Estimate of carbonate production by scleractinian corals at Luhuitou fringing reef, Sanya, China

Carbonate production by scleractinian corals not only maintains coral reef growth, but also represents an important source of atmospheric carbon dioxide. In this paper the carbonate production by scler-actinian corals at Luhuitou fringing reef, Sanya, Hainan Island, China, is investigated with an ecological census-based method. Averaged carbonate production is 1.16 ± 0.55 kg·m-2·a-1 and 3.52 ± 1.32 kg·m-2·a-1 on the reef flat and reef slope, respectively, depending on the composition and distribution of cor...     

Trend, seasonal and diurnal variations of atmospheric CO2 in Beijing

The concentration of atmospheric CO₂ in Beijing increased rapidly at a mean growth rate of 3.7% · a⁻¹ from 1993 to 1995. After displaying a peak of (409.7±25.9) μmol · mol⁻¹ in 1995, it decreased slowly. Both the almost stable anthropogenic CO₂ source and increasing biotic CO₂ sink contribute to the drop of CO₂ concentration from 1995 to 2000. The seasonal variation of CO₂ concentration exhibits a clear cycle with a maximum in winter, averaging (426.8±20.6) μmol · mol⁻¹, and a minimum in summer, averaging (369.1±6.1) μmol·mol⁻¹. The seasonal variation of CO₂ concentration is mainly controlled by phenology. The mean diurnal variation of atmospheric CO₂ concentration for a year in Beijing is highly clear: daily maximum CO₂ concentration usually occurs at night, but daily minimum CO₂ concentration does in the daytime, with a mean diurnal difference more than 34.7 μmol·mol⁻¹. It has been revealed that the interannual variations of atmospheric CO₂ concentration in winter and autumn regulated the interannual trend of atmospheric CO₂, whereas the interannual variation of CO₂ concentration in summer affected the general tendency of atmospheric CO₂ in a less degree.     

Effect of CO<Subscript>2</Subscript> concentrations on the activity of photosynthetic CO<Subscript>2</Subscript> fixation and extracelluar carbonic anhydrase in the marine diatom <Emphasis Type="Italic">Skeletonema costatum</Emphasis>

The growth and activity of photosynthetic CO2 uptake and extracellular carbonic anhydrase (CAext) of the marine diatom Skeletonema costatum were investigated while cultured at different levels of CO2 in order to see its physio-logical response to different CO2 concentrations under either a low (30 靘ol·m-2·s-1) or high (210 靘ol·m-2·s-1) irradiance. The changes in CO2 concentrations (4—31 靘ol/L) affected the growth and net photosynthesis to a greater extent under the low than under the high light re-gime. CAext was detected in the cells grown at 4 mol/L CO2 but not at 31 and 12 靘ol/L CO2, with its activity being about 2.5-fold higher at the high than at the low irradiance. Photo- synthetic CO2 affinity (1/ K1/2(CO2)) of the cells de-creased with increased CO2 concentrations in culture. The cells cultured under the high-light show significantly higher photosynthetic CO2 affinity than those grown at the low-light level. It is concluded that the regulations of CAext activity and photosynthetic CO2 affinity are dependent not only on CO2 concentration but also on light availability, and that the de-velopment of higher CAext activity and CO2 affinity under higher light level could sufficiently support the photosyn-thetic demand for CO2 even at low level of CO2.     

Kinetic studies of the decomposition reaction of adducts of dinuclear Fe(Ⅱ)/O2

Kinetic studies of the decomposition reaction of dinuclear Fe(Ⅱ) adducts [Fe₂(N-Et-HPTB){O₂P(OPh)₂}](Cl- O₄)₂ (1) and [Fe₂(N-Et-HPTB) {O₂P(Ph)₂}] (ClO₄)₂ (2) with O₂ have been carried out at low temperature using UV-vis spectra. The decomposition reaction of Fe(Ⅱ)/O₂ adducts was first-order in the experimental conditions, and the activation parameters were obtained. ?H^¹ = 85.62 kJ·mol^-1, ?S¹ = 19.43 J·mol^-1·K^-1 for compound (1) and ?H^¹ = 97.97 kJ·mol^-1, ?S^¹ = 55.68 J·mol^-1·K^-1 for compound (2). These results are similar to those of dioxygen adducts of other metals complexes and natural enzymes such as methane mono- oxygenase (MMOH).     

Investigation of the cross-reaction mechanism of C<Subscript>6</Subscript>H<Subscript>5</Subscript>F-HNO<Subscript>2</Subscript> aqueous solution irradiated at 355 nm by transient absorbance spectrum technique

The transient absorption spectrum technique was employed to investigate the cross-reaction mechanism of C6H5F-HNO2 aqueous solution irradiated at 355 nm. The characteristic and the kinetic parameters of transient species were also detected. Hydroxyl radical derived from the photolysis of HNO2 was added to monofluorobenzene with a second-order rate constant of （5.83±0.17）×10^9 L·mol^-1·s^-1 to form an adduct, C6H5F…OH, which was able to react with HNO2 as the main reaction pathway with a rate constant of （8.3±0.1）×10^7 L·mol^-1·s^-1. The C6F6…OH adduct can also be decayed by elimination of H2O to yield monofluorophenyl radical C6H4F-. By GC-MS technique, the final products were identified to be monofluorophenol, nitro-monofluorobenzene, nitro-monofluorophenol and para-fluorobiphenyl.     

Synthesis, Characterization and Calorimetry of Ni（C4H8N2O3）2Cl2

A coordination complex was synthesized from NiCl2 and dipeptide glycylglycine（GG）. It was characterized by element analysis, NMR and TG methods, and then was determined to be Ni（C4HsN2O3）2Cl2. Using an isoperibolic reaction calorimeter, the standard molar enthalpy of formation of Ni（GG）2Cl2（solid） has been determined to be -（1 674.66±2.02） kJ · mol^-1 at 298.15 K.     

Compression behavior and equation of state of Ni77P23 amorphous alloy

The compression behavior of Ni77P23 amorphous alloy is investigated at room temperature in a diamond-anvil cell instrument using insitu high pressure energy dispersive X-ray diffraction with a syn- chrotron radiation source. The equation of state is determined by fitting the experimental data accord- ing to Birch-Murnaghan equation: -ΔV/V0=0.08606P-3.2×10-4P2 5.7×10-6P3. It is found that the structure of Ni77P23 amorphous alloy is stable under pressures up to 30.5 GPa.     

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.     

Diurnal and monthly variations of carbon dioxide flux in an alpine shrub on the Qinghai-Tibet Plateau

Long-term flux observation is an efficient approachto collect CO2 emission or assimilation data in an ecosys-tem. In cooperation with a series of international coopera-tion programs including those sponsored by IGBP (Inter-national Geosphere-Biosphere Program), WCRP (WorldClimate Research Program), IHDP (International HumanDimension of Global Environment Change), GCTE(Global Change and Terrestrial Ecosystem) and LUCC(Land Use and Land Cover Change), a lot of researchwork conce…     

Gene product expression of cyclin D<Subscript>2</Subscript> and p16 during the transition from cardiac myocyte hyperplasia to hypertrophy

The current study was to investigate mRNA expression of cyclin D₂ and p16 during the transition from cardiac myocyte hyperplasia to hypertrophy. Cultured cardiac myocytes (CM) and fibroblasts (FC) obtained from 1-day-old Sparague-Dawley rats were used in this study. We have determined (1) hyperplasia by cell growth curve and fluorescence activated cell sorting (FACS); and (2) ultrastructure by electron microscope observation; and (3) expresions of cyclin D₂ mRNA and p16 mRNA by using in situ hybridization and image analysis. The results were shown (1) Results of cell growth curve and FACS analysis showed CM could proliferate in the first 3 cultured days (4 days in postnatal development). But the ability decreased quickly, concomitant with the differentiation. (2) The ultrastructure of CM showed the large amount of myofilaments and mitochondrion and FC showed moderate amount of rough endoplasmic reticulum. (3) The expression of cyclin D₂ mRNA in 3−, 4−, 5−day CM group was 0.89 times (p<0.05), 0.80 times (p<0.05) and 0.56 times (p<0.01) of that in 1-day group respectively. P16 mRNA in 2−, 3−, 4−, 5−day CM group were 1.63 times (p<0.01), 1.72 times (p<0.01), 1.99 times (p<0.01) and 2.84 times (p<0.01) of that in 1−day group respectively. It can be concluded that cultured neonatal rat cardiac myocytes could proliferate during the first 3 cultured days, but the ability of proliferation decreased, from the fourth day, concomitant with differentiation. Cyclin D₂ and p16 have the key roles during the transition from myocyte hyperplasia to hypertrophy. Biography: Zhang Yu-xia (1974-), female, Master, research direction: cardiovascular pathology.     

Analysis of the characteristics of the harmonics coefficient <Emphasis Type="Italic">J</Emphasis><Subscript>2</Subscript> of the Earth’s gravity field in different periods

The characteristics of the geopotential coefficient J2 in different periods are analyzed using satellite laser ranging data spanning the last 27 years.The satellites used in the analysis are Lageos1 and Lageos2.The variations in J2 are obtained by determining the dynamic orbit.The results show that there are strong seasonal and long-term variations.For different data spans,the seasonal variations agree well in terms of both amplitude and phase.Using all the data,the amplitude and phase of the annual term are 2.5 10-10 and 127°,respectively,while the amplitude and phase of the semiannual term are 0.94 10-10 and 213°,respectively.In the case of long-term variation,the secular variation in J2(J2) is-2.2 10-11 a-1 from 1984 to 2010.J2 differs for the different periods because of interannual variations,such as the "1998 anomaly".Another anomaly may have taken place during 2007-2010.Although the cause of the anomaly is unknown,it is an important observational constraint on the shape of the Earth.     

Comparative study of the net exchange of CO<Subscript>2</Subscript> in 3 types of vegetation ecosystems on the Qinghai-Tibetan Plateau

Using the eddy covariance method, from 1 July 2003 to 30 June 2004, we conducted the observation and analysis of ecosystem CO2 flux in 3 types of alpine meadow vegetation （Kobresia humilis, Potentilla fruticosa shrub and Kobresia tibetica swamp meadows） on the Qinghai-Tibetan Plateau. The results show that the Kobresia humilis meadow, the shrub meadow and the swamp meadow＇s highest CO2 uptake rates are 16.78, 10.42 and 16.57 μmol·m^-2·-s^-1 respectively, while their highest CO2 release rates are 8.22, 7.73 and 18.67μmol·m^-2·-s^-1 respectively. The Kobresia humilis meadow and shrub meadow＇s annual atmospheric uptakes are 282 g CO2/m^2 and 53 g CO2/m^2, respectively, while swamp meadow＇s annual atmospheric release is 478 g CO2/m^2. This proves that the Kobresia humilis meadow and the shrub meadow on the Qinghai-Tibetan Plateau have relatively low potential for CO2 uptake and release compared to C4 grasslands, a number of lowland grasslands, and forests. Moreover, swamp meadow has relatively high release potential. This, in turn, reveals clear differences in carbon source/sink between different types of vegetation in the Qinghai-Tibetan Plateau alpine meadow ecosystem. These differences are mainly brought by differences in the vegetations＇ photosynthetic capacity and soil respiration.     

Analysis of active sites for N2 and H^＋ reduction on FeMo-cofactor of nitrogenase

Dinitrogen (N2) and proton (H ),which act as physiological substrates of nitrogenase,are reduced on FeMo-co of the MoFe protein. However,researchers have different opinions about their exact reduction sites. Nitrogenases were purified from the wild type (WT) and five mutants of Azotobacter vinelandii (Av),including Qα191K,Hα195Q,nifV-,Qα191K/nifV- and Hα195Q/nifV-; and the activities of these en-zymes for N2 and H reduction were analyzed. Our results suggest that the Fe2 and Fe6,atoms closed to the central sulfur atom (S2B) within FeMo-co,are sites for N2 binding and reduction and the Mo atom of FeMo-co is the site for H reduction. Combining these data with further bioinformatical analysis,we propose that two parallel electron channels may exist between the 8Fe7S cluster and FeMo-co.     

Theoretical study on the lithium bond interaction of furan homologues C4H4Y （Y=O,S） with LiCH3 via DFT and MP2

The optimizations geometries and interaction energy corrected by BSSE of the complexes between C4H4Y （Y=O, S） and CHiLi have been calculated at the B3LYP/6-311＋＋G^＊＊ and MP2/6-311＋＋G^＊＊ levels. Three complexes were obtained. Abnormally, the calculations showed that all the C10--Li14 bond lengths increased obviously but the blue-shift of C10-Li14 stretching frequency occurred after formed complexes. The calculated binding energy with basis set super-position error （BSSE） and zero-point vibrational energy corrections of complexes I-III is -45.757, -35.700 and -39.107 kJ·mol^-1, respectively. The analyses on the combining interaction with the atom-in-molecules theory （AIM） also showed that a relatively strong lithium bond interaction presented in furan homologues C4H4Y-LiCH3 systems. Natural bond orbital theory （NBO） analysis has been performed, and the results revealed that the complex I is formed with n-σ type lithium bond interaction between C4H40 and LiCH3, complex II is formed with TT-s type lithium bond interaction between C4H4O and LiCH3, and complex III is formed with TT-s and n-s type lithium bond interactions between C4H4S and LiCH3, respectively.     

Carbon isotopic composition,turnover and origins of soil CO<Subscript>2</Subscript> in a monsoon evergreen broadleaf forest in the Dinghushan Biosphere Reservoir,South China

Carbon isotopic compositions of soil CO2 in rainy season (July) from two natural soil profiles (DHLS & DHS) in the monsoon evergreen broadleaf forest in the Dinghushan Biosphere Reservoir (DBR), South China, are presented. Turnover and origins of soil CO₂ are preliminarily discussed in this paper. Results show that the content of soil CO2 varies between 6120 and 18718 ppmv, and increases with increasing depth until 75 cm, and then it declines. In DHLS, soil CO₂ δ¹³C ranges from −24.71‰ to −24.03‰, showing a significant inverse correlation (R²＝0.91) with the soil CO₂ content in the same layer. According to a model related to soil CO₂ δ¹³C, the soil CO₂ is mainly derived from the root respiration (>80%) in DHLS. While in DHS, where soil CO₂ ? 13C ranges from −25.19‰ to −22.82‰, soil CO₂ is primarily originated from the decomposition of organic matter (51%–94%), excluding the surface layer (20 cm, 90%). Radiocarbon data suggest that the carbon in soil CO₂ is modern carbon in both DHLS and DHS. Differences in ¹⁴C ages between the “oldest” and “youngest” soil CO₂ in DHLS and DHS are 8 months and 14 months, respectively, indicating that soil CO₂ in DHLS has a faster turnover rate than that in DHS. The ¹⁴C values of soil CO₂, which range between 100.0‰ and 107.2‰ and between 102.5‰ and 112.1‰ in DHLS and DHS, respectively, are obviously higher than those of current atmospheric CO₂ and SOC in the same layer, suggesting that soil CO₂ is likely an important reservoir for Bomb-¹⁴C in the atmosphere.     

Electrochemical properties of LiNi<Subscript>0.5</Subscript>Mn<Subscript>1.3</Subscript>Ti<Subscript>0.2</Subscript>O<Subscript>4</Subscript>/Li<Subscript>4</Subscript>Ti<Subscript>5</Subscript>O<Subscript>12</Subscript> cells

Spinel compounds LiNi_0.5Mn_1.3Ti_0.2O₄ (LNMTO) and Li₄Ti₅O₁₂ (LTO) were synthesized by different methods. The particle sizes of LNMTO and LTO are 0.5–2 and 0.5–0.8 μm, respectively. The LNMTO/LTO cell exhibits better electrochemical properties at both a low current rate of 0.2C and a high current rate of 1C. When the specific capacity was determined based on the mass of the LNMTO cathode, the LNMTO/LTO cell delivered 137 mA·h·g⁻¹ at 0.2C and 118.2 mA·h·g⁻¹ at 1C, and the corresponding capacity retentions after 30 cycles are 88.5% and 92.4%, respectively.     

Kinetic investigation of <Emphasis Type="Italic">in situ</Emphasis> growth of CdMoO<Subscript>4</Subscript> nano-octahedra

CdMoO₄ nano-octahedra were grown in situ at room temperature by reverse-microemulsion. Energy evolution from this growth process was monitored using microcalorimetry. The microcalorimetric heat flow (MCHF) curve showed a characteristic endothermic peak for the initial reaction, and double discontinuous exothermic peaks for the subsequent crystal growth. Combined with complementary characterization techniques, the evolution of morphology and size of the CdMoO₄ nano-octahedra were correlated with the MCHF peaks. Calculations based on the microcalorimetric results at 298.15 K provided rate constants of 7.56×10⁻⁵ s⁻¹ for the reaction and nucleation process and 1.59×10⁻⁴ s⁻¹ for the crystallization process.     

The giant magnetocaloric effect in Gd<Subscript>5</Subscript>Si<Subscript>2</Subscript>Ge<Subscript>2</Subscript> with low purity gadolinium

The giant magnetocaloric effect Gd5Si2Ge2 alloy was prepared with 99wt% low purity commercial Gd. Powder XRD and magnetic measurements showed that the Gd5Si2Ge2 alloy annealed at 1200℃ for 1h had a significant magnetic- crystallographic first order phase transition at about 270 K. The maximal magnetic entropy change is 17.55 J· kg^-1· K^-1 under a magnetic field change of 0-5 T. The distinct increase of magnetic entropy change belongs to the first-order phase transition from the orthorhombic Gd5Si4-type to the monoclinic Gd5Si2Ge2-type after high temperature heat-treatment.     

Interspecies and spatial diversity in the symbiotic zooxanthellae density in corals from northern South China Sea and its relationship to coral reef bleaching

Coral reef bleaching is usually characterized by expulsion of symbiotic zooxanthellae, loss of zooxanthellae pigmentation, or both. We collected 128 samples comprising 39 species of 21 genera of reef-building corals from Luhuitou and Xiaodonghai in Sanya of Hainan Island and Daya Bay of Guangdong Province, respectively, and analyzed the symbiotic zooxanthellae population density. The results show that： （1） the symbiotic zooxanthella density varies from 0.67×10^6 to 8.48×10^6 cell/cm^2, displaying significant interspecies variability, with branch corals usually having relatively less zooxanthellae （ranging from 0.67×10^6 to 2.47×10^6 cell/cm^2） than massive species （from 1.0×10^6 to 8.48×10^6 cell/cm^2）; （2） corals inhabiting within 4 m water depth have higher levels of symbiotic zooxanthellae than those living at the bottom （-7 m depth） of the reef area; （3） there is no discernable difference in the zooxanthellae density between corals from relatively high latitude Daya Bay （-22°N） and those from relatively low latitude Sanya （-18°N） at comparable sea surface temperatures （SST）; （4） in partially-bleached corals, the density of zooxanthellae shows the following order： healthy-looking part〉 semi-bleached part 〉 bleached part. Based on the above results, we suggest that （1） the zooxanthellae density difference between branching and massive coral species is the main cause that branching corals are more vulnerable to bleaching than massive corals. For example, symbiotic zooxanthellae levels are low in branching Acropora and Pocillopora corals and thus these corals are more susceptible to bleaching and mortality; （2） symbiotic zooxanthellae density can also be affected by environmental conditions, such as sediment loads, diving-related turbidity, and aquaculture-related nitrate and phosphate input, and their increase may reduce symbiotic zooxanthellae density in corals.     

Surface tension and specific heat of liquid Ni<Subscript>70.2</Subscript>Si<Subscript>29.8</Subscript> alloy

The thermophysical properties of liquid alloys in me-tastable state are of importance for liquid-solid phase transformation under nonequilibrium conditions[1―10]. Sur-face tension and specific heat, two of the most important thermophysical properties, have significant influences on the process of crystal nucleation and growth. Furthermore, it is necessary to obtain these data so as to perform quan-titative research on rapid solidification[3―10]. The tradi-tional measurement methods, however,…