Wetland mapping in the Balqash Lake Basin Using Multi-source Remote Sensing Data and Topographic features Synergic Retrieval

AbstractWetland plays a major role in the hydrological cycle, the carbon sink (carbon sequestration), nitrogen absorption, geochemical cycle, water conservation, biological diversity. Traditional field surveys for mapping wetlands distribution in large areas are very difficult to undertake. Remote sensing techniques offer promising solutions to this problem. But spectral confusion with other land cover classes and different types of wetlands, it is difficult to extract wetland information automatically. The overarching goal of this study was to develop a hybrid method for lake wetlands automated delineation by integrated using multi-source remote sensing data and DEM data. Firstly, it is to do radiance correction and convert image DN value to reflectance or radiance. Secondly, spectral index calculation and topographic indices derive, such as NDVI, NDWI, TVDI, slope and others topographic feature indices and etc. Thirdly, water bodies extraction through the NDWI iterative computation. Finally, it is to retrieve marsh land from image via comprehensive information of soil moisture character, topographic factors and spatial analysis. By the above steps, we got the ultimate wetlands distribution information. The methodology was evaluated by the balqash lake basin wetland extraction in Kazakhstan. Experiments result shows that the hybrid method performs well in lake wetlands delineation. The overall accuracies of wetland classes exceed 85%, which can meet the application requirements

Isolation and characterization of α-amylase from marine Pseudomonas sp. K6-28-040

The α-amylase of marine Pseudomonas sp. K6-28-040 was purified through a series of three steps and the purity of enzymes was checked by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The results showed that, the enzyme was purified 4.7-fold with a specific activity of 134.6 U/mg protein and a yield of 44%. When it was subjected to SDS-PAGE, a single band near 58 kDa appeared. The optimum temperature and pH were 50°C and 7.0, respectively. The addition of Ca2+, Mn2+ and Co2+ could improve the enzyme activity, while Cu2+, Hg2+, Fe3+ and Al3+ decreased the activity. The enzyme was inhibited by ethylenediaminetetraacetic acid (EDTA), ethylenebis(oxonitrilo)]tetra-acetate (EGTA), SDS and dimethyl sulfoxide (DMSO), but was not affected by phenylmethane-sulfonyl fluoride (PMSF) and 1,4-dithiothreitol (DTT). Km and Vmax values of the purified enzyme for soluble starch were 1.73 ± 0.3 mg/ml and 1.24 ± 0.02 mg/ml/min, respectively. The degradation ability of wild type α amylase on starch granules was examined by thin layer chromatography. The final purified enzyme had an isoelectric point of 7.5-7.8 and α-helix of 28%, β-sheet of 32% and random coil of 40%.Keywords: α-Amylase; Pseudomonas sp., purification, enzyme characterizatio

Metal oxide nanofibres membranes assembled by spin-coating method

Ceramic membranes are of particular interest in many industrial processes due to their ability to function under extreme conditions while maintaining their chemical and thermal stability. Major structural deficiencies under conventional fabrication approach are pin-holes and cracks, and the dramatic losses of flux when pore sizes are reduced to enhance selectivity. We overcome these structural deficiencies by constructing hierarchically structured separation layer on a porous substrate using larger titanate nanofibres and smaller boehmite nanofibres. This yields a radical change in membrane texture. The differences in the porous supports have no substantial influences on the texture of resulting membranes. The membranes with top layer of nanofibres coated on different porous supports by spin-coating method have similar size of the filtration pores, which is in a range of 10–100 nm. These membranes are able to effectively filter out species larger than 60 nm at flow rates orders of magnitude greater than conventional membranes. The retention can attain more than 95%, while maintaining a high flux rate about 900 L m-2 h. The calcination after spin-coating creates solid linkages between the fibres and between fibres and substrate, in addition to convert boehmite into -alumina nanofibres. This reveals a new direction in membrane fabrication

High-Performance Ceramic Membranes with a Separation Layer of Metal Oxide Nanofibers

In conventional fabrication of ceramic separation membranes, the particulate sols are applied onto porous supports. Major structural deficiencies under this approach are pin-holes and cracks, and the dramatic losses of flux when pore sizes are reduced to enhance selectivity. We have overcome these structural deficiencies by constructing hierarchically structured separation layer on a porous substrate using lager titanate nanofibers and smaller boehmite nanofibers. This yields a radical change in membrane texture. The resulting membranes effectively filter out species larger than 60 nm at flow rates orders of magnitude greater than conventional membranes. This reveals a new direction in membrane fabrication

Unit Integration Method Solution and Experimental Research on Mechanism Characteristics for Flat Digging of Grab Dredgers

In the process of grab dredger dredging, how to ensure the accuracy of flat digging is a key technical question. The accuracy of flat digging is related to the force of grab digging. However, there are limitations in the traditional method of studying the force of grab digging. In this study, based on the Rankine theory, the unit integration method is proposed to calculate the force process of grab excavation. This method determines the shape and position of the failure surface under the action of active pressure FB and passive pressure FE and further obtains a functional expression for the relation between digging force and digging parameters. Through the simulation of flat digging force using the discrete element method (DEM), we obtained results consistent with the calculation results of the unit integration method. In addition, this study sought to control the movement distance of the closing wires and the hoist wires through the equation of motion, to carry out the precision calculations of theoretical data, and experimental research into grab flat digging. By comparing theoretical data and test data, the following conclusion was drawn: the deviation of the theoretical flat digging precision from the test data falls within the allowable range, at 3.15%. This study provides technical support for the flat digging process of the grab dredger

Experimental Investigation on the Dynamic Modulus Properties of Methane Hydrate Sediment Samples

Studying the strength and deformation properties of sediments containing gas hydrates is one of the key problems during the process of hydrate resource exploitation. In this paper, considering the effects of temperatures (−5, −3, −1 °C), confining pressures (0.5, 1, 2 MPa) and porosities (40%, 80%) on the dynamic modulus characteristics of sediments containing methane hydrates, several dynamic loading experiments were conducted. The results show that the sediment structure was more easily destroyed under a larger amplitude of dynamic loading. According to the dynamic stress–strain curves, the skeleton curves of the sediment samples were obtained, and it was shown that the deformation behaved with elastic characteristics in the initial stage, and then plastic deformation increased gradually and played a leading role with the increase in external loading. The maximum dynamic elastic modulus of sediments was reduced under the conditions of higher temperature and porosity, and effectively enhanced under higher confining pressure. Finally, on the basis of the Hardin–Drnevich equivalent model, and considering the influences of temperatures and confining pressures on model parameters, a viscoelastic constitutive model applied to analyze the dynamic modulus characteristics of sediments containing methane hydrate was established. The comparison showed that these calculated values of sediments’ dynamic elastic modulus accorded quite well with the experimental values

TiO2 nanofibers of different crystal phases for transesterification of alcohols with dimethyl carbonate

TiO2 nanofibers with different crystal phases have been discovered to be efficient catalysts for the transesterification of alcohols with dimethyl carbonate to produce corresponding methyl carbonates. Advantages of this catalytic system include excellent selectivity (>99%), general suitability to alcohols, reusability and ease of preparation and separation of fibrous catalysts. Activities of TiO2 catalysts were found to correlate with their crystal phases which results in different absorption abilities and activation energies on the catalyst surfaces. The kinetic isotope effect (KIE) investigation identified the rate-determining step, and the isotope labeling of oxygen-18 of benzyl alcohol clearly demonstrated the reaction pathway. Finally, the transesterification mechanism of alcohols with dimethyl carbonate catalyzed by TiO2 nanofibers was proposed, in which the alcohol released the proton to form benzyl alcoholic anion, and subsequently the anion attacks the carbonyl carbon of dimethyl carbonate to produce the target product of benzyl methyl carbonate

Purification and characterization of a hyperthermostable Mn-superoxide dismutase from Thermus thermophilus HB27

Thermostable Mn-dependent catalases are promising enzymes in biotechnological applications. In the present study, a Mn-containing superoxide dismutase of the hyperthermophilic Thermus thermophilus HB27 had been purified and characterized by a two-stage ultrafiltration process after being expressed in E. coli. The enzyme was highly stable at 90°C and retained 57% activity after heat treatment at 100°C for 1 h. The native form of the enzyme was determined as a homotetramer by analytical size exclusion chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The final purified enzyme had an isoelectric point of 6.2 and a high α-helical content of 70%, consistent with the theoretical values. This showed that the purified SOD folded with a reasonable secondary structure