Energy transfer mechanism of PBS-thylakoid complexes

Conclusion In this work, we studied the energy transfer mechanism among PBS and two reaction centers (PS I and PS II) in PBS-thylakoid complexes by using steady-state spectra (77 K) and spectral deconvolution techniques. The experimental results indicated that the PBS-thylakoid complexes could perform the function of light state transition just like intact algae cell, and confirmed that PBSs were directly connected with PS I and PS II reaction centers separately. The energy transfer pathways from PBSs to two reaction centers are PBS-PS I and PBS-PS II.     

Distribution of lanthanum among the chloroplast subcomponents of spinach and its biological effects on photosynthesis： location of the lanthanum binding sites in photosystem Ⅱ

The effects of lanthanum at different concentrations on the related photosynthetic activities of Hill reaction, Mg^2＋-ATPase and Ca^2＋-ATPase in spinach chloroplast were studied. Experimental results showed that lanthanum can increase all the activities at suitable concentration （15-30 mg· L^-1）, however, it behaves toxically on them when over used （60 mg. L^-1）. To get an improved understanding of the mechanism of lanthanum effects on the photosynthesis of spinach, the different subcomponents in the chloroplast of the cultured spinach were isolated, and the content of lanthanum in each subcomponent was determined by ICP-MS. The results obtained indicated that among these different subcomponents, about 90% out of the total chloroplast lanthanum was located in photosystem Ⅱ （PS Ⅱ） while there was little lanthanum in photosystem Ⅰ （PS Ⅰ）. Moreover, size exclusion high performance liquid chromatography （SE-HPLC） coupled with online UV and ICP-MS detections was novelly used for locating lanthanum binding sites in PS Ⅱ proteins for the first time. It was found that lanthanum has two binding sites in PS Ⅱ： La associates with chlorophyll together with magnesium in PS Ⅱ by partly replacing magnesium and also shares the common binding sites of PS Ⅱ proteins together with the inorganic cofactors of calcium and manganese, influencing the process of photosynthesis.     

Theoretical study of N(C)―H…H―B multi-dihydrogen bonds

The optimized geometries, frequencies and interaction energy corrected with basis set superposition error (BSSE) of the multi-dihydrogen bond complexes C₄H₄NH…BH₄^–. and CH≡CH…BH₄^–. have been calculated at both the B3LYP/6-311++G** and the MP2/6-311++G** levels. The calculations were per-formed to study the nature of the N―H…H3―B and C―H…H2―B red shift multi dihydrogen bond in complex C4H4NH…BH^–₄ and CH≡CH…BH4–. The BSSE-corrected multi-dihydrogen bond interaction en-ergy of complex I (C₄H₄NH…BH₄^–.) and complexⅡ(CH≡CH…BH₄^–.) is -76.62 and -33.79 kJ/mol (MP2/6- 311++G**), respectively. From the natural bond orbital（NBO）analysis, we detailedly discussed the orbital interactions, electron density transfers, rehybridizations and the essential of the correlative bond length changes in the two complexes. In addition, solvent effect on the geometric structures, vibration frequencies and interaction energy of the monomer and complexes was studied in detail. It is relevant to the relatively dielectric constants (ε).     

Photo-induced degradation of Ru（Ⅱ） complex absorbed on anatase TiO2 thin film electrode

Photo-induced degradation of a monolayer of Ru（Ⅱ） complex absorbed on anatase TiO2 thin film was studied by using resonant micro-Raman spectroscopy. Under intense light radiation of a laser and in the absence of a reducing agent, the dye decomposed quickly. When the dye-sensitized TiO2 thin film electrode was covered by a reducing agent, namely the I^-/I3^- redox couple, the photo-induced decomposing rate was slowed by a factor of -10^6. In both cases, the dye decomposed with time under an exponential law.     

The excitation energy transfer between β-Car and Chla molecules in PS Ⅱ core antenna complexes CP43 and CP47

The excitation energy transfer efficiency between β-Car and Chla molecules in purified CP43 and CP47 was calculated by comparing absorption and fluorescence excitation after normalization at 550 nm, CP43 had an energy transfer efficiency of 29.1% while the CP47 had an energy transfer efficiency of 62.8%, proving that excitation energy was transferred between β-Car and Chla molecules in CP43 and CP47 at normal conditions. The excitation energy transfer between β-Car and Chla molecules in CP43 and CP47 may occur through the “Dexter” mechanism and the distance between these two kinds of pigments should be less than 1 nm. In addition, the results were also used to discuss the conformational relationship between β-Car and Chla molecules in CP43 and CP47.     

HPLC determination of ascorbic acid using luminol-Cu (II) chemiluminescence-application to the analysis of Juice beverage

The chemiluminescence (CL) of luminol-Cu (II) was applied to HPLC determination of ascorbic acid, which was separated by a C₁₈ reverse-phase column with a mobile phase of 0.25 mol/L HAc. The eluted ascorbic acid was mixed with 0.3 mmol/L luminol and 0.05 mol/L CuSO₄. The light emission from the reaction of Cu(II) oxidized ascorbic acid and luminol was detected by a modified luminometer. The detection limit was 3.6×10⁻⁶ mol/L for ascorbic acid at aS/N ratio of 3, and the linear calibration range was 2×10⁻⁴–2×10⁻³ mol/L. The relative standard deviation for 5 replicate injections of 1×10⁻³ mol/L ascorbic acid was calculated as 4.3%. The method was successfully applied to determination of ascorbic acid in juice beverage. Foundation item: National Natural Science Foundation of China (29605001) Biography: Wu Feng-wu(1963-), male, research direction: analytical chemistry.     

Experimental investigation of incremental reactivity of di-tert-butyl peroxide

Large quantities of di-tert-butyl peroxide (DTBP) have been emitted into the troposphere due to human activities. Its role in the atmospheric photochemical reaction has not been understood. This study presents the results of the photochemical reactions of DTBP and NOx, which have been simulated in a self-made smog chamber under the temperature of (29±1)℃. Both the wall decays of ozone and NO2 could be neglected, compared to the results in simulative experiments. The effective intensity of UV light used in the experiments was 1.28×10-3 s-1, which was expressed by the rate constant of NO2 photolysis in purified air. The reaction mechanism was proposed according to our results and reports of other researchers. The maximum values of incremental reactivity (IR) in the three simulative ex- periments were 9.53×10-2, 5.23×10-2 and 3.78×10-2, respectively. The incremental reactivity decreased with the increase of initial concentrations of DTBP. The IR value of DTBP obtained in this study was comparable to that of acetylene reported in our previous research.     

Large selenium isotopic variations and its implication in the Yutangba Se deposit, Hubei Province, China

The selenium isotopic ratios have been measured in the Yutangba Se deposit, Hubei Province, China. The results show that the δ 82/76SeNIST values vary from -12.77‰ to 4.93‰, which is the largest Se iso- topic variation found so far in natural terrestrial samples. The sample Ytb-5 of high-selenium carbona-ceous shale has the lightest Se isotopic composition with a δ 82/76SeNIST value of -12.77‰. On the basis of variations of Se isotope in the deposit along with other geological and geochemical evidence, the "redox model" is suggested to favor the explanation of the occurrence of native Se in the deposit. The application to the Yutangba Se deposit with the discovery of large Se isotopic fractionation for natural samples indicates the potential of Se isotope as a new geochemical tracer.     

Chemical leaching of an Indian bituminous coal and characterization of the products by vibrational spectroscopic techniques

High volatile bituminous coal was demineralized by a chemical method. The vibrations of the "aromatics" structure of graphite, crystalline or non-crystalline, were observed in the spectra at the 1600 cm-1 region. The band at 1477 cm-1 is assigned as V_R band, the band at 1392 cm-1 as V_L band and the band at 1540 cm-1 as G_R band. Graphite structure remains after chemical leaching liberates oxygenated functional groups and mineral groups. The silicate bands between 1010 and 1100 cm-1 are active in the infrared (IR) spectrum but inactive in the Raman spectrum. Absorption arising from C-H stretching in alkenes occurs in the region of 3000 to 2840 cm-1. Raman bands because of symmetric stretch of water molecules were also observed in the spectrum at 3250 cm-1 and 3450 cm-1. Scanning electron microscopy analysis revealed the presence of a graphite layer on the surface. Leaching of the sample with hydrofluoric acid decreases the mineral phase and increases the carbon content. The ash content is reduced by 84.5wt% with leaching from its initial value by mainly removing aluminum and silicate containing minerals.     

Preparation of monolayer-assembled fluorescent film and its sensing performances to hidden nitroaromatic explosives

Pyrene was chemically assembled on a glass plate surface in a monolayer manner via spacers containing triethylenetetramine （TETA） subunits. It has been demonstrated that the fluorescence emission of the film is sensitive to the presence of trace amount of nitroaromatic compound （NAC） vapors. As discovered in the present work, the response selectivity of the pyrene-functionalized film depends on the length of the spacer, the vapor pressure of a given NAC, and the quencher size. The film shows faster response to those quenchers which have higher vapor pressure and smaller size. Compared to the film with shorter spacers, the present film with longer flexible spacers shows a slower response to the NACs, but higher selectivity to the quencher size. Additionally, the detection limits to common ex- plosives in vapor phase, 2,4,6-trinitrotoluene （TNT） and 2,4-dinitrotoluene （DNT）, are 7.14×10^-12 and 5.49×10^-11 g·mL^-1, respectively. Further examinations indicated that the sensing process is fully reversible, and the vapors of those common interference such as benzene, toluene, ethanol, and perfume have little effect upon the sensing performances of the film.     

Synthesis and surface activity of biquaternary ammonium salt gemini surfactants with ester bond

The synthesis and surface activity of gemini surfactants with ester bond as spacer are described. Their critical micelle concentrations （CMC） are much lower than that of conventional surfactants, i.e., 1.62×10^-5, 1.38×10^-5, 1.28×10^-5 mol·L^-1 for gemini Ⅰ, Ⅱ and Ⅲ respectively. Surface tension at the CMC of gemini Ⅰ, Ⅱ and Ⅲ were 36.4, 38.5, 41.2 mN · m^-1. The physico-chemical properties such as Krafft points, foaming abilities and emulsifying power were also investigated. It is found that the title compounds have low Krafft points and show good solubility in water. The gemini surfactants synthesized also exhibit good foaming properties and excellent emulsifying power toward toluene. The foaming abilities and emulsifying power increase with the increase in carbon number of hydrophobic chain, and this might be caused by the sheer viscosity of different gemini surfactant solution.     

Small-scale convection beneath oceans and continents

Small-scale convection supplies heat flow of ～17 mW m-2 to the base of stable continents where xenolith studies resolve the geotherm.However,effects of small-scale convection are difficult to resolve in ocean basins.On first pass,most seafloor appears to subside to an asymptote compatible with ～40 mW m-2 convective heat flow.These common regions are tracked by hotspots so uplift associated with ponded mantle material is an attractive alternative.Unaffected seafloor in the North and South Atlantic continues to subside with the square root of age as expected from pure conduction.The theory of stagnant-lid convection provides good scaling relationships for heat flow.For linear viscosity,heat flow is proportional to the underlying "half-space" viscosity to the 1/3 power and the temperature to change viscosity by a factor of e to the 4/3 power.The formalism is easily modified to represent convection beneath a lid of highly viscous and buoyant cratonal lithosphere and to represent transient convection beneath thickening oceanic lithosphere.Asthenospheric mantle with linear,strongly temperature-dependent,and weakly depth-dependent viscosity is compatible with both oceanic and continental data.More complicated rheology may allow vigorous small-scale convection under most but not all old ocean basins.Still viable hypotheses require poorly understood global features,including lateral variations of asthenospheric temperature.Seismological studies have the potential to resolve the lithosphere-asthenosphere boundary,including local variations of its depth associated with small-scale convection.     

Excitation energy distribution between two photosystems inPorphyra yezoensis and its significance in photosynthesis evolution

Comparative investigation on energy distribution between two photosystems were carried out in the sporo- phytes and gametophytes of Porphyra yezoensis. By perfor- ming 77 K fluorescence spectra, we suggested that there probably existed a pathway for energy transfer from PSⅡ to PSⅠ to redistribute the absorbed energy in gametophytes, while no such a way or at minor level in sporophytes. Electron transfer inhibitor DCMU blocked the energy transfer from PSⅡ to PSⅠ in gametophytes, but no obvious effects on sporophytes. These indicated that excitation energy distribution between two photosystems in gametophytes was more cooperative than that in sporophytes. These data in ontogenesis reflected the evolution process of photosynthetic organisms and supported the hypothesis of independent evolution of each photosystem.     

Dynamic Mechanisms for Evolution of Mountain Rural Settlements and Soil Conservation in Upper Yangtze River Basin

This paper presents the logic relationship between rural settlement reconstruction and soil conservation in the Upper Yangtze River. Firstly, by introducing the concepts of ＂flow＂ and ＂intercepted flow＂, we probe into the dynamic mechanism on interaction between ecological and environmental system, and then point out that the ＂intercepting sites＂ are physical conditions for establishment of human settlements in mountains. Secondly, by using ecological theories, ＂flow＂, ＂source＂, and ＂sink＂, material cycle and energy flow in mountains have been discussed. Thirdly, according to dissipative structure theory and thermodynamic laws, a hypothesis has been proposed that ＂entropy flow＂ is a dynamic force for settlement evolution. Finally, it is argued that a project for soil conservation is set to control and utilize flows so rural settlements can be supported and farmers＇ life improved.     

Changes in the transthylakoid proton gradient are caused by the movement of phycobilisomes in the cyanobacterium <Emphasis Type="Italic">Synechocystis</Emphasis> sp. strain PCC 6803

Phycobilisomes (PBSs) are the main accessory light-harvesting complexes in cyanobacteria and their movement between photosystems (PSs) affects cyclic and respiratory electron transport. However, it remains unclear whether the movement of PBSs between PSs also affects the transthylakoid proton gradient (ΔpH). We investigated the effect of PBS movement on ΔpH levels in a unicellular cyanobacterium Synechocystis sp. strain PCC 6803, using glycinebetaine to immobilize and couple PBSs to photosystem II (PSII) or photosystem I (PSI) by applying under far-red or green light, respectively. The immobilization of PBSs at PSII inhibited decreases in ΔpH, as reflected by the slow phase of millisecond-delayed light emission (ms-DLE) that occurs during the movement of PBSs from PSII to PSI. By contrast, the immobilization of PBSs at PSI inhibited the increase in ΔpH that occurs when PBSs move from PSI to PSII. Comparison of the changes in ΔpH and electron transport caused by the movement of PBSs between PSs indicated that the changes in ΔpH were most likely caused by respiratory electron transport. This will further improve our understanding of the physiological role of PBS movement in cyanobacteria.     

Four kinds of ENU-induced white spot mice and chromosome locations of the mutant genes

After the accomplishment of the Human Genome Project, life sciences have entered a post-genome era to systematically study gene functions on a large scale[1]. Because of its similarity to humanity in genomic se-quences, biochemical metabolism and physiological mechanism, Mus musculus is the ideal model animal in the study of functional genome. As the publication of the draft map of mouse genome sequences in December 2002, studying gene functions by mouse enters a new stage[2]. So far, there …     

ApcD is required for state transition but not involved in blue-light induced quenching in the cyanobacterium <Emphasis Type="Italic">Anabaena</Emphasis> sp. PCC7120

Pbycobilisomes （PBS） are able to transfer absorbed energy to photosystem Ⅰ and Ⅱ, and the distribution of light energy between two photosystems is regulated by state transitions. In this study we show that energy transfer from PBS to photosystem Ⅰ （PSI） requires ApcD. Cells were unable to perform state transitions in the absence of ApcD. The apcD mutant grows more slowly in light mainly absorbed by PBS, indicating that ApcD-dependent energy transfer to PSI is required for optimal growth under this condition. The apcD mutant showed normal blue-light induced quenching, suggesting that ApcD is not required for this process and state transitions are independent of blue-light induced quenching. Under nitrogen fixing condition, the growth rates of the wild type and the mutant were the same, indicating that energy transfer from PBS to PSI in heterocysts was not required for nitrogen fixation.     

Significance of native arsenic in the Baogutu gold deposit, western Junggar, Xinjiang, NW China

Native arsenic together with comb quartz and stibnite is found in the Baogutu gold deposit, western Junggar (Xinjiang), NW China. It is anhedral with various grain size (<0.001 to 2 mm), and contains 98 wt% to 98.7 wt% As. Micro-granular electrum, the main auriferous mineral in the Baogutu gold deposit, is commonly enclosed in or closely accompanied by native arsenic. Three ore-forming paragenetic stages could be identified. Native arsenic mainly formed at stage II which is also the major stage for gold deposition. Mineral assemblage formed at this stage is native arsenic-stibnite-electrum-arseno- pyrite-miargyrite-freibergite-pyrrhotite-pyrite. Based on native arsenic and its coexisting minerals, the temperature (230 to 170℃), oxygen fugacity (logfO₂ = −42―−56.5) and sulfur fugacity (logf S₂ = −13.3― −16.6) of stage II are estimated. From stage I to stage II, the temperature, sulfur fugacity and S²⁻ con-centration of hydrothermal fluid decrease obviously, whereas the As concentration increases. Coexis-tence with native arsenic of electrum and its contents of 0.5 wt%―1.3 wt% As suggest that As is im-portant to transport Au when S²⁻ concentration decrease in hydrothermal fluid. Crystallization of native arsenic induced the deposition of electrum and consequently the formation of the Baogutu gold deposit.     

Application of Constructed Wetlands on Wastewater Treatment for Aquaculture Ponds

A group of constructed wetlands （CWs） were applied to the recirculating aquaculture system. This study assessed the performance of CWs in treating the aquaculture wastewater, examined the water quality condition of aquaculture ponds and the growth and the survival rate of ＂target＂ species （Ictalurus punctatus and Megalobrama amblycephala）. The results showed that CWs were effective on reducing the concentrations of 5-day biochemical oxygen demand （BOD5, at 70.5%）, total suspended solids （TSS, at 81.9%）, chlorophyll a （Chl-a, at 91.9%）, ammonium （NH4^＋, at 61.5%） and nitrate nitrogen （NOa-N, at 68.0%）. Effect of CWs on phosphate （PO43 -P） removal was relatively lower （at 20.0%）. The concentrations of BODs, TSS, Chl-a, NH4^＋ and TN, TP in the recirculating culture pond were significantly lower than that in the control pond（ p〈0.05 ）. CWs could help to increase total yield, survival rate of the ＂target＂ species and significantly decrease feed conversion ratio （ p〈0.05 ）.     

Electrochemistry study on PEO-LiClO<Subscript>4</Subscript>-ZSM5 composite polymer electrolyte

Allsolid-statelithiumpolymerbatteriesmaybeoneofthebestchoicesforelectrochemicalpowersourceofthefuturecharacterizedbyitshighenergydensities,goodcyclability,reliabilityandsafety[1,2].PEO-LiXbasedpoly-merelectrolyteshadreceivedextensiveattention[4,5],foritspotentialcapabilitytobeusedascandidatematerialforthetraditionalliquidelectrolytes,sinceWrightetal.foundthatthecomplexofPEOandalkalinesaltshadtheabilityofionicconductivityin1973[3].ThegeneralconceptofthetransportofLi+inthepolymerelectrolytewa…