Inferences on flow at the base of Earth's mantle based on seismic anisotropy

We applied global waveform tomography to model radial anisotropy in the whole mantle. We found that in the last few hundred kilometers near the core-mantle boundary, horizontally polarized S-wave velocities (VSH) are, on average, faster (by approximately 1%) than vertically polarized S-wave velocities (VSV), suggesting a large-scale predominance of horizontal shear. This confirms that the D" region at the base of the mantle is also a mechanical boundary layer for mantle convection. A notable exception to this average signature can be found at the base of the two broad low-velocity regions under the Pacific Ocean and under Africa, often referred to as "superplumes," where the anisotropic pattern indicates the onset of vertical flow.     

Development of diapiric structures in the upper mantle due to phase transitions

Solid-state phase transitions in time-dependent mantle convection can induce diapiric flows in the upper mantle. When a deep mantle plume rises toward phase boundaries in the upper mantle, the changes in the local thermal buoyancy, local heat capacity, and latent heat associated with the phase change at a depth of 670 kilometers tend to pinch off the plume head from the feeding stem and form a diapir. This mechanism may explain episodic hot spot volcanism. The nature of the multiple phase boundaries at the boundary between the upper and lower mantle may control the fate of deep mantle plumes, allowing hot plumes to go through and retarding the tepid ones.     

Pervasive seismic wave reflectivity and metasomatism of the Tonga mantle wedge

Subduction zones play critical roles in the recycling of oceanic lithosphere and the generation of continental crust. Seismic imaging can reveal structures associated with key dynamic processes occurring in the upper-mantle wedge above the sinking oceanic slab. Three-dimensional images of reflecting interfaces throughout the upper-mantle wedge above the subducting Tonga slab were obtained by migration of teleseismic recordings of underside P- and S-wave reflections. Laterally continuous weak reflectors with tens of kilometers of topography were detected at depths near 90, 125, 200, 250, 300, 330, 390, 410, and 450 kilometers. P- and S-wave impedances decreased at the 330-kilometer and 450-kilometer reflectors, and S-wave impedance decreased near 200 kilometers in the vicinity of the slab and near 390 kilometers, just above the global 410-kilometer increase. The pervasive seismic reflectivity results from phase transitions and compositional zonation associated with extensive metasomatism involving slab-derived fluids rising through the wedge.     

重复温汤处理对提高百合两品种耐热性的比较研究

通过对抗性生理指标及电阻抗图谱参数的测定,研究了重复温汤处理种球对亚洲百合"多安娜"及"普瑞头"幼苗耐热性的影响。结果发现:种球经重复温汤处理后,其幼苗在38℃胁迫下,"多安娜"叶片τm及脯氨酸含量比"普瑞头"上升幅度大,且峰值出现较早;其淀粉、可溶性糖含量及根系活力均始终高于"普瑞头"。温汤处理种球可显著提高"多安娜"及"普瑞头"幼苗的耐热性,其中"多安娜"优于"普瑞头"。     

More stressful event does not always depress subsequent life performance

Climate change has led to a substantial increase in intensity and duration of heat waves worldwide. Predicting the ecological impacts of hot events should incorporate both immediate and potential carry-over effects in different intensities of heat waves. Previous studies suggested that higher heat dose in early life stage of insect generally decreased immediate survival and depressed adult reproduction through carry-over effects, or unchanged adult performance through recovery effects. However, our previous study showed a different pattern, in which longer heat exposures in larval stage did not always decrease but sometimes increase the subsequent adult maturation success in the diamondback moth. We speculated that it might be another important pattern in the carry-over effects vs. heat dose, and conducted experiments using a global pest, Plutella xylostella. Our present results suggested that heat exposures in early life stage reduced the immediate survival and produced general declines with significant zigzag fluctuating patterns in subsequent body size and reproduction as exposure durations increased. The similar patterns were also validated in other insect taxa and other stresses by reanalyzing the experiment data from literatures. The finding highlights the importance for differentiating the biological effects and consequences of changes in heat dose at fine scales; daily exposure hours of a hot day should be considered to predict population dynamic under climate change.     

Three-dimensional instabilities of mantle convection with multiple phase transitions

The effects of multiple phase transitions on mantle convection are investigated by numerical simulations that are based on three-dimensional models. These simulations show that cold sheets of mantle material collide at junctions, merge, and form a strong downflow that is stopped temporarily by the transition zone. The accumulated cold material gives rise to a strong gravitational instability that causes the cold mass to sink rapidly into the lower mantle. This process promotes a massive exchange between the lower and upper mantles and triggers a global instability in the adjacent plume system. This mechanism may be cyclic in nature and may be linked to the generation of superplumes.     

The Nature of the 660-Kilometer Upper-Mantle Seismic Discontinuity from Precursors to the PP Phase

Global Seismic Network data were used to image upper-mantle seismic discontinuities. Stacks of phases that precede the PP phase, thought to be underside reflections from the upper-mantle discontinuities at depths of 410 and 660 kilometers, show that the reflection from 410 kilometers is present, but the reflection from 660 kilometers is not observed. A continuous Lame's constant lambda and seismic parameter at the 660-kilometer discontinuity explain the missing underside P reflections and lead to a P-wave velocity jump of only 2 percent, whereas the S-wave velocity and density remain unchanged with respect to previous global models. The model deemphasizes the role of Lame's constant lambda with regard to the shear modulus and constrains the mineralogical composition across the discontinuity.     

Seismic anisotropy: tracing plate dynamics in the mantle

Elastic anisotropy is present where the speed of a seismic wave depends on its direction. In Earth's mantle, elastic anisotropy is induced by minerals that are preferentially oriented in a directional flow or deformation. Earthquakes generate two seismic wave types: compressional (P) and shear (S) waves, whose coupling in anisotropic rocks leads to scattering, birefringence, and waves with hybrid polarizations. This varied behavior is helping geophysicists explore rock textures within Earth's mantle and crust, map present-day upper-mantle convection, and study the formation of lithospheric plates and the accretion of continents in Earth history.     

The superswell and mantle dynamics beneath the South pacific

The region of sea floor beneath French Polynesia (the "Superswell") is anomalous in that its depth is too shallow, flexural strength too weak, seismic velocity too slow, and geoid anomaly too negative for its lithospheric age as determined from magnetic isochrons. These features evidently are the effect of excess heat and extremely low viscosity in the upper mantle that maintain a thin lithospheric plate so easily penetrated by volcanism that 30 percent of the heat flux from all hot spots is liberated in this region, which constitutes only 3 percent of the earth's surface. The low-viscosity zone may facilitate rapid plate motion and the development of small-scale convection. A possible heat supply for the Superswell is a mantle reservoir enriched in radioactive isotopes as suggested by the geochemical signature of lavas from Superswell volcanoes.     

鹅热休克蛋白70的表达提纯与病毒复合物形成的研究

 【目的】为研究HSP70在热应激时的特异性表达、组织中HSP70的分离纯化及其结合抗原肽形成复合物的特性，设计此试验。【方法】选取6 w健康五龙鹅60只随机分为3组，对照组鹅不经热处理，试验1组鹅进行1次（42±1）℃、5 h的急性热处理后立即宰杀，试验2组鹅经热处理后在正常饲养条件下恢复12h后宰杀。取心脏，常规石蜡切片做免疫组化试验；肝脏用于提纯HSP70。比较处理组鹅心脏HSP70表达的差异，同时对肝脏中HSP70进行分离纯化、鉴定。纯化后的HSP70和人工合成的乙肝病毒前S1多肽相结合形成复合物，以双特异抗体夹心法检测其复合物的形成。【结果】热应激状态下心肌纤维中有广泛的HSP70阳性颗粒，试验1组HSP70表达部位重点在核膜及其周围，阳性细胞率为76.0%，试验2组HSP70表达部位转移到胞膜周围，阳性细胞率为88.4%。通过两套纯化方案纯化蛋白均可得到HSP70纯化物，蛋白纯度分别为85.0%和95.0%，蛋白得率分别为0.115mg•g-1和0.157 mg•g-1。一定条件下合成肽与HSP70纯化物形成复合物，双特异性抗体夹心法检测复合物为阳性，复合物效价为1﹕81，表明试验中有复合物的形成。【结论】热应激时HSP70的特异性表达部位，在不同时间有所转移，显示HSP70在细胞保护中可能具有一定的功能。在低压层析条件下可以得到高纯度的HSP70蛋白，相比较而言，分子筛初步分离、ConA琼脂糖层析和ADP琼脂糖层析这一流程的纯化效果更好。在一定条件下，人工合成肽可以与HSP70相结合形成复合物，这将为进一步证明复合物的免疫作用提供试验基础。     

A Lower Mantle Source for Central European Volcanism

Cenozoic rifting and volcanism in Europe have been associated with either passive or active mantle upwellings. Tomographic images show a low velocity structure between 660- and 2000-kilometer depth, which we propose to represent a lower mantle upwelling under central Europe that may feed smaller upper-mantle plumes. The position of the rift zones in the foreland of the Alpine belts and the relatively weak volcanism compared to other regions with plume-associated volcanism are probably the result of the past and present subduction under southern Europe.     

高温热处理杉木间伐材的抗褐腐性能

以褐腐菌棉腐卧孔菌为试菌,对分别用热油和热空气为介质,经不同温度、不同时间热处理后的杉木间伐材试样的耐腐性进行了试验,并与质量分数为1.0%的CCA-C防腐剂处理材(吸药量为2.53 kg.m-3)和未处理材进行了比较.结果表明:在2种加热介质中经不同温度、不同时间处理后试材的耐腐性均比未处理材高,且随温度的升高、处理时间的延长,耐腐性有较明显的改善;试材在180、200℃分别经不同时间热处理后的耐腐性均低于CCA-C处理材,但在220℃热处理3、5 h后,各试材的质量损失率均为0;若处理温度和时间相同,则热油处理材的耐腐性基本上高于热空气处理材.     

热油管道非稳态流动传热数值模拟研究进展

随着计算机技术和计算方法的发展,求解热油管道非稳态流动传热问题的数值方法得到了更广泛的使用。从管道防腐层大修过程非稳态流动传热的数值模拟、冷热油交替顺序输送管道非稳态流动传热的数值模拟和双管同沟敷设管道非稳态流动传热的数值模拟三个方面介绍了近三年来热油管道非稳态流动传热数值模拟研究的进展和发展趋势。     

Lherzolite, anorthosite, gabbro, and basalt dredged from the mid-Indian ocean ridge

The Central Indian Ridge is mantled with flows of low-potassium basalt of uniform composition. Gabbro, anorthosite, and garnet-bearing lherzolite are exposed in cross fractures, and lherzolite is the bedrock at the center of the ridge. The Iherzolites are upper-mantle rock exposed by faulting.     

CARA效用函数下美式期权的定价

《中庸辑略》系朱子删定石《中庸集解》而成,原本辑录的十先生《中庸》说被芟节多达134条,比例几近30%。经此“再造”的版本异同,固已不同于一般而论的版本文字差异,而宜视作删订者的主观故意行为。本文采用文献考证、数量统计等方法,结合整体考察和个案分析,揭示朱子芟节的“义例”及其潜在的诠释意图,并将此置于朱子学术思想的发展环节来试作讨论。     

Compositional stratification in the deep mantle

A boundary between compositionally distinct regions at a depth of about 1600 kilometers may explain the seismological observations pertaining to Earth's lower mantle, produce the isotopic signatures of mid-ocean ridge basalts and oceanic island basalts, and reconcile the discrepancy between the observed heat flux and the heat production of the mid-ocean ridge basalt source region. Numerical models of thermochemical convection imply that a layer of material that is intrinsically about 4 percent more dense than the overlying mantle is dynamically stable. Because the deep layer is hot, its net density is only slightly greater than adiabatic and its surface develops substantial topography.     

温汤处理种球对亚洲百合幼苗耐热性的影响

【目的】研究温汤处理种球对亚洲百合幼苗耐热性的影响。【方法】以亚洲百合‘多安娜’(Pollyanna)为试材,研究种球在45℃下,经历不同时间梯度(0、10、20、30、40、50min)温汤处理后,其幼苗抗性生理指标及电阻抗图谱参数对38℃胁迫的反应。【结果】种球热锻炼20min,植株SOD活性及可溶性糖含量分别高于对照51.41%(P0.01)和23.45%(P0.01),根系活力比对照增加57.11%(P0.01),弛豫时间与对照无显著性差异;处理30min后,SOD活性及可溶性糖含量分别达到峰值,但与处理20min差异不显著,且根系活力下降至低于对照。【结论】种球温汤处理20min显著提高亚洲百合‘多安娜’幼苗耐热性。     

Perfection of the Technology for Production of Canned Apple Compotes Using Secondary Resources and Intensive Sterilization Regimes

This paper presents the results of research on improving the technology for production of canned apple compotes using secondary products after cutting and cleaning fruit for syrup boiling and intensive heat sterilization based on the use of new techniques—preliminary heating of fruit in cans in the ultrahigh frequency electromagnetic field with sterilization under intensive regimes with the use of high-temperature heat carriers and rotation of the cans during sterilization. It is established that the use of the resulting infusion of secondary products for syrup boiling provides saving of more than 8 kg of sugar per tube of product. In this case, the content of vitamin C in the finished product is more than two times higher than in the case of using the traditional method of blanching in hot water. Studies on the heating and actual lethality of microorganisms have shown that the developed mode provides the industrial sterility of canned food, saves heat energy, and shortens the duration of the heat sterilization mode by 20 min.     

5个一串红品种耐热性鉴定

一串红是夏季园林常见花卉,2008年北京奥运会召开期间正值北京地区夏季高温天气,为使一串红发挥出很好的景观效应,选用耐热性好的品种是关键措施之一。通过对自育的1120#、12#、73#品种和国外引进的展望、王后共5个一串红品种在热胁迫处理下叶绿素含量、电导率、MDA和脯胺酸含量测定,结果表明,随着热处理时间延长,展望和王后叶片叶绿素下降速度最大、细胞膜伤害率上升最快、MDA含量达最大、脯氨酸含量增幅较小,是最不耐热的2个品种,1120#、12#和73#品种耐热性较好。这种耐热性差异在北京地区夏季盆花生产中也得到证实。因此,在夏季高温季节种植一串红,建议选用耐热性较好的1120#、12#和73#品种。     

不同干燥方法对金线莲多糖含量的影响

通过热泵干燥与传统的自然晒干和热风干燥比较,采用苯酚-硫酸法测定金线莲多糖含量。结果表明:采用热泵干燥的金线莲多糖得率最高,经分离纯化后多糖含量达10.24%,且外观品质好,干燥时间短。