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1.
2.
Gianluca Iezzi Mario Tribaudino Giancarlo Della Ventura Fabrizio Nestola Fabio Bellatreccia 《Physics and Chemistry of Minerals》2005,32(7):515-523
The synthetic amphibole Na0.95(Li0.95Mg1.05)Mg5Si8O22(OH)2 was studied in situ at high-T, using IR OH-stretching spectroscopy and synchrotron X-ray powder diffraction. At room-T the sample has P21
/m symmetry, as shown by the FTIR spectrum. It shows in the OH region two well-defined and intense absorptions at 3,748 and
3,712 cm−1, respectively, and two minor bands at 3,667 and 3,687 cm−1. The main bands are assigned to the two independent O–H groups in the primitive structure. The two minor bands evidencing
the presence of small amount of vacant A-site (A□0.05). With increasing T, these bands shift continuously and merge into a unique absorption at high temperature. A change as a function of increasing
T is revealed by the evolution of the refined unit-cell parameters, whose trend shows a transition to C2/m at about 320–330°C. The spontaneous scalar strain, fitted with a tricritical 2–6 Landau potential, gives a T
c of 325(10)°C (β parameter = 0.27). Comparison with the second-order P21
/m ⇔ C2/m phase transition at 255°C for synthetic amphibole ANa0.8B(Na0.8Mg1.2)CMg5Si8O22(OH)2 indicates that the substitution of Na with Li at the B-sites strongly affects the thermodynamic character and the T
c of the phase transition. The comparison of LNMSH amphiboles with cummingtonitic ones shows that the high-T thermodynamic behaviour is affected by A-site occupancy. 相似文献
3.
《Geoforum》2016
This paper introduces a unique industrial configuration that has emerged in Beijing, where three economic clusters in the biomedical industry, originally established as industrial/research parks, have developed parallel to each other. This configuration of multiple co-located clusters of the same industry, which has not been discussed before, raises the question of whether the industrial/research parks are competing for the same resources, or whether they are complementary to each other and can collectively be viewed as a new type of industrial configuration. The paper conceptualizes a framework of multiple clusters in mega-city regions that distinguishes between collaborating and competing clusters and presents initial empirical evidence for the Beijing case. As such, this research aims to unravel the phenomenon of multiple clusters in mega-city regions and to understand the complex spatial interrelationships that exist within and beyond multiple co-located clusters in the same industry. 相似文献
4.
Indicators of the economic performance of fishing vessels are frequently computed in various countries. In this paper, we use different types of information to assess capital value and the economic performance of fishing vessels. On the one hand, field surveys provide technical and financial information on the main components of fishing capital. On the other hand, book values are given in bookkeeping databases. We use both sources of information on fishing capital are used for the same set of vessels, namely the commercial fishing fleet of the French region of Brittany. Based on these two sources, measures of economic performance can be produced for the short term using gross surplus; and for the long term including the cost of capital. The measures of performance obtained are presented and the differences between them are then discussed. 相似文献
5.
海洋红藻多管藻内生真菌EN-22 的化学成分研究 总被引:4,自引:0,他引:4
对采自广西涠州岛近海多管藻(Poiysiphonia urceolata)分离到的一株内生真菌EN-22的次生代谢产物的化学成分进行了研究.利用正相硅胶柱层析、葡聚糖凝胶Sephadex LH-20柱层析、制备薄层层析(PTLC)以及重结晶等分离手段从该菌发酵液中分离得到15个化合物,通过一维、二维核磁共振技术、质谱技术等鉴定了所有化合物的结构,分别为:4-(4-喹啉)-4-羟基-2-丁酮(1),3-羟基-3-(2-氧丙基)吲哚-2-酮(2),3-吲哚乙醇(3),3-吲哚甲酸(4),2-羟基-3-吲哚丙酸(5),2-酮-3-吲哚乙醇(6),3,3-二吲哚-2-羟基-丙醇(7),β-咔啉(8),尿嘧啶(9),环-(S-脯氨酸-S-异亮氨酸)(10),(22E,24R)-3β,5α,9α-三羟基麦角甾-7,22-二烯-6-酮(11),(22E,24R)-5α,6α-环氧麦角甾-8,22-二烯-3β,7α-二醇(12),5α,6α-环氧-24(R)-甲基胆甾-7,22-二烯-3β-醇(13),胡萝卜苷(14),过氧化麦角甾醇(15);其中化合物1和2为新天然产物,并首次报道化合物1的碳谱数据. 相似文献
6.
Tiexin Gu Zhong Zhang Chunshu Wang Weidong Yan 《Geostandards and Geoanalytical Research》2001,25(1):153-158
Two types of gold deposit with both good homogeneity and a high-grade of gold were selected to prepare four gold ore reference materials (GAu-19,GAu-20,GAu-21 and GAu-22) by the Institute of Geophysical and Geochemical Exploration (IGGE),China.Seven laboratories participated in the certification programme. Volumetric methods for GAu19-21 and atomic absorption spectrometry for GAu-22 were used for the homogeneity testing,the coefficient of variation being found to be less than 3%.After sample digestion and preconcentration,the samples were analysed by flame atomic absorption spectrometry (AAS),colorimetry,neutron activation analysis (NAA)and volumetric analysis. The certified values for the gold concentration in GAu19-22 are 18.3 μg g -1, 32.3 μg g -1, 53.0 μg g -1 and 5.72 μg g -1,respectively. 相似文献
7.
Sylwia Grabowska Jerzy W. Mietelski Krzysztof Kozak Paweł Gaca 《Journal of Atmospheric Chemistry》2003,46(2):103-116
The Petryanov air filters combined into half-year sets were analyzed for the presence of 40K, 137Cs and 22Na by means of low-background gamma rays spectrometry. Each sample contains aerosols from more than 1 Mm3 of air. Samples were collected in ground level air at Kraków (Southern Poland) from 1996 to 2002. Activity concentrations of 40K are almost constant with the mean of 14.7± 4.5 Bq m–3. Activity concentrations of 137Cs, which are on the level of single Bq m– 3 show exponential decrease with effective half-life time of 7.07± 0.77 years. The cosmogenic 22Na shows a strong seasonal variation with significant different mean values activity concentration between 0.333± 0.095 Bq m–3 and 0.137± 0.045 Bq m–3, for summer and winter, respectively. Moreover, the activity ratio for two cosmogenic radionuclides: 22Na and measured previously 7Be show also changes with statistically significant seasonal differences. The lower values were found during winters. The mechanisms which might govern this ratio are discussed. The conclusion is that transport of 22Na during summer seems to be so much effective, that results in kind of relative depletion of stratosphere of this nuclide. 相似文献
8.
9.
《Climate Policy》2013,13(2):851-864
The clean development mechanism (CDM) under the Kyoto Protocol allows industrialized countries to use credits from greenhouse gas (GHG) abatement projects in developing countries. A key requirement of the CDM is that the emission reductions be real, measurable and additional. This article uses data from registered projects to evaluate the extent to which these objectives are met by projects that reduce hydrofluorocarbon-23 (HFC-23) emissions in the production of hydrochlorofluorocarbon-22 (HCFC-22). The data show that HCFC-22 plants produced significantly less HFC-23 during periods when no emission credits could be claimed compared with periods when HFC-23 destruction could be credited under the CDM. Moreover, the total amount of HCFC-22 produced appears to be determined mainly by CDM rules. This suggests that the claimed emission reductions may partly not be real and that the CDM provides perverse incentives to generate more HFC-23. The accelerated phase-out of HCFCs under the Montreal Protocol on Substances that Deplete the Ozone Layer could worsen this situation. To address these issues an ambitious emission benchmark for the baseline HFC-23 emissions is proposed. 相似文献
10.
We study the problem of critical inclination orbits for artificial lunar satellites, when in the lunar potential we include,
besides the Keplerian term, the J
2 and C
22 terms and lunar rotation. We show that, at the fixed points of the 1-D averaged Hamiltonian, the inclination and the argument
of pericenter do not remain both constant at the same time, as is the case when only the J
2 term is taken into account. Instead, there exist quasi-critical solutions, for which the argument of pericenter librates around a constant value. These solutions are represented by smooth
curves in phase space, which determine the dependence of the quasi-critical inclination on the initial nodal phase. The amplitude
of libration of both argument of pericenter and inclination would be quite large for a non-rotating Moon, but is reduced to
<0°.1 for both quantities, when a uniform rotation of the Moon is taken into account. The values of J
2, C
22 and the rotation rate strongly affect the quasi-critical inclination and the libration amplitude of the argument of pericenter.
Examples for other celestial bodies are given, showing the dependence of the results on J
2, C
22 and rotation rate. 相似文献