Photoreduction of Se(Ⅵ) by Marine Algae-Transitional Metals-Light System

以海洋绿藻(Tetraselmislevis,Chlorellaautotrophica,Dunaliellasalina,Nannochloropsissp.,Tetraselmissubcordi-formis)、硅藻(Phaeodactylumtricornutum)、红藻(Porphyridiumpurpureum)和过渡金属(铁、锰、铜)构建海藻-光二元体系、过渡金属-光二元体系、海藻-过渡金属-光三元体系,对比分析不同海藻、不同过渡金属、海藻与过渡金属耦合引发光化学过程,对Se(Ⅵ)还原转化的贡献率.二元和三元体系均可光还原转化Se(Ⅵ)为Se(Ⅳ).铁、铜、锰通过自身的光氧化还原过程诱发Se(Ⅵ)/Se(Ⅳ)的氧化还原;海藻的光化学活性首次被证实,表面壁可吸附富集海水中还原性的有机物、Se(Ⅵ)/Se(Ⅳ)和过渡金属,改变其氧化还原电位,提供光反应场所;Se(Ⅵ)的光还原转化率依海藻和过渡金属的种类、浓度不同而异;海藻浓度的提高、海藻与过渡金属的耦合作用有利于光还原转化率的提高.通过三元体系的光还原转化,Se(Ⅵ)/Se(Ⅳ)比值为1·17~2·85,接近海洋真光层Se(Ⅵ)/Se(Ⅳ)实际浓度比,即海藻和过渡金属引发的光化学过程对硒的价态分布起决定性作用.Seven marine phytoplankton, including five green algae (Tetraselmis levis, Chlorella autotrophica, Dunaliella salina, Nannochloropsis sp. and Tetraselmis subcordiformis), one diatom (Phaeodactylum tricornutum), one red alga (Porphyridium purpureum), and three usual transitional metals (Fe(Ⅲ), Cu(Ⅱ), Mn(Ⅱ)) were used to make up marine phytoplankton-light or transitional metals-light or marine phytoplankton-transitional metals-light system. In such system, Se(Ⅵ) could be transformed into Se(Ⅳ) by photoreduction. The species transformation of selenium could be photo-induced by redox reaction of transitional metals. The photochemical activity of marine phytoplankton was confirmed for the first time, because marine phytoplankton could adsorb and concentrated of selenium, transitional metals and organic substances (including the exudation of algae, as reducing agent) which redox potentials were changed. The ratios of Se(Ⅵ) to Se(Ⅳ) were dominated by the species, the concentration of marine phytoplankton and transitional metals, and it could be enhanced through increasing the concentration of marine algae or the combined effect from marine algae and transitional metals. After photoreduction by ternary system, the ratio of Se(Ⅵ) to Se(Ⅳ) ranges from 1.17 to 2.85, which is close to the actual value in euphotic layer of seawater. The photochemical process that is induced by marine algae and transitional metals dominative the leading effects on the distribution of oxidation states of selenium.国家自然科学基金资助项目(40131160735);; 福建省科技三项费用项目(K02093);; 福建省青年科技人才创新项目(2003J035);; 福建省教育厅A类项目(JA00233

水源因素与戊型肝炎病毒感染的关联性

目的通过检测浙江省德清县水系上下游地区农村人群血清戊型肝炎病毒抗体水平,以评价非爆发状态下水源因素与戊型肝炎病毒感染的关联性。方法通过统一的调查表收集1 720人的一般资料及可能危险因素,并采用间接酶联免疫吸附法检测血清抗HEV-IgG抗体。结果总标化抗体阳性率为48.79%。其中,上游地区人群标化抗体阳性率为43.52%,下游标化阳性率为51.26%。将两地人群不同的构成特征调整后,下游抗体阳性率仍显著高于上游。同时发现,男性抗体阳性率高于女性;各年龄组阳性率随年龄升高而增加;家庭养猪、喜食猪肝、主要饲养动物和饮酒皆与戊肝感染有统计学关联。结论浙江农村地区戊型肝炎病毒感染情况与当地水源因素有较为显著的关联;猪可能是戊型肝炎病毒的自然宿主之一

Stabilization of anti-aromatic and strained five-membered rings with a transition metal

1981年诺贝尔化学奖获得者、美国康奈尔大学RoaldHoffmann教授评价该项工作说：'The　paper is an excellent one--it's　quite a mazing that the parent Os　system,molecule 1,chooses to give the osmapentalyne'。德国化学家Uwe Rosenthal教授等在同期《自然—化学》杂志的《News and Views》栏目以《Breaking the rules》为题撰文评述了这一研究成果。全文地址：http://www.nature.com/nchem/journal/vaop/ncurrent/pdf/nchem.1702.pdfAnti-aromatic compounds, as well as small cyclic alkynes or carbynes, are particularly challenging synthetic goals. The combination of their destabilizing features hinders attempts to prepare molecules such as pentalyne, an 8π-electron anti-aromatic bicycle with extremely high ring strain. Here we describe the facile synthesis of osmapentalyne derivatives that are thermally viable, despite containing the smallest angles observed so far at a carbyne carbon. The compounds are characterized using X-ray crystallography, and their computed energies and magnetic properties reveal aromatic character. Hence, the incorporation of the osmium centre not only reduces the ring strain of the parent pentalyne, but also converts its Hückel anti-aromaticity into Craig-type Möbius aromaticity in the metallapentalynes. The concept of aromaticity is thus extended to five-membered rings containing a metal–carbon triple bond. Moreover, these metal–aromatic compounds exhibit unusual optical effects such as near-infrared photoluminescence with particularly large Stokes shifts, long lifetimes and aggregation enhancement

First-principles Study of α-Fe Doped With Group-Ⅳ Elements

【中文摘要】 采用基于自旋极化的密度泛函理论的第一性原理方法,使用超原胞模型对Ⅳ族元素掺杂的α-Fe体系α-Fe:X(X=C,Si,Ge)的电子结构和磁学性质进行了系统研究.计算得到了α-Fe体系掺杂前后的能带结构、电子态密度及电荷密度分布等.对计算结果的分析表明:C、Si元素的替位使原胞的体积有所减小,而Ge的替位则导致原胞体积的增大;C和Ge的替位使得电荷密度分布的方向性增强,预示着C和Ge与周围原子相互作用有比较明显的共价性,而Si的替位却对周围电荷密度的影响很小;掺杂时,各替位原子本身基本上都没有表现出磁性,而各Fe原子都保持有磁性,其磁矩都比纯α-Fe中的Fe原子略大. 【英文摘要】 The electronic and magnetic properties of α-Fe doped with group-Ⅳ elements(C,Si,Ge) have been studied by employing the first-principles method based on the spin-polarized density functional theory.The band structures,density of states and electronic charge densities were calculated for both the pure α-Fe and the doped systems α-Fe:X(X= C,Si,Ge).The calculated results showed that:1) the substitution of Fe atom with C or Si leaded to a unit cell volume reduction.The substitution with Ge,on the contrary,leaded...国家自然科学基金项目(10774124

The structural stability and electronic properties of monolayer BC_2 N

【中文摘要】 采用基于密度泛函理论的第一性原理方法,对二维BC2N薄片的结构稳定性和电子性质进行了系统的研究.计算了BC2N化合物16种可能的二维单层结构.对它们的能带结构分析发现,对称性最高的构型与石墨烯一样是一种半金属,而其他二维结构则为有不同带隙的半导体,其中最稳定的构型是带隙值为1.63eV的直接带隙半导体.对最稳定构型的差分电荷密度分析和Bader分析发现:在最稳定的构型中,C—C键、C—N键、C—B键和B—N键主要以共价键的形式呈现,也具有比较明显的离子性.在应力作用下最稳定构型的单层BC2N的带隙宽度会发生变化,压缩时带隙变宽,而拉伸时带隙变窄,但仍然为直接带隙半导体. 【英文摘要】 The structural stability and the electronic properties of two-dimensional monolayer BC2N are studied by employing the first principles method based on the density functional theory.16 polymorphic structures of monolayer BC2N are calculated.Analysis of the 16 band structures suggests that the structure with the highest symmetry is of a semimetal which is the same as graphene.All the other structures are of semiconductors with different band gaps,of which the most stable structure is of semiconductor with a d...国家自然科学基金(批准号:11004165)资助的课

Biomimetic Fluoroimmunoassay for Egg Albumin

利用分子印记技术， 制备了卵清白蛋白（EA） 的人工抗体. 研究了其对抗原的特异性吸附能力， 在此基础上， 模拟竞争型免疫反应， 建立了卵清白蛋白的仿生荧光免疫分析方法.A gel mimetic antibody for egg albumin has been prepared by molecular imprinting and applied to develop a biomimetic fluoroimmunoassay for egg albumin.The format of the assay is analogous to that of the competitive fluoroimmunoassay.The specific binding between the mimetic antibody and antigen(egg albumin) was tested by using egg albumin-FITC,bovine serium albumin(BSA)-FITC and human serium albumin(HSA)-FITC conjugates as fluorescence probes,the results are satisfactory

Structural and electronic properties of hydrogenated bilayer boron nitride

采用第一性原理方法研究了表面氢化的双层氮化硼的结构和电子性质.考虑了表面氢化的双层bn可能存在的六种主要构型,计算结果表明:Ab-bn和AA-bn两种构型最为稳定.进一步分析了氢化后的双层bn最稳定构型的能带和电子性质.Ab-bn和AA-bn两种构型的原子薄片均为直接带隙半导体,ggA计算的带隙值分别为1.47 EV和1.32 EV.因为ggA通常严重低估带隙值,采用HybrId泛函计算得到带隙值分别为2.52EV和2.34 EV.在最稳定的Ab-bn和AA-bn两种构型中,b-n键呈现共价键,而b-H和n-H则具有明显的离子键的特点.在双轴应变下氢化双层bn原子薄片可以被连续地调节带隙,当晶格常数被压缩约8%时,原子薄片由半导体性转变为金属性.The structural and electronic properties of hydrogenated bilayer boron nitride(BN) were studied by employing the frst-principles calculations.Six major polymorphic structures of hydrogenated bilayer BN are considered.Calculated results show that,among them,the AB-BN and AA-BN structures are the most stable ones.The analysis on the energy bands and electronic properties of the two most stable structures are then performed.Structures of AB-BN and AA-BN are both semiconducting with direct band gaps,and the gaps are 1.47 eV and 1.32 eV,respectively,calculated using the GGA method.Since GGA usually severely underestimates the band gap,the hybrid density functional calculations are then conducted,which suggests that the band gaps are 2.52 eV and 2.34 eV for AB-BN and AA-BN structures,respectively.In the most stable structures of AB-BN and AA-BN,B-N bonds show mainly covalent characters,while B-H and N-H bonds exhibit clear ionic characteristics.Moreover,the band gap of hydrogenated bilayer BN atomic sheet can be continuously modulated by biaxial strains.When the lattice constant is compressed by around 8%,the electronic character of the atomic sheet changes from semiconducting into metallic.国家自然科学基金(批准号:11004165;21233004); 福建省教育厅科技项目(批准号:JK2013054)资助的课题~

单粒子在非轴对称八极形变势场中的混沌运动

针对单粒子处在长椭球谐振子势加上Y32+Y3-2形变势场中的情况,从经典和量子两个角度分析了粒子在非轴对称八极形变势场中的混沌运动．通过经典的轨道稳定性分析,指出了系统等势能面性质对粒子运动特点的重要性．又通过对体系存在的能级免交叉现象,三维不对称谐振子相干态在势场中的演化特征的研究,具体地说明了八级形变势的非轴对称性使单粒子更容易出现混沌运动

First-principles Calculations on the Optical Properties of Monolayer MoS_2

采用基于密度泛函理论的第一性原理方法计算了单层和体材料二硫化钼(MOS2)的电子能带结构及光学性质.在能带结构计算的基础上,计算了单层和体材料MOS2的介电函数虚部及实部,并导出了单层MOS2的能量损失谱、吸收系数、反射率、折射率和消光系数等.同时给出了体材料及单层MOS2介电函数图像中各峰值与对应的能带带间跃迁之间的关系.所得结果与实验结果及现有的理论结果相符合.The first-principles method based on the density functional theory has been used to calculate the electronic band structures and the optical properties of monolayer and bulk MoS2.Based on calculated band structures,imaginary and real parts of the dielectric functions are determined.The energy loss spectrum,the absorption coefficient,the reflectivity,the refractive and the extinction coefficient are then calculated on the basis of complex dielectric functions.The relationship between peaks in the dielectric function pictures and the inter-bands transitions in the calculated band structures are pointed out,for both the monolayer and bulk MoS2.Our calculation results are in good agreements with available experimental data and previous theoretic results.国家自然科学基金(10774124;10702056

First-principles calculations of magnetism of Fe atomic sheet

使用基于密度泛函理论的第一原理方法,对fE单层原子薄片在二维正方、二维六角晶格下的电子结构和磁学性质进行了系统研究.结果表明,二维正方、二维六角以及bCC晶格在平衡晶格常数下都具有磁性,其单位原子磁矩分别为2.65,2.54和2.20μВ.对二维晶格在被压缩和被拉伸时的磁性计算表明,随着晶格的被拉伸,当最近邻原子间距大于4.40时,铁原子间的键合被拉断,体系单位原子的磁矩趋于孤立fE原子的磁矩4μВ;随着原子键长的减小,各体系的磁矩都随着最紧邻原子间距的减小而减小.当键长缩短到一定的临界值时(平面正方1.80,平面六角1.75),铁磁性都会消失.使用STOnEr理论,可以理解晶格被缩短时体系由磁性到非磁性的变化.The electronic and the magnetic properties of Fe single-layered atomic shees separately with two-dimensional square and hexagonal structures are calculated by the first-principles method based on the spin-polarized density functional theory.The calculations show that planar square and hexagonal as well as the bcc structures manifest their magnetisms at their equilibrium lattice constants.The magnetic moments for these structures are 2.65,2.54 and 2.20μВ,respectively.The calculated magnetic properties for the elongated and the compressed bond lengths suggest that when the bond is stretched to a length larger than 4.40,the bond should be broken and the magnetic moments of the systems reach the magnetic moment of an independent Fe atom,4μВ.When the bond lengths are reduced,the magnetic moments of all the systems studied decrease correspondingly.At the critical bond lengths(1.80 for planar square lattice,and 1.75 for hexagonal lattice),the magnetisms of the two planar lattices disappear.Using the Stoner theory,the change from magnetism to non-magnetism for the lattice compression is elucidated.国家自然科学基金(批准号:10774124)资助的课题---