火焰原子吸收光谱法测定废水中重金属的质量控制

火焰原子吸收光谱法测定废水中的重金属含量,具有省时、省力、测定准确度高等特点,但在测定过程中受到外部因素的影响,往往会使测定的结果发生偏离,所以应对外部影响因素采取适当的质量控制措施,以获得准确的测定结果。     

A novel method for blood‐typing using nitrocellulose

Blood wicking in its steady‐state form, i.e. the uniform distribution of blood cells in plasma, is completely different from that in its coagulated form on a porous surface like paper. The hydrophilic property of the cellulose leads to a significant wicking of the blood cells on paper fibers after rinsing with isotonic solution. The difference in the wicking length of the blood cells in steady state and that in the coagulated form could be considered as a criterion to recognize the blood type in a paper‐based kit. However, owing to the molecular structure of the nitrocellulose, a better process occurs while separating the coagulated blood from the steady‐state form of cells. Therefore, it is possible to use the nitrocellulose for the blood‐typing kit which leads to a simpler way to diagnose a blood type. Two series of experiments were performed on nitrocellulose membrane. First, antibody solutions and blood samples were sequentially absorbed on nitrocellulose strips, allowed to interact, rinsed with an isotonic solution and distilled water, and image processing performed on a digital picture of the remaining blood cells. The efficiency of the agglutinated blood cell fixation was quantified by red color intensity. Then, it was demonstrated that there is no considerable difference in fixation of agglutinated blood cells with rinsing using isotonic and nonisotonic solutions. This fact can be a considerable advantage over paper since it can eliminate the probable mistake from using unisotonic solution for rinsing. Second, owing to the nonwicking property of the blood cells on the hydrophobic nitrocellulose fibers, we employed another diagnostic criterion and investigated nitrocellulose blood‐typing prototypes. The nitrocellulose blood‐typing kit provides more simple, sensitive and trustworthy assay for rapid blood typing in situations with no access to laboratory facilities.     

Stable and Low‐Cost Mesoscopic CH3NH3PbI2Br Perovskite Solar Cells by using a Thin Poly(3‐hexylthiophene) Layer as a Hole Transporter

Mesoscopic perovskite solar cells using stable CH₃NH₃PbI₂Br as a light absorber and low‐cost poly(3‐hexylthiophene) (P3HT) as hole‐transporting layer were fabricated, and a power conversion efficiency of 6.64 % was achieved. The partial substitution of iodine with bromine in the perovskite led to remarkably prolonged charge carrier lifetime. Meanwhile, the replacement of conventional thick spiro‐MeOTAD layer with a thin P3HT layer has significantly reduced the fabrication cost. The solar cells retained their photovoltaic performance well when they were exposed to air without any encapsulation, presenting a favorable stability. The combination of CH₃NH₃PbI₂Br and P3HT may render a practical and cost‐effective solid‐state photovoltaic system. The superior stability of CH₃NH₃PbI₂Br is also promising for other photoconversion applications.     

物流成本的推断方法研究

原本方物流成本和第三方物流成本会因各自条件明显欠缺而难以集中并进行会计核算．尽管如此,却可以运用统计方法对它们进行估算,即在理清物流成本结构的基础上,分别对物流需求者和物流经营者总体的有关特征进行抽样推断,进而估算出原本方物流成本和第三方物流成本以及由它们合成的物流供给成本．抽样推断方法具有科学性和可操作性,能有效解决物流成本估算问题,其应用成果为制定物流发展规划或设计物流建设方案提供了依据,为解决物流卫星账户构建之瓶颈问题奠定了重要基础．     

脲基嘧啶酮四氢键二茂铁二聚体:电子相互作用的调控

以脲基嘧啶酮四重氢键为桥联单元,组装了二茂铁同体二聚体(1·1)。电化学实验显示1·1中两个等同的二茂铁基团的氧化还原电位差值(ΔE)达260 mV,说明1·1中两个二茂铁基团间通过四氢键发生了显著的电子相互作用。在1·1/CHCl₃中逐步加入0.5、1和2等摩尔的CF₃COOH时,由于脲基嘧啶酮四氢键的逐步解离,二茂铁间的电子相互作用强度逐渐减弱,其ΔE从260 mV逐步减小至150、100和0 mV,此时再加入三乙胺又可以使电子相互作用逐步恢复至初始状态,说明通过加入质子酸、碱可有效调控四氢键体系中发色团间通过氢键的电子相互作用。     

一种改进的投资组合模型的算法和实证分析

目前,在Markowitz的均值-方差模型基础上对含有偏度和交易成本模型的研究较少,结合国内市场数据进行研究并做出三维投资组合有效前沿图像的成果更少。在建立两种在交易成本约束条件下以方差和偏度的线性组合为目标函数的最优投资组合模型之后,利用线性函数逼近,将模型转换成线性规划问题,而且这种逼近程度可以控制。用单纯形法求解以得到最优投资组合。利用国内八个上市公司的数据进行实证分析,做出了三维投资组合近似有效前沿图像,并讨论了目标函数最优值和参数的关系。可以发现,目标函数是期望r和参数m的增函数。     

考虑使用成本的软件交易方式选择研究

用户使用软件过程中往往需要支付数额不菲的各种成本。永久授权交易方式下,软件使用成本完全由用户负担;软件即服务交易方式下,部分使用成本(如软硬件维护成本)转由软件供应商负担,且供应商借助专业优势通常能压缩其分担的使用成本。对于永久授权和软件即服务两种交易方式,本文分别建立垄断软件供应商的两阶段定价模型,分析用户选择和供应商定价策略,考察软件使用成本、供应商分担部分使用成本及供应商成本压缩在软件交易方式选择中的作用。研究发现,当软件使用成本较高、供应商分担使用成本的比例较大、供应商压缩成本幅度较大时,软件即服务交易方式通常占优;否则,永久授权交易方式通常占优。     

An Enthalpy Control Volume Method for Transient Mass and Heat Transport with Solidification

A single domain enthalpy control volume method is developed for solving the coupled fluid flow and heat transfer with solidification problem arising from the continuous casting process. The governing equations consist of the continuity equation, the Navier–Stokes equations and the convection–diffusion equation. The formulation of the method is cast into the framework of the Petrov–Galerkin finite element method with a step test function across the control volume and locally constant approximation to the fluxes of heat and fluid. The use of the step test function and the constant flux approximation leads to the derivation of the exponential interpolating functions for the velocity and temperature fields within each control volume. The exponential fitting makes it possible to capture the sharp boundary layers around the solidification front. The method is then applied to investigate the effect of various casting parameters on the solidification profile and flow pattern of fluids in the casting process.     

考虑环境成本的能量系统(火用)经济学分析模型

随着可持续发展战略的实施,对传统的(火用)经济学提出了新的挑战。本文在传统佣经济学分析的基础上,将环境成本引入到(火用)经济学分析中,首先提出了“广义子系统”的概念,建立了包括(火用)环境成本平衡在内的各种平衡方程;在系统生产结构的描述中,将系统中的(火用)流划分成外界输入(火用)流、内部(火用)流以及向外界输出(火用)流三类,最终建立了以矩阵形式表示的各种平衡方程,用于求解系统中各股(火用)流的单位(火用)成本、单位(火用)经济成本、单位环境成本、单位综合(火用)经济成本等性能参数。最后针对某国产200MW机组进行了实例计算。