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231.
Viroj Wiwanitkit Amornpun Sereemaspun Rojrit Rojanathanes 《Stochastic Environmental Research and Risk Assessment (SERRA)》2008,22(4):583-585
In medicine, there is limited knowledge on the toxicity of nanoparticles. In reproductive medicine, there has been limited
knowledge on the effect of gold nanoparticle on the human red blood cell. In this work, the author performed a study to demonstrate
if gold nanoparticle can be detected inside red blood cell on microscopic test. Chulalongkorn Univesity, Bangkok Thailand.
This study was performed as an experimental study. Mixture of gold nanoparticle solution and blood sample was prepared and
further analyzed. According to this work, accumulation of gold nanoparticle in the red blood cell can be observed after mixing
the blood sample with gold nanoparticle solution. However, no significant destruction of the red cell can be seen. The effect
of gold nanoparticle on red blood cell can be detected and the implication for the possible chronic toxicity of the accumulated
gold nanoparticle in red cell is raised.
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Viroj WiwanitkitEmail: |
232.
Gold Mineralization in Kottathara Prospect, Attappadi Valley, Kerala, India: a Preliminary Appraisal
The Kottathara gold prospect of Attappadi Valley in Kerala is located within the Southern Indian Granulite Terrain comprising charnockite and gneisses with enclaves of high-grade supracrustals. The gold mineralization associated with the basic members of the Attappadi supracrustals and the quartz veins traversing them are confined within the Bhavani Shear Zone. Primarily the gold-quartz lode is emplaced in rheologically preferred zones along the contact of the basic members with the enclosing gneisses subsequent to a period of retrogression and shearing. Ore-mineralogical studies reveal that gold got remobilized and this remobilization is identified with the regional Bhavani Shear. SEM studies indicate that gold occurs in free state and also within sulphides especially pyrite. Variation in grain morphology is clearly discernible in gold occurring within oxidised and in non-oxidised zones.Sequencing of deformational events with associated emplacements of known ages suggests the age of gold mineralization of Attappadi area as between 2 Ga. and 2.5 Ga. The secondary mobilization has to be <2.0 Ga or younger possibly of younger Pan-African age related with the Moyar-Bhavani Shear System. The inherent gold content of the komatiitic metapyroxenites together with the auriferous quartz lodes assigns a lithological control on gold mineralisation. Subsequent folding and remobilization due to the regional shear constrained the geometry of the lode zones implying structural control. 相似文献
233.
由于自然界中Au元素呈微粒状、不均匀状态分布,致使部分金矿床(点)没有与之对应的Au元素异常出现,增加了通过元素异常开展地质找矿和成矿预测研究的难度。本文依据地学大数据"查明数据间的相关关系,解决地质问题"这一基本思路,以甘肃玉石山地区化探数据为研究对象,建立起研究区全样本Au元素回归模拟模型和异常样本Au元素回归模拟模型,分别计算全样本Au元素回归理论值(Au Q)和异常样本的回归理论值(Au Y)。通过异常查证,在Au Q异常区发现金矿点1处,在Au Y异常区发现金矿点3处(一处达到小型规模),取得了很好的找矿效果。进一步对Au、Au Q、Au Y分别做正规化处理相加获得综合理论值(Au H),以Au H圈定的综合异常使研究区75%金矿床(点)分布在研究区7. 1%面积范围内,有效地缩小了找矿靶区的范围,解决了小范围研究区内因已知矿床(点)不足而无法开展定量找矿预测的难题。结合异常强度和地质背景分析,在研究区划分出3级共10个找矿靶区,为今后在该区找矿工作提供了基础依据。 相似文献
234.
Gavin Hilson 《Geoforum》2008,39(1):386-400
This paper critically examines the challenges with, and impacts of, adopting the models in place for fair trade agriculture in the artisanal gold mining sector. Over the past two years, an NGO-led ‘fair trade gold’ movement has surfaced, its crystallization fuelled by a burgeoning body of evidence that points to impoverished artisanal miners in developing countries receiving low payments for their gold, as well as working in hazardous and unsanitary conditions. Proponents of fair trade gold contest that increased interaction between artisanal miners and Western jewellers could facilitate the former receiving fairer prices for gold, accessing support services, and ultimately, improving their quality of life. In the case of sub-Saharan Africa, however, the gold being mined on an artisanal scale does not supply Western retailers as perhaps believed; it is rather an important source of foreign exchange, which host governments employ buyers to collect for their coffers. It is maintained here that if the underlying purpose of fair trade is to improve the livelihoods and well-being of subsistence producers in developing countries, then the models that have proved so successful in alleviating the hardships of agro-producers of ‘tropical’ commodities such as coffee, tea, bananas and cocoa, should be adapted to artisanal gold mining in sub-Saharan Africa. Campaigns promoting ‘fair trade gold’ in the region should view host governments, and not Western retailers, as the ‘end consumer’, and focus on improving governance at the grassroots, organizing informal operators into working cooperatives, and addressing complications with purchasing arrangements - all of which would go a long way toward improving the livelihoods of subsistence artisanal miners. A case study of Noyem, Ghana, the location of a sprawling illegal gold mining community, is presented, which magnifies these challenges further and provides perspective on how they can be overcome. 相似文献
235.
236.
内蒙古安家营子金矿与侵入岩的关系及其地球动力学意义 总被引:5,自引:1,他引:5
位于华北陆块北缘金矿成矿带的安家营子中型金矿属赤峰-朝阳金矿化集中区。金矿体主要赋存于安家营子花岗岩岩体内。区内广泛分布着与金矿化相伴生的流纹斑岩脉。与金矿化密切相关的安家营子花岗岩具有轻稀土富集、重稀土亏损、较低的^87Sr/^86Sr初始比值、Ba—Sr含量高等特点,暗示该花岗岩浆形成深度较大。这些特点与我国胶东地区与金矿有关花岗岩的特征非常相似,但区别于较早期的喀喇沁花岗岩和成矿后的流纹斑岩脉。锆石U—Pb年龄表明,安家营子花岗岩侵位时代为132—138Ma,而穿切矿体的流纹斑岩岩脉的成岩时代为124.9—126,5Ma,进而金矿成矿时代可以限定在126.132Ma。这一年龄结果与华北克拉通中生代动力学体制发生转折的时间相吻合。研究表明,早中生代前后华北东部曾发生了动力学机制的重大转折,如挤压向伸展转变和岩石圈的减薄达到高峰导致岩浆作用增强等。华北克拉通绝大多数金矿床集中形成于这一转折时期暗示成矿作用可能与深部作用过程有关,即早白垩世地慢物质-能量强烈上涌的同时,使金等威矿元素活化迁移至地壳层次,并在有利的构造部位富集成矿。 相似文献
237.
Forecasting seasonal to multi-year shoreline change 总被引:1,自引:0,他引:1
This contribution details a simple empirical model for forecasting shoreline positions at seasonal to interannual time-scales. The one-dimensional (1-D) model is a simplification of a 2-D behavioural-template model proposed by Davidson and Turner (2009). The new model is calibrated and tested using five-years of weekly video-derived shoreline data from the Gold Coast, Australia. The modelling approach first utilises a least-squares methodology to calibrate the empirical model coefficients using the first half of the dataset of observed shoreline movement in response to known forcing by waves. The model is then verified by comparison of hindcast shoreline positions to the second half of the observed shoreline dataset. One thousand synthetic time-series of wave height and period are generated that encapsulate the statistical characteristics of the modelled wave field, retaining the observed seasonal variability and sequencing characteristics. The calibrated model is used in conjunction with the simulated wave time-series to perform Monte Carlo forecasting of the resulting shoreline positions. The ensemble-mean of the 1000 individual five-year shoreline simulations is compared to the unseen shoreline time-series. A simple linear trend forecast of the shoreline position was used as a baseline for assessing the performance of the model. The model performance relative to this baseline prediction was quantified by several objective methods, including cross-correlation (r), root mean square (RMS) error analysis and Brier Skill tests. Importantly, these tests involved no prior knowledge of either the wave forcing or shoreline response. The new forecast model was found to significantly improve shoreline predictions relative to the simple linear trend model, capturing well both the trend and seasonal shoreline variabilities observed at this site. Brier Skill Scores (BSS) indicate that the model forecasts based on unseen data were rated as ‘excellent’ (BSS = 0.83), and root mean square errors were less than 7 m (≈ 14% of the observed variability). The standard deviations of the 1000 individual simulations from ensemble-averaged ‘mean’ forecast were found to provide a useful means of predicting the higher-frequency (individual storm) shoreline variability, with 98% of the observed shoreline data falling within two standard deviations of the forecast position. 相似文献
238.
239.
以四川西部高原地质环境脆弱为据,提出了“南水北调”西线工程应引以重视的地质环境问题,并以科学发展观提出了对策。 相似文献
240.
The Dawson Cut Forest Bed lies in the lower part of thick, late Cenozoic loess deposits in the Fairbanks area. It is associated with several distal tephra beds that provide age control and offer the opportunity of its recognition elsewhere in central Alaska. EC tephra (named herein) occurs in the uppermost part of the Dawson Cut Forest Bed and its petrographic and chemical properties point to a co-magmatic relationship with PA tephra, which has not been found in direct association with the forest bed. Both tephra beds are pink and have unusually high Cl in their glass shards, which readily separates them from all other tephra beds in the Fairbanks area. They were produced by discrete eruptions, closely spaced in time. PA tephra has a glass-fission-track age of 2.02 ± 0.14 myr, indicating that the Dawson Cut Forest Bed must be about 2 million years old. The Palisades tephra (named herein) has very similar properties to these two tephra beds, suggesting that the buried forest bed just above it at the Palisades site on the Yukon River, about 250 km west of Fairbanks, correlates with the Dawson Cut Forest Bed. 相似文献