MOLECULAR CHARACTERISTICS AND CRYSTALLINE-STRUCTURE OF ETHYLENE-DIMETHYLAMINOETHYL-METHACRYLATE COPOLYMERS

The relationship between molecular and crystalline structural characteristics of the ethylene -dimethylaminoethylmethacrylate copolymers (EDAM) was investigated and related to melt flow index MI and average gross content of DAM comonomer, in comparison with low density polyethylene (LDPE) produced by the common high-pressure radical polymerization process. Although the average molecular weight and its distribution are influenced predominantly by the polymerization conditions, DAM-content seems not to depend significantly on molecular weight according to the GPC-FT/IR measurement. Comonomer sequence distributions were determined quantitatively with the C-13-NMR spectra entirely assigned by DEPT and H-1-C-13 COSY techniques. The result suggests the alternating copolymerization tendency and surprisingly coincides with the simulation out-puts based on the assumption of continuous complete mixing reactor model, using Mayo-Lewis equation and the same Q-e values as previously reported on different types of copolymers such as EVA and St.DAM (VA;vinylacetate, St;styrene). It was confirmed by WAXD and SAXS analyses that the crystallinity X(c) and the thickness of lamellar crystal l(c) decreased with increasing DAM-content, whereas the a-lattice and b-lattice dimensions enlarged. X(c) and l(c) can definitely be correlated to the heats of fusion and crystallization measured by DSC. The average size of spherulites measured with light scattering photometry tends to be enlarged with decreasing molecular weight (increasing MI) and DAM-content.

GENERAL ALPHA-N INDEX AND ITS APPLICATION .1. GENERAL ALPHA-N INDEX AND ITS APPLICATION IN THE EXTRACTION OF Y, CE, U, AND TH BY NEUTRAL PHOSPHORUS EXTRACTANCTS

The general a(N) index is established for molecules containing heteroatoms, rings, and multiple bonds. The general a(N) index is able to describe molecules with minute differences in structure and can also reveal the properties of molecules. This theory is successfully applied to the case of neutral phosphorus extractants. Both the molecular polarity and steric effect are characterized by the general a(N) index. The relationships between these properties and the distribution ratios for extracting Y, Ce, U, and Th are also shown by the general a(N) index.

ELECTRONIC-STRUCTURE AND CHEMICAL BONDING OF EUROPIUM NITRATE COMPLEX WITH AZACROWN (2, 2)

The electronic structure and bond character of europium nitrate complex with azacrown (2, 2)(1, 7, 10, 16-tetraoxa-4, 13-diazacyclooctadecane), [Eu(NO_3)_2(2, 2)] NO_3, have been studied by means of XPS and INDO method. The data of electronic binding energies and charge distribution of atoms in the complex showed that chemical shift of less electronegative nitrogen N1s binding energy was larger than that of more electronegative oxygen O1s binding energy in coordinating atoms, and that charge transfer from N...

Tectonic geomorphology of the Ryukyu Trench-Arc-Backarc System: geological-geophysical exploration and mapping

OKINAWA TROUGH; BASIN

REE and epsilon(Nd) of clay fractions in sediments from the eastern Pacific Ocean: Evidence for clay sources

Clay fractions in the non-calcareous surface sediments from the eastern Pacific were analyzed for clay minerals, REE and Nd-143/Nd-144. Montmorillonite/illite ratio (M/I ratio), total REE contents (Sigma REE), LREE/HREE ratio and cerium anomaly (delta Ce) may effectively indicate the genesis of clay minerals. Clay fractions with M/I ratio > 1, delta Ce < 0.85, Sigma REE > 400 mu g/g, LREE/HREE ratio approximate to 4, and REE patterns similar to those of pelagic sediments are terrigenous and autogenetic mixed clay fractions and contain more autogenetic montmorillonite. Clay fractions with M/I ratio < 1, delta Ce=0.86 to 1.5, Sigma REE=200 to 350 mu g/g, LREE/HREE ratio approximate to 6 and REE distribution patterns similar to that of China loess are identified as terrigenous clay fraction. The Nd-143/Nd-144 ratios or epsilon(Nd) values of clay fractions inherit the features of terrigenous sources of clay minerals. Clay fractions are divided into 4 types according to epsilon(Nd) values. Terrigenous clay minerals of type I with the eNd values of -8 to -6 originate mainly from North American fluvial deposits. Those of type 11 with the epsilon(Nd) Values of -9 to -7 are mainly from the East Asia and North American fluvial deposits. Those of type III with epsilon(Nd) values of -6 to -3 could come from the central and eastern Pacific volcanic islands. Those of type IV with epsilon(Nd) values of -13 to -12 may be from East Asia eolian. The terrigenous and autogenetic mixed clay fractions show patchy distributions, indicating that there are volcanic or hot-spot activities in the eastern Pacific plate, while the terrigenous clay fractions cover a large part of the study area, proving that the terrigenous clay minerals are dominant in the eastern Pacific.

Response of coastal marine eco-environment to river fluxes into the sea: A case study of the Huanghe (Yellow) River mouth and adjacent waters

The impact of the Huanghe (Yellow) River outflows on its estuary was investigated with river gauging and shipboard hydrographic observations. The river flux has been decreasing dramatically; the discharges of water and sediment in the 1990s dropped to 27.4% and 31.9% of those in the 1950s, respectively, resulting in frequent and lengthy events of downstream channel dry-up since the 1970s. There were accumulatively 897 zero-flow days during the 1990s in the river course below the Lijin Hydrological Station, 100 km upstream from the river mouth, which is 82.4% of that in 1972. As freshwater input decreases, river-borne nutrients to the estuarine increased significantly. Concentration of dissolved inorganic nitrogen (DIN) in the 1990s was four times of that in 1950s. Changes in amount and content of the riverine inputs have greatly affected the estuarine ecosystem. Over the past several decades, sea surface temperature and salinity in the estuary and its adjacent waters increased and their distribution pattern altered in response to the reduction of freshwater inflow. The distribution of and seasonal succession in nutrient concentrations in the surface layer have also changed with a shift of river outlet and the decrease in riverine nutrient loads. Furthermore, deterioration of estuarine ecosystem by less river input has decreased primary productivity in the deltaic region waters, and in turn depressed the fishery. (C) 2008 Published by Elsevier Ltd.

The characteristics of BSRs and their derived heat flow on the profile 973 in the northeastern South China Sea

Processing of a recently acquired seismic line in the northeastern South China Sea by Project 973 has been conducted to study the character and the distribution of gas hydrate Bottom-Simulating Reflectors (BSRs) in the Hengchun ridge. Analysis of different-type seismic profiles shows that the distribution of BSRs can be revealed to some extents by single-channel profile in this area, but seismic data processing plays an important role to resolve the full distribution of BSRs in this area. BSR' s in the northeastern South China Sea have the typical characteristics of BSRs on worldwide continental margins: they cross sediment bed reflections, they are generally parallel to the seafloor and the associated reflections have strong amplitude and a negative polarity. The characteristics of BSRs in this area are obvious and the BSRs indicate the occurrence of gas hydrate-bearing sediments in the northeastern South China Sea. The depth of the base of the gas-hydrate stability zone was calculated using the phase stability boundary curve of methane hydrate and gas hydrate with mixture gas composition and compared with the observed BSR depth. If a single gradient geothermal curve is used for the calculation, the base of the stability zone for methane hydrate or gas hydrate with a gas mixture composition does not correspond to the depth of the BSRs observed along the whole seismic profile. The geothermal gradient therefore changes significantly along the profile. The geothermal gradient and heat flow were estimated from the BSR data and the calculations show that the geothermal gradient and heat flow decrease from west to east, with the increase of the distance from the trench and the decrease of the distance to the island arc. The calculated 2 heat flow changes from 28 to 64 mW/m(2), which is basically consistent with the measured heat flow in southwestern offshore Taiwan.

Phytoplankton distributions and their relationship with the environment in the Changjiang Estuary, China

This study was carried out in the Changjiang Estuary from 19 to 26 May 2003. Based on the data collected from 29 stations, including two anchor stations, phytoplankton taxonomic composition, abundance, diurnal variability and spatial distribution were examined. Eighty-seven species, including 54 species of diatoms and 16 red tide causative species, were identified. Average diversity index (H') and evenness (J) values were 1.04 and 0.40, respectively. A bloom in abundance of certain phytoplankton species, especially Prorocentrum dentatum and Skeletoneina costatum, was thought to be the cause of the low diversity index and evenness values. Total phytoplankton abundance averaged 6.75 x 10(5) cells 1(-1), and was much higher than previous investigation carried out in the same month in 1986. Abundance increased seaward showing a distinct spatial difference, and the dominant species varied with salinity. Correlation between phosphorus and abundance further supported the former conclusion that phosphorus is the controlling factor in phytoplankton growth in the Changjiang Estuary where light is not limiting. Based on the relationship between DO, pH and abundance, it is likely that the bloom was caused by rapid in situ growth of phytoplankton with high nutrients and sufficient light. The data also indicated that the duration of the bloom was not long and

Digestive gut structure and activity of protease, amylase, and alkaline phosphatase in Calanus sinicus during summer in the Yellow Sea and the East China Sea

Calanus sinicus aggregate at the depth of 40-60 m (ambient temperature is 16 degreesC) in the waters of the continental shelf of the Yellow Sea during summer. in animals found in near shore regions, there are changes in digestive gut cells structure, digestive enzyme activity (protease, amylase), and tissue enzyme (alkaline phosphatase (ALP)), which may represent adaptations by this cold-water animal to a sharp seasonal increase in temperature of 6-23 degreesC. The activities of the digestive enzymes (protease and amylase) are very low in animals at stations near the estuary of Yangtse River, whereas they are relatively high in animals at stations in the central Yellow Sea, During summer, B-cells of the intestine and the villi intestinalis disappear in animals that do not feed at stations near the estuary of the Yangtse River. Respiration rates were undetectable or quite low during summer in C. sinicus from stations near the estuary of the Yangtse River, whereas they were relatively high at stations in the central Yellow Sea. Based upon the morphological characteristics of the digestive gut structure, enzyme levels, respiration rates, and the distribution of C. sinicus, we concluded that C. sinicus might be dormant during summer in the near shore areas of the East China Sea while remaining active in the central Yellow Sea. (C) 2002 Elsevier Science B.V. All rights reserved.

Size dependence of biomass spectra and abundance spectra: the optimal distributions

Based on the hypothesis of self-optimization, we derive four models of biomass spectra and abundance spectra in communities with size-dependent metabolic rates. In Models 1 and 2, the maximum diversity of population abundance in different size classes subject to the constraints of constant mean body mass and constant mean respiration rate is assumed to be the strategy for ecosystems to organize their size structure. In Models 3 and 4, the organizing strategy is defined as the maximum diversity of biomass in different size classes without constraints on mean body mass and subject to the constant mean specific respiration rate of all individuals, i.e. the average specific respiration rate over all individuals of a community or group, which characterizes the mean rate of energy consumption in a community. Models 1 and 2 generate peaked distributions of biomass spectral density whereas Model 3 generates a fiat distribution. In Model 4, the distributions of biomass spectral density and of abundance spectral density depend on the Lagrangian multipler (lambda (2)). When lambda (2) tends to zero or equals zero, the distributions of biomass spectral density and of abundance spectral density correspond to those from Model 3. When lambda (2) has a large negative value, the biomass spectrum is similar to the empirical fiat biomass spectrum organized in logarithmic size intervals. When lambda (2) > 0, the biomass spectral density increases with body mass and the distribution of abundance spectral density is an unimodal curve. (C) 2001 Elsevier Science B.V. All rights reserved.

Decline in medicinal and forage species with warming is mediated by plant traits on the Tibetan Plateau

Experimental studies of how global changes and human activities affect plant diversity often focus on broad measures of diversity and discuss the implications of these changes for ecosystem function. We examined how experimental warming and grazing affected species within plant groups of direct importance to Tibetan pastoralists: medicinal plants used by humans and palatable plants consumed by livestock. Warming resulted in species losses from both the medicinal and palatable plant groups; however, differential relative vulnerability to warming occurred. With respect to the percent of warming-induced species losses, the overall plant community lost 27%, medicinal plants lost 21%, and non-medicinal plants lost 40% of species. Losses of palatable and non-palatable species were similar to losses in the overall plant community. The deep-rootedness of medicinal plants resulted in lowered sensitivity to warming, whereas the shallow-rootedness of non-medicinal plants resulted in greater sensitivity to warming; the variable rooting depth of palatable and non-palatable plants resulted in an intermediate response to warming. Predicting the vulnerability of plant groups to human activities can be enhanced by knowledge of plant traits, their response to specific drivers, and their distribution within plant groups. Knowledge of the mechanisms through which a driver operates, and the evolutionary interaction of plants with that driver, will aid predictions. Future steps to protect ecosystem services furnished by medicinal and palatable plants will be required under the novel stress of a warmer climate. Grazing may be an important tool in maintaining some of these services under future warming.

Pollen morphology and its in systematic and ecological significance in Rheum (Polygonaceae) from China

Pollen morphology of 40 species of Rheum, belonging to eight sections, was investigated under LM and SEM. Four new exine patterns were found in the species: a) microcchinate-foveolate, b) rugulate, c) verrucate-perforate, and d) verrucaterugulate ornamentation. In addition, two patterns, the Rheum-type pollens with microechinate-perforate and fine-reticulate, as previously described, were also confirmed in the present study. Based on above study the evolution trends of pollen morphology in the taxa involved were discussed phylogenetically as below. As microechinate-perforate exine pattern existed commonly, the pattern is, therefore, regarded as the most primitive among all the six types. The fine-reticulate type was thought as a derivative type, deriving from the basic micro echinate-foveolate-perforate pattern, and followed by the rugulate and verrucate-perforate ornamentation. The verrucate-rugulate ornamentation should be the most advanced. More than one pollen type often exist in most of the sections in Rheum. The pollen morphology of Rheum was strongly correlated with its geographical and ecological distribution. Three medicinally important species R. officinale, R. palmation and R. tanguticum can be palynologically distinguished by their ornamentations.

Assessing the potential of VEGETATION sensor data for mapping snow and ice cover: a Normalized Difference Snow and Ice Index

The VEGETATION (VGT) sensor in SPOT 4 has four spectral bands that are equivalent to Landsat Thematic Mapper (TM) bands (blue, red, near-infrared and mid-infrared spectral bands) and provides daily images of the global land surface at a 1-km spatial resolution. We propose a new index for identifying and mapping of snow ice cover, namely the Normalized Difference Snow/Ice Index (NDSII), which uses reflectance values of red and mid-infrared spectral bands of Landsat TM and VGT. For Landsat TM data, NDSII is calculated as NDSIITM =(TM3 -TM5)/(TM3 +TM5); for VGT data, NDSII is calculated as NDSIIVGT =(B2- MIR)/(B2 + MIR). As a case study we used a Landsat TM image that covers the eastern part of the Qilian mountain range in the Qinghai-Xizang (Tibetan) plateau of China. NDSIITM gave similar estimates of the area and spatial distribution of snow/ice cover to the Normalized Difference Snow Index (NDSI=(TM2-TM5)/(TM2+TM5)) which has been proposed by Hall et al. The results indicated that the VGT sensor might have the potential for operational monitoring and mapping of snow/ice cover from regional to global scales, when using NDSIIVGT.

Size-controllable synthesis of monodispersed SnO2 nanoparticles and application in electrocatalysts

Size-controllable tin oxide nanoparticles are prepared by heating ethylene glycol solutions containing SnCl2 at atmospheric pressure. The particles were characterized by means of transmission electron microscopic (TEM), X-ray diffraction (XRD) studies. TEM micrographs show that the obtained material are spherical nanoparticles, the size and size distribution of which depends on the initial experimental conditions of pH value, reaction time, water concentration, and tin precursor concentration. The XRD pattern result shows that the obtained powder is SnO2 with tetragonal crystalline structure. On the basis of UV/vis and FTIR characterization, the formation mechanism of SnO2 nanoparticles is deduced. Moreover, the SnO2 nanoparticles were employed to synthesize carbon-supported PtSnO2 catalyst, and it exhibits surprisingly high promoting catalytic activity for ethanol electrooxidation.

Copper phthalocyanine on InSb(111)A?interface bonding, growth mode and energy band alignment

Copper phthalocyanine on InSb(111)A?interface bonding, growth mode and energy band alignment, D.A. Evans, H.J. Steiner, S. Evans, R. Middleton, T.S. Jones, S. Park, T.U. Kampen, D.R.T. Zahn, G. Cabailh and I.T. McGovern, J. Phys.: Condens. Matter, 15, S2729?S2740, (2003)