71 research outputs found

    Data driven three-dimensional temperature and salinity anomaly reconstruction of the northwest Pacific Ocean

    Get PDF
    By virtue of the rapid development of ocean observation technologies, tens of petabytes of data archives have been recorded, among which, the largest portion are those derived from the orbital satellites, embodying the character of ocean surface. Nevertheless, the insufficiency of information below the subsurface restricts the utilization of these data and the understanding of ocean dynamics. To circumvent these difficulties, we present the spatially three-dimensional reconstruction of ocean hydrographic profiles at depth based on the satellites and in-situ measurement data. In this manuscript, long short-term memory network (LSTM) and Gaussian process regression (GPR) methods are invoked to predict the temperature and salinity profiles in the northwest Pacific Ocean, and to improve computational and storage efficiency, the proper orthogonal decomposition (POD) method is subtly incorporated into these two models. LSTM and GPR show satisfactory results, with the root mean square error (RMSE) of temperature is less than 1.45, and the RMSE of salinity is less than 0.19. The incorporation of the POD method substantially accelerates efficiency, particularly in the LSTM model, which improves 7.5-fold without significant accuracy loss. The sensitivity of different sea surface parameters on the reconstructed profiles reveals that sea surface height anomaly and latitude significantly influence the reconstruction of temperature anomaly (TA) and salinity anomaly (SA) profiles. Besides, sea surface salinity and sea surface temperature anomalies can improve the model's estimation ability for the upper TAs and SAs, respectively. The contribution of monthly climatology to temperature and salinity profile estimation is also explored in this paper. It is shown that adding monthly mean climatology to the input of the model can achieve more accurate estimates

    Preparation and Characterization of Emamectin Benzoate Solid Nanodispersion

    Get PDF
    The solid nanodispersion of 15% emamectin benzoate was prepared by the method of solidifying nanoemulsion. The mean particle size and polydispersity index of the solid nanodispersions were 96.6±1.7 nm and 0.352±0.041, respectively. The high zeta potential value of 31.3±0.5 mV and stable crystalline state of the nanoparticles suggested the excellent physical and chemical stabilities. The contact angle and retention compared with microemulsions and water dispersible granules on rice, cabbage, and cucumber leaves indicated its improved wettability and adhesion properties. The bioassay compared with microemulsions and water dispersible granules against diamondback moths and green peach aphids provided an evidence of its enhanced biological activity. This formulation composition could avoid organic solvents and obviously reduce surfactants. It is perspective in raising bioavailability and reducing residual pollution of pesticides and further improving agricultural production and environmental safety

    Alternative binder phases for WC cemented carbides

    No full text
    WC cemented carbides are composites consisting of WC and a binder phase. WC/Co is widely used as cutting tools due to its excellent combination of hardness and toughness. This thesis work was performed at the R&D department of Sandvik Coromant and aimed to find the alternative binder phase to substitute cobalt. Several compositions of Fe-Ni and Fe-Ni-Co binder have been investigated in this study. The WC/Co reference samples were also prepared. The initial compositions were decided by the CALPHAD method. The samples were then produced by the means of powder metallurgy. The producing conditions, especially the sintering conditions, were manipulated to achieve full dense and uniform samples. The samples were analyzed by XRD, LOM, SEM, and EDS. Mechanical properties test has also been performed.The results showed that adjustment on carbon content is necessary to attain desirable structure. Increasing Fe content in the binder tends to make the materials harder. For Fe-Ni and Fe-Ni-Co, the martensitic transformation is essential to the mechanical performance. The induced “transformation toughening” in 72Fe28Ni and 82Fe18Ni binders significantly promoted the toughness. Furthermore, the grain growth inhibition by Fe was confirmed. The relations between sintering temperature, grain size and mechanical properties have been discussed. Compared with the WC/Co references, several compositions showed close and even superior mechanical performance which might provide solutions for the future alternative binder phase

    Alternative binder phases for WC cemented carbides

    No full text
    WC cemented carbides are composites consisting of WC and a binder phase. WC/Co is widely used as cutting tools due to its excellent combination of hardness and toughness. This thesis work was performed at the R&D department of Sandvik Coromant and aimed to find the alternative binder phase to substitute cobalt. Several compositions of Fe-Ni and Fe-Ni-Co binder have been investigated in this study. The WC/Co reference samples were also prepared. The initial compositions were decided by the CALPHAD method. The samples were then produced by the means of powder metallurgy. The producing conditions, especially the sintering conditions, were manipulated to achieve full dense and uniform samples. The samples were analyzed by XRD, LOM, SEM, and EDS. Mechanical properties test has also been performed.The results showed that adjustment on carbon content is necessary to attain desirable structure. Increasing Fe content in the binder tends to make the materials harder. For Fe-Ni and Fe-Ni-Co, the martensitic transformation is essential to the mechanical performance. The induced “transformation toughening” in 72Fe28Ni and 82Fe18Ni binders significantly promoted the toughness. Furthermore, the grain growth inhibition by Fe was confirmed. The relations between sintering temperature, grain size and mechanical properties have been discussed. Compared with the WC/Co references, several compositions showed close and even superior mechanical performance which might provide solutions for the future alternative binder phase

    Arabidopsis Ribonucleotide Reductases Are Critical for Cell Cycle Progression, DNA Damage Repair, and Plant Development

    No full text
    Ribonucleotide reductase (RNR), comprising two large (R1) and two small (R2) subunits, catalyzes a rate-limiting step in the production of deoxyribonucleotides needed for DNA replication and repair. Previous studies in yeast and mammals indicated that defective RNR often led to cell cycle arrest, growth retardation, and p53-dependent apoptosis, whereas abnormally increased RNR activities led to higher mutation rates. Because plants are constantly exposed to environmental mutagens and plant cells are totipotent, an understanding of RNR function in plants is important. We isolated and characterized mutations in all three R2 genes (TSO2, RNR2A, and RNR2B) in Arabidopsis thaliana. tso2 mutants had reduced deoxyribonucleoside triphosphate (dNTP) levels and exhibited developmental defects, including callus-like floral organs and fasciated shoot apical meristems. tso2 single and tso2 rnr2a double mutants were more sensitive to UV-C light, and tso2 rnr2a seedlings exhibited increased DNA damage, massive programmed cell death, and release of transcriptional gene silencing. Analyses of single and double r2 mutants demonstrated that a normal dNTP pool and RNR function are critical for the plant response to mutagens and proper plant development. The correlation between DNA damage accumulation and the subsequent occurrence of apoptotic nuclei in tso2 rnr2a double mutants suggests that perhaps plants, like animals, can initiate programmed cell death upon sensing DNA damage

    Analysis on Land Ticket Transaction System of Chongqing Municipality

    No full text
    On the basis of analyzing essence of land ticket system of Chongqing Municipality and its transaction process, this paper studies the relationship between government and farmers and between city and countryside, and discusses the drawbacks of land ticket system in Chongqing Municipality. Results show that inherent drawbacks of land ticket system and wrong guidance of policies lead to suspicion of land ticket system occupying rural resources. Interregional exploitation and generation exploitation are inherent mechanism of city exploiting countryside. Finally, it proposes increasing construction land index to satisfy demand of new socialist countryside construction primarily, to ensure rural social stability; Later, use land ticket index to fill the gap of construction land in economically developed areas, so as to alleviate conflict of urban land use and maximize circulation value of rural construction land. It is expected to provide theoretical reference for relevant departments to regulate land ticket transaction system and realize harmonious development ,between urban and rural areas

    Adsorption of Cr(â…Ą) polluted water by Fe3O4@SiO2-APTMS nanocomposites prepared in the presence of ultrasonic irradiation for sustainable water resources utilization

    No full text
    The research on developing a purification technology for Cr(â…Ą) polluted water with high efficiency and the low energy consumption is crucial for achieving several Sustainable Development Goals (SDGs). In order to achieve these goals, Fe3O4@SiO2-APTMS nanocomposites were prepared by Fe3O4 nanoparticles modified with silica and 3-aminopropyltrimethoxysilane in the presence of ultrasonic irradiation. The nanocomposites were characterized by TEM, FT-IR, VSM, TGA, BET, XRD, XPS and these analytic results proved that the nanocomposites were successfully prepared. The influential factors of Fe3O4@SiO2-APTMS on Cr(â…Ą) adsorption have been explored and better experimental conditions have been obtained. The adsorption isotherm conformed to the Freundlich model. Pseudo-second-order kinetic model provided a better correlation for the experimental data compared to other kinetic models. Thermodynamic parameters for adsorption indicated that the adsorption of Cr(â…Ą) was a spontaneous process. It was speculated that the adsorption mechanism of this adsorbent includes redox, electrostatic adsorption and physical adsorption. In summary, the Fe3O4@SiO2-APTMS nanocomposites were of great significance to human health and the remediation of heavy ion pollution, contributing to achievement of the Sustainable Development Goals (SDGs), including SDG-3, SDG-6
    • …
    corecore