Discovery of C<Subscript>4</Subscript> species at high altitude in Qinghai-Tibetan Plateau

Plant specimens are collected from the areas between latitude 27°?2′N and 40°57′N, and longitude 88°93°E and 103°24′E, with an altitudinal range from 2210 to 5050 m above the sea level in Qinghai-Tibetan Plateau. The stable carbon isotope analysis indicates that two of Chenopodiaceae and six of Poaceae in the samples are C4 plants. Four of the C4 plants are found in 11 spots with altitudes above 3800 m, and Pennisetum centrasiaticum, Arundinella yunnanensis and Orinus thoroldii are present in six spots above 4000 m, even up to 4520 m. At low CO2 partial pressure, that sufficient energy of high light improving C4 plant's tolerance of low temperature and precipitations concentrating in growing season probably are favorable for C4 plants growing at high altitude in Qinghai-Tibetan Plateau.     

Static opaque chamber-based technique for determination of net exchange of CO<Subscript>2</Subscript> between terrestrial ecosystem and atmosphere

Terrestrial carbon cycling is one of the hotspots in global change issues. In this paper, we presented the rationale for determination of net exchange of CO₂ between terrestrial and the atmosphere (NEE) and the methods for measuring several relevant components. Three key processes for determination of NEE were addressed, including the separation of shoot autotrophic respiration from total CO₂ emissions of the ecosystem, the partition of root respiration from soil CO₂ efflux, and the quantification of rhizodeposition C from NPP. With an understanding of the processes involved in the CO₂ exchange between terrestrial and the atmosphere, we estimated NEE of rice ecosystem in Nanjing based on field measurements of CO₂ emissions and several relevant biotic components as well as abiotic factors. The field measurements of CO₂ emissions were made over the rice-growing seasons in 2001 and 2002 with the static opaque chamber method. Calculations indicated that the seasonal pattern of NEE is comparable for two seasons. Either net carbon emission or fractional carbon fixation occurred during 3 weeks after rice transplanting and thereafter net carbon fixation appeared with an increasing trend as rice growing. Higher net carbon fixation occurred in the rice developmental period from elongating to heading. A decline trend in the fixation was documented after rice heading. The mean daily NEE was -6.06 gC·m⁻² in 2001 season and -7.95 gC·m⁻² in 2002 season, respectively. These values were comparable to the results obtained by Campbell et al. who made field measurements with the Bowen ratio-energy balance technique in irrigated rice, Texas USA. Moreover, the mean daily NEE in this study was also comparable to the values obtained from a Japanese rice paddy with the eddy covariance method under the similar water regime, either drainage course or waterlogged. It is concluded that NEE determined by the static opaque chamber method is comparable and in agreement with those measured by Bowen ratioenergy balance and eddy covariance methods.     

Influences of the degradation of swamp and alpine meadows on CO2 emission during growing season on the Qinghai-Tibet Plateau

CO2 emission fluxes of two types of ecosystem, swamp meadow and alpine meadow, in the Fenghuo- shan region of the Qinghai-Tibet Plateau were studied by the static chamber-portable infrared chro- matographic method. The results showed that there was large difference in the CO2 emission fluxes between the two ecosystems and in the same ecosystem of different degradation degrees. CO2 emis- sion flux of the swamp meadow gradually decreased with increasing degradation degree, while that of the alpine meadow gradually increased with increasing degradation degree except in May. The CO2 emission flux of undegraded swamp meadow was 65.1%―80.3% higher than that of undegraded alpine meadow; and the CO2 emission flux of moderately degraded swamp meadow was 22.1%―67.5% higher than that of alpine meadow; but the CO2 emission flux of severely degraded alpine meadow was 14.3%―29.5% higher than that of swamp meadow. The soil moisture content and temperature in the upper 5 cm soil layer and above-ground biomass were significantly correlated with the CO2 emission fluxes and regarded as the main environment factors to control the CO2 emission.     

Experimental study on CO2/CO of typical lining materials in full-scale fire test

Lining materials are widely used in buildings to cover walls and ceilings. Combustible linings may produce a potential high fire hazard in buildings. Once ignited, it propagates fire and accelerates the enclosure fire growth. Two types of lining materials were studied during the tests： block board and plywood. The test was conducted in an ISO 9705 room, where linings were mounted on walls without the ceiling. By changing the heat output of the burner, the ventilation, etc., the concentrations of CO2/CO of different lining materials were researched. The effect of test conditions on the production of CO2/CO of different lining materials was investigated, and useful experimental data were provided for the further development of numerical modeling to simulate enclosure fire growth lined with combustible materials.     

Transparent organic light-emitting diodes based on Cs<Subscript>2</Subscript>CO<Subscript>3</Subscript>:Ag/Ag composite cathode

The transparent organic light-emitting diodes (TOLEDs) based on Cs 2 CO 3:Ag/Ag composite cathode are reported in this paper.They show higher efficiency and better stability than the control devices with the Cs 2 CO 3 /Ag cathode.The devices are highly transparent,and show total efficiencies from both sides of the devices comparable with conventional bottom-emitting devices.The electroluminescence (EL) spectrum from the cathode side of the device is closer to the photoluminescence (PL) spectrum of the light...     

青藏高原沼泽及高寒草甸生长期内CO2排放

采用静态箱-便携式红外色谱法对青藏高原风火山地区沼泽草甸和高寒草甸两类生态系统CO2排放通量进行了研究.结果表明:生长期内两类生态系统之间及同一生态系统内部不同的退化程度之间CO2排放通量均存在较大差异.其中:未退化沼泽草甸较高寒草甸CO2的排放通量同比高出65.1%～80.3%;中度退化沼泽草甸较高寒草甸CO2的排放通量同比高出22.1%～67.5%;然而,严重退化的高寒草甸比沼泽草甸CO2的排放通量反而高出14.3%～29.5%.对于同类型高寒草地,未退化沼泽草甸CO2的排放通量分别是中度退化和严重退化的1.12～1.69倍和1.41～3.86倍;严重退化高寒草甸CO2的排放通量分别是未退化和中度退化的1.11～1.78倍和1.04～1.79倍.     

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.     

Effects of silty sand on CO<Subscript>2</Subscript> corrosion behavior of low-Cr tubing steel

An experimental study was carried out to assess the effects of silty sand on the CO 2 corrosion behavior of 1 wt% Cr (1Cr) and 3 wt% Cr (3Cr) tubing steel under 0.5 MPa CO 2 at 100°C and 1.5 m/s flow velocity.The 1Cr and 3Cr specimens both suffered general corrosion,but the surface was coarser in the pure CO 2 corrosion environment.Under silty sand conditions,severe pitting corrosion occurred on the 1Cr specimens and some acicular pitting appeared on the 3Cr specimens.The average corrosion rates of 1Cr and 3Cr steels increased by factors of 3 and 1.6,respectively.The corrosion products were analyzed by scanning electron microscopy (SEM),energy dispersive spectroscopy (EDS),X-ray diffraction (XRD),and electrical impedance spectroscopy (EIS).The results show that silty sand acts as an inclusion in corrosion product films and reduces the homogeneity and density of the products,rather than abrading the corrosion film.Ion-diffusion channels may build up around the irregular silty sand;this would degrade the protective capabilities of the product films and aggravate corrosion.     

ENSO frequency change in coupled climate models as response to the increasing CO<Subscript>2</Subscript> concentration

The response of ENSO frequency to the increasing CO2 concentration and associated mechanism are examined with outputs of four coupled climate models (GFDL/CM2.0,CNRM/CM3,IPSL/CM4 and INM/CM3.0) submitted to the IPCC Fourth Assessment Report (IPCC AR4).Results reveal a significant change of ENSO frequency as response to the increasing CO2 concentration.However,such a change exhibits an evident model dependence.The ENSO frequency tends to increase in GFDL/CM2.0 and CNRM/CM3 models and decreases in IPSL/CM4 an...     

Preliminary results of the study on wind erosion in the Qinghai-Tibetan Plateau using 137Cs technique

The worldwide fallout of caesium-137 (137Cs) associated with the nuclear weapon tests during the 1950s and 1960s has provided a valuable man-made tracer for studies of soil erosion and sediment delivery. But relatively few researchers have used it to estimate wind erosion. In this note, the 137Cs technique is introduced into the studies of wind erosion and its modern processes in the Qinghai-Tibetan Plateau. Two 137Cs reference inventories of 982.11 and 2 376.04 Bq·m-2 were established preminarily, distributed in the south and middle-north parts of the studied area respectively. By analyzing the patterns of 137Cs depth profiles from sampling sites, the aeolian processes of erosion and deposition in nearly 40 years have been revealed, i.e. the shrub coppice dunes (S1) and semi-fixed dunefields (S3) experienced the alternation of erosion and deposition, while the grasslands (S4, S6 and S7) and dry farmlands (S5) suffered erosion only. By using 137Cs model, the average wind erosion rates for shrub coppice dune (S1), semi-fixed dune fields (S3), dry farmlands (S5) and grasslands (S4, S6 and S7) were estimated to be 84.14, 69.43, 30.68 and 21.84 t·ha-1·a-1 respectively, averaging 47.59 t·ha-1·a-1 for the whole plateau, which can be regarded as of the medium erosion standard. These results derived from 137Cs for the first time have significant implications for the further research of wind erosion and desertification control in the Qinghai-Tibetan Plateau.     

Reaction of CH radical with O<Subscript>2</Subscript> by time-resolved FTIR spectroscopy

The Methylidyne radical, CH, plays a crucial role in several complex environments such as planetary atmos- pheres and interstellar clouds, and is one of the most im- portant and active intermediate in hydrocarbon flames[1]. The CH involving reactions, including chemiionization, oxidation of hydrocarbons, the soot formation[2—5], and especially the formation of prompt NO[6], are of funda- mental interest in combustion chemistry, owing to the high reactivity and the large enthalpy of formatio…     

Chemical quenching and inhibition of positronium in Cr<Subscript>2</Subscript>O<Subscript>3</Subscript>/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalysts

The pore structure of Cr2O3/Al2O3 catalysts and the surface chemical properties of these pores were characterized by positron lifetime and coincidence Doppler broadening (CDB) measurements. Four lifetime components could be resolved from the positron lifetime spectrum, with two long lifetime components and two short lifetime components. The two long lifetimes τ4 and τ3 are attributed to ortho-positronium (o-Ps) annihilation in large pores and microvoids, respectively. With increasing Cr2O3 content, both τ4 and its intensity I4 show sharp decrease, while τ3 and its intensity I3 keep nearly unchanged. The Doppler broadening S parameters also show sharp decrease with increasing Cr2O3 content. Detailed analysis of the CDB spectrum reveals that the parapositronium (p-Ps) intensity also decreases with increasing Cr2O3 content. This indicates that the change of o-Ps lifetime τ4 is due to the chemical quenching by Cr2O3 but not spin-conversion of positronium. The decrease of o-Ps intensity I4 indicates that Cr2O3 also inhibits positronium formation.     

Synthesis of highly ordered SnO2／Fe2O3 composite nanowire arrays by electrophoretic deposition method

Highly ordered SnO2/Fe2O3 composite nanowire arrays have been synthesized by electrophoretic deposition method. The morphology and chemical composition of SnO2/Fe2O3 composite nanowire arrays are characterized by SEM, TEM, EDX, XPS, and XRD. The results show that the SnO2/Fe2O3 composite nanowires are about 180 nm in width and tens of microns in length, and they are composed of small nanoparticles of tetraganal SnO2 and rhombohedral α-Fe203 with diameters of 10-15nm. The SnO2/Fe2O3 composite nanowires are formed by a series of chemical reactions.     

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.     

Nonlinear optical properties of Eu<Subscript>2</Subscript>O<Subscript>3</Subscript> doped 5ZnO-20Nb<Subscript>2</Subscript>O<Subscript>5</Subscript>-75TeO<Subscript>2</Subscript> glasses

The third-order optical nonlinearities, including third-order nonlinear susceptibility X^(3), nonlinear refractive index (n2) and temporal response, were measured with forward DFWM using Nd:YAG mode-locked pulse laser. The results show that Eu203 doped 5ZnO-20Nb2O5-75TeO2 glasses have large n2 and ultra-fast temporal response. Raman spectra show that Eu2O3 dopant induces the changes in the local structure of glasses. The higher the dopant concentration, the larger the nonlinear refractive n2 and the faster the temporal response. The enhancement on the third-order optical nonlinearities can be attributed to the deformation of the electronic clouds in [TeO4] enhanced by Eu2O3 dopant.     

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.     

Adsorption and catalytic combustion of ARB on CuO-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>

CuO-Fe2O3 composite material with strong magnetism and a large surface area is prepared by the co-precipitate method. Its adsorption properties towards Acid Red B (ARB) and the regeneration by catalytic combastion of organic compounds have been studied. The results show that the prepared CuO-Fe2O3 composite is an excellent adsorbent for ARB adsorption at acid condition. The presence of Cl^- has no effect on ARB adsorption. But the SO4^2- can inhibit ARB adsorption. After being recovered by the magnetic separation method, the adsorbent can be regenerated by catalytic oxidation of absorbate at 300℃ in air atmosphere. The combustion reactions of ARB in the presence or absence of CuO-Fe2O3 are studied by in situ diffuse refieclion FTIR. The results indicate that, in the presence of CuO-Fe2O3, the degradation temperature is significantly lowered by the catalysis of CuO-Fe2O3, and ARB can be oxidized completely without volatile organic compound by-product; in comparison, in the absence of CuO-Fe2O3, the temperature needed for oxidation of ARB is higher and the reaction is incomplete with some N-containing harmful compounds produced. The reusability of CuO-Fe2O3 is also studied in successive seven adsorption-regeneration cycles.     

Climate as the dominant control on C<Subscript>3</Subscript> and C<Subscript>4</Subscript> plant abundance in the Loess Plateau: Organic carbon isotope evidence from the last glacial-interglacial loess-soil sequences

Two modes of photosynthesis predominate in terres-REPORTS trial plants: the C3 and C4 modes[1]. The C3 mode is used by all of trees, bushes, and cold season grasses. The C4 mode is used by the most of tropical and warm season grasses. They are disadvantaged relative to C3 plants at high CO2/O2 ratios because of the additional energy ex-pense needed to concentrate CO2 in the bundle-sheath cells. At low CO2/O2, however, C4 plants can achieve a relatively high quantum yield by suppressin…     

Synthesis of LiCo<Subscript>0.3</Subscript>Ni<Subscript>0.7</Subscript>O<Subscript>2</Subscript> as cathode materials for lithium ion batteries by citric acid-assisted sol-gel method

The synthesis process of LiCo0.3Ni0.7O2 was investigated by FT-IR, mass spectroscopy, elemental analysis, SEM, BET, TG/DTA and XRD in this paper. The results revealed that lithium and transition metal ions were trapped homogeneously on an atomic scale throughout the precursor. Li2CO3, NiO and CoO are the intermediate products obtained after decomposition of the precursor and Li2CO3 undergoes direct reactions with NiO and CoO to form LiCo0.3Ni0.7O2. Moreover, the kinetics of formation of LiCo0.3Ni0.7O2 by dtrate sol-gel method is faster than the case of the conventional solid-state reaction between lithium carbonate and corresponding reactants. The single phase of LiCo0.3Ni0.7O2 was synthesized at temperature as low as 550℃. The discharge capacity of LiCo0.3Ni0.7O2 increases from 127 to 185 mAh/g as the caldnation temperature increasing from 550 to 750℃. After 100 cycles, the discharge capacity of the sample calcined at 750℃ is 155 mAh/g. The electrochemical study shows that the LiCo0.3Ni0.7O2 has high discharge capacity and good cycling behavior for lithium ion batteries.