长和繁殖影响最大的环境因素，随着海拔和纬度的升高，植株生长更高大，结实量增加；坡度和坡向对其生长和繁殖也有一定影响，随着坡度 和坡向增加，蔷薇生长和结实受到抑制。 2）三种蔷薇在岷江干旱河谷更新现状不佳, 但更新潜力大。活力种子比率低，动物取食以及两年生幼苗的大量死亡是蔷薇更新的主要限制因素。多苞蔷薇和黄蔷薇的结实率低，川滇蔷薇较高。三种蔷薇种子产量大，但种子质量较差，更新具有充足的种源。三种蔷薇都能形成持久种子库，种子库中种子总量大，但有效种子少，黄蔷薇被动物啃食的比例很高，多苞蔷薇和川滇蔷薇也有一部分种子受到动物破坏。三种蔷薇幼苗库组成特征表现为，当年生幼苗所占比例很高，年龄较大幼苗所占比例小。 3）三种蔷薇都具有不同程度休眠，未经处理种子的发芽率极低。黄蔷薇休眠程度最深，为深度生理休眠；多苞蔷薇为中度生理休眠；川滇蔷薇为非深度生理休眠。三种蔷薇种子在形态上发育成熟，种皮具有透水性。蔷薇果果肉和瘦果中含有抑制物质，其浸泡液抑制了油菜种子萌发，果肉抑制作用更强，果肉和瘦果浸泡液的抑制程度分别为：川滇蔷薇>黄蔷薇>多苞蔷薇。切割和硫酸腐蚀提高了川滇蔷薇种子的发芽能力，而对多苞蔷薇和黄蔷薇没有影响。完全去除瘦果果皮和种皮提高了多苞蔷薇种子发芽率，但对黄蔷薇没有影响。赤霉素和烟水对蔷薇种子萌发没有促进作用。三种蔷薇打破休眠所需低温层积时间分别为：黄蔷薇>多苞蔷薇>川滇蔷薇。对于多苞蔷薇和川滇蔷薇，层积前对种子进行硫酸腐蚀或暖温层积能缩短低温层积时间，提高发芽率。对于多苞蔷薇，变温层积中暖温层积和低温层积具有一定的负补性，即延长暖温层积可以缩短种子萌发对低温层积的需要。 4）多苞蔷薇种子形态特征和种子休眠与萌发在不同海拔梯度间存在较大差异。种子采集时间、采集季节和干藏影响多苞蔷薇和川滇蔷薇的种子休眠。多苞蔷薇果实大小、种子大小和千粒重、种皮厚度随海拔升高而增加，而种子饱满率和活力随海拔升高而降低，种子休眠程度也随海拔升高而增加。种皮厚度与种子大小、千粒重成正相关关系，硫酸腐蚀后的种子经过不同时间的低温层积后，种子发芽率与种皮厚度、种子大小、千粒重、海拔成正相关关系。2006 年采集川滇蔷薇和多苞蔷薇种子休眠程度较2005 年低。种子休眠随种子年龄增加而减弱。高温和干旱能减轻多苞蔷薇和川滇蔷薇种子休眠。 5）三种蔷薇的生长和生物量积累在干旱胁迫条件下受到抑制，而生物量分配、叶片形态特征和水分利用特征等都发生了变化。三种蔷薇的根、茎、叶各器官生物量以及总生物量等在干旱胁迫下明显减小，叶片脱落数量增加。在干旱胁迫条件下，较多的生物量分配到地下部分，从而这使R/S 明显增加。比叶面积（SLA）和冠层面积比（LAR）对干旱胁迫的反应不敏感，仅有部分物种在干旱胁迫条件下发生了变化，并且其变化特点在不同年龄幼苗之间有一定差异。干旱胁迫对WUE 的影响在不同物种间存在差异。多苞蔷薇和黄蔷薇的WUE 随着干旱胁迫的增加而增大， 而川滇蔷薇的WUE 则随干旱胁迫增加而减小。在干旱胁迫条件下，多苞蔷薇和黄蔷薇叶片脱落量和生物量减小幅度较川滇蔷薇大，表明其抗旱能力较强。在干旱胁迫条件，三种蔷薇两年生幼苗的生物量减小幅度较当年生幼苗小，表明两年生幼苗的抗旱能力更强。 6）两种植被恢复措施中，幼苗移栽比播种具有更好的植被恢复效果。播种后，蔷薇种子的发芽率较高，但出苗率都很低，即使出苗，幼苗也几乎在一月内全部死亡。 三种微生境条件下（灌木、半灌木和裸地），种子出苗和幼苗成活没有差异。移栽幼苗总体死亡率都比较低，小于20％。特别是两年生幼苗死亡率更低，小于2％。移栽后的幼苗生长状况良好，在整个生长季中，各生长指标不断增加。生境对幼苗的存活率没有显著影响，但对于幼苗的生长和生物量积累有一定影响，裸地更有利于幼苗生长和生物量积累。与当年生幼苗相比，两年生幼苗具有更高的成活率。总之，三种蔷薇在干旱河谷分布广泛、生长繁殖状况良好，结实量大，具有丰富种源，繁殖更新潜力大，但繁殖更新状况不佳；种子散布后动物对种子的取食、种子的深度休眠过程、种子出苗以及当年生幼苗的存活和定居是更新的主要限制环节。水分是影响结实、种子休眠解除和萌发，幼苗存活和定居的最主要的限制因素。在植被恢复中，应在种子成熟季节大量采集种子，在室内打破休眠后进行人工播种，培育两年生幼苗，通过幼苗移栽方式进行植被恢复。川滇蔷薇应栽种在相对湿润的过渡区，而多苞蔷薇和黄蔷薇可以应用于核心区植被恢复。 Regeneration is an important phase in plant life cycle. It has been a key component of ecological restoration in degradation ecosystem in which plants commonly has poor regeneration. In this paper, we investigated the natural growth, propagation and regeneration status of native three rose species, Rosa multibracteata, R. hugonis and R. soulieana, and analysis the limitation in seed germination and seedling establishment stages. Advice on facilitating the use of these plants in restoration based on the results has been proposed. The results were as follows: 1) Three rose plants widely distributed in the dry valley of the Minjiang River, and made a good performance in growth and propagation. There were significant spatial differences in each growth parameter, such as ramet height, basal diameter, crown diameter and propagation parameters including hip number of a clump, hip mass of a clump and a hip mass. Basa diameter was the most important growth parameter influencing fruit number for R. multibracteata and crown diameter was for R. hugoni. Altitude and latitude had the greatest effect on the growth and propagation of rose plants among environmental conditions. Each parameter of growth and propagation increased with the increase of altitude and latitude. In addition, the increase of slope and aspect limited the growth and propagation. 2) Three rose plants had poor natural regeneration, but great regeneration potential. Low seed viability, predation and higher mortality of current year old seedlings were the limitation in regeneration. R. multibracteata and R. hugonis had higher fruiting rates than R. souliean. All three plants produced a great number of seeds, while their viability was poor. Three rose plants had persistent seed banks, with high total seed number but very low viable seed density. Predation was most severe in R. hugonis, and it also existed to some degree in R. multibracteata and R. soulieana. The seedling age-structure was characteristic of current-year seedlings predominating and few older seedlings were observed. 3) Three rose seeds were dormant and untreated seeds germinated with very low germination percentages. The rose seeds had morphological mature embryos, and achenes were permeable. Some inhabit substances existed in hips and achenes for the extracts of hips and achenes inhibited germination of Brassica campestris. The inhibition effect of the extracts of three rose hip and achenes was R. soulieana>R. hugonis>R. multibracteata. Mechanical and H2SO4 scarification increased R. soulieana germination but had no effect on germination of R. hugonis and R. multibracteata seeds. Full removal of pericarp and testa improved the germination of R. multibracteata but did not affect R. hugonis germination. GA3 and smoke water had no positive effect on rose seed germination. The periods of cold stratification required to released seed dormancy was R. hugonis > R. soulieana >R. multibracteata. H2SO4 scarification and warm stratification shortened cold stratification to release dormancy for R. soulieana and R. multibracteata. Warm stratification had complementary effect for cold stratification, i.e. the longer warm stratification seeds received, the shorter cold stratification were required to obtain the same germination percentage. Three rose seeds had different kinds of dormancy; R. hugonis has deep physiological dormancy, R. multibracteata with intermediate physiological dormancy and R. souliean non-deep physiological dormancy. 4）The seeds traits and dormancy of R. multibracteata showed significant difference across altitudes. Year and season of seed collection had significant effect on seed dormancy for both R. souliean and R. multibracteata. Hip size, seed size, seed weight, seed coat thickness and seed dormancy level increased with the increase of the altitude. There were positive relations between seed coat thickness with seed size and seed weight. Germination percentage of seeds treated with H2SO4 scarification following different periods of cold stratification showed positive relation with seed coat thickness, seed size, seed weight and altitude. Seeds of R. souliean and R. multibracteata collected in 2006 had low dormancy level than those collected in 2005. Seed dormancy decreased with increasing seeds age. High temperature and drought were associated with low dormancy level. 5) Seedling growth, the total dry mass and their components of seedlings were reduced, while leaf senescence accelerated under drought stress. More biomass allocation to root system resulted in higher R/S ratio under drought. Water-use efficiency (WUE) of R. multibracteata and R. hugonis increased, while it declined for R. soulieana under drought stress. R. soulieana seedlings had poor drought-resistance capacity it had more senescent leaves, and its reduction of biomass was stronger than two other rose plants under drought. The reduction degree of one year old seedlings under drought stress was slighter than that of current year seedlings. Therefore, one year old seedling was more drought-resistent compared to current year seedlings. 6）Planting seedlings may have better effect in comparison with direct seeding. Most seeds germinated after seeding, but seedling emergence was very low. More than 80 % seedlings from direct seeding died within a months after emergence. Seedling emergence and survival rate did not show difference among microhabitats. Mortality rates of seedlings artificially planted in microhabitats were general lower than 20 %, and the mortality rate of one year old seedlings was lower than 2 %. Each grow parameter including plant height, leaf number and branch number continually increased after planting. Microhabitat type had effect on the growth parameter and biomass production, but it did not influence the seedling survival. Bare land tended to facilitate seedling growth. One year old seedlings had higher survival rate than current year seedlings. In conculsion, the three rose had wide distribution in the dry valley of the Minjiang River. They produced many seeds and had tolerance to drought stress to some degree. But they had poor regeneration in habitats may be caused by predation, seed dormancy，and high mortality in current year seedlings. We recommend that rose plants should be utilized in restoration by planting two-year old seedlings in spring. A large quantity of seeds should be collected artificially in autumn, release seed dormancy in room, and then cultivate two-year old seedlings by seeding in particular container. R. soulieana seedling probably be planted in transition area, and R. multibracteata and R. hugonis can be used in core area of the dry valley of the Minjiang River.

川西北高寒草甸土壤呼吸研究：季节动态和放牧效应

除植被冠层的光合作用之外，土壤的呼吸作用是陆地生态系统碳收支中最大的通量。土壤呼吸即使发生较小的变化也能显著地减缓或加剧大气中CO2浓度的增加，从而明显影响到全球气候变化。土壤呼吸速率变化与否以及变化的方向可以反映生态系统对环境变化的敏感程度和响应模式。尽管如此，土壤呼吸仍是一个为人们了解不多的生态系统过程。 草地生态系统是陆地生态系统的一个重要组成部分。针对草地土壤呼吸进行野外实验研究和相应方法论的探讨将对区域乃至全球碳源汇性质的准确估算具有重要的科学意义。然而，近几年来关于草地土壤呼吸的主要研究工作都集中在温带草原和部分热带草原，而针对高寒草甸生态系统土壤呼吸的研究报道还很少。 2008年4月至2009年4月期间，我分别在2008年6、8、10、12月和2009年2月和4月分6次对川西北的典型高寒草甸群落的土壤呼吸进行观测，分析了不同类型高寒草甸群落土壤呼吸的季节变化特征以及环境因子和放牧模式对其影响。主要研究结果如下： 1）该地区高寒草甸生态系统在生长季（6月～8月）土壤呼吸速率较大（6.07～9.30μmolCO2¡m-2¡s-1 ） ， 在非生长季（ 12 月～ 2 月） 较小（ 0.16 ～0.49μmolCO2¡m-2¡s-1 ） 。土壤CO2 年累积最大释放量为3963 ～ 5730gCO2¡m-2¡yr-1，其中，生长季土壤CO2的释放量占年总释放量的85%～90%。非生长季占10%～15%。非生长季所占比例略小于冬季积雪覆盖地区的冬季土壤呼吸占年土壤呼吸量的比例（14%～30%）。温度，尤其地温，是影响该地区高寒草甸生态系统土壤呼吸速率的最主要环境因子。土壤呼吸速率与地上生物量和土壤水分之间没有显著相关性，但是土壤含水量过大会导致土壤呼吸速率下降。 2）在观测期内，草丘区的土壤呼吸显著高于对照区的土壤呼吸，其最大土壤呼吸速率为16.77μmolCO2¡m-2¡s-1，土壤CO2 年累积最大释放量为8145gCO2¡m-2¡yr-1，是对照区的近2 倍。由于草丘在高寒草甸中占有较大的面积比例（近30%），因此，它将对高寒草甸生态系统的碳循环起着重要的作用。 3）放牧模式不仅可以影响高寒草甸群落的土壤CO2 排放，而且还可以改变土壤呼吸的温度敏感性（Q10）。本研究表明，在生长季有长期放牧活动干扰时将会增加土壤向大气中释放二氧化碳的速度，促使土壤碳库中碳的流失。禁牧样地的土壤呼吸速率在刚禁牧时先迅速增大，随着禁牧时间的延长土壤呼吸速率将会下降。此外，与其它放牧模式相比，冬季放牧将高寒草甸群落土壤呼吸速率在生长季达到最大值的时间明显向后推迟。不同放牧模式下高寒草甸群落土壤呼吸的Q10 值大小顺序为：禁牧一年群落>冬季放牧群落>禁牧三年群落>夏季放牧群落>自由放牧群落。 4）基于呼吸室技术的观测方法中，测量前的剪草处理可以明显改变该地区高寒草甸群落的土壤温度和土壤呼吸速率。在生长季，剪草处理将使土壤呼吸速率的瞬时响应增加90%左右。由于剪草处理明显增加了剪草样方白天的土壤温度，而土壤温度与土壤呼吸之间存在着极显著的指数相关关系，因而剪草处理导致土壤呼吸速率迅速增加。因此，在高寒地区基于呼吸室技术观测的土壤呼吸应当进行校正。 综上所述，川西北高寒草甸生态系统土壤呼吸速率在生长季较高，而在非生长季较低。土壤温度是影响该地区土壤呼吸的最主要环境因子。在实验观测期，草丘区土壤呼吸速率显著高于对照区的，是对照区土壤呼吸速率的近2倍。由于测量前的剪草处理可以明显改变待测点的土壤呼吸速率，因此，应对在高寒地区基于呼吸室技术观测的土壤呼吸进行校正。 Soil respiration is the second largest component (less than plant phtotosynthesis) of carbon dioxide flux between terrestrial ecosystems and the atmosphere. A minor change in soil respiration rate can significantly slow down or accelerate the increase of atmospheric CO2 concentration that is closely related to global climatic change. In turn, the change in the flux direction and rate of soil respiration may indicate the elasticity and stability of ecosystems to global changes and human disturbance. However, soil respiration is still an ecosystem process that has been poorly understood. Grassland ecosystem is an important component of the terrestrial ecosystem. Accurately estimating the CO2 flux from soil to atmosphere in situ is the key to evaluating the carbon resource and sink regionally or globally. Despite of extensive studies on the temperate and tropic grasslands, the soil respiration of alpine meadows has not substantially been measured. In the current study, soil respiration was measured for an annual cycle from April, 2008 to April, 2009 for the alpine meadow in northwestern Sichuan Province of China to determine the seasonal variation of soil respiration for the typical plant communities. The results are shown as follows: 1) Large seasonal variation of soil respiration was observed in the alpine meadow. The rate of soil respiration was the greatest (6.07～9.30μmolCO2¡m-2¡s-1) in June and the smallest (0.16 ～ 0.49μmolCO2¡m-2¡s-1) occurred from December to February in the non-growing season. The total emission of soil CO2 was estimated as 3963～5730 gCO2¡m-2¡yr-1, 85%~90% of which was released during the growing season, and 10%~15% during the non-growing season which was slightly less than the ratio of winter and annual CO2 flux from soil. Temperature, particularly the soil temperature, was the major environmental factor regulating the soil respiration. Significant and positive relationships were not found between soil respiration and soil moisture and between soil respiration and plant above-ground biomass, but excessive soil water content would decrease in the rate of soil respiration. 2) The rate of soil respiration in grass hummock communities was up to 16.77μmolCO2¡m-2¡s-1, which was about twice as great as in the controls (communities located in low and even sites). Considering the large proportion (about 30% on average) of hummock area in the meadow, it can be concluded that the hummocks played an important role in the carbon cycling of the study ecosystem. 3) Grazing patterns affected the flux of CO2 emission and the temperature sensitivity of soil respiration (Q10) in the alpine meadow. Grazing during growing season increased the rate of soil respiration. The rate of soil respiration increased significantly immediately after the alpine meadow being fenced, but thereafter decreased. In addition, grazing in winter delayed the peak respiration rate relative to the non-grazing mode. The Q10 value was the largest in the non-grazed area for one year, and next came the area with grazing in winter, followed by the non-grazed area for three years, the area with grazing in summer, and the non-limited grazed area. 4) In the chamber-based techniques, clipping manipulation before each measurement increased the transient rate of soil respiration by about 90% in the summer of the alpine meadow. As increase in soil temperature at daytime in the clipped plots by clipping and the exponential relationship between soil respiration and temperature, clipping manipulation led to increase in the rate of soil respiration. This suggested that a correction should be done for the techniques if employed in alpine and cold regions. In summary, the rate of soil respiration in the alpine meadow was the greatest in June and the smallest occurred from ecember to February in the non-growing season. Soil temperature was the major environmental factor regulating the soil respiration. The rate of soil respiration in grass hummock communities was up to 16.77μmolCO2¡m-2¡s-1, which was about twice as great as in the controls. A correction should be done for the techniques if employed in alpine and cold regions, because of the effect of clipping manipulation on soil temperature and respiration.