Lateral Transportation Research Articles

Dissolved organic nitrogen fluxes and crop yield after long-term crop straw incorporation

The transportation of dissolved organic nitrogen (DON) from croplands to aquatic ecosystems potentially negatively influences water quality. Sustaining crop yields while decreasing the environmental impacts of the DON from nitrogen fertilizer application is a key challenge in sustainable agriculture. However, few field datasets have measured the lateral transportation of DON via hydrological routes under different nitrogen fertilizer applications, particularly in sloping croplands. Using lysimeter plots (8 × 4 m2), we measured DON loss via overland flow, interflow, and soil erosion under different fertilizer applications under a long-term field experiment. There were four treatments, including no fertilizer (CK), mineral fertilizer (NPK), mineral fertilizer combined with swine manure (MNPK), and mineral fertilizer combined with crop straw (CNPK). In comparison to the NPK treatment, the annual DON loss fluxes via overland flow, interflow, and soil erosion for the MNPK treatment were significantly (P < 0.05) increased by 68.8, 100.6, and 63.7%, respectively. Conversely, this was significantly decreased by 182.6, − 14.1, and 49.4%, respectively, under the CNPK treatment. Correspondingly, the yield-scaled total DON losses for the MNPK and CNPK treatments were significantly increased by 78.8 and − 18.2% compared to the NPK treatment (0.33 ± 0.04 kg N t−1 grain). Therefore, long-term continuous manure application is associated with an increased risk of DON environmental pollution. Alternatively, the incorporation of crop straw can be recommended as a means of decreasing DON pollution while maintaining crop yield.

Development of a model to simulate soil heavy metals lateral migration quantity based on SWAT in Huanjiang watershed, China.

Lateral transportation of soil heavy metals in rainfall events could significantly increase the scope of pollution. Therefore, it is necessary to develop a model with high accuracy to simulate the migration quantity of heavy metals. A model for heavy metal migration simulation was developed based on the SWAT (Soil and Water Assessment Tool) model. This model took into consideration the influence of soil pH value, soil particle size, runoff volume, sediment amount, concentration of water-soluble heavy metals dissolved in runoff and insoluble absorbed to the soil particles. This model was reasonable in Huanjiang watershed, Guangxi Zhuang Autonomous Region, south China, covering an area of 273 km2. The optimal drainage area threshold was determined by analyzing the effects of watershed subdivision on the simulation results to ensure the simulation accuracy. The main conclusions of this paper were: (1) watershed subdivision could affect simulation migration quantity of heavy metals; (2) the quantity of heavy metals transported by sediment accounted for 97%-99% of the total migration quantity in the study watershed. Therefore, sediment played the most important role in heavy metal migration; (3) the optimal drainage area threshold percentage to ensure high simulation accuracy was determined to be 2.01% of the total watershed; (4) with the optimal threshold percentage, this model could simulate the migration quantity of As, Pb and Cd accurately at the total watershed and sub-watershed level. The results of this paper were useful for identifying the key regions with heavy metal migration.

Electrical-sedimentary anisotropy of landforms adjacent to postglacial faults in Lapland

Postglacial faults (PGFs) are common SW-NE-trending features in the northern part of the Fennoscandian shield being attributed to former high-magnitude (Mw ≈ 7–8.2) earthquakes (Arvidsson, 1996). These are of interest for the long-term seismic hazard of deep geological nuclear waste repositories. The PGFs are still seismically active; and many of the deformation features, such as paleolandslides, are spatially coextensive within these earthquake zones. Based on the 14C-datings of landslide-buried organic materials, three postglacial seismic episodes (≈9.7–11, ≈5–6, and 1.3–1.8 ky ago) have been found in western Finnish Lapland. Because the model predictions by Wu et al. (1999) suggested that the onset of fault instability started at 15 ky and that the maximum fault instability was reached at 13–10 ky in Fennoscandia, we postulate that not only subaerial but also subglacial types of deformations may have been associated with the past seismic events. Here, we present LiDAR DEM observations and sediment electromagnetic anisotropy data on the landforms, such as the rim-ridged/arcuate Pulju moraine (Kujansuu, 1967), roundish (liquefaction) bowls, postdepositional (liquefaction) deformations on streamlined landforms, as well as hummocky ridge fields of massflow sediments. The sediments in the Pulju moraine and massflow ridges displayed clear anisotropy, indicating lateral transportation in subglacial wet-based environment. Instead, sediments in the bowl-shaped morphologies next to PGFs and deformed ice-stream flutings tended to be isotropic, suggesting postdepositional and vertical liquefaction processes. Based on the LiDAR morphology and sedimentary anisotropy data, these landforms may be linked to past earthquakes.

Microscopic observation of lateral and vertical charge transportation in Si nanocrystals sandwiched by amorphous SiC layers

Charge injection and transportation process is a fundamental problem to Si nanocrystals (Si-ncs) based electric and photonic devices. In the manuscript, a single layer of Si-ncs sandwiched by amorphous Si carbide (a-SiC) was prepared by excimer laser annealing of a-SiC/a-Si/a-SiC multilayers, and the charging effect was then characterized by Kelvin probe force microscopy (KPFM) on the microscopic scale. Opposite charges were injected into Si-ncs through the biased tip and formed a core-ring or up-down shaped distribution. The decay characteristics showed that these opposite charges would not only vertically tunnel through the bottom a-SiC layer to substrate but also laterally transport and recombine with each other driven by the attractive Coulomb force. Besides, the charge retention time was also found dependent on the injection biases, which is tentatively ascribed to the charge trapping by the Si-ncs/a-SiC interface states under high bias scanning. The analysis was further supported by conductive atomic force microscopy (CAFM) measurement, in which the current-voltage curves gradually shifted during the repetition test, probably because of bias screening by the trapped charges at these interface states.

Sediment accumulation owing to backwater effect in the lower reach of the Stung Sen River, Cambodia

We examined channel bars at two sites in the lower reach of the Stung Sen River, which flows into Lake Tonle Sap, Cambodia, to identify sediment transport and accumulation processes during monsoon-related flood events and to investigate how sediment transport capacity changes as a result of enhanced backwater effect of the lake. Channel bars in the lower reach of the Stung Sen River that emerge in the dry season were classified into type A (lateral bars), type B (point bars), type C (concave-bank benches) and type D (diagonal and island bars, or fluvial dunes) based on Nagumo et al.'s previous study. Type B, type C, and type D channel bars were at our study sites of SEN-01 and SEN-02, about 83 and 77km from the river mouth respectively. Computation of water surface profiles showed that sediment transport capacity of the Stung Sen River decreased abruptly after the peak flow stage because of the backwater effect from Lake Tonle Sap during the decreasing flow stage. Our observations suggest that alternating layers of sand and silt to clay layers accumulate to form type C channel bars, corresponding to changes in sediment transport capacity controlled by backwater effects from Lake Tonle Sap and by changes in flow depths and associated slackwater systems. The accumulation of alternating silt and sand layers of type B channel bars results from lateral sediment transportation that is accelerated with an increase of secondary flow, whereas development of type D channel bars is related to bedload mobility.

Mechanical Preparation Showed Superior Shaping Ability than Manual Technique in Primary Molars - A Micro-Computed Tomography Study.

Manual instrumentation is still reported as the main choice in the primary teeth preparation; however, studies have shown limitations in its use. The morphological characteristics of primary teeth and the limited knowledge of shaping procedures in these teeth using mechanical preparation become a challenge for clinical practice and might impair the predictability of endodontic treatment.

Studies on the polycrystalline silicon/SiO2 stack as front surface field for IBC solar cells by two-dimensional simulations**Project supported by the National Natural Science Foundation of China (Grant Nos. 11104319, 11274346, 51202285, 61234005, 51172268, 51602340, 61274059, and 51402347), the Solar Energy Action Plan of Chinese Academy of Sciences (Grant Nos. Y1YT064001, Y1YF034001, and Y2YF014001), the Graduate and College Student’s Innovative Project

Interdigitated back contact (IBC) solar cells can achieve a very high efficiency due to its less optical losses. But IBC solar cells demand for high quality passivation of the front surface. In this paper, a polycrystalline silicon/SiO2 stack structure as front surface field to passivate the front surface of IBC solar cells is proposed. The passivation quality of this structure is investigated by two dimensional simulations. Polycrystalline silicon layer and SiO2 layer are optimized to get the best passivation quality of the IBC solar cell. Simulation results indicate that the doping level of polycrystalline silicon should be high enough to allow a very thin polycrystalline silicon layer to ensure an effective passivation and small optical losses at the same time. The thickness of SiO2 should be neither too thin nor too thick, and the optimal thickness is 1.2 nm. Furthermore, the lateral transport properties of electrons are investigated, and the simulation results indicate that a high doping level and conductivity of polycrystalline silicon can improve the lateral transportation of electrons and then the cell performance.

New evidence for Kuroshio inflow and deepwater circulation in the Okinawa Trough, East China Sea: Sedimentary mercury variations over the last 20 kyr

AbstractThe evolution of the Kuroshio Current (KC) in the Okinawa Trough (OT) has long been of paleoceanographic interest and has been the focus of many investigations because of its large impacts on both the ocean environment and the climate in East Asia. Here we present a new high‐resolution mercury (Hg) record from the OT sediments that provides robust evidence for the glacial‐interglacial variabilities of KC inflow. The Hg levels are anomalously high in the Holocene deposits, which feature a large and abrupt Hg increase at ~9.6 ka and a significant drop at 4.5–3.2 ka. Our observations show that most Hg was derived from seafloor hydrothermal plumes via active lateral transportation. Thus, the generally high Hg levels since ~9.6 ka are associated with enhanced basin‐wide deepwater circulation triggered by the KC inflow. This driving mechanism for the deposition and widespread of Hg is also evidenced by an abrupt drop in Hg levels during the late Holocene neoglacial cold period (~5–3 ka) when the KC inflow was temporarily interrupted and deepwater circulation was consequently weak or even absent in the OT. The changes in sedimentary Hg appear to be synchronous with those in other geochemical proxies that suggest that bottom water conditions switched from anoxic to oxic due to increased upwelling from the bottom in tandem with the strengthening KC and reduced freshwater effect since ~9.6 ka. This study shows that the hydrothermal Hg is a sensitive and independent tool for the reconstruction of paleodynamics of KC in the OT.

Soil-like bodies on Mars

Soils sensu stricto are absent on Mars; most probably, they have never been formed there, because, up to now, we have no evidence of the presence of life, either relict or recent, on this planet. Numerous references to “Martian soils” in scientific literature concern loose substrates rather than Dokuchaev’s soils. In this context, surface bodies on Mars can be described using the concept of planetary shells, or exons. Exons can be subdivided into sitons formed via in situ transformation of parent material, transons formed in the course of lateral transportation and deposition of substances, and transsitons formed by the combination of both in situ and lateral processes. Among Martian exons, transons predominate. They represent loose sediments of mainly eolian genesis related to extremely strong winds. Soil-like bodies (soloids) on Mars are represented by sitons and transsitons. These are abiotic formations having the profiles differentiated by the contents of iron oxides, soluble salts, and clay minerals and mainly formed in the presence of liquid water during the paleohumid eras of Mars evolution more than 2.5/3 billion years ago. True deep sitons (Martian weathering mantles) could only be formed under the impact of long-term weathering on stable surfaces during humid eras. Then, they were either buried by later deposited sediments, or eroded. Up to now, such objects have not been discovered on Mars.

Transport of trace metals (Mn, Fe, Ni, Zn and Cd) in the western Arctic Ocean (Chukchi Sea and Canada Basin) in late summer 2012

Distributions of trace metals (Mn, Fe, Ni, Zn and Cd) in the western Arctic Ocean (Chukchi Sea and Canada Basin) in September 2012 were investigated to elucidate the mechanisms behind the transport of these metals from the Chukchi Shelf to the Canada Basin. Filtered (<0.22µm) and unfiltered seawater samples were analyzed to determine dissolved (D) and total dissolvable (TD) trace metal concentrations, respectively. We identified maxima in vertical profiles for the concentrations of D-Fe and TD-Fe, as well as for the other four analyzed trace metals, which occurred in the halocline and/or near-bottom waters. Concentration profiles of all trace metals except for Cd also tended to show peaks near the surface, which suggest that the inflow of low-salinity Pacific-origin water from the Bering Strait, as well as local fresh water inputs such as river water and melting sea-ice, influenced trace metal concentrations. The distribution patterns and concentration ranges were generally similar between the D and TD fractions for Ni, Zn and Cd, which indicate that Ni, Zn and Cd were present mainly in their dissolved forms, whereas the concentrations of TD-Fe and TD-Mn were generally higher than those of D-Fe and D-Mn, respectively. These results are consistent with the results of previous studies of this region. For both Fe and Mn, labile particulate (LP) concentrations (the difference between the TD and D fractions, which is acid-leachable fraction in the particles during storage at pH 1.5–1.6) were highest in the near-bottom waters of the Chukchi Shelf region. The relationships between the distance from the shelf break and the concentrations of trace metals revealed that Fe and Mn concentrations in halocline waters tended to decrease logarithmically with distance, whereas changes in the concentrations of Ni, Zn, Cd and phosphate with distance were small. These results suggest that the distributions of Fe and Mn were controlled mainly by input from shelf sediment and removal through scavenging processes. Based on the phase distributions of Fe and Mn, which were calculated as ratios between the LP and D fractions, different behaviors between Fe and Mn were expressed during lateral transportation. The concentration of TD-Fe declined rapidly via removal of LP-Fe from the water column, whereas the concentration of TD-Mn declined more slowly through the transformation of D-Mn into LP-Mn. In contrast, the concentrations of D-Cd, D-Zn and D-Ni were more strongly correlated with phosphate levels, which suggest that, like phosphate, the distributions of Cd, Zn and Ni were generally controlled by the internal biogeochemical cycles of the ocean interior. Based on the findings of studies that have previously evaluated the concentration maxima of Ni, Zn and Cd within the halocline layer in the Canada Basin near the Canadian Arctic Archipelago, the elevated Ni, Zn and Cd concentrations in the halocline layer may extend across the Canada Basin from the Chukchi Sea shelf-break area. The determination coefficients for correlations with phosphate concentration varied between the concentrations of Ni, Zn and Cd, which suggest that the sources of these trace metals, such as sediments and sea-ice melting, affected their patterns of distributions differently. Our findings reveal the importance and impact of the halocline layer for the transport of trace metals in the western Arctic Ocean during the late summer. The existence of rich and various sources likely sustained the high concentrations of trace metals and their unique profiles in this region.

Marine Carbon-Sulfur Biogeochemical Cycles during the Steptoean Positive Carbon Isotope Excursion (SPICE) in the Jiangnan Basin, South China

Global occurrences of Steptoean Positive Carbon Isotope Excursion (SPICE) during Late Cambrian recorded a significant perturbation in marine carbon cycle, and might have had profound impacts on the biological evolution. In previous studies, SPICE has been reported from the Jiangnan slope belt in South China. To evaluate the bathymetric extent of SPICE, we investigate the limestone samples from the upper Qingxi Formation in the Shaijiang Section in the Jiangnan Basin. Our results show the positive excursions for both carbonate carbon (δ13C) and organic carbon (δ13Corg) isotopes, as well as the concurrent positive shifts in sulfur isotopes of carbonate associated sulfate (CAS, δ34SCAS) and pyrite (δ34Spyrite), unequivocally indicating the presence of SPICE in the Jiangnan Basin. A 4‰ increase in δ13Ccarb of the Qingxi limestone implies the increase of the relative flux of organic carbon burial by a factor of two. Concurrent positive excursions in δ34SCAS and δ34Spyrite have been attributed to the enhanced pyrite burial in oceans with extremely low concentration and spatially heterogeneous isotopic composition of seawater sulfate. Here, we propose that the seawater sulfur isotopic heterogeneity can be generated by volatile organic sulfur compound (VOSC, such as methanethiol and dimethyl sulfide) formation in sulfidic continental margins that were widespread during SPICE. Emission of 32S-enriched VOSC in atmosphere, followed by lateral transportation and aerobic oxidation in atmosphere, and precipitation in open oceans result in a net flux of 32S from continental margins to open oceans, elevating δ34S of seawater sulfate in continental margins. A simple box model indicates that about 35% to 75% of seawater sulfate in continental margins needs to be transported to open oceans via VOSC formation.

Analysis Research on the Lateral Replenishment Strategy of the Chain Supermarket Fresh Agricultural Products

The purpose of this research is to minimize the total cost of the overall system in the process of replenishment, to maximize the overall system profits. This paper regards all affiliated stores of chain supermarket as a system to do some research about the replenishment of fresh agricultural products. Then, this paper proposes the lateral replenishment strategy, analyzes its advantages, and applies the strategy thinking to the solution of the surplus or shortage of fresh agricultural products. Through the establishment of the inventory cost model, we compare the system inventory total cost between taking the lateral replenishment and deployment strategy and not using the lateral replenishment and deployment strategy, and get that there is lower total cost. Through the establishment of lateral replenishment transportation model, the optimal dispatching scheme between the surplus supermarket and the shortages supermarket is given. And then, the sensitivity analysis presents the variable range of the fresh agricultural products increment and decrement that does not affect this optimal dispatching scheme. This paper can provide a reference for the chain supermarket to deal with the shortage or surplus of fresh agricultural products so as to improve sales margins of agricultural products, to reduce the total inventory costs of the whole the chain supermarket system, and to improve the customer service levels.

Amino-Terminus of Oleosin Protein Defines the Size of Oil Bodies - Topological Model of Oleosin-Oil Body Complex

Lipids formed in seeds of oilseed plant are stored in specific cytosolic structures called oil bodies, which are covered with oleosin proteins. Disruption of oleosin layer by heat treatment makes lipids susceptible to oxidation. By analyzing the amino acid sequence of Arabidopsis oleosin, unique domains were identified within the aminoterminus of the protein. Removal of these domains affected both the size of oil bodies and their susceptibility to lipid-specific stain, Nile Blue A. Amino-terminally truncated oleosin mutant, which was in fusion to green fluorescent protein (GFP), confined to rough endoplasmic reticulum (rER) suggesting that the amino-terminus of oleosin is required for the efficient lateral transportation of oleosin proteins from rER to oil bodies. The size of oil bodies covered by amino-terminal mutants was at least 5 times larger than native oil bodies. Based on the observations, a topological model was generated, which could explain how oleosin maintains and protects the integrity of oil bodies during seed storage.

Effect of soil erosion on dissolved organic carbon redistribution in subtropical red soil under rainfall simulation

Water erosion governs soil carbon reserves and distribution across the watershed or ecosystem. The dynamics of dissolved organic carbon (DOC) under water erosion in red agricultural soil is not clear. To determine the effect of tillage management and water erosion on vertical and lateral transportation of soil organic carbon (SOC) and DOC production under distinct rainfall intensities in the hilly red soil region of southern China, a chisel tillage plot with low rainfall intensity (CT-L) and two no-tillage plots with high (NT-H) and low rainfall intensity (NT-L) studies were conducted. Soil samples were collected from 0–5, 5–10, 10–20, and 20–40cm soil layers from triplicate soil blocks pre- and post-rainfall for determining concentration of SOC and DOC. Runoff samples were collected at every 6min for determining concentration of DOC and sediments during rainfall simulations on runoff plots (2m×5m) with various intensities. No fertilizer was applied in any plots. Results clearly show that runoff volumes, sediments and SOC entrained with sediment, and laterally mobilized DOC were significantly larger on NT-H compared to other plots, coinciding with changes in rainfall intensity; and the extent of roughness of the plot surface (CT vs. NT) was the variation in runoff DOC concentration. During the simulated rainfall events, DOC exports average 0.76, 0.64, and 0.27gCm−2h−1; SOC exports average 3.52, 1.08, and 0.07gm−2h−1 in the NT-H, NT-L, and CT-L soils, respectively. The maximum export of DOC was obtained under a high intensity rainfall plot, which lagged behind maximum runoff volumes, sediments, and SOC losses with sediment. Export of DOC was proportional to SOC content of soil loss. The least DOC losses in surface runoff and SOC losses with sediment were observed in CT-L plots. Vertical DOC mobilization achieved its maximum with low intensity rainfall under CT treatment. The DOC did not accumulate at the soil surface and was distributed mainly in the second and third soil horizons. The distribution of DOC content down the soil profile increased compared to pre-rainfall, except for subplots E at NT-H and NT-L. Results indicate that rainfall significantly increased DOC content in experimental plots. The SOC content of sediment leaving the erosion zone was significantly correlated with overland flow volume and soil loss. These observations lead to the conclusion that soil erosion is an important factor controlling the export of dissolved organic carbon.

Ocean colour remote sensing in the southern Laptev Sea: evaluation and applications

Abstract. Enhanced permafrost warming and increased Arctic river discharges have heightened concern about the input of terrigenous matter into Arctic coastal waters. We used optical operational satellite data from the ocean colour sensor MERIS (Medium-Resolution Imaging Spectrometer) aboard the ENVISAT satellite mission for synoptic monitoring of the pathways of terrigenous matter on the shallow Laptev Sea shelf. Despite the high cloud coverage in summer that is inherent to this Arctic region, time series from MERIS satellite data from 2006 on to 2011 could be acquired and were processed using the Case-2 Regional Processor (C2R) for optically complex surface waters installed in the open-source software ESA BEAM-VISAT. Since optical remote sensing using ocean colour satellite data has seen little application in Siberian Arctic coastal and shelf waters, we assess the applicability of the calculated MERIS C2R parameters with surface water sampling data from the Russian–German ship expeditions LENA2008, LENA2010 and TRANSDRIFT-XVII taking place in August 2008 and August and September 2010 in the southern Laptev Sea. The shallow Siberian shelf waters are optically not comparable to the deeper, more transparent waters of the Arctic Ocean. The inner-shelf waters are characterized by low transparencies, due to turbid river water input, terrestrial input by coastal erosion, resuspension events and, therefore, high background concentrations of suspended particulate matter and coloured dissolved organic matter. We compared the field-based measurements with the satellite data that are closest in time. The match-up analyses related to LENA2008 and LENA2010 expedition data show the technical limits of matching in optically highly heterogeneous and dynamic shallow inner-shelf waters. The match-up analyses using the data from the marine TRANSDRIFT expedition were constrained by several days' difference between a match-up pair of satellite-derived and in situ parameters but are also based on the more stable hydrodynamic conditions of the deeper inner- and the outer-shelf waters. The relationship of satellite-derived turbidity-related parameters versus in situ suspended matter from TRANSDRIFT data shows that the backscattering coefficient C2R_bb_spm can be used to derive a Laptev-Sea-adapted SPM algorithm. Satellite-derived Chl a estimates are highly overestimated by a minimum factor of 10 if applied to the inner-shelf region due to elevated concentrations of terrestrial organic matter. To evaluate the applicability of ocean colour remote sensing, we include the visual analysis of lateral hydrographical features. The mapped turbidity-related MERIS C2R parameters show that the Laptev Sea is dominated by resuspension above submarine shallow banks and by frontal instabilities such as frontal meanders with amplitudes up to 30 km and eddies and filaments with horizontal scales up to 100 km that prevail throughout the sea-ice-free season. The widespread turbidity above submarine shallow banks indicates inner-shelf vertical mixing that seems frequently to reach down to submarine depths of a minimum of 10 m. The resuspension events and the frontal meanders, filaments and eddies indicate enhanced vertical mixing being widespread on the inner shelf. It is a new finding for the Laptev Sea that numerous frontal instabilities are made visible, and how highly time-dependent and turbulent the Laptev Sea shelf is. The meanders, filaments and eddies revealed by the ocean colour parameters indicate the lateral transportation pathways of terrestrial and living biological material in surface waters.

Microdroplet Manipulation at Ultra-Low Voltages on Conjugated Polymer Using Electrochemical Tunable Wetting

Manipulation of microdroplets has broad applications in microfluidic systems, lab-on-a-chip technologies, biotechnologies, and sensor devices. While the electrowetting on dielectric (EWOD) technique has been successfully used for the manipulation of microdroplets among other technologies, the actuation voltages of 12-80 V of EWOD-based techniques result in less portable power sources and potential interference with biological applications. Therefore, an alternative technique to achieve low-voltage manipulation of liquid droplets is highly desirable.This study demonstrated a manipulation of organic microdroplets at 0.9 V by utilizing the electrochemical tunable wetting and adhesion properties of the dodecylbenzenesulfonate doped polypyrrole (PPy(DBS)) surface. The PPy(DBS) switched between an oxidized and a reduced state upon application of low voltages. The PPy(DBS) surface reduced at -0.9 V is more oleophobic and less adhesive to an organic droplet than the PPy(DBS) oxidized at 0.6 V. We first demonstrated a lateral transportation of a dichloromethane (DCM) microdroplet from one PPy(DBS) electrode to another in 0.1 M NaNO3 solution at 0.9 V. The PPy(DBS) electrodes were fabricated using an electropolymerization method on Au/Cr patterned silicon dioxide substrates. The PPy(DBS) electrodes were oxidized first by applying a voltage of 0.6 V. When a voltage of -0.9 V was applied to reduce a PPy(DBS) electrode, a wettability gradient was induced between activated and inactivated electrodes. Consequently, a DCM droplet placed across the boundary of these two electrodes moved from the reduced electrode, which was more oleophobic, to the inactivated electrode. We also demonstrated a vertical capture-release of a DCM microdroplet at 0.9 V by utilizing the tunable adhesion of PPy(DBS) surface. To achieve a transition from super sticky to super slippery surface, a microstructured PPy(DBS) surface was used to amplify the change in adhesion force during the reduction and oxidization of PPy(DBS) surface. The microstructured PPy(DBS) surface was fabricated through an electrodeposition process on micropatterned Au/Cr coated silicon substrate. The oxidized PPy(DBS) microstructure exhibited a super sticky surface while the reduced PPy(DBS) microstructure was super slippery to a DCM droplet. For the vertical capture-release of a DCM microdroplet, the PPy(DBS) microstructure was first oxidized at 0.6 V before being placed in contact with a DCM microdroplet. Due to a strong adhesion force, the microdroplet was immediately captured by the oxidized PPy(DBS) microstructure after contact. The microdroplet was then lifted away from the glass substrate with the PPy(DBS) microstructure for transportation. After the transportation, the DCM microdroplet was released from the PPy(DBS) microstructure at a potential of -0.9 V since the reduced PPy(DBS) microstructure behaved like a super slippery surface. Throughout this whole process, the DCM microdroplet remained fully intact and no residual liquid remained on the PPy(DBS) microstructure.In summary, this study successfully demonstrated an ultra-low-voltage manipulation of an organic droplet in both lateral and vertical directions by using the electrochemical tunable wetting of PPy(DBS) surfaces. This technique has promising applications in microfluidics, antifouling, and biotechnologies.

Effect of the Vertical Transportation Component of the TCO Layer on the Electrical Properties of Silicon Heterojunction Solar Cells

Silicon heterojunction (SHJ) solar cells that consist of thin amorphous silicon layers and crystalline silicon substrate are known as the high-efficiency class of solar cells. To collect the charge carriers, transparent conductive oxide (TCO) layers are inserted in which the charge carriers are being either vertically or both laterally and vertically transported. In this study, we have investigated the effect of the vertical transportation component of aluminum-doped zinc oxide (AZO) layers on the electrical properties of the fabricated SHJ solar cells and its contribution to the total series resistance of the obtained devices. In order to separate the vertical from the lateral transportation, we have employed an AZO/Ag/AZO multilayer structure, which only allows the vertical transportation of the charge carriers within the AZO layers. Our results show that with increase in O2 flow, the reduction rate of the FF is about three times higher when both lateral and vertical conductions take place, compared with when only vertical conduction occurs. Moreover in the latter case, a reduction of ~ 6% in the FF value per unit increase of vertical resistivity is obtained. Finally, we validate our procedure by comparing the obtained experimental results with the theoretically modeled values. The validation delivered a good agreement.

Rare earth element compositions of core sediments from the shelf of the South Sea, Korea: Their controls and origins

Rare earth elements (REEs) of bulk sediments and heavy mineral samples of core sediments from the South Sea shelf, Korea, were analyzed to determine the constraints on REE concentrations and distribution patterns as well as to investigate their potential applicability for discriminating sediment provenance. Bulk sediment REEs showed large variation in concentrations and distribution patterns primarily due to grain size and carbonate dilution effects, as well as due to an abundance of heavy minerals. In the fine sandy sediments (cores EZ02-15 and 19), in particular, heavy minerals (primarily monazite and titanite/sphene) largely influenced REE compositions. Upper continental crust-normalized REE patterns of these sand-dominated sediments are characterized by enriched light REEs (LREEs), because of inclusion of heavy minerals with very high concentrations in LREEs. Notably, such a strong LREE enrichment is also observed in Korean river sediments. So, a great care must be taken when using the REE concentrations and distribution patterns of sandy and coarse silty shelf sediments as a proxy for discriminating sediment provenance. In the fine-grained muddy sediments with low heavy mineral abundance, in contrast, REE fractionation ratios and their UCC-normalized patterns seem to be reliable proxies for assessing sediment provenance. The resultant sediment origin suggested a long lateral transportation of some fine-grained Chinese river sediments (probably the Changjiang River) to the South Sea of Korea across the shelf of the northern East China Sea.

Scale Growth on Austenitic Alloys under KCl Deposits at 500°C

The scale growth on two austenitic alloys, Alloy 310 and Sanicro 28, under KCl deposits was examined. This is relevant to the long term corrosion of superheater tubes in biofuel combustion. Coupons were encapsulated in tablets so that 1 mm of KCl with a relative density of 91% covered the metal. Samples were tested at 500°C in 5%O2-10%H2O-N2 for 24, 168 and 672 h. After exposure the salt was broken off and the scale was characterised by using SEM-EDX and AES. After 24 h a 50 nm thick oxide surrounded 500 nm thick chromates on the surface. No oxide layer was detected under the chromates and no Cl was found under either layer. The chromate growth requires lateral transportation of Cr along the surface. This reduces the protectiveness of the oxide and accelerates the formation of less protective Fe rich oxides. The formation of chromates also releases HCl inside the KCl tablet. The chromates did not grow significantly between 24 and 168 h, but the oxide grew equally thick beneath and between them and Cl was enriched around the metal oxide interface. After 672 h the oxides were about 5 μm thick and only few chromates were seen. Crystals of KCl formed in areas with thick porous and Fe rich oxides on both alloys.

Iron, manganese and aluminum in upper waters of the western South Pacific Ocean and its adjacent seas

Total dissolvable iron, manganese and aluminum distributions in upper waters were determined in the western South Pacific, Solomon Sea, Coral Sea, and Tasman Sea. In these oceanic regions, the surface aluminum distributions well reflect the atmospheric deposition pattern of mineral dust in the western South Pacific reported previously. Surface manganese distributions derive mainly from lateral transportation from the coastal sediments of western tropical islands. Compared to Mn and Al, the Fe distributions reflect the nutrient cycle in upper waters. Iron limitation over the vast South Pacific, as revealed by physiological features of phytoplankton, seems to be caused by low atmospheric dust deposition and low Fe:N ratios in deep waters. In the western South Pacific, with its unique geographic and oceanographic settings, the local sources of trace metals might considerably affect their biogeochemical cycles.