Discovery of especially large bubble-like miarolitic granites in Laoshan and its geological and geomorphic significance
Recently, some especially large bubble-like miarolitic caves in A-type granites in Laoshan have been discovered with the largest diameter of up to 3.1 m, far exceeding the granitic miarolitic caves previously reported, thus adding new knowledge to geology. This helps to study the primary environment for granites formed in Laoshan and also reveal genesis of “natural-mortar” micro-landform for granites in Laoshan. The existence of a new genesis type—“bubble-like miarolitic caves” of speleology is also confirmed by this discovery. Especially large bubble-like miarolitic caves are rare geological relics with high ornamental, science and tourism value.
A DISCUSSION ON THE ORIGIN OF MOULINS IN SOUTH CHINA(2)
The discovery of a host of glacial drifts, stratified pebbles and deformation gravel in the moulin groups area in South China once again provides strong evidence for the conclusion that the moulins are not a pot holes. The landform of “rock block fields”, which was formed after glacial erratic boulders were subjected to freeze thaw action (physical weathering), is completely different from the granitic pebbly landform,resulting from chemical weathering, thus these two cases cannot be confused. Concave flood plains are composed of river alluvia. Such plains and bedrock ice sills should not be mentioned in the same breath. Joints and structure give influence only on the form and development degree, but not on development position of the moulin. This means that truth and falsehood should not be confused. A great number of traces of former glaciers have been discovered in South China. This proves that a large scale glacial movement did take place in the early Quaternary ( ca.2-3 Ma B P.). Thus the debate on the question, whether Quaternary glaciers existed in mountainous areas with medium or low elevations in East and South China, which has been continuing for more than half a century, can be finished with success.
A Critical Assessment on Functional Attributes and Degradation Mechanism of Membrane Electrode Assembly Components in Direct Methanol Fuel Cells
Direct methanol fuel cells (DMFC) are typically a subset of polymer electrolyte membrane fuel cells (PEMFC) that possess benefits such as fuel flexibility, reduction in plant balance, and benign operation. Due to their benefits, DMFCs could play a substantial role in the future, specifically in replacing Li-ion batteries for portable and military applications. However, the critical concern with DMFCs is the degradation and inadequate reliability that affect the overall value chain and can potentially impede the commercialization of DMFCs. As a consequence, a reliability assessment can provide more insight into a DMFC component’s attributes. The membrane electrode assembly (MEA) is the integral component of the DMFC stack. A comprehensive understanding of its functional attributes and degradation mechanism plays a significant role in its commercialization. The methanol crossover through the membrane, carbon monoxide poisoning, high anode polarization by methanol oxidation, and operating parameters such as temperature, humidity, and others are significant contributions to MEA degradation. In addition, inadequate reliability of the MEA impacts the failure mechanism of DMFC, resulting in poor efficiency. Consequently, this paper provides a comprehensive assessment of several factors leading to the MEA degradation mechanism in order to develop a holistic understanding.