Eddy diffusion coefficients and the variance of the atmosphere 30–60 km

The results of numerical models or of new observational programs are checked by comparing them with past observations. Also, it is desirable that the eddy diffusion coefficients used in two-dimensional models be derived from the same data set as the circulation statistics which the model outputs are checked against, so that all results refer to the same atmospheric conditions. For the first time, the three components of the eddy diffusion matrix, from 30–60 km, 80°N–10°S are computed, together with the means, variances and covariances of the wind and temperature through the same region using the same data set for 1960–76 and the same handling and analysis methods for all variables. Horizontal diffusivities,K _yy , are obtained from the variance and integral time scale of the meridional wind speed. The present values are generally smaller than past estimates, presumably because temporal variations longer than a month have been removed in this work. Estimates ofK _yz are based on the tentative assumption that the diffusivity is proportional to the slope of isentropic surfaces, and estimates ofK _zz are based on the assumption that small-scale gravity waves are primarily responsible for vertical mixing.     

C60,Cn及其衍生物的研究进展和地质学意义

Ｃ６０晶体是碳元素的第三种同质异构体，Ｃ６０，Ｃｎ及其衍生物有许多新奇的物理化学特性。本文介绍了运用高新测试分析技术深入研究这类新材料结构、物化特性、合成提纯条件及开发高科技新材料产品的前景；探讨了利用天然石墨、各种煤炭等提取合成一些重要价值的Ｃ６０，Ｃｎ及衍生物产品的可行性。     

中国东部中生代钾质火成岩研究中的几个问题

本文探讨当前中国东部中生代钾质火成岩研究中存在的几个问题，即：“C型埃达克岩”的成因、无负Eu异常粗面岩—正长岩的成因、火成岩组合的K60值推算造山带地壳厚度的可信度，和玄武岩构造环境判别图解对中国东部中生代钾质基性岩的适用性。本文认为：①中国东部中生代“C型埃达克岩”有多种成岩过程，并非仅仅源于下地壳物质的部分熔融。②加厚下地壳部分熔融不能形成无负Eu异常的粗面岩—正长岩，同时“C型埃达克岩”与玄武质岩石高压条件下部分熔融产物在钾含量方面具有显著的差别。③火成岩组合的K60值不能用于估算中国东部中生代造山带地壳厚度。④一些常用的玄武岩构造环境地球化学判别图解并不适用于中国东部中生代钾质基性岩。     

A locally conservative Eulerian–Lagrangian numerical method and its application to nonlinear transport in porous media

Eulerian-Lagrangian and Modified Method of Characteristics (MMOC) procedures provide computationally efficient techniques for approximating the solutions of transport-dominated diffusive systems. The original MMOC fails to preserve certain integral identities satisfied by the solution of the differential system; the recently introduced variant, called the MMOCAA, preserves the global form of the identity associated with conservation of mass in petroleum reservoir simulations, but it does not preserve a localized form of this identity. Here, we introduce an Eulerian-Lagrangian method related to these MMOC procedures that guarantees conservation of mass locally for the problem of two-phase, immiscible, incompressible flow in porous media. The computational efficiencies of the older procedures are maintained. Both the original MMOC and the MMOCAA procedures for this problem are derived from a nondivergence form of the saturation equation; the new method is based on the divergence form of the equation. A reasonably extensive set of computational experiments are presented to validate the new method and to show that it produces a more detailed picture of the local behavior in waterflooding a fractally heterogeneous medium. A brief discussion of the application of the new method to miscible flow in porous media is included. This revised version was published online in July 2006 with corrections to the Cover Date.     

模拟热浪天气对冠心病影响及其机理实验研究

通过模拟热浪天气对冠心病小鼠影响实验研究,探讨高温热浪对冠心病影响的机理.应用TEM1880气象环境模拟箱模拟一次实际的热浪天气过程,按体重大小将18只冠心病小鼠分配至6个区组,每个区组3只,再将3只小鼠随机分配到对照组、热浪组、热浪BH4组中,每组共有6只小鼠.放入模拟箱内,使其受热浪天气影响,模拟热浪天气结束后,采用断头采血和摘取心脏,测量各组小鼠的ET-1、NO、HSP60、SOD、TNF、sICAM-1和HIF-1α的含量.结果表明,热浪天气可导致冠心病小鼠心肌组织SOD活性明显下降,而NO、HSP60、TNF、sICAM-1和HIF-1α的含量增加,但对ET-1水平没有任何影响.通过各项生化指标分析得知,热浪可诱导冠心病小鼠心肌组织HSP60含量明显增加,过多的HSP60可以活化免疫细胞,诱导内皮细胞、巨噬细胞分泌大量ICAM-1、TNF-α等炎性细胞因子,进而激活体内炎症系统,破坏冠状血管内皮细胞结构,使血管内膜通透性增高,心脏组织SOD活性下降,使氧化血液中的脂蛋白加剧,大量的胆固醇加速了胆固醇穿透内膜在血管内壁上的沉积,形成动脉粥样硬化,致使冠心病病情加重;从而诱导ICAM-1、血栓素等血管活性物增加,造成血粘度增加,促使血栓的形成;抑制脂蛋白酯酶活性,诱导脂质浸润血管内膜,形成动脉硬化斑块,同时控制巨噬细胞的胆固醇代谢,利于脂质物质沉积于血管壁而增加冠脉疾病风险.该实验是高温热浪导致冠心病病情加重,甚至死亡的初步机理研究成果,可为我国高温热浪预警服务和冠心病防御等提供理论依据.     

Seakeeping standard series for oblique seas (a synopsis)

The seakeeping performance in oblique seas for a series of 72 cruiser-stern hull forms has been evaluated analytically and is presented in a systematic way. The hull form series have been created by Loukakis and Chryssostomidis (1975) by extending the principal characteristics of the Series 60 to cover usual shipbuilding practice. In that work, however, only the seakeeping performance in head seas was presented. Recently, the seakeeping performance of the Extended Series 60 was re-evaluated for both head seas and oblique seas. The complete results are presented in tabular and graphical form as a function of the principal characteristics of the ship, the Froude number (including Fn=0, missing in the original series), the non-dimensional modal wave period and the heading angle in a separate NTUA report (Grigoropoulos et al., 1994). In the present paper, the results for one case are given in tabular form accompanied by graphical representation. They include: heave, pitch, bending moment amidships, added resistance, absolute vertical acceleration and relative vertical motion at the bow and the stern regions and relative vertical velocity at stations 2 and 4 where slamming is likely to occur.     

Entrainment of fine-grained surface deposits into new ice in the southwestern Kara Sea,Siberian Arctic

The entrainment of bottom deposits (silt and clay) into newly formed ice was investigated in the Amderma/Vaygach flaw lead in the southwestern Kara Sea, Siberian Arctic. Fine-grained bottom deposits and sea ice sediments (SIS) were analyzed by granulometry, scanning electron microscopy and X-ray diffractometry. On average, SIS contain by a factor of four times more silt than the shelf deposits (66.7% vs. 16.3%), and the SIS clay percentage is more than three-fold of the bottom value (31.2% vs. 9.1%). Sand-sized particles are significantly less abundant in SIS compared to bottom sediment (2.1% vs. 74.6%). The preferred entrainment of silt into ice is underpinned by the enhanced silt-to-clay-ratio in SIS compared to bottom deposits. Though silt is preferably entrained into SIS, no evidence was found for preferential ice-entrainment of any silt sub-fraction (coarse, medium or fine). However, sub-angular- and angular-discoidal silt particles are favorably entrained into local sea ice. Clay mineral assemblages in SIS and shelf surface sediments match very well revealing that no individual clay mineral is preferably enriched in SIS or reduced at the bottom. The general textural, compositional and statistical match of fine-grained shelf surface deposits and SIS proves that bottom sediment is the principle source for ice-entrained material in the study area. We propose e.g. wave action and thermohaline convection to take sediment particles upward from the bottom nepheloid layer into the well-mixed 10–40 m deep water column of the Amderma/Vaygach flaw lead, and the turbulent process of suspension freezing to bring sediment particles and frazil crystals into contact, finally leading to the formation of sediment-laden ice. The role of SIS entrainment and export for local/regional shelf erosion and coastal retreat is of minor importance in the SW Kara Sea compared to other circum-Arctic shelf seas. However, the characteristic clay mineral assemblage of local SIS and bottom deposits can help identify the origin of SIS both on regional and Arctic-wide scales.     

Antiproliferative and apoptosis-inducing potential of 3β-hydroxy-△5-steroidal congeners purified from the soft coral Dendronephthya putteri

The exploration and identification of antiproliferative phytochemicals have received increased attention in medicinal chemistry. In particular, research focused on the toxicology of marine natural products has increased in recent years. Terpenoids, among many secondary metabolites, have been demonstrated to act as effective anticancer agents. Soft corals, a group of marine invertebrates, produce a variety of terpenoids with biofunctional properties. The current study presents the extraction, purification, and identification of sterol congeners from the soft coral Dendronephthya putteri. The method involves 50% chloroform-methanol extraction, polar column fractionation, and analysis through GC-MSn. Dose-dependent antiproliferative activity was observed within the sterol-rich fraction (DPCMH 2-4), which consisted of 3β-hydroxy-Δ5-steroidal congeners. This fraction inhibited the growth of HL-60 and MCF-7 cells with IC50 values of 25.27±1.43 and 22.81±0.15 μg/mL, respectively. Apoptotic body formation, DNA damage, cell cycle arrest, and apoptotic cell signaling pathway activation were also observed, reinforcing the dose-dependent antiproliferative and apoptosis-inducing activity of 3β-hydroxy-Δ5-steroidal congeners. To our knowledge, this is the first report of anticancer agent identification from the soft coral D. putteri. Based on the observations, these steroidal congeners are promising candidates for the development of anticancer drugs.     

Bifurcation of nonlinear Kelvin wave-CISK with conditional heating in a truncated spectral model: A possible mechanism of 30–60-day oscillation at the equator

In this paper, the nonlinear Kelvin wave equations with “positive-only” nonlinear (conditional) heating at the equator are reduced to a sixth-order nonlinear ordinary differential equation by using the Galerkin spectral truncated method. The stability analysis indicates that when the heating parameter increases, the supercritical pitchfork and Hopf bifurcations can occur for the prescribed three heating profiles. Numerical calculations are made with the help of the fourth-order Rung-Kutta method. It is found that the convec-tion heating-related Hopf bifurcation can lead to limit cycle and chaotic solutions. In a wide range of heat-ing parameter, the solutions possess 30-60-day periods, and are dominated by wavenumbers one and two, especially by wavenurnber-one. In addition, the zonal winds of the low-frequency solutions have a phase reversal between the upper and lower tropospheres. Thus, it appears that the convection heating-related Hopf bifurcation might be a possible mechanism of 30-60-day oscillation in the tropical atmosphere.     

The density functional calculations on the structural and electronic properties of the endohedral fullerene dimer (N2@C60)2

The generalised gradient approximation based on density functional theory is used to study the structural and electronic properties of the endohedral fullerene dimer (N₂@C₆₀)₂. Four N atoms sit at the cage centres in the form of two N_2 molecules. The density of states and Mulliken charge analysis explore that the energy levels from -6 to -10 eV are mainly influenced by the N₂ molecules.