在火焰原子吸收光度计上以无火焰原子化法测定碱金属元素

在常规火焰原子吸收分光光度计上采用特制的不锈钢原子化管对碱金属元素进行无火焰原子化法测定,克服了碱金属元素在火焰中的电离效应,试液用量极少。测定结果的相对标准偏差小于0.3%(n=11),回收率为98.9%~99.2%。     

大跨度采空影响顺倾构造山体侧向变动的复合机理

采空区地表山体侧向变动,不同于一般天然山坡,也与采空区一般上覆岩层的变形破坏有异;它是二者复合机理的效应。本文在分析考察了毗邻电厂的横山顺倾构造山体,剖析了地下采空情况后认为,山体侧向变动中,软弱夹层有决定性作用;变动范围、速率与规模,与地下采空有关。从而又利用地质力学模型试验和数值模拟,探索了采动引起山体应力场及变动规律。结果表明,山体岩层的变形、位移、破坏,由直接顶板向地表发展;采空坍陷诱发了软弱夹层的蠕滑,则产生山体侧向滑移;电厂区地表隆起变形是山体侧向滑移挤压地基土的反映。通过现场实际调究、变形观测资料分析与数值模拟和模型试验的对比研究,提出了“坍落拱梁”的成生效应、挤压蠕滑效应、失稳效应;揭露了顺倾构造山体在采空影响下,具有地表、地下的“复合临空面”的“复合应力场”中“复合变动”的“复合机理”;并提出这种山体侧向变动机理的典型地质模式,借以论证山体稳定性。     

用泵浦剩余能量放大F-P腔光纤激光器

本文报道了利用在腔外附加掺何光纤的方法放大双波长F-P腔掺辉光纤激光器的输出功率,使其输出功率分别达到-1.60dBm和-6.64dBm,增益分别为6dB和0.62dB,信噪比分别为45dB和40dB.这种方法可以用于在全光纤波分复用通信系统中提高光源的输出功率,特别是使泵浦源的能量得到了充分利用。     

Thapsigargin的全合成研究进展

Thapsigargin是一类从地中海植物毒胡萝卜(thapsia garganica)中分离得到的结构复杂的高氧化态倍半萜内酯,其对肌浆-内质网Ca~(2+)-ATP泵(SERCAs)具有不可逆的抑制作用,抑制浓度达纳摩尔级别(KD=0.4 nmol/L)。Thapsigargin因其独特的结构和良好的生物活性而备受有机合成化学家的广泛关注。在合成中,立体选择性地构建该分子cis-5/7/5稠环体系以及多个手性中心是极具挑战性的。本文综述了该分子近二十年来的全合成研究进展。     

Wallichanol类天然产物ABC环系合成研究

Wallichanol是一类具有独特桥环结构的二萜天然产物.以2-甲基-1,3-环己二酮作为起始原料,通过高立体选择性的Diels-Alder反应和金催化的炔烃碳环化反应构建Wallichanol的ABC三环核心骨架,共七步路线,总收率为42%.该合成工作为Wallichanol类天然产物全合成奠定了研究基础.     

等效电路计算同轴输出腔TM310模式的间隙阻抗

设计了外Q值较小,工作于高阶横磁TM310模的X波段速调管单间隙同轴输出谐振腔。用微波等效电路理论计算了高阶横磁TM310模情形六个漂移管的等效间隙中心位置,由此计算腔内等效间隙中心到输出波导内横向膜片的等效长度。以MATLAB编程计算得到同轴谐振腔TM310模式加载矩形波导滤波器输出回路的间隙阻抗,其结果与传统冷测模拟法计算结果吻合。验证了等效长度计算方法的正确性,用于圆柱腔基模的传统微波等效电路理论能用于分析同轴谐振腔高阶横磁模式输出回路,且比传统的冷测模拟法及场分析法更为快捷。     

On a generalized Cournot oligopolistic competition game

We consider a model whereby players compete for a set of shared resources to produce and sell substitute products in the same market, which can be viewed as a generalization of the classical Cournot oligopolistic competition model, or, from a different angle, the Wardrop type routing model. In particular, we suppose that there are K players, who compete for the usage of resources as well as the sales of the end-products. Moreover, the unit costs of the shared resources and the selling prices of the products are assumed to be affine linear functions in the consumption/production quantities. We show that the price of anarchy in this case is lower bounded by 1/K, and this bound is essentially tight, which manifests the harsh nature of the competitive market for the producers.     

Stress and bubble pressure response of wet foam to continuous and oscillatory sinusoidal shear

The European Physical Journal E - Recent theories of drag reduction in wall turbulence assumed that the presence of the polymer leads to an effective viscosity, which increases linearly with the...     

Functionalization of thermally reduced graphene by in situ atom transfer radical polymerization

In this report, functionalization of functionalized graphene sheets (FGS) was carried out by atom transfer radical polymerization (ATRP). Poly(methyl methacrylate) (PMMA) or polystyrene (PS) was successfully grafted from FGS. Thermogravimetric analysis (TGA) was used to estimate the content of linked organic compound. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) were used to observe the morphologies of the hybrid materials obtained. This approach was proved to be an effective way for functionalizing the graphene and tailoring the polymer structures.