环境磁学参数简介

环境磁学是20世纪80年代一门新兴的学科,是介于地球科学、环境科学及磁学的边缘科学。它通过研究磁性矿物在环境系统中的迁移、转化和组合的规律,根据物质在磁性特征上的联系及其反映在环境上的内涵,探索不同空间尺度的环境作用、环境问题和人类活动影响,揭示环境变化过程和机制。由于环境磁学具有快速、高效、经济以及对样品无破坏性等优点,近些年来得到越来越广泛的应用。但其采用的方法及涉及到的参数繁多,很容易混淆,本文简要介绍了环境磁学涉及的参数及其基本物理含义,为应用环境磁学解决气候、环境污染等问题提供参考。     

Characteristics and Rheological Properties of Polysaccharide Nanoparticles from Edible Mushrooms (Flammulina velutipes)

Nanotechnology has become relevant in the food‐related industries, and edible mushrooms can be a potential raw material for providing satisfied edible nanomaterial. In this study, by following 3 different pretreatments (hot water or cold alkali or hot alkali) insoluble polysaccharide nanoparticles were prepared from Flammulina velutipes by wet milling and high pressure homogenization and their properties were investigated. The resultant nanoparticles were characterized by SEM, GC‐MS (for its main compositions), FTIR, XRD, and TG. The 1 wt% nanoparticle dispersions presented non‐Newtonian, shear‐thinning fluids with the viscosity in an increasing order for the hot water < cold alkali < hot alkali. Moreover, the dynamical rheological results showed differences of storage (G′) and loss (G″) moduli of these particle dispersions. It was concluded that the Flammulina velutipes‐derived polysaccharides nanoparticles have great potential applications in the food industry, for example, as emulsifiers, reinforcement agents, and bioactive carriers.     

工业废水污染控制方法的新进展

环境污染是当今人类面临最大的危害之一,特别是工业生产的发展,排出大量的废水,这些废水如直接排放或处理不当,将影响水体的自净,因而使水质恶化。人们日益意识到环境污染带来的危害,现在污水必须通过处理才能排放已成为人们的共识。本文概括了应用于工业废水处理的化学法、物理化学法和生物法的一般原理和最新进展,由于废水的组成复杂,往往需要由几种方法组成一个处理系统,才能完成所要求的处理功能,因此指出不能认为某种方法是最好的,最先进的。同时指出：尽管化学方法有其自身的缺点,但在某些方面仍然有不可替代的作用;研究开放高效、经济的应用于工业废水处理新技术已成为环保工作者的热点。     

电子级金红石型TiO_2生产工艺的改进

对ＴｉＣｌ４水解法生产ＴｉＯ２的生产工艺进行了改进，结果ＴｉＯ２的物理特性，诸如晶型、颗粒形状、粒度分布及平均粒径得到改善。     

水热处理后FCC催化剂及Y型沸石的裂化活性及其物化性质表征

采用DTA、XRD、^27Al NMR和吡啶吸附-IR等方法，对水热处理后在不同条件下存放的两种FCC催化剂及相应的Y型沸石分别进行了物化性质表征。结果表明，经水热处理后在空气气氛下放置时，沸石易于吸附环境中的水分形成一定量的表面水，并将表面水进一步极化成以活性羟基形式存在的结构水，从而使总酸量提高；同时，在空气气氛中放置吸水后，沸石骨架中可能发生了晶格重排，部分非骨架铝转变为骨架铝，使晶胞常数略有增加。对水热处理后不同存放条件下FCC催化剂的裂化活性变化规律及其物化性质进行了关联。     

农作物秸秆纤维增强脱硫石膏墙体材料的制备与研究

以玉米秸秆纤维和稻草秸秆纤维作为脱硫石膏的增强材料,研究不同纤维掺量、碱处理浓度对农作物秸秆纤维增强脱硫石膏墙体材料物理力学性能、耐水性能和保温性能的影响.结果表明:玉米秸秆纤维掺量为3％时试样强度最高,抗折和抗压强度分别达到6.4 MPa和14.9 MPa,而掺稻草秸秆纤维的分别为6.2 MPa和14.3 MPa.农作物秸秆纤维经碱溶液处理后,与脱硫石膏之间胶结能力增强,5％碱溶液处理试样的抗折强度和抗压强度分别可提高到7.1 MPa和16.4 MPa.纤维能够阻止水分在墙体材料内部孔隙中迁移,提高其耐水性能,墙体材料吸水率最低为21.3％,软化系数最高可达0.56.掺加农作物秸秆纤维能够增加脱硫石膏墙体材料孔隙率,故降低其导热系数,导热系数最低可降至0.121 W/(m·K).     

Statistical approach of sedimentation flows

Statistical physics methods are applied to analyze a fluid particles flow in an attempt to avoid the over-detailed knowledge of the hydrodynamic interactions. The fluid is considered as a steady source of energy which controls the particle agitation, like a thermostat in molecular physics. This method was applied to a flow previously studied with the help of three-dimensional visualizations in which spherical particles fell down into a fluid in a square section channel. This flow is characterized by a solid volume fraction of 5% and a particle Reynolds number around 4. Schematically the beads are divided into free beads and beads involved in chain caused par wakes interactions. These wake effects explain the non-Maxwellian behavior of the solid phase. The wall influence on the normal velocity component is taken into account by an interaction potential related to the kinetic energy and the distance from the wall.     

Development of Spatially Dependent Resonance Shielding Method

A new spatially dependent resonance self-shielding method (SDDM: Spatially Dependent Dancoff Method) was developed based on the generalization of the conventional Dancoff method to multi-regions in a fuel pellet based on the Stoker/Weiss technique. SDDM correctly accounts for radial power distribution within fuel rods in a fuel assembly. SDDM is fully consistent with the conventional method if the pellet is not sub-divided. It also has the advantage of being less computing time consuming when compared to more rigorous resonance shielding method such as sub-group and special fine energy mesh methods. Moreover, it can be installed easily into the lattice physics code widely used in commercial LWR design. To validate the method, spatial concentration of isotopes and burnup distribution within a rod are evaluated using SDDM and the results are compared to the destructive measurement data. From the comparison, it is concluded that the spatially dependent Dancoff method, SDDM, is appropriate for generating the effective cross-sections in the fuel rings.