Strength and Leaching Behavior of Contaminated Mining Sludge at High Water Content Stabilized with Lime Activated GGBS

Sludge management is one of the major challenges in mining activities. The direct disposal of contaminated mining sludge can bring severe damages to the environment and community. Solidification/stabilization (S/S) is a very efficient technology for the treatment of contaminated mining sludge because it improves the stability of sludge dumping sites and reduces the leachability of contaminants. Very few studies investigate the S/S of mining sludge, especially with high water content. This paper investigated the effectiveness of S/S for the treatment of mining sludge at high water content by using quick lime (CaO) activated ground granulated blast furnace slag (GGBS) in comparison to ordinary Portland cement (OPC). To evaluate the mechanical, leaching, and microstructural behavior of CMS at high water content stabilized by lime-activated GGBS and OPC, a series of laboratory experimental tests were performed. Experimental results indicated that increasing the dosage of binder led to increased strength and decreased leachability of the heavy metal. In contrast, an increase in the water content of the mixture resulted in a decrease in compressive strength and an increase in the leachability of heavy metals. On the other hand, lime-activated GGBS mixes had substantially better performance than OPC mixes in the aspect of strength development of treated mining sludge and showed comparable capability of heavy metal stabilization compared to OPC. The microstructural tests revealed the formation of different hydration products such as calcium silicate hydrate, calcium aluminum silicate hydrate, ettringite, hydrotalcite, and heavy metal complexes in CG and OPC mixes.     

三叉神经节细胞电压门控通道研究中的钙电流振荡活动

目的 :探讨三叉神经节细胞电压门控性钙通道电流特性。方法 :在急性分离的三叉神经节细胞膜上 ,阻断电压门控性延迟整流钾通道和电压门控性钠通道 ,在 - 70mV的钳制电位下 ,给予 1 0mV步幅递增、80ms步宽的去极化脉冲刺激 ,进行全细胞膜片钳记录。结果 :在仅阻断电压门控性延迟整流钾通道时 ,- 1 0mV的去极化脉冲刺激激活了三叉神经节细胞膜上继快钠电流之后的慢内向电流 ,呈重复开闭的振荡特性 ;同时阻断电压门控性延迟整流钾通道和电压门控性钠通道 ,在 - 2 0mV的去极化脉冲刺下 ,也可记录到呈振荡特性的慢内向电流。振荡电流可被细胞外喷射的 1mmol·L-1 尼福地平所阻断。结论 :三叉神经节细胞膜上高电压激活的重复开闭慢内向电流可能为电压门控性钙电流 ,其振荡特性可能与感觉信息中枢传入的初级加工有关。     

6 Role of gastric acid in the aetiology of dyspeptic disease and dyspepsia

The main diseases associated with dyspepsia are peptic ulcer disease, gastro-oesophageal reflux disease and non-ulcer dyspepsia. Increased gastric acid secretion is a characteristic of most duodenal ulcer patients and of a small minority of non-ulcer dyspepsia and gastro-oesophageal reflux disease patients. Although acid secretion is normal in most gastro-oesophageal reflux disease patients, the condition is mainly the result of excess exposure of the distal oesophagus to acid refluxing from the stomach. Increased mucosal sensitivity to acid is involved in the aetiology of dyspeptic symptoms in the majority of patients with peptic ulcer disease and gastro-oesophageal reflux disease, and in a minority of non-ulcer dyspepsia subjects. Gastric acid, therefore, plays an important role in both the aetiology of dyspeptic diseases and in the aetiology of dyspeptic symptoms.     

Comparison of methods for monitoring solid particulate surface contamination in the workplace

This paper reports an assessment of various methods for sampling particulate surface contamination for use in the field. The results from the study will be used to develop guidance for monitoring particulate surface contamination in the workplace.Three types of adhesive tape, two manual and two `semi-automatic' wipe methods, and one Smair method were assessed. A field assessment of selected methods was carried out in two stages. In stage one, the manual wipes, semi-automatic wipes and adhesive tape (Scotch Tape®) were compared. In stage two, the adhesive tape (Scotch Tape®), black forensic tape, clear forensic tape and Smair were compared.Visits were made to ten metal processing facilities and particulate contamination was sampled from six locations at each site. Sampling locations were chosen for their potential as points of worker dermal contact and also to represent a range of surface characteristics. The metal content of the samples were analysed using Atomic Absorption Spectrophotometry (AAS) and X-ray Fluorescence Spectrometry (XRF).It was found that the Smair method proved to be inefficient in removing surface contamination, particularly where the surface was damp or greasy. Tape methods were found to be the most satisfactory and have considerably greater efficiency than wipe sampling. The black forensic tape is the preferred sampling medium as it is highly efficient, reproducible and easy to use.     

Astrocyte-conditioned saline supports embryonic rat hippocampal neuron differentiation in short-term cultures

Embryonic rat hippocampal neurons were cultured for 1–2 days in serum-free, HEPES-buffered Tyrode's solution. The effects of cortical astrocytes and astrocyte-conditioned saline on neuron survival, membrane surface area and the expression of functional amino acid neurotransmitter receptors were studied. Neurons grown in Tyrode's solution alone survived well for 1 day but deteriorated thereafter both in terms of percent neurons surviving and the amplitudes and densities of GABA-, glycine-, kainate- and NMDA-induced currents. Neurons grown in Tyrode's previously conditioned by astrocytes for 24 h had significantly larger apparent plasma membrane surface area, as indexed by whole-cell membrane capacitance, and larger amplitudes and densities of the amino acid-induced currents after both 1 and 2 days. The survival rate and neurite outgrowth were also greater in the astrocyte-conditioned saline group after 2 days in culture. Similarly, neurons cultured on glass cover-slips facing a confluent monolayer of astrocyte were larger in apparent plasma membrane area and amino acid-induced currents than neurons cultured in Tyrode's alone. Neurons cultured in saline conditioned by astrocytes provide a strategy to study the physiological basis of astrocyte-directed neuronal differentiation in the absence of ambiguities arising from the inclusion of sera and other additives often used in vitro.