Hydrogeochemical Characteristics and Formation Mechanisms of the Geothermal Water in the Qingdong Coal Mine,Northern Anhui Province,China

Mine Water and the Environment - The hydrogeochemistry of geothermal fluids provides insight into the occurrence, formation, and circulation of geothermal resources. We collected 13 geothermal...     

Canadian Field Soils I. Mineral Composition by XRD/XRF Measurements

Forty Canadian soils were laboratory tested for the presence of quartz and other minerals using X-ray diffraction/X-ray fluorescence techniques. On average, the highest quartz content was observed in soil samples from sites in Nova Scotia followed by Prince Edward Island sites, whereas soil sample from British Columbia sites had the lowest quartz content. The second most abundant mineral was albite that mainly occurred in soil samples from Ontario and Quebec sites. Illite was the third most abundant and prevailed in soils mainly from British Columbia and New Brunswick sites. Soil samples from British Columbia sites had the highest combined clay and silt content and were composed of illite, albite, kaolinite, and chlorite. The lowest clay content was found in the samples from the Quebec sites. The highest microcline (a potassium feldspar) content was observed in Quebec, Ontario, and Prince Edward Island sites. In contrast to other provinces, samples from Quebec and Ontario sites also included amphibole. Soil samples from Saskatchewan and Manitoba sites also comprised carbonates, i.e., calcite and dolomite. Iron oxides (e.g., goethite) were present in all soils, except the Quebec sites, but their occurrence was rather insignificant.     

Molecular attributes of an effective steric agent: Yield stress of dispersions in the presence of pure enantiomeric and racemate malic acids

The effects of pH on the yield stress and zeta potential behaviour of α-Al₂O₃ dispersions with addition of d-, l- and racemate (DL) malic acids were evaluated. Conformational structures and intramolecular hydrogen bonding of the adsorbed malic acids obtained via MM2 modeling were used to explain the surface forces operating in the dispersions. We found that the yield stress-pH behaviour is almost identical for d-, l- and racemate malic acids. At low surface coverage of adsorbed malic acid, the maximum yield stress was reduced by as much as 55%. At complete surface coverage the reduction decreased to ～40%. MM2 modeling showed the presence of intramolecular hydrogen bonding between the hydroxyl and the (free) charged carboxylate group within the malic acid molecule. Intra-molecular hydrogen bonding and the high number of strongly bound water molecules (hydration number of malic di-ionic species) were likely responsible for the di-ionic malic acid species acting as a very effective steric agent. At complete surface coverage, the inter-molecular hydrogen bond formed between the layers of adsorbed malic acid, is responsible for the small rise in the maximum yield stress. Racemate malic acid produced a smaller maximum yield stress at complete surface coverage compared to the pure enantiomers. This may be related to the two different types of hydrogen bonds found in the racemate. Only one type is found in the pure enantiomers.     

澳门园林建筑与装饰小品特色研究

澳门是亚洲典型的东西方文化交汇的城市,特殊的发展背景使澳]园林呈现出明显的中西合璧的特点.澳门的城市园林大多小巧精致,园林建筑与装饰小品的风格受葡萄牙建筑与园林风格的影响较大,具有鲜明的南洋风格,即融合了本地民居建筑、南欧葡式建筑和中国传统建筑的特色.其整体形象简洁大方,中西园林建筑形式兼容并蓄,细部装饰精致,色彩鲜艳明亮.对澳门园林建筑与装饰小品特色的研究,有助于澳门 世界文化遗产的传承和国际旅游观光业的发展.     

<供热工程制图标准>及其编制原则

概要介绍了该标准的概貌、编制背景,举例说明了标准的编制原则,为了解和正确执行该标准提供了帮助。     

Exploratory analysis of brain connectivity with ICA.

Covariance-based methods of exploration of functional connectivity of the brain from functional magnetic resonance imaging (fMRI) experiments, such as principal component analysis (PCA) and structural equation modeling (SEM), require a priori knowledge such as an anatomical model to infer functional connectivity. In this research, a hybrid method, combining independent component analysis (ICA) and SEM, which is capable of deriving functional connectivity in an exploratory manner without the need of a prior model is introduced. The spatial ICA (SICA) derives independent neural systems or sources involved in task-related brain activation, while an automated method based on the SEM finds the structure of the connectivity among the elements in independent neural systems. Unlike second-order approaches used in earlier studies, the task-related neural systems derived from the ICA provide brain connectivity in the complete statistical sense. The use and efficacy of this approach is illustrated on two fMRI datasets obtained from a visual task and a language reading task.     

Inter‐particle contact heat transfer model: an extension to soils at elevated temperatures

A simple ‘inter‐particle contact heat transfer’ model for predicting effective thermal conductivity of soils at moderate temperatures (0–30°C) has been extended up to 90°C. The extended model accounts for latent heat transport by water vapour diffusion in soil air above the permanent wilting point; below that point, the soil thermal conductivity is approximated by linear interpolation without latent heat effect. By and large the best results are obtained when the latent heat is used only in the ‘self consistent approximation’ model with an overall root mean square error of 35% for all soils under consideration or 26% when excluding volcanic soils. This option can also be applied to moderate temperatures at which the enhanced heat transfer is negligibly small. Copyright © 2005 John Wiley & Sons, Ltd.     

Pressure electrical contact improved by carbon black paste

Pressure and pressureless electrical contacts were evaluated by measuring the contact electrical resistivity between copper mating surfaces. Pressure electrical contacts with a contact resistivity of 2×10⁻⁵ Ω·cm² have been attained using a carbon black paste of a thickness of less than 25 μm as the interface material. In contrast, a pressureless contact with silver paint as the interface material exhibits a higher resistivity of 3×10⁻⁵ Ω·cm² or above. A pressureless contact with colloidal graphite as the interface material exhibits the same high contact resistivity (1×10⁻⁴ Ω·cm²) as a pressure contact without any interface material. On the other hand, pressureless contacts involving solder and silver epoxy exhibit lower contact resistivity than carbon black pressure contacts.     

Detailed analysis of high‐quality symmetrical octagonal spiral inductors on Si substrate

Research studies of symmetrical spiral inductors for silicon technology have become very important and challenging. In this article, we attempt to give a detailed explanation of how symmetrical spiral inductors help to improve the quality factor (Q) as compared to conventional nonsymmetrical inductors. The experimental results are presented to verify our theory. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005.