蜕壳促长素对斑节对虾、刀额新对虾蜕壳和生长的作用     

吴琴瑟  杨睿  刘翠红 《广东海洋大学学报》1996,(2)

在对虾人工配合饲料中添加蜕（脱）壳促长素，喂养斑节对虾（ＰｅｎａｅｕｓｍｏｎｏｄｏｎＦａｂｒｉｃｉｕｓ）和刀额新对虾（ＭｅｔａｐｅｎａｅｕｓｅｎｓｉｓＤｅＨａａｎ），观察其促进蜕壳、生长的作用。试验证明：饲料中添加不同浓度（０．５‰。、１．０‰、１．５‰）的蜕壳促长素，均不同程度地促进对虾的蜕壳和生长。添加浓度为１．５％。效果最为明显。值得在生产中应用。  相似文献   

Regression and Time Series Analysis of the World Oil Peak of Production: Another Look     

Peter Caithamer 《Mathematical Geosciences》2008,40(6):653-670

This paper analyzes world oil production data as a population/resource growth model. Both US and world oil production data are analyzed in terms of the logistic growth curve. It is shown that the logistic growth curve, while a suitable model for the American data, is not a suitable model for world oil production. A flexible family of curves which allows a wide range growth rates is considered. Using a nonlinear regression, one can predict various peak dates and total recoverable resources using different curves which all fit the data indistinguishably well.  相似文献   

Interaction of Freshly Precipitated Silica Gel with Aqueous Silicic Acid Solutions under Ambient and Near Neutral pH-conditions: A Detailed Analysis of Linear Rate Law     

Jiří Faimon  Martin Blecha 《Aquatic Geochemistry》2008,14(1):1-40

Interaction of freshly precipitated silica gel with aqueous solutions was studied at laboratory batch experiments under ambient and near neutral pH-conditions. The overall process showed excellent reversibility: gel growth could be considered as an opposite process to dissolution and a linear rate law could be applied to experimental data. Depending on the used rate law form, the resulting rate constants were sensitive to errors in parameters/variables such as gel surface area, equilibrium constants, Si-fluxes, and reaction quotients. The application of an Integrated Exponential Model appeared to be the best approach for dissolution data evaluation. It yielded the rate constants k _dissol ∼ (4.50 ± 0.68) × 10⁻¹² and k _growth ∼ (2.58 ± 0.39) × 10⁻⁹ mol m⁻² s⁻¹ for zero ionic strength. In contrast, a Differential Model gave best results for growth data modeling. It yielded the rate constants k _dissol ∼ (1.14 ± 0.44) × 10⁻¹¹ and k _growth ∼ (6.08 ± 2.37) × 10⁻⁹ mol m⁻² s⁻¹ for higher ionic strength (I ∼ 0.04 to 0.11 mol L⁻¹). The found silica gel solubility at zero ionic strength was somewhat lower than the generally accepted value. Based on the and standard Gibbs free energy of silica gel formation was calculated as and −850,318 ± 20 J mol⁻¹, respectively. Activation energies for silica gel dissolution and growth were determined as and respectively. An universal value for growth of any silica polymorph, is not consistent with the value for silica gel growth, which questions the hypothesis about one unique activated complex controlling the silica polymorph growth.  相似文献   

Models of thermal conductivity of crystalline rocks     

Alan M. Jessop 《International Journal of Earth Sciences》2008,97(2):413-419

A numerical model of a rock sample provides estimates of conductivity related to mineral content that are very close to estimates provided by previous models. For any given volumetric mineral content conductivity may vary slightly, depending on the crystal arrangement and the crystal size. Order of crystallisation of the minerals causes differences of conductivity of less than 2%. Crystal size from small to up to 75% of the sample size creates differences in conductivity of the sample of about 3%. Disagreement of calculated values based on surface point-count of mineral content with measured values of the samples is up to 35%, which is attributed to the inability of one surface to adequately represent the volumetric mineral content.  相似文献   

Emerald deposits and occurrences: A review   总被引：3，自引：0，他引：3  

L.A. Groat  G. Giuliani  D.D. Marshall  D. Turner 《Ore Geology Reviews》2008,34(1-2):87

Emerald, the green gem variety of beryl, is the third most valuable gemstone (after diamond and ruby). Although it is difficult to obtain accurate statistics, Colombia supplies most (an estimated 60%, worth more than $500,000,000 per year) of the world's emeralds. However there is speculation that the emerald mines in Colombia are becoming depleted. Brazil currently accounts for approximately 10% of world emerald production. Emeralds have also been mined in Afghanistan, Australia, Austria, Bulgaria, China, India, Madagascar, Namibia, Nigeria, Pakistan, South Africa, Spain, Tanzania, the United States, and Zimbabwe.Because it is difficult to obtain accurate analyses of beryllium, most published analyses of beryl are renormalized on the basis of 18 oxygen and 3 Be atoms per formula unit. The color of emerald is due to trace amounts of chromium and/or vanadium replacing aluminum at the Y site; in most cases the Cr content is much greater than that of V. To achieve charge balance, the substitution of divalent cations at the Y site is coupled with the substitution of a monovalent cation for a vacancy at a channel site.Beryl is relatively rare because there is very little Be in the upper continental crust. Unusual geologic and geochemical conditions are required for Be and Cr and/or V to meet. In the classic model, Be-bearing pegmatites interact with Cr-bearing ultramafic or mafic rocks. However in the Colombian deposits there is no evidence of magmatic activity and it has been demonstrated that circulation processes within the host black shales were sufficient to form emerald. In addition, researchers are recognizing that regional metamorphism and tectonometamorphic processes such as shear zone formation may play a significant role in certain emerald deposits.A number of genetic classification schemes have been proposed for emerald deposits. Most are ambiguous when it comes to understanding the mechanisms and conditions that lead to the formation of an emerald deposit. Studies of individual emerald deposits show that in most cases a combination of mechanisms (magmatic, hydrothermal, and metamorphic) were needed to bring Be into contact with the chromophores. This suggests the need for a more flexible classification scheme based on mode of formation. Stable isotopes can be used to estimate the contribution of each mechanism in the formation of a particular deposit. Such estimates could perhaps be more precisely defined using trace element data, which should reflect the mode of formation.Emerald may be identified in the field by color, hardness, and form. It will tend to show up in stream sediment samples but because its specific gravity is relatively low, it will not concentrate in the heavy mineral fraction. In Colombia, structural geology, the sodium content of stream sediment samples, and the lithium, sodium, and lead contents of soil samples have all been used to find emerald occurrences. Exploration for gem beryl could result in the discovery of new occurrences of non-gem beryl or other Be minerals that could become new sources of Be and Be oxide.Future efforts should go towards creating a comprehensive data base of emerald compositions (including trace elements), determination of the role of metamorphism in the formation of some emerald deposits, improved classification schemes, and more effective exploration guidelines.  相似文献   

The Campanian Ignimbrite (southern Italy) geochemical zoning: insight on the generation of a super-eruption from catastrophic differentiation and fast withdrawal   总被引：2，自引：2，他引：0  

Lucia Pappalardo  Luisa Ottolini  Giuseppe Mastrolorenzo 《Contributions to Mineralogy and Petrology》2008,156(1):1-26

More than ca 100 km³ of nearly homogeneous crystal-poor phonolite and ca 100 km³ of slightly zoned trachyte were erupted 39 ka during the Campanian Ignimbrite super eruption, the most powerful in the Neapolitan area. Partition coefficient calculations, equilibrium mineral assemblages, glass compositions and texture were used to reconstruct compositional, thermal and pressure gradients in the pre-eruptive reservoir as well as timing and mechanisms of evolution towards magma chamber overpressure and eruption. Our petrologic data indicate that a wide sill-like trachytic magma chamber was active under the Campanian Plain at 2.5 kbar before CI eruption. Thermal exchange between high liquidus (1199°C) trachytic sill and cool country rocks caused intense undercooling, driving a catastrophic and fast (10² years) in situ fractional crystallization and crustal assimilation that produced a water oversaturated phonolitic cap and an overpressure in the chamber that triggered the super eruption. This process culminated in an abrupt reservoir opening and in a fast single-step high decompression. Sanidine phenocrysts crystal size distributions reveal high differentiation rate, thus suggesting that such a sill-like magmatic system is capable of evolving in a very short time and erupting suddenly with only short-term warning.  相似文献   

Red micas from basal ignimbrites of Mt. Vulture (Italy): interlayer content appraisal by a multi-methodic approach     

Fernando Scordari  Emanuela Schingaro  Gennaro Ventruti  Maria Lacalamita  Luisa Ottolini 《Physics and Chemistry of Minerals》2008,35(3):163-174

The crystal chemistry of red phlogopites from Mt. Vulture (Italy) ignimbrites has been studied by electron microprobe, secondary ion mass spectrometry (SIMS), single crystal structural investigation and Fourier transform infrared (FTIR) spectroscopy. The analysed phlogopite has Fe/(Fe + Mg) ∼ 0.35, TiO₂ (wt%): 2.8–5.0 and H₂O (wt%): 1.24–3.37. Infrared spectra revealed the presence of bands due to the NH₄⁺ and H₂O stretching and bending vibrations. The samples belong to the 1M polytype. The bimodal behaviour of several structural parameters allows red micas to be clustered into two distinct groups: K⁺ ↔ NH₄⁺, H₂O and M³⁺-vacancy substitutions dominate in the first group; M^3+,4+-oxy, in the second group. It has to be pointed out that quantitative analysis of hydrogen (via SIMS) together with the characterization of the local environment of the anionic site (via FTIR) are fundamental in assessing the correct structural formula and the substitution mechanisms in micas. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.  相似文献   

中国铂族元素矿床类型和地质特征   总被引：18，自引：2，他引：18  

梁有彬  李艺 《矿产与地质》1997,11(3):145-151

根据成矿地质环境、容矿岩石类型、元素共生组合、矿床地质特征和成矿作用性质，将我国的铂族元素矿床划分为岩浆型、热液弄才外生型三大类型和九个亚类，而赋存于基性超基性岩体中的铜镍型铂族元素矿床是我国最重要的铂族元素矿床。  相似文献   

An index to assess maritime importance in the European Atlantic economy     

《Marine Policy》2016

Successive marine policies set by the European Union identify the maritime sectors as crucial drivers for growth and jobs in the EU economy. The design of marine policies and the assessment of the importance of the maritime economy need empirical support that provides the basic data to help the decision-making process. This paper proposes a metric, in the form of a synthetic index, to measure and compare the importance of the maritime sectors in the European Atlantic area. The index scores can be used to assess the position of each Atlantic region so that it is possible to compare its performance to the rest of the area. The results show the relative weight of the maritime sectors in the European Atlantic regions and the high heterogeneity among them. Analyzing the maritime economy with this index can provide guidance for the design of economic policies to identify and revitalize the regions with greater potential for Blue Growth in the Atlantic area. This may help to put into perspective the importance of the maritime economy and can serve to improve the socio-economic dimension of the use of marine waters.  相似文献   

合浦珠母贝代谢产物对异枝麒麟菜生长的促进作用   总被引：3，自引：1，他引：3  

吴汪黔生  钱培元  高洪峰  丁美丽  吴超元  谢玉坎  张偲 《海洋与湖沼》1997,28(5):453-457

于１９９５年４月间在海南省三亚市、陵水县分别采集合浦珠母贝和异枝麒麟菜并进行混养实验，测定贝释放的三氮（ＮＨ４－Ｎ，ＮＯ３－Ｎ，ＮＯ２－Ｎ）以及藻类对贝释放的三氮的吸收及其生长，在期探讨合浦珠母贝代谢产物促进异枝麒麟菜生长的原因。结果表明，贝释放物中以ＮＨ４－Ｎ为主，ＮＯ３－Ｎ次之，ＮＯ２－Ｎ含量较少；藻对三氮的吸收 依此顺序递减。实验组藻体的生长速率明显高于对照组的，在模拟实验组中，通过加入无机  相似文献