Silica Dynamics of Tidal Marshes in the Inner Elbe Estuary, Germany

In this study the seasonal and spatial variation of dissolved silica (DSi) and biogenic silica (BSi) in tidal marshes in the inner Elbe estuary was investigated. Seasonal sampling was conducted at three sites in the dyke foreland—the stretch of land between dyke and estuary—of the Elbe estuary, Germany. To assess the potential DSi export from the dyke foreland geographic information systems were used to calculate the DSi flux. Mean annual seepage DSi concentrations increased along the salinity gradient from 270 μmol L^???1 to 380 μmol L^???1. BSi concentration of the soil showed the opposite trend decreasing from 15.8 to 4.8 mg g^???1. Temporal variations of DSi concentrations were lowest at the freshwater site. At the brackish and saline site DSi concentrations increased about 2-fold from March to November from 200 to 500 and from 300 to 550 μmol L^???1, respectively. In March a diurnal signal of DSi uptake by diatoms could be observed at the saline sampling site, highlighting the role of sampling time and irradiance for the DSi flux estimate. DSi concentrations were reduced by 18.6 % between sunrise and noon. The DSi export from the dyke foreland is significant and equals the riverine DSi input into the estuary during times of low DSi concentrations. Furthermore the marsh DSi fluxes surpass DSi fluxes from highly active weathering regions, as reported in the literature, which corroborates the importance of tidal marsh areas for the coastal silica cycle. Factors steering the seasonality of DSi export and differences between the sites (temperature, hydrology, salinity and plant uptake of DSi) are discussed.     

The Marsh cone: a test or a rheological apparatus?

The present study is concerned with the Marsh cone, a workability test used for specification and quality control of cement pastes and grouts. It is demonstrated here that, under several consistency and geometry conditions, the flow time reflecting “fluidity” may be calculated from the plastic viscosity and yield stress in the case of a Bingham fluid and from the cone geometry. A relation between the behaviour parameters and the flow time of fresh pastes tested is derived and experimentally validated. A practical application of these results is suggested. Lastly, the concept of a new test apparatus based on two cones is presented and tested on a single cement paste.     

沼气脱硫系统存在的问题及解决措施

简单介绍了某公司沼气脱硫系统在生产初期出现的一些问题,通过对这些问题的分析和判断,提出了解决问题的方案.通过多次试验并与原来方法对比,提出的新方法在沼气脱硫系统生产中是成功的、令人满意的.     

成核阶段对沉淀法白炭黑团聚程度的影响

白炭黑制备过程中发生的团聚会影响其分散性,研究影响白炭黑制备过程中团聚程度的主要因素有助于制备高分散的白炭黑。本文采用正交实验法研究了沉淀法白炭黑制备过程中成核阶段各个因素对白炭黑团聚程度的影响,采用透射电镜表征白炭黑一次粒子大小和团聚程度,采用激光粒度仪表征白炭黑的平均粒径。结果表明,反应温度、硅酸钠浓度及加酸速度是影响白炭黑二次粒子平均粒径及团聚程度的主要因素;高温下,白炭黑一次粒子约为50 nm,团聚程度较高,但二次粒子平均粒径较小;低温下,白炭黑一次粒子约为10 nm,团聚程度略小。随着低温反应时间的增长,白炭黑一次粒子团聚程度增加。     

废水池钼酸的回收利用研究

废水池中钼酸回收利用在整个钼酸铵生产工艺中是比较重要的一环,尤其对钼酸铵成品中回收率影响比较大,同时是影响钼酸铵成品的化学指标,由于近年来随着国际、国内钼金属深加工技术的发展,对钼酸铵提出了更高的要求,我们需要对废水池钼酸的回收利用进行研究,为以后钼酸铵的生产工艺提供可靠的依据。     

气相法二氧化硅在胶衣树脂中的应用

通过气相法二氧化硅在胶衣树脂中的应用实验,重点研究影响不饱和树脂触变性和黏度的因素.同时测定树脂浇铸体的各项力学性能并讨论了影响该性能的因素.此外,将国产的气相法二氧化硅与国外的同类产品进行比较.     

玻璃用硅砂的若干探索

将相同颗粒配比不同产地的硅砂配制成配合料。通过配合料熔化实验,对1390℃玻璃液中未熔物的量及颗粒形貌进行观察对比,结果表明,不同产地的硅砂,熔化难易程度是不同的。     

催化剂载体—硅胶在催化反应中的应用

本文主要介绍了硅胶载体在催化反应中的一些应用。文中所说的催化反应主要有氧化反应、加氢反应、脱氢反应、氢甲酰化反应、烷基化反应等等。     

化工园区公共事故应急缓冲池设计研究

参照化工企业应急事故缓冲池的设计,对化工园区的应急事故缓冲池进行了设计研究,并提出了化工园区的应急事故缓冲池设计的意见和建议。     

布袋除尘器在气相法白炭黑生产中的应用

介绍了布袋除尘器在气相法白炭黑生产中的作用,通过布袋除尘器的过滤作用,将尾气中的白炭黑全部截留重新送回系统,提高了产品的收率,避免白炭黑进入尾气堵塞吸收系统,保证了生产装置的连续稳定运行。     

Phosphorus Loss in Tile Drains from a Reclaimed Marsh Soil Amended with Manure and Phosphogypsum

Reclamation of Guadalquivir river marshes (SW Spain) constitutes a representative example of wetland reclamation in Southern Europe. Nowadays, this is an important area of tile-drained soils (40,000 ha) with an intensive irrigated agricultural production where high fertilizer rates are usually applied. In tile-drained soils, flow through macropores or cracks, which connect the nutrient rich topsoil with drain lines, can be an important pathway for nutrient transfer from soil. In order to study P loss in these soils and how it is affected by soil amendment usually applied in the zone (phosphogypsum and manure) an experiment was performed during two consecutive growing seasons on a reclaimed marsh soil from the Guadalquivir Valley. In the first season (1998–1999), sugar beet (Beta vulgaris L.) was grown under sprinkler irrigation at a rate of 2.5 mm h⁻¹; in the second (2000), cotton (Gossypium hirsutum L.) was grown under furrow irrigation at 8–10 mm h⁻¹. The amendments applied included manure (30 Mg ha⁻¹), and phosphogypsum (13 and 26 Mg ha⁻¹). Drainage events were recorded, and water samples collected and analyzed for total P (TP), dissolved total P (DTP), and dissolved reactive P (DRP). Total P in drainflow ranged from 0 to 0.818 mg l⁻¹ in the 1998–1999 season and from 0 to 0.565 mg l⁻¹ in the 2000 season. The major P form in drainflow was DRP, which accounted for about 50% of TP in the two growing seasons (the mean DRP concentration was 0.068 mg l⁻¹ in 1998–1999 and 0.043 mg l⁻¹ in 2000). Dissolved organic P accounted for a higher portion of DTP in the first season (37%) than in the second (13%). A larger load of phosphorus was observed on plots receiving manure. This treatment significantly increased (P<0.05) the cumulative drainflow during the 1998–1999 growing season (sprinkler irrigation, low drainflow rates). This is consistent with the increased losses of TP, DTP, DAHP, and DRP resulting from this treatment in this growing season. In the following season, DTP loading were significantly increased by manure (P<0.05). This seems to be related mainly to significantly increased DOP losses (P<0.01), particularly during the first drainage event. The higher fraction of applied water was lost by drainage under furrow irrigation (high drainflow rates) is consistent with the high TP load during the 2000 growing season (199–285 g ha⁻¹) relative to the 1998–1999 season (20–59 g ha⁻¹). This difference in P losses was much greater than those resulting from amendment of the soil.     

微乳液水核结构对铟纳米粒子分散形态的影响

在环己烷/正己醇／水／乳化剂微乳液中,通过脉冲激光制得并观察到了球形、扁球形、六边形及棒状分散形态的铟纳米粒子。考察了不同水核的红外光谱图,利用透射电镜,观察到了铟纳米粒子的不同分散形态。     

Cationic Graft Polymerization onto Silica Nanoparticle Surface in a Solvent-Free Dry-System

For the purpose of the prevention of the environmental pollution and the simplification of reaction process, the scale-up synthesis of polymer-grafted silica nanoparticle by surface initiated cationic ring-opening graft polymerization of 2-methyl-2-oxazoline (MeOZO) in a solvent-free dry-system was investigated. The introduction of iodopropyl groups onto the silica surface as initiating group was carried out by the reaction of silanol groups with 3-iodopropyl- trimethoxysilane in a solvent-free dry-system. The graft polymerization of MeOZO onto silica nanoparticle surface in a solvent-free dry-system was initiated by spraying the monomer onto the surface having iodopropyl groups and the polymerization was conducted in powder fluid system under nitrogen. After the polymerization, unreacted MeOZO was readily removed under high vacuum. It was found that the cationic ring-opening polymerization of MeOZO was successfully initiated in the solvent-free dry-system to give polyMeOZO-grafted silica nanoparticles. The maximum grafting of polyMeOZO obtained from the polymerization initiated by iodopropyl groups on the surface reached 47.7 %. The percentage of grafting and grafting efficiency during the cationic ring-opening graft polymerization in the solvent-free dry-system were considerably larger than those in solution system. This suggests that chain transfer reaction from surface growing cation to monomer was effectively inhibited in the solvent-free dry-system.     

Apatite Formation Induced by Silica Gel in a Simulated Body Fluid

It has been confirmed that the essential condition for glasses and glass-ceramics to bond to living bone is the formation of an apatite layer on their surfaces in the body. It has been proposed that a hydrated silica formed on the surfaces of these materials in the body plays an important role in forming the surface apatite layer, but this has not yet been proved. In the present study, it is shown experimentally that a pure hydrated silica gel can induce apatite formation on its surface in a simulated body fluid when its starting pH is increased from 7.2 to 7.4.     

大气中二氧化硅光度法测定方法的研究

飘尘中的二氧化硅用盐酸溶解后,在氢氧化钠的碱性条件下与钼酸盐生成黄色的硅钼酸进行比色测定。     

Silica Structure Studies: V, The Variable Inversion in Cristobalite

It is demonstrated experimentally that even in the purest laboratory silicas available the temperature of the α-β inversion in cristobalite is variable and depends on the structure of the starting material and on the temperature and length of heat-treatment. It is shown that this variability is an index of the order achieved in the cristobalite structure quite independent of impurities. There is no specific order characteristic of a particular temperature; the completely ordered 3 C stacking of cristobalite is the most stable cristobalite throughout the temperature range and has an α-β inversion temperature of 267°± 2°C. All disordered cristobalites will tend toward the 3C 267° cristobalite with time. The conversion of cristobalite to tridymite involving the 3 C → 2 H stacking change does not alter the cristobalite inversion temperature, nor have any regular polytypes other than those recognized as tridymite been encountered.     

双组份彩色相纸显影液的研究

研究了一种双组份彩色相纸显影液：该显影液A组份高pH值,显影剂CD-3以对苯二胺游离碱形式和适量溶剂结合;该显影液B组份中含有灰雾抑制剂、显影促进剂、螯合剂等成分.这种显影液具有浓缩比高、储存稳定性好、色彩还原饱和高等特性.     

池式核沸腾中的“界面汽化热阱”效应

采用扩散极限电流技术 ( LDCT)与传热测定同时进行的实验方法分析了池核沸腾中的“界面汽化热阱”效应。传热实验所测定的是池核沸腾的总换热系数 ,由 LDCT测定并以类比原理可以获得对流传热系数 ,两者差值即为“界面汽化热阱”效应。实验结果表明 ,沸腾时 ,“界面汽化热阱”效应随热流率的提高而显著增大。对以 LDCT法测得的对流传热数据进行关联 ,获得了准数式。     

Preparation of Nano‐Structured RDX in a Silica Xerogel Matrix

RDX is preferred as explosive in munitions due to its balance of power and sensitivity that is known to be dependent on its particle size and size distribution. In this study, we prepared nano‐sized RDX in a silica xerogel matrix using a sol‐gel method and investigated its sensitivity for explosive properties. The presence of RDX in composite xerogel was confirmed by TG‐DSC and FTIR techniques. Microstructure and porosity were characterized by transmission electron microscopy (TEM), small angle X‐ray scattering, and N₂‐physisorption techniques. TEM results showed that the size of RDX particles in the RDX‐silica composites is in the range of 10–30 nm. The sensitivity to impact and friction was found to be higher for the composites compared to raw RDX. It was also found to be significantly dependent on the acetone/TMOS ratio used in the preparation.