The role of riparian woods in regulating nitrogen fluxes between the alluvial aquifer and surface water: A conceptual model

Conceptual models are proposed to explain nitrogen fluxes in the soils of riparian zones in relation to the different modalities of water logging and nitrate inputs. Non-submerged, temporarily submerged, and always submerged, sites are considered in both winter and summer. It is shown that capacities for epuration are elevated for nitrate loads from the alluvial aquifer during the lateral transfer of water from agricultural land to the river through the riparian zone. About 30 m of groundwater flow under the riparian wood studied is sufficient to remove all nitrate. Denitrification rates up to 50 mg N₂ per m² per day were observed in the field, but a potential for more denitrification exists. The efficiency of the riparian woods as natural filters regulating nutrient transfers to the river deserves more consideration in river management.     

热浸镀铝助镀剂及表面熔融剂配方的研究

通过研究得到了合理的热浸镀铝助镀剂及表面熔融剂的配方。     

连铸结晶器保护渣配炭量及配炭方式的研究

本文研究了保护渣熔化速度、熔融特性和熔融结构与渣中配炭量、配炭种类和配炭方式的关系。研究发现,炭质材料影响保护渣熔融行为的程度取决于炭质材料的含碳量,分散度和着火点,复合配炭优于目前广泛采用的单一配炭,采用复合配炭后,保护渣的熔融结构呈含有熔融层,半熔层、烧结层和粉渣层的多层熔融模型,熔化速度随含碳量的改变增减较缓。熔融特性在较宽的温度范围内保持相对稳定,使之能适应于连铸工艺参数在连铸过程中的突变。     

Characteristic patterns of QuikScat-based wind stress and turbulent heat flux in the tropical Indian Ocean

Using QuikScat-based vector wind data for 1999-2003, surface wind stress and turbulent heat (Q) have been mapped for the tropical Indian Ocean (IO) to understand their seasonal variability. During July wind stress is enhanced by ∼ 70% in the Arabian Sea compared to that during January. The Arabian Sea experiences a large Q loss (150-200 W/m²) during the summer and winter monsoons, which is nearly 1.3 times of that in the Bay of Bengal. The southeasterlies are strengthened during the southern hemisphere winter. Empirical Orthogonal Function analysis captures different phases of monsoon-induced variability in wind stress and Q, ranging from seasonal to high-frequency perturbations. Coherency between time coefficients of EOF-1 for wind stress and Q suggests that former leads the latter with a temporal lag of 20-40 days for period > 322 days. At high frequencies (< 21 days) Q leads wind stress with a temporal lag of 2 days. Possible explanation for wind stress leading Q over an annual time scale is offered based on the marine atmospheric boundary layer physics and pre-conditioned ocean surface, while on shorter time scales (21 days) ocean thermodynamics through mixed layer processes cause Q to lead wind stress.     

An a Posteriori Error Estimator for Two-Body Contact Problems on Non-Matching Meshes

A posteriori error estimates for two-body contact problems are established. The discretization is based on mortar finite elements with dual Lagrange multipliers. To define locally the error estimator, Arnold–Winther elements for the stress and equilibrated fluxes for the surface traction are used. Using the Lagrange multiplier on the contact zone as Neumann boundary conditions, equilibrated fluxes can be locally computed. In terms of these fluxes, we define on each element a symmetric and globally H(div)-conforming approximation for the stress. Upper and lower bounds for the discretization error in the energy norm are provided. In contrast to many other approaches, the constant in the upper bound is, up to higher order terms, equal to one. Numerical examples illustrate the reliability and efficiency of the estimator. This work was supported in part by the Deutsche Forschungsgemeinschaft, SFB 404, B8.     

Characterization of Procoagulant COAT Platelets in Patients with Glanzmann Thrombasthenia

Patients affected by the rare Glanzmann thrombasthenia (GT) suffer from defective or low levels of the platelet-associated glycoprotein (GP) IIb/IIIa, which acts as a fibrinogen receptor, and have therefore an impaired ability to aggregate platelets. Because the procoagulant activity is a dichotomous facet of platelet activation, diverging from the aggregation endpoint, we were interested in characterizing the ability to generate procoagulant platelets in GT patients. Therefore, we investigated, by flow cytometry analysis, platelet functions in three GT patients as well as their ability to generate procoagulant collagen-and-thrombin (COAT) platelets upon combined activation with convulxin-plus-thrombin. In addition, we further characterized intracellular ion fluxes during the procoagulant response, using specific probes to monitor by flow cytometry kinetics of cytosolic calcium, sodium, and potassium ion fluxes. GT patients generated higher percentages of procoagulant COAT platelets compared to healthy donors. Moreover, they were able to mobilize higher levels of cytosolic calcium following convulxin-plus-thrombin activation, which is congruent with the greater procoagulant activity. Further investigations will dissect the role of GPIIb/IIIa outside-in signalling possibly implicated in the regulation of platelet procoagulant activity.     

Effects of crystallisation behaviour of mould fluxes on properties of liquid slag film

Abstract

During the continuous casting of medium carbon steel slabs, stable liquid slag film performance is necessary to ensure that the process runs smoothly. In this paper, the effects of mould flux crystallisation behaviour on the properties of leftover liquid slag films were examined. First, the compositions of the leftover liquid slags of high fluorine, CaO–SiO₂–TiO₂ and CaO–SiO₂–Na₂O based mould fluxes after a single crystalline phase was separated were calculated. Then, the viscosity, melting temperature, break temperature and degree of crystallisation of each leftover liquid flux were measured. The results revealed that the properties of leftover liquid slag films of CaO–SiO₂–TiO₂ and CaO–SiO₂–Na₂O based mould fluxes are not as stable as those of high fluorine films after crystallisation. This paper provides a new method for developing fluorine free mould fluxes and for determining the most suitable type of crystalline phase that should be utilised in the continuous casting of medium carbon steel slabs.     

新型水性铝焊膏的研究

铝焊膏分油性和水性,水性铝焊膏由铝钎料、铝钎剂和水性成膏体组成,通过对这三组分定性、定量的研究,尤其将研究重点放在水性成膏体方面,研制出了新型水性铝焊膏。该水性铝焊膏同样适合于铝-铝、铝-铝合金、铝-不锈钢的焊接,具有简单、方便和环保的特点。     

Viscosity of Fluoride‐Free Mold Fluxes Containing B2O3 and TiO2

Viscosities of B₂O₃ and TiO₂‐bearing fluoride‐free mold fluxes have been measured by the rotating cylinder method in this work. Effects of different B₂O₃, TiO₂ content, and basicities on the viscosity characteristics have been examined. Viscosity of fluoride‐free mold fluxes containing B₂O₃ and TiO₂ was found to decrease with the increase of B₂O₃, TiO₂ content, and basicity. The values of apparent activation energy for viscous flow of slags decrease with additions of B₂O₃ and TiO₂ and the increase of basicity. Two parameters A and B in Riboud model were re‐evaluated based on the present experimental data, and the modified Riboud model was used to estimate the viscosity of fluoride‐free slag system investigated in present work. The viscosity values obtained by the experimental measurement were in good agreement with those calculated by the modified Riboud model.