60,190 research outputs found

    Raman Spectroscopy of the Sampleite Group of Minerals

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    Raman and infrared spectroscopy has enabled insights into the molecular structure of the sampleite group of minerals. These minerals are based upon the incorporation of either phosphate or arsenate with chloride anion into the structure and as a consequence the spectra refect the bands attributable to these anions, namely phosphate or arsenate with chloride. The sampleite vibrational spectrum reflects the spectrum of the phosphate anion and consists of ν1 at 964, ν2 at 451 cm-1, ν3 at 1016 and 1088 and ν4 at 643, 604, 591 and 557 cm-1. The lavendulan spectrum consists of ν1 at 854, ν2 at 345 cm-1, ν3 at 878 cm-1 and ν4 at 545 cm-1. The Raman spectrum of lemanskiite is different from that of lavendulan consistent with a different structure. Low wavenumber bands at 227 and 210 cm-1 may be assigned to CuCl TO/LO optic vibrations. Raman spectroscopy identified the substitution of arsenate by phosphate in zdenekite and lavendulan

    Isomorphic Substitution in Vanadinite [Pb5(VO4)3C1] - Raman Spectroscopic Study

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    The Raman and infrared spectroscopy of three vanadinite [Pb5(VO4)Cl] specimens from three localities has been studied. Single crystal Raman spectra were obtained and the spectra were found to be both orientation and temperature dependent. Measurement of the Raman spectra at liquid nitrogen temperature enabled better band separation and increased intensities of weak bands through band narrowing enabling, the assignment of the bands in vanadinites to be made. Two types of isomorphous substitution are identified (a) substitution in the bulk of the crystal where electron beam microanalysis identifies the presence of calcium and copper. (b) surface substitution where infrared spectroscopy shows the isomorphous substitution of vanadate by phosphate and of chloride by hydroxyl groups

    Count me in! Gender and ethnic minority attainment in school science

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    There is no single 'solution' to the 'problem' of under-achievement in school science by certain groups. Such under-achievement is strongly connected to the ways that society views the members of these groups. It is not enough for schools to be isolated islands of good practice; they need to help students critically reflect on the world inside and outside of school, and then equip students with the necessary tools to deal with this world. A number of strategies are suggested for use in schools to help pupils and students from groups which often underachieve to get more from their science lessons

    Vibrational Spectroscopy of Selected Natural Uranyl Vanadates

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    Raman spectroscopy has been used to study a selection of uranyl vanadate minerals including carnotite, curienite, francevillite, tyuyamunite and metatyuyamunite. The minerals are characterised by an intense band in the 800 to 824 cm-1 region, assigned to the ν1 symmetric stretching vibrations of the (UO2)2+ units. A second intense band is observed in the 965 to 985 cm-1 range and is attributed to the ν1 (VO3) symmetric stretching vibrations in the (V2O8) units. This band is split with a second component observed at around 963 cm-1. A band of very low intensity is observed around 948 cm-1 and is assigned to the ν3 antisymmetric stretching vibrations of the (VO3) units. Bands in the range 608-655 cm-1 may be attributed to molecular water librational modes or the stretching modes ○(V2O2) units. Bands in the range 573-583 cm-1 may be connected with the ○ (U-Oequatorial) vibrations or ○ (V2O2) units. Bands located in the range 467-539 cm-1 may be also attributed to the ○ (U-Oequatorial) units vibrations. The bending modes of the (VO3) units are observed in the 463 to 480 cm-1 range – there may be some coincidence with ○ (U-Oequatorial). The bending modes of the (V2O2) in the (V2O8) units are located in a series of bands around 407, 365 and 347 cm-1 (ν2). Two intense bands are observed in the 304 to 312 cm-1 range and 241 to 264 cm-1 range and are assigned to the doubly degenerate ν2 modes of the (UO2)2+ units. The study of the vibrational spectroscopy of uranyl vanadates is complicated by the overlap of bands from the (VO3) and (UO2)2+ units. Raman spectroscopy has proven most useful in assigning bands to these two units since Raman bands are sharp and well separated as compared with infrared bands. The uranyl vanadate minerals are often found as crystals on a host matrix and Raman spectroscopy enables their in-situ characterisation without sample preparation

    Organic Farming at ADAS PwllPeiran 1993 - 2001

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    Agriculture at Pwllpeiran has a long history. Pwllpeiran was eventually established as an Experimental Husbandry Farm in 1955. During the following forty years, work at the farm achieved substantial improvements in the quality and quantity of lamb and beef produced, but by the turn of the millennium the emphasis of agricultural policy was turning away from increased livestock production per se and towards the development of environmentally sensitive farming systems. The 1,118 ha Pwllpeiran Research Farm is now managed by ADAS Wales. The land is rented from the National Assembly for Wales and the Forestry Commission. All of the land is under a ‘whole farm’ Environmentally Sensitive Area agreement. The results from the Pwllpeiran unit underline the difficulties of organic farming in a severely disadvantaged upland area. The unit’s performance demonstrates the potential for production of organic lamb and beef but it also indicates some of the limitations on organic production. Organic farming theory and practice developed primarily in the lowlands and on mixed farms and these origins remain clearly evident in current standards for organic agriculture. Farming in the hills and uplands is, however, in many ways distinct. The lack of opportunity to grow arable crops, the difficulties of growing legumes such as clover and the shortages of farmyard manure, organic fertilisers and farm produced feed all represent particular challenges to the organic hill farm. At Pwllpeiran, production has been constrained by declining soil fertility which in turn has had an adverse effect on grass / clover production and thus on herbage availability and forage conservation. The system operated to date has not produced enough FYM to maintain soil nutrient levels in all of the organic pastures, a major constraint on the level of production. This leads to two important conclusions regarding organic farming in the uplands. The first is the importance of regular and systematic soil sampling to identify possible nutrient deficiencies. The second is the need for sector bodies to recognise that organic farming in severely disadvantaged high rainfall hill areas may require more regular input of permitted P and K fertilisers than lowland and mixed farms. Without such inputs production levels are likely to fall in the medium to long-term and more work needs to done on the best method of supplying these nutrients to the organic hill farm. At Pwllpeiran the decision was taken to accept a lower stocking rate on the organic unit, and to maintain financial performance by generating extra income from ESA agri environment payments and organic premiums. The unit’s experience demonstrates that combining organic farming with environmental conservation schemes on the mountain farm may add to the unit’s income, but environmental prescriptions will also place further limits on production. The balance of advantages to the organic hill farm offered by entry into an environmental management scheme needs to be weighed carefully. The future viability of the Pwllpeiran organic unit depends on maintaining farm income levels by optimising herbage and forage production and utilisation, and by controlling input costs, and producing quality beef and lamb. The impact of other factors like market prices, global trade and government policy will prove equally important. Control of these lies beyond the farm gate

    UTSI atmospheric science program

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    Two areas of research were carried out concerned with meteorological and environmental inputs to aviation systems. One effort dealt with the investigation of wind fields about bluff geometries typical of buildings or other man made obstructions to the surface wind and the behavior of craft flying through these disturbed wind fields. The second effort was the definition and mathematical models of atmospheric wind shear associated with thunderstorms, stable boundary layers, and synoptic fronts. These mathematical models can be utilized in flight simulators to train pilots and flight crews and to develop instrumentation for landing in adverse wind shear conditions

    Meteorological and environmental inputs to aviation systems: Opening remarks

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    Opening remarks for the workshop are given. A description of the workshop and a schedule of the committee meetings are presented. Tables of suggested questions for discussion and lists of the individual participants for the various committees are also presented

    Like A House Vowing To Say Its Good Nights

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