Post-perovskite phase transition in MgSiO3

In situ x-ray diffraction measurements of MgSiO3 were performed at high pressure and temperature similar to the conditions at Earth's core-mantle boundary. Results demonstrate that MgSiO3 perovskite transforms to a new high-pressure form with stacked SiO6-octahedral sheet structure above 125 gigapascals and 2500 kelvin (2700-kilometer depth near the base of the mantle) with an increase in density of 1.0 to 1.2%. The origin of the D" seismic discontinuity may be attributed to this post-perovskite phase transition. The new phase may have large elastic anisotropy and develop preferred orientation with platy crystal shape in the shear flow that can cause strong seismic anisotropy below the D" discontinuity.     

Continuous plasma outflows from the edge of a solar active region as a possible source of solar wind

The Sun continuously expels a huge amount of ionized material into interplanetary space as the solar wind. Despite its influence on the heliospheric environment, the origin of the solar wind has yet to be well identified. In this paper, we report Hinode X-ray Telescope observations of a solar active region. At the edge of the active region, located adjacent to a coronal hole, a pattern of continuous outflow of soft-x-ray-emitting plasmas was identified emanating along apparently open magnetic field lines and into the upper corona. Estimates of temperature and density for the outflowing plasmas suggest a mass loss rate that amounts to approximately 1/4 of the total mass loss rate of the solar wind. These outflows may be indicative of one of the solar wind sources at the Sun.     

环境激励条件建筑结构的试验建模研究

通过环境激励模态识别技术对一座中高层新结构大楼环境激励试验建模研究。首先介绍了试验模型设计 ,并在现场测量整栋大楼在环境激励下的振动响应。然后采用新发展的频率空间域方法 ( FSDD)进行模态识别 ,分别在 0～ 4.5 Hz和 0～ 6.5 Hz频率范围识别出 9阶弯曲和扭转模态频率和振型。采用频率空间域方法识别了结构的阻尼特性 ,并得到满意的结果。所得试验模型已成功应用于 CFT大楼的有限元动态模型修正。所研发的试验建模技术可望在结构响应预报 ,健康监测和振动控制中发挥重要作用     

Elevation in brain temperature during paradoxical sleep

During ordinary sleep, the temperature of the rabbit brain tended to drop, but during paradoxical sleep it rose sharply 0.1 degrees to 0.4 degrees C, a greater elevation than was observed during arousal. Changes in body temperature generally did not parallel the alterations in brain temperature. Shifts of direct-current potential in the brain are basically independent of the changes in brain temperature.     

Induction of 12-chromosome plants from anther culture in a tuberousSolanum

Summary Haploid plants (2n=12) were produced by anther culture from the tuber-bearing wild speciesS. verrucosum.     

Application timing of asulam for torpedograss (Panicum repens L.) control in sugarcane in Okinawa island

Field and glasshouse experiments were conducted from 1995 through 1996 to evaluate application timing of asulam (methyl sulfanilylcarbamate) for torpedograss (Panicum repens L.) control in relation to plant age in sugarcane. Above‐ground shoots of torpedograss were completely controlled with asulam at 2–4 kg active ingredient (a.i.) ha^?1 applied 60 or 80 days after planting (DAP) in artificially infested pots. But some newly developed rhizome buds survived after asulam application resulting in 1–25 and 76–100% or more regrowth in 60 and 80 DAP‐applied pots, respectively. Whereas the herbicide at 2–4 kg a.i. ha^?1 applied within 60 DAP completely controlled above‐ground shoots, applied 80 DAP at 2 kg a.i. ha^?1 it did not completely control the weed in the artificially infested field. Regrowth levels were 1–25 and 76–100% or more in 60 and 80 DAP‐applied plots, respectively. Asulam at 2–3 kg a.i. ha^?1 applied 20, 40, 60 or 80 DAP in a naturally infested field completely controlled above‐ground shoots and regrowth levels were 76–100 or more, 51–75, 1–25 and 26–50% in these same DAP applied plots, respectively. The herbicide applied at 4 kg a.i. ha^?1 caused chlorosis on younger sugarcane leaves (one‐leaf stage), but when applied at 2–3 kg a.i. ha^?1, no injury symptoms were shown. The herbicide at 2–4 kg a.i. ha^?1 applied within 60 DAP resulted in remarkably higher yield and shoot biomass of sugarcane than that applied 80 DAP. This study suggested that asulam at 2–3 kg a.i. ha^?1 should be applied 60 days after planting for the maximum control of torpedograss regrowth and better yield of sugarcane. This study also indicated that torpedograss cannot be completely controlled with a single application of asulam in a naturally infested field because of rhizome fragmentation by cross plowing and distribution of rhizomes into different soil layers that require different times to emerge. The shoots emerging after asulam application could not be controlled. Another study is required to determine the interval between sequential applications of asulam for better control of torpedograss in a naturally infested field.     

Evaluation of biological activities of extracts from 22 African tropical wood species

Heartwoods of 22 African tropical wood species were extracted with methanol and the contents of total phenolic compounds in these extracts were measured. Three bioassays were conducted to evaluate the antioxidant activity, tyrosinase inhibitory activity, and antifungal activity of the methanol extracts. The results indicated that the extracts from 13 species exhibited high antioxidant potential, and their inhibitory concentrations that caused 50% scavenging of the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical (IC₅₀) were less than 10 μg/ml. The crude extract from Cylicodiscus gabunensis showed the highest antioxidant activity, and was even higher than that of (+)-catechin, which is known as a potent antioxidant. There was a good correlation between the antioxidant activity and the content of total phenolic compounds, indicating that phenolic compounds played a predominant role in the antioxidant property of the wood extracts. Among all 22 species, only 1 species, Milicia excelsa, contained extractives that showed very high tyrosinase inhibitory activity. The extracts from 9 species showed high antifungal activity. No consistent relationship was observed between the tyrosinase inhibitory activity or antifungal activity and the content of total phenolics in the extracts. Part of this article was presented at the 56th Annual Meeting of the Japan Wood Research Society, Akita, August 2006