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INTRODUCTION The properties of phosphor usedin a plasma dis-play panel (PDP) affect the performance of the PDP(Okazaki et al .,2000 ; Rao and Devine ,2000) . Theluminescent properties of the phosphor are decided bythe morphology ,particle size and size distribution ofthe powder ,sothe requirements for the powder mor-phology are high in a color PDP which belongs to ahigh resolution display apparatus (I m et al .,2005 ;Yang et al ., 2005) . Studies have shown that withsmall particle si… 相似文献
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Dane R. Spearing Ian Farnan Jonathan F. Stebbins 《Physics and Chemistry of Minerals》1992,19(5):307-321
Relaxation times (T1) and lineshapes were examined as a function of temperature through the - transition for 29Si in a single crystal of amethyst, and for 29Si and 17O in cristobalite powders. For single crystal quartz, the three 29Si peaks observed at room temperature, representing each of the three differently oriented SiO4 tetrahedra in the unit cell, coalesce with increasing temperature such that at the - transition only one peak is observed. 29Si T1's decrease with increasing temperature up to the transition, above which they remain constant. Although these results are not uniquely interpretable, hopping between the Dauphiné twin related configurations, 1 and 2, may be the fluctuations responsible for both effects. This exchange becomes observable up to 150° C below the transition, and persists above the transition, resulting in -quartz being a time and space average of 1 and 2. 29Si T1's for isotopically enriched powdered cristobalite show much the same behavior as observed for quartz. In addition, 17O T1's decrease slowly up to the - transition at which point there is an abrupt 1.5 order of magnitude drop. Fitting of static powder 17O spectra for cristobalite gives an asymmetry parameter () of 0.125 at room T, which decreases to <0.040 at=" the=" transition=" temperature.=" the=" electric=" field=" gradient=" (efg)=" and=" chemical=" shift=" anisotropy=" (csa),=" however,=" remain=" the=" same,=" suggesting=" that=" the=" decrease=" in="> is caused by a dynamical rotation of the tetrahedra below the transition. Thus, the mechanisms of the - phase transitions in quartz and cristobalite are similar: there appears to be some fluctuation of the tetrahedra between twin-related orientations below the transition temperature, and the -phase is characterized by a dynamical average of the twin domains on a unit cell scale. 相似文献
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Dolgikh A. V. Matskovsky V. V. Voronin K. V. Solomina O. N. 《Doklady Earth Sciences》2017,474(2):706-708
The results of dendrochronological and radiocarbon dating by means of accelerator mass spectrometry (AMS) of six medieval icons, originating from northern European Russia and painted on wooden panels made from Scots pine, dated to the 15th to 17th centuries are presented. The panels of each icon were studied using dendrochronology. Five to six AMS dates were obtained for four icons. Although five icons were dendro-dated successfully, one failed to be reliably cross-dated with the existing master tree-ring chronologies and it was dated by radiocarbon wiggle-matching. Dendrochronological dating and wiggle-matching of radiocarbon dates allowed us to determine the narrow chronological intervals of icon creation.
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Z. H. Zhang Y. J. Feng P. Gao J. F. Liu N. Q. Ren 《International Journal of Environmental Science and Technology》2012,9(2):247-256
The adsorption and desorption behaviors of 17??-ethinylestradiol on various sludges derived from different treatment units of a sewage treatment plant were investigated using batch equilibration experiments. The results showed that adsorption process could be well described by pseudo-second-order kinetic model and fast adsorption played a main role. Adsorption ability varied as the order of aerobic sludge????anoxic sludge????primary sludge?>?sludge cake?>?anaerobic sludge. Adsorption/desorption isotherms were well fitted by the modified Freundlich model, and $ K_{f}^{\prime } $ values increased with the organic matter content. Thermodynamic analysis indicated that 17??-ethinylestradiol adsorption/desorption was exothermic and conducted spontaneously. After heat treatment for removing the organic carbon, $ K_{f}^{\prime } $ values decreased by more than 78%, but organic carbon normalized adsorption constant was 7.76?C29.51?mg/g. The 17??-ethinylestradiol adsorption capacity was found to decrease from 0.95?C1.39 to 0.44?C0.49?mg/g with sludge concentration increasing from 500 to 4,000?mg/L, being almost unchanged at pH 3?C10 and sharply decreasing with pH?>?10. The adsorption capacity was also found to fluctuate in the range of 2.0?C3.0?mg/g when Ca2+ concentration was <0.5?mol/L and increased rapidly above 0.5?mol/L. Addition of methanol and acetonitrile could improve 17??-ethinylestradiol desorption effect, which increased with the content of organic solvents, and the desorption degree of acetonitrile was higher than methanol. 相似文献
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Gablina I. F. Dobretsova I. G. Popova E. A. Dara O. M. Sadchikova T. A. Gor’kova N. V. Mikheev V. V. 《Lithology and Mineral Resources》2021,56(2):113-131
Lithology and Mineral Resources - The paper presents the mineral and chemical compositions of carbonate, metalliferous, and ore-bearing sediments developed within the Pobeda ore cluster based on... 相似文献
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《International Geology Review》2012,54(14):1691-1719
This study investigates the formation of lower oceanic crust and geochemical variations of basalts along the Central Indian Ridge (CIR, lat. 7°45′–17°10′ S). Harzburgites, various gabbroic cumulates, medium- to fine-grained oxide gabbros, diabases, and pillow basalts were recovered by dredging from segment ends such as ridge-transform intersections (RTIs), non-transform discontinuities (NTDs), and transform offset areas. The occurrence of both harzburgites and gabbroic rocks with minor basalts at all segments ends, and leucogabbro intrusive into harzburgite at the 12°45′ S NTD indicates that oceanic crust at segment ends exposes mantle-derived harzburgites and gabbroic intrusions with a thin basaltic cover due to sparse magmatic activity. Basalts collected along the entire ridge show wide compositional variations between N (normal)- and E (enriched)-mid-ocean ridge basalt (MORB). T (transitional)-MORBs with enriched affinities are more prominent than N-MORBs. There is no tendency of enrichment towards specific directions. (La/Sm)N variations in MORB along the CIR (8°–21°S) fluctuates at a regional scale with local high positive anomalies reflecting compositional heterogeneity of the sub-CIR mantle domain. 相似文献
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四年一度的国际矿物学大会于１９９８年８月９～１４日在加拿大多伦多大学召开,中国出席大会的有谢先德院士,黄蕴慧、何自立、李光麟、於祖相、宋学信等著名学者及青年科学家曹志敏等１８人。作为世纪之交的国际矿物学大会共设３个研讨会（ｓｙｍｐｏｓｉｕｍ）,２４个... 相似文献
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A case study for the ion–aerosol interactions is presented from the simultaneous measurements of mobility spectra of atmospheric
ions in the mobility range of 2.29 to 2.98 × 10 − 4 cm2 V − 1 s-1^{-1}(diameter range 0.41–109 nm) and of size distribution of atmospheric aerosol particles in the size ranges of 4.4–700 nm and
500–20,000 nm diameters made at Maitri (70°45′52′
′S, 11°44′2.7′
′E; 130 m above mean sea level), Antarctica, on two days January 17 and February 18, 2005, with contrasting meteorological
conditions. In contrast to January 17, on February 18, winds were stronger from the morning to noon and lower from the noon
to evening, atmospheric pressure was lower, cloudiness was more, the land surface remained snow-covered after a blizzard on
February 16 and 17 and the airmass over Maitri, descended from an altitude of ~3 km after an excursion over ocean. On these
days mobility spectra showed two modes, corresponding to intermediate ions and light large ions and an indication of additional
one/two maxima for small/cluster ions and heavy large ions. The small ions generated by cosmic rays, and the nucleation mode
particles generated probably by photochemical reactions grew in size by condensation of volatile trace gases on them and produced
the cluster and intermediate ion modes and the Aitken particle mode in ion/particle spectra. Particles in the size range of
9–26 nm have been estimated to grow at the rate of 1.9 nm h − 1 on February 18, 2005. Both, ions and aerosol particles show bimodal size distributions in the 16–107 nm size range, and comparison
of the two size distributions suggests the formation of multiple charged ions. Attachment of small ions to particles in this
bimodal distribution of Aitken particles together with the formation of multiple charged ions are proposed to result in the
light and heavy large ion modes. Growth of the nucleation mode particles on February 18, 2005 is associated with the passage
of the airmass over ocean. In contrast, though the ion size distributions were not much different, the aerosol size distributions
did not show a dominant peak for the formation and growth of nucleation mode particles on January 17. More measurements are
needed before the conclusion of this case study is generalized. 相似文献
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Mokhov A. V. Kartashov P. M. Rybchuk A. P. Gornostaeva T. A. Bogatikov O. A. 《Doklady Earth Sciences》2018,478(1):112-114
Doklady Earth Sciences - Particles of tantalo–niobate of the ferrotantalite-manganotantalite series are discovered for the first time in two lunar regolith fragments delivered by the... 相似文献
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Cecilie Bjørlykke 《GeoJournal》1996,39(2):221-227
This paper analyses the meeting between the international petroleum industry and two local communities. The building of an oil terminal in a local community is both a major event, and a generator of processes on the local level. Three different angles is used to enlighten these processes; categorised as as place, people and mind. The place analysis consentrates on the effects on population and workforce development, the people analysis look at the institutional and planning processes, and the mind analysis the effects on the feeling of local identification. The paper demonstrates that local factors are of crucial importance even for the international petroleum industry. 相似文献
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江油市敬元乡新房村17社滑坡稳定性分析 总被引：1，自引：1，他引：0
在分析滑坡地质环境背景,平剖面形态、特征及其诱因的基础上,使用传递系数法计算滑坡体稳定系数.结果表明,天然工况下基本稳定,暴雨工况下欠稳定,地震工况下不稳定.并拟定抗滑桩及改河工程防治方案,以保证村庄和河道安全. 相似文献
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