A light-harvesting siphonax-anthin-chlorophyll a／b-protein complex of marine green alga, Bryopsis corticulans

A light-harvesting chlorophyll a/b-protein complex (LHCP) was isolated directly from thylakoid membranes of marine green alga, Bryopsis corticulans, by two consecutive runs of liquid chromatography. The trimeric form of the light-harvesting complex has been obtained by sucrose gradient ultracentrifugation. The result of SDSPAGE shows that the light-harvesting complex is composed of at least five apoproteins in which a protein with apparent molecular weight of about 31 kD was never found in the major light-harvesting complex (LHC II ) from higher plants. The isolated Bryopsis corticulans light-harvesting complex contains a specific carotenoid, siphonaxanthin, as well as chlorophyll (Chl) a, Chl b, neoxanthin and violaxanthin. Siphonaxanthin which is present in the light-harvesting siphonaxanthin-chlorophyll a/b-protein complex of Bryopsis corticulans is responsible for enhanced absorption in the blue-green region (530 nm). Efficient energy transfer from both siphonaxanthin and Chl b to Chl a in Bryopsis corticulans LHCP, which has similar absorption and fluorescence emission spectra to those of the lutein-chlorophyll a/b-protein of higher plants, proved that molecular arrangement of the light-harvesting pigments was highly ordered in the Bryopsis corticulans LHCP. The siphonaxanthin-chlorophyll a/b-proteins allow enhanced absorption of blue-green light, the predominant light available in deep ocean waters or shaded subtidal marine habitats.     

Banach space valued martingales with respect to complex measure and their inequalities

Let dμ=ϕdν be a complex valued measure where ν is a non-negative measure and ϕ is a complex valued function which satisfiesb _p ⁺ orb _∞ ⁺ ⊂a ₁ condition. We prove some basic martingale inequalities such as B-G inequalities, weak (p, p) and strong (p, p) type inequalities for Banach space valued martingale with respect to complex measure μ. Supported by the National Natural Science Foundation of China Hou Youliang: born in 1956, Ph. D     

Cyclic peptides-assisted transport of metal ions across liquid-organic membrane

The formation of alkali and alkaline-earth metal picrate complexes with cyclo(Pro-Gly)_n ionophores (1, n = 3; 2, n = 4) can facilitate the migration of metal ions across a bulk liquid CH₂Cl₂ membrane. The migration behavior was studied by measuring the solution absorption at 356 nm, using a UV/Vis spectrophotometer, and the rates can be determined by comparing the initial absorption of donor solutions with the absorption of the corresponding receiver solutions as the function of time. It was found that cyclic peptide 1 shows higher transport activity for the studied alkali and alkaline-earth metal ions than compound 2, which is related to the backbone flexibility of the cyclic peptides. The findings in this work suggest that the rate of ionophore-facilitated ion transport depends not only on the ability of complex formation in aqueous phase, but also on the ability of complex dissociation in organic phase.     

Electrochemical studies of glutathione monolayer assembled on a polycrystalline gold electrode

The glutathione (GSH) monolayer and complex monolayer of GSH-metallic ion on polycrystalline gold electrode were studied by using K₃Fe(CN)₆ as the redox probe. As for the GSH monolayer, it was found that the metallic ions could open the ion-gate in the monolayer dramatically in the order La³⁺> Pb²⁺>>Ba²⁺>Ca²⁺ whereas Zn²⁺ ion closed the ion-gate. The complexes of GSH-metallic ions were capable of self-assembling the different kind of monolayer. All the differences were related to the structural configuration of the anchored GSH molecule, which changed with different metallic ions or pH. Biography:Fang Cheng (1971-) male, Ph. D, research direction: electroanlysis.     

New crystal structure of molecular complex 1-piperidine carboxylate-piperidinium-H<Subscript>2</Subscript>O studied by X-ray single crystal diffraction

Piperidine absorbs CO2 and H2O in air to form a molecular complex： piperidium-l-piperidinecarboxylate-H2O. The structure of the complex was characterized by X-ray single crystal diffraction. The crystal structure was determined to be triclinic, space group P1^-with a=0.648 6（8） nm, b=0.809 200） nm, c= 1.357 1（16） nm, a=96.96706）°, β =102.506（15）°,γ=104.202 05）°, Z=2. The complex is stabilized via five hydrogen bonds between the three components, N-O electrostatic interaction and O-O interaction （electron transfer） betweenl-piperidinecarboxylate and H2O. Due to electron transference of carbamate ion, the oxygen atom in water molecule is strongly negatively charged and the O-H bond is considerably shorter than that of the free molecule of water. The formation of the molecular complex is a reversible process and will decompose upon heating. The mechanism of formation and stabilization is further investigated herein.     

Single-crystal structure of coordination polymer [Nd2(C8H5NO4)3·4H2O]∞

Rapid progress is now being made in the design and synthesis of coordination polymers with unique topological structures[17]. Lots of interesting topological structures such as chain-like[4], ladder-like[8], grid-like[9], brick- like[10], comb-like structures[11], etc., have been reported. In recent years, preliminary applications of coordination polymers to chemistry and material science, such as molecular sieve, catalysis, nonlinear optical properties, magnetic materials, biotic sensors, etc…     

飞秒激光场中甲醇产物离子的角分布

利用直流切片离子成像技术结合飞行时间质谱技术,我们研究了甲醇(CH_3OH)分子在800 nm飞秒激光场中的多光子解离和库仑爆炸过程.获得了甲醇分子在光场中的飞行时间质谱和产物离子的切片影像,分析得到了不同库仑爆炸通道碎片离子的动能分布和角度分布.本文对比分析了C-O键断裂产生H_2O~+的H转移通道和产生OH~+的非H转移通道的角分布,计算了不同激光强度下两个通道的各向异性参数α_2和(cos~2θ),并根据产物离子角度分布与激光强度和离子价态的关系,揭示了甲醇分子在飞秒光场中的准直机制为动力学准直.     

Effects of different aggregation forms of LHC Ⅱ from Bryopsis corticulans on the excited state properties of Chl a

Steady-state and time-resolved fluorescence spectroscopies have been used to study the excited state properties of Chl a in different aggregation forms of light-harvesting complex Ⅱ （LHC Ⅱ） from an intertidal green alga, Bryopsis corticulans, i.e. LHC Ⅱ monomer, trimer and oligomer. When either Chl a or Chl b was selectively excited, the observed decrease in Chl a fluorescence in the oligomer is proved to be caused mainly by the fast fluorescence quenching among Chl a molecules, rather than by the decrease in Chl b-to-Chl a singlet excitation transfer efficiency. Analyses of the picosecond time-resolved fluorescence kinetics identified two exponential decay components in all of the three forms of LHC Ⅱ： a longer-lived component （4.1 -4.7 ns） originating from fluorescence emission of Chl a, and a shorter-lived one （135-540 ps） from the rapid equilibration of singlet excitation among Chl a molecules. The time constant of excitation equilibration is 135 ps in oligomer, 520 ps in trimer and 540 ps in monomer. These results imply that LHC Ⅱ in oligomer form is inherently able to quench Chl a excitation, a mechanism which may be related to the photoprotection of PS Ⅱ via changing the degree of LHC Ⅱ aggregation in Bryopsis corticulans.     

二维1:-5 Lotka-Volterra复四次系统的可线性化条件

本文考虑了如下的一类平面四次复Lotka-Volterra系统的可线性化问题ẋ=x（1-a₃₀x³-a₂₁x²y-a₁₂xy²-a₀₃y³）,ẏ=-y（5-b₃₀x³-b₂₁x²y-b₁₂xy²-b₀₃y³）.该系统为四次齐次多项式扰动下的具有$1:-5$线性项的复Lotka-Volterra系统,给出了该系统可线性化的充分必要条件.     

Synthesis,Structure and Antitumor Activities of [Ni（dien）2][Ni（CN）4] Complex

Ni(II)-dien complex was prepared and characterized by X-ray diffraction. The crystal belongs to triclinic system, space group P-1, with crystallographic parametersa=0.888 13(18) nm,b=0.890 10(18) nm,c=1. 591 8(3) nm, α=77.71(3)°, β=89.12(3)°, γ=61.24(3)°,Z=2. The two dien molecules coordinate to the central Ni atom, the six nitrogen atoms form a distorted octahedron. Preliminary pharmacological tests showed this complex had antitumor activity against HepG₂ and HL-60 cell linesin vitro. Foundation item, Supported by the National Natural Science Foundation of China (29972034) Biography: Li Tao (1976-), male, Ph. D candidate, research direction: ophthalmology and chemicalbiology.     

Dissociation of methanol in intense femtosecond laser field

Methanol was irradiated by 80 fs laser pulse, intensity range of 10¹³–10¹⁴ W/cm². A TOF-mass spectrometer was coupled to the laser system and used to detect the ions produced. The parent ions CH₃OH⁺ appeared firstly at the laser intensity of 1.4×10¹³ W/cm². While the laser intensity was gradually increased, the parent ions were dissociated and the primary ions CH₂OH⁺ were given as verified from the irradiation of deuterated methanol (CH₃OD) showing the C—H bond cracking firstly. While the laser intensity was further increased to 2.0 × 10¹³ W/cm², the C—O bonds of the parent ions also broke to give CH₃ ⁺. When the laser intensity was higher, smaller fragment ions like CH⁺, C⁺, OH⁺ and O⁺ also appeared. Among the fragment ions, only H⁺ ion yield had anisotropic angular distribution dependence on the laser polarization vector in the dissociation of methanol. All the experimental observations show that the dissociation of methanol proceeds through stepwise mechanism but not Coulomb explosion.     

Molecule modification and mass deposition induced by the implantation of low energy Fe+ ion beams into amino acids

Fe⁺ ion beams with the energy of 110 keV were implanted into films of L(+)-cysteine (HSCH₂CH(NH₂)COOH). One of the single crystals grown in hydrochloric acid solution with the implanted samples through slow evaporation was structurally characterized by the X-ray crystallography. The crystal is monoclinic, space group C2, with a = 1.8534(4) nm, b = 0.5234(1) nm, c = 0.7212(1) nm, β= 103.72°, V = 0.67965(3) nm³, Z = 4, F(000) = 144.0, D{clac} = 1.763 g · cm⁻³, μ(MoK _a = 1.06 mm⁻¹, T = 293(2) K. R = 0.0379, wR = 0.0835 for 660 observed reflections (I > 2σ(I)). The structural formula of the crystal compound is (CH₂CH(NH₂)NO₂)ClFe (M _r = 180.38 u). Products of heavy ion beam irradiation were purified and it was directly confirmed that the implanted Fe⁺ ions had been deposited in the novel molecules. The same doses of Fe⁺ ion beams of the same energy were implanted into films of L(+)-cysteine hydrochloride monohydrate. FTIR spectroscopy of the implanted samples proved that some of the original molecules were seriously damaged and significant modifications were induced.     

铀酰离子-细胞色素b_5复合物的分子动力学模拟

铀酰离子(UO_2~(2+))的生物学毒性是由于它能与蛋白质形成稳定的复合物而破坏了蛋白的正常功能。通过使用分子建模和分子动力学(molecular dynamics,MD)模拟,对铀酰离子-细胞色素b_5复合物(UO_2~(2+)-cyt b_5)进行了结构预测。模拟结构显示,UO_2~(2+)通过配位和氢键作用结合到Cyt b_5中谷氨酸Glu37和Glu43,导致Cyt b_5的动力学行为发生轻微改变,而对蛋白整体结构几乎不产生影响。这些现象与Cyt b_5的体内形成以及作为电子传递蛋白的生物功能紧密相联。这些原子水平上理论信息的获得,为铀酰离子的毒性机制,尤其是涉及Cyt b_5的细胞凋亡,提供了深刻内涵。     

Two-dimensional crystallization and preliminary electron crystallographic result of partially purified F<Subscript>0</Subscript> from porcine mitochondria

After removal of cytoplasmic sector F₁ from submitochondrial particles of F₀F₁-ATP synthase complex with guanidine hydrochloride, the transmembrane sector F₀ was specifically extracted from the stripped membranes in the presence of detergent CHAPS and partially purified. Two-dimensional crystals were produced by the reconstitution of the partially purified F₀ into asolectin and microdialysis. The obtained crystals are able to diffract to 2 nm. The projection map of the negatively stained crystal shows that the crystal has p42₁2 symmetry, lattice constant, a=b=14.4 nm. A unit cell contains four F₀ molecules.     

NMR and FT-IR analysis of new molecular complex 1-piperidine-carboxylate-piperidinium-H2O

Piperidine absorbs CO2 and H2O contents in air to form a molecular complex： piperidium-1-piperidinecarboxylate-H2O. The structure of the complex was characterized by FT-IR and NMR. The complex is stabilized via five hydrogen bonds between the three components, N…O electrostatic interaction and O…O interaction （electron transfer） betweenl-piperidinecarboxylate and H2O. Through electron transfer from the carbamate ion, the oxygen atom in water molecule is strongly negatively charged and the O-H bond is considerably shorter than that of free water molecule. The formation of the molecular complex is a reversible process and will decompose upon heating. The mechanism of formation and stabilization is further investigated herein.     

双线性分数次积分算子交换子在Triebel-Lizorkin空间上有界的充分必要条件

首先讨论了双线性分数次积分算子与Lipschitz函数生成的线性交换子在Triebel-Lizorkin空间上的有界性.然后证明了b_1=b_2为Lipschitz函数的等价条件是双线性分数次积分算子交换子从乘积Lebesgue空间到Lebesgue空间(或Triebel-Lizorkin空间)有界.     

The nonwandering set of some Hénon map

For the Hénon mapT _{a, b}(x, y) = (1 −ax ² +y, bx), Benedicks and Carleson proved that for (a,b) near (2, 0) andb > 0, there exists a setE with positive Lebesgue measure, whose corresponding mapT _{a, b} possesses a strange attractor. Viana conjectured that if (a, b) ∈E, then the nonwandering set of the mapT _a, b Ω(T_{a, b}) = ∧_{a, b},Uq _a, b, where ∧_{a, b}, is the strange attractor, q_a,b is a hyperbolic fixed point in the third quadrant. It is proved that this conjecture holds true for a positive measure set E₁ ⊂E.     

一类2n次Kolmogorov系统的极限环

研究一类2n次Kolmogorov系统{dx/dt=x(a0-a1x a3x3-a4x4 a5xy2n-1),dy/dt=y(b1x2n-b2),极限环的存在性问题.主要讨论a5＞0和a5＜0两种情形.当a5＞0时,系统在第一象限内不存在极限环;当a5＜0时,得到了平衡点的稳定性态,系统无闭轨的充分条件以及在第一象限内存在稳定极限环的条件.     

Comparative crystal structure determination of griseofulvin: Powder X-ray diffraction versus single-crystal X-ray diffraction

In an attempt to compare crystal structure determination from powder data and single-crystal data,crystal structure of griseofulvin(C 17 H 17 ClO 6) was tested by both powder and single-crystal X-ray diffraction.Lattice parameters of griseofulvin are α=90.0°,a=b=8.9757,c=19.9345,V=1605.99 3 from powder data coinciding with α=90.0°,a=b=8.9714,c=19.8848,V=1600.46 3 from single-crystal data.Main processes of structure elucidating of griseofulvin by the two approaches were analyzed.Powder X-ray diffraction was demonstrated to be a powerful auxiliary implement to single-crystal X-ray diffraction in structure characterization,and its application can be popularized in the field of structure research of small organic molecules.     

Remote sensing of algal blooms using a turbidity-free function for near-infrared and red signals

HARMFUL ALGAL BLOOM ACTS UPON IMPORTANT ENVIRON-MENTAL PROBLEMS IN COASTAL WATERS.A UNIFIED AND IM-PLEMENTING METHOD FOR SURVEY AND MONITORING ALGALBLOOMS HAS BEEN DEVELOPED SINCE LAST DECADE.HOWEVER THERE IS A DATA GAP OF ABOUT TENS YEARS IN THE PERIOD W…