Clinoenstatite in alpe arami peridotite: additional evidence of very high pressure

Observations by transmission electron microscopy show that lamellae of clinoenstatite are present in diopside grains of the Alpe Arami garnet lherzolite of the Swiss Alps. The simplest interpretation of the orientation, crystallography, and microstructures of the lamellae and the phase relationships in this system is that the lamellae originally exsolved as the high-pressure C-centered form of clinoenstatite. These results imply that the rocks were exhumed from a minimum depth of 250 kilometers before or during continental collision.     

Catalysis of the olivine to spinel transformation by high clinoenstatite

Although enstatite is a major constituent of the Earth's upper mantle and subducting lithosphere, most kinetic studies of olivine phase transformations have typically involved single-phase polycrystalline aggregates. Transmission electron microscopy investigations of olivine to spinel and modified spinel (beta phase) reactions in the (Mg, Fe)(2)SiO(4)-(Mg,Fe)SiO(3) system show that transformation of olivine in the stability field of spinel plus phase begins with coherent nucleation of spinel on high-clinoenstatite grains. These observations demonstrate that high clinoenstatite can catalyze the transformation by enhancing nucleation kinetics and therefore imply that secondary phases can influence reaction kinetics during high-pressure mineral transformations.     

Gone with the wind: the origin of S0 galaxies in clusters

We present three-dimensional, high-resolution hydrodynamical simulations of the interaction between the hot ionized intracluster medium and the cold interstellar medium of spiral galaxies. Ram pressure and turbulent/viscous stripping remove 100% of the atomic hydrogen content of luminous galaxies like the Milky Way within 100 million years. These mechanisms naturally account for the morphology of S0 galaxies and the rapid truncation of star formation implied by spectroscopic observations, as well as a host of observational data on the neutral hydrogen (HI) morphology of galaxies in clusters.     

Epitaxial growth and the art of computer simulations

The results of kinetic simulations of the aggregates formed during the deposition of atoms on a semiconductor surface are reviewed. Because the kinetic parameters are poorly known and the accuracy of the existing interatomic potentials has not been sufficiently tested, the goal has been to reach a qualitative understanding of the formation of unusual patterns during growth, such as the segregation of aluminum during the growth of aluminum-gallium-arsenide (AlGaAs) coherent tilted superlattices and the formation of thin, long, and parallel islands during the deposition of Si on an Si(100) surface. Kinetic mechanisms for these phenomena are proposed.     

Atomic-scale desorption through electronic and vibrational excitation mechanisms

The scanning tunneling microscope has been used to desorb hydrogen from hydrogen-terminated silicon (100) surfaces. As a result of control of the dose of incident electrons, a countable number of desorption sites can be created and the yield and cross section are thereby obtained. Two distinct desorption mechanisms are observed: (i) direct electronic excitation of the Si-H bond by field-emitted electrons and (ii) an atomic resolution mechanism that involves multiple-vibrational excitation by tunneling electrons at low applied voltages. This vibrational heating effect offers significant potential for controlling surface reactions involving adsorbed individual atoms and molecules.     

盐胁迫对柑橘愈伤组织生理效应的影响

以温州蜜柑品种国庆1号的愈伤组织为试材,研究不同浓度盐处理(0、25 、50及100 mmol/L NaCl)对柑橘愈伤组织生长量、可溶性蛋白、可溶性糖、游离脯氨酸含量以及过氧化氢酶、超氧化物歧化酶活性的影响.结果表明,随着NaCl浓度的升高,愈伤组织生长量显著下降,可溶性蛋白含量表现出先增加后减少的趋势,可溶性糖和游离脯氨酸的含量显著增加,而超氧化物歧化酶和过氧化氢酶活性均表现出先增强后减弱的变化趋势.试验为在细胞组织水平上阐明盐胁迫对柑橘的伤害机理提供了依据.     

外源一氧化氮对铝胁迫下烟草叶片呼吸作用和活性氧代谢的影响

为探明外源一氧化氮(NO)提高烟草耐铝性的生理机制,采用水培法研究了NO供体硝普钠(SNP)对铝胁迫下2个不同耐铝性烟草品种云烟100(耐铝)和云烟105(敏感)植株生长、叶片活性氧(ROS)含量、呼吸作用和线粒体抗氧化酶活性的影响。结果表明,铝胁迫显著降低了烟草叶片总呼吸速率、细胞色素呼吸速率、交替呼吸速率、细胞色素氧化酶(COX)活性和丙酮酸含量,导致叶片O—·2产生速率升高和H2O2大量积累,植株生物量显著下降,且云烟105变幅高于云烟100;外源NO处理显著缓解铝对烟草植株生长的抑制,提高叶片总呼吸速率、细胞色素呼吸速率、交替呼吸速率、COX活性和丙酮酸含量,降低叶片O—·2产生速率和H2O2含量,且对云烟105的缓解效果显著高于云烟100。此外,外源NO处理进一步提高铝胁迫下烟草叶片线粒体超氧化物歧化酶(SOD)和抗坏血酸过氧化物酶(APX)活性,且云烟105增幅显著大于云烟100。综上所述,外源NO处理可通过提高烟草叶片呼吸作用和线粒体抗氧化酶活性来清除线粒体内ROS含量,从而缓解铝对烟草的毒害作用,且对敏感基因型的缓解效应较耐铝基因型更为明显。     

Shoot and root traits in drought tolerant maize (Zea mays L.) hybrids

This study aimed to investigate the differences in shoot and root traits, and water use and water use efficiency (WUE) in drought tolerant (DT) maize (Zea mays L.) hybrids under full and deficit irrigated conditions. A two-year greenhouse study was conducted with four hybrids (one conventional hybrid, 33D53AM, two commercial DT hybrids, P1151AM, N75H, and an experimental hybrid, ExpHB) grown under two water regimes (I₁₀₀ and I₅₀, referring to 100 and 50% of evapotranspiration requirements). Under water stress, the hybids P1151AM, N75, and ExpHB showed more drought tolerance and had either greater shoot dry weight or less dry weight reduction than the conventional hybrid (33D53AM). However, these three hybrids responded to water stress using different mechanisms. Compared with the conventional hybrid, the two commercial DT hybrids (P1151AM and N75H) had a smaller leaf area, shoot dry weight, and root system per plant. As a result, these hybrids used less water but had a higher WUE compared with the conventional hybrid. In contrast, the experimental hybrid (ExpHB) produced more shoot biomass by silking stage at both irrigation levels than all other hybrids, but it had relatively lower WUE. The hybrids demonstrated different drought response mechanisms that may require different irrigation management strategies. More investigation and validation are needed under field conditions and in different soil types.     

Characteristics and Degradation Mechanism of Fomesafen

High performance liquid chromatography(HPLC) was used to determine the degradation efficiency of bacteria 2 strain(B2 S) under different conditions, the optimum cultivation conditions for fomesafen degradation bacterium B2 S were as the followings: temperature 35℃; inoculation quantity 5%; p H 5.0; glucose content 0.5% and fomesafen concentration 10 mg · L-1. Under optimal conditions, B2 S degraded fomesafen within 72 h of fomesafen application, with a degradation rate of nearly 100%. High performance liquid chromatography-mass spectrometry(HPLC-MS) was used to analyze fomesafen degradation into microbial products. A more thorough understanding of microbial fomesafen degradation mechanisms was discussed. The pathway of fomesafen degradation by B2 S was also inferred herein.     

铅与盐胁迫对黄菖蒲生长及生理抗性的影响

[目的]探讨Pb和NaCl对黄菖蒲生长、Pb富集及抗性的影响。[方法]采用营养液培养黄菖蒲,研究Pb、NaCl单因子及复合胁迫对黄菖蒲的生长、Pb在植物不同部位的富集以及生理变化的影响。[结果]结果显示,随着Pb和NaCl浓度的增加,黄菖蒲地上部和地下部干重下降;NaCl对Pb的吸收有一定促进作用。在浓度100 mmol/L单因子NaCl及与Pb复合胁迫下,MDA含量和Pro含量显著增加,在高浓度单因子Pb和NaCl及Pb和NaCl复合胁迫下SOD酶活性显著提高。[结论]黄菖蒲具有一定的耐Pb及NaCl胁迫的能力和对Pb的富集能力,是一种可用于修复Pb污染环境的Pb潜在超富集植物。     

Insights into African swine fever virus immunoevasion strategies

African swine fever(ASF) is an acute and highly contagious disease that causes severe economic losses to the swine industry. ASF is caused by infection of African swine fever virus(ASFV) in domestic pigs, leading to almost 100% mortality. However, no effective vaccines and pharmacologic treatment against ASF are available. ASF poses a severe threat to the swine industry and the economy. Here we summarize potential virus-host cell interaction mechanisms involving the suppression of innate and adaptive immune responses to ASFV entry and infection. These mechanisms include modulation of apoptosis, inhibition of inflammatory responses, reduction of IFN production, inhibition of autophagy, and suppression of MHC-I expression. Insights into immunoevasion strategies by ASFV may shed light on the development of vaccines, as well as preventive and therapeutic drugs.     

茉莉酸和水杨酸对热胁迫下葡萄幼苗抗氧化能力的影响

用50μmol/L茉莉酸和100μmol/L水杨酸预处理葡萄幼苗后,在高温胁迫下,蛋白质含量、抗坏血酸氧化物酶、谷胱甘酞还原酶活性呈现先升后降的变化趋势,抗坏血酸含量持续下降,茉莉酸和水杨酸预处理过的葡萄幼苗中可溶性蛋白质含量、抗坏血酸氧化物酶、谷胱甘酞还原酶活性和抗坏血酸含量与谷胱甘酞含量都高于对照。由此认为茉莉酸和水杨酸能减缓高温胁迫所引起的胁变反应。推测JA和SA处理在诱导葡萄抗热性能上可能具有相似的机理。     

Alleviation of arsenic toxicity by phosphate is associated with its regulation of detoxification,defense, and transport gene expression in barley

Arsenic(As) contamination in soils has posed a severe threat to safe crop production. The previous studies showed the antagonism between phosphorus(P) and As in plant growth and As uptake, while the mechanisms of alleviating As toxicity by P is not completely clear. Due to the limiting P condition, it is imperative to understand how low P addition can be used to suppress arsenate As(V) uptake and the subsequent mechanisms involved. Thus in this study we investigated the effect of P addition on As uptake, anti-oxidative enzyme activity, and anti-oxidant content, and the relative expression of transport, defense, and detoxification genes using two barley genotypes differing in As toxicity tolerance. P addition significantly reduced As concentration in plant tissues, and caused the great changes in activities of catalase and superoxide dismutase, glutathione content, and the relative expression of examined genes when the plants of the two barley genotypes were exposed to 100 μmol L~(–1) As, with ZDB160(As-tolerant) being much more affected than ZDB475(As-sensitive). The current results show that P addition can alleviate As toxicity by regulating the expression of As transport, defense, and detoxification genes to a greater extent in As tolerance of barley, suggesting the possibility of controlling As uptake and toxicity by applying low amount of P fertilizers in the As-contaminated soils.     

Mediation of wound-related Rous sarcoma virus tumorigenesis by TGF-beta

In Rous sarcoma virus (RSV)-infected chickens, wounding leads to tumor formation with nearly 100% frequency in tissues that would otherwise remain tumor-free. Identifying molecular mediators of this phenomenon should yield important clues to the mechanisms involved in RSV tumorigenesis. Immunohistochemical staining showed that TGF-beta is present locally shortly after wounding, but not unwounded controls. In addition, subcutaneous administration of recombinant transforming growth factor-beta 1 (TGF-beta 1) could substitute completely for wounding in tumor induction. A treatment protocol of four doses of 800 nanograms of TGF-beta resulted in v-src-expressing tumors with 100% frequency; four doses of only 10 nanograms still led to tumor formation in 80% of the animals. This effect was specific, as other growth factors with suggested roles in wound healing did not elicit the same response. Epidermal growth factor (EGF) or TGF-alpha had no effect, and platelet-derived growth factor (PDGF) or insulin-like growth factor-1 (IGF-1) yielded only occasional tumors after longer latency. TGF-beta release during the wound-healing response may thus be a critical event that creates a conducive environment for RSV tumorigenesis and may act as a cofactor for transformation in this system.     

噪声应激对大鼠脑内c-fos表达的影响

采用噪声应激的大鼠模型,以免疫组化法检测在慢性应激过程中大鼠脑内有关神经核的Fos蛋白表达.结果表明:下丘脑的室旁核(PVN)、视上核(SON)与脑桥蓝斑(LC)的Fos蛋白表达高峰出现在噪声应激的第5 d,而边缘前脑的海马(HC)和杏仁核则出现在第10 d,以后Fos蛋白表达逐渐减少,而且100 dB组比80 dB组的Fos蛋白表达水平更高.提示噪声应激的Fos蛋白表达不仅与刺激类型与强度有关,且有多重脑机制的参与.     

An ice-free cretaceous? Results from climate model simulations

We have quantitatively investigated the mechanisms that could explain the warm, equable climate that is believed to have been typical of the mid-Cretaceous (100 million years ago). By performing simulations with a climate model based on zonal energy balance, we demonstrate that past changes in geography were important in bringing about climatic change. However, the meridional distribution of Cretaceous temperatures cannot be successfully simulated unless additional physical "feedback mechanisms" are included in the model. These mechanisms may involve cloud and meridional heat transport changes. We also conclude that paleoclimatologists should reexamine carefully both existing data and their interpretations with regard to reconstruction of Cretaceous tropical and polar surface temperatures.     

免耕条件下不同秸秆覆盖量对土壤木质素含量的影响

【目的】研究不同秸秆覆盖量免耕对土壤木质素（VSC）含量的影响,探讨免耕作对土壤有机碳截获和平衡的影响过程和机制。【方法】以吉林省梨树县黑土免耕作长期定位试验田的表层土壤为研究对象,对比分析无秸秆覆盖、33%秸秆覆盖、67%秸秆覆盖、100%秸秆覆盖4种处理土壤中木质素的变化特征。【结果】与无覆盖相比,经过4年连续秸秆覆盖后,木质素在土壤表层聚集,随着土壤深度的增加,木质素含量逐渐减少;随着覆盖量的增多,0—2 cm土层中VSC含量逐步增大,100%覆盖是无覆盖处理的5.06倍; 5—20 cm土层中各处理间VSC含量差异并不显著;木质素来源碳在有机碳中的相对比例随着深度的增加而减少;与无覆盖相比,秸秆覆盖增加了木质素来源碳在有机碳中的相对比例;秸秆覆盖后,木质素丁香基单体（S）与香草基单体（V）比值（S/V）以及肉桂基单体（C）与S单体比值（C/V）减少,S类和V类单体的酸醛比（Ac/Al）s 和（Ac/Al）v增大,表明秸秆还田不同程度降低了土壤有机质的氧化程度。【结论】秸秆覆盖免耕条件下,植物来源木质素在土壤表层选择性积累,延缓了木质素的氧化,增加了土壤有机碳的截获量和稳定性。     

重金属Cu2+对紫荆种子萌发和幼苗生理的影响

为研究重金属Cu2+对紫荆幼苗生长影响的生理机制,试验利用CuSO4溶液的浓度梯度对紫荆种子进行了胁迫处理,分别测定紫荆种子的发芽率、发芽指数、活力指数等发芽指标和幼苗叶片的丙二醛、可溶性糖、脯氨酸含量及过氧化物酶活性、细胞膜透性等生理指标.结果表明,紫荆种子抗重金属Cu2+胁迫的能力比较强,在致死状态下,CuSO4溶液的浓度为183.40 mg/L;在半致死状态下,CuSO4溶液的浓度为104.22 mg/L.随着CuSO4溶液浓度的增加,紫荆种子的发芽率、发芽指数、活力指数逐步下降,幼苗叶片的细胞膜透性和丙二醛、可溶性糖、脯氨酸含量均有不同程度地增加,而幼苗叶片的过氧化物酶活性则呈现出先增加后递减的变化趋势.     

Visualizing gas molecules interacting with supported nanoparticulate catalysts at reaction conditions

Understanding how molecules can restructure the surfaces of heterogeneous catalysts under reaction conditions requires methods that can visualize atoms in real space and time. We applied a newly developed aberration-corrected environmental transmission electron microscopy to show that adsorbed carbon monoxide (CO) molecules caused the {100} facets of a gold nanoparticle to reconstruct during CO oxidation at room temperature. The CO molecules adsorbed at the on-top sites of gold atoms in the reconstructed surface, and the energetic favorability of this reconstructed structure was confirmed by ab initio calculations and image simulations. This atomic-scale visualizing method can be applied to help elucidate reaction mechanisms in heterogeneous catalysis.     

北方6种园林绿化灌木水分参数对干旱胁迫的响应

以红瑞木(Cornus alba)、红王子锦带(Weigela floridacv.Red prince)、麦李(Prunus glandulosa)、辽东水蜡(Ligustrum obtusifolium)、杞柳(Salixintegra)、忍冬(Lonicera maackii)6种绿化灌木幼苗为材料,采用盆栽控水法研究6种苗木在干旱胁迫下的水分状况。设置4种土壤水分条件,土壤含水量分别设为55%(A)、45%(B)、35%(C)和25%(D)。应用PV技术测定不同苗木的束缚水含量(Va)、饱和时的最大渗透势(Ψ1π00)、膨压为0时的渗透势(Ψ0π)、相对含水量(CR0W)、相对渗透水含量(C0ROW)、组织细胞体积最大弹性模量(εmax)等水分参数,并用模糊隶属函数值法对6种苗木在水分胁迫条件下的渗透调节和维持膨压的能力进行综合评定。结果表明:6个树种的Ψπ100、Ψπ0、CR0W、CR0OW、Va和εmax值均不同,抗旱性也存在一定的差异,抗旱能力大小依次为红瑞木红王子锦带麦李辽东水蜡杞柳忍冬。它们通过不同的方式来适应干旱环境,其抗旱能力的大小是相对而言的。