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BACKGROUND Axillary lymph node metastases (ALNM) is one of the most important prognostic factors in breast cancer. Positron emission tomography / computed tomography (PET/CT) and magnetic resonance imaging (MRI) are increasingly used to assess ALNM noninvasively. There has been no study investigating PET/CT and MRI in direct comparative studies. PURPOSE To assess the diagnostic accuracy of PET/CT and MRI for ALNM in the same population of breast cancer. STUDY TYPE Systematic review and meta-analysis. DATA SOURCE PubMed-MEDLINE, Web of Science, Cochrane, EMBASE, and Chinese Biomedical Literature databases were searched (September 1993-January 2020) by using concerned keywords. Studies using both MRI and PET/CT as diagnostic methods were included. Eleven studies included 1203 breast cancer patients using PET/CT and 1186 patients using MRI. FIELD STRENGTH 1.5T or 3.0T. ASSESSMENT The Quality Assessment of Diagnostic Accuracy Studies (v. 2) was used to assess the quality of the studies. STATISTICAL TESTS A bivariate mixed-effects binary regression model was used to obtain the diagnostic performance. Meta-regression analysis was conducted to investigate study heterogeneity. RESULTS A total of 369 articles were screened; out of these, 11 studies were included that meet the inclusion criteria. The respective pooled sensitivity and specificity values were 0.56 (95% confidence interval [CI]: 0.47-0.63) and 0.91 (95% CI: 0.87-0.93) for PET/CT and 0.55 (95% CI: 0.48-0.62) and 0.86 (95% CI: 0.82-0.89) for MRI. There was no statistically significant difference in sensitivity (P = 0.769) or specificity (P = 0.447) between PET/CT and MRI. There was no threshold effect in either of the imaging tests. The diagnostic performance of both imaging tests was affected by study design, breast cancer subtype, tumor stage, or imaging features. DATA CONCLUSION In the same population, PET/CT and MRI had comparable diagnostic performance for the detection of ALNM, with low sensitivity and high specificity. LEVEL OF EVIDENCE 3. TECHNICAL EFFICACY STAGE Stage 2. J. MAGN. RESON. IMAGING 2020;52:1840-1851.

Soil erodibility is an essential parameter used in soil erosion prediction. This study selected the Liangshan town watershed to quantify variation in the vertical zonality of rill erodibility (k(r)) in China's ecologically fragile Hengduan Mountains. Soil types comprised of yellow-brown (soil A), purple (soil B), and dry-red (soil C) in a descending order of occurrence from the summit to the valley, which roughly corresponds to the vertical climate zone (i.e. cool-high mountain, warm-low mountain, and dry-hot valley sections) of the study area. With elevation, vertical soil zonality varied in both soil organic matter (SOM) content and soil particle-size fractions. A series of rill erosion-based scour experiments were conducted, using water discharge rates of 100, 200, 300, 400, 500, and 600 mL min(-1). Additionally, detachment rates (Dr) were measured under three hydrological conditions (the drainage, saturation, and seepage treatments). Results show that both Dr and flow shear stress (&) values increased as discharge increased. As elevation increased, the k(r) values decreased, while the vertical zonality of critical shear stress (&(c)) values showed no obvious variation. The highest k(r) values were observed during the seepage treatment, followed by the saturation treatment then drainage treatment, indicating that variation in vertical hydraulic gradients could significantly alter k(r) values. This study also found that land-use types could also alter k(r) and &(c) values. Further research, however, is necessary to better quantify the effects of subsurface hydrological conditions and land-use types on k(r) under different soil zonalities in China's Hengduan Mountains. (c) 2018 John Wiley & Sons, Ltd.

Calligonum mongolicum is a successful pioneer shrub to combat desertification, which is widely used for vegetation restoration in the desert regions of northwest China. In order to reveal the limitations to natural regeneration of C. mongolicum by asexual and sexual reproduction, following the process of sand dune stabilization, we assessed clonal shoots, seedling emergence, soil seed bank density, and soil physical characteristics in mobile and stabilized sand dunes. Controlled field and pot experiments were also conducted to assess germination and seedling emergence in different dune soil types and seed burial depths. The population density of mature C. mongolicum was significantly different after sand dune stabilization. Juvenile density of C. mongolicm was much lower in stabilized sand dunes than mobile sand dune. There was no significant difference in soil seed bank density at three soil depths between mobile and stabilized sand dunes, while the emergence of seedlings in stabilized dunes was much lower than emergence in mobile dunes. There was no clonal propagation found in stabilized dunes, and very few C. mongolicum seedlings were established on stabilized sand dunes. Soil clay and silt content, air-filled porosity, and soil surface compaction were significantly changed from mobile sand dune to stabilized dunes. Seedling emergence of C. mongolicm was highly dependent on soil physical condition. These results indicated that changes in soil physical condition limited clonal propagation and seedling emergence of C. mongolicum in stabilized sand dunes. Seed bank density was not a limiting factor; however, poor seedling establishment limited C. mongolicum's further natural regeneration in stabilized sand dunes. Therefore, clonal propagation may be the most important mode for population expansion in mobile sand dunes. As a pioneer species C. mongolicum is well adapted to propagate in mobile sand dune conditions, it appears unlikely to survive naturally in stabilized sand dune plantations.

Nitrogen-doped nanoporous carbons have been successfully synthesized by direct carbonization of a nitrogen- rich metal-biomolecule framework, zinc glutamate (Zn(H2O)(C5H7NO4)·H2O), as a template without any additional carbon or nitrogen sources. The surface area and pore size distribution of the resultant carbon materials were studied based on the carbonization temperature. These carbons exhibited high specific surface area (as high as 1619.2 m2·g−1 for ZGC-1000). Furthermore, ZGC-1000 also provided a large specific capacitance of 140.8 F·g−1 at a current density of 0.25 A·g−1 when measured in a three-electrode system. It is believed that the presence of the nitrogen-doped nanoporous carbons prepared from the metal-organic frameworks will further facilitate the exploration of such materials as supercapacitors.

Tuning the bandgap and cytotoxicity of ZnO nanoparticles (NPs) is very important, not only for customizing their optoelectronic and biomedical applications, but also for their cytotoxicity assay and safe usage. A unique soft-template of polyvinylpyrrolidone has been developed here to realize a rapid room-temperature neutral synthesis of ZnO with controlled nanostructures for tuning the bandgap and cytotoxicity of ZnO. By simply changing the reagent stoichiometry and the soft-template shape, high-purity ZnO rods, tripods, tubes, and unique T-like tubes with tunable size, surface composition/charge, bandgap, and cytotoxicity are obtained. It has been revealed that the ZnO bandgap can be remarkably reduced by introducing the surface nonstoichiometry; and the ZnO-induced cytotoxicity can be tuned by the size, shape, surface charge/composition, and bandgap of ZnO NPs at different degrees. Significantly, both the photochemistry reaction and the reactive oxygen species induced by ZnO NPs are not necessary for the ZnO-induced cytotoxicity.

Research on how tillage-induced soil redistribution affects soil properties is limited for complex slopes in nonmechanized agricultural areas. The objectives of this study are (1) to examine the vertical redistribution of soil organic C (SOC), extractable P and K induced by tillage on a complex slope, (2) to assess the effects of tillage erosion on soil profile properties, and (3) to elucidate the variations in soil properties induced by both vertical mixture and downslope transport of soil within the landscape. Simulated tillage was conducted in the Yangtze Three Gorges Reservoir Area, China. The Cs-137 data showed that intense tillage caused the soil vertical mixture and downslope transport. The redistribution of Cs-137 and soil constituents varied with the number of tillage passes and location in relation to curvature. SOC was completely depleted with the disappearance of soil profiles at the summit position, while SOC concentrations decreased by 26% for the till layer and increased by 29% for the sublayer at the toeslope position for the 15-tillage operation, as compared with those of pretillage. The vertical redistribution of extractable P and K followed a similar pattern to that of SOC. The gap and variation in soil constituents between the till layer and sublayer declined after tillage, suggesting that the mixing effect of tillage attenuates the variability of soil properties in the vertical direction. Net loss and gain of soil constituents occurred at the summit and toeslope positions, respectively, suggesting that the downslope transport of soil induced by tillage accentuates the variability of soil properties in the lateral direction.

Few studies have demonstrated soil redistribution under upslope tillage (UT) rather than downslope tillage (DT) and its impact on soil organic carbon (SOC) redistribution in long-term agricultural practices in hillslope landscapes. We selected two neighbouring sites from the Sichuan Basin, China, one under DT and the other under UT, to determine the pattern of soil and SOC redistribution under a long-term UT practice. DT caused soil loss at upper slope positions and soil accumulation at lower slope positions. However, UT resulted in soil accumulation at upper slope positions and soil loss at lower slope positions. The total erosion rate decreased by 60.5% after 29years of UT compared with DT. Having the same direction of soil movement by tillage and water exaggerated total soil loss, whereas having the two movements in the contrasting direction of soil for the two reduced it. SOC stocks at positions from summit to downslope were much larger (33.8%) and at toe-slope positions were only slightly greater (4.5%) in the UT soils than comparable values for the DT site. The accumulation rate of SOC at the UT site increased by 0.26Mg/ha/year compared with that at the DT site. It is suggested that soil movement by water and tillage erosion occurred in the same direction accelerates the depletion of SOC pools, whereas the opposite direction of soil movement for the two can increase SOC accumulation. Our results suggest that UT has significant impacts on soil redistribution processes and SOC accumulation on steeply sloping land.

The facts that the global carbon budget cannot be currently balanced and current estimates of agricultural sources and sinks may be inaccurate, may be linked to unaccounted-for erosion-induced changes in soil organic carbon (SOC). A closed landscape with field banks and an open landscape without field banks were selected from two sites located in Jianyang County, Sichuan Province, and Zhongxian County, Chongqing Municipality, respectively. In these landscapes, the role of tillage and water erosion was examined using measurements of soil redistribution in relation to 137Cs radionuclide depth-stratigraphy, to elucidate the mechanism of SOC depth distribution in the soil profile and resultant stocks in agricultural landscapes of terraced field systems. Changes in the 137Cs inventory at different landscape positions depend on both 137Cs concentrations of individual subsample layers (5-cm depth) and the vertical extent of 137Cs depth distribution in the terrace system with field banks, while the changes are only associated with the vertical extent of 137Cs depth distribution in the terrace system without field banks because of similar 137Cs concentrations of individual subsample layers. The profile shape of SOC depth distribution exhibits notable differences between the upper and lower parts of the terrace in systems with field banks, but no apparent differences were found in the systems without field banks and the SOC profile shape is similar to that of the upper part of the terrace in systems with field banks. It is suggested that SOC depth distribution in these two types of terraced field systems is controlled by different soil erosion patterns. Tillage erosion playing a dominant role in the process of soil erosion within a landscape can increase SOC stocks. However, SOC depletion takes place in situations where the two processes of tillage and water erosion are both important and tillage erosion acts as a delivery mechanism for water erosion. We conclude that tillage erosion plays a dual role: enhancing carbon storage at depositional positions, and accelerating carbon depletion when combined with water erosion within the same landscape.

A poly (acryl acid) (PAA) post-treatment method is performed to modify the surface charge of ZnO nanospheres, hematite nanocubes, and Ag nanoprisms from highly positive to very negative by adjusting the PAA concentration, to and greatly modify their photoluminescence, cytotoxicity, magnetism, and surface plasmon resonance. This method provides a general way to tune the nanoparticle properties for broad physicochemical and biological applications.

SUMMARY In wireless sensor networks, most data aggregation scheduling methods let all nodes aggregate data in every time instance. It is not energy efficient and practical because of link unreliability and data redundancy. This paper proposes a lossy data aggregation (LDA) scheme to reduce traffic and save energy. LDA selects partial child nodes to sample data at partial time slots and allows estimated aggregation at parent nodes or a root in a network. We firstly consider that all nodes sample data synchronously and find that the error between the real value of a physical parameter and that measured by LDA is bounded respectively with and without link unreliability. Detailed analysis is given on error bound when a confidence level is previously assigned to the root by a newly designed algorithm. Thus, each parent can determine the minimum number of child nodes needed to achieve its assigned confidence level. We then analyze a probability to bound the error with a confidence level previously assigned to the root when all nodes sample data asynchronously. An algorithm then is designed to implement our data aggregation under asynchronization. Finally, we implement our experiment on the basis of real test-beds to prove that the scheme can save more energy than an existing algorithm for node selection, Distributive Online Greedy (DOG). Copyright © 2012 John Wiley & Sons, Ltd.

New fluorescein isothiocyanate/fluorescein/rhodamine B-doped ZnO composite nanostructures including tripods, tubes, and rods with tuned sizes have been designed and synthesized to greatly enhance the dye fluorescence up to ∼90 fold. The great fluorescence enhancement mainly arises from the interaction between Zn 2+ ions in the ZnO matrix and the dye carbonyl group. The refraction index difference between ZnO and the dyes used here and the segregation of the dye molecules by the ZnO matrix only slightly contribute to the fluorescence enhancement. The control pure ZnO sample has no emission in the dye fluorescence range (500-650 nm) and excludes the possible contribution of the ZnO emission and the relevant energy transfer between the dye and ZnO to the fluorescence enhancement. These composites with the new fluorescence enhancement mechanism not only facilitate dye applications such as medical diagnostics and biotechnology, but also supply a novel and general approach to improve the fluorescence of organic dyes with carbonyl group by doping them into metal oxides.

The mechanism of the reaction N2O(1Σ+)+CO(1Σ+)N2(1Σ)+CO2(1Σ) catalyzed by Cr+ has been investigated on sextet and quartet potential energy surfaces. The reactions are studied by using the UB3LYP density functional method and the standard 6-311+G(2d) basis sets. The geometries for reactants, the transition states and the products are completely optimized. The result shows that the reaction proceeds in a two-step manner, each mechanism are insertion-elimination and rearrangement mechanism. The involved crossing between the two potential energy surfaces have been discussed by means of the intrinsic reaction coordinate (IRC) approach, and the crossing points (CPs) are located. The minimum energy crossing point (MECP) that we obtained by the mathematical algorithm proposed by Harvey et al. has been also employed. Then the action of frontier molecular orbitals in MECPs were illuminated briefly. Finally, O-atom affinities (OA) testified that the argumentation is thermodynamically allowed.

A new chemically modified chitosan hydrogel with 2,5-dimercapto-1,3,4-thiodiazole (CTS-DMTD) has been synthesized. The structure of CTS-DMTD was confirmed by elemental analysis and FTIR. It was found that adsorption capacities were significantly affected by the pH of solution, with optimum pH values of 3.0 for Au(III), 2.0 for Pd(II) and Pt(IV). The saturated adsorption capacities were 198.5 mg/g for Au(III), 16.2 and 13.8 mg/g for Pd(II) and Pt(IV), respectively. Langmuir and Freundlich isotherm adsorption models were applied to analyze the experimental data. The results showed that adsorption isotherms of Pd(II) and Pt(IV) could be well described by the Langmuir equation. The adsorption kinetic investigations indicated that the kinetic data correlated well with the pseudo-second-order model. The recovery experimental data showed that CTS-DMTD had a higher affinity toward Au(III), Pd(II), and Pt(IV) in the coexistence system containing Cu(II), Fe(III), Cd(II), Ni(II), Mg(II), and Zn(II). The studies of desorption were carried out using various reagents and the optimum effect was obtained using thiourea. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Little is known about soil redistribution by tillage and its impact on the properties of soil profiles with thin soil layers on hillslopes. In this study, consecutive tillage by hoeing was performed 5 and 15 times on an Orthic Regosol within a steep hillslope landscape of the Sichuan Basin, China, to simulate the impact of short- and long-term tillage on soil profile properties at different slope positions. After intense tillage, significant changes in Cs-137 inventories of the soil occurred in the summit and toeslope positions. The soil profile (originally

A novel polyvinylpyrrolidone (PVP)-directed crystallization route is successfully developed for the shape-selective synthesis of ZnO particles with distinctive shapes, including monolayer, bilayer, and multilayer structures, gears, capped pots, hemispheres, and bowls, at temperatures as low as 32 °C. This route is based on exploiting a new water/PVP/n-pentanol system. In the system, PVP can greatly promote ZnO nucleation by binding water and direct ZnO growth by selectively capping the specific ZnO facets, which is confirmed by IR absorption spectra. The bandgap of the ZnO particles is readily tuned by modifying the product morphology by adjusting the PVP chain length, PVP amount, water volume, and reaction temperature. The remarkable ZnO structures and the biomimetic method demonstrated here not only expand the structures and applications of ZnO but also provide a new approach to explore the unusual structures for novel physicochemical properties and technological applications. Furthermore, the novel ZnO/Au/ZnO sandwich structure is successfully fabricated by inserting a Au plate into the bilayer ZnO structure.

The variation in soil nutrients is crucial to the understanding of productivity of soil undergoing erosion overall, as the latter can result in a decline in soil quality and crop production in the whole landscape. Two toposequences (a long slope and terraced field series) were selected from hilly areas of the Sichuan Basin, China, to determine the effects of soil redistribution rates and topographic changes on P, K and CaCO3 contents, and examine the contribution of water and tillage erosion to the variation and distribution pattern in these chemical properties within different landscapes. For the long slope, soil loss occurred at upper slope positions and soil accumulation was present at lower slope positions. However, terrace banks create a line of zero downslope transport of soil, and lead to abrupt changes in Cs-137 inventories over very short distances between the upper (or lower) part of the terrace and the lower (or upper) part of the neighbouring terrace. Extractable K concentrations are significantly related to Cs-137 inventories on both the long slope and terraced fields, which suggests that the distribution of extractable K is closely linked to soil redistribution. However, it is noticeable that no close relationship between extractable P concentrations and Cs-137 inventories was found on the terraced fields, while there was a highly significant correlation between the two variables on the long slope. The variation in extractable P by soil redistribution was enhanced on the long slope, but was concealed on the terraced fields due to the presence of CaCO3. It is suggested that the variation in extractable P not only depends on soil redistribution in relation to fine soil particles, but is also influenced by other factors such as P-fixation onto CaCO3, the concentration of which itself is linked to soil erosion and redistribution. Therefore, extractable P dynamics with reference to soil erosion are relatively complex on carbonate-rich soil and parent materials in areas such as those represented by the Sichuan Basin. Tillage erosion, the dominant soil redistribution process on terraced fields, was found to be a major contributor to the variation in soil chemical properties in the terraced field landscape, while water erosion plays an important role in the variation in soil chemical properties in the long slope landscape. In the case of carbonate-rich soils or parent materials, however, tillage erosion did not create accumulations of extractable P in depressions, whereas water erosion results in extractable P losses at upper slope positions and accumulation at lower slope positions.

The attachment of water molecules to poly(vinylpyrrolidone) (PVP) is used in conjunction with the region-selective distribution of PVP and water in a water/PVP/n-pentanol system to confine reactions along the surface of PVP, thus achieving the highly shape-selective synthesis of anisotropic Au nanostructures with controlled sizes and remarkable shapes such as regular octahedrons, triangles, rods, dumbbells, belts, and hexagons. The IR absorption spectra of the Au nanoparticles confirm that the nanoparticles are formed around PVP, and corroborate the adsorption of PVP on Au. The size, shape, and plasmon resonance of the Au nanoparticles can be readily tuned by modifying the adsorption behavior and/or the reducing ability of PVP by adjusting the relative amounts of PVP and water, directly adding gold seeds, or changing the stirring conditions in the reaction mixture. The obtained highly pure anisotropic Au nanostructures and the synthesis method demonstrated here enable us to study distinct nanostructures to search for novel physicochemical properties and technological applications. Our method is also successfully extended to prepare highly pure silica spheres, tubes, and needles with controlled aspect ratios.

A novel water/polyvinylpyrrolidone (PVP)/n-pentanol ternary system is successfully developed to realize the controlled growth and assembly of silver nanoprisms using a one-step synthesis for the first time. The highly shape-selective growth and assembly of nanoprisms is based on the unique water/PVP/n-pentanol interface. It is seen that the cooperative assembly of nanoprisms with PVP greatly affects the size-dependent nanoprism plasmon bands. The plasmon bands of the assemblies are closer to those of bulk silver than to those of nanoprisms. The method is simple and versatile, and is successfully extended to prepare Au and Pd nanoprisms, lamellar ZnO particles, and layered ZnO assemblies with high purity. The method may provide powerful technology for shape-selective synthesis and assembly of lamellar nanoparticles with novel structures and functions in nanotechnology.

High frequency seasonal drought in purple soils (Regosols in FAO taxonomy) of the hilly upland areas of Sichuan basin, China. is one of the key restrictive factors for crop production. In order to manage irrigation and fertilizer application in these soils effectively. the soil water content in a sloped plot with 60 cm soil depth was measured by neutron probe devices to investigate the soil moisture regime during the 1998 rainy season after various amounts of rainfall events. The results showed that variation of soil moisture along the slope positions was highest in the top soil layer during the period of sporadic rainfall that did not induce any runoff. The coefficients of variation of soil moisture at various slope positions (upper, middle, and lower) are 17-36%. 8.95% 10.25%. 8.58% 8.05% and 9.21% at the 10 cm, 20 cm, 30 cm, 40 cm, 50 cm and 60 cm soil depths respectively. When surface runoff occurred, the soil moisture dynamics at various positions on the plot were then very different. Soil water content decreased more rapidly on the upper slope than on the middle and lower slope positions. When both surface runoff and throughflow occurred, the soil moisture dynamics in the various layers showed a stable period (soil water content is near constant as time elapses) that lasted about I week. Also, the pattern of moisture dynamics is 'decreasing-stabilization-decreasing'. Thus, irrigation and fertilization management according to the spatial and temporal features of soil moisture dynamics on sloped land can increase the water and fertilizer utilization efficacy by reducing their losses during the stable period. Copyright (c) 2006 John Wiley & Sons, Ltd.

The ZnO-based diluted magnetic semiconductor materials have been widely investigated since the room temperature ferromagnetism (FM) was predicted in the p -type Mn doped ZnO. However, it is now clear that magnetic dopants or impurities are not necessary for introducing FM into ZnO. As confirmed by numerous theoretical and experimental works, tunable FM can be effectively introduced into ZnO nanoparticles (NPs) by controlling the surface and/or interface nanostructures. This review describes the recent advances in the surface and/or interface FM of ZnO NPs without any magnetic impurities. On the basis of the previous reports including our recent works, the origin of FM of ZnO NPs has been overviewed and discussed in terms of defects, complex reactions or compounds, and electron transfer at the NP surface or interface.

Soil organic carbon (SOC) displaced by soil erosion is the subject of much current research and the fundamental question, whether accelerated soil erosion is a source or sink of atmospheric CO2, remains unresolved. A toposequence of terraced fields as well as a long slope was selected from hilly areas of the Sichuan Basin, China to determine effects of soil redistribution rates and processes on SOC stocks and dynamics. Soil samples for the determination of caesium-137 (Cs-137), SOC, total N and soil particle size fractions were collected at 5 m intervals along a transect down the two toposequences. Cs-137 data showed that along the long slope transect soil erosion occurred in upper and middle slope positions and soil deposition appeared in the lower part of the slope. Along the terraced transect, soil was lost over the upper parts of the slopes and deposition occurred towards the downslope boundary on each terrace, resulting in very abrupt changes in soil redistribution over short distances either side of terrace boundaries that run parallel with the contour on the steep slopes. These data reflect a difference in erosion process; along the long slope transect, water erosion is the dominant process, while in the terraced landscape soil distribution is mainly the result of tillage erosion. SOC inventories (mass per unit area) show a similar pattern to the Cs-137 inventory, with relatively low SOC content in the erosional sites and high SOC content in depositional areas. However, in the terraced field landscape C/N ratios were highest in the depositional areas, while along the long slope transect, C/N ratios were highest in the erosional areas. When the samples are subdivided based on Cs-137-derived erosion and deposition data, it is found that the erosional areas have similar C/N ratios for both toposequences, while the C/N ratios in depositional areas are significantly different from each other. These differences are attributed to the difference in soil erosion processes; tillage erosion is mainly responsible for high-SOC inventories at depositional positions on terraced fields, whereas water erosion plays a primary role in SOC storage at depositional positions on the long slope. These data support the theory that water erosion may cause a loss of SOC due to selective removal of the most labile fraction of SOC, while on the other hand tillage erosion only transports the soil over short distances with less effect on the total SOC stock.

Some studies on the relationship between soil erosion and subsequent redeposition of eroded soils in the same field and soil quality have been conducted in croplands, yet few studies have revealed this relationship in rangelands. We selected a toposequence with a slope of 30% and a horizontal length of 342 m from the rangeland in the northern Tibet Autonomous Region, China (31 degrees 16'N, 92 degrees 09'E) to determine the relationship between soil erosion, soil organic carbon (SOC) content and available P patterns within a hillslope landscape. Soil samples for the determination of Cs-137 as well as SOC, available P and particle-size fractions were collected at 20 m intervals along a transect of this hillslope. Soil redistribution was caused primarily by wind erosion at toe-slope positions, but primarily by water erosion at the hillslope positions above the toe-slope. In upper- and mid-slope portions (0 m to 244 m horizontal length), SOC content is closely correlated to Cs-137 concentration (r = 0.74, P < 0.01, n= 15), suggesting that SOC distribution along the slope was similar to Cs-137 distribution, which itself was dependent on topographic changes. However, SOC contents in toe-slope portions are less than those above the toe-slope (i.e. upper- and mid-slope portions), and the correlation between Cs-137 and SOC in the toe-slope portion is weaker than that above the toe-slope. A highly significant correlation (r = 0.72, P < 0.001, n= 20) between Cs-137 concentration and available P was found within the whole hillslope landscape, implying the distribution pattern of available P was somewhat different from that of SOC. We suggest that the distribution of SOC within the hillslope landscape is also affected by factors such as assimilation rates due to difference in grassland productivity at different points and different biological oxidation rates of carbon related to patterns of moisture distribution.

Rare-earth acetates were used to catalyze the copolymerization reaction of carbon monoxide and styrene. Cupric acetate, 1,10-phenanthroline, p-toluenesulfonic acid, and 1,4-benzoquinone were also added to the catalyst system. The structures of the copolymers obtained were characterized with IR, 1H NMR, 13C NMR, wide-angle X-ray diffraction, and elemental analysis methods. The relationship between the catalytic activity and the catalyst composition was studied in detail. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 642–649, 2002; DOI 10.1002/pola.10147

In this article we propose a theoretical framework of distributed representations and a methodology of representational analysis for the study of distributed cognitive tasks—tasks that require the processing of information distributed across the internal mind and the external environment. The basic principle of distributed representations Is that the representational system of a distributed cognitive task is a set of internal and external representations, which together represent the abstract structure of the task. The basic strategy of representational analysis is to decompose the representation of a hierarchical task into its component levels so that the representational properties at each level can be independently examined. The theoretical framework and the methodology are used to analyze the hierarchical structure of the Tower of Hanoi problem. Based on this analysis, four experiments are designed to examine the representational properties of the Tower of Hanoi. Finally, the nature of external representations is discussed.

The title phosphor is synthesized by solid state reaction of CaS, La2S3, Ga2S3, and Ce2S3 (Ar, 950 °C, 2 h) and characterized by powder XRD, SEM, and photoluminescence spectroscopy.

In arid and semiarid areas, soil water deficit is a major constraint to vegetation establishment (Zhang 1992). While climatic conditions can be a constraint to soil water supply, other factors can be extremely important in determining forest survival. One of the key factors leading to tree death is livestock grazing in the early growth stage of forest establishment (Li 1995). Braunack & Walker (1985) found that after 16 years without grazing, the surface soil properties of a semiarid woodland still showed evidence of prior damage by grazing sheep. Infiltration rates can still increase many years after grazing has ceased (Gifford & Hawkins 1978).Greenwood et al. (1998) reported that there were significant increases in unsaturated hydraulic conductivity in the ungrazed treatments compared with the grazed controls after 2.5 years without livestock. The purpose of this study was to quantify the changes in soil water properties in a recently established forest as affected by grazing in a semiarid climate.