An Experimental Investigation of the Impact of Gas Phase Prepolymerization of Propylene

A systematic investigation is carried out on the gas phase of propylene during the initial instants of polymerization. The results confirm the positive impact of small amounts of mineral oil on the initial reaction rate and morphology. It is shown that polymerizing under conditions of mild temperature and pressure alone are not enough to achieve the same result. It is found that the presence of mineral oil, and low temperature of polymerization can be used to control the morphology of polymer particles and to obtain high activity in the main reaction. If enough oil is used, moderate to high temperatures of prepolymerization are acceptable in terms of controlling morphology but can compromise the activity of the main polymerization. It is also observed that the way in which the oil is introduced has an impact on the kinetics and particle morphology. Separate addition of oil from the precatalyst gives rise to relatively flat kinetics during prepolymerization and highest rate during main polymerization. To account for the activity enhancement, a selective quench‐labeling study employing methyl propargyl ether shows that the presence of mineral oil appears to increase the fraction of active titanium by a factor of almost 2.     

The design of colliery information and control systems

The paper is concerned with describing an investigation of information usage in the control of colliery operations. The premise of the work is that to make the most of new information retrieval technology currently being installed in collieries research in needed to provide compatible advances in methods of information usage. The approach adopted was to construct a continuous simulation model using system dynamics capable of providing a laboratory assessment of alternative managerial control policies based on alternative sources and levels of aggregation of information.The model developed represents a typical colliery situation composed of three working coal-faces and incorporating planning, production, development and manpower sectors. The face sectors transform coal reserves to mined coal output, under manpower constraints and geological shocks, and these are all interlinked by means of allocation policies for manpower and machine shifts.A range of policies for the exercise of control through these allocations are considered subject to a range of shocks. It is concluded that, although there are difficulties in designing single policies which are universally best, there are clear advantages associated with fully integrated colliery policies based on information inputs from all aspects of the operations.     

Fluorescence spectroscopy of polynuclear aromatic compounds in environmental monitoring

The occurrence of polynuclear aromatic compounds (PAC) in the environment and experimental techniques suitable for the detection of PAC in environmental compartments are briefly reviewed. The specific requirements for on-site andin situ environmental analysis are outlined. Particular emphasis is given to fluorescence spectroscopic techniques for the investigation of humic acid- and soil-containing samples. Some examples of studies in the literature on Shpol'skii and jet spectroscopy and on laser-induced fluorescence (OF) measurements of PAC and mineral oils are highlighted. Contaminants in the environment are usually encountered as multicomponent mixtures in very complex matrices. Total fluorescence analysis in combination with the chemometrical technique of rank annihilation factor analysis (RAFA) was employed for the evaluation of a six-component PAC mixture in toluene. It was shown that even in the presence of strong spectral overlap the qualitative identification of all compounds and the reliable quantification of five substances was possible. Results are presented from our stationary and time-resolved fluorescence investigations of the interactions between pyrene and humic acid in water. The Stern-Volmer analysis showed a significant effect of pH on the static quenching efficiency which can be explained by the pH-dependent macromolecular structure of humic acids. Preliminary results from studies of the deactivation of triplet PAC and quenching of delayed fluorescence by humic acid are reported. LIF measurements of mineral oils directly from soil surfaces and of a model oil in a soil column were performed with a fiber-optic coupled multichannel spectrometer. The fluorescence intensity/ concentration relationships were established for a crude and a fuel oil; the corresponding lower limits of detection (LOD) were determined to be 0.025 and 0.125% m/m (mass/mass percentages). These detection limits are compared with realistic oil contaminations of soils. In a soil column designed to mimic fixed-bed bioreactors the distributions of fluorescence signal intensities from a perylene-doped model oil before and after water flooding were determined. These results fromin situ measurements can provide a quantitative basis for the modelling of temporal and spatial contaminants' distributions in reactor design.     

The effect of bone structure on ultrasonic attenuation and velocity

The relationship between the structure of bovine cancellous bone, and its ultrasonic propagation parameters is investigated by means of a novel technique involving the application of large static loads, thereby changing the porosity in a controlled manner. The results show that for frequencies in the range 0.4 to 1 MHz, porosity decreases up to 35% are associated with a reduction in attenuation of up to 500%, whereas the velocity increases by roughly 35% for the same changes. The data taken overall suggest that in determining the ultrasonic attenuation coefficient at these frequencies, the amount of material in a given bone section is significantly less important than the distribution of that material.     

Domain Structures in Minerals

Domain structures in mineral crystals could be categorized into three groups and several subgroups within each group, based on characteristics of domain structures and mechanisms causing domain structures: (ⅰ) domain structures constituted by domains with the same (or identical) crystal structure and chemical composition, including anti-phase domain structures, twinning domain structures, inversion domain structures, and translationtwinning domain structures; (ⅱ) domain structures constituted by two or more than two kinds of domains with the same chemical composition but different crystal structures; and (ⅲ) domain structures constituted by two kinds of compositional and structural different domains, including exsolution-induced and polysomatic reaction-induced domain structures. Different types of domain structures may display different phenomena in their TEM images and SAED patterns, due to different crystallographic characteristics of different domain structures. The domain structures in minerals     

五华汤湖矿泉中9种微量元素的测定

采用火焰原子吸收分光光度法对五华汤湖矿泉中Na、Mg、Fe、Zn、K、Ca、Pb、Se、As 9种微量元素进行了检测与分析。结果表明，该矿泉中含有丰富的微量元素。为探讨矿泉对人体的保健作用提供了有用的依据。     

种植青海大黄叶中矿物质元素研究

青海地道中药材“西宁大黄”，野生资源濒临枯竭，人工种植规模不断扩大。定期采集了青海西宁及邻近地区两年生种植大黄叶，分析测试了其矿物质元素，为西宁大黄资源的可持续开发和利用提供科学依据。研究表明，种植大黄叶中矿物质营养元素的协同性以及有效蓄积对大黄的生长具有重要意义。钠元素在大黄叶中的有效蓄积以及环境中水分的及时补给对种植大黄的生长具有重要作用。     

Characterization of biochemical traits of dog rose (Rosa canina L.) ecotypes in the central part of Iran

Dog rose (Rosa canina L.) is a wild native species in Iran, with a significant genetic diversity. This plant serves as a rich source of vitamin C, anthocyanins, phenolic contents and carotenoids. Rose hips have been used in several food products, as well as perfumery and cosmetics industries. In this research, we investigate biochemical characteristics of five dog rose ecotypes (Kopehjamshid, Zarneh, Miyankish, Aghcheh and Sadeghiyeh), that were collected from the central part of Iran (Isfahan province). Amounts of vitamin C, total carotenoids, total phenolic contents, total anthocyanins, macro and micro minerals were measured. Seed oil are extracted by soxhlet method and analysed by gas chromatography. The macro and micro minerals levels in the fruit vary significantly among these regions. The results of this study demonstrate that dog rose have great diversity and can be used in breeding programmes in order to increase nutrient values as a food resource additive.