Diameter graphs of polygons and the proof of a conjecture of Graham

We show that for an n-gon with unit diameter to have maximum area, its diameter graph must contain a cycle, and we derive an isodiametric theorem for such n-gons in terms of the length of the cycle. We then apply this theorem to prove Graham's 1975 conjecture that the diameter graph of a maximal 2m-gon (m?3) must be a cycle of length 2m−1 with one additional edge attached to it.     

半导体中多光子吸收跃迁速率的全量子理论分析

本文从非线性光学中辐射跃迁速率的表达式出发,在全量子理论下,导出了半导体中任意阶多光子吸收跃迁速率的一般表达式。理论分析结果表明,n光子吸收跃迁速率与光强的n次方和n阶光子相干度成正比。本文在多能带及二能带理论模型下,对多光子吸收跃迁速率的一般表达式进行了化简,并对非线性相互作用项对跃迁速率的贡献,作了讨论。     

Mixed methods on quadrilaterals and hexahedra

We describe a new family of discrete spaces suitable for use with mixed methods on certain quadrilateral and hexahedral meshes. The new spaces are natural in the sense of differential geometry, so all the usual mixed method theory, including the hybrid formulation, carries over to these new elements with proofs unchanged. Because transforming general quadrilaterals into squares introduces nonlinearity and because mixed methods involve the divergence operator, the new spaces are more complicated than either the corresponding Raviart-Thomas spaces for rectangles or corresponding finite element spaces for quadrilaterals. The new spaces are also limited to meshes obtained from a rectangular mesh through the application of a single global bilinear transformation. Despite this limitation, the new elements may be useful in certain topologically regular problems, where initially rectangular grids are deformed to match features of the physical region. They also illustrate the difficulties introduced into the theory of mixed methods by nonlinear transformations.     

负电子亲和势GaAs光电阴极中的三光子激发和发射的理论研究

将三阶微扰理论应用于单晶GaAs半导体,结合与实际相接近的能带结构,得到了GaAs中三光子吸收系数的解析式表达式,在考虑了激发电子的逃逸过程的情况下,进而推导了负电子亲和势GaAs光电阴极中三光子光电发射的发射系数的解析表达式.两表达式得到的理论数值分别与用ns量级脉宽、2.06μm波长的激光测得的GaAs中三光子吸收系数和GaAs(Cs,O)光电阴极中三光子发射系数的实验值相比较,吻合较好.     

Determination of tributyltin oxide in coastal marine sediments and mussels by electrothermal atomic absorption spectrometry

We have devised a new method for bis(tributyltin)oxide (TBTO) determination in marine sediments and mussels. This technique involves an n-hexane/methylene chloride mixture extraction and extract purification with a sodium hydroxide wash in order to eliminate interfering compounds. TBTO is then extracted again by nitric acid and converted into an inorganic tin species; the analysis has been effected using Zeeman graphite furnace-atomic absorption spectrophotometry. The method detection limit for the matrices examined is 0.004 μg TBTO g^?1 (wet weight) and is sufficient for the analysis in real samples. The percentage recovery of TBTO from sediments and mussels samples is higher than 85% and 95% respectively. This method has been applied to TBTO level determination in sediments and mussels (Mytilus galloprovincialis) sampled in the harbour area in Taranto, where mussel culture activities are much developed; the TBTO levels obtained in sediments and mussels were in the range 15-47 ng g^?1 (wet weight) and 11-30 ng g^?1 (wet weight) respectively. Such values are comparable with those found in other harbour areas in the Mediterranean Sea.     

Preparation and microwave absorption properties of electroless Co-Ni-P coated strontium ferrite powder

A new type of Co-Ni-P coated strontium ferrite nanocomposite was prepared with electroless plating enhanced by ultrasonic wave at room temperature. The plating process was studied carefully. The morphology, crystal structure and microwave absorption properties of the Co-Ni-P coated powder were studied with field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), energy dispersive analysis of X-rays (EDX) and vector network analyzer. The results show that the strontium ferrite powder was successfully coated with Co-Ni-P alloy and possesses excellent microwave absorption properties. The maximum microwave loss of the composite powder reaches −44.12 dB. The bandwidth with the loss above −10 dB exceeds 13.8 GHz.     

三角帆蚌对水体Cr,Pb和Cd的净化与吸收

三角帆蚌（Hyriopsis cumingii Lea）对水体Cr,Pb,Cd污染有明显的净化能力，持续处理12d，能使水体Cr,Pb,Cd含量分别下降83％，77．6％和72％。蚌体的斧足、鳃、外磁膜、体表粘液、肝脏、肠道和生殖腺等组织对3种污染物的吸收和富集作用不尽相同，其中分别以体表粘液、鳃和肝脏最为显著。3种污染物进入蚌体的速度很快，其组织吸收量一般在第3天即可达到较高水平。进入蚌体的污染物，可在组织转移和重新分布。研究结果为生物治理Cr,Pb,Cd等重金属污染积累了资料。     

氯代5-氟脲嘧啶卟啉的红外光谱特性的研究

本文对新合成的对位及间位两类氯代苯基 5 氟脲嘧啶卟啉的红外光谱吸收峰进行了归属和总结 ,讨论了其红外吸收频率随取代基位置变化的规律。指出了苯环上的取代基为电负性强的基团时 ,由于场效应的存在 ,使被测化合物的羰基伸缩振动吸收峰的相对强度发生改变。同时 ,表明了嘧啶环上N原子发生了取代 ,形成单、双取代 5 氟脲嘧啶卟啉化合物的红外光谱特性。     

Solitary wave solutions of nonlinear financial markets :data-modeling-concept-practicing

This paper seeks to solve the difficult nonlinear problem in financial markets on the complex system theory and the nonlinear dynamics principle, with the data-model-concept-practice issue-oriented reconstruction of the phase space by the high frequency trade data. In theory, we have achieved the differentiable manifold geometry configuration, discovered the Yang-Mills functional in financial markets, obtained a meaningful conserved quantity through corresponding space-time non-Abel localization gauge symmetry transformation, and derived the financial solitons, which shows that there is a strict symmetry between manifold fiber bundle and guage field in financial markets. In practical applications of financial markets, we have repeatedly carried out experimental tests in a fluctuant evolvement, directly simulating and validating the existence of solitons by researching the price fluctuations (society phenomena) using the same methods and criterion as in natural science and in actual trade to test the stock Guangzhou Proprietary and the futures Fuel Oil in China. The results demonstrate that the financial solitons discovered indicates that there is a kind of new substance and form of energy existing in financial trade markets, which likely indicates a new science paradigm in the economy and society domains beyond physics.