The magnetic stability of spin-dependent tunneling devices

The tunneling resistance between two ferromagnetic metal layers that are separated by a thin insulator depends on the relative orientation of the magnetization M of each layer. In a memory device, independent switching of the magnetically soft layer is achieved by making the other layer either exchange-biased or magnetically hard. The repeated reversal of M of the soft layer by field cycling can demagnetize the other magnetically hard layer and thus erase the tunnel junction's memory. The M of exchange-biased structures was stable at least to 10(7) cycles, whereas in hard structures, M generally decayed logarithmically with the number of field cycles. The decay was very sensitive to the thickness of the hard layer and the composition of the soft layer. However, no decay was observed when the moment reversal was accomplished by coherent rotation, establishing that demagnetization results from the formation and motion of domain walls in the soft layer during field cycling.     

地下电站厂房层状围岩位移的动态效应研究

层状复合围岩岩体软硬相间，不满足均匀、连续及各向同性的要求．研究依据多种测试手段，对开挖后围岩的稳定性和变形进行实时监测．并对数值模型进行三维非线性弹塑性计算、分析，比较准确地预测了围岩的动态变化过程，研究了层状围岩位移和应力的变化规律。     

The remanent magnetization of lunar soils

The magnetic material in the lunar soils makes them potentially strong carriers of remanence and magnetically viscous. The soils therefore block remanence in the temperature range of the lunar diurnal cycle. This remanence is stable against alternating-field demagnetization. A mechanism whereby such hard natural remanent magnetization may be acquired by material buried in the regolith is proposed.     

X-ray diffraction from magnetically oriented solutions of macromolecular assemblies

A simple system was developed for obtaining x-ray diffraction patterns from magnetically oriented solutions of macromolecular assemblies. A small permanent magnet was designed that produces a magnetic field of 16 kilogauss in a volume of 1 cubic millimeter and is mountable on most x-ray cameras. Many subcellular structures have sufficient diamagnetic anisotropy that they exhibit orientation in dilute solution when placed between the poles of the magnet. Diffraction from solutions oriented in this magnet can provide substantially more structural information than small-angle scattering from isotropic solutions. In favorable cases, such as dilute solutions of filamentous bacteriophages, it is possible to produce oriented fiber diffraction patterns from which intensities along layer lines can be measured to 7-angstrom resolution. The magnetically induced birefringence observed in solutions of other macromolecular assemblies suggests that this technique may have broad applicability to subcellular structures.     

Metallic glasses

Amorphous metallic alloys, relative newcomers to the world of glasses, have properties that are unusual for solid metals. The metallic glasses, which exist in a very wide variety of compositions, combine fundamental interest with practical applications. They also serve as precursors for exciting new nanocrystalline materials. Their magnetic (soft and hard) and mechanical properties are of particular interest.     

Free-electron lasers. Status and applications

A free-electron laser consists of an electron beam propagating through a periodic magnetic field. Today such lasers are used for research in materials science, chemical technology, biophysical science, medical applications, surface studies, and solid-state physics. Free-electron lasers with higher average power and shorter wavelengths are under development. Future applications range from industrial processing of materials to light sources for soft and hard x-rays.     

上海市林地土壤有机碳分布特征及其与土壤理化性质的关系

土壤有机碳影响着全球气候生态系统的平衡。城市林地作为城市生态系统的重要组成部分,其碳含量和密度的高低是评价城市生态环境建设成功与否的关键。以上海市7种典型林地樟树Cinnamomum camphora林、阔叶混交林、其他软阔林、其他硬阔林、针阔混交林、水杉Metasequoia glyptostroboides林、经济林为对象,分析了不同林地、不同土层（0~10,10~30,30~100 cm）的有机碳质量分数和密度分布特征,并采用Pearson相关性分析方法和逐步剔除回归法探讨了有机碳质量分数与土壤基本理化性质的关系。结果表明:①上海市林地0~100 cm土壤有机碳平均质量分数从大到小依次为:其他软阔林、樟树林、经济林、阔叶混交林、水杉林、针阔混交林、其他硬阔林。各林地土壤有机碳质量分数在0~10和10~30 cm存在显著差异（P < 0.05）。除经济林,其余林地土壤有机碳质量分数在垂直方向上均表现为逐渐降低。②上海市林地0~100 cm土壤有机碳密度从大到小依次为:樟树林、其他软阔林、经济林、阔叶混交林、针阔混交林、水杉林、其他硬阔林。上海市林地0~30 cm土层有机碳密度对0~100 cm土层的贡献率较低。③上海市7种林地土壤有机碳质量分数与全氮和碱解氮呈极显著正相关（P < 0.01）,与电导率、全磷的相关性不显著。樟树林、其他软阔林、其他硬阔林、水杉林的土壤有机碳质量分数与容重显著负相关（P < 0.05）。阔叶混交林、其他软阔林、其他硬阔林的土壤有机碳质量分数与pH值呈显著负相关（P < 0.05）;樟树林、水杉林的土壤有机碳质量分数与速效磷显著正相关（P < 0.05）。除阔叶混交林、水杉林的土壤有机碳质量分数的主要影响因子为全氮,樟树林、其他软阔林、其他硬阔林和针阔混交林的土壤有机碳质量分数变化的主控因子为碱解氮。     

一种改进的小波阈值去噪方法

为了改进滤波效果,提高去噪质量,在分析目前被广泛应用的软、硬阈值去噪方法的基础上,提出了一种改进的阈值去噪方法.该方法既兼顾了软、硬阈值函数的优点,同时又在一定程度上弥补了它们在图像去噪中的缺陷.有效克服了硬阈值法去噪信号失真的和软阈值法细节模糊现象.仿真结果表明:该方法可以有效地去除白噪声干扰,无论在视觉效果上还是在信噪比定量指标上均明显优于传统的软、硬阈值算法,达到良好的去噪效果.     

菠萝蜜果实糖苷酶和多聚半乳糖醛酸酶的活性变化

【目的】研究菠萝蜜果实成熟软化的机制和干、湿苞菠萝蜜质地差异形成的机理,为菠萝蜜育种提供理论基础。【方法】以不同基因型的干苞和湿苞菠萝蜜为材料,以对硝基苯β-D-吡喃半乳糖苷和对硝基苯α-D-吡喃甘露糖苷为底物测定果实成熟软化过程中β-半乳糖苷酶（β-Gal）、α-甘露糖苷酶（α-Man）,以多聚半乳糖醛酸为底物测定多聚半乳糖醛酸酶（PG）的活性变化。【结果】水溶性和盐溶性的β-半乳糖苷酶活性在两个湿苞菠萝蜜基因型中均表现先上升后下降的趋势,分别在采后2d和采后当天达到最高值,其中,水溶性酶的活性水平分别先上升42.3%、52.8%随后下降22.8%、52.6%,盐溶性酶的活性先上升27.6%、67.7%后下降10.5%、35.4%;水溶性多聚半乳糖醛酸酶活性在两个湿苞菠萝蜜基因型中均表现出直线上升的趋势,酶活性水平增加75.0%、147.3%,而在两个干苞菠萝蜜基因型中则略有增加（增加40.9%）或变化不大;盐溶性的多聚半乳糖醛酸酶和水溶及盐溶性α-甘露糖苷酶在不同基因型的干苞和湿苞菠萝蜜果实中呈现不同的变化趋势。【结论】水溶性和盐溶性β-半乳糖苷酶、水溶性多聚半乳糖醛酸酶在湿苞和干苞菠萝蜜类型间表现出完全不同的变化趋势,而在湿苞或干苞基因型内表现出相同的变化趋势,它们与干湿苞菠萝蜜果实的质地差异形成有关。     

小麦籽粒胚乳结构性状的研究

利用扫描电镜观察了 4个小麦品种 (系 )的籽粒断面 ,分析了 2 6个小麦品种的加工品质性状。结果表明 :软麦籽粒断面胚乳薄壁细胞的淀粉粒清晰可见 ,并保持完整状态 ,胚乳结构比较疏松 ;而硬麦籽粒断面胚乳淀粉粒多数破碎 ,胚乳结构相对致密。硬麦品种出粉率、粗蛋白含量、沉淀值、面团评价值等性状的平均值均高于软麦品种 ,但软麦的水溶性蛋白质含量平均值高于硬麦品种。籽粒硬度与角质率与多种加工品质性状呈显著正相关 ,与水溶性蛋白质呈显著负相关 ,因而硬度作为硬麦指标比较可靠。试验还发现 ,参试软麦品种中有沉淀值较高的品种出现。     

菠萝蜜果实糖苷酶和多聚半乳糖醛酸酶的活性变化

【目的】研究菠萝蜜果实成熟软化的机制和干、湿苞菠萝蜜质地差异形成的机理,为菠萝蜜育种提供理论基础。【方法】以不同基因型的干苞和湿苞菠萝蜜为材料,以对硝基苯β-D-吡喃半乳糖苷和对硝基苯α-D-吡喃甘露糖苷为底物测定果实成熟软化过程中β-半乳糖苷酶（β-Gal）、α-甘露糖苷酶（α-Man）,以多聚半乳糖醛酸为底物测定多聚半乳糖醛酸酶（PG）的活性变化。【结果】水溶性和盐溶性的β-半乳糖苷酶活性在两个湿苞菠萝蜜基因型中均表现先上升后下降的趋势,分别在采后2 d和采后当天达到最高值,其中,水溶性酶的活性水平分别先上升42.3%、52.8%随后下降22.8%、52.6%,盐溶性酶的活性先上升27.6%、67.7%后下降10.5%、35.4%;水溶性多聚半乳糖醛酸酶活性在两个湿苞菠萝蜜基因型中均表现出直线上升的趋势,酶活性水平增加75.0%、147.3%,而在两个干苞菠萝蜜基因型中则略有增加（增加40.9%）或变化不大;盐溶性的多聚半乳糖醛酸酶和水溶及盐溶性α-甘露糖苷酶在不同基因型的干苞和湿苞菠萝蜜果实中呈现不同的变化趋势。【结论】水溶性和盐溶性β-半乳糖苷酶、水溶性多聚半乳糖醛酸酶在湿苞和干苞菠萝蜜类型间表现出完全不同的变化趋势,而在湿苞或干苞基因型内表现出相同的变化趋势,它们与干湿苞菠萝蜜果实的质地差异形成有关。     

Coupled superconducting and magnetic order in CeCoIn5

Strong magnetic fluctuations can provide a coupling mechanism for electrons that leads to unconventional superconductivity. Magnetic order and superconductivity have been found to coexist in a number of magnetically mediated superconductors, but these order parameters generally compete. We report that close to the upper critical field, CeCoIn5 adopts a multicomponent ground state that simultaneously carries cooperating magnetic and superconducting orders. Suppressing superconductivity in a first-order transition at the upper critical field leads to the simultaneous collapse of the magnetic order, showing that superconductivity is necessary for the magnetic order. A symmetry analysis of the coupling between the magnetic order and the superconducting gap function suggests a form of superconductivity that is associated with a nonvanishing momentum.     

Current-controlled magnetic domain-wall nanowire shift register

The controlled motion of a series of domain walls along magnetic nanowires using spin-polarized current pulses is the essential ingredient of the proposed magnetic racetrack memory, a new class of potential non-volatile storage-class memories. Using permalloy nanowires, we achieved the successive creation, motion, and detection of domain walls by using sequences of properly timed, nanosecond-long, spin-polarized current pulses. The cycle time for the writing and shifting of the domain walls was a few tens of nanoseconds. Our results illustrate the basic concept of a magnetic shift register that relies on the phenomenon of spin-momentum transfer to move series of closely spaced domain walls.     

软、硬鳞瓯江彩鲤鳞片生化成分比较

瓯江彩鲤(Cyprinus carpio var.color)鳞片存在软鳞和硬鳞两种形式。采用生化方法测定了这两种类型鳞片的生化成分。结果表明,软鳞鳞片中水分含量(54.94%)显著高于硬鳞鳞片(46.67%),P0.05。在干物质中,软、硬鳞鳞片粗蛋白含量分别为79.84%和82.57%、灰分含量分别为17.18%和14.84%,均存在显著性差异(P0.05);粗脂肪含量分别为2.09%和2.06%,差异不显著(P0.05)。瓯江彩鲤鳞片中共检测到16种氨基酸,除赖氨酸(Lys)外,软鳞鳞片中其余单个氨基酸含量均低于硬鳞鳞片中氨基酸含量,硬鳞鳞片中必需氨基酸总量显著高于软鳞鳞片(P0.05)。瓯江彩鲤鳞片水分含量的多少对鳞片的软硬程度可能有较大影响,而鳞片干物质中蛋白质、灰分所占的比例可能也是影响瓯江彩鲤鳞片软硬程度的重要因素。     

黄柏大棚轻基质播种育苗技术

本文阐述了黄柏大棚轻基质播种育苗技术,包括合理配备基质、科学防治病虫害、合理的日常管理等方面内容,以期培养出更多合格的苗木。     

栗钙土钙积层扰动对土壤物理性质和作物产量的影响

通过田间试验方法,研究探索人工扰动（深耕深松）干旱栗钙土钙积层对土壤水分、物理性状和作物产量的影响,试验结果表明,深松可破除坚硬的钙积层,使土壤变松软,土壤硬度减小,可降低土壤容重,深松后0～80cm土层的土壤容重减小0．03g/cm^3,可使下层土壤疏松、降水渗入率增高,提高土壤水分的保蓄能力,从而增加作物产量和降水利用效率。     

Diet-induced head allometry among foliage-chewing insects and its importance for graminivores

Individuals of the grass-feeding caterpillar of Pseudaletia unipuncta, reared from hatching on hard grass, had head masses twice as great as those of caterpillars fed soft artificial diet, even though the larvae reached the same body mass. Larvae reared on soft wheat seedlings had intermediate head masses. Thus muscular effort increases muscular development in an insect, which in turn has a dramatic morphogenetic effect on head size. Size differences in the head capsules, with the correlated differences in mandibular power, have a direct effect on the ability of the insects to ingest hard foods rapidly: larger heads are adaptive for dealing with hard grasses.     

Dynamics of magnetic domain walls under their own inertia

The motion of magnetic domain walls induced by spin-polarized current has considerable potential for use in magnetic memory and logic devices. Key to the success of these devices is the precise positioning of individual domain walls along magnetic nanowires, using current pulses. We show that domain walls move surprisingly long distances of several micrometers and relax over several tens of nanoseconds, under their own inertia, when the current stimulus is removed. We also show that the net distance traveled by the domain wall is exactly proportional to the current pulse length because of the lag derived from its acceleration at the onset of the pulse. Thus, independent of its inertia, a domain wall can be accurately positioned using properly timed current pulses.     

Jupiter's Magnetosphere: Plasma Description from the Ulysses Flyby

Plasma observations at Jupiter show that the outer regions of the Jovian magnetosphere are remarkably similar to those of Earth. Bow-shock precursor electrons and ions were detected in the upstream solar wind, as at Earth. Plasma changes across the bow shock and properties of the magnetosheath electrons were much like those at Earth, indicating that similar processes are operating. A boundary layer populated by a varying mixture of solar wind and magnetospheric plasmas was found inside the magnetopause, again as at Earth. In the middle magnetosphere, large electron density excursions were detected with a 10-hour periodicity as planetary rotation carried the tilted plasma sheet past Ulysses. Deep in the magnetosphere, Ulysses crossed a region, tentatively described as magnetically connected to the Jovian polar cap on one end and to the interplanetary magnetic field on the other. In the inner magnetosphere and lo torus, where corotation plays a dominant role, measurements could not be made because of extreme background rates from penetrating radiation belt particles.     

家居“软装”空间探析

解读了家居＂软装＂空间的定义,分析出＂软装饰＂可达到藏拙露巧、空间重划、空间重组、空间填充的目的,从而弥补家庭硬质装修的不足,起到细化家居空间、完善家居空间功能等作用。说明＂轻装修、重装饰＂将是家居装修新的发展方向。