On the origin of fiber calcite crystals in moonmilk deposits

In this study, we show that moonmilk subaerial speleothems in Altamira Cave (Spain) consist of a network of fiber calcite crystals and active microbial structures. In Altamira moonmilks, the study of the typology and distribution of fiber crystals, extracellular polymeric substances, and microorganisms allowed us to define the initial stages of fiber crystal formation in recent samples as well as the variations in the microstructural arrangement in more evolved stages. Thus, we have been able to show the existence of a relationship among the different types of fiber crystals and their origins. This allowed us to outline a model that illustrates the different stages of formation of the moonmilk, developed on different substrata, concluding that microbes influence physicochemical precipitation, resulting in a variety of fiber crystal morphologies and sizes.     

论环境意识的组成、结构与发展

环境意识是一种具有多维属性的社会意识,本文分别从环境意识的静态组成、深度层次、人群层次、时间属性和空间属性等5个方面探讨了环境意识的组成、结构和分类,揭示了环境意识的动态过程和发展特征,对环境意识的发展规律进行了理论概括.文章还阐述了在现代信息走向更加开放情况下环境意识的传播途径和环境教育的基本原则.     

专家畅谈地产节能

一、专家话题 　　话题一：住宅面积强调节约 　　董卫说,从中国现在的发展速度来看,2020年城市人口将达到全国人口的60%,而到国家发展的第三个战略步署即达到中等发达国家水平时,城市人口将占全国的75%以上.但是,与人口城市化的速度和人口增长的速度相比较,国内的人均资源占有将呈现逐步下降的趋势,所以,人均住宅面积一定要节约,要从中国的国情科学地定出一个合理的人均住宅面积.     

The growth of large diamond crystals

Large diamond crystals up to 6 mm in average diameter may be grown at high pressures (55–60 kbar) and temperatures (1400–1500 °C) by causing diamond to dissolve in a molten catalyst metal (Fe, Ni, Co, etc.) in a hot region and deposit upon a seed crystal in a slightly cooler region. Several days are required to produce a high quality single crystal. The process can be controlled to produce different kinds of diamonds whose properties have been studied.     

Squeezing light out of crystals: Triboluminescence

Triboluminescence is the light emitted when mechanical energy is applied to a crystal. Many common substances such as sugar and copper sulfate are triboluminescent. The origin of the light and the mechanical, chemical, and crystallographic requirements of the phenomenon are described in this paper.     

A laboratory study on the scavenging of SO2 by snow crystals

A laboratory experiment is described where the uptake of SO₂ by dendritic snow crystals was studied. In a first experimental series the uptake of SO₂ was investigated during the growth of the snow crystals from water vapor with and without the presence of H₂O₂ in the air. In a second series of experiments we studied the uptake of SO₂ by snow crystals which had completed their growth. The results of our experiments showed that under both conditions SO₂ became scavenged by snow crystals. The uptake of SO₂ was particularly pronounced during the growth of the snow crystals, and at temperatures close to 0°C where a quasi-liquid layer exists at the surface of ice. As expected, the SO₂ uptake becomes enhanced in the presence of H₂O₂. The present results are in qualitative agreement with previous studies involving bulk ice.