Two-dimension fluorescence correlation spectroscopy to characterize the binding of organic ligands with zinc in eutrophic lake

Metal binding of organic ligands can definitely affect its environmental behavior in waters, while information on the binding heterogeneity with different organic ligands is still lacked till now. In this study, the binding of zinc with organic matters associated with cyanobacterial blooms, including dissolved organic matters (DOM) and attached organic matters (AOM), were studied by using fluorescence quenching titration combined with two-dimensional correlation spectroscopy (2D-COS). Metal-induced fluorescent quenching was obviously observed both for DOM and AOM, indicating the formation of metal-ligand complexes. Compared with the one-dimensional spectra, 2D-COS revealed the sequences of metal-ligand interaction with the following orders: 276 nm > 232 nm for DOM and 232 nm > 276 nm for AOM. Furthermore, the modified Stern-Volmer model showed that the binding constant (log KM) of 276 nm in DOM was higher than that of 232 nm (4.93 vs. 4.51), while AOM was characterized with a high binding affinity for 232 nm (log KM: 4.83). The ranks of log KM values were consistent with the sequential orders derived from 2D-COS results both for the two samples. Fluorescence quenching titration combined with 2D-COS was an effective method to characterize the metal-ligand interaction.     

Structural and spectroscopic properties of trans-difluoro(1,4,8,12-tetraazacyclopentadecane)chromium(III) perchlorate hydrate

The structure of [CrF(2)([15]aneN(4))]ClO(4).H(2)O ([15]aneN(4)=1,4,8,12-tetraazacyclopentadecane) has been determined by a single-crystal X-ray diffraction study at 173 K. The complex crystallizes in the space group P1- of the triclinic system with two mononuclear formula units in a cell of dimensions a=9.6117(7) A, b=10.2882(7) A, c=11.0001(7) A and alpha=99.7570(10) degrees, beta=105.6080(10) degrees and gamma=113.7130(10) degrees. The complex cation unit has its central Cr atom in an octahedral coordination with four nitrogen atoms and two fluorine atoms in a trans position. Three six-membered and one five-membered chelate rings of the [15]aneN(4) ligand are in a chair-twist(skew)-chair-gauche conformation sequence. The gauche five-membered ring is disordered with the twist six-membered ring opposite. The four H atoms in the chiral N atoms have the trans-II (CTCg) type configuration. The mean Cr-N and Cr-F bonds are 2.095(2) and 1.8752(13) A, respectively. The IR and visible spectral properties are consistent with the result of X-ray crystallography. The resolved band maxima of the electronic d-d spectrum are fitted with secular determinant for quartet state energy of d(3) configuration in tetragonal field including configurational but neglecting spin-orbit coupling. It is confirmed that the fluoride has strong sigma- and pi-donor properties toward the chromium(III) ion and the nitrogen atoms of the [15]aneN(4) ligand also have a strong sigma-donor character.     

Spectral analysis of the UFBG-based acousto optical modulator in V–I transmission matrix formalism

In this study, the V-I transmission matrix formalism （V-I method） is proposed to analyze the spectrum characteristics of the uniform fiber Bragg grating （FBG）-based acousto--opfic modulators （UFBG-AOM）. The simulation results demon- strate that both the amplitude of the acoustically induced strain and the frequency of the acoustic wave （AW） have an effect on the spectrum. Additionally, the wavelength spacing between the primary reflectivity peak and the secondary reflectivity peak is proportional to the acoustic frequency with the ratio 0.1425 nm/MHz. Meanwhile, we compare the amount of calculation. For the FBG whose period is M, the calculation of the V-I method is 4 × （2M-l） in addition/subtraction, 8 × （2M - 1） in multiply/division and 2M in exponent arithmetic, which is almost a quarter of the multi-film method and transfer matrix （TM） method. The detailed analysis indicates that, compared with the conventional multi-film method and transfer matrix （TM） method, the V-I method is faster and less complex.     

钴(Ⅱ)(C_(2v))配合物电子光谱的强场处理及AOM参量计算

应用强场近似拟合了10个假四面体Co(Ⅱ)(C_(2γ))配合物的配体独场光谱,由拟合得到的单电子矩阵元得到了各个配体的AOM参量。结果说明各配体的AOM参量同该配体与金属离子之间的配键强度相关。     

Chemical Bonding in Molecules and Complexes Containing d-Elements Based on DFT

Summary. Metal–ligand bonding in transition metal halide molecules and complexes with different central ions, oxidations states, and coordination numbers: Cr^IIIX₆^3–, Cr^IVX₄, Cr^IIX₂ (X = F,Cl,Br,I), M^IIICl₆^3–(M = Mo,W), M^III(H₂O)₆³⁺(M = Cr,Co) and Re₂Cl₈^2– has been studied in terms of the Extended Transition State (ETS) energy patitioning scheme within the DFT and electron density analysis (the Laplacian of the electron density and the electronic localization function). Bonding is found to be dominated by ionicity in all cases, especially so for complexes with higher coordination numbers. Covalent contributions to the metal–ligand bond are found to be mainly due to the nd-electrons and to lesser extent due to the metal (n+1)s and (n+1)p-orbitals, contributions from (n+1)s increasing when going to lower coordination numbers. Metal–ligand bonding analysis have been used in order to check some concepts emerging from ligand field theory when applied to the spectroscopy and magnetism of transition metal complexes. It is pointed out that for complexes of high symmetry (MX₆, O_h, MX₄, T_d, and MX₂, D_h) electron density analyses gain interpretative power when partitioned into contributions from occupied orbitals of different symmetry.     

Dynamic control of a phase-shifted FBG through acousto-optic modulation

When an acoustic wave excites a phase-shifted fiber Bragg grating (PSFBG) several properties of the transmission/reflection spectrum, such as transmission notch depth and spectral bandwidth are influenced. In this work, a study on the effect of acoustic waves in PSFBGs is presented. The results are supported by theoretical simulation and experimental work. The technique can be used for different applications, such as in a fast tunable optical notch filter.     

Laser Diode Pumped Unidirectional Ring Laser Resonator with AOM Q-switch

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Allicin inhibits mouse colorectal tumorigenesis through suppressing the activation of STAT3 signaling pathway

Allicin is the major biologically active compounds of freshly crushed garlic. It has been reported to inhibit the proliferation and promote the apoptosis of multiple colorectal cancer cells. However, the anti-colorectal cancer effect of Allicin has not been verified by in vivo studies. In the present study, we investigated the effect of Allicin on azoxymethane/dextran sodium sulfate (AOM/DSS) colorectal cancer mouse model and explore the underlying possible mechanism. Our result showed that Allicin could inhibit colonic tumorigenesis of AOM/DSS mice in vivo. In vitro study showed that Allicin promoted the apoptosis and suppressed the survival and proliferation of HCT116 cells. The molecular mechanism is related to the suppression of STAT3 signaling activation. Thus, our data provide further support for Allicin as a potential favorable supplement for human colorectal cancer.     

激光多普勒测量自适应陷波器去噪研究

针对激光多普勒测量中声光调制、电光调制等引入的多频率噪音干扰,提出一种兼顾收敛性、鲁棒稳定性的自适应陷波器去噪方法.并在时域内研究自适应陷波器算法及其构造,最后给出了仿真实例.该算法不需具体的激光多普勒测试系统模型,方法简单,易于实现,试验结果表明了该方法的有效性.     

EGCG棕榈酸酯的制备、结构及其抗氧化活性

通过表没食子儿茶素—3—O—没食子酸酯(EGCG)与棕榈酰氯的酯化制备脂溶性的EGCG棕榈酸酯，利用高速逆流色谱对其进行分离和纯化，获得一种新的单取代的长碳链酰基儿茶素—表没食子儿茶素—3—O—没食子酸—4′—棕榈酸酯，并对其分子结构进行了元素分析、IR、MS和^1H—NMR等表征，用活性氧法(AOM)考察并比较了脂溶性的表没食子儿茶素—3—O—没食子酸—4′—棕榈酸酯和特丁基—4—羟基茴香醚(BHA)、2，6—二特丁基对甲酚(BHT)、叔丁基对苯二酚(TBHQ)在大豆色拉油中的抗氧化活性。结果表明，单取代的EGCG棕榈酸酯的抗氧活性与TBHQ相当，而比BHA、BHT有更强的活性。